Next generation: Unmanned launch vehicles and upper stages: The needs

The focus is on common vehicle elements, higher mission success, and lower transportation cost with respect to the common needs of the Department of Defense, NASA, and U.S. Industry. The following are presented in viewgraph form: (1) perspectives on mission costs and failures; (2) the recurring costs of the Delta 7925, Atlas/Centar, Titan 3, and Titan 4; (3) U.S. launches from 1957-1987 of Vanguard, Jupiter, Thor/Delta, Juno, Atlas, Scout, Redstone, Saturn, Titan, and the Space Transportation System; and (4) subsystem sources of failure. The following topics are also briefly presented: (1) engine costs; (2) a summary of flight experience; (3) recommendations for next generation space transportation; (4) low cost engine demonstration; and (5) the next generation commercial expendable launch vehicle (ELV) needs estimate

Color-Induced Displacement double stars in SDSS

We report the first successful application of the astrometric color-induced displacement technique (CID, the displacement of the photocenter between different bandpasses due to a varying contribution of differently colored components to the total light), originally proposed by Wielen (1996) for discovering unresolved binary stars. Using the Sloan Digital Sky Survey (SDSS) Data Release 1 with 2.5 million stars brighter than 21m in the u and g bands, we select 419 candidate binary stars with CID greater than 0.5 arcsec. The SDSS colors of the majority of these candidates are consistent with binary systems including a white dwarf and any main sequence star with spectral type later than ~K7. The astrometric CID method discussed here is complementary to the photometric selection of binary stars in SDSS discussed by Smolcic et al. (2004), but there is considerable overlap (15%) between the two samples of selected candidates. This overlap testifies both to the physical soundness of both methods, as well as to the astrometric and photometric quality of SDSS data.Comment: submitted to A&A, 13 pages, 6 figure

Self-aligned 0-level sealing of MEMS devices by a two layer thin film reflow process

Many micro electromechanical systems (MEMS) require a vacuum or controlled atmosphere encapsulation in order to ensure either a good performance or an acceptable lifetime of operation. Two approaches for wafer-scale zero-level packaging exist. The most popular approach is based on wafer bonding. Alternatively, encapsulation can be done by the fabrication and sealing of perforated surface micromachined membranes. In this paper, a sealing method is proposed for zero-level packaging using a thin film reflow technique. This sealing method can be done at arbitrary ambient and pressure. Also, it is self-aligned and it can be used for sealing openings directly above the MEMS device. It thus allows for a smaller die area for the sealing ring reducing in this way the device dimensions and costs. The sealing method has been demonstrated with reflowed aluminium, germanium, and boron phosphorous silica glass. This allows for conducting as well as non-conducting sealing layers and for a variety of allowable thermal budgets. The proposed technique is therefore very versatile

Effect of an oxide cap layer and fluorine implantation on the metal-induced lateral crystallization of amorphous silicon

In this work, we investigate the effect of oxide cap layer on the metal-induced lateral crystallization (MILC) of amorphous silicon. The MILC is characterized at temperatures in the range 550 to 428°C using Nomarski optical microscopy and Raman spectroscopy. It is shown that better lateral crystallization is obtained when the oxide cap layer is omitted, with the crystallization length increasing by 33% for a 15 hour anneal at 550°C. A smaller increase of about 10% is seen at lower temperatures between 525°C and 475°C and no increase is seen below 450°C. It is also shown that the detrimental effect of the oxide cap layer can be dramatically reduced by giving samples a fluorine implant prior to the MILC anneal. Raman spectroscopy shows that random grain growth is significantly less for unimplanted samples without an oxide cap and also for fluorine implanted samples both with and without an oxide cap. The crystallization length improvement for samples without an oxide cap layer is explained by the elimination of random grain crystallization at the interface between the amorphous silicon and the oxide cap layer

Customizing kernel functions for SVM-based hyperspectral image classification

Previous research applying kernel methods such as support vector machines (SVMs) to hyperspectral image classification has achieved performance competitive with the best available algorithms. However, few efforts have been made to extend SVMs to cover the specific requirements of hyperspectral image classification, for example, by building tailor-made kernels. Observation of real-life spectral imagery from the AVIRIS hyperspectral sensor shows that the useful information for classification is not equally distributed across bands, which provides potential to enhance the SVM's performance through exploring different kernel functions. Spectrally weighted kernels are, therefore, proposed, and a set of particular weights is chosen by either optimizing an estimate of generalization error or evaluating each band's utility level. To assess the effectiveness of the proposed method, experiments are carried out on the publicly available 92AV3C dataset collected from the 220-dimensional AVIRIS hyperspectral sensor. Results indicate that the method is generally effective in improving performance: spectral weighting based on learning weights by gradient descent is found to be slightly better than an alternative method based on estimating ";relevance"; between band information and ground trut

