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Wang L.,North China Electrical Power University | Li M.,North China Electrical Power University | Qi F.-H.,Beijing Wuzi University | Xu T.,China University of Petroleum - Beijing
Physics of Plasmas | Year: 2015

Under investigation in this paper is a variable-coefficient derivative nonlinear Schrödinger (vc-DNLS) equation modeling the nonlinear Alfvén waves in the inhomogeneous plasmas. The modulation instability is examined for this inhomogeneous nonlinear model. The nonautonomous breather and rogue wave solutions of the vc-DNLS equation are obtained via the modified Darboux transformation. It is found that the velocity and amplitude of the breather can be controlled by the inhomogeneous magnetic field and nonuniform density. Such novel phenomena as breather amplification and nonlinear Talbot effect-like property are demonstrated with the proper choices of the inhomogeneous parameters. Furthermore, dynamics of the fundamental rogue wave, periodical rogue wave, and composite rogue wave are graphically discussed. The trajectories and amplitudes of the rogue waves can be manipulated by the inhomogeneous magnetic field and nonuniform density. In addition, the nonlinear tunneling of the rogue waves and breathers is studied. As an application, a sample model is treated with our results, and the graphical illustrations exhibit the compressing, expanding, and fluctuating phenomena of the Alfvén rogue waves. © 2015 AIP Publishing LLC.

Xu J.,China University of Petroleum - Beijing
EPL | Year: 2015

This paper starts from modifying the kinetic exchange model and ends with making a parallel between economic crisis and the Bose-Einstein condensation. By introducing a parameter δ, we incorporate the time influence into the Bose-Einstein statistics. And δ is found to represent the technology level in an economy. δ's growth in time enlarges the rich and poor gap and induces economic crisis in free market despite the fact that average living standard is raised. Then we find the "δ-Te-Entropy" dilemma which features a strong implication of the second law of thermodynamics. The dilemma means when an economy is isolated the entropy grows and synergetically Te and δ grow inducing the Bose-Einstein condensation, i.e., economic crisis while for open economy the dilemma breaks. Then we raise the question: What would happen if the world economy as a whole became isolated with ultimately omnibearing globalization? © CopyrightEPLA, 2015.

Wei X.,China University of Petroleum - Beijing
Journal of Convergence Information Technology | Year: 2010

Three-phase shunt active power filter (APF) is often used to compensate the harmonic and reactive current derived from non-linear load. But many non-ideal factors, such as the limited bandwidth of output current loop and the time lag of signal sensing circuit and reference current generation etc, will deteriorate the compensation effect. Proportion-Integral (PI) controller cannot be used simply to control the output current without any steady error due to its limited current tracking capability. A novel output current control architecture in the synchronous rotating frame with ordinary PI and advanced repetitive controller (RC) in parallel is put forward in this paper to enhance the compensation characteristic of three-phase shunt APF. The advanced repetitive controller in parallel is used to eliminate the steady current tracking error caused by cyclic disturbance signal to improve the compensation precision of APF, while the ordinary PI controller is used to ensure the dynamic response performance of APF. The feasibility of this output current controller architecture is verified completely by theoretic analysis and experimental results in detail.

Ge L.,China University of Petroleum - Beijing
Materials Letters | Year: 2011

Novel metal-free g-C 3N 4 photocatalysts with light yellow colors were synthesized by heating melamine precursor at different temperatures. The products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and UV-vis diffuse reflectance spectra (DRS). The effect of calcining temperatures on photocatalytic activities of g-C 3N 4 samples were investigated based on the decomposition of phenol under visible light irradiation. The DRS spectra revealed that the g-C 3N 4 had strong absorption in the visible light region. The photocatalytic results indicated that the highest phenol degradation of 92.5% was achieved on the samples heated at 520 °C for 4 h. This study may provide an approach to development of novel metal-free photocatalysts to degrade organic pollutants by using visible light. © 2011 Elsevier B.V. All rights reserved.

Shi Y.,Dalian University of Technology | Li S.,China University of Petroleum - Beijing | Hu H.,Dalian University of Technology
Journal of Analytical and Applied Pyrolysis | Year: 2012

The resources of lignite in Dongsheng, Inner Mongolia Autonomous Region, China are abundant. Because of its low energy density and typically high moisture content, lignite is not utilized extensively compared to higher coal grades. This paper focused on pyrolysis characteristic of lignite and the properties of its pyrolysates. The result demonstrated that comprehensive utilization of Dongsheng lignite can be achieved with in-depth knowledge of property of Dongsheng lignite. The pyrolysis experiments on lignite were carried out using a thermogravimetric analyzer (TGA) at four different heating rates of 10, 15, 20 and 25°C/min and with a final temperature of 600°C. The kinetics model has been developed and the kinetic parameters are determined from TGA data. © 2012 Elsevier B.V. All rights reserved.

Yan J.,Harbin Engineering University | Fan Z.,Harbin Engineering University | Sun W.,Harbin Engineering University | Ning G.,China University of Petroleum - Beijing | And 5 more authors.
Advanced Functional Materials | Year: 2012

Hierarchical flowerlike nickel hydroxide decorated on graphene sheets has been prepared by a facile and cost-effective microwave-assisted method. In order to achieve high energy and power densities, a high-voltage asymmetric supercapacitor is successfully fabricated using Ni(OH) 2/graphene and porous graphene as the positive and negative electrodes, respectively. Because of their unique structure, both of these materials exhibit excellent electrochemical performances. The optimized asymmetric supercapacitor could be cycled reversibly in the high-voltage region of 0-1.6 V and displays intriguing performances with a maximum specific capacitance of 218.4 F g -1 and high energy density of 77.8 Wh kg -1. Furthermore, the Ni(OH) 2/graphene//porous graphene supercapacitor device exhibits an excellent long cycle life along with 94.3% specific capacitance retained after 3000 cycles. These fascinating performances can be attributed to the high capacitance and the positive synergistic effects of the two electrodes. The impressive results presented here may pave the way for promising applications in high energy density storage systems. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hazra A.,University of Houston | Rosenbaum R.,University of Houston | Bodmann B.,University of Houston | Cao S.,University of Houston | And 3 more authors.
Journal of Neurophysiology | Year: 2012

A description of healthy and pathological brain dynamics requires an understanding of spatiotemporal patterns of neural activity and characteristics of its propagation between interconnected circuits. However, the structure and modulation of the neural activation maps underlying these patterns and their propagation remain elusive. We investigated effects of β-adrenergic receptor (β-AR) stimulation on the spatiotemporal characteristics of emergent activity in rat hippocampal circuits. Synchronized epileptiform-like activity, such as interictal bursts (IBs) and ictal-like events (ILEs), were evoked by 4-aminopyridine (4-AP), and their dynamics were studied using a combination of electrophysiology and fast voltage-sensitive dye imaging. Dynamic characterization of the spontaneous IBs showed that they originated in dentate gyrus/CA3 border and propagated toward CA1. To determine how β-AR modulates spatiotemporal characteristics of the emergent IBs, we used the β-AR agonist isoproterenol (ISO). ISO significantly reduced the spatiotemporal extent and propagation velocity of the IBs and significantly altered network activity in the 1- to 20-Hz range. Dual whole cell recordings of the IBs in CA3/CA1 pyramidal cells and optical analysis of those regions showed that ISO application reduced interpyramidal and interregional synchrony during the IBs. In addition, ISO significantly reduced duration not only of the shorter duration IBs but also the prolonged ILEs in 4-AP. To test whether the decrease in ILE duration was model dependent, we used a different hyperexcitability model, zero magnesium (0 Mg2+). Prolonged ILEs were readily formed in 0 Mg2+, and addition of ISO significantly reduced their durations. Taken together, these novel results provide evidence that β-AR activation dynamically reshapes the spatiotemporal activity patterns in hyperexcitable circuits by altering network rhythmogenesis, propagation velocity, and intercellular/regional synchronization. © 2012 the American Physiological Society.

Cai J.,Shanghai JiaoTong University | Cai J.,China University of Petroleum - Beijing | Wu W.,Shanghai JiaoTong University | Liu R.,Shanghai JiaoTong University
Bioresource Technology | Year: 2013

The three-parallel-DAEM-reaction model was used to study the slow pyrolysis kinetics of rice straw based on thermogravimetric analysis (TGA) data. The kinetic parameters of the model were calculated using the pattern search method. A comparison between the predicted DTG data and experimental values showed good agreement. The influences of the kinetic parameters on the model for describing the experimental data of rice straw were analyzed by means of local parametric sensitivity analysis. The results indicated that the frequency factor and the mean value of the activation distribution for cellulose decomposition affect the model more strongly than other parameters, followed by the corresponding parameters for hemicellulose and lignin. The sensitivity of the model to the standard deviations of the activation energy distributions for all pseudocomponents is very slight. © 2012 Elsevier Ltd.

Lin Q.,China University of Petroleum - Beijing | Yuan H.,Tsinghua University | Biolzi L.,Polytechnic of Milan | Labuz J.F.,University of Minnesota
Engineering Fracture Mechanics | Year: 2014

Fracture tests were performed on sandstone specimens under three-point bending with a variety of notch positions to achieve KII/. KI= 0-12%. At peak load, the maximum crack opening displacement measured by digital image correlation was 45. μm under mixed mode loading and 30. μm under mode I, and these values were used to determine the length of the cohesive zone: 10-12. mm for mixed mode and 5-7. mm for mode I. For mixed mode fracture, the displacement in the cohesive zone was identified to be opening only, while sliding and opening were detected along the remaining length. © 2014 Elsevier Ltd.

Chu K.H.,Xian Jiaotong University | Feng X.,China University of Petroleum - Beijing
Process Safety and Environmental Protection | Year: 2013

Two types of waste paper materials, newspaper and office paper, were evaluated for their potential to be used as renewable feedstock for the production of fermentable sugars via the enzymatic hydrolysis of their cellulose fractions. The effects of four factors (hydrolysis time, enzyme loading, surfactant addition and phosphoric acid pretreatment) on the extent of sugar yield were assessed and quantified by using a methodical approach based on response surface methodology. The statistical experimental design used in this study requires fewer experimental runs compared to some commonly used experimental designs. In the newspaper hydrolysis case, response surface plots revealed that the degree of sugar release increased with an increase in hydrolysis time but it was hardly affected by the enzyme loading and acid pretreatment factors. The surfactant addition factor exhibited a positive effect when the enzyme loading level was relatively low. With office paper as the substrate, three of the four factors (hydrolysis time, enzyme loading and acid pretreatment) exhibited positive effects on the extent of sugar release. At local optimum conditions, the maximum sugar yield from office paper was found to be 0.82 g of reducing sugars per gram of paper, which was about 4.8 times higher than the maximum sugar release from the newspaper substrate. © 2011 The Institution of Chemical Engineers.

Chen X.,University of Science and Technology Beijing | Feng C.,University of Science and Technology Beijing | Wu Z.L.,Beijing Normal University | Yang F.,China University of Petroleum - Beijing | And 4 more authors.
Applied Physics Letters | Year: 2014

This paper reports the interfacial oxygen migration effect and its induced magnetic anisotropy evolution in Pt/Co/MgO/Pt films. During depositing the MgO layer, oxygen atoms from the MgO combine with the neighboring Co atoms, leading to the formation of CoO at the Co/MgO interface. Meanwhile, the films show in-plane magnetic anisotropy (IMA). After annealing, most of the oxygen atoms in CoO migrate back to the MgO layer, resulting in obvious improvement of Co/MgO interface and the enhancement of effective Co-O orbital hybridization. These favor the evolution of magnetic anisotropy from IMA to perpendicular magnetic anisotropy (PMA). The oxygen migration effect is achieved by the redox reaction at the Co/MgO interface. On the contrary, the transfer from IMA to PMA cannot be observed in Pt/Co/Pt films due to the lack of interfacial oxygen migration. © 2014 AIP Publishing LLC.

Han G.,China University of Petroleum - Beijing | Ling K.,University of North Dakota
Journal of Natural Gas Science and Engineering | Year: 2016

The free gas evolved in the pump chamber results in a low rod pump working efficiency, and it can even lead to a failure. A common and effective solution is to install a downhole gas separator before fluid entering the chamber, which can divert the free gas to the annulus. If we can re-inject the diverted gas back to the tubing at a shallower depth above the pump, the flowing gas is then re-combined with the liquid and decreases fluid density. Consequently, the injected gas also creates additional lifting drive for the liquid. A new technology based on this concept has been developed and called Casing Gas Assisted Rod Pumping (CGARP). This paper firstly presents an analytical model to optimize the overall lifting performance and minimize the operating expenditure. It is especially useful in producing hydrocarbon at high GOR.As the gas is re-combined with the liquid above the pump installation depth, the hydrostatic pressure gradient is reduced consequently. However, if the gas reinjection valve is placed at a shallow depth, the well segment at reduced fluid density is subsequently short, so the contribution of gas lift is restricted. Vice versa, if the gas reinjection valve is placed at the depth close to the pump, it requires high pressure to open the gas injection valve, so the gas reinjection can happen infrequently and the production rate is unsfplease. This paper has proposed a genetic optimization method to maximize the overall production system efficiency. A multi-variable vector has been defined, which includes pumping speed and depth, mechanical power, rod string diameter and length, surface stroke length, downhole separator efficiency, as well as gas reinjection valve depth. The optimized object can be the system lifting efficiency or Net Present Value, which must be a function of this vector in the constraint of mass and momentum conservations.This work has been applied as the primary guide for four oil producers with rod pump installed in Jilin field, China. The average system lifting efficiency and production rate have been increased by 20% and 15% respectively. This analytical model has enhanced the field performance. Most importantly, the same concept can be applied for other pump-assisted wells. © 2016 Elsevier B.V.

Gao Y.,Nankai University | Zhou Q.,China University of Petroleum - Beijing | Xie G.,Henan Institute of Science and Technology | Yao Z.,National Marine Environmental Monitoring Center
Journal of Separation Science | Year: 2012

Present study described a simple, environmental benign, easy to operate, and determination method for fungicides including thiram, metalaxyl, diethofencarb, myclobutanil, and tebuconazole. The method is based on temperature-controlled ionic liquid dispersive liquid phase microextraction coupled to HPLC with ultraviolet detector. In the enrichment procedure, ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate [C8MIM] [PF6] was used as the extraction solvent. Variable affecting parameters such as the volume of [C8MIM][PF6], temperature, extraction time, centrifuging time, and salting-out effect have been optimized in detail. Under the optimal conditions, this method has been found to have good linear relationship in the concentration range of 1.0-100 μg/L and excellent detection sensitivity with LODs (S/N = 3) in the range of 0.32-0.79 μg/L. Precisions of proposed method were in the range of 3.7-5.9% for intraday and 7.8-11.0% for interday (RSDs, n = 6). The proposed method was used for the analysis of real water samples and good spiked recoveries at two different spiked levels were achieved in the range of 84.6-102%. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Zuo Q.,Northwestern Polytechnical University | Liu F.,Northwestern Polytechnical University | Wang L.,Northwestern Polytechnical University | Chen C.,China University of Petroleum - Beijing
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2013

The solidification of UNS N08028 alloy subjected to different cooling rates was studied, where primary austenite dendrites occur predominantly and different amounts of sigma phase form in the interdendritic regions. The solidification path and elemental segregation upon solidification were simulated using the CALPHAD method, where THERMO-CALC software packages and two classical segregation models were employed to predict the real process. It is thus revealed that the interdendritic sigma phase is formed via eutectic reaction at the last stage of solidification. On this basis, an analytical model was developed to predict the evolution of nonequilibrium eutectic phase, while the isolated morphology of sigma phase can be described using divorced eutectic theory. Size, fraction, and morphology of the sigma phase were quantitatively studied by a series of experiments; the results are in good agreement with the model prediction. © The Minerals, Metals & Materials Society and ASM International 2013.

Dong Z.-Y.,China University of Petroleum - Beijing | Dong Z.-Y.,China University of Geosciences | Huang W.-H.,China University of Geosciences | Xing D.-F.,Petrochina | Zhang H.-F.,China Shenhua Coal to Liquid and Chemical Yulin Chemical Company
Journal of Hazardous Materials | Year: 2013

Successful remediation of soil co-contaminated with high levels of organics and heavy metals is a challenging task, because that metal pollutants in soil can partially or completely suppress normal heterotrophic microbial activity and thus hamper biodegradation of organics. In this study, the benefits of integrating electrokinetic (EK) remediation with biodegradation for decontaminating soil co-contaminated with crude oil and Pb were evaluated in laboratory-scale experiments lasting for 30 days. The treated soil contained 12,500. mg/kg of total petroleum hydrocarbons (TPH) and 450. mg/kg Pb. The amendments of EDTA and Tween 80, together with a regular refreshing of electrolyte showed the best performance to remediate this contaminated soil. An important function of EDTA-enhanced EK treatment was to eliminate heavy metal toxicity from the soil, thus activating microbial degradation of oil. Although Tween 80 reduced current, it could serve as a second substrate for enhancing microbial growth and biodegradation. It was found that oil biodegradation degree and microbial numbers increased toward the anode and cathode. Microbial metabolism was found to be beneficial to metal release from the soil matrix. Under the optimum conditions, the soil Pb and TPH removal percentages after 30 days of running reached 81.7% and 88.3%, respectively. After treatment, both the residual soil Pb and TPH concentrations met the requirement of the Chinese soil environmental quality standards. © 2013 Elsevier B.V.

Luan G.,China National Petroleum Corporation | He S.,China University of Petroleum - Beijing
Journal of Canadian Petroleum Technology | Year: 2012

The critical gas velocity and flow rate for unloading liquids from a gas well has been the subject of much interest, especially in old gas-producing fields with declining reservoir pressures. For low- pressure gas wells, Turner's model (also called Coleman's model) is judged as more suitable for predicting liquid loading in gas wells. However, field practice proves that there are still a number of low-pressure gas wells producing without loadup when the production rate is lower than Turner's minimum production rate. On the basis of experimental results, a new approach for calculating the critical gas-flow rate is introduced in this paper, which adopts Li's basic concepts, while taking into account the impact of the changes of gas-lifting efficiency caused by the rollover of droplets in the process of rising. A dimensionless parameter, loss factor S, is introduced in the new model to characterize the extent of the loss of gas energy. Well data from Coleman's paper (Coleman et al. 1991b) were used in this paper for validation of the new model. The predicted results from the new model are better than those from Li's model, and even better than Turner's model. The new model is simple and can be evaluated at the wellhead when the pressure is less than 500 psia and the liquid/gas ratios range from 1 to 130 bbl/ MMscf, which is suggested by Turner et al. (1969) to ensure a mist flow in gas wells. Copyright © 2012 Society of Petroleum Engineers.

Yu C.,China University of Petroleum - Beijing | Yu C.,University of Hong Kong | Wong T.N.,University of Hong Kong
International Journal of Production Research | Year: 2014

In practice, it is common for companies to purchase multiple products simultaneously. For the multiple required products, a large number of interested suppliers are involved. It is necessary for the purchasing company to shortlist a small number of qualified and competitive potential suppliers prior to finalising the suppliers for order fulfilment. In addition, synergy effect which is an effect arising between two or more products that produce an effect greater than the sum of their individual effects, could exist in the multi-product supplier selection environment. Since synergy effect between products can affect the choice of suppliers, it is also necessary to incorporate the synergy effect between products in the supplier selection for multiple products. However, few research efforts have been focused on the supplier pre-selection problem, let alone explicitly for multiple products with synergy effect. This paper presents a supplier pre-selection model for multiple products with synergy effect. The model is able to evaluate interested suppliers on the multiple pre-selection criteria, by the fuzzy Technique for Order Preference by Similarity to Ideal Solution (TOPSIS)-based supplier pre-selection algorithm, and shortlist a small number of potential suppliers. Illustrative examples are conducted to demonstrate the function and application of the supplier pre-selection model for multiple products with synergy effect. © 2014 Taylor & Francis.

Wang X.,Henan Normal University | Zhou Q.,Henan Normal University | Zhou Q.,China University of Petroleum - Beijing | Zhai M.,Henan Normal University
Analytical Methods | Year: 2012

The present study focused on the investigation of the applicability of a new material, Zr doped TiO 2 nanotubes, used as the solid phase extraction adsorbent for the enrichment of bisphenol A. The possible impacting parameters on the extraction such as the kind and volume of eluent, sample pH, sample flow rate, and sample volume were investigated in detail. Under the optimal extraction conditions, the proposed method had excellent linear range of 1-80 μg L -1 and the LOD was 0.016 μg L -1. The relative standard deviation at the concentration of 20 μg L -1 (RSDs, n = 6) was 2.9%. Four different real water samples were used for validation, and the spiked recoveries were satisfactory in the range of 102.9-108.8%, and all these results indicated that Zr doped TiO 2 nanotubes had much better extraction performance and would be widely used in the future. © The Royal Society of Chemistry 2012.

Wang B.,Xian Jiaotong University | Feng X.,China University of Petroleum - Beijing | Chu K.H.,Xian Jiaotong University
Journal of Cleaner Production | Year: 2012

In the oil refining and petrochemical industry, hydrogen flows in so-called hydrogen networks are a common feature. A practical problem in hydrogen network analysis is to identify the minimum fresh hydrogen input flowrate to ensure that the hydrogen streams produced by combining the flows of internal sources satisfy certain concentration specifications of sinks for hydrogen and impurities such as H 2S. To tackle this problem, this paper presents a novel graphical procedure, much inspired by the pioneering work of Shelley and El-Halwagi (2000) that makes use of the unique features of ternary composition diagram for three-component systems. In addition, accounting for constraints on flowrates inside a ternary visualization diagram is another novel aspect of this graphical method. Two literature case studies based on hydrogen systems with multiple impurities are solved to illustrate the effectiveness and elegance of the proposed method. © 2012 Elsevier Ltd. All rights reserved.

Ji Y.-J.,Southwest Petroleum University | Liu J.-J.,Southwest Petroleum University | Cheng L.-S.,China University of Petroleum - Beijing
Yantu Lixue/Rock and Soil Mechanics | Year: 2011

According to the execution situation of the tunnel project, the theory of elastoplastic mechanics and the seepage law of groundwater are taken into account; a mathematical model considering seepage-stress coupling of the tunnel is established; seepage and the stress field around the tunnel in different working states are simulated by applying Comsol. The results indicate that during the process of excavation without any measures, deformation of the soil around the tunnel occurs; the deformation of the rock and the settlement of the ground are large; the buildings nearby are in danger and the groundwater infiltrates into the tunnel; the project can't be conducted; after grouting, the deformation of the rock around the tunnel is reduced and the settlement of the ground is controlled; then the buildings nearby are safe and the tunnel excavation can be processed safely.

Li M.,China University of Petroleum - Beijing | Zhang Y.,Petrochina
Journal of Convergence Information Technology | Year: 2012

In order to process the assessment information more exactly and make the decision result more understandable in linguistic setting, a hybrid approach integrating OWA aggregation into VIKOR for multiple attributive group decision making in 2-tuple linguistic setting is proposed. In the method, the OWA is used to aggregate the linguistic assessment information. According to the ideas of VIKOR, the positive ideal solution and negative ideal solution are got. The optimal alternative(s) is determined by the criteria that are group utility, individual regret and advantage rate linguistically. The method has exact characteristics in linguistic information processing and the result is accepted more readily. Finally, a numerical example is used to illustrate the use of the proposed method. The result shows the approach is simple, effective and easy to calculate.

Ma Z.,China University of Petroleum - Beijing
Journal of Convergence Information Technology | Year: 2012

Propose of the paper is to analyze factors of customer service quality that could influence internet banking customer satisfaction in the Chinese commercial banking sector. Moreover, the paper also tries to explain the relationship between customer service quality and customer satisfaction, and to find some major facts for keeping high level internet banking customer satisfaction. The data demonstrated that customer service quality have direct and significant effect to internet banking quality in the banking sector. And customer service quality is positively related to internet banking customer satisfaction. Finally, it is observed that privacy, reputation and price are key factors to affect customer satisfaction in the internet banking service. After the validation of measurement scales, the hypothesis is verified through structural modeling. The authors validate the hypothesis and a measurement model. The paper proposes a structural model for analyzing empirically the link between customer service quality and internet banking customer satisfaction in Chinese internet banking sector.

Xu C.,Tsinghua University | Meng X.,China University of Petroleum - Beijing
Sensors and Actuators, A: Physical | Year: 2013

The effects of different geometrical factors such as the jet nozzle exit width, feedback channel width, oscillator depth, and the oscillating chamber shape on the feedback fluidic oscillator performance were investigated experimentally. A characteristic curve relating to only the oscillation frequency f and Reynolds number Re was found to be insensitive to the oscillator configurations and is expressed as f (Hz) = 6.05 exp(-α/3.30) + 14.5 exp(-α/0.859) + 0.669, where α = ln(Re)/f. The characteristic curve can be used to determine the Reynolds number and thereby the flowrate through the oscillators according to the detected oscillation frequency. © 2012 Elsevier B.V.

Da Silva M.L.B.,EMBRAPA - Empresa Brasileira de Pesquisa Agropecuaria | Cantao M.E.,EMBRAPA - Empresa Brasileira de Pesquisa Agropecuaria | Mezzari M.P.,University of West Santa Catarina | Ma J.,China University of Petroleum - Beijing | Nossa C.W.,Rice University
Microbial Ecology | Year: 2015

Microbial communities from two field-scale swine wastewater treatment plants (WWTPs) were assessed by pyrosequencing analyses of bacterial and archaeal 16S ribosomal DNA (rDNA) fragments. Effluent samples from secondary (anaerobic covered lagoons and upflow anaerobic sludge blanket [UASB]) and tertiary treatment systems (open-pond natural attenuation lagoon and air-sparged nitrification-denitrification tank followed by alkaline phosphorus precipitation process) were analyzed. A total of 56,807 and 48,859 high-quality reads were obtained from bacterial and archaeal libraries, respectively. Dominant bacterial communities were associated with the phylum Firmicutes, Bacteroidetes, Proteobacteria, or Actinobacteria. Bacteria and archaea diversity were highest in UASB effluent sample. Escherichia, Lactobacillus, Bacteroides, and/or Prevotella were used as indicators of putative pathogen reduction throughout the WWTPs. Satisfactory pathogen reduction was observed after the open-pond natural attenuation lagoon but not after the air-sparged nitrification/denitrification followed by alkaline phosphorus precipitation treatment processes. Among the archaeal communities, 80 % of the reads was related to hydrogeno-trophic methanogens Methanospirillum. Enrichment of hydrogenotrophic methanogens detected in effluent samples from the anaerobic covered lagoons and UASB suggested that CO2 reduction with H2 was the dominant methanogenic pathway in these systems. Overall, the results served to improve our current understanding of major microbial communities’ changes downgradient from the pen and throughout swine WWTP as a result of different treatment processes. © 2014, Springer Science+Business Media New York.

Liu S.,China University of Petroleum - Beijing | Guo D.,Tsinghua University | Xie G.,Tsinghua University
Tribology Letters | Year: 2013

A microbubble phenomenon induced by micro-oscillation in the grease lubricating film confined within a nanogap between a highly polished steel ball and a smooth glass disc has been observed with an interferometer. Experimental results show that when the micro-oscillation frequency is a constant value, the microbubble number increases with the micro-oscillation amplitude. When the micro-oscillation amplitude is a constant value, the microbubble number increases with the micro-oscillation frequency when the latter is lower than the critical value and decreases with the micro-oscillation frequency when it is higher than the critical value. Theoretical models and analyses have been used to discuss the bubble formation and describe the characteristics of bubble movement. © 2013 The Author(s).

