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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

Study on the electrodeposition method for Ni-based composite layer coating SiC and Al2O3 particles

Tseng, Shih-hua 03 September 2010 (has links)
Abstract In the study, amounts of ceramic particles in coating layer deposited on the surface of cathode specimen are investigated under two kinds of ceramic particles of Al2O3 and SiC mixed in the Nickel sulfate bath during electroplating or electrophoretic depositing process. According to the IEP of the particles, Al2O3 particles which showed the positive charge in the nickel sulfate bath are deposited onto the work-piece of cathode during electrophoretic deposition (EPD)process. And the other hand, SiC particles which showed Neutral ( or zero ) charge in the same bath are deposited onto the work-piece of cathode during electrolytic deposition (ELD)process. Therefore, it is expect that the composite electro - deposition layers on the work-piece have large amount of particles and high strength are fabricated by using the method of ELD¡VEPD¡VELD in sequence (ELEPIS). In the experiment conditions, the bath mixing the SiC particle with average diameter of 3 £gm and the Al2O3 particle with average diameter of 1 £gm respectively is stirred using the air pump and the magnetic stirrer, concentration of 20 g/L for each particle is seted. EPD is carried out under the apply voltage of 30 V, and ELD is carried out under the current density of 3 ASD. Results show that the amount of Al2O3 particle deposited in the composite coating layer is about 29.25 wt% during EPD, and the amount of SiC particle deposited in the composite coating layer is large and its distribution is uniform during ELD. Moreover, ELEPIS is carried out in the bath mixing 4 g/L of SiC particle and 8 g/L of Al2O3 particle to fabricate the composite coating layer. Result shows that the hardness of composite coating layer is 527 Hv, which is two times of that using traditional ELD method. This indicates that the strength and wear resistance of Ni-SiC- Al2O3 composite coating layer fabricated by ELEPIS method is excellent. Keywords : EPD¡BELD¡BELEPIS
2

Investigations on the Content Increment Method of Dispersive Particles and Wear Characteristics for Composite Electrodepostion Layers

Chen, Ming-Jen 25 July 2005 (has links)
Generally speaking , high volumetric content of particles and well-dispersed condition in the metallic matrix are the purposes in composite electrodeposition for different applications. The composite electrodeposition layer by EPD has high volumetric content of particles but low structure strength. The composite electrodeposition layer by ELD has tight structure but low volumetric content of particles . In this study combines EPD and ELD to produce the composite electrodeposition layer in ELD-EPD-ELD three steps. We hope to combine their advantages .In this study ,we first look for the best operating condition of EPD, then increase the volumetric content of particles with ELD-EPD-ELD(ELEPIS). Finally, it was examined by scratch test to prove the structure strength. By the result of experiment, it can be known that at the voltage 10V,the concentration 100g/L,stirring speed 50rpm is the best operating condition. In the process of ELEPIS, we find that Ni ions permeate into the second layer. In this method, we can produce the electrodeposition layer which of the volumetric content of particles is 4 times the traditional electrodeposition layer. We also propose the possibility of multi-storey ELEPIS composite electrodeposition layer. Finally, by the result of scratch test , it can be known that there are the least cracks in the scratch which of the electrodeposition layer by ELEPIS. Its depth is shallowest and its width is narrowest. It shows that the sample by ELEPIS has excellent performance in structure strength and binding with substrate.
3

The investigation on improving the content of dispersive particles for composite electrodeposition layer

Chang, Chin-hao 29 July 2006 (has links)
Composite electro-deposition always requires high volume fraction of particles and good dispersion and high wear resistance.¡@Composite electro-deposition made by the electrophoretic deposition (EPD) contains high volume fraction of particles but low structural strength, and it made by electrolytic deposition (ELD) are right opposite. Therefore, this study tries to combine the advantages of both EPD and ELD in the sulfamate bath with the average particle size 1
4

LAGRANGIAN FORMULATION OF MOND; MOND FIELD IN PERTURBED SPHERICAL SYSTEMS

Matsuo, Reijiro 27 July 2010 (has links)
No description available.
5

Emergent Phenomena in Classical and Quantum Systems: Cellular Dynamics in <i>E. coli</i> and Spin-Polarization in Fermi Superfluids

Ellis, Jason Keith 02 November 2009 (has links)
No description available.
6

Generalized hybrid methods for modeling complex electromagnetic structures

Usner, Brian C. 06 January 2006 (has links)
No description available.
7

Granatkastare i fredens tjänst<em> </em><em> </em> : studie av faktorer som har påverkat funktionen indirekt eld vid internationella operationer

