Simple heuristics for the assembly line worker assignment and balancing problem

We propose simple heuristics for the assembly line worker assignment and balancing problem. This problem typically occurs in assembly lines in sheltered work centers for the disabled. Different from the classical simple assembly line balancing problem, the task execution times vary according to the assigned worker. We develop a constructive heuristic framework based on task and worker priority rules defining the order in which the tasks and workers should be assigned to the workstations. We present a number of such rules and compare their performance across three possible uses: as a stand-alone method, as an initial solution generator for meta-heuristics, and as a decoder for a hybrid genetic algorithm. Our results show that the heuristics are fast, they obtain good results as a stand-alone method and are efficient when used as a initial solution generator or as a solution decoder within more elaborate approaches.Comment: 18 pages, 1 figur

Analysis of the Hydrogen-rich Magnetic White Dwarfs in the SDSS

We have calculated optical spectra of hydrogen-rich (DA) white dwarfs with magnetic field strengths between 1 MG and 1000 MG for temperatures between 7000 K and 50000 K. Through a least-squares minimization scheme with an evolutionary algorithm, we have analyzed the spectra of 114 magnetic DAs from the SDSS (95 previously published plus 14 newly discovered within SDSS, and five discovered by SEGUE). Since we were limited to a single spectrum for each object we used only centered magnetic dipoles or dipoles which were shifted along the magnetic dipole axis. We also statistically investigated the distribution of magnetic-field strengths and geometries of our sample.Comment: to appear in the proceedings of the 16th European Workshop on White Dwarfs, Barcelona, 200

A line-balancing strategy for designing flexible assembly systems

We present a rough-cut analysis tool that quickly determines a few potential cost-effective designs at the initial design stage of flexible assembly systems (FASs) prior to a detailed analysis such as simulation. It uses quantitative methods for selecting and configuring the components of an FAS suitable for medium to high volumes of several similar products. The system is organized as a series of assembly stations linked with an automated material-handling system moving parts in a unidirectional flow. Each station consists of a single machine or of identical parallel machines. The methods exploit the ability of flexible hardware to switch almost instantaneously from product to product. Our approach is particularly suitable where the product mix is expected to be stable, since we combine the hardware-configuration phase with the task-allocation phase.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45513/1/10696_2004_Article_BF00167513.pd

The generation of floor plans with circulation spaces

Floor plans with interior courtyards, circulation spaces, and prespecified number of exterior rooms, are generated. The approach is graph theoretic, that is, underlying graphs are generated and, then, based on those graphs, the floor plans are constructed.

Enumerating Architectural Arrangements by Generating their Underlying Graphs

One mathematical correspondence to the partitioning of the plane is a Weighted Plane Graph (WPG). This paper first focuses on the systematic generation of WPGs, in a fashion similar to crystal growth. During this process, the WPGs are represented by adjacency matrices. The authors, thus, present a method for embedding the WPG in the plane, given its adjacency matrix. These graphs can, then, be mapped into floor plans. The common practice here is the use of the `geometric dual'of a WPG. The authors propose, instead, the use of the `Pseudogeometric dual'of a WPG directly to translate (part of) a design brief into alternative spatial layouts. Also discussed is the ability to create courtyards and/or circulation spaces given a specific WPG, without increasing the size of the proble

Generating the Underlying Graphs for Architectural Arrangements

The mathematical correspondence to a floorplan is a Metric Planar Graph. Several methods for systematic direct generation of metric planar graphs have been developed including polyominoes, March and Matela and shape grammars. Another approach has been to develop a spatial composition in two separate steps. The first step involves discrete variables, and consists of enumerating a defined set of non-metric planar graphs. The second step involves spatial dimensions, e.g. continuous variables, and maps the graphs onto the Euclidean plane, from which a satisfactory or optimal one is selected. This paper focusses on the latter 2-step process. It presents a general method of solving the first step, that is the exhaustive enumeration of a set of planar graphs. The paper consists of three sections: The first section is an introduction to graph theory. The second section presents the generation of maximal planar graphs. The last section summarizes the presentation and comments on the appropriateness of the metho

Enumerating architectural arrangements by generating their underlying graphs

One mathematical correspondence to the partitioning of the plane is a weighted plane graph (WPG). This paper first focuses on the systematic generation of WPGs, in a fashion similar to crystal growth. During this process, the WPGs are represented by adjacency matrices. We, thus, present a method for embedding the WPG in the plane, given its adjacency matrix. These graphs can, then, be mapped into floor plans. The common practice here is the use of the 'geometric dual' of a WPG. We propose, instead, the use of the 'pseudogeometric dual' of a WPG directly to translate (part of) a design brief into alternative spatial layouts. Also discussed is the ability to create courtyards and/or circulation spaces given a specific WPG, without increasing the size of the problem.