奥地利哈尔斯塔特小记

时光倒流约两个世纪,德国著名科学家和探险家亚历山夫.冯.洪堡,来到这个峰峦环抱的湖区,面对旖旎的湖光山色,留下也这是"世界上最美丽的湖泊"的赞叹,引发了后人飞越的神思和向往。     

Correction to: Mission to Planet Earth: The First Two Billion Years

Space Science Reviews - The Ionospheric Connection Explorer (ICON) mission makes measurements in near-Earth space that provide knowledge of the state of the ionosphere. From the vantage of...     

Navigation: ships to space

An examination is made of old and new navigation technology that considers most factors affecting this technology, including cost, accuracy, autonomy, time-delay, global coverage, and the human interface. The author reviews cartography and the navigation of land, ship, air, and space vehicles, concluding with a forecast of navigation in the twenty-first century. An extensive annotated bibliography is included     

Energy efficiencies: Rickshaw to 757

Transportation efficiencies in terms of passenger miles per gallon are examined for a wind range of transportation methods: muscle-powered (running, swimming, flying), human-powered machines (bicycles), and fuel-consuming machines (trains, ships, sailplanes). The practicality of vehicles that can deliver 1000 passenger miles per gallon is evaluated     

物流--实现电子商务的桥梁

通过分析电子商务物流的产生与发展历程，结合国外电子商务物流的现状和我国目前物流模式存在的问题，提出完善我国物流体系建设的一些建议。     

Managing: From Invention to Hardware

A definition of the five categories of technical effort in the Air Force; an establishment of a new subcategorization of basic research (unbounded and guided); and a discussion in detail of the following, with cross-references to like problems in industrial concerns: 1) basic research, 2) exploratory development, 3) advanced development, 4) the role of the manager, 5) the manager's desirable and undesirable traits, 6) the role of the scientist and engineer, 7) the organization, and 8) future trends.     

Designing to MIL-STD-2165: Testability

The V-22 avionic hardware is the first to be designed under MIL-STD-2165 testability program requirements. This paper presents an overview of the avionics design-for-testability approach and lessons learned to date relative to the application of MIL-STD-2165. The paper will discuss incorporation of testability requirements up front in the avionics design which will drive the supportability philosophy at both the Organizational and Depot levels of maintenance. The paper will compare previous avionics hardware testability requirements versus those applied to the V-22 avionics and highlight areas of improvement. A discussion of testability design impacts on reduced level of testing (i.e. WRA/SRA/System) will be included. In addition, the paper discusses an innovative approach to meeting the user requirements for a man-portable forward deployed maintenance capability that forms the basis for a two level support scenario (Organizational and Depot). The innovation comes from the fact that the on-board Central Integrated Checkout system will provide data as well as fault isolation and will use this data as a mechanism to reduce the size and complexity of the stimulus and measurement hardware at either the Organizational or Depot level depending on the deployment requirements.     

发动机短期租赁市场被看好

2006年9月,威利斯租赁融资公司宣布建立新的北美备用发动机共享库,使得发动机可以真正地进行短期租赁,而且这些发动机都有完整的数据记录和最终的合同文件.     

From Mercury to Pluto: A Common Approach to Mission Timekeeping

The successful launch of the New Horizons spacecraft for a rendezvous with Pluto and Charon and the continuing progress of the MESSENGER spacecraft toward Mercury now positions mankind to unlock mysteries of our solar system from Mercury to Pluto and beyond. Both missions, though very different in concept, use the same generic timekeeping system design. This paper explores how we maintain time on these spacecraft and how we establish on the ground the correlation between spacecraft time and Earth time. It further reviews the sub-millisecond correlation accuracy that has been demonstrated for the MESSENGER mission and the time accuracy we expect to achieve for that mission at Mercury and for the New Horizons mission at Pluto-Charon     

Software testing: from theory to practice

This paper is about the disparity between what is known and what is being learned in academia and what is being used in industry. The author believes there are many reasons. Some of these represent accidental and some essential problems. Most are part of a general issue of quality in the software products. Most problems that make it more difficult to apply testing techniques are part of a larger problem which make them more cost-effective to produce high quality software. The author presents a list of reasons industry does not use the highly advanced, and in some cases, highly developed software testing techniques that are available. The problems are divided into three broad categories: problems in industry; problems in academic research and education; and problems in the interface between the two     

Applications of level crossing theory to target intervisibility: to be seen or not to be seen?

Here we discuss intervisibility (the existence of an unobstructed line of sight (LOS) between two points) accounting for the vertical and horizontal errors in the estimated locations of both points as well as elevation errors in the database of the terrain that could obstruct the LOS between these points. The errors are first simply treated as a "white" noise sequence: we assume no correlation between the intervisibility at two different times, and the probability of an instantaneous intervisibility event is in this case developed. This is useful; but perhaps of greater concern is whether or not a target remains visible long enough and/or often enough that its motion can be tracked? Consequently, we present a second treatment in which the errors are stochastic processes of a certain bandwidth, and both the probability density function (pdf) of an intervisibility interval and the average number of intervisibility intervals over a certain time period are developed.     

Information security: from reference monitors to wrappers

Information system security has turned out to be much more challenging than at first thought. In the 1980s, a great deal of energy was expended in an attempt to create a broad market of security-enhanced systems. This market, however, did not develop, and most computer systems today include only rudimentary security mechanisms. New technologies, such as extensible systems and security wrappers, hold promise to reintroduce security as an effective and ubiquitous system service     

军民合作带来军机维修的整体性

提高军机的战备状态、缩小供应链的规模和降低成本的关键是基于性能的后勤保障(PBL)合同.可使军民合作更为密切,可以合理的价格为部队提供所需的可用率.     

Introduction to Solar Magnetism: The Early Years

The year 2008 marked the one hundredth anniversary of the observational discovery by George Ellery Hale of magnetic field in sunspots (Hale in Astrophys. J. 28:315–343, 1908). This observation, the first to suggest a direct link between the best-known variable features on the Sun and magnetism, started a line of research that has widened considerably over the last 100 years and is continuing today. Knowledge about all aspects of the Sun has increased in a remarkable way over the past few decades. Variations in the appearance of the Sun and its corona, as well as deeper sources of quasi-regular and chaotic changes that make up solar variability have been extensively documented by both ground-based and space-based solar observatories. It has been recognized that solar magnetism is the key phenomenon that drives solar variability. The workshop devoted to the origin and dynamics of solar magnetism held in the International Space Science Institute in Bern, Switzerland, from 21 to 25 January 2008 reviewed the status of the field and has led to this volume that brings together the best available knowledge and understanding of solar magnetism 100 years after Hale’s pioneering paper. This introductory paper gives an outline of the history of research into solar variability up to the work of Hale and his colleagues. The achievements of the past decades are discussed extensively in the other contributions to this volume.     

TORCH: from strategic planning to real-time optimisation

To ensure that available capacity is managed as efficiently as possible, TORCH promotes to exchange more transparently available data to ensure that the distribution of information and decision making is located where it is most effective. This article presents an overview of the work carried out, with the aim of avoiding unstable scheduling delays through open, cooperative management of scarce ATM capacity.