A Subway Train Timetable Optimization Approach Based on Energy-Efficient Operation Strategy

2012 ◽  
Author(s):  
Shuai Su ◽  
Xiang Li ◽  
Tao Tang
Keyword(s):  
Energy Efficient ◽  
Optimization Approach ◽  
Energy Prices ◽  
Real Time Control ◽  
Speed Limits ◽  
Efficient Operation ◽  
Time Control ◽  
Trip Time ◽  
The Difference ◽  
Automatic Train Operation

With the rising energy prices and environment concerns, energy-efficient operation is paid more and more attention in the subway systems, which is one of the effective ways to reduce the operation cost and then improve the operation efficiency. There are many researches for energy-efficient operation on designing a reasonable timetable or optimizing the speed profile, but all of them are studied separately. To achieve a better performance on energy saving, we present an integrated algorithm for optimizing the timetable for the entire route together with the speed profiles between successive stations, which is named as integrated timetable. First, we give an analytical algorithm to get the optimal switching points for each section by using the Pontryagin maximum principle. For dealing with the variable speed limits, we calculate the reserve time, i.e., the difference between the pre-determined trip time and the minimum trip time, and then design an algorithm to distribute it among different sections with constant speed limits. Finally, we extend the algorithm to solve the integrated timetable. We also give some numerical examples to illustrate the validity of the algorithm based on the data from the Beijing YiZhuang subway line in China. It is recorded that the energy consumption for interstation trip can be reduced by 10.3% on average, and the total energy reduction for the entire trip is 14.5% by using the integrated timetable. Besides, it takes about 0.15 seconds to generate the integrated timetable, which means that the algorithm is quick enough to be used in the automatic train operation (ATO) system for real-time control.

scholarly journals Optimization of Energy-Efficient Speed Profile for Electrified Vehicles

2018 ◽  
Author(s):  
Hadi Abbas ◽  
Youngki Kim ◽  
Jason B. Siegel ◽  
Denise M. Rizzo
Keyword(s):  
Energy Consumption ◽  
Energy Efficient ◽  
Minimum Energy ◽  
Efficient Operation ◽  
Operating Modes ◽  
Minimum Energy Consumption ◽  
System A ◽  
Trip Time ◽  
Route Information

This paper presents a study of energy-efficient operation of vehicles with electrified powertrains leveraging route information, such as road grades, to adjust the speed trajectory. First, Pontryagin’s Maximum Principle (PMP) is applied to derive necessary conditions and to determine the possible operating modes. The analysis shows that only 5 modes are required to achieve minimum energy consumption; full propulsion, cruising, coasting, full regeneration, and full regeneration with conventional braking. The minimum energy consumption problem is reformulated and solved in the distance domain using Dynamic Programming to optimize speed profiles. A case study is shown for a light weight military robot including road grades. For this system, a tradeoff between energy consumption and trip time was found. The optimal cycle uses 20% less energy for the same trip duration, or could reduce the travel time by 14% with the same energy consumption compared to the baseline operation.

Driving strategy optimization for trains in subway systems

2016 ◽  
Vol 232 (2) ◽  
pp. 369-383 ◽  
Author(s):  
Shuai Su ◽  
Tao Tang ◽  
Xiang Li
Keyword(s):  
Energy Efficient ◽  
Mechanical Energy ◽  
Maximum Acceleration ◽  
Efficient Operation ◽  
Energy Unit ◽  
Solution Approach ◽  
The Maximum Principle ◽  
Trip Time ◽  
Efficient Control ◽  
Control Sequences

Energy-efficient operation of trains in subway systems is regarded as one of the most effective strategies to cut down the operational cost. Most of the studies about the energy-efficient operation of trains aim to minimize the consumption of mechanical energy of trains. In this paper, an energy-efficient train control model is proposed under the practical billing system by introducing the traction efficiency. In addition, a numerical solution approach is presented to solve the energy-efficient driving strategy, which consists of the control sequences and the corresponding switching points. First, the authors analyze the energy-efficient control problem by applying the maximum principle, from which the energy-efficient control regime is proved to include the maximum acceleration, coasting, cruising with partial braking, and maximum braking. Second, the control sequences for one section are fully analyzed and an algorithm is presented to calculate the switching points with the energy consumption constraint. To obtain the solution to an interval with variable speed limits and gradients, the interval is divided into several sections, where the gradient and speed limit of each section are constants. A primary energy-efficient solution, which costs a longer trip time, is given. Then, energy units are assigned into multiple sections to shorten the trip time of the primary solution. Specifically, each energy unit is added into the selected section to achieve the maximum time reduction. Finally, the energy-efficient driving strategy at all sections will be obtained when the scheduled trip time of the interval is delivered. Some examples based on the practical data are conducted to illustrate that the proposed approach has a good potential on saving energy of trains.

scholarly journals Low-Complexity Run-time Management of Concurrent Workloads for Energy-Efficient Multi-Core Systems

2020 ◽  
Vol 10 (3) ◽  
pp. 25
Author(s):  
Ali Aalsaud ◽  
Fei Xia ◽  
Ashur Rafiev ◽  
Rishad Shafik ◽  
Alexander Romanovsky ◽  
...  
Keyword(s):  
Time Management ◽  
Energy Efficient ◽  
Low Cost ◽  
Low Complexity ◽  
Optimization Approach ◽  
System Configuration ◽  
Efficient System ◽  
Time Control ◽  
Time Optimization ◽  
Run Time

