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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.
41

Analysis And Control Of Gun Barrel Vibrations

Buyukcivelek, Firat 01 December 2011 (has links) (PDF)
Modern battle tanks are equipped with gun stabilization systems using gyro and encoder data to stabilize the gun barrel, although these systems are very sensitive and reliable, these systems assume the gun barrel as a rigid beam, and do not use information from
42

Pirmosios Lietuvos Respublikos Gaižiūnų poligonas 1930-1939 metais / Gaižiūnai firing range of the first army of the Republic of Lithuania in 1930–1939

Kasparaitė, Lina 25 June 2012 (has links)
XX a. 3-iajame dešimtmetyje Lietuvos kariuomenės kovinio rengimo įgyvendinimui buvo naudojamas Varėnos poligonas, kurio buvo atsisakyta 1931 m. įsteigus Gaižiūnų poligoną. Pastarasis poligonas buvo įkurtas Vyriausiojo štabo viršininko gen. št. plk. P. Kubiliūno ir kariuomenės inspektoriaus plk. O. Urbono pastangomis. Netoli nuo Jonavos miesto steigiamam poligonui reikalingi žemės plotai buvo išperkami iš privačių savininkų pagal specialiai tam parengtus įstatymus, kurių įgyvendinimas buvo vykdomas per visą poligono funkcionavimo laikotarpį. Įkūrus Gaižiūnų poligoną buvo suformuota administracinė įstaiga – poligono komendantūra, užtikrinusi karinės teritorijos tinkamą funkcionavimą ir priežiūrą. Karinių pratybų laikotarpiu, kuris buvo skiriamas gegužės – rugsėjo mėnesiais, poligone veikė jo vadovybė ir štabas, atlikę organizacines pratybų funkcijas. Gaižiūnų poligono įrengimo darbai buvo orientuoti į teritorijos parengimą vadovaujančio personalo darbui ir karių gyvenimo sąlygų sudarymą bei pritaikymą karinių pratybų vykdymui. Atsižvelgiant į tai, poligono teritorijoje buvo atliekami medžių kirtimo ir žemės drenavimo darbai, susisiekimo infrastruktūros sutvarkymas, buvusių pastatų remontas bei naujų įvairios paskirties pastatų statyba buvo įrenginėjamos šaudyklos. Šie poligono įrengimo darbai buvo atliekami per visą Gaižiūnų poligono funkcionavimo laikotarpį, t. y. iki 1939 m. spalio 31 d., kuomet patvirtinus poligono perleidimą Sovietų Sąjungos kariams, buvo nurodyta poligono... [toliau žr. visą tekstą] / “Gaižiūnai firing range of the first army of the Republic of Lithuania in 1930–1939” Varėna firing range was used to realization of combat training of Lithuanian army in the 3rd decade of XX century. It was refused in 1939 when Gaižiūnai firing range was established. It was founded by chief of staff general colonel P. Kubiliūnas and army inspector colonel O. Urbonas. The necessary territories for near Jonava city founded range were redeemed from private owners by special prepared law implementation of which was filled during whole period of working of firing range. Founding the Gaižiūnai firing range an administrative office – commandant headquarter of firing range vouchsafed the right working and supervision of military territory. In period of military exercises which was named in May – September, command and staff operated in range which performed functions of organizational exercises. Installation work of Gaižiūnai firing range was oriented to preparation of territory for work of managing staff, making of living conditions of soldiers and fitting of military exercises. In this context deforestation, land drainage works, transaction of transport infrastructure, repair of previous buildings and construction of new buildings of various purposes and shooting-ranges were made in the territory of range. The installation work was made during whole period of working of Gaižiūnai range until the 31st of October 1939, when transfer of range to Soviet soldiers was confirmed, it was... [to full text]
43

搬硬幣遊戲與離散型熱帶因子等價關係 / The Chip-Firing Game and Equivalence of Discrete Tropical Divisors

王珮紋, Wang, Pei Wen Unknown Date (has links)
在這篇論文裡,我們研究Baker-Norine的搬硬幣遊戲,並且把這個遊戲應用在離散型的熱帶因子上。特別地,我們去探討這個遊戲與等價熱帶因子之間的關係。最後我們證明了下面的定理:若$D, E$為熱帶曲線$\Gamma$上的離散型熱帶因子, 而$\overline{D}$, $\overline{E}$分別代表因子$D,E$在搬硬幣遊戲時的狀態,因子$D$與$E$等價,若且為若 $\overline{D}$可經搬硬幣遊戲變成$\overline{E}$。 / In this thesis, we study Baker-Norine's chip-firing game, and apply it to discrete tropical divisors. In particularly, we discuss the relationship between this game and the equivalence of divisors. Finally, we give a proof of the theorem: Let $D$ and $E$ be discrete tropical divisors of tropical curve $\Gamma$, and let $\overline{D}$ and $\overline{E}$ be corresponding configurations of the chip-firing game. The divisors $D$ and $E$ are equivalent if and only if $\overline{D}$ can be transformed into $\overline{E}$.
44