Pang M.,Xian Jiaotong University | Wei J.,Xian Jiaotong University | Yu B.,China University of Petroleum - Beijing
Chemical Engineering Science | Year: 2010

Bubbly flows exist extensively in industrial processes, so it is very meaningful to study hydrodynamic characteristics of them to improve efficiency of bubbly flow equipments. This paper introduces a numerical method of the Euler-Lagrange two-way model for the air-water bubbly flows in detail. The flow field is simulated by using direct numerical simulations (DNS) in Euler frame of reference, while the bubble dynamics are fully analyzed by integration of Newtonian equations of motion taking into account interphase interaction forces including drag force, lift force, wall lift force, pressure gradient force, virtual mass force, gravity force, buoyant force, and inertia force in Lagrange frame of reference. The coupling between phases is considered by regarding the interphase interaction forces as a momentum source term of the continuous phase. Bubbles distribution and turbulent statistics of the liquid phase are comprehensively analyzed. The results show that an overwhelming majority of bubbles cluster near the walls, and turbulent structures of the liquid phase are modified to some certain by addition of bubbles, namely, the mean streamwise velocity become increased at the core of the channel, the wall-normal and spanwise turbulent intensities and Reynolds stress are reduced. Redistribution of turbulent energy from the streamwise velocity components to wall-normal and spanwise velocity components is also suppressed due to the addition of bubbles. © 2010 Elsevier Ltd.

Hou L.,China University of Petroleum - Beijing
Rheologica Acta | Year: 2012

The yield behavior of Daqing crude oil was studied by means of multi-mode controlled-stress tests with a high-precision stress controlled rheometer. Two experiments of creep and constant stress loading rate were performed. The yield stress of gelled crude oil was dependent on the test conditions such as the stress loading time and the stress loading rate, but the yield strain did not change with test conditions. The yield strain did exist objectively and it can be used as the criterion for the yielding of the structure of gelled crude oil. The yield strain of gelled oil was studied through experiments of creep, constant stress loading rate, oscillatory shear stress increase, and constant shear rate. The yield strain of gelled crude oil decreased with the increasing gel strength. The experiment of constant speed increase of stress showed the strain softening phenomena for low gel strength oil. © 2012 Springer-Verlag.

Li M.,China University of Petroleum - Beijing
Journal of Convergence Information Technology | Year: 2012

Process mining has emerged as a way to analyze processes based on the event logs of the systems that support them. Today's knowledge management systems embedded with workflow systems produce detailed event logs. The omnipresence of event logs is an important enabler for process mining. The primary goal of process mining in knowledge maintenance is to extract knowledge from these logs and use it for a detailed analysis of reality. Most knowledge maintenance process mining algorithms focused on the control flow mining and organization mining. As a result, other aspects have been neglected, e. g., the factors influencing the knowledge maintenance process. Therefore, we focus on case mining. We will present techniques to find the correlation between case properties and the performance. To do this, we use existing techniques in an innovative manner. The proposed approach is applied to an aviation design institute to validate its feasibility. The description of this case study is covered in this paper.

Zhang X.,Tsinghua University | Zhang X.,China University of Petroleum - Beijing | Shi H.,Tsinghua University | Shi H.,Technical University Mnchen | Xu B.-Q.,Tsinghua University
Journal of Catalysis | Year: 2011

Hydrogenation of 1,3-butadiene over Au/ZrO2 catalysts with different gold loadings and calcination temperatures was reported. The catalysts were characterized in depth to understand their structure-property relationship. Gold oxidation states and surface hydroxyl groups, which were found to be sensitive to the gold loading, calcination temperature, and treatment with water, were shown to play vital roles in the hydrogenation activity of Au/ZrO2. Continued activity decrease was seen when the density of surface hydroxyl groups was lowered by elevating the pre-calcination temperature of ZrO2. Fully dehydroxylated Au/ZrO2 was essentially inactive, but became very active after partial regeneration of the hydroxyl groups by water treatment. Moreover, the activity of Au/ZrO2 increased with increasing Au3+/Au0 ratio. Isolated Au3+ ions at the support surface showed up to two orders of magnitude higher activity than Au0 atoms on Au particles. Several models are proposed to address the structural features of active sites for H2 activation in Au/ZrO2 catalysts. © 2011 Elsevier Inc. All rights reserved.

Wang L.,Northwestern Polytechnical University | Liu F.,Northwestern Polytechnical University | Zuo Q.,Northwestern Polytechnical University | Chen C.F.,China University of Petroleum - Beijing
Materials and Design | Year: 2013

Based on the dislocation density theory and kinetics of dynamic recrystallization (DRX), a two-stage model was developed to determine the flow stress curves of N08028 corrosion resistant alloy at hot deformation condition. The proposed model is capable of predicting the flow behavior of work-hardening and dynamic recovery (DRV) region as well as the softening caused by DRX. To establish the model, firstly, the flow stress curves of DRV were modeled by adjusting an evolution equation, with a dynamic recovery parameter r describing plastic behavior in work-hardening and dynamic recovery region. Secondly, the flow stress after onset of DRX can be modeled by incorporating the DRX softening behavior into the evolution equation. A modified Avrami equation was employed to represent this softening behavior and a critical strain εc for initiation of DRX was determined by a double-differentiation method. The established model was adopted to predict the flow stress in the entire deformation process of N08028 corrosion resistant alloy; the corresponding prediction is in good agreement with the experimental result. © 2013 Elsevier Ltd.

Kaiser M.J.,Louisiana State University | Liu M.,China University of Petroleum - Beijing
Marine Structures | Year: 2014

Decommissioning is the final stage in the life cycle of an offshore structure, where all wells are plugged and abandoned, the platform and associated facilities are removed, and the seafloor cleared of all obstructions created by the operations. From 1989 to 2012, 15 structures in water depth greater than 400ft were decommissioned in the U.S. Gulf of Mexico, but none of the project cost have been publicly released. The purpose of this paper is to apply work decomposition algorithms developed by ProServ Offshore to estimate cost for well plugging and abandonment, conductor severance and removal, pipeline abandonment, umbilical and flowline removal, and platform removal for the 53 deepwater fixed platforms and compliant towers in the Gulf of Mexico circa January 2013. Decommissioning cost estimates are presented by stage and operator. Bullwinkle and Pompano are expected to be the most expensive fixed platform decommissioning projects in the Gulf of Mexico estimated at $265 million and $203 million, respectively. Total undiscounted decommissioning liability for the asset class is estimated to be $2.4 billion. © 2014 Elsevier Ltd.

Qian S.,Tsinghua University | Guo D.,Tsinghua University | Liu S.,Tsinghua University | Lu X.,China University of Petroleum - Beijing
Tribology Letters | Year: 2011

Lubrication failure of polyalphaolefin (PAO) oil film at high slide/roll ratios of more than 1.9 has been experimentally investigated based on a ball-on-disc configuration. The central film thickness and the oil pool shape in the contact were determined by optical interferometry and fluorescence microscopy, respectively, and the traction coefficient and surface profiles of the tribopairs were measured using a tension-compression sensor and light surface profilometer, respectively. The results demonstrate that the central film in the contact was in the elastohydrodynamic lubrication regime at the initial stage under high slide/roll ratios. Variation in the traction coefficient and the presence of wear scars on the disc surface shows that the sliding speed played an important role in lubrication failure. We propose that a thermal effect explains the obtained results at high slide/roll ratios. The fluorescence technique combined with optical interferometry was also used to gain more understanding of lubrication properties under mixed slide/roll conditions. © Springer Science+Business Media LLC 2011.

Wu Z.,China University of Petroleum - Beijing | Wu Z.,Nankai University | Chen J.,Nankai University | Di Q.,Nankai University | Zhang M.,Nankai University
Catalysis Communications | Year: 2012

We reported a general strategy of size-controlled synthesis of supported nickel nanoparticle catalysts using electroless plating technique. The synthesis conditions (e.g. compositions of plating solution and plating temperatures) were optimized to promote plating rate, and nickel nanoparticles with 9 nm diameter and a narrow size distribution were highly dispersed on TiO 2. The as-prepared Ni/TiO 2 catalyst showed high activity, selectivity and stability in the selective hydrogenation of p-nitrophenol to p-aminophenol. © 2011 Elsevier B.V. All rights reserved.

Wu Z.,China University of Petroleum - Beijing | Mao Y.,Nankai University | Song M.,Nankai University | Yin X.,Nankai University | Zhang M.,Nankai University
Catalysis Communications | Year: 2013

Small Cu clusters (~ 1 nm) were highly dispersed over boehmite via an aqueous chemical reduction method. In comparison with Cu/γ-Al 2O3, Cu/SiO2 and Ru/C catalyst, Cu/boehmite catalyst showed the highest conversion and selectivity of 1,2-propanediol in the hydrogenolysis of glycerol. The good conversion and selectivity are ascribed to the small size of Cu metal clusters and the Lewis acid sites of boehmite, which provides high surface concentrations of active metal sites without CC bond cleavage activity and promotes the dehydration of glycerol to acetol as the intermediate of 1,2-propanediol, respectively. © 2012 Elsevier B.V.

Loizou N.,Department of Energy, United Kingdom | Chen S.,China University of Petroleum - Beijing
First Break | Year: 2012

Perhaps over a billion barrels of oil, distributed over dozens of mostly small prospects, remain trapped in Palaeogene reservoirs in the UK sector of the North Sea Basin. Here we consider whether traditional amplitude versus offset (AVO) analysis, augmented by spectral decomposition, can provide a useful tool in helping to evaluate which of these prospects are worthwhile targets for drilling. In recent years, exploration drilling in the Palaeogene play fairway of the UK Northern North Sea has had mixed results. Eighty percent of wells drilled since 2000 have failed to encounter hydrocarbons, for reasons that include poor interpretation and evaluation of prospects, lack of AVO analysis, and positioning of wells on poor quality seismic data. Our analysis suggests that AVO analysis and spectral decomposition can be very useful and powerful tools for predicting the presence or absence of hydrocarbons in undrilled Palaeogene prospects in the North Sea. However, the validity of the results depends upon the availability of good quality seismic data with broad frequency content that have been acquired with cable lengths greater than 3 km. © 2012 EAGE www.firstbreak.org.

Hou S.,Louisiana Tech University | Song P.,CAS Beijing Institute of Applied Physics And Computational Mathematics | Wang L.,China University of Petroleum - Beijing | Zhao H.,University of California at Irvine
Journal of Computational Physics | Year: 2013

A typical elliptic interface problem is casted as piecewise defined elliptic partial differential equations (PDE) in different regions which are coupled together with interface conditions, such as jumps in solution and flux across the interface. In many situations, such as the interface is moving, the challenge is how to solve such a problem accurately, robustly and efficiently without generating a body fitted mesh. The key issue is how to capture complex geometry of the interface and jump conditions across the interface effectively on a fixed mesh while the interface is not aligned with the mesh and the PDE is not valid across the interface. In this work we present a systematic formulation and further study of a second order accurate numerical method proposed in Hou and Liu (2005) [16] for elliptic interface problem. The key idea is to decompose the solution into two parts, a singular part and a regular part. The singular part captures the interface conditions while the regular part belongs to an appropriate space in the whole domain, which can be solved by a standard finite element formulation. In a general setup the two parts are coupled together. We give an explicit study of the construction of the singular part and the discretized system for the regular part. One key advantage of using weak formulation is that one can avoid assuming/using more regularity than necessary of the solution and the interface. We present the numerical algorithm and numerical tests in 3D to demonstrate the accuracy and other properties of our method. © 2013.

Li H.,University of Business and Technology | Sun Q.,Shandong University of Science and Technology | Zhang Q.,China University of Petroleum - Beijing | Wallin F.,University of Business and Technology
Renewable and Sustainable Energy Reviews | Year: 2015

Heating represents the largest proportion of energy use as supplied to consumers across all end energy uses. Therefore, there is huge potential for energy savings in the heating sector in order to reduce the emission of CO2. District heating (DH) has been considered an efficient, environmentally friendly and cost-effective method for heating in buildings, and is playing an important role in the mitigation of climate change. In the interest of fairness and in the highly competitive market the DH companies operate, there is a strong need to develop a novel heat pricing mechanism in order to promote sustainable development of DH systems. In this paper, existing methods and models regarding heat pricing have been reviewed. The features of different pricing mechanisms have been analysed, including advantages and disadvantages. Insights into developing an advanced pricing mechanism for DH systems have been offered. © 2014 Elsevier Ltd. All rights reserved.

Xiao H.,Tsinghua University | Guo D.,Tsinghua University | Liu S.,China University of Petroleum - Beijing | Pan G.,Tsinghua University | Lu X.,Tsinghua University
Tribology Letters | Year: 2011

Ionic liquids are generally considered as environmentally friendly material. The film thicknesses of ionic liquids and silicone oils at high pressures up to 3 GPa are measured employing the relative optical interference intensity method. The results show that for the three ionic liquids the relative order of film thickness is 1-octyl-3-methylimidazolium hexafluorophosphate ([OMIM]PF 6) > 1-hexyl-3-methylimidazolium hexafluorophosphate ([HMIM]PF 6) > 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF 6). In elastohydrodynamic lubrication the order of viscosity can simply account for this fact. In thin film lubrication condition the length of alkyl side chain and arrangement manner of cation are used to explain the experimental results. Another remarkable phenomenon is that even though the viscosities of silicone oils are close to those of ionic liquids, the measured film thicknesses of silicone oils are quite less than those of the ionic liquids. The results show that long alkyl chain ionic liquid can form rather thick films at high pressure. © 2010 Springer Science+Business Media, LLC.

Zhou Q.,China University of Petroleum - Beijing | Zhou Q.,Henan Normal University | Zhang X.,Henan Normal University
Journal of Separation Science | Year: 2010

This paper describes a new method for rapid and sensitive determination of diflubenzuron, flufenoxuron, triflumuron and chlorfluazuron in water samples by ultrasound-assisted ionic liquid dispersive liquid-phase microextraction in combination with HPLC. Ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate ([C6MIM][PF6]) was used as the extraction solvent for the enrichment of four benzoylurea (BU) pesticides. Factors such as volume of [C6MIM][PF6], sonication time, sample pH, extraction time, centrifuging time and salting-out effect were systematically investigated. Under the optimum conditions, an excellent linear relationship was achieved in the range of 1.0-100 μg/L. The detection limits varied from 0.21 to 0.45 μg/L and the precision of the method was below 6.9% (RSD, n=6). The proposed method was successfully applied for the determination of these BU pesticides in water samples and excellent spiked recoveries were achieved. All these results demonstrated that this procedure provided a new simple, rapid, easy to operate, efficient and sensitive method for the analysis of BU pesticides in aqueous samples. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Jiang W.,Jiangsu University | Zhu W.,Jiangsu University | Li H.,Jiangsu University | Chao Y.,Jiangsu University | And 4 more authors.
Journal of Molecular Catalysis A: Chemical | Year: 2014

Various Fenton-like catalysts prepared by choline chloride (ChCl) and metal salts (FeCl3, ZnCl2, SnCl2) were characterized by FT-IR, UV-vis, Raman, ESI-MS and elemental analysis. High desulfurization efficiency of dibenzothiophene (DBT) could be obtained not only in hydrophilic ionic liquid (IL) [Bmim]BF4 (94.9%) but also in hydrophobic IL [Omim]BF4 (97.2%) by using ChFeCl4 as a catalyst under mild conditions. ESR measurements could give the evidence that the active oxygen species generated by ChFeCl4 and H2O2 in IL were involved in the catalytic oxidation of DBT. The influential factors, including reaction time, temperature, catalyst dosage, and O/S (H 2O2/DBT) molar ratio, were investigated in detail to estimate the optimal conditions for the desulfurization system in [Omim]BF 4. The aromatic sulfur compounds, DBT, benzothiophene (BT), and 4,6-dimethyldibenzothiophene (4,6-DMDBT), could be oxidized to the corresponding sulfones, which were detected by GC-MS. Moreover, the catalytic system containing IL and catalyst could be easily separated from oil and could be recycled at least five times without a significant decrease on removal of DBT. © 2013 Elsevier B.V. All rights reserved.

Ge L.,University of California at Riverside | Ge L.,China University of Petroleum - Beijing | Zuo F.,University of California at Riverside | Liu J.,University of California at Riverside | And 5 more authors.
Journal of Physical Chemistry C | Year: 2012

Novel CdS quantum dot (QD)-coupled graphitic carbon nitride (g-C 3N 4) photocatalysts were synthesized via a chemical impregnation method and characterized by X-ray diffraction, transmission electron microscopy, ultraviolet-visible diffuse reflection spectroscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and photoluminescence spectroscopy. The effect of CdS content on the rate of visible light photocatalytic hydrogen evolution was investigated for different CdS loadings using platinum as a cocatalyst in methanol aqueous solutions. The synergistic effect of g-C 3N 4 and CdS QDs leads to efficient separation of the photogenerated charge carriers and, consequently, enhances the visible light photocatalytic H 2 production activity of the materials. The optimal CdS QD content is determined to be 30 wt %, and the corresponding H 2 evolution rate was 17.27 μmol·h -1 under visible light irradiation,∼9 times that of pure g-C 3N 4. A possible photocatalytic mechanism of the CdS/g-C 3N 4 composite is proposed and corroborated by photoluminescence spectroscopy and photoelectrochemical curves. © 2012 American Chemical Society.

Liu J.,China University of Petroleum - Beijing | Teo K.L.,Curtin University Australia | Wang X.,Curtin University Australia | Wu C.,Curtin University Australia
Soft Computing | Year: 2015

Differential search (DS) is a recently developed derivative-free global heuristic optimization algorithm for solving unconstrained optimization problems. In this paper, by applying the idea of exact penalty function approach, a DS algorithm, where an S-type dynamical penalty factor is introduced so as to achieve a better balance between exploration and exploitation, is developed for constrained global optimization problems. To illustrate the applicability and effectiveness of the proposed approach, a comparison study is carried out by applying the proposed algorithm and other widely used evolutionary methods on 24 benchmark problems. The results obtained clearly indicate that the proposed method is more effective and efficient over the other widely used evolutionary methods for most these benchmark problems. © 2015 Springer-Verlag Berlin Heidelberg

Zhang Y.,China University of Petroleum - Beijing | Doroodchi E.,University of Newcastle | Moghtaderi B.,University of Newcastle
Energy and Fuels | Year: 2015

Fe2O3/Al2O3 is found to be a suitable oxygen carrier candidate for the chemical looping combustion with ultralow methane concentration in a previous study by our team. In order to facilitate the fundamental reactor design and understand the energy consumption, the reduction kinetics mechanism of Fe2O3 (hematite) with 0.5 vol % CH4 was determined and the kinetic parameters were estimated based on the thermogravimetric analysis. Two oxygen carriers (i.e., Fe25Al and Fe45Al) were prepared and used in the TGA experiment. It was observed that the reduction of Fe2O3 was a two-steps process. Initially, Fe2O3 is transformed into Fe3O4 (magnetite) at a fast reaction rate and followed by a slow step corresponding to the reduction from Fe3O4 to FeAl2O4. A topochemical approach associated with Hancock and Sharp's method was therefore applied to determine the most suitable kinetic model for the reduction process. It was found that the initial fast step can be described by the Avrami-Erofe'ev phase change model, the A2 model for low conversion, and the A3 model for high conversion, whereas the reaction for the second step was in diffusion control. It also can be concluded that within the Fe2O3 content of 25-45 wt %, there is no difference on the reduction kinetic mechanism and similar activation energy was obtained, which can be comparable with the findings in the literature. © 2014 American Chemical Society.

Pang M.J.,Xian Jiaotong University | Pang M.J.,Changzhou University | Wei J.J.,Xian Jiaotong University | Yu B.,China University of Petroleum - Beijing
Ocean Engineering | Year: 2014

Although many investigations on the drag reduction by microbubbles have been conducted, a general mechanism guiding the design of the drag reduction system has not been achieved yet. The drag reduction by microbubbles was investigated in detail with the Euler-Lagrange two-way coupling method in order to understand the drag reduction mechanism by microbubbles in this paper. The liquid velocity field was solved with direct numerical simulations (DNS), and the bubble trajectory was calculated by Newtonian motion equation. The mutual momentum transfer between gas and liquid phases was bridged by interphase forces. The computational results show that a low drag-reduction rate is obtained, the liquid-phase velocity is slightly increased in the region away from the channel wall (i.e., the channel side containing microbubbles), and the turbulence intensity and Reynolds shear stress of the liquid phase are changed along the whole channel height. The present analysis shows that the drag reduction depends on mutual interactions between microbubbles and the liquid turbulence with the help of interphase forces. © 2014 Elsevier Ltd.

Zhang W.,China University of Petroleum - Beijing | Wei D.,Pukyong National University | Jin Seo H.,Pukyong National University
Materials Letters | Year: 2013

A new phosphor of Eu2+-doped pollucite CsAlSi2O 6 was synthesized by conventional solid-state reaction. The photoluminescence (PL) excitation and emission spectra were measured. The phosphors can be efficiently excited by near-UV light and show broad luminescence spectra with the main emission peak at around 450 nm corresponding to 5d-4f transition of Eu2+ ions. CsAlSi2O 6:0.05 Eu2+ exhibits the brightest blue-green emission with CIE coordinates (x=0.21, y=0.32) and a quantum efficiency of 67%. The dependence of the luminescence intensity of CsAlSi2O 6:Eu2+ on temperatures was investigated. The activation energy (ΔE) for thermal quenching was reported. © 2012 Elsevier B.V. All rights reserved.

Pan M.,China University of Petroleum - Beijing
Environment, Energy and Sustainable Development - Proceedings of the 2013 International Conference on Frontier of Energy and Environment Engineering, ICFEEE 2013 | Year: 2014

This paper deals with option pricing with jump volatility, which is described by a Poisson process. Based on this viewpoint, we show that the jump volatility produces the Knightian uncertainty and then we establish our model. We identify the factors which decide the Knightian premium and obtain the price of European call option. We also find that the option price under Knightian uncertainty is not unique. © 2014 Taylor & Francis Group, London.

Wang F.,China University of Petroleum - Beijing
Journal of Natural Gas Science and Engineering | Year: 2015

The superposition principle is the fundamental theory of pressure-transient analysis. Many pressure analysis methods, such as pressure build-up analysis and deconvolution, are based on the superposition principle. Deconvolution, which can provide the equivalent constant-rate pressure response from variable-rate pressure data, has become more popular in recent years. Mathematically, the superposition principle is only valid in a linear system. However, many reservoir behaviours can make the system nonlinear and the superposition principle invalid, such as the time-dependent skin factor and permeability, multiphase flow and non-Darcy flow. Erroneously applying the superposition principle and related methods will lead to incorrect analysis results and inappropriate production decisions. To reduce the analysis uncertainties and obtain the correct reservoir information, diagnosing the nonlinear reservoir behaviour and selecting the appropriate pressure analysis method are important. In this paper, nonlinear reservoir behaviours are diagnosed from transient pressure data with the wavelet transform. A defined diagnosis function can effectively diagnose the nonlinear reservoir behaviours. As studies have proved, the diagnosis function is constant in the linear system and time varying in the nonlinear system. Based on the diagnosis result, the nonlinear system can be linearized in a short time period using the sliding window technique, and the superposition principle and related methods can be correctly applied. © 2015 Elsevier B.V.

In this paper, the dielectric relaxation of SiO2 nano-particle suspensions is studied by electrical impedance spectroscopy method. The case of suspension composed of particles with thick double layer is concerned. The objective of this study is to find out the relationship between particle properties (size and concentration) and electrical impedance spectroscopy for developing a particle characterization method based on electrical impedance spectroscopy/tomography. The influences of particle size on electrical impedance spectroscopy (EIS) and relaxation frequency are investigated and analyzed. The experimental results indicate that impedance phase angle and α relaxation frequency are functions of particle size. α relaxation frequency is proportionally changing with (a+ κ-1)-n (a is particle radius, κ-1 is double layer thickness, n equals 0.344 for 4.76% suspension and 0.308 for 2.38% suspension). The exponent term, n, is smaller than the one in dilute suspensions (n=2), which is possibly due to decreasing of diffusion distance of ions around the particles in concentrated suspensions with thick double layer. The impedance parameters, including conductivity increment, δK', and α relaxation frequency are influenced by particle volume fraction. The conductivity increment, δK' becomes less negative with increasing particle volume fraction due to the positive contribution of double layer charge on the conductivity increment. The α relaxation frequency increases with increasing particle volume fraction and the small particles show a more significant increase than large particles. The experimental result on the differential electrical impedance tomographic images between the silica suspension and water (with same conductivity value) shows that small differences on the values of impedance imaginary part and phase can be observed at the upper right corner in the EIT images, which represent a small differentiation on the dielectric property caused by the electrical polarization of double layer on the particle surface. © 2015 Elsevier B.V..

Wang X.,Nanjing University | Wang X.,China University of Petroleum - Beijing | Chou I.-M.,U.S. Geological Survey | Hu W.,Nanjing University | Burruss R.C.,U.S. Geological Survey
Geochimica et Cosmochimica Acta | Year: 2013

A previously unknown liquid-liquid phase separation in vapor-saturated aqueous MgSO4 solutions containing 1.19-19.36mass% of MgSO4 was observed in fused silica capillary capsules during heating at temperatures above 259°C. Under these conditions, we observed that MgSO4-rich droplets were separated from the original aqueous MgSO4 solutions during heating, and these two coexisting liquid phases homogenized during cooling. The newly discovered liquid-liquid phase separation in MgSO4 solutions was characterized by a lower critical solution temperature phenomenon, which was considered to be a macro-scale chemical property of polymeric mixtures. In situ Raman spectroscopic investigations identified a distinctly new ν1(SO42-) mode at ~1020cm-1 in the MgSO4-rich droplets; the new ν1(SO42-) mode was predicted to be present in MgSO4 polymer(s) in aqueous solutions. As mentioned above, both the phase behavior and relevant Raman spectra indicate the existence of polymer(s) in MgSO4 solutions. The recognition of the liquid-liquid phase separation and polymerization of MgSO4 in aqueous MgSO4 solutions is important for the experimental investigation of thermochemical sulfate reduction (TSR), because (1) the emergence of the MgSO4-rich droplets will substantially increase the local MgSO4 concentration, which is not representative of the geologic environments where TSR occurs; and (2) the formation of various ion pairs and MgSO4 polymers makes the mechanism of TSR far more complex than that occurring at relatively low temperatures (i.e., <200°C). © 2012 Elsevier Ltd.

Cai J.,Shanghai JiaoTong University | Cai J.,China University of Petroleum - Beijing | Wu W.,Shanghai JiaoTong University | Liu R.,Shanghai JiaoTong University
Industrial and Engineering Chemistry Research | Year: 2012

A critical study of the use of the iterative linear integral isoconversional method for a parallel reactions process and a successive reactions process has been performed using theoretical simulated nonisothermal data. The activation energies obtained for these complex processes show a strong dependence on the range of heating rates, which is against the assumptions of isoconversional methods. Therefore, a systematic kinetic analysis for discriminating the reactions rather than merely assuming that the activation energy varies with the conversion would be required for understanding the reaction mechanism of these processes. © 2012 American Chemical Society.

Li L.-C.,China University of Petroleum - Beijing
Proceedings - 2010 2nd WRI Global Congress on Intelligent Systems, GCIS 2010 | Year: 2010

In exploration and development of oil and gas engineering, signal processing method based on wavelet transform is very import approach. After analyzing a kind of not-compact-supported (or not all compact-supported) orthogonal wavelet basis, a new method of wavelet transform algorithms based on FFT (Fast Fourier Transform) has been presented in this paper, which does not hurt the transform effect but speed the computing ,and help the wavelet transform to be implemented faster for signal processing. Based on the comparison with fast algorithms from many references at home and abroad, we can get better speed and effect. Using it to our project about image processing for mobile application, we have gained very good results, so it can be used generally.. © 2010 IEEE.

