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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.
631

A Study in the Design and Development of a Baseball Pitching Machine

Lundwall, Neal M. 01 May 1971 (has links)
Throughout history man has had the need of services which require great skill or tremendous strength or delicate consistency on the part of those who perform. Much of the time he has turned to the machine to accomplish these requirements.
632

Containers & Virtual machines : A performance, resource & power consumption comparison

Lindström, Martin January 2022 (has links)
Due to the growth of cloud computing in recent years, the use of virtualization has exploded. Virtual machines (VMs) and containers are both virtualization technologies used to create isolated computing environments. While VMs are created and managed by hypervisors and need their own full guest operating system, containers share the kernel of the host computers and do not need a full guest operating system. Because of this, containers are rumored to have less overhead involved, yielding higher performance and less resource usage compared to VMs.  In this paper we perform a literature study along with an empirical study to examine the differences between containers and virtual machines when it comes to cpu, memory and disk performance, cpu and memory resource utilization, and power consumption. To answer the question regarding performance, a series of benchmarks were run inside both a container and a VM. During these benchmarks the resource utilization of the host machine was also measured to answer the second question and to answer the third and final question the power draw was measured while some of the benchmarks were running. The results showed that the cpu performance was extremely similar between the two and memory performance seemed to be similar for the most part but fairly big differences were seen in favor of both depending on the benchmark in some cases. With disk performance the container was between 15-50% faster depending on the benchmark. As for resource usage, the cpu usage was the same for both technologies but memory usage differed greatly in favor of the container. The VM used between 3-4 GiB and the container between 70 MiB - 2.5 GiB depending on the benchmark. The power draw was the same for both technologies when under cpu and memory load but when idle the VM proved to draw around 40% more power.
633

Controlled Trim-Blasting Model to Improve Stability and Reduce Vibrations at a Production Gallery of the San Ignacio de Morococha S.A.A. Mining Company

Camallanqui-Alborque, C., Quispe, G., Raymundo-Ibañeez, C. 25 November 2019 (has links)
This paper presents a blasting method called controlled trim blasting, in which the rock mass of an unstable gallery where high levels of vibration have been detected is analyzed. This methodology comprises a drilling mesh with two-contour gallery assessment, producing its drilling machines and determining the type of explosive used and burden and spacing, which will be detonated after the internal blasting. Further, the internal blasting will possess its drilling machines, burden, spacing, and a second type of explosive. The separation of the gallery into smaller parts will improve the blasting, as verified in the recorded simulation. In addition, the rock-mass stability improves because the explosives used in the perimeter of the gallery are low-power with mild detonation pressure, which does not generate high levels of vibration. This is a practical and efficient method in areas where the rock mass is not good or there is a mixture of rock types.
634

Análisis de una plataforma para aplicaciones web con una arquitectura basada en contenedores para implementar servicios dirigidos a startups

Quispe Cieza, Francisco 27 February 2020 (has links)
Cuando una startup sale al mercado, se enfoca en crecer exponencialmente, utilizando una idea innovadora y un presupuesto relativamente bajo. Este crecimiento exponencial se apoya en la tecnología, la cual debe manejar un rendimiento adecuado en los recursos de hardware para los servicios, acorde con el giro del negocio. El objetivo principal de este trabajo es realizar un análisis de una plataforma para aplicaciones web con una arquitectura basada en contenedores, que sea capaz de soportar el crecimiento exponencial de usuarios de sus servicios Web. Las arquitecturas tradicionales basadas en servidores físicos implican tiempos y costos de configuración, despliegue y mantenimiento que son altos. Cuando se hace necesario escalar, se requiere, normalmente, de más recursos de hardware y de tiempo para realizar las configuraciones necesarias. La flexibilidad que provee la virtualización de servidores agiliza los procedimientos de escalamiento y reduce considerablemente el tiempo y los costos, comparados con las soluciones basadas solamente en hardware. Sin embargo, para atender requerimientos más exigentes, la virtualización tiene una huella muy pesada y tiempos de despliegue todavía elevados. La tecnología de contenedores nos ofrece una plataforma liviana y eficiente. Un contenedor es un paquete ejecutable muy liviano que aísla una pieza de software, incluyendo todo lo necesario para ser ejecutado. Está claro que la velocidad y la eficiencia son las mayores necesidades para las startups, y Docker, uno de los líderes en el mercado de contenedores de software, es capaz de proporcionarlas de manera efectiva. Si bien es cierto no ha reemplazado a las máquinas virtuales, se está notando el potencial de Docker. Eso no quiere decir que las máquinas virtuales quedaran obsoletas, por el contrario, Docker y las máquinas virtuales coexistirán uno al lado del otro, dando a los startups más opciones para ejecutar sus aplicaciones en la nube. / When a startup goes to market, it focuses on growing exponentially, using an innovative idea and a relatively low budget. This exponential growth is supported by technology, which must handle adequate performance in the hardware resources for services, in accordance with the line of business. The main objective of this work is to carry out an analysis of a platform for web applications with a container-based architecture, which is capable of supporting the exponential growth of users of its Web services. Traditional physical server-based architectures involve high configuration, deployment, and maintenance times and costs. When scaling becomes necessary, it usually takes more hardware and time to complete the necessary configurations. The flexibility that server virtualization provides streamlines escalation procedures and greatly reduces time and cost, compared to hardware-only solutions. However, to meet more demanding requirements, virtualization has a very heavy footprint and still high deployment times. Container technology offers us a lightweight and efficient platform. A container is a very lightweight executable package that isolates a piece of software, including everything needed to be run. It is clear that speed and efficiency are the greatest needs for startups, and Docker, one of the leaders in the software container market, is capable of providing them effectively. While it's true it hasn't replaced virtual machines, Docker's potential is being noticed. That doesn't mean that virtual machines will become obsolete, on the contrary, Docker and virtual machines will coexist side by side, giving startups more options to run their applications in the cloud. / Tesis
635

