界限理论在汉语动词中的应用

主要研究现代汉语动词的"界限"问题。界限设置并不仅仅是关于名词所指事物的概念,动词所表示的行为过程是否有起点和终点也可以看作是一种时间上的界限设置。我们依据沈家煊先生的论点,认为仅仅在时轴上将动词区分为"有界"与"无界"是不够全面的,将在其基础上对动词做一个更为详细的区分。     

英语比较动词纵探

英语比较动词是用来表达级差这一逻辑意义的一类较特殊的动词。英语比较动词的数量虽不如形容词、副词比较级丰富，但仍是构成英语比较语义系统不可忽视的环节。本文系统探讨了英语比较动词的语义、语法与形态学特征，以及相关语义动词的比较级分类，并在对比分析的基础上推演出英语比较动词的不同类别，从而加强了对英语比较动词的了解和认识。     

精度和重复性的区别

许多工程师都不明白精度和重复性间存在着区别．因此，在购置定位工作台时，常会出现超支的情况．同高等级的重复性相比，高等级的绝对定位精度的花费要大得多．一般情况下，应避免追求不必要的高精度．定位精度是沿着运动轴向测得的拟定位置与实际位量间的最大误差；重复性精度是指某一特定位还方向上的运动从一个方向（单向）或两个方向（双向）上重复其本身的程度．当逐点测量以实际距离为基准时．绝对定位精度是必需的．用于对号件上特征量间的精确距离进行检测的坐标测量机就是一个很好的例子．在这种情况下，一般需要用到高精密的工作…     

21世纪先进纤维和复合材料的市场前景

3扩大未来工业市场的要来在规划扩大先进纤维和复合材料未来市场时必须考虑的几个重要而相互关联的问题是：技术、经济和政治与政府问题。3．且技术问题3．1．1改进纤维性能要不断改进先进纤维的性能。例如，当前PAN基高强碳纤维的应变可以达到2％，而在10年后应达到2．5％，这     

水温警示亮起 切勿盲目行车

<正>在行车时出现水温表读数升高且快到红线位置并出现水温表红色警示标志,或是发动机盖突然冒出白色的水蒸气的情况,就说明水温过高。应当及时将车开到路边停车检查几项内容:第一、要看水箱的水是否充足或是漏水。第二、要检查电子扇是否正常转动。第三、温度传感器是否损坏。第四、冷凝器管是否堵塞等等。同时切不可盲目行车,水箱温度过高会加快活塞的磨损,造成温度变化不均匀,会影响到车子的动力,严重的甚至有可能造成发动机永久损害。     

屈折形态学视角下的日语动词谓语的声调变化

在日语声调研究领域中,从屈折形态学的角度揭示日语动词谓语的声调变化规律,是一个崭新的声调研究视角。基于此,通过屈折形态学的研究方法,主要探讨了日语动词谓语发生形态变化时所引发的声调核移位现象以及其主要特征。日语动词谓语发生屈折形态变化时,随着语素的增加,声调核的位置也发生复杂的变化。如果从屈折形态学的视角分析日语动词谓语的声调变化,就能进一步挖掘声调变化的内在规律。     

干涉预应力在拉压大载下变化规律的比较研究

对厚度6mm,干涉量3．1％情况下的硬铝合金LY12CZ板销钉干涉配合预应力及其在35％σ0.2,45%σ0.2,55%σ0.2的拉伸,压缩载荷情况下的变化规律进行了比较实验研究。结果表明,在3．1％干涉水平下,干涉配合较适宜在中等及其以下的拉伸载荷环境中工作,此时干涉预应力场的稳定性较好,在压缩载荷下,干涉配合也是有效的,但为得到稳定的干涉预应力场,同样干涉水平下,压缩载荷要比拉伸载荷低。     

刍议算法在程序设计中的重要性

当程序设计人员对问题的描述清楚后，要想利用计算机来解决问题时，就得编写程序，但如果直接开始写程序可能有些复杂，所以，一般都是先由算法着手，在配合适当的数据结构，就能容易地写出程序。本文通过在实践教学中遇到的一例问题，讨论了算法在程序设计中的重要性。     

