Double injection: high frequency noise and temperature dependence

Noise measurements from 140°K to 350°K ambient temperature and between 10kHz and 22MHz performed on a double injection silicon diode as a function of operating point indicate that the high frequency noise depends linearly on the ambient temperature T and on the differential conductance g measured at the same frequency. The noise is represented quantitatively by〈i^2〉 = α•4kTgΔf. A new interpretation demands Nyquist noise with α ≡ 1 in these devices at high frequencies. This is in accord with an equivalent circuit derived for the double injection process. The effects of diode geometry on the static I-V characteristic as well as on the ac properties are illustrated. Investigation of the temperature dependence of double injection yields measurements of the temperature variation of the common high-level lifetime τ(τ ∝ T^2), the hole conductivity mobility µ_p (µ_p ∝ T^(-2.18)) and the electron conductivity mobility µ_n(µ_n ∝ T^(-1.75)).

Readout of a real-time hologram in bacteriorhodopsin film with high diffraction efficiency and intensity

A scheme for the readout of a hologram recorded in bacteriorhodopsin film with high diffraction efficiency and intensity is suggested and demonstrated. Two weak coherent continuous beams function as the recording beams, and a strong light pulse is used to read the real-time hologram. The width of the readout light pulse is modulated to be short compared with the erase time of the reading beam; the time space between two adjacent pulses is ensured to be longer than the time the beams take to recover the hologram, and high diffraction efficiency and intensity (similar to 11 mW/cm(2)) can be obtained. (C) 1996 Optical Society of America.

Energy inequalities and error estimates for axisymmetric torsion of thin elastic shells of revolution

The problem motivating this investigation is that of pure axisymmetric torsion of an elastic shell of revolution. The analysis is carried out within the framework of the three-dimensional linear theory of elastic equilibrium for homogeneous, isotropic solids. The objective is the rigorous estimation of errors involved in the use of approximations based on thin shell theory.

The underlying boundary value problem is one of Neumann type for a second order elliptic operator. A systematic procedure for constructing pointwise estimates for the solution and its first derivatives is given for a general class of second-order elliptic boundary-value problems which includes the torsion problem as a special case.

The method used here rests on the construction of “energy inequalities” and on the subsequent deduction of pointwise estimates from the energy inequalities. This method removes certain drawbacks characteristic of pointwise estimates derived in some investigations of related areas.

Special interest is directed towards thin shells of constant thickness. The method enables us to estimate the error involved in a stress analysis in which the exact solution is replaced by an approximate one, and thus provides us with a means of assessing the quality of approximate solutions for axisymmetric torsion of thin shells.

Finally, the results of the present study are applied to the stress analysis of a circular cylindrical shell, and the quality of stress estimates derived here and those from a previous related publication are discussed.

4th European Conference on Energy Efficiency and Sustainability in Architecture and Planning : Donostia-San Sebastián, 1-3 Julio 2013

XXXII Cursos de Verano de la UPV/EHU

5th European Conference on Energy Efficiency and Sustainability in Architecture and Planning : Donostia-San Sebastián, 7-9 Julio 2014

XXXIII Cursos de Verano de la UPV/EHU

Temporal-space-transforming pulse-shaping system with a knife-edge apparatus for a high-energy laser facility

For the first time to our knowledge, in a high-energy laser facility with an output energy of 454.37 J, by using a temporal-space-transforming pulse-shaping system with our own design of a knife-edge apparatus, we obtained a quasi-square laser pulse. (c) 2005 Optical Society of America.

6th European Conference on Energy Efficiency and Sustainability in Architecture and Planning

