民航销售市场无序竞争的根源及对策

无序竞争是对近年来民航销售市场竞争纷乱状况的一种形象表述，反映了民航系统上下对当前市场竞争形势的无奈心态。在民航系统体制改革以前，全国的销售机构都是中国民航总局一家所有，实行政府垄断经营制度，加上当时的市场是卖方市场，运力严重不足，供需矛眉异常突出，为了保证政府要员的随时乘机需求，不得不对客票销售进行必要的控制，根本不存在竞争问题。随着地方航空公司的不断涌现，打破政府垄断，开放航空市场的呼声越来越高。民航总局被迫进行了自上而下规模宏大的体制改革，各大航空公司相继成立，被旧体制束缚的生产力得到解放…     

地方政府经济行为失范的制度分析

在改革开放的过程中，地方政府对于体制改革和经济增长做出了巨大贡献，但另一方面，也存在较严重的失范现象。地方政府经济行为失范有着深刻的制度背景。理论和实践表明，要规范地方政府经济行为，就必须实现地方政府的制度创新。     

国家竞争理论的演变及对我国的启示

基于比较优势的国家竞争理论更多的是强调自然资源等国家内生性要素在竞争中的作用，国家竞争理论的进一步发展则强调国家竞争优势的形成和动态发展，更突出政府、体制等外生性要素对国家竞争的影响力，从而大大丰富和深化了国家竞争的主体、客体和竞争形式等问题的研究。     

论现代企业制度下民航运输企业经济效益的综合评价

在1998年全国民航工作会议上，陈光毅局长提出“中国民航已从高速度发展转到适度快速发展，下一步改革的中心环节是加快建立现代企业制度，转变增长方式，走“安全、质量、效益型”的发展路子”。的确，近年来，民航事业的高速发展举世瞩目，但生产和效益指标却出现了明显下滑的趋势。出现这种情况的原因是传统体制下，企业进行粗放式的生产经营管理造成的。这种粗放式的生产经营模式不是提高工艺技术水平、改善经营管理、提高劳动者的技术教育水平，进而提高质量和效益来推动生产的扩张；而是通过人力和资本的投入，靠消耗大量资料和扩大生…     

重大公共卫生事件、税收政策与企业创新——基于新冠疫情的证据

基于增长期权理论，利用我国A股上市公司2015—2021年的面板数据，研究新冠疫情对企业创新的影响。研究结果表明：新冠疫情的冲击能促使企业增加研发投入；这种影响在行业集中度低、金融发展水平高的企业中更加明显。进一步的分析表明，新冠疫情期间我国政府推出的税收优惠政策在其中起到了部分中介作用。研究结论有助于理解重大公共卫生事件冲击下企业创新行为的发展过程，并为政府引导企业促进创新发展提供了经验证据。企业应充分理解危机中创新活动的重要性，加大研发投入，并以此赢得竞争优势；政府则应在发生危机时主动发挥“有形之手”的积极作用，出台针对性的经济政策，助推企业平稳发展，降低危机带来的负面影响。     

长江三角洲地区产业分工、产业转移分析

对长三角地区的三次产业发展和制造业产业结构变动趋势进行实证分析，得出的基本结论是长三角地区初步出现了产业分工，上海劳动密集型产业开始向周边地区转移。出现这一现象的原因包括：竞争、技术转移和产业政策引导。值得注意的是，当前还存在着生产要素流动性不强，地方政府的限制等制约产业分工、产业转移的因素，因此短期内长三角地区的产业分工和产业转移并不会大规模出现。     

当代中国公共政策执行效力探析

提出了一个全新的概念，即政策执行效力。在此基础上，参照关国学者马兹曼尼安和萨巴蒂尔提出的政策执行影响因素，结合中国的现实情况，提出了影响中国公共政策执行效力的四个变量，即党政一把手和基层执法人员，中央、地方关系和人事管理体制，政策形成的程序，执行组织责权清晰程度和组织体系的完善程度。最后，根据当代中国公共政策执行效力与其变量之间的相关关系，提出了推行行政听证和专家咨询制，实施责任追究制，增加地方地府执行政策的灵活性，健全政府组织的咨询、信息评估和反馈系统等政策建议。     

从英航看中国民航发展趋势

中国民航业重组已经基本完成,形成了以中央政府控制的中国航空集团、南方航空集团、东方航空集团三家航空集团为主体,和以海南航空集团、上海航空公司、山东航空公司、四川航空公司等地方航空公司为补充的航空市场构架。按照政府对航空运输企业重组的构想,重组后的航空运输格局,可以在一定程度上改善中国航空运输网络结构,发挥一定的规模效应。但是,从英国航空运输业重组的经验来看,本次重组基本没有涉及民航的产权机制和经营管理机制,依然存在严重的机制缺陷。因而效果将是有限的、结果将是过渡性的,是我国航空运输市场竞争格局形成过程中的一个阶段。加入WTO和中国经济全球化是推动我国民航业改革的强大动力,最终将形成以市场需求为导向,以追求企业价值最大化为目标的航空运输市场格局。笔者认为在5—8年以后,政府对航空业的特殊保护政策将减弱,航空运输业将会有一次大的兼并和产权调整,形成产权多元化,在充分竞争环境下的、按市场规律运营的航空运输体系。     

美国放松管制的喜和忧

今天，当美国实施对航空公司放松管制进入第20年，并开始向世界其他地区输出这一观念之时，美国对本国国内和国际航空政策未来的发展趋势又展开了激烈的争论。美国1978年实施的航空公司放松管制法和1977年实施的放松货运管制，在航空运输领域形成自由的竞争环境并由此所带来的诸多益处，世人有目共睹。在过去20年中，美国的航空客运量增长了一倍多，1997年的客运量达到近6亿人次；乘机旅行的人口百分比增长了一倍，1997年达到50％；货运量增长了两倍。尽管在过去20年中，由于竞争激烈，有些形象很好的航空公司破产，例如：泛美世界航空公司…     

机场行业SWOT分析

随着属地化改革的完成，我国各地机场依照民航总局和地方政府的，要求，纷纷组建机场公司或机场集团公司，实施企业化运营，我国机场行业将逐步进入群雄逐鹿的时代，面临的竞争将越来越激烈。为了更好地谋求发展、赢得竞争，各机场公司或机场集团纷纷加强了发展战略和竞争战略的研究。但在制定战略的过程中，不少机场公司或机场集团都感到对环境分析没有把握，制定的战略针对性不强，因此采用什么方法对企业的环境因素进行分析，成为大家关注的内容。     

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.