Effect of combining a DC bias current with an AC transport current on AC losses in a High Temperature Superconductor

Creating complex flux configurations by superposing a dc current or magnetic field onto the ac current in a type II superconducting tape should lead to a variety of peculiar behaviors. An example is the appearance of the Clem valley, a minimum in the ac losses as a function of the dc bias amplitude, which has been theoretically studied by LeBlanc et al., in the continuation of Clem's calculations. These situations have been investigated by applying a dc current to a silver-gold sheathed Bi-2223 tape at 77 K (critical current 29 A), in addition to the usual ac transport current. The ac losses were measured by the null calorimetric method to ensure that the total losses were being accounted for. These were recorded for different values of the ac and dc currents, leading to the observation of two different behaviors depending on the ac current. Our revelation of the Clem valley is, to our knowledge, the first experimental validation of this phenomenon in high temperature superconductors, and may provide a simple way of reducing the ac loss in industrial applications of these materials.Comment: 4 pages,4 figures - ASC 9

Experimental Determination of Elastic Anisotropy of Berea Sandstone, Chicopee Shale and Chelmsford Granite

We use the ultrasonic transmission method to measure P-, SH-, and SV-wave velocities for Chelmsford Granite, Chicopee Shale, and Berea Sandstone in different directions up to 1000 bars confining pressure. The velocity measurements indicate that these three rocks are elastically anisotropic. The stiffness constants, dynamic Young's moduli, dynamic Poisson's ratios, and dynamic bulk moduli of these three rocks were also calculated. These elastic constants, together with velocity measurements, suggest that: (1) Elastic anisotropy is due to the combined effects of pores/cracks and mineral grain orientation. (2) Elastic anisotropy decreases with increasing confining pressure. The residual anisotropy at higher confining pressure is due to mineral grain orientation

Molecular dynamics in shape space and femtosecond vibrational spectroscopy of metal clusters

We introduce a method of molecular dynamics in shape space aimed at metal clusters. The ionic degrees of freedom are described via a dynamically deformable jellium with inertia parameters derived from an incompressible, irrotational flow. The shell correction method is used to calculate the electronic potential energy surface underlying the dynamics. Our finite temperature simulations of Ag_14 and its ions, following the negative to neutral to positive scheme, demonstrate the potential of pump and probe ultrashort laser pulses as a spectroscopy of cluster shape vibrations.Comment: Latex/Revtex, 4 pages with 3 Postscript figure

Hot and repulsive traffic flow

We study a message passing model, applicable also to traffic problems. The model is implemented in a discrete lattice, where particles move towards their destination, with fluctuations around the minimal distance path. A repulsive interaction between particles is introduced in order to avoid the appearance of traffic jam. We have studied the parameter space finding regions of fluid traffic, and saturated ones, being separated by abrupt changes. The improvement of the system performance is also explored, by the introduction of a non-constant potential acting on the particles. Finally, we deal with the behavior of the system when temporary failures in the transmission occurs.Comment: 22 pages, uuencoded gzipped postscript file. 11 figures include

Seismic borehole tomography

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric and Planetary Sciences, 1988.Includes bibliographies.by Tien-when Lo.Ph.D

Analisis Faktor-Faktor yang Memengaruhi Perilaku Penggunaan E-wallet di Masa Pandemi Covid-19

Penelitian yang berjudul ”Analisis Faktor-Faktor yang Memengaruhi Perilaku Penggunaan E-wallet di Masa Pandemi Covid-19” ini merupakan penelitian kuantitatif yang dilakukan untuk mengetahui pengaruh dari persepsi kemudahan penggunaan, persepsi kegunaan, persepsi risiko uang tunai, dan persepsi dukungan pemerintah terhadap perilaku penggunaan e-wallet. Populasi dalam penelitian ini adalah mahasiswa Fakultas Ekonomi dan Bisnis Universitas Jenderal Soedirman. Sampel penelitian diambil dengan menggunakan teknik purposive sampling dengan kriteria yaitu mahasiswa aktif Fakultas Ekonomi dan Bisnis Universitas Jenderal Soedirman dan pernah menggunakan e-wallet selama masa pandemi covid-19, dengan jumlah sampel sebesar 172 sampel. Data dalam penelitian ini dianalisis menggunakan SEM-PLS (Structural Equation Modeling-Partial Least Square) dan menunjukkan hasil bahwa : (1) Persepsi kemudahan penggunaan berpengaruh positif terhadap perilaku penggunaan e-wallet, (2) Persepsi kegunaan berpengaruh positif terhadap perilaku penggunaan e-wallet, (3) Persepsi risiko uang tunai berpengaruh positif terhadap perilaku penggunaan e-wallet, dan (4) Persepsi dukungan pemerintah tidak berpengaruh terhadap perilaku penggunaan e-wallet. Implikasi dari kesimpulan di atas yaitu untuk dapat meningkatkan perilaku penggunaan e-wallet perusahaan penerbit harus lebih memperhatikan persepsi penggunanya dalam hal kemudahan penggunaan dan kegunaan dari e-wallet. Upaya yang dapat dilakukan oleh perusahaan penerbit e-wallet yaitu dengan meningkatkan fitur-fitur e-wallet yang dapat mempermudah dalam penggunaan e-wallet, serta fasilitas yang dapat membuat pengguna lebih merasakan kegunaan dari e-wallet. Apalagi dengan adanya persepsi risiko uang tunai pada masa pandemi covid-19 dapat meningkatkan penggunaan e-wallet sehingga perusahaan penerbit diharapkan dapat meningkatkan kinerja e-wallet. Kata Kunci : E-wallet, Covid-19, Persepsi Kemudahan Penggunaan, Persepsi Kegunaan, Persepsi Risiko Uang Tunai, Persepsi Dukungan Pemerintah, Perilaku Penggunaan

