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.

Effect of metal based additive on performance emission and combustion characteristics of diesel engine fuelled with biodiesel

This study investigates the use of ferric chloride (FeCl₃) as a fuel borne catalyst (FBC) for waste cooking palm oil based biodiesel. The metal based additive was added to biodiesel at a dosage of 20 μmol/L. Experiments were conducted to study the effect of ferric chloride added to biodiesel on performance, emission and combustion characteristics of a direct injection diesel engine operated at a constant speed of 1500 rpm at different operating conditions. The results revealed that the FBC added biodiesel resulted in a decreased brake specific fuel consumption (BSFC) of 8.6% while the brake thermal efficiency increased by 6.3%. FBC added biodiesel showed lower nitric oxide (NO) emission and slightly higher carbon dioxide (CO₂) emission as compared to diesel. Carbon monoxide (CO), total hydrocarbon (THC) and smoke emission of FBC added biodiesel decreased by 52.6%, 26.6% and 6.9% respectively compared to biodiesel without FBC at an optimum operating condition of 280 bar injection pressure and 25.5^o bTDC injection timing. Higher cylinder gas pressure, heat release rate and shorter ignition delay period were observed with FBC added biodiesel at these conditions.     

Development of gas diffusion electrodes for low relative humidity proton exchange membrane fuel cells

A series of polyaniline nanofibers (PANFs) were synthesized and incorporated into gas diffusion electrodes (GDE) of proton exchange membrane fuel cells (PEMFC) to improve their performances at low relative humidity (RH) conditions. Three different placements to incorporate the PANFs in the anodes include (1) placing a PANFs layer between catalyst layer (CL) and membrane, (2) coating the CL with PANFs and catalyst mixed slurry, and (3) placing a PANFs layer between the CL and gas diffusion layer (GDL). Fuel cell performance data indicates that the last method is superior to the others and is adopted as incorporation method thereafter. Extensive studies on single cell performances have been conducted to compare the membrane electrode assemblies with and without the incorporation of PANFs in both anode and cathode. Polarization curves show the incorporation of H₂SO₄-doped PANFs is highly effective in improving the hydrophilic characteristic of the electrodes and thus can promote the PEMFC performance at low RH conditions. For example, with a lowering of reactant RH from 100 to 70%, the electrode with H₂SO₄-doped PANFs layer exhibits an increase in power density from 0.57 to 0.7 W cm⁻². On the other hand, a traditional carbon-supported platinum electrode exhibits a decline of performance from 0.73 to 0.55 W cm⁻².     

Low cycle fatigue properties of modified 9Cr-1Mo ferritic martensitic steel weld joints in sodium environment

Mod.9Cr-1Mo ferritic-martensitic steel is the material chosen for the steam generator of the Prototype Fast Breeder Reactor being built at Kalpakkam, India. The use of sodium as a heat transfer medium for Liquid Metal Fast Breeder Reactors (LMFBRs) necessitates a comprehensive understanding of the effects of dynamic sodium on the Low Cycle Fatigue (LCF) behaviour of structural components. Moreover welds being the weak links in any structure, it is necessary to evaluate the LCF behaviour of joints in sodium environment, more so in Mod.9Cr-1Mo steel because of the well established Type — IV cracking in this material. With this aim in view, a programme has been initiated to evaluate the LCF properties of weld joints of this steel in dynamic sodium environment. A facility has been developed in-house for mechanical property evaluation in dynamic sodium. LCF tests conducted in flowing sodium environment at 823 and 873 K showed a similar trend in cyclic stress response in air and sodium environments exhibiting a continuous cyclic softening behaviour. The fatigue lives are significantly improved in sodium environment when compared to the data obtained under identical testing conditions in air environment. The lack of oxidation in sodium environment is considered to be responsible for the delayed crack initiation and consequent increase in fatigue life. Comparison with RCC-MR code shows that the design curve based on air tests is conservative.     

