This thesis presents a timing error detector (TED) used in the symbol timing synchronization subsystem for digital communications. The new timing error detector is designed to minimize the probability of symbol decision error, and it is called minimum symbol error rate TED (MSERTED). The new TED resembles the TED derived using the maximum likelihood (ML) criterion but gives rise to faster convergence relative to MLTED. The new TED requires shorter training sequences for symbol timing recovery. The TED operates on the outputs of the matched filter and estimates the timing offset. The S-curve is used as a tool for analyzing the behavior of the TEDs. The faster convergence of the new TED is shown in simulation results as compared to MLTED. The new TED works well for any two-dimensional constellation with arbitrarily shaped decision regions.

Sedan implementeringen av on-load release funktionen på samtliga livbåtskrokar har det skett många olyckor som följd av introduktionen med detta system. Detta problem diskuterades under Internationella Maritima Organisationens Maritime Safety Committee, 89:e sammanträde 2011. Under detta sammanträde utvecklades ändringar och tillägg till koden för International Life-Saving Appliances med syfte att bemöta detta problem. Fokus för denna studien är resolution MSC.320(89) vilket formulerades under det sistnämnda mötet. Resolutionen lade fram nya krav rörande on-load release livbåtskrokar. Syftet med denna studie är att förstå hur MSC.320(89) har påverkat säkerheten vid hantering av livbåtar. Studien har utförts genom en kvalitativ litteraturstudie med komplementerande intervju. Genom att jämföra orsakande faktorer vid livbåtsolyckor med det nya kraven så har man kunnat spekulera fram positiva effekter gällande säkerheten. Implementeringsprocessen består av godkännande för utformning och funktion, rigorösa tester iland, samt granskningskrav för samtliga ombordvarande system. Minskning i antalet rapporter om olyckor vilket sker till följd av on-load release krokar efter implementeringsprocessen av MSC.320(89) tyder på att det sker ett färre antal olyckor relaterade till on-load release system. Denna minskning kan möjligtvis påverkas av implementeringen med fallprevention devices vilket kan ha som effekt att maskera svikt av on-load release system. Det övergripande resultatet från studien tyder på att MSC.320(89) har haft en positiv inverkan vad gäller säkerheten vid hantering av livbåtar. / There have occured many accidents as a result of the mandatory implementation of on-load release mechanisms on all lifeboats. In order to combat the problem amendments to the International Convention for the Safety of Life at Sea and the International Life-Saving Appliances Code were put forth during the Maritime Safety Committee, 89th session, 2011. The focus of this study lies on a product of this meeting: resolution MSC.320(89). The resolution presents new requirements for the design and function of on-load release systems. The purpose of this study is to understand how MSC.320(89) has influenced safety concerning the handling of lifeboats. A qualitative literature study with a complementary interview was used to conduct this study. By comparing causal factors of accidents involving on-load release systems with the new requirements stated in MSC.320(89) speculations could be made pertaining to improved safety conditions. The implementation process for the new requirements included a design review and performance test of existing and new on-load release and recovery systems. Moreover all systems onboard merchant vessels were either inspected, modified or replaced in order to be made compliant with the amended Life-Saving Appliance code. A decline in the number of accident reports concerning on-load release systems following implementation was observed during the data collection phase of this study. This decline may imply a reduction in the number of accidents caused by on-load release systems however the use of fall-prevention devices may have stopped failing on-load release systems from ending in catastrophe. The overriding conclusion of this study infers that resolution MSC.320(89) has effected safety concerning the handling of lifeboats in a positive manner.

