The Dollars and Sense of Continuing Education

Lifetime earnings of a high school graduate of $150 000 can be increased to $725 000 with a doctorate. Continued study is required to ?stand still? with an engineering half life of ten years. These points, among others, point to the value of investment in continued education.     

?AL Proyecto Azimut?La Industria Aeronáutica en el ámbito de la Comunidad Económica de América Latina ?AL Azimuth Project?Aeronautical Industry for the Latin-American Conmmon Market

The purpose of this paper is to promote the establishment of standards and basic requirements to direct development of preliminary orientational studies for the organic and financial structure, in the incipient period, of a Latin-American Aeronautical Industry, which is urgently needed to be incorporated into the integration plans of the Latin-American Common Market. Immediate action is recommended in view of statistical data analyzed for Mexican import and export values, for aircraft and its spare parts, that give $122 091 000 (U. S. currency) in the period from 1957 to 1964, with an average value of $6.55 per pound. Indices are also given for modern flight equipment in the range of $40 to $60 per pound, with a tendency to increase to the range of $80 to $90 per pound in the next five years.     

Theory and Modeling of Planetary Dynamos

Numerical dynamo models are increasingly successful in modeling many features of the geomagnetic field. Moreover, they have proven to be a useful tool for understanding how the observations connect to the dynamo mechanism. More recently, dynamo simulations have also ventured to explain the surprising diversity of planetary fields found in our solar system. Here, we describe the underlying model equations, concentrating on the Boussinesq approximations, briefly discuss the numerical methods, and give an overview of existing model variations. We explain how the solutions depend on the model parameters and introduce the primary dynamo regimes. Of particular interest is the dependence on the Ekman number which is many orders of magnitude too large in the models for numerical reasons. We show that a minor change in the solution seems to happen at $\mbox {E}=3\mbox {$\times 10^{-6}$}$ whose significance, however, needs to be explored in the future. We also review three topics that have been a focus of recent research: field reversal mechanisms, torsional oscillations, and the influence of Earth’s thermal mantle structure on the dynamo. Finally we discuss the possibility of tidally or precession driven planetary dynamos.     

Managing change through roadmapping [changes in aviation electronics]

Presently the USAF is operating with 90 different Model Design Series (MDS) aircraft. The 90 MDS aircraft make up a total of 5778 airframes, each with a different number of Line Replaceable Units (LRUs) which make up the avionics systems. Some of the MDSs have as few as 53 avionics LRUs while others as many as 495. The total dollar value of the USAF aircraft avionics LRUs is approximately $42.4B and $30.68B in spares. Depot repairable cost to maintain these components each year is approximately $1.2B. Each MDS is assigned specific missions and the avionics systems are developed to support those missions. Due to the evolution of mission types and user needs, change is constant for the avionics manager.     

For aerospace programs,the crises continue

The Legislative Update column reports on President Bush's supplemental budget request for the war in Iraq, the formation of a defense caucus in the House of Representatives, stabilized funding for airport security, the Department of Homeland Security budget, NASA's budget request, funding for NASA's aeronautics program, and NASA's new authorization. NASA's FY04 budget request is $15.47 billion, less than 1% more than FY03. The aeronautics program budget request for FY04 is $959 million, a decrease of 8.5% from FY03. Congress is working to introduce a multiyear authorization for NASA during the 108th session.     

Steady course for civil space in 2002

Total expenditures for space activities by civilian governments totaled $20.3 billion in 2002. National summaries by expenditure and type of flight are provided.     

