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Zhang Z.,Tianjin municipal Engineering Design & Research Institute | Wang H.,Nanjing Southeast University
Wuhan Ligong Daxue Xuebao (Jiaotong Kexue Yu Gongcheng Ban)/Journal of Wuhan University of Technology (Transportation Science and Engineering) | Year: 2015

In the lane changing model of lane changing execution phase, the target vehicle not only by the lane in front of the vehicle impact, but also the influence of the target before and after the vehicle lane. Firstly, in this paper the traditional car following model is improved, get the Double-Head following model. And the study of the target vehicle trajectory, the target vehicle trajectory is divided into the forward direction and the vertical direction and displacement, relative speed, acceleration. Based on the vehicle track different longitudinal velocity analysis found that, the target vehicle lateral velocity is influenced by the longitudinal velocity and lateral displacement, with the increase of the lateral displacement of the target vehicle in the driveway, the vehicle in front attention will be reduced gradually. ©, 2015, Wuhan University of Technology. All right reserved.


PubMed | Tohoku University, Tianjin Chengjian University, Water and Disaster Management Bureau, Tianjin Municipal Engineering Design & Research Institute and 2 more.
Type: | Journal: Bioresource technology | Year: 2017

Toilet-paper cellulose with rich but refractory carbon sources, are the main insoluble COD fractions in sewage. An anaerobic membrane bioreactor (AnMBR) was configured for sewage treatment at room temperature and its performance on methanogenic degradation of toilet paper was highlighted. The results showed, high organic removal (95%), high methane conversion (90%) and low sludge yield (0.08gVSS/gCOD) were achieved in the AnMBR. Toilet-paper cellulose was fully biodegraded without accumulation in the mixed liquor and membrane cake layer. Bioconversion efficiency of toilet paper approached 100% under a high organic loading rate (OLR) of 2.02gCOD/L/d and it could provide around 26% of total methane generation at most of OLRs. Long sludge retention time and co-digestion of insoluble/soluble COD fractions achieving mutualism of functional microorganisms, contributed to biodegradation of toilet-paper cellulose. Therefore the AnMBR successfully implemented simultaneously methanogenic bioconversion of toilet-paper cellulose and soluble COD in sewage at room temperature.


PubMed | Harbin Institute of Technology, Tianjin Municipal Engineering Design & Research Institute and Nanjing Forestry University
Type: Journal Article | Journal: Water science and technology : a journal of the International Association on Water Pollution Research | Year: 2016

A novel process, inclined-plates hydrolytic tank (IHT) and membrane bioreactor (MBR), was used to treat domestic sewage continuously. In this study, the effects of carriers addition on operational performances of IHT-MBR were studied at the hydraulic retention time of 5.4 h and the recycling rate of 200%. Experimental results indicated the removal efficiencies of chemical oxygen demand, total nitrogen and total phosphorus reached 86.8%, 82.9% and 89.6%, respectively, corresponding trans-membrane pressure decreased to 1.50 kPa/d at a packing ratio of 20%. Simultaneously, the scanning electron microscope and soluble microbial products analysis demonstrated that high nutrient removal and low membrane fouling were attributed to the attached growth of microorganisms on carriers. The bioattachment and adsorption of carriers not only decreased the soluble proteins and polysaccharide in MBR, but also provided good living environments for denitrifying bacteria and phosphorus-accumulating bacteria.


Geng P.,Southwest Jiaotong University | Quan Q.,Tianjin Municipal Engineering Design & Research Institute | Wang S.,Southwest Jiaotong University | An J.,Southwest Jiaotong University | Yan Q.,Southwest Jiaotong University
Modern Tunnelling Technology | Year: 2015

Mud and water bursts are common phenomena when tunnels pass through water-rich fault zones and are serious disasters encountered during tunnel construction. In order to explore the formation process of mud and water bursts in tunnels and the influence of fault dip angles on the formation process in order to avoid serious engineering disasters, the processes of mud and water bursts induced by tunnelling in water-rich fault zones with different dip angels were simulated by Discrete Element Method (DEM) based on coupling the particle and fluid. In the simulation process, the development of fractures in surrounding rocks and the amounts of inrushing mud and water were traced and recorded, the formation processes of the mud- and water-bursting channels were analyzed, and the influence of fault dip angles on mud and water bursts was revealed. The study shows that the smaller the fault dip angles, the shorter the vertical distances between the fault and tunnel, and the more likely that mud and water bursts will occur and concentrate at the bottom of the working face. The study results provide a reference for the design of tunnel excavations in water-rich fault zones as well as for the forecast and prevention of mud and water bursts. ©, 2015, Editorial Office of "Modern Tunnelling Technology". All right reserved.


