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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.
21

Analysis of cutting parameters and heat generation on bits of a continuous miner using numerical and experimental approach /

Mishra, Brijes. January 2007 (has links)
Thesis (Ph. D.)--West Virginia University, 2007. / Title from document title page. Document formatted into pages; contains ix, 104 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 94-96).
22

Prediction of wellbore trajectory considering bottom hole assembly and drillbit dynamics /

Brakel, Johannes Daniel. January 1986 (has links)
Thesis (Ph.D.)--University of Tulsa, 1986. / Bibliography: l. 104-116.
23

Parametric study of a single PDC cutter with a numerical model

Sunal, Ozge. January 2009 (has links)
Thesis (M.S.)--West Virginia University, 2009. / Title from document title page. Document formatted into pages; contains xv, 91 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 82-84).
24

The temperature factor in rotary drilling of Indiana limestone

Karfakis, Mario G. January 1983 (has links)
Thesis (Ph. D.)--University of Wisconsin--Madison, 1983. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 150-164).
25

[en] COMPRESSION OF NATURAL NUMBERS, SEQUENCE OF BITS AND GRAPHS / [pt] COMPRESSÃO DE NÚMEROS NATURAIS, SEQUÊNCIA DE BITS E GRAFOS

BRUNO TENORIO AVILA 01 June 2012 (has links)
[pt] Esta tese aborda os problemas de compressão para os seguintes tipos de dados: sequência de bits e grafos web. Para o problema de compressão de sequência de bits, demonstramos a relação entre algoritmos de intercalação e codificadores de fonte binária. Em seguida, mostramos que os algoritmos de intercalação binária (Hwang e Lin, 1972), recursivo (Dudzinski, 1981) e probabilístico (Vega, 1993), geram respectivamente os codificadores de entropia baseado em comprimentos de carreiras codificados com o código de Rice, o codificador de intercalação binária (Moffat, 2000) e o codificador de Rice aleatório, na qual é um novo variante do código de Rice. Para o problema de compressão de grafos web, propomos uma nova representa ção compacta para grafos web, intitulada árvore-w, construída especificamente para memória externa (disco), sendo a primeira nesse gênero. Propomos também um novo tipo de layout projetado especificamente para grafos web, intitulado layout escalado. Além disso, mostramos como construir um layout cache-oblivious para explorar a hierarquia de memórias, sendo a primeira desse tipo. Apresentamos vários tipos de consultas que podem ser executadas e é a primeira representação a suportar execução de consulta de leitura aleatória em lote e a otimização de consultas avançadas, inclusive em memória principal. Por fim, executamos uma série de experimentos que mostra que a árvore-w apresenta taxas de compressão e de tempo de execução competitivas com outras representações compactas em memória principal. Assim, demonstramos empiricamente a viabilidade de uma representação compacta para memória externa na prática, contrariando a afirmação de vários pesquisadores (Suel, 2001) (Buehrer, 2008). / [en] This thesis addresses the problems of compression for the following data types: numbers, sequence of bits and webgraphs. For the problem of compression of a sequence of bits, we demonstrate the relationship between merge algorithms and binary source coders. Then, we show that the algorithms binary merge (Hwang and Lin, 1972), recursive merge (Dudzinski, 1981) and probabilistic merge (Vega, 1993), generate respectively an entropy coder based runlengths encoded with the Rice code, the interpolative binary coder (Moffat, 2000) and the random Rice coder, which is a new variant of the Rice code. For the problem of webgraph compression, we propose a new compact representation for webgraphs, entitled w-tree, built specifically for external memory (disk), being the first one in this genre. We also propose a new type of layout designed specifically for webgraphs, entitled scaled layout. In addition, we show how to build a cache-oblivious layout to explore the hierarchy of memories, being the first of its kind. We offer several types of queries that can be performed and it is the first representation to support batched random read query execution and advanced query optimization, including in main memory. Finally, we performed a series of experiments showing that the w-tree provides compression rates and running times competitive with other compact representations for main memory. Therefore, we demonstrate empirically the feasibility of a compact representation for external memory in practice, contrary to the assertion of several researchers (Suel, 2001) (Buehrer, 2008).
26

Inspirational Bits : Förmedla teknik i en designmiljö / Inspirational Bits : Communicating Technology in a Design Community

Grufberg, Katja January 2010 (has links)
I alla designprocesser måste man ta hänsyn till ett mediums egenskaper. Detta är inget nytt inom design. Ändå förekommer det ofta inom människa --‐ dator interaction (HCI) och interaktiv systemdesign att teknikens egenskaper bara ses över som hastigast. Tekniken är ofta abstraherad, utan att tillräcklig uppmärksamhet ges till hur deras distinkta egenskaper öppnar upp för designmöjligheter. I den här rapporten beskrivs ett tillvägagångssätt som kallas Inspirational Bits för att bli mer bekant med designmaterialet inom HCI, det digitala materialet. Det är också ett sätt för att bli bättre på att förmedla kunskapen till alla gruppmedlemmar i ett interdisciplinärt designteam. Inspirational Bits skapas ”snabbt och smutsigt” men är fullt fungerande system i både hard--‐ och mjukvara, med målet att blotta en eller flera av de dynamiska egenskaperna hos digitala material. / In any design process, a medium’s properties need to be considered. This is nothing new in design. Still it is found that in Human--‐Computer Interaction (HCI) and interactive systems design the properties of a technology are often glossed over. That is, technologies are black--‐boxed without much thought given to how their distinctive properties open up design possibilities. This thesis describes an approach using Inspirational Bits to become more familiar with the design material in HCI, the digital material. It is also a way to become better able to share some of this knowledge with all members of an interdisciplinary design team. Inspirational Bits are quick and dirty but fully working systems in both hardware and software with the single aim of exposing one or several of the dynamic properties of some of the digital materials.
27

