ARTEMIS: a positioning system

ARTEMIS is an acronym for: automatic ranging theodolite emitting microwave signals. The reference direction in azimuth is obtained by mounting a theodolite on the antenna, aiming it at a known position in the field and adjusting the azimuth reading. About 300 ARTEMIS sets, in various configurations, have been sold and, in spite of its much higher price when compared with DGPS, sales are continuing. Many sets were made gastight in view of security requirements on platforms. It is shown how a plotter can determine the course driven by a car on the road. The pen indicates accurately where the car was on the map. Advances in the technique of optical angle encoders are discussed     

World Space Congress: a vision quest

The World Space Congress (WSC) in October, 2002, brought together luminaries, aerospace engineers, students, and scientists to discuss strategies for reviving the world's space agency. WSC lectures and plenary sessions focused on future research in space. Among topics discussed are the use of the Hubble Space Telescope to scan for habitable planets and obtain data about the beginning of the universe, new weather satellites, planetary protection from comets or asteroids, exploration and establishment of colonies on the Moon and Mars, medical advances, the role of space exploration in the world economy.     

Ll-CFAR: a flexible and robust alternative

A new family of constant false alarm rate (CFAR) processors is introduced. An Ll-CFAR forms its noise power estimate by linearly filtering ranked samples from the reference set; the weights of this combination, however, depend not only on the rank, but also on the relative proximity of the sample to the cell under test. From the class of Ll-CFARs may be chosen members which effectively censor spurious targets; members which exhibit impressive control of false alarm in the presence of a clutter edge; and members which are robust against both such inhomogeneities. While the design of such schemes is involved, their implementation is not significantly more burdensome than that of plain ordered statistic CFAR (OS-CFAR). After a discussion of the stochastic training of Ll-CFAR, the performance is thoroughly assessed under the most commonly encountered instances of environmental conditions, and compared with those of classical CFAR techniques     

Behavioral science: a progress report

A prominent neuroscientist A. Damasio has observed that “More may have been learned about the brain and the mind in the 1990s... than during the entire previous history of psychology and neuroscience” (1999). This progress, which should continue at an exponentially increasing pace as we move into the 21^st century, sets the stage for another revolution-in the scientific formulation of intentional behavior. Just as applied sciences such as fluid mechanics and solid-state electronics benefited from breakthroughs in physics, so it may be expected that social psychology and economics, for example, will similarly benefit from our expanding knowledge of psychosomatic and psychological function. Economics, however, with its basic concepts dating from the nineteenth century, must endure an extensive renewal. Toward this end, a new mathematical theory of behavior was formulated in the early 1990s based on the contributions of prominent psychologists and economists over the past two centuries. Presentation of the new approach at international conferences continued in 2000 with attention moving beyond the fundamentals into macroeconomic concerns including business cycles, productivity, and unemployment     

Open Systems: a process for achieving affordability

A major factor that will drive the definition and design of future avionics systems is affordability. Affordability is being addressed on numerous fronts such as hardware re-use, software re-use, COTS leveraging, and reduced cycle times. Each of these thrusts provide potential cost saving along with unique challenges. What is needed is a process that integrates these initiatives while ensuring the overall system objectives are achieved. An Open Systems-based process is key to integrating these initiatives and balancing affordability and system performance goals. Although Open Systems are being widely recognized as a key to affordability, most interpret Open Systems as a set of system attributes that need to be achieved. There are numerous claims of vendors saying they have an Open Systems architecture; or how their system will evolve to an Open Systems architecture. This emphasis is not on increasing affordability, but on attaching a politically-correct label to their product. In this paper, we focus on the Open Systems process as the key to affordability. An Open Systems process is based on Open Systems principles. This paper discusses the Open Systems principles and process in detail and shows how this process integrates numerous affordability initiatives     

Towards a new paradigm: from a quasi-steady description to a dynamical description of the magnetosphere

A great deal of the research done on the dynamical process of the solar wind- magnetosphere interaction is based on large-scale, quasi-steady theoretical models, such as the classical reconnection model. However, it can be argued that the theoretical and observational foundations of these commonly believed paradigms are not always strong, and support for these models is sometimes weak, controversial or inconsistent. This paper discusses the need for a transition from an oversimplified quasi-steady paradigm towards a more realistic one including the dynamics of MHD waves and wave packets. The effects of localized wave packets may be most important in active plasma regions, where ideal MHD breaks down and localized, time-dependent processes become dominant. New insights into the theories of field-aligned current generation, auroral particle acceleration and the concept of reconnection may be found by including MHD wave propagation and wave packet dynamics.     

