对控制理论中三个问题的研讨

对控制理论中的三个问题--无约束条件的泛函极值,按可控制和可观性的规范分解,输出反馈与极点配置--进行了讨论.以期对自动控制原理课程的教学提供较大的参考价值,对学术研究也可起一定的启发研讨作用.     

对《大学物理》课程教学改革的思考

简要论述了物理学教育的重要意义和当前《大学物理》教学改革的必要性,提出了《大学物理》课程教学改革的思路、设想和实践目标。教学改革的关键任务,是要提高学生的创新意识和综合应用能力。应以教学方法和手段的改革为课程改革的先导。对课程的内容体系框架的改革提出了建设性的设想,强调指出要加强近代物理教学,同时应调整和更新经典物理的教学内容;强调教学手段的改革是极为重要的,也是迫切需要解决的任务。还介绍了中国民航学院的《大学物理》课程正在着手实施的教学改革实践。     

辛酸的旅程——对《秀拉》中三个人物疯癫行为的解析

《秀拉》中的每一个人物似乎都有异于常人的性格或行为特征。其中,伊娃、秀拉和夏德里克的疯癫行为尤其能够引起读者的注意。透视这三位人物身体或精神上的病态,挖掘出隐藏在他们疯癫行为背后的真相,从而呈现出他们辛酸且无望的"寻我"之路。     

燃烧室轴向和周向长度对气液两相旋转爆轰特性的影响

为了研究旋转爆轰发动机燃烧室轴向和周向长度对气液两相旋转爆轰特性的影响,采用守恒元和求解元(CE/SE)方法对带化学反应的汽油/富氧空气两相旋转爆轰理论模型进行求解,获得了气液两相旋转爆轰流场结构,并分析了燃烧室轴向和周向长度对燃烧室流场、爆轰波传播特性以及发动机推力性能的影响。计算结果表明:轴向长度对燃烧室上游流场影响甚小,却对下游流场参数影响较显著。随着轴向长度增加,燃烧室出口压力、温度、密度以及周向速度均降低,轴向速度则逐渐增大,同时发动机平均推力密度和燃料比冲先增大后减小。当周向长度过短,燃烧室内难以形成自持传播的爆轰波,随着周向长度增加,上游爆轰波强度增加,对应的流场参数均有所增大,但发动机推力性能略有所降低。     

对管制通话用语几个问题的探讨

ADiscussiononAirTrafficControlPhrases影响空中交通安全的因素很多,有设备因素、技术因素、环境因素和人为因素等,但是最值得注意的是管制通话用语。据有关机构的研究表明,70％以上事件都和人与人之间的语言交流有直接关系。现阶段尽管有很多高科技的数据网,大量的数据可以通过数据网自动传输,世界各国和国际民航组织正在想尽办法来解决管制员和飞行员之间的通话问题,如：欧洲地区已将民用航空使用频率的频段减少到8．33KHz,还有的国家通过使用数据链来减少管制员飞行员间的通话量。但管制员与飞行员之间大量的通话受到限制,…     

高职《机械制图》实践教学的探讨

根据高职教育对《机械制图》课程实践教学的实际需求，加强和改善实践教学的内容、方法，探讨新时期高职《机械制图》实践教学新模式，为国家培养应用型高素质的技术人才很有必要。     

对产品设计图样中几个标准化问题的探讨

基于对产品图样的标准化审查工作实际,对其中存在的非标准尺寸比重较大、尺寸及公差选取不合理、无图件选取不当等问题作了探讨、分析,并提出了改进建议。     

关于格子Boltzmann方法的几个问题(Ⅰ)

格子气方法及后续发展的格子Boltzmann方法,是一种完全不同于传统流场计算的基于介观物理的新方法.由于其内在的优势,尽管该方法问世不过几十年的时间,就在传统计算流体力学难于处理的研究领域得到了广泛的应用,被誉为是现代流体力学的一场变革.文章主要论述了格子Boltzmann方法有关学术思想的源头,论述在该论题发展过程中的一些关键性工作.     

