scholarly journals Coordinated Headway-Based Control Method to Improve Public Transit Reliability considering Control Points Layout

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Hu Zhang ◽  
Shidong Liang ◽  
Jing Zhao ◽  
Shengxue He ◽  
Tianyu Zhao
Keyword(s):  
Waiting Time ◽  
Control Strategy ◽  
Control Method ◽  
Public Transit ◽  
Control Point ◽  
Threshold Value ◽  
Control Points ◽  
The Public ◽  
Transit Reliability ◽  
Improve Reliability

The headway-based control method is usually used to regulate the bus headways and improve reliability of public transit. In general, the holding control strategy is applied at the control point, because enough space for dwell longer at the control point is required, while the stop-skipping control strategy can be used at any bus stop. However, in the headway-based control method, too much stop-skipping will bring longer waiting time and make the passengers impatient. The number and distribution of control points for stop-skipping are not considered in previous self-equalizing bus headway control works. Therefore, in this paper, the control points selection rules for stop-skipping involving their number and distribution on the bus route are discussed. A second by second discrete system is formulated to describe the bus operation. In the proposed control method, the threshold value for activating stop-skipping strategy is raised, avoiding provoking much additional waiting time because of boarding rejected. In the numerical analysis, a set of cases are conducted to evaluate the performance of control method under different number and distribution of control points for stop-skipping. The numerical results show that distribution of control points for stop-skipping has a greater influence on the public transit than the number.

scholarly journals Modelling for The COVID-19 with The Contacting Distance

2021 ◽  
Author(s):  
Zhihui Ma ◽  
Shufan Wang ◽  
Xuanru Lin ◽  
Xiaohua Li ◽  
Xiaotao Han ◽  
...  
Keyword(s):  
Epidemic Model ◽  
Large Scale ◽  
Control Method ◽  
Numerical Test ◽  
Threshold Value ◽  
Human Beings ◽  
Healthy Individuals ◽  
The Public ◽  
Immigration Rate ◽  
The Family

Abstract The COVID-19, which belongs to the family of Coronaviridae and is large-scale outbreak in the whole world, is a public health emergency for human beings and brings some very harmful consequences in social and economic fields. In order to modelling the COVID-19 and develop the efficient control method corresponding to the contacting distance, this paper proposes an SEIR-type epidemic model with the contacting distance between the healthy individuals and the asymptomatic or symptomatic infected individuals, and the immigration rate of the healthy individuals, since the contacting distance and the immigration rate are two critical factors which determine the transmission of the COVID-19. Firstly, the threshold contacting distance and the threshold immigration rate are obtained by analyze the dynamical behaviors of the proposed SEIR-type epidemic model in order to control the COVID-19. The effect of the contacting distance and the immigration rate on the control of the COVID-19 are revealed based on ecological and epidemiological issues. The results show that the COVID-19 will be controlled while the contacting distance between the healthy individuals and the symptomatic infected individuals is larger than the threshold value A~ and the immigration rate is smaller than the threshold value ~ d. Secondly, the sensitivity analysis is conducted and the results show that the contacting distance and the immigration rate play an important role in controlling the COVID-19. Finally, the numerical test for Wuhan city are conducted and the conclusions show that the extinct lag decreases as the the contacting distance increase or the immigration rate decrease. Our study could give some reasonable suggestions for the health officials and the public.

scholarly journals Modelling for the COVID-19 with the Contacting Distance

2021 ◽  
Author(s):  
Zhihui Ma ◽  
Shufan Wang ◽  
Xuanru Lin ◽  
Xiaohua Li ◽  
Xiaotao Han ◽  
...  
Keyword(s):  
Epidemic Model ◽  
Large Scale ◽  
Control Method ◽  
Numerical Test ◽  
Threshold Value ◽  
Human Beings ◽  
Healthy Individuals ◽  
The Public ◽  
Immigration Rate ◽  
The Family

Abstract The COVID-19, which belongs to the family of Coronaviridae and is large-scale outbreak in the whole world, is a public health emergency for human beings and brings some very harmful consequences in social and economic fields. In order to modelling the COVID-19 and develop the efficient control method corresponding to the contacting distance, this paper proposes an SEIR-type epidemic model with the contacting distance between the healthy individuals and the asymptomatic or symptomatic infected individuals, and the immigration rate of the healthy individuals, since the contacting distance and the immigration rate are two critical factors which determine the transmission of the COVID-19. Firstly, the threshold contacting distance and the threshold immigration rate are obtained by analyze the dynamical behaviors of the proposed SEIR-type epidemic model in order to control the COVID-19. The effect of the contacting distance and the immigration rate on the control of the COVID-19 are revealed based on ecological and epidemiological issues. The results show that the COVID-19 will be controlled while the contacting distance between the healthy individuals and the symptomatic infected individuals is larger than the threshold value $\tilde{d}^*$ and the immigration rate is smaller than the threshold value $\tilde{A}^*$. Secondly, the sensitivity analysis is conducted and the results show that the contacting distance and the immigration rate play an important role in controlling the COVID-19. Finally, the numerical test for Wuhan city are conducted and the conclusions show that the extinct lag decreases as the the contacting distance increase or the immigration rate decrease. Our study could give some reasonable suggestions for the health officials and the public.

