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  • 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.
181

Integral control of infinite-dimensional linear systems subject to input hysteresis

Mawby, Adam D. January 2000 (has links)
No description available.
182

Controle robusto de sistemas não-lineares sujeitos a falhas estruturais /

Silva, Emerson Ravazzi Pires da. January 2009 (has links)
Orientador: Edvaldo Assunção / Banca: Marcelo Carvalho Minhoto Teixeira / Banca: Alfredo Del Sole Lordelo / Resumo: Uma técnica de projeto de controladores robustos para sistemas não-lineares contínuos no tempo é proposta neste trabalho. É suposto que a planta não-linear está sujeita a falhas estruturais, que podem ser consideradas como incertezas politópicas. Os sistemas não-lineares são representados por modelos fuzzy propostos por Takagi-Sugeno e uma formulação para o tratamento das incertezas politópicas é apresentado para o projeto dos controladores. Este trabalho aborda projetos de controle usando a realimentação dos estados e a realimentação da derivada dos estados. O projeto do controlador é realizado através de condições baseadas em Desigualdades Matriciais Lineares (em inglês, Linear Matrix Inequalities (LMI)), que podem ser resolvidas facilmente utilizando técnicas de programação convexa. Essa metodologia permite a inclusão de restrições de desempenho no projeto, tais como: taxa de decaimento e restrição na entrada. Ao final, exemplos numéricos e suas simulações ilustram a eficiência da técnica proposta. / Abstract: A technique of robust controllers design for nonlinear continuous-time systems is proposed in this work. It is supposed that the nonlinear plant is subject to structural failures, which can be considered as polytope uncertainties. The nonlinear systems are represented through fuzzy models proposed by Takagi-Sugeno and a formulation for the treatment of polytope uncertain is presented for the controllers design. This work focuses control designs using state feedback and state-derivative feedback. The controllers design is made through conditions based in Linear Matrix Inequalities (LMIs), which can be easily solved using convex programming techniques. This methodology allows the inclusion of performance restrictions on design, such as: decay rate and input constraint. Finally, numeric examples and their simulations show the efficiency of the proposed method. / Mestre
183

Using containers in a continuous integration and delivery environment : A performance and scalability comparison

Olle, Emilsson, Marcus, Hrvatin January 2018 (has links)
With a software industry that is moving at a fast pace, continuous integration and delivery is something important for many products today. Moreover, with containers being on the rise since 2013, more companies are moving their CI/CD environment into containers not only for development but also for testing. This thesis begins with giving the reader an introduction to containers, container orchestration, and Jenkins, which is a continuous integration and delivery tool. The experiment was then set up with one container based cluster and one single node machine. Two kinds of experiments were run on them, one big job and one small job. The system scalability is assessed, and with smaller clusters the memory overhead could be an issue. Performance wise, the container cluster is performing better than a single node machine, as long as it is utilizing all its nodes. Security with containers is still an issue and it could be fatal for a cluster if it is compromised.
184

Structure and dynamics of vortices in superfluid helium-3

Karimäki, J. (Janne) 06 February 2012 (has links)
Abstract In this thesis, the structure and the dynamics of vortices are studied from the standpoint of the hydrodynamical theory of superfluids. In the hydrodynamical theory a superfluid is described by a continuous order parameter field. In the case of superfluid helium-4 this field is a complex-valued function of position and time. However, in superfluid helium-3 the order parameter is a complex-valued 3 × 3 matrix. The first part of this work consists of studies on structures that appear in the order parameter field, when a vessel filled with superfluid helium-3 in the A phase (3He-A) is rotated in an external magnetic field. Among the most common of these structures are the so-called continuous vortices. They exist in several different forms. In addition to vortices, other possible structures include the vortex sheet of 3He-A that was discovered at the Low Temperature Laboratory of Helsinki University of Technology (currently Aalto University) in late 1993. In this thesis, these structures were studied by finding stationary vortex configurations that minimize the free energy of the superfluid. An algorithm for minimizing the free energy was implemented by writing a computer program. This program was then used to study the structure of a few vortex types, inferred to be the most probable ones. In addition, regular lattices formed by these vortices, including the vortex sheet, were studied. A phase diagram for vortex lattices was constructed by comparing the free energy of various lattice structures as a function of rotational velocity and external magnetic field. The study of vortex structures also lead to a discovery of a new type of vortex in 3He-A, later named the LV3 vortex. In the second part of the work, the dynamics of vortices was studied using a filament model of vortex motion, which also has its theoretical justification in the hydrodynamical model of superfluids, but where the detailed structure of the vortex core is not relevant. The specific problem under consideration here was the motion of a quantized vortex in a rotating elongated cylinder filled with superfluid, and how the motion of the vortex depends on temperature and the rotational velocity of the vessel. The study of vortex motion was simplified using scaling laws. A new type of scaling law was discovered, which both simplified the specific problem under study, and made the results more general. In summary, the research in this thesis touched upon two somewhat complementary areas, i.e. the structure of continuous vortices in 3He-A and the dynamics of thin vortex lines, which is more applicable to superfluid 4He or to the B phase of superfluid helium-3 (3He-B). However, these areas complement each other in advancing the general scientific understanding about the properties of superfluids.
185