对HB 7089-94中几个问题的探讨

ＨＢ７０８９《航空电子设备完整性大纲要求》提出了一些新颖的概念,提供了一套科学的设计方法和管理程序,开辟了提高航空电子设备质量的新途径。概括介绍了航空电子设备完整性大纲的主要内容及其所要求的分析和试验工作。分析对比了完整性与可靠性在定义、属性、失效机理、故障模式、维修策略、分析和试验要求,以及完整性大纲与可靠性大纲在目标、要求、内容方面的主要差别。指出完整性和可靠性都是设备的一种特性,而前者涵盖了后者。编制、实施ＡＶＩＰ和可靠性大纲是提高航空电子设备质量的不同途径,对于任务和安全关键设备而言,实施ＡＶＩＰ效果更好。     

Nonlinear problems of physics of the geomagnetic pulsations

The current state of research involving manifestations of nonlinearity in geomagnetic pulsations is reviewed. Traditionally, the attention of researchers was focused on the effects of resonant interaction of geomagnetic pulsations with small groups of energetic particles, which actually means the study of the quasi-linear relaxation of radiation belt ions, the modulation of auroral electron fluxes, etc. The present review concentrates on the problem of the nonlinear effect influence of pulsations on the backgroud (cold) plasma and on the geomagnetic field. This kind of interaction results in a significant modification of the plasma distribution in the magnetosphere. Self-consistent wave structures—solitons and vortices may occur as well. Such nonlinear effects contribute to physics of geomagnetic pulsations and are also of fundamental importance for general physics. Another set of more narrow problems considered in the review, is related to phenomenological modeling of fluctuational and critical phenomena in the magnetosphere. The essence of our approach is to present the magnetosphere as a black box, whose properties should be determined by the statistical characteristics of its output signals. This approach to phenomenology can be a useful supplement to the methods of microscopic modeling aimed at detecting nonlinear manifestations of geomagnetic pulsations.     

Global problems in magnetospheric plasma physics and prospects for their solution

Selected problems of magnetospheric plasma physics are critically reviewed. The discussion is restricted to questions that are global in nature, i.e., involve the magnetosphere as a whole, and that are beyond the stage of systematic survey or isolated study requirements. Only low-energy particle aspects are discussed. The article focuses on the following subjects: (i) Effect of the interplanetary magnetic field on topography, topology and stability of the magnetospheric boundary; (ii) Solar wind plasma entry into the magnetosphere; (iii) Plasma storage and release mechanisms in the magnetospheric tail; (iv) Magnetic-field-aligned currents and magnetosphere-ionosphere interactions. A brief discussion of the prospects for the solution of these problems during and after the International Magnetospheric Study is given.Prepared for the Panel on Heliosphere Hydromagnetics of the National Academy of Sciences and for the Steering Committee of the International Magnetospheric Study.     

Some problems of pulsar physics or I'm madly in love with electricity

Some current topics in the theory of pulsar magnetospheres and their emission are reviewed. The mode of plasma supply and its consequences for structure of planetary and stellar magnetospheres is discussed. In the pulsar case, the plasma is supplied by electrical forces, in contrast to all other known examples. The resulting theories of particle acceleration along polar field lines are then reviewed, and the total energization of the charge separated plasma is summarized, when pair creation is absent. The effects of pair creation are reviewed using models of the resulting steady and unsteady flows, when the polar zones of the pulsar emit either electrons or ions. The application of these theories of acceleration and plasma supply to pulsars is discussed, with particular attention paid to the total amount of electron-positron plasma created and its momentum distribution. Qualitative agreement is shown between the spatial structure of the relativistically outflowing plasma described in one version of these models and the morphology of pulsar wave forms. Various aspects of radiation emission and transport are summarized, based on the polar current flow model with pair creation, and the phenomenon of marching subpulses is discussed. The corotation beaming and the relativistically expanding current sheet models for pulsar emission are also discussed briefly, and the paper concludes with a brief discussion of the relation between the theories of polar flow with pair plasma and the problem of the energization of the Crab Nebula.Proceedings of the NASA/JPL Workshop on the Physics of Planetary and Astrophysical Magnetospheres.     

