An integrated energy-efficient and transfer-accessible model for the last train timetabling problem

A new observation of significant differences in the high frequency device parameters and performance like fT and fMAX is identified from the comparison of 3-terminal (3T) and 4-terminal (4T) multi-finger (MF) nMOSFETs. Through an extensive characterization on the intrinsic Z- and Y-parameters, it is found that the major impact comes from the particular increase of intrinsic parasitic resistances and inductances at the source terminal, namely R s, int and L s, int in the 4T MF MOSFETs. The proposed analytical models as a function of key device parameters incorporating the influence of the intrinsic parasitic RLC through high frequencies can accurately predict fT and fMAX degradation in 4T MF nMOSFETs as well as the complicated layout dependent effects. The experimental results and analytical models can be useful to facilitate MF devices layout optimization for high frequency design and performance improvement.

Electronic ballasts are needed to shape the voltage and current waveforms which suit the needs of the metal-halide, high-intensity discharge (HID) lamps. This paper deals with the evaluation of the low frequency and the high frequency operations of electronic ballasts. The results are analyzed in terms of lamps operating characteristics. A boost converter works as CCM PFC in both the operations. A DC/DC buck and a full-bridge inverters are used for low frequency operations. An LCC resonant inverter is used for high frequency operations. Simulation results and actual test bench results are shown for both 100 W and 400 W metal-halide HID lamps. It is concluded that the choice is between cost and reliability corresponding to high frequency and low frequency operations, respectively.

Energy consumption analysis of trains based on multi-mode virtual coupling operation control strategies

The calculation of train running times is crucial for the process of timetable construction. The Swedish National Rail Administration and the Swedish Rail Traffic Administration have started a project to export an infrastructure model from the database BIS to SIMON/RTT and TrainPlan, and to export running time calculations from SIMON/RTT to TrainPlan. The main task of the subproject, Running Time Calculations, during Phase 1 from June 1999 to March 2000 was to develop a software prototype SIMON/RTT and to analyze the existing running time calculation model. The project is planning the second phase from April 2000 to October 2001. The subproject's objective is to calculate running times for the entire network and a great number of different train configurations. These running times are to be exported to the timetable construction tool TrainPlan and used as the basis for the timetable construction process within the Swedish Rail Traffic Administration. The results of SIMON/RTT running time calculations depend on, among other things, the infrastructure model. SIMON/RTT performs the calculations for a fixed model of the railway network and fixed, quality controlled track data. The calculation of the running time for a single train is performed for the train operation without any interaction with other trains. The dynamic functionality of the signaling system is omitted.

Urban railway transit is the most prevalent way of green transportation. But from the macroscopic perspective, the overall energy consumption of urban railway transit remains noticeable. Therefore, optimizing train operation strategies for energy efficiency has become a topic of significant research interest. Additionally, train running strategy determines different train running states under different environments, which is closely related to the reliability of train operation. This study analyzes train operation strategies to explore the factors influencing train energy consumption. Firstly, a train operation state transition model by Petri net was built, and the logical conditions for different state transitions were also introduced. Most notably, this study considers three typical operational strategies, including cruising strategy, coasting strategy and hybrid strategy. Then, based on the theoretical model, a train operation simulation was established to identify key factors affecting train energy consumption. In conclusion, simulation results show that train energy consumption tends to increase as the gradient rises, and the three typical operational strategies exhibit different impacts on travel time and energy consumption under the same gradient condition.

A Solid-State Transformer as Enabling Technology for Microgrids for Integration into the Power Distribution System: An Overview

BACKGROUND: When a vehicle is in motion, self-oscillations which properties are dependent on slip rate in a contact patch may occur in the area of tire interaction with ground surface. Oscillations frequency will vary in dependence with value of wheel slip relative to ground surface. Soft self-oscillations are excited by variable set of initial conditions at full slip in traction and driven wheel rolling modes as well as in mixed braking mode with partial slip. Hard mode of self-oscillations occurs at full wheel slip in braking mode. These processes have a negative impact on the processes in electric drive and mechanical drivetrain reducing their efficiency and may cause damage of components. Oscillations in the system are excited by interaction forces of an elastic tire with ground surface featuring vertical oscillations due to elastic behavior of its interaction with road unevenness. AIMS: Research of features of oscillating process behavior in the nonlinear system of individual traction drive of an electrobus. METHODS: Simulation of self-oscillation excitation processes in the area of contact interaction of a wheel and road was carried out in the MATLAB/Simulink software package. RESULTS: The article features the results of simulation and experimental studies of self-oscillation excitation processes of the KAMAZ 6282 electrobus moving on asphalt-concrete surface. It was found that vertical wheel displacement when moving through unevenness lead to oscillating behavior of vertical reaction forces in contact patches and, as a consequence, to oscillating behavior of longitudinal reaction forces, torque and rotation velocity of the shaft of the traction electric motor of the individual drive. It was defined that tire oscillation frequency is 67 Hz that coincides with electric motor shaft rotation oscillation frequency and this value is the same for both experiment and simulation. CONCLUSIONS: Practical value of the study lies in ability of using the study results at development of self-oscillation processes exclusion algorithms as a part of vehicle control system.

