Witness Simulation Software Research Articles

Multiagent-Based Modeling and Simulation of a Coal Multimodal Transport System

With the change in coal supply and demand, the dynamics of multiple transit nodes and the connection between different transportation modes make the Coal Multimodal Transportation System (CMTS) more complicated in the long-distance transportation of coal. Therefore, it is necessary to analyze the multimodal transportation nodes, build a coal multimodal transportation model, measure the network throughput through simulation experiments, and identify system bottlenecks. The CMTS is a complex nonlinear dynamic system with many participants with complex and uncertain links. Different transportation modes, operation links, and connection processes will affect system performance, and modeling and simulation technology effectively study complex dynamic systems. This paper takes the CMTS as the research object, uses agent-based modeling methods and Witness simulation software to analyze the composition and operation mechanism of CMTS, establishes the multiagent model of CMTS, and validates the model by a Witness simulation experiment of northern coal shipped to south. The simulation results indicate the capacity of the transport route and resource utilization of nodes in CMTS in case of different demand growth rates in the future. Based on the multiagent model andWitness simulation results, this paper provides practical support for constructing and applying the multimodal transport system model library and provides the basis for decision-making for the CMTS plan.

Layout optimization of workshop equipment based on WITNESS

According to the production order, the engine parts workshop of a company mainly produces four parts: valve hydraulic tappet, camshaft, camshaft gear and bearing cover. With the increasing demand of production, the production capacity brought by the original workshop equipment layout gradually cannot meet the increasing demand. In this paper, based on the WITNESS simulation software, we are preparing to collect the data of engine parts and components production workshop in order to get the data information of each element by simulation, and reasoning the unreasonable parts where the busy rate is too high and put forward several improvement methods. Through WITNESS software simulation, respectively, we can analyse whether there will have improvement and conclude the optimal improvement project. As the busy rate of lathe group and milling machine group of the original workshop layout is more than 80%, while the statistics are less than 60% by using the optimal plan to improve the existing layout, reaching a reasonable busy rate. It can be concluded that it is feasible to solve the problem of high work step busy rate and improve the overall production efficiency of the workshop through reasonable equipment layout optimization.

Modelling green multimodal transport route performance with witness simulation software

This study proposes an approach for dynamically calculating multimodal transport line parameters based on a “Witness” software simulation. The approach is designed to reduce the carbon emissions of multimodal transport, as green transportation has recently received increased attention. A multi-objective multimodal transport efficiency evaluation framework is combined with an order relation analysis and an entropy-weight fuzzy analytical hierarchy process method to assess route performance under various multimodal transport schemes. This study validated the proposed approach using the China-Europe railway network from Wuhan, China to Berlin, Germany. The results are as follows: (1) the energy conservation and emission reduction values of a multimodal transport scheme fluctuate significantly, and it is scientifically appropriate to increase the energy conservation and emission reduction values as the indexes for scheme planning; (2) a multi-objective and multi-scenario efficiency evaluation method can provide a solution for green multi-modal transport route planning, and can reduce energy usage and emissions by 24% as compared to an optimal routing considering a single objective; and 3) the China-Europe railway express has unique advantages in a multi-modal transport network, as it can save more than 60% of the transport time and reduce the carbon emissions by 40% as compared with a traditional water transport. This study presents a green multi-modal transport organization approach.

The validation of productivity on the changeover activity at the automotive stamping press line by comparing the embedded SMED frame-work versus SMED approach: A witness simulation case study

Single-Minute Exchange of Die (SMED) is a popular method used to optimize the die change processing time. The purpose of this study is to identify on how to reduce set-up time by using Embedded SMED in automotive stamping press line. An actual case study at an automotive company XYZ in Malaysia was conducted based on parts supply issues. The observations, assessments and standard manufacturing practices were carried out during the study. WITNESS simulation software was used to identify the critical processes and also enable the validation of actual output based on the production. The result of the particular press line (combination of 800 Tons and 500 Tons machines) which produced 6 parts in 1-shift operations with small lot size output has been identified and improved. The significant improvement based on the Embedded SMED compared to conventional SMED approach showed a decreasing change-over time from an average of 12.51 minutes to 9.41 minutes (effectively a single-digit minute) resulting in circa 62% reduction.

INVESTIGATION OF AN ELEVATOR DISPATCHER SYSTEM

To provide an efficient elevator system, a variety of diverse and sometimes conflicting constraints have to be solved. This paper focuses on using discrete event simulation as a means to model and explore elevator dispatching strategies. Witness simulation software has been used as a test-bed for model building, simulation and some experimentation. Model building using Witness model elements is described in detail followed by two different elevator call strategies. The main steps in the methodology are described with reference to a single elevator servicing a five-storey office building. The elevator call strategies are simulated and results compared. It was found that the data set significantly skews the results and overshadows any efficiency gains that might be possible from the different dispatching strategies. The paper concludes with the need to carefully select the data set as the basis for simulation comparisons and outlines future work required.

