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排序方式: 共有465条查询结果,搜索用时 15 毫秒
1.
2.
A. Vahid Shahidi I. Shih T. Araki C. H. Champness 《Journal of Electronic Materials》1985,14(3):297-310
Structural investigation on monocrystalline CuInSe2 samples has been made. From the single crystal results, the space group of CuInSe2 was confirmed to be Iˉ42d and the crystal solidification direction was investigated. Compositional uniformity of the ingots
was established by EPMA and it was found that the indium concentration was greater than that for copper. Systematic annealing
experiments were carried out in vacuum at different temperatures (as low as 160° C) and for different times. Large variation
in resistivity was observed after the annealing treatment. P-type samples were found to convert to n-type after the heat-treatments. 相似文献
3.
A finite element model was developed to simulate the temperature distributions produced by radiofrequency catheter ablation. This model incorporated blood, myocardium and torso tissues. The Laplace equation was solved to determine the steady-state electric field. The heat generation in the tissues was then computed from the power density distribution and the bioheat equation was solved to determine the time-varying temperature distribution, taking into account the convective energy exchange at the blood-myocardium and torso-air interfaces. This model was used to predict the lesion depth and to evaluate the effects of electrode location, changes of the electrical and thermal conductivities, and the electrode radius on the thermally induced damage to the myocardium. Temperature distributions induced by radiofrequency ablation were found to be: i) not very sensitive to the reference electrode location, ii) more sensitive to electrical conductivity changes than to thermal conductivity changes, and iii) larger electrodes allow a current distribution at higher level of power with reducing the chance of impedance rise 相似文献
4.
A genetic algorithm for the optimisation of assembly sequences 总被引:6,自引:0,他引:6
This paper describes a Genetic Algorithm (GA) designed to optimise the Assembly Sequence Planning Problem (ASPP), an extremely diverse, large scale and highly constrained combinatorial problem. The modelling of the ASPP problem, which has to be able to encode any industrial-size product with realistic constraints, and the GA have been designed to accommodate any type of assembly plan and component. A number of specific modelling issues necessary for understanding the manner in which the algorithm works and how it relates to real-life problems, are succinctly presented, as they have to be taken into account/adapted/solved prior to Solving and Optimising (S/O) the problem. The GA has a classical structure but modified genetic operators, to avoid the combinatorial explosion. It works only with feasible assembly sequences and has the ability to search the entire solution space of full-scale, unabridged problems of industrial size. A case study illustrates the application of the proposed GA for a 25-components product. 相似文献
5.
Mechanically deboned chicken meat (MDCM) was washed with water, 0·5% NaCl or 0·5% NaHCO(3) solutions. Approximately 75·5% of the total hemoprotein pigments were removed by washing of MDCM with a sodium bicarbonate solution which resulted in the best colour improvements in the samples. Approximately 18·7% of total lipids were removed as a result of aqueous washing. The yield of proteins ranged from 56·5% after one washing with water to 43·4% after washing with water and then with a sodium bicarbonate solution. The Hunter L and a colour parameters of the samples correlated well with the total hemoproteins (correlation coefficients -0·984 and +0·947, respectively); corresponding correlation coefficient with the Hunter b value was only +0·693. 相似文献
6.
M.?NaczkEmail author R.?B.?Pegg R.?Zadernowski F.?Shahidi 《Journal of the American Oil Chemists' Society》2005,82(4):255-260
Possible use of canola hulls as a source of natural anti-oxidants was explored. Cyclone canola hulls were extracted with methanol
(30 to 80%, vol/vol) and acetone (30 to 80%, vol/vol). The free radical-scavenging activity of phenolic extracts so prepared
was evaluated using the 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS) radical ion (ABTSo−), 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, and chemiluminescence assays. The total content of phenolics in prepared
extracts from canola hulls ranged from 15 to 136 mg sinapic acid equivalents per gram of extract. Higher levels of condensed
tannins were detected in the acetone extracts than in the corresponding methanolic counterparts. Seventy and 80% (vol/vol)
acetone extracts displayed markedly stronger antioxidant activity than any of the other extracts investigated. Statistically
significant linear correlations were found between TEAC (Trolox equivalent antioxidant capacity) values (expressed in mM of
Trolox equivalents per gram of extract) and total pehnolics, TEAC and total condensed tannins (i.e., determined using the
modified vanillin and pronthocyanidin assays), as well as TEAC and protein precipitation activity of phenolic extracts (i.e.,
measured using the dye-labeled assay). The antioxidant activities of extracts as determined by the ABTSo− radical ion assay correlated highly with those of the chemiluminescence and DPPH radical assays. 相似文献
7.
