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11.
为了提高数控机床的加工精度和效率,在分析传统机床加工轮廓控制方案不足的基础上,提出了一种改进的NURBS曲线插补算法,该算法实现了基于S型速度曲线的加减速控制,并提出时间顺延法,加减速对称法等方法,合理解决了加减速点的预测问题,实现了在线实时自适应的加减速控制。 相似文献
12.
Protection against voltage dips is very important for transient stability in a Doubly Fed Induction Generator (DFIG). Conventional crowbar circuits have been used for protection of DFIGs; however, they may be insufficient in some transient situations. Therefore, the Low Voltage Ride Through (LVRT) capability was enhanced by a Demagnetization Current Controller (DCC) for the purpose of transient analysis. In addition, both stator and rotor circuit electromotive forces were modeled in a DFIG. The performances of the DFIG models with and without the DCC were compared. Modeling was carried out in a MATLAB/SIMULINK environment. A comparison of system behaviors was made between three-phase faults with and without a stator–rotor dynamic. Parameters for the DFIG including output voltage, speed, electrical torque variations and d–q axis rotor–stator current variations in addition to a 34.5 kV bus voltage were examined. It was found that in the DFIG model the system became stable in a short time when using the DCC. 相似文献
13.
Chandra Sekhar A. Durisety Rajagopal Vijayraghavan Lakshmipriya Seshan Syed K. Islam Benjamin J. Blalock 《Analog Integrated Circuits and Signal Processing》2006,48(2):143-150
This paper demonstrates a technique for controlling the electron emission of an array of field emitting vertically aligned
carbon nanofibers (VACNFs). An array of carbon nanofibers (CNF) is to be used as the source of electron beams for lithography
purposes. This tool is intended to replace the mask in the conventional photolithography process by controlling their charge
emission using the “Dose Control Circuitry” (DCC). The large variation in the charge emitted between CNFs grown in identical
conditions forced the controller design to be based on fixed dose rather than on fixed time. Compact digital control logic
has been designed for controlling the operation of DCC. This system has been implemented in a 0.5 μm CMOS process.
Chandra Sekhar A. Durisety received his B.E. (Hons.) Instrumentation from Birla Institute of Technology and Sciences, Pilani, India in 1997 and his
M.S in Electrical Engineering from University of Tennessee, Knoxville in 2002. Since 2003, he has been working towards his
Ph.D degree also in Electrical Engineering at Integrated Circuits and Systems Lab (ICASL), University of Tennessee, Knoxville.
He joined Wipro Infotech Ltd, Global R & D, Bangalore, India in 1997, where he designed FPGA based IPs for network routers.
Since 1999, he was involved in the PCI bridge implementation at CMOS chips Inc, Santa Clara, CA, and the test bench development
for Sony’s MP3 player, while at Toshiba America Electronic Components Inc., San Jose, CA. His research interests include multi-stage
amplifiers, data converters, circuits in SOI and Floating Gate Devices.
Rajagopal Vijayaraghavan received the B.E degree in electronics and communication engineering from Madras University in 1998 and the M.S degree in
electrical engineering from the University of Texas, Dallas in 2001.He is currently working towards the Ph.D degree in electrical
engineering at the University of Tennessee. His research interest is in the area of CMOS Analog and RF IC design. His current
research focuses on LNAs and VCOs using SOI based MESFET devices.
Lakshmipriya Seshan was born in Trivandrum, India on April 30, 1979. She received her B.tech in Electronincs & Communication Engg from Kerala
University, India in June 2000 and M.S in Electrical Engg from University of Tennessee in 2004. In 2004, she joined Intel
Corporation as an Analog Engineer, where she is engaged in the design of low power, high speed analog circuits for various
I/O interface topologies.
Syed K. Islam received his B.Sc. in Electrical and Electronic Engineering from Bangladesh University of Engineering and Technology (BUET)
and M.S. and Ph.D. in Electrical and Systems Engineering from the University of Connecticut. He is presently an Associate
Professor in the Department of Electrical and Computer Engineering at the University of Tennessee, Knoxville. Dr. Islam is
leading the research efforts of the Analog VLSI and Devices Laboratory at the University of Tennessee. His research interests
are design, modeling and fabrication of microelectronic/optoelectronic devices, molecular scale electronics and nanotechnology,
biomicroelectronics and monolithic sensors. Dr. Islam has numerous publications in technical journals and conference proceedings
in the areas of semiconductors devices and circuits.
Benjamin J. Blalock received his B.S. degree in electrical engineering from The University of Tennessee, Knoxville, in 1991 and the M.S. and
Ph.D. degrees, also in electrical engineering, from the Georgia Institute of Technology, Atlanta, in 1993 and 1996 respectively.
