Simulation support of lean layout considerations for new products: a case from large scale products

Planning a new production line for a product presents many opportunities to build best practice techniques into the new system. Set against the unknown quantities may be certain requirements for the production system to be lean, to have the flexibility to respond to market changes or make use of existing equipment of factory space. The unknown quantities can include: anticipated demand volumes, assembly and processing sequences, the specific production processes, lead-times of parts and components and even late changes to the product design after manufacturing/production decisions have been made. Simulations of a production system can be used to consider different scenarios and compare how well alternative approaches meet the defined requirements. [Continues.

Analyse du processus d'élaboration d'un projet de simulation

International audienceNous présentons dans cet article une étude orientée sur l'analyse du processus d'élaboration d'un projet de simulation de système de production. Après avoir présenté un état de l'art traitant de cette problématique, nous détaillons le cadre d'élaboration d'un processus de simulation à travers la présentation des différentes étapes le constituant ainsi que celle des délivrables qui lui sont associés. Nous donnons ainsi la vision que nous avons de ce processus. L'accent est en particulier mis sur le rôle déterminant de la première étape qui vise à identifier et caractériser le besoin à l'origine du projet de simulation, généralement un problème à résoudre, et à évaluer la capacité de l'outil de simulation à évènements discrets à répondre efficacement à ce besoin. Nous proposons ensuite une classification des outils de simulation actuellement présents sur le marché en fonction de l'approche de modélisation utilisée, à savoir les outils orientés " fonction " ou " processus " et les outils orientés " composant " ou " objet ". Ainsi, après une description assez brève de ces approches de modélisation, nous présentons certains des avantages et des inconvénients de chaque type d'outil par rapport à un point de vue de l'utilisateur potentiel

A Methodology for Continuous Quality Assurance of Production Data

High quality input data is a necessity for successful Discrete Event Simulation (DES) applications, and there are available methodologies for data collection in DES projects. However, in contrast to standalone projects, using DES as a day-to-day engineering tool requires high quality production data to be constantly available. Unfortunately, there are no detailed guidelines that describes how to achieve this. Therefore, this paper presents such a methodology, based on three concurrent engineering projects within the automotive industry. The methodology explains the necessary roles, responsibilities, meetings, and documents to achieve a continuous quality assurance of production data. It also specifies an approach to input data management for DES using the Generic Data Management Tool (GDM-Tool). The expected effects are increased availability of high quality production data and reduced lead time of input data management, especially valuable in manufacturing companies having advanced automated data collection methods and using DES on a daily basis

Supporting Discrete Event Simulation with 3D Laser Scanning and Value Stream Mapping: Benefits and Drawbacks

Discrete Event Simulation (DES) has been applied to analyze and understand production systems for many decades, however the models created may not accurately represent the spatial data of the system. 3D laser scanning can be utilized to capture and digitalize the spatial data of production systems, giving proper references for the simulation model. This paper evaluates the benefits and drawbacks of using a DES model supported with Value Stream Mapping (VSM) and 3D laser scanning to analyze a low volume production system. Results show benefits in several steps of a DES study, mainly at the cost of simulation speed

Simulation in Automated Guided Vehicle System Design

The intense global competition that manufacturing companies face today results in an increase of product variety and shorter product life cycles. One response to this threat is agile manufacturing concepts. This requires materials handling systems that are agile and capable of reconfiguration. As competition in the world marketplace becomes increasingly customer-driven, manufacturing environments must be highly reconfigurable and responsive to accommodate product and process changes, with rigid, static automation systems giving way to more flexible types. Automated Guided Vehicle Systems (AGVS) have such capabilities and AGV functionality has been developed to improve flexibility and diminish the traditional disadvantages of AGV-systems. The AGV-system design is however a multi-faceted problem with a large number of design factors of which many are correlating and interdependent. Available methods and techniques exhibit problems in supporting the whole design process. A research review of the work reported on AGVS development in combination with simulation revealed that of 39 papers only four were industrially related. Most work was on the conceptual design phase, but little has been reported on the detailed simulation of AGVS. Semi-autonomous vehicles (SA V) are an innovative concept to overcome the problems of inflexible -systems and to improve materials handling functionality. The SA V concept introduces a higher degree of autonomy in industrial AGV -systems with the man-in-the-Ioop. The introduction of autonomy in industrial applications is approached by explicitly controlling the level of autonomy at different occasions. The SA V s are easy to program and easily reconfigurable regarding navigation systems and material handling equipment. Novel approaches to materials handling like the SA V -concept place new requirements on the AGVS development and the use of simulation as a part of the process. Traditional AGV -system simulation approaches do not fully meet these requirements and the improved functionality of AGVs is not used to its full power. There is a considerflble potential in shortening the AGV -system design-cycle, and thus the manufacturing system design-cycle, and still achieve more accurate solutions well suited for MRS tasks. Recent developments in simulation tools for manufacturing have improved production engineering development and the tools are being adopted more widely in industry. For the development of AGV -systems this has not fully been exploited. Previous research has focused on the conceptual part of the design process and many simulation approaches to AGV -system design lack in validity. In this thesis a methodology is proposed for the structured development of AGV -systems using simulation. Elements of this methodology address the development of novel functionality. The objective of the first research case of this research study was to identify factors for industrial AGV -system simulation. The second research case focuses on simulation in the design of Semi-autonomous vehicles, and the third case evaluates a simulation based design framework. This research study has advanced development by offering a framework for developing testing and evaluating AGV -systems, based on concurrent development using a virtual environment. The ability to exploit unique or novel features of AGVs based on a virtual environment improves the potential of AGV-systems considerably.University of Skovde. European Commission for funding the INCO/COPERNICUS Projec

