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11.
12.
The influence of the specimen thickness B and the ligament length b on the J
R
-curves is numerically investigated for CT specimens. The thickness effect is taken into account with 2-D analyses by dividing a plain sided specimen into a plane stress part and a plane strain part. The fracture process is controlled by experimentally determined critical values of the crack tip opening displacement for crack growth initiation (CTODi) and the crack tip opening angle for stable crack growth (CTOAC). It is shown that for the global behaviour of a plain sided specimen, the B/b ratio is essential. The difference between the geometry dependence of the initiation value of the J-integral and the geometry dependence of the slope of the J
R
-curves is also shown. 相似文献
13.
Jyh-Ming Wang Sung-Chuan Fang Wu-Shiung Feng 《Solid-State Circuits, IEEE Journal of》1994,29(7):780-786
Two new methods are proposed to implement the exclusive-OR and exclusive-NOR functions on the transistor level. The first method uses non-complementary signal inputs and the least number of transistors. The other one improves the performance of the prior method but two more transistors are utilized. Both of them have been fully simulated by HSPICE on a SUN SPARC 2 workstation 相似文献
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15.
A powerful concept to cope with resource limitations and information redundancy in wireless sensor networks is the use of collaboration groups to distill information within the network and suppress unnecessary activities. When the phenomena to be monitored have large geographical extents, it is not obvious how to define these collaboration groups. This article presents the application of geometric duality to form such groups for sensor selection and non-local phenomena tracking. Using a dual-space transformation, which maps a non-local phenomenon (e.g., the edge of a half-plane shadow) to a single point in the dual space and maps locations of distributed sensor nodes to a set of lines that partitions the dual space, one can turn off the majority of the sensors to achieve resource preservation without losing detection and tracking accuracy. Since the group so defined may consist of nodes that are far away in physical space, we propose a hierarchical architecture that uses a small number of computationally powerful nodes and a massive number of power constrained motes. By taking advantage of the continuity of physical phenomena and the duality principle, we can greatly reduce the power consumption in non-local phenomena tracking and extend the lifetime of the network. 相似文献
16.
It is demonstrated for the first time that long nanowires with radii as small as 30 nm can be manufactured with a conventional coupler fabrication rig. The temporal deterioration of nanowire optical properties has been studied and correlated with its mechanical behaviour. The original transmission properties have been restored by a post-fabrication treatment. 相似文献
17.
介绍了平煤集团围绕以人为本的理念开展的提升理念、创新管理、加大投入和提高员工素质等一系列安全活动,为进一步抓好安全生产打下了坚实基础。 相似文献
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19.
港口起重机风灾事故的防范 总被引:1,自引:0,他引:1
介绍了港口起重机所受风害的种类及其设防情况,分析了起重机结构形式与风作用的关系。介绍了上海国际港务(集团)有限公司几种常用的大型起重机防风装置的原理、功效及检测情况。 相似文献
20.
Ahmari D.A. Fresina M.T. Hartmann Q.J. Barlage D.W. Mares P.J. Feng M. Stillman G.E. 《Electron Device Letters, IEEE》1996,17(5):226-228
A self-aligned InGaP/GaAs heterojunction bipolar transistor with a compositionally graded InxGa1-xAs base has been demonstrated with fT=83 GHz and fmax=197 GHz. To our knowledge, these results are the highest reported for both parameters in InGaP/GaAs HBT's. The graded base, which improves electron transport through the base, results in a DC current gain and a cutoff frequency which are 100% and 20% higher, respectively, than that achieved by an identical device with a nongraded base. The high fmax results from a heavily doped base, self-aligned base contacts, and a self-aligned collector etch. These results demonstrate the applicability of InGaP/GaAs HBT's in high-speed microwave applications 相似文献