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The present invention relates to a device and method for measuring supercritical carbon dioxide fracturing fluid throttling coefficient under different viscosities. The device for measuring supercritical carbon dioxide fracturing fluid throttling coefficient under different viscosities comprises a supercritical carbon dioxide fracturing fluid throttling coefficient measurement system and a supercritical carbon dioxide fracturing fluid viscosity adjustment apparatus; the supercritical carbon dioxide fracturing fluid throttling coefficient measurement system determines throttling coefficient of a high temperature and high pressure supercritical carbon dioxide fracturing fluid, and the supercritical carbon dioxide fracturing fluid viscosity adjustment apparatus determines viscosity of the high temperature and high pressure supercritical carbon dioxide fracturing fluid.


Patent
China University of Petroleum - East China | Date: 2015-05-07

A device for evaluating the foaming property of a gas-soluble surfactant, which comprises a gas source part, an evaluating kettle, a liquid part, and an intermediate container part. By means of the rotation of the evaluating kettle, the gas-soluble surfactant and the supercritical carbon dioxide can be sufficiently and evenly mixed with each other when the solubility of the gas-soluble surfactant in the supercritical carbon dioxide is measured.


Patent
China University of Petroleum - East China | Date: 2016-09-20

The present invention relates to offshore oil and gas exploration drilling field and, in particular, to a surface layer conductor running tool for deep-water well drilling, which is used to run a conductor to a designated position, so that the drill stem can be released and the drilling can be continued. The surface layer conductor running tool for deep-water well drilling comprises a mandrel, an inner sleeve, an outer sleeve, and a main body, wherein the inner sleeve, the outer sleeve, and the main body are fitted over the mandrel sequentially; the inner sleeve can slide up and down but cannot rotate in relation to the mandrel, the outer sleeve and the inner sleeve are connected via a transmission thread pair, and the main body is situated on the inner sleeve; a retaining pawl penetrating the main body and radially slidable in horizontal direction; and an anti-rotation pin penetrating the main body and the outer sleeve, so that the outer sleeve can move up and down in the main body only, but cannot rotate.


Zhang X.,China University of Petroleum - East China | Zhao X.,China University of Petroleum - East China | Jiang Z.,Shanghai University of Finance and Economics | Shao S.,Shanghai University of Finance and Economics
Global Environmental Change | Year: 2017

The Chinese government actively follows the low-carbon development pattern and has set the definite targets of reducing carbon emissions by 2030. The industrial sector plays a significant role in China's economic growth and CO2 emissions. This is the first study to present a specific investigation on the retrospective decomposition (1993–2014) and prospective trajectories (2015–2035) of China's industrial CO2 emission intensity (ICEI) and industrial CO2 emissions (ICE), aiming at China Industrial Green Development Plan 2016–2020 targets and China's 2030 CO2 emission-reduction targets. We introduce process carbon intensity, investment and R&D factors into the decomposition model and make a combination of dynamic Monte Carlo simulation and scenario analysis to identify whether and how the targets would be realized from a sector-specific perspective. The results indicate that investment intensity is the primary driver for the increase in ICEI, while R&D intensity and energy intensity are the leading contributors to the reduction in ICEI. Under existing policies, it is very possible for the industrial sector to achieve the 2020 and 2030 intensity-reduction targets. However, the realization of 2030 emission-peak target has some uncertainties and needs extra efforts in efficiency improvement and structural adjustment. All the five scenarios would achieve the 2020 and 2030 intensity-reduction targets, except Scenario N4 for China Industrial Green Development Plan 2016–2020 target. Nonetheless, only three scenarios would realize the 2030 emission-peak target. With strong efficiency improvement and structural adjustment, ICE would hit the peak in 2025. In contrast, with high/low efficiency improvement and weak structural adjustment, ICE would fail to reach the peak before 2035. Both ICEI and ICE have substantial mitigation potentials with the enhancement of efficiency improvement and structural adjustment. Finally, we suggest that the Chinese government should raise the baseline requirements of efficiency improvement and structural adjustment for the industrial sector to achieve China's 2030 targets. © 2017 Elsevier Ltd


Wang Q.,China University of Petroleum - East China | Jiang X.-T.,Xinjiang Institute of Ecology and Geography | Jiang X.-T.,University of Chinese Academy of Sciences | Li R.,China University of Petroleum - East China
Energy | Year: 2017

As a major contributor to carbon dioxide emissions, the electric power sector has instigated significant changes in environmental issues. To show the effectiveness of the program, research on whether the changes of electricity production and CO2 emissions are out of sync are conducted by applying a decoupling elasticity analysis method. Then the decoupling index from the electricity analysis on the basis of the extended multilevel LMDI method are applied to study Shandong Province, covering the period from 1995 to 2012. Finally, a comparative decoupling stability analysis is applied. Our results indicate electricity output and coal consumption play significant roles in determining levels of CO2 emissions. Also, “relative decoupling” and “no decoupling” were the main states during the study period. We also found that the decoupling index performed better (in terms of stability) than did the electricity output elasticity of CO2 emission. © 2017 Elsevier Ltd


Wang Y.,China University of Petroleum - East China
Drilling Fluid and Completion Fluid | Year: 2016

Carbonate rock reservoirs have plenty of micro fractures. Unidirectional fingering of acid solution in acidizing carbonate reservoirs always results in difficulties in communicating fractures and low efficiency of acidizing fracturing job. To improve the job efficiency, a new high performance diverting acid, which is sensitive to CO2, has been developed. The diverting acid has a formulation as follows: 3.96%SDS+1.09% MPDA+24% HCl+0.5% Z-1 (a corrosion inhibitor). This acid, although not viscoelastic, can acquire viscoelasticity through the reaction of TMPDA with SDS at the presence of CO2, because the reaction of TMPDA with SDS produces a surfactant Gemini which had superior viscoelasticity. The diverting acid resumed its original state as soon as CO2 disappeared. Laboratory study has shown that this diverting acid had good high temperature stability, good shearing performance, and superior diverting ability. In core experiment, several groups of cores were displaced with the new diverting acid. It was found that the permeability of the acid-flooded cores increased remarkably, even after removing the biggest permeability increases of two groups of cores. The efficiency of acidizing fracturing job can be improved with the new diverting acid, and recycling of the diverting acid may also be realized. © 2016, The Editorial Board of Drilling Fluid & Completion Fluid. All right reserved.


Dong Y.,China University of Petroleum - East China
Proceedings - 2016 10th International Conference on Complex, Intelligent, and Software Intensive Systems, CISIS 2016 | Year: 2016

There are many illegal memory access (IMA) defects in C programs, for example, null pointer dereference, buffer overflow and array out of bounds. When C programs are running, these defects may cause software failure, and may lead to serious consequences. In order to fully detect these IMA defects, we apply abstract regions to simulate memory blocks that allocated to memory objects at the runtime, and use the region-based model to describe memory states of each program point based on the result of dataflow analysis. Based on the region-based model, the determining criterion of IMA defects is introduced for detecting these defects. The method has been implemented in the defect detection tool DTSC, and 5 open source projects are tested, the test results show the validity of our method. © 2016 IEEE.


Wang F.,China University of Petroleum - East China | Li Z.,China University of Petroleum - East China | Chen H.,China University of Petroleum - East China | Zhang X.,China University of Petroleum - East China
RSC Advances | Year: 2017

The evaluation and simulation of foam-based materials are still matters of significant debate, despite the large number of available studies, due to the excellent properties of foam and its successful applications, especially in oil and gas field development. The properties of foam are substantially determined as a result of a dynamic structure, however few studies have been reported which investigate and perform measurements related to such a structure. In this work, a new model based on fractal theory is proposed for the simulation of aqueous foam. As a first step, the fractal characteristics of foam are confirmed using image processing and calculations. Accordingly, the foam structure is quantitatively studied by defining and calculating the foam fractal dimensions. Secondly, a foam structure evolution model is established, which reveals that the evolutional trend of the fractal dimensions of foam is non-linear with the changing of time, following an exponential equation. The model is then validated and a sensitivity analysis is also carried out. Finally, the applications of this model to the evaluation of foaming agents and the prediction of foam structures are discussed. These results are expected to be helpful for further understanding the dynamic characteristics of foam fluids and their advanced applications. © The Royal Society of Chemistry.


Wang B.,China University of Petroleum - East China | Froment G.F.,Texas A&M University
Catalysis Letters | Year: 2017

Abstract: The dehydrogenation of cyclohexane on Pt (111) single crystal was investigated in a bulb reactor. The volume expansion associated with the dehydrogenation of cyclohexane into benzene causes a total pressure change which was used as an index of the extent of the reaction. The validity of this reactor for kinetic studies was tested by means of CO oxidation. The dehydrogenation of cyclohexane is a reversible reaction. High temperature is favorable for dehydrogenation. By switching the temperature, the cycles of cyclohexane dehydrogenation and benzene hydrogenation were observed in this bulb reactor. The formation of carbonaceous deposits on Pt(111) surface caused a progressive loss of total pressure during the reaction cycle. A Hougen-Watson model was used to model the dehydrogenation of cylohexane on Pt(111) single crystal in the absence of deactivation. The model parameters were statistically significant and satisfied the physicochemical criteria. Graphical Abstract: [Figure not available: see fulltext.] © 2017 Springer Science+Business Media New York


Li Z.,China University of Petroleum - East China | Wang Y.,China University of Petroleum - East China | Chen Y.,China University of Petroleum - East China | Wu M.,China University of Petroleum - East China
RSC Advances | Year: 2017

Nanocomposites containing Mn3O4 and MnOOH dual-nanocrystals on N-doped graphene sheets were prepared using a solvothermal method. Nanostructure and rate of dual-nanocrystals in the composites can be adjusted, having effects on their electrochemical performance. The nanohybrid NG-36 is composed of 1D MnOOH nanowires, Mn3O4 nanotetragonals and electroconductive N-doped graphene matrix. Experimental data for NG-36 reveals a high rechargeable specific capacity of 341.5 mA h g-1 at a current density 3 A g-1 after 500 cycles, resulting from synergetic effects among the components. © 2017 The Royal Society of Chemistry.


Liu J.,CAS Dalian Institute of Chemical Physics | Liu J.,China University of Petroleum - East China | Leng J.,CAS Dalian Institute of Chemical Physics | Wu K.,CAS Dalian Institute of Chemical Physics | And 2 more authors.
Journal of the American Chemical Society | Year: 2017

Two-dimensional (2D) organolead halide perovskites are promising for various optoelectronic applications. Here we report a unique spontaneous charge (electron/hole) separation property in multilayered (BA)2(MA)n-1PbnI3n+1 (BA = CH3(CH2)3NH3 +, MA = CH3NH3 +) 2D perovskite films by studying the charge carrier dynamics using ultrafast transient absorption and photoluminescence spectroscopy. Surprisingly, the 2D perovskite films, although nominally prepared as "n = 4", are found to be mixture of multiple perovskite phases, with n = 2, 3, 4 and ≈ ∞, that naturally align in the order of n along the direction perpendicular to the substrate. Driven by the band alignment between 2D perovskites phases, we observe consecutive photoinduced electron transfer from small-n to large-n phases and hole transfer in the opposite direction on hundreds of picoseconds inside the 2D film of ∼358 nm thickness. This internal charge transfer efficiently separates electrons and holes to the upper and bottom surfaces of the films, which is a unique property beneficial for applications in photovoltaics and other optoelectronics devices. © 2017 American Chemical Society.


Li X.,China University of Petroleum - East China | Liu S.,China University of Petroleum - East China | Wang Y.,China University of Petroleum - East China
IEEE Transactions on Applied Superconductivity | Year: 2017

This paper proposes a new stator high-temperature superconducting (HTS) field-modulated machine with the merit of high torque density for direct-drive applications, which incorporates the attractive features of both stator excitation HTS machine and field-modulated machine. The key is to artfully place the HTS windings on the stator to implement static seals as well as utilizing the "magnetic gearing effect" to achieve high torque capability. Based on the geometry of the fabricated double-layer Dewar assembly for cooling the HTS excitation coil, the proposed machine is initially designed. By using the finite element analysis (FEA), the machine performances are analyzed, and its validity is verified. © 2017 IEEE.


Li X.,China University of Petroleum - East China | Liu S.,China University of Petroleum - East China | Wang Y.,China University of Petroleum - East China
IEEE Transactions on Applied Superconductivity | Year: 2017

This paper proposes a new high-Temperature superconductor (HTS) dual-rotor flux-switching machine for direct-drive wind energy conversion. The key is to adopt dual-rotor structure to improve utilizations of the HTS excitation field and the machine space, thus achieving a high power density. Also, the HTS excitation can easily achieve flexible flux regulation to keep armature voltage constant under time-varying wind speeds. The operation principle, with emphasis on the effect of relative position of both rotors on the magnetic circuits, is described in details. And the initial machine design, especially the split ratio optimization, has been done. By using the finite element analysis, the machine performances are analyzed, and its validity is verified. © 2002-2011 IEEE.


Ma X.,China University of Petroleum - East China | Cao Z.,China University of Petroleum - East China | Liu W.,China University of Petroleum - East China
IEEE International Conference on Data Mining Workshops, ICDMW | Year: 2017

With the rapid development of Internet technology and smart devices, tremendous amounts of multimedia data (e.g.Text, image, video, audio, etc.) are produced and uploaded online every day. Semi-supervised learning has been proved to be one effect and effective solution to manage the massive emerging multimedia, which usually leverages the performance by exploiting the local geometry of a small number of labelled and a large number of unlabeled samples. The representative local structure preserving methods include manifold regularization and pairwise constraints. In this paper, we propose a local structure preserving method that effectively integrates manifold regularization and pairwise constraints. Particularly, we construct a new graph Laplacian by combining the traditional Laplacian and pairwise constraints. The new graph Laplacian can better preserve the local geometry and then further boost the performance. Finally, we build new local structure preserving classifiers including kernel least squares and support vector machines. We conduct extensive experiments on Chinese Academy of Sciences-Yunnan University-Multimodal Human Action Database (CAS-YNU-MHAD) for action recognition, respectively. The experimental results demonstrate that the proposed algorithm outperforms the baseline algorithms. © 2016 IEEE.


Wu Z.,China University of Petroleum - East China
International Journal of Simulation: Systems, Science and Technology | Year: 2016

We focus on modeling and controller design for a networked control system with uncertain time delay. In addition to structure of the networked control system, other causes of time delay existing in actual engineering have also been taken into account, such as unknown disturbance, modeling error and direct action of system input on system output. An improved quantum-behaved particle swarm optimization (IQPSO) algorithm is proposed to optimize quantification factors and scaling factors of the fuzzy controller of the networked control system (NCS) for which traditional experiences and methods are inapplicable. In the IQPSO algorithm, disadvantages of QPSO algorithm in its population diversity and premature convergence are overcome by introducing search operators of ABC algorithm into the QPSO algorithm as mutation operators. Optimization of the fuzzy controller is realized by taking ITAE indices as a fitness function of IQPSO algorithm. Our simulation results show the robust controller design method proposed here is superior in: i) it is free from limitations of the duration of time delay which may be longer or shorter than a sampling period, ii) no need to conform to certain known random distribution, iii) effectiveness in improving stability and control accuracy of the networked control system. © 2017, UK Simulation Society. All rights reserved.


Tang M.,China University of Petroleum - East China | Zhao H.,Research Institute of Petroleum Exploration & Development of Jilin OilfieldJilin | Ma H.,China University of Petroleum - East China | Lu S.,China University of Petroleum - East China | Chen Y.,Research Institute of Petroleum Exploration & Development of Jilin OilfieldJilin
Fuel | Year: 2017

A poro-elasticity reservoir simulation model was developed to analyze the huff-n-puff operations in the Fuyu continental tight oil layer. The model was based on the “two-way” coupling of a geomechanical model and a compositional model. The pressures induced from the compositional model were set as input for the geomechanical model, and the effective stresses calculated from the geomechanical model were set as input for the compositional model. The results show that under specific assumptions, effective stress increases during the depletion and production period and decreases during the injection and soaking period, resulting in corresponding changes to the displacement and effective stress. Biot coefficient also has a significant and systematic influence on the resulting oil recovery factor of CO2 huff-n-puff. In addition, a sensitivity analysis of the injection parameters, including injection timing, production time, and soaking time, was performed in detail. This work provides a better understanding of the mechanisms of the CO2 huff-n-puff operations of horizontal wells in a continental tight oil sandstone formation. © 2016 Elsevier Ltd


Yin C.,China University of Petroleum - East China | Wang Y.,China University of Petroleum - East China
Korean Journal of Chemical Engineering | Year: 2017

Oxidic unsupported Ni-Mo-W catalysts were chosen to elucidate the effect of sulfidation conditions on the catalytic performance. The catalysts were sulfided in situ by using dimethyl sulfide as sulfiding agent. The relationships between the time needed for sulfidation and the sulfiding conditions were studied by GC-analysis method. Straight-run gas oil with high sulfur and nitrogen content was used to evaluate the hydrotreating performance. The oxidic catalyst precursors and sulfided catalysts were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectroscopy (XPS). With increasing sulfiding liquid hourly space velocity (LHSV) of the sulfiding agent, the reaction time necessary for the sulfidation decreased, while the activity of the catalyst increased significantly. The higher catalytic activity might be due to the MoS2/WS2 slabs with shorter length and higher stacking number, which might contribute to the catalyst with more active sites. Sulfiding at 330 °C took the longest sulfidation time, while the catalytic activity was also the highest after sulfiding at this temperature. Furthermore, within a certain range, the sulfidation pressure had no evident effect on the catalytic behavior or activity. The purpose of this work was to provide a basis for actual production and a reference for further research. © 2017, Korean Institute of Chemical Engineers, Seoul, Korea.


Lin Y.,China University of Petroleum - East China | Pan Y.,China University of Petroleum - East China | Pan Y.,Tsinghua University | Zhang J.,China University of Petroleum - East China
Electrochimica Acta | Year: 2017

How to enhance the catalytic performance of electrocatalyst for the hydrogen evolution reaction (HER) is the main focus among many researches. In this work, an efficient hybrid composed of CoP nanorods (NRs) and N, P co-doped carbon flakes (NPCFs) which were synthesized by direct pyrolysis of the mixture of biomass macromolecule sodium alginate and ammonium hypophosphite was constructed. The as-synthesized CoP/NPCFs hybrid catalyst exhibits efficient electrocatalytic activity with a low onset overpotential (45 mV), small Tafel slope (67 mV dec−1), high exchange current density (1.37 × 10−3 mA cm−2), large electrochemical double-layer capacitance (9.25 mF cm−2) and good stability for HER in 0.5 M H2SO4 solution. The good HER electrocatalytic performance derived from the more defects and active sites in the catalyst as well as the strong synergetic effect between NPCFs and CoP NRs. This study opens a door for designing low-cost transition metal phosphide catalysts decorated heteroatom doped carbon materials for water splitting. © 2017 Elsevier Ltd


Song M.,Guangdong University of Technology | Song M.,Hong Kong Polytechnic University | Gong G.,Hunan University | Mao N.,China University of Petroleum - East China | And 2 more authors.
Applied Energy | Year: 2017

Air source heat pump units could efficiently recover low grade waste heat from ambient air for indoor air heating or hot water supplying, which makes them widely applied in recent decades. For a vertically installed multi-circuit outdoor coil, a reverse cycle defrosting operation is always used to solve its frosting problem at high humidity and cold climate. Reverse cycle defrosting operation is terminated when the tube surface temperature at exit of the lowermost circuit reaching a pre-set value. It is obviously that when the pre-set temperature is higher or lower, the defrosting duration would be prolonged or more residual water left, respectively. Both of them result in potential energy waste for an air source heat pump unit, or even adversely degrade the indoor thermal comfort. However, as reported, a wide range of 10-35. °C was used as the pre-set defrosting termination temperature, without a fixed value or range given. To save energy for an air source heat pump unit, in this paper, an experimental methodology was firstly presented. Then, an air source heat pump unit with three-circuit outdoor coil was specially selected, and experimental investigation conducted. Finally, the defrosting termination temperature was concluded suitable at 20-25. °C, around 22. °C for this study. This methodology makes contributions to the control strategy optimization and energy saving for air source heat pump units. © 2017 Elsevier Ltd.


Li H.,China University of Petroleum - East China | Yu S.,China University of Petroleum - East China
Journal of Alloys and Compounds | Year: 2017

In this work, a Cu[sbnd]Zn coating with dandelion-like CuO microstructure was fabricated on pipeline steel surface by a simple two-step combined method of electrodeposition and chemical oxidation. This coating was then coated with a thin pentadecafluorooctanoic acid to achieve superhydrophobic, with the contact angle of water about 156.81° and the sliding angle around 3°. When a water droplet contacted on the Cu[sbnd]Zn coating surface, the dandelion-like CuO microstructure was seen as the dual-scale structure that was proposed to be composed of spherical and pillared microstructures. Based on the Wenzel's and Cassie's formulas, the theoretical explanation was used to confirm the Cassie-Cassie wetted state between water droplet and the dandelion-like hierarchical superhydrophobic coating according to the geometric parameters of the surface morphology. Meanwhile, the superhydrophobic Cu[sbnd]Zn coating had the ability to repel the impinging water droplets and excellent long-term, thermal, solution immersion and chemical stability. Such robust superhydrophobic Cu[sbnd]Zn coating with hierarchical microstructures was expected to have various potential applications in our daily life. © 2016 Elsevier B.V.


Wang Z.,China University of Petroleum - East China | Wang J.,China University of Petroleum - East China | Jiang W.,China University of Petroleum - East China | Feng Q.,Xi'an Jiaotong University
Applied Thermal Engineering | Year: 2017

In the single screw refrigeration compressor (SSRC), the capacity control mechanism is normally employed to meet the actual required cooling capacity under different load conditions. In this paper, theoretical calculation models describing the working process of the SSRC with the single slide valve capacity control mechanism (SVCCM) and SSRC with the frequency conversion regulating mechanism (FCRM) are established to research the thermal dynamic characteristics for variable load SSRC under part-load conditions. Experimental investigation on a SSRC under part-load conditions is also carried out to verify the theoretical calculation models. By using these validated models, the thermodynamic performances and dynamic characteristics of the SSRC with different capacity control mechanism under part-load conditions have been analyzed and compared. Through the comparison, the economical efficiency and reliability of the SSRC with different capacity control mechanism were obtained. All of these works can provide the basis for the later optimization design for the variable load single screw refrigeration compressor. © 2016 Elsevier Ltd


Jiang Y.,China University of Petroleum - East China | Wang Y.,China University of Petroleum - East China
International Conference on Signal Processing Proceedings, ICSP | Year: 2017

In this paper, we propose a novel multiple categories classification approach based on the Bayesian decision classification method using the dense SIFT feature. First, the dense scale invariant feature transform (SIFT) feature for each image belonging to various categories is extracted as image representation. Second, the statistical models for multiple categories are established by estimating the conditional PDFs (probability density functions). Each category is modeled to follow the multivariate normal distribution, respectively. Finally, we classify the probe images to the category with the maximum posterior probability under the Bayesian framework. Experimental results on three databases demonstrate the performance of the proposed method. © 2016 IEEE.


Qiu Z.,China University of Petroleum - East China | Xue C.,China University of Petroleum - East China | Wang Y.,China University of Petroleum - East China
International Conference on Signal Processing Proceedings, ICSP | Year: 2017

It is a pervasive problem that recognizing the relationship between structural connectivity detected by diffusion tensor imaging (DTI) and functional connectivity obtained from resting state functional magnetic resonance imaging (rs-fMRI) in human brain mapping. Current experimental studies indicate that functional connectivity and structural connectivity relate with each other. Furthermore, functional connection can be used to discover the links of two brain hemispheres, hard to detect with technological means such as diffusion tensor imaging, which motivates many studies to establish computational models. Here, we propose a method based on network deconvolution for inferring structural connectivity from resting-state functional connectivity, assuming that the correlation of functional connectivity are generated by the sum of one and two-step structural paths. We apply the method to a 90-ROI database and a 998-ROI database respectively, and the performance of the method is tested with ROC curves. © 2016 IEEE.


Feng X.,China University of Petroleum - East China | Wang Y.,China University of Petroleum - East China | Liu B.-D.,China University of Petroleum - East China
International Conference on Signal Processing Proceedings, ICSP | Year: 2017

Classification algorithms based sparse coding have formed a mature system for visual recognition. Recent studies suggest collaborative representation is a much more effective method for classification, compared with sparse representation, the objective function of collaborative representation is constrained by ℓ2-norm. Traditional collaborative representation based classification always uses a set of training samples to construct a dictionary directly, which causes high residual error and thus reduces the correct rate of classification. To handle the problem, we propose an innovative method, which integrates centralized image coding and class specific dictionary learning algorithm with collaborative representation based classification together, namely class specific centralized dictionary learning based collaborative representation (CSCDL-CRC). Meanwhile, kernel method can obtain nonlinear information between data points through mapping feature space to kernel space, especially when it is applied to image classification. We extended our proposed CSCDL-CRC to the kernel space to improve the classification performance. We make plenty of experiments on three frequently-used fine-grained image datasets, including Caltech-UCSD Birds-200-2011 (CUB-200-2011) dataset, Oxford 102-Flowers dataset and Stanford Dogs dataset, to validate the effectiveness of the proposed approach. © 2016 IEEE.


Zhou Y.,China University of Petroleum - East China | Zhou Y.,Marquette University | Yang S.,Marquette University | Huang J.,Marquette University
Physical Chemistry Chemical Physics | Year: 2017

In this work, we report a new photocatalytic system that links multifunctional semiconductor nanocrystals with emerging water-soluble molecular catalysts made of earth-abundant elements for H2 generation [Ni(P2 RN2 R′)2(BF4)2]4-, R = Ph, R′ = [PhSO3]- (NiS). This noble metal free hybrid exhibits remarkable catalytic activity with a turnover number of 511 for H2 production and a photon-to-H2 conversion efficiency of 12.5%. The mechanistic insight into such high efficiency in this photocatalytic system was examined using a combination of steady-state emission and time-resolved absorption spectroscopy. © the Owner Societies 2017.


Zhang L.,China University of Petroleum - East China | Zhang L.,Circle Technology | Zhao X.,China University of Petroleum - East China | Yan X.,China University of Petroleum - East China | Yang X.,China University of Petroleum - East China
International Journal of Geomechanics | Year: 2017

A two-dimensional elastoplastic analytical model of stress-strain analysis of the pipeline under strike-slip faults was established based on the plastic flow theory and elastoplastic-beam theory, considering the effects of service loads and the nonlinearities of the pipeline and the pipe-soil interaction. According to the plastic flow theory, the axial, radial, and hoop plastic strains were derived, and the stress-strain relation was established under the plane stress state. The axial stress and strain of the pipeline induced by fault displacements were analyzed based on the elastoplastic beam theory. Additionally, the axial stresses, hoop stresses, and strains induced by the service loads (i.e., the internal pressure and the temperature variation) were also considered. The proposed model was verified by comparing the analytical results and the finite-element results. The results show that the proposed model can predict accurately the mechanical response of the pipeline subjected to strike-slip fault displacements, with minor deviations of within 10%. © 2016 American Society of Civil Engineers.


Cai B.,China University of Petroleum - East China | Cai B.,City University of Hong Kong | Zhao Y.,China University of Petroleum - East China | Liu H.,City University of Hong Kong | Xie M.,City University of Hong Kong
IEEE Transactions on Power Electronics | Year: 2017

Permanent magnet synchronous motor and power electronics-based three-phase inverter are the major components in the modern industrial electric drive system, such as electrical actuators in an all-electric subsea Christmas tree. Inverters are the weakest components in the drive system, and power switches are the most vulnerable components in inverters. Fault detection and diagnosis of inverters are extremely necessary for improving drive system reliability. Motivated by solving the uncertainty problem in fault diagnosis of inverters, which is caused by various reasons, such as bias and noise of sensors, this paper proposes a Bayesian network-based data-driven fault diagnosis methodology of three-phase inverters. Two output line-to-line voltages for different fault modes are measured, the signal features are extracted using fast Fourier transform, the dimensions of samples are reduced using principal component analysis, and the faults are detected and diagnosed using Bayesian networks. Simulated and experimental data are used to train the fault diagnosis model, as well as validate the proposed fault diagnosis methodology. © 1986-2012 IEEE.


Li C.,Beijing University of Technology | Zhang F.,China University of Petroleum - East China
Geophysics | Year: 2017

In prestack seismic data, outlier errors occur and can negatively influence the outcome of the amplitude-versus-angle (AVA) inversion process. Hence, their effect needs to be minimized during AVA inversion. AVA inversion based on the L2-norm-based likelihood function is highly sensitive to outlier errors. In comparison, AVA inversion based on the L1-norm-based likelihood function is less affected by outlier errors, and for this reason we have used it with the total variation regularization method used as a constraint to invert discontinuities from geologic bodies. To ensure that the inversion results contain low-frequency components, prior information constraints from model parameters are added to the inverse objective function, which is then solved by the iterative reweighted least-squares method. Results of numerical tests and real-data examples from the application of this method indicate that the algorithm is strongly robust against noise, especially abnormal outlier errors, and that the results of the inversion are reasonable. © 2017 Society of Exploration Geophysicists.


Chen H.,China University of Petroleum - East China | Zhang G.,China University of Petroleum - East China
Surveys in Geophysics | Year: 2017

Fracture detection and fluid identification are important tasks for a fractured reservoir characterization. Our goal is to demonstrate a direct approach to utilize azimuthal seismic data to estimate fluid bulk modulus, porosity, and dry fracture weaknesses, which decreases the uncertainty of fluid identification. Combining Gassmann’s (Vier. der Natur. Gesellschaft Zürich 96:1–23, 1951) equations and linear-slip model, we first establish new simplified expressions of stiffness parameters for a gas-bearing saturated fractured rock with low porosity and small fracture density, and then we derive a novel PP-wave reflection coefficient in terms of dry background rock properties (P-wave and S-wave moduli, and density), fracture (dry fracture weaknesses), porosity, and fluid (fluid bulk modulus). A Bayesian Markov chain Monte Carlo nonlinear inversion method is proposed to estimate fluid bulk modulus, porosity, and fracture weaknesses directly from azimuthal seismic data. The inversion method yields reasonable estimates in the case of synthetic data containing a moderate noise and stable results on real data. © 2017, Springer Science+Business Media Dordrecht.


Qu Y.,China University of Petroleum - East China | Huang J.,China University of Petroleum - East China | Li Z.,China University of Petroleum - East China | Li J.,Chinese Academy of Geological Sciences
Geophysical Journal International | Year: 2017

Seismic wave propagation in a fluid-solid environment cannot be simulated with a single wave equation, but can be described by use of the acoustic and viscoelastic wave equations for their respective fluid and solid parts. Proper boundary conditions at the fluid-solid interface based on the relationship between pressure and stress are crucial when combining the two different wave equations. Traditional finite difference methods have had difficulties in dealing with the irregular fluid-solid interface topography. The Cartesian grids discretization leads to artificial reflections and diffractions during the conversion between acoustic wave and elastic waves. We propose a variable coordinate transformation methodology to simulate seismic waves in a fluid-solid environment.An irregular fluid-solid interface can be transformed into a horizontal interface, so that pressure and stress can be well converted. We also introduce a multiblock coordinate transformation (MCT) method which meshes each layer with curvilinear grids to transform the interface topography into a horizontal one, thereby allocating vertical sampling points adaptively. The grid size is determined adaptively based on the shape and the parameters of the target area, which reduces in size in when the layers are thin or exhibit low velocities. A Lebedev-standard staggered grid scheme is applied to the MCT method to reduce both the computational cost associated with the Lebedev grid scheme and the instability in the auxiliary coordinate system when using a standard staggered grid scheme. © The Authors 2016. Published by Oxford University Press on behalf of The Royal Astronomical Society.


Huang J.-Q.,China University of Petroleum - East China | Li Z.-C.,China University of Petroleum - East China
Chinese Journal of Geophysics (Acta Geophysica Sinica) | Year: 2017

Forward modeling and reverse time migration (RTM) of quasi-P-waves (qP) in TI medium for practical application draw great attention in recent year. Modeling based on conventional coupled equations may exist SV-wave artifacts and numerically dispersion, also suffer from strict limitations on the media parameter (η>0) and instabilities. For decoupled qP wave equation, it requires many tedious mathematical deduction, causing its numerical calculation to be very challenging, and its accuracy is limited, due to containing a pseudo-differential operator in this equation. To overcome these defects, Firstly, we derived a pure qP-wave propagator suitable for arbitrary TI media. Then the Low-rank decomposition algorithm was employed to solve the space-wavenumber domain matrix in propagator. In addition, the Cerjan's attenuation boundary condition was adopted to eliminate boundary reflections. Finally, an indirect pure qP-wave evolution scheme was implemented, which is successfully applied to perform modeling and RTM. Numerical experiments on modeling and RTM validate that, compared to the traditional approaches, the proposed scheme is more accurate and stable for anisotropic qP-wave modeling and RTM. Specifically, our method presented here include three aspects: (1) it cannot only avoid the complicatedly mathematical deduction of decoupled equations, but also break the restrictions (η>0) on media parameters for coupled equations; Besides, (2) SV-waves artifacts and numerical dispersion can be eliminate completely by this strategy; (3) Synthetic results remain high quality even for large temporal and spatial intervals or high-frequency sources, which proves better adaptability of the proposed method. © 2017, Science Press. All right reserved.


Tang M.,China University of Petroleum - East China | Zhang J.,Beijing Normal University
Xinan Shiyou Daxue Xuebao/Journal of Southwest Petroleum University | Year: 2017

Fracture modeling of tight oil reservoir has become the focus of reservoir modeling technology. Because existing fracture modeling methods are mostly ignored the essential relationship between the law of fracture propagation and the distribution of fracture characteristics, and therefore impossible to give an effective information of fracture distribution. In this paper, we proposed one new fracture modeling method called stochastic extended finite element method, which is build based on fracture mechanics and multi-field Kriging method. This method established the fracture propagation inversion model firstly, based on law of fracture propagation and extended finite element method, by using annealing simulation method. Then, by integrating the Kriging system and fracture simulation system and using structure and imaging logging data, we constructed an multi-field Kriging estimation model. Finally, based on the stochastic extended finite element simulation method, we wrote a fracture modeling system software, and build the fracture propagation model and fracture distribution model of Upper Cretaceous Qingshankou Formation in Daqingzijing area. Simulation results have shown that the fracture modeling method based on stochastic extended finite element simulation could overcome the difficult of existing fracture modeling method, and improve the characterization precision of fractured reservoir. © 2017, Science Press. All right reserved.


Xu K.,Yantai University | Qiu X.,China University of Petroleum - East China | Tian X.,China University of Petroleum - East China
Journal of Nondestructive Evaluation | Year: 2017

Metal magnetic memory (MMM) testing is an advanced and nondestructive testing method based on magneto-mechanical effects. This technique can be used to assess defects based on MMM signals (MMMS). However, a thorough understanding of the impact that crack depth, working load, and heat treatment have on residual magnetic field variations (which can in turn affect defect assessment) has not yet been established in the literature. This report presents MMMS testing results of buried welding cracks under different applied loads, as well as before and after heat treatment, in order to analyse the impact of such factors on MMMS data. The results show that the MMMS is significantly affected by the depth at which a given crack is buried in a material, any load applied to the specimen, and the type of heat treatment employed. Therefore, the above factors should be considered when evaluating defects to avoid the inappropriate assessment of such defects. © 2017, Springer Science+Business Media New York.


Zhang D.,China University of Petroleum - East China | Jiang C.,China University of Petroleum - East China | Liu J.,China University of Petroleum - East China | Cao Y.,China University of Petroleum - East China
Sensors and Actuators, B: Chemical | Year: 2017

A sub-ppm-level CO gas sensor based on copper oxide (CuO)-decorated graphene hybrid nanocomposite was reported in this paper. The CuO/graphene hierarchical nanocomposite was successfully deposited on a substrate with interdigital microelectrodes via layer-by-layer self-assembly technique. The morphologies, microstructures and compositions of the as-prepared CuO/rGO film were sufficiently characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD). The gas sensing properties of the CuO/graphene nanocomposite was investigated at room temperature over a wide range concentration of CO gas from 0.25 ppm to 1000 ppm. The experimental results exhibited not only an unprecedented detection abilities, but also fast response and recovery times, excellent repeatability, good stability and selectivity. The superior sensing mechanism for the presented sensor was ascribed to the hierarchical porous nanostructure and the formed heterojunction at the interfaces between CuO nanoflowers and rGO nanosheets. © 2017 Elsevier B.V.