浅谈高级一地面活动引导和控制系统

一、高级一地面活动引导和控制系统（A-SMGCS）的提出随着机场规模的扩大，机场布局愈发复杂，对地面活动引导和控制的要求也随之提高、难度也越来越大。据有关统计资料表明，地面交通事故，如飞机危险接近、车辆与飞机争道抢行等时有发生，并呈上升趋势。因此，管理好机场地面交通对于保证运行安全和提高机场效益是至关重要的。目前，绝大多数机场运行是依靠塔台管制员、飞行员、车辆驾驶员根据目视观察，估计出各自与其它飞机、车辆的相对位置和距离，再采用相应措施避免冲突发生。但随着机场平面布局的复杂化、交通密度的增加、天气恶劣等原因，再维持传统的“看见和被看见（see and be seen）”的原则（这里的“看见和被看见”是广义的，不单指在能见度低时的，而更多的是指在能见度好的情况下，机场高密度流量和布局复杂的情况下，塔台管制员、飞行员和车辆驾驶员是否还有能力清晰地看到对方，和被对方看到），此时实施对机场地面活动引导和控制，已经超出了人们正常的承受能力。因此，地面活动存在着极大的安全隐患。自90年代中期以来，航空运输较发达国家对机场地面活动引导和控制系统进行了一系列的研究探讨，利用自动控制原理和当今最新的信息及网络技术，对原有的SMGCS进行改造，逐步完善并加强原有各种功能使之自动化，形成了A—SMGCS的原型机。并在欧洲几个机场的运行环境中进行了示范运行，并取得了一定的效果。     

半圆铣刀刃磨夹具

半圆铣刀刃磨夹具如图所示，平面磨床上使用的这种专用夹具易于制造。销子Ａ是固夹铣刀头部的止动器，在刃磨小直径铣刀时，可使磨轮离开夹具体一个间隙。刀柄孔径镗削加工后，比刀柄尺寸大０．００１ｉｎ（０．０２４ｍｍ）左右。两个压紧螺钉可调整，以便与刀柄很好配合...     

The effect of inlet conditions on the flow and heat transfer in multiple rotating cavity with axial throughflow

This paper discusses experimental results from two different build configurations of a heated multiple rotating cavity test rig.Measurements of heat transfer from the discs and tangential velocities are presented.The test rig is a 70% full scale version of a high pressure compressor stack of an axial gas turbine engine.Of particular interest are the internal cylindrical cavities formed by adjacent discs and the interaction of these with a central axial throughflow of cooling air.Tests were carried out for a range of non-dimensional parameters representative of high pressure compressor internal air system flows(Re up to 5×106 and Rez up to 2×105).Two different builds have been tested.The most significant difference between these two build configurations is the size of the annular gap between the(non-rotating) drive shaft and the bores of the discs.The heat transfer data were obtained from thermocouple measurements of surface temperature and a conduction solution method.The velocity measurements were made using a two component,LDA system.The heat transfer results from the discs show differences between the two builds.This is attributed to the wider annular gap allowing more of the throughflow to penetrate into the cavity.There are also significant differences between the radial distributions of tangential velocity in the two builds of the test rig.For the narrow annular gap,there is an increase of non-dimensional tangential velocity V/Ωr with radial location to solid body rotation V/Ωr=1.For the wider annular gap,the non-dimensional velocities show a decrease with radial location to solid body rotation.      

Research on Auto-detection for Remainder Particles of Aerospace Relay Based on Wavelet Analysis

Aerospace relay is one kind of electronic components which is used widely in national defense system and aerospace system. The existence of remainder particles induces the reliability declining, which has become a severe problem in the development of aerospace relay. Traditional particle impact noise detection (PIND) method for remainder detection is ineffective for small particles, due to its low precision and involvement of subjective factors. An auto-detection method for PIND output signals is proposed in this paper, which is based on direct wavelet de-noising (DWD), cross-correlation analysis (CCA) and homo-filtering (HF), the method enhances the affectiv-ity of PIND test about the small particles. In the end, some practical PIND output signals are analysed, and the validity of this new method is proved.     

Preparation of Highly Dispersed Antimony-doped Tin Oxide Nano-powder via Ion-exchange Hydrolysis of SnCl4 and SbCl3 and Azeotropic Drying

Antimony-doped tin hydroxide colloid precipitates have been synthesized by hydrolysis of SnCl4 and SbCl3 using: (1) an ion-exchange hydrolysis to remove chlorine ions, and (2) isoamyl acetate as an azeotropic solvent to obviate water. The obtained dried powder is of high dispersivity without any need for further grinding. The size and dispersivity of the final particles are investigated with the aid of TG-DTA, BET, XRD and TEM. After having calcined, the antimony-doped tin oxide nanopowder possesses a tetragonal rutile structure with high dispersivity, uniform particles and low hard agglomeration.     

Effects of Mo on the Microstructure and Hydrogen Sorption Properties of Ti-Mo Getters

The effects of Mo on the microstructure evolution, porosity and hydrogen sorption properties of Ti-Mo getters are investigated in this work. The results show that the addition of Mo prolongs the densification process of Ti-Mo getters and results in a significant amount of sintered pores. With the Mo content increasing, the porosity of getters firstly increases reaching the maximum value as it at- tains about 7.5wt.%, and then drops. At the room temperature, the hydrogen sorption property of getters increases progressively with the Mo content increasing, but the tendency is not very clear before its content lies below 2.5wt.%. When the Mo content achieves about 7.5wt.%, the hydrogen sorption property proves to be the best. The discussion is made about the above mentioned phenomena inclusive of hydrogen sorption properties of getters under different activation conditions (from 500-750 ℃).     

