Optimal system selection in fuzzy environment

The problem of the selection of an optimal decision from a set of finite number of alternatives is considered, when there is a single or multiple decision-makers present. In the single decision-maker case, the optimal decision is the one that satisfies pre-specified multiple objectives. A method is given to select the optimal decision based on membership grade. However, in the multiple decision-makers case, the problem of arriving at group decision, when each decision-maker gives his preference, has been discussed. Nevertheless, in both the situations decision-makers have the freedom to modulate their decision functions by some measure of their satisfaction or preference. Results from the theory of fuzzy sets have been applied to develop the solution methods for different situations. Illustrations are included to show the usage of the methodology.     

An approach to demarcate ground water potential zones through remote sensing and a geographical information system

In order to demarcate the ground water potential zones of Marudaiyar basin different thematic maps such as, lithology, landforms, lineaments and surface water bodies at a 1: 50000 scale were prepared, using remotely-sensed data as well as drainage density and slope classes from Survey of India topographical sheets. In addition, a soil map at 1:50000 scale covering the study area was generated from a 1:250000 scale soil map prepared by the Soil Survey and Landuse Organization by regrouping the soil types based on their hydrological characteristics. All the thematic layers were integrated and analysed using a model developed with logical conditions in the geographical information system (GIS). The ground water potential zones map generated through this model was verified with the yield data to ascertain the validity of the model developed. The verification showed that the ground water potential zones demarcated through the model are in agreement with the bore well yield data collected in the field. Since the present approach was built with logical conditions and reasoning, this approach can be successfully used elsewhere with appropriate modifications. Thus, the above study has clearly demonstrated the capabilities of remote sensing technique and GIS in demarcation of the different ground water potential zones, particularly in such a diverse geological set up.     

Efficient computerized Petri net approach for the enumeration of the sets of path identifiers for reliability analysis of broadcasting networks

An efficient Petri net approach for enumerating the sets of path identifiers for the reliability analysis of broadcasting networks is presented. The sets of path identifiers are enumerated with the help of a place-to-transilion incident matrix of the Petri net model of Ihe given network. The reachability, marking and firing concepts of Petri nets are used to give a Petri net interpretation to certain properties of the network. The proposed method is applicable to ST-connectivity, SKT-connectivity and SAT-connectivity problems. The sets of path identifiers are generated in ascending order of cardinality which is one of the basic requirements for efficiency in most of the techniques available for obtaining the symbolic and numerical system reliability expressions. The developed algorithm has been programmed in FOR-TRAN-77 and tested on various types of data. The proposed method directly obtains the sels of path identifiers for SKT- and SAT-connectivity problems without the necessity of generating the ST-minimal path sets. In comparison to the previously published approach, the algorithm is conceptually simpler and requires less computer time and memory space. Examples have been provided to demonstrate the effectiveness of the method. A comparison of CPU time and memory requirement of the present method with an existing method has also been given.     

ELECTROSTATIC DEPOSITION OF LARGE GRAINED POLYCRYSTALLINE SILICON FILMS FOR SOLAR CELL APPLICATIONS

ABSTRACT

Large grained (> 50 μm < 100 μm) poly crystalline silicon films have been formed using a patented electrostatic deposition method which utilizes charged panicle motion in an electric field. After deposition, the films are heat treated at varying times and temperatures in a programmable furnace maintained under a purified argon atmosphere Solar cells were fabricated using these large grained polycrystalline silicon films by sputtering pure gold as back contacts and using high quality silver paint as front contacts. The cells have shown efficiencies of 1.8% indicating that great potential exists for significant improvement.     

CORRELATION FOR DROP SIZE IN LIQUID/LIQUID SPRAY COLUMNS

A single equation is presented which predicts the drop size in liquid/liquid spray columns up to the critical nozzle velocity:

with an average deviation of 9.7%. This can be reduced to 7.3% if two regions are considered separated by a critical nozzle diameter:     

Structural and spectral properties of 4-phenoxyphthalonitrile dye sensitizer for solar cell applications

The geometries, electronic structures, polarizabilities and hyperpolarizabilities of organic dye sensitizer 4-phenoxyphthalonitrile was studied based on ab initio HF and density functional theory (DFT) using the hybrid functional B3LYP. Ultraviolet?Cvisible (UV?CVis) spectrum was investigated by time dependent DFT (TD-DFT). Features of the electronic absorption spectrum in the visible and near-UV regions were assigned based on TD-DFT calculations. The absorption bands were assigned to $\pi \to \pi^*$ transitions. Calculated results suggest that the three excited states with the lowest excited energies in 4-phenoxyphthalonitrile was due to photo-induced electron transfer processes. The interfacial electron transfer between semiconductor TiO₂ electrode and dye sensitizer 4-phenoxyphthalonitrile was due to an electron injection process from excited dye to the semiconductor??s conduction band. The role of phenoxy group in 4-phenoxyphthalonitrile in geometries, electronic structures and spectral properties were analysed.     

High temperature C/C–SiC composite by liquid silicon infiltration: a literature review

The ceramic matrix carbon fibre (CMC) reinforced composite has received great attention for use in aerospace engineering. In aerospace, the atmosphere is highly oxidative and experiences very high temperature. In addition to this, the materials require high thermal stability and high abrasion resistance in that atmosphere. The C/C–SiC composite meets with these requirements. In this paper, the C/C–SiC composite by liquid silicon infiltration is reviewed thoroughly.     

Effectiveness of macrogol and talcum base formulations of a new insect repellent N, N-diethyl phenyl acetamide

The effectiveness of macrogol and talcum base formulations of a new multi-insect repellent N, N-diethyl phenyl acetamide (DEPA) was studied against Aedes aegypti mosquitoes in the laboratory. The efficacy was compared with widely used repellent in India, viz. Dimethylphthalate. Twenty-five per cent DEPA incorporated macrogol ointment and talcum base formulation offered more than 8 h and 6 h protection, as compared to DMP for 3 h and 1 h 30 min, respectively. The ointment was found to be stable as more than 99% DEPA was recovered by gas liquid chromatography after 6 months of storage at room temperature. The repellent formulations have not shown any gross adverse effect to the skin of albino rabbits.

Résumé

L'efficacité d'un nouvel agent repousseur d'insectes (le N, N-diethyl phenyl acetamide) dans des formulations à base de macrogol et du talc
L'efficacité des bases formulées à partir de macrogol et de talc pour un nouvel insecticide, N, N-diethyl pnenyl acetamide (DEPA) a étéétudiée contre les moustiques Aedes aegypti en laboratoire. Cette efficacité a été comparée avec un insecticide couramment utilisé en Inde, le Dimethyl phthalate. 25% de DEPA incorporéà une base formulée à partir de pommade de macrogol et de talc a permis une protection respectivement de plus 5 h et de plus de8 h comparativement au DMP pour lequel la protection était respectivement de 3 h et 1 h 30. La pommade s'est avérée stable car plus de 99% de DEPA ont été identifiés par GLC après 6 mois de stockage à température ambiante. Les formulations d'insecticides n'ont révélé aucun effet adverse sur la peau des lapins albinos.