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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.
1

A Study of the Hammer Impact

Hsu, Yu-ming 09 August 2006 (has links)
The purpose of this study is to investigate the impact effects of varied forms of a hammer on a nail of different material. To achieve the study purpose, the researcher integrated the computer-aided design software SoildWorks and finite element analysis software LS-DYNA to analyze some familiar hammer heads with varied shapes for striking nails. After observing the results of simulation, the researcher compared efficiencies of the physical properties and the mechanical effects. In addition, the researcher simulated different materials and sizes of the nail stricken by a hammer. He found out the best slenderness ratio of the nail. The researcher hoped that his study could provide the other designers to produce more effective hammers and nails.
2

Acoustic impedance matching of a liquid-air termination within a pipe

Lunn, Robert Joseph, 1927- January 1961 (has links)
No description available.
3

Technique and performance level comparisons of male and female hammer throwers /

Konz, Suzanne M., January 2006 (has links) (PDF)
Thesis (Ph. D.)--Brigham Young University. Dept. of Exercise Sciences, 2006. / Includes bibliographical references (p. 119-124).
4

Development of a model to calculate mechanical specific energy for air hammer drilling systems

Okuchaba, Boma Jeremiah 15 May 2009 (has links)
Drilling for hydrocarbons is an expensive operation; consequently operators try to save costs by reducing the number of days spent during this operation. Drilling efficiently with the highest attainable rate of penetration is one of the ways drilling time could be reduced. Real-time monitoring of Mechanical Specific Energy will enable drilling engineers to detect when the optimum drilling rate for a given set of drilling parameters is not being achieved. Numerous works have been done on air hammers and rock Mechanical Specific Energy. Previous research has shown that Mechanical Specific Energy, which is a ratio that quantifies the input energy and Rate of Penetration (ROP) of a drilling system, is directly proportional to the rock compressive strength being drilled. The Mechanical Specific Energy model utilizes drilling parameters such as ROP, Weight on bit (WOB), RPM, torque, flow-rate, bottom-hole pressure, and bottom-hole temperature to show how effectively energy being put into the drill string is being converted to ROP at the bit. This research effort proposes a new model to calculate the Mechanical Specific Energy for air hammer drilling systems. A thermodynamic model for the air hammer from which the piston impact velocity and kinetic energy is obtained is presented. To be able to estimate the effective energy delivered to the rock by the hammer, the stress wave propagation model is used and factored into the Mechanical Specific Energy model. The Mechanical Specific Energy values obtained from the application of this model provide a qualitative indicator of formation pressure changes and a means for drilling engineers to detect when optimum drilling rate is not being achieved. It can be deduced from the model that the impact energy of the hammer is greatly affected by the pressure drop across the hammer and since the hammer accounts for about sixty percent of the energy required for destroying the rock, the ROP can be varied by varying the pressure drop across the hammer.
5

Joseph Freiherr von Hammer-Purgstall (1774-1856) : ein Dichter und Vermittler orientalischer Literatur /

Elgohary, Baher Mohamed, January 1979 (has links)
Texte remanié de: Diss.--Wien, 1974. / Bibliogr. p. 263-276. Notes bibliogr.
6

Vapor cavity formation in a pipe after valve closure

Heath, William Estill 12 1900 (has links)
No description available.
7

Water hammer in pipelines caused by periodic operation of an upstream value

Beatty, David Alexander 12 1900 (has links)
No description available.
8

State and Parameter Estimation in Quantum Theory

Kubitzki, Marcus. January 2003 (has links)
Konstanz, Univ., Diplomarb., 2003.
9

Numerical analysis of condensation induced water-hammer in horizontal piping systems

Eichenberg, Thomas William 21 August 1990 (has links)
Condensation Induced Water-Hammer, CIWH, has been an historical problem for the nuclear power industry over the past 2 decades. It has caused damage to plant systems, and considerable anguish to plant operators. This thesis has embarked on an attempt to characterize the fluid motion, heat transfer, mixing, and stability of a horizontal, stratified flow of steam over subcooled water. A literature review was conducted to determine the state of numerical and analytical methods which have been applied to this problem. The result of the review has led to the implementation of new analytical interfacial stability models. Information from the review has also led to the development of correlations for wave frequency and amplitude on the phase interface. A numerical model has been developed to estimate the temperature profile on the phase interface. Also, the model will construct, by use of the above correlations, an estimate of the interface wave structure. This wave structure is then evaluated against a non-linear model for interface stability to determine the onset of slug formation. The numerical model has been used to evaluate two known CIWH events. The results indicate that the onset of slug formation is necessary, but not sufficient, to ensure a water-hammer event. The results imply that there is the possibility that once a slug has formed, it may break up before a trapped steam void can fully collapse. The model also indicates that CIWH in steam generator, feedwater nozzle sections is not due to the formation of slug on an unstable phase interface. Rather, CIWH may occur when the liquid level inside of the feedwater nozzle is above the top of the feedring, thus creating an isolated steam pocket. The rapid condensation of the trapped steam in the causes CIWH. This particular result implies that it may be possible to completely avoid CIWH in the feedwater nozzle altogether. / Graduation date: 1991
10

A laboratory investigation of water hammer associated with the establishment of flow in a pipeline containing centrifugal pumps

Martin, Charles Samuel 05 1900 (has links)
No description available.

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