Zhao H.Y.,Virginia Polytechnic Institute and State University | Li D.,Virginia Polytechnic Institute and State University | Li D.,China University of Petroleum - Beijing | Bui P.,Virginia Polytechnic Institute and State University | And 2 more authors.
Applied Catalysis A: General | Year: 2011

The gas phase hydrodeoxygenation (HDO) of guaiacol, as a model compound for pyrolysis oil, was tested on a series of novel hydroprocessing catalysts - transition metal phosphides which included Ni2P/SiO2, Fe2P/SiO2, MoP/SiO2, Co2P/SiO 2 and WP/SiO2. The turnover frequency based on active sites titrated by the chemisorption of CO followed the order: Ni2P > Co2P > Fe2P, WP, MoP. The major products from hydrodeoxygenation of guaiacol for the most active phosphides were benzene and phenol, with a small amount of methoxybenzene formed. Kinetic studies revealed the formation of reaction intermediates such as catechol and cresol at short contact times. A commercial catalyst 5% Pd/Al2O3 was more active than the metal phosphides at lower contact time but produced only catechol. A commercial CoMoS/Al2O3 deactivated quickly and showed little activity for the HDO of guaiacol at these conditions. Thus, transition metal phosphides are promising materials for catalytic HDO of biofuels. © 2010 Elsevier B.V. All rights reserved.

Li Q.,CAS Wuhan Institute of Rock and Soil Mechanics | Wei Y.-N.,CAS Wuhan Institute of Rock and Soil Mechanics | Liu G.,CAS Wuhan Institute of Rock and Soil Mechanics | Lin Q.,China University of Petroleum - Beijing
Applied Energy | Year: 2014

CO2 geological storage, when combined with deep saline water recovery (CO2-EWR), not only achieves the relatively secure storage of CO2 that was captured from the coal chemical industry, due to lower pressure, but also enhances saline water for drinking and industrial or agricultural utilization. This storage will undoubtedly become a win-win choice for the enhancement of energy security and for the promotion of regional development in China, particularly for western regions with a relative shortage of water resources and a more fragile ecological environment. In this paper, a three-dimensional injection-extraction model is established that uses the TOUGH2/ECO2N program according to typical formation parameters of a coal chemical industry in the Xinjiang Uyghur Autonomous Region. Numerical results showed that under the guarantee of sufficient water conditions, 1.73×108tons of saline water could be produced when the CO2-EWR is adopted. Well arrangements and formation parameters are also analyzed, and the following conclusions can be drawn: arrangements of pumping wells, such as pumping well number, pumping rate and distance, have considerable influences on the reservoir pressure, and in addition, the sensitivity of pressure on the distance and pumping rate decreases as their values increase. In view of these features, it is necessary to find an optimal point to achieve the best combination of pressure, the leakage time and the amount of dissolution. Formation parameters primarily control the mechanism of CO2 migration and dissolution. Salinity in the salt water has the greatest impact on CO2 dissolution trapping followed by permeability and porosity. The arrival time that is allowable for saline water production primarily depends on porosity followed by the permeability ratio and the arrangements of pumping wells. The reservoir pressure change that is caused by parameters is not obvious compared with setting pumping wells. Overall, CO2-EWR technology is a potential strategic choice for China, particularly in western regions. Additionally, the analysis results provide a reliable guide and reference for CO2 storage site selection, as well as the practical arrangements of wells. © 2013 Elsevier Ltd.

Luo D.,China University of Petroleum - Beijing | Yan C.,CAS Beijing National Laboratory for Molecular | Wang T.,CAS Beijing National Laboratory for Molecular
Small | Year: 2015

Studies on the self-assembly of nanoparticles have been a hot topic in nanotechnology for decades and still remain relevant for the present and future due to their tunable collective properties as well as their remarkable applications to a wide range of fields. The novel properties of nanoparticle assemblies arise from their internal interactions and assemblies with the desired architecture key to constructing novel nanodevices. Therefore, a comprehensive understanding of the interparticle forces of nanoparticle self-assemblies is a pre-requisite to the design and control of the assembly processes, so as to fabricate the ideal nanomaterial and nanoproducts. Here, different categories of interparticle forces are classified and discussed according to their origins, behaviors and functions during the assembly processes, and the induced collective properties of the corresponding nanoparticle assemblies. Common interparticle forces, such as van der Waals forces, electrostatic interactions, electromagnetic dipole-dipole interactions, hydrogen bonds, solvophonic interactions, and depletion interactions are discussed in detail. In addition, new categories of assembly principles are summarized and introduced. These are termed template-mediated interactions and shape-complementary interactions. A deep understanding of the interactions inside self-assembled nanoparticles, and a broader perspective for the future synthesis and fabrication of these promising nanomaterials is provided. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sun J.,CAS Beijing National Laboratory for Molecular | Gao T.,CAS Beijing National Laboratory for Molecular | Song X.,CAS Beijing National Laboratory for Molecular | Zhao Y.,Peking University | And 9 more authors.
Journal of the American Chemical Society | Year: 2014

High-quality monolayer graphene was synthesized on high-K dielectric single crystal SrTiO3 (STO) substrates by a facile metal-catalyst-free chemical vapor deposition process. The as-grown graphene sample was suitable for fabricating a high performance field-effect transistor (FET), followed by a far lower operation voltage compared to that of a SiO2-gated FET and carrier motilities of approximately 870-1050 cm2·V -1·s-1 in air at rt. The directly grown high-quality graphene on STO makes it a perfect candidate for designing transfer-free, energy-saving, and batch production of FET arrays. © 2014 American Chemical Society.

Ruan L.,University of California at Los Angeles | Ramezani-Dakhel H.,University of Akron | Chiu C.-Y.,University of California at Los Angeles | Zhu E.,University of California at Los Angeles | And 4 more authors.
Nano Letters | Year: 2013

Surfactants with preferential adsorption to certain crystal facets have been widely employed to manipulate morphologies of colloidal nanocrystals, while mechanisms regarding the origin of facet selectivity remain an enigma. Similar questions exist in biomimetic syntheses concerning biomolecular recognition to materials and crystal surfaces. Here we present mechanistic studies on the molecular origin of the recognition toward platinum {111} facet. By manipulating the conformations and chemical compositions of a platinum {111} facet specific peptide, phenylalanine is identified as the dominant motif to differentiate {111} from other facets. The discovered recognition motif is extended to convert nonspecific peptides into {111} specific peptides. Further extension of this mechanism allows the rational design of small organic molecules that demonstrate preferential adsorption to the {111} facets of both platinum and rhodium nanocrystals. This work represents an advance in understanding the organic-inorganic interfacial interactions in colloidal systems and paves the way to rational and predictable nanostructure modulations for many applications. © 2013 American Chemical Society.

Liu Y.,China University of Petroleum - Beijing
Natural Gas Industry | Year: 2013

China has successively released a series of schemes constituting an overall plan of a complete industrial chain for natural gas industry, the blueprint of which can be seen clearly during the national 12th Five-Year Plan. This overall plan is formulated under such background as facing global and domestic pressure in emission reductions improving the economic development to a new level; keeping the sustainable development of the industrial chain, and so on. The highlights of the overall plan are reflected in the following three aspects. (1) The total planned supply of natural gas can ensure the planned consumption. From the resource reserves to consumption capacity, the overall plan leaves adequate room to enhance the support capability of gas supply. The development of unconventional natural gas resources as well as development capacity reserves provides a support for sequence of resource supply after the 12th Five-Year Plan. (2) With the infrastructures to be perfected as the focus, natural gas usage areas will be expanded, natural gas transmission capacity will be enhanced, natural gas will be utilized in various ways, and the effective connection of each part in the industrial chain will be strengthened. (3) More exploring ways will be tried to promote the evolution of the industrial chain towards a competitive structure. However, some defects can be seen in this overall plan. (1) The energy management system is so hard to adapt to the development needs that the overall plan will be easily split; as a result, the critical system will be altered with neither timetable nor roadmap, and the top level system design will get imperfect. (2) The target of the natural gas industrial chain 's structural development is so ambiguous that it becomes extremely hard to judge the future trend. For instance, there is even no any clear-cut viewpoint yet on how to regulate the integration of the upstream, midstream and downstream of the manufacturers.

Zhang K.,Sinopec | Zhang L.,China University of Petroleum - Beijing
Natural Gas Industry | Year: 2013

Unconventional oil and gas exploration and development have moved from behind the scenes to the stage all over the world. To get a better understanding and make a proper decision, we made a discussion on the E & P history and prospect of unconventional natural gas resources such as tight oil and gas, shale oil and gas, etc. The following findings were obtained. a. In current industrial mining, tight oil & gas, in a broad sense, mainly includes tight sandstone oil & gas, shale oil & gas and coalbed methane (CBM) with the same core exploiting technologies-horizontal drilling and hydraulic fracturing. b. In the USA, exploitation has been extending from tight sand hydrocarbons to coalbed methane and shale gas. The decrease of natural gas prices justified the rapid development of shale oil exploitation in recent years, which makes the USA the fastest growing producer of natural gas and oil. c. The up-to-date survey indicates that shale oil and shale gas account for 10% and 32% respectively of the global cumulative assessed hydrocarbon reserves. d. Tight liquids, an outstanding and popular concept worldwide in recent years, are mainly of shale oil including Natural Gas liquids (NGLs) and Light Oil. It suggests that only relatively light oil can be exploited out of tightly reserved oil. Accordingly, it could be named Light Tight Oil or LTO.

Song Q.,China University of Petroleum - Beijing
Applied Mechanics and Materials | Year: 2011

Magnetic flux leakage (MFL) is a non-destructive testing method used to inspect ferrous materials. However, there are a variety of factors that can affect the MFL inspection tool's ability to detect and characterize anomalies. An orthogonal experimental design (OED) method is applied to study the effects of apparatus parameters on MFL signals. Integration of OED method of analysis into a routine sample preparation technique could improve the repeatability and quantization capabilities of MFL tools. Three key apparatus parameters, namely permanent magnet (PM) height, magnetic concentrator (MC) length and backing iron (BI) length are chosen for the present study. The importance of each of these key parameters on MFL signals for different defects is determined by a series of experiments. © (2011) Trans Tech Publications.

Ji Z.-L.,China University of Petroleum - Beijing
Zhongguo Shiyou Daxue Xuebao (Ziran Kexue Ban)/Journal of China University of Petroleum (Edition of Natural Science) | Year: 2013

The concentration and size distribution of dust particles at the inlet and outlet of multi-cyclone separators and filters in two domestic natural gas stations are measured by the particle online measuring devices for high pressure gas, and the separation performances of in-site cyclones and filters are evaluated. These field test results are compared with the laboratory test results under atmospheric temperature and pressure. The field test results of multi-cyclone separators are in agreement with the laboratory test results, and so the data measured under atmospheric temperature and pressure can be used as the indicator for evaluating separation performance of multi-cyclone under high pressure condition. However, the field test results of filters show some differences from the laboratory test results. The overall efficiency of filters decreases with the operation period because some large particles can penetrate the filter candle.

Li J.,China University of Petroleum - Beijing | Guo B.,University of Louisiana at Lafayette | Ling K.,University of North Dakota
Journal of Energy Resources Technology, Transactions of the ASME | Year: 2013

With the downturn in natural gas prices, it is vitally important to reduce the cost of drilling shale gas wells. Gas-percussion drilling has been recently employed in shale gas field development. It increases footage capacity by nearly 60%. However, wellbore erosion by the high-velocity gas has been recognized as a problem that hinders further application of the technology. This paper investigates a potential solution to the problem using a new type of flow-diverting joint (FDJ). The FDJ with exchangeable nozzles can be installed at the shoulder of the drill collar to partially bypass gas flow into the annulus between the drill pipe and open hole. Hydraulics computations with a state-of-the-art computer program indicate that this technique will allow for the use of high-gas injection rate to carry drill cuttings while reducing the gas flow rate through the drill bit. As a result, the gas velocity in the drill collar-open hole annulus can be maintained at a safe level to prevent hole erosion. The reduced gas flow rate through the drill bit also minimizes wellbore enlargement at hole bottom. Sensitivity analyses with the computer program show that the FDJ-nozzle area to bit-nozzle area ratio is directly proportional to the annulus area ratio, and the bypassed flow rate fraction remains constant as drilling progresses. This makes the FDJ system easy to design and practical to use over a long section of hole to be drilled. © 2013 by ASME.

Fu G.,Federal University of Rio de Janeiro | Lourenco M.I.,Federal University of Rio de Janeiro | Duan M.,China University of Petroleum - Beijing | Estefen S.F.,Federal University of Rio de Janeiro
Journal of Constructional Steel Research | Year: 2014

This study investigates the welding residual stress and distortion in T-joint welds under various mechanical boundary conditions. An experimentally calibrated and sequentially coupled thermal and mechanical 3D finite element (FE) model is developed, and Goldak's double ellipsoidal heat source model is implemented into the numerical model. The results show that the transverse residual stress, vertical displacement, angular distortion and transverse shrinkage depend significantly on the mechanical boundary conditions, and the influence on the longitudinal residual stress is not significant. Applying the clamped condition along the edges during the welding process and releasing it after the T-joint cools down to ambient temperature can significantly reduce the welding-induced geometric imperfections. © 2014 Elsevier Ltd. All rights reserved.

Wang G.,Xian Jiaotong University | Feng X.,China University of Petroleum - Beijing | Chu K.H.,Xian Jiaotong University
Journal of Cleaner Production | Year: 2013

Instability is a severe barrier to the successful development and evolution of industrial symbiosis systems. In this paper, a novel approach for stability analysis of industrial symbiosis systems is proposed. Two parameters (symbiosis profit and symbiosis cost) are defined on the basis of profit consideration. With the introduction of asymmetric distribution coefficient as a quantitative index, the distribution of symbiosis cost and symbiosis profit can be analyzed. An illustrative example demonstrates that the approach can be used to assess the stability of a hypothetical coal-based symbiosis system under different states. Specifically, the impact of changes in the system structure and external environment on the stability of the coal-based symbiosis system is investigated. The results confirm the practical applicability and effectiveness of the proposed approach. © 2012 Elsevier Ltd. All rights reserved.

Li T.,University of British Columbia | Zhang Y.,China University of Petroleum - Beijing | Grace J.R.,University of British Columbia | Bi X.,University of British Columbia
AIChE Journal | Year: 2010

Gas mixing in a tall narrow fluidized bed operated in the slugging fluidization regime is simulated with the aid of computational fluid dynamics. In the first part, a parametric study is conducted to investigate the influence of various parameters on the gas mixing. Among the parameters studied, the specularity coefficient for the partial-slip solid-phase wall boundary condition had the most significant effect on gas mixing. It was found that the solid-phase wall boundary condition needs to be specified with great care when gas mixing is modeled, with free slip, partial slip and no-slip wall boundary conditions giving substantial differences in the extent of gas back mixing. Axial and radial tracer concentration profiles for different operating conditions are generally in good agreement with experimental data from the literature. Detailed analyses of tracer back mixing are carried out in the second part. Two parameters, the tracer backflow fraction and overall gas backflow fraction, in addition to axial profiles of cross-sectional averaged tracer concentrations, are evaluated for different flow conditions. Qualitative trends are consistent with reported experimental findings. © 2010 American Institute of Chemical Engineers (AIChE).

Ding Y.,Xian Jiaotong University | Feng X.,China University of Petroleum - Beijing | Chu K.H.,Xian Jiaotong University
Journal of Cleaner Production | Year: 2011

Hydrogenation units are often operated at high pressure, requiring the use of compressors which are one of the most expensive chemical processing equipment. Optimizing a hydrogen network should therefore take into consideration not only purity and flowrate constraints but also pressure requirements. In this paper, based on the hydrogen surplus diagram approach, the average pressure profiles of hydrogen sources and sinks are proposed through the introduction of a system's minimum pressure drop Δp. Combined with the traditional purity profiles, whether a source can meet a sink either for hydrogen concentration or for pressure requirements can be determined intuitively. In cases where the pressure of a source is not sufficient for a sink, installing a hydrogen compressor or using another source with higher purity and pressure could be potential solutions. A cost equation is established to determine which of the two solutions is economically more viable. For different matching situations between sources and sinks, strategies for optimum placement of compression equipment within a given hydrogen network are proposed. A case study is used to illustrate the application and effectiveness of the proposed method. © 2010 Elsevier Ltd. All rights reserved.

HU W.,China National Petroleum Corporation | BAO J.,Petrochina | HU B.,China University of Petroleum - Beijing | HU B.,China National Petroleum Corporation
Petroleum Exploration and Development | Year: 2013

Major progress achieved in oil and gas exploration in terms of reserves, number of oil and gas fields and discovery of large oilfields were analyzed, trend and progress of global oil and gas exploration in eight aspects were elaborated, and four enlightenments for oil and gas exploration in China were proposed. The following aspects have become the shifting trend of oil and gas exploration around the world: from oil and gas reservoirs to source rocks, from trap to large area reservoir, from structural reservoirs and lithological reservoirs to unconventional continuous reservoirs, from structural highs to low sags and slopes, from conventional hydrocarbon to unconventional hydrocarbon, from middle depth layers to deep and ultra-deep layers, from shallow and middle depth sea to deep and ultra-deep sea, and from conventional zones to extreme zones. China should put more effort into the research on basic exploration theory and key techniques, attach more attention to the role of exploration engineering technology, seek the effective way for comprehensive exploration of oil and gas resources, and strengthen secondary exploration of old oil and gas fields. The major transformation in oil and gas exploration field and strategy will be beneficial to the discovery of more oil and gas fields in China. © 2013 Research Institute of Petroleum Exploration & Development, PetroChina.

Xu C.,Tsinghua University | Yu H.,China University of Petroleum - Beijing
Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science | Year: 2014

A compact retrieval system without moving parts was designed to lift and transport residuals in storage tanks to a higher elevation. The key component of the retrieval system, a curve reverse flow diverter (CRFD) with a vortex diode, was machined into a stainless steel disk to enable the entire system to be compact. The compact retrieval system can be installed in storage tanks through an existing narrow mounting hole. The pumping performance of the retrieval system was examined in terms of the effects of curve reverse flow diverter configurations, lift height, compression pressure, and suction pressure. Results reveal that the vortex diode with higher swirl resistance does not enhance thepumpingcapacity of the retrieval system. The pumping capacity of the retrieval system increased with increasingcompression pressure and decreased with increasing lift height and suction pressure. During the compression phase of the retrieval system, the empty factor qc was found to be linear with the Euler number Eu. The compact retrieval system can resolve the difficulty to retrieve high-Level radioactive residuals in storage tanks without radioactive leak and frequent maintenance. © IMechE 2014.

Li Y.,China National Offshore Oil Corporation | Fu N.,China National Offshore Oil Corporation | Zhang Z.,China University of Petroleum - Beijing
Shiyou Xuebao/Acta Petrolei Sinica | Year: 2013

The deepwater area of the northern South China Sea underwent multistage rifting in Paleogene and came into depression stage in Neogene. Lacustrine and transitional source rocks were formed mainly in the rifting period, while marine source rocks developed mainly in the depression stage. The transitional source rock is one of major source rocks in the deepwater area of the northern South China Sea. Oil and gas found in the northern South China Sea are mainly generated from transitional source rocks of Yacheng Formation and Enping Formation, while Zhuhai Formation marine source rock makes an important contribution to oil in the deepwater area of the Zhu II Depression. Natural gas in the Qiongdongnan deepwater area is a typical coal-type gas generated from Yacheng Formation humic source rock, but gas in the Zhu II Depression of the Pearl River Mouth Basin is neither a typical coal-type gas nor an oil-type gas, instead it is a transitional gas generated from Enping Formation humic-sapropel source rock.

Cai J.,Shanghai JiaoTong University | Cai J.,China University of Petroleum - Beijing | Wu W.,Shanghai JiaoTong University | Liu R.,Shanghai JiaoTong University
Renewable and Sustainable Energy Reviews | Year: 2014

Research interest in the conversion of lignocellulosic biomass into energy and fuels through the pyrolysis process has increased significantly in the last decade as the necessity for a renewable source of carbon has become more evident. For optimal design of pyrolysis reactors, an understanding of the pyrolysis kinetics of lignocellulosic biomass is of fundamental importance. The distributed activation energy model (DAEM) has been usually used to describe the pyrolysis kinetics of lignocellulosic biomass. In this review, we start with the derivation of the DAEM. After an overview of the activation energy distribution and frequency factor in the DAEM, we focus on the numerical calculation and parameter estimation methods of the DAEM. Finally, this review summarizes recent results published in the literature for the application of the DAEM to the pyrolysis kinetics of lignocellulosic biomass. © 2014 Elsevier Ltd.

Zhang Y.,University of Science and Technology Beijing | Pang X.,University of Science and Technology Beijing | Qu S.,University of Science and Technology Beijing | Li X.,China Petroleum Pipeline Engineering Corporation | And 2 more authors.
Corrosion Science | Year: 2012

The corrosion behaviour of X65 pipeline steel at various temperatures for different immersion time under low CO 2 partial pressure and supercritical CO 2 condition were investigated by weight loss measurements and surface analysis techniques. By comparing the characteristics of CO 2 corrosion product scale formed under experimental conditions and the variation rule of corrosion rate with temperature, the CO 2 corrosion mechanism under low partial pressure and supercritical condition was studied. To explain the big difference of corrosion rate between low CO 2 partial pressure and supercritical CO 2 condition, thermodynamic calculation of the solubility of CO 2 in H 2O were discussed. © 2012 Elsevier Ltd.

Yang J.,University of Queensland | Yuan P.,China University of Petroleum - Beijing | Chen H.-Y.,University of Queensland | Zou J.,University of Queensland | And 2 more authors.
Journal of Materials Chemistry | Year: 2012

Novel phosphorus (P) adsorbents with a high adsorption capacity (up to 2.272 mmol g -1) and excellent adsorption performance in a low P concentration range of 1 mg L -1 have been successfully developed. The material achieves up to 96% P removal within 30 min with an initial concentration of 1 mg L -1. The adsorbents are prepared using macroporous ordered silica foams (MOSF) as the host. After modification by lanthanum species (La-MOSF), the two sides of the silica layer (∼5 nm in thickness) are coated by two layers of lanthanum oxide each with a thickness of ∼2.3 nm, forming a unique sandwich-like wall structure. Due to the very large pore size of La-MOSF (∼100 nm), after P adsorption the formed LaPO 4 species are confined inside the pores without causing pore blocking, allowing for a high loading of lanthanum oxide and a high adsorption capacity. Moreover, the thin layer nature of lanthanum oxide facilitates the reaction between lanthanum oxide and phosphate ions, leading to the enhanced performance for the adsorption in low P concentration ranges. These rationally designed macroporous materials with outstanding performance have great potentials in water quality control and protection. © 2012 The Royal Society of Chemistry.

Hook M.,Uppsala University | Tang X.,China University of Petroleum - Beijing
Energy Policy | Year: 2013

Future scenarios with significant anthropogenic climate change also display large increases in world production of fossil fuels, the principal CO2 emission source. Meanwhile, fossil fuel depletion has also been identified as a future challenge. This chapter reviews the connection between these two issues and concludes that limits to availability of fossil fuels will set a limit for mankind's ability to affect the climate. However, this limit is unclear as various studies have reached quite different conclusions regarding future atmospheric CO2 concentrations caused by fossil fuel limitations. It is concluded that the current set of emission scenarios used by the IPCC and others is perforated by optimistic expectations on future fossil fuel production that are improbable or even unrealistic. The current situation, where climate models largely rely on emission scenarios detached from the reality of supply and its inherent problems are problematic. In fact, it may even mislead planners and politicians into making decisions that mitigate one problem but make the other one worse. It is important to understand that the fossil energy problem and the anthropogenic climate change problem are tightly connected and need to be treated as two interwoven challenges necessitating a holistic solution. © 2012 Elsevier Ltd.

Wu Z.,University of California at Berkeley | Wu Z.,China University of Petroleum - Beijing | Goel S.,University of California at Berkeley | Choi M.,University of California at Berkeley | And 2 more authors.
Journal of Catalysis | Year: 2014

Noble metal clusters (Pt, Pd, Rh, Ir, Re, and Ag) are selectively encapsulated within LTA voids via hydrothermal synthesis using metal precursors with ligands (NH3 for Pt and Ir; ethylenediamine for Pd, Rh, Re and Ag) that prevent their premature precipitation as colloidal oxyhydroxides. Such stability appears to be necessary and sufficient for successful encapsulation of cationic precursors during nucleation and growth of zeolite frameworks. Mean cluster diameters measured by titration of exposed metal atoms (H2 on Pt, Pd, Rh, Ir and Re; O2 on Ag; 1.1-1.8 nm) and by transmission electron microscopy (1.2-1.9 nm) were similar, indicating that cluster surfaces were clean and accessible to molecules used as titrants or reactants. Metal clusters were narrowly distributed in size and stable against sintering and coalescence during oxidative thermal treatments (573-873 K). Encapsulation selectivities were measured from turnover rates for reactions of small and large reactants, specifically hydrogenation of alkenes (ethene and isobutene) and oxidation of alkanols (methanol, ethanol, and isobutanol), which reflect the restricted access to encapsulated clusters by the larger molecules. These encapsulation selectivities, which reflect the ratio of metal surface areas within and outside LTA crystals ranged from 7.5 to 83 for all samples. Confinement within LTA crystals protects clusters from contact with thiophene and allows ethene hydrogenation to proceed at thiophene concentrations that fully suppressed reactivity for metal clusters dispersed on mesoporous SiO 2. These protocols provide a general strategy for encapsulating clusters within small-pore zeolite voids, for which post-synthesis exchange is infeasible. Their successful encapsulation protects such clusters from coalescence and growth and allows them to select reactants and reject poisons based on their molecular size. © 2014 Elsevier Inc. All rights reserved.

Zhang X.,Peking University | Zhang X.,China University of Petroleum - Beijing
Procedia Earth and Planetary Science | Year: 2011

Special elemental sulfurs formed by thermochemical sulfate reduction (TSR) are reported for the first time in the Upper Permian Changxing Formation and the Lower Triassic Feixianguan Formation, Northeastern Sichuan Basin, Southwest China. They occur mainly as single pellets with round morphology, and partly in semi or 'A pellets of 10 to 100 μm in diameter, or form interpenetrating grains. Most of them precipitate at the inner wall of the vugs, oomoldic or inter-granular pores of the dolomitic reservoirs. Petrogenetic sequence analysis demonstrates that they postdate the dolomite formation and cementation, while are prior to the late calcite and quartz cementation The sulfur develops restrictively in the section where pyrobitumen is found, namely in the paleo-oil window, which strongly supports that the crude oil/liquid hydrocarbon had been involved in the TSR. © 2011 Published by Elsevier Ltd.

Yin J.-P.,China University of Petroleum - Beijing
Natural Gas Geoscience | Year: 2014

In recent years, with the development of natural gas market, China's natural gas consumption increases rapidly. However, "gas shortage" has occurred frequently because of the lack of a perfect natural gas storage mechanism, which has highlighted the importance of constructing its natural gas storage system. In this field, the experience of U.S. and some European countries is worth learning, definitely. Firstly, this paper briefly introduced the current situation of China's natural gas supply and demand, as well as several storage methods of natural gas. And then, it analyzed the natural gas supply & demand, together with storage situation of the U.K, France, Germany, Italy, Spain, Ukraine and the U.S. At last, based on China's current situation of natural gas storage, the paper summarized the experience of these countries, which would enlighten us how to construct our own natural gas storage system.

Xu J.-H.,CAS Institute of Policy and Management | Fan Y.,CAS Institute of Policy and Management | Yu S.-M.,CAS Institute of Policy and Management | Yu S.-M.,China University of Petroleum - Beijing
Energy Economics | Year: 2014

In the 11th Five-Year Plan (FYP) (2005-2010), the Chinese Government initiated a series of energy-saving and emission reduction policies in many key fields in response to environmental pollution and climate change. This paper quantitatively evaluates the performance of energy conservation and CO2 emission reduction in this period, the impact of these policies and potentials, by integrating the contributions of energy conversion efficiency and energy utilization efficiency improvement, industrial restructuring, fuel mix shift and renewable energy development in a unified framework, as a first attempt to introduce energy conversion efficiency improvement into a decomposition approach. Comprehensive and specific policies are summarized as a policy list to be investigated. The results show that energy intensity and conversion efficiency effects were mainly responsible for driving down energy consumption, by 637.4Mtce and 85.4Mtce respectively, and they reduced CO2 emissions by 1345.3Mt and 243.8Mt respectively due to a significant improvement in the 11th FYP period. Most of the contributions made by the conversion efficiency effect (94%) come from thermal power generation, and the emission coefficient effect reduced CO2 emissions by 17.4Mt through developing renewable energy. Economic growth is still the biggest driver of energy consumption and increasing emissions, while industrial restructuring and fuel mix shift effects contributed relatively little. Developing renewable energy and promoting economic restructuring to limit the increase of energy-intensive sectors are still the main challenges and the next policy focus to achieve the targets for energy saving and carbon emission reduction in the 12th Five-Year Plan. © 2014 Elsevier B.V.

