La2O3纳米晶的制备与表征

La₂O₃ Nanocrystals were prepared by polyethylene glycol method. The structure and morphology of La₂O₃ nanocrystals were characterized by X-ray powder diffraction (XRD), transmission electron microscope (TEM) and BET specific surface area absorption meter.La₂O₃ nanocrystals with different size of particles and different type of morphology were produced at different heat-treatment temperatures. Mixed La₂O₃ nanocrystals of monocline and hexagonal were obtained at 600℃ and completely transformed to the hexagonal phase when the heat-treatment temperature raised above 850℃. The Raman spectra of the La₂O₃ nanocrystals are also analyzed in this paper.     

Comparison of alternative route selection strategies based on simulation optimization

Air traffic flow management (ATFM) is a collaborative process between the airspace provider and the airspace users. The result of the collaboration should be an outcome that maxi-mizes the utility of the system without excessively penalizing any of the agents. This paper develops a discrete-event simulation model which consists of aggregate departure/arrival airports, flight routes, and sectors for evaluating the alternative collaborative route selection strategy. Given the different perspectives from air traffic control center (ACC) and airlines, eight performance-metrics and five alternative route selection strategies represent the past, current and proposed air traffic flow management operations that were evaluated. The Monte Carlo method combined with the Optimal Computing Budget Allocation (OCBA) simulation optimization technique is employed to assess the performance of different strategies. A case study of the upper air routes in central and southern China shows that the proposed model can be readily implemented to simulate different kinds of air traffic flow management strategies and predict the effect of changes on the airspace sys-tem. It also shows that the proposed alternative collaborative route selection strategy is an effective way in alleviating the en-route traffic congestion.     

Effects of the Fabrication Processes of NC-Si： H Films on Their Mechanical Properties

Studies of nanoindentation were performed on nc-Si：H films to evaluate the effects of the fabrication processes on their mechanical properties. It is observed that with the decrease of the SiH4 contents, the grain size of the films increases gradually, and as does the crystalline volume fraction. The smaller the grains become, the more homogeneous the films, and the more even the hardness as well as the modulus will be. The hardness and the modulus will increase with the substrate＇s temperature rising. The hardness and the modulus of the nc-Si：H films on the Si substrate prove to be higher than those on the glass substrate given the same technology parameters. How- ever, the films on the glass substrate appear to be more homogeneous.     

Effects of the Fabrication Processes of NC-Si:H Films on Their Mechanical Properties

Studies of nanoindentation were performed on nc-Si:H films to evaluate the effects of the fabrication processes on their mechani-cal properties. It is observed that with the decrease of the SiH4 contents, the grain size of the films increases gradually, and as does the crystalline volume fraction. The smaller the grains become, the more homogeneous the films, and the more even the hardness as well as the modulus will be. The hardness and the modulus will increase with the substrate’s temperature rising. The hardness and the modulus of the nc-Si:H films on the Si substrate prove to be higher than those on the glass substrate given the same technology parameters. How-ever, the films on the glass substrate appear to be more homogeneous.     

Si3N4－TiN－SiC复相陶瓷的燃烧合成

Si₃N₄－TiN－SiC Multiphase ceramics was produced by self-propagating high-temperature synthesis with TiSi₂ and SiC. The liqu id phases produced during combustion of TiSi₂ and N₂ will decrease conversi on factor of the products. The effect of the dilution and nitrogen pressure on t he conversion of the products and combustion temperature was analyzed. The contradictory of liquid phases, dilution and combustion temperature was reso lved by increasing nitrogen pressure. Decrease of porosity was resulted from the volume expansion of discomposed TiSi₂,the volume expansion of Si transformed to Si₃N₄ at high temperature. The nitride mechanism of TiSi₂ was studied. TiN was first synthesized,then Si₃N₄ was formed.     

