共查询到20条相似文献，搜索用时 602 毫秒
1.
Since the optical lithography is reaching its mini- mal structure size limit, alternative lithography tech- niques in the sub-100 nm range should be developed. In recent years, some nontraditional patterning tech- nologies, such as imprint lithography, soft lithogra- phy , and others, with a potentially wider application in microdevice fabrication, have been explored [1-4]. In 1995, nanoimprint lithography (NIL) was pro- posed. NIL technology is a hot subject and a develop- ment trend in the… 相似文献
2.
扈新福 《中学英语园地(高三版)》2006,(10)
A large press conference(会议,商谈) is currently underway in Beijing, 1 part of the National People's Congress. China's environmental authority(官方) 2 that the Songhua River in northeast China is unlikely to suffer 3 water pollution this year. This announcement was made by the Minister of State Administration for Environmental Protection, Zhou Shengxian.The M inister said the conclusion4from test results by both Chi-nese and R ussian authorities.W ater in the Songhua R ive… 相似文献
3.
INTRODUCTIONChaoticmotionisacomplexnonlinearmo tion ,whoseorbitstrajectoryinthephaseplaneisverycomplexbutnotstochastic.Chaosplaysanimportantroleindynamicalsystemsandisap pliedinmanyfieldssuchasphysics ,chemistry,economics,andsoon (Heetal.,2 0 0 2 ;Tongeta… 相似文献
4.
5.
6.
* With the further exploitation of offshore oil fieldsin deep-water, studying deep-water jacket construc-tion technique is becoming increasingly vital. At pre-sent, offshore platforms are usually sustained by ajacket and the jacket is fixed on the sea floor withskirt piles. For the sake of enhancing the stiffness ofthe jacket, the method of fillingcementslurry into theannular gap between the sleeve of the jacket and theskirt piles is usually adopted to connect the jacket andthe skirt piles[1].… 相似文献
7.
lIntroductionTheflexiblemanulhcturingtechnology(FMT)originatedinUSAinthemid1960s',sincethenithasspreadtomanyothercountries.Duringthelastfewyears,theflexiblemanufacturingsystem(FMS)hasdemonstratednotonlypopularintheindustrializedcountries,butalsofindsitsap… 相似文献
8.
Totransmitthemultimediadataovertheinternet ,pre encodedvideobitstreamsarepreferablebecauseofthelimitofthenetworkbandwidth .Inmostcases ,theencodershouldknowthechannelcharacteristicsinad vanceandencodethemasparameters .Consequently ,theflexibilityisreduced .Theratecontrolisemployedtocontroltheoutputbitrateaccordingtonetworkcondi tions.Forwirelessnetworks ,theirbandwidthsaremuchmorelimitedthanwirenetworks.Soratecontrolbecomesespeciallyimportantfortransmittingmultimediaoverthewirelessdomains[1- … 相似文献
9.
The maintaining overheads of Distributed Hash Table (DHT) topology have recently received considerable attention.This paper presents a novel SHT (Session Heterogeneity Topology) model, in which DHT is reconstructed with session heterogeneity. SHT clusters nodes by means of session heterogeneity among nodes and selects the stable nodes as the participants of DHT. With an evolving process, this model gradually makes DHT stable and reliable. Therefore the high maintaining overheads for DHT are effectively controlled. Simulation with real traces of session distribution showed that the maintaining overheads are reduced dramatically and that the data availability is greatly improved. 相似文献
10.
Frame skipping in low bit video coding could significantly reduce the visual quality of reconstructed video. At the same time, if the complexity of the video sequence remains high for a long period, then driving up the long term average bit rate, the only resort of MPEG-4 Q2 rate control algorithm results in using a high quantization scale, which shows a poor visual quality of the reconstructed video. This paper analyzes the main causes of frame skipping in current MPEG-4 frame rate control scheme, and presents a new rate control algorithm based on the quadratic R-D model over a CBR channel. Key features of the present work are. 1) the bits allocated to each P-frame or B-frame are in proportion to its distance from the end of this GOP, i.e. more bits are allocated to the frames that are nearer to their reference Ⅰ -frame: 2) the target buffer level is changeable in the GOP, at the end of each GOP( five P-frames or B-frames), the target buffer level is linearly reduced from 1/2 to 1/4 of buffer size, to other frames, the target buffer level is set to 1/2 of buffer size: 3 ) a selective and judicious use of the reduced resolution mode, in addition to a modulation of the quantization scale parameter, is to control the average long term bit rate. Experimental results with different video sequences of varied complexity, encoded at low bit rates show better efficacy of the proposed algorithm than MPEG-4 Q2 rate control scheme, and the experimental results also show that the improved algorithm has significantly reduced the number of frame skipping, increased the overall PSNR, and improved the perceptual quality. 相似文献
11.