Kazem Tahmasebi Mohammad Maleki Shahraki Touraj Ebadzadeh 《Materials and Manufacturing Processes》2018,33(8):817-821
Coarse-grained ZnO varistors for low-voltage applications were prepared by microwave sintering technique under different soaking times of 5–150?min. For comparison, a low-voltage ZnO varistor was also prepared through a conventional sintering process. Microwave sintering remarkably enhanced the grain growth rate of ZnO varistors. Average grain size of the sample prepared by microwave sintering in 15?min was about 20?µm, which is similar to the grain size of sample prepared conventionally in 150?min time. In addition to grain growth, an increase in microwave sintering time led to precipitation of zinc titanate (Zn2TiO4) on the top surface of samples which sintered for long dwell times. X-ray diffraction and scanning electron microscopy results from different points of the samples declared that precipitation of Zn2TiO4 phase is due to the high rate of bismuth evaporation of Bi-rich liquid from top surface and the reaction between remaining titanium ions on the surface with ZnO. The results showed that increasing sintering time from 5 to 150?min increased the grain size from 14 to 33?µm, consequently, the breakdown field decreased from 90 to 27?V/mm, respectively. These changes led to a switch in the varistor application, from low to very low voltage. 相似文献
8.
Accurate robotic belt grinding of workpieces with complex geometries using relative calibration techniques 总被引:2,自引:0,他引:2
Robotic belt grinding operations are performed by mounting a workpiece to the end effector and commanding it to move along a trajectory while maintaining contact with the belt grinding wheel. A constant contact force throughout the grinding process is necessary to provide a smooth finish on the workpiece, but it is difficult to maintain this force due to a multitude of installation, manipulation, and calibration errors. The following describes a novel methodology for robotic belt grinding, which primarily focuses on system calibration and force control to improve grinding performance. The overall theory is described and experimental results of turbine blade grinding for each step of the methodology are shown. 相似文献
9.
Kazem Taghva Eric Stofsky 《International Journal on Document Analysis and Recognition》2001,3(3):125-137
In this paper, we describe a spelling correction system designed specifically for OCR-generated text that selects candidate
words through the use of information gathered from multiple knowledge sources. This system for text correction is based on
static and dynamic device mappings, approximate string matching, and n-gram analysis. Our statistically based, Bayesian system
incorporates a learning feature that collects confusion information at the collection and document levels. An evaluation of
the new system is presented as well.
Received August 16, 2000 / Revised October 6, 2000 相似文献
10.
The primary purpose of this paper is to propose a computer aided optimal design system to support a generalized oval–round pass design, which is widely used as both intermediate and final passes in the process of rod rolling. This system, which is based on a hybrid model and the genetic algorithm, is developed to improve the efficiency, to reduce the manufacturing errors, as well as to extend the useful life of rolls through uniform wear design. Generalized parametric equations are established for geometrical modeling, graphic plotting of oval–round passes, as well as calculation of the cross section area, contact area and the lengths of contact arcs along the cross section of round groove in the MATLAB programming environment. Moreover, these equations can also realize the parametric transformation between roll profile and mathematical models for the oval–round pass design and optimization. The genetic algorithm is employed for the optimal design of oval–round passes in this paper. The objective functions are formulated for minimization of power consumption in the rolling process, variances between ideal dimensions and design dimensions, as well as variances between the lengths of contact arcs. To reduce the complexity and computational burden of the system, some reliable empirical formulas for the calculations of contact area and contact arc length are applied. Finally, the proposed approach is applied to an oval–round pass design. Through simulation and comparison of results against experimental data acquired from literature, it is found that this system is reliable, effective and easier to use. 相似文献