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固定阴极电化学射孔的成型规律研究 总被引：1，自引：0，他引：1
根据电场理论,提出了一种研究固定阴极电化学射孔成型规律的更为严密的处理方法, 且基于这种思路分析了该加工方式下阴极表面电荷密度及加工区电场强度、电流密度、加工速度等在加工过程中的变化规律,建立了加工中间隙变化的数学模型,并给出了相关的实验结果,为这种简易加工方式的合理应用提供了理论依据.,A kind of new idea based on electromagnetic theory is presented, and it is used in research of the shaping law of electrochemical perforation with fixed cathode. The changing laws of the electric field vectors at certain point on the surface of the anode workpiece with machining time, such as the electric field intensity E, the current density j and so on, are introduced. The mathematical model of the perforating velocity is presented, moreover, the experimental result to verify it is given at the end of the paper. 相似文献
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本文给出了多维小波网络的结构及其随机梯度学习算法,提出了基于小波网络的MQAM数字通信自适应均衡器.仿真结果表明:该均衡器对于MQAM数字信号非线性信道的均衡,其性能明显优于传统的基于LMS和RLS算法的线性均衡器和基于RLS算法的判决反馈均衡器,且性能稍好于基于BP网络的均衡器,其缺点是计算复杂度高和训练收敛速度慢.,A novel wavelet network based adaptive equalizer (WNBAE) is presented and the structure and stochastic gradient learning algorithm is given. The proposed WNBAE has better performance than that of the conventional linear transversal equalizer based on the LMS and the RLS algorithms, as well as that of the decision feedback equalizer based on the RLS algorithm, especially for MQAM digital communication reception systems over the nonlinear channels. In addition, it outperforms the BP neural network based adaptive equalizer slightly. However, it has a slow convergence rate and a high computational complexity. Several simulations are performed to evaluate the behavior of the WNBAE. 相似文献
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对一台220t/h燃油锅炉掺烧油焦后的炉膛内三维流场进行了冷模实验和数值模拟,以预测由于掺烧而对锅炉进行改造后的炉膛内流场的空气动力特性.采用K-ε模型,运用TTM的非正交贴体网格来处理炉膛的不规则边界,在贴体坐标系下用SIMPLE算法对控制方程进行求解.为了验证解的正确性,将原型锅炉制成模型,在额定工况下进行实验,实验结果与计算结果相吻合.在此基础上,结合该锅炉三种改造方案计算出较佳结构尺寸.现场改造结果显示,运用数值计算和模化实验相结合的方法对锅炉进行改造,具有广阔的应用前景.,In this paper, cold simulation experiments and numerical calculations are conducted to predict 3-D flow field aerodynamics for an oil furnace after being retrofitted due to its fuel variation. K-ε model and SIMPLE program under body-fit-coordination (BFC) system, in which TTM non-orthogonal method is used to control the irregular geometric boundary, are adopted to solve the control equations. Model tests are conducted to check the calculation results, showing that they are in agreement with each other. Three different alternatives with different side window locations are also calculated to optimize the designs. The field retrofitting results show that the combination of cold tests with numerical calculations has prosperous application in retrofitting or renewing medium and small boilers. 相似文献
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提出了一种新的语音识别方法,该方法综合了VQ和离散HMM算法,在每个状态通过用矢量量化误差值取代传统的HMM输出概率值来建立VQ-HMM.介绍了VQ-HMM,并通过非特定人汉语数码语音识别实验对其识别性能与传统的HMM作了相应的比较.实验结果表明该方法识别效果优于传统的HMM.,In this paper, a new speech recognition method was proposed, which integrated a VQ-distortion measure and a discrete HMM. The VQ-HMM uses a VQ-distortion measure at each state instead of a discrete output probability used by a discrete HMM. The VQ-HMM is described, and its speech recognition performance is compared with the conventional HMMs through the experiments on speaker-independent Chinese spoken digit recognition. The comparisons confirm that the new method over-performed traditional HMMs. 相似文献
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对外汉语写作教学与写作教材建设刍议——兼论《体验汉语写作教程》的编写思想及特点 总被引：1，自引：0，他引：1
本文分析了我国对外汉语写作教学及写作教材中存在的问题,认为要解决写作教学中的问题,就必须先解决好写作教材中存在的问题;讨论了《体验汉语写作教程》的编写思路及主要特点,并提出了书面表达是对外汉语教学的一个重要组成部分。因此,应该有计划、分阶段地对学习者进行书面表达能力的训练。Abstract： Based on the basic situation of the current writing materials in TCSL,this paper analyzes the existing problems in writing teching and writing materials,and proposes that in order to solve the problems of teaching writing,the problems in writing materials should be first solved.The paper describes the thoughts and the main features of Experience Chinese Writing Course,then puts forward that written expression is an important language skill,and written expression teaching is an important component of TCSL,therefore the training of written exprsseion should be carried out step by step and in a planned way. 相似文献