The effect of chemical additives on cutting forces and rate of wear of natural diamonds

Rao, Bokka Narasimha,1952- January 1978 (has links)
Call number: LD2668 .T4 1978 R37 / Master of Science
28

Facilitating enforcement of international investment dispute awards

Esra, Yildiz January 2017 (has links)
In the current investment climate, most investor-state disputes are settled through investment arbitration. Investor-state arbitration enables the foreign investor to bring a case before a neutral forum, whose decision is binding and enforceable in countries across the world. In instances where the dispute is governed by an arbitration clause, the clause places the disputing parties under the jurisdiction of an arbitral tribunal. In the event of achieving a victory, the investor may nonetheless come up against the obstacle of state sovereignty, even though the state party has ostensibly waived sovereign immunity from jurisdiction. If a state rejects to comply with an award, then investors must commence a worldwide search (forum-shopping), with a view to retrieving the assets that have been awarded. In instances where the state party is victorious, there is a danger that the award payment will not be made if the foreign investor has already declared bankruptcy. Although there are two Conventions (ICSID and the New York Convention) that facilitate the enforcement of arbitral awards, neither one is sufficient to preclude the emergence of the enforcement issue. In both instances, this issue is damaging as it wastes time and money, ultimately contributing to wider inefficiencies and uncertainties in investor-state arbitration. In addressing themselves to this problem and aspiring to the reduction of the obstacle of sovereign immunity from execution, scholars and practitioners have put forward two practical solutions; firstly, a hybrid sovereignty act has been proposed; secondly, it has been suggested that the World Bank could take punitive action, refusing to provide the state party with further loans until the award is resolved. However, these proposals have, to date, not been practically applied or developed. This thesis has two primary objectives: firstly, it attempts to analyse previous solutions that have been addressed to the enforcement issue of ICSID awards: secondly, it addresses itself to two alternatives: 1) that the ICSID Administrative council can review compliance with awards; 2) that countermeasures can be initiated against the failing state under the law of state responsibility (the ILC Articles on State Responsibility). In concluding, the thesis will consider the various advantages and disadvantages associated with each of the aforementioned solutions, ultimately proposing an approach that is best-suited to upholding the interest of the victorious party at the enforcement stage.
29

En studie av metodbyte vid sintring av hårdmetaller till mikrovågsintring samt dess ekonomiska fördelar : Självständigt arbete i teknisk fysik med materialvetenskap & Självständigt arbete i kemiteknik / A study of the change in methodology at the sintering of hard metals to microwavesintering and its economic benefits : Självständigt arbete i teknisk fysik med materialvetenskap & Självständigt arbete i kemiteknik

Vargas, Ernesto, Färnlund, Kim, Bäcklin, Annika, Karlsson, Karolin, Massoud, George, Renman, Viktor, Björklund, Erik January 2010 (has links)
<p>The aim with this study was to investigate the effects a change of manufacturing process would have on the mechanical properties of drill bits made of a WC/Co composite used for stone cutting. The method used today is sintering, where the material is heated in a conventional sintering oven. The other method was microwave sintering, where the material is heated by radiation in the microwave region. Also an investigation of the manufacturing cost were made.</p><p>The main difference between the two heating methods is that the conventional way is a rather slow process and the microwave method is very fast. The material is also heated homogeniously in the method with mirowaves, aposed to the case with the conventional sintering where the material is heated from the outside in.</p><p>This makes the material harder and more wear resistent. Another positive effect is that the pysical properties of the drill bits is easier to controll, because of the very small grain growth due to the short process time.The cost of manufacturing these drill bits by microwave sintering does not exceed the cost of the conventionall sintering.</p>
30

Drilling process evaluation by predicting drilled hole quality and drill bit wear with on-line acoustic emission signals

Wang, Kuang-Jen, 1962- 30 August 1996 (has links)
Improvement of manufacturing productivity is dependent on the successful automation of manufacturing processes, the success of which is based in turn upon the availability of information which describes the state of manufacturing operations. Acoustic Emission (AE) signals related to the cutting process and tool wear have been recently applied to monitor manufacturing processes, and various AE parameters can be used to provide process information. For example, when cutting tools become worn, AE energy generated at the interface of tool flank and work piece increases. This study is thus an experimental investigation of the AE spectrums representing AE signals energy distribution to determine the possibility of extracting useful parameters to provide on-line information about drilled-hole quality and drill-bit wear. An experiment conducted using a radial-arm drilling machine was employed to collect on-line AE drilling process spectrums, yielding eight indicator parameters. Drill wear states were measured using a machine vision system. Assessment of the drilled hole quality was based on tolerances established in Geometric Dimensioning and Tolerancing (GD&T). Correlations among drill wear, drilled-hole quality measurements, and the AE spectrum indicator parameters were examined by regression analysis. A forward-stepwise variable selection procedure was used to select the best-fit regression model for each drilled hole quality measurement associated with the set of one AE parameter raised to different powers. According to quality measurements, drilled holes were categorized as either "acceptable" or "unacceptable" holes, using cluster analysis with a group-averaging method. The usage of AE parameters to decide to which group a drilled hole belonged was also examined. From the experimental evidence, it was observed that there are strong relationships between AE parameters and drill-wear state and the quality measurements of drilled holes. AE parameters could be useful predictor variables to provide information to controller/operators to evaluate current drilling processes. Based on the status information of drill wear and the quality measurements, drilling processes can be adjusted accordingly. / Graduation date: 1997

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