Continuous seismic reflection profiling in the Strait of Georgia, British Columbia

Tiffin, Donald Lloyd January 1969 (has links)
Approximately 790 kilometers of continuous seismic reflection data were obtained with a 5000 joule Sparker in the Strait of Georgia, southwestern British Columbia. The Strait is a geological boundary between Upper Cretaceous Nanaimo Group rocks of the Vancouver Island area and Late Cretaceous-Early Tertiary continental rocks found in scattered outcrops on the southern mainland. Coast Intrusives form mountains on the mainland northeast of the Strait. The Fraser River has built a large submarine delta across the Strait and is the main source of Recent sediments. Deposition is occurring mainly on the delta front and in deep basins to the northwest. In the basin adjacent to the delta, flat-lying bottomset beds average about 200 meters in thickness. An older layer of bottomset beds in this basin overlies bedrock and extends under the present foreset beds. Thinner sedimentary layers of possible hemipelagic origin overlie Pleistocene banks and ridges along the mainland north of the delta. No significant amounts of Recent sediment are presently accumulating in the Strait south of the delta. Erosion of possible Late Pleistocene deltaic sediments has deepened the Strait in that area. Pleistocene deposits of probable drift, till and interglacial sediments occur mainly along the northeast side of the Strait. One extensive stratified deposit, possibly correlated with exposed Pleistocene deposits on nearby shorelines, may reach 550 meters in thickness. Below the Pleistocene, stratified reflectors, suspected to be Late Cretaceous-Early Tertiary bedrock, unconformably overlie Coast Intrusive bedrock along the mainland shore. The reflectors dip seaward at 8 degrees or more. Along the southwest Island coast Upper Cretaceous bedrock dips into the Strait. Deformation, most severe in the south, decreases northward. Dips of bedrock reflectors become less in mid-Strait before disappearing under delta deposits toward the mainland. Some synclinal and anticlinal folding occurs near mid-Strait. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate
186

Lateral stability of continuous glulam beams

Everest, Edwin Albert January 1968 (has links)
This thesis presents the results of a theoretical and experimental study of the lateral buckling of straight beams of rectangular cross-section resting on columns, a type of structure commonly found in the roofing system of multi-bayed buildings. The structure is analyzed as a simply supported beam, uniformly loaded, restrained at one end against longitudinal torsion and resting near the other end on a flexible column which may provide various torsional and lateral restraints. Beyond the column is a cantilevered projection of various lengths and loads. The entire top edge of the beam is considered as fastened to a continuous decking which restrains it against horizontal displacement but permits free rotation about this edge. The method of solution of the theoretical lateral buckling load is by using a computer program to calculate the structure stiffness matrix's determinant at increasing load levels, and a plot of the determinant versus load level yields the critical load (at determinant equals zero). This theoretical approach is verified by model experiments in the laboratory. Design curves and equations are produced incorporating the usual flexural beam and axially loaded column strength concepts, with lateral buckling considerations. Recommended design code procedures are forwarded based on these curves which would permit more economical use of deep beams. Included in the thesis is the computer program listing used in the solution technique. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate
187

Case study of spray design for a continuous billet caster

Agarwal, Prakash K. January 1979 (has links)
The spray cooling system of an operating billet caster has been redesigned with the aim of reducing the formation of mid-way cracks. These cracks are caused by tensile strain which is generated at the solidification front when the surface temperature of the strand rebounds owing to a sharp reduction in surface heat extraction. The objective of the design, therefore, was to achieve a cooling system that would minimize surface temperature rebound of the strand as it passes from one cooling zone to the next. A computer program based on the explicit finite difference method has been used for the design work. The spray design was implemented on one strand of an operating continuous casting machine which produced 10.8 cm square billets. Transverse sections were cut from the test strand and sulfur printed, then compared to sulfur prints of sections taken from an adjacent strand of the same heat but with unmodified sprays. It was shown that with empirical adjustment, the redesigned spray system reduced the severity of mid-way cracks in over 80% of the heats. It was also found that the carbon content and cast structure have a profound effect on the cracking tendency, whereas, the Mn/S ratio (up to 30%) is less effective. Finally, a new design method for sprays has been proposed which may result in a better temperature distribution and may be easier to adjust to suit specific operating conditions. / Applied Science, Faculty of / Materials Engineering, Department of / Graduate
188