Assembly Line Efficiency Improvement by Using WITNESS Simulation Software

In the nowadays-competitive world, efficiencies and the productivity of the assembly line are essential in manufacturing company. This paper demonstrates the study of the existing production line performance. The actual cycle time observed and recorded during the working process. The current layout was designed and analysed using Witness simulation software. The productivity and effectiveness for every single operator are measured to determine the operator idle time and busy time. Two new alternatives layout were proposed and analysed by using Witness simulation software to improve the performance of production activities. This research provided valuable and better understanding of production effectiveness by adjusting the line balancing. After analysing the data, simulation result from the current layout and the proposed plan later been tabulated to compare the improved efficiency and productivity. The proposed design plan has shown an increase in yield and productivity compared to the current arrangement. This research has been carried out in company XYZ, which is one of the automotive premises in Pahang, Malaysia.

Improvement of productivity in low volume production industry layout by using witness simulation software

In almost all manufacturing industry, increased productivity and better efficiency of the production line are the most important goals. Most factories especially small scale factory has less awareness of manufacturing system optimization and lack of knowledge about it and uses the traditional way of management. Problems that are commonly identified in the factory are a high idle time of labour and also small production. This study is done in a Small and Medium Enterprises (SME) low volume production company. Data collection and problems affecting productivity and efficiency are identified. In this study, Witness simulation software is being used to simulate the layout and the output is focusing on the improvement of layout in terms of productivity and efficiency. In this study, the layout is rearranged by reducing the travel time from a workstation to another workstation. Then, the improved layout is modelled and the machine and labour statistic of both, original and improved layout is taken. Productivity and efficiency are calculated for both layout and then being compared.

Route optimization for the cement industry under the CPEC initiative

The China-Pakistan Economic Corridor (CPEC) initiative envisages substantial infrastructure development in Pakistan. This study ascertains optimal transportation routes for the cement industry under the CPEC program using a mixed integer linear programming model and discrete-event simulation using Witness simulation software. The solution of the mathematical model presents the best combination of cement manufacturing clusters, road interchanges and ports to connect. Policy makers and practitioners can use the findings of this study to optimize logistics decisions under CPEC.

PRACTICAL PRODUCTION LAYOUT DESIGN FOR MULTI-PRODUCT AND SMALL-LOT-SIZE PRODUCTION: A CASE STUDY

Facility layout design has an important function in manufacturing systems because it affects manufacturing costs, work in progress, lead times, and production output. This study presents facility layout designs for multi-product and small-lot-sized production lines. This research focuses on the development and analysis of layout alternatives on the basis of performance measures and aims to improve production efficiency. Thus, the tools and techniques available for the layout designed were investigated. Related data were collected, and alternative layouts were developed using the WITNESS simulation software. Finally, the alternative layouts were ana1yzed and evaluated using the analytic hierarchy process to identify the best possible layout. Two important parameters observed in the alternative layouts: the ability to produce a desired output and the flexibility of each layout coherent with the fluctuation of product demands in the industry. Results from analysis shows that suggested Model 3 with the combination of flow line and job shop configurations is the most suitable layout. This model has the highest machine utilization rate and the highest labour utilization rate yet requires only 21 operators, the lowest number of workers. For future work, this type of layout should be tested with different variation in lot sizes.

Simulation and Optimization Study on Layout Planning of Plant Factory Based on WITNESS

The emergence of plant factory has solved great restriction problem of natural environment in the traditional agriculture. Therefore, it has been the research concentrate on the facility agriculture in recent years. However, the reasonability of factory's production process and layout determines quality of the product, production efficiency and economic benefits. This paper took Wuchang Jingtian Plant Factory as an example, analyzed the production process and layout and provided a corresponding improvement scheme which was verified by the WITNESS simulation software. An optimal solution was determined from the evaluation index of production efficiency, busy rate, production cycle etc.. Besides, the simulation analysis of production cost before and after the improvement verified the improved plant factory operation is effective and feasible. This improvement scheme not only improved efficiency of production system of the plant factory, but also reduced the operating cost.

Application of re-layout approach for cellular layout in manual assembly process

This study presents a conversion approach for cellular layout in facility planning. At present, efficiency and flexibility of production lines are highly important to satisfy the urgency and variability of consumer demands in manufacturing enterprises. To achieve high efficiency and high productivity to satisfy customer orders, a systematic methodology of the conversion process is conducted to integrate similar groups into cellular layout. The converted cellular layout is tested by WITNESS simulation software. The performances of converted cellular layouts are analysed by analysis of variance (ANOVA). Finally, one cell line layout is observed to be effective in terms of low, medium, and high volume with different types of varieties.