Yao Y.,Nankai University | Wang Z.,Tianjin Normal University | Zhao S.,Nankai University | Wang D.,Nankai University | And 2 more authors.
Catalysis Today | Year: 2014

A cross-linked sulfonated polyethersulfone supported Ru nanoparticle catalyst was prepared for highly hydrogenation of levulinic acid (LA) into γ-valerolactone (GVL) at mild conditions (3.0 MPa H2 and 70 °C) in aqueous solution. X-ray diffraction (XRD) and transmission electron microscopy (TEM) characterizations show the formation of highly dispersed small (∼3 nm) Ru clusters on the surface of polyethersulfone. Infrared spectroscopy (IR) and acid-base titration indicate the presence of sulfonic groups without the influence of the deposition of Ru species. Polyethersulfone consisted of cross-linked electron -withdrawing group SO2, maintained its intrinsic thermal stability during the hydrogenating reaction process, and its swelling property promoted the adsorption of LA in aqueous solution. The synchronization of sulfonic groups as active sites for esterification process and metal sites for hydrogenation promoted the hydrogenation reactivity. © 2014 Elsevier B.V.

Sun X.,China University of Petroleum - Beijing
Petroleum Refinery Engineering | Year: 2013

The selective solvent deasphalting experiment for vacuum residue (VR) from Canadian tar sand bitumen was performed and the results showed that the viscosity of HDAO was decreased by about 70% at a higher yield of DAO. The viscosity of HDAO at 100 °C was reduced to 1 366 mPa · s from 4 187 mPa · s after HDAO was treated by visbreaking process under the conditions of 410 °C reaction temperature and 25 minutes reaction time. The viscosity reduction is above 67% and the stability of visbreaking product met specifications of Grade 1. When the diesel oil, vacuum gas oil (VGO) and visbreaker oil were blended with a little amount of diluent was required, only 14% and 6% diluent were needed to be added respectively at 15 °C (in summer) and 8 °C (in winter) for the oil to meet the requirements of pipeline transportation in Canada.

Liu W.,China University of Petroleum - Beijing | Jin Y.,Tianjin University | Tan X.,University of Alberta | Yeung A.,University of Alberta
Fuel | Year: 2011

The abilities of three ionic surfactants - sodium methylnaphthalene sulfonate (SMNS), sodium dodecyl sulfate (SDS), and cetyl trimethylammonium bromide (CTAB) - to alter the wettability of bitumen-treated glass surfaces was examined. Surface wettability was characterized by contact angles, and all measurements were carried out under alkaline conditions by having sodium carbonate (Na2CO3) dissolved in the aqueous phase. It was found that Na2CO3 alone could slightly increase the hydrophilcity of bitumen-treated glass surfaces. With surfactants added to the system, it was demonstrated that SMNS and SDS (both anionic surfactants) were much more effective in enhancing the water wettability of bitumen-treated glass in comparison to CTAB (a cationic surfactant). X-ray photoelectron spectroscopy (XPS) analyses were also conducted to determine the functional groups and relative mass concentrations of various elements on the glass substrates. Based on these results, we speculate that most or all of the adsorbed hydrocarbon material could be removed from a glass substrate through synergistic effects between sodium carbonate, which provides the alkaline condition, and anionic surfactants, which likely interacted with adsorbed cationic materials. This resulted in dramatic alteration in the wettability of bitumen-treated glass surfaces - from oil-wet to water-wet. © 2011 Elsevier Ltd. All rights reserved.

Guo Y.,Petrochina | Liu J.,Petrochina | Yang H.,Petrochina | Liu Z.,China University of Petroleum - Beijing | And 4 more authors.
Shiyou Kantan Yu Kaifa/Petroleum Exploration and Development | Year: 2012

By analyzing the hydrocarbon accumulation conditions under the guideline of sequence stratigraphy, the hydrocarbon accumulation mechanism in the low permeability, tight reservoirs of the Yanchang Formation in the Ordos Basin is studied from the perspective of pore evolution, and the hydrocarbon accumulation evolution models are concluded. The low permeability, tight reservoirs of the Yanchang Formation are distributed within the range of good hydrocarbon source rocks. The reservoir sand-bodies are dominated by lacustrine gravity flow deposits and delta front deposits. In the early period when hydrocarbons are accumulated in the Yanchang Formation, the reservoirs are characterized by high porosity and high permeability. The oil and gas generated in the period are accumulated normally under the effect of buoyancy. In the middle-late period, the reservoirs have experienced continuous compression. The petroleum generated in the late period, the major hydrocarbon generation period, migrates and accumulates by infiltration along the previously remained paths under the effect of buoyancy and pressure difference between the source rocks and the reservoirs. When the reservoirs become tight, oil and gas stop migration. From the Late Jurassic to the middle period of the Early Cretaceous, oil and gas widely charge the high porosity sandstones near the source rocks when they migrate from the center of the lacustrine basin to the borders. In the late period of the Early Cretaceous, the diagenesis of sandstone reservoirs is enhanced, making the reservoirs tight. After the Late Cretaceous, the present low permeability tight lithologic reservoirs are formed due to the compressing and uplifing movement of the structure which dips down in the west and tilts up in the east.

Quality function deployment (QFD) is a customer-driven approach for product design and development. A QFD analysis process includes a series of subprocesses, such as determination of the importance of customer requirements (CRs), the correlation among engineering characteristics (ECs), and the relationship between CRs and ECs. Usually more than group of one decision makers are involved in the subprocesses to make the decision. In most decision making problems, they often provide their evaluation information in the linguistic form. Moreover, because of different knowledge, background, and discrimination ability, decision makers may express their linguistic preferences in multigranularity linguistic information. Therefore, an effective approach to deal with the multi-granularity linguistic information in QFD analysis process is highly needed. In this study, the QFD methodology is extended with 2-tuple linguistic representation model under multi-granularity linguistic environment. The extended QFD methodology can cope with multi-granularity linguistic evaluation information and avoid the loss of information. The applicability of the proposed approach is demonstrated with a numerical example. © 2012 Ming Li.

Li M.,China University of Petroleum - Beijing
Mathematical Problems in Engineering | Year: 2012

Axiomatic design (AD) provides a framework to describe design objects and a set of axioms to evaluate relations between intended functions and means by which they are achieved. It has been extended to evaluate alternatives in engineering under fuzzy environment. With respect to multiple criteria group decision making (MCDM) with incomplete weight information under fuzzy linguistic environment, a new method is proposed. In the method, the fuzzy axiomatic design based on triangle representation model is used to aggregate the linguistic evaluating information. In order to get the weight vector of the criteria, we establish a nonlinear optimization model based on the basic ideal of fuzzy axiomatic design (FAD), by which the criteria weights can be determined. It is based on the concept that the optimal alternative should have the least weighted information content. Then, the weighted information content is derived by summing weighted information content for each criterion. The alternative that has the least total weighted information content is the best. Finally, a numerical example is used to illustrate the availability of the proposed method. © 2012 Ming Li.

Fan Z.-J.,Harbin Engineering University | Yan J.,Harbin Engineering University | Wei T.,Harbin Engineering University | Ning G.-Q.,China University of Petroleum - Beijing | And 5 more authors.
ACS Nano | Year: 2011

We report on the fabrication of 3D carbonaceous material composed of 1D carbon nanofibers (CNF) grown on 2D graphene sheets (GNS) via a CVD approach in a fluidized bed reactor. Nanographene-constructed carbon nanofibers contain many cavities, open tips, and graphene platelets with edges exposed, providing more extra space for Li+ storage. More interestingly, nanochannels consisting of graphene platelets arrange almost perpendicularly to the fiber axis, which is favorable for lithium ion diffusion from different orientations. In addition, 3D interconnected architectures facilitate the collection and transport of electrons during the cycling process. As a result, the CNF/GNS hybrid material shows high reversible capacity (667 mAh/g), high-rate performance, and cycling stability, which is superior to those of pure graphene, natural graphite, and carbon nanotubes. The simple CVD approach offers a new pathway for large-scale production of novel hybrid carbon materials for energy storage. © 2011 American Chemical Society.

Yu C.,China University of Petroleum - Beijing | Wong T.N.,University of Hong Kong
Journal of Intelligent Manufacturing | Year: 2015

Supplier selection an important problem in supply chain management (SCM), since the performances of suppliers determine the competitiveness of the SCM. It is practical for the purchasing company to procure multiple products simultaneously. Synergy effect may exist between products in multi-product supplier selection process, and affect the final choice of suppliers. It is advantageous for the purchasing company to take into account the synergy effect between products to reduce cost and improve efficiency. On the other hand, suppliers need to consider the synergy effect between products to increase the chance of winning bids. Nevertheless, supplier selection involves complex decision making processes regarding supplier evaluation, selection and order fulfillment, it is difficult to fully incorporate the synergy effect between products in the case of multi-product supplier selection. Most of existing research only deal with supplier selection involving the acquisition of one product, or they assume that the multiple required products are independent. They are not sufficient to incorporate the synergy effect between products for multi-product supplier selection. This paper presents a product bundle determination model which can determine the synergy effect between products, group products based on the synergy effect between products, and determine the preferred product bundles of the purchasing company. This model can help the decision maker to make right decision in multi-product supplier selection process. Illustrative examples are conducted to demonstrate the functioning of the proposed product bundle determination model and its application in multi-product supplier selection process. © 2013, Springer Science+Business Media New York.

Yu C.,China University of Petroleum - Beijing | Yu C.,University of Hong Kong | Wong T.N.,University of Hong Kong
Expert Systems with Applications | Year: 2015

Supplier selection is an important problem in supply chain management (SCM), and has attracted the attention of many researchers. Tremendous effort has been spent on the development of agent-based systems to automate supplier selection negotiation process in SCM applications. In this kind of multi-agent system (MAS), software agents are established to represent various parties and functions involving in the supplier selection negotiation process. Most of current systems only deal with relatively simple negotiations involving the acquisition of one product, they are not sufficient to support complex negotiations involving multiple products with synergy effect. However, in practice, it is common for a purchasing company to procure multiple products simultaneously, and the synergy effects that exist between products could affect the final choice of cooperative suppliers. This paper presents an agent-based negotiation model to automate the supplier selection process involving a bundle of products with synergy effect. A MAS is established to realize the proposed negotiation model for multi-product supplier selection. Furthermore, the negotiation proposal, negotiation protocol, negotiation strategies, and decision making methods involving in the negotiation model are elaborated for the multi-product supplier selection environment. Through the proposed negotiation model, the purchasing company and suppliers can reach agreements on the details of products simultaneously and exploit the synergy effect between products. Finally, illustrative examples are conducted to demonstrate the function and effectiveness of the negotiation model for multi-product supplier selection. © 2014 Elsevier Ltd. All rights reserved.

Hou Q.,Peking University | Hou Q.,Petrochina | Zhao Z.,Petrochina | Huang Z.,China University of Petroleum - Beijing
Petroleum Exploration and Development | Year: 2011

To further understand the accumulation mechanism and distribution rules of deep basin oil, the laboratory physical simulation experiment is conducted for water-sealed oil in sand columns of different grain sizes, and the water-sealed oil mechanism and the accumulation threshold of deep basin oil are analyzed. Stable deep basin oil can be formed under laboratory conditions. The accumulation threshold of deep basin oil mainly depends on the pore throat radius of oil-bearing sand layer as well as the oil/water interfacial tension and strata dip under such conditions. The accumulation threshold and its main controlling factors of the deep basin reservoir in the Fuyang oil layer are studied, and the prediction model of deep basin reservoir boundaries is established: the porosity is less than 11%, the permeability is less than 1×10 -3 μm 2, the largest pore throat radius is less than 6.2 μm, and the burial depth is 1800-2100 m, located at the lower positions of syncline or slope, and good source rock in Qing-1 Member is developed, with obviously abnormal pressure. Three " sweet spot" areas favorable for deep basin oil in the Songliao Basin are determined, namely south Liangjing area, east Haituozi area, and west Qian'an area. The predicted deep basin oil potential in these three areas is 0.317 billion tons. The total proved resources of deep basin oil in the Songliao Basin are 1.575 billion tons, with good exploration potential. © 2011 Research Institute of Petroleum Exploration & Development, PetroChina.

Li M.,China University of Petroleum - Beijing | Li M.,Beihang University | Liu L.,Beihang University | Li C.-B.,Shenyang University of Technology
Expert Systems with Applications | Year: 2011

Since organizational tacit knowledge such as know-how and experiences usually resides in the owner's brain, consulting the expert is an effective and efficient way to utilize this type of knowledge. However, users are no longer able to effectively find the appropriate experts in the knowledge management system due to the complexity and diversity of the expertise and the knowledge needs. In this paper, an approach to expert recommendation is proposed to assist the user to find the required experts. The method adopts the fuzzy linguistic method to construct the expert profile, that is, to model expert's expertise. In addition, the fuzzy text classifier is used to get the relevant degree of the document to each knowledge area when the document is registered, which is the base of the following user profile construction. Then, the user profile consisting of the time and the relevance factors of the rated documents is constructed to derive the overall knowledge needs level of the user. Consequently, the expert that fulfills the knowledge needs most is recommended based on the similarity between the derived expert profile and the user profile. The developed prototype system, "knowledge management system in aircraft industry company", is introduced and the experimental results show the proposed approach is feasible and effective. © 2011 Elsevier Ltd. All rights reserved.

Fan Z.,Harbin Engineering University | Yan J.,Harbin Engineering University | Ning G.,China University of Petroleum - Beijing | Wei T.,Harbin Engineering University | And 2 more authors.
Carbon | Year: 2013

Porous graphene obtained by chemical vapor deposition (CVD) using porous MgO sheets as template is demonstrated to exhibit a high reversible capacity (1723 mAh g-1), excellent high-rate capability and cycling stability for Li-ion batteries. The simple CVD approach offers a new way for large-scale production of porous graphene materials for energy storage. © 2013 Elsevier Ltd. All rights reserved.

Kang W.,China University of Petroleum - East China | Kang W.,China University of Petroleum - Beijing | Guo L.,China University of Petroleum - East China | Fan H.,China University of Petroleum - East China | And 2 more authors.
Journal of Petroleum Science and Engineering | Year: 2012

The oil-water separation and dispersed phase droplet or flocculate droplet or flocculate size variation in the heavy oil emulsion were analyzed by using the Turbiscan Lab stability analyzer. The demulsification process of the heavy oil emulsion was described as well. The results indicated that three-phase separation took place slowly in the heavy oil emulsion and the emulsion middle layer finally formed between the oil phase and water phase, and the demulsification was mainly caused by the dispersed phase droplets sedimentation. After the chemical demulsifier was added into the emulsion, two-phase separation took place quickly, the emulsion stability data accurately conformed to the emulsion stability model based on the two-phase separation. Comparing the characteristic of the demulsification process of the heavy oil emulsion before and after the addition of demulsifier, it indicated that the coalescence of the dispersed phase droplets is the controlling factor and crucial step of the demulsification. © 2011 Elsevier B.V.

Li T.,U.S. National Energy Technology Laboratory | Li T.,URS Corporation | Zhang Y.,China University of Petroleum - Beijing
Chemical Engineering Science | Year: 2013

Pseudo-two dimensional (pseudo-2D) fluidized beds, for which the thickness of the system is much smaller than the other two dimensions, are widely used to perform fundamental studies on bubble behavior, solids mixing, or clustering phenomenon in different gas-solids fluidization systems. The abundant data from such experimental systems are very useful for numerical model development and validation. However, it has been reported that two-dimensional (2D) computational fluid dynamic (CFD) simulations of pseudo-2D gas-solids fluidized beds usually predict poor quantitative agreement with the experimental data, especially for the solids velocity field. In this paper, a new model is proposed to improve the 2D numerical simulations of pseudo-2D gas-solids fluidized beds by properly accounting for the frictional effect of the front and back walls. Two previously reported pseudo-2D experimental systems were simulated with this model. Compared to the traditional 2D simulations, significant improvements in the numerical predictions have been observed and the predicted results are in better agreement with the available experimental data. © 2013 Elsevier Ltd.

Jiang H.-Q.,China University of Petroleum - Beijing
Zhongguo Shiyou Daxue Xuebao (Ziran Kexue Ban)/Journal of China University of Petroleum (Edition of Natural Science) | Year: 2013

Channels with very high permeability can be developed in oil reservoirs at ultra-high water cut stage. In this study, different types of channeling problems were identified and described according to the geological characteristics of the reservoir and the dynamics of channel forming. An early warning and discriminating model for the detection of channeling was proposed based on the theory of early warning and the principles of reservoir engineering. The model can be used to identify various channels and their distribution in the reservoir, and the channels are differentiated as severely, normally and less-developed according to their flow conductivities. Water shut-off and conformance control methods were proposed for different types of the channels and their performance and application conditions were assessed using a numerical simulation model. The results show that, after the water shut-off or conformance control treatments, the selection of the subsequent or alternative flooding mode is very important to enhance the effectiveness of the channel blockage and control technique. Finally, a differentiated and fine adjustment strategy for controlling the channeling problems was proposed, which can be used for mature oil reservoirs at ultra-high water cut stage.

Li X.,China National Offshore Oil Corporation | Li H.,China University of Petroleum - Beijing
Journal of Petroleum Science and Engineering | Year: 2013

In the traditional data-driven data mining process, there are huge gaps between the efficient algorithms and intelligent tools as well as the invalidity of knowledge which is obtained by traditional data-driven data mining. Meanwhile, each data in the earth science field contains a solid physical meaning. If there is no corresponding domain knowledge involved in the mining process, the information explored by data-driven data mining will be lack of practicability and not able to effectively solve problems in the earth science area. Therefore, the task-driven data mining is proposed. Additionally, task-driven data mining concepts and principles are elaborated with the help of data mining concepts and techniques. It is divided into seven elements such as data warehousing, data preprocessing, feature subset selection, modeling, model evaluation, model updating and model release. Those constitute a cyclic and iterative process until a predictive model which is capable of effectively achieving the objectives. In order to accurately identify complex lithologies, this paper puts forward a self-organizing feature map neural network based on the task-driven data mining. With the attempt to solve the problem of complex reservoir identification, the decision tree and support vector machine are used to build the fluid predictive model. Meanwhile, the optimization algorithms inclusive of genetic, grid and quadratic are adopted to optimize the important parameters of C-SVC and υ-SVC, such as C, υ and γ, so as to improve the classification performance and generalization ability of the predictive model of support vector machine. The conclusions of fine interpretation are compared with the core analysis data and well testing data. As a result, the accuracy of the complex lithology and reservoir identification is more than 90%. Finally, the paper puts forward the understandings, development prospects and key challenges of task-driven data mining facing. © 2013 Elsevier B.V.

Liu K.,Renmin University of China | Li Y.,Renmin University of China | Zheng X.,Renmin University of China | Liu W.,Renmin University of China | And 2 more authors.
Tetrahedron | Year: 2012

A general and practical method for the synthesis of α-ester-β- keto peroxides has been achieved by iron-catalyzed three-component reactions of alkenes, aldehydes, and TBHP. A wide variety of functionalized organic peroxides were synthesized efficiently and selectively. © 2012 Elsevier Ltd. All rights reserved.

Zhang X.,Nanjing University | Zhang X.,China University of Petroleum - Beijing | Lin C.-M.,Nanjing University | Dalrymple R.W.,Queens University | And 2 more authors.
Bulletin of the Geological Society of America | Year: 2014

Filling of the modern coastal-zone portion of the Qiantang River (QR) in eastern China was initiated by marine inundation during the transgression after the Last GlacialMaximum and has continued during the Holocene sea-levelstillstand. The early part of the fillis transgressive in character, while the younger part is regressive. This paper deals with the sedimentary facies, surfaces, architecture, and depositionalmodelof the QR incised-valley fillbased on the detailed analysis of the newly drilled core SE2 and its correlation with more than 800 boreholes. The incised-valley deposits are grouped into five stacked facies: amalgamated channel, floodplain and channel, paleo-estuary, offshore shallow marine, and present-day estuary. A paleo-estuary facies had never been identified before, making these observations novel. This facies is characterized by a sedimentary succession and sediment distribution that are distinct from those of the present-day estuary because of a change in sediment supply from the sea floor beyond the estuary mouth. It also contains large numbers of tidal-channelsand bodies that are significant reservoirs for shallow biogenic gas. Since the last glaciation, there have been three stages in the development of the QR incised-valley fillsequence: (1) a formation stage associated with sea-levelfall, (2) a filling stage during the early transgression with rapid sea-levelrise, and (3) a burialstage corresponding to the slowing of sea-levelrise and the onset of progradation. This fillconsists of four longitudinalsegments, each of which is distinguished by a distinct stratigraphic succession and different degrees of marine and fluvialinfluence. The basalerosion surface and sidewalls of the incised valley, the top of stiff clay on the interfluves, and the top of falling-stage fluvial-terrace deposits compose the sequence boundary. The initialflooding surface and maximum flooding surface are located within the amalgamated channeland offshore shallow-marine sediments, respectively. These observations indicate that: (1) relative sea-levelchanges determine the stratalstacking patterns, but localenvironmentalfactors, such as physicalprocesses, accommodation, sediment supply, and coastalconfiguration controlthe nature of the facies, surfaces, and sediment-distribution patterns; and (2) the tripartite facies organization and wave ravinement surfaces typifying wavedominated or mixed-energy (wave and tide) incised-valley fills are absent in the macrotidalQR succession, and the tidalravinement and erosion surfaces of the macrotidalQR incised valley are more extensive and numerous than those of the wave-dominated or mixed-energy succession. © 2014 Geological Society of America.

Sun X.,China University of Petroleum - Beijing
Petroleum Processing and Petrochemicals | Year: 2014

The hydrocarbon and non-hydrocarbon compositions of coker diesel of Xinjiang Fengcheng vacu-um residuum (FCVR) and supercritical fluid extraction narrow fractions (SFEF) were analyzed by GC, GC-MS, GC-SCD and GC-NCD methods. The results show that the composition and distribution of hydrocarbon and non-hydrocarbon are affected directly by properties of feeds. With the fractions getting heavier, the content of sulfur and nitrogen compounds gets higher, and the types of hydrocarbon and non-hydrocarbon compounds become more complex. The content of saturated hydrocarbon in coker diesels is higher than that of aromatics and so as the cycloalkanes compared with that of alkane. The contents of aro- matics in diesels increase and the saturated hydrocarbon is just the opposite with the fractions getting heavier. Sulfides in diesels are mainly benzothiophenes and dibenzothiophenes, while alkaline quinolines and benzoquinolines, neutral indoles and carbazoles are main N-containing components.

Yao Y.,China University of Petroleum - Beijing
Special Topics and Reviews in Porous Media | Year: 2010

The fundamental theory of fluid flow in porous media should be consistent with material balance. However, the quadratic gradient term in the nonlinear diffusion equations is usually neglected, according to the slightly compressible fluid assumption, during the process of linearization, which will lead to errors for large time values. In this paper, fractal geometry theory is used to combine with seepage flow mechanics to establish the nonlinear diffusion equation of fluids flow in fractal reservoirs, including the quadratic gradient term. A method is used to scale the fractal properties of a fractal reservoir by double parameters (df, ds) and to describe the generalized flow characteristics of the nonlinear diffusion equation by four parameters, α, ds, df , and cD. A nonlinear flow model for fractal medium is presented, and all terms in the nonlinear diffusion equation are retained. A methodology to solve the diffusion equation with the quadratic gradient term is proposed. The solution technique, which is based on Laplace transform andWeber transform, is well suited for solving the flow model of fractal mediums. After analyzing the typical curves, we find that the relative error caused by the effects of the quadratic gradient term on pressure may amount to several to tens of percent in fractal reservoir flow. Especially for live oil and low-permeability reservoirs, linearization by neglecting the quadratic gradient term may generate inaccurate values for large time values. © 2010 by Begell House, Inc.

Li Y.,China University of Petroleum - Beijing
Petroleum Refinery Engineering | Year: 2014

In producing condensate gas reservoirs "gas wet" method has recently been focused in researches to solve formation damages caused by retrograde condensate blocking and caused by liquid phase trapping in low- and ultra-low-permeability reservoirs. The wettability change of rock surface results in a change in methane adsorption on rock surface that cannot be ignored. To solve this problem, a study on the changes of adsorptive power of solid surfaces to methane, carbon dioxide, water and nitrogen is conducted using "ab initio quantum chemistry method" (HF-3-21G). This study is based on the proposed surface atom cluster model of rocks that are liquid wet and gas wet. The study shows that after gas wettability reversal, adsorptive powers of the four gases decrease, and the molecules of these gases on the liquid wet and gas wet rock surfaces are both in monolayer molecule physical adsorption.

Yan J.,China University of Petroleum - Beijing
Lecture Notes in Electrical Engineering | Year: 2013

The advantages of tree routing and distributed addresses assignment mechanisms in ZigBee wireless sensor networks are its simplicity and less resource consumption. However, they bring some constraints on the network configuration and may reduce the network connectivity. This will cause the expected network operations and functionality to be unreached and also waste the corresponding deployment costs of the isolated sensor devices with failed joining. This paper proposed an efficient connection shifting mechanism to reduce the isolated device and improve the overall network connectivity. © 2013 Springer-Verlag London.

Shuai J.,China University of Petroleum - Beijing
Zhongguo Shiyou Daxue Xuebao (Ziran Kexue Ban)/Journal of China University of Petroleum (Edition of Natural Science) | Year: 2013

The R-curve as well as fracture toughness and tearing module were tested for X65 and X80 steel using multi-specimen method, in which the characteristic parameters were J-integral and CTOD. Plastic hinge model and η factor method were compared. The results show that the test result of plastic hinge model is similar to that of η factor method based on load-crack mouth displacement curves, but has a relative large difference when compared with the test result of η factor method based on load-load line displacement curves. For X65 as mid strength pipeline steel, R curves by plastic hinge model and η factor method based on load-crack mouth displacement curves and load-load line displacement curves, are relatively consistent. However, for X80 as high strength pipeline steel, R curves, especially δ-R curves by the three methods, have a large dispersion. The tearing modulus based on the R curve tend to be a constant, which represents the steady propagation characteristics of crack.

Xiao L.-Z.,China University of Petroleum - Beijing
Zhongguo Shiyou Daxue Xuebao (Ziran Kexue Ban)/Journal of China University of Petroleum (Edition of Natural Science) | Year: 2013

The design of nuclear magnetic resonance (NMR) system in downhole extreme conditions was briefly summarized. The extreme conditions here include environments with high temperature (up to 175°C) and high pressure (up to 68.95 MPa) in a well bore, very restricted space for system size, measurements done in moving conditions, sample outside of the probe with low magnetic field and low signal-to-noise ratio (SNR). NMR systems in downhole extreme conditions are very different from the conventional ones, so the probe and control systems require special consideration. Noise reduction, data processing and interpretation are equally important. The key issues of design and implementation of downhole NMR systems, including design of components of the NMR system and signal flow, design and implementation of probe, monitoring and control system, noise reduction methods and design and implementation of data acquisition and processing software, were discussed. The NMR system proposed and designed was delivered to engineering and application stage, and improved high end instrumentation and technology for China petroleum industry.