《Journal of moral education》2012,41(1):63-67
Abstract: Groups of twenty children, aged between 6 years, 7 months and 11 years, 3 months, attending either a traditional Catholic school or a Freinet school were compared on judgments involving moral concepts. Subjects in the two groups were matched for age, IQ, sex, school grade, religious affiliation, fathers’ occupational level, number of siblings and birth order. Moral conflict stories differed in the presence or absence of authority figures and peers, and were set either in the home or the school. Children attending the Freinet school exhibited the more advanced moral judgments for all stories combined. Stories involving peers only elicited more mature judgments than those involving authority figures. Freinet schools encourage democratic group self‐discipline and provide many and varied role‐taking opportunities. The results suggest that such practices accelerate moral development. 相似文献
12.
Thevibrationinducedbyiceisanimportantfactorofdamageforjacketplatforms ,sotheiceloadshavebeenthecontrolloadforjacketplatformsintheBohaiBay[1] .Toreducedamageinducedbytheiceforce ,theloadsstandardofjacketplatformshasbeenimproved .Infact ,thestrengthofjacketplatformsagainststaticiceforceismeteasily .But,thesafetyproblemoftheplatformaf fectedbyboththebehaviorsofself excitedandcouplingissolvedbyothertechnologysolutions[2— 3] .Xuetalde signedasetofdevicesforreducingvibrationofthejacketplatforminth… 相似文献
13.
Dynamic model and control strategy of parallel mechanism have always been a problem in robotics research. In this paper,different dynamics formulation methods are discussed first, A model of redundant driven parallel mechanism with a planar parallel manipulator is then constructed as an example. A nonlinear adaptive control method is introduced. Matrix pseudo-inversion is used to get a desired actuator torque from a desired end-effector coordinate while the feedback torque is directly calculated in the actuator space. This treatment avoids forward kinematics computation that is very difficult in a parallel mechanism. Experiments with PID together with the descibed adaptive control strategy were carried out for a planar parallel mechanism. The results show that the proposed adaptive controller outperforms conventional PID methods in tracking desired input at a high speed, 相似文献
14.
LUOJun LUTian－sheng 《上海大学学报(英文版)》2001,5(4):312-316
From a bionics viewpoint,this paper proposes a mechanical model of a wheeled snake-like mobile mechanism.On the hypothesis of the existing non-holonomic constraints on the robot kinematics,we set up the relationship among the kinetic control parameters in the snake-like movement using Lie group and Lie algebra of the principle fiber bundle and provide some theoretical control methods to realize the snake-like locomotion. 相似文献
15.
《中山大学学报论丛》1995,(3)
Irrigationisthelifebloodofagriculture,"ThisisoneofthefundamentalpolicieswhichChinagovermentformulatetodevelopagriculture.EachirrgationfacilityinChinahadproducedamarkedeffect.Itistheguaranteeforagricu1ture'scontinuousdevelopment.InsouthpartofChangjiang,almostallkindsofbankanddamezittwosortsoftermites,whichbuildlargenest,blackwingedtermitesandyellowwingedtermites,especiallytheformer.Blackwingedtermitesbuiltitsnestundertheground,varyindepthfrom1.0mto3.0m.Thesenestshaveonevitalnestandseverlvicen… 相似文献
16.
ＲｅｍｏｔｅＣｏｍｍｕｎｉｃａｔｉｏｎａｎｄＣｏｎｔｒｏｌｏｆａＲｏｂｏｔＵｓｉｎｇＭＭＳＤｉｎｇＸｉｎｑｕａｎ（丁心泉）（ＤｅｐａｒｔｍｅｎｔｏｆＣｏｍｐｕｔｅｒＳｃｉｅｎｃｅａｎｄＥｎｇｉｎｅｅｒｉｎｇ，ＳｏｕｔｈｅａｓｔＵｎｉｖｅｒｓｉｔｙ，... 相似文献
17.
梁宇 《重庆大学学报(英文版)》2005,4(1):6-8
1 Introduction 1 Semi-active suspension is advantaged by good performance and low price over the passive suspension and active suspension [1]. The control strategy as the core of a control system is widely researched in practice. The simple dynamic model is often adopted in the typical process. However, the differences between the practical and physical models bring on more idealization and less practicability. On the other hand, the mechanical designer and the controls designer use different… 相似文献
18.
李康顺 《赣南师范学院学报》2003,(6):66-67
在VISUALFOXPRO编程中使用网格控件显示表格时经常出现表格无数据或GRID表格突然变成一片空白等现象,就VISUALFOXPRO的GRID控件这一不完善问题作了分析并提出解决的方案. 相似文献
19.
Nowadays, the operation tasks and environmentof robotic manipulators have become more and moresophisticated, which requires that robotic manipula-tors possess more and more degrees of freedom(DOF) to offer greater dexterity and versatility. Thekinematic redundancy occurs when the DOF of a ma-nipulator is more than the minimum numberdemanded for executing a given task. The operationalperformance of manipulators may be greatly enhancedby utilizing the kinematic redundancy such as singu-larity … 相似文献
20.
INTRODUCTION The problem of minimal surface is an old and active problem in the field of differential geometry. The minimal surface has been employed in many areas such as architecture, material science, aviation, ship manufacture, biology, crystallogeny, and so on. The history of minimal surface began with La- grange in 1762 (Nitsche, 1989). Many literature on the minimal surface exist in the last two hundred years (Nitsche, 1989; Osserman, 1986), but few on the minimal surface from the… 相似文献