Comments on `Enumeration of all minimal cutsets for a node pair ina graph'

The commenters point out that the algorithm of S.A. Kumar and S.H. Lee for the enumeration of all minimal s-t cutsets is defective (see ibid., vol.R-26, p.51-5, April 1979). It is illustrated through an example that their algorithm misses several minimal cutsets. The commenters cite two reasons for this: the adjacency problem and the back-vertex problem     

Tensile creep study of copper with alumina dispersions prepared by high rate physical vapour deposition

Mott has suggested that the ideal creep-resistant material will be one with a fine grain size in which the grain boundaries are filled with some substance, say a refractory oxide, to inhibit the motion of grain boundaries. Such a system, alumina-dispersed copper, was prepared by high rate physical vapour deposition. The process parameters and their effect on structure and texture have been studied. The room temperature mechanical properties have also been reported. This paper deals with a high temperature mechanical property, i.e. tensile creep. Tests were made on a constant-stress vacuum creep rig with a Ferrometic feedthrough to ensure a zero leakage rotary seal. A vacuum of 1.33 X 10^?3 Pa was maintained. The test temperatures were 500°C (0.57T_m) and 700°C (0.72T_m). The stresses applied were 2.07, 3.45, 4.14 and 6.89 X 10⁷ Nm^?2. Tests were made on as-deposited films and on cold-rolled condensates.Minimum creep rate curves showed the effect of the alumina content in raising the creep resistance of copper. Cold rolling also reduced the minimum creep rate markedly. Varying the temperature and stress affected the shape of these curves. Stress-rupture plots were used to summarize the data.Grain refinement together with a fine stable dispersion seem to give improved creep strength. The critical barrier of the Orowan stress was noted. The stress exponent for a low alumina deposit (0.21 vol.%) was about 8, and the apparent activation energy for creep was about 202 kJ mol^?1 (0.13 vol.%). There was an inverse relationship between the rupture life and the minimum creep rate, their product being constant (about 0.2).     

Electronic absorption spectrum of Cu2 ions doped in lithium ammonium sulphate crystal

Single crystals of Lithium Ammonium Sulphate doped with Cu²⁺ ions were grown by slow evaporation technique. Electronic absorption spectra have been recorded at room and liquid nitrogen temperatures on Cary-2390 spectrophotometer. The spectrum is characteristic of a Cu²⁺ ion in octahedral symmetry. From the magnitude and and relative position of the bands a successful interpretation of all the observed bands has been made. The crystal field and tetragonal field parameters are derived. The observed and calculated energies are in good agreement.     

A computer program for automatic generation of stiffness and mass matrices in finite-element analysis

A computer program to generate automatically the stiffness and mass matrices in finite element analysis is introduced. By using programs like this, researchers only need to derive the expressions for the energies (strain or kinetic) and the expressions for the displacements or stresses and their derivatives in terms of nodal variables. Tedious calculations to obtain the matrices are avoided. Such programs would facilitate checking of existing matrices and would encourage researchers to try out new finite element models.     

Generation of vertex connected subgraphs for multi-input multi-output reliability networks

In this paper, the problem of evaluation of reliability (probability of success) of a network consisting of several inputs and outputs is studied. Edges are assumed to be perfect and vertices are assigned the probabilities of success. A new concept called “vertex connected subgraph” is introduced for this purpose. This concept is useful even for dense graphs because they are of the order of 2^(v-k-1) which is independent of e, where ν(e) is the number of vertices (edges) and k is the number of outputs of a graph.     

Biopreservative technologies of food: an alternative to chemical preservation and recent developments

Food Science and Biotechnology - Despite centuries of developing strategies to prevent food-associated illnesses, food safety remains a significant concern, even with multiple technological...     

Combined quality loss (CQL) concept in WPCA-based Taguchi philosophy for optimization of multiple surface quality characteristics of UNS C34000 brass in cylindrical grinding

The present study highlights a multi-objective optimization problem by applying Weighted Principal Component Analysis (WPCA) coupled with Taguchi method through a case study in cylindrical grinding of UNS C34000 Medium Leaded Brass. The study aimed at evaluating the best process environment which could simultaneously satisfy multiple requirements of surface quality. In view of the fact that traditional Taguchi method fails to solve a multi-objective optimization problem, to overcome this limitation, WPCA has been coupled with Taguchi method. Furthermore, to follow the basic assumption of Taguchi method, i.e., quality attributes should be uncorrelated or independent; which is not always satisfied in practical situation; the study applied WPCA to eliminate response correlation and to evaluate independent or uncorrelated quality indices called principal components which were aggregated by WPCA to compute overall quality index denoted as Multi-Response Performance Index. A combined quality loss was then estimated which was optimized (minimized) finally. The study combined WPCA and Taguchi method for predicting optimal setting. Optimal result was verified through confirmatory test. This indicates application feasibility of the aforesaid methodology proposed for multi-response optimization and off-line control of correlated multiple surface quality characteristics in cylindrical grinding.     

Physicochemical characterization of muscle proteins from different regions of mackerel (Rastrelliger kanagurta)

Physicochemical characteristics of proteins extracted from muscles excised from four distinct regions of mackerel were examined. Three regions were identified based on their fin position; namely anterior muscle, median muscle, posterior muscle and red muscles from beneath the lateral line. The biochemical characteristics like reactive sulphydryl groups, surface hydrophobicity, Ca²⁺ ATPase activity, turbidity, proximate composition and the functional characteristics such as viscosity, emulsion activity index (EAI) and emulsion stability (ES) were studied in the samples, from different regions. Sarcoplasmic protein (SPP) solubility was found to be higher in red muscles compared to that of white muscles, whereas myofibrillar protein (MFP) solubility was higher in white muscles particularly in the posterior portion. The MFP from posterior white muscles showed better viscosity, surface hydrophobicity and Ca²⁺ ATPase activity, which in turn contributed to the higher EAI and ES of this muscle portion. Variations in composition, electrophoretic pattern of proteins and selected functional properties (EAI) were noticed between red and white muscles, which may be of significance from the utilization point of the fish.