Guo S.,China University of Petroleum - East China | Liu H.,China University of Petroleum - East China | Shan Y.,North China Electrical Power University | Bu Y.,China University of Petroleum - East China
Construction and Building Materials | Year: 2017

The research objectives in this paper are designed to develop one new type of retarder for calcium aluminate phosphate cement (CAPC) to extend the thickening time. Results show that due to the influence of sodium hexametaphosphate, many kinds of conventional Portland cement retarder lose the retarding function in CAPC. AMPS/IA copolymer could extend the thickening time obviously; however, the thickening curves show consistency fluctuations. Although, treated AMPS/IA copolymer could avoid the consistency fluctuation, right angle thickening property is weak. Due to the synergistic effect, the combination of treated AMPS/IA copolymer and borax is more suitable as the retarder for CAPC. © 2017 Elsevier Ltd


Liu C.,China University of Petroleum - East China | Li Y.,China University of Petroleum - East China | Fang L.,Qinzhou University | Xu M.,China University of Petroleum - East China
International Journal of Pressure Vessels and Piping | Year: 2017

To protect the pipelines from significant danger, the acoustic leak detection and location method for oil and gas pipelines is studied, and a de-noising system is established to extract leakage characteristics from signals. A test loop for gas and oil is established to carry out experiments. First, according to the measured signals, fitting leakage signals are obtained, and then, the objective signals are constructed by adding noises to the fitting signals. Based on the proposed evaluation indexes, the filtering methods are then applied to process the constructed signals and the de-noising system is established. The established leakage extraction system is validated and then applied to process signals measured in gas pipelines that include a straight pipe, elbow pipe and reducing pipe. The leak detection and location is carried out effectively. Finally, the system is applied to process signals measured in water pipelines. The results demonstrate that the proposed de-noising system is effective at extracting leakage signals from measured signals and that the proposed leak detection and location method has a higher detection sensitivity and localization accuracy. For a pipeline with an inner diameter of 42 mm, the smallest leakage orifice that can be detected is 0.1 mm for gas and water and the largest location error is 0.874% for gas and 0.176% for water. © 2017 Elsevier Ltd


Bai F.,China University of Petroleum - East China | Jiao Z.,China University of Petroleum - East China | Xu X.,China University of Petroleum - East China | Zhang H.,China University of Petroleum - East China
Materials Science Forum | Year: 2017

A compact passively Q-switched YVO4/Nd:YVO4/KTA intracavity optical parametric oscillator (OPO) is realized. With an end-pumping diode power of 16.6 W, output signal power of 932 mW and idler power of 415 mW are obtained at a pulse repetition rate of 101 kHz. The pulse widths and the beam quality factors are also analyzed for both signal and idler lasers. © 2017 Trans Tech Publications, Switzerland.


Gao X.,China University of Petroleum - East China | Zhang X.,China University of Petroleum - East China | Wang J.,China University of Petroleum - East China
Paiguan Jixie Gongcheng Xuebao/Journal of Drainage and Irrigation Machinery Engineering | Year: 2017

In order to realize an effective repair and a supply of inhibitor in a follow-up normal injection process for an inhibitor to exhibit corrosion protection effect, the distribution of corrosion inhibitor in a gas pipeline needs to be studied in detail. Software Fluent was used to simulate the gas and liquid turbulent flow and inhibitor distribution in a pipeline based on the Euler-Euler model, RNG k-ε turbulence model and VOF method. The distribution of inhibitor liquid film along the inner wall of the gas pipeline is obtained, and the influences of surface tension of the corrosion inhibitor on the liquid film distribution under scouring and gravity are clarified. The results show that the inhibitor settles toward pipe bottom due to the gravity, which accounts for 1/3 of the cross-section of the pipe. The se-condary flow in the elbow can destroy the initial distribution of corrosion inhibitor, and drive the inhibitor along the secondary flow path to damp it on the bottom of the elbow. Therefore, the pipe and elbow top should be monitored carefully in engineering practice. The higher surface tension the inhibitor possesses, the more adhesion work the pipe wall has, in consequence the more uniform distribution of corrosion inhibitor and the higher inhibitor volume fraction adhered to the wall. As a result, the highest corrosion inhibitor volume fraction can be as large as 100%. It suggests that an inhibitor with stronger adhesiveness and higher surface tension should be chosen in pre-filming process. © 2017, Editorial Department of Journal of Drainage and Irrigation Machinery Engineering. All right reserved.


Zhang D.,China University of Petroleum - East China | Jiang C.,China University of Petroleum - East China | Li P.,Tsinghua University | Sun Y.,China University of Petroleum - East China
ACS Applied Materials and Interfaces | Year: 2017

This article is the first demonstration of a molybdenum disulfide (MoS2)/tricobalt tetraoxide (Co3O4) nanocomposite film sensor toward NH3 detection. The MoS2/Co3O4 film sensor was fabricated on a substrate with interdigital electrodes via layer-by-layer self-assembly route. The surface morphology, nanostructure, and elemental composition of the MoS2/Co3O4 samples were examined by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, energy-dispersive spectrometry, and X-ray photoelectron spectroscopy. The characterization results confirmed its successful preparation and rationality. The NH3 sensing properties of the sensor for ultra-low-concentration detection were investigated at room temperature. The experimental results revealed that high sensitivity, good repeatability, stability, and selectivity and fast response/recovery characteristics were achieved by the sensor toward NH3. Moreover, the MoS2/Co3O4 nanocomposite film sensor exhibited significant enhancement in ammonia-sensing properties in comparison with the MoS2 and Co3O4 counterparts. The underlying sensing mechanisms of the MoS2/Co3O4 nanocomposite toward ammonia were ascribed to the layered nanostructure, synergistic effect, and heterojunction created at the interface of n-type MoS2 and p-type Co3O4. The synthesized MoS2/Co3O4 nanocomposite proved to be an excellent candidate for constructing high-performance ammonia sensor for various applications. © 2017 American Chemical Society.


Xu X.,China University of Petroleum - East China | Liu J.,Dalian Maritime University | Hao J.,China University of Petroleum - East China
Harbin Gongcheng Daxue Xuebao/Journal of Harbin Engineering University | Year: 2017

The weak demand for the global shipping market and the serious oversupply of China's shipbuilding capacity have prompted the national and regional shipbuilding industry to accelerate industry restructuring and upgrading. To ensure the pertinence and effectiveness of related measures, the interaction relationship and degree between the regional shipbuilding industry and the economic system need to be studied first. In this paper, the economic data of Qingdao from 1990-2014 are compiled. A dynamic transfer model between the shipbuilding industry and economic variables is then constructed by utilizing vector autoregression model(VAR). Then, Granger causality test and Cholesky orthogonal impulse response are used to analyze the correlation effects and trend influence of variables. Analysis results show that the shipbuilding industry and the economic system in Qingdao have a close relationship; financing channels and service modes have an important influence on the development of the shipbuilding industry; and the industrial chain and product category need optimized allocation. © 2017, Editorial Department of Journal of HEU. All right reserved.


Wang H.,China University of Petroleum - East China | Li X.,China University of Petroleum - East China | Li C.,China University of Petroleum - East China
Applied Surface Science | Year: 2017

Different with Wang et. al.’s study, we found that polymeric Si–O–Sn2+ rather than Ni-Sn alloy and metallic Sn are active species in silica-supported tin oxide catalysts for dehydrogenation of propane. The results showed that high surface area of mesoporous silica brought about high dispersion of tin oxide species, as a result, catalytic activity and stability were both improved. DRUV–vis, XPS, TPR and XRD studies of fresh and reduced catalysts indicated that the deactivation was related to the reduction of active species rather than the coke formation since active tin species cannot maintain its oxidation state at reaction conditions (high temperature and reducing atmosphere). The formed Ni3Sn2 alloy after reduction just functioned as promoter which accelerated the desorption of H2 and regeneration of active site. A synergy effect between active tin species and Ni3Sn2 alloy were observed. © 2017 Elsevier B.V.


Wu X.-P.,China Coal Technology and Engineering Co. | Jin P.-J.,China University of Petroleum - East China | Zhang Y.,China University of Petroleum - East China
Civil Engineering and Urban Planning IV - Proceedings of the 4th International Conference on Civil Engineering and Urban Planning, CEUP 2015 | Year: 2016

According to the element stresses, strains, and displacements calculated by the Finite Difference Method (FDM), the Finite Arc Method that is based on the limit equilibrium theory and the Strength Reduction Method with deformation trend as the failure standard are established in this paper. The two methods coupled with the Limit Equilibrium Method are mutually applied to study the critical slope degree of large channel excavation in South-to-North Water Diversion project in China. Three typical channel slope modes, which high slope, reclaimed slope and deeply excavated slope mode, are selected to acquire the variation curve of safety factor with the changes of excavation slope. Through comparison and analysis of the results, the critical excavated slope of the channel can be determined. © 2016 Taylor & Francis Group, London.


Li J.,Arizona State University | Hu X.,Texas A&M University | Jian L.,China University of Petroleum - East China | Liu H.,Arizona State University
Proceedings - IEEE International Conference on Data Mining, ICDM | Year: 2017

Recent years have witnessed the prevalence of networked data in various domains. Among them, a large number of networks are not only topologically structured but also have a rich set of features on nodes. These node features are usually of high dimensionality with noisy, irrelevant and redundant information, which may impede the performance of other learning tasks. Feature selection is useful to alleviate these critical issues. Nonetheless, a vast majority of existing feature selection algorithms are predominantly designed in a static setting. In reality, real-world networks are naturally dynamic, characterized by both topology and content changes. It is desirable to capture these changes to find relevant features tightly hinged with network structure continuously, which is of fundamental importance for many applications such as disaster relief and viral marketing. In this paper, we study a novel problem of time-evolving feature selection for dynamic networks in an unsupervised scenario. Specifically, we propose a TeFS framework by leveraging the temporal evolution property of dynamic networks to update the feature selection results incrementally. Experimental results show the superiority of TeFS over the state-of-The-Art batch-mode unsupervised feature selection algorithms. © 2016 IEEE.


Broadband Spectral inversion of incoherent light is realized via four-wave mixing in a highly nonlinear fiber without spectrum deformation providing an implementation solution for compensating power depletion due to SRS in high-power delivery fiber. © OSA 2016.


Liu D.,China University of Petroleum - East China | Wang A.,Dalian University of Technology | Liu C.,China University of Petroleum - East China | Prins R.,ETH Zurich
Catalysis Today | Year: 2016

Bulk Ni2P and Al2O3-supported Ni2P were prepared at low phosphidation temperature (300 or 330°C) from nickel nitrate, oxide, sulfate, chloride, and acetate as nickel source and ammonium and sodium hypophosphite as well as hypophosphoric acid as phosphorus source. The hypophosphite source was positioned up-flow of the nickel source in an oven and flowing N2 gas transported the phosphine formed in the decomposition of hypophosphite to the nickel compound. X-ray diffraction, N2 adsorption-desorption, thermogravimetry and differential scanning calorimetry, temperature-programmed reduction in H2, and transmission electron microscopy, field emission scanning electron microscopy, CO chemisorption, and solid-state 31P nuclear magnetic resonance were used to study the bulk and supported Ni2P. Whereas unsupported nickel nitrate, sulfate, chloride, and oxide led to impure Ni2P, nickel acetate gave pure Ni2P. Ni2P/Al2O3 catalysts were therefore prepared from nickel acetate and their activity was studied in the hydrodesulfurization of dibenzothiophene. Separating the hypophosphite from the nickel compound has the advantage that the phosphate formed in the disproportionation of hypophosphite does not reach the Al2O3-supported Ni compound and cannot block the pores of the support. Ni2P is formed by sequential reduction and phosphidation reactions and therefore its preparation demands careful adjustment of the synthesis conditions. Insufficient PH3 leads to Ni and Ni12P5 side products and too much PH3 to Ni5P4, which all have a lower HDS activity than Ni2P. © 2016 Elsevier B.V.


Gao M.,China University of Petroleum - East China | Sheng L.,China University of Petroleum - East China | Zhou D.,Shandong University of Science and Technology | Niu Y.,China University of Petroleum - East China
Signal Processing | Year: 2017

This paper deals with the event-based fault detection problem for T–S fuzzy systems with packet dropouts as well as state- and disturbance-dependent noises ((x, v)-dependent noises for short). To utilize limited network resources efficiently, the event-triggered mechanism is employed such that only selected valuable data is transmitted to the filter according to whether specific events happen or not. The aim of the addressed problem is to design a fuzzy fault detection filter which guarantees the stochastic stability of the overall fault detection dynamics as well as the robustness against disturbances and sensitivity to faults of the residual signal. Some sufficient criteria are obtained for the existence of the desired fault detection filter which can be designed by solving a set of linear matrix inequalities. Finally, a numerical example is presented to illustrate the validity of the derived results. © 2017 Elsevier B.V.


Wang M.,China University of Petroleum - East China | Zhou P.,China University of Petroleum - East China | Wang J.,China University of Petroleum - East China | Zhao Y.,China University of Petroleum - East China | And 3 more authors.
Journal of the American Chemical Society | Year: 2017

Peptide and protein fibrils have attracted an enormous amount of interests due to their relevance to many neurodegenerative diseases and their potential applications in nanotechnology. Although twisted fibrils are regarded as the key intermediate structures of thick fibrils or bundles of fibrils, the factors determining their twisting tendency and their handedness development from the molecular to the supramolecular level are still poorly understood. In this study, we have designed three pairs of enantiomeric short amphiphilic peptides: LI3 LK and DI3 DK, LI3 DK and DI3 LK, and LaI3 LK and DaI3 DK, and investigated the chirality of their self-assembled nanofibrils through the combined use of atomic force microscopy (AFM), circular dichroism (CD) spectroscopy, scanning electron microscopy (SEM), and molecular dynamic (MD) simulations. The results indicated that the twisted handedness of the supramolecular nanofibrils was dictated by the chirality of the hydrophilic Lys head at the C-terminal, while their characteristic CD signals were determined by the chirality of hydrophobic Ile residues. MD simulations delineated the handedness development from molecular chirality to supramolecular handedness by showing that the β-sheets formed by LI3 LK, LaI3 LK, and DI3 LK exhibited a propensity to twist in a left-handed direction, while the ones of DI3 DK, DaI3 DK, and LI3 DK in a right-handed twisting orientation. © 2017 American Chemical Society.


Wang Y.,China University of Petroleum - East China | Ge J.,China University of Petroleum - East China | Zhang G.,China University of Petroleum - East China
Journal of Surfactants and Detergents | Year: 2017

The original purpose of our work was finding commercial foaming agents for high-salinity reservoirs. During the study, the commercial lauramide amide oxide solution displayed different foaming properties in high-salinity water (salinity 220,000 mg/L) at different aging times and relatively low temperature (25 °C). Foam volume decreases drastically first with the increase of aging time. Then, with further aging, foam volume increases. However, in low-salinity water or at high temperature, no obvious foam volume variation was observed. Lauric acid in the commercial surfactant plays a key role. Under proper temperature and pH conditions, lauric acid will react with Ca2+. Calcium laurate generated from lauric acid in the commercial form and Ca2+ from water influences the foaming property significantly. At the beginning of calcium laurate generation, surfactants adsorb on calcium laurate and decelerate the diffusion velocity of lauramide amide oxide from the bulk phase to the air–water interface. With the increase of aging time, calcium laurate gathers, thus adsorption of lauramide amide oxide by calcium laurate decreases. Hence, the foaming volume increases. © 2017, AOCS.


Chen S.J.,China University of Petroleum - East China | Zhu M.,China University of Petroleum - East China | Fu Y.,China University of Petroleum - East China | Huang Y.X.,China University of Petroleum - East China | And 2 more authors.
Applied Energy | Year: 2017

This work investigates the application of X zeolites for capturing CO2 from post-combustion flue gas. LiX and LiPdAgX zeolites were prepared by an ion-exchange method using 13X zeolite. X-ray diffraction analysis showed that all samples exhibited characteristic peaks of X zeolites, where the peak intensities increased in the order: LiPdAgX > LiX > 13X. The enhanced intensity of the diffraction peaks can increase the activity of the X zeolites and improve their adsorption performance. Scanning electron microscopy imaging showed that the intergranular pore canals of LiPdAgX zeolite were more concentrated. Pore structure analysis indicated that addition of Li+ to the 13X zeolite enhanced the specific surface areas and pore volumes of the zeolites. Among the 13X, LiX, and LiPdAgX zeolites, LiPdAgX showed the highest CO2/N2selectivity, where the difference in the CO2 adsorption capacity was due to differences in the number of adsorption sites and thermal conductivities of the X zeolites. The CO2 breakthrough time increased in succession for the 13X, LiX, and LiPdAgX zeolites. The CO2/N2 separation factor of the LiPdAgX zeolite was twice that of the 13X zeolite at a CO2 concentration of 20 vol.%. The temperature variations during the adsorption process were used to determine the regeneration energy and adsorption capacity of the X zeolites. LiPdAgX zeolite required less energy for regeneration than 13X zeolite and MEA. After regeneration, the separation factor of LiPdAgX zeolite remained at 6.38 for 20 vol.% CO2 in the flue gas. Therefore, LiPdAgX zeolite can effectively capture CO2 from post-combustion flue gas to curtail the release of CO2 into the atmosphere. © 2017 Elsevier Ltd


Wang Q.,China University of Petroleum - East China | Li R.,China University of Petroleum - East China
Renewable and Sustainable Energy Reviews | Year: 2017

The shale gas revolution has resulted in a sharp growth in the number of researchers and collaborative work in this area, particularly during the past few decades. This study aims to provide unprecedented and invaluable shale gas information to businesses, policymakers, and any part of society involved in shale gas development. Using bibliometric and collaboration techniques, our study focuses (on an individual level) on the development trends in shale gas research. We examine the most influential authors and explore the characteristics and implications of collaboration networks and patterns in shale gas literature between 1990 and 2014. Much of our information was obtained from the Science Citation Index Expanded (SCIE) database. Author collaboration analysis software that has been independently developed was used to further explain core author contributions and trends, as well as collaboration networks. We primarily focus on three research areas: (1) the quantity and growth trend of the number of authors exploring shale gas, (2) author productivity distribution, and (3) an analysis of author collaboration networks. First, our results reveal three developmental stages. The period from 1990 to 2008 was the early stage and characterized by steady development. The years between 2008 and 2013 witnessed rapid growth, before that growth slowed notably after 2013. The annual growth rate of the number of new authors was determined to be approximately 980%. This finding also indicates that shale gas is becoming a fast-developing and popular research topic. Furthermore, Horsfield B from the German Research Centre for Geosciences has been the dominant contributor to date, followed by Krooss BM and Ballice L. The top 15 authors are mainly from Germany, the USA, Canada, Estonia, Jordan, and China. Our collaboration network and pattern analysis reveals that the two biggest clusters of cooperation are comprised of Horsfield B and Ballice L. We also discovered that most authors have a specific collaboration, such as that between Williams PT and Jaber JO, both of whom are from the Al-Ahliyya Amman University. © 2017 Elsevier Ltd


Li S.,China University of Petroleum - East China | Li Z.,China University of Petroleum - East China | Sun X.,China University of Petroleum - East China
Fuel | Year: 2017

Heavy-oil reservoirs with thin-pay and bottomwater can be exploited effectively by thermal recovery process assisted by flue gas and n-hexane. The interface properties between flue gas/n-hexane and heavy oil and viscosity reduction of the heavy oil were investigated by laboratory experiments. Steam flooding, flue gas assisted steam flooding, n-hexane assisted flooding and flue gas and n-hexane assisted steam flooding were conducted to research the displacement pressure difference, oil displacement efficiency and component variation of produced and residual oils. The results show that the flue gas dissolving in heavy oil can effectively reduce oil viscosity, increase the flow capability, and make the heavy oil swell. Higher pressure reduces surface tension of heavy oil and gas, and higher temperature increases surface tension. Compared with flue gas, n-hexane can reduce heavy oil viscosity and surface tension more obviously. The flue gas and n-hexane can effectively improve the development effect of the steam flooding. The pressure difference of steam flooding assisted by flue gas and n-hexane is the lowest, the oil production rate is greatest, and the oil recovery efficiency can reach 80%. Flue gas and n-hexane can effectively change crude oil properties. The heavy components, molecular weight of asphaltene and oil viscosity for the produced oil all reduced. The heavy components and molecular weight of asphaltene for the residual oil in sandpacks all increased. The effect of flue gas and n-hexane together on heavy oil is the greatest. The asphaltenes component in the residual oil is not as stable as that in produced oil. The experimental results not only show that flue gas and n-hexane can successfully improve the performance of steam flooding process, but also provide a deep understanding of properties changes of produced and residual oils for the flooding. © 2016 Elsevier Ltd


Zhang F.,China University of Petroleum - East China | Li Y.,China University of Petroleum - East China
Nonlinear Dynamics | Year: 2017

In this paper, a delayed-diffusive predator–prey model with hyperbolic mortality and nonlinear prey harvesting subject to the homogeneous Neumann boundary conditions is investigated. Firstly, the global asymptotic stability of the unique positive constant equilibrium is obtained by an iteration technique. Secondly, regarding time delay as a bifurcation parameter and using the normal form theory and center manifold theorem, the existence, stability and direction of bifurcating periodic solutions are demonstrated, respectively. Finally, numerical simulations are conducted to illustrate the theoretical analysis. © 2017 Springer Science+Business Media Dordrecht


Xiao Z.,China University of Petroleum - East China | Liang W.,China University of Petroleum - East China | Zhu X.,China University of Petroleum - East China | Zhao J.-Y.,China University of Petroleum - East China
Journal of Biotechnology | Year: 2017

Consumers prefer biotechnological food products with high nutritional values and good flavors. Solid-state fermentation is a commonly used technique with a long history. In the present study, Myroides sp. ZB35 was used in solid-state fermentative production of aroma volatiles on a rice medium. Using the headspace solid phase microextraction coupled with gas chromatography-mass spectrometry technique and authentic standards, 22 esters with molecular weight ranging from 102 to 172 were identified. At 192. h, the esters reached a total concentration of 1774. μg/kg. Subsequently, the complete genome of ZB35 was sequenced using the PacBio RS II platform. ZB35 has a single circular chromosome of 4,065,010. bp with a GC content of 34.1% and six putative novel esterase genes were found. ZB35 is the first bacterium here discovered being capable of producing so many kinds of aroma esters. The data revealed here would provide helpful information for further developing this strain as a promising source of aroma esters relevant in food and fragrance industries and the source of novel enzymes with potential usages. © 2017 Elsevier B.V.


Abdelrasoul A.,Ryerson University | Zhang H.,China University of Petroleum - East China | Cheng C.-H.,Ryerson University | Doan H.,Ryerson University
Microporous and Mesoporous Materials | Year: 2017

Zeolites are fascinating and versatile materials which are vital for a wide range of industries, due to their unique structural and chemical properties, which are the basis of applications in gas separation, ion exchange, and catalysis. Given their economic impact, there is a powerful incentive for smart design of new materials with enhanced functionalities for maximizing their application performance. This review article intends to summarize the published reports on the applications of molecular simulation in adsorption, separation and diffusion. The theoretical aspects, adsorption thermodynamics, adsorption isotherm were comprehensively studied in relation to the adsorption applications and how the adsorbates’ characteristics influence the adsorption. This review comprehensively discusses the theoretical and computational aspects of diffusion of pure components, long chain hydrocarbons or mixture diffusion, including the molecular dynamics simulations and kinetic Monte Carlo. Furthermore, the cation-zeolite-adsorbate interactions are thoroughly examined so as to elucidate the role of cations in zeolites applications and how the cation exchange influences structural dynamics and properties of zeolites. This study also focuses on the role of cations in gas/liquid adsorption and separations. © 2017 Elsevier Inc.


Wang Y.,China University of Petroleum - East China | Yin C.,China University of Petroleum - East China | Zhao X.,China University of Petroleum - East China | Liu C.,China University of Petroleum - East China
Catalysis Communications | Year: 2017

A bifunctional highly-loaded NiMoW catalyst was prepared via hydrothermal reaction method with the incorporation of USY zeolite during synthetic process of precursor. The obtained samples were characterized by N2 physisorption, XRD, Py-FTIR, and HRTEM. Combined with 4,6-DMDBT HDS activity results, Brønsted acid sites have been successfully generated in catalysts, and facilitated the demethylation and cracking reaction, as well as the DDS activity. The high activity of thus-achieved bifunctional catalysts can be attributed to the appropriate acid amount and the synergistic effect of Lewis and Brønsted acid sites combining with desirable textural properties and suitable stacking morphology of MoS2/WS2 slabs. © 2016


Zhou L.,Naval Academy of Armament | Chen Y.,China University of Petroleum - East China | Yang Z.,Naval Academy of Armament
Proceedings - 2016 9th International Symposium on Computational Intelligence and Design, ISCID 2016 | Year: 2017

Diffusion-based salient region detection has recently received intense research attention. In this paper, we propose a salient region detection method based on the foreground and background propagation with manifold ranking. By considering the spatial variance of superpixel clusters, foreground and background seed regions are extracted preliminarily. Then, in order to produce a pixel-accurate saliency map covering the salient objects more uniformly, we propagate the foreground and background seed regions through the diffusion process. Experimental results on public benchmark databases show that the proposed method can completely highlight the salient regions and sufficiently suppress the background regions. © 2016 IEEE.


Liu Q.,Shandong University of Science and Technology | Tian Y.,Shandong University of Science and Technology | Tian Y.,China University of Petroleum - East China
International Journal of Hydrogen Energy | Year: 2017

The NiO/SBA-15 monolith with a three-dimensional (3D) network structure was synthesized by a facile one-pot hydrothermal method for CO2 methanation. The results showed that the net-linked mesoporous framework of SBA-15 was well preserved after incorporation of 15 wt% NiO, and the one-pot prepared NiO/SBA-15-Op material exhibited higher surface area, larger pore volume than the NiO/SBA-15-Im synthesized by traditional impregnation method. In addition, NiO/SBA-15-Op showed higher catalytic activity and anti-sintering property of metallic Ni than NiO/SBA-15-Im for CO2 methanation due to higher Ni dispersion and more Ni particles dispersed in the meso-channels. © 2017 Hydrogen Energy Publications LLC.


Li X.,China University of Petroleum - East China | Shao M.-W.,China University of Petroleum - East China | Zhao X.-M.,Shenzhen University
International Journal of Machine Learning and Cybernetics | Year: 2017

The construction of concept lattices is one of the key issues of formal concept analysis. Many methods and algorithms are proposed to build a lattice, among which, incremental algorithms are more appropriate in real-life applications that work with dynamic datasets. But they cost much time to locate generators before generating a real concept. The batch algorithms generate concepts quickly. However, they ignore the procedure of building lattice relationship. In this paper, we build the lattice from meet-irreducible attribute concepts by using generators directly, and make optimizations in key steps. We yield the relationship among concepts during the generating process that saves much time in contrast to other batch algorithms. In addition to proving the correctness of our algorithm, we evaluate its performance on some real datasets and compare it with an incremental algorithm called FastAddIntent. The results show that our algorithm mainly depends on the numbers of concepts and the numbers of attributes, which achieves good performance, especially to large formal contexts. © 2016, Springer-Verlag Berlin Heidelberg.


Hao Y.,China University of Petroleum - East China | Sun G.,China University of Petroleum - East China
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2016

Seismic image classification is of vital importance for extracting damage information and evaluating disaster losses. With the increasing availability of high resolution remote sensing images, automatic image classification offers a unique opportunity to accommodate the rapid damage mapping requirements. However, the diversity of disaster types and the lack of uniform statistical characteristics in seismic images increase the complexity of automated image classification. This paper presents a novel automatic seismic image classification approach by integrating an adaptive spectral-textural descriptor into gravitational self-organizing map (gSOM). In this approach, seismic image is first segmented into several objects based on mean shift (MS) method. These objects are then characterized explicitly by spectral and textural feature quantization histograms. To objectify the image object delineation adapt to various disaster types, an adaptive spectral-textural descriptor is developed by integrating the histograms automatically. Subsequently, these objects as classification units are represented by neurons in a self-organizing map and clustered by adjacency gravitation. By moving the neurons around the gravitational space and merging them according to the gravitation, the object-based gSOM is able to find arbitrary shape and determine the class number automatically. Taking advantage of the diversity of gSOM results, consensus function is then conducted to discover the most suitable classification result. To confirm the validity of the presented approach, three aerial seismic images in Wenchuan covering several disaster types are utilized. The obtained quantitative and qualitative experimental results demonstrated the feasibility and accuracy of the proposed seismic image classification method. © 2016 SPIE..


Gong F.,China University of Petroleum - East China | Shao M.-W.,China University of Petroleum - East China | Shao M.-W.,Key Laboratory of Oceanographic Big Data Mining and Application of Zhejiang Province | Qiu G.,Shanxi University
International Journal of Machine Learning and Cybernetics | Year: 2017

In this paper, three kinds of adjoint extent-intent and intent-extent operators between two complete lattices are constructed. Three new types of concept granular computing systems are then formulated via a quadruple including two complete lattices and the corresponding adjoint operators. It is showed that all the concepts in any of the concept granular computing systems form a complete lattice. Furthermore, based on the four types of concept granular computing systems, we present four types of rough set approximation operators in a formal context which can characterize different aspect of knowledge. Some important properties of the proposed approximation operators are also proved. © 2015, Springer-Verlag Berlin Heidelberg.


Wu S.,China University of Petroleum - East China | Ge H.,China University of Petroleum - East China | Wang X.,China University of Petroleum - East China | Meng F.,China University of Petroleum - East China
Journal of Natural Gas Science and Engineering | Year: 2017

The study of the shale rocks’ fracturing characteristics reveal general guidelines for hydraulic fracturing processes in shale reservoirs, and the microseismic information provides a direct reflection of the fracturing process. Acoustic emission (AE) testing of rocks in the laboratory can be used for the application of microseismic information acquired in the field. Therefore, uniaxial compression experiments were performed to study AE characteristics during the failure process in shale rocks. In this study, the number of AE hits, along with the energy, a-values and b-values, were used to characterise the AE data and to describe the rock's rupture behaviour. The testing results indicated that the AE rates and energy values increased markedly when slippage occurred and these parameters reflect the generation of micro-cracks in the rock. The b and a-value curves can be divided into four stages corresponding with the fracture processes. The changes in the b and a -values can indicate the distribution characteristics of cracks within the rock. Based on this theory, the AE characteristics from dry and water-saturated shale samples under uniaxial compression were compared to demonstrate that water diffuses pressure in the rock and promotes fracture network generation. The b-values in the elastic-yield stage increase along with the brittleness index, and the b-values in the post-peak stage can offset the limitations of brittleness indexes used in evaluations of reservoir fracability. Exploring the law of rupture for shale under pressure provides a foundation for microseismic-based quantitative evaluation of the hydraulic fracturing stimulation efforts in shale reservoirs; therefore, this knowledge has both scientific and engineering significance. © 2017 Elsevier B.V.


Li S.,China University of Petroleum - East China | Qiao C.,China University of Petroleum - East China | Li Z.,China University of Petroleum - East China | Wanambwa S.,China University of Petroleum - East China
Energy and Fuels | Year: 2017

Nanoparticles can improve the stability of CO2 foam and increase oil recovery during CO2 flooding in reservoirs. The synergistic effect of hydrophilic SiO2 nanoparticles and hexadecyltrimethylammonium bromide (CTAB) on CO2 foam stability was examined in this study. Experimental results show that the synergistic effect requires a CTAB/SiO2 concentration ratio of 0.02-0.07, with 0.033 representing the best concentration ratio. With the increase in the concentration ratio, the synergistic stabilization effect of CTAB/SiO2 dispersion first increases and then decreases. In the monolayer adsorption stage (concentration ratio from 0.02 to 0.033), when the hydrophobicity of SiO2 nanoparticles increases with the concentration ratio, the nanoparticles tend to adsorb on the gas-liquid interface and the stability of CO2 foam increases. In the double-layer adsorption stage (concentration from 0.033 to 0.07), when the hydrophobicity of SiO2 nanoparticles decreases with an increase in the concentration ratio, the nanoparticles tend to exist in the bulk phase and the stability of CO2 foam decreases. The CTAB/SiO2 dispersion stabilizes CO2 foam via three mechanisms: decreasing the coarsening of CO2 bubbles, improving interfacial properties, and reducing liquid discharge. CTAB/SiO2 foam can greatly improve oil recovery efficiency compared to water flooding. Experimental results provide theoretical support for improving CO2 foam flooding under reservoir conditions. © 2017 American Chemical Society.


Yan X.-H.,China University of Petroleum - East China | Lin Y.-N.,China University of Petroleum - East China
Modern Physics Letters B | Year: 2017

First-principles calculations based on density functional theory (DFT) were employed to investigate the influence of Ga concentration on the stability of binary Fe-Ga alloy. The contents of Ga element are 6.25, 12.5, 18.75 and 25 at.% for Fe15Ga, Fe7Ga, Fe13Ga3 and Fe3Ga alloys, respectively. Cohesive energy, elastic properties, electronic structures and phonon properties of optimized Fe-Ga models were calculated. Our results of calculated elastic constants and elastic moduli are in good accordance with the determined available literature. Our study shows that with increasing Ga content, the absolute value of cohesive energy of Fe-Ga alloy is decreasing. From the calculations of elastic constants, we found that the value of C11 decreases with the increasing Ga content, which indicates that the stability of Fe-Ga along the [001] direction is decreasing with the increasing Ga content. The calculated bulk moduli of Fe-Ga alloys increase with increasing Ga content because of the increase of the average bonding number evaluated by our calculations of densities of states. Conversely, the shear moduli decrease with increasing Ga content, which indicates that the stability of Fe-Ga is decreasing with the increasing Ga content. Tetragonal shear elastic constant C′ = (C 11 - C12)/2 almost decreases linearly with increasing Ga content, which follows the same decreasing trend as the cohesive energy and the shear modulus. It is worth noting that with the increasing Ga content, the pseudogap between two major peaks in the minority-spin state became softer. The softness brings the Fermi level into a high state, which lowers the stability of the Fe-Ga alloy. According to the phonon calculations, the acoustic mode of Fe-25 at.% Ga appeared to be softening along the [001] direction, which is in good accordance with the direction predicted by the calculations of elastic constant. But this softening trend cannot be observed in the phonon dispersion spectrum of Fe-6.25 at.% Ga, which proved that Fe-6.25 at.% Ga is more stable than the Fe-25 at.% Ga alloy. © 2017 World Scientific Publishing Company.


Xie X.,Tianjin University of Technology | Zhang C.,Tianjin University of Technology | Wu M.-B.,China University of Petroleum - East China | Tao Y.,Tianjin University of Technology | And 4 more authors.
Chemical Communications | Year: 2013

Graphene oxide hydrogel is used as a reactive template to prepare nanoporous materials with a 3D microstructure. The as-prepared porous MnO 2 shows a capacitance retention of ∼70.6% at a current density as high as 15 A g-1, resulting from the 3D interconnected ion transport channel replicated from the graphene oxide hydrogel. © 2013 The Royal Society of Chemistry.


Zhao X.,Bohai University | Zhao X.,China University of Petroleum - East China | Zhang L.,Harbin Institute of Technology | Shi P.,University of South Wales | And 2 more authors.
IEEE Transactions on Fuzzy Systems | Year: 2014

In this paper, novel stability conditions for Takagi-Sugeno (T-S) fuzzy systems are presented. The so-called nonquadratic membership-dependent Lyapunov function is first proposed, which is formulated in a higher order form of both the system states and the normalized membership functions than existing techniques in the literature. Then, new membership-dependent stability conditions are developed by the new Lyapunov function approach. It is shown that the conservativeness of the obtained criteria can be further reduced as the degree of the Lyapunov function increases. Two numerical examples are given to demonstrate the effectiveness and less conservativeness of the obtained theoretical results. © 1993-2012 IEEE.