Biophysics underlying bistable neurons with branching dendrites

Kim, Hojeong Unknown Date
No description available.
45

Life Cycle Assessment of Biomass Conversion Pathways

Kabir, Md R Unknown Date
No description available.
46

Volumetric combustion of torrefied biomass for large percentage biomass co-firing up to 100% fuel switch

Li, Jun January 2014 (has links)
The co-firing of biomass and coal plays an important role in increasing the biomass power capacity and reducing greenhouse gas (GHG) emissions. The challenges of the large percentage biomass co-firing (over 20% on energy basis) in existing pulverized coal boilers are keeping the same steam parameters and having a high boiler efficiency and a stable operating. The primary goal of this thesis is to develop a combustion concept for coal-fired boilers to enablea large percentage of biomass co-firing with up to a 100% fuel switch; these changes should increase the combustion efficiency, reduce CO2  and NOx emissions, improve the process efficiency, while maintaining the same steam parameters after switching fuels. To achieve these goals,  a  typical  biomass  pretreatment technology  called  torrefaction  has  been  employed to upgrade  the  biofuel  quality  in  terms  of  both  energy  density  and  chemical  properties. Consequently, a torrefaction based co-firing system has been proposed. In addition, a novel biomass combustion method called volumetric combustion has been designed; this process involves intense mixing and flue gas internal recirculation inside the combustion chamber, increasing the residence time of the biomass particles and making the temperature and gas species more uniform. In this thesis, a series of studies based on experiments, CFD modelling, and process simulations have been performed. First, the raw material was palm kernel shells (PKS) that were torrefied over same residence time but at different temperatures in a laboratory-scale torrefaction reactor, producing three torrefied biomasses with different degrees of torrefaction. The devolatilization kinetics and char oxidation kinetics were determined based a series of high-temperature high-heating-rate tests in an isothermal plug flow reactor (IPFR), the obtained kinetic parameters were adopted for CFD modeling. Continually, the numerical investigations on the flame properties of the torrefied biomass and a 220 MWe coal-fired boiler performance were conducted, to understand the predicted results of the coal-fired boiler performance at varying biomass co-firing ratios. Afterward, analyses of the impacts of the degree of torrefaction and the biomass co-firing ratio on process operation, performance and electricity efficiency of a torrefaction based co-firing power plant were performed. Finally, the properties of the pollutants emitted from biomass volumetric combustions under various combustion modes and co-firing ratios were studied using Aspen Plus. According to the results, the following conclusions can be reached: 1) a high heating rate enhances the yields of the volatiles for biomass devolatilization processes with the same final temperature; 2) the enhanced drag force on the biomass particles causes a late release of volatile matter and delays the ignition of the fuel-air mixture. Furthermore, oxidizers with lower oxygen concentrations normally generate larger flame volumes, lower peak flame temperatures and lower NO emission; 3) the co-firing simulation reveals that a boiler load reduction of less than 10% is observed when firing 100% torrefied biomass; 4) deep torrefaction is not recommended because the energy saved during biomass grinding is lower than that consumed by the additional torrefaction process; the electrical efficiency of power plant is reduced when increasing either the degree of torrefaction or the biomass substitution ratio; 5) the amount of flue gas that needs to be recycled for NOx reduction decreased when the percentage of co-fired biomass increased. Overall, from the perspective of combustion, both the torrefaction process and volumetric combustion are promising steps toward realizing large percentage biomass co-firing in coal-fired boilers with high efficiency and reduced emissions. / <p>QC 20140130</p>
47

Performance Of Combined Cycle Power Plants With External Combustion

Dogan, Osman Tufan 01 January 2003 (has links) (PDF)
No description available.
48

Archaeometrical Investigation Of Mud Plasters On Hittite Buildings In Sapinuwa-corum

