Frequency tunable metallo–dielectric structure for backscattering reduction

Electromagnetic scattering behaviour of a superstrate loaded metallo– dielectric structure based on Sierpinski carpet fractal geometry is reported. The results indicate that the frequency at which backscattering is minimum can be tuned by varying the thickness of the superstrate. A reduction in backscattered power of 44 dB is obtained simultaneously for both TE and TM polarisations of the incident field.

Backscattering Reduction of Corner Reflectors using SCS Technique

Reduction of radar cross -section of dihedral corner reflectors using simulated corrugated surface (.SCS) is reported. This technique is found lo be more effective in the reduction of RCS or corner reflectors for normal incidence . A typical reduction of 40-50 dB is achieved using this method

Backscattering Reduction of Corner Reflectors using SCS Technique

Reduction of radar cross -section of dihedral corner reflectors using simulated corrugated surface (SCS) is reported. The technique is found to be more effective in the reduction of RCS or corner reflectors for normal incidence . A typical reduction of 40-50 dB is achieved using this method.

Ni(II) and Ru(II) Schiff base complexes as catalysts for the reduction of benzene

Two new complexes, [MII(L)(Cl)(H2O)2]·H2O (where M=Ni or Ru and L = heterocyclic Schiff base, 3- hydroxyquinoxaline-2-carboxalidene-4-aminoantipyrine), have been synthesized and characterized by elemental analysis, FT-IR, UV–vis diffuse reflectance spectroscopy, FAB-MASS, TG–DTA, AAS, cyclic voltammetry, conductance and magnetic susceptibility measurements. The complexes have a distorted octahedral structure andwere found to be effective catalysts for the hydrogenation of benzene. The influence of several reaction parameters such as reaction time, temperature, hydrogen pressure, concentration of the catalyst and concentration of benzenewas tested. A turnover frequency of 5372 h−1 has been found in the case of ruthenium complex for the reduction of benzene at 80 ◦C with 3.64×10−6 mol catalyst, 0.34 mol benzene and at a hydrogen pressure of 50 bar. In the case of the nickel complex, a turnover frequency of 1718 h−1 has been found for the same reaction with 3.95×10−6 mol catalyst under similar experimental conditions. The nickel complex shows more selectivity for the formation of cyclohexene while the ruthenium complex is more selective for the formation of cyclohexane

Studies on Soft Bycatch Reduction Devices for Selective Trawling

Trawling, though an efficient method of fishing, is known to be one of the most non-selective methods of fish capture. The bulk of the wild caught penaeid shrimps landed in India are caught by trawling.In addition to shrimps, the trawler fleet also catches considerable amount of non-shrimp resources. The term bycatch means that portion of the catch other than target species caught while fishing, which are either retained or discarded. Bycatch discards is a serious problem leading to the depletion of the resources and negative impacts on biodiversity. In order to minimize this problem, trawling has to be made more selective by incorporating Bycatch Reduction Devices (BRDs). There are several advantages in using BRDs in shrimp trawling. BRDs reduce the negative impacts of shrimp trawling on marine community. Fishers could benefit economically from higher catch value due to improved catch quality, shorter sorting time, lower fuel costs, and longer tow duration. Adoption of BRDs by fishers would forestall criticism by conservation groups against trawling.

Investigations on Hard Bycatch Reduction Devices for Selective Trawling

In the context of Indian fisheries there is a paucity of information on bycatch, in general, and bycatch reduction technologies, in particular. In this study, a detailed investigation on trawl bycatch and bycatch reduction measures is attempted with a view to evolve optimized BRDs for improving selectivity of commercial shrimp trawls. The objectives of the study included design and development of hard bycatch reduction devices (BRDs), comparative evaluation of hard bycatch reduction devices, for selective trawling, bycatch characterisation of the trawl landings, off Central Kerala; and investigations on status of the existing trawling systems operated off Central Kerala.

Electrochemical Reduction and Voltammetric Determination of Metronidazole Benzoate at Modified Carbon Paste Electrode

A metalloporphyrin incorporated carbon paste sensor has been developed for the determination of metronidazole benzoate (MTZB). Zn(II) complex of 5,10,15,20-tetrakis (3-methoxy-4-hydroxy phenyl) porphyrin (TMHPP) was used as the active material. The MTZB gave a well-defined reduction peak at - 0.713V in 0.1 mol l -1 phosphate buffer solution of pH around 7. Compared with bare carbon paste electrode (CPE), the TMHPP Zn(II) modified electrode significantly enhanced the reduction peak current of MTZB as well as lowered its reduction potential. Under optimum conditions the reduction peak current was proportional to MTZB concentration over the range 1×10-3 mol1-1 to 1×10-5mol1-1. The detection limit was found to be 4.36×10-6mol1-1 . This sensor has been successfully applied for the determination of MTZB in pharmaceutical formulations and urine samples.