Luminescent Nanocrystalline Silicon Carbide Thin Film Deposited by Helicon Wave Plasma Enhanced Chemical Vapour Deposition

Hydrogenated nanocrystalline silicon carbide （SIC） thin films were deposited on the single-crystal silicon substrate using the helicon wave plasma enhanced chemical vapor deposition （HW-PECVD） technique. The influences of magnetic field and hydrogen dilution ratio on the structures of SiC thin film were investigated with the atomic force microscopy （AFM）, the Fourier transform infrared absorption （FTIR） and the transmission electron microscopy （TEM）. The results indicate that the high plasma activity of the helicon wave mode proves to be a key factor to grow crystalline SiC thin films at a relative low substrate temperature. Also, the decrease in the grain sizes from the level of microcrystalline to that of nanocrystalline can be achieved by increasing the hydrogen dilution ratios. Transmission electron microscopy measurements reveal that the size of most nanocrystals in the film deposited under the higher hydrogen dilution ratios is smaller than the doubled Bohr radius of 3C-SiC （approximately 5.4 nm）, and the light emission measurements also show a strong blue photoluminescence at the room temperature, which is considered to be caused by the quantum confinement effect of small-sized SiC nanocrystals.     

飞机机体使用寿命定义

 <正> The maximum service period reached safely and economically by frames of an airplane is defined as service life. This definition is different from "safe life" or "economic life" specified in MILA-008866A or MIL-A-87221, respectively.It is explicated that service life is related to the overall process of production activity from material to operation management. The paper has also pointed out the way of obtaining the service life.     

Guide for Authors

<正>About Journal Chinese Journal of Aeronautics(CJA) is a comprehensive academic journal dealing with the fields of aeronautics and astronautics. It reports researches concerning the two fields in China and abroad to promote the academic exchange. Founded in 1988 and sponsored by the Chinese Society of Aeronautics and Astronautics and Beihang University, CJA publishes papers bimonthly, with issues released in February, April, June, August, October and December. The intended readers of the journal are specialized technical workers, teachers and students in colleges and universities and the related personnel of management,     

SEPARATED FLOW AROUND BENT-NOSE BICONIC IN HYPERSONIC FLOW

This article investigates the separated flow around the bent-nose biconic, in which the second ordered TVD(Total Variation Diminishing) method is applied. The governing cqua-tion is a thin layer Navier-Stokes equation. The surface pressure distribution at the leeward side is a little higher in the vicinity of the symmetrical plane. This seems to be caused by the development of the vortex at the leeward side due to the separated flow. The location of a separation line and the size are in very good agreement with the experiment. Also the secondary separation is captured very clearly.     

Luminescent Nanocrystalline Silicon Carbide Thin Film Deposited by Helicon Wave Plasma Enhanced Chemical Vapour Deposition

Hydrogenated nanocrystalline silicon carbide (SiC) thin films were deposited on the single-crystal silicon substrate using the heli-con wave plasma enhanced chemical vapor deposition (HW-PECVD) technique. The influences of magnetic field and hydrogen dilution ratio on the structures of SiC thin film were investigated with the atomic force microscopy (AFM), the Fourier transform infrared ab-sorption (FTIR) and the transmission electron microscopy (TEM). The results indicate that the high plasma activity of the helicon wave mode proves to be a key factor to grow crystalline SiC thin films at a relative low substrate temperature. Also, the decrease in the grain sizes from the level of microcrystalline to that of nanocrystalline can be achieved by increasing the hydrogen dilution ratios. Transmis-sion electron microscopy measurements reveal that the size of most nanocrystals in the film deposited under the higher hydrogen dilution ratios is smaller than the doubled Bohr radius of 3C-SiC (approximately 5.4 nm), and the light emission measurements also show a strong blue photoluminescence at the room temperature, which is considered to be caused by the quantum confinement effect of small-sized SiC nanocrystals.     

