Time filter

Source Type

This paper presents an optimization model for water quantity and quality integrated management of an urban lake in a water deficient city. A representative water quantity and quality safeguard system served urban lake, including multi-source water supply facilities, recirculating water purification facilities and surplus water discharge facilities, is widely used in Chinese water deficient cities. Because it is complicated, any mismanagement will result in water quality deterioration, water waste and high operation cost. The presented model attempts to achieve the objectives of controlling water pollution, reducing economic cost and improving water utilization efficiency through an optimized operating water safeguard system. The model is applied to Qingjing Lake in Tianjin, China. Results show that the model plays a more positive role for water quantity and quality integrated management. © 2017 Informa UK Limited, trading as Taylor & Francis Group

Xu J.-J.,McGill University | Chen Y.-Q.,Tianjin Chengjian University
Acta Materialia | Year: 2014

The present paper investigates steady spatially periodic eutectic growth during directional solidification with isotropic surface tension in terms of analytical approach. We consider the case when the Péclet number ε is small and the segregation coefficient κ is close to unit, and obtain a family of the global, steady-state solutions with two free parameters: the tilt angle φ and the Péclet number ε. The corresponding interfacial patterns of the steady states are spatially periodic, and may be tilted or non-tilted. The results show that near the triple point, there is a boundary layer Oε12 thick, where the isotropic surface tension plays a significant role, the slope and curvature of interface may be very large and the undercooling temperatures of interface may have a noticeable non-uniformity. Quantitative comparisons between theoretical predictions and recent experimental data are made without making any adjustments to parameters, and show good agreement. © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Deng A.,University of Adelaide | Zhou Y.,Tianjin Chengjian University
Journal of Geotechnical and Geoenvironmental Engineering | Year: 2016

The results of numerical simulations for electroosmosis-surcharge preloading consolidation, obtained using the EC2 model, are presented. EC2 accounts for hydraulic and electroosmotic flows under the conditions of changing physical and geoelectrical properties of saturated compressible porous media. Verification checks for EC2 show excellent agreement of the pore pressure and degree of consolidation with analytical solutions for one- and two-dimensional small-strain consolidation. Similarly, excellent agreement is attained for twodimensional large-strain consolidation occurring to a kaolinite layer subjected to an experimental test. The EC2 model is then used to investigate consolidation optimization for soil layers in three example problems. The electroosmosis-surcharge preloading combined method outperformed single-process methods, particularly where hydraulic conductivity is on an order of magnitude of 10-8 m/s or lower. Applying voltage in steps optimizes electric power usage, as does cutting off the power supply when the degree of consolidation reaches approximately 80%. © 2015 American Society of Civil Engineers.

Deng A.,University of Adelaide | Zhou Y.,Tianjin Chengjian University
Journal of Geotechnical and Geoenvironmental Engineering | Year: 2016

A numerical model, EC2, is developed to simulate the consolidation of a soil layer subjected to combined electroosmosis and surcharge preloading. EC2 includes the capabilities of a previous model, EC1, in accounting for large-strain-induced nonlinear changes in the physical and geoelectrical properties that take place on a layer, with the additions of two-dimensional consolidation, coupled loading and electric fields, time-dependent loading and current density, and an external hydraulic gradient. A highlight of the EC2 model is the superposition of multiple streams between small elements, which improves the prediction accuracy of the rate of flow and the degree of consolidation. The consolidation algorithm of EC2 is one-dimensional and conducted using finite-difference and piecewise-linear methods. This paper presents the theoretical and numerical development of the EC2 model. A companion paper presents the validation of the model and the results of simulations that illustrate the optimization of the consolidating processes for some interesting design scenarios. © 2015 American Society of Civil Engineers.

Pan L.,Tianjin Chengjian University
IEEE Transactions on Power Electronics | Year: 2014

On the basis of the classical Z-source inverter (ZSI), this paper presents a novel ZSI which only contains inductors and diodes in Z-source network. The inverter uses a unique inductor and diode network for boosting its output voltage, provides a common ground for the dc source and inverter, and avoids the disadvantage causing by capacitor in the classical ZSI and SL-ZSI, especially in prohibiting the inrush current at startup and the resonance of Z-source capacitors and inductors. The inverter can increase the boost factor through adjusting shoot-through duty ratio and increasing the number of inductor. The working principle of the proposed ZSI and comparison with the classical ZSI and SL-ZSI are analyzed in detail. Simulation and experimental results are given to demonstrate the operation features of the inverter. © 2014 IEEE.

