4,208 research outputs found
Resistive switching effects on the spatial distribution of phases in metal-complex oxide interfaces
In order to determine the key parameters that control the resistive switching
mechanism in metal-complex oxides interfaces, we have studied the electrical
properties of metal / YBa2Cu3O7-d (YBCO) interfaces using metals with different
oxidation energy and work function (Au, Pt, Ag) deposited by sputtering on the
surface of a YBCO ceramic sample. By analyzing the IV characteristics of the
contact interfaces and the temperature dependence of their resistance, we
inferred that ion migration may generate or cancel conducting filaments, which
modify the resistance near the interface, in accordance with the predictions of
a recent model.Comment: 3 pages, 5 figures, to be published in Physica B. Corresponding
author: C. Acha ([email protected]
Technology Frames: The Art of Perspective and Interpretation in Strategy
In this paper, I bring together the literatures of the economics of innovation, corporate strategy and managerial and organizational cognition to explore how and why companies come to different conclusions and strategies for technology when presented with essentially very similar situations and information. Building on the work of Orlikowski and Gash (1994) on technological frames, I seek to explore the role of the technology frame of key senior managers in defining corporate strategy with respect to technology. To provide an empirical basis for the study, I take the case of the 6 leading US vertically integrated oil companies involved in the exploration and production of petroleum during the period 1984 to 1997. The analysis considers two key salients for the technology frame which are operationalised for the six companies based on their R&D expenditures, patents, publications and contrasted with their operational performance measures. These salients reflect respectively adaptational mapping (whereby signals in the environment prompt adaptation) and formational mapping (whereby experience and path-dependency influence interpretation) within the technology frame. The findings indicate support for the proposed approach to proxying technology frames on the two key points of salience for the upstream petroleum industry, and the paper concludes with a short discussion of future lines of research.technology frames, upstream petroleum, technology strategy, adaptational mapping, formational mapping
Cyclic electric field stress on bipolar resistive switching devices
We have studied the effects of accumulating cyclic electrical pulses of
increasing amplitude on the non-volatile resistance state of interfaces made by
sputtering a metal (Au, Pt) on top of the surface of a cuprate superconductor
YBaCuO (YBCO). We have analyzed the influence of the
number of applied pulses on the relative amplitude of the remnant
resistance change between the high () and the low () state
[] at different temperatures (). We show that
the critical voltage () needed to produce a resistive switching (RS, i.e.
) decreases with increasing or . We also find a power law
relation between the voltage of the pulses and the number of pulses
required to produce a RS of . This relation
remains very similar to the Basquin equation used to describe the
stress-fatigue lifetime curves in mechanical tests. This points out to the
similarity between the physics of the RS, associated with the diffusion of
oxygen vacancies induced by electrical pulses, and the propagation of defects
in materials subjected to repeated mechanical stress.Comment: 5 pages, 5 figures. To be published in JAP. Corresponding author:
[email protected]
Impacts of plug-in hybrid vehicles and combined heat and power technologies on electric and gas distribution network losses
Distribution network operators (DNOs) require strategies that can offset the tradeoffs new embedded technologies have on their assets. This paper employs modelling to show that through control device manipulation, gas and electric (G&E) network operators can influence savings in energy losses under the presence of plug-in hybrid vehicles (PHEVs) and combined heat and power technologies (CHPs). An integrated gas and electric optimal power flow (OPF) tool is introduced to undertake various case studies. The OPF tool evaluates the technical impacts experienced in the networks when DNOs apply a "plug and forget" operation strategy and then compares the results against a "loss minimisation" strategy. Results show the benefits in applying different strategies are more considerable in electric networks than in gas networks. The study corroborates that an integrated G&E analysis offers a fresh perspective for stakeholders in evaluating energy service networks performance under different operation strategies
Poole-Frenkel effect and Variable-Range Hopping conduction in metal / YBCO resistive switching devices
Current-voltage (IV) characteristics and the temperature dependence of the
contact resistance [] of Au / YBaCuO (optimally
doped YBCO) interfaces have been studied at different resistance states. This
states were produced by resistive switching after accumulating cyclic
electrical pulses of increasing number and voltage amplitude. The IV
characteristics and the dependence of the different states are
consistent with a Poole-Frenkel (P-F) emission mechanism with trapping-energy
levels in the 0.06-0.11 eV range. remains constant up to a
number-of-pulses-dependent critical voltage and increases linearly with further
increasing the voltage amplitude of the pulses. The observation of a P-F
mechanism reveals the existence of an oxygen-depleted layer of YBCO near the
interface. A simple electrical transport scenario is discussed, where the