Zhang J.,China University of Petroleum - Beijing | Zhang J.,University of Illinois at Urbana - Champaign | Zhang Y.,University of Illinois at Urbana - Champaign
Energy and Fuels | Year: 2014

In this paper, hydrothermal liquefaction (HTL) of microalgae Chlorella pyrenoidosa was conducted for biocrude oil production. The ethanol-water co-solvent was introduced to take advantage of the special properties of supercritical ethanol and hot compressed water. The effects of the ethanol/water mass ratio (R) on the product distribution and characterization were discussed. The co-solvent showed better performance over any constituent mono-solvent, indicating synergistic effects of ethanol and water. The highest biocrude oil yield of 57.3% and the lowest solid residue yield of 9.4% were achieved at R = 5:2. The loading factor was considered as another influencing factor under supercritical conditions. Furthermore, potential reaction pathways for major biomacromolecule monomers in the ethanol-water co-solvent were also proposed on the basis of the gas chromatography-mass spectrometry (GC-MS) analysis of the liquid products. © 2014 American Chemical Society.

Zhang H.,Qinzhou University | Zhang H.,Guangxi University | Dong M.,University of Calgary | Zhao S.,China University of Petroleum - Beijing
Energy and Fuels | Year: 2012

The effect of the surfactant, NaOH, and polymer and the interactions between them on the heavy oil/water interface are unveiled by studying the dynamic interfacial tension (IFT), minimal transient IFT, and total organic carbon (TOC) and analyzing the phenomenon during the measurement of IFT of heavy oil/different alkaline systems, including alkaline (A), alkaline-surfactant (AS), alkaline-polymer (AP), and alkaline-surfactant-polymer (ASP). The results show that there exists a minimum transient IFT. There is an optimal composition to achieve the minimal IFT with varying NaOH concentrations in 0.018-0.8 wt %. For different chemical solutions, the optimal composition is different. Adding polymer affects the IFT by influencing the diffusion of species to or from the interface. Despite polymer addition, adding surfactant will increase the IFT at a lower alkaline concentration because of its competitive adsorption with OH - and reduce the IFT at a higher alkaline concentration because of its synergistic effect. The synergy between the surfactant and alkaline is turned out as follows: NaOH reacts with the polar components in the oil phase to produce ionized surface-active species; then the IFT is reduced; and the oil drop is prolonged. Surfactant accelerates the diffusion of ionized species from the interface to the bulk phase, and then the polar components underneath it are exposed to NaOH; therefore, the reaction between NaOH and polar oil components can proceed to further reduce the IFT. The contraction of the oil drop after surface-active species departed can be explained reasonably by considering the influence of the composition and structure of heavy oil. © 2012 American Chemical Society.

Chen M.,China University of Petroleum - Beijing
Zhongguo Shiyou Daxue Xuebao (Ziran Kexue Ban)/Journal of China University of Petroleum (Edition of Natural Science) | Year: 2013

A three-dimensional model for reactivation and re-orientation of hydraulic fractures in shale gas reservoir was established based on the theory of rock fracture mechanics. The re-orientation of fractures was considered as a continuous propagation process under discontinuous normal stress. Important factors and mechanical characteristics that affect fracture's geometry were studied in real cases. The results show that, in the direction of main fracture propagation, fracture width dramatically narrows after re-orientation when high horizontal differential stress is subjected. Higher pump rate and higher viscosity of the fracture fluid can generate a wider fracture because higher residual energy is provided after the re-orientation. When the initial angle between hydraulic and natural fractures nears to 30°, the hydraulic fracture tends to re-orientation more easily along the natural fractures. The propagation of the hydraulic fracture after its re-orientation will deviate from the maximum horizontal stress direction, resulting in shorter fracture length and smaller volume since more energy was lost in the re-orientation process. After the re-orientation, the hydraulic fracture can become a complicated fracture network with two to three modes.

Zhang G.-Q.,China University of Petroleum - Beijing
Zhongguo Shiyou Daxue Xuebao (Ziran Kexue Ban)/Journal of China University of Petroleum (Edition of Natural Science) | Year: 2013

Three-dimensional elasto-plastic models based on finite element method were developed for studying wellbore stability during branch well drilling, in which a mechanical system incorporating rock formation, cement sheath, casing and branch junction was considered. In the models, cement, rock formation and casing were treated as different materials with a plastic feature. Model transformation was established for stress anisotropic formations to maintain the same geometry for various branch orientations and avoid the errors caused by differential geometry model. The influence of branch orientation on wellbore stability during branch drilling was analyzed using the elasto-plastic finite element simulation. The results indicate that, when the branch azimuth angle is less than 15°, the maximum equivalent stress of the formation and cement sheath appears on the main wellbore system, which is favorable to the stability of branch wellbores. When the branch azimuth angle is greater than 75°, the maximum stress will appear on the branch wellbore, which may cause stability problems of the branch wellbores. To reduce deformation around the opening of the casing, the branch orientation should be very close to the direction of the maximum horizontal stress. Failure of the cement sheath in the main wellbore may cause problems during branch drilling, especially when the branch azimuth angle is greater than 30°. Small branch azimuth angle should be used in terms of the distribution of equivalent stress, casing deformation and cement's plastic deformation. Azimuth angle range of 50°-80° should also be avoided in order to ensure the stability of the wellbore.

Tong H.,China University of Petroleum - Beijing
Petroleum Science | Year: 2012

Fault formation and evolution in the presence of multiple pre-existing weaknesses has not been investigated extensively in rift basins. The fault systems of Weixinan Sag, Beibuwan Basin of China, which is fully covered with high-precision 3-D seismic data and is rich in oil-gas resources, have been successfully reproduced by sandbox modeling in this study with inclusion of multiple preexisting weaknesses in the experimental model. The basic characteristics of fault formation and evolution revealed by sandbox modeling are as follows. 1) Weakness-reactivation faults and weakness-related faults are formed much earlier than the distant-weakness faults (faults far away from and with little or no relationship to the weakness). 2) Weakness-reactivation faults and weakness-related faults develop mainly along or parallel to a pre-existing weakness, while distant-weakness faults develop nearly perpendicular to the extension direction. A complicated fault system can be formed in a fixed direction of extension with the existence of multiple pre-existing weaknesses, and the complicated fault system in the Weixinan Sag formed gradually in a nearly N-S direction with multiple pre-existing weaknesses. 3) The increase in the length and number of faults is closely tied to the nature of pre-existing weaknesses. The sandbox model may provide a new clue to detailed fault system research for oil and gas exploration in rift basins. © 2012 China University of Petroleum (Beijing) and Springer-Verlag Berlin Heidelberg.

Wang Q.,Harbin Engineering University | Yan J.,Harbin Engineering University | Wang Y.,Harbin Engineering University | Ning G.,China University of Petroleum - Beijing | And 5 more authors.
Carbon | Year: 2013

A carbon material consisting of hollow carbon spheres anchored on the surface of carbon nanotubes (CNT-HCS) has been synthesized by an easy chemical vapor deposition process using a CNT-MnO2 hybrid as template. An electrode made of this material exhibits a maximum specific capacitance of 201.5 F g-1 at 0.5 A g-1 and excellent rate performance (69% retention ratio at 20 A g-1). It has impressive cycling stability with 90% initial capacitance retained after 5000 cycles at 5 A g-1 in 6 mol L-1 KOH. Symmetric supercapacitors based on CNT-HCS achieve a maximum energy density of 11.3 W h kg-1 and power density of 11.8 kW kg-1 operated within a wide potential range of 0-1.6 V in 1.0 mol L-1 Na2SO4 solution. © 2012 Elsevier Ltd. All rights reserved.

Li X.-Y.,British Geological Survey | Li X.-Y.,China University of Petroleum - Beijing | Zhang Y.-G.,Sinopec
Journal of Geophysics and Engineering | Year: 2011

This paper discusses the concepts of multicomponent seismology and how it can be applied to characterize hydrocarbon reservoirs, illustrated using a 3D three-component real-data example from southwest China. Hydrocarbon reservoirs formed from subtle lithological changes, such as stratigraphic traps, may be delineated from changes in P- and S-wave velocities and impedances, whilst hydrocarbon reservoirs containing aligned fractures are anisotropic. Examination of the resultant split shear waves can give us a better definition of their internal structures. Furthermore, frequency-dependent variations in seismic attributes derived from multicomponent data can provide us with vital information about fluid type and distribution. Current practice and various examples have demonstrated the undoubted potential of multicomponent seismic in reservoir characterization. Despite all this, there are still substantial challenges ahead. In particular, the improvement and interpretation of converted-wave imaging are major hurdles that need to be overcome before multicomponent seismic becomes a mainstream technology. © 2011 Nanjing Geophysical Research Institute.

Yao Y.,China University of Petroleum - Beijing | Wu Y.-S.,Colorado School of Mines | Zhang R.,Colorado School of Mines
Transport in Porous Media | Year: 2012

The mathematical model for transient fluid flow in porous media is based in general on mass conservation principle. Because of the small compressibility of formation fluid, the quadratic term of pressure gradient is always ignored to linearize the non-linear diffusion equation. This may result in significant errors in model prediction, especially at large time scale. In order to solve this problem, it may be necessary to keep the quadratic term in the non-linear equations. In our study, the quadratic term is reserved to fully describe the transient fluid flow. Based on this rigorous treatment, the mathematical models are established to analyze the transient flow behavior in a double porosity, fractal reservoir with spherical and cylindrical matrix. In addition, Laplace transformation method is employed to solve these mathematical models and the type curves are provided to analyze the pressure transient characteristics. This study indicates that the relative errors in calculated pressure caused by ignoring the quadratic term may amount to 10 % in a fractal reservoir with double porosity, which can't be neglected in general for fractal reservoirs with double porosity at large time scale. © 2012 Springer Science+Business Media B.V.

Li M.,China University of Petroleum - Beijing
Mathematical Problems in Engineering | Year: 2013

The selection of a design for the given product is a critical problem in product design development. Focuses of the designers and customers on the design are not identical. In order to bridge the gap and provide a more relaxing way to select the design, a new method based on quality function deployment (QFD) is proposed. In such a method, customers are required to give their linguistic preferences on the design with respect to the customer requirements (CRs). In the rating of the weight of CRs, they are allowed to provide incomplete linguistic weight information and the objective optimization model is proposed to derive the exact linguistic weight information. Designers are required to rate the correlation between design requirements (DRs) and the relationship between the CRs and DRs to construct the house of quality. Opinions given by the customers are translated into the opinions with respect to the DRs based on the QFD. Afterwards, the priorities of the designs and design requirements are determined. The assessment results not only show the contribution of each design requirement to the customer satisfaction but also show the advantages and disadvantages of each design from the designers' perspective clearly and directly. An example is provided to validate the applicability of the proposed method. © 2013 Ming Li.

Wang J.,China University of Petroleum - Beijing
AIChE 2013 - 2013 AIChE Spring Meeting and 9th Global Congress on Process Safety, Conference Proceedings | Year: 2013

A discussion covers a model for calculating the total energy of gas-liquid layer on the float valve trays operating at low loads; liquid flow characteristics of different areas; expressions of kinetic energy, potential energy, and surface energy; pressure fluctuations; safety issues when valve trays are operated at low loads; and hydraulics parameters. This is an abstract of a paper presented at the 2013 AIChE Spring Meeting and 9th Global Congress on Process Safety (San Antonio, TX 4/28/2013-5/2/2013).

Gao G.,China University of Petroleum - Beijing
Natural Gas Geoscience | Year: 2013

To understand petroleum geology role of carbonate rock stylolite, this paper stated the research advances of the cause, type, material composition and diagenesis of the carbonate rock stylolite and its role on the carbonate rock thickness recovering, generation, expulsion, migration and accumulation of petroleum. Research in the distribution, type and genesis of stylolite is relatively mature and it was concluded that stylolite resulted from the contact [JP]of stress and solution. Stylolites consisted of clay, quartz, solid organic matter, bitumen, and secondary minerals such as pyrite, calcite, etc. Its formation resulted in the reduction of carbonate rock thickness. Stylolites played an important role on the petroleum migration and accumulation due to secondary alteration. In the area with low abundance of organic matter, organic-rich stylolites had significant meaning to the generation-expulsion of hydrocarbons. However, the research was far from enough. In the future, more attention should be paid to the role of carbonate rock stylolites on the petroleum migration, accumulation, organic matter enrichment and mechanism of hydrocarbon generation & expulsion.

Zhang W.,China University of Petroleum - Beijing | Huang Y.,Soochow University of China | Seo H.J.,Pukyong National University
Ceramics International | Year: 2013

A series of Ce3+, Tb3+ singly doped and Ce 3+/Tb3+-co-doped Mg2La3[SiO 4]2[PO4]O phosphors with the apatite-like structure were prepared by conventional solid-state reaction. The X-ray diffraction (XRD), photoluminescence excitation and emission spectra, luminescence decay curves and lifetimes were applied to characterize the samples. The efficient excitation energy transfer from Ce3+ to Tb3+ was verified by the excitation and emission spectra together with the luminescence decay curves. The Ce3+/Tb3+ co-doped phosphor shows an intense broad excitation band between 300 and 430 nm, which matches near-UV chip (350-420 nm). Under the excitation of near UV light, the Ce3+/Tb3+ co-doped sample exhibits two distinct luminescence bands: a blue one centered at about 415 nm originating from Ce 3+ ions and a green-emitting at 543 nm from the 5D 4→7F5 transition of Tb3+ ions. The emission can be tuned from the blue to the green color by changing the doping concentration of Tb3+. The energy transfer from Ce 3+ to Tb3+ has been demonstrated to be the dipole-quadrupole mechanism, and the critical distance is calculated to be 16.04 Å. © 2012 Elsevier Ltd and Techna Group S.r.l.

Yan J.,Harbin Engineering University | Xiao Y.,Harbin Engineering University | Ning G.,China University of Petroleum - Beijing | Wei T.,Harbin Engineering University | Fan Z.,Harbin Engineering University
RSC Advances | Year: 2013

Highly crumpled graphene sheets (HCGSs) have been prepared by a facile and rapid route through freezing a chemically reduced graphene oxide aqueous suspension with liquid nitrogen. The porous and highly crumpled graphene structure with a large surface area and pore volume facilitates fast ionic transport within the electrode while preserving excellent electrical conductivity and thus endows HCGSs with excellent electrochemical properties. As the electrodes for supercapacitors, the HCGSs exhibit high specific capacitance (259 F g-1), excellent rate capability and cycling stability (93% retention after 5000 cycles). This journal is © 2013 The Royal Society of Chemistry.

Wang F.,China University of Petroleum - Beijing
Arabian Journal of Geosciences | Year: 2016

Reservoir properties may change during the long-term production, such as time-dependent skin factor and permeability. The reservoir modeling with constant reservoir properties cannot match the field performance, which will bring huge uncertainties for future forecasting. Therefore, for the reservoir with time-dependent reservoir properties, reservoir model needs to be calibrated continuously. However, diagnosis of changes in reservoir properties is difficult. This paper proposes a method of real-time reservoir simulation model update using time-dependent reservoir properties diagnosed from transient pressure with wavelet transform (WT). A key diagnostic function can identify the time and degree of changes in reservoir properties, and then the sliding window technique is applied to divide pressure history into different time windows, and in each time window reservoir properties change so little that they can be treated to be constant. When the changes in reservoir properties are large, time window will slide to the subsequent one and near-wellbore model (NWM) will be selected from the full-field reservoir model and then updated with new reservoir properties. An effective workflow of calibrating reservoir model by updating NWM with time-dependent reservoir properties has been proposed and demonstrated with a case study. This method can improve reliability of long-term reservoir modeling and reduce uncertainties of future forecasting, especially for the reservoir with time-dependent reservoir properties. © 2016, Saudi Society for Geosciences.

Pang Z.X.,China University of Petroleum - Beijing
Journal of Dispersion Science and Technology | Year: 2014

Flow characteristics and regeneration processes of foams were influenced by lamella properties and pore-throat structure in porous media. In this article, porous media was simplified as a bunch of constricted capillary tubes according to grain size, pore-throat radius, and immobile water saturation in porous media. Based on an analysis of forces upon liquid lamella, a mathematical model of foam migration and regeneration at steady state was established according to the mass conservation law and the momentum conservation law in porous media. The model could be used to calculate some important parameters in porous media, such as pressure distribution, shearing stress, lamella morphology, liquid-layer thickness, regeneration bubble size, etc. A series of flow experiments were carried out to investigate the influence of liquid properties and pore-throat structure on flow characteristics and resistance behavior of foams in porous media. The experimental results showed that pressure distribution monotonously decreased along porous media. The theoretical results were in good agreement with the experimental results. Foam structure, that is, foam quality was an important factor upon foam resistance behavior in porous media. The strongest resistance ability of foams was achieved at foam quality of 85% in porous media. © 2014 Copyright Taylor & Francis Group, LLC.

Zhang Y.,University of Science and Technology Beijing | Pang X.,University of Science and Technology Beijing | Qu S.,University of Science and Technology Beijing | Li X.,China Petroleum Pipeline Engineering Corporation | And 2 more authors.
International Journal of Greenhouse Gas Control | Year: 2011

Corrosion experiments were performed with X65 pipeline steel under static supercritical carbon dioxide (SC CO2) conditions at 50, 80, 110 and 130°C. The morphology, structure, chemical composition and fracture toughness of CO2 corrosion scales formed on the surface of X65 pipeline steel at various temperatures were investigated by means of Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD) and Energy Dispersive X-ray Spectroscopy (EDS). The corrosion rates were measured using weight-loss method. The fracture toughness of CO2 corrosion scale formed at different temperatures was investigated by means of nanoindentation and Vicker's indentation on a polished cross-section of the CO2 corrosion scale. The results showed that the corrosion rates increased from 50°C to 80°C and then decreased from 80°C to 130°C. As the temperature increased, the fracture toughness of CO2 corrosion scale first decreased and then increased, and the lowest fracture toughness was found at 80°C. The corrosion rate (CR) has a quantitative relationship with the fracture toughness (KIC)CR=(3.25/KIC3/2)-0.908. © 2011 Elsevier Ltd.

Li M.,China University of Petroleum - Beijing
Mathematical Problems in Engineering | Year: 2013

Axiomatic Design (AD) principles have been used to resolve the multicriteria decision making (MCDM) problems in engineering. With respect to MCDM problems in intuitionistic fuzzy environment, in which the criteria values take the form of intuitionistic fuzzy numbers, a new MCDM method is developed. Firstly, the approach proposed by Chen is extended to aggregate the decision makers' opinions in intuitionistic fuzzy environment. Secondly, membership common area and nonmembership common area are derived from the membership probability density function and the nonmembership probability density function, respectively. Then the membership information content and nonmembership information content are obtained based on the basic ideal of axiomatic design principles. Afterwards, the score function S and accuracy function H in intuitionistic fuzzy sets are extended with the information content to compare the alternatives. The alternatives that have the lowest values of functions of S and H are the best. Finally, a numerical example is used to illustrate the availability of the proposed method. © 2013 Ming Li.

Ma Z.,China University of Petroleum - Beijing
Lecture Notes in Electrical Engineering | Year: 2012

The purpose of this research is to study factors that may influence customer satisfaction in online banking sector in China. Moreover, the paper also aims to understand the relationship between customer satisfaction and website quality, and to find some major factors for keeping high level customer satisfaction in online banking sector. The paper describes the positive effect of website quality about customer satisfaction in online banking sector. After the validation of measurement scales, the hypothesis is contrasted through structural modeling. Finally, the authors validate the hypothesis and a measurement model in the paper. The data showed that website quality have direct and significant effect to customer satisfaction in online banking sector. Besides this, the authors found that some factors are positively related to customer satisfaction. Finally, it is observed that efficiency, interactivity, security, information, ease of use and content are major factors to affect customer satisfaction in the online banking sector. This study proposes a model for analyzing empirically the link between website quality and customer satisfaction in the online banking sector. © 2012 Springer-Verlag.

Yang H.,China University of Petroleum - Beijing
Journal of Energy Resources Technology, Transactions of the ASME | Year: 2012

As a highly efficient production method, multibranch horizontal well is widely used in the development of low permeability reservoirs, naturally fracture reservoirs, heavy oil reservoirs, shallow layer reservoirs, and multilayer reservoirs, because it can significantly improve the productivity of a single well, inhibit edge or bottom water coning, and enhance oil recovery. This paper presents a new productivity equation for multibranch horizontal well in 3D anisotropic reservoirs. By applying coordinate transformation, a 3D anisotropic reservoir is transformed into an equivalent isotropic reservoir with considering wellbore deformation and vertical radial flow. An analytical solution of multibranch horizontal well productivity in 3D anisotropic reservoirs is obtained by using pseudo-3D solving method and similar flow replaces theory. The results show that branch number n, branch length (l), and permeability anisotropy degree (β3) are the three main factors that have big effects on the production rate of multibranch horizontal well. © 2012 American Society of Mechanical Engineers.

Wang F.,China University of Petroleum - Beijing
Petroleum Science | Year: 2012

With permanent down-hole gauges (PDGs) widely installed in oilfields around the world in recent years, a continuous stream of transient pressure data in real time is now available, which motivates a new round of research interests in further developing pressure transient processing and analysis techniques. Transient pressure measurements from PDG are characterized by long term and high volume data. These data are recorded under unconstrained circumstances, so effects due to noise, rate fluctuation and interference from other wells cannot be avoided. These effects make the measured pressure trends decline or rise and then obscure or distort the actual flow behavior, which makes subsequent analysis difficult. In this paper, the problems encountered in analysis of PDG transient pressure are investigated. A newly developed workflow for processing and analyzing PDG transient pressure data is proposed. Numerical well testing synthetic studies are performed to demonstrate these procedures. The results prove that this new technique works well and the potential for practical application looks very promising. © 2012 China University of Petroleum (Beijing) and Springer-Verlag Berlin Heidelberg.

Zhang S.-W.,China University of Petroleum - Beijing
Mocaxue Xuebao/Tribology | Year: 2011

The background to the use of the expression "green tribology" is given. The definition, objectives and main mission of green tribology are presented. The fields of the green tribology in a narrow sense and in a broad sense are also clarified. Moreover, through introducing the recently advances in green tribology, its research contents are discussed comprehensively from four aspects: (1) Tribological theories, methods and technologies for saving both energy and materials, and prolonging the working life of tribological parts and tribo-systems; (2) Tribological theories, methods and technologies for removing or reducing the harmful effects to ecological balance (including human health) produced by both tribological parts and tribo-systems in the course of life cycle; (3) Research on the tribological aspects of natural environment and natural disaster, mainly focused on the role, mechanisms and effects of friction; (4) Tribological technologies for providing technological support to the equipment of both renewable and clean energy. The developing directions of green tribology are also pointed out. It is held that green tribology will certainly play an increasingly important role as the earth is facing with serious energy and environmental problems.

Xu C.,Tsinghua University | Yu H.,Tsinghua University | Yu H.,China University of Petroleum - Beijing
Chemical Engineering Research and Design | Year: 2014

Reverse-flow diverter pumps have no moving parts that are in direct contact with the fluid; as a result, they are applicable for the transport of hazardous liquids or liquid-solid mixtures. To date, there is no method available for predicting the pumping capacity of reverse-flow diverter pumps. In this study, we experimentally investigated the pumping performance of reverse-flow diverters in the reverse-flow mode. Two dimensionless performance equations, expressed as q=0.9597exp(-Eur/0.9237)+0.4946exp(-Eur/7.360)+0.1765 and q=kα+I, were determined from the experimental data. Based on these two equations, a method for predicting the pumping capacity of reverse-flow diverter pumps was proposed. © 2013 The Institution of Chemical Engineers.

Hu B.,Northeast Normal University | Hu B.,Jilin Normal University | Zhang J.,Northeast Normal University | Chen Y.,China University of Petroleum - Beijing
European Polymer Journal | Year: 2011

We report here a theoretical investigation of the white-light emission from a single-polymer system with simultaneous blue (polyfluorene as a blue host) and orange (2,1,3-benzothiadiazole(BTD)-based derivative as an orange dopant) emission. With use of quantum-chemical approaches, our studies are focused on the variation in electronic and optical properties as a function of the chemical composition of the backbone in BTD-based derivatives. Furthermore, the results show that the electronic and optical properties of designed BTD-based derivatives can be tuned by the introduction of suitable electron-donating groups on terminal N,N-disubstituted amino groups, implying good candidates as orange dopants in WPLEDs with polyfluorene as a blue-light-emitting host. In addition, low reorganization energy values of holes or narrow differences between hole and electron transportations within the framework of the charge hopping model suggest designed BTD-based derivatives to be good hole transport or ambipolar transport materials in organic light-emitting diodes. It is also found that the designed BTD-based derivatives containing fluorene-based unit exhibit higher stability. © 2010 Elsevier Ltd. All rights reserved.

Song C.,China University of Petroleum - Beijing | Zhuang J.,State University of New York at Buffalo
International Transactions in Operational Research | Year: 2016

In the food industry, manufacturers may add some chemical additives to augment the appearance or taste of food. This may increase the food demand and sales profits, but may also cause health problems to consumers. The government could use a punishment policy to regulate and deter such risky behavior but could also benefit from economic prosperity and tax income based on their revenues. This generates a tradeoff for the government to balance tax income, punishment income, and health risks. Adapting to government regulations, the manufacturers choose the level of chemical additives, which impacts the consumer demand. To our knowledge, no prior work has studied the strategic interactions of regulating the government and the manufacturers, faced with strategic customers. This paper fills this gap by (a) building a government-manufacturer model and comparing the corresponding decentralized and centralized models; and (b) applying the 2008 Sanlu food contamination data to validate and illustrate the models. © 2016 The Authors.

Jia X.,China University of Petroleum - Beijing | Lu Y.,University of California at Los Angeles | Wei F.,Tsinghua University
Nano Research | Year: 2016

Nanomaterials with electrochemical activity are always suffering from aggregations, particularly during the high-temperature synthesis processes, which will lead to decreased energy-storage performance. Here, hierarchically structured lithium titanate/nitrogen-doped porous graphene fiber nanocomposites were synthesized by using confined growth of Li4Ti5O12 (LTO) nanoparticles in nitrogen-doped mesoporous graphene fibers (NPGF). NPGFs with uniform pore structure are used as templates for hosting LTO precursors, followed by high-temperature treatment at 800 °C under argon (Ar). LTO nanoparticles with size of several nanometers are successfully synthesized in the mesopores of NPGFs, forming nanostructured LTO/NPGF composite fibers. As an anode material for lithium-ion batteries, such nanocomposite architecture offers effective electron and ion transport, and robust structure. Such nanocomposites in the electrodes delivered a high reversible capacity (164 mAh·g–1 at 0.3 C), excellent rate capability (102 mAh·g–1 at 10 C), and long cycling stability. © 2016, Tsinghua University Press and Springer-Verlag Berlin Heidelberg.

Zeng Y.,China University of Petroleum - Beijing
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2010

The regional ecological risk has the characters of large scale, multiple stressors and multiple types of agents and difficult being quantified, From the definition of ecological risk, the ecological risk assessment method based on the indexes of landscape fragmentation degree and land value coefficient weighted by areas proportion has been put forward in this paper. Based on software platforms of ArcGIS and FRAGSTATS, the isoline map for ecological risk can be created by using the spatial sample method and the ordinary Kriging interpolator method. The land use map of Hohhot City for year 2005 was selected as example,the scope of ecological risk are between 0. 04-0. 26, but spatial difference of them are obviously, which high risk region locate at northeast mountainous area and southwest corner of faming land,. The driving force of north areas comes from soil erode, underwater and forest degradation, while that of south areas are the rapid industrialization, which make the forest, grass and especially agriculture land rapidly convert to industry use land. The results show the method set up in this paper is intuitionistic and convenient. It can be used to score relatively value and rules of spatial distribution for regional ecological risk.

