CONCURRENT PRODUCT PORTFOLIO PLANNING AND MIXED PRODUCT ASSEMBLY LINE BALANCING

Reconfigurable products and manufacturing systems have enabled manufacturers to provide ＂cost effective＂ variety to the market. In spite of these new technologies, the expense of manufacturing makes it infeasible to supply all the possible variants to the market for some industries. Therefore, the determination of the right number of product variantsto offer in the product portfolios becomes an important consideration. The product portfolio planning problem had been independently well studied from marketing and engineering perspectives. However, advantages can be gained from using a concurrent marketing and engineering approach. Concurrent product development strategies specifically for reconfigurable products and manufacturing systems can allow manufacturers to select best product portfolios from marketing, product design and manufacturing perspectives. A methodology for the concurrent design of a product portfolio and assembly system is presented. The objective of the concurrent product portfolio planning and assembly system design problem is to obtain the product variants that will make up the product portfolio such that oversupply of optional modules is minimized and the assembly line efficiency is maximized. Explicit design of the assembly system is obtained during the solution of the problem. It is assumed that the demand for optional modules and the assembly times for these modules are known a priori. A genetic algorithm is used in the solution of the problem. The basic premise of this methodology is that the selected product portfolio has a significant impact on the solution of the assembly line balancing problem. An example is used to validate this hypothesis. The example is then further developed to demonstrate how the methodology can be used to obtain the optimal product portfolio. This approach is intended for use by manufacturers during the early design stages of product family design.

Intellectual capital and value creation in the production and assembly of vehicles and auto-parts sector in Brazil： A panel data analysis

This work investigates the relationship between intellectual capital and value creation in the sector of production and assembly of vehicles and auto-parts in Brazil. Through the access of the database from the annual industrial research conducted by the Brazilian Institute of Geography and Statistics, we gathered 865 observations, from 2000 to 2006, of public and private Brazilian companies with more than 100 employees. The database allows the estimate of relevant aggregated variables such as national accounts, gross domestic product, intermediate consumption, as well as propitiates a sectorial study of business strategies and performance, including value added by individual companies. In particular, in this study we use data on variables associated to intellectual capital. To achieve the goal of the study, we consider intellectual capital as defined by Pulic （2000, 2002）, including human capital and structural capital. For the analysis of business performance, we used Pulic＇s VAIC （Value Added Intellectual Cofficient） index as a measure of efficiency of the employed financial and intellectual capital. Regression models were run to verify the relationship among the efficiency in the use of intellectual capital and the profitability of Brazilian companies. The gross income, calculated as before selling, general and administrative expenses, depreciation expenses, amortization and interest expenses, was used as measure of the flows of value creation and the profitability was measured by the gross income to the total assets of the companies. Considering the constructs defined by Pulic （2000, 2002）, we tested, for the Brazilian sector of Production and Assembly of Vehicles and Auto-parts, the following hypotheses： （l） there is a positive relationship between value creation and intellectual capital, （2） there is a positive relationship between value creation and stock of intellectual capital, （3） there is a positive relationship between value creation and efficiency of the employed capital, （4） there is a positive relationship between value creation and efficiency of the human capital, （5） there is a positive relationship between value creation and efficiency of the structural capital. The results of the study, obtained through panel data analysis and through the use static and dynamic models, support the hypotheses that the intellectual capital of the companies, in its flow and stock dimensions, is positively and significantly related to value creation.

The Calculation of Material Requirements Based on BOP in Assembly Production

A calculation method for material requirements which is based on BOP（Bill of Process） in assembly production is presented in this paper. Firstly, the BOP of assembly production is constructed. Then, the calculation method Based on the BOP is brought forward for material requirements planning.

Algorithms for Assembly Type Flowshop Scheduling Problem

An assembly type flowshop scheduling problem with minimizing makespan is considered in this paper. The problem of scheduling for minimizing makespan is first addressed, and then a new heuristic algorithm is proposed for it.

PLANNED LEAD TIME OPTIMIZATION IN MATERIAL REQUIREMENT PLANNING ENVIRONMENT FOR MULTILEVEL PRODUCTION SYSTEMS

This paper deals with the problem of planned lead time calculation in a Material Requirement Planning （MRP） environment under stochastic lead times. The objective is to minimize the sum of holding and backlogging costs. The proposed approach is based on discrete time inventory control where the decision variables are integer. Two types of systems are considered： multi-level serial-production and assembly systems. For the serial production systems （one type of component at each level）, a mathematical model is suggested. Then, it is proven that this model is equivalent to the well known discrete Newsboy Model. This directly provides the optimal values for the planned lead times. For multilevel assembly systems, a dedicated model is proposed and some properties of the decision variables and objective function are proven. These properties are used to calculate lower and upper limits on the decision variables and lower and upper bounds on the objective function. The obtained limits and bounds open the possibility to develop an efficient optimization algorithm using, for example, a Branch and Bound approach. The paper presents the proposed models in detail with corresponding proofs and se＇~eral numerical examples. Some advantages of the suggested models and perspectives of this research are discussed.

Knowledge-Based Curved Block Construction Scheduling and Application in Shipbuilding

To increase efficiency in fierce competition,it is necessary and urgent to improve the standard of production planning for shipbuilding.The construction of curved blocks is the bottleneck to improve the efficiency of shipbuilding.Thus it is a key breakthrough for higher shipbuilding productivity to study the curved block production.By analyzing the scheduling problem in curved blocks production,we propose an intelligent curved block production scheduling method and its system based on a knowledge base,and show the main process of the system.The functions of the system include data management,assembly plan generation,plan adjustment,and plan evaluation.In order to deal with the actual situation and inherit the empirical knowledge,the system extracts some rules to control block selecting,algorithm selection,and evaluation thresholds to build a production decision-making knowledge base in the curved block scheduling system.The proposed knowledge base could be referred and modified by users,especially after a few interactions between the users and the knowledge base.The final assembly plan can be visualized and evaluated to facilitate the observation of plan implementation and effects of the decisions in the process.Finally,the system is verified by a large shipyard in Shanghai using real data and the results illustrate that the proposed method can perform the knowledge-based scheduling for curved blocks construction effectively.