In this study, a novel counter-cross-flow run-around membrane energy exchanger (RAMEE) system was designed and tested in the laboratory. The RAMEE system consists of two (2) counter-cross-flow Liquid-to-Air Membrane Energy Exchangers (LAMEEs) to be located in the supply and exhaust air streams in the building Heating Ventilation and Air-Conditioning (HVAC) system. Inside each exchanger, a micro-porous membrane separates the air and liquid streams and allows transfer of the sensible and latent energy from the air stream to the liquid stream or vice-versa. The system exchanges sensible and latent energy between supply and exhaust air streams using a desiccant solution loop. The supply and exhaust air streams in the RAMEE can be located far apart from each other or adjacent to each other. The flexibility of non-adjacent ducting makes the RAMEE system a better alternative compared to available energy recovery systems for the retrofit of HVAC systems.<p> Two counter-cross-flow exchangers for the RAMEE system were designed based on an industry recommended standard which is to obtain a target overall system effectiveness of 65% for the RAMEE system at a face velocity of 2 m/s. The exchanger design was based on heat exchanger theory and counter-cross-flow design approach. An exchanger membrane surface aspect ratio (ratio of exchanger membrane surface height to exchanger length) of 1/9 and the desiccant solution entrance ratio (ratio of desiccant solution entrance length to exchanger length) of 1/24 were employed. Based on different heat transfer case studies, the energy transfer size of each exchanger was determined as 1800 mm x 200 mm x 86 mm. ProporeTM was used as the membrane material and Magnesium-Chloride solution was employed as the desiccant solution.<p> The RAMEE performance (sensible, latent and total effectiveness) was evaluated by testing the system in a run-around membrane energy exchanger test apparatus by varying the air stream and liquid solution-flow rates at standard summer and winter operating conditions. From the test data, the RAMEE effectiveness values were found to be sensitive to the air and solution flow rates. Maximum total effectiveness of 45% (summer condition) and 50% (winter condition) were measured at a face velocity ¡Ö 2 m/s. A comparison between the experimental and numerical results from the literature showed an average absolute discrepancy of 3% to 8% for the overall total system effectiveness. At a low number of heat transfer units, i.e. NTU = 4, the numerical and experimental results show agreement within 3% and at NTU = 12 the experimental data were 8% lower than the simulations. The counter-cross-flow RAMEE total system effectiveness were found to be 10% to 20% higher than those reported for a cross-flow RAMEE system by another researcher.<p> It is thought that discrepancies between experimental and predicted results (design and numerical effectiveness) may be due to the mal-distributed desiccant solution-flow, desiccant solution leakage, lower than expected water vapor permeability of the membrane, uncertainties in membrane properties (thickness and water vapor permeability) and heat loss/gain effects. Future research is needed to determine the exact cause of the discrepancies.

In this study, a novel counter-cross-flow run-around membrane energy exchanger (RAMEE) system was designed and tested in the laboratory. The RAMEE system consists of two (2) counter-cross-flow Liquid-to-Air Membrane Energy Exchangers (LAMEEs) to be located in the supply and exhaust air streams in the building Heating Ventilation and Air-Conditioning (HVAC) system. Inside each exchanger, a micro-porous membrane separates the air and liquid streams and allows transfer of the sensible and latent energy from the air stream to the liquid stream or vice-versa. The system exchanges sensible and latent energy between supply and exhaust air streams using a desiccant solution loop. The supply and exhaust air streams in the RAMEE can be located far apart from each other or adjacent to each other. The flexibility of non-adjacent ducting makes the RAMEE system a better alternative compared to available energy recovery systems for the retrofit of HVAC systems.<p> Two counter-cross-flow exchangers for the RAMEE system were designed based on an industry recommended standard which is to obtain a target overall system effectiveness of 65% for the RAMEE system at a face velocity of 2 m/s. The exchanger design was based on heat exchanger theory and counter-cross-flow design approach. An exchanger membrane surface aspect ratio (ratio of exchanger membrane surface height to exchanger length) of 1/9 and the desiccant solution entrance ratio (ratio of desiccant solution entrance length to exchanger length) of 1/24 were employed. Based on different heat transfer case studies, the energy transfer size of each exchanger was determined as 1800 mm x 200 mm x 86 mm. ProporeTM was used as the membrane material and Magnesium-Chloride solution was employed as the desiccant solution.<p> The RAMEE performance (sensible, latent and total effectiveness) was evaluated by testing the system in a run-around membrane energy exchanger test apparatus by varying the air stream and liquid solution-flow rates at standard summer and winter operating conditions. From the test data, the RAMEE effectiveness values were found to be sensitive to the air and solution flow rates. Maximum total effectiveness of 45% (summer condition) and 50% (winter condition) were measured at a face velocity ¡Ö 2 m/s. A comparison between the experimental and numerical results from the literature showed an average absolute discrepancy of 3% to 8% for the overall total system effectiveness. At a low number of heat transfer units, i.e. NTU = 4, the numerical and experimental results show agreement within 3% and at NTU = 12 the experimental data were 8% lower than the simulations. The counter-cross-flow RAMEE total system effectiveness were found to be 10% to 20% higher than those reported for a cross-flow RAMEE system by another researcher.<p> It is thought that discrepancies between experimental and predicted results (design and numerical effectiveness) may be due to the mal-distributed desiccant solution-flow, desiccant solution leakage, lower than expected water vapor permeability of the membrane, uncertainties in membrane properties (thickness and water vapor permeability) and heat loss/gain effects. Future research is needed to determine the exact cause of the discrepancies.