[ES]Esta obra recoge las comunicaciones seleccionadas para el 6º Congreso Europeo sobre Eficiencia Energética y Sostenibilidad en Arquitectura, organizado por el grupo de investigación Calidad de Vida en Arquitectura de la Universidad del País Vasco/Euskal Herriko Unibertsitatea. El congreso, que se celebra en el marco de los XXXIV Cursos de Verano de la UPV/EHU, aborda en esta cuarta edición el tema “Ciudades en riesgo: resiliencia y redundancia”. Alrededor de este tema general se desarrollan cinco ponencias magistrales, a cargo de Margaretha Breil (Centro Euro-Mediterráneo para el Cambio Climático), Cristina Garzillo Leemhuis (ICLEI), Ignasi Fontanals (OptiCits), Juan Carlos Barrios Montenegro (Global Action Plan) y Manuel Valdés López (Ajuntament de Barcelona). Además, 24 comunicaciones seleccionadas por el comité científico presentarán trabajos de investigaciones actuales en las sesiones orales y póster. Es objetivo paralelo del congreso es fortalecer las líneas de investigación en eficiencia energética y sostenibilidad de los grupos de investigación y formación de la UPV/ EHU comprometidos con esta propuesta, con objeto de colaborar en el reforzamiento de la I D i en su ámbito de conocimiento y apoyar la apuesta específica de los Gobiernos Central y Vasco, así como de otras instituciones nacionales e internacionales respecto a las actividades de I D i en las materias relacionadas con el cambio climático, la eficiencia energética y la sostenibilidad ambiental [ENG] This work contains the selected abstracts of the 6th European Conference on Energy Efficiency and Sustainability in Architecture and Planning, organized by the research group Quality of life in Architecture of the University of the Basque Country. The conference is part of the XXXIV Summer Courses of the UPV/EHU and deals, in its fourth edition, with the topic “Cities at risk: resilience and redundancy”. Around this general theme there are five invited speakers: Margaretha Breil (Euro-Mediterranean Centre for Climate Change), Cristina Garzillo Leemhuis (ICLEI), Ignasi Fontanals (OptiCits), Juan Carlos Barrios Montenegro (Global Action Plan) y Manuel Valdés López (Barcelona City Council). 24 abstracts additional have been selected by the scientific committee that offer actual research works in presentations and posters. The purpose of the conferences is to strengthen the investigation lines in energy efficiency and sustainability of the research and education groups of the University of the Basque Country (UPV/EHU) involved, with the purpose of collaborating in the reinforcement of the I D i in its field of knowledge, and support the specific projects of the Central and Basque Governments, as well as other national and international institutions related to the I Di activities in similar fields of climate change, energy efficiency and environmental sustainability.

Spectroscopic properties of neodymium doped high silica glass and aluminum codoping effects on the enhancement of fluorescence emission

Nd3+ -codoped and Al3+-Nd3+-codoped high silica glasses have been prepared by sintering nanoporous glasses impregnated with Nd3+ stop and Al3+ ions. The Judd-Ofelt intensity parameters Omega(2,4,6) of Nd3+-doped high silica glasses were obtained and used to analyze aluminum codoping effects. Fluorescence properties of Nd3+-doped high silica glasses strongly depend on the Al3+ concentration. While Nd3+ ion absorption and emission intensities of obviously increase when aluminum is added to Nd3+-doped high silica glasses, fluorescence lifetimes decrease and aluminum codoping has almost no influence on the radiative quantum efficiencies. This indicates that aluminum codoping is responsible for an anti-quenching effect through a local modification of rare-earth environments rather than through physical cluster dispersion.

Energy transfer and infrared-to-visible upconversion luminescence of Er3+/Yb3+-codoped halide modified tellurite glasses

We report on the energy transfer and frequency upconversion spectroscopic properties of Er3+-doped and Er3+/Yb3+-codoped TeO2-ZnO-Na2O-PbCl2 halide modified tellurite glasses upon excitation with 808 and 978 nm laser diode. Three intense emissions centered at around 529, 546 and 657 nm, alongwith a very weak blue emission at 4 10 nm have clearly been observed for the Er3+/Yb3+-codoped halide modified tellurite glasses upon excitation at 978 nm and the involved mechanisms are explained. The quadratic dependence of fluorescence on excitation laser power confirms the fact that the two-photon contribute to the infrared to green-red upconversion emissions. And the blue upconversion at 410 nm involved a sequential three-photon absorption process. (c) 2005 Elsevier Ltd. All rights reserved.

High quantum efficiency and high concentration erbium-doped silica glasses fabricated by sintering nanoporous glasses

A new method was used to prepare erbium-doped high silica (SiO2% > 96%) glasses by sintering nanoporous glasses. The concentration of erbium ions in high silica glasses can be considerably more than that in silica glasses prepared by using conventional methods. The fluorescence of 1532 nm has an FWHM (Full Wave at Half Maximum) of 50 nm, wider than 35 nm of EDSFA (erbium-doped silica fiber amplifer), and hence the glass possesses potential application in broadband fiber amplifiers. The Judd-Ofelt theoretical analysis reflects that the quantum efficiency of this erbium-doped glass is about 0.78, although the erbium concentration in this glass (6 x 103) is about twenty times higher than that in silica glass. These excellent characteristics of Er-doped high silica glass will be conducive to its usage in optical amplifiers and microchip lasers.