先进的制造系统和方法

本对近年来出现的先进的制造系统和技术，如计算机集成制造系统，并行工程，敏捷制造，全能制造，精良生产，虚拟制造，生物制造，分形制造等的原理和特点等做了简要介绍。     

基于ASP的网络化制造服务研究

数字化和网络化已成为当前制造业最为显著的生产特征。为解决目前制造企业设备低利用率与企业得不到快速成形与制造 (RP&M)技术服务的矛盾 ,必须将数字化服务有机地集成到企业产品的设计和制造环境中。应用服务供应商 (ASP)促进了先进制造技术与模式的新发展 ,而基于ASP技术的网络化分散制造是以服务商为中介的新的先进制造模式。文章分析在国内外网络化制造服务研究的基础上 ,结合国内制造业的生产实际需求 ,提出了基于ASP的网络化制造应用服务的模式及其对策 ,对促进网络化分散制造信息服务提供新的思路和实现途径。     

敏捷制造模式研究

本文综述了国内外制造业市场变化趋势及其对制造模式发展变革的客观需求，论述了敏捷制造等现代制造模式诞生发展的历程，详细讨论了敏捷制造的基本原理、主要技术内涵和一些关键技术的实现手段、方法和途径     

建立现代制造工程系统模式的基础和途径

变革传统的制造模式,建立现代制造工程系统模式是制造企业在激烈的市场竞争中求生存和发展的战略性抉择。本文简要论述了几种典型的现代制造工程系统模式建立的基础;通过对波音公司建立和实施现代制造工程系统的案例分析,提出我国航空企业建立现代制造工程系统模式的途径和建议。     

液体火箭发动机增材制造技术研究进展

针对增材制造技术在国内外液体火箭发动机领域的应用成果和研究现状,分别综述了增材制造在发动机的制造技术和流程、制造工艺标准以及在发动机推力室、涡轮泵、阀门、总装及其他组件和整机中的应用研究,并展望了增材制造技术在液体发动机中的发展方向,指出在液体发动机领域,增材制造应该在应用广度和深度、结合增材制造特点的发动机结构设计方...     

飞机零件制造模型及数字化定义

在大飞机数字化制造中,不仅仅是用数字化的装备改变传统的制造工艺过程,而且新的产品信息模型定义技术同样使制造过程产生重大的变革。本课题提出用MBD数据集和DMM数据集共同构成面向全数字化制造的产品模型,将改变原有的产品制造技术体系,实现数字化向产品制造过程的延伸。     

新一代制造策略—灵捷制造原理

需求主导制造市场和市场国际化导致了新一代制造策略───灵捷制造。本文研究了其产生背景、发展现状和基本原理，并探讨了相应的对策。     

虚拟制造模式探讨

虚拟制造是对真实的制造系统的产品及过程的信息提取加工和逻辑功能抽象,是实现敏捷性的一种有效的手段。它包括两个方面的内容：产品生命全程仿真和企业行为仿真,阐述了虚拟制造的概念,对虚拟制造环境下的产品设计模式、生产模式和企业运行模式进行了探讨,并给出虚拟制造相关技术。     

当代先进制造技术发展趋势研究

制造技术是制造业赖以发展的技术支撑,而80年代末提出的先进制造技术对制造技术的新阶段作了一个形象的描述,它使制造技术从一个新的高度得到发展。本文介绍了先进制造技术的产生背景、体系结构,并简述了几种先进制造技术的发展趋势。     

数控加工车间集成制造技术应用

介绍了航空制造类企业数控制造技术的应用现状 ;探索了以产品、人、设备、工艺、管理为对象的综合集成制造技术 ,构造了集成制造车间的体系结构 ;分析了数控加工车间实现集成制造的关键技术和集成的方法。     

Triton, Pluto, Centaurs, and Trans-Neptunian Bodies

The diverse populations of icy bodies of the outer Solar System (OSS) give critical information on the composition and structure of the solar nebula and the early phases of planet formation. The two principal repositories of icy bodies are the Kuiper belt or disk, and the Oort Cloud, both of which are the source regions of the comets. Nearly 1000 individual Kuiper belt objects have been discovered; their dynamical distribution is a clue to the early outward migration and gravitational scattering power of Neptune. Pluto is perhaps the largest Kuiper belt object. Pluto is distinguished by its large satellite, a variable atmosphere, and a surface composed of several ices and probable organic solid materials that give it color. Triton is probably a former member of the Kuiper belt population, suggested by its retrograde orbit as a satellite of Neptune. Like Pluto, Triton has a variable atmosphere, compositionally diverse icy surface, and an organic atmospheric haze. Centaur objects appear to come from the Kuiper belt and occupy temporary orbits in the planetary zone; the compositional similarity of one well studied Centaur (5145 Pholus) to comets is notable. New discoveries continue apace, as observational surveys reveal new objects and refined observing techniques yield more physical information about specific bodies.     

Caution, contention, and consolidation

The Washington Watch column provides an overview of NASA's cautious approach to the launch of Space Shuttle Discovery STS-114, contention between the Air Force and administration about production of the F/A-22 Raptor aircraft, and consolidation among U.S. airline companies.     

CIR Morphology, Turbulence, Discontinuities, and Energetic Particles

Corotating interaction regions (CIRs) in the middle heliosphere have distinct morphological features and associated patterns of turbulence and energetic particles. This report summarizes current understanding of those features and patterns, discusses how they can vary from case to case and with distance from the Sun and possible causes of those variations, presents an analytical model of the morphological features found in earlier qualitative models and numerical simulations, and identifies aspects of the features and patterns that have yet to be resolved. This revised version was published online in August 2006 with corrections to the Cover Date.     

