The Electrically Small Elliptical Loop with an Oblate Spheroidal Core

The fundamental properties of an electrically small elliptical loop wound on an oblate spheroidal core are calculated using quasi-static theory. Closed-form expressions are derived for the elements of a complete equivalent circuit, including the inductance and capacitance, and radiation, conductor, and core-loss resistances. It is shown that the bandwidth and efficiency are greatly increased by the use of a ferrite core. Losses in the core are computed for two low-loss ferrites. Although the primary objective is to simplify the design of a transmitting antenna for use in the lower part of the HF band, 2-4 MHz, the theory presented is equally valid for the design of receiving antennas and for other frequencies.     

Response to Comment on “Development of a High-Pressure Aerodynamic Lens for Focusing Large Particles (4–10 μm) into the Aerosol Time-of-Flight Mass Spectrometer”

Copyright 2015 American Association for Aerosol Research     

Analysis of Aerosols from the World Trade Center Collapse Site,New York,October 2 to October 30, 2001

The collapse of the World Trade Center (WTC) buildings #2 (South Tower), #1 (North Tower), and #7 created an enormous collapse pile which emitted intense plumes of acrid smoke and dust until roughly mid-December, when the last spontaneous surface fire occurred. We collected particles by size (8 modes, ≈12 to 0.09 micrometers diameter) and time (typical resolution of 1 to 3 h) from October 2 until late December at the EML 201 Varick Street site roughly 1.8 km NNE of the collapse site and 50 m above ground level. Here we show some of the 70,000 mass and elemental data from the time period October 2 through October 30. Identification of a WTC collapse pile source for aerosols seen at the receptor site were based upon the simultaneous presence of finely powdered concrete, gypsum, and glass with intense very fine combustion mode mass episodes concurrent with winds from the southwest quadrant. The results, derived from seven independent beam-based analytical techniques, showed that while PM₁₀ and PM_2.5 24 h values rarely, if ever, violated federal air quality standards, WTC-derived plumes swept over lower Manhattan Island, resulting in intense aerosol impacts of duration a few hours at any one site. The WTC plume resembled in many ways those seen from municipal waste incinerators and high temperatures processes in coal-fired power plants. The size fractions above 1 micrometer contained finely powdered concrete, gypsum, and glass, with sootlike coatings and anthropogenic metals, but little asbestos. Composition in the very fine size range (0.26 > D_p > 0.09 μm) was dominated by sulfuric acid and organic matter, including polycyclic aromatic hydrocarbons (PAHs) and their derivatives, and glasslike silicon-containing aerosols. Many metals were seen in this mode, most, but not all, at low concentrations. The concentrations of very fine silicon, sulfur, and many metals, as well as coarse anthropogenic metals, decreased markedly during October, probably in association with the cooling of the collapse piles. Values of very fine elements seen in May, 2002 at the WTC site were only a few percent of October values.     

Bridging boundaries: CORBA in perspective

Applications that cross the boundaries of different computing machines, operating systems, and programming languages are increasingly the norm. As a result, the need for what might be called bridging technologies to develop software that works across heterogeneous environments has become more compelling. The Common Object Request Broker Architecture is one such technology that is both robust and commercially available. CORBA essentially describes how client applications can invoke operations on server objects using the services of an intermediary known as an Object Request Broker, or ORB. This article introduces CORBA by describing its key components. It then reviews the boundaries it helps to bridge. It concludes by comparing CORBA with a number of other bridging technologies available today     

The design of a collision avoidance system for use by Pilots operating on the airport ramp and in taxiway areas

Ground collisions have serious implications from both a safety and a commercial perspective. This paper reports on human computer interaction (HCI) research related to the advancement of a collision avoidance system, for use by Pilots operating on the airport ramp and in taxiway areas. Primarily, this paper focuses on the key findings of this research and the emerging HCI design solution.     

Interpretability of graphic symbols as a function of context and experience factors.

10 of the graphic symbols for vehicle and equipment operation developed by an industrial design firm were tested for ease of interpretation in context and in isolation. Ss were 30 male mechanical engineering students who differed in their extent of familiarity with such equipment. As hypothesized, the symbols were more often correctly identified in context and by Ss with relevant prior experience. Symbols maintained the same relative order of difficulty under both context and no-context conditions, a difficulty which ranged from 100% correct responses to only a few correct responses. It is concluded that empirical validation of effectiveness is a necessary, although often neglected, step in the symbol development process. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The impact of lean production and related new systems of work organization on worker health.

New systems of work organization, such as lean production and total quality management, have been introduced by employers throughout the industrialized world to improve productivity, quality, and profitability. However, few studies have examined the impact of such systems on occupational injuries or illnesses or on job characteristics related to job strain, which has been linked to hypertension and cardiovascular disease. The studies reviewed provide little evidence to support the hypothesis that lean production "empowers" auto workers. In fact, auto industry studies suggest that lean production creates intensified work pace and demands. Increases in decision authority and skill levels are modest or temporary, whereas decision latitude typically remains low. Thus, such work can be considered to have job strain. In jobs with ergonomic stressors, intensification of labor appears to lead to increases in musculoskeletal disorders. The evidence for adverse health effects remains inconclusive for related new work systems in other industries, such as modular manufacturing or patient-focused care. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Maximum zeros scheduling for satellite switch TDMA

A scheduling technique suitable for preassignment in satellite switched time division multiple access (SS-TDMA) systems is presented. As many uninterrupted bursts as are feasible are transmitted per configuration of the switch matrix. For small switch matrices (up to 6*6) this technique usually requires fewer reconfigurations than previous methods.<>