Fast lean-rich cycling for enhanced NOx conversion on storage and reduction catalysts

The energy consumption of freight train is very huge. Among all kinds of the energy consumptions, the energy consumption of traction is the largest, which leads to a great cost of freight trains. The optimization of the speed curve plays an important role in energy-saving operation. In this paper, a speed curve optimization method based on Ant Colony Optimization (ACO) is established. A simulation model combined with the characteristics of train operation is built. The related data of energy consumption and the DYNAMIS are applied to analyze the train operation. The effectiveness of the optimization algorithm is demonstrated by the simulation results.

The on-board controllers of high speed trains have been used to relieve drivers’ work by introducing a cruising control strategy or a target-speed automatic control strategy. However, the two control strategies above can only play a minor role during train operation, and the punctuality should be ensured by the train driver and the gradient profile may not be utilized to reduce energy consumption without debasing the punctuality. This paper investigates the real-time control problem of high speed trains, and then proposes a hierarchical control strategy to reduce energy consumption and improve the punctuality of the train operation planned by the railway timetable. The control strategy comprises of two modules, one of which is a speed profile planner, and the other is a speed tracking actuator. In the speed profile planner, an efficient algorithm via solving the optimal switching of adjoint variable based on the maximum principle is adopted to calculate the optimal speed profile of the train running section, meeting both the objective of energy consumption minimization and punctuality constraint. Then an active disturbance rejection controller is designed as the actuator to track the planned speed profile, implementing an accurate tracking of the accelerating process, cruising process and decelerating process. An extended state observer is designed to produce real-time estimates and compensation for the total disturbance. Simulations show that the hierarchical controller can ameliorate train operation effectively, from the aspects of planning and self-regulating ability which can improve operation punctuality offered by the speed profile planner, energy saving and riding comfort mainly offered by the speed tracking actuator with proper parameter values.

Active elements working in the current or mixed mode are still attractive for the design of analog functional blocks. The current conveyor (CC) was defined already in 1968. This paper deals with hysteresis comparators using second generation current conveyor. The comparator is basically a pulse circuit. In these circuits, the maximum rate of change in the output voltage is required during switching from one state to another. In comparators with operational amplifiers the switching time is given by the slew rate of the operational amplifier used, which is not too high. If a current conveyor is used, the time of switching the comparator gets shorter. The comparator is capable to operate at a higher frequency bands and if it is used, for example, in converters, a higher operating frequency can be reached. The connection of an inverting and a non-inverting comparator with adjustable hysteresis is shown as a practical implementation. Using the AD844, results of experimental measurements are presented that confirm the theoretical assumptions and the results of computer simulation.

This paper introduces a simple diesel train energy consumption model that calculates the instantaneous energy consumption using vehicle operational input variables, including the instantaneous speed, acceleration, and roadway grade, which can be easily obtained from global positioning system (GPS) loggers. The model was tested against real-world data and produced an error of −1.33% for all data and errors ranging from −12.4% to +8.0% for energy consumption of four train datasets amounting to a total of 5854 km trips. The study also validated the proposed model with separate data that were collected between Valencia and Cuenca, Spain, which had a total length of 198 km and found that the model was accurate, yielding a relative error of −1.55% for the total energy consumption. These results show that the proposed model can be used by train operators, transportation planners, policy makers, and environmental engineers to evaluate the energy consumption effects of train operational projects and train simulation within intermodal transportation planning tools.

The efficiency of 4 K Stirling type pulse tube cryocoolers (SPTCs) is rather low due to significant regenerator losses associated with the unique properties of helium around 4 K and the high operating frequencies. In this paper, regenerator performance at liquid helium temperature regions under high frequencies is investigated based on a single-stage SPTC precooled by a two-stage Gifford-McMahon type pulse tube cryocooler (GMPTC). The 4 K SPTC used a 10 K cold inertance tube as phase shifters for better phase relationship between pressure and mass flow. The effect of the operating parameters, including frequency and average pressure on the performance of the 4 K SPTC, was investigated and the first and second precooling powers provided by the GMPTC were obtained. To reduce the regenerator heat transfer losses, a multi-layer regenerator matrix, including Gd2O2S (GOS) and HoCu2, was used instead of a single-layer HoCu2 around 4 K. A theoretical and experimental comparison between the two types of regenerator materials was made and the precooling requirements for a regenerator operating at high frequencies to reach liquid helium temperatures were given, which provided guidance for the design of a three-stage SPTC.

China is currently the world's largest energy consumer. The rapid growth in energy consumption has resulted in many problems in this country. The Chinese government has realized the necessity of improving energy efficiency and reducing energy consumption. As a useful decision-support tool, simulation models can be used to examine the potential impacts of different plans on urban development and energy consumption. This study presents a model that integrates support vector regression (SVR) and cellular automata (CA) to simulate urban forms and to estimate the corresponding energy consumption in one of the most developed regions in China, the Pearl River Delta (PRD). SVR is used to predict energy consumption and to project future urban size. The logistic CA model simulates different urban forms to evaluate their effects on energy consumption. In this study, we simulated four scenarios to assess the impacts of different development strategies on urban forms and the related energy consumption. For each scenario, we used the model to predict land demand and energy consumption. The result indicates that land demand is more sensitive to changes of economic structure than is energy consumption. The comparison of different simulated scenarios suggests that promoting low-energy-consuming industries is the most effective strategy to balance economic development and energy and land consumption.

Real-time energy consumption minimization in railway networks