A Dynamic Programming Algorithm for Facility Location and Allocation

This article considers the problem of facility location-allocation. The problem is to allocate K facilities in M facility locations and assign N demands such that the total cost is minimized. The model is formulated as a mathematical programming problem and decomposed into the recursive equations of dynamic programming. A sample problem is presented and analyzed in detail in order to demonstrate an application of the model. The procedure was coded in Fortran IV and used to obtain the sample problem results.     

Use of local area networks within manufacturing systems

Proposals have recently been made within the computer industry to standardize local area computer networking hardware and, although such standards are primarily aimed at the office automation market, they will undoubtedly find many applications in distributed industrial control where a requirement for high speed reliable standardized digital communications also exists. A simple manufacturing cell will be described which demonstrates the advantage of distributed control by using an integrated communications network employing low cost twin axial cable. The individual cell element control systems are supervised by a single computer station providing both control and management information. It will also be shown how such techniques can be applied within industrial manufacturing systems by considering the use of computer networks within a process plant and for the integration of industrial robot systems.     

Spontaneous coronary artery perforation with tamponade. Demonstration by necropsy selective coronary arteriography

Pericardial tamponade in a 51-year-old man after acute anteroseptal myocardial infarction was the result of spontaneous perforation of an atheromatous coronary artery. The value of a simple necropsy technique of selective coronary arteriography in demonstrating the lesion is described.     

Elaboration of cellulose fibrils by Agrobacterium tumefaciens during attachment to carrot cells

The attachment of virulent strains of Agrobacterium tumefaciens to plant cells is the first step in the bacterial induction of tumors. Binding of A. tumefaciens to carrot tissue culture cells occurred as a two-step process. The initial step was the attachment of the bacteria to the plant cell wall. Living plant cells were not required. Bacterial attachment to heat-killed or glutaraldehyde-fixed carrot cells proceeded with only slightly altered kinetics and unaltered bacterial strain specificity. After the bacteria bound to the carrot cell surface, scanning electron microscopy showed that fibrils developed, surrounded the bacteria, and anchored them to the plant cell surface. These fibrils were synthesized by the bacteria and not by the plant cell since they were also made after the attachment of A. tumefaciens to dead carrot cells and since under some conditions the bacteria synthesized fibrils in the absence of plant cells. Calcofluor staining, acid hydrolysis, enzymatic digestion studies, and infrared spectroscopy showed that the fibrils were composed of cellulose. The formation of these cellulose fibrils occurred during the attachment of virulent strains of A. tumefaciens to plant cells in vitro. The fibrils anchored the bacteria to the plant cell surface and entrapped additional bacteria. The multiplication of entrapped and attached bacteria resulted in the formation of large clusters of bacteria held close to the plant cell wall and plasma membrane by cellulose fibrils. This high concentration of bacteria may facilitate transfer of Ti plasmid deoxyribonucleic acid to the plant cell resulting in the formation of tumors.     

Spin‐coated epoxy resin embedding technique enables facile SEM/FIB thickness determination of porous metal oxide ultra‐thin films

A facile nonsubjective method was designed to measure porous nonconductive iron oxide film thickness using a combination of a focused ion beam (FIB) and scanning electron microscopy. Iron oxide films are inherently nonconductive and porous, therefore the objective of this investigation was to optimize a methodology that would increase the conductivity of the film to facilitate high resolution imaging with a scanning electron microscopy and to preserve the porous nature of the film that could potentially be damaged by the energy of the FIB. Sputter coating the sample with a thin layer of iridium before creating the cross section with the FIB decreased sample charging and drifting, but differentiating the iron layer from the iridium coating with backscattered electron imaging was not definitive, making accurate assumptions of the delineation between the two metals difficult. Moreover, the porous nature of the film was lost due to beam damage following the FIB process. A thin layer plastication technique was therefore used to embed the porous film in epoxy resin that would provide support for the film during the FIB process. However, the thickness of the resin created using conventional thin layer plastication processing varied across the sample, making the measuring process only possible in areas where the resin layer was at its thinnest. Such variation required navigating the area for ideal milling areas, which increased the subjectivity of the process. We present a method to create uniform thin resin layers, of controlled thickness, that are ideal for quantifying the thickness of porous nonconductive films with FIB/scanning electron microscopy.     

Evaluation of the Lifetime and Thermal Conductivity of Dysprosia-Stabilized Thermal Barrier Coating Systems

The aim of this study was the further development of dysprosia-stabilized zirconia coatings for gas turbine applications. The target for these coatings was a longer lifetime and higher insulating performance compared to today’s industrial standard thermal barrier coating. Two morphologies of ceramic top coat were studied: one using a dual-layer system and the second using a polymer to generate porosity. Evaluations were carried out using a laser flash technique to measure thermal properties. Lifetime testing was conducted using thermo-cyclic fatigue testing. Microstructure was assessed with SEM and Image analysis was used to characterize porosity content. The results show that coatings with an engineered microstructure give performance twice that of the present reference coating.