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排序方式: 共有678条查询结果,搜索用时 31 毫秒
531.
Prangya Parimita Sahoo S. Sumithra Giridhar Madras T. N. Guru Row 《Bulletin of Materials Science》2009,32(3):337-342
Monoclinic ZrMo2O8 was synthesized via solid state method and single crystals of the title compound have been grown by the hydrothermal method. The crystals belong to monoclinic crystal system with space group C2/c (No. 15) with a = 11·4243(19) Å, b = 7·9297(6) Å, c = 7·4610(14) Å and β = 122·15(2)°, Z = 4. The bandgap of the compound was 2·57 eV. Unlike the other polymorphs of ZrMo2O8, the monoclinic form has unique crystallographic features with ZrO8 and Mo2O8 polyhedra. The photocatalytic activity of this compound has been investigated for the first time for the degradation of various dyes under UV irradiation and has been compared with the photoactivity of the trigonal form of ZrMo2O8. It has been observed that this compound exhibits specificity towards the degradation of cationic dyes. 相似文献
532.
K. L. Sahoo P. Poddar Randhir Kumar P. T. Pushp 《Transactions of the Indian Institute of Metals》2009,62(4-5):275-278
Processing of alloys in the semi solid state, within the liquidus and solidus temperature, has several potential advantages over casting and forging, such as reduction of macrosegregation, porosity and improved properties. A356 alloy produced by means of conventional gravity die casting, rheocasting and strain induced melt activation (SIMA) process has been investigated and their microstructure, mechanical and tribological properties were compared. The microstructure of conventional cast sample is fully dendritic in contrast to spheroidal morphology in rheocast and SIMA samples. The mechanical properties of the SIMA samples are considerably higher than that of conventional cast and rheocast samples. The volumetric wear loss and co-efficient of friction in SIMA samples are always less than those in conventional cast samples at all loads. 相似文献
533.
Thermal conductivity and viscosity analysis of Al2O 3/CuO (50/50) hybrid nanofluid in various mass fractions of ethylene glycol (EG) and propylene glycol (PG) binary base fluid have been investigated in the present work. Hybrid nanofluid with vol. fraction range limited to 1.5% and within the higher temperature range of 50°C to 70°C is considered for thermal conductivity and viscosity analysis. Impact on viscosity and conductivity models with various shape nanoparticles, i.e, spherical, cylindrical, brick, platelets, and blades have been discussed and were compared in EG and PG binary base fluids. Also, the analysis extends to the prediction for the stability with zeta potential and synthesis of spherical shape Al2O3/CuO hybrid nanofluid with X‐ray diffraction (XRD) and scanning electron microscope (SEM). The theoretical analysis revealed that thermal conductivity of Al2O3/CuO hybrid nanofluid in EG binary base fluid is lower compared to in PG binary base fluid. The thermal conductivity is observed to be higher in spherical and cylindrical shape nanoparticle compared to bricks, blades, and platelets shape nanoparticles. Optimum viscosity of Al2O3/CuO hybrid nanofluid is observed at 50%EG and 30%PG of the binary base fluid. Hybrid nanofluid in 30% of PG as binary base fluid results 16.2% higher dynamic viscosity compared to pure PG base fluid for a volume concentration of 2%. Zeta potential measurement results in the stability of spherical Al2O3‐CuO/ (50/50) EG/W hybrid nanofluid, and it may be considered as a heat transfer fluid. 相似文献
534.
Energy and exergy analysis comparison of lauric and stearic acid phase‐change material (PCM)–based energy storage system integrated with engine exhaust have been investigated in the present study, which provides more realistic assessment than the conventional energy analysis. On the basis of thermodynamic laws, energy, exergy, charging efficiencies, and availability of PCM thermal storage with various mass fractions have been investigated at engine full load. The exergy saved for PCMs in the overall system is quantified and were compared. The results revealed a considerable enhancement in energy and exergy efficiency for thermal energy storage with lauric acid PCM due to its enhanced thermophysical properties. Energy and exergy of the storage medium for lauric acid PCM with 0.4 kg mass fraction, increased by 68% and 57.5% compared with stearic acid PCM thermal storage integrated with a diesel engine. Also, energy and exergy efficiency of charging and integrating the system with stearic acid PCM decrease with increase in mass fractions. Thus, lauric acid PCM can be used as thermal storage medium at high temperatures for exhaust heat recovery from engines and also an option for green technology. 相似文献
535.
A comparative theoretical performance analysis for diesel, 5% water in diesel emulsion (WiDE), and 10% WiDE as fuels in a single‐cylinder diesel engine is presented here. Variations in engine performance parameters such as effective power density (EPD), effective power (EP), and effective efficiency (EE), along with compression ratio and equivalence ratio, have been analyzed on the basis of isobaric heat addition and isochoric heat rejection assumptions. Also, friction loss, exhaust loss, and total loss occurring in engines with the above‐mentioned fuels have been discussed. Theoretical analysis revealed that in a diesel engine with compression ratio 18, the EP and power density increased by 28.6% and 30.45%, respectively, for diesel fuel compared with 10% WiDE fuel. The optimum cycle temperature ratio, EP, and power density were obtained with an equivalence ratio of 1.2 and the optimum EE with an equivalence ratio of 0.89 for diesel, 5% WiDE, and 10% WiDE fuels. However, the maximum exhaust loss and the minimum incomplete combustion losses were obtained with an equivalence ratio of 1.2 and 0.8, respectively. At an equivalence ratio of 1.2, diesel fuel had a higher exhaust loss of 9.25% and 27.21% and heat loss of 5.39% and 11.8%, respectively, compared with 5% WiDE and 10% WiDE fuels. Thus, the fuel consumption rate with diesel as fuel was higher, followed by 5% WiDE and 10% WiDE fuels for diesel engine performance. 相似文献
536.
