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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.
301

Výroba pantu / Manufacturing of a hinge

Moravec, Jiří January 2011 (has links)
The project presents design of technology production of the hinge made of metal sheet plate 11 321. The variant proposed solutions have been designed manufacturing cutting and bending technology in transfer combined die. These themes were elaborated in literatures studies. As a working machine was selected eccentric press LEN 40 C of Slovak producer TOMA INDUSTRIES s.r.o., Trnava, with a nominal force 400 kN. Functional parts are made of tool steel 19 436. In economic results was defined cost of one piece including manufacturers profit and the break-even point, which is coming after production of 151 966 pieces.
302

Technologie výroby kombinovaných řezných nástrojů / Technology of production combinated cutting tools

Rusz, Radek January 2012 (has links)
In the thesis is solved manufacturing technology of step drill from material of cemented carbide. At first is made review of existing shank cutting tool types, after that follows an analysis of cemented carbide tool material. In the next part of thesis is manufacturing technology of this tool, including review of grinding wheels, designed. Output of this work is procedure of program designing for manufacturing this tool in software Numroto. Next output is techno-economic evaluation of step hole manufacture with combined tool and comparison to conventional type of manufacture.
303

Energetický paroplynový zdroj na bázi spalování hutnických plynů / Gas steam cycle power plant using metelurgic gas

Kysel, Stanislav January 2012 (has links)
The main goal of my thesis is to carry out thermic calculations for adjusted conditions of electric and heat energy consumption. The power of the generator is 330 MW. In the proposal, you can find combustion trubines type GE 9171E. Steam-gas power plant is designed to combust metallurgical gases. Effort of the thesis focuses also on giving a new informations about trends in combinated production of electric and heat energy.
304

Thermo-economic optimization of a combined heat and power plant in Sweden : A case study at Lidköping power plant

Bergström, Jarl, Franzon, Conny January 2020 (has links)
Energy production in power plants comes with both high costs and turnover whereas variations in the production strategy—that is, which boilers, coolers, or generators that should be running—have big impact on the economic result. This is especially true for a combined heat and power (CHP) plant where the production of district heating and electricity is linked, thus allowing for a higher flexibility in the production strategy and potential of increasing the revenue. Previous research states that thermo-economic optimization can have a great impact on economic result of power plants, but every power plant is operating under a unique set of conditions depending on its location, operating market, load demand, construction, surrounding, and the like, and comparable studies on CHP plants in Sweden are very few. This study aims to fill this research gap by evaluating savings potential of a CHP plant in Lidköping, Sweden by utilizing thermo-economic optimization with the approach of combining actual historical data from the power plant with mass-flow equations and constraints to construct a mathematical MODEST model that is optimized by linear programming. The result demonstrates a clear theoretical potential to improve earnings and the conclusion that the studied CHP would benefit by implementing optimization procedures or software to schedule production. The result was also comparable to previous research but varied over time, which highlights how unique conditions may impact the result.
305

Kombinerade vapen : hur det kan förklara luftlandsättningar

Eriksson, Victor January 2020 (has links)
Combined arms is a central and integral part of how Sweden’s armed forces choose to operate on strategic, operative and tactical level. Despite this fact the manuals, regulations and doctrine which Sweden’s armed forces rely on does not allow for tracing the military theory behind the concept. Focusing on Sweden’s light air assault battalion, which only have lighter weapons, the question arise on how they are to achieve combined arms. The study’s aim was to get an answer if combined arms also are applicable to airborne and air assult operations. To tackle this question this study used Robert Leonhard’s theory of combined arms and asked the question of how it can explain success and failure in two historic cases, operation Mercur 1941 and operation Market Garden 1944. The analysis focused on the initial three days of each operation. The method used was a qualitative textanalysis of empirical descriptions of the events during the initial phases of the operations using indicators deducted from Robert Leonhard´s theory of combined arms. The result was that combined arms was used extensively in operation Mercur and by quite a large degree in operation Market Garden. What the analysis show is that despite the fact that it was used to quite an extent during operation Market Garden it was not sufficient to achieve success, however in operation Mercur it played a big role in achieving success. The analysis on the operations showed that other factors played a role such as veterancy, differences in equipment and tactics but also a difference in numbers.
306