Johansson, Stina January 2009 (has links)
<p>Försvarsmakten deltar i allt större utsträckning i operationer utomlands. Hittills har dock inte artilleriförband deltagit men möjligheten att tungt understöd kan komma att behövas verkar inte minska. </p><p>Syftet med min forskning är att försöka belysa och ta tillvara de slutsatser som dragits av svenska förband inom funktionen indirekt eld vid internationella operationer. På detta vis hoppas jag kunna bidra till att begränsa de problem som hittills har funnits och ta tillvara vad som har fungerat bra. </p><p>Problemformuleringen lyder: <em>Vilka faktorer samt hur har dessa påverkat användandet av funktionen indirekt eld vid svenska internationella insatser?</em> </p><p>Jag har genomfört en fallstudie på det indirekta eldsystemets nyttjande i Kongo och Kosovo. För inhämtning av information har jag använt mig av tekniken enkätundersökning samt intervju.</p><p>Några av de viktigaste resultat jag erhållit är att personalen inom funktionen indirekt eld måste ha djup förståelse och en bred kunskapsbank inom artilleritjänsten för att kunna lösa problem som kan uppkomma vid internationell tjänst. Lika självklart är att de också måste kunna fungera som en skyttepluton. Allt är beroende inom vilken konfliktnivå artilleriet kommer att verka. Vidare har det utifrån resultatet även framkommit att för att få verka inom Rules of Engagement måste det fastställas vilka krav som gäller på de underrättelser som eldledningsgrupperna presenterar. Detta för att ge ett bra beslutsunderlag så att processen från upptäckt till verkan går snabbare.</p>
8

Granatkastare i fredens tjänst   : studie av faktorer som har påverkat funktionen indirekt eld vid internationella operationer

Johansson, Stina January 2009 (has links)
Försvarsmakten deltar i allt större utsträckning i operationer utomlands. Hittills har dock inte artilleriförband deltagit men möjligheten att tungt understöd kan komma att behövas verkar inte minska.  Syftet med min forskning är att försöka belysa och ta tillvara de slutsatser som dragits av svenska förband inom funktionen indirekt eld vid internationella operationer. På detta vis hoppas jag kunna bidra till att begränsa de problem som hittills har funnits och ta tillvara vad som har fungerat bra.  Problemformuleringen lyder: Vilka faktorer samt hur har dessa påverkat användandet av funktionen indirekt eld vid svenska internationella insatser?  Jag har genomfört en fallstudie på det indirekta eldsystemets nyttjande i Kongo och Kosovo. För inhämtning av information har jag använt mig av tekniken enkätundersökning samt intervju. Några av de viktigaste resultat jag erhållit är att personalen inom funktionen indirekt eld måste ha djup förståelse och en bred kunskapsbank inom artilleritjänsten för att kunna lösa problem som kan uppkomma vid internationell tjänst. Lika självklart är att de också måste kunna fungera som en skyttepluton. Allt är beroende inom vilken konfliktnivå artilleriet kommer att verka. Vidare har det utifrån resultatet även framkommit att för att få verka inom Rules of Engagement måste det fastställas vilka krav som gäller på de underrättelser som eldledningsgrupperna presenterar. Detta för att ge ett bra beslutsunderlag så att processen från upptäckt till verkan går snabbare.
9

INVERKAN AV UPPLÖSNING OCH RENDERINGS PRECISION PÅ VOLYMETRISK ELD I REALTID i realtids Spel : En balans mellan prestanda och utseende / IMPACT OF RESOLUTION AND RENDERING PRECISION OF REALTIME VOLUMETRIC FIRE in realtime GAMES : A balance between performance and appearance

Henriksson, Petter January 2014 (has links)
Detta arbete har undersökt hur mycket en volymetrisk eldeffekt med tillhörande fysiksimulering kan optimeras medan effekten samtidigt presterar tillfredställande. I bakgrunden ges en sammanfattning om eldteknikens historia. De begrepp som krävs för att förstå arbetet som helhet redogörs. I bakgrunden presenteras även den forskning som motiverar utförandet av arbetet. Bakgrunden följs av problemformuleringen med tillhörande metodbeskrivning. Problemformuleringen förklarar att optimering av en eldeffekt skall undersökas och då  eld är en mycket använd effekt. Metodbeskrivningen behandlar utförandet och förklarar att ett frågeformulär användes med en urvalsgrupp på 10 respondenter. I implementationen förklaras hur den utvecklade applikationen fungerar och vilka problem som påträffats under implementationen. Sedan följer utvärderingen som presenterar den data som samlats. Datan analyseras och intressanta slutsatser som antalet stickprov presenteras. I en avslutande diskussion presenteras vilken nytta samhället har av arbetet samt hur en fortsatt forskning kan se ut.
10

