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8 results on '"Chen, Kaijia"'

3. Analytical Solution for Vacuum Electroosmosis Consolidation Considering Nonlinear Attenuation of Electric Permeability Coefficient of Copper-Contaminated Sediment.

Author

Qi, Wencheng, Shen, Yang, Li, Shaoyu, Chen, Kaijia, and Xu, Junhong

Subjects
ANALYTICAL solutions, PORE water pressure, PERMEABILITY, CONTAMINATED sediments, SEDIMENTS, ELECTRO-osmosis
Abstract

Conventional vacuum electroosmosis consolidation theory tends to assume that the electric permeability coefficient remains unchanged or attenuates linearly. In contrast, the sediment from environmental dredging projects contains copper contaminants, whose electrochemical reactions during electroosmosis may influence the soil properties. Consequently, electroosmosis experiments were conducted for copper-contaminated sediments. It was found that the electric permeability coefficient attenuated rapidly due to the generation of copper hydroxide flocculant deposits under electrochemical reactions. The attenuation was 67.89% after 48 h, and its attenuation trend had obvious nonlinear characteristics. On this basis, an expression for the attenuation of the electric permeability coefficient with time was obtained by fitting an exponential function. A two-dimensional vacuum electroosmosis consolidation model considering the nonlinear attenuation rule of the electric permeability coefficient was established, and the analytical solution of the pore water pressure was deduced. Vacuum electroosmosis experiments on contaminated sediment were carried out, and the measurement results of pore water pressure at the anode verified the rationality of the analytical solution. It was also compared with conventional vacuum electroosmosis consolidation theory, which showed that the analytical solution in this study is better able to predict the dissipation of pore water pressure during long-term vacuum electroosmosis. [ABSTRACT FROM AUTHOR]

Published
2023
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6. Robust Signal Control of Exit Lanes for Left-Turn Intersections With the Consideration of Traffic Fluctuation

Author

Chen Kaijia, Xing Gao, Victor L. Knoop, and Jing Zhao

Subjects
050210 logistics & transportation, General Computer Science, Computer science, 05 social sciences, General Engineering, robust optimization, Saturation flow rate, 02 engineering and technology, unconventional intersections, signal control, Traffic signal, Design speed, Robustness (computer science), Control theory, 0502 economics and business, 0202 electrical engineering, electronic engineering, information engineering, 020201 artificial intelligence & image processing, General Materials Science, lcsh:Electrical engineering. Electronics. Nuclear engineering, Exit-lanes for left-turn intersection, lcsh:TK1-9971
Abstract

Traffic throughput at intersections can be improved by using exit lanes for left-turning (EFL), tidal flow lanes near an intersection, which has been recently introduced. This paper considers the operational robustness of the EFL intersection in relation to the control scheme applied to the traffic light setting. For safety and efficiency, it is important that the tidal lanes are emptied before traffic in the opposing direction uses these lanes. Hence, the signal control should not only be optimized for the mean value but be robust for all kinds of fluctuations. This paper formulates a traffic control scheme using robust optimization, i.e. an optimization scheme which explicitly accounts for extreme events. The fluctuation of traffic is considered from three aspects: the distribution of traffic demand, the distribution of base saturation flow rate, and the distribution of actual travel speed. Via a case study and extensive numerical analysis, we find that the established robust optimization method produces an efficient design of signal control and design speed at the EFL intersection under traffic demand and supply fluctuations. Though the optimization method is now applied to intersections with an EFL, it is considered useful for all intersections with high fluctuation of traffic demand and saturation flow rate.

Published
2020

8. Modeling loading area effectiveness at off-line bus stops with no clear-cut separation of berths

Author

Zhao, Jing, Chen, Kaijia, Wang, Tao, and Malenje, Jairus Odawa

Abstract

ABSTRACTThe loading area effectiveness is a key factor for the estimation of the bus stop capacity. The basic assumption of the existing studies is that the berths of the bus stop are divided clearly. In this paper, a new loading area effectiveness model is proposed for computing the number of effective loading areas of the off-line bus stops that have no clear-cut separation of berths. The key parameters, including the critical overtaking exiting distance gap, critical overtaking entering distance gap, and dwelling space-gap between two adjacent buses were calibrated by field data. A simulation-based approach is applied to solve the model. The proposed model was validated and the sensitivity analysis of main factors were also conducted. The results reveal that the driving behavior plays an important role. On average, 4.1% increase in the loading area effectiveness can be obtained by one meter decrease of the critical overtaking entering space-gap.

Published
2019
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