Prédiction du niveau de bruit aéroacoustique d'une machine haute vitesse à reluctance variable / Aeroacoustic noise prediction for a high speed switched reluctance motor

Parrang, Sylvain 02 November 2016 (has links)
Simples à produire et robustes, les machines électriques à reluctance variable sont adaptées à des conditions sévères de fonctionnement, notamment à vitesse élevée. Les machines à reluctance variable (MRV) ne sont cependant que rarement utilisées principalement en raison du niveau élevé de bruit qu'elles émettent. Les travaux menés au cours de cette thèse visent, dans un premier temps, à qualifier le bruit émis par une machine à reluctance variable à haute vitesse de rotation. Conformément à ce qui est communément admis, il a été établi que le bruit émis en haute vitesse par la machine étudiée est dominé par le bruit aérocoustique. Le bruit aéroacoustique consiste en l'ensemble des émissions sonores issues de phénomènes aérodynamiques qui prennent naissance dans l'entrefer de la machine. Le second chapitre de l'étude est consacré à la mise en place d'une méthode d'estimation quantitative du bruit aéroacoustique émis par la machine étudiée. Le bruit aéroacoustique n'ayant pas encore été étudié de manière quantitative pour les machines électriques, l'étude se tourne vers les machines tournantes (turboréacteur, ventilateurs, ...) pour lesquelles la littérature sur le bruit aéroacoustique est abondante. Une méthode d'estimation du bruit aéroacosutique émis par la machine est alors construite. Cet estimateur se base sur une simulation de dynamique des fluides en deux dimensions de l'écoulement turbulent dans l'entrefer. Vient ensuite une confrontation des niveaux de bruit estimés avec des données expérimentales. Le bruit émis par la machine étudiée est calculé et mesuré pour deux géométries différentes du rotor sur une large plage de vitesses de rotation. La cohérence observée entre les résultats expérimentaux et numériques valide les hypothèses formulées au chapitre précédent tout en soulignant, comme attendu, les limites de la méthode de calcul en deux dimensions. Enfin, dans un quatrième chapitre, la méthode d'estimation du niveau de bruit aéroacoustique est utilisée afin d'explorer l'influence des paramètres géométriques de la machine sur son niveau de bruit. / Due to its simple construction and robustness, Switched Reluctance Machine (SRM) is well suited for high rotation rates. SRM applications are however quite rare mainly because of the high level of noise this machine produces. First, this work aims to describe the noise emmitted by the studied SRM at high rotation rates. In accordance with the common understanding, it was proven that noise emitted by high rotation rates SRM is dominated by aeroacoustic noise. The aeroacoustic noise consists of the whole soundemission comig out of aerodynamic phenoma located in the air gap of the machine. Chapter two is concerned with the implementation of an estimation method for aeroacoustic noise level dedicated to the studied SRM. Aeroacoustic noise for electrical machines has not been quantitatively studied yet. Conversely, studies about aeroacoustic noise of rotating machinery (turboreactor, fan, ...) is quite abundant in the litterature. Consequently, this study focuses onrotating machinery to build an aeroacoustic noise estimation method for SRM. This estimationtool is based on a Computational Fluid Dynamics (CFD) calculation of the turbulent ow in theair gap. Estimated noise levels are then compared with experimental data. Emitted noise level is estimated and measured for two distinct rotor geometries over a wide range of rotation rates. Calculation assumptions are validated by the consistency between experimental and numerical results. Asexpected, the 2D CFD simulation brings an over estimation of noise level. Finally, the fourth chapter deals with the use of the aeroacoustic noise estimation tool to study the influence of geometrical parameters of a SRM on its noise emission level.
636

