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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.
161

Novel algorithms in wireless CDMA systems for estimation and kernel based equalization

Vlachos, Dimitrios January 2012 (has links)
A powerful technique is presented for joint blind channel estimation and carrier offset method for code- division multiple access (CDMA) communication systems. The new technique combines singular value decomposition (SVD) analysis with carrier offset parameter. Current blind methods sustain a high computational complexity as they require the computation of a large SVD twice, and they are sensitive to accurate knowledge of the noise subspace rank. The proposed method overcomes both problems by computing the SVD only once. Extensive simulations using MatLab demonstrate the robustness of the proposed scheme and its performance is comparable to other existing SVD techniques with significant lower computational as much as 70% cost because it does not require knowledge of the rank of the noise sub-space. Also a kernel based equalization for CDMA communication systems is proposed, designed and simulated using MatLab. The proposed method in CDMA systems overcomes all other methods.
162

Ramverk för temperaturstyrning i Matlab : Programmering av DAQ , datalogger,temperaturskåp och spänningsaggregat

Pavlov, Anton, Särnholm, Jonathan January 2016 (has links)
Examensarbetet utfördes på Calmon. Ett Ramverket för instrumenten:DA/AD - Modul, datalogger, klimatkammare och nätaggregat skapades medhjälp av programmet Matlab. Arbetet utfördes med hjälp av programmeringi syfte att kunna genomföra mätningar på föremål i klimatkammaren.Kommandon för styrning av instrumenten implementerades. För att vägledaanvändaren utvecklades en specifikation och ett exempelprogram.
163

Värmestrålning i ugn för hushållsbruk, modellering – simulering - experiment / Heat radiation in ovens for domestic use, modeling – simulation - experiment

Wahlström, Krister January 2005 (has links)
I många mikrovågsugnar finns grillelement som kan färgsätta matens yta. Vissa kommande modeller av mikrovågsugnar planeras vara utan roterande tallrik och maten blir då stillastående. Därför måste grillelementen och tillhörande reflektorer optimeras så värmestrålningen om möjligt blir jämnt fördelad i ugnen. Syftet med examensarbetet är att undersöka hur värmestrålningen i ugnarna kan beräknas så optimeringar kan göras. Värmestrålningen i en befintlig mikrovågsugn har simulerats och mätts. Simuleringarna och mätningarna visar att värmestrålningens fördelning bör kunna beräknas med tillräcklig noggrannhet då quartzglasen som omger grillelementens värmetrådar försummas, reflektionerna ansätts som diffusa och ytorna ansätts som grå. Väggarnas emissionstal har troligen mindre betydelse för strålningsfördelningen, men påverkar den absoluta strålningen. / In many microwave ovens are grill elements, which give color to the food surface. Some future models of microwave ovens are designed with no turning table and the food will therefore be stationary. The grill elements and their reflectors must therefore be optimized so the heat radiation if possible will be evenly distributed in the oven. The purpose of this work is to examine how the heat radiation in the ovens can be calculated, thus the optimization can be carried out. The heat radiation in an existing microwave oven has been simulated and measured. The simulations and measurements show that the distribution of the heat radiation should be calculated with sufficient accuracy when the quartz glass that surrounds the filament of the grill element is neglected, reflections are assumed to be diffuse and the surfaces are assumed to be mathematically grey. The emissivities of the surfaces
164

VITA 49 Radio DF : Using coherent digital receiver set with VC++ and Octave

Perup, Daniel January 2013 (has links)
The objective of this thesis was to evaluate radio receivers that had been previously acquired for other tasks by the Swedish Defence Materiel Administration, for additional service in a radio direction finding (DF) system. The antenna, calibration signal generator and DF algorithm were provided. As the receivers used the VITA 49 frame format, much of the work involved the interpretation of the frame structure and contents. The other main challenges were to put the receivers into the correct internal state, to compensate the analogue phase errors due to cabling, and to correlate the digital frames according to the time stamps. The work was performed partly as a literature study and, during implementation, by using an investigative trial and-error method. Collection of reference signals, for later offline analysis, was made at the Swedish Defence Research Agency. The findings of the evaluation was that the receivers were phase coherent and that the VITA 49 frame format was suitable for DF use. An apparently systematic error of unknown origin rendered the DF results inaccurate, even though the precision of the results was high. The automatic gain control (AGC) of the receivers did not perform according to norm. If the systematic error is compensated for, and the AGC problem is eliminated, the receivers will function as a DF system using the manufacturer's instructions, with the provided antenna. The performance of the receivers in this setting was not a primary concern for the thesis, but was deemed to be acceptable. Suggestions for further development include finding the source of the systematic error, an automatic calibration function, a more thorough performance analysis, and code optimizations using multiple threads.
165