Ju S.,China University of Petroleum - East China | Chang Y.,China University of Petroleum - East China | Chen G.,China University of Petroleum - East China | Liu X.,China University of Petroleum - East China | And 2 more authors.
Shiyou Kantan Yu Kaifa/Petroleum Exploration and Development | Year: 2012

The common critical criterion and nonlinear search method were adopted for the study of connected operation envelopes of deepwater drilling platform and a riser-wellhead-conductor integral finite element model was established. The combination parameters of drilling platform offset, current speed and slip joint stroke were used to determine the riser operability envelopes. The results show that the drilling envelope has an upconing shape and is limited by lower flex joint angle when the surface current speed is low (less than 1.0 m/s). In downstream direction, when the current speed increases, the rotation angle of the lower flex joint increases and the allowable maximum offset of the platform reduces, but in upstream direction, the conditions will be opposite. When surface current speed exceeds 1.0 m/s, the drilling envelope is limited by upper flex joint angle. When it is in upstream direction, the increase of current flow will increase the rotor angle of the upper flexible joint and reduce the drilling envelope rapidly. The non-drilling envelope and emergency disconnect sequence (EDS) actuation envelope are mainly subject to the maximal equivalent stress of the conductor and they will drift towards the upstream direction with the increase of current speed. In addition, through the analysis on influence factors of connection window operation of riser, the tensile force at the top could be increased and drilling fluid density could be reduced properly, so that the drilling envelope could be expanded.


Zhu Z.,Shanghai University | Bai Y.-L.,Shanghai University | Zhang L.,China University of Petroleum - East China | Sun D.,China University of Petroleum - East China | And 2 more authors.
Chemical Communications | Year: 2014

Two rht anionic metal-organic frameworks were synthesized. There are six [M(H2O)6]2+ ions held together by a super-strong H-bond and arranged in a regular octahedron in each medium cage. Dye adsorption studies revealed a rapid and selective adsorption of cationic dyes and the adsorbed dyes can be released in saturated NaCl aqueous solution. This journal is © the Partner Organisations 2014.


Li C.P.,Shanghai University | Zhang F.R.,Shanghai University | Zhang F.R.,China University of Petroleum - East China
European Physical Journal: Special Topics | Year: 2011

Recently, fractional calculus has attracted much attention since it plays an important role in many fields of science and engineering. Especially, the study on stability of fractional differential equations appears to be very important. In this paper, a brief overview on the recent stability results of fractional differential equations and the analytical methods used are provided. These equations include linear fractional differential equations, nonlinear fractional differential equations, fractional differential equations with time-delay. Some conclusions for stability are similar to that of classical integer-order differential equations. However, not all of the stability conditions are parallel to the corresponding classical integer-order differential equations because of non-locality and weak singularities of fractional calculus. Some results and remarks are also included. © 2011 EDP Sciences and Springer.


Zhang M.,Zhangzhou Normal University | Zeng J.,China University of Petroleum - East China
Journal of Chromatographic Science | Year: 2013

This review focuses on a solid-phase microextraction (SPME) method coupled with molecularly imprinted polymers (MIPs), namely molecularly imprinted solid-phase microextraction (MISPME). The first two sections discuss the summaries of conventional SPME and MIPs. The third section reviews the development of MISPME in past years, including the preparation of MISPME, and the applications to compounds in real samples. © [2013] The Author.


Meng Y.-F.,China University of Petroleum - East China | Zhao D.-F.,China University of Petroleum - East China
Procedia Engineering | Year: 2011

At present, the design of chemical facility layout is always based on kinds of indicated codes, e.g. GB50160-2008 and GB50016-2006. There are many shortcomings of these codes, such as inflexible, lacking of comprehensive safety theory and ambiguous when applying to extra-large scale chemical plant and pilot plant. A performance-based framework was built for the safety design of chemical facility layout, which contains four key components: hazard identification, performance target confirmation, consequence assessment and defending effect evaluation. As the most important component of the framework, performance target confirmation was analyzed in particular, and a confirmation method was proposed through matching accident scenario and acceptable damage level of chemical facility. © 2011 Published by Elsevier Ltd.


Lei H.,Harbin Engineering University | Lei H.,University of Sydney | Wang Z.,Harbin Engineering University | Tong L.,University of Sydney | And 2 more authors.
Composite Structures | Year: 2013

This paper presents an experimental and numerical investigation into the macroscopic mechanical behavior of shape memory alloy hybrid composites (SMAHCs) subjected to quasi-static loading taking into account of weak interface effect and damage evolution. SMA fiber reinforced hybrid laminates were fabricated by vacuum assisted resin injection (VARI). Scanning electron microscopy was used to evaluate the quality of SMA-matrix interface. Uniaxial tensile tests were performed to study the effects of weak interface on the effective modulus of hybrid composite. Failure morphology was discussed based on the observation using digital HF microscope. Owing to the embedding of SMA fiber, the material exhibited a bilinear mechanical behavior, and the overall stiffness of composite at the second stage was lower on average 32.7% than that of the first stage. Ultimate strength was improved by 3.4% for the three-SMA-fiber composite, and rupture elongation was slightly decreased (∼0.1%). A script program was developed to generate the hybrid composite model by using ANSYS Parameter Design Language (APDL). Uniaxial tensile test was simulated using finite element method to study the macroscopic behavior of hybrid composite based on a bilinear cohesive zone model (BCZM). The effects of embedded SMA fiber number and fiber ratio were respectively discussed. © 2013 Elsevier Ltd.


Li X.J.,China University of Petroleum - East China | Xing W.,China University of Petroleum - East China | Zhou J.,Shandong University of Technology | Wang G.Q.,Shandong University of Technology | And 4 more authors.
Chemistry - A European Journal | Year: 2014

Three-dimensional hierarchical porous graphene/carbon composite was successfully synthesized from a solution of graphene oxide and a phenolic resin by using a facile and efficient method. The morphology, structure, and surface property of the composite were investigated intensively by a variety of means such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption, Raman spectroscopy, and Fourier transform infrared spectroscopy (FTIR). It is found that graphene serves as a scaffold to form a hierarchical pore texture in the composite, resulting in its superhigh surface area of 2034 m2g-1, thin macropore wall, and high conductivity (152 S m-1). As evidenced by electrochemical measurements in both EMImBF4 ionic liquid and KOH electrolyte, the composite exhibits ideal capacitive behavior, high capacitance, and excellent rate performance due to its unique structure. In EMImBF4, the composite has a high energy density of up to 50.1 Wh kg-1 and also possesses quite stable cycling stability at 100 °C, suggesting its promising application in high-temperature supercapacitors. In KOH electrolyte, the specific capacitance of this composite can reach up to an unprecedented value of 186.5 F g-1, even at a very high current density of 50 A g-1, suggesting its prosperous application in high-power applications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Zhao X.,China University of Petroleum - East China | Shi P.,Victoria University of Melbourne | Shi P.,University of Adelaide | Zhang L.,Harbin Institute of Technology
Systems and Control Letters | Year: 2012

The stabilization problem for a class of switched linear systems with average dwell time (ADT) switching is reinvestigated in this paper. State-feedback controllers are designed, which takes the more practical case, asynchronous switching, into account, where the so-called "asynchronous switching" indicates that the switchings between the controllers and the system modes are in the presence of a time delay. By combining the asynchronous switching, an improved stabilization approach is given, and existence conditions of the controllers associated with the corresponding ADT switching are formulated in terms of a set of linear matrix inequalities. A numerical example is given to show the validity and potential of the obtained theoretical results. © 2012 Elsevier B.V. All rights reserved.


Cao Y.G.,China University of Petroleum - East China | Zhang S.H.,China Institute of Technology
Engineering Failure Analysis | Year: 2013

Component analysis, metallographic examination and hardness test were performed respectively for a failed pinion and a new rack of the jacking system of a jack-up platform. Experiment results showed that the superficial heat treatment of the pinion was not uniform and there was no hardened layer at the tooth root. At the same time, the hardened layer near the pitch circle had been worn out for long-term service, thus the surface hardness of the failed pinion was lower than that of the rack. Considering that each pinion bears different load during service, the exact load that each pinion bears under the action of self-weight, variable loads and wind loads, was deduced firstly. As per the deduced bearing load of the failed pinion, elastic FEM analysis was performed and the distribution of stresses on the rack and pinion was simulated when the platform was under preload condition. By comparing the Von mises stresses and contact stresses with those calculated according to the formula, the accuracy of FEM analysis was verified. Then elastic-plastic FEM analysis was performed for pinion models with hardened layer and without hardened layer respectively, the results were used to explain the failure of the pinion. © 2013 Elsevier Ltd.


Chen S.,University of Adelaide | Xing W.,China University of Petroleum - East China | Duan J.,University of Adelaide | Hu X.,Hong Kong University of Science and Technology | Qiao S.Z.,University of Adelaide
Journal of Materials Chemistry A | Year: 2013

The fast growing interest in portable electronic devices and electric vehicles has stimulated extensive research in high performance energy storage devices, such as supercapacitors. Nanostructured electrodes can achieve high electrochemical performances in supercapacitors owing to their high surface atom ratio, tuneable texture and unique size-dependent properties that can afford effective electrolyte diffusion and improved charge transportation and storage during charging-discharging. This review reports on the recent progress in designing and fabricating different kinds of nanostructured electrodes, including electrical double layer based electrodes such as porous carbons and graphene, and Faradic reaction based electrodes such as metal oxides/hydroxides and conductive polymers. Furthermore, the review also summarizes the advances of hybrid electrodes, which store charges by both mechanisms, such as porous carbons-metal oxides/hydroxides, porous carbons-conductive polymers, graphene-metal oxides/hydroxides, and graphene-conductive polymers. Finally, we provide some perspectives as to the future directions of this intriguing field. © 2013 The Royal Society of Chemistry.


Yang G.,China University of Petroleum - East China | Wang Q.,National University of Singapore | Miao C.,China University of Petroleum - East China | Bu Z.,China University of Petroleum - East China | Guo W.,China University of Petroleum - East China
Journal of Materials Chemistry A | Year: 2013

We report in this paper a simple and cheap method for the preparation of ZnO microrod array/TiO2 nanoparticle hybrid films for applications in dye-sensitized solar cells (DSCs), which is achieved by screen printing TiO2 paste into the interspace of low-density ZnO microrod arrays grown on FTO glass. The as-fabricated DSCs exhibit a remarkably enhanced power conversion efficiency of 7.76%, higher than 6.57% for standard TiO2 nanoparticle based DSCs. The electrochemical impedance spectroscopy analysis reveals that the electron transport, electron lifetime, effective diffusion length and the electron collection efficiency are increased, while the charge recombination is reduced, indicating that the ZnO microrod array/TiO2 nanoparticle hybrid film can be considered as a superior material to TiO 2 nanoparticle in many respects. © 2013 The Royal Society of Chemistry.


Sun X.,Peking University | Sun G.,China University of Petroleum - East China
2nd International Workshop on Education Technology and Computer Science, ETCS 2010 | Year: 2010

This paper presents a new edge detection algorithm based on calculating the difference value of two clusters. An edge is defined as a boundary that separates two adjacent regions that are relatively homogenous. For each image pixel, a window is first defined by placing the pixel at the center, and this window is partitioned into two regions respectively in four different directions. An appropriate function is then selected to estimate the difference between each pair of two adjacent regions and to calculate edge information in terms of edge stretch and direction by maximizing the difference value. Finally, the non-maxima suppression is adopted to derive the output edge map. Experiments on a variety of noise contaminated images show that the new algorithm is more robust under noisy conditions. In addition, the proposed algorithm can also be applied to color or multi-spectral images. © 2010 IEEE.


Song M.,Guangdong University of Technology | Song M.,Hong Kong Polytechnic University | Chen A.,Nanyang Technological University | Mao N.,China University of Petroleum - East China
Applied Thermal Engineering | Year: 2016

For an air source heat pump (ASHP) unit with a vertically installed multi-circuit outdoor coil, it is rarely possible to make the frost accumulations on each circuit's surface equal, leading to different frosting evenness values (FEVs) as a reverse cycle defrosting operation starts. On the other hand, uneven defrosting phenomenon was found and reported as many methods were developed to improve defrosting performance of ASHP systems, which may be attributable to the reverse cycle defrosting starting at an uneven frosting. Understanding of defrosting performance of an ASHP unit with a multi-circuit outdoor coil at different FEVs is of importance for ASHP units' application, but studies are scarce in the open literatures. In this paper, we report an experimental study on defrosting performance when frost accumulated on the surface of outdoor coil at different FEVs. This paper presents details of an experimental ASHP unit and the experimental conditions, followed by results, and conclusions. Finally, an increase of 6.8% in defrosting efficiency was confirmed when the FEV changed from 82.6% to 96.6%. © 2015 Elsevier Ltd.


Kou J.,Zhejiang Normal University | Kou J.,China University of Petroleum - East China | Lu H.,Zhejiang Normal University | Wu F.,Zhejiang Normal University | And 2 more authors.
Nano Letters | Year: 2014

We performed molecular dynamics simulations to study water permeation through a single-walled carbon nanotube with electrical interference. It was found that the water net flux across the nanochannel is greatly affected by the external electrical interference, with the maximal net flux occurred at an electrical interference frequency of 16670 GHz being about nine times as high as the net flux at the low or high frequency range of (<1000 GHz or >80 000 GHz). The above phenomena can be attributed to the breakage of hydrogen bonds as the electrical interference frequency approaches to the inherent resonant frequency of hydrogen bonds. The new mechanism of regulating water flux across nanochannels revealed in this study provides an insight into the water transportation through biological water channels and has tremendous potential in the design of high-flux nanofluidic systems. © 2014 American Chemical Society.


Zhang Z.,Shandong University of Technology | Zhou J.,Shandong University of Technology | Xing W.,Shandong University of Technology | Xing W.,China University of Petroleum - East China | And 4 more authors.
Physical Chemistry Chemical Physics | Year: 2013

Microporous carbon materials with extremely small pore size are prepared by employing polyaniline as a carbon precursor and KOH as an activating agent. CO2 sorption performance of the materials is systematically investigated at the temperatures of 0, 25 and 75 °C. The prepared carbons show very high CO2 uptake of up to 1.86 and 1.39 mmol g-1 under 1 bar, 75 °C and 0.15 bar, 25 °C, respectively. These values are amongst the highest CO2 capture amounts of the known carbon materials. The relation between CO2 uptake and pore size at different temperatures is studied. An interesting and innovative point that the micropores with pore size smaller than a critical value play a crucial role in CO2 adsorption at different temperatures is demonstrated. It is found that the higher the sorption temperature is, the smaller this critical value of pore size is. Pores smaller than 0.54 nm are manifested to determine CO 2 capture capacity at high sorption temperature, e.g. 75 °C. This research proposes a basic principle for designing highly efficient CO 2 carbon adsorbents; that is, the adsorbents should be primarily rich in extremely small micropores. © 2013 the Owner Societies.


Li H.,China University of Petroleum - East China | Li H.,China National Offshore Oil Corporation | Chen D.,China University of Petroleum - East China | Meng H.,China University of Petroleum - East China
Shiyou Kantan Yu Kaifa/Petroleum Exploration and Development | Year: 2010

Aimed at the problems of bottom water coning, high cost of perforation and deterioration of casing tube, the optimized models of variable density perforation for horizontal wells are established after the study of the fluid flow model through porous medium, the perforation flow model, the pressure gradient model of well bore flow and the flow coupling model based on analyzing the production flow pressure dropdown of perforated horizontal wells. The inflow section of horizontal well production fluid can be regulated effectively by optimizing the density distribution of variable density perforation and bottom water coning can be prevented; variable density perforation can decrease the perforation density, so the cost of perforation and damage of casing also drop down; the initial perforation density, the viscosity of crude oil as well as the perforation condition of polluted zone has a prominent influence on the density distribution. The larger the initial perforation density, the larger the variation of perforation density; the larger the viscosity of crude oil, the smaller the variation of perforation density; the variation is bigger when the contamination zone is completely perforated than incomplete perforated. Also, the initial perforation density and the viscosity of crude oil also have a large effect on the bottom hole flowing pressure and the drop of pressure in well bore.


Zhang C.,Tianjin University | Lv W.,Tsinghua University | Zhang W.,Tianjin University | Zheng X.,Tianjin University | And 5 more authors.
Advanced Energy Materials | Year: 2014

Graphene oxide is effectively reduced by H2S and a graphene/sulfur hybrid is simultaneously obtained. The resulting graphene sheets interlink, forming a curly and porous structure that accompanies a uniform distribution of sulfur on the graphene sheets. The product is a promising electrode for Li-S batteries and provides a novel strategy for the removal of H2S. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Yu L.,Peking University | Yu L.,China University of Petroleum - East China | Yang C.,Peking University | Hou Y.,Peking University
Nanoscale | Year: 2014

It is extremely desirable but challenging to develop exchange-coupled magnets with well-dispersed hard/soft phase and confined size to meet the high energy requirements of advanced magnets in modern industry and information technology. Here, we report a novel bottom-up strategy with two-step thermal decomposition and reductive annealing process to synthesize Nd 2Fe14B/α-Fe nanocomposites, in which effective control of the hard/soft magnetic phase size and proportion was achieved. It is worth noting that the composition, as well as phase distribution, can be readily tuned by changing the ratio between Nd-Fe-B-oxide and α-Fe. This work provides an effective approach to adjust the phase size and distribution for exchange-coupled, rare-earth nanomagnets, which can be fundamental for high energy magnets. © the Partner Organisations 2014.


Xu L.,China National Offshore Oil Corporation | Chen G.,China University of Petroleum - East China
Shiyou Xuebao/Acta Petrolei Sinica | Year: 2010

It is very difficult to resolve the problem about the dynamic fatigue reliability control simultaneously considering randomness and fuzziness of offshore drilling platform. According to the fuzziness of inspection results and failure criterion, a new simple fuzzy model for the dynamic fatigue reliability control of offshore drilling platform was proposed on the basis of the minimum cost per unit operation time model. Fuzzy model reckons the time effects of the capital and the loss of the failure of offshore drilling platform with time. The conclusion can also be generalized to the platform system. An example illustrated the validation of the proposed method. The effect of fuzzy uncertainty is very important for getting the reasonable dynamic fatigue reliability control.


Zhao X.,Bohai University | Zhao X.,China University of Petroleum - East China | Zhang L.,Harbin Institute of Technology | Shi P.,University of Adelaide | And 2 more authors.
IEEE Transactions on Industrial Electronics | Year: 2014

In this paper, the problems of robust stability and stabilization are investigated for a class of continuous-time uncertain systems. The uncertainties in the model are state-dependent and belong to a polytopic convex set, as can be found in many electronic circuits and some other applications. The global asymptotic stability conditions for such systems are first established by the classic common quadratic Lyapunov function approach. To reduce conservativeness, a particular class of nonquadratic parameter-dependent Lyapunov functions is introduced, by which improved robust stability conditions for the underlying systems are also derived. Based on the stability criteria, a static output feedback controller is then designed for the system. The effectiveness of the proposed approaches is illustrated by a numerical example, and the applicability of our theoretical findings is simultaneously demonstrated by modeling, analysis, and control design for a class of electronic circuits. © 1982-2012 IEEE.


Zhang L.L.,National University of Singapore | Li S.,China University of Petroleum - East China | Zhang J.,National University of Singapore | Guo P.,Qingdao University | And 3 more authors.
Chemistry of Materials | Year: 2010

Conducting polymer-macroporous carbon composite electrode materials were prepared by deposition of a thin layer of polyaniline (PANI) on the surface of three-dimensionally ordered macroporous carbon. A specific capacitance of 1490 F/g was observed over the deposited PANI in the composite electrode. Good rate performance and cycle ability were realized on the composite electrode, attributed to the combined contribution from both the unique properties of the carbon matrix (e.g., highly ordered interconnected pores and good electrical conductivity) and pseudocapacitance of the deposited PANI layer. The three-dimensionally ordered pore structure of the carbon favored the diffusion of the electrolyte ions, hence not only improving the energy storage capacity but also enhancing power density. ©2009 American Chemical Society.


Yang G.,China University of Petroleum - East China | Miao C.,China University of Petroleum - East China | Bu Z.,China University of Petroleum - East China | Wang Q.,National University of Singapore | Guo W.,China University of Petroleum - East China
Journal of Power Sources | Year: 2013

We report in this paper a cheap and easy method for the preparation of ZnO nanowire/TiO2 nanoparticle hybrid films for applications in dye-sensitized solar cells (DSCs), which is achieved by post-embedding ZnO nanowires in mesoporous TiO2 film via a seed free low-temperature hydrothermal process. The electron transport and recombination properties in the as-fabricated DSCs are studied by using electrochemical impedance spectroscopy. Results indicate that the electron transport, electron lifetime, effective diffusion length and the electron collection efficiency are increased, while the charge recombination is reduced, resulting in the remarkably enhanced power conversion efficiency of 7.46%, higher than 6.09% of standard TiO2 nanoparticle based DSCs. © 2013 Elsevier B.V. All rights reserved.


Deng W.,China University of Petroleum - East China | Luo H.,China University of Petroleum - East China | Gao J.,Shandong Sunway Petrochemical Engineering Company Ltd | Que G.,China University of Petroleum - East China
Energy and Fuels | Year: 2011

Asphaltenes play a key role in the stability of the residue during processing. When asphaltenes reach their solubility limit in the residue, they would begin to aggregate, so that a new phase, called the mesophase, would separate from the oil phase, which eventually leads to coke formation. To relate coking characteristics, the changes in stability of the residue were studied during a slurry-phased hydrocracking reaction. The results indicated that the coke formation is obviously restrained by H2 and a catalyst such that the coke induction period is prolonged and the coke content is also reduced significantly compared to the coke content only in the presence of H 2. The colloidal stability parameters (CSPs) determined by means of flocculation onset titration and the colloidal stability function (CSF) calculated on the basis of saturate, aromatic, resin, and C7- asphaltene (SARA) composition of the residue have a similar variation trend, which could be related to coking characteristics. First, the coking onset and the maximum asphaltene content in the residue were in correspondence with the turning point in the downward trend of the stability of the residue. The stability of the residue deteriorated significantly during the coke induction period, and the decreased trend tended to smooth after the coking onset point. Second, it is confirmed that the downward trend of stability is inhibited effectively in the presence of H2 and a catalyst, so that the ability of the residue against thermal disturbance is enhanced to reduce the coke formation. The changes in structure parameters of asphaltenes also showed that the catalyst could inhibit or delay the excessive condensations of asphaltenes to reduce the coke formation. © 2011 American Chemical Society.


Xing W.,Shandong University of Technology | Liu C.,Shandong University of Technology | Zhou Z.,Shandong University of Technology | Zhang L.,CAS Dalian Institute of Chemical Physics | And 6 more authors.
Energy and Environmental Science | Year: 2012

Here we show that the introduction of N into a carbon surface facilitates the hydrogen-bonding interactions between the carbon surface and CO2 molecules, which accounts for the superior CO2 uptake of the N-doped activated carbons. This new finding challenges the long-held viewpoint that acid-base interactions between N-containing basic functional groups and acidic CO2 gas are responsible for the enhanced CO2 capture capacity of N-doped carbons. This journal is © 2012 The Royal Society of Chemistry.


Song M.,Guangdong University of Technology | Song M.,Hong Kong Polytechnic University | Wang Z.,Xi'an Jiaotong University | Mao N.,China University of Petroleum - East China | And 2 more authors.
Applied Thermal Engineering | Year: 2015

For an air source heat pump (ASHP) unit with a vertically installed multi-circuit outdoor coil, many parameters would affect system defrosting performance, especially the uneven distribution of refrigerant for each circuit and downwards flowing of melted frost due to gravity from up circuit(s) to down circuit(s). Currently, the negative effects of melted frost have been demonstrated and quantitatively studied, without however giving a fundamental study on the effects of uneven refrigerant distribution due to gravity and tube internal resistance for an ASHP unit with a vertically installed multi-circuit outdoor coil. Therefore, an experimental study on system defrosting performance when refrigerant was evenly or unevenly distributed into each circuit has been carried out and a comparative and quantitative analysis conducted using the experimental data. In this paper, the negative effects of refrigerant uneven distribution on system defrosting performance were demonstrated and an increase of 6.9% in defrosting efficiency when refrigerant evenly distributed, compared with the case of refrigerant unevenly distributed, was reported. © 2015 Elsevier Ltd. All rights reserved.


Wu X.,China University of Petroleum - East China | Wu X.,Shandong University of Technology | Zhou J.,Shandong University of Technology | Xing W.,China University of Petroleum - East China | And 7 more authors.
Journal of Materials Chemistry | Year: 2012

Graphene aerogel (GA) is successfully prepared through hydrogen reduction of graphene oxide aerogel (GOA) which is self-assembled from graphene oxide solution and subsequently dried by a supercritical CO 2 method. The morphology, structure and surface property evolution in the preparation of GA are investigated intensively by a variety of means such as atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), N 2 adsorption, X-ray diffraction (XRD), Raman spectroscopy, ultraviolet-visible absorption spectroscopy (UV-Vis), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR). A self-assembly mechanism based on the hydrogen-bonding interactions between hydroxyl groups and carbonyl groups is proposed for the first time to explain the formation of GA. As evidenced by elemental analysis (EA) and electrochemical measurements, this three dimensional GA has an unprecedented high C/O molar ratio of 69.9, which contributes to the excellent high-rate performance of this material for supercapacitor applications. © 2012 The Royal Society of Chemistry.


Yin X.-Y.,China University of Petroleum - East China | Zhang S.-X.,China National Offshore Oil Corporation | Zhang F.,China University of Petroleum - Beijing
Chinese Journal of Geophysics (Acta Geophysica Sinica) | Year: 2013

Russell fluid factor is a sensitive indicator for deep reservoir fluid identification. Considering that the seismic data of deep reservoir is lack of large angle information and has low signal-noise-ratio, the Bayesian-based two term elastic impedance inversion and Russell fluid factor direct estimation method are carried out. Firstly, based on the saturated poroelastic media theory, we derive the two term reflection coefficient approximation in terms of Russell fluid factor and P-wave impedance, using which we get the new equation of elastic impedance containing the Russell fluid factor. Secondly, we analyze the precision and applicable condition of the new elastic impedance and the model test shows that it can satisfy the accuracy of small angle incidence. Finally, the Bayesian-based elastic impedance inversion and Russell fluid factor estimation procedure is introduced, the model tests illustrate that the direct estimation method can take full advantage of elastic impedance inversion to have high signal-noise-ratio and practicability, and furthermore, the direct estimation method can diminish negative effect of accumulative error. The real application shows that the direct estimated Russell fluid factor raise the reliability of the deep reservoir fluid identification.


Yang C.,Nanjing University of Posts and Telecommunications | Yang C.,China University of Petroleum - East China
Computers and Mathematics with Applications | Year: 2015

We present an almost optimal error estimate for the finite element solution of a nonlinear parabolic interface problem, where the coefficient depends on the unknown variable and is discontinuous along an interface inside the computational domain. A linearized second-order backward difference formula is used for the time discretization, and piecewise linear interpolation is used to approximate the interface. We do not assume Lipschitz continuity of the nonlinear coefficient. © 2015 Elsevier Ltd. All rights reserved.


Yin X.,China University of Petroleum - East China | Zhang S.,China National Offshore Oil Corporation
Geophysics | Year: 2013

Fluid indicators estimated fromseismic data play important roles in reservoir characterization and prospect identification. Traditionally, there are a variety of fluid indicators proposed, but they are very likely to provide ambiguous results for fluid identification due to the fact that their sensitivity is dependent upon the mixed effect of pore fluid and rock porosity. To raise the sensitivity of fluid indication, we used the effective porefluid bulk modulus as a fluid indicator. Starting with the poroelastic amplitude variation with offset (AVO) theory and the corresponding rock-physics model with the homogeneous sorting trend, we derived a new AVO approximation that allowed us to estimate the effective pore-fluid bulkmodulus in a direct fashion. The inversion for the fluid indicator is formulated in Bayesian framework with the Cauchy distribution as a prior constraint. We tested the method on synthetic data and analyzed the feasibility and stability of the inversion. A field data example shows that the effective pore-fluid bulk modulus can reduce the ambiguity caused by the rock porosity and improve the quality of fluid discrimination in a clastic reservoir. Further research needs to be done on the reservoirs that do not fit the rock-physics model without a sorting trend. © 2014 Society of Exploration Geophysicists.


Patent
Dongfang Hongsheng New Energy Application Technology Research Institute Co., Jiangsu Kaimao Chemical Technology Co. and China University of Petroleum - East China | Date: 2015-12-10

The present invention pertains to the technical field of energy resource chemical industry, and in particular relates to a process for producing polyoxymethylene dimethyl ethers by directly using concentrated formaldehyde aqueous solution as feedstock to catalytically react with methanol and/or methylal in a fixed bed reactor. The method of the present invention uses concentrated formaldehyde aqueous solution with a concentration of over 80% by weight to react with methanol and/or methylal, in the presence of an acidic catalyst, to produce the required polyoxymethylene dimethyl ethers. As compared with using paraformaldehyde powder as feedstock, the method of the present invention accelerates the depolymerization process of paraformaldehyde, thus significantly reduces the time required for product synthesis and makes the synthesis reaction able to be carried out in a fixed bed reactor; meanwhile, as compared with using formaldehyde aqueous solution with a low concentration as feedstock, the method of the present invention also significantly increases the yield rate of the target product.


Sun Q.,University of Queensland | Wang M.,China University of Petroleum - East China | Li Z.,University of Wollongong | Ma Y.,Chengdu University of Technology | Du A.,Queensland University of Technology
Chemical Physics Letters | Year: 2013

Concern about the increasing atmospheric CO2 concentration and its impact on the environment has led to increasing attention directed toward finding advanced materials and technologies suited for efficient CO2 capture, storage and purification of clean-burning natural gas. In this letter, we have performed comprehensive theoretical investigation of CO2, N2, CH4 and H2 adsorption on B2CNTs. Our study shows that CO2 molecules can form strong interactions with B2CNTs with different charge states. However, N2, CH 4 and H2 can only form very weak interactions with B 2CNTs. Therefore, the study demonstrates B2CNTs could sever as promising materials for CO2 capture and gas separation. © 2013 Elsevier B.V. All rights reserved.


Xu H.J.,Shanghai JiaoTong University | Xu H.J.,China University of Petroleum - East China | Zhao C.Y.,Shanghai JiaoTong University | Xu Z.G.,Shanghai JiaoTong University
Applied Thermal Engineering | Year: 2016

Forced convection in a mini/microchannel filled with microfoam is analytically studied in the condition of uniform but asymmetrical heat fluxes. Velocity slip, thermal slip, local thermal non-equilibrium (LTNE) effect, and asymmetric heat fluxes imposed on the two parallel-plates sandwiching the microfoams are especially considered. For two walls with different heat fluxes, solid and fluid temperatures at the boundary are equal to each other based on self-coupling conditions. Explicit expressions for velocity and temperatures of solid and fluid are derived and the analytical solution agrees well with existing references. This solution can predict velocity, temperatures, friction loss and thermal performance of porous microchannel for wide ranges of Knudsen number and HF ratio. With the increased Knudsen number, the friction factor gradually decreases and the decreasing amplitude in slip flow region is very large. With the increased shape factor, the dimensionless pressure drop sharply decreases for small shape factor, while its value gradually approaches 1 for large shape factor. A maximum Nusselt number exists with the increase in Knudsen number. Heat transfer can be enhanced by increasing effective Biot number or decreasing thermal conductivity ratio. The analytical solution is symmetrical on the axis ξσ=σ1 in the region 0σ<σξσ<σ+∞. © 2015 Elsevier Ltd. All rights reserved.


Yin X.,China University of Petroleum - East China | Hutchins D.A.,University of Warwick | Chen G.,China University of Petroleum - East China | Li W.,China University of Petroleum - East China
NDT and E International | Year: 2012

This paper describes the application of the capacitive imaging (CI) technique to the detection of surface features on conducting specimens. The fundamental theory of the CI technique was briefly described. Comparison was made between the CI technique and the eddy current approach. A two-dimensional finite-element method was employed to model the electric field distribution from the CI probe, and how it interacts with conducting specimens through an insulation layer. Experiments using prototype CI probes were carried out. Effects of electrical conditions of the conducting specimen, lift-off distances and thicknesses of insulation between the CI probe and the conducting specimen were studied. The proof-of-concept results indicated that the CI technique is sensitive to surface features on conducting specimens through a significant air gap and/or insulation layer, thus could be used to detect Corrosion Under Insulation (CUI). © 2012 Elsevier Ltd.


Huang X.-G.,China University of Petroleum - East China | Xu J.-Q.,Shanghai JiaoTong University
Journal of Zhejiang University: Science A | Year: 2013

This paper presents a deterministic model to predict the pit evolving morphology and crack initiation life of corrosion fatigue. Based on the semi-ellipsoidal pit assumption, the thermodynamic potential including elastic energy, surface energy and electrochemical energy of the cyclically stressed solid with an evolving pit is established, from which specific parameters that control the pit evolution are introduced and their influence on the pit evolution are evaluated. The critical pit size for crack nucleation is obtained from stress intensity factor criterion and the crack nucleation life is evaluated by Faraday's law. Meanwhile, this paper presents a numerical example to verify the proposed model and investigate the influence of cyclic load on the corrosion fatigue crack nucleation life. The corrosion pit appears approximately as a hemisphere in its early formation, and it gradually transits from semicircle to ellipsoid. The strain energy accelerates the morphology evolution of the pit, while the surface energy decelerates it. The higher the stress amplitude is, the smaller the critical pit size is and the shorter the crack initiation life is. © 2013 Zhejiang University and Springer-Verlag Berlin Heidelberg.


An C.,Universities of Shandong | Wang J.,Universities of Shandong | Qin C.,Universities of Shandong | Jiang W.,Universities of Shandong | And 3 more authors.
Journal of Materials Chemistry | Year: 2012

Heterostructured Ag@AgBr/AgCl nanocashews have been synthesized by an anion-exchange reaction between AgCl nanocubes and Br - ions followed by photoreduction. Compared to polyhedral Ag@AgBr nanoparticles, the obtained nanostructures exhibit enhanced photocatalytic activity towards decomposition of organic pollutants, i.e., rhodamine-B (RhB). For example, only 2 min is taken to completely decompose RhB molecules with the assistance of these novel heterostructured nanoparticles under visible light irradiation. Furthermore, the as-synthesized nanocatalyst can be reused 20 times without losing activity, showing its high stability. Interestingly, the novel heterostructured Ag@AgBr/AgCl nanophotocatalyst also shows efficient visible light conversion of CO 2 to energetic fuels, e.g. methanol/ethanol. Therefore, the present route opens an avenue to achieve highly efficient visible-light-driven nanophotocatalysts for applications in environmental remediation and resourceful use of CO 2. © 2012 The Royal Society of Chemistry.


Liu Z.,China University of Petroleum - East China | Liu Z.,Universities of Shandong | Xue Q.,China University of Petroleum - East China | Xue Q.,Universities of Shandong | And 3 more authors.
Nanoscale | Year: 2013

We demonstrate by molecular dynamic (MD) simulations that patterned partially hydrogenated graphene (C4H) can self-assemble at room temperature. The main driving force of the self-assembly of C4H is due to the one-sided distribution of hydrogen and the corresponding asymmetric orientation of sp3 bonding, there exists strong electrostatic repulsion between the relatively close H atoms. The simulations show that C 4H can self-assemble into various carbon nanoscroll (CNS) structures, this is mainly controlled by its geometry (size and aspect ratio). And the carbon nanotube (CNT) is a good candidate to activate and guide C4H to form CNS, whose core size can be controlled. Meanwhile, a novel CNT/C 4H core/shell composite nanostructure is also formed. The theoretical results shed important light on a feasible approach to fabricate high-quality CNS and other novel nanostructures including core/shell structures, which hold great potential applications in optics, optoelectronic devices, hydrogen storage, sensors, and energy storage in supercapacitors or batteries. © 2013 The Royal Society of Chemistry.