Návrh nové výrobní technologie zadaného dílu / A design of new production technology of a specified part

Paška, Josef January 2021 (has links)
This diploma thesis focuses on the design of new technology for the production of a given part by company Poppe + Potthoff s.r.o. The thesis is divided into three parts. The first part is a theoretical analysis of individual operations that are necessary for the production of the given part. The second part deals with the analysis of the current technological process of production. In the third part, a new technological process is proposed. In the end, there is a technical and economic evaluation performed, where both variants are compared.
637

Kinematics of helical filament winding on circular and elliptic cylindrical mandrels

Maki, Sandra January 1988 (has links)
No description available.
638

Performance of a tangential feed threshing cylinder as affected by corn cob break-up and concave design parameters.

Wall, Gavin Lindsay. January 1981 (has links)
No description available.
639

Performance Improvement of Switched Reluctance Motor (SRM) Drives Through Online Optimization Based Reference Current Identification and Digital Sliding-Mode Control

Dhale, Sumedh January 2021 (has links)
This thesis presents a torque control mechanism for switched reluctance machine (SRM) drives. The proposed mechanism is capable of maintaining ripple free torque control while minimizing the copper loss or mode-0 radial force or both at a fixed switching frequency. In the proposed approach, the torque control problem is addressed by splitting it into two parts. The first part consists of identification of optimum phase current references while the second part incorporates the design of an efficient current controller. For the identification of optimum phase current references, three algorithms are presented in the form of a developmental process. The nature of the online optimization problem is demonstrated using a simple 2-dimensional gradient descent method. Subsequently, a parametric form gradient descent algorithm is presented which transforms the original optimization problem into two 1-dimensional problems, viz. torque error minimization and identification of optimum search direction. This method yields improved computational efficiency and accuracy. The third algorithm incorporates projection using equality constraint on the phase torque contributions to achieve a 1-dimensional solution process. Although this algorithm takes more iteration as compared to the parametric form gradient descent algorithm, it demonstrates greater accuracy and computational efficiency. A comparative analysis of these algorithms is performed in at different operating conditions in terms of the torque ripple magnitude and computational effort. The thesis also presents a comprehensive analysis of well known control techniques for application in SRM current control in discrete-time domain. This analysis also presents a comparative evaluation of these control techniques under different operating conditions. On account of this analysis, several recommendations pertaining to the performance improvement are presented. Finally, a digital sliding-mode based model-free current controller suitable for fixed switching frequency operation is presented. The proposed controller is capable of providing a consistent dynamic response over wide operating range without utilizing any model information. The reference current tracking performance of this controller is verified through simulation studies in MATLAB/Simulink® environment and over a 1.2kW, 100V, 2500RPM, 12/8 experimental SRM drive. / Thesis / Doctor of Philosophy (PhD)
640

Analysis and time calculations of NC files : Time calculation of Nailing Bridge machine movements

Rohnér, Julia, Sköld, Emelie January 2023 (has links)
Randek is a company that develops machines. The machines are used to build prefabricated houses. They have developed a CNC machine called Nailing Bridge that creates house walls. One of their issues is that they must predict the time it takes to build a wall because their customers need to know how long it takes to deliver their house. Our project solves this problem by making a program that calculates the time it takes to build a wall on the Nailing Bridge with help from NC files (Numerical Control files) consisting of G-code. One NC file contains the machine's operations, such as sawing, nailing, and routing. The goal was to develop a program with a maximum margin of error of 3% from reality. The machine was tested to measure the time of different operations to develop the program, and the NC files were analysed. Calculations for the jerk, acceleration, deceleration, and velocity of the CNC machine were considered to predict the time of the movements with high enough precision. The calculations and implementation are written in C#. A GUI is created for the user to use the program easily. The end product is a program that can take in one NC file and gives output on the time it should take for the Nailing Bridge to go through the file. The margin of error was between 5% to 31% for one operation of sawing or nailing, which is significantly higher than the goal of 3%. The program was therefore debugged with unit testing and new tests of the Nailing Bridge to find the sources for this margin of error. The conclusion is that the program works but not exactly to the company's standards.

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