An C.,China University of Petroleum - Beijing | Su J.,Federal University of Rio de Janeiro
Applied Mathematics and Mechanics (English Edition) | Year: 2014

The generalized integral transform technique (GITT) is used to find a semianalytical numerical solution for dynamic response of an axially moving Timoshenko beam with clamped-clamped and simply-supported boundary conditions, respectively. The implementation of GITT approach for analyzing the forced vibration equation eliminates the space variable and leads to systems of second-order ordinary differential equations (ODEs) in time. The MATHEMATICA built-in function, NDSolve, is used to numerically solve the resulting transformed ODE system. The good convergence behavior of the suggested eigenfunction expansions is demonstrated for calculating the transverse deflection and the angle of rotation of the beam cross-section. Moreover, parametric studies are performed to analyze the effects of the axially moving speed, the axial tension, and the amplitude of external distributed force on the vibration amplitude of axially moving Timoshenko beams. © 2014, Shanghai University and Springer-Verlag Berlin Heidelberg.

Song Q.,China University of Petroleum - Beijing
Communications in Computer and Information Science | Year: 2011

A new illumination invariant feature extraction method for texture classification is proposed. In order to capture the local image texture, texture pattern transform (TPT) in a local neighborhood of a monochrome texture image is introduced. The TPT is robust against any monotonic transformation of the gray scale. The joint distributions of two different TPT, which can be characterized using a pattern co-occurrence matrix (PCM), can be used for texture classification. The PCM technique only requires comparison and counting operations, and thus is highly computationally efficient. The properties of PCM include translation and illuminant invariance, which is highly desirable in real-world applications. Illumination invariant texture classification experimental results show that the texture features derived from PCM achieve good discrimination. © 2011 Springer-Verlag.

Song Q.,China University of Petroleum - Beijing
Communications in Computer and Information Science | Year: 2011

This paper presents a new methodology for multi-scale texture analysis. The basic idea is that an image texture is viewed as a tessellation of square texels of different sizes and pixel levels. A textural image is decomposed into a set of scale images and each scale image consists of square texels of the same size. The texels in a scale image may have different pixel values. The degree of presence of a texel in a textural image can be measured by the image area occupied by the texel in terms of pixel. The histogram of texel area is shown to be a useful texture feature, and a dominant texture scale derived from the histogram provides a good reference parameter for computing gray-level co-occurrence matrix. © 2011 Springer-Verlag.

Zhou Z.-Y.,China University of Petroleum - Beijing
Wutan Huatan Jisuan Jishu | Year: 2013

A hyperspectral curve can be decomposed into a series of intrinsic mode function (IMF) by empirical mode decomposition (EMD), thus we can analyze the hyperspectral data from various aspect and extract feature based on the decomposed IMF. The EMD method is adapted to process hyperion data in this paper. Each curve in a pixel is decomposed into a series of IMF, a series of IMF images are then constructed. It shows from the IMF images that different target have a corresponding IMF, and the level and property of noise are different for different bands; It can also be shown distinct smile effect by IMF images. Own to the corresponding relation between IMF and original data, the result from EMD is more intu-itionistic and easier to understand than that of wavelet and FFT methods. The factors, i. e. the definition of extremum, interpolating method, IMF criterion and end-points effect, which influence on the EMD result are discussed in the paper.

Macdonald M.J.,University of Canterbury | Wu Z.,China University of Petroleum - Beijing | Ruzicka J.-Y.,University of Canterbury | Golovko V.,University of Canterbury | And 2 more authors.
Separation and Purification Technology | Year: 2014

In this study, three forms of faujasite zeolite Y, i.e. ammonium, proton and sodium form, were tested as catalyst supports for ferric ions (Fe 3+) in the oxidation of aqueous formaldehyde (FA) in the presence of H2O2 and UVC. The effect of charge-balancing cations on the FA oxidation at acidic and alkaline conditions was investigated using a batch reactor. The results showed that the three tested catalysts behave similarly at pH 3. However, the presence of charge-balancing proton gives the highest conversion of FA (26%) after 120 min at pH 7, which is comparable to the results obtained at pH 3, indicating the confined space in the supercage of Fe/H-Y provides a pH environment for Fenton reaction different to that provided by Fe/NH4-Y and Fe/Na-Y. Turnover frequency given by Fe/H-Y is more than 3 times faster than that given by Fe/NH4-Y or Fe/Na-Y. We proposed the surface proton, which is in close proximity to Fe3+, mitigates the leaching of metal and allows photo-Fenton process similar to what is generally observed at acidic pH condition. No change in solution pH was observed after the addition of all three tested form of zeolite. We concluded that the localized acidic setting given by the proton inside the porous structure of zeolite is able to promote photo-Fenton reaction at alkaline condition in a convenient and effective way.© 2014 Elsevier B.V. All rights reserved.

Hook M.,Uppsala University | Davidsson S.,Uppsala University | Johansson S.,Uppsala University | Tang X.,China University of Petroleum - Beijing
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences | Year: 2014

Two of the most fundamental concepts in the current debate about future oil supply are oilfield decline rates and depletion rates. These concepts are related, but not identical. This paper clarifies the definitions of these concepts, summarizes the underlying theory and empirically estimates decline and depletion rates for different categories of oilfield. A database of 880 post-peak fields is analysed to determine typical depletion levels, depletion rates and decline rates. This demonstrates that the size of oilfields has a significant influence on decline and depletion rates, with generally high values for small fields and comparatively low values for larger fields. These empirical findings have important implications for oil supply forecasting. © 2013 The Author(s) Published by the Royal Society. All rights reserved.

Dong Z.,China University of Petroleum - Beijing | Lu M.,Jingdezhen Ceramic Institute | Huang W.,China University of Geosciences | Xu X.,China University of Geosciences
Journal of Hazardous Materials | Year: 2011

In this study, a novel suspended ceramic carrier was prepared, which has high strength, optimum density (close to water), and high porosity. Two different carriers, unmodified and sepiolite-modified suspended ceramic carriers were used to feed two moving bed biofilm reactors (MBBRs) with a filling fraction of 50% to treat oilfield produced water. The hydraulic retention time (HRT) was varied from 36 to 10. h. The results, during a monitoring period of 190 days, showed that removal efficiency of chemical oxygen demand was the highest in reactor 3 filled with the sepiolite-modified carriers, followed by reactor 2 filled with the unmodified carriers, with the lowest in reactor 1 (activated sludge reactor), at an HRT of 10. h. Similar trends were found in the removal efficiencies of ammonia nitrogen and polycyclic aromatic hydrocarbons. Reactor 3 was more shock resistant than reactors 2 and 1. The results indicate that the suspended ceramic carrier is an excellent MBBR carrier. © 2011 Elsevier B.V.

Cai S.,Metals USA | Schaffer J.E.,Metals USA | Ren Y.,Argonne National Laboratory | Yu C.,China University of Petroleum - Beijing
Applied Physics Letters | Year: 2013

Nitinol has been widely used to make medical devices for years due to its unique shape memory and superelastic properties. However, the texture of the nitinol wires has been largely ignored due to inherent complexity. In this study, in situ synchrotron X-ray diffraction has been carried out during uniaxial tensile testing to investigate the texture evolution of the nitinol wires during martensite detwinning, variant reorientation, and phase transformation. It was found that the thermal martensitic nitinol wire comprised primarily an axial (1̄20), (120), and (102)-fiber texture. Detwinning initially converted the (120) and (102) fibers to the (1̄20) fiber and progressed to a (1̄30)-fiber texture by rigid body rotation. At strains above 10%, the (1̄30)-fiber was shifted to the (110) fiber by (21̄ 0) deformation twinning. The austenitic wire exhibited an axial (334)-fiber, which transformed to the near-(1̄30) martensite texture after the stress-induced phase transformation. © 2013 AIP Publishing LLC.

Rao Y.,China University of Petroleum - Beijing | Rao Y.,Imperial College London | Wang Y.,Imperial College London
Geophysical Journal International | Year: 2013

In seismic waveform simulation, an irregular topography such as mountainous areas cannot be simplified to a flat surface. Even for marine seismic, a rough water bottom cannot be treated as a planar interface numerically. A body-fitted grid scheme will accurately present an earth model with an irregular topography. As it is a structured grid, then a simple finite difference scheme can be used as an efficient solver for waveform simulation. The pseudoorthogonal property of grids is obtained by solving Poisson's equation. Investigation reveals that grids should have the acute angles >67° (90° for completely orthogonal) and the cellsize change rate <5 per cent, so that meshes are in a good orthogonality suitable for finite difference operation in waveform modelling. The acoustic wave equation and the absorbing boundary condition are reformulated from the physical space to the computational space. Waveform simulation and eventually tomographic inversion using a realistically complicated velocity model with a curved surface demonstrate the effectiveness of developed technology that works for irregular topographic models. © The Authors 2013. Published by Oxford University Press on behalf of The Royal Astronomical Society.

Cao Y.,South China University of Technology | Luo X.,South China University of Technology | Yu H.,South China University of Technology | Peng F.,South China University of Technology | And 2 more authors.
Catalysis Science and Technology | Year: 2013

The catalytic properties of sp2- and sp3-hybridized carbons, represented by graphene and diamond, in the selective oxidation of cyclohexane were investigated to understand the structure dependence of carbon materials in the reaction. sp2 carbons showed the higher activity than sp3 carbons. The highest activity was obtained over mesoporous graphene, a representative sp2-hybridized carbon, yielding a weight-normalized activity of 162.6 mmol g-1 h-1. The excellent performance of sp2 carbons was rationalized by their ability to catalyze the decomposition of peroxide intermediates, such as cyclohexyl hydroperoxide, which promoted the oxidative reaction to produce cyclohexanol and cyclohexanone. © 2013 The Royal Society of Chemistry.

Li T.,China University of Petroleum - Beijing | Li T.,Petrochina
Shiyou Kantan Yu Kaifa/Petroleum Exploration and Development | Year: 2015

In view of the issue that casing patching by solid expandable tubular (SET) has a low success ratio in high temperature (HT) thermal recovery wells or high pressure (HP) water injection wells, four key techniques of SET were studied theoretically and experimentally, and the casing patching SET tool for the HT/HP wells was designed. The expandable tubular with post expansion mechanical properties reaching API N80 steel grade was developed. The loading plane angle of expandable connecting thread was optimized as -9°. The sealing piece of inlaid welded copper and the cone coated with tungsten carbide were developed. Based on these researches, a prototype SET patching tool for HT/HP wells has been manufactured. The SET patching tool for HT/HP wells was manufactured. Laboratory experiments demonstrated that the expansion force of the patching tool was between 25 MPa and 32 MPa, the pressure resistance in three periods of alternating temperature load was over 15 MPa, the sealing capacity exceeded 35 MPa, all were up to the designed standard. The field tests in 45 wells in the Liaohe and Tuha oil fields demonstrated that this technique has good adaptability in casing patching in high temperature thermal recovery wells or high pressure water injection wells. After the patching operation, the water pressure 15 MPa was maintained for 30 minutes to test the tool's sealing performance, the pressure drop was less than 0.2 MPa, and the success ratio of one-time construction was 100%. After the casing patching, the oil wells production increase significantly and remarkable economic benefits are achieved. ©, 2015, Science Press. All right reserved.

We modified the binary interaction parameter in Wong-Sandler mixing rule for cubic EOS as a two-parameter linear function of composition. We then incorporated the Non-Random-Two-Liquid excess Gibbs energy model into the modified Wong-Sandler mixing rule to correlate the phase boundaries of the CO2-H2O system through the φ-φ approach by using Peng-Robinson-Stryjek-Vera equation of state. The proposed EOS/Gex model has four adjustable temperature-dependent parameters for polar molecules; and it can be reduced smoothly to the van der Waal one-fluid mixing rule with only one binary interaction parameter for hydrocarbon systems. An excellent result was obtained when compared the modeling results with a large amount of the vapor-liquid equilibria experimental data (more than 1300 experimental data points located in a P-T region of 273-623 K and 0.1-200 MPa) for the CO2-H2O system. The average absolute deviations (AAD%) of modeling results from experimental data (mutual solubilities of CO2 and H2O) are less than 7.5% for both phases. In addition, the proposed model can be easily extended to a multi-component system on condition that the binary interaction parameters of each binary pair in the multi-component system are known. We provided a calculation example for the ternary CO2-CH4-H2O system and found that the modeling result agrees very well with experimental data for this ternary system. © 2016 Elsevier B.V.

Yan H.,CAS Institute of Geology and Geophysics | Liu Y.,China University of Petroleum - Beijing | Zhang H.,CGGveritas
Exploration Geophysics | Year: 2013

With advanced computational power, prestack reverse-time migration (RTM) is being used increasingly in seismic imaging. The accuracy and efficiency of RTM strongly depends on the algorithms used for numerical solutions of wave equations. Hence, how to solve the wave equation accurately and rapidly is very important in the process of RTM. In this paper, in order to improve the accuracy of the numerical solution, we use a time-space domain staggered-grid finite-difference (SFD) method to solve the acoustic wave equation, and develop a new acoustic prestack RTM scheme based on this time-space domain high-order SFD. Synthetic and real data tests demonstrate that the RTM scheme improves the imaging quality significantly compared with the conventional SFD RTM. Meanwhile, in the process of wavefield extrapolation, we apply adaptive variable-length spatial operators to compute spatial derivatives to decrease computational costs effectively with little reduction of the accuracy of the numerical solutions. © 2013 ASEG.

Liu Q.,Sinopec | Zhijun J.,Sinopec | Jianfa C.,China University of Petroleum - Beijing | Krooss B.M.,RWTH Aachen | Qin S.,Petrochina
Journal of Petroleum Science and Engineering | Year: 2012

We have detected the N 2 content in the natural gas from Tarim Basin by measuring the chemical and stable isotope composition of 107 natural gas samples, and found the N 2 contents vary widely. Based on the carbon isotopic composition of gas hydrocarbons, we have classified the natural gases into two genetic types: coal-type and oil-type gases, and the latter have consistently higher nitrogen contents than the former. Furthermore, according to the N 2 content, stable carbon and nitrogen isotope composition, three groups of N 2 sources have been identified: (I) Coal-type gas in Cenozoic reservoirs has low N 2 contents (N 2<5%), less depleted carbon and nitrogen isotope compositions (δ 13C 2>-26‰, δ 15N>+5.0‰). These nitrogen molecules likely come from ammonium montmorillonites and thermal degradation of aromatic and heterocyclic structures of anthracite; (II) Oil-type gas with moderate N 2 contents (5%20%), depleted carbon (δ 13C 2<-34‰) and widely varying nitrogen isotope compositions (-15‰<δ 15N<+15‰), located in Paleozoic and Mesozoic intervals such as Tazhong, Donghetang, Hade and Lunnan gas fields, etc. This high concentration of N 2 is mainly derived from Cambria-Ordovician shale carbonates at mature and highly mature stages, and the N 2 contents tend to increase with increasing thermal stress. In the end, we have provided a broad correlation between N 2 content and 3He/ 4He ratio and helium concentration, which indicates that a deep N 2 gas source may be relevant. © 2011 Elsevier B.V.

Ma C.,Sinopec | Wu X.,China University of Petroleum - Beijing | Gao S.,University of Leicester
Applied Thermal Engineering | Year: 2013

A heat transfer model that exploits the geothermal energy in oil production wells has been developed by considering not only the produced fluid from the oil well, but also its coupling with the formation temperature distribution and the heat transfer characteristics of the two-phase closed thermosyphon. This study shows that the two-phase closed thermosyphon can transfer effectively the required heat from the fluid of high temperature at the wellbore bottom to the fluid of relatively low temperature at the upper part of the wellbore, so that the overall fluid temperature distribution in the wellbore is improved with the fluid temperature near the wellhead being increased. The numerical model has been validated and further improved by comparing the computational results with the real production data from Chu 32 well and Chu 29-11 well of Huabei Oilfield. A number of influencing parameters on the efficiency of the proposed two-phase closed thermosyphon model have also been investigated in this study, which include the working fluid, the fluid production rate of the oil well, the water cut of the produced fluid and the working depth of the thermosyphon. © 2013 Elsevier Ltd. All rights reserved.

Chen Y.,United Information Technology | Niu F.,China University of Petroleum - Beijing | Niu F.,Rice University
Geophysical Journal International | Year: 2013

While inversion of seismic velocity from receiver function data could be instable due to its intrinsic non-linearity and non-uniqueness, improper stacking of receiver function could also introduce significant biases to the resulting velocity structure. In a distance section of receiver functions, the Moho Ps conversion and the two reverberations possess a positive and negative moveout, respectively. Stacking receiver functions without moveout correction could significantly reduce and distort the amplitude and waveform of these phases. Inversion with these incorrectly stacked receiver functions will thus inevitably introduce artefacts to the resulting velocity structure. In this study, we have improved the inversion procedure in two ways. First, we introduce a ray-parameter based (RPB) stacking method to correctly construct receiver function data for inversion. Specifically we develop a 'four-pin' method that accounts for the moveout effect of the converted and reverberated phases in stacking individual receiver functions recorded at various distances. Secondly, we divide the receiver function trace into conversion and reverberation windows and assign different weights between the two windows in the inversion. More weight is given to the Ps conversion window in resolving the shallow structure, which can be nearly fixed in the successive inversion of deeper structure. We also employ other pre-conditioning proposed by previous studies, such as balancing the receiver function data being filtered with different Gaussian filters, smoothing the velocity model and further regulating the model based on existing information. We compute synthetic receiver functions at distances between 30° and 90° from a target model and then use the RPB stacking method to generate the input data for various inversions (iterative linear) with different initial models. Our inversions with enhanced pre-conditioning and RPB stacked data demonstrate a good capability in recovering the target model from generally more stable iterations. Applying these techniques to two broad-band stations in China indicates that the improvements on data stacking and inversion can eliminate potential stacking-induced artefacts, and yield models more consistent with surface geology. © The Authors 2013. Published by Oxford University Press on behalf of The Royal Astronomical Society.

Liu R.,CAS Research Center for Eco Environmental Sciences | Liu J.-F.,CAS Research Center for Eco Environmental Sciences | Zhang Z.-M.,CAS Research Center for Eco Environmental Sciences | Zhang L.-Q.,China University of Petroleum - Beijing | And 3 more authors.
Journal of Physical Chemistry Letters | Year: 2014

For their unique properties, core-shell bimetal nanostructures are currently of immense interest. However, their synthesis is not a trivial work, and most works have been conducted on nanoparticles. We report herein a new synthetic tactic for submonolyer-Pt coated ultrathin Au nanowires (NWs). Besides providing a strong electromagnetic field for Raman signal enhancing, the underlined Au NWs markedly enhanced the catalytic activity of Pt atoms through increasing their dispersity and altering their electronic state. The integration of excellent SERS and high catalytic activity within Au@Pt NWs enable it work as platform for catalyzed reaction study. As a proof of principle, the self-organized Au@Pt NWs thin film is employed in operando SERS monitoring of the p-nitrothiophenol reduction process. In addition to providing kinetic data for structure-activity relationship study, the azo-intermidate independent path is also directly witnessed. This synthetic tactic can be extended to other metals, thus offering a general approach to modulate the physical/chemical properties of both core and shell metals. © 2014 American Chemical Society.

Guo X.,China University of Petroleum - Beijing | Zhou C.,Sinopec
Xinan Shiyou Daxue Xuebao/Journal of Southwest Petroleum University | Year: 2014

After the hydraulic fracturing of horizontal wells, shale gas reservoir seepage areas show a complex fracture net-work morphology, single well flow numerical model considering desorption-adsorption mechanism has a strong theoretical value and practical significance for analyzing single well production factors. Based on Warren-Root dual media model guiding ideology, matrix flow mathematical model and fracture flow mathematical model are established considering desorption-adsorption. Methods of discrete differential equations is designed and IMPES seepage linear processing method is carried out, and finally iterative simulation programming is realized through the Gauss-Seidel. Field applications, based on the results of the microseismic for fractured horizontal wells in shale reservoir geological model was constructed, the established numerical model can analyze the impact of pressure, gas adsorption, permeability, formation properties and other characteristics on production parameters. The results are consistent with the law of shale gas production, so this simple model can effectively guide the field of engineering design and dynamic analysis.

Li M.,China University of Petroleum - Beijing | Ellis G.S.,U.S. Geological Survey
Energy and Fuels | Year: 2015

Dibenzofuran (DBF), its alkylated homologues, and benzo[b]naphthofurans (BNFs) are common oxygen-heterocyclic aromatic compounds in crude oils and source rock extracts. A series of positional isomers of alkyldibenzofuran and benzo[b]naphthofuran were identified in mass chromatograms by comparison with internal standards and standard retention indices. The response factors of dibenzofuran in relation to internal standards were obtained by gas chromatography-mass spectrometry analyses of a set of mixed solutions with different concentration ratios. Perdeuterated dibenzofuran and dibenzothiophene are optimal internal standards for quantitative analyses of furan compounds in crude oils and source rock extracts. The average concentration of the total DBFs in oils derived from siliciclastic lacustrine rock extracts from the Beibuwan Basin, South China Sea, was 518 μg/g, which is about 5 times that observed in the oils from carbonate source rocks in the Tarim Basin, Northwest China. The BNFs occur ubiquitously in source rock extracts and related oils of various origins. The results of this work suggest that the relative abundance of benzo[b]naphthofuran isomers, that is, the benzo[b]naphtho[2,1-d]furan/{benzo[b]naphtho[2,1-d]furan + benzo[b]naphtho[1,2-d]furan} ratio, may be a potential molecular geochemical parameter to indicate oil migration pathways and distances. © 2015 American Chemical Society.

Wei X.,China University of Petroleum - Beijing
Proceedings - International Conference on Electrical and Control Engineering, ICECE 2010 | Year: 2010

With development of modern industry, more and more non-linear loads are used in power system, resulting in increasingly severe harmonic pollution. Harmonic becomes main factors affecting power quality. Active power filter, as the most effective method to eliminate harmonic, has been paid more and more attention recently. The current compensation performance of active power filter depends on the controller. At present, more and more active power filters have been controlled by digital controller, which has the advantage of flexible control strategy, powerful ability of signal processing. However, digital controller has inherent drawbacks, such as quantization error, signal delay caused by Zero-Order hold, sample and computation delay. With analyzing active power filter's decreased performance caused by digital controller, this paper concentrates on two reasons: Zero-Order hold, sample and computation delay. © 2010 IEEE.

Wang J.,China University of Petroleum - Beijing | Wang J.,Tsinghua University | Xu C.,Tsinghua University
Chemical Engineering and Technology | Year: 2014

A mini liquid-liquid extractor was designed based on a feedback fluidic oscillator. According to the Coanda effect, the designed oscillator with two feedback channels enables good mixing of the aqueous and organic phases. Co-current liquid-liquid extraction was performed in the mini extractor, and it was visually observed that the aqueous phase was dispersed into small droplets because of fluidic oscillation and vortex formation. The aqueous phase was more effectively dispersed at the stage near the outlet and with increasing flow. Several tests were performed for evaluating the extraction performance of the extractor using 30% tributyl phosphate-kerosene and 3M HNO3 solutions as the organic and aqueous phases, respectively. The obtained extraction efficiency was close to the equilibrium efficiency, indicating that this extractor has the potential for liquid-liquid extraction of hazardous liquids. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Wang Y.,China University of Petroleum - Beijing
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2016

We uncover an optimization principle for the finite-time heat-work conversion process performed between two finite-sized heat reservoirs in the nonlinear response regime that is characterized by rather generic flux-force relations. We solve the problem of maximizing work output in a given time interval by means of the variational method. Moreover, in the limiting case that the cold reservoir is infinite, we find the corresponding optimized process can be determined by a single quantity, which plays the role similar to that of the Hamiltonian in classical mechanics. Some theoretical implications are discussed consequently, under the generalized tight-coupling condition which applies to both linear and nonlinear response cases. Our results can hopefully help design and control realistic thermodynamical processes. © 2016 American Physical Society.

Zhou Q.,University of California at Davis | Zhou Q.,China University of Petroleum - Beijing | Ristenpart W.D.,University of California at Davis | Stroeve P.,University of California at Davis
Langmuir | Year: 2011

We report a magnetic technique for altering the apparent contact angle of aqueous droplets deposited on a nanostructured surface. Polymeric tubes with embedded superparamagnetic magnetite (Fe 3O 4) nanoparticles were prepared via layer-by-layer deposition in the 800 nm diameter pores of polycarbonate track-etched (PCTE) membranes. Etching away the original membrane yields a superparamagnetic film composed of mostly vertical tubes attached to a rigid substrate. We demonstrate that the apparent contact angle of pure water droplets deposited on the nanostructured film is highly sensitive to the ante situm strength of an applied magnetic field, decreasing linearly from 117 ± 1.3° at no applied field to 105 ± 0.4° at an applied field of approximately 500 G. Importantly, this decrease in contact angle did not require an inordinately strong magnetic field: a 15° decrease in contact angle was observed even with a standard alnico bar magnet. We interpret the observed contact angle behavior in terms of magnetically induced conformation changes in the film nanostructure, and we discuss the implications for reversibly switching substrates from hydrophilic to hydrophobic via externally tunable magnetic fields. © 2011 American Chemical Society.

Bai D.,Beijing University of Chemical Technology | Chen G.,China University of Petroleum - Beijing | Zhang X.,Beijing University of Chemical Technology | Wang W.,Beijing University of Chemical Technology
Langmuir | Year: 2011

In this paper, we report microsecond molecular dynamics simulations of the kinetic pathway ofCO2 hydrate formation triggered by hydroxylated silica surfaces. Our simulation results show that the nucleation of the CO 2 hydrate is a three-stage process. First, an icelike layer is formed closest to the substrates on the nanosecond scale. Then, on the submicrosecond timescale, a thin layer with intermediate structure is induced to compensate for the structure mismatch between the icelike layer and the final stable CO 2 hydrate. Finally, on the microsecond timescale, the nucleation of the first CO2 hydrate motif layer is generated from the intermediate structure that acts as nucleation seeds. We also address the effects of the distance between two surfaces. © 2011 American Chemical Society.

Shi H.,Ohio State University | Wang Y.,China University of Petroleum - Beijing | Fang B.,Ohio State University | Fang B.,East China University of Science and Technology | And 4 more authors.
Langmuir | Year: 2011

Drag-reducing (DR) surfactant fluids based on threadlike micelles are known to suffer from poor heat-transfer capabilities. Accordingly, the use of these fluids is limited to recirculating systems in which heat exchange is not important. Here, we show for the first time that light-responsive threadlike micelles can offer a potential solution to the above problem. The fluids studied here are composed of the cationic surfactant Ethoquad O/12 PG (EO12) and the sodium salt of trans-orthomethoxycinnamic acid (OMCA). Initially, these fluids contain numerous threadlike micelles and, in turn, are strongly viscoelastic and effective at reducing drag (up to 75% DR). Upon exposure to UV light, OMCA is photoisomerized from trans to cis. This causes the micelles to shorten considerably, as confirmed by cryo-transmission electron microscopy (cryo-TEM). Because of the absence of long micelles, the UV-irradiated fluid shows lower viscoelasticity and much lower DR properties; however, its heat-transfer properties are considerably superior to the initial fluid. Thus, our study highlights the potential of switching off the DR (and in turn enhancing heat-transfer) at the inlet of a heat exchanger in a recirculating system. While the fluids studied here are not photoreversible, an extension of the above concept would be to subsequently switch on the DR again at the exit of the heat exchanger, thus ensuring an ideal combination of DR and heat-transfer properties. © 2011 American Chemical Society.

Bao Y.,China University of Petroleum - Beijing
Applied Mechanics and Materials | Year: 2013

Gas channeling is tending to happen in CO2 immiscible flooding process, and that would seriously influence gas injection development. In order to plugging gas channeling channel effectively, improve inspiration and production profile, and enhance swept volume and oil displacement efficiency of the gas injection, field trials of foam seal channeling are carried out. The tests showed that carbon dioxide foam can effectively plugging the gas channeling channel, expand the swept volume of carbon dioxide gas, reduce invalid circulation, and enhancing oil displacement efficiency. The anti-sealing channeling technology is cost-efficient, and it is suitable for Daqing peripheral low permeability oil field on gas injection development. It has good prospects, and it will provide a strong technical support on gas injection development of low permeability reservoir. © (2013) Trans Tech Publications, Switzerland.