Ökad resurseffektivitet i kraftvärmesystem genom säsongslagring av värme / Seasonal storage of heat for increased resource efficiency in combined heat and power plant systems

Björe Dahl, Emilia, Sjöqvist, Mikaela January 2014 (has links)
Increased resource efficiency in an energy system could result in large economic and environmental benefits. Tekniska verken i Linköping AB (Tekniska verken) is responsible for the district heating network in Linköping. Their vision is to create the world’s most resource efficient region. An important step towards this vision is more efficient usage of produced heat, something which could be achieved through integration of a seasonal heat storage in the energy system. The purpose of the Master’s thesis is therefore to explore the economic and technical potential for a seasonal heat storage in Tekniska verken’s energy system. The investigated technology is borehole thermal energy storage using two different kinds of borehole heat exchangers; u-pipe and annular coaxial heat exchanger. To evaluate how Tekniska verken’s energy system changes through integration of a seasonal heat storage a calculation model has been developed in MATLAB. The heat from the seasonal storage needs to be upgraded in order to be used in the ordinary district heating network. Therefore two kinds of heat pumps have been evaluated in the model; absorption heat pumps and compression heat pumps. The main method used for calculations on the heat transfer processes in the storage is the finite difference method. During economic calculations, the economic potential of the investment is expressed solely in relation to the scenario that the storage is not built. Four different combinations of borehole heat exchangers and heat pumps have been simulated over a twenty year period. The simulated storages have a depth of 200-250 meters and a radius of approximately 100 meters which relates to1500 boreholes. The result shows small differences between the two types of heat exchangers. The choice of heat pump has though a crucial importance of the economic result. The systems with absorption heat pumps uses drive heat from existing steam production and can cover a major part of the peak load during winter. Meanwhile the compression heat pumps have a large cost for electricity. This causes a negative net present value according to the result, while the systems with absorption heat pumps have a discounted pay-back time of 12 years. Another positive effect of the systems with absorption heat pumps is the decrease in carbon dioxide emissions from the heat production. The result of the Master thesis shows that both economic advantages and increased resource efficiency can be achieved through integration of a borehole thermal energy storage with absorptions heat pumps.  To further investigate this potential seems therefore beneficial. / Att öka resurseffektiviteten i ett energisystem kan medföra stora ekonomiska och miljömässiga fördelar. Tekniska verken i Linköping AB (Tekniska verken) är ansvariga för Linköpings fjärrvärmeförsörjning. De har som vision att skapa världens mest resurseffektiva region. Ett viktigt steg på vägen för att nå detta är bättre utnyttjande av producerad värme, något som kan uppnås genom integrering av ett säsongsvärmelager i energisystemet. Syftet med detta examensarbete är därmed att utreda vilken ekonomisk och teknisk potential som finns för ett säsongsvärmelager i Tekniska verkens energisystem. Den lagerteknik som undersöks är borrhålslager med två typer av borrhålsvärmeväxlare; u-rör och ringformad koaxial borrhålsvärmeväxlare. För att utvärdera hur Tekniska verkens energisystem förändras vid integrering av ett säsongsvärmelager har en beräkningsmodell byggts upp i MATLAB. Två typer av värmepumpar har utvärderats i modellen; absorptionsvärmepumpar och kompressions­värmepumpar. Anledningen till detta är att den säsongslagrade värmen behöver uppgraderas för att kunna användas i ordinarie fjärrvärmenät. Den huvudsakliga metoden som använts vid beräkning av värmeöverföringsprocesser är finita differensmetoden. Vid ekonomiska beräkningar uttrycks investeringens ekonomiska potential enbart i relation till scenariot att lagret inte byggs. Fyra system med olika kombinationer av borrhålsvärmeväxlare och värmepumpar har simulerats över en tjugoårsperiod. De simulerade lagren har ett djup på 200-250 meter och en radie på cirka 100 meter vilket motsvarar ungefär 1500 borrhål. Resultatet påvisar små skillnader mellan de två typerna av borrhålsvärmeväxlare. Vilken typ av värmepump som används har dock en avgörande betydelse för det ekonomiska resultatet. Systemen med absorptionsvärmepumpar drivs av värme från befintlig ångproduktion och klarar av att täcka en större andel av topplasten vintertid. Samtidigt medför användning av kompressionsvärmepumpar en stor kostnad för drivel. Detta medför ett negativt nettonuvärde enligt examensarbetets resultat, medan systemen med absorptionsvärmepumpar har en diskonterad avbetalningstid på 12 år. Ytterligare en positiv effekt av systemen med absorptionsvärmepump är minskade utsläpp av koldioxid. Utifrån examensarbetets resultat framstår det som att genom integrering av ett borrhålslager med absorptionsvärmepumpar uppnås både ekonomiska vinster och en ökad resurseffektivitet i Tekniska verkens energisystem. Att fortsätta utreda denna potential framstår därmed som fördelaktigt.
166

