Static and dynamic helicopter airframe analysis with NASTRAN

The use of NASTRAN at Bell Helicopter Company for structural static and dynamic analysis of a helicopter airframe is described. Analysis of airframe internal loads, main rotor isolation systems, and airframe vibration is discussed. The use of each rigid format for these types of analysis is summarized. Suggested improvements to NASTRAN to increase its effectiveness in performing helicopter airframe analysis are given

Optical and electrical measurements on UV sensitive photodiodes

The optical and electrical characteristics of the various types of photodiodes potentially useful for UV radiometers were studied. It was concluded that both GaAsP and GaP photodiodes have advantages over silicon photodiodes in terms of spectral response and UV stability. Both GaAsP and GaP have excellent electrical characteristics for low frequency radiometers, although their high capacitance could be inconvenient for high frequency applications. GaAsP is particularly good with respect to dynamic range

The structure of lightning flashes HF-UHF: 12 September 1975, Atlanta, Georgia

Simultaneous measurement of sferics at 3, 30, 139, and 295 MHz were made during thunderstorms. Wideband electronics and an analogue tape recorder continuously recorded the radiation from lightning with about 300 kHz of bandwidth. The data were obtained during the passage of a cold front. Flashing rate, burst rate and the structure of individual flashes were recorded. The record of a typical flash begins with a sudden burst of closely spaced pulses whose temporal structure is typical of the stepped leader, and ends in a large pulse suggestive of a first return stroke. The remainder of the flash consists of a sequence of pulses of varying amplitude separated by quiet periods of the order of milliseconds. The shape of these pulses and the temporal structure suggest that the first few large pulses are return strokes. Other discharges begin with widely spaced discrete pulses and resemble the preceding discharge less the leader and return stroke phase. The radiation exhibits a similar structure, at each of the frequencies monitored

Thermodynamic property measurements in reflected shock air plasmas at 12,000 - 16,000 K

Reflected shock air plasma thermodynamic properties at 12,000 to 16,000 deg

High-temperature thermal storage systems for advanced solar receivers materials selections

Advanced space power systems that use solar energy and Brayton or Stirling heat engines require thermal energy storage (TES) systems to operate continuously through periods of shade. The receiver storage units, key elements in both Brayton and Stirling systems, are designed to use the latent heat of fusion of phase-change materials (PCMs). The power systems under current consideration for near-future National Aeronautics and Space Administration space missions require working fluid temperatures in the 1100 to 1400 K range. The PCMs under current investigation that gave liquid temperatures within this range are the fluoride family of salts. However, these salts have low thermal conductivity, which causes large temperature gradients in the storage systems. Improvements can be obtained, however, with the use of thermal conductivity enhancements or metallic PCMs. In fact, if suitable containment materials can be found, the use of metallic PCMs would virtually eliminate the orbit associated temperature variations in TES systems. The high thermal conductivity and generally low volume change on melting of germanium and alloys based on silicon make them attractive for storage of thermal energy in space power systems. An approach to solving the containment problem, involving both chemical and physical compatibility, preparation of NiSi/NiSi2, and initial results for containment of germanium and NiSi/NiSi2, are presented

Measuring the Efficiency Cost of Taxing Risky Capital Income

In this paper, we derive a measure of the efficiency cost of taxing risky capital income in an infinite horizon stochastic model. The resulting measure differs from all those that have been proposed in the existing literature. It can be represented by the expression -sigma(s) T(s)c(deltaX(s)), where T(s) measures the present value of the taxes that would be paid on a unit of investment in a riskless project with the same expected depreciation rate and tax treatment as capital invested in period s, X(s), while c(X(s)) represents the certainty equivalent to the representative individual of the lottery where measures the ex post change in investment in period s due to the tax change. The paper then compares this measure with others that have appeared in the literature. We were unable to find support for the argument in Bulow-Suinmers(1984) that the efficiency cost of taxing risky capital income is much larger than that implied by the measure -sigma(s)T(s)E(deltaX(s)). In fact, we show in special cases that our measure implies a smaller efficiency cost than does the measure -sigma(s)T(s)E(deltaX(s)).

Tax Structure and Government Behavior: Implications for Tax Policy

Changes in tax policy can affect all aspects of the economy. Not only do firms and individuals change behavior, creating efficiency costs, but government expenditure choices can also change. Unless these expenditure choices had been optimal' previously, changes in response to a tax reform affect welfare and should be taken into account when designing tax policy. This paper develops a specific model of government behavior and then explores the implications of government, as well as private, behavioral responses for tax policy. In particular, we assume that government officials favor expenditure (or regulatory) choices that increase the government's budget. As a result, higher tax rates on a particular activity encourage government behavior that aids the growth of this activity. This response enables tax policy to redirect government activity in desirable directions, but it also makes Pigovian taxes on negative externalities less effective.

Conceptual design for Mobile Geological Laboratory position and heading fix system

Conceptual design of position fixing system for Mobile Geological Laboratory in Lunar Mobile Laboratory simulatio

Bitter taste stimuli induce differential neural codes in mouse brain.

A growing literature suggests taste stimuli commonly classified as "bitter" induce heterogeneous neural and perceptual responses. Here, the central processing of bitter stimuli was studied in mice with genetically controlled bitter taste profiles. Using these mice removed genetic heterogeneity as a factor influencing gustatory neural codes for bitter stimuli. Electrophysiological activity (spikes) was recorded from single neurons in the nucleus tractus solitarius during oral delivery of taste solutions (26 total), including concentration series of the bitter tastants quinine, denatonium benzoate, cycloheximide, and sucrose octaacetate (SOA), presented to the whole mouth for 5 s. Seventy-nine neurons were sampled; in many cases multiple cells (2 to 5) were recorded from a mouse. Results showed bitter stimuli induced variable gustatory activity. For example, although some neurons responded robustly to quinine and cycloheximide, others displayed concentration-dependent activity (p<0.05) to quinine but not cycloheximide. Differential activity to bitter stimuli was observed across multiple neurons recorded from one animal in several mice. Across all cells, quinine and denatonium induced correlated spatial responses that differed (p<0.05) from those to cycloheximide and SOA. Modeling spatiotemporal neural ensemble activity revealed responses to quinine/denatonium and cycloheximide/SOA diverged during only an early, at least 1 s wide period of the taste response. Our findings highlight how temporal features of sensory processing contribute differences among bitter taste codes and build on data suggesting heterogeneity among "bitter" stimuli, data that challenge a strict monoguesia model for the bitter quality