Rainwater Management for Smallholder Irrigation and it’s Impact on Crop Yields in Eastern India

A tank cum open dug well system suitable for plateau region of eastern India has been developed for providing reliable irrigation to croplands. The system comprises of a series of tanks with open dug wells in the recharge zone of the tank that reharvest back the seepage water. Thus, the rainwater remaining in the tank as well as partial seeped water is used for providing round the year full irrigation. This system was evaluated in field in Keonjhar district of Orissa of eastern India with six tanks and five wells in two drainage lines. The total command area of the system of six tanks and five wells in both drainage lines is 23 ha and the total irrigation potential is 44.5 ha. The total cost of the system is US $19,180 making the cost of irrigation resource creation as US $426 per ha which is much less than about $2,220 per ha for major and medium irrigation projects in the last decade of 20th century. The system increased the rice yields from 1.92 t ha^− 1 to a range of 2.25 to 3.8 t ha^− 1 depending upon the package of practices or the amount of inputs. The farmers went for crops in post-monsoon and summer season and the cropping intensity rose to 112% in the first year, 126% in the second year and 132% in the third year. The internal rate of return from the system was 13.4% at the present level of utilization, which is about 2.4% more than the prime-lending rate of Indian banks, and 3.4% more than the lending rate for agricultural purposes.     

Chemical degradation of melanin in enzyme based dehairing and fiber opening of buff calfskins

Global leather industry is undergoing a paradigm shift towards bioprocessing of hides and skins. Hence, the enzyme-based dehairing and fiber opening are becoming ecologically important. However, the enzymatic dehairing and fiber opening of buff calfskins results in non-removal of melanin leading to patches in the finished leather. In this study, an attempt has been made to remove the melanin from buff calfskins using various chemicals having reduction, oxidation or bleaching abilities. Preliminary trials have been carried out with various concentrations of chemicals in enzymatic dehairing and fiber opening processes. It was found that 1% dosage of sodium sulfite and sodium dithionite provides complete removal of melanin during enzymatic dehairing and fiber opening, respectively. The optimized chemicals and percentages were experimented at semi-technical scale. The removal of melanin was assessed visually and confirmed with scanning electron microscopy. UV–visible spectral analysis also substantiated the melanin removal by showing the disappearance of peak in the region of 300 nm using the optimized processes. The performance characteristics of the resulted leathers have been analyzed and are found to be satisfactory.     

Association between perfluorinated compounds and pathological conditions in southern sea otters

Concentrations of four perfluorinated contaminants, including perfluorooctanesulfonate (PFOS) and perfluorooctanoic acid (PFOA), were measured in liver tissue from 80 adult female sea otters collected from the California coast during 1992-2002. Concentrations of PFOS and PFOA were in the ranges of <1-884 and <5-147 ng/g, wet wt, respectively. Concentrations of PFOA in the livers of these sea otters were among the highest values reported for marine mammals to date. Liver tissue from 6 male sea otters also was analyzed and contained significantly higher concentrations of PFOS than did tissues from female otters. To examine the association between exposures and potential effects, concentrations of PFOS and PFOA were compared among the adult female otters that died from infectious diseases, noninfectious causes, and from apparent emaciation. Concentrations of both PFOA and PFOS were significantly higher in sea otters in the infectious disease category than in the noninfectious category. Concentrations of PFOS and PFOA were not significantly different between noninfectious and emaciated otters, suggesting that the poor nutritive (body) status of emaciated otters did not affectthe concentrations of perfluorochemicals in livers. Concentrations of PFOA increased significantly from 1992 to 2002, whereas PFOS concentrations increased from 1992to 1998 and then decreased after 2000. Significant association between infectious diseases and elevated concentrations of PFOS/PFOA in the livers of sea otters is a cause for concern and suggests the need for further studies.     