Biomass and Natural Gas Hybrid Combined Cycles

Petrov, Miroslav January 2003 (has links)
Biomass is one of the main natural resources in Sweden.Increased utilisation of biomass for energy purposes incombined heat and power (CHP) plants can help the country meetits nuclear phase-out commitment. The present low-CO2 emissioncharacteristics of the Swedish electricity production system(governed by hydropower and nuclear power) can be retained onlyby expansion of biofuels in the CHP sector. Domestic Swedishbiomass resources are vast and renewable, but not infinite.They should be utilised as efficiently as possible in order tomeet the conditions for sustainability in the future.Application of efficient power generation cycles at low cost isessential for meeting this challenge. This applies also tomunicipal solid waste (MSW) incineration with energyextraction, which is to be preferred to landfilling. Modern gas turbines and internal combustion engines firedwith natural gas have comparatively low installation costs,good efficiency characteristics and show reliable performancein power applications. Environmental and source-of-supplyfactors place natural gas at a disadvantage as compared tobiofuels. However, from a rational perspective, the use ofnatural gas (being the least polluting fossil fuel) togetherwith biofuels contributes to a diverse and more secure resourcemix. The question then arises if both these fuels can beutilised more efficiently if they are employed at the samelocation, in one combined cycle unit. The work presented herein concentrates on the hybriddual-fuel combined cycle concept in cold-condensing and CHPmode, with a biofuel-fired bottoming steam cycle and naturalgas fired topping gas turbine or engine. Higher electricalefficiency attributable to both fuels is sought, while keepingthe impact on environment at a low level and incorporating onlyproven technology with standard components. The study attemptsto perform a generalized and systematic evaluation of thethermodynamic advantages of various hybrid configurations withthe help of computer simulations, comparing the efficiencyresults to clearly defined reference values. Results show that the electrical efficiency of hybridconfigurations rises with up to 3-5 %-points in cold-condensingmode (up to 3 %-points in CHP mode), compared to the sum of twosingle-fuel reference units at the relevant scales, dependingon type of arrangement and type of bottoming fuel. Electricalefficiency of utilisation of the bottoming fuel (biomass orMSW) within the overall hybrid configuration can increase withup to 8-10 %-points, if all benefits from the thermalintegration are assigned to the bottoming cycle and effects ofscale on the reference electrical efficiency are accounted for.All fully-fired (windbox) configurations show advantages of upto 4 %-points in total efficiency in CHP mode with districtheating output, when flue gas condensation is applied. Theadvantages of parallel-powered configurations in terms of totalefficiency in CHP mode are only marginal. Emissions offossil-based CO2 can be reduced with 20 to 40 kg CO2/MWhel incold-condensing mode and with 5-8 kg CO2 per MWh total outputin CHP mode at the optimum performance points. Keywords: Biomass, Municipal Solid Waste (MSW), Natural Gas,Simulation, Hybrid, Combined Cycle, Gas Turbine, InternalCombustion Engine, Utilization, Electrical Efficiency, TotalEfficiency, CHP. / NR 20140805
307

Techno-economic Analysis of Combined Hybrid Concentrating Solar and Photovoltaic Power Plants: a case study for optimizing solar energy integration into the South African electricity grid