Zhang Q.,Xian Jiaotong University | Feng X.,China University of Petroleum - Beijing | Chu K.H.,Xian Jiaotong University
Industrial and Engineering Chemistry Research | Year: 2013

Large consumption and soaring demand have led to huge deficiencies in the availability of fresh resources such as hydrogen and water in the chemical industries throughout the world, casting a long shadow over their operating margins. More than ever the efficient use and conservation of fresh resources plays a pivotal role in many large-scale chemical processing enterprises such as refinery operations. This paper addresses the target of minimum fresh resource demand and design of resource conservation networks with multiple contaminants. With a view to the allocation of a single sink, a triangle rule is deduced from an existing design technique. In order to describe the quality difference of sources and sinks according to different impurity concentrations, the nearest neighbor algorithm for resource conservation networks with single contaminant is generalized to the case of resource conservation networks with multiple contaminants. On the basis of the new nearest neighbor algorithm, a ranking rule is established to give a reasonable order of sources as well as sinks. With the ranked order, the material recovery pinch diagram for multiple contaminants is constructed. For each match, the proposed solution procedure can achieve the maximum direct reuse at sharp match status of at most two contaminants. The resulting group of matching polygons gives the target and the corresponding network as well as the restrictive contaminants in each match. Three cases are studied to illustrate the proposed methodology. © 2012 American Chemical Society.

Lu H.,CAS Guangzhou Institute of Geochemistry | Peng P.,CAS Guangzhou Institute of Geochemistry | Hsu C.S.,China University of Petroleum - Beijing | Hsu C.S.,Florida State University
Energy and Fuels | Year: 2013

For the sulfur-rich heavy oils in Jinxian Sag, Bohai Bay Basin, northern China, high abundances of organic sulfur compounds (OSCs), including benzothiophenes and dibenzothiophenes, were detected in aromatic hydrocarbon fractions. Short-chain (such as 20-thienylpregnanes and thienylandrostanes) and regular carbon-numbered S-containing steroids are also present in the saturate hydrocarbon fractions. In addition, a series of short-chain steranes (C 21-26), unusual short-chain lanostanes (C24-25), 4-methyl steranes (C22-23), 4,4-dimethyl steranes (C22-24), and androstanes (C19-20) were found, accompanied with high-molecular-weight analogues, C27-30 regular steranes, C 27-30 4-methyl steranes, and C28-30 4,4-dimethyl steranes. The distinctive distribution characteristics and dominance of the short-chain steroids in these oils are believed to be derived from the cleavage of the weak C-S bond at C-17 and C-20 positions of extensively sulfurized steroids with subsequent microbial attack or bacterial reworking. To overcome the limitations of routine gas chromatography mass spectrometric analysis, which are only suitable for analyzing volatile and nonpolar saturate and aromatic hydrocarbon fractions, and to obtain more information and overall cognition on macromolecular OSCs in highly complicated petroleum substrates, such as polar NSO and asphaltene fractions, electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry was employed for the analysis of Jinxian heavy oils after methylation pretreatment. The results revealed that very complicated sulfur (S1, S2, and S3) and oxidized sulfur (OS and OS2) compounds were present in the Jinxian heavy oils, with the absence of nitrogen-containing compounds. In addition, the distribution of the most abundant S1-type OSCs was featured by a series of compounds with a wide range of double bond equivalent (DBE) values of 1-14 and carbon numbers of 10-44. On the basis of the reported carbon number distributions of steroid biomarkers in these oils, the most abundant OSCs in Jinxian oils with DBE = 5-7 in the vicinity of C19-22 and C 28-30 might come from the short-chain and regular S-containing steroids. The occurrence of abundant S-containing steroids was the results of extensive sulfurization during early diagenetic stages because much more double bonds, hydroxyl groups, and carbonyl groups exist in sterols and sterenes, which are prone to attack by inorganic sulfur. © 2013 American Chemical Society.

Purpose: The purpose of the paper is to develop a model for the selection of knowledge management system (KMS), in which the assessment criteria are defined and the TOPSIS method with multiple distances in fuzzy environment is proposed. Design/methodology/approach: First, the paper establishes the evaluation criteria from functional, performance and economic aspects. Second, a new TOPSIS method is proposed to deal with the linguistic evaluation information. In the proposed method, in order to eliminate the bias of TOPSIS with single distance, six kinds of distances that are commonly used in TOPSIS including Hamming distance, Euclidean distance, Dp,q distance, Hausdorff distance, L2 distance and vertex distance are extended in fuzzy environment and employed in the TOPSIS to generate six independent pre-rankings. Afterwards these pre-rankings are combined by Condorcet method to generate the final joint ranking. Findings: Since the final ranking is the collective result, the bias in each single pre-ranking is eliminated and the selection is more objective and accurate. The example shows the proposed model is practical. Research limitations/implications: The linguistic preferences are given in the single granularity linguistic information. Practical implications: The proposed model can be applied as a tool for decision makers in the evaluation and selection of KMS. Originality/value: The paper gives an overall evaluation of KMS and proposes the new TOPSIS method with multiple distances in fuzzy environment. © Emerald Group Publishing Limited.

Tian Y.,Taiyuan University of Science and Technology | Ge L.,China University of Petroleum - Beijing | Wang K.,Taiyuan University of Science and Technology | Chai Y.,Taiyuan University of Science and Technology
Materials Characterization | Year: 2014

Novel MoS2/g-C3N4 heterojunction photocatalysts were synthesized via a simple impregnation and heating methods. The products were characterized by X-ray diffraction, transmission electron microscopy and UV-vis diffuse reflectance spectra. The photocatalytic activities of MoS2/g-C3N4 samples were evaluated based on the hydrogen evolution experiments under visible light irradiation (λ > 400 nm). The UV-vis diffuse reflectance spectra revealed that the MoS 2/g-C3N4 photocatalysts had strong absorption in the visible light region. The photocatalytic results indicated that the highest H2 evolution rate of 23.10 μmol·h- 1 was achieved on the 0.5 wt.% MoS2-g-C3N4 sample, which was enhanced by 11.3 times compared to pure g-C3N4. This study may provide an approach to the development of novel heterojunction photocatalysts for hydrogen production under visible light irradiation. © 2013 Elsevier Inc.

Mou J.,China University of Petroleum - Beijing | Zhu D.,Texas A&M University | Hill A.D.,Texas A&M University
SPE Journal | Year: 2010

In the acid-fracturing process, the fracture conductivity created by acid etching of the fracture walls is because of the surface roughness created by the acid's nonuniform dissolution of the fracture surfaces. The acid-fracture conductivity is dependent on surface etching patterns, which are determined by permeability and mineralogy distributions. That is, the spatial distribution of fracture roughness affects the fracture conductivity, which cannot be considered in laboratory measurements of acid-fracture conductivity, which use core samples that are too small to observe such macroscale heterogeneities, or in typical acid-fracture simulators, in which the gridblock size is much larger than the scale of local heterogeneities. An accurate prediction of acid-fracture conductivity necessitates the detailed description of the acid etching profiles on the fracture surfaces, which depend on acid transport in the fracture, leakoff because of local permeability, and acid/rock reactions. In this paper, we developed a 3D intermediate-scale acid-fracture model with gridblock sizes small enough (gridblock sizes comparable to the core-sample size in experiments) and total dimensions large enough (the total dimensions comparable to a gridblock size in an acid-fracture simulator) to capture local and macroscale heterogeneity characteristics. The model predicts the pressure field, the flow field, acid concentration profiles, and fracture-surface profiles as functions of acid injection volume. In the model, we use a front-fixing method (Crank 1984) to handle the irregular, moving boundaries in numerical simulation. Spatially correlated permeability and mineralogy distributions were generated by using a semivariogram model. The model was validated by comparing simulation results with experimental results from an acid-fracture conductivity cell. With the model, by extensive numerical simulation, we analyzed the relationship among fracture-surface-etching patterns, conductivities, and the distributions of permeability and mineralogy. We also illustrated the formation characteristics necessary for acid to create channel-caused high acid-fracture conductivity. We found that a fracture segment with channels extending from the inlet to the outlet of the segment has high conductivity because fluid flow in deep channels causes a very small pressure drop. Such long and highly conductive channels can be created by acids if the formation has heterogeneities in either permeability or mineralogy or both, with high correlation length in the main flow direction, which is the case in laminated formations. Copyright © 2010 Society of Petroleum Engineers.

Zeng L.,China University of Petroleum - Beijing | Liu H.,Petrochina
Journal of Petroleum Science and Engineering | Year: 2010

This paper studies the influence of fracture on the development of low-permeability sandstone reservoirs. There are four assemblages of high angle tectonic fractures assuming east-west, south-north, northwest-southeast and northeast-southwest strikes respectively in the Putaohua oil layer of the Taizhao district, leading to a gradual weakening in their development. In light of the influences of the present-day stress field, the east-west fractures are considered to have the best connectedness, the biggest aperture, the highest permeability and the lowest opening pressure, present the main channel for fluid flow in the low-permeability sandstone reservoirs. These fractures impact on the well pattern deployment, water injection and hydraulic fracturing in the low-permeability sandstone reservoirs. Based on the distribution and flow characteristics of fractures, favorable effects can be obtained by rectangular and rhombus well patterns along the principal seepage fractures of the east-west orientation in the primary period of development. Due to their minimum opening pressure, the east-west fractures are the earliest to open during the water flooding development, so we should control the injection pressure under the open pressure of east-west fractures. Artificial fractures formed by hydraulic fracturing in low-permeability sandstone reservoirs are controlled by natural fractures and the presented-day stress. If the angle between natural fractures and the present-day stress is less than the critical angle, the artificial fractures extend mainly along the natural fractures and do not generate new fractures. If the angle between natural fractures and the present-day stress is bigger than the critical angle, the artificial fractures extend vertically to the minimum stress (σ3) of the present-day stress field. These results demonstrate the importance of assessing the fracture distribution in the low-permeability sandstone reservoirs. © 2010 Elsevier B.V.

The western Sichuan Basin located at the front of the Longmen Mountain in the western Sichuan Province of China is a foreland basin formed in the Late Triassic. The Upper Triassic Xujiahe Formation in the basin is an ultralow-permeability and low-porosity tight-gas sandstone reservoir. Microfractures, such as intragranular microfractures, grain-edge microfractures, and transgranular microfractures, are abundant in the tight sandstones. Microfractures improve storage and permeability and impact distribution of natural gas. Microfractures reflect tectonic, overpressure, and diagenetic origins. Using quartz and calcite fluid inclusions and burial history, tectonic microfractures were determined to be formed at the end of the Triassic, the end of the Cretaceous, and the end of the Neogene-early Pleistocene. Microfractures related to overpressure, being tension microfractures, are commonly filled with bitumen and were formed at the middle to Late Cretaceous when the maximum pressure coefficients were 1.6 to 2.1. In the middle to late Neogene, the pressure coefficient was reduced to less than 1.3 because of fault activity and tectonic uplift in the southwestern Sichuan Basin, and these tension microfractures closed and were filled with calcite. The transition of stress state from compression to tension by overpressure is the reason that tension microfractures were formed in the compression setting. Diagenetic fractures were formed at the end of the Late Triassic to Jurassic. Under intense compaction, grain-crushing crackle fractures in quartz and cleavage fractures in feldspar formed intragranular microfractures. Some transgranular microfractures caused by diagenesis are along the bedding plane and parallel to the directional mineral grains. Copyright ©2010. The American Association of Petroleum Geologists. All rights reserved.

Zhang J.,Heriot - Watt University | Zhang J.,China University of Petroleum - Beijing | Bian X.,Sinopec
Fuel | Year: 2014

A Gum fracturing fluid compatible fracture stabilizers was selected through experimental evaluation in the former research. The simulation experiments show that the flow conductivity of fractures could be maintained by fracture stabilizer, and the number of intrusive particles in the proppant processed by stabilizers was significantly reduced. The dosage of the fracture stabilizer was optimized according to comprehensive experiments of long term conductivity and sand control effect under condition of bilinear flow. Results showing that conductivity decreases over time and reaches steady state after 5 days. The conductivity reduction decreases with the increase of stabilizer mass fraction. After a comprehensive evaluation, fracture stabilizer of 3-5% mass fraction is recommended. © 2014 Elsevier Ltd. All rights reserved.

Zhang F.R.,China University of Petroleum - Beijing
Applied Mechanics and Materials | Year: 2013

In order to predict the demand of fresh water in China in the year of 2025, a mathematical model is proposed based on the summation of demand of water in ten major regions in China. The gray model is applied to predict the fresh water resource in the year of 2025 while neural network model is applied to predict the fresh water demand. The degree of water shortage is evaluated by the international water scarcity assessment criteria which are commonly used. The conclusion is that some provinces in China may be faced with big challenges for water shortage. © (2013) Trans Tech Publications, Switzerland.

Guoyi H.,Petrochina | Guoyi H.,China University of Petroleum - Beijing | Jin L.,Petrochina | Xiuqin S.,Petrochina | Zhongxi H.,Petrochina
International Journal of Coal Geology | Year: 2010

The genetic type, source and charging history of natural gas in the Yulin gas field in the Ordos Basin have been studied by combining the carbon isotopic composition of natural gas and geochemical characteristics of light hydrocarbons with carbon isotope fractionation model results and fluid inclusion analysis. The carbon isotopic composition of methane and ethane in the Yulin gas field is relatively enriched in 13C with δ13C1 values ranging from -35.3%to -29.8% (average value=-32.4%) and δ13C2 ranging from -26.3% to -23.5% (average value=-24.8%). The C7 light hydrocarbons are predominated by methylcyclohexane, accounting for 65.8% to 80.9% (average value=71.6%), which is characteristic of coal-derived gas. Furthermore, the gas geochemistry indicates that, although marine limestone source rocks are present in the region, the contribution of oil-associated gas from this source to the Yulin gas field is quite low. Based on the empirical relationship between δ13C1 and %Ro of gas source rocks, and the kinetic isotope fractionation predictions for gases generated in the Yulin gas field, the observed δ 13C of methane is heavier than that of natural gas only originated from in-situ coal-measures. This result shows that gas in the Yulin gas field is contributed not only by the natural gas generated from local coal-measure source rocks, but also from the higher maturity natural gas sourced from the coal-measure source rocks to the south or southwest of this gas field. Fluid inclusion analysis proves that the accumulation of natural gas in the Yulin gas field has the characteristics of continuous charge. © 2009 Elsevier B.V.

Hou Y.,China Oilfield Services Ltd. | Yue X.,China University of Petroleum - Beijing
Petroleum Science | Year: 2010

A composite gel was prepared for plugging CO2 channeling, which is a serious problem for enhanced oil recovery with CO2. A composite gel which is one of the materials for successful control of CO2 channeling during CO2 injection process was studied in this paper. SEM and nano particle size analysis were used to describe this material's microstructure. Its effect on CO2 channeling control was evaluated with core flow experiments. Both the rheological test and core plugging experiments indicated that both acrylamide monomer concentration and reaction pressure had positive influences on gel properties. The gel system with an acrylamide monomer concentration of 2% and 5% sodium silicate was proved to have excellent strength, elastic and plugging efficiency, which confirmed huge development potential and wide application of the composite gel system. The high-pressure acid environment arising from the CO2 injection not only reacts with solid silicate to form silicic acid gel, but also facilitates efficient polymerization. © 2010 China University of Petroleum (Beijing) and Springer-Verlag Berlin Heidelberg.

Qun L.,China University of Petroleum - Beijing
Petroleum Exploration and Development | Year: 2010

Based on discussions about the tectonic background and the relationship between faulting and petroleum accumulation in Chinese continental basins, this paper introduces the basic concepts, principles, scientific foundation, an exploration of fault controlling hydrocarbon theory as well as the differences between fault controlling hydrocarbon theory and other viewpoints about fault controlling petroleum. The geologic tectonic backgrounds of compression from three directions, continental facies basin, extension in east and compression in west, developed faults and frequent tectonic movement suggests that faulting is the main reason for various geological processes that influence petroleum generation, migration, accumulation and distribution in Chinese oil-bearing basins. The exploration concept based on fault controlling hydrocarbon theory is: take faults as the main control factor, find hydrocarbon controlling faults such as source-controlling faults and trap-controlling faults as well as seal faults, analyze their petroleum migration and accumulation potential, evaluate trap properties and determine the exploration targets.copy; 2010 Research Institute of Petroleum Exploration & Development, PetroChina.

Liu Y.,China University of Petroleum - Beijing
Geophysics | Year: 2013

Spatial finite-difference (FD) coefficients are usually determined by the Taylor-series expansion (TE) or optimization methods. The former can provide high accuracy on a smaller wavenumber or frequency zone, and the latter can give moderate accuracy on a larger zone. Present optimization methods applied to calculate FD coefficients are generally gradient-like or global optimization-like algorithms, and thus iterations are involved. They are more computationally expensive, and sometimes the global solution may not be found. I examined second-order spatial derivatives and computed the optimized spatial FD coefficients over the given wavenumber range using the least-squares (LS) method. The results indicated that the FD accuracy increased with increasing operator length and decreasing wavenumber range. Therefore, for the given error and operator length, globally optimal spatial FD coefficients can be easily obtained. Some optimal FD coefficients were given. I developed schemes to obtain optimized LS-based spatial FD coefficients by minimizing the relative error of space-domain dispersion relation for second-order derivatives and time-space-domain dispersion relation for the acoustic wave equation. I discovered that minimizing the relative error of the space-domain dispersion relation provides less phase velocity error for small wavenumbers, compared to minimizing the absolute error. I also found that minimizing the relative error of the time-space-domain dispersion relation can reduce relative errors of phase velocity. Accuracy analysis demonstrated the correctness and advantage of schemes. I gave three examples of 2D acoustic FD modeling for a homogeneous, a large velocity-contrast, and a heterogeneous model, respectively. LS-based spatial FD operators have variable lengths for different velocities. Modeling examples demonstrated that the proposed LS-based FD scheme can maintain the same modeling precision while using a shorter spatial FD operator length, thus reducing the computation cost relative to conventional TEbased FD schemes, particularly for the higher order. © 2013 Society of Exploration Geophysicists.

Wang G.-L.,China University of Petroleum - Beijing
Zhongguo Shiyou Daxue Xuebao (Ziran Kexue Ban)/Journal of China University of Petroleum (Edition of Natural Science) | Year: 2010

Based on the theory and methodology of molecular organic geochemistry, molecular paleontology and its depositional environment in the Eocene Shahejie formation of Jiyang depression, Bohai Bay Basin, East China, were studied. The results show that the types of molecular fossils vary significantly on level whereas cycle on vertical. Molecular heterogeneousness of member 1 and 3 of Shahejie formation (Es1, Es3) is weaker than that of the upper part of member 4 (Es4 u) on level. The scale of lake basin of Es1 and Es3 is the largest, and the basin segmentation of Es4 u is strong. Photic euxinic conditions prevailed in the paleowater column during the Eocene lacustrine. Both dinoflagellates and bacteria were significant phytoplanktons in addition to coccolithophoride limited to brackish water lakes of Es1 and Es4 u.

Liu Y.,China University of Petroleum - Beijing
Natural Gas Industry | Year: 2010

Gas famine has aroused public concern all over China, reflecting the risks present and the different problems in the natural gas industrial chain. Key factors influencing gas famine include the stage of development accompanying the imbalance between supply and demand; specific driving force triggering the imbalance between supply and demand, e.g., competition; and unique developing trajectory, which aggregates the imbalance between supply and demand. Risk mitigation measures are put forward. These include a full plan that should be developed for the whole industrial chain; peak-valley adjustment mechanism for the whole chain; a reformed gas pricing system; and the introduction of a competitive system into the industrial chain via new reforms.

Zhang Y.,China University of Petroleum - Beijing
International Journal of Chemical Reactor Engineering | Year: 2016

In gas-solids risers of fast fluidization regime, the gross particle flux determined by integrating the product of the measured average particle concentration and velocity is always found several times or even larger than that measured by direct experimental methods. Based on analysis of the measurement mechanisms and a simple model for two-phase flow structure in gas-solids risers, this big unidirectional deviation is first explained in depth in this study. It is concluded that the unique two-phase flow structure (i.e. the low-velocity dense phase and high-velocity dilute phase in a gas-solids riser) and the bad coupling quality of the measured transient particle concentration and velocity during data processing lead to this big unidirectional deviation. Finally, this explanation is extended to wider multiphase flow systems and advices are proposed in measuring phase fluxes. © 2016 by De Gruyter 2016.

Wang Y.,China University of Petroleum - Beijing | Sun S.,King Abdullah University of Science and Technology
Communications in Computational Physics | Year: 2016

Velocity of fluid flow in underground porous media is 6~12 orders of magnitudes lower than that in pipelines. If numerical errors are not carefully controlled in this kind of simulations, high distortion of the final results may occur [1-4]. To fit the high accuracy demands of fluid flow simulations in porous media, traditional finite difference methods and numerical integration methods are discussed and corresponding high-accurate methods are developed. When applied to the direct calculation of full-tensor permeability for underground flow, the high-accurate finite difference method is confirmed to have numerical error as low as 10-5% while the high-accurate numerical integration method has numerical error around 0%. Thus, the approach combining the high-accurate finite difference and numerical integration methods is a reliable way to efficiently determine the characteristics of general full-tensor permeability such as maximum and minimum permeability components, principal direction and anisotropic ratio. Copyright © Global-Science Press 2016.

Zhang J.,Heriot - Watt University | Zhang J.,China University of Petroleum - Beijing
Fuel | Year: 2014

Some coal seam is well known for its three low characteristics: low permeability, low reservoir pressure and low gas saturation. Thus stimulation measures must be taken during coalbed methane development stage to enhance its recovery. Hydraulic fracturing transformation technology is an effective method for increasing coalbed methane production. This paper presents a two-phase, 3D flow and hydraulic fracturing model of dual-porosity media based on the theories of oil-gas geology and mechanics of flow through porous media. Correspondingly, a finite difference numerical model has been developed and applied successfully to a coalbed methane reservoir. Well test data from one western China basin is utilized for simulation. Results show that hydraulic fracturing promotes desorption and diffusion of coalbed methane which in turn substantially increases production of coalbed methane. © 2014 Elsevier Ltd. All rights reserved.

Liu Z.-W.,China National Petroleum Corporation | Sa L.-M.,China National Petroleum Corporation | Yang X.,China National Petroleum Corporation | Li X.-Y.,China University of Petroleum - Beijing
Shiyou Diqiu Wuli Kantan/Oil Geophysical Prospecting | Year: 2011

As the needs of low carbon economics and the demands of clear energy keep increasing, shale gas exploration has greatly developed in recent years, especially in North America. With enormous potential reserves and bright prospect, shale gas exploration in China draws more attention of the industry. At present, the exploration and development in our country is still in the primary stage. Functions of exploration geophysics in the domains remain unclear. With analysis of requirements of geophysical technologies in shale gas E&P, this paper discuss a few key methods for reservoir characterization and production improvement, which will pay an important role in shale gas E&P in the future.

Yang M.,Xian Jiaotong University | Feng X.,China University of Petroleum - Beijing | Chu K.H.,Xian Jiaotong University
Industrial and Engineering Chemistry Research | Year: 2013

Setting heat pumps correctly in a chemical process system can enhance the energy utilization ratio of the system, reduce the consumption of both the hot and cold utilities, and achieve utility savings and economic benefits. In this paper, for the case of introducing a single heat pump into a system, the dynamic changes of the grand composite curve and pinch temperature under different scenarios are analyzed using a graphical analysis method. The reasons and conditions for such changes are determined. It is shown that for cases that exhibit a change in pinch temperature more hot and cold utility savings may be obtained by using two heat pumps. Existing as well as new two-heat-pump arrangements that comply with the cross-pinch rule are presented. © 2013 American Chemical Society.

Zhou Q.,China University of Petroleum - Beijing | Lin H.,Jilin Municipal Research Institute of Environmental science
Clean - Soil, Air, Water | Year: 2013

Nanoscale zerovalent iron (NZVI) has been proved to be effective in the degradation of environmental pollutants and exhibits advantages in the removal of 1-(2-chlorobenzoyl)-3-(4-chlorophenyl) urea (CCU), an analog of diflubenzuron. This present study focused on the influence of surfactants in the degradation procedure with NZVI in order to provide a simple and rapid removal method for CCU. Triton X-100, Tween 20, Tween 80, sodium dodecyl sulfonate (SDS), and cetyltrimethylammonium bromide (CTAB) were investigated under anaerobic conditions. The experimental results demonstrated that the degradation rate increased sharply with the presence of SD during the first 15min, up to 99.97% with addition of 0.01gL-1 SDS, whereas the presence of Triton X-100, Tween 80, and Tween 20 resulted in a slight enhancement of the degradation of CCU. The enhancement strength of them was in the order Tween 20, Triton X-100, and Tween 80. However, addition of the cationic surfactant CTAB resulted in a significant inhibitive effect. In contrast, the mixed surfactants did not result in the expected performance, and the performance was lower than that using some certain single surfactant among the mixed surfactants. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Zhu W.,Jiangsu University | Zhu G.,Jiangsu University | Li H.,Jiangsu University | Chao Y.,Jiangsu University | And 4 more authors.
Fuel Processing Technology | Year: 2013

Surfactant-type polyoxometalate-based ionic liquids (SPILs), such as [(n-C8H17)3NCH3]3{PO 4[MoO(O2)2]4}, [(n-C 12H25)3NCH3]3{PO 4[MoO(O2)2]4}, [(n-C 8H17)3NCH3]3{PO 4[WO(O2)2]4} and [(n-C 12H25)3NCH3]3{PO 4[WO(O2)2]4} have been investigated on their oxidative desulfurization. SPILs were very promising for the desulfurization of DBT in the model oil using H2O2 as the oxidant. Supposed mechanism and kinetics studies on the catalytic avtivity of SPIL [(n-C8H17)3NCH3] 3{PO4[MoO(O2)2]4} revealed that the oxidative desulfurization of organosulfur compounds could present a pseudo first-order kinetic. The reaction rate constant and half-life of DBT oxidation were calculated. Moreover, the catalytic activity for other sulfur-containing compounds increased in the order BT < 4, 6-DMDBT < DBT. There is little change for the oxidative desulfurization efficiency of SPIL after 8 recycles. And this work offers an alternative for oxidative desulfurization of actual prehydrotreated fuel as well. © 2012 Elsevier B.V.

An C.,China University of Petroleum - Beijing | An C.,Federal University of Rio de Janeiro | Su J.,Federal University of Rio de Janeiro
Applied Thermal Engineering | Year: 2013

In this study, a lumped parameter model was developed for one-dimensional heat conduction with melting of a phase change material (PCM) slab with volumetric heat generation. Two types of boundary conditions were considered: (a) adiabatic condition at the left side and isothermal condition at the right side and (b) isothermal condition at the left side and convective condition at the right side. The lumped model was obtained through two-point Hermite approximations for integrals. The two-side corrected trapezoidal rule (H 1,1 approximation) was employed in the averaged temperature integrals for both the liquid and solid phases during melting process of the slab, and the plain trapezoidal rule (H0,0 approximation) was used to estimate the heat fluxes. For the melting problem with the boundary conditions (a), the lumped model results were verified by the analytical solution of melting in half-plane without internal heat source. Case study was performed to investigate the effect of the volumetric energy generation and the Stefan number on the instantaneous interface position. For the melting problem with the boundary conditions (b), the lumped model results were verified by the enthalpy method solution. Transient heat condition of the PCM slab was analyzed to illustrate the applicability of the proposed lumped model, with respect to different values of the volumetric energy generation, the Stefan number, the Biot number, the liquid-to-solid thermal conductivity ratio and the boundary temperature at the left side. Excellent agreement with available analytical or numerical solutions was achieved. © 2013 Published by Elsevier Ltd.

