Optimal design and manufacture of thin‐walled polystyrene structures

In this study, we investigated the implementation of an automatic procedure for optimizing thermoformed thin‐walled structures. Such objects are created in great numbers, especially in the food packaging industry. The methodology for the optimal design of such structures is based on the use of a parameterized geometry model created within an interactive design environment. By varying the parameters associated with the computer‐aided design (CAD) model, one can create a rich variety of possible designs. One can then subject these designs to physical analysis to calculate their physical properties, and thus select an optimal design. The two distinct stages of this process—the prediction of the shape of the thermoformed structure, and the physical behavior of the structure—were validated by experiments. This article reports the experimental investigation of the deformation behavior of polystyrene, the mechanical behavior of specially prepared deformed polystyrene sheets, and the response to loading of a hemispherical structure (used in the validation). POLYM. ENG. SCI., 45:694–703, 2005. © 2005 Society of Plastics Engineers     

A NOTE ON THE REDUCED EFFICIENCY OF THE INDUSTRIAL CYCLONE

In this paper a theoretical investigation into the basis of the reduced efficiency of a conical cyclone is performed. By considering the flow in a region where viscosity is unimportant an analytical solution to the problem is obtained. From this model the performance of the cyclone is evaluated and this can be expressed in terms of three operating and design parameters. One of these parameters is the split ratio, that is the proportion of the volume of fluid entering the cyclone which goes to the underflow. It is demonstrated mathematically that the empirical formula for the reduced efficiency at present in common use is a very good absolute measure of the separating ability of a cyclone.     

Solid-state polymerization of tricosa-10,12-diynoic acid

The -ray polymerization of tricosa-10,12-diynoic acid (CH₃-(CH₂)₉-CC-CC-(CH₂)₈-COOH) crystals has been studied by X-ray diffraction, optical- and scanning electron-microscopy and Raman- and optical-spectroscopy. Up to a conversion of about 60%, the bulk of the polymerization proceeds in a homogeneous single phase. Above about 50% conversion a phase transition, nucleating at crystal defects, occurs. Defect free crystals, which remain in the initial phase above 60% conversion, can be transformed by mechanical deformation. The transformation to the new phase destroys the macroscopic crystalline order but allows further polymerization at a reduced rate.     

A novel polarizer‐free dye‐doped polymer‐dispersed liquid crystal for reflective TFT displays

Abstract— A novel preparation method for dichroic dye‐doped polymer‐dispersed liquid crystals has been developed. This was achieved by creating a porous polymer matrix first by washing out the liquid crystal from a polymer‐dispersed liquid crystal (PDLC), which is then refilled with dye‐doped liquid crystal. Optimizing the liquid crystal used in the refilling results in decreased turn‐on voltage and faster response time. Poster‐standard reflectivity and newspaper‐standard contrast was demonstrated with a 3.8‐in. QVGA reflective TFT display with a drive voltage of 10 V.     

Comparison of memory switching operation in a number of amorphous chalcogenide systems

A number of chalcogenide glasses were investigated for thin film switching applications. Two ranges of threshold voltage were of interest, 15 and 30 V. The switching performance of thin film devices was evaluated and rated on a simple numerical scale. The memory glasses based on the Ge-Te eutectic gave generally satisfactory performance. Selenium-based glasses exhibited high threshold voltage in thin film form, but had limited lifetime. Threshold voltages of about 30 V were obtained from Bi-As-Se glasses; these proved difficult to lock “ON” and possible reasons for this are discussed. Measurements on the bulk properties were used to give an indication of the properties to be expected from thin films of the corresponding glasses.     

Performance evaluation of boundary data structures

Boundary representations, or B-reps, are a solid modeling technique with widespread applications in computer-aided design, computer-aided manufacturing, and robotics. B-reps have evolved considerably in recent years, and advances in theoretic studies-particularly in topological models and associated operators-make it possible now to model nonorientable, nonmanifold objects, as well as orientable, manifold objects. Boundary data structures are normally built on the adjacency relations between faces, edges, and vertices. The analytic method presented here identifies optimal combinations of relations for building these structures