Carrier-wave interference to Loran-C: a statistical evaluation

Loran-C is a pulsed, hyperbolic radio aid for long-range marine, air, and land navigation. The worldwide expansion of Loran-C, especially in Europe, has focused attention on carrier-wave interference to the system. The effects of a multiplicity of carrier-wave interferers (CWIs) on receiver timing measurement accuracy are considered. Both the phase tracking and the cycle-selection performance of receivers are quantified in terms of the probabilities that they will operate correctly within the arbitrarily set error limits. Characteristic functions (CFs) are used to compute these probabilities. Analyses and results are presented for typical situations. The relative sensitivity of the phase tracking and cycle-selection functions to interfering signals are discussed     

Shared technologies: a new roadmap

The long-term goal of the USAF Shared Technologies Program is to facilitate the development of a roadmap for technology insertion on the wide variety of legacy Automatic Test Equipment (ATE) accumulated by the USAF over the past 30 years. A successful roadmap will provide for Operation & Support (O&S) cost reduction, preserve Test Program Set (TPS) development investments, and evolve in concert with the DoD Executive Agent for Automatic Test Systems (ATS) initiatives and commercial industry, and (e.g., NxTest) changes. The near-term objective of this phase of the USAF Shared Technologies Program is to demonstrate the feasibility of incorporating available commercial technology into the Radio Frequency (RF) Mobile Electronic Test Set (RFMETS). The RFMETS was originally delivered to the USAF during the early 1990s and is used to support a variety of C-130 avionics including the APQ-170 and APQ-180 Radar Systems.     

General direction-of-arrival estimation: a signal subspace approach

A high-resolution algorithm is presented for resolving multiple incoherent and coherent plane waves that are incident on an array of sensors. The incident sources can be a mixture of narrowband and broadband sources, and, the geometry of the array is unrestricted. The algorithm makes use of a fundamental property possessed by those eigenvectors of the array spectral density matrix that are associated with eigenvalues that are larger than the sensor noise level. Specifically, it is shown that these eigenvectors can each be represented as linear combinations of the steering vectors identifying the incident plane waves. This property is then used to solve the important special cases of incoherent sources incident on a general array and coherent sources incident on an equispaced linear array. Simulation results are presented to illustrate the high-resolution performance achieved with this approach relative to that obtained with MUSIC and spatial smoothed MUSIC in which the coherent-signal-subspace focusing method is used     

Directionalet:一种新的多尺度几何分析方法

方向小波是继轮廓小波之后又一种新的基于多尺度几何分析的图像处理工具。在对有关方向小波文献的理解和综合的基础上,阐述了方向小波的基本理论框架及其应用,总结了方向小波的优缺点,最后基于对方向小波的理解,展望了方向小波在图像处理中的应用。     

Radar target identification using the bispectrum: a comparativestudy

Radar target identification is performed using time-domain bispectral features. The classification performance is compared with the performance of other classifiers that use either the impulse response or frequency domain response of the unknown target. The classification algorithms developed here are based on the spectral or the bispectral energy of the received backscatter signal. Classification results are obtained using simulated radar returns derived from measured scattering data from real radar targets. The performance of classifiers in the presence of additive Gaussian (colored or white), exponential noise, and Weibull noise are considered, along with cases where the azimuth position of the target is unknown. Finally, the effect on classification performance of responses horn extraneous point scatterers is investigated     

Human-computer interaction in aeronautics: a cognitive engineering perspective

This article presents issues and perspectives that are currently emerging from the evolution of new technology integration in aircraft cockpits. It advocates the need for cognitive engineers and human-computer interaction specialists to rationalize emerging practice in aviation, to better understand the current socio-technical evolution and to contribute in the human-centered design of the next generation aircraft. It also introduces six articles that show these trends and introduce some controversial discussions on various alternative solutions.     

