10,331 research outputs found

    Applications of DFT to the theory of twentieth-century harmony

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    Music theorists have only recently, following groundbreaking work by Quinn, recognized the potential for the DFT on pcsets, initially proposed by Lewin, to serve as the foundation of a theory of harmony for the twentieth century. This paper investigates pcset “arithmetic” – subset structure, transpositional combination, and interval content – through the lens of the DFT. It discusses relationships between interval classes and DFT magnitudes, considers special properties of dyads, pcset products, and generated collections, and suggest methods of using the DFT in analysis, including interpreting DFT magnitudes, using phase spaces to understand subset structure, and interpreting the DFT of Lewin’s interval function. Webern’s op. 5/4 and Bartok’s String Quartet 4, iv, are discussed.Accepted manuscrip

    X-ray bursters and the X-ray sources of the galactic bulge

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    Type 1 X-ray bursts, optical, infrared, and radio properties of the galactic bulge sources, are discussed. It was proven that these burst sources are neutron stars in low mass, close binary stellar systems. Several burst sources are found in globular clusters with high central densities. Optical type 1 X-ray bursts were observed from three sources. Type 2 X-ray bursts, observed from the Rapid Burster, are due to an accretion instability which converts gravitational potential energy into heat and radiation, which makes them of a fundamentally different nature from Type 1 bursts

    A New Method to Improve the Sensitivity of Leak Detection in Self-Contained Fluid-filled Cables

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    A method of real-time detection of leaks for self-contained fluid-filled cables without taking them out of service has been assessed and a novel machine learning technique, i.e. support vector regression (SVR) analysis has been investigated to improve the detection sensitivity of the self-contained fluid-filled (FF) cable leaks. The condition of a 400 kV underground FF cable route within the National Grid transmission network has been monitored by Drallim pressure, temperature and load current measurement system. These three measured variables are used as parameters to describe the condition of the cable system. In the regression analysis the temperature and load current of the cable circuit are used as independent variables and the pressure within cables is the dependent variable to be predicted. As a supervised learning algorithm, the SVR requires data with known attributes as training samples in the learning process and can be used to identify unknown data or predict future trends. The load current is an independent variable to the fluid-filled system itself. The temperature, namely the tank temperature is determined by both the load current and the weather condition i.e. ambient temperature. The pressure is directly relevant to the temperature and therefore also correlated to the load current. The Gaussian-RBF kernel has been used in this investigation as it has a good performance in general application. The SVR algorithm was trained using 4 days data, as shown in Figure 1, and the optimized SVR is used to predict the pressure using the given load current and temperature information

    Electronic structure and chemical bonding of nc-TiC/a-C nanocomposites

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    The electronic structure of nanocrystalline (nc-) TiC/amorphous C nanocomposites has been investigated by soft x-ray absorption and emission spectroscopy. The measured spectra at the Ti 2p and C 1s thresholds of the nanocomposites are compared to those of Ti metal and amorphous C. The corresponding intensities of the electronic states for the valence and conduction bands in the nanocomposites are shown to strongly depend on the TiC carbide grain size. An increased charge-transfer between the Ti 3d-eg states and the C 2p states has been identified as the grain size decreases, causing an increased ionicity of the TiC nanocrystallites. It is suggested that the charge-transfer occurs at the interface between the nanocrystalline TiC and the amorphous C matrix and represents an interface bonding which may be essential for the understanding of the properties of nc-TiC/amorphous C and similar nanocomposites.Comment: 13 pages, 6 figures, 1 table; http://link.aps.org/doi/10.1103/PhysRevB.80.23510

    Case Study #4-3 of the Program: ''Food Policy For Developing Countries: The Role Of Government In The Global Food System''

