Nuclear reactor descriptions for space power systems analysis

For the small, high performance reactors required for space electric applications, adequate neutronic analysis is of crucial importance, but in terms of computational time consumed, nuclear calculations probably yield the least amount of detail for mission analysis study. It has been found possible, after generation of only a few designs of a reactor family in elaborate thermomechanical and nuclear detail to use simple curve fitting techniques to assure desired neutronic performance while still performing the thermomechanical analysis in explicit detail. The resulting speed-up in computation time permits a broad detailed examination of constraints by the mission analyst

Hedge Funds With Style

The popular perception is that hedge funds follow a reasonably well defined market-neutral investment style. While this long-short investment strategy may have characterized the first hedge funds, today hedge funds are a reasonably heterogeneous group. They are better defined in terms of their freedom from the constraints imposed by the Investment Company Act of 1940, than they are by the particular style of investment. We study the monthly return history of hedge funds over the period 1989 through to January 2000 and find that there are in fact a number of distinct styles of management. We find that differences in investment style contribute about 20 per cent of the cross sectional variability in hedge fund performance. This result is consistent across the years of our sample and is robust to the way in which we determine investment style. We conclude that appropriate style analysis and style management are crucial to success for investors looking to invest in this market.

TEXES Observations of M Supergiants: Dynamics and Thermodynamics of Wind Acceleration

We have detected [Fe II] 17.94 um and 24.52 um emission from a sample of M supergiants using TEXES on the IRTF. These low opacity emission lines are resolved at R = 50, 000 and provide new diagnostics of the dynamics and thermodynamics of the stellar wind acceleration zone. The [Fe II] lines, from the first excited term, are sensitive to the warm plasma where energy is deposited into the extended atmosphere to form the chromosphere and wind outflow. These diagnostics complement previous KAO and ISO observations which were sensitive to the cooler and more extended circumstellar envelopes. The turbulent velocities, Vturb is about 12 to 13 km/s, observed in the [Fe II] forbidden lines are found to be a common property of our sample, and are less than that derived from the hotter chromospheric C II] 2325 Angstrom lines observed in alpha Ori, where Vturb is about 17 to 19 km/s. For the first time, we have dynamically resolved the motions of the dominant cool atmospheric component discovered in alpha Ori from multi-wavelength radio interferometry by Lim et al. (1998). Surprisingly, the emission centroids are quite Gaussian and at rest with respect to the M supergiants. These constraints combined with model calculations of the infrared emission line fluxes for alpha Ori imply that the warm material has a low outflow velocity and is located close to the star. We have also detected narrow [Fe I] 24.04 um emission that confirms that Fe II is the dominant ionization state in alpha Ori's extended atmosphere.Comment: 79 pages including 10 figures and 2 appendices. Accepted by Ap

A Complete Atlas of HI Absorption toward HII Regions in the Southern Galactic Plane Survey (SGPS1)

We present a complete catalog of H I emission and absorption spectrum pairs, toward H II regions, detectable within the boundaries of the Southern Galactic Plane Survey (SGPS I), a total of 252 regions. The catalog is presented in graphical, numerical and summary formats. We demonstrate an application of this new dataset through an investigation of the locus of the Near 3kpc Arm.Comment: Accepted for publication by ApJS Feb 6, 2014. Data files and Figure Set (252 images) to appear in the on-line version of the journa

Entrepreneurs'' attitude towards the computer and its effect on e-business adoption

This paper presents research exploring further the concept that many SMEs do not adopt computer based technologies due to decision maker's negative attitudes towards computers generally. Importantly, by assessing the entrepreneur's belief structure, we provide quantitative evidence how SMEs, particularly micros, are affected. Earlier research that addresses technology acceptance model (TAM) suggests that TAM parameters are particularly influential factors of e-commerce adoption, as perceived by top managers of SMEs. The model we develop is tested using a sample of 655 enterprises. The information was gathered, via a telephone survey of UK SMEs, from decisions makers in the enterprise. Technically, the paper uses k-means cluster analysis to segment respondents using the TAM perceptions, ease of use, usefulness and enjoyment. Based on two determined segments we look at the differential rate of adoption of internet, and the potential adoption of new e-collaborative technologies like video conferencing and electronic whiteboards. The diffusion of internet for low IT utility (LIT) segments was considerably slower than in the high utility segment (HIT). Similarly, the anticipated adoption of e-collaboration technologies was much lower for LIT than HIT. Interestingly, we find that LIT is populated by more micro SMEs than HIT. The results we present are limited however as our sample is considerably underweight in micro SMEs, suggesting that the problem may be much larger in the economy than our model predicts. For policy makers, this research confirms the value of knowledge transfer programs to SMEs in the form of technology support. Our research shows that organisations which have dedicated IT support will tend to be more advanced technologically than those that do not. The implication for entrepreneurs is if they can be persuaded that a technological route is beneficial to them, and that suitable support can be provided via KT, then operational efficiency gains could be made. This paper contributes to knowle