超声速燃烧数值模拟中的湍流与化学反应相互作用模型

高精度数值模拟有助于理解超声速湍流燃烧中湍流与化学反应的相互作用,可为发动机燃烧室等工程应用设计提供可靠的预测模型。除直接数值模拟外,目前在湍流燃烧应用中使用的大涡模拟和雷诺平均Navier-Stokes模拟均需要借助模型模化发生在湍流小尺度上的流动与化学反应过程对湍流大尺度运动的影响。现有的湍流与化学反应相互作用模型大致可分为:火焰面类模型和概率密度函数类模型,2类模型在不同的应用中各自具有优势和局限性。此外,现有模型大都基于低马赫数燃烧,而超声速燃烧中通常会伴随快速混合、局部熄火和再着火以及激波等复杂过程,这为发展其中的湍流与化学反应相互作用模型提出了更多的挑战。     

适于低轨卫星IP网络的单核共享树组播算法(英文)

为了解决低轨卫星IP网络中现有典型源组播算法的信道资源浪费问题,本文提出了一套单核共享树组播算法,即核心群合并共享树(CCST)和加权核心群合并共享树(w-CCST)算法。CCST 算法包括动态近似中心(DAC)选核方法和核心群合并组播路径构建方法。DAC方法专为周期、规律运动的低轨卫星网络提出,不需要复杂的星上计算。在核心群合并方法中,以核节点作为初始核心群,通过核心群和剩余组成员的最短路径方法逐步扩展直至整棵组播树构建完成,从而使得组播树的树代价最小,大大提高了网络的带宽利用率和组播传输效率。w-CCST 算法中所提出的加权因子可以调整树代价和端到端传播时延之间的折衷程度,因此,可以通过调整加权因子来适度增大树代价、降低端到端传播时延以支持某些端到端时延要求苛刻的实时组播业务。最后,与低轨卫星 IP 网络中典型算法进行了性能比较,仿真结果说明,CCST 算法的平均树代价比其它算法显著降低,w-CCST 算法的平均端到端传播时延小于 CCST 算法。     

Jet Vectoring Control Using a Novel Synthetic Jet Actuator

A primary air jet vectoring control system with a novel synthetic jet actuator (SJA) is presented and simulated numerically. The results show that, in comparison with an existing traditional synthetic jet actuator, which is able to perform the duty of either “push” or “pull”, one novel synthetic jet actuator can fulfill both “push” and “pull” functions to vector the primary jet by shifting a slide block inside it. Therefore, because the new actuator possesses greater efficiency, it has potentiality to replace the existing one in various appli- cations, such as thrust vectoring and the reduction of thermal signature. Moreover, as the novel actuator can fulfill those functions that the existing one can not, it may well be expected to popularize it into more flow control systems.     

Nonlinear Adaptive Slewing Motion Control of Spacecraft Truss Driven by Synchronous V-gimbaled CMG Precession

The slewing motion control of a truss arm driven by a V-gimbaled control-moment-gyro (CMG) is a nonlinear control problem. The V-gimbaled CMG consists of a pair of gyros that must precess synchronously. The moment of inertia of the system, the angular momentum of the gyros and the external disturbances are not exactly known. With the help of feedback linearization and recursive Lyapunov design method, an adaptive nonlinear controller is designed to deal with the unknown items. Performance of the proposed controller is verified by simulation.     

An SOR Implicit Time-accurate Scheme in Calculating Unsteady Flows

A new time-accurate marching scheme for unsteady flow calculations is proposed in the present work. This method is the combination of classical Successive Over-Relaxation (SOR) iteration method and Jacobian matrix diagonally dominant splitting method of LUSGS. One advantage of this algorithm is the second-order accuracy because of no factorization error. Another advantage is the low computational cost because the Jacobian matrices and fluxes are only calculated once in each physical time step. And, the SOR algorithm has better convergence property than Gauss-Seidel. To investigate its accuracy and convergency, several unsteady flow computa- tional tests are carried out by using the proposed SOR algorithm. Roe’s FDS scheme is used to discritize the inviscid flux terms. Un- steady computational results of SOR are compared with the experiment results and those of Gauss-Seidel. Results reveal that the numerical results agree well with the experimental data and the second-order accuracy can be obtained as the Gauss-Seidel for unsteady flow computations. The impact of SOR factor is investigated for unsteady computations by using different SOR factors in this algorithm to simulate each computational test. Different numbers of inner iterations are needed to converge to the same criterion for different SOR factors and optimal choice of SOR factor can improve the computational efficiency greatly.