Investigation Into Laser Shock Processing

Laser shock processing is a good candidate for surface industry due to its rapid processing, localized ablation, and precision of operation. In the current study, laser shock processing of steel was considered. The numerical solutions for temperature rise and recoil pressure development across the interface of the ablating front and solid are presented. The propagation of elastic-plastic waves in the solid due to recoil pressure loading at the surface is analyzed and numerical solution for the wave propagation was obtained. An experiment was conducted to ablate the steel surfaces for shock processing. Scanning electron microscopy was carried out to examine the ablated surfaces shock processing while transmission electron microscopy was conducted to obtain dislocation densities after the shock processing. It was found that surface hardness of the workpiece increased in the order of 1.8 times of the base material hardness, and the dislocation was the main source of the shock hardening in the region affected by laser shock processing

Laser sensor for detection of SF6 leaks in high powerinsulated switchgear systems

A novel photoacoustic spectrometer (PA) has been developed for in-situ detection of SF6 leaks in low concentrations. The developed system is equipped with a sound alarm system and has been tested in the laboratory for very minute SF6 leaks. This newly developed SF6 detection device utilizes a high quality factor resonant photoacoustic cell and continuous wave (CW) line tunable CO2 laser at 10.55 m wavelength. Whenever SF6 is detected an acoustic signal is generated and no signal appears from ambient air if there is no leakage of SF6. An electret microphone is used for the detection of these acoustic signals. The system is capable of detecting leaks of the order of 3.5 ppbv (parts per billion by volume) concentration. This device has been proved to have significant applications to industrial organizations that have electric power gas insulated systems (GIS). It could be also applied for other applications such as monitoring of environmental pollutants with minimal adjustment

Laser sensor for detection of SF6 leaks in high powerinsulated switchgear systems

A novel photoacoustic spectrometer (PA) has been developed for in-situ detection of SF6 leaks in low concentrations. The developed system is equipped with a sound alarm system and has been tested in the laboratory for very minute SF6 leaks. This newly developed SF6 detection device utilizes a high quality factor resonant photoacoustic cell and continuous wave (CW) line tunable CO2 laser at 10.55 m wavelength. Whenever SF6 is detected an acoustic signal is generated and no signal appears from ambient air if there is no leakage of SF6. An electret microphone is used for the detection of these acoustic signals. The system is capable of detecting leaks of the order of 3.5 ppbv (parts per billion by volume) concentration. This device has been proved to have significant applications to industrial organizations that have electric power gas insulated systems (GIS). It could be also applied for other applications such as monitoring of environmental pollutants with minimal adjustment

355-nm photodissociation of CH4 and production ofhydrogen

Summary form only given. Methane gas is available as a cheap source for heating purposes as well as for converting into higher hydrocarbons using steam reforming and other processes to produce syn-gas. Research has been directed towards the development of alternative techniques to convert methane into more valuable hydrocarbons such as ethylene and propylene as well as for generation of hydrogen. Hydrogen is forecast to become the major source of energy in future. Molecular hydrogen is a clean burning fuel and can be stored as liquid or gas. The ethylene and propylene are raw materials for producing polyethylene and polypropylene and the demand for these polymers is increasing at an immense growth rate. In spite of many research programs, there is no direct conversion process so far reported which is capable of large scale production of these products from methane which could be described as high yield and highly selective process. At present, there are three different photochemical-process based techniques, which have been used for methane conversion with some degree of success. These include UV light, plasma and microwave irradiation in the presence of different catalyst. To the best of our knowledge, there is no report on photodissociation of methane at 355 nm. The aim of the present study is to develop a technique for direct conversion of methane into hydrogen and higher hydrocarbon and to analyze the regenerated products as a result of laser-photodissociatio

