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排序方式: 共有1650条查询结果,搜索用时 15 毫秒
81.
This paper presents the results of a residential customer survey conducted in service areas of the Nepal Integrated Electric Power System (NPS). The objective was to determine the power interruption costs incurred by the residential customers of a developing country, and extend the customer survey approach to reliability worth evaluation in a developing environment. Interruption cost estimates were obtained using in-person interviews with 944 sample customers. The results indicate the implications of service reliability to residential customers of Nepal, and show that reliability worth evaluation in a developing country is both possible and practical 相似文献
82.
The aim of the paper is to propose two efficient algorithms for the numerical evaluation of Hankel transform of order ν, ν>−1 using Legendre and rationalized Haar (RH) wavelets. The philosophy behind the algorithms is to replace the part xf(x) of the integrand by its wavelet decomposition obtained by using Legendre wavelets for the first algorithm and RH wavelets for the second one, thus representing Fν(y) as a Fourier-Bessel series with coefficients depending strongly on the input function xf(x) in both the cases. Numerical evaluations of test functions with known analytical Hankel transforms illustrate the proposed algorithms. 相似文献
83.
Dharmendra Pratap Singh Swadesh Kumar Gupta Satya Prakash Yadav P K Sharma A C Pandey Rajiv Manohar 《Bulletin of Materials Science》2014,37(3):511-518
The present paper deals with the characterization of a ferroelectric liquid crystal–nanoparticle (FLC–NP) composite system. The dielectric, electrical and polarization property of the FLC–NP composite system have been studied as a function of temperature and frequency. Ferroelectric Cu-doped ZnO (Cu–ZnO) nanoparticles have been added to the pure ferroelectric liquid crystal (FLC) Felix 17/100. The nanoparticles are bigger in size as compared to FLC molecules; therefore, they distort the existing geometry of FLC matrix and set up an antiparallel correlation with the dipole moments of the host FLC molecules. This antiparallel correlation of guest–host geometry reduces the net ferroelectricity of the composite system and modifies all the physical properties of the pure FLC. The change in properties has been analysed and explained in the light of guest–host interaction. 相似文献
84.
The optical and electrical properties of the conducting polymer poly(3-hexylthiophene) and single walled carbon nanotube (SWCNT) composites have been investigated. The composites were prepared by dispersing carbon nanotubes in the polymer matrix already dissolved in 1,2-dichlorobenzene. The optical absorption, photoluminescence (PL) and electrical conductivity of the composite was studied as a function of SWCNT concentration in the solution. The absorption coefficient of the polymer was found to be unaffected upto a SWCNT concentration 5% w/w. However a minor decrease in the absorption in visible region was observed for higher SWCNT concentrations. The intensity of PL emission from the composite was measured and was found to decrease with the increase in SWCNT concentration. For a SWCNT concentration of 30% w/w, ∼90% of the PL was quenched, indicating an ultra fast transfer of photoinduced charges from donor polymer to acceptor SWCNT. Direct current conductivity of the composite film was found to increase rapidly with the increase in SWCNT concentration and an increase of ∼5 orders of magnitude was observed for a 30% w/w concentration. The enhancement in conductivity is explained in terms of percolation theory with an estimated percolation threshold of 2% w/w. 相似文献
85.
R.K. Pandey 《Engineering Fracture Mechanics》1989,34(5-6):1119-1129
The metallurgical changes have been studied in a typical offshore structure material, BS4360 grade 50E steel at various simulated depths (0–185 m) in the dry underwater welding conditions and the weld metal and heat affected zone (HAZ) fracture toughness have been related with the microstructure and micromechanisms of fracture. The results indicated substantial decrease in weld metal CTOD toughness at 185 m welding depth whereas HAZ toughness remained generally unaffected. High toughness of weld metal was found to be associated with greater proportion of the polygonal and the acicular ferrites and negligible proportion of aligned cerbide. High HAZ toughness was due to fine ferrite (6–8 μm) and absence of martensite in the structure. 相似文献
86.
Plasmodium yoelii infected cerebral microvessels of mice had an enhanced time-dependent, temperature-sensitive, and saturable uptake of [14C]-amino acid. viz. leucine, valine and glycine. Metabolic inhibitors caused a noticeable inhibition of amino acid uptake in normal microvessels as compared to infected cerebral microvessels indicating that the uptake of [14C]-L-leucine, [14C]-L-valine and [14C]-glycine is an energy dependent process. 相似文献
87.
In this paper, we propose a shrinkage testimator for the shape parameter λ of an Inverse Gaussian distribution when the estimated value of λ is available in such a way that either λ = λ1 or λ = λ2(>;λ1) is expected. The (α + β)min test for testing the hypothesis H0: λ = λ1 against H1: λ = λ2 is derived. The shrinkage factors are chosen to be the function of the (α + β)min test. The shrinkage testimator is found to be more efficient (in the sense of the MSE) than the UMVUE in certain parametric space. 相似文献
88.
Thermally stimulated depolarization current (TSDC) studies have been performed on solution grown cellulose acetate films doped
with different concentrations of acrylic acid (AA) prepared at the poling temperatures (40–75°C) with poling fields (10–50
kV/cm). The TSDC spectra of pure and AA doped CA films reveal two relaxation peaks at 80°C and 180 ±2°C, having activation
energies centred around 0.25 and 0.55 eV. The phenomena of the existence of these current maxima have been analyzed and discussed
in terms of the molecular motion of the polar side groups and release of the remaining part of the frozen dipoles by their
cooperative motion with adjoining segments of the main polymer chain. The peak currents, released charge and activation energies
associated with the peaks are affected by AA doping. The effect of doping with acrylic acid on the discharge current indicates
the formation of molecular aggregates 相似文献
89.
90.
A shrinkage testimator, based on a test of hypothesis when an initial estimate of the scale parameter is available, has been proposed. The salient feature of the proposed testimator is that, being dependent on the test statistic, it removes arbitrariness in the choice of the shrinkage factor for a given level of significance. Expressions for bias, mean square error and relative efficiency with respect to the conventional estimator have been derived. Also, it has been shown that by taking the square of the shrinkage factor the relative efficiency of the testimator can be increased. 相似文献