The impact of market focus on operations practices

A key element of successful organisations is the alignment of their strategy and tactics. This study explores the relationship between a firm's competitive strategy and its operations practices in the context of a developing economy. Two competitive strategies are examined; a niche market strategy characterised by targeting specific market segments, and a broad market strategy characterised by serving a wide range of market segments. Three sets of operations practices consistent with the adoption of lean manufacturing, Total Quality Management, and relationship development in a supply chain context, are explored. Using survey data from senior managers in Thailand, results show that for firms adopting a niche market focus, competitive strategy directly influences process management and relationship development, which in turn affect workforce commitment. Only workforce commitment has a direct effect on operational performance. In contrast, for firms adopting a broad market focus, competitive strategy directly influences workforce commitment, which in turn affects process management and relationship development practices. It is the latter practices that directly influence operational performance.     

Genetic algorithm for minimizing assembly variation in selective assembly

Selective assembly is a method of obtaining high-precision assemblies from relatively low-precision components. In selective assembly, the mating parts are manufactured with wide tolerances. The mating part population is partitioned to form selective groups, and corresponding selective groups are then assembled interchangeably. If the mating parts are manufactured in different processes and in different machines, their standard deviations will be different. It is impossible that the number of parts in the selective group will be the same. A large number of surplus parts are expected according to the difference in the standard deviations of the mating parts. A method is proposed to find the selective groups to minimize the assembly variation and surplus parts when the parts are assembled linearly. A genetic algorithm is used to find the best combination of the selective groups to minimize the assembly variation. Selective assembly is successfully applied using a genetic algorithm to achieve high-precision assemblies without sacrificing the benefit of wider tolerance in manufacturing.     

Batch biodegradation of PAHs in mixture by Mycobacterium frederiksbergense: analysis of main and interaction effects

Biodegradation is an effective technique to remediate soil and water contaminated with polycyclic aromatic hydrocarbons (PAHs). In the present experimental study, Mycobacterium frederiksbergense, a fast growing mycobacterium, was used to degrade anthracene, naphthalene and pyrene in mixture each at initial concentrations varying between 1 and 50 mg l⁻¹. Experiments were conducted according to the 2³ factorial design at the low (1 mg l⁻¹) and high (50 mg l⁻¹) levels of the PAHs in combination, to identify the main and interaction effects of the compounds on their biodegradation. The results showed that the PAH removals varied 54–81% when each PAHs were at low concentrations in the mixture and 67–89% at their higher concentration combinations. Statistical analysis of the results in the form of ANOVA and Student t test indicated significant role played by the main effects of pyrene on its degradation. Similarly on anthracene degradation, interaction effect with pyrene was found to be highly significant with P value less than 0.1.     

MPOE Based Prefiltering and MRT Beamforming with Matched Filter Receiver for DS-CDMA Systems

In order to reduce the complexity of the mobile receiver, we develop two prefilter models using a linear FIR prefilter for minimizing the probability of error in multi-user transmission scenario. We consider downlink transmission. In the first system model, we have a single common prefilter for all users at the base station transmitter and in the second system model, we consider an individual prefilter for each and every user. We assume complete knowledge of the channel at the base station. In order to fully utilize the knowledge available at the transmitter, the filter weights are computed, conditioned on the transmitted bit vector sequence. This also makes the computation of the prefilter coefficients linear in the number of users as opposed to the exponential complexity otherwise. Coefficients of FIR prefilter are computed by minimizing the conditional probability of error and the mean square error. To further improve the performance of the proposed models, we consider Maximum Ratio Transmission (MRT) beamforming at the base station for both the models. Simulation results illustrate the performance of the proposed system models.

Elliptic key cryptography with Beta Gamma functions for secure routing in wireless sensor networks

Wireless Networks - The security of data communicated through wireless networks is a challenging issue due to the presence of malicious and unauthenticated users whose intention is either to...     

Optimization of friction welding by taguchi and ANOVA method on commercial aluminium tube to Al 2025 tube plate with backing block using an external tool

The aim of the present work is to optimize the Friction welding of tube to tube plate using an external tool (FWTPET) with clearance fit of commercial aluminum tube to Al 2025 tube plate using an external tool. Conventional frictional welding is suitable to weld only symmetrical joints either tube to tube or rod to rod but in this research with the help of external tool, the welding has been done by unsymmetrical shape of tube to tube plate also. In this investigation, the various welding parameters such as tool rotating speed (rpm), projection of tube (mm) and depth of cut (mm) are determined according to the Taguchi L₉ orthogonal array. The two conditions were considered in this process to examine this experiment; where condition 1 is flat plate with plain tube Without holes [WOH] on the circumference of the surface and condition 2 is flat plate with plane tube has holes on its circumference of the surface With holes [WH]. Taguchi L₉ orthogonal array was utilized to find the most significant control factors which will yield better joint strength. Besides, the most influential process parameter has been determined using statistical Analysis of variance (ANOVA). Finally, the comparison of each result has been done for conditions by means percentage of contribution and regression analysis. The general regression equation is formulated and better strength is obtained and it is validated by means of confirmation test. It was observed that value of optimal welded joint strength for both tube without holes and tube with holes are to be 319.485 MPa and 264.825 MPa, respectively.

     

The Marcus Gunn phenomenon: discussion and report of three cases

The Marcus Gunn phenomenon and Marin Amat syndrome (inverted Marcus Gunn phenomenon) are discussed, along with their associated features. Two patients exhibiting the Marcus Gunn phenomenon only and one patient exhibiting both the Marcus Gunn phenomenon and Marin Amat syndrome are described.     

Technical note

The primary aim of this paper is to develop models for replacement strategies using genetic algorithms. Two models have been developed, one for implementing the strategy using a discrete function to replace the items whose efficiency deteriorates with time and the other for implementing the strategy using a continuous function. The main aim is to show how genetic algorithms can be applied to these models. For the quick convergence to the optimal solution for the replacement problems, Queen Bee strategy has been adopted.