Sahoo KC Chang EY Li Y Lin MK Huang JH 《Journal of nanoscience and nanotechnology》2010,10(9):5692-5699
To replace the double layer antireflection coating and improve the efficiency of solar cell, a self assembled nickel nano particle mask followed by inductively coupled plasma (ICP) ion etching method is proposed to form the sub-wavelength structures (SWS) on silicon nitride (Si3N4) antireflection coating layers instead of semiconductor layer. The size and density of nickel nano particles can be controlled by the initial thickness of nickel film that is annealed to form the nano-particles on the Si3N4 film deposited on the silicon substrate. ICP etching time is responsible for controlling the height of the fabricated Si3N4 SWS on silicon substrate, which is seen from our experiment. It is found that the lowest average reflectivity of 3.12% for wavelength ranging from 350 to 1000 nm is achieved when the diameter and height of the SWS are 120-180 nm and 150-160 nm, respectively. A low reflectance below 1% is observed over the wavelength from 590 to 680 nm for the fabricated Si3N4 SWS on silicon subs. The efficiency of Si3N4 SWS could be improved by 1.31%, compared with the single layer anti-reflection (SLAR) coatings of Si3N4, using PC1D program. The results of this study may benefit the fabrication of solar cells. 相似文献
537.
Oblique flexural gravity-wave scattering due to an abrupt change in water depth in the presence of a compressive force is
investigated based on the linearized water-wave theory in the case of finite water depth and shallow-water approximation.
Using the results for a single step, wide-spacing approximation is used to analyze wave transformation by multiple steps and
submerged block. An energy relation for oblique flexural gravity-wave scattering due to a change in bottom topography is derived
using the argument of wave energy flux and is used to check the accuracy of the computation. The changes in water depth significantly
contribute to the change in the scattering coefficients. In the case of oblique wave scattering, critical angles are observed
in certain cases. Further, a resonating pattern in the reflection coefficients is observed due to change in the water depth
irrespective of the presence of a compressive force in the case of a submerged block. 相似文献
538.
S.B. Singh M. Pandey N. Chand B. Sundaravel N.K. Sahoo 《Surface & coatings technology》2009,203(8):986-991
Diamond like carbon (DLC) films were deposited at room temperature on Si (111) substrates by microwave electron cyclotron resonance (ECR) plasma chemical vapor deposition (CVD) process using plasma of methane diluted with argon gas. During deposition, dc self bias (− 25 V to − 200 V) on substrate was varied by application of RF power to the substrate. The influence of substrate bias on density of the deposited films was studied by X-ray reflectivity (XRR). The results from these measurements are further correlated with the results from UV and visible Raman spectroscopy. DLC film is modeled as a structure having three different layers such as low density surface, bulk and interface with the substrate. This three-layer model is used to fit the measured XRR data to evaluate the surface, interface and interlayer roughness, thickness and density of these films. The surface roughness obtained from XRR is correlated with the results from Atomic Force Microscopy (AFM) measurements. The observed results are explained based on the subplantation model for DLC film growth. 相似文献
539.
Over the last few decades, doubly fed induction generators (DFIG) have become one of the most successful and preferred types of wind energy generators (WEG). The DFIG has the advantages of a wide range of speed operations, a high efficiency, and partial rated converters. However, direct coupling of the stator with the grid makes the system more prone to grid disturbances. The consequences of grid disturbances, such as a rotor overcurrent, stator overcurrent, electromagnetic torque oscillations, and direct current (DC) link overvoltage, are the predominant considerations that affect the rotor circuit, stator circuit, mechanical components, and DC‐link capacitor of the DFIG, respectively. These uncertainties affect the operation of the generator and may lead to the generator to be shutdown. In this paper, a novel position for the placement of a passive resistive element (PRE) is illustrated. This position of the PRE placement is compared with all other possible locations for the PRE. The different locations for PRE placement are the stator side, rotor side, across the DC‐link capacitor, and between the rotor side converter (RSC) and grid side converter (GSC). This paper aims to determine a cost‐effective solution among all possible locations of the PRE placement. The novel position of the PRE, ie, between the RSC and GSC, is the best position among the other possible locations of the PRE, when the performance, cost, and loss are taken into consideration. The effectiveness of the PRE is further compared with the resistive‐type superconducting fault current limiter (R‐SFCL). The PRE performs better and has a lower cost than the R‐SFCL. 相似文献
540.
Nayak Rupak Kumar Bartarya Gaurav Sahoo Manas Ranjan 《Journal of Mechanical Science and Technology》2021,35(3):1215-1222
Journal of Mechanical Science and Technology - The white layer formed during hard turning deteriorates surface integrity, thereby severely affecting the fatigue life of machined parts. A 2D... 相似文献