Additive Functions

McNeir, Ridge W. 06 1900 (has links)
The purpose of this paper is the analysis of functions of real numbers which have a special additive property, namely, f(x+y) = f(x)+f(y).
189

Multi-factor Authentication : System proposal and analysis of continuous authentication methods

Fält, Markus January 2020 (has links)
It is common knowledge that the average user has multiple online accounts which all require a password. Some studies have shown that the number password for the average user is around 25. Considering this, one can see that it is unreasonable to expect the average user to have 25 truly unique passwords. Because of this multi-factor authentication could potentially be used to reduce the number of passwords to remember while maintaining and possibly exceeding the security of unique passwords. This thesis therefore, aims to examine continuous authentication methods as well as proposing an authentication system for combining various authentication methods. This was done by developing an authentication system using three different authentication factors. This system used a secret sharing scheme so that the authentication factors could be weighted according to their perceived security. The system also proposes a secure storage method for the secret shares and the feasibility of this is shown. The continuous authentication methods tests were done by testing various machine learning methods on two public datasets. The methods were graded on accuracy and the rate at which the wrong user was accepted. This showed that random forest and decision trees worked well on the particular datasets. Ensemble learning was then tested to see how the two continuous factors performed once combined into a single classifier. This gave an equal error rate of around 5% which is comparable to state-of-the-art methods used for similar datasets.
190

Diseño de TPM y 5S en el soplado de envases PET para reducir botellas defectuosas

Del Aguila Peralta, Nataly, Palomino Chanca, Melanny Stefhania 25 July 2019 (has links)
El proyecto se basa en la mejora de los procesos de empresa Industrias John’s, dedicada al soplado, etiquetado y embalado de botellas de Pereftalato de Polietileno, dentro de la Planta de Perú Cola en Ucayali. El problema de la empresa es el número elevado de mermas de la empresa, que traducido en términos monetarios representa un importante porcentaje de pérdidas respecto a los ingresos anuales. Como primer paso se realizará el análisis de los procesos para identificar las principales causas de este problema. Además, se realizarán propuestas que ayudarán a la mejora de los procesos, las que se basan en conceptos de las técnicas de la ingeniería industrial que servirán para atacar y hacer frente el problema central. Las propuestas planteadas y desarrolladas serán evaluadas a fin de determinar los diferentes impactos dentro de la organización. Estas propuestas tienen el fin de reducir las mermas en los dos procesos anteriores. Se trabajan los siguientes puntos: Económico: De acuerdo con la medida que se opte se pueda disminuir el impacto económico que tienen las mermas relacionadas a los ingresos. Estratégico: Se desarrollará una alternativa de solución que le permita a la empresa poder competir con las principales empresas dentro del rubro y pueda estar a la par con la competencia. Además de ello, crear modelos de Mejora Continua. Por último, se optará por la mejor alternativa que aseguren el avance de la empresa, el desarrollo de sus ventajas competitivas a fin de mejorar la situación actual de la empresa, empleando menos recursos y por supuesto con mayores ganancias. / The project is based on the improvement of Industrias John's company processes, dedicated to the blowing, labeling and packaging of polyethylene perethalate bottles, within the Peru Cola Plant in Ucayali. The problem of the company is the high number of losses of the company, which translated into monetary terms represents a significant percentage of losses with respect to annual revenues. The first step will be the analysis of the processes to identify the main causes of this problem. In addition, proposals will be made that will help to improve processes, which are based on concepts of industrial engineering techniques that will serve to attack and address the central problem. The proposals proposed and developed will be evaluated in order to determine the different impacts within the organization. These proposals are aimed at reducing the merchandise in the two previous processes. The following points are worked: Economic: According to the measure chosen, the economic impact of the losses related to income can be reduced. Strategic: A solution alternative will be developed that allows the company to compete with the main companies within the field and can be on par with the competition. In addition to this, create models of Continuous Improvement. Finally, we will choose the best alternative to ensure the progress of the company, the development of its competitive advantages in order to improve the current situation of the company, using fewer resources and of course with higher profits. / Tesis

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