Lunar Ranging, Gravitomagnetism, and APOLLO

The technique of lunar laser ranging (LLR) has for many decades contributed to cutting-edge tests of the fundamental nature of gravity. These include the best tests to date of the strong equivalence principle, the time-rate-of-change of the gravitational constant, gravitomagnetism, the inverse square law, and preferred frame effects. The phenomenologies of each are briefly discussed, followed by an extended discussion of gravitomagnetism. Finally, the new APOLLO project is summarized, which achieves range precision as low as one millimeter.     

Cosmic Rays,Clouds, and Climate

A correlation between a global average of low cloud cover and the flux of cosmic rays incident in the atmosphere has been observed during the last solar cycle. The ionising potential of Earth bound cosmic rays are modulated by the state of the heliosphere, while clouds play an important role in the Earth's radiation budget through trapping outgoing radiation and reflecting incoming radiation. If a physical link between these two features can be established, it would provide a mechanism linking solar activity and Earth's climate. Recent satellite observations have further revealed a correlation between cosmic ray flux and low cloud top temperature. The temperature of a cloud depends on the radiation properties determined by its droplet distribution. Low clouds are warm (>273K) and therefore consist of liquid water droplets. At typical atmospheric supersaturations (1%) a liquid cloud drop will only form in the presence of an aerosol, which acts as a condensation site. The droplet distribution of a cloud will then depend on the number of aerosols activated as cloud condensation nuclei (CCN) and the level of super saturation. Based on observational evidence it is argued that a mechanism to explain the cosmic ray-cloud link might be found through the role of atmospheric ionisation in aerosol production and/or growth. Observations of local aerosol increases in low cloud due to ship exhaust indicate that a small perturbation in atmospheric aerosol can have a major impact on low cloud radiative properties. Thus, a moderate influence on atmospheric aerosol distributions from cosmic ray ionisation would have a strong influence on the Earth's radiation budget. Historical evidence over the past 1000 years indicates that changes in climate have occurred in accord with variability in cosmic ray intensities. Such changes are in agreement with the sign of cloud radiative forcing associated with cosmic ray variability as estimated from satellite observations.     

Decisions, endings, and new beginnings

The Washington Watch column examines NASA shuttle developments, airline pilot age issues, development of a personnel recovery vehicle, and includes an obituary for retired Air Force General Bernard Schriever, remembered as an air and space pioneer. The discussion of NASA shuttle developments reports on the space shuttle flight schedule and NASA's ability to deliver hardware to the International Space Station, funding levels and equipment development schedules related to President Bush's mandate to visit Mars, a report on the space program by the American Academy of Arts and Sciences, and top-level management changes at NASA. The discussion of airline pilot age issues examines efforts to change mandatory retirement requirements. The discussion of personnel recovery vehicles reports on development of an aircraft designed to rescue survivors during combat search and rescue missions.     

Water and Volatile Inventories of Mercury,Venus, the Moon,and Mars

We review the geochemical observations of water, \(\mbox{D}/\mbox{H}\) and volatile element abundances of the inner Solar System bodies, Mercury, Venus, the Moon, and Mars. We focus primarily on the inventories of water in these bodies, but also consider other volatiles when they can inform us about water. For Mercury, we have no data for internal water, but the reducing nature of the surface of Mercury would suggest that some hydrogen may be retained in its core. We evaluate the current knowledge and understanding of venusian water and volatiles and conclude that the venusian mantle was likely endowed with as much water as Earth of which it retains a small but non-negligible fraction. Estimates of the abundance of the Moon’s internal water vary from Earth-like to one to two orders of magnitude more depleted. Cl, K, and Zn isotope anomalies for lunar samples argue that the giant impact left a unique geochemical fingerprint on the Moon, but not the Earth. For Mars, an early magma ocean likely generated a thick crust; this combined with a lack of crustal recycling mechanisms would have led to early isolation of the Martian mantle from later delivery of water and volatiles from surface reservoirs or late accretion. The abundance estimates of Martian mantle water are similar to those of the terrestrial mantle, suggesting some similarities in the water and volatile inventories for the terrestrial planets and the Moon.     

Observability, Eigenvalues, and Kalman Filtering

In higher order Kalman filtering applications the analyst often has very little insight into the nature of the observability of the system. For example, there are situations where the filter may be estimating certain linear combinations of state variables quite well, but this is not apparent from a glance at the error covariance matrix. It is shown here that the eigenvalues and eigenvectors of the error covariance matrix, when properly normalized, can provide useful information about the observability of the system.     

Collapse,equilibrium, and fragmentation of rotating,adiabatic clouds

Numerical calculations of the collapse of adiabatic clouds from uniform density and rotation initial conditions show that when restricted to axisymmetry, the clouds form either near-equilibrium spheroids or rings. Rings form in the collapse of low thermal energy clouds and have = T/ ¦W¦ 0.43. When the axisymmetric constraint is removed and an initial m=2 density variation is introduced, clouds either collapse to form near-equilibrium ellipsoids or else fragment into binary systems through a bar phase. Ellipsoids form in the collapse of high thermal energy clouds and have 3 0.27. The results are consistent with the critical values of for instabilities in Maclaurin spheroids, and suggest that protostellar clouds may undergo a dynamic fragmentation in the nonisothermal collapse regime.National Academy of Sciences — National Research Council Resident Research Associate.