Exploiting witness for traffic simulation

Traffic congestion in urban cities is an increasing problem. Not only does it lead to an increase in pollution, but the time spent waiting in traffic queues wastes valuable time in addition to causing frustration. A system that can control and manage traffic efficiently is one way that this issue can be reduced.A specific road traffic intersection in South Manchester, UK, was selected for investigation as it experiences high levels of traffic flow through it during the evening peak time. This has led to large queues and long waiting times due to the fixed timings of the traffic lights. This paper explores strategies to better control the traffic flow through it. A model of the selected traffic junction has been built using Witness simulation software. Data for this junction has been obtained partially from observations and mostly from traffic surveys enabling a simulation of the traffic flow. Analysing the results allowed two alternative scenarios to be developed and simulated. Results from one of the scenarios showed noticeable reductions in the average queue waiting times at the traffic junction.

Enterprise Inventory Management and Simulation

Inventory is an important link in supply chain, according to characteristics and objectives of inventory control, the reasonable safety inventory, order point, the highest inventory and inventory strategy were determined based on historical sales data. Using Witness simulation software, the optimal strategy was selected from nine inventory strategies by running simulation model for one year. If goods shortage was allowing, the seventh schemes (72000,158100) was better ,the minimum total cost was 888158 yuan ; considering allowing a small amount of shortage, the cost of eighth schemes ( 82000,158100) was least of 1095167; the third scenarios (92000,138100) was selected if without shortage, and the minimum total cost was 1254909 yuan. This shows, the application of computer simulation to assist in the management of inventory is scientific and feasible, it can help enterprises to save the order and operation cost.

Healthcare system simulation using Witness

Simulation techniques have a proven track record in manufacturing industry as well as other areas such as healthcare system improvement. In this study, simulation model of a health center in Malaysia is developed through the application of WITNESS simulation software which has shown its flexibility and capability in manufacturing industry. Modelling procedure is started through process mapping and data collection and continued with model development, verification, validation and experimentation. At the end, final results and possible future improvements are demonstrated.

High-Mix Low-Volume Flow Shop Manufacturing System Scheduling

The paper deals with the production scheduling optimization in High-Mix Low-Volume (HMLV) flow shop manufacturing system. Three new heuristic production scheduling algorithms balancing the machines assignment to the production orders are proposed. The goal of the algorithms is to find a production schedule that minimizes the total production time of the set of jobs - makespan. An example case study, where the proposed scheduling algorithms are verified and compared with basic solutions using the simulation model of the HMLV manufacturing system created in Witness simulation software, is presented.

Simulation on Efficency of Mobile Rack in Medicine Warehouse

Mobile racks are used broadly in warehouse, especially in those with low items and large stock-keeping unit (SKU). However, contraction between storage capacity and rack efficiency may restrict the usage of mobile racks. Such an example in medicine industry was offered in this paper. Using Witness simulation Software, a model has been developed for medicine warehouse with mobile rack system. Simulations have been executed to analyze rack efficiency in five different scenarios. All scenarios embodied more or less low efficiency and long line in front of buffers. Results indicated that efficiency relies on policies of order-picking and space allocation. It can also be concluded that the minority items of small quantities and low frequency may decide the performance of the whole system.

Multi-objective supply chain sourcing strategy design under risk using PSO and simulation

Sourcing strategy design in a supply chain is vital to gain competitive advantage. In recent years, supply chain risks are growing significantly and supplier failure is identified as one of the top supply chain risks. Researchers attempt to mitigate the negative impacts of supplier failure by applying strategies such as local versus global sourcing, single versus dual/multiple-sourcing, performance-based supply contracts, and optimizing the order allocation among suppliers. Global sourcing is a widely recognized strategy among firms, and it involves a trade-off between reliable, high-cost local suppliers and unreliable, low-cost offshore suppliers. The global sourcing is associated with the risks of exchange rate volatility, trade restrictions, longer lead time, and problems with supplier reliability. Sourcing strategy design considering price, exchange rate risks, and supplier delivery reliability is an important research topic and needs attention. In this work, a hybrid optimization and simulation approach is proposed to design the supply chain sourcing strategy. In the optimization approach, a multi-objective binary particle swarm algorithm is developed for minimizing the total cost and maximizing the supplier delivery reliability. Selected scenarios from the optimization results are modeled using Witness simulation software to evaluate the robustness of sourcing strategies under price, exchange rate and demand risks. The proposed approach is exemplified using a real-life case study of a plastic product manufacture in India.

Linking the Witness Simulation Software to an Expert System to Represent a Decision�Making Process

Expert systems, and artificial intelligence more generally, can provide a useful means for representing decision-making processes. By linking expert systems software to simulation software an effective means of including these decision-making processes in a simulation model can be achieved. This paper demonstrates how a commercial-off-the-shelf simulation package (Witness) can be linked to an expert systems package (XpertRule) through a Visual Basic interface. The methodology adopted could be used for models, and possibly software, other than those presented here.