New Algorithms for Some Economic Dispatch Problems

Navin, S January 2016 (has links) (PDF)
An electric power system consists of several generating stations which cater to the load demands of various regions. The prime function of any generating utility is to optimally schedule the real power output of its generating units to meet any specified real power demand subject to various constraints on the operation of the units and the system. The optimal scheduling of individual generators at the least possible cost is referred to as the economic dispatch or economic load dispatch (ELD) problem. The ELD studies play a vital role in the day­to­day operation of the power system and in formulating economic operating strategies, besides ensuring the stability and security of the system. This thesis work makes an effort to probe deeper into some aspects of the economic load dispatch problem and the underlying mathematical formulations and attempts to come up with generalized algorithms that can effectively handle different types of systems under different operating conditions and, to a certain extent, to try and resolve some aspects hitherto unresolved. The primary focus is on developing efficient computational techniques to solve some Specific types of ELD problems in a simple and systematic manner. In the course of this investigation, we highlight some imperfect assumptions involved in the solutions proposed for the ELD problems for systems with complicated constraints like prohibited operating zones (POZ). We also set forth new concepts and strategies and develop new techniques in this investigation to help resolve some of these incorrect propositions and ambiguities. The first chapter introduces the ELD problem in general and proceeds to discuss the effects of the transmission losses and the presence of POZs on both the scheduling of the generators and the complexity of the ELD analysis. It also provides a brief review of some relevant aspects of the state-of-the-art solution techniques and clearly spells out the motivation for the present work. The second chapter presents a generalized algorithm for solving the ELD problem efficiently. The algorithm is effectively applicable to any system comprising power generating units with any type of well-defined, smooth and monotonic cost functions, besides quadratic cost functions usually considered in conventional algorithms. The proposed method first identifies the units that are forced to operate at their generating limits for any given value of the system demand. Subsequently, it limits the ELD problem to calculating The system's incremental cost of received power and the power output of only those units operating within their normal feasible range. The specific improvement introduced here is the development of an efficient computational scheme for calculating the value of the system incremental cost accurately. In addition to quadratic and higher order polynomial cost functions, the proposed algorithm can easily be generalized to include units with smooth, monotonic, non­ polynomial cost functions. The major advantages of the proposed ELD scheme are its inherent simplicity, scalability, rapid convergence and high computational efficiency. These characteristics are particularly important for real-time online implementation. The results obtained for test cases from the literature and some new ones as well are presented to illustrate the effectiveness of the proposed scheme. The third chapter proposes an algorithm for solving the ELD problem considering power losses in the transmission network. The losses are computed using the transmission loss­ formula A coefficients method suggested by Nanda and Bijwe as an alternative to the conventional B­loss coefficients approach popularized by Kirchmayer. The proposed ELD­with­ Losses scheme builds upon the ELD scheme developed in the second chapter for the lossless case. The specific contribution of the third chapter is the computational approximation suggested for the iterative procedure involving The Newton­Raphson (NR) method with the losses considered, while still retaining the elegant solution scheme developed in the earlier chapter. The results obtained using test cases from the literature are presented to demonstrate the precision and effectiveness of the proposed technique. The fourth chapter presents a novel algorithm for efficiently solving the ELD problem for systems having generators with prohibited operating zones. The proposed ELD­ POZ scheme partitions the no convex solution space into simpler convex intervals in which the ELD scheme developed in the second chapter can be applied directly. The improvisation lies in the optimal ordering­cum­sorting strategy adopted to systematically determine the output levels of the units constrained by POZs and to adjust the output power of the remaining units appropriately. The proposed scheme also recognizes and exactly computes the multiple, equivalent optimal solutions wherever applicable–– another significant contribution of this thesis work. It also seeks to clarify and set right some unintentionally imperfect propositions and assumptions currently prevalent in the literature regarding the formulation and analysis of the ELD problem considering POZs. The results generated for a number of systems using test cases from the literature along with some new ones are presented to clearly illustrate the validity as well as the Simplicity and superiority of the proposed scheme for different types of systems. The final chapter briefly recounts the work done in this thesis work. It also presents a summary of the significant results obtained using the schemes proposed in the earlier chapters, along with the conclusions drawn in support of the validity and superiority of the proposed algorithms. More areas for further investigation and some possible avenues for future applications of the proposed techniques are also indicated.

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