Cui D.,Tianjin University | Xing J.,Tianjin Data Center Design & Engineering Co. | Ling J.,Tianjin University | Hao H.,Tianjin Data Center Design & Engineering Co. | And 2 more authors.
Modern Tunnelling Technology | Year: 2014

Based on a tunnel practice, the ventilation effect of the shaft during traffic clogging in a tunnel with ventilation shaft is studied through a model test. The research results show that ventilation shaft presents a character of cyclical transition between air intake and air exhaust with small air quantities when natural ventilation due to low speed movement of vehicles is used; and air exhaust rate of rectangular shaft increases with the increase of cross-section equivalent diameter while air exhaust rate increases with the decrease of slope angle of ventilation shaftwhen a combination of jet fan and traffic induced air is used to keep a constant state of air exhaust. ©, 2014, Editorial Office of "Modern Tunnelling Technology". All right reserved.


Zhang H.,Tianjin University | Zhai H.,Tianjin University | Ji M.,Tianjin University | Su X.,Tianjin University | And 2 more authors.
Desalination and Water Treatment | Year: 2015

Chromium (Cr) is a toxic compound in wastewater and can cause inhibitory effects on nitrification in a biological treatment system. However, different long-term inhibitory effects of Cr(VI) on ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) were seldom investigated in activated sludge systems. In this study, the influences of 1−10 mg/L Cr(VI) on bioactivities and quantities of AOB and NOB in long-term inhibition and recovery periods were investigated. The transformation of inorganic nitrogen, fluorescence in situ hybridization assay for analyzing micro-organism population, and specific oxygen uptake rates of activated sludge were examined. Results show that the inhibitory effect of Cr(VI) on nitrification increased with the Cr(VI) loading concentration and running cycle. The inhibited nitrification can be gradually recovered in a recovery period despite of a high accumulation of Cr (including Cr(VI) and Cr(III)) in activated sludge. AOB were more sensitive than NOB to Cr(VI). AOB recovered fast both in activity and quantity. NOB recovered more slowly than AOB. © 2014, © 2014 Balaban Desalination Publications. All rights reserved.


Cui W.,Tianjin University | Chen W.,Tianjin University | Wang N.,Tianjin Municipal Engineering Design & Research Institute
Tumu Gongcheng Xuebao/China Civil Engineering Journal | Year: 2015

Temperature and humidity are important factors causing cracking in early-age concrete, and the behavior of early-age concrete is closely related to the change of temperature and time. However, there are obvious defects in the existing methods for the simulation of thermo-hydro-mechanical coupling effect. In order to simulate the stress field of early-age concrete realistically and evaluate the cracking risk of structure reasonably, the secondary development platform of ABAQUS is employed to develop three subroutines, including a temperature field calculation subroutine based on hydration degree theory with respect to the changing of thermal parameters, a humidity field calculation subroutine considering the effects of temperature on the moisture diffusion coefficient, and a stress field calculation subroutine based on the theory of maturity and DPL (double power law) function, which were then verified by using numerical examples. With a sequential coupling method, the subroutines were applied to a practical project. The results show that the temperature field is mainly affected by the heat of hydration in the early stage and with a certain lag in time, it will change with the atmospheric temperature; The shrinkage deformation mainly affects the surface stress; After taking the humidity into account, the internal stress of structures may be reduced; The surface cracking of structures may be viewed as the result of the joint action of temperature and drying shrinkage, but the internal cracking are mainly caused by the temperature. ©, 2015, Editorial Office of China Civil Engineering Journal. All right reserved.