The spray drying process is widely established in the industry worldwide. However, due to its complexity in predicting variables, the technology is often regarded as a "Black box" process. In this study, a model based on energy and mass balances is designed and validated using Matlab/Simulink software and real data from a medium-sized machinery, specifically the Production Minor manufactured by GEA NIRO S/A. Additionally, the simulation incorporates a heat recovery system based on a heat pump, and its economic feasibility is examined.The simulation is validated for a narrow range of variables and demonstrates an accuracy of approximately 95% in most cases.The heat recovery system achieves an average natural gas savings of 0.43 kg/h. However, this saving is accompanied by an additional electrical consumption of 2.1 kW resulting from the operation of the heat pump.The economic feasibility study of the heat recovery system reveals an extra production cost of 0.1€/h in exchange for a 36% average reduction in natural gas dependency.

The Water Recovery System (WRS) is one of the necessary subsystems in an Advanced Life Support program. It regenerates potable water by processing wastewater generated on a space shuttle or on a space station. The Biological Water Processor (BWP) is one of the complex subsections of WRS that involves processes described by continuous time as well as discrete event dynamics. Such systems can be modeled as hybrid dynamical systems in MATLAB/Stateflow. The following state variables of the BWP have been simulated in MATLAB: Pressure drop across Organic Carbon Oxidation Reactor (OCOR), Pressure drop across nitrification reactor, nitrifier flow rate, total flow to OCOR, Gas-liquid separator level, feed pump modes. The developed model of the BWP can be used for the simulation of the complete WRS and also for synthesis of a distributed control laws for the BWP subsection.

A strategy for beneficiation of wastewater streams from fissure and process water developed for a gold mine operation in the west of Johannesburg was tested for viability in a pilot study. The investigation was aimed at evaluating the compliance of the finally discharged effluent streams with the current Water Use Licence (WUL). The core of the water recovery process consisted of softening to remove divalent cationic species, followed by ion exchange processes employing Strong Acid Cationic (SAC) resins and Weak Acid Cationic (WAC) resins. An operational design limitation was that the crystalactor used in the softening stage had a minimum capacity of 20 000 L/h, whereas the rest of the system could be operated at flow rates of as low as 2 000 L/h. For this reason, the softening step was done in semi-batch mode. Calcium hardness was decreased from 70 mg/L to values lower than 40 mg/L (as Ca2+). During the ion exchange (water recovery) process, columns using SAC resin produced better quality water than the WAC resins. The SAC columns produced water compatible with South African Water Quality Standards. Additionally, the use of SAC proved to be a more financially favourable option, since the regenerant stream contained high concentrations of calcium nitrate, magnesium nitrate and sodium nitrate fertilizer. The latter could be sold as a liquid fertilizer to farmers. In addition to the above findings, the pilot system reduced the concentration of toxic and radiotoxic metals such as uranium. The final concentration of the uranium in the effluent (0.01 mg/L) was below the regulation limit 0.07 mg/L. The selective removal of uranium is crucial in order to produce high-quality fertilizer from the ion exchange regeneration streams. Copyright / Dissertation (MEng)--University of Pretoria, 2013. / Chemical Engineering / unrestricted

This thesis describes the development of an autonomous recovery system for stratospheric balloons, focusing on the novel pressurised balloon prototype BALMAN of CNES. Stratospheric balloons, reaching altitudes of up to 40 km, are utilised for scientific experiments, with recovery of payloads being a critical aspect. While traditional recovery methods involve separating the balloon envelope and deploying a parachute, BALMAN's parachute will be deployed in free fall. The proposed autonomous system comprises decision-making and electronics components. The decision-making segment employs microcontrollers and environmental sensors to recognise the balloon's descent, triggering the release decision. The electronics section, responsible for providing energy to a pyro cutter, is designed with electrical switches and capacitors. Thermal simulations guide the placement of heaters, maintaining system temperature within operational limits. The final prototype, tested for functionality on-ground, exhibits a measured energy release of 24 mJ, double the requirement for pyro cutter activation. However, environmental and flight testing remain pending. The system's potential applications extend beyond BALMAN, offering a standardised autonomous recovery solution for various balloons. This innovation promises enhanced landing accuracy, obviates the need for telecommunication in recovery, and facilitates payload descent deceleration. Future endeavors involve comprehensive testing and potential integration into BALMAN missions, showcasing the system's adaptability and operational simplicity across diverse stratospheric endeavors.