Yin X.,China University of Petroleum - East China | Hutchins D.A.,University of Warwick | Chen G.,China University of Petroleum - East China | Li W.,China University of Petroleum - East China
NDT and E International | Year: 2013

In this paper, the measurement sensitivity distributions of coplanar capacitive imaging probes are studied. An equation to calculate measurement sensitivity distribution of a coplanar capacitive sensor was derived. The measurement sensitivity distribution of a coplanar capacitive imaging (CI) probe with two back-to-back triangular electrodes was obtained both from finite element (FE) models and experiment. The effects of specimen under test on the measurement sensitivity distribution were discussed. The measurement sensitivity distribution is useful to evaluate the imaging ability of coplanar capacitive probes with different design parameters and to retrieve the actual shape of the targeted feature. The concept of negative sensitivity has also been introduced, and experiments were also performed so as to verify the existence of negative sensitivity. © 2013 Elsevier Ltd.


Ge H.,Tongji University | Zhang C.L.,Tongji University | Zhang C.L.,University of Georgia | Dang H.,China University of Petroleum - East China | And 2 more authors.
Geoscience Frontiers | Year: 2013

Archaea have unique glycerol dialkyl glycerol tetraether (GDGT) lipids that can be used to develop paleotemperature proxies such as TEX86. This research is to validate proposed GDGT-proxies for paleotemperature determination in the South China Sea (SCS). Samples were collected from core-top sediments (0-5 cm) in the northern SCS. Total lipids were extracted to obtain core GDGTs, which were identified and quantified using liquid chromatography-mass spectrometry (LC-MS). The abundance of isoprenoidal GDGTs (iGDGTs) ranged from 271.5 ng/g dry sediment to 1266.3 ng/g dry sediment, whereas the branched GDGTs (bGDGTs), supposedly derived from terrestrial sources, ranged from 22.2 ng/g dry sediment to 56.7 ng/g dry sediment. The TEX86-derived sea surface temperatures ranged from 20.9 °C in the coast (water depth < 160 m) to 27.9 °C offshore (water depth > 1000 m). TEX86-derived temperatures near shore (<160 m water depth) averaged 23.1 ± 2.5 °C (n = 4), which were close to the satellite-derived winter mean sea surface temperature (average 22.6 ± 1.0 °C, n = 4); whereas the TEX86-derived temperatures offshore averaged 27.4 ± 0.3 °C (n = 7) and were consistent with the satellite mean annual sea surface temperature (average 26.8 ± 0.4 °C, n = 7). These results suggest that TEX86 may record the sea surface mean annual temperature in the open ocean, while it likely records winter sea surface temperature in the shallower water. © 2012, China University of Geosciences (Beijing) and Peking University. Production and hosting by Elsevier B.V. All rights reserved.


Zhang Z.,China University of Petroleum - East China | Wang K.,China University of Petroleum - East China | Atkinson J.D.,University of Illinois at Urbana - Champaign | Yan X.,China University of Petroleum - East China | And 3 more authors.
Journal of Hazardous Materials | Year: 2012

Nitrogen-containing porous carbon was synthesized from an ocean pollutant, Enteromorpha prolifera, via hydrothermal carbonization and potassium hydroxide activation. Carbons contained as much as 2.6% nitrogen in their as-prepared state. Physical and chemical properties were characterized by XRD, N2 sorption, FTIR, SEM, TEM, and elemental analysis. The carbon exhibited a hierarchical structure with interconnected microporosity, mesoporosity and macroporosity. Inorganic minerals in the carbon matrix contributed to the development of mesoporosity and macroporosity, functioning as an in situ hard template. The carbon manifested high CO2 capacity and facile regeneration at room temperature. The CO2 sorption performance was investigated in the range of 0-75°C. The dynamic uptake of CO2 is 61.4mg/g and 105mg/g at 25°C and 0°C, respectively, using 15% CO2 (v/v) in N2. Meanwhile, regeneration under Ar at 25°C recovered 89% of the carbon's initial uptake after eight cycles. A piecewise model was employed to analyze the CO2 adsorption kinetics; the Avrami model fit well with a correlation coefficient (R2) of 0.98 and 0.99 at 0°C and 25°C, respectively. © 2012 Elsevier B.V.


Sun Q.,University of Queensland | Wang M.,University of Queensland | Wang M.,China University of Petroleum - East China | Li Z.,University of Wollongong | And 3 more authors.
Journal of Physical Chemistry C | Year: 2014

Exploring advanced materials for efficient capture and separation of CO2 is important for CO2 reduction and fuel purification. In this study, we have carried out first-principles density functional theory calculations to investigate CO2, N2, CH4, and H2 adsorption on the amphoteric regioselective B80 fullerene. Based on our calculations, we find that CO2 molecules form strong interactions with the basic sites of the B80 by Lewis acid-base interactions, while there are only weak bindings between the other three gases (N2, CH4, and H2) and the B 80 adsorbent. The study also provides insight into the reaction mechanism of capture and separation of CO2 using the electron deficient B80 fullerene. © 2014 American Chemical Society.


Liu J.-L.,China University of Petroleum - East China | Xia R.,Key Laboratory of Transients in Hydraulic Machinery | Zhou Y.-T.,Yonsei University
Chinese Physics Letters | Year: 2011

Nanowire stiction is a crucial bottleneck for the development of M/NEMS devices. We present a model of a nano-beam stuck to the substrate in consideration of both surface elasticity and residual surface stress. The critical detachment length can be derived from the transversality condition using the variational method. The effects of the surface parameters on the adhesion of the nano-beam are discussed in detail. These analyses provide some suggestions for engineers in the design and fabrication of more accurate M/NEMS instruments. © 2011 Chinese Physical Society and IOP Publishing Ltd.


Xu H.J.,Shanghai JiaoTong University | Xu H.J.,China University of Petroleum - East China | Zhao C.Y.,Shanghai JiaoTong University
Energy | Year: 2015

CHS (cascaded heat storage) plays a significant role in the improvement of thermal efficiency and the utilization of multi-graded thermal energies. This work presents thermodynamic modeling of the CHS for direct thermal utilization purpose with the lumped parameter method employed for the PCMs. The optimization of temperatures of HTF (heat transfer fluid) and multistage PCMs (phase change materials) is performed based on the entransy theory. Analytical solutions for optimal temperatures of HTF and PCMs are obtained with heat optimization for fixed entransy dissipation and entransy optimization for fixed heat. The existence conditions of the two optimizations are put forward with corresponding critical stage numbers proposed. The results show that CHS can extend applicable temperature scope for multigraded thermal energies. Heat transfer enhancement is essential for multistage heat storage. The uniform distribution of parameter C in each stage is beneficial for thermal efficiency improvement. The present thermodynamic optimization and solutions can guide the selection of PCMs, and establish a benchmark for similar research in CHS. © 2015 Elsevier Ltd.


Shi Y.,China University of Petroleum - East China | Liu Y.,China University of Petroleum - East China | Yi P.,China University of Petroleum - East China | Hu J.,Shanghai JiaoTong University
Optics and Laser Technology | Year: 2012

In a laser forming process, different forming mechanisms have different deformation behaviors. The aim of laser forming is to acquire plane strain under an upsetting mechanism, while a plate undergoes a small bending deformation. In some industrial applications, the bending strain should not occur. To achieve high-precision forming, the deformation behaviors of a metal plate when an upsetting mechanism plays a dominant role are studied in the paper. Several heating methods are proposed to reduce the plane strain difference along the thickness direction and little bending deformation resulting from a small temperature difference between the top and bottom surfaces of the plate. The results show that negligible bending deformation and a uniform plastic plane strain field can be obtained by simultaneously heating the top and bottom surfaces with the same process parameters. A conventional scanning method needs a larger spot diameter and slower scanning speed under the upsetting mechanism, but a smaller spot diameter and quicker scanning speed may be selected using the simultaneous heating method, which can greatly widen the potential scope of process parameters. © 2011 Elsevier Ltd. All rights reserved.


An C.,University of Illinois at Urbana - Champaign | An C.,China University of Petroleum - East China | Peng S.,Argonne National Laboratory | Sun Y.,Argonne National Laboratory
Advanced Materials | Year: 2010

Figure Equotion Present Highly efficient plasmonic photocatalysts of AgCl:Ag hybrid nanoparticles are successfully synthesized via a one-pot synthetic approach involving a precipitation reaction followed by polyol reduction. The as-synthesized nanoparticles exhibit high catalytic performance under visible light and sunlight for decomposing organics, such as methylene blue. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Zhao D.,Shanghai JiaoTong University | Zhao D.,China University of Petroleum - East China | Li S.,Shanghai JiaoTong University | Zhu Q.,University of the West of England | Gao F.,Shanghai JiaoTong University
IET Control Theory and Applications | Year: 2010

In this study, a new robust finite-time stability control approach for robot systems is developed based on finite-time Lyapunov stability principle and proved with backstepping method. The corresponding stability analysis is presented to lay a foundation for theoretical understanding to the underlying design issues as well as safe operation for real systems. A case study of a two-link robot model is presented to demonstrate the effectiveness of the proposed approach. © 2010 The Institution of Engineering and Technology.


Zhao X.,Bohai University | Zhao X.,China University of Petroleum - East China | Liu H.,Harbin Institute of Technology | Zhang J.,Shanghai JiaoTong University | Li H.,Bohai University
IEEE Transactions on Automation Science and Engineering | Year: 2015

In this paper, the problems of state estimation are investigated for switched linear systems with average dwell time (ADT) switching in both continuous-time and discrete-time contexts. First, a set of mode-dependent Luenberger-type observers is designed subject to the ADT switching that is synchronous with the switching of the estimated systems. Then, a more practical case of the delayed observers is also considered, which implies that the switching of the multiple-mode observer to be designed has a lag to the switching of the estimated systems. In this case, the asynchronous switching signals are combined as a preliminary attempt, upon which sufficient conditions for the existence of the Luenberger-type observers and the corresponding ADT switching are formulated in terms of a set of linear matrix inequalities. Finally, the proposed approaches are applied to the state estimation of electronic circuits to demonstrate the effectiveness and applicability. © 2004-2012 IEEE.


Yin X.,China University of Petroleum - East China | Hutchins D.A.,University of Warwick
Composites Part B: Engineering | Year: 2012

This paper describes the application of the capacitive imaging technique to the inspection of composite materials. The fundamental theory of the capacitive imaging technique was briefly described. Experiments using prototype capacitive imaging probes were also carried out. The proof-of-concept results indicated that the capacitive imaging technique could be used to detect cracks and delaminations in the glass fibre composite, defects in the aluminium core through the glass fibre face as well as surface features on the carbon fibre specimens. © 2011 Elsevier Ltd. All rights reserved.


Zhao D.,China University of Petroleum - East China | Li S.,Shanghai JiaoTong University | Zhu Q.,University of the West of England
Proceedings of the 30th Chinese Control Conference, CCC 2011 | Year: 2011

In this study, a new adaptive synchronized tracking control approach is developed for the operation of multiple robotic manipulators systems in the presence of uncertain kinematics and dynamics. In terms of the system synchronization theory and adaptive control principle, the proposed approach can stabilize position tracking of each robotic manipulator while coordinating its motion with others. Due to designing novel kinematic and dynamic adaptive laws, the proposed approach can cope with kinemaic and dynamic uncertainties effectively. A systematical and solid theoretical analysis is presented to lay a foundation for theoretical understanding to the underlying issues as well as safely operating real systems. Finally, an illustrative example is bench tested to validate the effectiveness of the proposed approach. © 2011 Chinese Assoc of Automati.


Ma C.,Shanghai JiaoTong University | Bu Y.,China University of Petroleum - East China | Chen B.,Shanghai JiaoTong University
Construction and Building Materials | Year: 2014

In this article, a new type of graft copolymer retarder as modified phosphoaluminate cement (MPC) has been discussed. Graft copolymerization of 2-acrylamido-2-methyl propane sulfonic acid (AMPS) and itaconic acid (IA) onto sodium lignosulfonate (LS) was performed using potassium persulfate as an initiator by free radical aqueous solution copolymerization. The optimal LS/AMPS/IA copolymer (OLSAI) was obtained under the optimum reaction conditions: mass ratio of LS/(AMPS + IA) = 1:1, temperature = 60 C, mole ratio of AMPS/IA = 9:1, initiator concentration = 1%, pH value = 5. The synthesized copolymer OLSAI was characterized by FTIR analysis. The experimental results demonstrate that the OLSAI has excellent retarding ability, dispersing power, thermal-resistant and pressure-tolerant properties, and little negative impact on the compressive strength of MPC. The graft copolymer OLSAI is expected to be an excellent retarder for MPC. © 2014 Elsevier Ltd. All rights reserved.


Zhao D.,China University of Petroleum - East China | Zou T.,Zhejiang University of Technology | Li S.,Shanghai JiaoTong University | Zhu Q.,China University of Petroleum - East China | Zhu Q.,University of the West of England
IET Control Theory and Applications | Year: 2012

Facing the critical challenge in coordination control and uncertainty encountered in leader-follower multi-agent systems, this study proposes a new adaptive backstepping sliding mode control approach in light of integration of the advantages of backstepping and sliding mode control principles. A systematic controller design procedure is proposed with step-by-step implement details. Correspondingly, the stability analysis is presented to lay a foundation for analytical understanding in generic theoretical aspects and safe operation in real systems. Two simulated examples are selected to bench test the effectiveness and efficiency of the proposed approach. © 2012 The Institution of Engineering and Technology.


Zhao D.,China University of Petroleum - East China | Zhu Q.,China University of Petroleum - East China | Zhu Q.,University of the West of England | Li N.,Shanghai JiaoTong University | Li S.,Shanghai JiaoTong University
Neurocomputing | Year: 2014

In this paper, a new neural network enhanced synchronized control approach is proposed for multiple robotic manipulators systems (MRMS) based on the leader-follower network communication topology. The justification of introducing two adaptive Radial Basis Function Neural Networks (RBF NN), also called neuro-agents, is to facilitate the whole control system design and analysis. Otherwise such design is impossible with classical analytical procedure. The first agent is the neuro-compensator to accommodate uncertainty associated with the follower manipulators, and the second agent is the neuro-estimator to obtain acceleration of the leader manipulator. Correspondingly the stability analysis of the designed control system is formulated with Lyapunov method. Finally numerical bench tests under various critical conditions are conducted to validate the effectiveness of the proposed approach. © 2013 Elsevier B.V.


Yang C.,CAS Wuhan Institute of Rock and Soil Mechanics | Jing W.,CAS Wuhan Institute of Rock and Soil Mechanics | Jing W.,China University of Petroleum - East China | Daemen J.J.K.,University of Nevada, Reno | And 2 more authors.
Reliability Engineering and System Safety | Year: 2013

Salt rock is internationally accepted as an ideal medium for energy storage. As an energy storage structure, the safety of hydrocarbon storage caverns in salt rock is related to the national economy and to social public security. Risk analysis is an important method of engineering safety evaluation. In this paper the major risks associated with hydrocarbon storage caverns in bedded salt rock are defined. The major risks are classified under the headings of 'oil and gas leakage', 'ground subsidence', and 'cavern failure', and are discussed under these topical titles. The factors leading to the major risks associated with storage caverns are identified by reviewing descriptions of major accidents of salt storage caverns around the world. Fault tree models for the three major risks are established and analyzed. Basic paths of the risk and their occurrence probability ranking are derived. The risk factors which contribute greatly to the risk are identified by calculating the importance degree of all the basic events. Finally, a comprehensive evaluation methodology for major risk loss is generated based on the analytic hierarchy process. This provides a theoretical foundation for the evaluation and prevention of major risks in the construction and operation of storage caverns in bedded salt rock. © 2013 Elsevier Ltd. All rights reserved.


Long X.,Hong Kong University of Science and Technology | Li G.,China University of Petroleum - East China | Wang Z.,Hong Kong University of Science and Technology | Zhu H.,China University of Petroleum - East China | And 4 more authors.
Journal of the American Chemical Society | Year: 2015

We report on the synthesis of iron-nickel sulfide (INS) ultrathin nanosheets by topotactic conversion from a hydroxide precursor. The INS nanosheets exhibit excellent activity and stability in strong acidic solutions as a hydrogen evolution reaction (HER) catalyst, lending an attractive alternative to the Pt catalyst. The metallic α-INS nanosheets show an even lower overpotential of 105 mV at 10 mA/cm2 and a smaller Tafel slope of 40 mV/dec. With the help of DFT calculations, the high specific surface area, facile ion transport and charge transfer, abundant electrochemical active sites, suitable H+ adsorption, and H2 formation kinetics and energetics are proposed to contribute to the high activity of the INS ultrathin nanosheets toward HER. © 2015 American Chemical Society.


Chu L.,China University of Petroleum - East China | Xue Q.,China University of Petroleum - East China | Sun J.,China University of Petroleum - East China | Xia F.,China University of Petroleum - East China | And 3 more authors.
Composites Science and Technology | Year: 2013

A novel sandwich structure based on few-layer graphene nanosheets (FLGs) composed of functionalized porous graphene, pristine graphene and functionalized porous graphene is proposed. After one-step alkaline-mediated hydrothermal treatment, the outmost layers of FLGs are etched to porous structure. Sandwich FLGs/poly(vinylidene fluoride) (PVDF) composites are fabricated and the composites show excellent dielectric properties among carbon-based fillers/PVDF composites. Owing to the unique semiconductor/conductor/semiconductor structure, theoretical analysis indicates that the dielectric constant of the sandwich FLGs/PVDF composites can be as high as 105. Our findings provide a novel strategy to fabricate high dielectric performance graphene based composites and the process is simple, low-cost and environmentally friendly. © 2013 Elsevier Ltd.


Li A.,China University of Petroleum - East China | Liu P.,Beihang University
Journal of Hydraulic Research | Year: 2010

Scour of rock bed downstream of high dams ismainly caused by the transient forces as a result of the propagation of fluctuating pressures, which is significantly controlled by the rock fracture-structure. The physical mechanism of rock disintegration and scour pool forming are analysed herein by considering the fracture- structure of rock bed. A two-dimensional discrete fracture network is imitated applying the Monte-Carlo method. The model of transient flow is established along with each discrete fracture to simulate numerically the propagation of fluctuating pressure waves. Applying the method of automatic tracing of rock blocks layer by layer, the mechanism of disorganization of fractured rock, both the transient physical and dynamic characteristics of isolated rocks, and the damage process of the rock bed are discussed. Finally, a stability criterion of rock blocks and the evaluationmethod of equilibrium scour depth are established. © 2010 International Association for Hydro-Environment Engineering and Research.


Gao M.,Shandong University of Science and Technology | Sheng L.,China University of Petroleum - East China
Xi Tong Gong Cheng Yu Dian Zi Ji Shu/Systems Engineering and Electronics | Year: 2011

The stability and stabilization problem for a class of continuous-time Markov jump singular systems is investigated. A sufficient condition is proposed for the Markov jump singular system to be regular, impulse-free and stochastically stable, and the design of the stabilizing controller is presented. Comparing with the previous literature, the system under consideration is more general since their transition probabilities of mode jumps can be partly unknown, and the results are presented in terms of a strict linear matrix inequality. A numerical example shows the effectiveness of the obtained result.


Zhang H.,China University of Petroleum - East China | Wang P.,China University of Petroleum - East China | Han B.,Beihang University
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2014

On account of the features of the high speed permanent magnet synchronous motor which has a high speed and a wide speed range, this paper proposes a kind of rotor position observer which is model reference adaptive system (MRAS) based on fuzzy PI self-adaptive regulator. This method uses the fuzzy controller regulate the proportion and the integration ratio of the PI regulator, so that the PI regulator has a perfect performance in a wide speed range of the HSPMSM. This method improves the precision of the rotor's position which is observed by MRAS. In the end, simulations and experiments for a 4 kW HSPMSM with an air blower are carried out for this method. It realizes the position estimation. The error is analyzed and a compensation method is proposed. The results demonstrate that the Fuzzy PI MRAS Observer can effectively estimate the rotor position of the HSPMSM in a wide speed range. © 2014 Chin. Soc. for Elec. Eng.


Li S.,Nanjing Southeast University | Wang Z.,Nanjing Southeast University | Wang Z.,China University of Petroleum - East China | Fei S.,Nanjing Southeast University
Aerospace Science and Technology | Year: 2011

In a recent paper by Jin Erdong and Sun Zhaowei [Robust controllers design with finite time convergence for rigid spacecraft attitude tracking control, Aerospace Science and Technology 12 (2008) 324-330], a terminal sliding mode control technique has been applied to the attitude control problem of rigid spacecraft. Unfortunately, the controller has singularity problem which will cause the instability of the closed-loop system of attitude tracking errors. In this article, a nonsingular terminal sliding mode controller is presented to overcome this problem. © 2010 Elsevier Masson SAS.


Xu J.,China University of Petroleum - East China | Xu J.,Weifang Biomedical Innovation and Entrepreneurship Service Center | Jiang C.-S.,CAS Shanghai Institute of Materia Medica | Zhang Z.-L.,China University of Petroleum - East China | And 2 more authors.
Acta Pharmacologica Sinica | Year: 2014

Macrolides, which comprise a family of lactones with different ring sizes, belong to the polyketide class of natural products. Resorcinolic macrolides, an important subgroup, possess interesting structures and exhibit a wide variety of bioactivities, such as anti-tumor, anti-bacteria, and anti-malaria activities, etc. This review summarizes progress in isolation, bioactivity studies, biosynthesis, and representative chemical syntheses of this group of macrolides in recent decades, encompassing 63 naturally occurring macrolides published in 120 articles. © 2014 CPS and SIMM.


Sheng L.,China University of Petroleum - East China | Gao M.,Shandong University of Science and Technology | Zhang W.,Shandong University of Science and Technology
International Journal of Systems Science | Year: 2014

The dissipative analysis and control problems for a class of Markov jump non-linear stochastic systems (MJNSSs) are investigated. A sufficient condition for the dissipativity of MJNSSs is given in terms of coupled non-linear Hamilton-Jacobi inequalities (HJIs). Generally, it is difficult to solve the coupled HJIs. In this paper, based on T-S fuzzy model, the dissipative analysis and controller design for MJNSSs is proposed via solving a set of linear matrix inequalities (LMIs) instead of HJIs. Finally, a numerical example is presented to show the effectiveness of the proposed method. © 2012 Taylor & Francis.


Gao M.,Shandong University of Science and Technology | Sheng L.,China University of Petroleum - East China | Zhang W.,Shandong University of Science and Technology
IET Control Theory and Applications | Year: 2014

This study investigates the finite horizon H2/H ∞ control of time-varying stochastic Markov jump systems (SMJSs) with state, control and disturbance-dependent noise. Firstly, the stochastic bounded real lemma of SMJSs is established, which by itself has theoretical importance. Secondly, several necessary and sufficient conditions for H2/H∞ control of SMJSs are proposed by means of coupled generalised differential Riccati equations. Finally, two numerical examples are given to show the effectiveness of the obtained results. © The Institution of Engineering and Technology 2014.


Liu D.,Shandong University of Science and Technology | Liu C.,China University of Petroleum - East China
China Petroleum Processing and Petrochemical Technology | Year: 2013

Diatomite-dispersed NiMoW catalyst was prepared and characterized, and the activity of catalyst samples was tested during the HDS reaction of FCC diesel. Sulfur compounds in the feedstock and the hydrogenated products obtained over different catalysts were determined by GC-PFPD. The test results showed that the diatomite-dispersed NiMoW catalyst had high hydrodesulfurization activity for FCC diesel, which could be contributed to the excellent hydrogenation performance of the said catalyst. Characterization of catalyst by TEM and XRD indicated that the diatomite-dispersed NiMoW catalyst possessed higher layer stacking, larger curvature of MoS2 or WS2, and segregated Ni3S2 crystals relative to the supported catalyst. This kind of structure leads to high hydrogenation activity of the diatomite-dispersed NiMoW catalyst.


Sheng L.,China University of Petroleum - East China | Gao M.,Shandong University of Science and Technology
International Journal of Systems Science | Year: 2013

This article discusses the robust stability problem for a class of uncertain Markovian jump discrete-time neural networks with partly unknown transition probabilities and mixed mode-dependent time delays. The transition probabilities of the mode jumps are considered to be partly unknown, which relax the traditional assumption in Markovian jump systems that all of them must be completely known a priori. The mixed time delays consist of both discrete and distributed delays that are dependent on the Markovian jump modes. By employing the Lyapunov functional and linear matrix inequality approach, some sufficient criteria are derived for the robust stability of the underlying systems. A numerical example is exploited to illustrate the developed theory. © 2013 Copyright Taylor and Francis Group, LLC.


Sheng L.,China University of Petroleum - East China | Gao M.,Shandong University of Science and Technology | Zhang W.,Shandong University of Science and Technology
IET Control Theory and Applications | Year: 2013

This study is concerned with the stability analysis and stabilisation of linear stochastic systems with Markovian switching by using the spectral technique. The notion of spectrum for Markovian jump linear stochastic systems (MJLSSs) is introduced and the relationship between the spectrum and the asymptotical mean-square stability is revealed. As applications, a necessary and sufficient condition for regional stability of MJLSSs and a result on generalised Lyapunov equations are derived. Examples are presented to illustrate the results established. © The Institution of Engineering and Technology 2013.


Sheng L.,China University of Petroleum - East China | Gao M.,Shandong University of Science and Technology
Fuzzy Sets and Systems | Year: 2010

Abstract: This paper is concerned with the stability and stabilization problems for a class of nonlinear systems with Markovian jump parameters. The Takagi-Sugeno (T-S) fuzzy model is employed to represent the Markovian jump nonlinear systems with partly unknown transition probabilities. In contrast with the certain or uncertain transition probabilities investigated recently, the concept of partly unknown transition probabilities does not need any knowledge of the unknown elements. Some sufficient conditions for stochastic stability and stabilization conditions with a mode-dependent fuzzy controller are derived for the Markovian jump fuzzy systems in terms of linear matrix inequalities (LMIs). A numerical example is provided to illustrate the design developed in this paper. © 2010 Elsevier B.V. All rights reserved.


Zhang W.,Shandong University of Science and Technology | Chen B.-S.,National Tsing Hua University | Tang H.,Shandong University | Sheng L.,China University of Petroleum - East China | Gao M.,Shandong University of Science and Technology
IEEE Transactions on Automatic Control | Year: 2014

This technical note studies the nonlinear stochastic H∞ control of Itô-type differential systems with all the state, control input and external disturbance-dependent noise (x,u,v-dependent noise for short). A sufficient condition is given for the finite/infinite horizon H ∞ control of such a system by means of an Hamilton-Jacobi inequality (HJI) instead of three coupled Hamilton-Jacobi equations (HJEs) as in previous literature. © 2013 IEEE.


Sheng L.,China University of Petroleum - East China | Gao M.,Shandong University of Science and Technology
Proceedings of the World Congress on Intelligent Control and Automation (WCICA) | Year: 2012

In this paper, the multiperiodicity of a class of high-order Cohen-Grossberg neural networks (HOCGNNs) with special activation functions is discussed by using analysis approach and decomposition of state space. The activation functions of this class of neural networks consist of nondecreasing functions with saturation, standard activation functions of cellular neural networks, etc. It is shown that the n-neuron HOCGNNs can have 2n locally exponentially attractive periodic orbits located in saturation regions. In addition, a condition is derived for ascertaining the periodic orbit to be locally exponentially attractive and to be located in any designated region. Finally, an example is given to show the effectiveness of the obtained results. © 2012 IEEE.


Kang Z.,China University of Petroleum - East China | Zi S.,Qingdao Jiaozhou Power Supply Company
Diangong Jishu Xuebao/Transactions of China Electrotechnical Society | Year: 2013

As the regional distributed network of oil-field possessing the characteristics of heavy load, severe short of reactive power and large grid losses, a reactive power optimization method which is suitable for the oil-field regional network is proposed in this paper. The mathematical model of reactive power optimization was established which had comprehensively considered the economy and security of the system to make them constraint each other in the proposed method. The proposed optimization model was solved with the differential evolution algorithm, which had been merely mentioned in previous research of power system reactive power optimization. By using this algorithm, the optimization results are independent of the initial values and few controlled variables are neccessory. It is easy to find the global optimal solutions with the differential evolution. The results of the cases analysis and the compare of different optimization methods suggested that the proposed regional distributed network reactrive power optimization method be feasible and valid.


Ling C.,China University of Petroleum - East China | Xue Q.,China University of Petroleum - East China | Jing N.,China University of Petroleum - East China | Xia D.,University of Aarhus
Nanoscale | Year: 2012

The effect of functional groups on the radial collapse and elasticity of a single-walled carbon nanotube (SWNT) under hydrostatic pressure was investigated using molecular dynamics and molecular mechanics simulations. It is found that the radial collapse and elasticity of the chemically modified SWNTs strongly depend on the polarity of the functional groups and the degree of functionalization. The results show that the fluorine modified SWNT (F-SWNT), on which 2.5-5.0% of the atoms are attached to -F groups, can sustain the original elasticity of the intrinsic SWNT, and the pressure needed to collapse the F-SWNT increases by 11.3-21.8%. Functional groups such as hydroxyl groups, amino groups and carboxylic groups can increase the pressure needed to collapse the modified SWNTs, but decrease their radial elasticity. Therefore, the F-SWNTs, due to the higher collapse pressure, are ideal fillers for nanocomposites for high load mechanical support. © 2012 The Royal Society of Chemistry.


Chen X.-F.,Shandong Academy of Sciences | Zang H.,Shandong Academy of Sciences | Zang H.,Shandong University of Science and Technology | Wang X.,Shandong Academy of Sciences | And 4 more authors.
Analyst | Year: 2012

In this paper, the potential applications of metal-organic framework (MOF) materials as fiber coatings for the solid-phase microextraction (SPME) of polycyclic aromatic hydrocarbons (PAHs) in water samples were explored. Fibers coated with MIL-53(Al, Cr, Fe) materials were fabricated by an adhesive method for SPME. The quantitation was performed by gas chromatography-tandem mass spectrometry (GC-MS/MS) using the multiple reaction monitoring mode. Among the three MIL-53(M) coatings, MIL-53(Al) showed the highest extraction efficiency towards PAHs under the current fabrication procedure. Under optimized conditions, the MIL-53(Al)-coated fiber showed good precision (relative standard deviation <12.5%), low detection limits (0.10 ng L -1 to 0.73 ng L -1, S/N = 3), and good linearity (R 2 > 0.98) for aqueous solutions containing 16 PAH. The fiber also offered high thermal and chemical stability. The method developed based on MIL-53(Al) SPME-GC-MS/MS was successfully applied in the analysis of real water samples. Based on the simulation results, the PAHs were adsorbed on MIL-53(Al) primarily through the hydrophobic and π-π interactions between PAHs and the organic linker of the material. The results presented in this paper indicate that water-stable MOF materials have great potential for the SPME of aromatic compounds in water samples. This journal is © 2012 The Royal Society of Chemistry.


Xia D.,China University of Petroleum - East China | Xie J.,China University of Petroleum - East China | Chen H.,China University of Petroleum - East China | Lv C.,China University of Petroleum - East China | And 3 more authors.
Small | Year: 2010

A simple way of synthesizing carbon nanotube (CNT)/graphene (GN) nanoscroll core/shell nanostructures is demonstrated using molecular dynamics (MD) simulations. The simulations show that GN sheets can fully self-scroll onto CNTs when the CNT radius is larger than a threshold of about 10 Å, forming a stable core/shell structure. Increasing the length of the GN sheet results in multilayered carbon nanoscroll (CNS) shells that exhibit a tubular structure similar to that of multiwall CNTs. The distances between the CNT and the GN wall or adjacent GN walls are about 3.4 Å. It is found that the van der Waals force plays an important role in the formation of the CNT/GN nanoscroll core/shell-composite nanostructures. However, the chirality of the CNT and the GN sheet does not affect the self-scrolling process, which thus provides a simple way of controlling the chirality and physical properties of the resulting core/shell structure. It is expected that this preparation method of CNT/GN nanoscroll core/shell composites will lead to further development of a broad new class of carbon/carbon core/shell composites with enhanced properties and even introduce new functionalities to composite materials. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA.


Yang H.,Beihang University | Bai X.,Beihang University | Zhou J.,Griffith University | Ren P.,China University of Petroleum - East China | And 2 more authors.
Proceedings of the IEEE Computer Society Conference on Computer Vision and Pattern Recognition | Year: 2014

Hashing is very useful for fast approximate similarity search on large database. In the unsupervised settings, most hashing methods aim at preserving the similarity defined by Euclidean distance. Hash codes generated by these approaches only keep their Hamming distance corresponding to the pairwise Euclidean distance, ignoring the local distribution of each data point. This objective does not hold for k-nearest neighbors search. In this paper, we firstly propose a new adaptive similarity measure which is consistent with k-NN search, and prove that it leads to a valid kernel. Then we propose a hashing scheme which uses binary codes to preserve the kernel function. Using low-rank approximation, our hashing framework is more effective than existing methods that preserve similarity over arbitrary kernel. The proposed kernel function, hashing framework, and their combination have demonstrated significant advantages compared with several state-of-the-art methods. © 2014 IEEE.


Wang Z.,China University of Petroleum - East China | Li S.,Nanjing Southeast University | Fei S.,Nanjing Southeast University
Transactions of the Institute of Measurement and Control | Year: 2012

In this paper, an output feedback finite-time controller based on a finite-time stable observer is developed for a bioreactor system. The observer is proposed to estimate the biomass concentration in finite time. Based on the estimation of the biomass concentration, an output feedback controller is designed to track the reference signal in finite time. A Lyapunov function is constructed to prove that the observer is a finite-time stable observer. The finite-time stability results for cascaded systems are employed to prove that the closed-loop system satisfies the finite-time stability. Thus, the observer and the controller can be designed separately, both with finite-time convergence. Numerical simulation results demonstrate the effectiveness of the method. © The Author(s) 2012.


Guo Q.,China University of Petroleum - East China | Xue Q.,China University of Petroleum - East China | Sun J.,China University of Petroleum - East China | Dong M.,University of Aarhus | And 2 more authors.
Nanoscale | Year: 2015

Novel core/shell structured multi-walled carbon nanotube/amorphous carbon (MWCNT@AC) nanohybrids were successfully prepared using a simple and novel method. Subsequently, the MWCNT@AC nanohybrids were used as fillers to enhance the dielectric properties of poly(vinylidene fluoride) (PVDF) based composites. It is found that the dielectric constant of the MWCNT@AC/PVDF composites can reach 5910 (the dielectric loss is ∼2), which is considerably better than that of MWCNT/PVDF composites. The uniform amorphous carbon shell provides an insulative layer between adjacent MWCNTs in the polymer matrix, which not only prevents the direct contact of MWCNTs but also improves the dispersibility of the MWCNTs. Therefore, a surprising number of microcapacitors could be formed in the composites before the formation of a conductive network, leading to a gigantic enhancement in the dielectric properties. Our strategy provides a new approach to fabricate excellent dielectric materials for energy storage capacitors. In addition, the design concept used in this work can be extended to other carbon materials. This journal is © The Royal Society of Chemistry.


Guo K.,Hong Kong University of Science and Technology | Yan K.,Hong Kong University of Science and Technology | Lu X.,China University of Petroleum - East China | Qiu Y.,Hong Kong University of Science and Technology | And 5 more authors.
Organic Letters | Year: 2012

This work identifies the dithiafulvenyl unit as an excellent electron donor for constructing D-π-A-type metal-free organic sensitizers of dye-sensitized solar cells (DSCs). Synthesized and tested are three sensitizers all with this donor and a cyanoacrylic acid acceptor but differing in the phenyl (DTF-C1), biphenyl (DTF-C2), and phenyl-thiopheneyl-phenyl π-bridges (DTF-C3). Devices based on these dyes exhibit a dramatically improved performance with the increasing π-bridge length, culminating with DTF-C3 in η = 8.29% under standard global AM 1.5 illumination. © 2012 American Chemical Society.


