Simulations on field uniformity in a triangular reverberation chamber

This article presented the results of an electromagnetic field analysis inside a rectangular and triangular reverberation chamber being attached to the Schroeder Quadratic Residue Diffusers (QRD). Simulation results showed that a triangular chamber, which had more mode distribution than the rectangular chamber in the defined volume, had advantages of producing improved field uniformity. © 2002 Wiley Periodicals, Inc. Int J RF and Microwave CAE 12: 198–205, 2002.     

Product Mix Optimization for Semiconductor Manufacturing Based on AHP and ANP Analysis

In a competitive market, a company needs to utilize its available capacity efficiently in order to acquire high profit. The purpose of this paper is to present effective approaches to find a set of product mix optimal for the company to achieve the optimal manufacturing. Analytic hierarchy process (AHP) and analytic network process (ANP) approaches are taken to analyse multiple process inputs and outputs, incorporating experts’ opinion on their priority of importance, to obtain optimal product mixes for semiconductor production. The results provide guidance to the fabricator regarding strategies for accepting orders to maximize the manufacturing efficiency and the profit, while simultaneously considering other important input and output factors for maintaining manufacturing smoothness.     

Laser Process Proximity Correction for Improvement of Critical Dimension Linearity on a Photomask

We report on the improvement of critical dimension (CD) linearity on a photomask by applying the concept of process proximity correction to a laser lithographic process used for the fabrication of photomasks. Rule‐based laser process proximity correction (LPC) was performed using an automated optical proximity correction tool and we obtained dramatic improvement of CD linearity on a photomask. A study on model‐based LPC was executed using a two‐Gaussian kernel function and we extracted model parameters for the laser lithographic process by fitting the model‐predicted CD linearity data with measured ones. Model‐predicted bias values of isolated space (I/S), arrayed contact (A/C) and isolated contact (I/C) were in good agreement with those obtained by the nonlinear curve‐fitting method used for the rule‐based LPC.     

Thermotropic polyester amide-carbon fiber composites

Liquid crystal polymers (LCP) have been developed for the first time as a thermoplastic matrix for high-performance composites. A successful melt impregnation method has been developed that results in the production of continuous carbon fiber (CF)-reinforced LCP prepreg tape. Subsequent layup and molding of prepreg into laminates has yielded composites of good quality. Tensile and flexural properties of LCP-CF composites are comparable to those of epoxy-CF composites. LCP-CF composites have better impact resistance than the latter, although epoxy-CF composites possess superior compression and shear strength. LCP-CF composites have good property retention until 200°F (67% of room temperature value). Above 200°F, mechanical properties are found to decrease significantly. Experimental results indicate that the poor compression and shear strength may be due to the poor interfacial adhesion between the matrix and carbon fiber.     

Benzene‐di‐N‐substituted carbamates as conformationally constrained analogs of Pseudomonas lipase substrates

Benzene‐1,2‐, ‐1,3‐, and ‐1,4‐di‐N‐substituted carbamates ( 1 – 15 ) are synthesized as the constrained analogs of gauche, eclipsed, and anti conformations of diesters of ethylene glycol, respectively. Carbamates 1 – 15 are characterized as the pseudo‐substrate inhibitors of Pseudomonas species lipase. Long‐chain carbamates are more potent inhibitors than short‐chain ones. Different geometries of benzene‐di‐substituted carbamates, such as benzene‐1,2‐di‐N‐octylcarbamate ( 3 ) (ortho compound), benzene‐1,3‐di‐N‐octylcarbamate ( 8 ) (meta compound), and benzene‐1,4‐di‐N‐octylcarbamate ( 13 ) (para compound), show similar inhibitory potencies for the enzyme. In other words, kinetic data suggest that the enzyme does not discriminate ortho, meta, and para geometries of these constrained analogs.     

Solution phase synthesis of amyloid-cleaving catalysts, two [1,3,5]triazine based compounds

Solution phase synthetic method for amyloid-cleaving catalysts was developed, which bears triazine core, scaffold with bulky and that have various solubility properties; Co(III) complex of cyclen (1,4,7,10-tetraazacyclododecane) for catalytic group, and two imaging agents for binding group. This synthetic method was identified by H-NMR, C-NMR for intermediates and MS for the last products. The yields by this method surpassed solid phase synthesis and took much lower labor, expense, and time. The products which were synthesized by solution phase synthetic method showed good catalytic activities.     

Mechanical analysis of woven composites at high strain rates and its application to predicting impact behavior

The deformation behavior of woven composites at high strain rates was analyzed using a constitutive equation developed to describe the nonlinear, anisotropic/asymmetric and rate-dependent mechanical behavior of woven composites. The rate-dependent nonlinear behavior of woven composites was characterized at high strain rates (1 s⁻¹ to 100 s⁻¹) using a tensile testing method first proposed in this research. The material properties for the developed constitutive equation were determined and subsequently used in a finite element analysis of the deformation behavior of woven composites at high strain rates. Finally, the impact behavior of woven composites was predicted using the constitutive equation and the results were compared with experiments, showing that the current constitutive equation including the characterization method is adequate to describe the deformation behavior of woven composites at high strain rates up to impact level.     

Electrochemical recovery of silver from waste aqueous Ag(I)/Ag(II) redox mediator solution used in mediated electro oxidation process

The paper presents a process for the electrochemical recovery of silver(Ag) by electro deposition on the electrode surface from the waste solutions of Ag(I)/Ag(II) redox system in nitric acid medium used for the mediated electrochemical process. Electrochemical recovery was carried out in an undivided cell with DSA-O₂ electrodes at room temperature condition. At an optimized current density of 12 A/dm², 99% of Ag recovery efficiency was achieved with high yield and low energy consumption. Experimental runs were made in order to observe the performance of the Ag recovery process. The operating conditions like current density, temperature and Ag(I) concentration of the electrolyte, the acid concentrations, agitation rate and inter-electrode distance were optimized.     

Diversity codes for differential phase modulation in a correlatedRayleigh fading channel

This paper proposes a simple diversity scheme that makes use of nonlinear block coding, symbol interleaving, and differential phase modulation. The resultant signaling mechanism merits intrinsic time diversity within each codeword, which is resistant to correlated fading. The maximum-likelihood noncoherent receiver which operates over correlated Rayleigh fading is developed. Exact and approximate upper bounds are derived to assess the codeword-error probability characteristics of the proposed system     

The viscoelastic bending stiffness of fiber-reinforced composite Ilizarov C-rings

In order to optimize the design of unidirectional fiber-reinforced composite (Ilizarov) C-rings, the viscoelastic load relaxation behavior was analyzed under a point load. Initially, the deflection and bending stiffness were calculated from the Castigliano theorem and the Euler–Bernoulli bending theory for the elastic solution. The viscoelastic relaxation and creep behavior were then derived from the elastic solution by using the correspondence theorem. Besides the orthotropic mechanical properties of the composite, the asymmetric mechanical properties due to different tensile and compressive properties were also considered. With the exception of the deviation, which was affected by a relatively large thickness ratio to the radius of the C-ring, the calculated relaxation showed good agreement with the experimental result.