The International Space Station: a question of federal funding andpolicy implications

A summary form is given of the author's full paper (ibid. vol. 33, p. 7, 1998). The ISS program is a huge investment by the U.S. government. It is estimated by NASA that the program will cost the American public more than $70 billion over a period of 30 years. Since the scientific impact of this program is relatively unknown (and uncertain), the question that policy makers will have to struggle with is whether the federal government should continue to fund the program, or to pull out from the program altogether, thus saving American taxpayers close to $30 billion. Although funding is a major concern, since the inclusion of Russia in the program, the ISS has also become a foreign policy tool. Therefore, additional questions about policy implications of the ISS program need to be addressed     

Batteries vs. alternatives for storing energy

Electric utilities need quickly-available sources of power for supplying expected and unexpected peak loads. Among useful sources have been the energy stored in water by pumping it to elevated storage reservoirs, in air compressed into underground chambers, and in batteries. A new power source, tBase-load nuclear and coal-fired steam plants generate off-peak energy for recharging the depleted storage facility. The aero-derived gas turbine, challenges the economics of these traditional energy-storage means. These turbines have been designed for aircraft where quick startup, rapid change in output power, and high reliability are essential. With a 1426°C (2600°F) turbine inlet temperature the available efficiencies are 42% in simple-cycle operation and 60% in a combined-cycle power plant. A recent 84-MW natural-gas-burning peak-power plant cost $204 per kW. Pacific Gas and Electric's Helmes River pumped-hydro plant had cost $656 per kW. The combined-cycle gas turbine plants, with their low manpower requirements, are producing power that costs less than power from nuclear power plants. We examine the performance and economics available from these new power sources     

Advances and trends in primary and small secondary batteries

Improvements in performance and reliability continue to be made in the traditional primary and secondary systems such as C-Zn, alkaline MnO ₂, Zn-air, Li-I, and sealed Ni-Cd and lead acid. In addition, two new secondary systems, Ni-metal hydride and lithium ion, have recently been introduced. They are growing rapidly in response to environmental concerns and the need for more energy density by devices. Two new rechargeable systems, Zn-air and lithium polymer electrolyte are nearing commercial production. One manufacturer has just introduced a rechargeable version of the alkaline MnO₂ system for consumer use. Lithium primary systems, such as Li-MnO₂, Li-FeS₂ and CF_x are gaining substantial market share, amounting to about $500 million in 1992. Li-silver vanadium primary cells have been developed to supply the higher currents needed by implantable medical devices such as defibrillators     

Baryons in the diffuse intergalactic medium

The baryon density of the universe _B is well measured indirectly from Big-Bang nucleo-synthesis, in particular by recent measurements of the D/H ratio in high-redshift QSO absorption systems. In addition, very recent measurements of the second maximum of the power-spectrum of the CMB fine scale anisotropy allow to constrain _B at z1000. Both results agree and yield _B=0.02h ^–2. Direct measurements of the diffuse baryonic component (intergalactic gas) at redshifts z=3 and 1.5 and in the local universe are reviewed and shown to be much more difficult. Available observations are consistent with the hypothesis that at z=3 and possibly still at z=1.5 nearly all baryons are located in the highly ionized L forest component, while at later epochs the contribution of a low-density, shock-heated component (10⁵–10⁷ K), the so called warm-hot intergalactic medium (WHIM), occupies with decreasing redshift an increasing fraction of all baryons. Methods to detect this component and the difficulty to make quantitative estimates are described. In the local universe of all baryons may be hidden in the WHIM. Yet at z=1.5, this component contains at least a factor of 5 less material.     

In this issue technically: 12th DASC report-our archaic airtransport control: What can be done?

Commercial airplanes in the Fiji archipelago fly straight from take-off to their destination, using global-positioning-satellite (GPS) receivers. So can general-aviation airplanes in the United States. Commercial airplanes on U.S. transcontinental routes fly dog-legs from city to city. An airplane flying across the Atlantic occupies an exclusive 10,000-cubic-mile moving box. These practices, plus waiting for take-off and landing opportunities, cost United Airlines $2 billion a year. The available USAF flight-management technology is reviewed to see what can be adapted for use in management of the commercial air-space. The problems and plans for implementing a seamless world-wide flight management system, are examined     

Microtab对风力机叶片翼型气动特性的影响研究

选取S814风力机叶片翼型进行了二维几何建模和计算网格划分,通过求解Navier—Stokes方程对翼型的空气动力特性进行了数值模拟,并与实验数据进行了对比分析,验证了计算模型及求解器的可靠性。对S814翼型后缘加载Microtab进行了气动数值模拟,分析了其流场和空气动力特性。计算结果表明：风力机叶片翼型后缘加载Mierotab可以改变翼型的环量,达到增升的目的,与此同时伴随一定阻力的增加,但升阻比得到小幅的提升。     

