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991.
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The optimal lamination arrangements of laminated composite plates with maximum stiffness subject to side constraints are investigated via a constrained multi-start global optimization approach. In the optimal design process, the deformation analysis of laminated composite plates is accomplished by utilizing a shear deformable laminated composite finite element and the optimal design problem, which has been converted into an unconstrained minimization problem via the general augmented Lagrangian method, is solved by utilizing the proposed unconstrained multi-start global optimization technique to determine the optimal fiber angles and layer group thicknesses of the laminated composite plates for attaining maximum stiffness and simultaneously satisfying the imposed side constraints. The feasibility of the proposed constrained multi-start global optimization algorithm is validated by means of a simple but representative example and its applications are demonstrated by means of a number of examples on the maximum stiffness design of symmetrically laminated composite plates. The effects of length-to-thickness ratio, aspect ratio, and number of layer groups upon the optimum fiber angles and layer group thicknesses of the plates are investigated. 相似文献
994.
调查了攀钢1号,2号烧结机密封设备的磨损变形情况;系统测定了2号烧结机中修前后各部位的漏风情况;分析了风率高的原因,提出了降低漏风率的主要措施。在1号,3号烧结机头尾风箱安装重锤式密封装置及篦塞加工方法后,漏风率均降低了5.44%。 相似文献
995.
Using handhelds in a Jigsaw cooperative learning environment 总被引:1,自引:0,他引:1
Abstract This paper reports our implementation of a handheld wireless environment to support Jigsaw cooperative learning activities in a college setting. A quasi-experimental research design was conducted to investigate the effects of using handhelds, as well as issues associated with the use of handheld technology. Two intact classes of fourth-year students from a five-year junior nursing college participated in the experiment. Our findings showed that handheld tools enhanced both students' attitudes and performance in learning, and promoted better interactions among students and instructors. We also found that the handheld technology was not sophisticated enough to support cooperative learning goals without full support from a technology specialist. 相似文献
996.
A systematic method of adaptive joint design considering different assembly sequence in sheet metal product 总被引:1,自引:1,他引:0
Jun Cao Xinmin Lai Sun Jin Zhongqin Lin 《The International Journal of Advanced Manufacturing Technology》2007,34(5-6):457-463
In sheet metal assembly, not only the component variations and tool errors, but also the component structure (joint type)
and assembly process (assembly sequence) affect the final dimensional quality. In this paper, a systematic method for adaptive
joint design considering different assembly sequence is proposed to meet the in-process dimensional adjustability of KCs (key
characteristics). First, the adaptive characteristic of the sheet metal joint is depicted. Then, the mathematical model in
order for concurrently optimizing both joint type and different assembly sequence is presented. How to evaluate the combination
of joint type and assembly sequence is carried out according to two conditions: (1) for single KC, and (2) for multiple KCs.
The KC confliction is considered to ensure the important KCs. Genetic algorithm is used to resolve the optimization of joint
design. An example is chosen to demonstrate our method finally, and various joint designs are acquired according to different
assembly sequences by this means. The proposed methods make it possible for us to improve the dimensional quality of product
in the design stage. 相似文献
997.
998.
Gao-Chao Lai Masao Takahashi Kohji Nobugai Fumikazu Kanamaru 《Journal of the American Ceramic Society》1989,72(12):2310-2313
Solid-solution thin films, Mo1−x Nbx N, with B1 (NaCl) structure have been deposited on substrates at 450°C by reactive sputtering of composite targets with Mo and Nb metals in an equimolar Ar and N2 gas mixture. The lattice parameter of the solid solution increased linearly with an increase of Nb content, x . The superconducting transition temperature, T c , of the Mo-rich films ( x ≦ 0.12) was around 6 K, which was lower than that expected from theoretical prediction. The residual resistivity ratio, r =ρ(300 K)/ρ(20 K), of the films varied with x , and a minimum value of r was observed in the vicinity of x = 0.5. 相似文献
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1000.