Adaptive Demodulation in Differentially Coherent Phase Systems: Design and Performance Analysis

Adaptive Demodulation (ADM) is a newly proposed rate-adaptive system which operates without requiring Channel State Information (CSI) at the transmitter (unlike adaptive modulation) by using adaptive decision region boundaries at the receiver and encoding the data with a rateless code. This paper addresses the design and performance of an ADM scheme for two common differentially coherent schemes: M-DPSK (M-ary Differential Phase Shift Keying) and M-DAPSK (M-ary Differential Amplitude and Phase Shift Keying) operating over AWGN and Rayleigh fading channels. The optimal method for determining the most reliable bits for a given differential detection scheme is presented. In addition, simple (near-optimal) implementations are provided for recovering the most reliable bits from a received pair of differentially encoded symbols for systems using 16-DPSK and 16- DAPSK. The new receivers offer the advantages of a rate-adaptive system, without requiring CSI at the transmitter and a coherent phase reference at the receiver. Bit error analysis for the ADM system in both cases is presented along with numerical results of the spectral efficiency for the rate-adaptive systems operating over a Rayleigh fading channel.Comment: 25 pages, 11 Figures, submitted to IEEE Transactions on Communications, June 1, 201

The search for innovators and early adopters of e-collaborative technologies within small and medium sized enterprises in the UK

New product diffusion theory predicts that innovators and early adopters are critical to the success of new innovations. The rate at which enterprises adopt e-Science technologies must therefore rely upon reliable market intelligence so that the critical early stages of adoption are successfully navigated by developers and planners. Failure to understand attitudes towards new technologies can lead to even useful technologies being under-adopted. This paper applies a survey based methodology to develop estimates of demand for web based virtual Collaborative technologies. We show that approximately 76% of the 1029 firms that we interviewed are technologically ready to deploy these technologies. We also show that 10% of all firms are ready look at these technologies as solutions to collaborative problem solving

Fees on Fees in Funds of Funds

Funds of funds are an increasingly popular avenue for hedge fund investment. Despite the increasing interest in hedge funds as an alternative asset class, the high degree of fund specific risk and the lack of transparency may give fiduciaries pause. In addition, many of the most attractive hedge funds are closed to new investment. Funds of funds resolve these issues by providing investors with diversification across manaager styles and professional oversight of fund operations that can provide the necessary degree of due diligence. In addition, many such funds hold shares in hedge funds otherwise closed to new investment allowing smaller investors access to the most sought-after managers. However, the diversification, oversight and access comes at the cost of a multiplication of fees paid by the investor. One would expect that the information advantage of funds of funds would more than compensate investors for these fees. Unfortunately, individual hedge funds dominate fund of funds on an after-fee return or Sharpe ratio basis. In this paper we argue that the disappointing after-fee performance of some fund of funds may be explained by the nature of this fee arrangement. Fund of funds providers pass on individual hedge fund incentive fees in the form of after-fee returns, although they are in a better position to hedge these fees than are their investors. We examine a new fee arrangement emerging in the industry that may provide better incentives at a lower cost to investors in these funds.

Optical observations of the AMPTE artificial comet and magnetotail barium releases

The first AMPTE artificial comet was observed with a low light level television camera operated aboard the NASA CV990 flying out of Moffett Field, California. The comet head, neutral cloud, and comet tail were all observed for four minutes with an unifiltered camera. Brief observations at T + 4 minutes through a 4554A Ba(+) filter confirmed the identification of the structures. The ion cloud expanded along with the neutral cloud at a rate of 2.3 km/sec (diameter) until it reached a final diameter of approx. 170 km at approx. T + 90 s. It also drifted with the neutral cloud until approx. 165 s. By T + 190 s it had reached a steady state velocity of 5.4 km/sec southward. A barium release in the magnetotail was observed from the CV990 in California, Eagle, Alaska, and Fairbanks, Alaska. Over a twenty-five minute period, the center of the barium streak drifted southward (approx. 500 m/sec), upward (24 km/sec) and eastward (approx 1 km/sec) in a nonrotating reference frame. An all-sky TV at Eagle showed a single auroral arc in the far North during this period

Composite engines for application to a single-stage-to-orbit vehicle

Seven composite engines were designed for application to a reusable single-stage-to-orbit vehicle. The engine designs were variations of the supercharged ejector ramjet engine. The resulting performance, weight, and drawings of each engine form a data base for establishing a potential of this class of composite engine to various missions, including the single-stage-to-orbit application. The impact of advanced technology in the design of the critical fan turbine was established