An Optimal Control Toolbox for MATLAB Based on CasADi

Leek, Viktor January 2016 (has links)
Many engineering problems are naturally posed as optimal control problems. It may involve moving between two points in the fastest possible way, or to put a satellite into orbit with minimum energy consumption. Many optimal control problems are too difficult to be solved analytically and therefore require the use of numerical methods. The numerical methods that are the most widespread are the so-called direct methods. However, there is one major drawback with these. If the problem is non-convex, the solution is not guaranteed globally optimal, that is, the absolute best, instead it is guaranteed locally optimal, that is the best in its vicinity. To compensate for this, the problem should be solved several times, under different conditions, in order to investigate whether the solution is a good candidate for the global optimum. CasADi is a software specifically designed for dynamic optimization. It has gained wide spread in recent years because it provides all the necessary building blocks for dynamic optimization. This has given individual engineers and scientists the ability to independently formulate and solve all sorts of optimal control problems. However, this requires good theoretical knowledge of the necessary numerical methods. The advantage of a toolbox, which solves general optimal control problems, is that the underlying numerical methods have been tested and shown to function on optimal control problems with known solutions. This means that the user does not need exhaustive knowledge of the numerical methods involved, but can focus on formulating and solving optimal control problems. The main contribution of this thesis is an optimal control toolbox for MATLAB based on CasADi. The toolbox does not require expert knowledge of the numerical methods, but provides an alternative lower level abstraction that allows for more complex problem formulations. The toolbox implements two direct methods, direct multiple shooting and direct collocation. This allows a problem formulation with many degrees of freedom. The most important property of the toolbox is that the discretization can be changed, without the problem formulation needing to be altered. This way the user can easily change the conditions for his/her problem. The thesis describes how the two implemented direct methods work, and the design choices made. It also describes what remains to test and evaluate, and the problems that have been used as a reference during the development process.
167

Study of Numerical Model Parameters and Crack Tip of a Packaging Materials

Kodavati, Venkata Seshank, Buraga, Devi Prasad January 2017 (has links)
Packaging industries widely use Low-Density Polyethylene (LDPE) in manufacturing different types of containers to store the food products. They are difficult to model numerically in order to have similar experimental response. This research deals with the study of numerical material model parameters of continuum LDPE. It is carried out with the help of experiments along with the numerical simulation of LDPE. Study of stress-strain distribution at crack tip and elements close to the tip is carried out in the LDPE material with the pre-existing center crack with varying lengths. By implementing an optimization algorithm and automating the simulation with the help of python code, we obtain a set of parameters. This obtained data for the material can be used directly for numerical simulation in the future without carrying out additional experimental studies. After implementing the optimization algorithm is also validated, against the results that were close to the experimental response.
168

System for Tracking of Surgical Tools and Assessment of Surgical Skills Using Continuously Adaptive Mean Shift Methodology

