N-SAP and G-SAP neutron and gamma ray albedo model scatter shield analysis program

Computer program calculates neutron or gamma ray first order scattering from a plane or cylindrical surface to a detector point. The SAP Codes, G-SAP and N-SAP, constitute a multiple scatter albedo model shield analysis

Synthesis of calculational methods for the design and analysis of radiation shields for nuclear rocket systems. Volume 2 - Analysis of radiation measurements in a nuclear rocket propellant tank mockup using simulated liquid hydrogen

Calculational methods for nuclear rocket radiation shield design - analysis of radiation measurements in nuclear rocket propellant tank mockup using simulated liquid hydroge

A Shell of Thermal X-ray Emission Associated with the Young Crab-like Remnant 3C58

Deep X-ray imaging spectroscopy of the bright pulsar wind nebula 3C58 confirms the existence of an embedded thermal X-ray shell surrounding the pulsar PSR J0205+6449. Radially resolved spectra obtained with the XMM-Newton telescope are well-characterized by a power-law model with the addition of a soft thermal emission component in varying proportions. These fits reproduce the well-studied increase in the spectral index with radius attributed to synchrotron burn-off of high energy electrons. Most interestingly, a radially resolved thermal component is shown to map out a shell-like structure ~6' in diameter. The presence of a strong emission line corresponding to the Ne IX He-like transition requires an overabundance of ~3 x [Ne/Ne(sun)] in the Raymond-Smith plasma model. The best-fit temperature kT ~ 0.23 keV is essentially independent of radius for the derived column density of N_H = (4.2 +/- 0.1)E21 per cm squared. Our result suggests that thermal shells can be obscured in the early evolution of a supernova remnant by non-thermal pulsar wind nebulae emission; the luminosity of the 3C58 shell is more than an order of magnitude below the upper limit on a similar shell in the Crab Nebula. We find the shell centroid to be offset from the pulsar location. If this neutron star has a velocity similar to that of the Crab pulsar, we derive an age of 3700 yr and a velocity vector aligned with the long axis of the PWN. The shell parameters and pulsar offset add to the accumulating evidence that 3C58 is not the remnant of the supernova of CE 1181.Comment: 7 pages, 8 figures, 2 tables, Latex emulateapj style. To appear in the Astrophysical Journa

Radio Images of 3C 58: Expansion and Motion of its Wisp

New 1.4 GHz VLA observations of the pulsar-powered supernova remnant 3C 58 have resulted in the highest-quality radio images of this object to date. The images show filamentary structure over the body of the nebula. The present observations were combined with earlier ones from 1984 and 1991 to investigate the variability of the radio emission on a variety of time-scales. No significant changes are seen over a 110 day interval. In particular, the upper limit on the apparent projected velocity of the wisp is 0.05c. The expansion rate of the radio nebula was determined between 1984 and 2004, and is 0.014+/-0.003%/year, corresponding to a velocity of 630+/-70 km/s along the major axis. If 3C 58 is the remnant of SN 1181, it must have been strongly decelerated, which is unlikely given the absence of emission from the supernova shell. Alternatively, the low expansion speed and a number of other arguments suggest that 3C 58 may be several thousand years old and not be the remnant of SN 1181.Comment: 12 pages; accepted for publication in the Astrophysical Journa

Bio-development of motorway network in the Netherlands: A slime mould approach

Plasmodium of a cellular slime mould Physarum polycephalum is a very large eukaryotic microbe visible to the unaided eye. During its foraging behavior the plasmodium spans sources of nutrients with a network of protoplasmic tubes. In this paper we attempt to address the following question: Is slime mould capable of computing transport networks? By assuming the sources of nutrients are cities and protoplasmic tubes connecting the sources are motorways, how well does the plasmodium approximate existing motorway networks? We take the Netherlands as a case study for bio-development of motorways, while it has the most dense motorway network in Europe, current demand is rapidly approaching the upper limits of existing capacity. We represent twenty major cities with oat flakes, place plasmodium in Amsterdam and record how the plasmodium spreads between oat flakes via the protoplasmic tubes. First we analyze slime-mould-built and man-built transport networks in a framework of proximity graphs to investigate if the slime mould is capable of computing existing networks. We then go on to investigate if the slime mould is able calculate or adapt the network through imitating restructuring of the transport network as a response to potential localized flooding of the Netherlands. © World Scientific Publishing Company

Quantum walks in higher dimensions

We analyze the quantum walk in higher spatial dimensions and compare classical and quantum spreading as a function of time. Tensor products of Hadamard transformations and the discrete Fourier transform arise as natural extensions of the quantum coin toss in the one-dimensional walk simulation, and other illustrative transformations are also investigated. We find that entanglement between the dimensions serves to reduce the rate of spread of the quantum walk. The classical limit is obtained by introducing a random phase variable.Comment: 6 pages, 6 figures, published versio

The evaluation of a synthetic material for use as a wave protection agent on irrigation dams

This report presents the results of a field and laboratory testing program to evaluate the performance of a slope protection method utilizing a new synthetic fabric material in the form of soil filled bags. The field study was performed to evaluate the feasibility of filling and placing the bags on an operational irrigation darn using equipment and resources available to a typical farmer. Test sections on the dam were monitored to determine the amount of wave erosion of both unprotected and protected slopes of the dam. Tensile strength tests were performed on samples of the fabric. The results of the strength tests indicate the durability of the system. Laboratory immersion tests were conducted on two soil materials used to fill the bags. The results of the immersion tests were then compared to the field performance of each material in the bags. The results of this investigation indicate that the system is readily installed on irrigation dams and offers excellent slope protection. The factors which influence the practicality of the system include the cost of alternate slope protection methods, the position of the irrigation dam in relation to local winds and the availability of fill material for the bags. A medium-scale laboratory model study was performed on a new synthetic fabric designed to be used in the form of soil-filled sand pillows in order to determine the relationship that affect the stability of the pillows and to determine basic design criteria for the protection system. The model testing of the sand pillow system was performed to evaluate the parameters that affect the stability of the pillows when placed on an embankment slope. The results of the model investigation were consolidated and analyzed to develop design criteria for the individual pillows. The results of the model study investigation indicate that the stability of sand pillows is primarily a function of wave height, wave period, embankment slope angle, and individual sand pillow weight. A possible design equation was developed for a silty clay soil such that the wave height calculated for a given reservoir could be utilized to determine the weight of the individual sand pillow necessary to economically and effectively protect the embankment. The results of the laboratory and field evaluation investigation indicate that the sand pillow method offers excellent slope protection. However, since some soils appear to be readily lost through fabric when subjected to repeated wave action, some limiting minimum particle size specification is required in order to prevent unnecessary maintenance of the system.Project # B-122-MO Agreement # 14-34-0001-809

Study of Space Station propulsion system resupply and repair Final report

Resupply and repair capabilities for orbital space station bipropellant propulsion syste