Castillo Ochoa, Luis Ramon January 2014 (has links)
The cooperation between large scale Concentrated Solar Power plants (CSP) and Solar Photovoltaic (PV) parks can offer stability in power supply and enhance the capacity factor of the CSP plant intended to cover a common demand on the power system. Moreover, it can offer an investment option with lower risk. This Master thesis project presents optimum plant configurations for both technologies under the same meteorological and market conditions. The study is based in the South African electricity market and the Renewable Energy Independent Power Producer Program currently in place in the country. Using MATLAB and TRNSYS softwares, a series of detailed codes were designed in order to model both technologies energy transformation process. The main approach was to design the nominal operation point of both technologies for a given typical meteorological year data and respective technical conditions for each case. Then, a transient simulation was done in order to obtain the electricity yield. The intention was to measure the internal rate of return, levelized cost of electricity and capacity factor for each technology and the combined configuration (CSP-PV plant) under different scenarios and operation modes while a firm capacity was maintained. It was found that the plants can be economically feasible by sizing a storage unit capable of just covering the peak hours. The solar multiple sizes can vary depending on the scenario and plant configuration. Moreover, the internal rate of return increases with the capacity of the CSP in all cases. After the results were obtained, a comparison with a single CSP plant and the optimum CSP-PV plant was done in order to evaluate the performance of the proposed cooperation. Even though the internal rate of return of the CSP-PV plant was found to be within a good range for investment, the CSP-alone alternative offered always higher internal rate of return and lower levelized cost of electricity values. Nonetheless, it was found that the capacity factor of the combined configuration was favored by the integration of PV. The PV alone configuration hold the lowest levelized cost of electricity, thus considered the best option for and investment in South Africa due to its independence towards incentives. Combined PV-CSP systems were also found to be an attractive investment under the South African scheme if the CSP capacity is similar to the PV power plant.
308

Teoriprövande fallstudie av Robert Leonhards teori om kombinerade vapen vid amfibieoperationer

Nöjdh, Patrik January 2019 (has links)
No description available.
309

Microphysical aerosol properties retrieved from combined lidar and sun photometer measurements

Wagner, Janet 06 January 2012 (has links)
To assess information about the optical, microphysical, and radiative properties of aerosol particles the lidar technique and sun photometers are commonly used. Information that result from both lidar and sun photometer data can provide a distinct image of the vertical aerosol properties. The algorithm developed at the Institute of Physics of the National Academy of Science of Belarus (IPNASB) uses lidar measurements at the three wavelengths 355, 532, and 1064 nm and mean backscatter and extinction coefficients retrieved from radiometric data to obtain profiles of fine-mode and coarse-mode concentrations. Within the master thesis the IPNASB algorithm was tested for specific aerosol situations. Three cases are considered representing Saharan dust, smoke and industrial aerosol from East Europe, and volcanic aerosol from the Eyjafjallajokull eruption. The retrieved microphysical aerosol properties are in good to acceptable agreement with findings of well-established methods.
310

Clean coal technology using process integration : a focus on the IGCC

Madzivhandila, Vhutshilo A. 20 October 2011 (has links)
The integrated gasification combined cycle (IGCC) is the most environmentally friendly coal-fired power generation technology that offers near zero green house gas emissions. This technology has higher thermal efficiency compared to conventional coal-fired power generation plants and uses up to 50% less water. This work involves the optimization of IGCC power plants by applying process integration techniques to maximize the use of energy available within the plant. The basis of this project was the theoretical investigations which showed that optimally designed and operated IGCC plants can achieve overall thermal efficiencies in the regions of 60%. None of the current operating IGCC plants approach this overall thermal efficiency, with the largest capacity plant attaining 47%. A common characteristic in most of these IGCC plants is that an appreciable amount of energy available within the system is lost to the environment through cold utility, and through plant irreversibility to a smaller extent. This work focuses on the recovery of energy, that is traditionally lost as cold utility, through application of proven process integration techniques. The methodology developed comprises of two primary energy optimization techniques, i.e. pinch analysis and the contact economizer system. The idea behind using pinch analysis was to target for the maximum steam flowrate, which will in turn improve the power output of the steam turbine. An increase in the steam turbine power output should result in an increase in the overall thermal efficiency of the plant. The contact economizer system is responsible for the recovery of low potential heat from the gas turbine exhaust en route to the stack to heat up the boiler feed water (BFW). It was proven in this work that a higher BFW enthalpy results in a higher overall efficiency of the plant. A case study on the Elcogas plant illustrated that the developed method is capable of increasing the gross efficiency from 47% to 55%. This increase in efficiency, however, comes at an expense of increased heat exchange area required to exchange the extra heat that was not utilized in the preliminary design. / Dissertation (MEng)--University of Pretoria, 2011. / Chemical Engineering / unrestricted

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