473 research outputs found

    Fuzzy Controller for Matrix Converter System to Improve its Quality of Output

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    In this paper, Fuzzy Logic controller is developed for ac/ac Matrix Converter. Furthermore, Total Harmonic Distortion is reduced significantly. Space Vector Algorithm is a method to improve power quality of the converter output. But its quality is limited to 86.7%.We are introduced a Cross coupled DQ axis controller to improve power quality. The Matrix Converter is an attractive topology for High voltage transformation ratio. A Matlab / Simulink simulation analysis of the Matrix Converter system is provided. The design and implementation of fuzzy controlled Matrix Converter is described. This AC-AC system is proposed as an effective replacement for the conventional AC-DC-AC system which employs a two-step power conversion.Comment: 11 page

    Accelerometer and global positioning system measurement of recovery of community ambulation across the first 6 months after stroke: an exploratory prospective study

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    Objective: To characterize community ambulation and determine if it changes across the first 6 months after discharge from hospital after stroke

    Antioxidants, anti-proliferative, anti-inflammatory, anti-diabetic and anti-microbial effects of isolated compounds from Swertia corymbosa (Grieb.) Wight ex C.B. Clark – An in vitro approach

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    AbstractThe present study, antioxidant, enzyme inhibitory, anti-inflammatory and antimicrobial activity of isolated compounds such as Decussatin (1), Gentiacaulein (2), Swertianin (3), 1,8-dihydroxy-2,6-dimethoxy xanthone (methylswertianin) (4) 8-hydroxy-1,2,4,6-tetramethoxyxanthone (5) and 1,2-dihydroxy-6-methoxyxanthone-8-O-β-d-xylopyranosyl (6) were investigated using an in vitro model. Results of antioxidant studies revealed that the compound 6 possessed an efficient 2,2-diphenyl-1-picryl-hydrazyl (DPPH) (IC50 07.19±4.56μmol/mL), 2,2-azinobis (3-ethylbenzothiozoline-6-sulfonic acid) (ABTS+) (42.62±0.25mmol/L TE/g), superoxide (57.89±3.45μmol/mL), nitric oxide (18.45±1.23μmol/mL) and hydroxyl (12.13±2.76μmol/mL) radical scavenging activities, ferric reducing antioxidant power (14.76±0.10molar Fe (II)/g), metal chelating (213.85±27.18mg EDTA/g) ability. Compounds 6 and 3 exhibited significant anti-proliferative activity. Compound 6 displayed strongest antibacterial activity against Streptococcus pneumoniae and Escherichia coli with MIC value of 3.90μg/mL and 21.21±0.25 and 20.27±0.11mm zone of inhibition at 25μg/mL concentration respectively. In the membrane stabilization and protein denaturation test 3 was the most potent with an IC50 value of 12.57, 18.75μmol/mL respectively

    Housing and child development: key dimensions, knowledge gaps and issues for future research in Australia

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    This paper begins by reviewing the existing international literature on the links between housing and child development. The housing environment can significantly improve or hinder a child’s physical, social, emotional, behavioural and cognitive development directly and via its impacts on the child’s parenting methods. The review of international literature is drawn from a range of disciplines including sociology, epidemiology, economics, housing policy, social welfare, health, medicine, child development and psychology. It highlights key dimensions of children’s housing circumstances that are associated with their health and development. These include housing tenure, neighbourhood conditions, housing affordability, homelessness, frequency of residential moves, extent of crowding, housing disrepair, environmental allergens and toxicants used in the home. The paper also raises some important conceptual and methodological issues that need to be addressed in examining the causal pathways through which housing factors influence child developmental outcomes. In particular, there is a need to isolate housing factors from confounding influences such as parental socio-economic status and identify mediating factors such as parenting behaviour, and the inter-relationships between different housing factors that need to be accounted for.There is currently a dearth of empirical studies that analyse the links between housing and child development in Australia, despite the plethora of studies examining these links in other developed countries such as the United States and United Kingdom. Hence, the third part of this paper utilises officially published statistics and the limited pool of Australian studies to highlight key policy issues requiring urgent empirical research in Australia in the near future. These issues include the disparity in housing conditions between Indigenous and non-Indigenous children, the impact of homelessness on children and measuring the impacts of housing affordability stress on child development

    Highly efficient, perfect, large angular and ultrawideband solar energy absorber for UV to MIR range

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    Although different materials and designs have been tried in search of the ideal as well as ultrawideband light absorber, achieving ultra-broadband and robust unpolarized light absorption over a wide angular range has proven to be a major issue. Light-field regulation capabilities provided by optical metamaterials are a potential new technique for perfect absorbers. It is our goal to design and demonstrate an ultra-wideband solar absorber for the ultraviolet to a mid-infrared region that has an absorptivity of TE/TM light of 96.2% on average. In the visible, NIR, and MIR bands of the solar spectrum, the absorbed energy is determined to be over 97.9%, above 96.1%, and over 95%, respectively under solar radiation according to the Air Mass Index 1.5 (AM1.5) spectrum investigation. In order to achieve this wideband absorption, the TiN material ground layer is followed by the SiO2 layer, and on top of that, a Cr layer with patterned Ti-based resonators of circular and rectangular multiple patterns. More applications in integrated optoelectronic devices could benefit from the ideal solar absorber’s strong absorption, large angular responses, and scalable construction

