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排序方式: 共有87条查询结果,搜索用时 140 毫秒
21.
The health monitoring has been studied to ensure integrity of design of engine structure by detection, quantification, and prediction of damages. Early detection of faults may allow the downtime of maintenance to be rescheduled, thus preventing sudden shutdown of machines. In cylinder pressure developed, vibrations and noise emissions data provide a rich source of information about condition of engines. Monitoring of vibrations and noise emissions are novel non-intrusive methodologies for which positioning of various transducers are important issue. The presented work shows applicability of these diagnosis methodologies adopted in case of diesel engines. The effects of changing various fuel injection parameters was analyzed. Scope of using non-intrusive technique has been analyzed by changing locations of microphone. Novelty of this worklies in exploring signal processing methods for various locations around the engine test set up. Various frequency ranges of contributing noise and vibration sources were identified. Time-Frequency analysis showed the onset of various cyclic. Based on the identification of various frequency bands, it is possible to device suitable filters in order to extract more information. 相似文献
22.
Laura J. Parry Victoria Vinader Ian J. Scowen Vipul K. Patel Kamyar Afarinkia 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-3):195-199
Abstract The Horner-Wittig reaction between diphenyl(2-phenylpropyl)phosphine oxide and 1-naphtaldehyde affords an equal mixture of the cis and trans isomers even though the formation of the initial adduct is selective. 相似文献
23.
Das Ritu Dhiman Abhijeet Kapil Arti Bansal Vipul Sharma Tarun Kumar 《Analytical and bioanalytical chemistry》2019,411(6):1229-1238
Analytical and Bioanalytical Chemistry - Despite of various advancements in biosensing, a rapid, accurate, and on-site detection of a bacterial pathogen is a real challenge due to the lack of... 相似文献
24.
We analyze a holey fiber that consists of a circular distribution of air holes by the radial effective-index method. By this method, we show that the holey fiber is a leaky structure and its extended single-mode operation is governed by the differential leakage loss between the first two modes of the fiber. The effects of the hole size and the hole separation on the leakage losses of the first two modes are calculated. The leakage loss of the fundamental mode of the fiber is found to be comparable to that of a conventional holey fiber that has a hexagonal distribution of air holes. 相似文献
25.
Vipul J. Srivastava Kerby F. Fannin David P. Chynoweth James R. Frank 《Applied biochemistry and biotechnology》1988,18(1):111-126
A nonmixed upflow solids reactor (USR), which permitted longer solids than hydraulic retention times, was used to study the
anaerobic digestion performance of sea kelp (Macrocystis pyrifera). The performance of the USR was compared to that of the continuously stirred tank reactor (CSTR) at different organic loading
rates in terms of methane yield, methane production rate, and process stability. Results showed that, although digester performance
was markedly affected by kelp compositional variability, methane yields and production rates in the USR were significantly
higher than those observed with the CSTR. Results also showed that volatile acid concentrations, which are generally inversely
related to digester stability, were significantly lower in the USR than in the CSTR. 相似文献
26.
Multicritical potentials and correlation functions are given for models of rectangular M × N matrices, in the limit that N goes to infinity. These models are soluble without using orthogonal polynomials, and describe filamentary random surfaces, or, equivalently, a phase of branched polymers. It is shown that the equations describing multicritical behaviour are obtained from the hierarchy of flows that preserve Burgers' equation. Instanton solutions are studied - they imply that only the k = 2 model is unitary, and that the coefficients (for arbitrary k) of gstl is the perturbative expansion of the specific heat grow as l!. 相似文献
27.
Pressure induced structural phase transition of mono-antimonides of lanthanum, cerium, praseodymium and neodymium (LnSb, Ln=La, Ce, Pr and Nd) has been studied theoretically using an inter-ionic potential with modified ionic charge which parametrically includes the effect of Coulomb screening by the delocalized f electrons of rare earth (RE) ion. The anomalous structural properties of these compounds have been interpreted in terms of the hybridization of f electrons with the conduction band and strong mixing of f states of Ln ion with the p orbital of neighbouring antimonide ion. All the four compounds are found to undergo from their initial NaCl (B1) phase to body centered tetragonal (BCT) phase at high pressure and agree well with the experimental results. The body centered tetragonal phase is viewed as distorted CsCl structure and is highly anisotropic with c/a=0.82. The transition pressure of LnSb compounds is observed to increase with decreasing lattice constant in NaCl phase. The nature of bonds between the ions is predicted by simulating the ion-ion (Ln-Ln and Ln-Sb) distances at high pressure. The calculated values of elastic constants are also reported. 相似文献
28.
Bansal V Syed A Bhargava SK Ahmad A Sastry M 《Langmuir : the ACS journal of surfaces and colloids》2007,23(9):4993-4998
One of the important routes for the production of zirconia is by chemical treatment and removal of silica from zircon sand (ZrSixOy). We present here a completely green chemistry approach toward enrichment of zirconia in zircon sand; this is based on the reaction of the fungus Fusarium oxysporum with zircon sand by a process of selective extracellular bioleaching of silica nanoparticles. Since this reaction does not result in zirconia being simultaneously leached out from the sand, there is a consequent enrichment of the zirconia component in zircon sand. We believe that fungal enzymes specifically hydrolyze the silicates present in the sand to form silicic acid, which on condensation by certain other fungal enzymes results in room-temperature synthesis of silica nanoparticles. This fungus-mediated twofold approach might have vast commercial implications in low-cost, ecofriendly, room-temperature syntheses of technologically important oxide nanomaterials from potentially cheap naturally available raw materials like zircon sand. 相似文献
29.
Gitanjali Pagare Vipul Srivastava Sankar P. Sanyal M. Rajagopalan 《Physica B: Condensed Matter》2011,406(3):449-455
The ground state electronic structure and thermal properties of B2-type intermetallic compounds AlRE (RE: Pm, Sm, Eu, Tb, Gd and Dy) have been studied using a self-consistent tight-binding linear muffin-tin orbital (TB-LMTO) method at ambient as well as at high pressure. These compounds show metallic behavior under ambient condition. The band structure, total energy, density of states and ground state properties like lattice parameter, bulk modulus are calculated in the present work. The Debye-Grüneisen model is used to calculate the Debye temperature and the Grüneisen constant. The calculated results are in good agreement with the reported experimental and other theoretical results. The variation in the Debye temperature with pressure has also been reported. We present a detailed analysis of the role of f electrons of RE in the AlRE system. 相似文献
30.