Sheng L.,China University of Petroleum - East China | Zhang W.,Shandong University of Science and Technology | Gao M.,Shandong University of Science and Technology
IEEE Transactions on Automatic Control | Year: 2014

This technical note is concerned with discussing the relationship between Nash equilibrium strategies and the finite horizon H2/H∞ control of time-varying stochastic systems subject to Markov jump parameters and multiplicative noise. It is revealed that the equivalence of these two problems depends on whether the disturbance enters into the diffusion term. Furthermore, necessary and sufficient conditions for the finite horizon H 2/H∞ control of stochastic Markov jump systems are presented via coupled matrix-valued equations. © 2014 IEEE.


Sheng L.,China University of Petroleum - East China | Gao M.,Shandong University of Science and Technology
Proceedings of the 30th Chinese Control Conference, CCC 2011 | Year: 2011

In this paper, the problem of synchronization for a class of delayed BAM neural networks with reaction-diffusion terms is investigated. By using the drive-response concept, a feedback control law is derived to achieve the state synchronization of two identical BAM neural networks with reaction-diffusion terms. Moreover, based on Lyapunov stability method and Young inequality lemma, a sufficient condition is obtained to ensure asymptotic synchronization of the models considered. An example is given to show the effectiveness of the obtained results. © 2011 Chinese Assoc of Automati.


Zhang T.,China University of Petroleum - East China | Xue Q.,China University of Petroleum - East China | Zhang S.,University of Aarhus | Dong M.,University of Aarhus
Nano Today | Year: 2012

Graphene with its peculiar and exceptional properties has been widely used in the preparation of next generation functional nanocomposites. However, future development of graphene and graphene-based composites crucially depends on the fundamental understandings of their hierarchical structures and dynamical behaviors provided by multiscale modeling and simulation. In the beginning of this review, some computational methods that have been applied extensively in the area of graphene and graphene-based composites are introduced, covering from Quantum Chemistry approach, Molecular Dynamics method to Monte Carlo simulation technique. Then the applications of these methods to various aspects of graphene and graphene-based composites are discussed in some detail. Particular emphasis is laid on researches that explore the physical properties, interacting mechanisms, and potential applications of graphene-based materials. Finally, future challenges and perspectives in modeling and simulation of graphene-based composites are addressed. © 2012 Elsevier Ltd. All rights reserved.


Zhao X.,Bohai University | Zhao X.,China University of Petroleum - East China | Zhang L.,Harbin Institute of Technology | Wang Z.,Harbin Institute of Technology
IET Control Theory and Applications | Year: 2012

This brief concerns the stabilisation problem for a class of slowly switched positive linear systems in discrete-time context. The average dwell-time switching associated with the corresponding state-feedback controllers is designed to stabilise the closed-loop systems and keep the states non-negative. The developed conditions are formulated as linear matrix inequalities, which can be directly used for controller synthesis and switching designing. Finally, a numerical example is presented to show the feasibility of the obtained theoretical results. © 2012 The Institution of Engineering and Technology.


Zhao X.,China University of Petroleum - East China | Zhang L.,Harbin Institute of Technology | Shi P.,University of South Wales | Shi P.,Victoria University of Melbourne | Liu M.,Harbin Institute of Technology
IEEE Transactions on Automatic Control | Year: 2012

In this paper, the stability and stabilization problems for a class of switched linear systems with mode-dependent average dwell time (MDADT) are investigated in both continuous-time and discrete-time contexts. The proposed switching law is more applicable in practice than the average dwell time (ADT) switching in which each mode in the underlying system has its own ADT. The stability criteria for switched systems with MDADT in nonlinear setting are firstly derived, by which the conditions for stability and stabilization for linear systems are also presented. A numerical example is given to show the validity and potential of the developed techniques. © 2011 IEEE.


Liu C.,China University of Petroleum - East China | Zhao C.,China University of Petroleum - East China | Wang A.,Harbin Institute of Technology | Guo Y.,China University of Petroleum - East China | Lee D.-J.,National Taiwan University
Applied Microbiology and Biotechnology | Year: 2015

Denitrifying sulfide removal (DSR) process comprising both heterotrophic and autotrophic denitrifiers can simultaneously convert nitrate, sulfide, and acetate into nitrogen gas, elemental sulfur (S0), and carbon dioxide, respectively. Sulfide- and nitrate-laden wastewaters at 2–35 g/L NaCl were treated by DSR process. A C/N ratio of 3:1 was proposed to maintain high S0 conversion rate. The granular sludge with a compact structure and smooth outer surface was formed. The microbial communities of DSR consortium via high-throughput sequencing method suggested that salinity shifts the predominating heterotrophic denitrifiers at <10 g/L NaCl to autotrophic denitrifiers at >10 g/L NaCl. © 2015, Springer-Verlag Berlin Heidelberg.


Liu B.-D.,China University of Petroleum - East China | Wang Y.-X.,Carnegie Mellon University | Shen B.,Purdue University | Zhang Y.-J.,Tsinghua University | Hebert M.,Carnegie Mellon University
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2014

Traditional sparse representation algorithms usually operate in a single Euclidean space. This paper leverages a self-explanatory reformulation of sparse representation, i.e., linking the learned dictionary atoms with the original feature spaces explicitly, to extend simultaneous dictionary learning and sparse coding into reproducing kernel Hilbert spaces (RKHS). The resulting single-view self-explanatory sparse representation (SSSR) is applicable to an arbitrary kernel space and has the nice property that the derivatives with respect to parameters of the coding are independent of the chosen kernel. With SSSR, multiple-view self-explanatory sparse representation (MSSR) is proposed to capture and combine various salient regions and structures from different kernel spaces. This is equivalent to learning a nonlinear structured dictionary, whose complexity is reduced by learning a set of smaller dictionary blocks via SSSR. SSSR and MSSR are then incorporated into a spatial pyramid matching framework and developed for image classification. Extensive experimental results on four benchmark datasets, including UIUC-Sports, Scene 15, Caltech-101, and Caltech-256, demonstrate the effectiveness of our proposed algorithm. © 2014 Springer International Publishing.


Xu K.,Coastal Carolina University | Li A.,CAS Qingdao Institute of Oceanology | Liu J.P.,North Carolina State University | Milliman J.D.,College of William and Mary | And 5 more authors.
Marine Geology | Year: 2012

Surficial grain-size and down-core clay mineralogical data show that sediment along the inner-most part of the continental shelf in East China Sea is mainly derived from the Yangtze River (Changjiang), spanning from the Yangtze mouth (33°N) ~. 1000. km southward to the southwestern corner of the Taiwan Strait (24°N). High-resolution CHIRP seismic profiles reveal an elongated mud wedge extending along the inner shelf, with a northern depocenter on the modern Yangtze delta and a southern depocenter at 27.5°N. Four distinct acoustic units are delineated within the mud wedge (from bottom up): unit I (late-Pleistocene, mainly valley fills), unit II (formed by transgressions, thin strata), unit III (11-2. kyr BP, downlapping strata) and unit IV (2-0. kyr BP, flat and opaque strata). Incised valleys, up to 15-m deep, are filled by flat-lying or inclined strata in unit I. The thin (<3 m) and acoustically transparent unit II is only seen between 30 and 26°N in water depths between 40 and 90. m. Separated by acoustically opaque strata or unconformities, units III and IV are widely distributed. During the past 11. kyr Yangtze sediment accumulation has been unsteady, showing two high and one low accumulation-rate periods. The high-accumulation period at 5-8. kyr BP may be related to maximum East Asian summer monsoon precipitation in the Yangtze basin; the other high-accumulation period, 0-2. kyr BP, probably reflects intensive human activities in the river's watershed. The low-accumulation-rate period at 2-5. kyr BP, which is seen in both northern and southern Yangtze depocenters, is probably related to low river discharge and/or intensified Taiwan Warm Current and China Coastal Current. © 2011 Elsevier B.V..


Wei W.,Tianjin University | Lv W.,Tianjin University | Lv W.,Tsinghua University | Wu M.-B.,China University of Petroleum - East China | And 6 more authors.
Carbon | Year: 2013

Graphene wrapping is used to experimentally understand how a carbon coating works in improving the electrochemical performance of the LiFePO4 cathode for a lithium ion battery. A full wrapping of LiFePO4 by graphene is realized by a self-assembly driven by the electrostatic interaction in a graphene oxide suspension. Results indicate that a partial graphene wrapping provides a balance between increased electron transport and fast ion diffusion while full graphene wrapping isolates LiFePO4 from the electrolyte and retards ion diffusion. This indicates that steric hindrance for ion diffusion should be considered together with electron transport in constructing a carbon coating layer. © 2013 Elsevier Ltd. All rights reserved.


Zhou J.,Shandong University of Technology | Li Z.,Shandong University of Technology | Xing W.,China University of Petroleum - East China | Zhu T.,Shandong University of Technology | And 2 more authors.
Chemical Communications | Year: 2015

N-doped microporous carbons with uniform ultramicropores (∼0.50 nm) are facilely prepared by direct carbonization of K+ exchanged meta-aminophenol-formaldehyde resin. These materials give an unprecedented CO2 uptake of 1.67 mmol g-1 at 25 °C and 0.15 bar and superior CO2-over-N2 selectivity (50:1). This journal is © The Royal Society of Chemistry 2015.


Zhao X.,Bohai University | Zhao X.,China University of Petroleum - East China | Liu X.,Southwest University for Nationalities | Yin S.,Bohai University | Li H.,Bohai University
Automatica | Year: 2014

In this paper, the problems of stability for switched positive linear systems (SPLSs) under arbitrary switching are investigated in a continuous-time context. The so-called "copositive polynomial Lyapunov function" (CPLF) giving a generalization of copositive types of Lyapunov function is first proposed, which is formulated in a higher order form of the positive states of the underlying systems. It is illustrated in this paper that some classical types of Lyapunov functions can be seen as special cases of the proposed CPLF. Then, new stability conditions are developed by the new Lyapunov function approach. It is also proved that the conservativeness of the obtained criteria can be further reduced as the degree of the Lyapunov function increases. A numerical example is given to demonstrate the effectiveness and less conservativeness of the developed techniques. © 2013 Elsevier Ltd. All rights reserved.


Liu Y.,Jilin University | Yin X.,Jilin University | Zhang J.,Jilin University | Yu S.,China University of Petroleum - East China | And 2 more authors.
Electrochimica Acta | Year: 2014

Super-hydrophobic surface has many special functions that are studied wildly. The ingenious microstructures of typical plant leaves with super-hydrophobicity enlighten researchers to design and fabricate artificial super-hydrophobic surface. Being the lightest alloy among structural metals materials magnesium alloy was restricted due to its poor corrosion resistance. A super-hydrophobic surface with self-cleaning was successfully deposited on AZ91D magnesium alloy by the nickel plating process. The super-hydrophobic surfaces were covered with cauliflower-like cluster binary micro-nano structural Ni coatings. The procedure was that the samples were processed by plating after pretreatment, finally modified by stearic acid (CH3(CH 2)16COOH). The surface morphologies, chemical composition, wettability and corrosion resistance are characterized by means of SEM, FT-IR, water contact angle and electrochemical impedance spectroscopy (EIS) measurements. The as-prepared super-hydrophobic surface has a contact angle as high as 160.8 ± 1 and a SA as low as 1.8 ± 1, showing good long-term stability. The super-hydrophobic surface exhibited excellent corrosion resistance property in the 3.5 wt. % NaCl solution. This method could provide a straightforward and effective route to fabricate large-area super-hydrophobic surface with anticorrosion and self-cleaning for a great number of potential applications, and easily extended to other metal materials. © 2014 Elsevier Ltd.


Wang Y.,China University of Petroleum - East China | Zhou Y.,Xi'an Jiaotong University | Brauer F.,University of British Columbia | Heffernan J.M.,York University
Journal of Mathematical Biology | Year: 2013

We present two HIV models that include the CTL immune response, antiretroviral therapy and a full logistic growth term for uninfected CD4+ T-cells. The difference between the two models lies in the inclusion or omission of a loss term in the free virus equation. We obtain critical conditions for the existence of one, two or three steady states, and analyze the stability of these steady states. Through numerical simulation we find substantial differences in the reproduction numbers and the behaviour at the infected steady state between the two models, for certain parameter sets. We explore the effect of varying the combination drug efficacy on model behaviour, and the possibility of reconstituting the CTL immune response through antiretroviral therapy. Furthermore, we employ Latin hypercube sampling to investigate the existence of multiple infected equilibria. © 2012 Springer-Verlag.


Yu S.R.,China University of Petroleum - East China | Yu S.R.,Hubei University | Liu J.A.,Jilin University | Diao W.,Jilin University | And 2 more authors.
Journal of Alloys and Compounds | Year: 2014

A superhydrophobic surface with the bionic microtexture was prepared successfully on X52 pipeline steel using the sandblasting roughening treatment, chemical etching and fluorination treatment composite methods. The pipeline steel surface was modified with (heptadecafluoro-1,1,2,2-tetradecyl) trimethoxysilane (HFTTMS). The effects of HCl concentration and the chemical etching time on the morphology of the pipeline steel surface and the wettability of the surface with distilled water were investigated. The results show that at certain HCl concentration, with the increase of the chemical etching time, the contact angles have a maximum value. At certain chemical etching time, the higher HCl concentration was, the severer the reaction between the pipeline steel surface and HCl solution was, and the surface roughness formed by the sandblasting roughening treatment decreased rapidly, resulting in the decrease of the contact angle. The sample sandblasted for 1.5 min and etched chemically for 1.5 h at 7 mol/L HCl can obtain the best surface fine structure. After the fluorination treatment, the biggest contact angle is 156.4°. © 2013 Elsevier B.V. All rights reserved.


Zeng W.,University of Cincinnati | Liu G.R.,University of Cincinnati | Li D.,Shandong University of Technology | Dong X.W.,University of Cincinnati | Dong X.W.,China University of Petroleum - East China
Computers and Structures | Year: 2016

This paper presents a novel class of smoothing techniques based beta finite element method (βFEM) for modeling of crystalline materials. The method is first examined by a simple standard patch test and applied in elastic problems. It is then implemented to model the anisotropic plastic deformation of rate-independent single crystals and bi-crystal. Several representative examples are studied to demonstrate the capability of proposed method with the integration algorithm for capturing the strain localization and dealing with plastic incompressibility. It is also performed to simulate the mechanical behavior of polycrystalline aggregates through modeling the synthetic microstructure constructed by Voronoi tessellation technique. © 2015 Elsevier Ltd. All rights reserved.


Zhixue S.,China University of Petroleum - East China | Zhilei S.,CAS Qingdao Institute of Oceanology | Zhilei S.,CAS Guangzhou Institute of Geochemistry | Hongjiang L.,Chengdu University of Technology | Xijie Y.,State Oceanic Administration
Petroleum Exploration and Development | Year: 2010

Authigenic carbonate cement is dominant in the Yanchang Formation sandstones of the middle and southern Ordos Basin. The main types of the carbonate cement are calcite, dolomite, ferrodolomite and ferrocalcite and the carbonate cement abundance decreases with depth increasing. Polarizing microscope and SEM reveal that carbonate cement occurs as pore-filling cement, replacement of feldspar, and thin rim surrounding the grains. The isotopic values of carbon and oxygen in the authigenic carbonates indicate that the precipitation of the carbonate cements was long, multi-phased, and varying in temperature. The origin of the substance for carbonate cements include the solution of the detrital carbonate, the illitization of smectite, the expelled fluid flow from the overlying shale, and the decomposition of the unstable dark-color minerals in reservoirs. The occluding of pores, the division of thick reservoir, the formation of calcium layers and the absence of solution of the carbonate cements significantly decrease the reservoir qualities all together. © 2010 Research Institute of Petroleum Exploration & Development, PetroChina.


Chao B.,CAS Shanghai Institute of Materia Medica | Lin S.,CAS Shanghai Institute of Materia Medica | Ma Q.,China University of Petroleum - East China | Lu D.,CAS Shanghai Institute of Materia Medica | Hu Y.,CAS Shanghai Institute of Materia Medica
Organic Letters | Year: 2012

A novel cascade reaction was developed for the synthesis of diverse members of a series of benzofuro[3,2-d]pyrimidine derivatives. The process utilizes readily prepared 3-chlorochromenones and various commercially available amidines and their analogues as starting materials. This tandem reaction is promoted by using a simple copper(I) reagent and involves a chemoselective Michael addition-heterocyclization-intramolecular cyclization sequence. © 2012 American Chemical Society.


Si W.,Shandong University of Technology | Zhou J.,Shandong University of Technology | Zhang S.,Shandong University of Technology | Li S.,Shandong University of Technology | And 3 more authors.
Electrochimica Acta | Year: 2013

In this work, human hair was firstly used to prepared heteroatom-doped carbon materials. Tunable N-doped or dual N, S-doped microporous carbons were successful prepared using glucose and human hair as carbon precursors via a method of hydrothermal carbonization procedure and sequent KOH activation. The electrochemical capacitive performance of the prepared carbons was investigated in KOH electrolyte. The morphology, structure and surface properties of the carbon materials are investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption, X-ray photoelectron spectroscopy (XPS), Energy Dispersive Spectroscopy (EDS) and Fourier transform infrared spectroscopy (FT-IR). The N- or S-doping could be tuned by controlling the dosage of human hair additives. Due to the synergistic effect of multi N, O, S-doped species, the prepared carbons showed large pseudo-capacitance. The capacitance of AHC-4 could reach 264Fg-1 in KOH electrolyte. AHC-1 shows an acceptable cycle life with relatively high capacitance value of 154Fg-1 after 1000 cycles. The present preparation method is attractive and inspiring for preparation of tunable dual heteroatom-doped carbon materials with high surface area and capacitive performance using renewable biomass. Crown Copyright © 2013 Published by Elsevier Ltd. All rights reserved.


Ali M.M.,University of California at Irvine | Li F.,University of California at Irvine | Li F.,University of Alberta | Zhang Z.,University of California at Irvine | And 7 more authors.
Chemical Society Reviews | Year: 2014

Rolling circle amplification (RCA) is an isothermal enzymatic process where a short DNA or RNA primer is amplified to form a long single stranded DNA or RNA using a circular DNA template and special DNA or RNA polymerases. The RCA product is a concatemer containing tens to hundreds of tandem repeats that are complementary to the circular template. The power, simplicity, and versatility of the DNA amplification technique have made it an attractive tool for biomedical research and nanobiotechnology. Traditionally, RCA has been used to develop sensitive diagnostic methods for a variety of targets including nucleic acids (DNA, RNA), small molecules, proteins, and cells. RCA has also attracted significant attention in the field of nanotechnology and nanobiotechnology. The RCA-produced long, single-stranded DNA with repeating units has been used as template for the periodic assembly of nanospecies. Moreover, since RCA products can be tailor-designed by manipulating the circular template, RCA has been employed to generate complex DNA nanostructures such as DNA origami, nanotubes, nanoribbons and DNA based metamaterials. These functional RCA based nanotechnologies have been utilized for biodetection, drug delivery, designing bioelectronic circuits and bioseparation. In this review, we introduce the fundamental engineering principles used to design RCA nanotechnologies, discuss recently developed RCA-based diagnostics and bioanalytical tools, and summarize the use of RCA to construct multivalent molecular scaffolds and nanostructures for applications in biology, diagnostics and therapeutics. © 2014 the Partner Organisations.


Zhang L.,Shandong University | Xu B.,Shandong University of Technology | Xue Y.,China University of Petroleum - East China | Gao H.,Shandong University
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2012

In order to solve the fault location problem of single phase grounding fault in non-solidly earthed distribution network, a new fault location method based on transient component of line voltage and zero-mode current was presented. This method is realized by the feeder automation (FA) system and does not require additional equipment. The product of transient line voltage after Hilbert transformation and transient zero-mode current is defined as the parameter of fault direction, calculated by the feeder terminal unit (FTU). The fault section is located by master station according to opposite polarity of direction parameter before and after fault point. The algorithm of detecting single phase grounding fault and confirming the fault phase was introduced. Results of digital simulation and experiment demonstrated the accuracy and feasibility of this method. © 2012 Chinese Society for Electrical Engineering.


Liu J.-L.,China University of Petroleum - East China | Feng X.-Q.,Tsinghua University
Acta Mechanica Sinica/Lixue Xuebao | Year: 2012

Elastocapillary phenomena involving elastic deformation of solid structures coupled with capillary effects of liquid droplets/films can be observed in a diversity of fields, e.g., biology and microelectromechanical systems (MEMS). Understanding the physical mechanisms underlying these phenomena is of great interest for the design of new materials and devices by utilizing the effects of surface tension at micro and nano scales. In this paper, some recent developments in the investigations on elastocapillary phenomena are briefly reviewed. Especially, we consider the deformation, adhesion, self-assembly, buckling and wrinkling of materials and devices induced by surface tensions or capillary forces. The main attention is paid to the experimental results of these phenomena and the theoretical analysis methods based on continuum mechanics. Additionally, the applications of these studies in the fields of MEMS, micro/nanometrology, and biomimetic design of advanced materials and devices are discussed. © The Chinese Society of Theoretical and Applied Mechanics and Springer-Verlag Berlin Heidelberg 2012.


Xu M.-W.,Xinjiang Normal University | Jia W.,Xinjiang University | Bao S.-J.,Xinjiang University | Su Z.,Xinjiang Normal University | Dong B.,China University of Petroleum - East China
Electrochimica Acta | Year: 2010

MnO2 with novel mesoporous structure has been firstly synthesized via a simple in situ reduction process by using different carbon materials as sacrificed template and reducing agent. The morphology and microstructure of as-synthesized mesoporous MnO2 were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), nitrogen adsorption and desorption experiments. The results demonstrate that porous MnO2 prepared using mesoporous carbon as template has very large specific surface area and uniform pore-size distribution. The electrochemical measurements showed that novel porous MnO2 have higher capacity (221 F g-1) with excellent rate and higher capacity retention as electrochemical capacitors (ECs) electrode materials, which may be attributed to the unique nanostrcture of porous MnO2. These all imply that MnO2 with novel mesoporous structure has been attractive for practical and large-scale applications in mobile equipment. © 2010 Elsevier Ltd. All rights reserved.


Bao X.X.,China University of Petroleum - East China | Li C.L.,CAS Qingdao Institute of Oceanology | Xiong C.B.,State Oceanic Administration
Applied Physics Letters | Year: 2015

Modal analysis is an ongoing interdisciplinary physical issue. Modal parameters estimation is applied to determine the dynamic characteristics of structures under vibration excitation. Modal analysis is more challenging for the measured vibration response signals are contaminated with noise. This study develops a mathematical algorithm of structured low rank approximation combined with the complex exponential method to estimate the modal parameters. Physical experiments using a steel cantilever beam with ten accelerometers mounted, excited by an impulse load, demonstrate that this method can significantly eliminate noise from measured signals and accurately identify the modal frequencies and damping ratios. This study provides a fundamental mechanism of noise elimination using structured low rank approximation in physical fields. © 2015 AIP Publishing LLC.


Zhang H.,Shanghai Maritime University | Lu C.,China Electric Power Research Institute | Sun Z.,China University of Petroleum - East China
Applied Physics Letters | Year: 2015

This paper develops a self-biased magnetoelectric (ME) heterostructure FeCuNbSiB/Terfenol-D/Be-bronze/Pb(Zr,Ti)O3 (PZT) by sandwiching a nonmagnetic elastic Be-bronze plate between an piezoelectric PZT plate and a magnetization-graded FeCuNbSiB/Terfenol-D layer. The Be-bronze plate severs as the resonance frequency determining element of the ME heterostructure. By using the magnetization-graded magnetostrictive layer and the elastic Be-bronze plate, seven large peaks of ME response with magnitudes of 0.3-10 (V/cm Oe) in 1-70 kHz range are observed at zero-biased magnetic field. This demonstrates that the proposed multi-peak self-biased heterostructure may be useful for multifunctional devices such as multi-frequency energy harvesters or low-frequency ac magnetic field sensors. © 2015 AIP Publishing LLC.


Shen S.-Q.,China University of Petroleum - East China | Li M.,China University of Petroleum - East China | Duan X.-F.,Guilin University of Electronic Technology
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2015

Based on the mutually unbiased bases, the mutually unbiased measurements and the general symmetric informationally complete positive-operator-valued measures, we propose three separability criteria for d-dimensional bipartite quantum systems, which are more powerful than the corresponding ones introduced previously [C. Spengler, M. Huber, S. Brierley, T. Adaktylos, and B. C. Hiesmayr, Phys. Rev. A 86, 022311 (2012)PLRAAN1050-294710.1103/PhysRevA.86.022311; B. Chen, T. Ma, and S. M. Fei, Phys. Rev. A 89, 064302 (2014)PLRAAN1050-294710.1103/PhysRevA.89.064302; and B. Chen, T. Li, and S. M. Fei, arXiv:1406.7820v1 [quant-ph] (2014)]. Some states such as Werner states and Bell-diagonal states are used to further illustrate the efficiency of the presented criteria. © 2015 American Physical Society.


Qiao W.,China University of Petroleum - East China | Qiao W.,Tohoku University | Takayanagi K.,Tohoku University | Shofie M.,Tohoku University | And 3 more authors.
Bioresource Technology | Year: 2013

Coffee grounds are deemed to be difficult for degradation by thermophilic anaerobic process. In this research, a 7L AnMBR accepting coffee grounds was operated for 82days and failed with pH dropping to 6.6. The deficiency of micronutrients in the reactor was identified. The system was recovered by supplying micronutrient, pH adjustment and influent ceasing for 22days. In the subsequent 160days of co-digestion experiment, waste activated sludge (15% in the mixture) was mixed into coffee grounds. The COD conversion efficiency of 67.4% was achieved under OLR of 11.1kg-COD/m3d and HRT of 20days. Tannins was identified affecting protein degradation by a batch experiment. Quantitative supplements of NH4HCO3 (0.12g-N/g-TSin) were effective to maintain alkalinity and pH. The solid concentration in the AnMBR reached 75g/L, but it did not significantly affect membrane filtration under a flux of 5.1L/m2h. Soluble carbohydrate, lipid and protein were partially retained by the membrane. © 2013 Elsevier Ltd.


Qiao W.,China University of Petroleum - East China | Qiao W.,Tohoku University | Takayanagi K.,Tohoku University | Niu Q.,Tohoku University | And 2 more authors.
Bioresource Technology | Year: 2013

The performance of thermophilic anaerobic co-digestion of coffee grounds and sludge using membrane reactor was investigated for 148days, out of a total research duration of 263days. The OLR was increased from 2.2 to 33.7kg-COD/m3d and HRT was shortened from 70 to 7days. A significant irreversible drop in pH confirmed the overload of reactor. Under a moderately high OLR of 23.6kg-COD/m3d, and with HRT and influent total solids of 10days and 150g/L, respectively, the COD removal efficiency was 44.5%. Hydrogen in biogas was around 100-200ppm, which resulted in the persistent propionate of 1.0-3.2g/L. The VFA consumed approximately 60% of the total alkalinity. NH4HCO3 was supplemented to maintain alkalinity. The stability of system relied on pH management under steady state. The 16SrDNA results showed that hydrogen-utilizing methanogens dominates the archaeal community. The propionate-oxidizing bacteria in bacterial community was insufficient. © 2013 Elsevier Ltd.


Li Y.,China University of Petroleum - East China | Gao Y.H.,Xiamen University | Li X.S.,Xiamen University | Yang J.Y.,China University of Petroleum - East China | Que G.H.,China University of Petroleum - East China
Colloids and Surfaces B: Biointerfaces | Year: 2010

The self-assembled monolayers (SAMs) with gradient surface free energies were prepared by surface grafting of a binary mixture of methyl and vinyl terminated trimethoxysilanes on hydrophilic glass slides followed by in situ oxidation of vinyl groups into carboxyl groups. Characterized by contact angles, the SAMs combined with freshly cleaned glass slides bearing hydroxyl groups were used to study the adhesion behavior of marine benthic diatom Nitzschia closterium MMDL533. The attachment densities were much higher on hydrophobic CH3-SAMs and lower on mixed SAMs with surface free energy of 40.1-50.4 mJ/m2. More gregarious adhesion had been found on hydrophobic CH3-SAMs. The percentage removal was in a narrow range of 63-80% on the engineered surfaces and was much lower with a value of 54% on the hydrophilic slides. Our studies have revealed some subtle but interesting differences in attachment and adhesion from the features reported for these benthic species, indicating the possible links to different diatom species. © 2009 Elsevier B.V. All rights reserved.


Liu J.,China University of Petroleum - East China | Zuo W.,Jilin University | Mei Y.,South China University of Technology
Colloids and Surfaces A: Physicochemical and Engineering Aspects | Year: 2012

The surface tension of liquid is generally negligible at macroscopic scale but can cause a lot of anomalous deformation of slender structures at small scales. In this study, we presented the analytical deflection solutions of a rectangular plate with two clamped ends and a clamped circular plate based upon the principle of superposition, where a droplet was deposited onto the micro-plate surfaces. In the light of these analytical solutions, the abnormal bending of the plate when the droplet is placed at different positions of the top or bottom surface of the plate was discussed in detail. The FEM (finite element method) simulation was also conducted, and the results show excellent agreement with our analytical solutions. We also put to use the FEM simulation to explore the displacement field of a more general plate with complex boundary conditions and complicated loads originating from the droplet, and the folding of a soft membrane caused by a droplet was also simulated. This investigation is beneficial to understand the physical mechanisms underlying the droplet-induced deformation of slender structures, and is of great interest for the design of new materials and devices by utilizing the effects of surface tension at micro and nano scales. © 2012 Elsevier B.V.


Chen J.Q.,China University of Petroleum - East China | Wang B.G.,Tsinghua University | Lv H.L.,China University of Petroleum - East China
Advanced Materials Research | Year: 2011

The electrolyte flow states of all vanadium redox flow battery (VRB) have a direct effect on the battery performance and life. To reveal the electrolyte distribution in the battery, the computation fluid dynamics (CFD) method was used to simulate a parallel flow field. A hydraulics experiment and a battery performance experiment were carried out to confirm the simulated results. The results show that the predicted information agreed well with the experimental results. The electrolyte has a concentrated distribution in the central region of the parallel flow field and the disturbed flow and then vortex flow areas mainly appear in the inlet and outlet regions. The higher flux of electrolyte is helpful to uniform the distributions and to reduce the impact of flow irregularity on the battery performance. The battery with the flow field generates a power density of 15.9 mW·cm-2, and the coulombic, voltage and energy efficiency is up to 90.5%, 74.0% and 67.2% at a current density of 20 mA·cm-2. © (2011) Trans Tech Publications.


Zhou J.,Shandong University of Technology | Zhang Z.,Shandong University of Technology | Xing W.,China University of Petroleum - East China | Yu J.,Shandong University of Technology | And 3 more authors.
Electrochimica Acta | Year: 2015

In this work, nitrogen-doped hierarchical porous carbon materials (NHPCs) are prepared by a two-step method combined of a hard template process and KOH-activation treatment. Low cost and large-scale commercial nano-SiO2 are used as a hard template. The hierarchical porosity, structure and nitrogen-doped surface chemical properties are proved by a varies of means, such as scanning electron microscopy, transition electron microscopy, N2 sorption, Raman spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy. When the prepared NHPCs materials are used as the electrode materials for supercapacitors in KOH electrolyte, they exhibit very high specific capacitance, good power capability and excellent cyclic stability. NHPC-800 carbon shows a high capacitance of 114.0 F g-1 at the current density of 40 A g-1, responding to a high energy and power densities of 4.0 Wh kg-1 and 10 000 W kg-1, and a very short drain time of 1.4 s. The excellent capacitive performance may be due to the synergistic effect of the hierarchical porosity, high effective surface area and heteroatom doping, resulting in both electrochemical double layer and Faradaic capacitance contributions. © 2014 Elsevier Ltd. All rights reserved.


Xia R.,Wuhan University | Xia R.,Tsinghua University | Li X.,Tsinghua University | Qin Q.,Australian National University | And 2 more authors.
Nanotechnology | Year: 2011

Using the theory of surface elasticity, we investigate the mechanical properties of nanoporous materials. The classical theory of porous materials is modified to account for surface effects, which become increasingly important as the characteristic sizes of microstructures shrink to nanometers. First, a refined Timoshenko beam model is presented to predict the effective elastic modulus of nanoporous materials. Then the surface effects on the elastic microstructural buckling behavior of nanoporous materials are examined. In particular, nanoporous gold is taken as an example to illustrate the application of the proposed model. The results reveal that both the elastic modulus and the critical buckling behavior of nanoporous materials exhibit a distinct dependence on the characteristic sizes of microstructures, e.g. the average ligament width. © 2011 IOP Publishing Ltd.


Liu T.-X.,China University of Petroleum - East China | Tao Z.-Q.,Dagang Oilfield Company
Zhongguo Shiyou Daxue Xuebao (Ziran Kexue Ban)/Journal of China University of Petroleum (Edition of Natural Science) | Year: 2011

Based on the data from well drilling, geology, well logging and production performance, the reservoir architecture modeling of meandering river was researched using the method of multi-order bounding surface restriction and deterministic modeling in a block of Dagang Oilfield. Reservoir architecture model was established by the method of multi-order bounding surface restriction and limited the architecture element among bounding surfaces on the basis of the sedimentary microfacies model and point-bar architecture, then the reservoir parameter model was established using stochastic modeling under the restrictions of reservoir architecture on the basis of well data analysis. The results show that the space, dip angle and trend of lateral accretion interbeds on the scale, and they must be rectified using the well data during the modeling. The spatial distribution of lateral accretion bodies and lateral accretion interbeds are embodied well by the modeling method of multi-order bounding surface restriction. The attribute modeling under reservoir architecture restriction combines deterministic modeling with stochastic modeling, and the result can reflect the actual situation in the reservoir.


Zhao X.,China University of Petroleum - East China | Zhang L.,Harbin Institute of Technology | Shi P.,University of South Wales | Shi P.,Victoria University of Melbourne
International Journal of Robust and Nonlinear Control | Year: 2013

This paper addresses the problem of stability for a class of switched positive linear time-delay systems. As first attempt, the Lyapunov-Krasovskii functional is extended to the multiple co-positive type Lyapunov-Krasovskii functional for the stability analysis of the switched positive linear systems with constant time delay. A sufficient stability criterion is proposed for the underlying system under average dwell time switching. Subsequently, the stability result for system under arbitrary switching is presented by reducing multiple co-positive type Lyapunov-Krasovskii functional to the common co-positive type Lyapunov-Krasovskii functional. A numerical example is given to show the potential of the proposed techniques. Copyright © 2012 John Wiley & Sons, Ltd.


Gao L.,China University of Petroleum - East China | Liang D.,York University
Communications in Computational Physics | Year: 2012

The symmetric energy-conserved splitting FDTD scheme developed in [1] is a very new and efficient scheme for computing the Maxwell's equations. It is based on splitting the whole Maxwell's equations and matching the x-direction and y-direction electric fields associated to the magnetic field symmetrically. In this paper, we make further study on the scheme for the 2D Maxwell's equations with the PEC boundary condition. Two new energy-conserved identities of the symmetric EC-S-FDTD scheme in the discrete H 1-norm are derived. It is then proved that the scheme is unconditionally stable in the discrete H 1-norm. By the new energy-conserved identities, the super-convergence of the symmetric EC-S-FDTD scheme is further proved that it is of second order convergence in both time and space steps in the discrete H 1-norm. Numerical experiments are carried out and confirm our theoretical results. © 2012 Global-Science Press.