Contemporary embedded systems may execute multiple applications, potentially concurrently on heterogeneous platforms, with different system workloads (CPU- or memory-intensive or both) leading to different power signatures. This makes finding the most energy-efficient system configuration for each type of workload scenario extremely challenging. This paper proposes a novel run-time optimization approach aiming for maximum power normalized performance under such circumstances. Based on experimenting with PARSEC applications on an Odroid XU-3 and Intel Core i7 platforms, we model power normalized performance (in terms of instruction per second (IPS)/Watt) through multivariate linear regression (MLR). We derive run-time control methods to exploit the models in different ways, trading off optimization results with control overheads. We demonstrate low-cost and low-complexity run-time algorithms that continuously adapt system configuration to improve the IPS/Watt by up to 139% compared to existing approaches.

In-Cycle Closed Loop Control of the Fuel Injection on a 1-Cylinder Heavy Duty CI-Engine

2010 ◽  
Author(s):  
Claes-Go¨ran Zander ◽  
Per Tunesta˚l ◽  
Ola Stenla˚a˚s ◽  
Bengt Johansson
Keyword(s):  
Heat Release ◽  
Real Time ◽  
Fuel Injection ◽  
Real Time Control ◽  
Loop Control ◽  
Time Control ◽  
Ci Engine ◽  
The Difference ◽  
Proportional Controller ◽  
Polytropic Exponent

The focus of this article is on implementation of real time combustion control by using an FPGA. The feedback used for the controller is the heat release. Due to the desire to avoid using division on the FPGA an alternative way of calculating the polytropic exponent is investigated. When this method is compared against using a constant exponent it shows less fluctuations in regards to cycle to cycle variations when calculating the heat release. A dual injection strategy is used and real time control is implemented on the second fuel injection. The calculated heat release is continuously compared with a reference and then the difference is converted to a duration correction of the fuel injection. This is done by a proportional controller which is initiated after the start of the second injection. By adding a perturbation on the first fuel injection the controller is shown to compensate during the second and thereby decreasing the cycle to cycle variations.

Green FLASH: energy efficient real-time control for AO

2016 ◽  
Author(s):  
D. Gratadour ◽  
N. Dipper ◽  
R. Biasi ◽  
H. Deneux ◽  
J. Bernard ◽  
...  
Keyword(s):  
Real Time ◽  
Energy Efficient ◽  
Real Time Control ◽  
Time Control

A Model to Assess the Performance of Controlled Urban Drainage Systems

1994 ◽  
Vol 29 (1-2) ◽  
pp. 437-444 ◽  
Author(s):  
Fons Nelen
Keyword(s):  
Real Time ◽  
Storage Capacity ◽  
Drainage System ◽  
Urban Drainage ◽  
Real Time Control ◽  
Drainage Systems ◽  
Time Control ◽  
Controlled Systems ◽  
Urban Drainage Systems ◽  
The Difference

The LOCUS modelling package, which has been designed to assess the performance of an urban drainage system that is controlled in real time is presented. Besides the simulation of 'optimal' controlled systems, LOCUS offers the possibility to simulate local (or static) controlled systems as well (i.e. the present way of operation of most urban drainage systems). Since an identical system description is used in both cases, the difference between the results is only due to the way the system is operated and hence the effects of real time control can be quantified by comparing the results. The use of the model is illustrated by a simple example, which shows that it is worth investigating the potential of real time control before constructing extra storage in the system. For a small fictitious system with limited storage capacity at the downstream section it is shown that this potential is comparable to increasing the storage capacity by 1.5 mm at this particular section.

scholarly journals Research on Aircraft Surface Taxi Path Planning and Conflict Detection and Resolution

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Ningning Zhao ◽  
Nan Li ◽  
Yu Sun ◽  
Lei Zhang
Keyword(s):  
Time Window ◽  
Time Windows ◽  
Conflict Detection ◽  
Real Time Control ◽  
A Algorithm ◽  
Use Of Time ◽  
Time Control ◽  
Control Decision ◽  
The Difference ◽  
Glide Paths

Aircraft surface taxiing conflict avoidance is mostly adopted by waiting and rerouting methods, but this method does not consider the difference in total taxiing time that may be caused by different strategies. In this study, the airport taxiing path optimization model and taxiing area division model are constructed first. Then, the taxiway use is controlled by subregion based on the analysis of the surface activity area connection relationship. Based on the results of aircraft surface taxiway preselection, the time window of the taxiing area is solved and conflict detection is performed. For aircraft with taxiing conflicts, waiting or changing paths is selected to deconflict taxiing by comparing priorities. An improved A∗ algorithm solution is applied to generate conflict-free glide paths and new glide trajectory occupancy time windows, while the glide paths of aircraft without glide conflicts are not affected. The results of the study show that the use of time windows for conflict detection and deconfliction can further reduce the total taxiing time of aircraft operating on the surface, resulting in a significant reduction in the number of aircraft conflicts, and thus, airport operational safety is ensured. This study has a high practical value and is expected to be applied in the real-time control decision of aircraft taxiing in the future.

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