    Low Fatigue Response of Crest-Fixed Cold-Formed Steel Drape Curved Roof Claddings

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    Cold-formed steel roof claddings are subjected to significant suction/uplift pressures during high wind events. In New Zealand, the strong prevailing winds makes this a common occurrence. Suction pressures are generated by the turbulence of the wind flow around the building which can vary both spatially and temporally. The weakest link in the roofing system is the connection between roof sheeting and screw fasteners, which if fails, can lead to progressive collapse of the whole roofing assembly. Fluctuating high wind suction pressures can result in either static or fatigue pull-through failure of the roof sheeting at its screw fastener connections. Current literature has covered the static and fatigue wind uplift performance of crest-fixed corrugated and trapezoidal roof claddings. However, no research has been undertaken to understand the wind uplift performance of the typical crest-fixed cold-formed steel drape curved roof claddings used in New Zealand. This issue is addressed herein. In total, 35 large scale experimental tests are presented for crest-fixed drape curved steel roof claddings subjected to static and cyclic wind suction/uplift loads applied using a Pressure Loading Actuator. The material properties of claddings were determined using tensile coupon tests while the initial geometric imperfections of claddings were measured using a laser scanner. The critical fastener reactions were determined using a three axis load cell. Crack initiation, propagation of cracks, crack patterns and the number of load cycles to failure are discussed for such claddings under different load levels. Tests showed that the drape curved roof claddings are also subjected to localised dimpling and pull-through failures at their screw connections under static and cyclic wind uplift loads with the occurrence of low cycle fatigue failures under cyclic loading

    Evaluation of Anticonvulsant, Sedative, Anxiolytic, and Phytochemical Profile of the Methanol Extract from the Aerial Parts of Swertia corymbosa (Griseb.) Wight ex C.B. Clarke

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    The objective of the present study was to evaluate the anxiolytic, antidepressant, and anticonvulsant activity of the methanolic extract of Swertia corymbosa (SCMeOH). After acute toxicity test, oral treatment with SCMeOH at doses of 125, 250, and 500 mg/kg behavioral models of open field, elevated-plus-maze, actophotometer, rotarod, pentylenetetrazole, isoniazid, and maximal electroshock induced seizure models were utilized. In open field test, SCMeOH (125, 250, and 500 mg/kg) ( < 0.01, < 0.001) increased the number of rearings. However, the number of central motor and ambulation ( < 0.01, < 0.001) were reduced. Likewise, the number of entries and the time spent in open arm were increased while the number of locomotion was decreased ( < 0.001) in elevated-plus-maze and actophotometer test, respectively. SCMeOH (125-500 mg/kg) protected the mice against the pentylenetetrazole and isoniazid induced convulsions; it causes significant ( < 0.01 and < 0.001) dose dependent increase in latency of convulsion. Treatment with SCMeOH reduced the duration of the tonic hind limb extension induced by electroshock. Two major compounds such as gentiopicroside and swertianin were analyzed by HPLC system

    Immense impact from small particles: Review on stability and thermophysical properties of nanofluids

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    Nanofluid is a conventional fluid, blended with single or more nano additives with a dimension of less than 100 nm. Early studies revealed that dispersing a small amount of nano additives to base fluids can enhance the effective heat transfer properties of nanofluids by up to 250% relative to the base fluid. However, from a number of studies on nanofluid published, inconsistent thermophysical properties of formulated nanofluids reported due to many factors such as preparation approach, types of base fluids and morphology of nano additives. Selection of accurate parameters during nanofluids formulation can resolve this issue. The discussion on experimental studies by different authors include the stability evaluation of nanofluids and thermophysical measurement including its density, rheological and thermal conductivity studies can provide a guideline to the researchers towards the future development of nanofluids system with optimum thermophysical properties. This review article provided critical comments on biodegradable vegetable oil base fluid as one of the alternatives to non-renewable mineral oil as well it presents an overview of the remarkable research progress on conducting polymers base nanofluids witnessed in recent years. The outcome of this review paper would give an overview of further enhancements in nanofluid systems for industrial

    Nickel nanowire: magnetic ordering synthesis

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    Magnetic nanowires have been material of interest among researchers due to their unique magnetic properties. In the present research, Nickel (Ni) nanowires with an average diameter of 250 nm and length up to 25 μm have been successfully prepared via anodic alumina oxide (AAO) template-assisted electrodeposition method at the different magnetic field intensities and current density. The primary interest is to investigate the effect of the external magnetic field and current density on the morphological, growth length, crystal orientation and growth of the Ni nanowires. Investigation finding reveals that the employed magnetic field and current density smoothened the surface texture, improved growth length and reduced the crystal size. The observed changes are believed to be contributed by the interaction forces induced by the intensity of applied electric field and the external magnetic field known as magnetohydrodynamic (MHD) effect
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