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排序方式: 共有2398条查询结果,搜索用时 31 毫秒
31.
Kähkönen E Nykyri E Ilmarinen R Ketola R Lusa S Nygård CH Suurnäkki T 《Applied ergonomics》1992,23(3):186-190
A study was made of the appraisers' effect on the estimation of metabolic rate with the Edholm scale and a table of the ISO 7243 heat stress standard. The appraisers, five experienced and five inexperienced persons, estimated the metabolic rate of three different work tasks from videotapes. Analysis of variance indicated significant ( [Formula: see text] ) differences in the appraisers' recordings of the activities. The appraisers were grouped according to the similarity of the estimated values they gave. The groups thus contained both experienced and inexperienced appraisers, and it was not possible to classify the appraisers into experienced and inexperienced groups according to their earlier experience. The metabolic rates according to the Edholm scale were higher than according to the ISO 7243 table. The differences in metabolic rates given by the individual observers varied from 38 to 118 W/m(2). The variations in the estimation of metabolic rates were greater when the Edholm scale was used. This variation caused considerable variation also in the predicted mean vote, PMV index. It is recommended that the appraisers be selected carefully, because it is not possible to know whether a randomly selected appraiser is an 'average' or an 'extreme' appraiser without a test. Before conducting extensive field surveys where several appraisers estimate the metabolic rates, it would be useful to arrange training in order to calibrate the levels of the Edholm scale as well as ISO method among the appraisers because training clearly unified the estimation. 相似文献
32.
In this paper we study small depth circuits that contain threshold gates (with or without weights) and parity gates. All circuits we consider are of polynomial size. We prove several results which complete the work on characterizing possible inclusions between many classes defined by small depth circuits. These results are the following:
相似文献
1. | A single threshold gate with weights cannot in general be replaced by a polynomial fan-in unweighted threshold gate of parity gates. |
2. | On the other hand it can be replaced by a depth 2 unweighted threshold circuit of polynomial size. An extension of this construction is used to prove that whatever can be computed by a depthd polynomial size threshold circuit with weights can be computed by a depthd+1 polynomial size unweighted threshold circuit, whered is an arbitrary fixed integer. |
3. | A polynomial fan-in threshold gate (with weights) of parity gates cannot in general be replaced by a depth 2 unweighted threshold circuit of polynomial size. |
33.
Experimental information and theoretical estimates for the enthalpy of formation at 298 K for the RM2 (whereM = Fe, Co,orNi andR = La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, or Lu) lanthanide Laves phases with the MgCu2 (C15) structure are reviewed and discussed in the light of information on lattice parameters and atomic volume. The purpose of the present study is to analyze all the available experimental information on enthalpies of formation for transition-metal lanthanide Laves phases and then plot the data in order to reveal tendencies and allow reliable estimates of data that have not yet been measured. It is concluded that as the lanthanide atomic number increases the enthalpy of formation is almost constant or becomes slightly more negative. The accompanying volume contraction is slightly larger than expected from the lanthanide contraction, 7.6 %. From the so-called Gschneidner correlation one would have expected the contrary behavior, that is, that the bonding strength would become slightly lower when going from LaM2 to LuM2. An increase in the transition-metal atomic number has a stronger effect on the enthalpy of formation and atomic volume than an increase in the lanthanide atomic number. 相似文献
34.
Ståhlkrantz Adam Hedström Peter Sarius Niklas Borgenstam Annika 《Metallurgical and Materials Transactions A》2022,53(9):3418-3427
Metallurgical and Materials Transactions A - Variant pairing in bainite was evaluated in four different commercial low alloy steels with medium to high carbon content. The steels investigated were... 相似文献
35.
The kinetics of aluminium deposition from NaCl-AlCl3 melts (cAlCl3 < 10 mol%) contained in alumina crucibles was studied by linear sweep voltammetry and potential step amperometry at temperatures around 820°C. At low concentrations (cAlCl3 < 0.4 mol%) the reduction of AlCl3 on liquid aluminium has been found to be diffusion controlled. At higher concentrations a passivation of the aluminium electrode was observed during the deposition reaction. The passivation appears to be caused by precipitation of alumina from supersaturated melt in the diffusion layer at the aluminium cathode. 相似文献
36.
The poisoning effect of various halogen compounds on a nickel-based hydrogenation catalyst has been investigated. While alkyl
monochlorides did not affect the catalyst activity, alkyl monobromide and-iodide had a strong poisonous effect. Vicinal dichlorides,
1,1-dichlorides, and HC1 also poisoned the catalyst. It is shown that with chlorine containing compounds, the poisoning mechanism
involves a fission of the carbon-chlorine bond with the formation of HC1, while bromine and iodine compounds adsorb to the
catalyst surface as such in a simple equilibrium reaction. A mackerel oil previously shown to exhibit three kinetically distinguishable
poisoning effects has been further examined, and it is shown that its content of halogens can probably account for the observed
poisoning pattern. 相似文献
37.
Dorota Johansson Björn Bergenståhl 《Journal of the American Oil Chemists' Society》1992,69(8):728-733
The influence of water on the interactions between fat and sugar crystals dispersed in triglyceride (vegetable) oils was qualitatively
estimated from sedimentation and rheological experiments. The experiments were performed both with and without food emulsifiers
(monoglycerides and lecithins) present in the oil. The effects of minor natural oil components (nontriglycerides) on the interactions
and on emulsifier adsorption to the crystals were examined by comparing a commercial refined oil and a chromatographically
purified oil. The results show that water generally increases the adhesion between fat and sugar crystals in oils and also
increases the surface activity of the oil-soluble food emulsifiers. Minor oil components give a small increase in the adhesion
between fat and sugar crystals in oils, but do not influence the adsorption of food emulsifiers in any systematic way. 相似文献
38.
Attraction of fry of Arctic char [Salvelinus alpinus (L.)] to water conditioned by conspecifics of the same age was studied in a Y-maze fluviarium. Two types of experiments were run. In up-swimming tests (1), starting from the common leg of the Y-maze, a single fish was given the choice of entering one of the two upstream arms. In gradient tests (2), the momentary positions of a single char were time-lapse photographed in a test yard of this common shank. Strong attraction to conditioned water was observed in both types of tests. 相似文献
39.
O. Podlaha B. Tregrd B. Petersson 《European Journal of Lipid Science and Technology》1982,84(1):17-20
Analysis of Triglycerides Only recently the analytic of triglycerides of natural fats and oils has found in HPLC an adaquate method. By means of HPLC it is possible to separate the glycerides of the fat with respect to partition number (PN) and to analyse the collected fractions by GLC with respect to carbon number (CN). This procedure yields a complete basis for calculation of the composition of triglyceride groups which are characterized by their carbon number and number of double bonds (e.g. C54:1). If the analytical data of each fraction are completed with the fatty acid composition, the fatty acid combination of the single triglycerides and their distribution can likely be characterized. This method was applied to triglyceride analysis of LOBRA oil. The obtained results are reported. 相似文献
40.
Standard methods for the determination of iodine values of oils involve direct addition of halogen elements to the double bond. Since the reaction proceeds slowly there is a risk of substitution. A direct coulometrical titration method has been investigated. 相似文献