普通高校办学质量宏观评估指数研究

为了更好地实施高等学校质量提升工程,在对高校办学目标解析的基础上,分析了现行我国普通高校办学质量评估方法存在的主要问题,研究了评价高校办学质量的宏观指数。给出了社会影响指数（SYI）、社会价值指数（SJI）、学业成绩指数（SCI）、投入产出指数（TCI）和教师发展指数（JFI）的含义,并提出了五个指数的具体计算方法。这些指数从不同侧面描述了高校总体发展状况。在此基础上,提出了基于数据包络分析的评估方法。对我国普通高校办学质量的评估有一定的借鉴意义。     

收缩-扩张形气膜孔提高气膜冷却效率的机理研究

为了揭示收缩-扩张形孔提高气膜冷却效率的机理,选择了两种典型的气膜孔:圆柱形孔和扇形孔,进行了数值模拟对比研究.湍流模型选取Realizable k-ε模型,壁面函数采用增强壁面函数.结果表明:圆柱形孔射流法向动量很大很集中,生成了较强的耦合涡,冷却效率最低;扇形孔减弱了射流的法向动量,并产生了一定的展向速度,冷却效率得以提高;收缩-扩张形孔减小了射流的流向厚度,增大了射流的展向宽度,且产生了更大的展向速度,扩大了射流的覆盖区域,形成了与圆形孔及扇形孔射流相比作用相反的耦合涡,使气膜更好地贴附于壁面,气膜冷却效率高于其它两种孔形的效率;相对于圆柱形孔和扇形孔,收缩-扩张形孔的平均气膜冷却效率,在吹风比为0.5时,分别提高了约110%和15%,在吹风比为2时,分别提高了约560%和60%.      

大学资源计划(URP)研究

教育信息化的目的是实现创新人才的培养,教育信息化的过程不仅仅是一种信息引入教育的过程,更是一种全新的教育思想.数字化校园是教育信息化的实体表现.URP是数字校园的核心解决方案,也是大学信息系统的总集成,它从全局的高度分析大学内部的关系,并通过建立统一的信息标准,提供平台与接口规范,将各种信息系统以松散耦合的方式集成起来,以统一的形象为用户提供个性化的服务.     

The role of antiprotons in cosmic-ray physics

Though success eluded experimentalists from detecting cosmic-ray antiprotons over a long period of time, the study of cosmic-ray antiprotons has now become a fascinating field of research. In this review, we have attempted to elucidate the excitement in this area of research since the discovery of antiprotons in the laboratory. We have described the experiments carried out so far to measure the energy spectrum of antiprotons, from about 200 MeV to about 15 GeV, and summarised the results. The observed spectrum, with the limited data, appears to be very hard and is different from other components of cosmic radiation. Upper limits to the fraction of antiprotons in cosmic-rays have also been derived at higher energies, using the observed spectra of cosmic-ray primary and secondary particles at different depths in the atmosphere. We have described various physical processes by which antiprotons could be produced, such as high-energy interactions, neutron oscillations, evaporation of Mini Black Holes, decay of super symmetric particles, etc. The energy spectrum of antiprotons, which are produced through the above processes, undergoes modifications during propagation in the Galaxy. We have examined in detail the propagation models which have been employed to explain the observed data. It is shown that no single model could predict correctly the observed energy spectrum of antiprotons over the entire energy region. However, many models are able to explain the data at relativistic energies. It is difficult at this stage to make a choice among these models. The implications of these models for other components of cosmic-rays, such as positrons, deuterium, and He, have been discussed. We have examined the production of gamma rays in the Galaxy from sources, which produce the observed antiprotons through high-energy interactions. We have also briefly indicated the effect of possible re-acceleration during their confinement in the Galaxy. We finally emphasized the need for more detailed measurements of the spectral shape of cosmic-ray antiprotons to further refine speculations of their origin. Similarly, we have shown that detailed observation of the energy spectra of positrons, deuterium, and He at relativistic energies are crucial to test various propagation models.