• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 1598
  • 689
  • 348
  • 186
  • 180
  • 93
  • 71
  • 54
  • 46
  • 32
  • 19
  • 18
  • 11
  • 10
  • 7
  • Tagged with
  • 3972
  • 574
  • 489
  • 467
  • 464
  • 428
  • 404
  • 399
  • 370
  • 360
  • 330
  • 315
  • 311
  • 306
  • 306
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
401

Método beam search aplicado ao problema de escalonamento de tarefas flexível / Beam search method applied to the flexible job shop scheduling problem

José Eurípedes Ferreira de Jesus Filho 06 June 2013 (has links)
O Job Shop Scheduling Problem é um problema NP-Difícil que chama a atenção de muitos pesquisadores devido seu desafio matemático e sua aplicabilidade em contextos reais. Geralmente, principalmente em cenários próximos aos de fábricas e indústrias, obter um escalonamento ótimo por meio de métodos computacionais exatos implica em um alto desprendimento de tempo. Em contrapartida, devido às exigências de um mercado cada vez mais competitivo, as decisões de onde, como, quando e com o que produzir devem ser tomadas rapidamente. O presente trabalho propõe o desenvolvimento de um método heurístico Beam Search para solucionar o Job Shop Scheduling Problem e o Flexible Job Shop Scheduling Problem. Para isso, inicialmente um algoritmo do tipo list scheduling é definido e então o método Beam Search é construído baseado neste algoritmo. Os métodos propostos foram avaliados em diferentes níveis de complexidade utilizando instâncias da literatura que retratam diferentes cenários de planejamento. Em linhas gerais, as soluções encontradas se mostraram bastante competitivas quando comparadas a outras soluções da literatura. / The Job Shop Scheduling Problem is a NP-Hard problem which draws the attention of researchers due to both its mathematical challenge and its applicability in real contexts. Usually, mainly in industry and factory environments, an optimal schedule got by the use of exact computational methods implies in a long spending time. On the other hand, due to a more and more competitive marketplace, the decisions on where, how, when and with which to produce must be taken quickly. The present work proposes the development of an heuristic Beam Search method to solve both the Job Shop Scheduling Problem and the Flexible Job Shop Scheduling Problem. To that end, at rst a list scheduling algorithm is dened and then the Beam Search method is built based on the list scheduling algorithm. The proposed methods were evaluated over dierent complexity levels using instances from the literature that report dierent planning environments. In general terms, the solutions implemented have been proved very competitive when compared against other solutions in the literature.
402

Měření parametrů ultrazvukového svazku / Measurement of ultrasonic beam parameters

Hlavatý, Radek January 2021 (has links)
The work deals with methods of measuring the parameters of the ultrasonic beam generated by piezoelectric sensors. The theoretical part contains a literature search of methods for the analysis of the ultrasonic beam generated by piezoelectric transducers with dimensions of units of millimeters. The problematics of measurement using piezoelectric or optical fiber hydrophones is investigated in more detail. The scope of the practical part of the work is the design and implementation of measuring equipment that allows spatial analysis of the beam during propagation by a complicated signal path, for automotive level and concentration sensors of the company Vitesco Technologies s.r.o. The system uses a hydrophone method to measure the ultrasonic beam. Due to test measurements, the repeatability of the measured results is confirmed, the results are discussed in the end.
403

Měření mechanické stability budov a stožárů využívaných pro FSO spoje / Measurement of the Mechanical Stability of Buildings and Consoles Used for the FSO Links

Kočvara, Pavel January 2015 (has links)
The Master's thesis deals with the determination of measurement method of deflection the axis of the optical beam from its ideal position, which is caused by action of force of strong winds affecting the positional stability of the building or supporting structure (tower) used for placement of FSO links'heads. The thesis informs the readers about the other causes of deflection of beam axis in a real environment, about methods of determining the position of the beam axis in the plane perpendicular to the beam axis and the basic properties and parameters of the Gauss beams, including the phenomenon of diffraction on the output aperture of the laser transmitter.
404

Reliéfní difraktivní struktury pro optické elementy realizované pomocí elektronové litografie / Manufacturing of Relief Diffractive Structures for Optical Elements Using Electron Beam Lithograph