Wang J.,Tongji University | Chen C.,Tongji University | Song Y.,Tongji University | Zhang L.,Tianjin Municipal Engineering Design & Research Institute
Zhendong yu Chongji/Journal of Vibration and Shock | Year: 2016

Considering the random nature of a barge-bridge collision, 6 barges with different tons were modeled to get the dynamic time history probabilistic model samples of a barge-rigid wall oblique collision. FE software LS-DYNA was used for numerical simulation, and 36 sample curves of the dynamic time history with 6 velocities were obtained. These sample curves were non-dimensionalized, and dimensionless curves of dynamic time history were obtained. Furthermore, the expressions of mean impact force and duration versus tonnage and velocity were derived. 21 discrete points were used to express the dimensionless curves approximately and statistical analysis was conducted at each discrete point. The results showed that the dimensionless impact forces of each discrete section are normally distributed, and then their mean values and standard deviations are obtained; according to the random number generation technique, the sample curves of a barge-rigid wall oblique collision are generated. Comparing the artificial probabilistic model samples with numerical simulation ones, it was verified that this technical approach has a better accuracy. © 2016, Editorial Office of Journal of Vibration and Shock. All right reserved.


Chen J.,Central South University | Zhang J.,Central South University | Li J.,Central South University | Li J.,Tianjin Municipal Engineering Design & Research Institute
Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology) | Year: 2016

Concrete block surface with different roughness were made and the surface was used as the soil-concrete interface. The interface roughness was measured by sand filling method. The direct shear tests on the interface of red clay-block by using the large-direct shear apparatus were carried out. The influences of interface roughness on the parameters of shear strength, the relationships between shear stress and tangential displacement and the behavior of shear dilatancy & shear shrinkage were studied by quantitative analysis of roughness. The results show that the interface roughness has little influence on the angle of internal friction of red clay-concrete interface. With the interface roughness approaching its marginal value, cohesion of red clay-concrete interface increases with the increase of roughness and its value is approaching that of red clay. The interface roughness has a great influence on the relationships between shear stress and tangential displacement. There is the zone above the interface, in the soil, in which the mechanical properties are affected by the interface roughness. The zone expands with the increment of interface roughness until it reaches the maximum when the roughness also reaches or exceeds its marginal value. The behavior of shear dilatancy of the red clay is shown when the normal stress is low. The interface roughness has little influence on the behavior of shear dilatancy & shear shrinkage of red clay. © 2016, Central South University of Technology. All right reserved.


Chen J.,Central South University | Zhang J.,Central South University | Li J.,Tianjin Municipal Engineering Design & Research Institute
Sichuan Daxue Xuebao (Gongcheng Kexue Ban)/Journal of Sichuan University (Engineering Science Edition) | Year: 2015

A new method for the definition and measurement of roughness of soil-structure interface was proposed based on reversing the roughness measured by sand filling method. The new method, sand filling method and the method for the measurement of peak-valley distance were used to measure the roughness of the surfaces with semi-circle grooves made by the test and the surface with tooth grooves made by the other research scholars. The comparisons were made according to the results of measurement. The direct shear tests on the interface of red clay-concrete block were carried out using the large-scale direct apparatus. The effects of roughness on the interface characteristics of shear failure and deformation were studied by quantitative analysis and the effect mechanism of roughness were discussed. The results indicated that, for the measurement of roughness of interface, the new method suggested by this paper is more effective than both sand filling method and the method for the measurement of peak-valley distance. The shear failure of interface agrees well with the Mohr-Coulomb strength failure criterion. The roughness has little effects on the internal friction angle. The growth rates of the shear strength and the cohesion reduce with the increment of roughness of interface. With the increment of roughness of interface, the cohesion of interface increases until it approaches to the cohesion of red clay. If the cohesion of interface approaches to that of red clay, the shear failure may occur on the interface or in the soil near the interface. With the increment of the normal stress, the critical roughness decreases, meanwhile, the effects of roughness on shear strength of interface reduce. When the roughness of interface is low, the stress-dropping phenomenon is shown after the shear failure occurs. ©, 2015, Editorial Department of Journal of Sichuan University. All right reserved.

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