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排序方式: 共有791条查询结果,搜索用时 15 毫秒
61.
Tokar David M.; Withrow Jason R.; Hall Rosalie J.; Moradi Bonnie 《Canadian Metallurgical Quarterly》2003,50(1):3
Structural equation modeling was used to test theoretically based models in which psychological separation and attachment security variables were related to career indecision and those relations were mediated through vocational self-concept crystallization. In contrast to previous studies, which have found either weak or no support for a relation between separation or attachment security variables and career indecision, results based on a sample of 350 college students indicated that some components of separation and attachment security did relate to career indecision in a theoretically supportable direction. Results also revealed that regardless of whether global or component career indecision measures were used, separation and attachment security effects on indecision were at least partially mediated through vocational self-concept crystallization. The strongest mediated relations were observed for the effects of attachment anxiety and maternal separation. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
62.
A novel voltammetric sensor based on chemically modified bentonite–porphyrin carbon paste electrode (MBPCE) has been introduced for the determination of trace amount of Mn(II) in wheat flour, wheat rice and vegetables. In this method Mn(II) gives well-defined voltammetric peak at the pH range of 3.5–7.5. For the preliminary screening purpose, the catalyst was prepared by modification of bentonite with porphyrin and characterized by thermogravimetric method (TG) and UV–vis spectroscopy. The detection limit (three times signal-to-noise) with 4 min accumulation is 1.07 × 10−7 mol L−1 Mn(II). The peak currents increases linearly with Mn(II) concentration over the range of 6.0 × 10−7 to 5.0 × 10−4 mol L−1 (r2 = 0.9959). Statistical treatment of the results gave a relative standard deviation lower than 2.30%. The chemical and instrumental parameters have been optimized and the results showed that 1000-fold excess of the additive ions had not interferences on the determination of Mn(II). 相似文献
63.
64.
This paper presents sliding mode control and model reference adaptive control strategies for the tape transport mechanism. A nonlinear multivariable MIMO model of the process, consisting of take-up and supply reel servos for tape tension control and capstan servo for speed control is considered. The sliding mode control is applied for the nonlinear dynamic model of the process, while the model reference adaptive control deals with the linearized one. Moreover, in order to associate with the realistic model of system, design of controllers is accomplished with respect to parametric uncertainties. It is shown that both control strategies can guarantee asymptotic stability of the closed-loop system and tracking of desired outputs with the appropriate pace in the presence of uncertainties. Finally, simulation results demonstrate the effectiveness of the proposed controllers. 相似文献
65.
Keyhan Rahmani Iraj Mahdavi Hadi Moradi Hamid Khorshidian Maghsud Solimanpur 《The International Journal of Advanced Manufacturing Technology》2011,55(9-12):1135-1147
Motivated by just-in-time (JIT) manufacturing, we study the bi-objective scheduling problem of minimizing the total weighted earliness and the number of tardy jobs on a single machine, in which machine idle time and preemption are allowed. The problem is known to be NP-hard. In this paper, we propose a new mathematical model, with nonlinear terms and integer variables which cannot be solved efficiently for medium- and large-sized problems. A method combining the new ranked-based roulette wheel selection algorithm with Pareto-based population ranking algorithm, named nondominated ranking genetic algorithm (NRGA), has been presented to find nondominated solutions in a reasonable time. Various operators and parameters of the proposed algorithm are reviewed to calibrate the algorithm by means of the Taguchi method. A number of numerical examples are solved to demonstrate the effectiveness of the proposed approach. The solutions obtained via NRGA are compared against solutions obtained via ε-constraint method in small-sized problems. Experimental results show that the proposed NRGA is competitive in terms of the quality and diversity of solutions in medium- and large-sized problems. 相似文献
66.
Falling rock hazard index: a case study from the Marun Dam and power plant, south-western Iran 总被引:1,自引:0,他引:1
Mehran Koleini Jan Louis Van Rooy 《Bulletin of Engineering Geology and the Environment》2011,70(2):279-290
Rock fall phenomena are a major hazard during construction in mountainous regions. At the Marun Dam site, rock falls occur almost every day on the downstream side. The left flank power plant and access roadways as well as the right flank roadways are susceptible to rock falls from the 100?m high cliffs with slopes of 70??0°. The cause is a combination of the orientation of the bedding planes and joint sets and the active tectonic setting of the area. The paper reports the use of RocFall and Dips software to simulate the conditions in order to define the potential risk of rock falls at the Marun Dam site, which could affect workers as well as structures. In the light of the Falling Rock Hazard Index obtained, preventative and remedial measures are suggested. 相似文献
67.
Pejman Mehran Kudret Demirli 《The International Journal of Advanced Manufacturing Technology》2013,67(5-8):1113-1125
This paper describes an automated machine vision-based inspection method for fast and accurate detection of broken edges on the machined surface of water pumps which are formed during casting. The paper proposes a collection of steps to inspect images taken in a noisy environment to identify broken edges. By developing three broken edge verification features and using fuzzy C-means clustering, we provide a fuzzy broken edge inspection model that classifies water pumps into three classes: pumps with significant (major) broken edges, pumps with insignificant (minor) broken edges, and pumps with no broken edges. The devised machine vision-based inspection method is efficient in terms of processing time and accuracy to recognize the parts with broken edges and to make decisions consistent with human knowledge. The fuzzy broken edge detection was carried out on a database of 150 gray-level images. The developed method properly identifies about 95 % of the broken edges in the entire database. 相似文献
68.
HISTORICALLY superalloys have been used in gasturbine applications with a protective coating to combatoxidation problems in aero engines and hot corrosionproblems in industrial and marine engines.Theprotective coatings used are predominantly of thediffusion type produced by variety of techniques suchas pack cementation,chemical vapor deposition,slurryfusion and hot dipping[1,2].The purpose of this typeof coatings is to increase the amount of Al at thesurface of a component,so that a protec… 相似文献
69.
HT Neshat-Doost MR Taghavi AR Moradi W Yule T Dalgleish 《Canadian Metallurgical Quarterly》1998,107(4):642-650
An experiment was conducted to examine memory for emotional trait adjectives in depressed children and adolescents. Two groups of children and adolescents, clinically depressed participants and non-clinical controls, were compared on computerized versions of recall and recognition memory tasks. Three groups of words (positive trait adjectives, negative trait adjectives, and categorized neutral words) were used in the experiment. Results showed that the depressed group recalled significantly more negative adjectives than positive adjectives, whereas the control group recalled the same number of positive and negative adjectives. This effect was predicted by the association between age and level of depression, with the depression-related bias becoming stronger with age. Signal detection analysis revealed that the depressed group did not show any bias in the recognition task. The findings are discussed with respect to cognitive theories of depression with consideration of the developmental implications. 相似文献
70.
Krishna N. Vinod Christian A. Zorman Azzam A. Yasseen Mehran Mehregany 《Journal of Electronic Materials》1998,27(3):L17-L20
This paper reports on a process to fabricate single-crystal 3C-SiC on SiO2 structures using a wafer bonding technique. The process uses the bonding of two polished polysilicon surfaces as a means
to transfer a heteroepitaxial 3C-SiC film grown on a Si wafer to a thermally oxidized Si wafer. Transfer yields of up to 80%
for 4 inch diameter 3C-SiC films have been achieved. Homoepitaxial 3C-SiC films grown on the 3C-SiC on SiO2 structures have a much lower defect density than conventional 3C-SiC on Si films. 相似文献