degree of disorder, the trap energy level and the temperature range determine
an electrical conduction dominated by non-linear effects, or by a P-F emission
or by a Variable-Range Hopping regime.Comment: 16 pages, 5 figure
Electrical transport properties of manganite powders under pressure
We have measured the electrical resistance of micrometric to nanometric
powders of the LaPrCaMnO (LPCMO with y=0.3) manganite
for hydrostatic pressures up to 4 kbar. By applying different final thermal
treatments to samples synthesized by a microwave assisted denitration process,
we obtained two particular grain characteristic dimensions (40 nm and 1000 nm)
which allowed us to analyze the grain size sensitivity of the electrical
conduction properties of both the metal electrode interface with manganite (Pt
/ LPCMO) as well as the intrinsic intergranular interfaces formed by the LPCMO
powder, conglomerate under the only effect of external pressure. We also
analyzed the effects of pressure on the phase diagram of these powders. Our
results indicate that different magnetic phases coexist at low temperatures and
that the electrical transport properties are related to the intrinsic
interfaces, as we observe evidences of a granular behavior and an electronic
transport dominated by the Space Charge limited Current mechanism.Comment: 4 pages, 7 figures, to be published in Physica B Corresponding
author: C. Acha ([email protected]
Interest Rates in Nigeria: An Analytical Perspective
This paper set out to examine the implications of interest rate for savings and investment in Nigeria. It used data obtained from the Central Bank of Nigeria (CBN). Data were analyzed using Pearson's Correlation Coefficient and regression. Evidence showed interest rate as a poor determinant of savings and investment indicating that bank loans are mostly not used for productive purposes. Therefore, bank loans should be channeled to productive investments if interest is to play its catalytic role in the Nigerian economy
Francisco Valsecchi and the Adventures of a Catholic Economic Axiology in 20th Century Argentina
El recorrido intelectual de Francisco Valsecchi (1907-1992) en la historia
de las ideas económicas católicas muestra las inflexiones teóricas de una
axiologÃa derivada de la Doctrina Social de la Iglesia. Sin embargo, las condiciones
históricas del desarrollo de una economÃa católica en la Argentina y
las transformaciones sociales, económicas y polÃticas del periodo 1930-1970
incidieron sobre las tendencias conceptuales de esa axiologÃa en apariencia
perenne. Para explicar los cambios operados se sigue la trayectoria de Valsecchi.
Se muestran las fases principales de sus posiciones, destacando tres
momentos fundamentales coincidentes con los tres momentos de la economÃa
católica en la Argentina. Al mismo tiempo se muestra la curva teórica
de los economistas católicos, que los aleja de una propuesta propiamente
católica de una economÃa polÃtica para concentrar su punto de vista en la
dimensión ética de las prácticas empresariales. El recorrido intelectual de
Valsecchi revela el pasaje de una visión crÃtica de la economÃa predominante
en 1930 a una funcionalidad con la propuesta en clave antipopulista por las
clases propietarias en 1970.The intellectual trajectory of Francisco Valsecchi (1907-1992) in the history of
Catholic economic ideas shows the theoretical turns of an axiology derived
from the Social Doctrine of the Church. Both the historical circumstances
of a Catholic economic thought in Argentina and the social, economic, and
political changes of the 1930-1970 period had an impact on the conceptual
trends of this apparently perennial axiology. To explain the changes in the
economic perspectives the main stages of his theoretical positions are studied,
emphasizing the three key moments of Catholic economy. At the same time
the article shows the theoretical path followed by Catholic economists from
their original proposal of a political economy towards a view orientated to
the construction of an axiology of business practices. Valsecchi’s intellectual
trajectory reveals the passage from a critical perspective of economy prevailing
in the 1930’s to an antipopulist point of view strongly related to the
proprietor class in the 1970’s.Fil: Acha, Omar.
Universidad de Buenos Aire
ANALISIS KAPASITAS OKSIGEN GEDUNG OLAHRAGA INDOOR SPORT ACEH
Oksigen merupakan elamen penting dalam kehidupan manusia. Oksigen adalah salah satu yang mempengaruhi kehidupan manusia dan merupakan ganguan yang sring terjadi dalam segala janis aktifitas. Dalam sebuah gedung olahraga kapasitas oksigen yang sesuai meupakan salah satu kebutuhan yang penting bagi penonton dan atlit itu sendiri. Dalam Standards, and Work Designuntuk relative Humidity kapasaitas oksigen yang layak dalam sebuah gedung olahraga ialah 2050. Tujuan penelitian untuk mengetahui kapasitas oksigen. Penelitian ini menguunakan pendekatan deskriktif kualitatif dan termasuk jenis penelitian evaluasi. Subjek dalam penelitian ini adalah gedung olahraga Provinsi Aceh. Teknik analisis data yaitu: reduksi data data display, dan penarikan kesimpulan. Hasil yang di peroleh dari penelitian adalah: pada GOR (gedung olahraga) Indoor Sport Serba Guna Lhoong Raya kapasitas oksigen dengan rata-rata 20,. GOR Indoor Sport Gelanggang Mahasiswa Unsyiah kapastias oksigen dengan rata-rata 20,45. GOR Indoor Sport Pango kapasitas oksigen rata-tara 20,39 dan GOR Indoor Sport KONI kapastitas oksigen dengan rata-rata 20,38. Mengacu pada regulasi atau standar yang di tetapkan dalam Standards, and Work Design untuk relative Humidity, kapastias oksigen yang ada pada gedung di atas masih di bawah standar
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