Catalytic activity of lanthanum oxide for the reduction of cyclohexanone

Lanthanum oxide, La2O3 has been found to be an effective catalyst for the liquid phase reduction of cyclohexanone. The catalytic activities of La2O3 activated at 300, 500 and 800·C and its mixed oxides with alumina for the reduction of cyclohexanone with 2-propanol have been determined and the data parallel that of the electron donating properties of the catalysts. The electron donating properties of the catalysts have been determined from the adsorption of electron acceptors of different electron affinities on the surface of these oxides.

Invertase immobilised on montmorillonite: reusability enhancement and reduction in leaching

Invertase was immobilised on microporous montmorillonite K-10 via adsorption and covalent binding. The immobilised enzymes were tested for sucrose hydrolysis activity in a batch reactor. Km for immobilised systems was greater than free enzyme. The immobilised forms could be reused for 15 continuous cycles without any loss in activity. After 25 cycles, 85% initial activity was retained. A study on leaching of enzymes showed that 100% enzyme was retained even after 15 cycles of reuse. Leaching increased with reaction temperature. Covalent binding resisted leaching even at temperatures of 70 °C.

Applications of Fractal Based Structures in Radar Cross Section Reduction

This thesis presents the Radar Cross Section measurements of different geometric structures such as flat plate,cylinder, corner reflector and circular cone loaded with fractal based metallo dielectric structures.Use of different fractal geometris,metallizations of different shapes as well as the frequency tanability is investigated for TE and TM polarization of the incident electromagnetic field.Application of fractal based metallo-dielectric structures results in RCS reduction over a wide range of frequency bands.RCS enhancement of dihedral corner is observed at certain acute and obtuse corner angles.The experimental results are validated using electromagnetic simulation softwares.

Bioremediation of petroleum sludge through Phytoremediation.Land farming and Microbial enhanced oil separation

The objective of this research is to study the feasibility of bioremediating the oily sludge from a refinery site. Three different methods of waste treatment were tried i.e. phytoremediation, land farming and microbial enhanced oil separation in laboratory scale treatment systems. A multiprocess approach by combination of phytoremediation, biostimulation and microbial enhanced oil separation is also presented. The methods of analysis, experimental procedure, and results are incorporated into five chapters of this thesis entitled "Bioremediation of petroleum sludge through phytoremediation, land farming and microbial enhanced oil separation.

Application of chitosan and PASS for the removal of turbidity and colour from water

The most common and conventional method for removing turbidity from water is by coagulating with alum or iron salts, and settling the precipitate in suitably designed clarifiers followed by filtration. But the sludge produced is bulky, difficult to dewater and accumulates in the dumping grounds causing environmental problems. Synthetic polymers such as polyacrylamide and polyethyleneoxide have been investigated for their ability to remove turbidity. They overcome many of the disadvantages of conventional methods, but are cost—effective only when rapid flocculation and reduction in sludge volume are demanded. Considering the aforementioned situation, it was felt that more easily available and eco-friendly materials must be developed for removing turbidity from water. The results of our studies in this direction are presented in this thesis. The thesis comprises of nine chapters, with a common bibliography at the end. Chapter 1 gives an introduction to the nature of turbidity and colour usually present in water. Chapter 2 discusses the nature and availability of the principal material used in these studies, namely chitosan. Chapters 3 to 8, which deal with the actual experimental work, are further subdivided into (a) introduction, (b) materials and methods, (c) results and discussion and (d) conclusions. Chapter 9 summarises the entire work so as to put the results and conclusions into proper perspective.

Preparation of useful raw materials from Refinery sludge and its utilisation in rubber processing

Petroleum, a mixture of organic compounds, comes from underground rock formations ranging in age from ten to several hundred million years. The process by which it is formed and developed is not yet completely known. Studies indicate that petroleum is formed mainly from microscopic-sized marine animals and plants. When these organisms died in water of low oxygen content, they did not decompose. Thus their remains sank to the bottom to be buried under accumulations of sediment. Their conversion to petroleum remains a subject of research even today.

Reduction of radar cross section of targets using periodic strip grating technique

The- classic: experiment of Heinrich Hertz verified the theoretical predict him of Maxwell that kxnfli radio and light waves are physical phenomena governed by the same physical laws. This has started a.rnnJ era of interest in interaction of electromagnetic energy with matter. The scattering of electromagnetic waves from a target is cleverly utilized im1 RADAR. This electronic system used tx> detect and locate objects under unfavourable conditions or obscuration that would render the unaided eye useless. It also provides a means for measuring precisely the range, or distance of an object and the speed of a moving object. when an obstacle is illuminated by electromagnetic waves, energy is dispersed in all directions. The dispersed energy depends on the size, shape and composition of the obstacle and frequency and nature of the incident wave. This distribution of energy’ is known as ‘scattering’ and the obstacle as ‘scatterer’ or 'target'.