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排序方式: 共有4674条查询结果,搜索用时 31 毫秒
991.
Gab Seon Rho Kyeong-hoon Koo Naehyuck Chang Jaehyun Park Yeong-gi Kim Wook Hyun Kwon 《Microprocessors and Microsystems》1995,19(10):599-608
A special purpose RISC (reduced instruction set computer) microprocessor for programmable logic controllers (PLC), named PLCRISC, is proposed. To develop an optimal PLCRISC, we analysed existing PLC programs currently used in factories, with special attention to the instruction execution characteristics and features required for a high performance PLC processor. Based on this analysis, an optimal RISC-style instruction set and an architecture suitable for the required features are suggested. In particular, the instruction format, the instruction pipeline, and the detailed internal architecture are the significant characteristics of the proposed PLCRISC. The performance enhancement achieved with a PLCRISC is seen from a straightforward evaluation. ASIC implementation with VHDL is also discussed. The PLCRISC is under fabrication in a 0.8 μm CMOS technology. 相似文献
992.
Removal of hot spot speckle on rear projection screen using the rotating screen system 总被引:1,自引:0,他引:1
Sung Chul Shin Sin Sung Yoo Sang Yeon Lee Chan-Young Park So-Yeon Park Jae Wook Kwon Seung-Gyu Lee 《Display Technology, Journal of》2006,2(1):79-84
This paper investigates a method to remove hot spot speckle, which is produced by laser-long coherence, on a projection screen. The objective of the work has been to first create an image from a digital light processing (DLP) display system using an RGB laser source. We then successfully obtained a high-quality image with speckle contrast, which is less than 2% when the screen was rotated by piezoelectric motor. 相似文献
993.
The LQG/LTR (linear quadratic Gaussian/loop transfer recovery) method is discussed, along with related frequency-domain properties for linear systems with delay in state. Based on the frequency-domain inequality and a robust stability condition, the guaranteed stability margin of LQ regulators and the guaranteed nondivergence margin of Kalman filters are obtained. To improve the robustness of LQG regulators, the asymptotic property of the filter gain is investigated and a loop-transfer recovery procedure is suggested with an illustration 相似文献
994.
The diffusion of zinc into GaAs, Al0.3Ga0.7As and Al0.3Ga0.7As/GaAs single heterostructures have been studied. The depth of the diffusion front is found to be proportional to the square
root of the diffusion time, [t]1/2, and for single heterostructures the Al0.3Ga0.7As layer thickness,d
1 modifies this relationship through decreasing the junction depth byd
1 multiplied by a constant. It is shown that this relationship can be used for predicting diffusion fronts in double heterostructures. 相似文献
995.
996.
Suk Myung-Jin Choi Sung-II Kim Ji-Soon Kim Young Do Kwon Young-Soon 《Metals and Materials International》2003,9(6):599-603
A porous structure with a porosity gradient can be applied to the preparation of continuous FGM, where liquid or chemical
vapor of the second phase is infiltrated into the graded pores. It also has applications in skeletal implant materials and
ultrafiltration media. An attempt was made to fabricate a porous material with a porosity gradient by means of a pulsed electric
current sintering (PECS) process. The present work describes not only the measured value of the temperature difference between
the upper and lower part of the specimen, which brings about a gradual change in pore distribution, but also the sintering
characteristics of the porous structure obtained by the pressureless PECS process. 相似文献
997.
The Space Shuttle orbiter (SSO) Ku -band single access return (KSAR) link and the Space Station Freedom (SSF) KSAR link via the tracking and data relay satellite system (TDRSS) use the same carrier frequency. The interference between spacecraft is minimized by opposite antenna polarizations and by TDRSS antenna beam pointing, but if the SSF and SSO are in close proximity, it is expected that mutual interference will be significant. It is shown that a simplified analytical approach will yield adequate accuracy for the expected range of operating conditions. Relative degradation in bit-energy-to-thermal-noise power spectral density ratio to achieve a 10-5 coded bit-error probability is determined to be 4 dB for the Ku -band SSO-to-TDRS I-channel return link with a 4.5-dB effective signal-to-interference total power ratio (S /I ) when the Ku -band SSF-to-TDRS return link interferes. For the Ku -band SSF-to-TDRS return link, both analysis and simulation results yield a relative signal degradation of 0.4 dB at the effective S /I =21.6 dB 相似文献
998.
Bong-Hwan Kwon Myung-Joong Youn 《Automatic Control, IEEE Transactions on》1986,31(5):449-451
Optimization of linear time-invariant systems, using a given time-weighted quadratic performance index, is investigated for the prespecified closed-loop eigenvalues. The necessary conditions have simple forms and this algorithm gives a considerable amount of computational time savings compared to the previous algorithms [1]-[2]. 相似文献
999.
It is demonstrated that inherent constrained densification characteristics of the bimodal size distributed powders can be utilized to fabricate porous alpha alumina. Seeded boehmite was mixed with coarse alpha alumina particles to produce various compositions of bimodal mixtures. The densification behaviour of the mixtures was correlated with shrinkage and microstructural evolution. The mixtures sintered at 1200 °C contained more than 30% porosity and the mechanical strength of the mixtures was increased by 2–4 fold relative to the coarse particles alone with similar porosity (<5 MPa). © 1998 Chapman & Hall 相似文献
1000.
S. H. Yoon Y. W. Kwon L. A. Clawson 《Journal of Mechanical Science and Technology》1997,11(2):136-142
This study focuses on an experimental investigation of damage tolerance of the foam cored sandwich composite subjected to low energy impact. Tests are performed to correlate delamination length with failure loads and loss of damage tolerance of the sandwich composite. The impact force history is used to determine momentum imparted to the specimen, the work done on the specimen, and the kinetic energy in order to gain an understanding of the mechanisms involved in damage due to impact loading. 相似文献