Helium Nanodroplets And Liquid Hot Nagma: What Students Can Learn About Thermodynamics From Infrared Spectroscopy And A Model Dipeptide

Students taking physical chemistry often find the thermodynamics section of the course confusing and even downright uninteresting. In part, this is due to the abstract nature of concepts, such as entropy and enthalpy, as well as the math skills that are required and/or the transference of skills that students already possess. An activity was created and implemented for use in an undergraduate physical chemistry course to guide students through an application of thermodynamics through the lens of spectroscopy. The activity combines current spectroscopic research techniques\footnote{Leavitt, C. M.; Moore, K. B.; Raston, P. L.; Agarwal, J.; Moody, G. H.; Shirley, C. C.; Schaefer, H. F.; Douberly, G. E. Liquid Hot NAGMA Cooled to 0.4 K: Benchmark Thermochemistry of a Gas-Phase Peptide. J. Phys. Chem. A 2014, 118 (41), 9692–9700.} together with concepts covered in class to give students a complete picture of this topic. In this talk, the activity and its implementation will be discussed along with preliminary outcomes

A Modified Magnitude System that Produces Well-Behaved Magnitudes, Colors, and Errors Even for Low Signal-to-Noise Ratio Measurements

We describe a modification of the usual definition of astronomical magnitudes, replacing the usual logarithm with an inverse hyperbolic sine function; we call these modified magnitudes `asinh magnitudes'. For objects detected at signal-to-noise ratios of greater than about five, our modified definition is essentially identical to the traditional one; for fainter objects (including those with a formally negative flux) our definition is well behaved, tending to a definite value with finite errors as the flux goes to zero. This new definition is especially useful when considering the colors of faint objects, as the difference of two `asinh' magnitudes measures the usual flux ratio for bright objects, while avoiding the problems caused by dividing two very uncertain values for faint objects. The Sloan Digital Sky Survey (SDSS) data products will use this scheme to express all magnitudes in their catalogs.Comment: 11 pages, including 3 postscript figures. Submitted to A

The deductibility of interest

The deduction of interest expenditure, for the purpose of calculating the South African taxable income on which normal tax is levied, must satisfy the requirements of the preamble to section 11 and section 11(a) of the Income Tax Act 58 of 1962, read with section 23(g), unless a particular section makes specific provision for its deduction. There appears to be a presumption that if interest expenditure is incurred in the production of income derived from carrying on a trade, it is deductible and we need look no further. This presumption may underlie the 2005 amendment of sub-section (2) of section 24J, which provides that interest is deductible provided it has been incurred “in the production of income” and “for the purposes of trade” (sections 11(a) and 23(g)). This paper discusses the deductibility of interest and, in particular, whether there are circumstances in which interest paid on a loan used to acquire a capital asset could be of a capital nature. The provisions of the Income Tax Act and court decisions relating to the deductibility of interest, as well as opinions expressed by authoritative writers on tax, are subjected to critical analysis. The paper first distinguishes the tests for determining whether an expense has been incurred “in the production of income” and whether the expense is “of a capital nature”. Specific court decisions relating to the deductibility of interest are then analysed. The research considers section 24J of the Act, to determine whether its provisions have settled the debate, and refers briefly to the provisions of section 11(bB), in the context of the research question. The conclusion reached in the research is that there are occasions where the courts appear to have confused the tests for determining whether interest expenditure was incurred “in the production of income” and whether it is “of a capital nature”, in certain instances have also failed to address the question of the capital or revenue nature of the interest expenditure under scrutiny, and that the matter does not appear to be settled that interest incurred on funds used to acquire a capital asset used to produce trade income is automatically deductible

Magnetoswitching of current oscillations in diluted magnetic semiconductor nanostructures

Strongly nonlinear transport through Diluted Magnetic Semiconductor multiquantum wells occurs due to the interplay between confinement, Coulomb and exchange interaction. Nonlinear effects include the appearance of spin polarized stationary states and self-sustained current oscillations as possible stable states of the nanostructure, depending on its configuration and control parameters such as voltage bias and level splitting due to an external magnetic field. Oscillatory regions grow in size with well number and level splitting. A systematic analysis of the charge and spin response to voltage and magnetic field switching of II-VI Diluted Magnetic Semiconductor multiquantum wells is carried out. The description of stationary and time-periodic spin polarized states, the transitions between them and the responses to voltage or magnetic field switching have great importance due to the potential implementation of spintronic devices based on these nanostructures.Comment: 14 pages, 4 figures, Revtex, to appear in PR