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991.
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993.
It is well known that angles in composite parts contract as they are cooled down from the curing temperature, this is often referred to as spring-in. It is caused mainly by the significantly different thermal contractions and cure shrinkage's experienced between the fibre direction and the through-thickness direction during the manufacturing process. A number of works have reported on the spring-in of straight angle composite parts. However, little has been done to investigate the distortion of curved flanged composite parts, which will distort differently owing to the introduction of the additional curvature, thus constraint.

In the present work, the distortion of the circularly curved flanged laminates is studied numerically. The finite element method is used to predict the processing-induced distortion of the part with two different approaches. In the first approach, the shear angles of the composite plies are predicted by a draping analysis. The effect of the fibre shearing on the mechanical properties of the laminates is considered in the model used to predict the distortion. The second simplified approach assumes that the in-plane properties of the laminates are isotropic. The results obtained by these two approaches are compared with those obtained experimentally.  相似文献   

994.
We report on improvements in the overall intensity of a sputter ion source that evolved originally from an NEC MCSNICS. Beam output increases benefit both AMS measurements and nuclear physics experiments using low natural abundance beams. In particular, minor changes in source geometry suggested by a combination of electrostatic calculations and simple design principles have yielded increases in extracted negative ion intensity of nearly a factor of 4.  相似文献   
995.
Molecular electronics seeks to build electrical devices to implement computation - logic and memory - using individual or small collections of molecules. These devices have the potential to reduce device size and fabrication costs, by several orders of magnitude, relative to conventional CMOS. However, the construction of a practical molecular computer will require the molecular switches and their related interconnect technologies to behave as large-scale diverse logic, with input/output wires scaled to molecular dimensions. It is unclear whether it is necessary or even. possible to control the precise regular placement and interconnection of these diminutive molecular systems. This paper describes genetic algorithm-based simulations of molecular device structures in a nanocell where placement and connectivity of the internal molecular switches are not specifically directed and the internal topology is generally disordered. With some simplifying assumptions, these results show that it is possible to use easily fabricated nanocells as logic devices by setting the internal molecular switch states after the topological molecular assembly is complete. Simulated logic devices include an inverter, a NAND gate, an XOR gate and a 1-bit adder. Issues of defect and fault tolerance are addressed.  相似文献   
996.
用Calyculin A诱导的染色体凝聚研究辐射的剂量效应关系   总被引:1,自引:1,他引:0  
采用不同剂量(0,0.25,0.5,1.0,2.0,3.0Gy)的60Coγ射线照射离体人血,于照后46h加入CalyculinA,观察其诱导的染色体凝聚,并与常规染色体畸变法进行比较,结果表明,Calyculin A法PCC与常规秋水仙素阻滞法及融合法PCC相比可获得更高的分裂指数,Calyculin A法PCC的断片数与剂量之间呈良好的线性关系。  相似文献   
997.
On the basis of numerical model the parameters of high electron mobility transistors (HEMT’s) as a function of gate and drain voltages are obtained. The simulation of nonlinear properties of low noise amplifier cascade with HEMT for various modes of its operation has shown that the account of its dependence simultaneously on both the voltages allows to approach the results of calculation to experimental data.  相似文献   
998.
A Biologically-Parameterized Feather Model   总被引:1,自引:0,他引:1  
Feathers, unlike other cutaneous appendages such as hair, fur, or scales have a definite structure. Variation in feather structure creates a wide range of resulting appearances. Collectively, feather structure determines the appearance of the feather coat, which can largely affect the resulting look of a feathered object (bird). In this paper we define the structure of individual feathers using a parameterization based on biological structure and substructures of actual feathers. We show that our parameterization can generate a large variety of feathers at multiple levels of detail and provide an initial step to semi‐automatically generating a wide range of feather coats. his is achieved by specifying an intuitive interpolation between different structures and ages of feathers.  相似文献   
999.
Market segmentation has commonly applied cluster analysis. This study intends to make the comparison of conventional two-stage method with proposed two-stage method through the simulated data. The proposed two-stage method is the combination of self-organizing feature maps and K-means method. The simulation results show that the proposed scheme is better than the conventional two-stage method based on the rate of misclassification.  相似文献   
1000.
The intraneural ganglion of the peroneal nerve is a rare lesion. The differential diagnosis includes lesions of the knee especially the tendinopathia of the knee flexors. Clinical examination, electrophysiological investigations, ultrasound imaging and magnetic resonance tomography will establish the diagnosis. We report a case in which an artificial puncture of the ganglion caused a temporary peroneal palsy. Surgical procedure led to complete restoration of the nerve function.  相似文献   
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