Zhang Y.,CAS Institute of Geology and Geophysics | Liu J.,CAS Institute of Geology and Geophysics | Meng F.,China University of Petroleum - East China
Island Arc | Year: 2012

There are wide spread Cenozoic volcanic rocks in Tengchong (CVRT), Yunnan province, SW China. These rocks comprise three rock types: basalt, andesite (dominant type) and dacite. Most samples are sub-alkaline, and among the sub-alkaline rocks, most are high-K calc-alkaline. These rocks have a SiO2 range of 49.1 wt.% to 66.9 wt.%. TiO2 contents are not high and have a variation of 0.7 wt.%-1.6 wt.%. Trace element concentrations and element ratios (such as Nb/U, Ce/Pb, Nb/La, etc.) of these rocks have a large variation. 87Sr/86Sr values fall in the range of 0.7057-0.7093 and 143Nd/144Nd values change from 0.5120 to 0.5125. 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios are in the range of 17.936-19.039, 15.614-15.810, and 38.894-39.735, respectively. These geochemical characteristics of CVRT make them resemble island-arc volcanic rocks. We suggest that the magmas were generated in the lithospheric mantle that had already been metasomatized by previous subduction processes. By the study of the uplift history of the Tibetan Plateau, we found that the beginning of the geotectonic processes to the eruption of CVRT was coeval with one uplift event. Therefore, we propose that the uplift of the Tibetan Plateau caused collapse of the collisional orogeny in Tengchong, which further triggered the generation and eruption of the CVRT magmas. © 2012 Wiley Publishing Asia Pty Ltd.


Jiang W.,China University of Petroleum - East China | Liu Z.,Jilin University | Gong J.M.,Nanjing University of Technology | Tu S.T.,Nanjing University of Technology
International Journal of Pressure Vessels and Piping | Year: 2010

Clad plates are widely used in the construction of corrosion resistant equipment. During the repair of clad plates, residual stresses are generated and influence the structure integrity. This paper uses the finite element method (FEM) to predict the residual stresses in a repair weld of a stainless steel clad plate. The effect of repair width on residual stresses has also been investigated by numerical simulation. Due to the material mismatching between clad metal and base metal, a discontinuous stress distribution has been generated across the interface between clad and base metals. The peak residual stress occurs in the heat affected zone (HAZ) of the base metal, because the yield strength of the base metal is larger than that of the clad metal. With an increase in repair width, the residual stresses are decreased. When the repair width is increased to 24 mm, the residual stresses in the weld have been decreased greatly and the peak residual stresses have been reduced to less than the yield strength. Therefore, the recommended repair width should not be less than 24 mm, which provides a reference for optimizing repair welding technology for this stainless steel clad pate. © 2010 Elsevier Ltd.


Zhao X.,China University of Petroleum - East China | Zhang L.,Harbin Institute of Technology | Shi P.,University of South Wales | Shi P.,Victoria University of Melbourne | Liu M.,Harbin Institute of Technology
Automatica | Year: 2012

In this paper, the stability analysis problem for a class of switched positive linear systems (SPLSs) with average dwell time switching is investigated. A multiple linear copositive Lyapunov function (MLCLF) is first introduced, by which the sufficient stability criteria in terms of a set of linear matrix inequalities, are given for the underlying systems in both continuous-time and discrete-time contexts. The stability results for the SPLSs under arbitrary switching, which have been previously studied in the literature, can be easily obtained by reducing MLCLF to the common linear copositive Lyapunov function used for the system under arbitrary switching those systems. Finally, a numerical example is given to show the effectiveness and advantages of the proposed techniques. © 2012 Elsevier Ltd. All rights reserved.


Guo T.,China University of Petroleum - East China | Guo T.,China University of Petroleum - Beijing | Zhang S.,China University of Petroleum - Beijing | Qu Z.,China University of Petroleum - East China | And 3 more authors.
Fuel | Year: 2014

"Stimulated reservoir volume" (SRV) makes it possible for commercial production of shale gas by means of multistage fracturing of horizontal wells. However, the formation mechanism of effective fracture network has not been well understood. The mechanism of fracture propagation in shale with hydraulic fracturing needs to be further explored, in order to realize the control on morphology of fracture network with SRV and increase the single well production of shale gas. In this article, the true triaxial test system was deployed for horizontal well hydraulic fracturing simulation experiments of shale outcrops for the first time. The effects of multiple factors on propagating rules of fractures of horizontal well in shale with SRV were studied, and the fracture morphology of post-fracturing rock cores was observed for the first time by high-energy CT scanning using the large-scale non-destructive testing system based on linear accelerator. The results show that the influence of flow rate (for SRV) on fracture complexity differs when its value falls in different intervals. When the horizontal in situ stress difference is less than 9 MPa, the hydraulic fracture easily propagates along the natural fractures, forming a fracture network. In this range, when the stress difference is increased, the appearance of the main hydraulic fracture contributes to interconnecting more natural fractures, forming a relatively more complex fracture system. Under the condition of the same horizontal stress difference, if the coefficient of stress difference Kh > 0.25, there is an obvious trend to form single main fracture. The effects of viscosity of fracturing fluid and flow rate on the fracture propagation can be expressed by the parameter q·μ. When the order of magnitude of q·μ-value is 10-9 N m, it is favorable to the generation of fracture network, but too small or too large values are both harmful. The development and cementing strength of depositional beddings seriously affect the propagating complexity of fracture network with hydraulic fracturing. Refracturing helps to produce some new fractures which are different from the initial ones, and better fracturing effect is achieved. The fracture initiation morphology in perforation fracturing is closely related to the distribution of natural fractures (depositional bedding) around the perforations. If the pressure curve fluctuates significantly, it is indicated that the shale core contains a large number of opened natural fractures or depositional beddings before fracturing, which causes the serious loss of fracturing fluid in the propagation process. © 2014 Elsevier Ltd. All rights reserved.


Jin M.,Hunan University | Li R.,Smart Control | Xu Z.,Smart Control | Zhao X.,Bohai University | Zhao X.,China University of Petroleum - East China
Neurocomputing | Year: 2014

In this paper, a fuzzy ARTMAP (FAM) ensemble approach based on the improved Bayesian belief method is presented and applied to the fault diagnosis of rolling element bearings. First, by the statistical method, continuous Morlet wavelet analysis method and time series analysis method many features are extracted from the vibration signals to depict the information about the bearings. Second, with the modified distance discriminant technique some salient and sensitive features are selected. Finally, the optimal features are input into a committee of FAMs in different sequence, the output from these FAMs is combined and the combined decision is derived by the improved Bayesian belief method. The experiment results show that the proposed FAMs ensemble can reliably diagnose different fault conditions including different categories and severities, and has a better diagnosis performance compared with single FAM. © 2014 Elsevier B.V.


Huang J.,Rice University | Huang J.,China University of Petroleum - East China | Vanacore E.,Rice University | Niu F.,Rice University | Levander A.,Rice University
Earth and Planetary Science Letters | Year: 2010

We analyzed receiver-function data recorded by a temporary broadband array deployed as part of the BOLIVAR project and the permanent seismic network of Venezuela to study the mantle transition zone structure beneath the Caribbean-South American plate boundary and Venezuela. Significant topography on both the 410-km and the 660-km discontinuities was clearly imaged in the CCP (common-conversion-point) stacked images. Beneath the southeastern Caribbean, the 410-km is featured by a narrow (∼ 200 km EW) ∼ 25-km uplift extending in the NS direction around 63° west, while the 660-km is depressed by ∼ 20 km in a narrow region slightly west to the uplift, a scenario that is more consistent with westward descent of the oceanic South American plate rather than a break-off of NNW dipping proto-Caribbean oceanic lithosphere along the El Pilar Fault. We also found a thick transition zone beneath the Falcon region in northwestern Venezuela, possibly associated with the subducted Nazca plate. A flat 410-km was observed beneath the Guayana shield, suggesting that the shield has a stable and moderately deep keel, which has little effect on the underlying transition zone structure. © 2009 Elsevier B.V. All rights reserved.


Liu M.,Harbin Institute of Technology | Shi P.,University of South Wales | Shi P.,Victoria University of Melbourne | Shi P.,University of South Australia | And 2 more authors.
IEEE Transactions on Circuits and Systems I: Regular Papers | Year: 2011

This paper investigates the problem of sensor fault estimation and fault-tolerant control for Markovian jump systems with time delay and Lipschitz nonlinearities. The issues involved here are: i) sensor faults; ii) model Lipchitz nonlinearities; iii) system structure changes governed by Markovian jumping parameters; and iv) time delay in system states. Such type of mathematical models can represent a large number of practical systems in the actual engineering. A new estimation technique (named proportional and derivative sliding mode observer) is developed to deal with this design problem. The proposed observer is mode-dependent type in which a derivative gain and a proportional gain are introduced to provide more design freedom, and a discontinuous input term is introduced to eliminate the effects of sensor faults. By employing the developed estimation technique, the asymptotic estimations of system states and sensor faults can be obtained simultaneously. Based on the estimation, an observer-based fault-tolerant control scheme is developed to stabilize the resulting closed-loop system. Finally, a numerical example is presented to illustrate the effectiveness and applicability of the proposed technique. © 2011 IEEE.


Zhang X.,China University of Petroleum - East China | Lin C.,China University of Petroleum - East China | Zhang T.,China University of Petroleum - East China | Liu W.,Dagang Oilfield Company
Shiyou Kantan Yu Kaifa/Petroleum Exploration and Development | Year: 2011

In shallow sea areas with irregular well pattern and sparse well control, the accuracy of reservoir characterization based on well logging data is too low to satisfy the need of reservoir development research. A seismic sedimentologic study is made in the Block I of Chenghai Oilfield, Dagang. The architecture of braided bars is characterized finely by the inter-calibration and inter-restriction of vertical and horizontal information. Seismic data is processed with technologies of phasing and stratal slicing and then the amplitude on slice is interpreted to obtain the planar distribution of bars. The evolution of braided bars is analyzed with research on slices of different depth. In this research, sand layer of the braided bar in NgI1-1 formation is subdivided into three parts, each of which is formed by a stage of flood deposition. The sedimentary characteristics and evolution revealed by stratal slice interpretation is verified by fine research of vertical and horizontal wells. A sedimentary model is built and will play an important role in horizontal well development and in the architecture characterization of reservoirs without wells.


Ji J.,Xiamen University | Liu H.,Xiamen University | Chen J.,Xiamen University | Zeng J.,China University of Petroleum - East China | And 4 more authors.
Journal of Chromatography A | Year: 2012

Zinc oxide (ZnO) nanorods based solid-phase microextraction (SPME) coating was directly prepared on stainless steel wires using in situ hydrothermal growth method. This coating has high surface-to-volume ratio with a diameter in the range of 300-500nm and a thickness of about 3-5μm. A guiding tube was introduced into the laboratory-made SPME fiber to protect the ZnO nanorods coating from shaving, which significantly improved the method repeatability and prolonged the service life of the coating. The extraction properties of the prepared fiber were investigated using headspace SPME (HS-SPME) coupled to gas chromatography (GC) for the determination of aldehydes in instant noodle samples. The extraction efficiency of the coating for the five aldehydes was comparable to that of a commercial 85μm Carboxen/Polydimethylsiloxane fiber, which has been reported to have best affinity towards aldehydes among all commercial fibers. The linear ranges of the proposed HS-SPME-GC method were from 0.05 to 5μgg -1 (hexanal, nonanal and decanal) and 0.1-5μgg -1 (heptanal and octanal), with the correlation coefficients from 0.990 to 0.999. The method developed was successfully applied to the determination of five aldehydes in instant noodle samples, and the recoveries were found to be 70.5-129% at the spiking level of 2μgg -1. © 2012 Elsevier B.V.


Song Y.,China University of Petroleum - East China | Ren J.,China University of Geosciences | Stepashko A.A.,Russian Academy of Sciences | Li J.,CAS Nanjing Institute of Geology and Palaeontology
Tectonophysics | Year: 2014

The T11 unconformity lies between the Qingshankou and Yaojia Formations in the post-rifting sequence of the Cretaceous Songliao Basin, NE China. It is intimately associated with petroleum reservoirs and considered to be a disconformity forming in the tectonic quiet stage. We present the interpretations from new seismic surveys and cored sections of the Cretaceous Continental Scientific Drilling borehole (CCSD-SK-1) in order to resolve the nature and origin of T11 unconformity. The T11 is often a low-angle unconformity with underlying Qingshankou Formation having been deformed and eroded prior to deposition of the Yaojia Formation. In the post-rift evolution of the basin it marks an abrupt change from a deep lake to shallow lake or subaerial environment, documented by reddening of the lacustrine mudstone, extinction of the ostracod assemblages and a great increase of coarse detrital inputs. The sharp change of depositional environment, the truncation of gentle folds and the cluster of volcanic and paleoearthquake activities, all happened simultaneously, immediately before the development of T11 unconformity, indicating a significant regional compressional uplift event in the basin. The timing of the T11 unconformity formation is within the interval 88-86.2. Ma. Correlations with coeval unconformities in other Cretaceous sedimentary basins in eastern Asia indicate that this compressional uplift coincided with an episode of global plate reorganization between the Eurasian and Paleo-Pacific plates that culminated at 88-87. Ma. During this short interval the northeast Asian margin, in eastern China, South Korea, Japan and Russian Far East experienced widespread violent volcanic and granite emplacement activity triggered by compression resulting from rapid and orthogonal slab subduction. The post-rift basin tectonic inversion occurred during T11 (Coniacian) time; thereafter the basin again evolved in an extension regime. Two subsidence phases in post-rift history took place as the direct consequence of Coniacian compression peak, which defined the distribution of oil sources and reservoirs. © 2014 Elsevier B.V.


Zhan K.,China University of Petroleum - East China | Hou C.,Harbin Institute of Technology
Optics Express | Year: 2014

We study theoretically surface lattice solitons driven by quadratic electro-optic effect at the interface between an optical lattice and diffusive nonlinear media with self-focusing and self-defocusing saturable nonlinearity. Surface solitons originating from self-focusing nonlinearity can be formed in the semi-infinite gap, and are stable in whole domain of their existence. In the case of self-defocusing nonlinearity, both surface gap and twisted solitons are predicted in first gap. We discover that surface gap solitons can propagate stably in whole existence domain except for an extremely narrow region close to the Bloch band, and twisted solitons are linearly unstable in the entire existence domain. © 2014 Optical Society of America.


Liu W.,China University of Petroleum - East China | Tao D.,Intelligent Systems Technology, Inc. | Cheng J.,CAS Shenzhen Institutes of Advanced Technology | Cheng J.,Chinese University of Hong Kong | Tang Y.,Macau University of Science and Technology
Computer Vision and Image Understanding | Year: 2014

Sparse coding represents a signal sparsely by using an overcomplete dictionary, and obtains promising performance in practical computer vision applications, especially for signal restoration tasks such as image denoising and image inpainting. In recent years, many discriminative sparse coding algorithms have been developed for classification problems, but they cannot naturally handle visual data represented by multiview features. In addition, existing sparse coding algorithms use graph Laplacian to model the local geometry of the data distribution. It has been identified that Laplacian regularization biases the solution towards a constant function which possibly leads to poor extrapolating power. In this paper, we present multiview Hessian discriminative sparse coding (mHDSC) which seamlessly integrates Hessian regularization with discriminative sparse coding for multiview learning problems. In particular, mHDSC exploits Hessian regularization to steer the solution which varies smoothly along geodesics in the manifold, and treats the label information as an additional view of feature for incorporating the discriminative power for image annotation. We conduct extensive experiments on PASCAL VOC'07 dataset and demonstrate the effectiveness of mHDSC for image annotation. © 2013 Elsevier Inc. All rights reserved.


Guo A.,China University of Petroleum - East China | Lin X.,China University of Petroleum - East China | Lin X.,Sinopec | Liu D.,China University of Petroleum - East China | And 2 more authors.
Fuel Processing Technology | Year: 2012

A systematic study was undertaken to reveal shot-coke formation pathway and to find solutions to minimize and even eliminate shot-coke formation during heavy oil delayed coking. The heavy oil used as coking feedstock was in the form of vacuum residue. Shot-coke-forming propensity was characterized by dynamic monitoring optical texture in the coke product, and coke morphology was macroscopically recorded by photography. Results show that the pathway for shot-coke formation is distinctively stepwise: Feedstock → Formation of anisotropic spherules → Limited growth of the spherules in the viscous coking system → Mosaic optical texture in the solidifying bulk coke → Formation of primary shot coke → Formation of secondary shot coke. Coking feedstocks with higher asphaltene content, higher carbon residues, and higher heteroatom content have higher propensity to form shot coke. Particularly, when a coking feedstock has an asphaltene/Conradson carbon residue mass ratio greater than 0.5, H/C molar ratio less than 1.5, and colloidal stability parameter less than 3.5, it could be tentatively called shot-coke-forming feedstock, which shows dominant mosaic optical texture in the coke derived from typical delayed coking conditions. Hydrogen donating additives such as suitable FCC slurry (raw, i.e. without HDA/HDS treatment) are economically advantageous in reducing shot-coke-forming propensity. Feedstock blending, decreasing coking temperature, increasing coking pressure, increasing recycle ratio, and employing hydrogen donating additives are potentially effective measures for controlling shot-coke formation. © 2012 Elsevier B.V.


Wang F.,China University of Petroleum - East China | Shuai Y.,Harbin Institute of Technology | Wang Z.,Shandong University | Leng Y.,China University of Petroleum - East China | Tan H.,Harbin Institute of Technology
International Journal of Hydrogen Energy | Year: 2014

In order to investigate the thermochemical reaction performance of steam methane reforming (SMR), the steady heat and mass transfer model coupled with thermochemical reaction kinetics is developed for the volumetric porous media solar thermochemical reactor. The local non-thermal equilibrium (LNTE) model with modified P1 approximation is adopted to investigate the temperature distributions of the solid phase and fluid phase. For the solid phase energy equation, the irradiative heat transfer coupled with chemical reaction kinetics is programmed via User Defined Functions (UDFs). The concentrated solar irradiation is not only considered as the boundary condition at the reactor front surface, but also as the irradiative heat source in the whole volume of reactor. The parametric studies are conducted to investigate the thermal and hydrogen production performances as a function of operational parameters. The numerical results indicate that SMR reaction has big effects on temperature distribution. The generated H2 mole fraction decreases sharply with the increasing of fluid inlet velocity, porosity and mean cell size. The generated H2 mole fraction increases significantly with the increasing of incident solar irradiance. Copyright © 2013, Hydrogen Energy Publications, LLC.


Wang F.,China University of Petroleum - East China | Lin R.,China University of Petroleum - East China | Liu B.,Harbin Institute of Technology | Tan H.,Harbin Institute of Technology | Shuai Y.,Harbin Institute of Technology
Solar Energy | Year: 2013

The bottom surface of conventional cavity receiver cannot be fully covered by coiled metal tube during fabrication, which would induce a dead space of solar energy absorption. The dead space of solar energy absorption can severely decrease the optical efficiency of cavity receiver. Two new types of cavity receiver with bottom surface convex are put forward with the objective to solve the problem of dead space of solar energy absorption and improve the optical efficiency of cavity receiver. The optical efficiency and heat flux distribution of the two new types of cavity receiver are analyzed by Monte Carlo ray tracing method. Besides, the optical efficiency comparisons between conventional cavity receiver and the two new types of cavity receiver are conducted at different characteristic parameter conditions. © 2013 Elsevier Ltd.


Wang F.,China University of Petroleum - East China | Shuai Y.,Harbin Institute of Technology | Tan H.,Harbin Institute of Technology | Zhang X.,Harbin Institute of Technology | Mao Q.,Harbin Institute of Technology
Solar Energy | Year: 2013

In this paper, Monte Carlo Ray Tracing (MCRT) and Finite Volume Method (FVM) coupling method is adopted to solve the radiation, conduction and convection coupled heat transfer problems of porous media receiver with multi-dish collector. The MCRT method is used to obtain the concentrated heat flux distribution on the fluid inlet surface of porous media receiver. The local thermal non-equilibrium (LTNE) model with concentrated solar irradiation on the fluid inlet surface is used for energy equations. FVM software FLUENT with User Defined Functions (UDFs) is used to solve the fluid phase and solid phase heat transfer problems. The effects of solar irradiance, air inlet velocity, average particle diameter, receiver radius and air properties on the temperature distribution are investigated. © 2013 Elsevier Ltd.


Wang F.,Harbin Institute of Technology | Tan J.,Harbin Institute of Technology | Shuai Y.,Harbin Institute of Technology | Gong L.,China University of Petroleum - East China | Tan H.,Harbin Institute of Technology
Energy Conversion and Management | Year: 2014

The calorific value of syngas can be greatly upgraded during the methane steam reforming process by using concentrated solar energy as heat source. In this study, the Monte Carlo Ray Tracing (MCRT) and Finite Volume Method (FVM) coupling method is developed to investigate the hydrogen production performance via methane steam reforming in porous media solar thermochemical reactor which includes the mass, momentum, energy and irradiative transfer equations as well as chemical reaction kinetics. The local thermal non-equilibrium (LTNE) model is used to provide more temperature information. The modified P1 approximation is adopted for solving the irradiative heat transfer equation. The MCRT method is used to calculate the sunlight concentration and transmission problems. The fluid phase energy equation and transport equations are solved by Fluent software. The solid phase energy equation, irradiative transfer equation and chemical reaction kinetics are programmed by user defined functions (UDFs). The numerical results indicate that concentrated solar irradiation on the fluid entrance surface of solar chemical reactor is highly uneven, and temperature distribution has significant influence on hydrogen production. © 2014 Elsevier Ltd. All rights reserved.


Zhan K.,Harbin Institute of Technology | Zhan K.,China University of Petroleum - East China | Hou C.,Harbin Institute of Technology | Du Y.,Harbin Institute of Technology
Optics Communications | Year: 2010

The effects of diffusion on self-deflection of steady-state bright spatial solitons in biased centrosymmetric photorefractive crystals are investigated systematically by both numerical and perturbation methods. The results show that the soliton propagates along a parabolic trajectory and the central spatial frequency component shifts linearly with the propagation distance. Both the deflection effects vary cubically with applied external bias field. © 2009 Elsevier B.V. All rights reserved.


Zhao G.,China University of Petroleum - East China | Dai C.,China University of Petroleum - East China | Zhao M.,China University of Petroleum - East China | You Q.,China University of Geosciences
Journal of Applied Polymer Science | Year: 2014

The use of gel systems as profile control and water shutoff agents has become a wide practice in recent years for oil recovery applications. But few systematic studies have been carried out on the microstructure of gels. In this study, environmental scanning electron microscopy (ESEM) was employed to investigate the microstructure of gels in their natural state. It was directly observed that a three-dimensional network structure formed in chromium or zirconium crosslinked polymer gels is the same as organic/ inorganic crosslinked gels. However, there is a dense flat structure in phenol resin crosslinked polymer gels or phenolic resin gels. The differences between the microstructures can be attributed to the different crosslinking sites and crosslinking density, and this affect the gel's stability at reservoir temperatures. In addition, this paper also introduced the crosslinking mechanism and macro-morphology of the bulk gels. It can contribute to a better understanding of the gel's microstructure. © 2013 Wiley Periodicals, Inc.


Guo X.,Harbin Engineering University | Liu L.,Harbin Institute of Technology | Liu Y.,Harbin Institute of Technology | Zhou B.,China University of Petroleum - East China | Leng J.,Harbin Institute of Technology
Smart Materials and Structures | Year: 2014

Recently, increasing applications of shape memory polymers have pushed forward the development of appropriate constitutive models for smart materials such as the shape memory polymer. During the heating process, the phase transition, which is a continuous time-dependent process, happens in the shape memory polymer, and various individual phases will form at different configuration temperatures. In addition, these phases can generally be divided into two parts: the frozen and active phase (Liu Y et al 2006 Int. J. Plast. 22 279-313). During the heating or cooling process, the strain will be stored or released with the occurring phase transition between these two parts. Therefore, a shape memory effect emerges. In this paper, a new type of model was developed to characterize the variation of the volume fraction in a shape memory polymer during the phase transition. In addition to the temperature variation, the applied stress was also taken as a significant influence factor on the phase transition. Based on the experimental results, an exponential equation was proposed to describe the relationship between the stress and phase transition temperature. For the sake of describing the mechanical behaviors of the shape memory polymer, a three-dimensional constitutive model was established. Also, the storage strain, which was the key factor of the shape memory effect, was also discussed in detail. Similar to previous works, we first explored the effect of applied stress on storage strain. Through comparisons with the DMA and the creep experimental results, the rationality and accuracy of the new phase transition and constitutive model were finally verified. © 2014 IOP Publishing Ltd.


Yan Y.,China University of Petroleum - East China | Cheng L.,China Petroleum Engineering and Construction Corporation
Advanced Materials Research | Year: 2012

Seismic loading is one of the most important factors of submarine pipeline damage, so the research on submarine pipeline failure mechanism is still lifeline engineering frontier topics. According to Biot consolidation theory, considering the interaction of submarine pipelines with the soil medium under earthquake action, the model of the seabed-pipeline interaction is established. The influences of wall thickness, radius and cover layer thickness on submarine pipeline strain response are studied under El Centro seismic wave based on this model. The calculating results show that effective stress and axial strain of the submarine pipeline increases with wall thickness, radius and cover layer thickness increasing. © (2012) Trans Tech Publications, Switzerland.


Zhan K.,China University of Petroleum - East China | Hou C.,Harbin Institute of Technology
Optics Communications | Year: 2012

We analyze the existence and stability of gap solitons supported by optical lattices with self-focusing nonlinearity in biased centrosymmetric photorefractive crystals. It is shown that, in first finite bandgap, gap solitons are symmetric in transverse dimension, single humped, entirely positive and linearly stable, while these solitons are antisymmetric with similar profiles, the stable and unstable intervals of the gap solitons are intertwined in the second finite bandgap. © 2012 ElsevierB.V.Allrightsreserved.


Liu H.,Harbin Institute of Technology | Shen Y.,Harbin Institute of Technology | Zhao X.,China University of Petroleum - East China
Nonlinear Analysis: Hybrid Systems | Year: 2013

This paper concerns the asynchronous finite-time H∞ control problem for a class of switched linear systems with time-varying disturbances. The asynchronous switching means that the switchings between the candidate controllers and system modes are asynchronous. By using the Average Dwell Time (ADT) and Multiple Lyapunov Functions (MLFs) technologies, some sufficient conditions which can guarantee that the corresponding closed-loop system is finite-time bounded with a prescribed H∞ performance index via asynchronously switched control, are derived for the switched linear systems. Unlike the traditional Lyapunov asymptotic stability, there is no requirement of negative definiteness (or semidefiniteness) on the derivative of Lyapunov-like function. Moreover, a set of mode-dependent dynamic state feedback controllers are designed. Finally, two examples are provided to verify the efficiency of the proposed method. © 2012.


Liu H.,Harbin Institute of Technology | Shen Y.,Harbin Institute of Technology | Zhao X.,China University of Petroleum - East China
Journal of the Franklin Institute | Year: 2013

In this paper, finite-time stabilization and boundedness (FTSB) problems are investigated. Unlike the existing approach based on time-dependent switching strategy, in which the switching instants must be given in advance, largest region function strategy, i.e., state-dependent switching strategy, is adopted to design the switching signal. Based on multiple Lyapunov-like functions method, some sufficient conditions are provided for FTSB of switched linear system and the corresponding sliding motion problem is also considered. Finally, two examples are given to verify the efficiency of the proposed methods. © 2012 The Franklin Institute.


Zhao X.,China University of Petroleum - East China | Liu H.,Harbin Institute of Technology | Wang Z.,Harbin Institute of Technology
International Journal of Systems Science | Year: 2013

This article is concerned with the disturbance attenuation properties of a class of switched linear systems by using a mode-dependent average dwell time (MDADT) approach. The proposed switching law is less strict than the average dwell time (ADT) switching in that each mode in the underlying system has its own ADT. By using the MDADT approach, a sufficient condition is obtained to guarantee the exponential stability with a weighted H ∞ performance for the underlying systems. A numerical example is given to show the validity and potential of the developed results on improving the disturbance attenuation performance. © 2013 Copyright Taylor and Francis Group, LLC.


Li Y.,Harbin Institute of Technology | Li Y.,China University of Petroleum - East China | Wang M.,Harbin Institute of Technology
Nonlinear Analysis: Real World Applications | Year: 2013

The paper is concerned with a diffusive prey-predator model subject to the homogeneous Neumann boundary condition, which models the trophic intersections of three levels. We will prove that under certain assumptions, even though the unique positive constant steady state is globally asymptotically stable for the dynamics with diffusion, the non-constant positive steady state can exist due to the emergence of cross-diffusion. We demonstrate that the cross-diffusion can create stationary pattern. Moreover, we treat the cross-diffusion parameter as a bifurcation parameter and discuss the existence of non-constant positive solutions to the system with cross-diffusion. © 2012 Elsevier Ltd. All rights reserved.


Zuo H.,CAS Institute of Automation | Zuo H.,China University of Petroleum - East China | Hu W.,CAS Institute of Automation | Wu O.,CAS Institute of Automation
Proceedings of the 19th International Conference on World Wide Web, WWW '10 | Year: 2010

Along with the explosive growth of the World Wide Web, an immense industry for the production and consumption of pornography has grown. Though the censorship and legal restraints on pornography are discriminating in different historical, cultural and national contexts, selling pornography to minors is not allowed in most cases. Detecting human skin tone is of utmost importance in pornography image filtering algorithms. In this paper, we propose two patch-based skin color detection algorithms: regular patch and irregular patch skin color detection algorithms. On the basis of skin detection, we extract 31-dimensional features from the input image, and these features are fed into a random forest classifier. Our algorithm has been incorporated into an adult-content filtering infrastructure, and is now in active use for preventing minors from accessing pornographic images via mobile phones. © 2010 Copyright is held by the author/owner(s).


Wu J.-F.,China University of Petroleum - East China | Zhang R.,China University of Petroleum - East China | Wang R.-H.,China University of Petroleum - East China | Yao Y.-X.,Harbin Institute of Technology
International Journal of Machine Tools and Manufacture | Year: 2014

Parallel kinematics machine has attracted attention as machine tools because of the outstanding features of high dynamics and high stiffness. Although various calibration methods for parallel kinematics machine have been studied, the influence of inaccurate motion of joints is rarely considered in these studies. This paper presents a high-accuracy and high-effective approach for calibration of parallel kinematics machine. In the approach, a differential error model, an optimized model and a statistical method are combined, and the errors of parallel kinematics machine due to inaccurate motion of joints can be reduced by this approach. Specifically, the workspace is symmetrically divided into four subspaces, and a measurement method is suggested by a laser tracker to require the actual pose of the platform in these subspaces. An optimized model is proposed to solve the kinematic parameters in symmetrical subspaces, and then arithmetical mean method is proposed to calculate the final kinematic parameter. In order to achieve the global optimum quickly and precisely, the initial value of the optimal parameter is directly solved based on the differential error model. The proposed approach has been realized on the developed 5-DOF hexapod machine tool, and the experiment result proves that the presented method is very effective and accurate for the calibration of the hexapod machine tool. © 2014 Elsevier Ltd. All rights reserved.


Yang Y.,China University of Petroleum - East China | Qiu L.,China University of Petroleum - East China | Jiang Z.,China University of Geosciences | Yin X.,Sinopec
Shiyou Xuebao/Acta Petrolei Sinica | Year: 2011

The upper part of the fourth member of the Shahejie Formation in the Dongying Sag consists mainly of gravelly beach bar, sandy beach bar and carbonate beach bar. The present paper proposed that the formation of these beach bars showed a certain correlation with their sources, which was mainly influenced by combination of source type, source supply, hydrodynamic conditions and so on. There existed a significant difference in characteristics between the macro-distribution and the micro-deposition of beach bars in various regions of the Dongying Sag. Based on the detailed analysis of sedimentary characteristics, the paper divided beach bars of the upper part of the fourth member of the Shahejie Formation into several sedimentary systems, such as bedrock-beach bar, normal delta-beach bar, fan delta-beach bar and carbonate-beach bar. Consequently, the corresponding sedimentary patterns were established in order to provide guidance for oil and gas exploration in the Dongying Sag.


Shao H.,China University of Petroleum - East China | Zheng G.,JANA Solutions Inc.
Neurocomputing | Year: 2011

In this paper, the deterministic convergence of an online gradient method with penalty and momentum is investigated for training two-layer feedforward neural networks. The monotonicity of the new error function with the penalty term in the training iteration is firstly proved. Under this conclusion, we show that the weights are uniformly bounded during the training process and the algorithm is deterministically convergent. Sufficient conditions are also provided for both weak and strong convergence results. © 2010 Elsevier B.V.


Shao H.,China University of Petroleum - East China | Zheng G.,JANA Solutions Inc.
Neurocomputing | Year: 2011

In this paper, the convergence of a new back-propagation algorithm with adaptive momentum is analyzed when it is used for training feedforward neural networks with a hidden layer. A convergence theorem is presented and sufficient conditions are offered to guarantee both weak and strong convergence result. Compared with existing results, our convergence result is of deterministic nature and we do not require the error function to be quadratic or uniformly convex. © 2010 Elsevier B.V.


Wang F.,China University of Petroleum - East China | Shuai Y.,Harbin Institute of Technology | Tan H.,Harbin Institute of Technology | Yu C.,Harbin Institute of Technology
International Journal of Heat and Mass Transfer | Year: 2013

The distribution of concentrated solar irradiation has a significantly impact on the temperature distribution of porous media receiver. The thermal performance of porous media receiver is investigated by combining the Monte Carlo Ray Tracing (MCRT) method and FLUENT software with user defined functions (UDFs). The MCRT method is used to obtain the heat flux distribution on the fluid inlet surface of porous media receiver. The calculated heat flux distribution is treated as the wall heat flux boundary condition of thermal performance analysis. The local non-equilibrium thermal equation (LNTE) model with Rosseland approximation is used to investigate the temperature distributions. Typical influences of the heat flux boundary condition, radiation heat loss, porosity, emissivity, flow mass and average particle diameter on the temperature distributions are investigated. © 2013 Elsevier Ltd. All rights reserved.


Zhang X.,Harbin Institute of Technology | Zhang X.,China University of Petroleum - East China | Li W.,Harbin Institute of Technology | Liu M.,Huaiyin Normal University | Wang K.,Harbin Institute of Technology
Physica A: Statistical Mechanics and its Applications | Year: 2015

In this paper, a stochastic Holling II one-predator two-prey system with jumps is investigated. Firstly, the properties of the solution, such as the existence and uniqueness of the global positive solution, stochastic ultimate boundedness and the pathwise estimation are studied. Then we mainly establish the sufficient conditions for the extinction and persistence in the mean of the solution. Results show that positive jump noise is advantageous to the system while negative jump noise is disadvantageous. Finally, a numerical example is introduced to illustrate the results. © 2014 Elsevier B.V. All rights reserved.


Liu H.,Harbin Institute of Technology | Shen Y.,Harbin Institute of Technology | Zhao X.,China University of Petroleum - East China
Nonlinear Analysis: Hybrid Systems | Year: 2012

This paper is concerned with the problem of observer design for switched linear systems with time-varying delay and exogenous disturbances. The attention is focused on designing the full-order observers that guarantee the finite-time bounded and H ∞ finite-time stability of the dynamic augmented system. Based on linear matrix inequalities (LMIs) technology and an average dwell time (ADT) approach, sufficient conditions which ensure the observer-based finite-time bounded and H ∞ finite-time stability are given, respectively. By using a state observer, the memory state feedback controller is designed to finite-time stabilize a time-delay switched system, and the conditions are formulated in terms of delay-dependent LMIs. An example is given to illustrate the efficiency of the proposed methods. © 2012 Elsevier Ltd.


Zuo W.,Harbin Institute of Technology | Zuo W.,China University of Petroleum - East China | Wei J.,Harbin Institute of Technology
International Journal of Bifurcation and Chaos | Year: 2012

A diffusive Brusselator model with delayed feedback control subject to Dirichlet boundary condition is considered. The stability of the unique constant equilibrium and the existence of a family of inhomogeneous periodic solutions are investigated in detail, exhibiting rich spatiotemporal patterns. Moreover, it shows that Turing instability occurs without delay. And under certain conditions, the constant equilibrium switches finite times from stability to instability to stability, and becomes unstable eventually, as the delay crosses through some critical values. Then, the direction and the stability of Hopf bifurcations are determined by the normal form theory and the center manifold reduction for partial functional differential equations. Finally, some numerical simulations are carried out for illustrating the analysis results. © 2012 World Scientific Publishing Company.