Wu W.,Shanghai JiaoTong University | Cai J.,Shanghai JiaoTong University | Cai J.,China University of Petroleum - Beijing | Liu R.,Shanghai JiaoTong University
Industrial and Engineering Chemistry Research | Year: 2013

Seven different distributed activation energy model (DAEM) processes, which were used to describe the pyrolysis kinetics of wood, algae, lignin, corn stalk skin, kerogen, cellulose, and coal, were analyzed by means of the Friedman differential isoconversional method. It has been shown that the activation energies obtained from the Friedman method are independent of the heating rate. For all DAEM processes considered, the effect activation energies evaluated by the Friedman isoconversional method showed significant dependence on the conversion. The kinetic parameters obtained by means of the Friedman isoconversional method were used to reconstruct the conversions and rates data. The agreement between the reconstructed data and the data calculated by the DAEM is excellent at the presimulated and extrapolated conditions for all the DAEM processes. This indicates the DAEM process can be taken as an example to check the accuracy of some integral isoconversional methods in the determination of the activation energy. © 2013 American Chemical Society.

Ye H.-M.,Tsinghua University | Ye H.-M.,China University of Petroleum - Beijing | Tang Y.-R.,Tsinghua University | Xu J.,Tsinghua University | Guo B.-H.,Tsinghua University
Industrial and Engineering Chemistry Research | Year: 2013

The details of poly(butylene fumarate) (PBF) as highly effective nucleating agent for poly(butylene succinate) (PBS) were systematically studied via X-ray diffraction, differential scanning calorimeter, polarized optical microscopy, and atom force microscopy. All results show that PBF can significantly improve the melt-crystallization temperature and the degree of crystallinity of PBS during the nonisothermal crystallization process. Both crystallization time span and spherulitic size of PBS decrease drastically with the addition of a small amount of PBF, which shows that PBF not only enhances the primary nucleation of PBS by epitaxial mechanism, but also greatly accelerates the secondary nucleation during spherulite growth. The secondary nucleation parameters of PBS, Kg and G0, are notably improved just with a small amount of PBF. Furthermore, the appearance of wrinkles on PBF-nucleated PBS ultrathin film visually suggests that PBF indeed affects the subsequent growth behavior, besides the primary nucleation. © 2013 American Chemical Society.

Zhang K.,North China Electrical Power University | Chang J.,North China Electrical Power University | Guan Y.,China University of Petroleum - Beijing | Chen H.,North China Electrical Power University | And 2 more authors.
Renewable Energy | Year: 2013

With the critical worldwide energy shortage and global environment concern, lignocellulosic biomass is regarded as one of the potential renewable energy resources to substitute conventional fossil fuels. Among various thermo-chemical conversion technologies, gasification is now regarded as an advanced and efficient method. Based on the mechanism of biomass gasification, this paper outlines different types of gasifiers that have been developed in China. Air gasification technology has been employed in the rural areas or forestry/agricultural processing entities. Obviously, the product gas for cooking and heating can significantly upgrade the living standard of rural residents. The product gas for heating boiler and generating electricity benefits the forest or agricultural processing enterprises. For China's sustainable development of energy and environment, multi-cogeneration of heat, electricity and liquid fuels together with chemical feedstock will be a potential direction for efficiently utilizing product gas from lignocellulosic biomass. This means oxygen (including oxygen-enriched air) gasification and steam gasification should be taken into more consideration. © 2012 Elsevier Ltd.

Salama A.,King Abdullah University of Science and Technology | Li W.,China University of Petroleum - Beijing | Sun S.,King Abdullah University of Science and Technology
Journal of Hydrology | Year: 2013

In this work the problem of flow in three-dimensional, axisymmetric, heterogeneous porous medium domain is investigated numerically. For this system, it is natural to use cylindrical coordinate system, which is useful in describing phenomena that have some rotational symmetry about the longitudinal axis. This can happen in porous media, for example, in the vicinity of production/injection wells. The basic feature of this system is the fact that the flux component (volume flow rate per unit area) in the radial direction is changing because of the continuous change of the area. In this case, variables change rapidly closer to the axis of symmetry and this requires the mesh to be denser. In this work, we generalize a methodology that allows coarser mesh to be used and yet yields accurate results. This method is based on constructing local analytical solution in each cell in the radial direction and moves the derivatives in the other directions to the source term. A new expression for the harmonic mean of the hydraulic conductivity in the radial direction is developed. Apparently, this approach conforms to the analytical solution for uni-directional flows in radial direction in homogeneous porous media. For the case when the porous medium is heterogeneous or the boundary conditions is more complex, comparing with the mesh-independent solution, this approach requires only coarser mesh to arrive at this solution while the traditional methods require more denser mesh. Comparisons for different hydraulic conductivity scenarios and boundary conditions have also been introduced. © 2013 Elsevier B.V.

Wang X.,University of Wyoming | Wang X.,China University of Petroleum - Beijing | Alvarado V.,University of Wyoming | Swoboda-Colberg N.,University of Wyoming | Kaszuba J.P.,University of Wyoming
Energy Conversion and Management | Year: 2013

Carbon dioxide injection in porous reservoirs is the basis for carbon capture and storage, enhanced oil and gas recovery. Injected carbon dioxide is stored at multiple scales in porous media, from the pore-level as a residual phase to large scales as macroscopic accumulations by the injection site, under the caprock and at reservoir internal capillary pressure barriers. These carbon dioxide saturation zones create regions across which the full spectrum of mutual CO2-H2O solubility may occur. Most studies assume that geochemical reaction is restricted to rocks and carbon dioxide-saturated formation waters, but this paradigm ignores injection of anhydrous carbon dioxide against brine and water-alternating-gas flooding for enhanced oil recovery. A series of laboratory experiments was performed to evaluate the reactivity of the common reservoir mineral dolomite with water-saturated supercritical carbon dioxide. Experiments were conducted at reservoir conditions (55 and 110 °C, 25 MPa) and elevated temperature (220 °C, 25 MPa) for approximately 96 and 164 h (4 and 7 days). Dolomite dissolves and new carbonate mineral precipitates by reaction with water-saturated supercritical carbon dioxide. Dolomite does not react with anhydrous supercritical carbon dioxide. Temperature and reaction time control the composition, morphology, and extent of formation of new carbonate minerals. Mineral dissolution and re-precipitation due to reaction with water-saturated carbon dioxide may affect the contact line between phases, the carbon dioxide contact angle, and the relative permeability and permeability distribution of the reservoir. These changes influence fundamental properties of hysteresis of drainage and imbibition cycles, rock wettability, and capillary pressure. The efficacy of physical carbon dioxide trapping mechanisms, integrity of caprock, and injectivity of a carbon dioxide storage reservoir as well as the injectivity and production rate of an enhanced oil recovery operation may be affected. © 2012 Elsevier Ltd. All rights reserved.

Zhou Q.,China University of Petroleum - Beijing | Zhou Q.,Henan Normal University | Gao Y.,Henan Normal University
Analytical Methods | Year: 2014

The present study describes a simple and sensitive method for the determination of polycyclic aromatic hydrocarbons (PAHs) in water samples by temperature-controlled ionic liquid dispersive liquid-liquid microextraction prior to high performance liquid chromatography with an ultraviolet detector. Three ionic liquids including 1-hexyl-3-methylimidazolium hexafluorophosphate [C6MIM][PF6], 1-benzyl-3-methylimidazolium hexafluorophosphate [C7MIM][PF6] and 1-octyl-3- methylimidazolium hexafluorophosphate [C8MIM][PF6] were investigated for enrichment, and the experimental results indicated that the best extraction efficiencies were achieved when [C8MIM][PF 6] was used as the extraction solvent. Other factors affecting the extraction efficiency such as the volume of ionic liquid, heating temperature, extraction time, addition of 2-propanol, centrifugation time and ionic strength were also optimized. Under the optimal conditions, the detection limits of PAHs were in the range of 0.0005-0.88 μg L-1. The intra-day and inter-day precisions of the proposed method (RSDs, n = 6) were in the range of 2.7-7.4% and 5.5-11.4%, respectively. The proposed method was applied to the analysis of real environmental water samples and good spiked recoveries in the range of 83.5-118% were achieved. All these results indicate that the proposed method is a viable alternative to existing methods and would be very useful in the future. © 2014 the Partner Organisations.

Zhang C.,Tsinghua University | Dong X.,Tsinghua University | Dong X.,China University of Petroleum - Beijing | Feng X.,Tsinghua University | Hwang K.-C.,Tsinghua University
Optics Letters | Year: 2013

Multiwavelength shearing interferometry, a full-field, real-time, and vibration-insensitive method with enhanced accuracy, is proposed. Theoretically, the more wavelengths that are used for shearing interferometers, the higher the precision that can be achieved in the measurement of slopes, curvatures, and the shapes of reflective surfaces. A spherical mirror with specified curvature radius is used to calibrate this method, and then the nonuniform deformation and shape of the TiNi film/Si substrate system are obtained experimentally. © 2013 Optical Society of America.

Chen W.-T.,University of Illinois at Urbana - Champaign | Zhang Y.,University of Illinois at Urbana - Champaign | Zhang J.,University of Illinois at Urbana - Champaign | Zhang J.,China University of Petroleum - Beijing | And 4 more authors.
Applied Energy | Year: 2014

This study explored the feasibility of combining two types of feedstocks, swine manure (SW) and mixed-culture algae (AW) from wastewater treatment systems, for bio-crude oil production via hydrothermal liquefaction. The effect of feedstock combination ratios on the bio-crude oil yields and qualities were investigated. SW to AW ratios (dry weight basis) were 1:3, 1:1 and 3:1 with a total solids content of 25%. Pure SW and AW were also hydrothermally converted at the same reaction condition for comparison. By combining 75% SW with 25% AW, the highest bio-crude oil yield was achieved (35.7% based on dry matter). By mixing 25% SW with 75% AW, the highest heating value (27.5. MJ/kg) was obtained. GC-MS spectra and thermal gravimetric analysis of bio-crude oils revealed that both light oils and heavy crude were produced, averaging 25% and 20% of the bio-crude oil, respectively. Analysis of energy consumption ratios indicated that co-liquefaction of AW and SW is energetically feasible and could be an economically competitive system for bio-crude oil production. © 2014 Elsevier Ltd.

An C.,China University of Petroleum - Beijing | Su J.,Federal University of Rio de Janeiro
Nuclear Engineering and Design | Year: 2015

In this paper, the dynamic behavior of pipes conveying gas-liquid two-phase flow was analytically and numerically investigated on the basis of the generalized integral transform technique (GITT). The use of the GITT approach in the analysis of the transverse vibration equation lead to a coupled system of second order differential equations in the dimensionless temporal variable. The Mathematica's built-in function, NDSolve, was employed to numerically solve the resulting transformed ODE system. The characteristics of gas-liquid two-phase flow were represented by a slip-ratio factor model that was devised and used for similar problems. Good convergence behavior of the proposed eigenfunction expansions is demonstrated for calculating the transverse displacement at various points of pipes conveying air-water two-phase flow. Parametric studies were performed to analyze the effects of the volumetric gas fraction and the volumetric flow rate on the dynamic behavior of pipes conveying air-water two-phase flow. Besides, the normalized volumetric-flow-rate stability envelope for the dynamic system was obtained. © 2015 Elsevier B.V. All rights reserved.

Liu R.,CAS Research Center for Eco Environmental Sciences | Sun J.-F.,CAS Research Center for Eco Environmental Sciences | Cao D.,CAS Research Center for Eco Environmental Sciences | Zhang L.-Q.,China University of Petroleum - Beijing | And 2 more authors.
Chemical Communications | Year: 2015

In this report, we propose and demonstrate the fabrication of a highly-specific SERS substrate, which was achieved by the co-precipitation of functional materials, such as nanosorbents and nanocatalysts, into Ag nanoporous films. Based on the nanostructures developed, we performed the ultrasensitive detection of arsenic ions by SERS and monitored the catalyzed reactions using real-time SERS. This journal is © The Royal Society of Chemistry 2015.

Pang Z.-X.,China University of Petroleum - Beijing | Pang Z.-X.,MOE Key Laboratory of Petroleum Engineering
Transport in Porous Media | Year: 2010

Foam flow experiments were carried out to study the influence factors such as surfactant concentration, foam quality, injection rate of liquid and gas, permeability of porous media, temperature, and oil saturation on blocking ability and flowing characteristics of steady foams in porous media. Foam blocking mechanisms and flowing characteristics were summarized according to the experimental results and foam migration behavior. The results showed that the pressure distribution of flowing foams was linearly descending in porous media at steady state. The results further showed that the foam size and quality in pores along the sand pack were almost uniform, that is, foam generation and destruction gradually reached dynamic equilibrium at steady state. In porous media, the blocking ability of steady foams increased with the concentration of the foaming agent and the increase in the permeability of porous media, but the blocking ability decreased with the increase in the temperature, the shearing rate, and the oil saturation of the porous media. Foam resistance factor reached maximal value at the foam quality of 85% in porous media. © 2010 Springer Science+Business Media B.V.

Tsukahara T.,Tokyo University of Science | Ishigami T.,Tokyo University of Science | Yu B.,China University of Petroleum - Beijing | Kawaguchi Y.,Tokyo University of Science
Journal of Turbulence | Year: 2011

The effect of viscoelastic contribution on wall-bounded turbulent flow of drag-reducing surfactant solution is investigated through direct numerical simulations (DNS). A series of DNS on turbulent channel flow is performed for different rheological properties at two different Reynolds numbers. It is found that high drag reduction is achieved by suppressing the turbulent contribution for the high Weissenberg number, and/or by decreasing the viscosity ratio and the effective viscosity.Ahighly drag-reduced turbulent flow at a high Reynolds number is mainly caused by the viscoelastic effect in the elastic layer, whereas the outer layer flow hardly affects the drag reduction. Moreover, we focus on the viscoelastic contribution term in the budget of Reynolds stress and its relation to the local flow pattern. It is shown that in the near-wall region of the highly drag-reduced flow a positive work done by viscoelastic stress is closely associated with vortex stretching that produces turbulent kinetic energy from stored elastic energy, whereas a negative one causes vortex compression. © 2011 Taylor & Francis.

Niu F.,China University of Petroleum - Beijing | Niu F.,Rice University
Earth and Planetary Science Letters | Year: 2014

We observe a clear seismic arrival at ~35-45. s after the direct P wave in USArray recordings of two deep earthquakes occurring beneath northeast China. Velocity-spectrum and beam-forming analyses reveal that this arrival has a lower slowness value than the direct P wave and a back azimuth slightly different from the great-circle direction. The measured slowness and arrival time indicate that it is a transmitted S to P conversion from structures below the sources. We employ the common-conversion-point (CCP) stacking and diffraction migration methods to determine the location and geometric features of the seismic structures. The CCP stacking image indicates that the structure is a localized discontinuity at ~1000. km with a dimension at ~200. km by ~50. km along the E-W and N-S directions, respectively. It is located at ~150. km northeast to the two events. The 2D migrated images, on the other hand, indicate that the sources structure are reflectors dipping northeastwards by ~17° at a slightly shallower depths. The reflectors have a length scale of ~100. km ant their centers are ~50. km away from the epicenters of the two earthquakes. Forward waveform modeling suggests that the dipping reflectors may be thin layers with a thickness of few kilometers. The layers have a lower shear velocity and a higher density than that of the surrounding mantle, which matches well with those predicted for mid-ocean-ridge basalt (MORB) at mid-mantle depths, according to a recent ab initio study. Combined with the results from previous studies, our observations here suggest that the former oceanic crust may be ubiquitously present in the lower mantle beneath subduction zones. © 2013 Elsevier B.V.

Chen M.,Massachusetts Institute of Technology | Chen M.,Rice University | Huang H.,Massachusetts Institute of Technology | Yao H.,Massachusetts Institute of Technology | And 4 more authors.
Geophysical Research Letters | Year: 2014

We present a refined 3D crustal model beneath SE Tibet from ambient noise adjoint tomography. Different from ray-theory-based tomography, adjoint tomography in this study incorporates a spectral-element method (SEM) and takes empirical Green's functions (EGFs) of Rayleigh waves from ambient noise interferometry as the direct observation. The frequency-dependent traveltime misfits between SEM synthetic Green's functions and EGFs are minimized with a preconditioned conjugate gradient method, meanwhile the 3D model gets improved iteratively utilizing 3D finite-frequency kernels. The new model shows 3 - 6% shear wave speed increasing beneath the western Sichuan Basin (SCB) (depth > 15 km) and the central Chuan-Dian Block (CDB), and 6 - 12% shear wave speed reduction in the mid-lower crust beneath the northern and the southern CDB. The inferred spatial pattern of low wave speed zones, consistent with possible partial melt, suggests more complex and disconnected geometry than the pervasive narrow zone from the channel flow models. ©2013. American Geophysical Union. All Rights Reserved.

Li K.,China University of Petroleum - Beijing
Computer Aided Chemical Engineering | Year: 2012

A new internal model control (IMC) based robust PID tuning method for second order plus time delay (SOPTD) systems is developed to meet specified gain and phase margins (GPM). The exact open-loop amplitude ratio and phase change equations are derived based on frequency analysis. The tuning method based on IMC with constraints on GPM and closed-loop overshoot ratio is further given. The method is demonstrated in simulation examples and compared with previous work on this topic. © 2012 Elsevier B.V.

Wang S.-D.,China University of Petroleum - Beijing
Applied Geophysics | Year: 2011

Attenuation compensation, which corrects the attenuation and dispersion of seismic waves, is one of the effective methods for improving seismic data resolution. In general, the attenuation compensation is achieved by an inverse Q-filter based on wave field continuation. In this paper, using the Futterman attenuation model, a method to compute synthetic seismogram is derived for an attenuation medium. Based on the synthetic method, the attenuation compensation problem is reduced to an inversion problem of the Fredholm integral equation and can be achieved by inversion. The Tikhonov regularization is used to improve inversion stability. The processing results of numerical simulation and real data show the effectiveness of the method. © 2011 Editorial Office of Applied Geophysics and Springer-Verlag Berlin Heidelberg.

Zhou Y.Y.,China University of Petroleum - Beijing | Lu C.F.,Zhejiang University | Chen W.Q.,Zhejiang University
Composite Structures | Year: 2012

Bulk wave propagation in laminated piezomagnetic/piezoelectric plates with initial stresses and imperfect interface is investigated using the state space approach. Either electrically and magnetically open or shorted conditions on the top and bottom surfaces are considered. The phase velocity and frequency spectra of the wave are numerically calculated for various electric and magnetic conditions, and normalized modes are also analyzed. Although numerical results do indicate that the initial compressive stress can reduce the phase velocity of the wave propagating in a layered multiferroic structure, the effect is not as obvious as that reported in literature where the initial stresses were taken far beyond the strength of real materials. While the imperfect interface affect the frequency spectra much greater than initial stresses, because imperfection decreases the structural stiffness. © 2012 Elsevier Ltd.

Tianfeng Z.,China University of Petroleum - Beijing | Zhigang T.,Exmar Offshore Company
Applied Ocean Research | Year: 2016

As an ideal use of corrosion-resistant alloys and low-alloy steels, Mechanically Lined Pipelines (MLPs) have been employed gradually for offshore exploitation. If the risk of thin-walled liner wrinkling is to be effectively averted, reel-lay is the most economical installation method for this type of pipeline, especially for deepwater oil and gas development. A suite of tools and corresponding techniques is proposed in this paper to realize the spooling-on of an MLP stalk with inner pressure to avoid detachment and wrinkling of the MLP liner. Additionally, The related numerical verification and a prototype test for a 5-in. MLP spooling-on tool are completed to prove the validity of this new technique and further illustrate the application effect of providing internal pressure during the spooling-on of MLP stalk to a reel. © 2016 Elsevier Ltd.

Yunhua G.,China University of Petroleum - Beijing
Hydraulic Engineering - Proceedings of the 2012 SREE Conference on Hydraulic Engineering, CHE 2012 and 2nd SREE Workshop on Environment and Safety Engineering, WESE 2012 | Year: 2013

In order to find out defects in safety management and improve safety management in enterprises, enterprise safety management diagnosis was developed. It was essential to define what should be diagnosed to implement safety management diagnosis. So, a safety management Diagnosis Item (DI) system was developed. The item system nearly covered all aspects of enterprise safety management. According to enterprise diagnosis theories, diagnosis procedure was provided, which was composed of diagnosis preparation, initial diagnosis, formal diagnosis and guidance conduction. Four diagnosis methods were proposed, which were document inspection, questionnaire survey, interviews and statistical analysis. There were three safety management diagnosis conclusion patterns in diagnosing, which were comprehensive diagnosis conclusion, item diagnosis conclusion and particular problem analysis. The comprehensive diagnosis conclusion was obtained by Fuzzy Comprehensive Evaluation. © 2013 Taylor & Francis Group.

Wang R.,Beijing University of Technology | He H.,Beijing University of Technology | Liu L.-C.,Beijing University of Technology | Dai H.-X.,Beijing University of Technology | Zhao Z.,China University of Petroleum - Beijing
Catalysis Science and Technology | Year: 2012

It is of great interest to study the shape effect on the catalytic activity of metal nanocrystals, which exposed different crystallographic facets upon adopting various shapes. The investigations on shape-dependent catalysis of supported metal nanocrystals need to be conducted over nanocrystals with well-defined shapes and cleaned surface. The palladium nanocrystals with cubic, octahedral, and spherical morphologies were synthesized and well dispersed onto the inert silica support after removing the capping agents, which were used as the heterogeneous catalysts for carbon monoxide (CO) oxidation. It was found that the crystal facets of Pd nanoparticles played an essential role in determining the catalytic oxidation properties. As a result, the octahedral and spherical nanoparticles that predominantly exposed the Pd {111} crystal facets exhibited significantly better catalytic activity than the palladium nanocubes that possessed the Pd {100} crystal facets as the basal plane for the CO catalytic oxidation. It was inferred that the appropriate adsorption strength of CO molecules on Pd {111} planes was beneficial to the enhancement of the catalytic activity. © 2012 The Royal Society of Chemistry.

Zhou Q.-X.,China University of Petroleum - Beijing | Gao Y.-Y.,Nankai University
Chinese Chemical Letters | Year: 2014

A temperature-controlled ionic liquid dispersive liquid-phase microextraction in combination with high performance liquid chromatography was developed for the enrichment and determination of triazine herbicides such as cyanazine, simazine, and atrazine in water samples. 1-Octyl-3-methylimidazolium hexafluorophosphate ([C8MIM][PF6]) was selected as the extraction solvent. Several experimental parameters were optimized. Under the optimal conditions, the linear range for cyanazine was in the concentration range of 0.5-80 μg/L and the linear range for simazine and atrazine was in the range of 1.0-100 μg/L. The limit of detection (LOD, S/N = 3) was in the ranges of 0.05-0.06 μg/L, and the intra day and inter day precision (RSDs, n = 6) was in the ranges of 3.2%-6.6% and 4.8%-8.9%, respectively. Four real water samples were analyzed with the developed method, and the experimental results showed that the spiked recoveries were satisfactory. All these exhibited that the developed method was a valuable tool for monitoring such pollutants. © 2014 Qing-Xiang Zhou. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

Li M.,China University of Petroleum - Beijing
Advances in Information Sciences and Service Sciences | Year: 2012

The quality of knowledge in the knowledge repository determines the effects of knowledge reusing and sharing. In knowledge management systems (KMS), knowledge maintenance events are recorded in process logs. In order to take knowledge maintenance process logs to discover process, control, organizational, and social structure and construct a more appropriate knowledge maintenance process model, process mining is applied to the knowledge maintenance. The paper demonstrates the applicability of process mining using a real case of a knowledge maintenance process in an aviation design institute. In this paper, we analyzed the knowledge maintenance from two different perspectives: (1) the process perspective, which is used to find a good characterization of knowledge maintenance tasks and paths and (2) the organizational perspective which is used to find relations between individual performers. The results show that process mining can be used to provide new insights that facilitate the improvement of existing knowledge maintenance process.

In this letter we explore the propagation behavior of permeability reduction due to particulate transport in heterogeneous porous media. By simulating an advection-dispersion-based model we find that an attenuating sequence exists in terms of the propagation of particle concentration, permeability reduction and heterogeneity perturbation. The advancing speed of the fronts of the mentioned physical quantities attenuates successively from const to to (where n > 1 and t denotes time) regardless of the heterogeneity patterns. Then we move on to discuss the micro-dynamics of the propagation sequence, involving how it originates and how it connects with the macroscopic results. Moreover, exploiting the propagation mechanism enables us to know the condition under which we can apply the hypothesis of media homogeneity to describe the behavior of the particulate transport system in porous media. © CopyrightEPLA, 2016.

Liu G.,Xian Jiaotong University | Li H.,WISDRI Engineering and Research Incorporation Ltd Company | Feng X.,Xian Jiaotong University | Deng C.,China University of Petroleum - Beijing
AIChE Journal | Year: 2013

The purification reuse/recycle is one effective resource conservation strategy. In this article, a novel conceptual method is proposed to identify the optimal purification feed flow rate (PFFR) and the corresponding maximum hydrogen utility savings (HUS) of the hydrogen network with purification reuse/recycle. In this method, the sources and sink-tie-lines are divided into three regions according to the purified product and purification feed. The quantitative relationship between the HUS and the PFFR is analyzed for the sink-tie-lines and sources of each region. With the quantitative relationship line between the HUS and the PFFR of each source plotted, the quantitative relationship diagram can be obtained and can be used to identify the pinch point and the HUS for a given PFFR. Furthermore, the optimal PFFR and the maximum HUS can be identified easily. Three cases are studied to illustrate the applicability of the proposed method. © 2012 American Institute of Chemical Engineers (AIChE).

An Z.,CAS Institute of Computing Technology | An Z.,University of Chinese Academy of Sciences | Zhu H.,CAS Institute of Software | Li X.,University of North Texas | And 3 more authors.
IEEE Transactions on Industrial Electronics | Year: 2011

Similar to other cyber infrastructure systems, as wireless sensor networks become larger and more complex, many classic algorithms may no longer work efficiently. This paper presents a wireless sensor network time synchronization model that was initially inspired by synchronous flashing of fireflies. Synchronous flashing of fireflies is an interesting phenomenon that has been studied for decades. A variety of models have been proposed to explain this phenomenon, among which is the pulse-coupled oscillators model that models fireflies as oscillators. The oscillators in such a model interact only through discrete pulses, similar to the flashing of fireflies. In this paper, we propose a new nonidentical linear pulse-coupled oscillators model and use the model to analyze synchronization of pulse-coupled oscillators with different frequencies. The conditions to achieve and maintain synchronization are derived, and then, the results are used to prove that the oscillators in the model can achieve synchronization eventually, except for a set of frequencies with zero Lebesgue measure. Furthermore, through simulations and implementation on a wireless sensor network testbed, we demonstrate that the proposed nonidentical linear pulse-coupled oscillators model can be used in designing lightweight scalable time synchronization protocols for distributed systems. © 2009 IEEE.

An C.,China University of Petroleum - Beijing | Su J.,Federal University of Rio de Janeiro
Applied Thermal Engineering | Year: 2015

In this study, improved lumped parameter models were proposed for transient thermal analysis of multilayered composite pipeline with active heating, which is essential for flow assurance design and operating strategies of deepwater subsea pipelines. Improved lumped models for transient heat conduction in multilayered composite pipelines were based on two-points Hermite approximations for integrals. The transient energy equation for the bulk temperature of the produced fluid was transformed into a set of ordinary differential equations in time by using a finite difference method. The coupled system of ordinary differential equations for average temperatures in the solids and bulk temperature of the fluid at each longitudinal discretization point along the pipeline was solved by using an ODE solver. With the proposed method, we analyzed the transient heat transfer in stainless steel-polypropylene-stainless steel sandwich pipes (SP) with active electrical heating. Convergence behaviors of the average temperature of each layer and the bulk temperature of the produced fluid calculated by using the improved lumped models (H0,0/H1,1 and H1,1/H1,1 approximations) against the number of grid points along the pipelines were presented. Case studies were performed to investigate the effect of the linear rate of power input and the average velocity on the bulk temperature distribution of the produced fluid. © 2015 Elsevier Ltd. All rights reserved.