关于两个管理理念的思考

管理不能过于严格,也不能过于宽松,严格管理和宽松管理各有其利弊和适应条件,过分地严格管理必然走入误区。打破“铁饭碗”是对的,但职工“饭碗”也不是越脆弱越好。“饭碗”坚固与脆弱必须适度,应该兼顾效率与公平的原则。     

从刚性管理到弹性管理——我国家族式企业管理改革新思路

家族式企业存在的本身具有世界性,能够与现代市场经济相容。我国家族式企业有其存在的必然性和长期性,但家长式管理体制不适应生产力的发展。我们需要在充分认识其弊端的前提下,改革传统家长式的刚性管理体制为现代家族公司制的弹性管理体制。我国的家族式企业仍然拥有广阔的发展前景。     

计量仪器及检测设备的标识管理方法

根据国家国防科工局有关要求,计量技术机构要进一步规范使用计量标识,建立、健全计量标识管理制度。本文就计量仪器及检测设备实行ABC标识管理的现状进行了分析,并就如何划分A,B,C类检测设备、实施标识管理、确保其计量传递特性进行了讨论。     

高校图书馆期刊管理服务创新举措

高校图书馆期刊管理工作需立足本校实际情况,提高期刊信息服务意识及采购质量,建立合理的馆藏期刊结构,创新期刊管理服务措施,拓展期刊服务内涵。高效发挥期刊信息的作用,提高期刊资源利用率,更好地为读者服务。     

浅谈ERP软件在车间现场的应用与实施

以某生产厂应用实施企业资源规划系统ERP(Enterprise Resource Planning)为例,阐述ERP软件在车间现场的应用实施过程。针对实施中存在的问题进行了深入剖析与探讨。说明ERP系统应用必须兼顾企业自身管理的可行性,系统的合理性与实际的可行性之间存在着折衷的实施方式。     

论民航运输企业管理以财务管理为中心

分析了民航运输企业管理的现状,提出并论述了民航运输企业管理以财务管理为中心的依据,阐述了民航运输企业管理以财务管理为中心的特征与标志,说明了今后在财务管理方面应作的工作。     

规范公文起草 提高以文辅政水平

公文处理是高校行政管理工作的重要组成部分,公文起草的质量和效率,反映着学校工作的质量和管理水平。规范高校公文起草工作,应从公文主题、发文意图、行文内容、文种选择、文字表达等方面入手,以此提高以文辅政水平。     

民用飞机供应商构型管理体系审核

构型管理是民用飞机研制成功的重要保证,在以"主制造商-供应商"模式进行的民用飞机研制中,作为主制造商构型管理的重要组成部分,供应商构型管理至关重要。需要确保供应商能够在产品的全生命周期内为产品构型提供持续的控制,以及确保供应商的构型管理工作能够满足主制造商规划的型号设计要求,因此有必要对供应商构型管理体系进行全面的审核。提出了在供应商构型管理体系审核中应关注的主要方面,以确保达到审核目的。     

企业的控制和激励机制与交易成本分析

运用交易成本理论对企业的控制和激励机制进行了分析，提出企业管理控制的重点应转向引发成本的根源——活动上．而在激励中应更重视部门间的合作。     

回归人本管理——百年管理史从"科学"到"人文"的发展趋势

管理学诞生百年来，随着社会的进步，“人”的价值日益突显。早期泰勒的“科学管理”是产生于机器大工业特殊历史背景下的产物，其基本信条是工人如牛马，效率高于一切，管理就是监控。20世纪20年代至20世纪30年代，管理学开始关注“人”，其中，人事管理学派主张在管理中“善待”其雇员，但其追求的最高境界只是雇主与雇员利益关系的整合。20世纪中后期，特别是20世纪90年代以来，由于新技术革命的推动，人力资源，特别是知识工人和专业化的人力资本越来越成为决定企业市场竞争成败的战略性要素，于是，以“战略性激励”为核心理念的人力资源管理学逐渐成为管理学主流，但人力资源管理的实质是要求从战略高度将人作为资财（资源、资产、资本）来运营。21世纪的管理要进一步超越人力资源管理，真正树立“以人为本”的理念，从总体上、动态上、“人本”精神层面去挖掘员工的“群体精神创造力”。这在本质上符合马克思关于“人的全面发展”的思想。