A CO2 emission analysis and system investigation of a direct fuel cell waste energy recovery and power generation system (DFC-ERG) for pressure letdown stations was undertaken. The hybrid system developed by FuelCell Energy Inc. is an integrated turboexpander and a direct internal reforming molten carbonate fuel cell system in a combined circle. At pressure letdown stations, popularly called city gates, the pressure of natural gas transported on long pipelines is reduced by traditional pressure regulating systems. Energy is lost as a result of pressure reduction. Pressure reduction also results in severe cooling of the gas due to the Joule Thompson effect, thus, requiring preheating of the natural gas using traditional gas fired-burners. The thermal energy generated results in the emission of green house gases. The DFC-ERG system is a novel waste energy recovery and green house gas mitigation system that can replace traditional pressure regulating systems on city gates. A DFC-ERG system has been simulated using UniSim Design process simulation software. A case study using data from Utilities Kingston’s city gate at Glenburnie was analysed. The waste energy recovery system was modelled using the design specifications of the FuelCell Energy Inc’s DFC 300 system and turboexpander design characteristics of Cryostar TG120. The Fuel Cell system sizing was based on the required thermal output, electrical power output, available configuration and cost. The predicted performance of the fuel cell system was simulated at a current density of 140mA/cm2, steam to carbon ratio of 3, fuel utilization of 75% and oxygen utilization of 30%. The power output of the turboexpander was found to strongly depend on the high pressure natural gas flowrate, temperature and pressure. The simulated DFC-ERG system was found to reduce CO2 emissions when the electrical power generated by the DFC-ERG system replaced electrical power generated by a coal fired plant. / Thesis (Master, Chemical Engineering) -- Queen's University, 2010-08-31 02:02:11.392

The rise in green-house gases emissions is an overall problem nowadays, in order to achieve the European goals by 2030, several changes are needed. Supermarkets are responsible of 3% of the emissions in Sweden, which makes them a clear target to reduce emissions. By using heat recovery systems, supermarkets can recover part of the heat excesses and use it for ambient or water heating. This can generate a reduction in heat demand, however, to be able to recover heat excess, more electricity is consumed. In the case study conducted, the heat recovery system of a supermarket in Matorp, Sweden has been analyzed. Studying the performance of the system, it has been seen that the COP values are around 2, low values compared with other case studies. The reason for this low performance is because of low discharge pressure, that also leads to a low amount of heat recovered. In the techno economic analysis, the operational costs of the heat recovery system are compared to the ones that a floating condensations system would have had. In the operational costs, both the electricity and the heating costs are considered. The results show that the overall floating condensation costs are only 1.86% higher than the heat recovery costs. This is a small value, but it has to be taken into account that the performance of the system and the heat recovered is low. Finally, in the environmental analysis the CO2 emissions savings by using a HR instead of a FC one is calculated, showing a reduction of 2.3 tons of CO2 per year. / Ökningen av utsläpp av växthusgaser är ett övergripande problem nuförtiden, och för att uppnå de europeiska målen till 2030 behövs flera förändringar. Supermarkets står för 3% av utsläppen i Sverige, vilket gör dem till en tydlig målgrupp för att minska utsläppen. Genom att använda värmeåtervinningssystem kan livsmedelsbutiker återvinna en del av överskottsvärmen och använda den för uppvärmning av lokaler eller vatten. Detta kan minska värmebehovet, men för att kunna återvinna överskottsvärme förbrukas mer elektricitet. I den genomförda fallstudien har värmeåtervinningssystemet i en livsmedelsbutik i Matorp, Sverige analyserats. Genom att studera systemets prestanda har man sett att COP-värdena ligger runt 2, vilket är låga värden jämfört med andra fallstudier. Anledningen till denna låga prestanda är det låga avluftningstrycket, vilket också leder till en låg mängd återvunnen värme. I den tekno-ekonomiska analysen jämförs driftskostnaderna för värmeåtervinningssystemet med de som ett flytande kondensationssystem skulle ha haft. I driftskostnaderna beaktas både el- och uppvärmningskostnader. Resultaten visar att de totala kostnaderna för flytande kondensation endast är 1,86% högre än kostnaderna för värmeåtervinning. Detta är ett litet värde, men det måste beaktas att systemets prestanda och den återvunna värmen är låg. Slutligen, i den miljömässiga analysen beräknas minskningen av CO2-utsläpp genom att använda ett HR istället för ett FCsystem, vilket visar en minskning med 2,3 ton CO2 per år.