Guducu, Gulnur 01 January 2004 (has links) (PDF)
The study aimed to identify mud brick and mud plaster technology of Hittites by examining some burnt mud brick walls of Shapinuwa Hittite city and to point out repair and conservation needs of those burnt mud brick structures. The walls were documented by mapping the visual decay forms. The bulk density, total porosity, water absorption by capillarity and water vapour permeability were obtained as basic physical properties. The mechanical properties were expressed by the modulus of elasticity and the uniaxial compressive strength. Compositional and mineralogical properties were determined by optical microscopy, XRD, TGA and SEM coupled with EDX, and by XRF analyses. In addition, pozzolanic activity of powdered samples was determined.. The samples studied had low bulk density, high porosity and high water vapour permeability. The Emod values and the UCS values showed that their mechanical properties were comparable with some historic mortars and bricks. The petrographic and mineralogical analyses of burnt materials indicated a mud brick composition containing fine and medium sized siliceous aggregates mainly composed of quartz. The binder was concluded to be composed of kaolinite illite and micritic calcite that indicated the use of ideal soil compositions by Hittites to make lime stabilized mud bricks, in terms of today standards. The temperature during the fire was estimated to be around 700-800 C. The high pozzolanicity of burnt mud bricks and plasters, provided an opportunity to repair the structure using pozzolanic lime mortars to produce good adhesion. The first results of consolidation treatments had shown that the physical and mechanical properties of burnt mud brick can be improved by impregnation with ethylsilicates such as Tegovakon V.
49

Biophysics underlying bistable neurons with branching dendrites

Kim, Hojeong 06 1900 (has links)
The goal of this thesis is to investigate the biophysical basis underlying the nonlinear relationship between firing response and current stimulation in single motor neurons. After reviewing the relevant motoneuron physiology and theories that describe complex dendritic signaling properties, I hypothesize that at least five passive electrical properties must be considered to better understand the physiological input-output properties of motor neurons in vivo: input resistance, system time constant, and three signal propagation properties between the soma and dendrites that depend on the signal direction (i.e. soma to dendrites or vice versa) and type (i.e. direct (DC) or alternating (AC) current). To test my hypothesis, I begin with characterizing the signal propagation of the dendrites, by directly measuring voltage attenuations along the path of dendrites of the type-identified anatomical neuron models. Based on this characterization of dendritic signaling, I develop the novel realistic reduced modeling approach by which the complex geometry and passive electrical properties of anatomically reconstructed dendrites can be analytically mapped into simple two-compartment modeling domain without any restrictive assumptions. Combining mathematical analysis and computer simulations of my new reduced model, I show how individual biophysical properties (system input resistance, time constant and dendritic signaling) contribute to the local excitability of the dendrites, which plays an essential role in activating the plateau generating membrane mechanisms and subsequent nonlinear input-output relations in a single neuron. The biophysical theories and computer simulations in this thesis are primarily applied to motor neurons that compose the motor neuron pool for control of movement. However, the general features of the new reduced neuron modeling approach and important insights into neuronal computations are not limited to this area. My findings can be extended to other areas including artificial neural networks consisting of single compartment processors. / Medical Sciences – Biomedical Engineering
50

Effect of veneering technique, heat rate, holding time and zirconia thickness on the mechanical properties of porcelain veneers

Alwthinani, Fahad K. 28 September 2016 (has links)
OBJECTIVES: Evaluate the effect of different veneering techniques, Y-TZP core thicknesses, and firing cycles with different heat rates and holding times on the mechanical properties of veneering porcelain. MATERIALS AND METHODS: Biaxial flexural strength and Thermal shock resistance tests were conducted to evaluate the mechanical properties of veneer porcelain. Core material, Y-TZP and two porcelain veneers, IPS e.max Ceram and VITA VM9, were used in this study. Vita YZ zirconia blocks were sectioned and sintered to provide slabs of 1.65, 3.25, and 6.50mm in thickness. Two techniques were used to fabricate VITA VM9 and e.max Ceram porcelain veneer porcelain discs, Hand Layered, mixing powder with manufacturer’s molding liquid, condensed in a mold, and Pressed, pressing powder uniaxially in a mold. A layer of carbon paint was applied to the zirconia to allow removal of the porcelain discs. For thermal shock test the veneering porcelain fired on the Y-TZP core with a wash layer. After the veneer discs were fabricated, they were sintered: (1) According to the manufacturer’s instructions; (2) Two different cycles with slower heat rate and longer holding than the recommended value. Biaxial flexural strength was determined using a universal mechanical tester. Thermal shock tests were performed using a Pober thermal shock device. Statistical analysis was conducted for all tests using ANOVA and Tukey post hoc test at p= 0.05. RESULTS: There was significant effect from changes of YZ Core thickness, firing cycle, and veneer technique on the mechanical properties of porcelain veneer. The veneering technique had the largest impact on the mechanical properties of veneer porcelain followed by firing cycle, followed by YZ core thickness. In using different firing cycles with different heat rates and holding times, slowing the heating rate had more influence on the mechanical properties of veneer porcelain. In measuring the surface temperature of the Y-TZP/VITA VM9 assembly, the specimen surface temperature was coincidental with the furnace programmed firing cycle using a slower heating rate firing cycle. CONCLUSIONS Veneering technique, slower heat rate firing cycle, and Y-TZP core thickness have significant impact on veneering porcelain mechanical properties. / 2018-09-28T00:00:00Z

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