scholarly journals A Simulation-Based Dynamic Programming Method for Interchange Scheduling of Port Collecting and Distributing Network

2018 ◽  
Vol 2018 ◽  
pp. 1-17 ◽  
Author(s):  
Yun Peng ◽  
Wenyuan Wang ◽  
Xinglu Xu ◽  
Modi Chen ◽  
Xiangqun Song ◽  
...  

As one of the effective methods to reduce congestion, grade intersection has already been changed to interchange in port collecting and distributing network (PCDN) of many Chinese ports, since the first interchange was built in the PCDN of Dalian port in 1924. Due to the growing demand for port freight transportation, congestion in PCDN is becoming one of the inevitable problems that need to be solved. This paper addresses the best interchange scheduling multistage decision problem in PCDN at a network level. The main challenges are how to estimate the delay time and cope with high uncertainties in port network and PCDN. Therefore, a simulation-based dynamic programming (DP) model is proposed with the purpose of minimizing total cost in lifetime period by combining a DP model and two nested simulation models together. Two simulation models are built to figure out the delay cost in the optimization model, which cannot be calculated by mathematical analysis due to complex vehicle travel patterns and irregular traffic volume caused by random events, such as the arrival pattern of ships’, natural conditions, and storage period of cargos. Finally, a real project in northern China is presented as a case study. The proposed method can be applied in similar cases and can help solve analogous complicated multistage problems.

Author(s):  
Thorsten Plum ◽  
Marius Wegener ◽  
Markus Eisenbarth ◽  
Ziqi Ye ◽  
Konstantin Etzold ◽  
...  

An increasing level of driving automation and a successive electrification of modern powertrains enable a higher degree of freedom to improve vehicle fuel efficiency and reduce pollutant emissions. Currently, both domains themselves, driving automation as well as powertrain electrification, face the challenge of a rising development complexity with extensive use of virtual testing environments. However, state-of-the-art virtual testing environments typically strictly focus on just one domain and neglect the other. This paper shows the results of a simulation-based case study considering both domains simultaneously. The influence of energy saving automated functionalities on a conventional, a hybrid, and a pure electric powertrain is investigated for a carefully selected inner-city driving scenario. The vehicle simulation models for the different powertrain configurations are calibrated using test bench results and vehicle measurements. A model predictive acceleration controller is developed for realizing the speed optimization function. By considering traffic conditions such as traffic light schedules and a preceding vehicle as the boundary conditions, unnecessary accelerations and decelerations are avoided to reduce the energy demand. The case study is realized by applying this function to the three powertrains variants. As a final result, a clear difference in energy demand is observed: the hybrid powertrain benefits the most in terms of energy demand reduction in the given use case. The results clearly underscore that in future vehicle development programs, the powertrain and the real-world driving functionalities have to be optimized simultaneously to minimize the energy demand during everyday vehicle operation.


2019 ◽  
Vol 25 (7) ◽  
pp. 1802-1821 ◽  
Author(s):  
Fatih Cavdur ◽  
Betul Yagmahan ◽  
Ece Oguzcan ◽  
Nazli Arslan ◽  
Nurbanu Sahan

Purpose The purpose of this paper is to present a methodology for using simulation models together with value stream mapping (VSM) for designing lean service systems and illustrate it with a case study. Design/methodology/approach The authors propose a methodology combining simulation and VSM. Simulation models for both current and future states are developed to validate the results of the corresponding maps of current and future states, respectively. Findings The results illustrate the advantages of the suggested design represented by the future state map. Additionally, using simulation models together with VSM for validating current and future states also allows decision makers to perform comprehensive analyses on the system and draw statistical conclusions. Originality/value Although some lean applications in educational services exist in previous studies, according to the best of the authors’ knowledge, this study is the first one combining VSM and simulation for the implementation of the lean concepts in the construction and technical services of a public university.


2021 ◽  
Vol 12 (9) ◽  
pp. s843-s855
Author(s):  
Larissa Moreira Alves de Souza Souza ◽  
Adriano Maniçoba da Silva ◽  
Julio Maria de Souza ◽  
Regis Cortez Bueno ◽  
Sivanilza Teixeira Machado ◽  
...  

Flexible manufacturing processes improve profitability and competitiveness for the company through an efficient process, with quality in a short time, and contribute to achieving low costs. One of the approaches that have been currently developed to improve the flexible manufacturing process is simulation. Simulation models consist of an assertive and powerful tool in strategic planning.  It permits a controlled way of the company's reality so that it was possible to study and analyze the organization's current situation under several circumstances without altering the production's physical environment and involving low costs. Accordingly, this study's primary purpose was to develop a simulation model to verify bottlenecks' existence in the bearing manufacturing process. For this, a case study is presented, and it was used modeling/simulation with Arena Software as a research method. The results showed no bottlenecks in the manufacturing process.


Author(s):  
Clint Alex Steed

Purpose This paper aims to present an approach for the simulation of a heterogeneous robotic cell. The simulation enables the cell’s developers to conveniently compare the performance of alternative cell configurations. The approach combines the use of multiple available simulation tools, with a custom holonic cell controller. This overcomes the limitation of currently available robot simulation packages by allowing integration of multiple simulation tools including multiple vendor simulation packages. Design/methodology/approach A feeding cell was developed as a case study representing a typical robotic application. The case study would compare two configurations of the cell, namely, eye-in-hand vision and fixed-camera vision. The authors developed the physical cell in parallel with the simulated cell to validate its performance. Then they used simulation to scale the models (by adding subsystems) and shortlist suitable cell configurations based on initial capital investment and throughput rate per unit cost. The feeding cell consisted of a six-degree of freedom industrial robot (KUKA KR16), two smart cameras (Cognex ism-1100 and DVT Legend 500), an industrial PC (Beckhoff) and custom reconfigurable singulation units. Findings The approach presented here allows the combination of dissimilar simulation models constructed for the above mentioned case study. Experiments showed the model developed in this approach could reasonably predict various eye-in-hand and fixed-camera systems’ performance. Combining the holonic controller with the simulation allows developers to easily compare the performance of a variety of configurations. The use of a common communication platform allowed the communication between multiple simulation packages, allowing multi-vendor simulation, thereby overcoming current limitation in simulation software. Research limitations/implications The case study developed here is considered a typical feeding and assembly application. This is however very different from other robotic applications which should be explored in separate case studies. Simulation packages with the same communication interface as the physical resource can be integrated. If the communication interface is not available, other means of simulation can be used. The case study findings are limited to the specific products being used and their simulation packages. However, these are indicative of typical industry technologies available. Only real-time simulations were considered. Practical implications This simulation-based approach allows designers to quickly quantify the performance of alternative system configurations (eye-in-hand or fixed camera in this case) and scale, thereby enabling them to better optimize robotic cell designs. In addition, the holonic control system’s modular control interface allows for the development of the higher-level controller without hardware and easy replacement of the lower level components with other hardware or simulation models. Originality/value The combination of a holonic control system with a simulation to replace hardware is shown to be a useful tool. The inherent modularity of holonic control systems allows that multiple simulation components be connected, thereby overcoming the limitation of vendor-specific simulation packages.


2019 ◽  
Author(s):  
Michael Petronis ◽  
◽  
Vincent Twomey ◽  
William McCarthy ◽  
Craig MaGee
Keyword(s):  

2021 ◽  
Vol 57 ◽  
pp. 126939
Author(s):  
Mari Ariluoma ◽  
Juudit Ottelin ◽  
Ranja Hautamäki ◽  
Eeva-Maria Tuhkanen ◽  
Miia Mänttäri

Sign in / Sign up

Export Citation Format

Share Document