Manat, Namith N. 01 January 2005 (has links)
A tracking system that serves as a tool for tracking the movement of surgical instruments has been developed. The system tracks color markers on the surgical instruments. The Continuously Adaptive Mean Shift (CAMSHIFT) methodology was employed for tool tracking and a total distance traversed by the surgical instrument of interest was calculated. Two cameras were used to record the motion of the tool and the software developed was used to track the movement of markers on the tools over subsequent frames. The information thus derived from the two views of cameras was used to calculate the three dimensional coordinates of the location of the marker on the instrument and subsequently the distance traversed. MATLAB, which is a commercial software package, was used to implement the tool tracking algorithm and for developing the GUI (Graphic User Interface). Data was collected using Commercial off the shelf (COTS) camera hardware and processing was done on a 2.2 GHz, 512 MB RAM Intel Pentium 4 computer.
169

Monitoring and Inverse Dispersion Modeling to Quantify VOCs from MSW Landfill

Das, Sarit Kumar 20 December 2009 (has links)
In USA, the Municipal Solid Waste (MSW) landfills accumulate about 130 million tons of solid waste every year. A significant amount of biodegradable solid waste is converted to landfill gas due to anaerobic stabilization by bacteria. These biochemical reactions produce volatile organic compounds (VOCs) like methane and others. Due to heterogeneity in refuse composition, unpredictable distribution of favorable environmental conditions for bacterial actions and highly uncertain pathway of gases, estimation of landfill gas emission for a particular landfill is complex. However, it is important to quantify landfill gases for health risk assessment and energy recovery purposes. This research is based on the monitoring and modeling methodology proposed by researchers at University of Central Florida is reported in this thesis. River Birch Sub-title D landfill, Westwego, LA was selected as the study area. The total emission calculated using the mathematical model ran on MATLAB is comparable with the result obtained from EPA LandGEM model, using historical waste deposition records
170

The development of a fuzzy expert system to help top decision makers in political and investment domains

Alshayji, Sameera January 2012 (has links)
The world’s increasing interconnectedness and the recent increase in the number of notable regional and international events pose greater and greater challenges for political decision-making, especially the decision to strengthen bilateral economic relationships between friendly nations. Typically, such critical decisions are influenced by certain factors and variables that are based on heterogeneous and vague information that exists in different domains. A serious problem that the decision-maker faces is the difficulty in building efficient political decision support systems (DSS) with heterogeneous factors. One must take many factors into account, for example, language (natural or human language), the availability, or lack thereof, of precise data (vague information), and possible consequences (rule conclusions). The basic concept is a linguistic variable whose values are words rather than numbers and are therefore closer to human intuition. A common language is thus needed to describe such information which requires human knowledge for interpretation. To achieve robustness and efficiency of interpretation, we need to apply a method that can be used to generate high-level knowledge and information integration. Fuzzy logic is based on natural language and is tolerant of imprecise data. Fuzzy logic’s greatest strength lies in its ability to handle imprecise data, and it is perfectly suited for this situation. In this thesis, we propose to use ontology to integrate the scattered information resources from the political and investment domains. The process started with understanding each concept and extracting key ideas and relationships between sets of information by constructing object paradigm ontology. Re-engineering according to the object-paradigm (OP) provided quality for the developed ontology where conceptualization can provide more expressive, reusable object and temporal ontology. Then fuzzy logic has been integrated with ontology. And a fuzzy ontology membership value that reflects the strength of an inter-concept relationship to represent pairs of concepts across ontology has been consistently used. Each concept is assigned a fixed numerical value representing the concept consistency. Concept consistency is computed as a function of strength of all the relationships associated with the concept. Fuzzy expert systems enable one to weigh the consequences (rule conclusions) of certain choices based on vague information. Rule conclusions follow from rules composed of two parts, the if antecedent (input) and the then consequent (output). With fuzzy expert systems, one uses fuzzy logic toolbox graphical user interface (GUI) tools to build up a fuzzy inference system (FIS) to aid in decision-making. This research includes four main phases to develop a prototype architecture for an intelligent DSS that can help top political decision makers.

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