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目前,在国内多数地区采用小电流接地选线装置。这种装置适用于3~66 kV中性点不接地或中性点经电阻、消弧线圈接地装置的单相接地选线。小电流接地选线装置,能够快速、准确的判断出单相接地故障。并且其接地电流小,如若出现事故,能够防止事故扩大的趋势。但小电流接地选线装置选线的准确率偏低,系统运行方式多变,容易引起因接地电流小而带来的误判。 相似文献
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铁路岩石二次转载生产是白云铁矿生产工艺中重要环节,其各排岩线路由于受生产制约,线路状况,外部环境影响等,捣铺周期各不相同,某些线路的捣铺周期顺延至冬季,对生产不利。文章通过调控产量,治理独头,延长线路,调节高道宽度,放宽沟塘等措施,把冬季捣铺延顺至夏秋季,节约成本,提升产能,确保安全生产。 相似文献
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对现有铁路线路设备维修体制进行分析,以可靠性为中心收集设备的故障数据,分析故障模式、原因及影响,对每一故障有针对性地确定预防性维修方案,建立合理有效的以可靠性为中心的维修模式。 相似文献
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本文介绍铁路线路钢轨长度现有的测量方法,探索提高铁路线路钢轨长度测量准确程度的几种方案. 相似文献
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介绍了内燃涂油机的基本结构、工作原理以及在铁路线路养护中的作用,对其在使用过程中的常见故障进行了分析,并提出了解决方案,实施后取得了良好效果。 相似文献
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自行研制开发了应用Ⅲ型弹条用垫板,使其可在木枕上铺设.效果良好.有足够的扣压力,阻止了线路爬行,节省维护资金投入.降低了维修工作量。 相似文献
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重载铁路是新时期铁路的发展趋势,重载铁路最主要的特点是运量大和轴重大.这两大特点必然使轨道结构承受较大的荷载,由此造成轨道结构及其部件的破坏速度较普通线路加快,线路变形也增加较大,从而线路维修养护工作量和维修成本都加大.本文主要从重载铁路线路设备现状、重载铁路病害的产生、病害整治的方法以及线路维修的作用等方面来阐述重载铁路线路养护的主要措施;确保重载铁路的安全运行. 相似文献
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本文介绍了常见过电压保护及小电流接地选线方法,介绍了消弧及过电压保护装置及小电流接地选线装置的功能、原理及在铁前变电所的应用。 相似文献
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It is argued that the clasisc prediction model is grossly oversimplified and has resulted in corresponding oversimplifications in the design of most validation studies. A modified and more complex prediction model is presented. Implications for future validation research are discussed in the context of the kinds of behaviors to be predicted, the necessity for investigating heterocedastic and nonlinear relationships, and the important advantages in prediction which may be realized by discovering homogeneous subsets of jobs, tests, people, and behavior within which prediction equations may be developed and crossvalidated. (32 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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Covariance structures analysis is often used in nursing research to appraise statistical models reflecting complex human health processes. The model selection approach in covariance structures analysis is designed to select the "best" model from a specified set of theoretically defensible, competing alternatives, all of which are viewed as approximations. Model selection criteria explicitly incorporate both model misfit in the population and sampling error to evaluate the set of models. The result is that interpretability of model parameters and goodness-of-fit are enhanced simultaneously. Relative merits of the model selection approach are identified in light of technical concerns, parsimony, and use of scientific theory in nursing. 相似文献
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Canadian industrial/organizational psychologists are being challenged to justify the use of employment selection tests to ensure adherence to fair employment practice legislation. The author examines 4 issues related to validation research: the definition of terms, such as validity, test bias, and test fairness; sample size; the adverse impact of employment tests; and the legal responsibilities of test users. Strategies of concurrent validation, validity generalization, synthetic validation, and latent trait theory are discussed. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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Bem (1981a) used median splits on her Masculinity (M) and Femininity (F) scales to classify individuals into four sex role groups. Recently, Larsen and Seidman (1986) recommended performing separate factor analyses on the sex-typed subjects (high M–low F plus low M–high F) and non-sex-typed subjects (high M–high F plus low M–low F). For the sex-typed group, the authors found that (a) bipolar factors emerged, with M-scale items at one end and F-scale items at the other, and (b) the M and F scales correlated negatively (–.72). For the non-sex-typed group, they found that (a) unipolar factors emerged, with M- and F-scale items both loading positively, and (b) the M and F scales correlated positively (.73). Larsen and Seidman interpreted these results as supporting the use of the M and F scales for measuring gender schemas. However, all of their findings are an artifact of their selection process and, therefore, cannot be used to support the M and F scales or gender-schema theory. In particular, one cannot draw conclusions about the cognitive processing of individuals on the basis of the correlation of traits in a sample. Larsen and Seidman also found higher correlations between the M and F scales and biological sex in the sex-typed group. This finding is explained in the context of the interpersonal circumplex. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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Identifies and discusses some subtle experimental artifacts that may be generated by common procedures for the selection of patients to serve as Ss in psychotherapy research. Clinical observations derived from a project investigating Time-Limited Dynamic Psychotherapy are used as examples of potential artifacts in both the recruitment and screening phases of the selection process. It is proposed that the activities of patient recruitment and screening ought to become separate foci of research attention in their own right, so that questions of extratherapeutic motives, expectancies, and role can be addressed more systematically than is possible with informal clinical observation. Investigators should eschew any avoidable intrusions upon the naturalistic help-seeking and help-giving activities of patients and therapists. It is concluded that there should be some attempt to standardize recruitment and screening activities across research projects and settings. (35 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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Russell Craig J.; Settoon Randall P.; McGrath Robert N.; Blanton A. Elyssa; Kidwell Roland E.; Lohrke Franz T.; Scifres Elton L.; Danforth George W. 《Canadian Metallurgical Quarterly》1994,79(2):163
Surrogate measures of original authors' reward context, primary motivation for doing the research, and knowledge, skills, and abilities (KSAs) were examined for their affect on criterion-related validities reported in the Journal of Applied Psychology and Personnel Psychology between 1964 and 1992. Number of years of experience (a surrogate KSA measure) displayed no moderating relationship. Type of organizational need (equal employment opportunity compliance, augmenting existing selection system, etc.) and investigator interests (e.g., theory testing) were related to criterion-related validities. Place of authors' employment (i.e., reward context) also displayed a moderating relationship (authors in private industry reported higher average validities in comparison with academics). Interaction effects on criterion-related validities were found between authors' experience and (1) place of employment and (2) primary motivation for conducting the research. Results are interpreted in view of possible differences in ability, motivation, and opportunity to do research across employment settings. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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宝钢3号高炉高煤比条件下的高利用系数生产研究 总被引:4,自引:0,他引:4
宝钢3号高炉通过技术创新和开发,不断完善操作技术水平,改善原燃料条件,1999年在维持煤比200kg/t以上的同时,实现年均利用系数2.303,2000年高炉利用系数再创新高,月均最高达到2.145,宝钢高煤比高利用系数冶炼技术达到世界领水平。 相似文献
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Examined 13 research studies dealing with differences between negroes and caucasians in the validity of employment and training selection procedures. It was found that 100 of the 160 validity coefficients computed were not significant for either group, indicating the need for validation prior to operational use. Significant differences in the coefficients between groups were found only in 7 instances. Statistical significance of single group validity occurred in 33 instances. The combination of ethnic groups yielded lower validity than for either group separately on only 3 out of 120 instances. It is concluded that there is very little evidence of differential validity. Single-group validity appears linked to the use of ratings (rather than more objective criterion measures), and small samples. (25 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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BH Brandt A Beckmann F Gebhardt A R?tger C Jackisch G Assmann KS Z?nker 《Canadian Metallurgical Quarterly》1997,118(2):143-151
Effect of indirect moxibustion stimulation on mouse skin was studied by thermal qualitative, biochemical, and histological methods. The maximum temperature change by indirect moxibustion was about 65 degrees C on the skin, and 45 degrees C in the subcutaneous layer. The treatment of indirect moxibustion was found to be associated with the decrease of lipid peroxidation and increase of superoxide dismutase (SOD) in the skin. Histological findings after indirect moxibustion showed an increase in the number of hair mother cells and hypertropy of the cells. 相似文献