A Study on the Public Transit Transfer Behavior in New Rail Cities Based on Travelers’ Cognition

CICTP 2020 ◽  
2020 ◽  
Author(s):  
Shenghui Zhao ◽  
Lishan Sun ◽  
Dewen Kong ◽  
Jinghan Cao ◽  
Yan Wang
Keyword(s):  
Public Transit ◽  
The Public ◽  
Transfer Behavior

scholarly journals Torque Ripple Suppression of PMSM Based on Robust Two Degrees-of-Freedom Resonant Controller

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1015
Author(s):  
Mingfei Huang ◽  
Yongting Deng ◽  
Hongwen Li ◽  
Jing Liu ◽  
Meng Shao ◽  
...  
Keyword(s):  
Control Strategy ◽  
Measurement Errors ◽  
Degrees Of Freedom ◽  
Control Method ◽  
Torque Ripple ◽  
Current Loop ◽  
Two Degrees Of Freedom ◽  
Robust Stability Analysis ◽  
Resonant Controller ◽  
Testing Environments

This paper concentrates on a robust resonant control strategy of a permanent magnet synchronous motor (PMSM) for electric drivers with model uncertainties and external disturbances to improve the control performance of the current loop. Firstly, to reduce the torque ripple of PMSM, the resonant controller with fractional order (FO) calculus is introduced. Then, a robust two degrees-of-freedom (Robust-TDOF) control strategy was designed based on the modified resonant controller. Finally, by combining the two control methods, this study proposes an enhanced Robust-TDOF regulation method, named as the robust two degrees-of-freedom resonant controller (Robust-TDOFR), to guarantee the robustness of model uncertainty and to further improve the performance with minimized periodic torque ripples. Meanwhile, a tuning method was constructed followed by stability and robust stability analysis. Furthermore, the proposed Robust-TDOFR control method was applied in the current loop of a PMSM to suppress the periodic current harmonics caused by non-ideal factors of inverter and current measurement errors. Finally, simulations and experiments were performed to validate our control strategy. The simulation and experimental results showed that the THDs (total harmonic distortion) of phase current decreased to a level of 0.69% and 5.79% in the two testing environments.

Controlling chemical dosing for sulfide mitigation in sewer networks using a hybrid automata control strategy

2013 ◽  
Vol 68 (12) ◽  
pp. 2584-2590 ◽  
Author(s):  
Yiqi Liu ◽  
Ramon Ganigué ◽  
Keshab Sharma ◽  
Zhiguo Yuan
Keyword(s):  
Control Strategy ◽  
Control Method ◽  
Biological Processes ◽  
Control Performance ◽  
Hybrid Automata ◽  
Sewer Pipe ◽  
Physical Chemical ◽  
Iron Salts ◽  
Pumping Stations ◽  
Sewer Networks

Chemicals such as magnesium hydroxide (Mg(OH)2) and iron salts are widely used to control sulfide-induced corrosion in sewer networks composed of interconnected sewer pipe lines and pumping stations. Chemical dosing control is usually non-automatic and based on experience, thus often resulting in sewage reaching the discharge point receiving inadequate or even no chemical dosing. Moreover, intermittent operation of pumping stations makes traditional control theory inadequate. A hybrid automata-based (HA-based) control method is proposed in this paper to coordinate sewage pumping station operations by considering their states, thereby ensuring suitable chemical concentrations in the network discharge. The performance of the proposed control method was validated through a simulation study of a real sewer network using real sewage flow data. The physical, chemical and biological processes were simulated using the well-established SeweX model. The results suggested that the HA-based control strategy significantly improved chemical dosing control performance and sulfide mitigation in sewer networks, compared to the current common practice.

Performance Improvement of SVPWM-Based Three-Phase Grid-Connected Inverters

2013 ◽  
Vol 732-733 ◽  
pp. 1261-1264
Author(s):  
Zhi Lei Yao ◽  
Lan Xiao ◽  
Jing Xu
Keyword(s):  
Dynamic Response ◽  
Control Strategy ◽  
Pulse Width Modulation ◽  
Control Method ◽  
Grid Current ◽  
Current Controller ◽  
Three Phase ◽  
Reference Grid ◽  
Grid Connected Inverter