Screening and optimization of media constituents for decolourization of Mordant Blue-9 dye by Phanerochaete chrysosporium

Decolourization of Mordant Blue-9 (MB-9) by the white-rot fungi Phanerochaete chrysosporium MTCC 787 was investigated by screening and optimization of the media constituents used for growing the fungus. Both % decolourization and specific removal of MB-9 by the fungus were taken as the responses to screen and optimize the media constituents using statistically valid Plackett–Burman and response surface methodology (RSM) design of experiments, respectively. Amongst the media constituents screened, glucose, veratryl alcohol, KH₂PO₄ and CaCl₂ were selected as the most important (P value < 0.05) media constituents for MB-9 dye decolourization; the other media constituents, viz. MgSO₄, tween 20, NH₄Cl₂ and inoculum size were, however, found to be insignificant in the study. Central composite design followed by RSM used in optimizing the important media constituents for enhancing the decolourization of MB-9 dye revealed optimum combinations of glucose, 13.46 g l⁻¹; veratryl alcohol, 9.30 mM; KH₂PO₄, 24.52 g l⁻¹; CaCl₂, 2.18 g l⁻¹; MgSO₄, 9.89 g l⁻¹; NH₄Cl₂, 4.68 g l⁻¹; tween 20, 0.050% and inoculum size, 0.8 OD₆₅₀, which gave a maximum % dye decolourization of 100% and specific dye removal of 0.1571 mg U⁻¹.     

Enhancing stress corrosion cracking resistance in Al-Zn-Mg-Cu-Zr alloy through inhibiting recrystallization

The aim of the work was to inhibit recrystallization in Al-Zn-Mg-Cu-Zr alloy and to evaluate the stress corrosion cracking (SCC) behavior of the alloy in the peak aged condition. For this purpose, scandium addition was made to an Al-Zn-Mg-Cu-Zr alloy as the former inhibits recrystallization. The scandium-containing alloy was heat-treated to peak aged condition and compared with the base peak aged alloy which contained recrystallized grains. The SCC susceptibilities of the alloys were evaluated using slow strain rate testing (SSRT) and U-bend techniques. While, the base alloy having recrystallized grains showed drastic loss in ductility in the corrosive environment (3.5 wt.% NaCl solution), the scandium-containing alloy having un-recrystallized and fine grains showed no significant loss in ductility in the similar environment. The fracture surface analysis revealed typical intergranular cracking of recrystallized grains in the base alloy, whereas in the scandium-containing alloy predominant ductile failure was observed. Thus, the study clearly indicated that inhibiting recrystallization in Al-Zn-Mg-Cu-Zr alloy through scandium addition, the SCC resistance of the alloy can be substantially improved even in the peak aged condition.     

Biomedical Nanomagnetics: A Spin Through Possibilities in Imaging, Diagnostics, and Therapy

Biomedical nanomagnetics is a multidisciplinary area of research in science, engineering and medicine with broad applications in imaging, diagnostics and therapy. Recent developments offer exciting possibilities in personalized medicine provided a truly integrated approach, combining chemistry, materials science, physics, engineering, biology and medicine, is implemented. Emphasizing this perspective, here we address important issues for the rapid development of the field, i.e., magnetic behavior at the nanoscale with emphasis on the relaxation dynamics, synthesis and surface functionalization of nanoparticles and core-shell structures, biocompatibility and toxicity studies, biological constraints and opportunities, and in vivo and in vitro applications. Specifically, we discuss targeted drug delivery and triggered release, novel contrast agents for magnetic resonance imaging, cancer therapy using magnetic fluid hyperthermia, in vitro diagnostics and the emerging magnetic particle imaging technique, that is quantitative and sensitive enough to compete with established imaging methods. In addition, the physics of self-assembly, which is fundamental to both biology and the future development of nanoscience, is illustrated with magnetic nanoparticles. It is shown that various competing energies associated with self-assembly converge on the nanometer length scale and different assemblies can be tailored by varying particle size and size distribution. Throughout this paper, while we discuss our recent research in the broad context of the multidisciplinary literature, we hope to bridge the gap between related work in physics/chemistry/engineering and biology/medicine and, at the same time, present the essential concepts in the individual disciplines. This approach is essential as biomedical nanomagnetics moves into the next phase of innovative translational research with emphasis on development of quantitative in vivo imaging, targeted and triggered drug release, and image guided therapy including validation of delivery and therapy response.