Zhang Z.,Tianjin Chengjian University | Sun Z.,Tianjin Chengjian University | Duan C.,Tianjin Chengjian University
Energy and Buildings | Year: 2014

The heat transfer performance on the wall has a great influence on the energy conservation and the indoor thermal comfort. Once it can be adjustable according to the requirement, the wall can effectively regulate the indoor temperature, thereby directly reducing the building energy consumption. In this paper, a new type of passive solar energy utilization technology, the wall implanted with heat pipes (WIHP), was proposed, and its heat transfer performance and energy-saving characteristic were investigated theoretically and experimentally with the typical meteorological data of Jinan. The results indicate that the theoretical results agree well with experimental ones. The heat transfer performance of the WIHP is adjustable and controllable, which can reduce the heating load and improve thermal environment. During the winter in a typical year, the heat loss of the south external wall is reduced by 14.47%. Therefore, such a type of wall can apparently improve the indoor thermal environment, which can be popularized in engineering applications. © 2014 Elsevier B.V. All rights reserved.

Guo M.,Tianjin Chengjian University
RSC Advances | Year: 2014

The electronic structures and optical properties of C, Ag-codoped TiO2 were investigated within the GGA + U framework. Different doping concentration and different dopant distance (CsAgs (near and far), C2sAgs (near and far), and C3sAgs (near and far)) models were constructed. According to the formation energy results of these codoped systems, it was found that low concentration codoping was more stable than high concentration codoping. Therefore, we chose the CsAgs (near and far) codoped TiO2 to calculate further electronic structures and optical properties. It was found that near distance codoping could narrow the band gap to 2.81 eV, and far distance codoping decreased the band gap to 2.66 eV. Meanwhile, it was found that far distance codoping preferred to form more localized states near the top of the valence band, while near distance codoping could induce more significant hybrid states in the band gap. Optical property showed that C and Ag codoping could induce a synergistic effect compared with single C and single Ag doping. After codoping, the visible absorption was stronger for both the near and far distance codoped systems than those of the single doped systems, moreover, the far distance codoping configuration could induce both more significant band edge shift and stronger visible optical absorption than that of the near distance codoping configuration. This journal is © The Royal Society of Chemistry.

Guo G.,Dalian Maritime University | Zhao Y.,Dalian Maritime University | Yang G.,Tianjin Chengjian University
Information Sciences | Year: 2014

This paper investigates a minimum energy cooperation control problem in mobile sensor networks. Assuming a time-invariant undirected network topology for the sensors, we present a suboptimal solution that guarantees minimum overall energy cost of mobility and communication for the sensors to achieve consensus. The design procedure of the distributed control protocol is composed of two steps. The first step yields the local feedback gain via solving a linear quadratic regulating (LQR) problem, while the second step produces the network feedback gain based on convex optimization technique. The results are extended to formation control problems with and without communication delays. The effectiveness of the proposed methodology is illustrated by numerical examples. © 2013 Elsevier Inc. All rights reserved.

Liu Y.,Tianjin Chengjian University
Proceedings - 2015 2nd International Conference on Information Science and Control Engineering, ICISCE 2015 | Year: 2015

With the appearance of high speed WPA/WPA-PSK brute forcer, the security of WLAN faces serious threats. The attackers can acquire PSK easily so as to decrypt all the traffics. To solve this problem, a series of defence schemes are proposed, including defence schemes for passive and active brute forcers. The schemes adopt active jammer and wireless packet injection. And then the theoretical analysis is processed and the implementation methods are given. In the last past, the conclusions are reached. © 2015 IEEE.

Chen N.,Tianjin Chengjian University
WIT Transactions on Information and Communication Technologies | Year: 2014

The user-oriented information service of the university digital library is the personalized information service based on the users' actual demand for information, so as to meet their demand of information and tackle the problems. The paper discusses the features of the information service, related technologies as well as the suggestions on the development according to the characters of the information demand in the universities digital library. © 2014 WIT Press.

Loading Tianjin Chengjian University collaborators
Loading Tianjin Chengjian University collaborators