The effects of the returning behaviour in the profitability of customers within fashion e-commerce

Purpose: The purpose of this thesis is to explore how the experience that customers gain by means of their purchasing and returning behaviour affects their profitability for the e-commerce fashion company. More specifically, how the profit per order or per period of time that this customers represent varies, depending on his previous experience. Method: The methodology followed for the present project combined the development of an algorithm to process the available raw data with a case study approach. In the first stage a conceptual model and an algorithm where developed, followed then by an analysis of the data obtained from the output of the model. The results of the analysis were then used to assess the defined research questions. Limitations: The scope of the project is limited to the case of a specific fashion e-commerce company, and the data used corresponds to the year 2009. Findings: Experiencing a return during the first orders of a customer enhances this customer’s confidence in the e-commerce company and increases the customer retention rate. However, customers who make returns from the first orders have higher chances of returning from the future orders they purchase and, therefore, these customers show a lower average profitability per order than those who do not return from those orders.Outgoin

Photovoltaic system with multilevel converter coupled to a compressed air energy storage system for grid integration.

M. Sc. Eng. University of KwaZulu-Natal, Durban 2014.Electricity demand is continuously increasing and nations including South Africa, are looking to exploit renewable energy sources to augment conventional electricity generation. An analysis of electricity demand and supply, the electricity infrastructure and the status of renewable electricity including the progress and plans made thereof in South Africa were carried out. A review of the challenges affecting the bulk exploitation of renewable energy (RE) resources and its future prospects are discussed to determine the sustainability of these efforts. This research investigation focuses on a simulation model designed to harness the energy from the sun through a photovoltaic system. Based on empirical data of environmental conditions, a photovoltaic (PV) system model to generate 30 MW of electricity at Witkop substation, Polokwane (South Africa) was developed and to be fed into the grid. A maximum power point tracker (MPPT) control scheme is utilised to ensure that maximum power can be derived from the PV plant. A modular multi-level converter (MMLC) is utilised to convert the electricity generated by the PV system from direct current (DC) to alternative current (AC). The MMLC coupled to compressed air energy storage (CAES) stores the electricity generated during the day and injects it into the grid during peak periods of electricity demand. Mathematical models of the PV system, the MMLC, the CAES and the grid integration were developed, modelled and simulated to describe the electrical behaviour and to establish the ideal operational parameters of the various systems components. Furthermore, validation of the performance of the system components in the simulation model were carried out against manufacturers’ data sheets for similar studies and prototypes. The simulation model were used to combine all the system components effectively into the grid based on the electricity generation system configurations, electricity demand and the environmental conditions of the selected site. More importantly, this investigation seeks to increase the effort of development of PV generation models in the field of renewables when compared to other alternative energy sources such as wind energy generation

Embedding simulation technologies in business processes.

The need to fully integrate simulation as a daily tool has been subject to much attention over the past few years, however little research has previously contributed to this area. This study examines the development of systematic guidelines to enable companies to strategically implement simulation as a mainstream technology within their businesses.An extensive review of the literature was conducted in order to investigate the reasons behind the limited use of simulation and to establish the failure and success factors of companies implementing new technology. The importance of knowledge management in developing simulation technology was also investigated. Additionally, a questionnaire survey was conducted to examine the ways in which simulation technology has been used and developed within different companies. Furthermore, a case study was conducted in order to understand and investigate the processes of implementing simulation in a real organisation.Subsequently, an easy-to-follow framework for enabling companies to embed simulation technologies into their business processes was developed. This framework comprises five key stages, namely: Foundation, Introduction, Infrastructure,Deployment and Embedding. Each stage provides a best practice approach to guide companies in achieving every objective of that stage. Adjustments to the framework were made in the validation and reliability section to reduce any limitations.In creating a relevant and workable framework, this study has contributed significantly to the research gap established within existing simulation integration studies