This thesis aims to examine the performance of Stockbridge dampers used to suppress aeolian vibrations on overhead transmission lines arising from the wind. In this respect, a computer program, based on the Energy Balance Method, is developed using MATLAB. The developed computer program has also a graphical user interface (GUI), which allows the program to interactively simulate Stockbridge damper performance for vibration control of overhead transmission lines. Field tests results obtained from literature are used in various case studies in order to validate and evaluate the developed software. Moreover, sample Stockbridge damper characterization tests, which then could be introduced to the software, are performed. A custom test fixture is designed due to its unavailability of commercial alternatives in the market. In the design of the test fixture, modal and transmissibility analyses are done by using ANSYS Workbench. To further validate the test setup, transmissibility test is done and consistent results with the transmissibility analyses are observed in the range of expected aeolian vibration frequencies. Finally, the stepped-sine and swept-sine tests are performed with and without damper for the characterization test, where the latter one is performed to eliminate the negative effects of the test setup. Both tests yield almost same damper power dissipation curves.

På uppdrag från Umeå Energi AB ska två av deras rostereldade värmepannor (panna 6 och 7) undersökas med avseende på pannverkningsgraden. Umeå Energi genomför i dagsläget månadsvisa kontroller av pannverkningsgraden beräknade med den direkta metoden. Denna beräkningsmetod är dessvärre ganska otillförlitlig, vilket medför att en noggrannare undersökning av pannverkningsgraden krävs. Av denna anledning så beräknades pannverkningsgraden med den indirekta beräkningsmetoden, vilket resulterade i ett mer tillförlitligt resultat där även pannans förlustfaktorer bestämdes. Pannverkningsgraden beräknades och analyserades med hänsyn till de ingående förlustfaktorerna vid samma nyttiga effekt för båda pannorna. För att genomföra detta arbete så undersöktes först de rådande standarderna inom området, detta för att välja ut den mest lämpliga standarden för detta arbete beträffande kriterier och viktiga beräkningsfaktorer. De viktigaste provtagningarna och analyserna som dessa standarder berörde gällde bränsle, aska och rökgaser. För att genomföra alla provtagningar skapades ett provtagningsschema. Provtagningarna genomfördes på båda pannorna vid två olika provtagningstillfällen, därefter skickades proverna på analys och pannverkningsgraden kunde sedan beräknas.Resultatet som detta arbete resulterade i är att panna 6 har något högre pannverkningsgrad än panna 7, 89,3 respektive 82,8 %. Detta medför att förlustfaktorerna står för 10,7 samt 17,2 % för panna 6 respektive panna 7, där den överlägset största förlustfaktorn är rökgasförlusterna. Denna förlustfaktor beror till stor del på rökgasernas temperatur och fukthalt. Rökgasförlusterna uppgår till 9,5 samt 16,3 % på panna 6 respektive panna 7. Därefter i storleksordningen kommer askförlusterna för panna 6 (0,8 %) och värmeförlusterna för panna 7 (0,5 %). Både värmeförlusterna och askförlusterna för panna 6 respektive panna 7 uppgår till en förlustfaktor på 0,3 %. Den minsta förlustfaktorn är oförbränt i gasfas (CO) som ligger mellan 0–0,1 % för panna 6 och panna 7, detta tyder på låga halter av kolmonoxid och oförbränt i rökgaserna.De effektiviseringsförslag som detta arbete ledde fram till var att minska fukthalten och temperaturen på de utgående rökgaserna, detta genom att installera en rökgaskondenseringsanläggning som sänker rökgastemperaturen ytterligare och kondenserar ut mer fukt från rökgaserna. Detta realiseras genom att sänka kondensattemperaturen i rökgaskondenseringsanläggningen antingen genom lägre returledningstemperatur på fjärrvärmen som värmeväxlas mot kondensatet eller via en värmepump placerad mellan fjärrvärmereturen och kondensatet som arbetar med en lägre drifttemperatur än fjärrvärmen. Ett annat effektiviseringsförslag är att förbättra bränslehanteringen genom att torka bränslet innan de matas in i pannan. Slutligen skulle också en mer frekvent uppföljning av bränsleparametrar såsom värmevärde vara ett möjligt effektiviseringsförslag. Alla dessa förslag kräver dessvärre en ekonomisk och tekniskt utredning för att avgöra om dessa effektiviseringsförslag är ekonomiskt försvarbara samt tekniskt genomförbara. / On behalf of Umeå Energi AB, two of their grate fired heating boilers (boiler 6 and 7) was evaluated with respect to boiler efficiency. Currently these boiler efficiency calculations is carried out monthly by the input-output method. This calculation method is unfortunately rather unreliable, which means that a more exact examination of the boiler efficiency is required. For this reason, the boiler efficiency was calculated using the energy balance method, which gives more reliable results and also evaluates the boiler losses. Boiler efficiency was calculated and analysed with respect to the boiler losses at approximately the same useful effect for both the boilers.To perform this work the leading standards in the field were examined, which was done in order to evaluate the most appropriate standard with regard to criteria and important calculation factors. The most important samples and analyses that these standards was concerned with was fuel, ash and flue gas. To conduct all sampling, a sampling plan was created. All samplings was performed on both boilers at two sampling occasions, the samples were then sent for analysis and the boiler efficiency could then be calculated.The result from this work shows that boiler 6 has slightly higher boiler efficiency than boiler 7, 89.3 and 82.8% respectively. As a result, the boiler losses total up to 10.7 and 17.2% for boiler 6 and 7 respectively, where the flue gas losses constitutes the largest losses. The flue gas losses depends largely on the temperature of the flue gases and the moisture content. Flue gas losses sums up to 9.5 and 16.3% on boiler 6 and 7 respectively. The second largest boiler loss is ash losses on boiler 6 which sums up to 0.8% and heat losses on boiler 7 which sums up to 0.5%. The heat losses on boiler 6 and the ash losses on boiler 7 both sums up to a boiler loss of 0.3 %. The smallest loss factor is unburned in gas phase (CO) and is between 0–0.1% for boiler 6 and boiler 7, this suggests low levels of carbon monoxide and unburned in flue gases.The efficiency proposals this work resulted in was to reduce the moisture content and temperature of the outgoing flue gases, this by installing a flue gas condenser, which lowers the temperature further and condenses out more moisture from the flue gases. This is realized by reducing the flue gas condensate temperature either through lowering district heating return temperature which exchange heat with the flue gas condensate or through a heat pump that is placed between the district heating return and flue gas condensate which operates at a lower temperature than the district heating. Another efficiency proposals is to improve the fuel handling by drying the fuel before being fed into the furnace. Finally, also a more frequent follow up of the fuel parameters such as calorific value would be a possible efficiency proposal. All of these proposals require unfortunately economic and technical investigation to determine whether these efficiency proposals are economically viable and technically feasible.