Li Y.,Harbin Institute of Technology | Li Y.,China University of Petroleum - East China
Nonlinear Analysis: Real World Applications | Year: 2011

This paper is concerned with a general Schnakenberg model subject to the homogeneous Neumann boundary condition. Various existence and non-existence results are obtained in terms of self-diffusion coefficients. © 2011 Elsevier Ltd. All rights reserved.


Zuo W.,Harbin Institute of Technology | Zuo W.,China University of Petroleum - East China | Wei J.,Harbin Institute of Technology
Nonlinear Analysis: Real World Applications | Year: 2011

This paper is concerned with a delayed predatorprey system with diffusion effect. First, the stability of the positive equilibrium and the existence of spatially homogeneous and spatially inhomogeneous periodic solutions are investigated by analyzing the distribution of the eigenvalues. Next the direction and the stability of Hopf bifurcation are determined by the normal form theory and the center manifold reduction for partial functional differential equations. Finally, some numerical simulations are carried out for illustrating the theoretical results. © 2011 Elsevier Ltd. All rights reserved.


Dai C.,China University of Petroleum - East China | Yan Z.,China University of Petroleum - East China | You Q.,China University of Geosciences | Du M.,China University of Petroleum - East China | Zhao M.,China University of Petroleum - East China
PLoS ONE | Year: 2014

Through the descriptive and rheological characterization of worm-like micelles formed by N-hexadecyl-N-methylpyrrolidinium bromide and sodium laurate, the formation and properties of the worm-like micelles were affected by the concentrations of sodium laurate and temperature. Additionally, cryogenic transmission electron microscopy images further validated the formation of worm-like micelles. © 2014 Dai et al.


Xiao Z.,China University of Petroleum - East China | Lu J.R.,University of Manchester
Biotechnology Advances | Year: 2014

Acetoin is a volatile compound widely used in foods, cigarettes, cosmetics, detergents, chemical synthesis, plant growth promoters and biological pest controls. It works largely as flavour and fragrance. Since some bacteria were found to be capable of vigorous acetoin biosynthesis from versatile renewable biomass, acetoin, like its reduced form 2,3-butanediol, was also classified as a promising bio-based platform chemical. In spite of several reviews on the biological production of 2,3-butanediol, little has concentrated on acetoin. The two analogous compounds are present in the same acetoin (or 2,3-butanediol) pathway, but their production processes including optimal strains, substrates, derivatives, process controls and product recovery methods are quite different. In this review, the usages of acetoin are reviewed firstly to demonstrate its importance. The biosynthesis pathway and molecular regulation mechanisms are then outlined to depict the principal network of functioning in typical species. A phylogenetic tree is constructed and the relationship between taxonomy and acetoin producing ability is revealed for the first time, which will serve as a useful guide for the screening of competitive acetoin producers. Genetic engineering, medium optimization, and process control are effective strategies to improve productivity as well. Currently, downstream processing is one of the main barriers in efficient and economical industrial acetoin fermentation. The future prospects of microbial acetoin production are discussed in light of the current progress, challenges, and trends in this field. © 2014 Elsevier Inc.


Liu Y.,Zhejiang University of Technology | Gao Z.,Zhejiang University of Technology | Li P.,Zhejiang University | Wang H.,China University of Petroleum - East China
Industrial and Engineering Chemistry Research | Year: 2012

An efficient nonlinear just-in-time learning (JITL) soft sensor method for online modeling of batch processes with uneven operating durations is proposed. A recursive least-squares support vector regression (RLSSVR) approach is combined with the JITL manner to model the nonlinearity of batch processes. The similarity between the query sample and the most relevant samples, including the weight of similarity and the size of the relevant set, can be chosen using a presented cumulative similarity factor. Then, the kernel parameters of the developed JITL-RLSSVR model structure can be determined adaptively using an efficient cross-validation strategy with low computational load. The soft sensor implement algorithm for batch processes is also developed. Both the batch-to-batch similarity and variation characteristics are taken into consideration to make the modeling procedure more practical. The superiority of the proposed soft sensor approach is demonstrated by predicting the concentrations of the active biomass and recombinant protein in the streptokinase fed-batch fermentation process, compared with other existing JITL-based and global soft sensors. © 2012 American Chemical Society.


Zhao X.,University of Manchester | Zhao X.,China University of Petroleum - East China | Pan F.,University of Manchester | Xu H.,University of Manchester | And 8 more authors.
Chemical Society Reviews | Year: 2010

Short synthetic peptide amphiphiles have recently been explored as effective nanobiomaterials in applications ranging from controlled gene and drug release, skin care, nanofabrication, biomineralization, membrane protein stabilization to 3D cell culture and tissue engineering. This range of applications is heavily linked to their unique nanostructures, remarkable simplicity and biocompatibility. Some peptide amphiphiles also possess antimicrobial activities whilst remaining benign to mammalian cells. These attractive features are inherently related to their selective affinity to different membrane interfaces, high capacity for interfacial adsorption, nanostructuring and spontaneous formation of nano-assemblies. Apart from sizes, the primary sequences of short peptides are very diverse as they can be either biomimetic or de novo designed. Thus, their self-assembling mechanistic processes and the nanostructures also vary enormously. This critical review highlights recent advances in studying peptide amphiphiles, focusing on the formation of different nanostructures and their applications in diverse fields. Many interesting features learned from peptide self-organisation and hierarchical templating will serve as useful guidance for functional materials design and nanobiotechnology (123 references). © 2010 The Royal Society of Chemistry.


Wang Z.L.,China University of Petroleum - East China | Mu H.T.,China University of Petroleum - East China | Liang J.G.,China University of Petroleum - East China | Tang D.W.,CAS Institute of Engineering Thermophysics
International Journal of Thermal Sciences | Year: 2013

This work uses 3ω thermometry to separate interface resistances with growth and opposing substrates for aligned MWCNT array between 280 and 380 K. The measured DLC-MWCNT and MWCNT-Si substrate thermal resistances range between 5 and 12 mm2 K W-1 and 0.8-2.1 mm2 K W -1, respectively. The temperature dependency of the measured heat capacity is well consistent with the predictions. The nonlinear temperature dependence of the interface resistance suggests an important role of phonon inelastic scattering including all the acoustic bands and greatly enhanced by the low frequency optical phonon bands with high velocity. The phonon transport physical mechanism of an isolated SWCNT well captures the temperature dependency of thermal capacity of the MWCNT array and only approximately captures the temperature dependency of thermal boundary resistance in the current experimental temperature range. © 2013 Elsevier Masson SAS. All rights reserved.


Liu D.,China University of Petroleum - East China | Zhao F.-Y.,TU Munich | Zhao F.-Y.,Hunan University of Technology | Wang H.-Q.,Hunan University of Technology | Rank E.,TU Munich
International Journal of Thermal Sciences | Year: 2013

The backward time modeling of diffusion-convection pollutant dispersions has been developed with quasi-reversibility method in this work. The procedure is applied to the backward time identification of the contaminant release history and source location in a three-dimensional slot ventilated building enclosure. Spatial distributions of pollutant concentrations are known in priori. The effects of supplying air velocity, pollutant source location, pollutant diffusivity property, and pollutant release time on the accuracy of the pollutant dispersion history recovery have been investigated. Numerical results demonstrate that the accuracy of the pollutant dispersion history recovery can be enhanced with different approaches and measures, including the promotion of room ventilation rate, the shrinkage of distance between the pollutant source and supplying air port, and the reduction of pollutant diffusivity. The facilitated implementations of boundary conditions and the improved generality of quasi-reversibility methods make the pollutant source history identifications of less computational efforts. Particularly, the good agreement of the backward time identified source location with the true situation fully shows that quasi-reversibility method is more competitive in the engineering applications involving with convective fluid flows. © 2012 Elsevier Masson SAS. All rights reserved.


Wang Z.L.,China University of Petroleum - East China | Tang D.W.,CAS Institute of Engineering Thermophysics
International Journal of Thermal Sciences | Year: 2013

The 3ω principle is presented for the measurement of the heat transfer coefficient (h) based on natural convection model and heat conduction model. The 3ω technique is used at room temperature to measure h over the surfaces of microwires of the diameters 10-100 μm at horizontal and vertical orientations. The fitted results show that the heat loss from the microscale platinum wire to the air is dominated by heat conduction and the natural convection contribution is negligible. The comparison of the measured third harmonics for horizontal and vertical wires justifies that the orientation effect is negligible at microscales. The measured value of h is nearly two orders larger than that at macro scale and of the similar order to those from other literatures. Based on the 3ω principle, an explicit expression with a heat conduction shape factor is introduced and can predict the heat transfer coefficient reasonably in the validated range of frequency. Both the experimental results and the theoretical analysis conclude that the scale effect of heat transfer may be contributed to two factors: the effect of buoyancy, the driving force at microscales may be negligible; the heat loss is enhanced mainly by high ratio of surface to volume at microscales. It also shows the validation of the 3ω principle for thin wire if the heat loss to surrounding gas is dominated by heat conduction at microscale. © 2012 Elsevier Masson SAS. All rights reserved.


Xiao Z.,China University of Petroleum - East China | Lu J.R.,University of Manchester
Journal of Agricultural and Food Chemistry | Year: 2014

Acetoin is a common food flavor additive. This volatile compound widely exists in nature. Some microorganisms, higher plants, insects, and higher animals have the ability to synthesize acetoin using different enzymes and pathways under certain circumstances. As a very active molecule, acetoin acts as a precursor of dozens of compounds. Therefore, acetoin and its derivatives are frequently detected in the component analysis of a variety of foods using gas chromatography-mass spectrometry. Because of the increasing importance of these compounds, this paper reviews the origins and natural existence of these substances, physiological roles, the biological synthesis pathways, nonenzymatic spontaneous reactions, and the common determination methods in foods. This work is the first review on dietary natural acetoin. © 2014 American Chemical Society.


Zhao F.-Y.,TU Munich | Zhao F.-Y.,Hunan University of Technology | Rank E.,TU Munich | Liu D.,China University of Petroleum - East China | And 2 more authors.
International Journal of Heat and Mass Transfer | Year: 2012

Combined natural convective heat and moisture transports in a moist-air-filled enclosure with four free vent ports are numerically investigated. Four situations of ambient air states, hot and humid (I), hot and arid (II), cold and arid (III), and cold and humid (IV), are taken into consideration. Convective transports of semi-enclosed air, heat and moisture are respectively analyzed using the contours of streamfunction, heatfunction and massfunction, in addition to the isotherms and iso-concentrations. Overall convective heat transfer rate (Nu) and moisture transfer rate (Sh) of the internal concentrated heat and moisture source have been correlated with the thermal Rayleigh number respectively within the domain of the heat transfer driven flows and that of moisture transfer driven flows. When different initial convective flow conditions were imposed in the cases (I) and (IV), dual steady flow states of semi-enclosed heat and moisture convection are observed, and heat and moisture transport potentials can be enhanced or inhibited depending on the flow solution branches. These results can be adopted to guide the design of natural ventilation in the humid regions. © 2012 Elsevier Ltd. All rights reserved.


Chen S.,Nankai University | Fan F.,Nankai University | Wang X.,Nankai University | Wu P.,Key Laboratory of Optical Information Science and Technology | And 2 more authors.
Optics Express | Year: 2015

A magneto-metasurface with nonreciprocal terahertz (THz) transmission has been proposed to form a THz isolator. Importantly, we have discussed the two necessary conditions for THz nonreciprocal transmission in the metasurface: (1) There should be magneto-optical responses for THz waves in the metasurface; (2) The transmission system of the metasurface needs to be asymmetric for forward and backward waves. These two conditions lead to the time reversal symmetry breaking of system, and the magnetoplasmon mode splitting and nonreciprocal resonance enhancement can be observed in the asymmetry magnetometasurface. Moreover, the isolation dependences and tunability on the external magnetic field and temperature have also been investigated, which shows that the best operating state with a high isolation can be designed. The numerical simulations show a maximum isolation of 43 dB and a 10 dB operating bandwidth of 20 GHz under an external magnetic field of 0.3 T, and the insertion loss is smaller than 1.79 dB. This low-loss, high isolation, easy coupling THz isolator has broadly potentials for THz application systems. © 2015 Optical Society of America.


Chen C.,China University of Petroleum - East China | Hu J.,China University of Petroleum - East China | Zhang S.,China University of Petroleum - East China | Zhou P.,China University of Petroleum - East China | And 5 more authors.
Biomaterials | Year: 2012

Biomimicry of antimicrobial peptides secreted by innate immune systems represents a major strategy in developing novel antibacterial treatments. There are however emerging concerns over the possible compromise of host natural defenses by these biomimetic peptides due to their structural similarity. In our recent work we have extended the search by exploring the potential from unnatural synthetic antimicrobial peptides. Here we show that a series of surfactant-like peptides (AmKn, m ≥ 3, n = 1, 2) can kill not only bacteria but also cancerous HeLa cells in similar manner. Under the same experimental conditions, however, these peptides showed little affinity to NIH 3T3 cells and human red blood cells (hRBCs), thus demonstrating high biocompatibility in selective responses to host mammalian cells and low hemolysis. A9K1 was most effective in killing HeLa cells, a trend consistent with their bactericidal effects against Escherichia coli and Bacillus subtilis. Mechanistic investigations through combined studies of SEM and fluorescence assays revealed that the killing of bacteria and cancerous cells was caused by disrupting cell membranes, initiated by electrostatic interactions between cationic peptides and negatively charged cell membranes. In contrast, the absence of such interactions in the case of NIH 3T3 and hRBCs over the same peptide concentration range rendered low cytotoxicity. The most effective killing power of A9K1 within this series benefited from the combined effects of several factors including modest micellar concentration and balanced amphiphilicity, consistent with its propensity of self-assembly and effective membrane lytic power. © 2011 Elsevier Ltd.


Wang S.,China University of Petroleum - East China | Xue J.,China University of Petroleum - East China | Ge X.,China University of Petroleum - East China | Fan H.,China University of Petroleum - East China | And 2 more authors.
Chemical Communications | Year: 2012

By manipulating the interfacial interactions between the peptide templates and the silicate species derived from TEOS and APTES, a facile biomimetic method was developed for the fabrication of silica nanostructures exhibiting "string-of-beads" and fibrillar morphologies of varied sizes. © 2012 The Royal Society of Chemistry.


Xu H.,China University of Petroleum - East China | Wang Y.,China University of Petroleum - East China | Ge X.,China University of Petroleum - East China | Han S.,China University of Petroleum - East China | And 5 more authors.
Chemistry of Materials | Year: 2010

Many de novo designed amphiphilic peptides capable of self-assembly and further structural templating into hierarchical organizations such as nanofibers and gels carry more than 10 amino acid residues. A curious question is now raised about the minimal size that is required for initiating amphiphilically driven nanostructuring. In this work, we show that ultrashort peptides I 3K and L3K could readily self-assemble into stable nanostructures. While L3K formed spherical nanospheres with diameters of ∼10-15 nm, I3K self-assembled into nanotubes with diameters of ∼10 nm and lengths of >5 μm. I3K nanotubes were very smooth and carried defined pitches of twisting. The difference could arise from the different β-sheet promoting power between isoleucine and leucine, suggesting that while hydrophobic interaction was dominant in the formation of L3K nanospheres hydrogen bonding governed the templating of antiparallel β-sheets and the subsequent formation of I3K nanotubes. Because of their extreme stability against heating or exposure to organic solvents, I3K nanotubes were used as templates for silicification from the hydrolysis of organosilicate precursors using TEOS (tetraethoxysilane). The lysine groups on the inner and outer nanotube surfaces worked to catalyze silicification, leading to the formation of silica nanotubes, which is evident from both AFM and TEM imaging. The formation of interesting nanotubes and nanospheres as demonstrated from very short peptide amphiphiles is significant for further exploration of their use in technological applications. © 2010 American Chemical Society.


Hu J.,China University of Petroleum - East China | Chen C.,China University of Petroleum - East China | Zhang S.,China University of Petroleum - East China | Zhao X.,First Peoples Hospital | And 3 more authors.
Biomacromolecules | Year: 2011

We report a new class of cationic amphiphilic peptides with short sequences, G(IIKK) nI-NH 2 (n = 1-4), that can kill Gram-positive and Gram-negative bacteria as effectively as several well-known antimicrobial peptides and antibiotics. In addition, some of these peptides possess potent antitumor activities against cancer cell lines. Moreover, their hemolytic activities against human red blood cells (hRBCs) remain remarkably low even at some 10-fold bactericidal minimum inhibitory concentrations (MICs). When bacteria or tumor cells are cocultured with NIH 3T3 fibroblast cells, G(IIKK) 3I-NH 2 showed fast and strong selectivity against microbial or tumor cells, without any adverse effect on NIH 3T3 cells. The high selectivity and associated features are attributed to two design tactics: the use of Ile residues rather than Leu and the perturbation of the hydrophobic face of the helical structure with the insertion of a positively charged Lys residue. This class of simple peptides hence offers new opportunities in the development of cost-effective and highly selective antimicrobial and antitumor peptide-based treatments. © 2011 American Chemical Society.


Tao K.,China University of Petroleum - East China | Wang J.,China University of Petroleum - East China | Zhou P.,China University of Petroleum - East China | Wang C.,China University of Petroleum - East China | And 3 more authors.
Langmuir | Year: 2011

We report the characterization of self-assembly of two short β-amyloid (Aβ) peptides (16-22), KLVFFAE and Ac-KLVFFAE-NH2, focusing on examining the effect of terminal capping. At pH 2.0, TEM and AFM imaging revealed that the uncapped peptide self-assembled into long, straight, and unbranched nanofibrils with a diameter of 3.8 ± 1.0 nm while the capped one formed nanotapes with a width of 70.0 ± 25.0 nm. CD analysis indicated the formation of β-sheet structures in both aggregated systems, but the characteristic CD peaks were less intense and less red-shifted for the uncapped than the capped one, indicative of weaker hydrogen bonding and weaker π-π stacking. Fluorescence and rheological measurements also confirmed stronger intermolecular attraction associated with the capped nanotapes. At acidic pH 2, each uncapped KLVFFAE molecule carries two positive charges at the N-terminus, and the strong electrostatic repulsion favors interfacial curving and twisting within the β-sheet, causing weakening of hydrogen bonds and π-π stacking. In contrast, capping reduces the charge by half, and intermolecular electrostatic repulsion is drastically reduced. As a result, the lateral attraction of β-sheets favors stronger lamellar structuring, leading to the formation of rather flat nanotapes. Flat tapes with similar morphological structure were also formed by the capped peptide at pH 12.0 where the charge on the capping end was reversed. This study has thus demonstrated how self-assembled nanostructures of small peptides can be manipulated through simple molecular structure design and tuning of electrostatic interaction. © 2011 American Chemical Society.


Liu J.,China University of Petroleum - East China | Yin M.,China University of Petroleum - East China | Zhu H.,China University of Petroleum - East China | Lu J.,University of Manchester | Cui Z.,University of Oxford
Extremophiles | Year: 2011

Thermostable Mn-dependent catalases are promising enzymes in biotechnological applications. In the present study, a Mn-containing superoxide dismutase of the hyperthermophilic Thermus thermophilus HB27 had been purified and characterized by a two-stage ultrafiltration process after being expressed in E. coli. The enzyme was highly stable at 90°C and retained 57% activity after heat treatment at 100°C for 1h. The native form of the enzyme was determined as a homotetramer by analytical size exclusion chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The final purified enzyme had an isoelectric point of 6.2 and a high α-helical content of 70%, consistent with the theoretical values. This showed that the purified SOD folded with a reasonable secondary structure. © 2010 Springer.


Xiao Z.,China University of Petroleum - East China | Wang X.,China University of Petroleum - East China | Huang Y.,China University of Petroleum - East China | Huo F.,China University of Petroleum - East China | And 3 more authors.
Biotechnology for Biofuels | Year: 2012

Background: Acetoin and 2,3-butanediol are two important biorefinery platform chemicals. They are currently fermented below 40°C using mesophilic strains, but the processes often suffer from bacterial contamination. Results: This work reports the isolation and identification of a novel aerobic Geobacillus strain XT15 capable of producing both of these chemicals under elevated temperatures, thus reducing the risk of bacterial contamination. The optimum growth temperature was found to be between 45 and 55°C and the medium initial pH to be 8.0. In addition to glucose, galactose, mannitol, arabionose, and xylose were all acceptable substrates, enabling the potential use of cellulosic biomass as the feedstock. XT15 preferred organic nitrogen sources including corn steep liquor powder, a cheap by-product from corn wet-milling. At 55°C, 7.7 g/L of acetoin and 14.5 g/L of 2,3-butanediol could be obtained using corn steep liquor powder as a nitrogen source. Thirteen volatile products from the cultivation broth of XT15 were identified by gas chromatography-mass spectrometry. Acetoin, 2,3-butanediol, and their derivatives including a novel metabolite 2,3-dihydroxy-3-methylheptan-4-one, accounted for a total of about 96% of all the volatile products. In contrast, organic acids and other products were minor by-products. α-Acetolactate decarboxylase and acetoin:2,6-dichlorophenolindophenol oxidoreductase in XT15, the two key enzymes in acetoin metabolic pathway, were found to be both moderately thermophilic with the identical optimum temperature of 45°C. Conclusions: Geobacillus sp. XT15 is the first naturally occurring thermophile excreting acetoin and/or 2,3-butanediol. This work has demonstrated the attractive prospect of developing it as an industrial strain in the thermophilic fermentation of acetoin and 2,3-butanediol with improved anti-contamination performance. The novel metabolites and enzymes identified in XT15 also indicated its strong promise as a precious biological resource. Thermophilic fermentation also offers great prospect for improving its yields and efficiencies. This remains a core aim for future work. © 2012 Xiao et al.; licensee BioMed Central Ltd.


Wang S.,China University of Petroleum - East China | Ge X.,China University of Petroleum - East China | Xue J.,China University of Petroleum - East China | Fan H.,China University of Petroleum - East China | And 4 more authors.
Chemistry of Materials | Year: 2011

This work reports a mechanistic study of template-directed synthesis of silica nanomaterials utilizing self-assembled peptide nanotubes as scaffolds. An ultrashort amphiphilic peptide (I3K) underwent self-assembly in aqueous solution under ambient conditions to form long and uniform nanotubes. The assembled peptide nanotubes then were used as templates for the subsequent fabrication of silica nanotubes from tetraethoxysilane (TEOS), also under ambient conditions. In order to gain better insight into the mediation of peptide self-assembly on the formation of silica nanostructures, we have carefully investigated environmental influences including the concentrations of peptide and silica precursor, solution pH, and reaction time, with the full screening of the processes by TEM, SEM, 29Si MAS NMR, FTIR, and TG-MS. The results revealed that, while peptide nanotubes worked as scaffolds for the formation of tubular silica structures, the surfaces of these peptide nanotubes served as catalytic sites for both hydrolysis and condensation of TEOS, thereby working as templates for directing silica deposition. Because the electrostatic attraction of the negatively charged silica intermediates onto the positively charged surface of peptide nanotubes drove the templating process, tuning of such an interaction by adjusting the solution conditions (such as pH) affected silica morphological structures. Silica tended to deposit along the exterior surface of the template at undersaturation over weak acidic and neutral pH ranges, while silica intermediates overcame diffusion resistance and moved inside the tubular template over mild basic pH ranges, enabling silica precipitation along the interior surface. This work has thus demonstrated that the morphological nanostructures of silica can be controlled by adjusting the silicification conditions (such as peptide concentration and solution pH) under an ambient environment, thus avoiding harsh chemicals or extreme reaction conditions. © 2011 American Chemical Society.


Xu H.,China University of Petroleum - East China | Chen C.X.,China University of Petroleum - East China | Hu J.,China University of Petroleum - East China | Zhou P.,China University of Petroleum - East China | And 3 more authors.
Biomaterials | Year: 2013

Following our recent report of attractive antibacterial properties of a designed amphiphilic peptide, A9K, we have investigated its antitumor activities by examining the modes of its action against different mammalian cell types. The peptide strongly inhibited the growth of cancerous HeLa cells and human promyelocytic leukemia HL60 cells whilst remaining benign to the host cells, including Cos 7 cells, mouse fibroblast NIH3T3 cells and human red blood cells. Images from SEM and fluorescence microscopy showed that A9K penetrated HeLa cell membranes and disrupted membrane structures, a feature broadly similar to that observed from its bactericidal actions. Further interactions of A9K with inner cellular membranes caused mitochondrial dysfunction associated with the F-actin reorganization and the decreased transcription of bcl-2 and c-myc genes, resulting in HeLa cell apoptosis in a mitochondria-induced apoptosis pathway. Thus A9K has high selectivity against cancerous cells and kills them by dual modes of action: membrane disruption and cell apoptosis. In addition, the peptide does not induce non-specific immunological effects and is not degraded by proteases. These features are crucial for developing their applications in future research. © 2013 Elsevier Ltd.


Chen C.,China University of Petroleum - East China | Hu J.,China University of Petroleum - East China | Zeng P.,China University of Petroleum - East China | Pan F.,University of Manchester | And 3 more authors.
Biomaterials | Year: 2014

Development of functional biomaterials and drugs with good biocompatibility towards host cells but with high potency against cancer cells is a challenging endeavor. By drawing upon the advantageous features of natural antimicrobial peptides and α-helical proteins, we have designed a new class of short α-helical peptides G(IIKK)nI-NH2 (n=1-4) with different potency and high selectivity against cancer cells. We show that the peptides with n=3 and 4 kill cancer cells effectively whilst remaining benign to the host cells at their working concentrations, through mechanistic processes similar to their bactericidal effects. The high cell selectivity could stem from their preferential binding to the outer cell membranes containing negative charges and high fluidity. In addition to rapid membrane-permeabilizing capacities, the peptides can also induce the programmed cell death of cancer cells via both mitochondrial pathway and death receptor pathway, without inducing non-specific immunogenic responses. Importantly, these peptides can also inhibit tumor growth in a mouse xenograft model without eliciting side effects. Whilst this study reveals the clinical potential of these peptides as potent drugs and for other medical and healthcare applications, it also points to the significance of fundamental material research in the future development of highly selective peptide functional materials. © 2013 Elsevier Ltd.


Zhao D.,China University of Petroleum - East China | Zou T.,Zhejiang University of Technology
International Journal of Systems Science | Year: 2012

In this study, a new finite-time synchronised approach is developed for multiple mobile robots formation control based on terminal sliding mode control principle and system synchronisation theory. Associated stability analysis is presented to lay a foundation for analytical understanding in generic theoretical aspects and safe operation for real systems. An illustrative example of multiple mobile robots formation control is bench tested to validate the effectiveness of the proposed approach. © 2012 Taylor & Francis Group, LLC.


Xia Y.,China University of Petroleum - East China | He X.,China University of Petroleum - East China | Cao M.,China University of Petroleum - East China | Chen C.,China University of Petroleum - East China | And 3 more authors.
Biomacromolecules | Year: 2013

This work reports the formation of thermoresponsive poly(N- isopropylacrylamide-co-styrene) (PNIPAAmSt) microgel films and their use for cell growth and detachment via temperature stimuli. Thermoresponsive surface films can be conveniently produced by spin-coating or drop-coating of PNIPAAmSt microgel dispersions onto substrates such as glass coverslips, cell culture plates, and flasks, making this technique widely accessible. The thickness, stability, and reversibility of the PNIPAAmSt films coated on silicon wafers with respect to temperature switching were examined by spectroscopic ellipsometry (SE) and atomic force microscopy (AFM). The results unraveled the direct link between thermoreversibility and changes in film thickness and surface morphology, showing reversible hydration and dehydration. Under different coating conditions, well-packed microgel monolayers could be utilized for effective cell recovery and harvesting. Furthermore, cell adhesion and detachment processes were reversible and there was no sign of loss of cell viability during repeated surface attachment, growth, and detachment, showing a mild interaction between cells and thermoresponsive surface. More importantly, there was little deterioration of the packing of the thermoresponsive films or any major loss of microgel particles during reuse, indicating their robustness. These PNIPAAmSt microgel films thus open up a convenient interfacial platform for cell and cell sheet harvesting while avoiding the damage of enzymatic cleavage. © 2013 American Chemical Society.


Zhao D.,China University of Petroleum - East China | Ni W.,Nanchang University | Zhu Q.,China University of Petroleum - East China | Zhu Q.,University of the West of England
Neurocomputing | Year: 2014

A framework for neural networks (NN) based consensus control is proposed for multiple robotic manipulators systems (MRMS) under leader-follower communication topology. Two situations, that is, fixed and switching communication topologies, are studied by using adaptive and robust control principles, respectively. Radial basis function (RBF) NN enhances estimator and observer are developed to estimate system uncertainty and obtain the leader manipulator[U+05F3]s control torque online. By using the Lyapunov stability theory, an adaptive consensus control algorithm is designed to tune the weight of the RBF NN online, which can stabilize the consensus error to a small residual set. On this basis, a novel robust control algorithm is presented to eliminate the estimating errors caused by RBF NN, which can achieve asymptotical stability. The stability of the proposed approaches is analyzed by using Lyapunov methods. Finally numerical bench tests are conducted to validate the effectiveness of the proposed approach. © 2014 Elsevier B.V.


Tao K.,China University of Petroleum - East China | Wang J.,China University of Petroleum - East China | Li Y.,China University of Petroleum - East China | Xia D.,China University of Petroleum - East China | And 3 more authors.
Scientific Reports | Year: 2013

Although one dimensional (1D) Pt nanostructures with well-defined sizes and shapes have fascinating physiochemical properties, their preparation remains a great challenge. Here we report an easy and novel synthesis of 1D Pt nanostructures with controllable morphologies, through the combination of designer self-assembling I 3 K and phage-displayed P7A peptides. The nanofibrils formed via I 3 K self-assembly acted as template. Pt precursors ((PtCl 4) 2-and (PtCl 6) 2-) were immobilized by electrostatic interaction on the positively charged template surface and subsequent reduction led to the formation of 1D Pt nanostructures. P7A was applied to tune the continuity of the Pt nanostructures. Here, the electrostatic repulsion between the deprotonated C-terminal carboxyl groups of P7A molecules was demonstrated to play a key role. We finally showed that continuous and ordered 1D Pt morphology had a significantly improved electrochemical performance for the hydrogen and methanol electro-oxidation in comparison with either 1D discrete Pt nanoparticle assemblies or isolated Pt nanoparticles.


Rajagopalan S.,Center for Protein Engineering | Rajagopalan S.,University of Washington | Huang F.,Center for Protein Engineering | Huang F.,China University of Petroleum - East China | Fersht A.R.,Center for Protein Engineering
Nucleic Acids Research | Year: 2011

The state of oligomerization of the tumor suppressor p53 is an important factor in its various biological functions. It has a well-defined tetramerization domain, and the protein exists as monomers, dimers and tetramers in equilibrium. The dissociation constants between oligomeric forms are so low that they are at the limits of measurement by conventional methods in vitro. Here, we have used the high sensitivity of single-molecule methods to measure the equilibria and kinetics of oligomerization of full-length p53 and its isolated tetramerization domain, p53tet, at physiological temperature, pH and ionic strength using fluorescence correlation spectroscopy (FCS) in vitro. The dissociation constant at 37°C for tetramers dissociating into dimers for full-length p53 was 50 ± 7 nM, and the corresponding value for dimers into monomers was 0.55 ± 0.08 nM. The half-lives for the two processes were 20 and 50 min, respectively. The equivalent quantities for p53tet were 150 ± 10 nM, 1.0 ± 0.14 nM, 2.5 ± 0.4 min and 13 ± 2 min. The data suggest that unligated p53 in unstressed cells should be predominantly dimeric. Single-molecule FCS is a useful procedure for measuring dissociation equilibria, kinetics and aggregation at extreme sensitivity. © The Author(s) 2010. Published by Oxford University Press.


Patent
Sinopec, Shandong Seri Petrotech Development Co. and China University of Petroleum - East China | Date: 2014-07-10

The present disclosure discloses a device and a method for measuring gas chemical solvent absorption and desorption reaction heat. The device comprises an outer casing; an metal guard inner shell; a reactor; a pressure sensor; a thermal insulation material between the outer casing and the metal guard inner shell; guard electric heaters provided respectively in an upper portion and a lower portion of an outer periphery of the metal guard inner shell; a glass fiber thermal insulation layer between the inner metal guard shell and the reactor; temperature thermocouples provided in the glass fiber thermal insulation layer; a glass fiber board provided in a lower portion of an outer periphery of the reactor; main electric heaters between the glass fiber board and the reactor; a liquid inlet pipe and a gas discharge pipe; a temperature thermistor, a liquid discharge pipe; a data acquisition board; a computer; and a power supply.


Zhang W.,China University of Petroleum - East China | Hansen K.M.,Copenhagen University | Ingstrup M.,No Magic
Knowledge-Based Systems | Year: 2014

Self-management capabilities for pervasive computing systems are critical in improving dependability, usability, and autonomicity. However, realizing self-management is not an easy task due to complexities of implementing autonomous behaviors. It has been recognized that a single autonomicity handling mechanism is not sufficient to realize comprehensive self-management capabilities when different technologies are involved. Therefore, we propose a hybrid approach, the 'LinkSmart Three Layered architectural (LinkSmart-3L) style', in which different architecture styles are incorporated. The LinkSmart-3L style enables self-management at an architectural level. In our approach, semantic web technologies are used to achieve comprehensive context-awareness and extensibility of self-management capabilities, genetic algorithms are used to achieve configuration optimizations, and a planner is used to compute planning procedures on how to arrive at an optimum system configuration based on current architectural structure of the underlying system using an architectural query language. These technologies are integrated seamlessly based on the service oriented computing (SoC) paradigm. We have extensively evaluated both runtime and development time qualities of our implementation of the style. These evaluations can serve as guidelines for evaluating other middleware systems. We conclude that our approach is usable and effective in achieving these quality attributes. © 2014 Elsevier B.V. All rights reserved.


Tao B.,China University of Petroleum - East China | Zhang Y.,China University of Petroleum - East China | Han D.,CAS Qingdao Institute of Bioenergy and Bioprocess Technology | Li Y.,China University of Petroleum - East China | Yan Z.,China University of Petroleum - East China
Journal of Materials Chemistry A | Year: 2014

In this work, polycrystalline indium oxyhydroxide (InOOH) porous spheres were synthesized through a mixed solvothermal method in the presence of sodium citrate (Na3cit) as a structure-directing agent. Corundum-type In2O3 porous spheres were obtained via annealing InOOH precursors at 400 °C for 2 hours. The samples were characterized by means of X-ray powder diffraction, thermogravimetric analysis, UV-Vis diffuse reflectance spectroscopy, scanning electron microscopy, transmission electron microscopy, and high-resolution transmission electron microscopy. The Ostwald ripening process was proposed as the mechanism for the formation of porous spheres. Photocatalytic activity of the porous h-In2O3 spheres was evaluated by degrading rhodamine B (RhB) under ultraviolet (UV) irradiation. The results indicated that the porous h-In2O3 spheres possessed superior photocatalytic activity to their counterparts, and could restore 95% of the initial photocatalytic activity after 5 reaction runs. © 2014 the Partner Organisations.