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2006年春季我国在西部实施农村义务教育经费保障措施,至今已在全国城乡推广开来。湖北省恩施土家族苗族自治州是民族聚居地区、农村地区和贫困地区在地理空间上为交互＂叠加＂关系的地区。如何把国家对该地区有限的义务教育投入进行优化配置,提高教育质量和相关制度建设,树立民族地区可持续减贫的理念,使有限的公共财政支出发挥更大的绩效是亟待解决的问题。本研究深入恩施州几县市进行实地调查,分析恩施州义务教育经费新机制实施之后经费的投入和使用状况,从而发现存在的问题并提出相应的政策建议。Abstract： The financial guarantee mechanism for rural compulsory education in the Western China started in the spring of 2006.By now,it has been carried out in urban and rural areas all over the country.Hubei Enshi Tujia and Miao Autonomous Prefecture is not only a compact community of minorities but also a poverty-stricken rural area.The problems demanding prompt solution are how to optimize limited disposition of the state input for compulsory education in this region,how to improve education quality and construct relevant systems,and how to uphold the concept of sustainable poverty reduction in ethnic regions to give full play to better performance of limited public finance expenditure.In this study,a field investigation was made in a few counties in Enshi Prefecture to analyze financial input and application after the implementation of the new financial mechanism for compulsory education so as to find out problems and put forward policy suggestions. 相似文献
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多回路平面机构装配构形数的研究 总被引：12，自引：0，他引：12
本文提出了同伦方法与基本运动链相结合来求解平面机构构形数的新方法,首次提出机构构形数决定于基本运动链,给出了关于机构构形数的一般定量求解公式,求解并列表给出了所有1～4回路BKC构形数,揭示了平面机构构形数的内在规律.通过实例分析讨论可以看出:本文所提出的方法和公式对求解机构构形数具有普遍意义,可迅速查表计算得出可分解成1～4回路BKC的平面组合机构的构形数.,This paper presents a general approach for determining the configuration number for any linkage: A kinematic cham (KC) can be divided into some basic kinematic chains (BKCs) and driving joints, there are only 33 kinds of BKCs with υ=1-4 independent loop, containing only R (revolute) joints and their configuration numbers are given, the configuration number of a KC equals to the multiplication of the configuration numbers of BKCs contained in the KC. 相似文献
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周期信号测量同步采样中同步误差的分析与仿真 总被引：4，自引：0，他引：4
周期信号测量中广泛采用软件同步采样测量方法,其测量误差普遍存在.本文分析了用软件实现同步采样在测量正弦电流电压有效值、有功功率的过程中产生误差的原因及误差的大小,建立了测量误差的数学模型, 并通过仿真计算,提出了减小测量误差的措施.,Software synchronous sampling is widely employed in periodic signal measurement, but measurement errors occur very commonly. This paper analyses the cause of the errors, deduces the mathematical model for the measurement errors in measuring RMS voltage, RMS current and active power using the software synchronous sampling method. Some measures to reduce the errors are put forward by simulating. 相似文献
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《宜宾学院学报》2017,(6):25-29
针对农村土地流转统计分析无法体现土地流转中社会关系的复杂性和个体行为的随机性,提出了建立人工社会模型研究农村土地流转变化趋势.该模型结合制度分析、发展框架(IAD)与基于制度分析的主体模型系统(MAIA),形式化与土地流转有关的主要社会制度与规则,将土地流转主体(Agent)划分为农民主体与农户主体,并抽象出农户主体属性与行为,农民主体在不同角色下的属性与行为以及在角色之间的转换规则.通过模型计算可以得到土地流转、土地利用情况,不同年度农村人口结构、劳动力流动变化结果.结果分析表明,该模型能较好地反映个体行为与社会关系对农村土地流转的影响,可为研究土地流转政策提供合理的依据. 相似文献
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提出了正交向粘贴CFRP条带和钢板条带的新型复合加固方法,利用CFRP条带和钢板条带共同工作,以提高钢筋混凝土结构的性能.为了检验该方法加固钢筋混凝土双向板的效果,对7块尺寸为1 500 mm×1 500 mm×70 mm、配筋率为0. 22%的双向板进行了集中荷载下的受压试验,其中1块板未加固,1块板在板底粘贴CFRP条带形成格栅加固(CFRP格栅),5块板在板底正交向粘贴CFRP条带和钢板条带形成复合格栅加固(CFRP-钢板格栅),并用螺栓锚固.研究参数包括加固方法、条带间距(150,200,250 mm)和CFRP条带的层数(CFRP-钢板格栅中分别包含1层、2层和3层CFRP条带).试验结果表明:与CFRP格栅加固板相比,CFRP-钢板格栅能有效延缓钢筋混凝土双向板的开裂并提高其承载能力和变形能力.利用塑性铰线理论模型计算加固板的承载力,计算结果与试验结果吻合较好. 相似文献
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《海外英语》2007,(5):10-11
Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help? 相似文献
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《海外英语》2007,(4):36
There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love. 相似文献
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Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject. 相似文献
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Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities. 相似文献
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RUZBEHANI Mohsen 《重庆大学学报(英文版)》2004,3(1):20-25
1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec… 相似文献
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唐芳 《读与写:教育教学刊》2008,5(6)
During interview with English majors, it was found that a majority of students expressed disappointment with their experience of English literature classes. Students' dislike of learning English literature appears to be the major problem of teaching English literature in China. Reader response approach is a good way to solve this problem. In this paper, I explain the rationale behind the reader response approach, such as its origin, definition, features, assumptions, and strategies. Then I illustrate how reader response approach works as a teaching strategy by presenting several teaching models. At last I evaluate its usefuiness for teachers and present the advantages of reader response approach in Chinese context. 相似文献