Sensitivity and optimization of composite structures using MSC/NASTRAN

Design sensitivity analysis for composites will soon be available in MSC/NASTRAN. The design variables for composites can be lamina thicknesses, orientation angles, material properties or a combination of all three. With the increasing use of composites in aerospace and automotive industries, this general capability can be used in its own right for carrying out sensitivity analysis of complicated real-life structures. As part of a research effort, the sensitivity analysis was coupled with a general purpose optimizer. This preliminary version of the optimizer is capable of dealing with minimum weight structural design with a rather general design variable linking capability at the element level or system level. Only sizing type of design variables (i.e., lamina thicknesses) can be handled by the optimizer. Test cases were run and validated by comparison with independent finite element packages. The linking of design sensitivity capability for composites in MSC/NASTRAN with an optimizer would give designers a powerful automated tool to carry out practical opitmization design of real-life complicated composite structures

MAXIMIZATION OF PULL-IN VOLTAGE OF MICRO-ELECTROMECHANICAL STRUCTURES USING TOPOLOGY OPTIMIZATION

The design problem consists in maximizing the pull-in voltage using topology optimization method, which is formulated as an optimal material distribution. In addition to the classical volume constraint, different structural constraints could be taken into consideration. Sensitivity analysis is one of the key issues of the optimization process and is performed with the formulation of eigenvalue topology optimization problems. Here the paper investigates topology optimization of strongly coupled electromechanical systems. To avoid important modifications of the electric field by the optimization process, this first study considers a non design electrode and use topology optimization to design an optimal suspension structure. Solution procedure of the optimization problem is based on CONLIN optimizer using a sequential convex programming. This method that has proved its efficiency in many structural problems (sizing, shape) is here tailored to strongly coupled multiphysics design problems under consideration. The choice of appropriate explicit convex approximations schemes for multiphysic problems is investigated. The proposed method is illustrated and validated on microbeam optimization applications

Las costumbres de los israelitas [Texto impreso]

Sign. : calderon-5calderon8, A-P8, Q

Costumbres de los israelitas

Copia digital. Madrid : Ministerio de Cultura. Subdirección General de Coordinación Bibliotecaria, 2010Sign.: A-2L8/4, 2M6Port. con viñeta xil

Measurement of Extraction and Absorption Parameters in GaN-based Photonic-crystal Light-emitting Diodes

The light extraction efficiency of photonic-crystal (PhC) light-emitting diodes (LEDs) relies on the competition between the PhC extraction and dissipation mechanisms of the guided light within the LED. This work presents the experimental determination of the PhC extraction length of each guided mode and the absorption coefficient of the active region (AR) and quantum wells (QWs) from the observation of the LED far-field emission using a high-resolution angle-spectrum-resolved measurement. The angular and spectral linewidths of the extracted guided modes reveal, depending on the spectral range, the modal extraction length of the PhCs, the AR absorption length, or a combination of both. Modes with a high confinement with the QWs presented a shorter absorption length compared with their extraction length by a shallow surface PhC (95-nm-deep), meaning that the AR absorption was a more efficient mechanism than the PhC extraction. The measured modal extraction length of the shallow surface PhC varied in the range of 55–120 μm, which determines the minimum dimensions of the device and the maximum acceptable dissipation length for an efficient extraction of the guided light by the PhCs. This paper presents also a discussion on the PhC designs that yield PhC extraction lengths shorter than other dissipation lengths, a fundamental requirement for high-efficiency PhC LEDs. The same technique was also applied to estimate the absorption coefficient of the InGaN-based QWs, and can be extended to experimentally determine losses by metallic layers from electrical contacts or other dissipation mechanisms, which are parameters of interest to a broader class of optoelectronic devices, not only PhC LEDs.Engineering and Applied Science

Christau doctriñ berri-ecarlea christauari dagozcan : eguia sinis-beharren-berría dacarrena

Sign.: A-O8, [calderón]3Dialecto : texto en dialecto central -- guipuzcoano. Algúnpasaje (171) eneuskera labortanoS. XVIII -- Periodo : primer euskera modernoEuskalkia : erdialdekoa -- gipuzkera. Pasarteren bat lapurteraz (171.)XVIII. md. -- Lehen euskera modernoaDigitalización. Vitoria-Gasteiz : Fundación Sancho el Sabio, 2008Digitalización. Vitoria-Gasteiz : Archivos y Bibliotecas, Febrero 199

[Cathechismul cel mic istoricesc în carele pre scurt se cuprind sfintele întâmplări şi învăţătura creştinească]

[Cathechismul cel mic istoricesc în carele pre scurt se cuprind sfintele întâmplări şi învăţătura creştinească] / [aşezat de arhimandritul Claudie Fleuri] ; [iară pre limba românească prefăcut (...) de Vasilie Colossi]. - [Buda] : [în Crăiasca Tipografie a Universitatei Ungureşti], [1814]. - 194 P., [3] f. ; 18 cm. Text în limba română cu caractere chirilice. - Exemplar incomplet: lipsă pagina de titlu. - Însemnări