Lin L.,Tianjin Polytechnic University | Zhang Y.,Tianjin Polytechnic University | Zhang H.,China University of Petroleum - East China | Lu F.,China University of Petroleum - East China
Journal of Colloid and Interface Science | Year: 2011

Typical ion-exchanged modified Y zeolites (AgY and CeY) were prepared for sulfur removal. The adsorption and desorption behavior of typical sulfur and hydrocarbon molecules in various Y zeolites has been investigated by the adsorption breakthrough and on site solvent washing experiments, as well as computer simulation. Breakthrough experiments showed that the adsorption capacity for thiophenic sulfur increased for the studied adsorbents as follows: CeY > AgY > NaY. The higher initial sulfur concentration accelerated the appearance of breakthrough, and the outlet sulfur concentration, in all cases, cannot reach the corresponding initial sulfur level. The concentration profile of washing solvent during desorption process showed that most of the sulfur compounds could be recovered at initial desorption stage. The desorption rates of typical Y zeolites follow the order: NaY > AgY > CeY, which is the reverse as that found in adsorption capacity. The distinct adsorption and desorption behavior of CeY, AgY, and NaY zeolites was markedly related with their various binding force (S-M coordination, π-complexation, and Van der Waals force) with sulfur compounds. The adsorption isotherms and density distribution snapshots study by computer simulation confirmed the preferential adsorption of thiophenic sulfur. © 2011 Elsevier Inc.


Jiang W.,China University of Petroleum - East China | Jiang W.,Korea Atomic Energy Research Institute | Zhang Y.,China University of Petroleum - East China | Woo W.,Korea Atomic Energy Research Institute
International Journal of Pressure Vessels and Piping | Year: 2012

316L type stainless steel is widely used in chemical industries due to its excellent resistance to corrosion. But the welding residual stresses have a great effect on stress corrosion cracking. This paper used finite element method to study the effect of heat sink on residual stress. The effects of contact length and the average heat transfer coefficient on residual stress have been investigated. It is found that the heat sink technology can decrease the residual stress greatly. Compared to the model without heat sink, 20% of the peak longitudinal stress has been reduced. The heat sink decreases the dwell time during cooling from 850 °C to 400 °C, which is helpful to decrease the risk of sensitization of 316L stainless steel. With the contact length increase, the transverse stress is decreased. Further increase of the contact length has no positive effect on reducing the longitudinal stress. With the average heat transfer coefficient increase, the transverse stress is decreased greatly while the longitudinal stress decreases slightly, and some tensile residual stresses have been changed to compressive in some zone. © 2012 Elsevier Ltd.


Hu S.-L.J.,University of Rhode Island | Bao X.,China University of Petroleum - East China | Li H.,Ocean University of China
Science China: Physics, Mechanics and Astronomy | Year: 2012

Modal identification involves estimating the modal parameters, such as modal frequencies, damping ratios, and mode shapes, of a structural system from measured data. Under the condition that noisy impulse response signals associated with multiple input and output locations have been measured, the primary objective of this study is to apply the local or global noise removal technique for improving the modal identification based on the polyreference time domain (PTD) method. While the traditional PTD method improves modal parameter estimation by over-specifying the computational model order to absorb noise, this paper proposes an approach using the actual system order as the computational model order and rejecting much noise prior to performing modal parameter estimation algorithms. Two noise removal approaches are investigated: a "local" approach which removes noise from one signal at a time, and a "global" approach which removes the noise of multiple measured signals simultaneously. The numerical investigation in this article is based on experimental measurements from two test setups: a cantilever beam with 3 inputs and 10 outputs, and a hanged plate with 4 inputs and 32 outputs. This paper demonstrates that the proposed noise-rejection method outperforms the traditional noise-absorption PTD method in several crucial aspects. © Science China Press and Springer-Verlag Berlin Heidelberg 2012.


Zhang K.,Beijing University of Technology | Zhang K.,China University of Petroleum - East China | Liu Z.,Beijing University of Technology | Li Y.,Beijing University of Technology | And 3 more authors.
Applied Thermal Engineering | Year: 2014

Absorption heat transformer (AHT) and flash evaporator (FE) are used to reduce the heat consumption of CO2 capture processes and an AHT-FE-aided capture system is proposed. Analyses are carried out to verify the effectiveness in reducing heat consumption. Compared with the base CO 2 capture system of 3000 t/d CO2 capture capacity from a 660MW coal- fired power unit, the AHT-FE-aided capture system reduces the heat consumption from 3.873 GJ/tCO2 to 3.772 GJ/tCO2, and the corresponding energy saving is 2.62%. The economic analysis shows that the annual profit would be 2.94 million RMB Yuan. The payback period of the AHT-FE-aided capture system is approximately 2.4 years. Therefore, the AHT-FE-aided capture system is both economically and technically feasible for improving the CO2 capture energy performance. © 2013 Elsevier Ltd. All rights reserved.


Zhang D.,University of Minnesota | Zhang D.,China University of Petroleum - East China | Cui T.,University of Minnesota
Sensors and Actuators, A: Physical | Year: 2012

This paper presents layer-by-layer (LbL) self-assembly of single-walled carbon nanotube (SWNT)/polymer membranes with a well-dispersed wide-range tunable volume fraction of functionalized SWNTs. The surface morphology of the SWNT/polymer membranes shows a high strength, dense and random network structures. The quartz crystal microbalance (QCM) characterization illustrates that the deposition thickness and the SWNT loading fraction in SWNT nanocomposites can be controlled in a large range based on LbL sequential deposition process. The Young's modulus of the self-assembled SWNT/polymer composite membranes is characterized by a combinative approach of piezoelectric excitation and laser vibrometer measurement. The Young's modulus of SWNT/polymer nanocomposites is tunable from hundreds to tens of GPa, as a function of the SWNT volume fraction. Such significant enhancement of LbL self-assembled SWNTs offers a way in which the embedded SWNTs can realize the true potential to strengthen SWNT/polymer nanocomposites. Conventional mixture models such as rule-of-mixture model and Halpin-Tsai model fail to explain the structure-property regime in nanoscale at a high SWNT fraction ratio. This observed tunability can serve as a benchmark to tailor the design of nanocomposite thin films for potential applications to MEMS and NEMS devices. © 2012 Elsevier B.V.


Liu J.,China University of Petroleum - East China | Xia R.,Wuhan University | Zhou X.,PLA Fourth Military Medical University
Science China: Physics, Mechanics and Astronomy | Year: 2012

In this study, we considered the wetting phenomenon on a general substrate from a new viewpoint of continuum mechanics. The analyses first show how the Wenzel and the Cassie models deviate the practical results in some special substrates, and then elucidate the mechanism of the triple contact line (TCL) moving. Based upon variational theory of the total free functional dealing with the movable boundary condition, we show that the macroscopic contact angle (MCA) expression is the corresponding transversality condition. It manifests that the MCA depends only on the chemical and geometric property at the TCL, and is not affected by the gravity of the droplet and the contact area beneath the liquid. Our continuum model also shows the exploration of the pinning effect on a sharp wedge or the interface between two different phases. This investigation will help designing super-hydrophobic materials for novel micro-fluidic devices. © Science China Press and Springer-Verlag Berlin Heidelberg 2012.


Yang G.,Xi'an Jiaotong University | Yang G.,China University of Petroleum - East China | Yan Z.,China University of Petroleum - East China | Xiao T.,University of Oxford
Applied Surface Science | Year: 2012

In this work, a low-temperature solvothermal method has been developed to synthesize visible-light-responsive S-doped TiO 2 nanocrystal photocatalyst, using thiourea as the sulfur source to enhance sulfur incorporation into TiO 2 lattice. The effects of different S:Ti molar ratio on the crystal structure, chemical composition, surface property and catalytic performance have been studied. X-ray photoelectron spectroscopy (XPS) analysis and Fourier transform infrared (FT-IR) spectra displayed that the TiO 2 was modified by the S element incorporated into the TiO 2 network to form TiOS bond, which therefore led to the formation of intermediate energy level just above the O 2p valance band, and caused the absorption edge of TiO 2 to shift into the visible light region up to 500 nm. Characterization results show that the pure nanocrystal anatase structure, with both the degree of S doping and oxygen vacancies makes contribution to the exceptional photocatalytic activity of TONS in visible-light degradation of Methylene Blue (MB) and phenol molecules. © 2011 Elsevier B.V. All rights reserved.


Wang D.,Xi'an Jiaotong University | Liang F.-C.,China University of Petroleum - East China | Peng Z.-Q.,Xi'an Jiaotong University | Wang Y.-G.,Xi'an Jiaotong University | Lin Z.-H.,Xi'an Jiaotong University
International Journal of Multiphase Flow | Year: 2012

This paper presents a gas-liquid two-phase flow measurement method by sampling a very small fraction (5%) of the total flow. Unlike the conventional sample technique, the sample is drawn from the whole cross section instead of a local place. During the sampling, a discrete total two-phase flow sample is extracted by a sampling device and separated into single phase flows with a much small separator, and they are subsequently metered by two single phase flowmeters respectively, after that, these two streams will return to the main stream. The sample is able to represent the total flow and accurately determine the total flowrates. Because the sample is only a very small fraction of the total flow, the separator can be greatly reduced in size, which can be as small as a single phase flowmeter. At the same time, considering the flow has become two single phase streams after the separation, the measurement reliability is significantly improved. Experiments were conducted in an air-water two phase flow test loop. The inner pipe diameter of the test loop was 50. mm, and the superficial gas velocity varied from 1.5. m/s to 22. m/s, the liquid superficial velocity was in the range of 0.02-0.45. m/s. The flow pattern occurring during the experiments included stratified flow, stratified wave, slug flow and annular flow. The experimental results showed that this sampling method was feasible of measurin. g the two phase flowrates, and independent of flow pattern, the error of flowrates measurements was less than ±5%. © 2011 Elsevier Ltd.


Yang G.,China University of Technology | Wang T.,China University of Technology | Yang B.,China University of Technology | Yan Z.,China University of Petroleum - East China | And 2 more authors.
Applied Surface Science | Year: 2013

A visible light active F-N co-doped TiO2 photocatalysts with varying molar ratio of TiO2/NH4F were successfully prepared using an effective yet simple ethanol-water solvothermal method. The photocatalytic activities of the prepared catalysts were tested for the degradation of methylene blue (MB) under visible light irradiation. Superior photocatalytic activity relative to that of undoped TiO2 was observed on the F-N co-doped catalyst with TiO2: NH4F molar ratio of 1.0. Based on the characterization results including FT-IR, XRD, Raman analysis, UV-vis DRS, XPS and ESR, the F and N dopants were effectively incorporated into the anatase TiO2 lattice, and resulted in a decrease in the energy gap, especially for the TONF-2 sample, which shows two optical absorption edge at 2.32 eV and 2.99 eV, respectively. The ESR data showed that the presence of fluorine and nitrogen in the lattice induces the formation of reduced Ti3+ centers and oxygen vacancies. In addition, the surface O2 •-radicals were also detected by ESR analysis, which together with • OH radicals are responsible for the MB solution decoloration under visible light. According to the experimental results, it is believed that the enhanced visible light activity arises from thesynergistic effect of F-N co-doping, the presence of Ti3+ centers and oxygen vacancies, and thus possible mechanism for both visible light absorption and charge separation were proposed. © 2013 Elsevier B.V. All rights reserved.


Jiang W.,China University of Petroleum - East China | Luo Y.,China University of Petroleum - East China | Zhang G.,Suzhou Nuclear Power Research Institute | Woo W.,Korea Atomic Energy Research Institute | Tu S.T.,East China University of Science and Technology
Materials and Design | Year: 2013

This paper presents an experimental study of multiple repair welds in a stainless steel clad plate. Four weld samples with one, two, three and four repairs in the same area were prepared, respectively, to determine the changes in microstructure, residual stress and micro hardness. Neutron diffraction measurement was used to determine the weld residual stress. The results show that the repair weld contains nine zones with different microstructures. Around weld-base metal interface, a diffusion layer is formed because of the diffusion of C, Cr, Ni and Fe elements. The diffusion layer, which contains martensite with larger hardness than the adjacent metals, should be removed completely before re-repair. Around the weld-clad metal interface, short ferrite is generated along the fusion zone. As the repair number increases, the fusion zone becomes thicker, and the content of short ferrite also increases, which leads to some voids in the third and fourth repair welds. In the fusion zone of the sample with four repairs, massive ferrite is generated because more Cr element is diffused to the fusion zone. Residual stress increases gradually from the weld center and reaches the maximum at heat affected zone (HAZ) and then decreases far away. The residual stress in the sample with four repairs decreases because the hardness is decreased. Based on the comprehensive considerations of microstructure, residual stress and hardness, it proposes that the clad plate cannot be repaired more than 2 times. © 2013 Elsevier Ltd.


Lv X.,China University of Petroleum - East China | Lv X.,CAS Qingdao Institute of Bioenergy and Bioprocess Technology | Li L.,China University of Petroleum - East China | Tang S.,CAS Qingdao Institute of Bioenergy and Bioprocess Technology | And 3 more authors.
Chemical Communications | Year: 2014

A metal-organic framework with chiral pores and decorated imidazole and methyl groups was constructed. Upon activation, this MOF undergoes a pore contraction and shows very high selectivity for CO2/N2 and CO2/CH4, indicating a synergistic effect of dynamic pores and functional groups. © the Partner Organisations 2014.


Liu J.,China University of Petroleum - East China | Mei Y.,China University of Petroleum - East China | Xia R.,Wuhan University
Langmuir | Year: 2011

The classical Wenzel and Cassie models fail to give a physical explanation of such phenomenon as the macroscopic contact angle actually being equal to the Young's contact angle if there is a spot (surface defect) inside the droplet. Here, we derive the expression of the macroscopic contact angle for this special substrate in use of the principle of least potential energy, and our analytical results are in good agreement with the experimental data. Our findings also suggest that it is the triple contact line (TCL) rather than the contact area that dominates the contact angle. Therefore a new model based upon the TCL pinning is developed to explain the different wetting properties of the Wenzel and Cassie models for hydrophilic and hydrophobic cases. Moreover, the new model predicts the macroscopic contact angle in a broader range accurately, which is consistent with the existing experimental findings. This study revisits the fundamentals of wetting on rough substrates. The new model derived will help to design better superhydrophobic materials and provide the prediction required to engineer novel microfluidic devices. © 2010 American Chemical Society.


Sun L.,China University of Petroleum - East China | Chang N.,Colorstone Leakage Supervisory Technology Company
Journal of Loss Prevention in the Process Industries | Year: 2014

Leaks in pipelines can cause major incidents resulting in both human injuries and financial losses. Among the considerable leak detection and location methods, the Negative Pressure Wave (NPW) based method has been widely used in locating leaks in liquid pipelines. The NPW based method only monitors the pressure changes at two ends of a pipeline. But the pressure is apt to be fixed by the end equipment and the change of it induced by a small or slow leakage is too small to be detected, which limit the application of the NPW based method in these situations. This paper presents a novel leak location method based on integrated signal, which is a combination of the pressure and flow rate signals. The representation of the integrated signal is derived from the transient analysis of the leakage. For the change of the integrated signal induced by a leakage is larger than the pressure change and it is also unaffected by the end equipment, the proposed method can be used to detect and locate small or slow leakage in a pipeline and can also be used in pipelines which end pressures are fixed by some kinds of equipment. The validation of the proposed method also confirms its advantages. © 2014 Elsevier Ltd.


Liu J.-L.,China University of Petroleum - East China | Xia R.,Wuhan University
Acta Mechanica Sinica/Lixue Xuebao | Year: 2013

In this study, we developed a general method to analytically tackle a kind of movable boundary problem from the viewpoint of energy variation. Having grouped the adhesion of a micro-beam, droplet and carbon nanotube (CNT) ring on a substrate into one framework, we used the developed line of reasoning to investigate the adhesion behaviors of these systems. Based upon the derived governing equations and transversality conditions, explicit solutions involving the critical parameters and morphologies for the three systems are successfully obtained, and then the parameter analogies and common characteristics of them are thoroughly investigated. The presented method has been verified via the concept of energy release rate in fracture mechanics. Our analyses provide a new approach for exploring the mechanism of different systems with similarities as well as for understanding the unity of nature. The analysis results may be beneficial for the design of nano-structured materials, and hold potential for enhancing their mechanical, chemical, optical and electronic properties. © 2012 The Chinese Society of Theoretical and Applied Mechanics; Institute of Mechanics, Chinese Academy of Sciences and Springer-Verlag Berlin Heidelberg.


Jiang W.,Korea Atomic Energy Research Institute | Jiang W.,China University of Petroleum - East China | Woo W.,Korea Atomic Energy Research Institute | An G.-B.,POSCO | Park J.-U.,Chosun University
Materials and Design | Year: 2013

Temperature and residual stresses were thermo-mechanically modeled in a 1000. mm long welding plate based on the simplified variable length heat source. The stress relaxations were simulated as a function of the plate length after cutting the initial weld specimen by using an element removal method and treating the prior stress field as the next cutting origins. Meanwhile residual stresses were sequentially measured in a weld with the length of 300. mm and cut welds having 150, 10. mm lengths for comparison using neutron diffraction. Residual stresses from both the modeling and experimental results exponentially decrease from about 370 to 0. MPa as the total weld plate length decreases from 300. mm to 10. mm. Such stress relaxation by the cutting length is correlated to the exponential decrease law based on the St. Venant's principle. It suggests that the minimum cutting length about 300. mm is necessary to prevent the stress relaxation less than 3% of the initial stresses in a high-strength steel weld. © 2013 Elsevier Ltd.


Li L.,China University of Petroleum - East China | Bell J.G.,Northumbria University | Tang S.,CAS Qingdao Institute of Bioenergy and Bioprocess Technology | Lv X.,CAS Qingdao Institute of Bioenergy and Bioprocess Technology | And 5 more authors.
Chemistry of Materials | Year: 2014

A novel nanoporous metal-organic framework NPC-4 with excellent thermal stability was assembled from 2,3,5,6-tetramethylbenzene-1,4-diisophthalate (TMBDI) and the paddle-wheel secondary building unit (Cu2(COO) 4). The porous structure comprises a single type of nanoscale cage (16 Å diameter) interconnected by windows (5.2 × 6.3 Å), which give a high pore volume. CH4 (195-290 K), CO2 (198-303 K), N2 (77 K), and H2 (77 K) adsorption isotherms were studied for pressures up to 20 bar. NPC-4 exhibits excellent methane and carbon dioxide storage capacities on a volume basis with very high adsorbate densities, under ambient conditions. Isobars were investigated to establish the relationship for adsorption capacities over a range of storage temperatures. The isosteric enthalpies of adsorption for both CH4 and CO2 adsorption did not vary significantly with amount adsorbed and were ∼15 and ∼25 kJ mol-1, respectively. The adsorption/desorption kinetics for CH4 and CO2 were investigated and activation energies, enthalpies of activation, and diffusion parameters determined using various kinetic models. The activation energies for adsorption obtained over a range of uptakes from the stretched exponential kinetic model were 5.1-6.3 kJ mol -1 (2-13.5 mmol g-1) for CO2 and 2.7-5.6 kJ mol-1 (2-9 mmol g-1) for CH4. The activation energies for surface barriers and diffusion along pores for both CH4 and CO2 adsorption obtained from a combined barrier resistance diffusion model did not vary markedly with amount adsorbed and were <9 kJ mol-1. Comparison of kinetic and thermodynamic parameters for CH 4 and CO2 indicates that a surface barrier is rate determining at high uptakes, while intraparticle diffusion involving diffusion through pores, consisting of narrow windows interconnecting with nanocages, being rate determining at very low uptakes. The faster CH4 intraparticle adsorption kinetics compared with CO2 for NPC-4 was attributed to faster surface diffusion due to the lower isosteric enthalpy of adsorption for CH4. © 2014 American Chemical Society.


Yang G.,Xi'an Jiaotong University | Yang G.,China University of Petroleum - East China | Yang G.,University of Oxford | Yan Z.,China University of Petroleum - East China | Xiao T.,University of Oxford
Applied Surface Science | Year: 2012

In this study, SnO 2/ZnO/TiO 2 composite photocatalysts were successfully synthesized using sol-gel and solid-state methods. The as-prepared samples were characterized for the phase structure, optical absorption, thermal stability and surface property using X-ray diffraction (XRD), Raman spectroscopy, UV-vis diffuse reflectance spectra (DRS), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The photocatalytic activity was tested with photodecomposition of Methyl Orange under both visible and UV light irradiations. The results indicated that the SnO 2/ZnO/TiO 2 composite materials have an apparent visible light absorption, combining TiO 2 with SnO 2 and ZnO could promote the TiO 2 phase transition from anatase to rutile. The SnO 2/ZnO/TiO 2 heterojunctions with the highest performance was the one prepared using Sn(Zn)/Ti molar ratio of 0.05. It was found that the enhanced photocatalytic activity could be attributed to the increased separation of the charge carriers, which therefore depress the charge pair recombination and prolonged the electron lifetime in the composite structure, and a large number of electrons could take part in the photoreaction. Based on the results of the present study, a tentative mechanism for the enhanced photocatalysis of the SnO 2/ZnO/TiO 2 composite catalyst has been proposed. © 2012 Elsevier B.V. All rights reserved.


Xu G.,CAS Qingdao Institute of Bioenergy and Bioprocess Technology | Li Q.,CAS Qingdao Institute of Bioenergy and Bioprocess Technology | Li Q.,China University of Petroleum - East China | Feng J.,China University of Petroleum - East China | And 5 more authors.
ChemSusChem | Year: 2014

The direct α-alkylation of ketones with alcohols has emerged as a new green protocol to construct C-C bonds with H2O as the sole byproduct. In this work, a very simple and convenient Pd/C catalytic system for the direct a-alkylation of ketones with primary alcohols in pure water is developed. Based on this catalytic system, aqueous mixtures of dilute acetone, 1-butanol, and ethanol (mimicking ABE fermentation products) can be directly transformed into C5-C11 or longer-chain ketones and alcohols, which are precursors to fuels.


Li M.,China University of Petroleum - East China | Fei S.-M.,Capital Normal University | Fei S.-M.,Max Planck Institute for Mathematics in the Sciences
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2010

We study the entanglement of formation for arbitrary-dimensional bipartite mixed unknown states. Experimentally measurable lower and upper bounds for entanglement of formation are derived. © 2010 The American Physical Society.


Liu J.L.,China University of Petroleum - East China | Mei Y.,South China University of Technology | Xia R.,Wuhan University | Zhu W.L.,Wuhan University
Physica E: Low-Dimensional Systems and Nanostructures | Year: 2012

Nanowires are widely used as building blocks of micro/nano devices, such as micro-sensors, probes, transistors and actuators in micro/nano-electro- mechanical systems (M/NEMS) and biotechnology. In this study, we investigated the large deformation behavior of a nanowire in consideration of its surface effects (surface elasticity and residual surface stress). For nanowires of large displacements with different boundary conditions, we established the governing equation set in combination with the residual surface stress and surface elasticity. Then a computer program of shooting method by using the commercial software MathCAD was developed to solve the boundary value problem numerically. Furthermore, the influences of surface effects on the large and infinitesimal deformation of the nanowires were quantitatively compared. These findings are beneficial to understanding the mechanism of the surface effects, and can also provide some inspirations to characterize the mechanical properties of nano-materials, and engineer new micro/nano-scaled devices. © 2012 Elsevier B.V.


Li M.,China University of Petroleum - East China | Fei S.-M.,Capital Normal University | Fei S.-M.,Max Planck Institute for Mathematics in the Sciences
Physical Review Letters | Year: 2010

We present a set of Bell inequalities which are sufficient and necessary for separability of general pure multipartite quantum states in arbitrary dimensions. The relations between Bell inequalities and distillability are also studied. We show that any quantum states that violate one of these Bell inequalities are distillable. © 2010 The American Physical Society.


Jian L.,China University of Petroleum - East China | Jian L.,Dalian University of Technology | Gao C.,Zhejiang University | Xia Z.,Western Kentucky University
IEEE Transactions on Automation Science and Engineering | Year: 2012

This paper constructs the framework of the reproducing kernel Hilbert space for multiple kernel learning, which provides clear insights into the reason that multiple kernel support vector machines (SVM) outperform single kernel SVM. These results can serve as a fundamental guide to account for the superiority of multiple kernel to single kernel learning. Subsequently, the constructed multiple kernel learning algorithms are applied to model a nonlinear blast furnace system only based on its input-output signals. The experimental results not only confirm the superiority of multiple kernel learning algorithms, but also indicate that multiple kernel SVM is a kind of highly competitive data-driven modeling method for the blast furnace system and can provide reliable indication for blast furnace operators to take control actions. © 2012 IEEE.


Chang C.-Y.,National Cheng Kung University | Chang S.-J.,National Cheng Kung University | Liu C.H.,Nan Jeon University of Science and Technology | Li S.,China University of Petroleum - East China | Lin T.K.,Epistar Corporation
IEEE Photonics Technology Letters | Year: 2012

In this letter, we report the fabrication of GaN-based light-emitting diodes (LEDs) with double strain releasing multiquantum wells and Si delta-doping (Si-DD) layers. We find that Si-DD can enhance current spreading in the in-plane direction and also suppress dislocation in the epitaxial layers. By inserting the Si-DD layers, we find that we can achieve a smaller forward voltage. We also find that we can significantly increase the reverse breakdown voltage from 35 to 125 V by introducing Si-DD layers. Furthermore, we find that the output power of the LED with Si-DD is more than 10% larger than that of the LED without Si-DD. © 2012 IEEE.


Li M.,China University of Petroleum - East China | Li M.,Max Planck Institute for Mathematics in the Sciences | Wang J.,China University of Petroleum - East China | Wang J.,Capital Normal University | And 3 more authors.
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2014

We present separability criteria for both bipartite and multipartite quantum states. These criteria include the criteria based on the correlation matrix and its generalized form as special cases. We show by detailed examples that our criteria are more powerful than the positive partial transposition criterion, the realignment criterion, and the criteria based on the correlation matrices. © 2014 American Physical Society.


Sun L.-Y.,China University of Petroleum - East China | Chang X.-W.,China University of Petroleum - East China | Qi C.-X.,Shandong Qilu Petrochemical Engineering Co. | Li Q.-S.,China University of Petroleum - East China
Separation Science and Technology | Year: 2011

In this article, the design and optimization procedures of a dividing-wall column for heterogeneous azeotropic distillation (DWC-A) using cyclohexane as an entrainer for ethanol dehydration are investigated. The proposed procedures can detect the optimal values of the design variables and thereby guarantee the minimum energy requirements, which is related to the minimum CO2 emissions and the lowest total annual cost (TAC). Since ethanol and water form an azeotrope under atmosphere pressure, a conventional heterogeneous azeotropic distillation sequence (CHADS), including an azeotropic column and a recovery column, is usually used to perform the ethanol dehydration process. However, due to high energy requirements and equipment investments of CHADS, the TAC is at a relatively high level. DWC-A can be used to eliminate the condenser of the second column and decrease the degree of back-mixing. Both CHADS and DWC-A are simulated with Aspen Plus®, and the results show that DWC-A has an energy saving of 42.17% and the TAC reduction of 35.18% along with higher thermodynamic efficiency and reduction in greenhouse gas emissions. © Taylor & Francis Group, LLC.


Wang Y.,CAS Guangzhou Institute of Geochemistry | Zhang F.,CAS Guangzhou Institute of Geochemistry | Fan W.,CAS Guangzhou Institute of Geochemistry | Zhang G.,Northwest University, China | And 4 more authors.
Tectonics | Year: 2010

Zircon U-Pb geochronological data on over 900 zircon grains for Cambrian to Silurian sandstone samples from the South China Block constrain the pre-Devonian tectonic setting of, and the interrelationships between, the constituent Cathaysia and Yangtze blocks. Zircons range in age from 3335 to 465 Ma. Analyses from the Cathaysia sandstone samples yield major age clusters at ∼2560, ∼1850, ∼1000, and 890-760 Ma. Zircons from the eastern and central Yangtze sandstone samples show a similar age distribution with clusters at ∼2550, ∼1860, ∼1100, and ∼860-780 Ma. A minor peak at around 1450 Ma is also observed in the Cathaysia and central Yangtze age spectra, and a peak at ∼490 Ma represents magmatic zircons from Middle Ordovician sandstone in the eastern Yangtze and Cathaysia blocks. The Cambrian and Ordovician strata show a transition from a carbonate-dominated succession in the central Yangtze Block, to an interstratified carbonate-siliciclastic succession in the eastern Yangtze Block, to a neritic siliciclastic succession in the Cathaysia Block. Paleocurrent data across this succession consistently indicate directions toward the W-NNW, from the Cathaysia Block to the Yangtze Block. Our data, together with other geological constraints, suggest that the Cathaysia Block constitutes a fragment on the northern margin of east Gondwana and both Cathaysia and east Gondwana constituted the source for the analyzed early Paleozoic samples. The similar age spectra for the Cambrian to Silurian sandstone samples from the Yangtze and Cathaysia blocks argue against the independent development and spatial separation of these blocks in the early Paleozoic but rather suggest that the sandstone units accumulated in an intracontinental basin that spanned both blocks. Subsequent basin inversion and Kwangsian orogenesis possibly at 400-430 Ma also occurred in an intracontinental setting probably in response to the interaction of the South China Block with the Australian-Indian margin of east Gondwana. Copyright 2010 by the American Geophysical Union.


Li M.,China University of Petroleum - East China | Fei S.-M.,Capital Normal University | Fei S.-M.,Max Planck Institute for Mathematics in the Sciences
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2012

Entanglement of formation is an important measure of quantum entanglement. We present an experimental way to measure the entanglement of formation for arbitrary dimensional pure states. The measurement only evolves local quantum mechanical observables. © 2012 American Physical Society.


Li M.,China University of Petroleum - East China | Fei S.-M.,Capital Normal University | Fei S.-M.,Max Planck Institute for Mathematics in the Sciences
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2012

We present a set of Bell inequalities for multiqubit quantum systems. These Bell inequalities are shown to be able to detect multiqubit entanglement better than previous Bell inequalities such as Werner-Wolf-Zukowski-Brukner ones. Computable formulas are presented for calculating the maximal violations of these Bell inequalities for any multiqubit states. © 2012 American Physical Society.


Yang G.,China University of Technology | Yang G.,University of Oxford | Yan Z.,China University of Petroleum - East China | Xiao T.,University of Oxford | Yang B.,China University of Technology
Journal of Alloys and Compounds | Year: 2013

In this study, a series of alkalis doped TiO2 (alkalis = Na, K and Rb) photocatalysts were synthesized at low temperature using solvothermal method. Various characterization techniques, such as X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectra (FT-IR), Scanning electron microscopy (SEM), N2 adsorption and UV-vis diffuse reflectance spectra (DRS) spectrophotometer, were employed to investigate the influence of alkali ions on the crystalline phase, grain size, optical absorption and surface functional groups of alkali ion doped TiO2 catalysts. The XRD results indicate that the alkali ion doping restrains the growth of the TiO2 particle size, resulting in a high specific surface area for the alkali ion doped TiO2 materials. The photocatalytic performances of these materials were evaluated using the degradation of methyl orange (10 mg/L) as the model reaction under UV light irradiation. It was found that the photocatalytic activity of the alkali ion doped TiO2 catalysts can be enhanced significantly with the samples doped by 3 wt% alkali ion, which is due to the synergistic effect of pure anatase TiO2 phase structure, small crystallite size, higher surface basic sites and fast electronic transfer rate.


Yang G.,China University of Technology | Yang B.,China University of Technology | Xiao T.,University of Oxford | Yan Z.,China University of Petroleum - East China
Applied Surface Science | Year: 2013

One-step solvothermal method was developed for the synthesis of hierarchically porous nanostructured CdS/TiO2 heterojunction materials, which exhibited enhanced visible-light-driven photocatalytic activity in decomposing both methyl orange (MO) and rhodamine B (RhB) in water. The photocatalyst with the highest performance was the one prepared using the Ti:Cd molar ratio of 1:1. Based on the characterization results of XRD, XPS, FT-IR, SEM, HRTEM, UV-vis DRS and N2 adsorption-desorption, the influence of coupling TiO2 with CdS on the crystal phase, band structure, surface element composition, morphology, optical absorption and surface area of the as-prepared samples are investigated. The results showed that the CdS/TiO 2 heterojunction catalysts possessed well-defined hierarchically porous structure composed of anatase TiO2 and hexagonal CdS nanoparticle with average grain size of 4-6 nm. Their enhanced catalytic activity can be attributed to the synergistic effect of crystal compositions, porous architectures, electronic band structure, large specific surface area and strong visible light absorption. © 2013 Elsevier B.V. All rights reserved.


Gu Y.-Y.,China University of Petroleum - East China | Yeung A.T.,University of Hong Kong
Geotechnical Special Publication | Year: 2012

Citric acid industrial wastewater (CAIW) is a waste by-product generated by the manufacturing process of citric acid. Effective and economical treatment and disposal of the wastewater is an environmental challenge. A research program was launched to investigate the feasibility of using CAIW as an enhancement agent for electrochemical remediation of Cd-contaminated clay of high acid/base buffer capacity, so as to lower the cost of electrochemical remediation and to put a waste byproduct into productive use. The research program included batch experiments to quantify various soil-Cd-CAIW interactions and laboratory bench-scale electrochemical remediation experiments. The results indicate CAIW is a promising replacement for other more expensive synthetic chelating agents in the enhancement of electrochemical remediation. Details of the study are presented in the paper. © 2012 American Society of Civil Engineers.


Ren B.,China University of Petroleum - East China | Ren B.,University of Texas at Austin | Ren S.,China University of Petroleum - East China | Zhang L.,China University of Petroleum - East China | And 2 more authors.
Energy | Year: 2016

Jilin Oilfield is conducting a large-scale demonstration project on CO2 EOR (enhanced oil recovery) and storage in China. CO2 separated from a nearby natural gas reservoir (15-30 mol% CO2) is injected into the northern part of H59 oil block with permeability and porosity of 3.5 mD and 12.7%, respectively. After about six years of operation, nearly 0.26 million tons of CO2 (0.32 HCPV (hydrocarbon pore volume)) has been injected into the thin oil layers with well-developed natural fractures. In order to track the movement of CO2 in the oil reservoir, a microseismic monitoring program has been implemented to map the CO2 flow anisotropy and estimate its sweeping efficiency. Gas tracer testing has also been conducted to examine the inter-well connectivity. The temporal change of produced CO2 has been analyzed in a real-time mode to monitor the dynamic response in production wells. It is demonstrated that the migration of CO2 in the thin oil layers can be successfully detected by the microseismic technique, and the sweeping profiles of CO2 obtained from the inverted microseismic are in good agreement with the produced CO2 rate from production wells as well as the reservoir's petrophysical properties. © 2016 Elsevier Ltd.


Zhou X.,PLA Fourth Military Medical University | Liu J.,China University of Petroleum - East China
Physica E: Low-Dimensional Systems and Nanostructures | Year: 2013

The stability of short DNA ring is phenomenologically analyzed by discussing the second variation of its elastic free energy. Through expanding the perturbation functions as Fourier series, the DNA ring's stability condition is obtained in a general case. This result is also suitable for other structures which can be taken as one-dimensional (1D) curvature elastomers, such as ribbons and filaments. Stability analysis in a typical model provides some useful results which are consistent with the experimental observations in a wide parameter range. © 2012 Elsevier B.V. All rights reserved.


Gu Y.-Y.,China University of Petroleum - East China | Yeung A.T.,University of Hong Kong
Journal of Hazardous Materials | Year: 2011

The sorption/desorption characteristics of heavy metals onto/from soil particle surfaces are the primary factors controlling the success of the remediation of heavy-metal contaminated soils. These characteristics are pH-dependent, chemical-specific, and reversible; and can be modified by enhancement agents such as chelates and surfactants. In this study, batch experiments were conducted to evaluate the feasibility of using citric acid industrial wastewater (CAIW) to desorb cadmium from a natural clay from Shanghai, China at different soil mixture pHs. It can be observed from the results that the proportion of cadmium desorbed from the soil using synthesized CAIW is generally satisfactory, i.e., >60%, when the soil mixture pH is lower than 6. However, the proportion of desorbed cadmium decreases significantly with increase in soil mixture pH. The dominant cadmium desorption mechanism using CAIW is the complexion of cadmium with citric acid and acetic acid in CAIW. It is concluded that CAIW can be a promising enhancement agent for the remediation of cadmium-contaminated natural soils when the environmental conditions are favorable. As a result, CAIW, a waste product itself, can be put into productive use in soil remediation. © 2011 Elsevier B.V.