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排序方式: 共有1319条查询结果,搜索用时 15 毫秒
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介绍了黄河上游龙青段主要环境工程地质问题的分析思路,以达到抛砖引玉,交流和提高电工程地质勘测水平的目的。 相似文献
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Xiang Lu S. Sundar Kumar Iyer Jin Lee Brian Doyle Zhineng Fan Paul K. Chu Chenming Hu Nathan W. Cheung 《Journal of Electronic Materials》1998,27(9):1059-1066
We have demonstrated feasibility to form silicon-on-insulator (SOI) substrates using plasma immersion ion implantation (PIII)
for both separation by implantation of oxygen and ion-cut. This high throughput technique can substantially lower the high
cost of SOI substrates due to the simpler implanter design as well as ease of maintenance. For separation by plasma implantation
of oxygen wafers, secondary ion mass spectrometry analysis and cross-sectional transmission electron micrographs show continuous
buried oxide formation under a single-crystal silicon overlayer with sharp Si/SiO2 interfaces after oxygen plasma implantation and high-temperature (1300°C) annealing. Ion-cut SOI wafer fabrication technique
is implemented for the first time using PIII. The hydrogen plasma can be optimized so that only one ion species is dominant
in concentration and there are minimal effects by other residual ions on the ion-cut process. The physical mechanism of hydrogen
induced silicon surface layer cleavage has been investigated. An ideal gas law model of the microcavity internal pressure
combined with a two-dimensional finite element fracture mechanics model is used to approximate the fracture driving force
which is sufficient to overcome the silicon fracture resistance. 相似文献
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许桂水 《武汉工业学院学报》1993,(4)
本广继[8]后讨论了K—调和映射的稳定性。作为其应用最后得出了当N具常数截面曲率时,稳定2、3—调和映射的几个不存在定理。 相似文献
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报道了一种新型高灵敏浸没型HgCdTe红外探测器的研制,获得了D^*=1.46×10^11cmHz^1/2W^-1,R=608V/W,λc(20%)-20μ,灵敏元面积A=0.12×0.12mm^2,和有效通光孔径ψ=6mm的浸没型器件。 相似文献
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Zr41.5Ti14Cu13Ni10Be22.5大块非晶的耐蚀性能 总被引:3,自引:0,他引:3
秦秀娟 《腐蚀科学与防护技术》2003,15(1):52-53
用浸泡法研究了ZrTiCuNiBe大块非晶合金在酸、碱、
盐各种腐蚀性介质中的腐蚀行为.并与典型材料做了比较,结果表明:ZrTiCuNiBe大块非晶合金具有良好的耐蚀性. 相似文献
10.
Computational Problem Solving in Spatial Substrates -- A Cognitive Systems Engineering Approach
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Christian Freksa 《International Journal of Software and Informatics》2015,9(2):279-288
The ability to perform spatial tasks is crucial for everyday life and of great importance to cognitive agents such as humans, animals, and autonomous robots. A common artificial intelligence approach to accomplish spatial tasks is to represent spatial configurations and tasks in form of detailed knowledge about various aspects of space and
time. Suitable algorithms then use the representations to compute solutions to spatial problems. In comparison, natural embodied and situated agents often solve spatial tasks without detailed knowledge about geometric, topological, or mechanical laws; they directly relate actions to effects that are due to spatio-temporal affordances in their bodies and environments. Accordingly, we propose a paradigm that makes the spatio-temporal
substrate an integral part of the engine that drives spatial problem solving. We argue that spatial and temporal structures in body and environment can substantially support (and even replace) reasoning effort in computational processes: physical manipulation and perception in spatial environments substitute formal computation. While the approach is well known – for example, we employ diagrams as spatial substrate for geometric problem solving and maps for wayfinding – the underlying principle has not been systematically investigated or formally analyzed as a paradigm of cognitive processing. Topology, distance, and orientation constraints are all integrated and interdependent in truly 2- or 3-dimensional space. Exploiting this fact may not only help overcome the need for acquiring detailed knowledge about the interrelationships between different aspects of space; it also can point to a way of avoiding exploding computational complexity that occurs when we deal with these aspects of space in complex real-world scenarios. Our approach employs affordance-based object-level problem solving to complement knowledge-level formal approaches. We will assess strengths and weaknesses of the new cognitive systems paradigm. 相似文献