An improved control strategy for three-phase grid-connected inverters with space vector pulse width modulation (SVPWM) is proposed. When the grid current contains harmonics, the d-and q-axes grid currents is interacted in the traditional control method, and the waveform quality of the grid current is poor. As the reference output voltage cannot directly reflect the change of the reference grid current with the traditional control strategy, the dynamic response of the grid-connected inverter is slow. In order to solve the aforementioned problems, the d-and q-axes grid currents in the decoupled components of the grid current controller are substituted by the d-and q-axes reference grid currents, respectively. The operating principles of the traditional and proposed control methods are illustrated. Experimental results show that the grid-connected inverter with the improved control strategy has high waveform quality of the grid current and fast dynamic response.

scholarly journals Public Transit Loyalty Modeling Considering the Effect of Passengers’ Emotional Value: A Case Study in Xiamen, China

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Shi-chao Sun
Keyword(s):  
Structural Equation ◽  
Goodness Of Fit ◽  
Public Transit ◽  
Perceived Value ◽  
Index Score ◽  
The Public ◽  
Bus Service ◽  
Bus Services ◽  
Emotional Value

To better sustain passengers’ loyalty towards bus service, this paper addressed the modeling of the public transit loyalty by the use of structural equation model. As a novel hypothesis, the emotional value was considered to have effects on the perceived value of bus services in this study, which reflected the degree of passengers’ emotional dependence on the public transit. Specifically, in order to better assess the loyalty, seven unobserved variables were measured to construct the structural model, namely, “service guarantee,” “operational services and efficiency,” “emotional value,” “perceived value,” “expectation,” “satisfaction,” and “loyalty.” The goodness-of-fit of the model was estimated and evaluated by using the survey data harvested from Xiamen, China. Besides, the index score of variables was also computed to help determine targeted approaches to better improve the level of bus service. The results indicated that the time cost and the monetary cost actually had no effects on the perceived value of users in the case study. At the same time, however, it also proved that passengers’ emotional value towards the public transit indeed affected passengers’ perception of the service value. In addition, whether users’ perceived value was as expected determined how much passengers satisfied with the service. Regarding the index score of variables, it indicated a great dissatisfaction of passengers towards the current bus service. Unexpectedly, the score of loyalty even still retained a relatively high level, which reflected continue-to-use willingness of passengers. It implied that being subject to economic conditions and other factors, passengers were captive and had to continue relying on the public transit, in spite of their dissatisfaction. As for the improvement direction of bus services, targeted approaches should be determined to improve the quality of bus service, regarding the aspects of “condition of facilities in the bus,” “driving stability and comfort,” “vehicle speed,” and “safety.”

Optimized Non-Dead-Time Control of Inverter with Two-Phase Modulated SVPWM

2012 ◽  
Vol 562-564 ◽  
pp. 1531-1536
Author(s):  
Ming Xing Zhu ◽  
Jing Bo Shi
Keyword(s):  
Control Strategy ◽  
Pulse Width Modulation ◽  
Dead Time ◽  
Control Method ◽  
Short Circuit ◽  
Two Phase ◽  
Zero Crossing ◽  
Time Control ◽  
Bus Voltage ◽  
Current Zero

In the inverter control system, two-phase modulated space vector pulse width modulation (SVPWM) algorithm has the advantages of minimum switch loss and higher utilization of direct current (DC) bus voltage. Non-dead-time control strategy can eliminate the problems of the dead time effects. But the traditional non-dead-time control strategy heavily depends on the current zero-crossing detection, which may cause the output voltage distortion or even a short circuit. Based on the analysis of the reason for the distortion, a new optimized non-dead-time control method is proposed. Two methods for the detection of the overlapping area are enumerated. The conclusions are confirmed by the simulation results with MATLAB/ SIMULINK.

Time-Optimal Coordination Control for the Gear-Shifting Process in Electric-Driven Mechanical Transmission (Dog Clutch) without Impacts

2020 ◽  
Vol 9 (2) ◽  
pp. 155-168
Author(s):  
Ziwang Lu ◽  
◽  
Guangyu Tian ◽  
Keyword(s):  
Control Strategy ◽  
Position Control ◽  
Control Method ◽  
Synchronization Control ◽  
Mechanical Transmission ◽  
Coordination Control ◽  
Optimal Position ◽  
Drive Motor ◽  
Time Optimal ◽  
Optimal Coordination

Torque interruption and shift jerk are the two main issues that occur during the gear-shifting process of electric-driven mechanical transmission. Herein, a time-optimal coordination control strategy between the the drive motor and the shift motor is proposed to eliminate the impacts between the sleeve and the gear ring. To determine the optimal control law, first, a gear-shifting dynamic model is constructed to capture the drive motor and shift motor dynamics. Next, the time-optimal dual synchronization control for the drive motor and the time-optimal position control for the shift motor are designed. Moreover, a switched control for the shift motor between a bang-off-bang control and a receding horizon control (RHC) law is derived to match the time-optimal dual synchronization control strategy of the drive motor. Finally, two case studies are conducted to validate the bang-off-bang control and RHC. In addition, the method to obtain the appropriate parameters of the drive motor and shift motor is analyzed according to the coordination control method.

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