355-nm photodissociation of CH4 and production ofhydrogen

Summary form only given. Methane gas is available as a cheap source for heating purposes as well as for converting into higher hydrocarbons using steam reforming and other processes to produce syn-gas. Research has been directed towards the development of alternative techniques to convert methane into more valuable hydrocarbons such as ethylene and propylene as well as for generation of hydrogen. Hydrogen is forecast to become the major source of energy in future. Molecular hydrogen is a clean burning fuel and can be stored as liquid or gas. The ethylene and propylene are raw materials for producing polyethylene and polypropylene and the demand for these polymers is increasing at an immense growth rate. In spite of many research programs, there is no direct conversion process so far reported which is capable of large scale production of these products from methane which could be described as high yield and highly selective process. At present, there are three different photochemical-process based techniques, which have been used for methane conversion with some degree of success. These include UV light, plasma and microwave irradiation in the presence of different catalyst. To the best of our knowledge, there is no report on photodissociation of methane at 355 nm. The aim of the present study is to develop a technique for direct conversion of methane into hydrogen and higher hydrocarbon and to analyze the regenerated products as a result of laser-photodissociatio

Co-sensitization effect of N719 dye with Cu doped CdS colloidal nanoparticles for dye sensitized solar cells

Dye-sensitized solar cell’s (DSSC) performances are enhanced by engineering the materials at the interface of various device components owing to easy and inexpensive fabrication steps. Ru (II) polypyridyl-based synthetic dyes are the most widely used photosensitizers for DSSCs due to their superior molar extinction coefficient and facile interaction with metal oxide electrodes. However, these dyes are mostly expensive, and as a result, natural dyes and metal-free organic dyes have become an alternative way for sensitization to reduce the significant drawbacks of synthetic dyes. In this study, minimizing the usage of the N719 dye can be performed through an alternative method for better light-harvesting through supreme optical interfacial interaction with colloidal Cu-doped CdS as a co-sensitizer in a facile approach. This co-sensitization signifies the colloidal CdS (donor), which can corroborate the energy transfer mechanism with the N719 dye (acceptor). The introduction of Cu causes extreme tuning of broad absorption to near-infrared for CdS, enhancing the solar light harvesting entrapment followed by extensive optical interaction with N719 dye. This accelerates the activity of the sensitizers for light absorption enhancement and expects a better performance of DSSC compared to traditional sensitization. A massive improvement in photocurrent density (∼42 %) was observed without sacrificing other photovoltaic parameters, as observed for TiO2-based photoanodes. The sensitizer’s interfacial optical energy transfer process, unless excited electron recombination, may indirectly be used as an excitation source of the acceptor and minimizes the recombination energy loss

Removal of hazardous Rhodamine dye from water by adsorption onto exhausted coffee ground

Exhausted coffee ground powder (CGP) was proved to be an efficient adsorbent for the removal of Rhodamine dyes (i.e. Rhodamine B and Rhodamine 6G) from aqueous solutions by batch adsorption experiments. The morphology, chemical structure as well as the surface property of the as-prepared CGP adsorbent were investigated by using SEM, FT-IR and contact angle meter analytical techniques. The adsorption kinetics and isotherm behaviors of Rhodamine molecules onto CGP were studied and compared using pseudo-1st, pseudo-2nd and Langmuir/Freundlich models, respectively. The maximum adsorption capacities of Rh B and Rh 6G were calculated at 5.255 and 17.369 μmol g−1 by Langmuir model fitting. The effects of temperature, ionic strength, solution volume and the co-existing anions on the sorption behavior were also investigated. Furthermore, the adsorption mechanism responsible for the efficient removal of dyes is discussed in terms of adsorption process caused by electrostatic and intermolecular forces

A REPORT ON SURRA IN GUJRANWALA

A project was conducted to study the prevalence, clinical signs, treatment response and necropsy findings in equines suffering from Surra in Gujranwala. For this purpose, 34334 animals brought to the Brooke Hospital for Animals were tested over a five year period from April, 1997 to December, 2002. The data showed that out of 34334 animals tested, 1151 were positive for the disease, showing a prevalence of 3.35 per cent. The clinical and necropsy findings were characteristics for the disease. Out of 1151 infected animals, 1129 (98.09 per cent) responded to isometamedium chloride and recovered while only 22 (1.91 per cent) died