Analisis determinan perilaku penggunaan E-Wallet pada masa pandemi Covid-19

Abstract. This study aims to analyze the determinants of e-wallet usage behavior including perceived ease of use, usability, risk and government support. The population includes students from Jenderal Soedirman University, Purwokerto, Faculty of Economics and Business. The sampling technique uses purposive sampling with the criteria of students who are still active and utilizing e-wallets during the corona-19 virus pandemic with a sample of 172 respondents using the PLS-SEM technique. The findings show that: a person's behavior in using e-wallets can be positively and partially influenced by users' perceptions of ease of use, of their usefulness, and perceptions of avoiding the risks of using cash. However, e-wallet usage behavior is not influenced by user perceptions of government support. to increase the use of e-wallets, electronic money issuers should focus on how to shape user perceptions of the ease of use and clarity of use and avoid risks when transacting using cash. Keywords: Perceived Ease of Use; Perceived Government Support; Perceived Risk of Cash; Perceived Usefulness; Usage Behavior. Abstrak. Studi ini bertujuan untuk menganalisis pengaruh determinan perilaku penggunaan e-wallet mencakup persepsi kemudahan penggunaan, kegunaannya, risiko serta dukungan pemerintah. Populasi meliputi para mahasiswa Universitas Jenderal Soedirman Purwokerto, Fakultas Ekonomi dan Bisnis. Teknik sampling menggunakan purposive sampling dengan kriteria mahasiswa yang masih aktif dan memanfaatkan e-wallet saat pandemic virus corona-19 dengan sampel sebanyak 172 responden menggunakan teknik PLS-SEM. Temuannya memperlihatkan bahwa: perilaku seseorang dalam penggunaan e-wallet dapat dipengaruhi secara positif dan secara parsial oleh persepsi para penggunanya pada kemudahan penggunaan, pada kegunaannya, dan persepsi menghindari risiko penggunaan uang tunai. Namun, perilaku penggunaan e-wallet tidak dipengaruhi oleh persepsi penggunanya atas dukungan pemerintah. Agar penggunaan e-wallet meningkat, sebaiknya penerbit uang elektronik menitikberatkan bagaimana membentuk persepsi penggunanya merasakan faktor kemudahan penggunaan dan kejelasan kegunaannya serta menghindari risiko ketika bertransaksi memakai uang secara tunai. Katakunci: Perilaku Penggunaan; Persepsi Dukungan Pemerintah; Persepsi Kegunaan; Persepsi Kemudahan Penggunaan; Persepsi Risiko Uang Tunai

Ultrasonic laboratory tests of geophysical tomographic reconstruction

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric and Planetary Sciences, 1986.Microfiche copy available in Archives and Science.Bibliography: leaves 31-35.by Tien-when Lo.M.S

Closing the knowing-applying gap in water utilities: experience from Uganda's NWSC

In recent decades, there has been a steady rise of knowledge and capacity development (KCD) interventions targeting water utilities in developing countries. However, field experiences show that very often little change occurs in what water utilities' professionals and managers do as a result of capacity development efforts. Notwithstanding that, there are also some cases of success. In this paper, the authors argue that very often the main challenge facing utilities is not the development of utility competences per se, but their actual use. Drawing on the case of Uganda's National Water and Sewerage Corporation, we identify and discuss five interrelated factors that have allowed the corporation to progressively turn its knowledge base into improved performance, by means of its change management programmes. The paper concludes that water utilities can bridge the knowing-applying gap by carefully introducing a corporate culture, and management systems and structures that motivate staff to apply their knowledge