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    10 pp.©Cornell University, Ithaca, New York. All rights reserved. This case study may be reproduced for educational purposes without express permission but must include acknowledgment to Cornell University. No commercial use is permitted without permission.Since the mid-1970s Niger has suffered from political instability and corruption. Following a 1996 coup, the World Bank and International Monetary Fund (IMF) worked with Niger to implement various structural adjustment programs, but nearly 10 years later, in 2004–2005, the country faced a food crisis. One-third of Niger's population suffered from high levels of food insecurity and vulnerability. Yet the food crisis gained little media coverage; the government of Niger denied the country was even faced with a food crisis and continued to claim that food shortages were normal for this country. As the crisis progressed, Niger did receive aid, yet efforts to improve the situation did not help. Many blamed the situation in Niger on donor countries—their delay in sending assistance and their lack of overall assistance. Others blamed the structural adjustment programs of the World Bank and International Monetary Fund, and most found at least some fault with the Nigerien government. The food crisis in Niger evolved into one of the largest food crisis “blame games.” Numerous challenges arise as policymakers try to craft a common solution appropriate for all stakeholders. In an analysis of what happened in Niger and why food aid was so ineffective, many central themes emerge. Corrupt governance was one issue, as was the timeliness of food aid. Food aid arrived too late; it then became available at the time of Niger's harvest, depressing market prices of Niger's staple foods. The United Nations, then, must examine how to most effectively target the neediest populations and how to best access assistance for these emergencies. In addition, one cannot separate the food crisis from the chronic poverty that exists in the country. Poor infrastructure, Niger's geographic position as a landlocked country, and low agricultural productivity remain a challenge to the overall health of the region. Many policy options exist for the donor countries, international institutions, and the government of Niger. Such options include improving the United Nations' Central Emergency Revolving Fund, establishing a Global Food Aid Compact, and reforming the Nigerien government (including implementing the country's poverty reduction strategy). Such steps can help prevent future crises and help alleviate the suffering of the people of Niger. Your assignment is to develop a set of policies that will satisfy the main stakeholder groups.Cornell University Division of Nutritional Science

    Non-perturbative embedding of local defects in crystalline materials

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    We present a new variational model for computing the electronic first-order density matrix of a crystalline material in presence of a local defect. A natural way to obtain variational discretizations of this model is to expand the difference Q between the density matrix of the defective crystal and the density matrix of the perfect crystal, in a basis of precomputed maximally localized Wannier functions of the reference perfect crystal. This approach can be used within any semi-empirical or Density Functional Theory framework.Comment: 13 pages, 4 figure

    Latitudinal Shear Instabilities during Type I X-ray Bursts

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    Coherent oscillations have been observed during Type I X-ray bursts from 14 accreting neutron stars in low mass X-ray binaries, providing important information about their spin frequencies. However, the origin of the brightness asymmetry on the neutron star surface producing these oscillations is still not understood. We study the stability of a zonal shearing flow on the neutron star surface using a shallow water model. We show that differential rotation of >2% between pole and equator, with the equator spinning faster than the poles, is unstable to hydrodynamic shear instabilities. The unstable eigenmodes have properties well-matched to burst oscillations: low azimuthal wavenumber m, wave speeds 1 or 2% below the equatorial spin rate, and e-folding times close to a second. Instability is related to low frequency buoyantly driven r-modes that have a mode frequency within the range of rotation frequencies in the differentially rotating shell. We discuss the implications for burst oscillations. Growth of shear instabilities may explain the brightness asymmetry in the tail of X-ray bursts, although some fine tuning of the level of differential rotation and a spin frequency near 300 Hz are required in order for the fastest growing mode to have m=1. If shear instabilities are to operate during a burst, temperature contrasts of 30% across the star must be created during ignition and spreading of the flash.Comment: To appear in ApJ (12 pages, 11 figures

    Partial discharge testing of defective three-phase PILC cable under rated conditions

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    The ability to accurately monitor the health of power distribution plant is a very attractive prospect for utility companies. This capability would provide a system that engineers could use to assess the real-time state of the network. Analysis of the data produced could allow for more informed decisions to be made in the areas of asset replacement and maintenance scheduling amongst others. It is widely accepted that partial discharge activity is linked with the electrical ageing/degradation of high voltage equipment. Work at Southampton is focused on obtaining a better understanding of the characteristics and trends of partial discharge events associated with medium voltage cables under, 'real life' conditions. An experiment has been developed that allows for service conditions to be applied to defective paper insulated lead covered cable samples. The samples under investigation were exposed to mechanical damage designed to replicate typical problems found on an active circuit. Partial discharge measurement was undertaken during the stressing process

    Relativistic Iron Lines in Galactic Black Holes: Recent Results and Lines in the ASCA Archive

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    Recent observations with Chandra and XMM-Newton, aided by broad-band spectral coverage from RXTE, have revealed skewed relativistic iron emission lines in stellar-mass Galactic black hole systems. Such systems are excellent laboratories for testing General Relativity, and relativistic iron lines provide an important tool for making such tests. In this contribution to the Proceedings of the 10th Annual Marcel Grossmann Meeting on General Relativity, we briefly review recent developments and present initial results from fits to archival ASCA observations of Galactic black holes. It stands to reason that relativistic effects, if real, should be revealed in many systems (rather than just one or two); the results of our archival work have borne-out this expectation. The ASCA spectra reveal skewed, relativistic lines in XTE J1550-564, GRO J1655-40, GRS 1915+105, and Cygnus X-1.Comment: to appear in the proc. of the 10th Annual Marcel Grossmann Meeting on General Relativity, 5 pages, 1 figure, uses specific .cls and .sty file
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