Computerized Medical Devices: Trends, Problems, and Safety

Virtually all of the medical devices utilizing electronics will contain a micro or minicomputer by 1990. These devices accounted for $7 billion in U.S. sales in 1984. Their capabilities can provide the means for new or greatly improved medical procedures, and ensure greater patient safety. However, these benefits can easily be compromised if ``computer safety' is not practiced in the design, manufacturing, testing and clinical use of these devices. Along with a trend to wider usage, the number of recalls of medical devices due to computer-related problems has approximately doubled in the last five years. ``Computer-caused' problems are often not recognized or reported as such, resulting in an underestimation of the prevalence of this type of problem. Our study of technical factors causing problems in computerized devices revealed that software quality assurance (SQA), the quality of the ac power, and electromagnetic interference are primary factors. Selected design and QA techniques that are well-known in military-aerospace industries can be used to prevent the most prevalent problems occurring in computerized medical devices, without significantly affecting overall device manufacturing costs.     

Global Positioning System-the newest utility

The Global Positioning System (GPS) has become the high tech utility of the 20th century. It was developed by the US Department of Defense as a precise navigation reference for the military services. Although the signal available to civilian users had been purposely degraded in what is called selective availability (SA), it is one of a few technological success stories that had positive unintended consequences. Recent announcements indicate that this SA impediment has been removed. GPS currently has a huge civilian market in commercial and private aviation, ship navigation, mapping and surveying, telecommunications position determination, and recreational boating and hiking. By 2003 sales of GPS based products are expected to be $16 billion     

Investment Costs of Terrestrial Long-Haul Telecommunication Facilities

The investment costs of long-haul, modern, radio relay and coaxialcable systems, as determined from data submitted to the Federal Communications Commission, are presented. Formulas to determine costs per voice-circuit-mile, and per television-channel-mile, are developed. The specific facilities investigated are the TD-2, TD-3, and TH radio relay systems, and the L-3 12-tube and L-4 20-tube coaxial cable systems. The radio relay systems are significantly, with one exception, less expensive than coaxial cable systems over their design capacity ranges. The L-4 20-tube coaxial cable system (32 400 voice circuits) and the TD-3 radio relaysystem (12 000 voice circuits) have approximately equal investment costs per voice-circuit-mile ($3.40) at full capacity.     

缺口件振动疲劳寿命预测的频域法和时域法的比较与分析

以缺口件为研究对象,在窄带信号下分别采用频域法和时域法预测缺口件的振动疲劳寿命。频域法选用Rayleigh模型和Dirlik模型作为应力变程概率密度p(S)模型,采用Miner累积损伤准则计算振动疲劳寿命。时域法通过傅里叶逆变换将结构危险点处的应力响应功率谱密度函数转为应力-时间历程样本,采用雨流循环计数结合Miner累积损伤准则,得到一个疲劳寿命样本,计算多个样本取均值作为振动疲劳寿命。计算结果和试验结果表明:时域法的精度较高,但工作量较大;选用 Rayieigh 模型和 Dirlik 模型的频域法预测寿命精度接近,比时域法的精度略差,但工作量较小。     

A System for the Measurement of the Amazon

The System for the Vigilance of the Amazon (SIVAM) is a $1.4 billion dollar project of Brazil aimed at the development and deployment of a high-technology system-of-systems to perform monitoring, protection, and control of the land, air, and water resources of the Brazilian Amazon region. The primary challenge of the SIVAM project is to perform remote sensing and communications over a vast and undeveloped land area. The SIVAM network meets this challenge through an extensive network of Air Traffic Control/Surveillance Radars, Environmental Sensors, Communications Systems, Airborne Sensor Systems, and Coordination Centers. Now fully operational, the SIVAM system is the world's largest fully integrated remote monitoring system of the environment and provides critical information on a timely basis to the Brazilian government, law enforcement agencies, and to commercial, educational, and research groups.