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21.
Tahui Wang Chimoon Huang Chou P.C. Chung S.S.-S. Tse-En Chang 《Electron Devices, IEEE Transactions on》1994,41(9):1618-1622
A two-dimensional numerical simulation including a new interface state generation model has been developed to study the performance variation of a LDD MOSFET after a dc voltage stress. The spatial distribution of hot carrier induced interface states is calculated with a breaking silicon-hydrogen bond model. Mobility degradation and reduction of conduction charge due to interface traps are considered. A 0.6 μm LDD MOSFET was fabricated. The drain current degradation and the substrate current variation after a stress were characterized to compare the simulation. A reduction of the substrate current at Vg ≃0.5 Vd in a stressed device was observed from both the measurement and the simulation. Our study reveals that the reduction is attributed to a distance between a maximum channel electric field and generated interface states 相似文献
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基于媒体用户访问行为偏好模型的代理缓存算法 总被引:2,自引:0,他引:2
目前,代理缓存技术广泛应用于改善流媒体传输的服务质量.文章从实际用户日志文件的分析出发,利用发现的用户浏览流媒体对象时的行为分布模型,提出了一种新的视频流媒体缓存算法.仿真结果证明,该算法可以通过记录很少的用户访问信息获取较高的性能表现. 相似文献
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A wireless/mobile network supporting multilevel quality of service (QoS) is considered. In such a network, users or applications can tolerate a certain degree of QoS degradation. Bandwidth allocation to users can, therefore, be adjusted dynamically according to the underlying network condition so as to increase bandwidth utilization and service provider's revenue. However, arbitrary QoS degradation may be unsatisfactory or unacceptable to the users, hence resulting in their subsequent defection. Instead of only focusing on bandwidth utilization or blocking/dropping probability, two new user-perceived QoS metrics, degradation ratio and upgrade/degrade frequency, are proposed. A Markov model is then provided to derive these QoS metrics. Using this model, we evaluate the effects of adaptive bandwidth allocation on user-perceived QoS and show the existence of trade offs between system performance and user-perceived QoS. We also show how to exploit adaptive bandwidth allocation to increase system utilization (for the system administrator) with controlled QoS degradation (for the users). By considering various mobility patterns, the simulation results are shown to match our analytical results, demonstrating the applicability of our analytical model to more general cases. 相似文献
24.
Shang-Ching Chou 《Journal of Automated Reasoning》1988,4(3):237-267
Wu's algebraic method for mechanically proving geometry theorems is presented at a level as elementary as possible with sufficient examples for further understanding the complete method.The work reported here was supported by NSF Grant DCR-8503498. 相似文献
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Risks always exist in construction projects and often cause schedule delay or cost overrun. Risk management is a key issue in project management. The first step of risk management is risk identification. It includes the recognition of potential risk event conditions in the project and the clarification of risk responsibilities. We conducted multiple-case studies using a systematic analytical procedure to identify risks in highway projects in Taiwan, to recognize risk allocation by contract clauses, and to analyze the influence of risk allocation on the contractor’s risk handling strategies. The results show that the owner allocates risks by stipulating specific contract clauses into five kinds of risk allocation conditions. If a risk is more controllable by the contractor, the owner has a greater tendency to allocate the risk to the contractor. Risk allocation determines which kinds of risks the contractor would take and influences the contractor’s risk handling decisions. The analysis furthermore indicates that, if the probability of a certain risk event condition is uncontrollable, then with the increasing possibility of taking the risk, the contractor’s tendency of risk handling changes from actively transferring the risk to passively retaining the risk. In contrast, if a risk is controllable and certainly allocated to the contractor, the contractor tends to take the initiative to reduce the impact caused by the risk event rather than retain the risk. 相似文献
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Young-Huang Chou Shew-Jon Lin Shyh-Jong Chung 《Vehicular Technology, IEEE Transactions on》2002,51(1):194-199
In this paper, grating metal structures with broad and flat back-scattering field patterns are studied for possible applications in a vehicle collision avoidance system. The two-dimensional TE scattering of a planar grating structure and a curved grating structure are analyzed at a frequency of 77 GHz. For the planar structure, the method of moments and Floquet's theorem are used to solve the induced current and the resultant back-scattering field. Based on the results of the planar structure, the scattering field of the curved grating structure is obtained by using a perturbation method. The influence on the field pattern of the curvature as well as other structure parameters, such as the width and geometry of each period in the grating structure, is investigated 相似文献