He is currently an Assistant Professor in the Department of Electrical and Computer Engineering at The University of Tennessee
where he directs the Integrated Circuits and Systems Laboratory (ICASL). His research focus there includes analog IC design
for extreme environments (both wide temperature and radiation immune), multi-gate transistors and circuits on SOI, body-driven
circuit techniques for ultra low-voltage analog, mixed-signal/mixed-voltage circuit design for systems-on-a-chip, and bio-microelectronics.
Dr. Blalock has co-authored over 60 published refereed papers. He has also worked as an analog IC design consultant for Cypress
Semiconductor Corp. and Concorde Microsystems Inc. 相似文献
14.
中海油东方石化有限责任公司催化裂解汽油苯含量较高,受加工流程限制,通过调整装置操作参数以降低汽油苯含量。简述了催化裂解汽油中苯的生成机理,汽油中的苯主要来自芳烃的侧链裂解反应、环烷烃的氢转移反应和烯烃的环化脱氢反应;分析了催化裂解装置原料性质、操作条件及催化剂性质对汽油苯含量的影响,通过操作参数的调整,使催化裂解汽油苯体积分数由1.60%降至1.40%。将降低汽油苯含量的的理论成功应用于生产实践,取得良好的应用效果。 相似文献
15.
Natarajan Madhusudhanan Rajamanickam Venkateswari 《International Journal of Communication Systems》2020,33(4)
Outage analysis plays a vital role in wireless systems to determine reliable transmission and effective communication. Incremental hybrid decode‐amplify‐forward (IHDAF) relay offers a way of meeting the challenges of capacity and coverage improvement with great potential in cooperative communication networks. Therefore, opportunistic incremental hybrid relaying must be integrated with coding schemes to achieve full diversity. In this paper, the outage behavior of polar coded and distributed coded cooperative relaying schemes is analyzed. Simulation results show that opportunistic incremental HDAF using polar code offers an outage capacity of 17 b/s/Hz for 4 × 4 multiantenna and 45 b/s/Hz in 8 × 8 multiantenna systems with an outage of 10?8 and 10?13, respectively. Moreover, the polar coded opportunistic IHDAF system in 8 × 8 MIMO achieves 2 and 6 dB higher gains compared with amplify‐and‐forward (AF) and decode‐and‐forward (DF) relaying schemes. The closed‐form expression for outage probability has been derived through Marcum‐Q approximations and processed through Monte Carlo simulations. 相似文献
16.
17.
《Journal of the European Ceramic Society》2017,37(3):891-897
Dense silicon carbide ceramics using chemical treated powder by DCC via dispersant reaction method and liquid phase sintering was reported. Ammonium peroxydisulfate ((NH4)2S2O8) and ammonium carbonate ((NH4)2CO3) were used as acid and base solutions to treat the silicon carbide powder, respectively. Influence of silicon carbide powder with chemical treatment on the preparation of silicon carbide suspension was studied. It was indicated that 50 vol% and 52 vol% silicon carbide suspensions with viscosities of 0.71 Pa s and 0.80 Pa s could be prepared using acid and base treated powders. Influence of silicon carbide powder with chemical treatment on the coagulation process and properties of green bodies and sintered ceramics were studied. It was indicated that silicon carbide green bodies with compressive strength of 1.13 MPa could be prepared using base treated powder. Dense silicon carbide ceramics with relative density above 99.3% and flexural strength of 697 ± 30 MPa had been prepared by DCC via dispersant reaction and liquid phase sintering using Al2O3 and Y2O3 as additives at 1950 °C for 2 h. 相似文献
18.
分别考察了常规条件下和微波合成条件下,碘催化法合成7-(2-甲基-3-丁炔-2-氧基)-香豆素的研究.实验结果表明,微波合成法不仅大大缩短了反应时间,还节省了昂贵原料3-氯-3-甲基-1-丁炔的用量,是合成该产物较优的合成方法.此外,还对比考察了Mitsunobu成醚法与碘催化法合成目标产物,并对二者的反应历程进行了探讨,对DCC法合成进行了尝试. 相似文献
19.
介绍了一种应用QJ55型直流比较仪电桥(改进型)测量高精度的空气电阻的方法。利用改进型QJ55直流电流比较仪电桥的现有高阻线路对高精度空气电阻的测量进行了分析和试验。从电桥原理入手,分析了对新型的精密空气电阻进行测量的可行性,并用实验进行了证实,根据现有电路特点对现有的接线方式进行了计算,并用数据证明了分析和计算的准确可靠。结果表明,此方法可以在不改变现有实验设备情况下测量出高精度的空气电阻值,提高标准设备的应用范围,扩展标准器本身的功能。 相似文献
20.
通过HCC、DCC、TMP、CPP四种增产丙烯工艺的方案对比,阐明了各种工艺的优缺点及原料的适应性。指出通过FCC家族工艺增产丙烯将成为石化企业新的效益增长点。 相似文献