Bioprocess Scale-up for Acetohydroxamic Acid Production by Hyperactive Acyltransferase of Immobilized Rhodococcus Pyridinivorans

Catalysis Letters - In this study, Rhodococcus pyridinivorans cells containing hyperactive acyltransferase was immobilized on various macromolecules based-polymeric matrices and used to improve...     

A Lagrangean heuristic for integrated production and transportation planning problems in a dynamic, multi-item, two-layer supply chain

We present a Lagrangean-based decomposition that is used to generate solutions for an integrated production and transportation planning problem in a two-stage supply chain. This supply chain consists of a number of facilities, each capable of producing the final products, and a number of retailers. It is assumed that the retailers' demands are known and deterministic, and that there are production capacity constraints. The problem is formulated as a multi-commodity network flow problem with fixed charge costs which is a NP-hard problem. An alternative formulation is provided whose linear programming relaxation gives tighter lower bounds. The quality of the lower and upper bounds from the Lagrangean decomposition is tested on a large set of randomly generated problems.     

A High-Rate Optimal Transform Coder With Gaussian Mixture Companders

This paper examines the problem of designing fixed-rate transform coders for sources whose distributions are unknown and presumably non-Gaussian, under input-weighted squared error distortion measures. As a component of this system, a flexible scalar compander based on Gaussian mixtures is proposed. The high-rate analysis of transform coders is reviewed, and extended to the case of input-weighted squared error. An algorithm is developed to set the parameters of the system using a data-driven technique that automatically balances the source statistics, distortion measure, and structure of the transform coder to minimize the high-rate distortion. The implementation of Gaussian mixture companders is explored, resulting in a flexible, low-complexity scalar quantizer. Additionally, modifications to the system for operation at moderate rates, using unstructured scalar quantizers, are presented. The operation of the system for the problem of wideband speech line spectral frequencies (LSF) quantization with log spectral distortion is illustrated, and shown to provide good performance with very low complexity     

Analysis of Multiple-Antenna Systems With Finite-Rate Feedback Using High-Resolution Quantization Theory

This paper considers the development of a general framework for the analysis of transmit beamforming methods in multiple-antenna systems with finite-rate feedback. Inspired by the results of classical high-resolution quantization theory, the problem of finite-rate quantized communication system is formulated as a general fixed-rate vector quantization problem with side information available at the encoder (or the quantizer) but unavailable at the decoder. The framework of the quantization problem is sufficiently general to include quantization schemes with general non-mean-squared distortion functions and constrained source vectors. Asymptotic distortion analysis of the proposed general quantization problem is provided by extending the vector version of the Bennett's integral. Specifically, tight lower and upper bounds of the average asymptotic distortion are proposed. Sufficient conditions for the achievability of the distortion bounds are also provided and related to corresponding classical fixed-rate quantization problems. The proposed general methodology provides a powerful analytical tool to study a wide range of finite-rate feedback systems. To illustrate the utility of the framework, we consider the analysis of a finite-rate feedback multiple-input single-output (MISO) beamforming system over independent and identically distributed (i.i.d.) Rayleigh flat-fading channels. Numerical and simulation results are presented that further confirm the accuracy of the analytical results     

Development of Stress-Induced Martensitic Transformation in TiNi Shape Memory Alloy

TiNi shape memory alloy (SMA) was subjected to tension at strain-controlled test on quasistatic testing machine. The nucleation, development, and saturation of the stress-induced martensitic transformation were investigated, taking into account the obtained dependency of mechanical parameters and the specimen temperature changes measured by an infrared camera (IR). Three kinds of data obtained by the IR system were analyzed: the temperature distribution on the SMA sample surface, the temperature changes derived as average from the chosen sample area, and the temperature profiles obtained along the sample length. The temperature distribution shows nucleation of the transformation process and a creation of the transformation bands. The average temperature reflects the effects of thermomechanical coupling, accompanying exothermic martensitic forward and endothermic reverse transformation. The temperature profiles revealed the temperature difference between the band and the rest of the sample. The experimental results were supported with finite element method numerical analysis (FEM). The FEM software components for structural and heat transfer problems, coupled in partitioned approach, were used for thermomechanical analysis.     

Cross-facility management of production and transportation planning problem

This paper studies an integrated production and transportation planning problem in a two-stage supply chain. This supply chain consists of a number of facilities, each capable of producing the final product, and a number of retailers. We assume that retailers’ demands are known deterministically and there are no production or transportation capacity constraints. We formulate the problem as a network flow problem with fixed charge costs. This is an NP  -hard problem. To solve the problem we propose a primal-dual based heuristic that generates upper and lower bounds and runs in O(FRT²)$O({\mathit{FRT}}^2)$. The quality of the upper and lower bounds is tested on a large set of randomly generated problems. The maximum error reported for these problems is 4.36% and the maximum running time is 7.65 cpu seconds.     

Bioprocess for Hyperactive Thermotolerant Aspergillus fumigatus Phytase and its Application in Dephytinization of Wheat Flour

Catalysis Letters - In the present study, statistically optimized production of thermotolerant Aspergillus fumigatus phytase was carried out in batch fermentation (1-L). An enhancement in phytase...