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This paper presents a control scheme for single phase grid connected photovoltaic (PV) system operating under both grid connected and isolated grid mode. The control techniques include voltage and current control of grid-tie PV inverter. During grid connected mode, grid controls the amplitude and frequency of the PV inverter output voltage, and the inverter operates in a current controlled mode. The current controller for grid connected mode fulfills two requirements – namely, (i) during light load condition the excess energy generated from the PV inverter is fed to the grid and (ii) during an overload condition or in case of unfavorable atmospheric conditions the load demand is met by both PV inverter and the grid. In order to synchronize the PV inverter with the grid a dual transport delay based phase locked loop (PLL) is used. On the other hand, during isolated grid operation the PV inverter operates in voltage-controlled mode to maintain a constant amplitude and frequency of the voltage across the load. For the optimum use of the PV module, a modified P&O based maximum power point tracking (MPPT) controller is used which enables the maximum power extraction under varying irradiation and temperature conditions. The validity of the proposed system is verified through simulation as well as hardware implementation. 相似文献
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Valuable metal extraction technology from thermal power plant fly ash is limited. In the present study, aluminium is extracted from fly ash as highly pure aluminium sulphate (>99.0%) by leaching with sulphuric acid, followed by pre-concentration and successive crystallization. Two types of fly ashes from different sources, i.e., Talcher Thermal Power Station (TTPS) and Vedanta Aluminium Company Limited (VAL) were chosen for comparative study on the extraction of aluminium as aluminium sulphate. The product is characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). Purity of aluminium sulphate was also investigated by inductively coupled plasma–optical emission spectrometry (ICP–OES). The extraction efficiency of aluminium depends on the varied solid-to-liquid ratio (fly ash : 18 mol/L H2SO4, g/mL) and particle size of fly ashes. Physico-chemical analysis indicates that the obtained product is Al2(SO4)3·18H2O, having low iron content (0.08%). 相似文献
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Swetapadma PANDA Nikhil P. ZADE Pradip SARKAR Robin DAVIS 《Frontiers of Structural and Civil Engineering》2022,16(1):117-130
Proven research output on the behavior of structures made of waste copper slag concrete can improve its utilization in the construction industry and thereby help to develop a sustainable built environment. Although numerous studies on waste copper slag concrete can be found in the published literature, no research has focused on the structural application of this type of concrete. In particular, the variability in the strength properties of waste copper slag concrete, which is required for various structural applications, such as limit state design formulation, reliability-based structural analysis, etc., has so far not attracted the attention of researchers. This paper quantifies the uncertainty associated with the compressive-, flexural- and split tensile strength of hardened concrete with different dosages of waste copper slag as fine aggregate. Best-fit probability distribution models are proposed based on statistical analyses of strength data generated from laboratory experiments. In addition, the paper presents a reliability-based seismic risk assessment of a typical waste copper slag incorporated reinforced concrete framed building, considering the proposed distribution model. The results show that waste copper slag can be safely used for seismic resistant structures as it results in an identical probability of failure and dispersion in the drift demand when compared with a conventional concrete building made of natural sand. 相似文献
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SMITA H. PANDA MOUSUMI PARMANICK RAMESH C. RAY 《Journal of Food Processing and Preservation》2007,31(1):83-101
Lactic acid (LA) fermentation has many benefits. It is feasible in small scale, inexpensive, and does not require additives and confers organoleptic characteristics to the foodstuff according to the habits and requirement of the consumers. Sweet potato roots were pickled by lactic fermentation by brining the cut and blanched roots in common salt (NaCl, 2–10%) solution and subsequently inoculated with a strain of Lactobacillus plantarum (MTCC 1407) for 28 days. The treatment with 8–10% brine solution was found to be the most acceptable organoleptically. The final product with 8 and 10% brine solutions had a pH of 2.9–3.0, titratable acidity of 2.9–3.7 g/kg, LA of 2.6–3.2 g/kg and starch of 58–68 g/kg on fresh weight basis. Sensory evaluation rated the sweet potato lacto‐pickle acceptable based on texture, taste, aroma, flavor and aftertaste. Principal component analyses reduced the six original analytical variables to two independent components (factors), which accounted for 92% of the total variations. 相似文献
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Supersaturated polycrystals of solid-solution spinel were heat-treated below the solvus temperature. Precipitation of α-alumina was examined by X-ray diffraction, microprobe, and scanning transmission electron microscopy. Precipitation kinetics followed classical time-temperature-transformation behavior: the precipitation rate was growth controlled at large undercoolings and nucleation controlled at low undercoolings. Scanning transmission electron microscopy and microprobe analysis revealed that the growth of precipitates was limited by interface reaction. Nucleation occurred throughout the polycrystal and was probably promoted by the grain boundaries. Precipitation was accompanied by the growth of pores at interfaces, presumably to accommodate the change in volume required by the phase transformation. Our observations in polycrystals contrast sharply with single-crystal work, where it has been reported that nucleation occurs at the free surface and that the formation of α-alumina is preceded by metastable phases. 相似文献
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This paper presents the material design and fresh properties of geopolymer mortar developed for 3D concrete printing application. Unlike traditional casting, in 3D printing, extruded materials are deposited layer-by-layer to build complex architectural and structural components without the need of any formwork and human intervention. Extrudability, shape retention, buildability and thixotropic open time (TOT) are identified as critical early-age properties to characterize the 3D printable geopolymer material. Five different mix designs of geopolymer are tested in a systematic experimental approach to obtain a best printable mix and later it is used to print a 60-centimeter-tall freeform structure using a concrete gantry printer to validate the formulation. 相似文献
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Padhi Biranchi Narayana Pandey Mukundjee Mishra Ipsita 《Journal of Mechanical Science and Technology》2021,35(10):4737-4746
Journal of Mechanical Science and Technology - The article deals with the effects of change in dimensions of solar chimney upon the thermodynamic characteristics of the air flowing inside it. The... 相似文献