Censoring sensors: a low-communication-rate scheme for distributeddetection

We consider a new scheme for distributed detection based on a “censoring” or “send/no-send” idea. The sensors are assumed to “censor” their observations so that each sensor sends to the fusion center only “informative” observations, and leaves those deemed “uninformative” untransmitted. The main result of this work is that with conditionally independent sensor data and under a communication rate constraint, in order to minimize the probability of error, transmission should occur if and only if the local likelihood ratio value observed by the sensor does not fall in a certain single interval. Similar results are derived from Neymarr-Pearson and distance-measure viewpoints. We also discuss simplifications for the most interesting case that the fusion center threshold is high and the communication constraint is severe. We compare censoring with the more common binary-transmission framework and observe its considerable decrease in communication needs. Finally, we explore the use of feedback to achieve optimal performance with very little communication     

Microwave landing system: a pilots point of view

The author describes the MLS installation on runway 19L at Mid-Continent Airport, Wichita, Kansas, which has been operational since mid-1987. He describes the MLS equipment installation in his aircraft, which is one of a number of aircraft in the Wichita area that have been equipped with MLS equipment and routinely utilize the system. He summarizes his operational experience with the system. He reports complete satisfaction and increased versatility as a result of the guidance information provided     

Reconnection and Waves: A Review with a Perspective

This review is intended to help prepare a new stage of wave studies in the context of magnetic reconnection. Various results that have accumulated would not let the two-dimensional, steady and laminar magnetic reconnection to remain as the standard model. Emphasis on three-dimensional, temporally varying, and turbulent effects is growing and this fact tells that the effects of waves in various frequency ranges deserve further attention in the context of magnetic reconnection. In this review, by setting a perspective, selected recent topics are reviewed and the ways in which these can be viewed as the stepping stones towards a new research horizon of magnetic reconnection are discussed.     

Synthetic vision: a prototype display concept for commercial aircraft

The synthetic vision implementation discussed in this paper comprises elements in the navigation display, the vertical profile display, and the primary flight display. The design rationale is provided based on an overview of the intended functions, options to implement these functions, and the justifications used in the selection of a specific option.     

Global energy issues affecting aeronautics: a reasoned conjecture

This paper is a reasoned conjecture of the future up to 2050 AD including estimates of energy supply and consumption, transport system developments and corresponding pollution effects. Results of the logistic substitution methods (Volterra–Lotka) are used in forecasting trends in innovation, transport and energy. Later work on normative forecasts is also included. The future of aeronautics cannot be isolated from events in other transport modes which together create the major problem of crude oil replacement during the next century. Natural gas will be the dominant energy source for the next 80 years and a major question is how best to use it for aviation.The work on which this paper is based was started in 1992 to answer the following questions:

• 1. Is the future oil shortfall sufficient to restrict aviation traffic and growth in the next 50 years?
• 2. If so, what is its substitute?
• 3. Can a substitute be obtained cheaply enough to free aviation from future kerosine shortages?
• 4. Is it paramount to change to liquid hydrogen fuel to avoid future fuel shortage in aeronautics, incidentally conferring possible environmental advantages?

There was no adequate evidence available to answer these questions, hence a method was devised to bring together several sets of partial data that contributed to the solution. The essence is to use the mean annual growth rate of traffic or energy over a future period as a pseudo-independent variable. This allows the inclusion of alternative high and low estimates of all the important quantities involved.     

STEP: a tool for estimating avionics life cycle costs

An overview is presented of how the US Air Force has had significant success in the estimation of life cycle costs (LCC) for avionics hardware and software using the Standardization Evaluation Program (STEP) model for estimating operating and support (O&S) costs. The capabilities of the existing STEP model as well as ongoing enhancements to provide a total LCC estimating methodology are described. In addition to the standard cost reports, STEP has the capability to assess the impact of reliability on life cycle cost. Another unique feature of the STEP model is the capability to assess the impact of retest OK (RTOK) on life cycle costs. The acquisition enhancement is being accomplished in three parts each of which will produce a distinct, usable product. The three products are an automated database, an analogy estimating capability, and a parametric estimating technique. Each is briefly discussed