In this dissertation, certain problems of stochastic optimal control and relevant analysis of random vibrations are considered. Dynamic Programming approach is used to find an optimal control law for a linear single-degree-of-freedom system subjected to Gaussian white-noise excitation. To minimize a system's mean response energy, a bounded in magnitude control force is applied. This approach reduces the problem of finding the optimal control law to a problem of finding a solution to the Hamilton-Jacobi-Bellman (HJB) partial differential equation. A solution to this partial differential equation (PDE) is obtained by developed 'hybrid' solution method. The application of bounded in magnitude control law will always introduce a certain type of nonlinearity into the system's stochastic equation of motion. These systems may be analyzed by the Energy Balance method, which introduced and developed in this dissertation. Comparison of analytical results obtained by the Energy Balance method and by stochastic averaging method with numerical results is provided. The comparison of results indicates that the Energy Balance method is more accurate than the well-known stochastic averaging method.

Following diploma thesis deals with waste-based renewable energy production. Waste is a very heterogeneous mixture consisting of various materials with different origin. This can be either fossil or biogenic. The very substances with biogenic origin are considered renewable energy source with financial support from state. Therefore is nowadays tendency to develop a method, which can determine the biogenic waste ratio. The method, aside possible cheapest price and simplicity, should be also reliable and easy reproducible due to its usage. At the beginning, thesis focuses on the waste-to-energy facilities. Important part deals with legislative side of this topic. The reasons, why Czech Republic is behind with thermal waste treating are stated as well as Czech Republic’s obligations to European Union in the field of biodegradable municipal solid waste. Main part of thesis deals with different methods to determine biogenic waste ratio in municipal solid waste. Step by step are introduces 4 known methods, where especially sorting, balance and 14C methods are described closely. By each method are stated its major benefits and handicaps in case of using. Finally, the computational model, which is based upon balance methods equations, is introduced following with feasibility study of balance method for local conditions. The very end of the thesis brings comparison of each method results, general summary, where are results of this thesis stated and possible trends for future in this area of expertise, as well.