Daněk, Lukáš January 2009 (has links)
This thesis describes several techniques for the optimization of the manufacturing of relief diffractive structures used as optical elements by Electron beam lithograph BS600 in the Electron beam laboratory of the Institute of Scientific Instruments of the Academy of Sciences of the Czech Republic. The Electron beam lithograph BS600 was originally developed and constructed in the Institute of Scientific Instruments of the Academy of Sciences of the Czech Republic for Tesla in 1983, but is still developing, which was published. The Electron been lithograph BS600 is specific in these days because of its accelerating potential and is unique in the world because of the possibility to shape the beam. The optimization of manufacturing of relief diffractive structures, used as optical elements, was mostly reached by analysis, bringing optimal solution for the required effect. Moreover, an algorithm was developed for driving the electron beam position, shape, size and the time of each elementary exposition. The analysis showed that is convenient to use mathematical description of separate lines of diffractive structures. A separate subject was carried out for the calibration of the exposition field of the Electron beam lithograph BS600.
405

Diagnostika a zhodnocení stavu konstrukce mostu / Diagnostics and assessment of the structure of bridge

Lehocký, Peter January 2022 (has links)
This diploma thesis focuses on diagnostics of bridge structures. First part of this diploma thesis will focus on theoretical knowledge about bridge structures and common diagnostic techniques suited for examining material priperties of samples taken from structure. Second part of this thesis will focus on practical use of experiments used in diagnostic branch. I will be doing visual observation of concrete structure followed by experiments on core samples. End of thesis will be evaluating structure from global perspective and will deliver specific sugestions for renovation.
406

Nákupní centrum v Brně / Shopping mall in Brno

Brozmanová, Dagmar Unknown Date (has links)
The aim of the diploma thesis is to design and assessment of the steel structure of shopping mall, which is situated in Brno. Three variants were processed, from which one was selected for more detailed processing. Variants have hexagonal floor plan with maximum dimension 60,0 m, four floors and same structural solution. They differ in plan of secondary beams and columns, in floor plan of glass atrium and used cross-sections. Building´s load-bearing structure consists of pin-supported columns, primary beams, secondary beams and purlins. Rigidity of the structure is enshured by system of vertical bracings and in horizontal direction by composite slab. The structure elements are made of steel S355, except secondary beams, which are made of steel S235.
407

Damage Detection in a Steel Beam using Vibration Response

Sharma, Utshree 03 August 2020 (has links)
No description available.
408

Operation of Cold STM System In Conjunction With In Situ Molecular Beam Epitaxy

Foley, Andrew January 2012 (has links)
No description available.
409

A Methodology for the Design of Spaceborne Pencil-Beam Scatterometer Systems

Spencer, Michael W. 14 May 2003 (has links) (PDF)
Spaceborne scatterometer instruments are important tools for the remote sensing of the Earth's environment. In addition to the primary goal of measuring ocean winds, data from scatterometers have proven useful in the study of a variety of land and cryopshere processes as well. Several satellites carrying scatterometers have flown in the last two decades. These previous systems have been "fan-beam" scatterometers, where multiple antennas placed in fixed positions are used. The fan-beam scatterometer approach, however, has disadvantages which limit its utility for future missions. An alternate approach, the conically-scanning "pencil-beam" scatterometer technique, alleviates many of the problems encountered with earlier systems and provides additional measurement capability. Due to these advantages, the pencil-beam approach has been selected by NASA as the basis for future scatterometer missions. Whereas the fan-beam approach is mature and well understood, there is need for a fundamental study of the unique aspects of the pencil-beam technique. In this dissertation, a comprehensive treatment of the design issues associated with pencil-beam scatterometers is presented. A new methodology is established for evaluating and optimizing the performance of conically-scanning radar systems. Employing this methodology, key results are developed and used in the design of the SeaWinds instrument - NASA's first pencil-beam scatterometer. Further, the theoretical framework presented in this study is used to propose new scatterometer techniques which will significantly improve the spatial resolution and measurement accuracy of future instruments.
410

Analysis of a Thin-Walled Curved Rectangular Beam with Five Degrees of Freedom

Moghal, Khurram Zeshan 13 December 2003 (has links)
A study of a thin-walled curved rectangular box beam under torsion and out-of-plane bending is documented in this thesis. A new one-dimensional theory that takes into account warping and distortion in the beam cross-sections is the main focus. Existing available theories for thin-walled curved beams lack rigorous theoretical development, and most have ignored the effects of warping and distortion. A higher order theory including two additional degrees of freedom corresponding to warping and distortion was derived. The conventional three degrees of freedom model was compared with the new five degrees of freedom model. The variation of beam thickness to control and decrease the high distortion variable is investigated.

Page generated in 0.3912 seconds