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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.
241

Zatěžovací zkouška a statické posouzení stropní ŽB konstrukce 1.poloviny 20.století / Static load test and the assessment ceiling of reinforced concrete structure built in the 1st half of 20th century

Málek, Jaroslav January 2012 (has links)
This master thesis deals with static load test and static assessment of selected segments of reinforced concrete ceiling construction of the Hennebique system at the Faculty of Arts at Masaryk University in Brno. This thesis contains: the execution of the static load test, the data evaluation of the static load test and the data evaluation of the complementary laboratory testing, geometric orientation of bearing elements, the checking of the ceiling placement in the peripheral position, and the diagnosis of the reinforcing of the construction. This thesis also includes the static assessment according to various standard norm rules and the numerical analysis in ATENA software program.
242

Automatická detekce knihovního kódu ze spustitelných souborů typu PE / Automatic Library Code Detection in PE Executable Files

Mareš, Petr January 2008 (has links)
Master's thesis describes imported functions detection in PE executables, which are from static libraries. Main reason is process automatization and analysis simplification. Detection is solved by searching prepared patterns with missmatch tolerance. Missmatch are caused by changing address during building application. Resulting application supports compiler detection and it contains patterns for MinGW32, Visual studio 2005 and C++ Builder 6.
243

Estimation of Static Stiffnesses from Free Boundary Dynamic (FRF) Measurements

Pasha, Hasan G. January 2014 (has links)
No description available.
244

Signaling Schemes And Fundamental Limits of A 2-User Static Gaussian Multiple-Access Channel With 1-Bit Analog-To-Digital-Converter

Banik, Sejuti 28 July 2022 (has links)
No description available.
245

Development of intelligent systems for evaluating voltage profile and collapse under contingency operation

Mohammed, Mahmoud M. Jr. January 1900 (has links)
Doctor of Philosophy / Department of Electrical and Computer Engineering / Shelli K. Starrett / Monitoring and control of modern power systems have become very complex tasks due to the interconnection of power grids. These large-scale power grids confront system operators with a huge set of system inputs and control parameters. This work develops and compares intelligent systems-based algorithms which may be considered by power system operators or planners to help manage, process, and evaluate large amounts of data due to varying conditions within the system. The methods can be used to provide assistance in making operational control and planning decisions for the system in a timely manner. The effectiveness of the proposed algorithms is tested and validated on four different power systems. First, Artificial Neural Network (ANN) models are developed and compared for two different voltage collapse indices and utilizing two different-sized sets of inputs. The ANNs monitor and evaluate the voltage profile of a system and generate intelligent conclusions regarding the status of the system from a voltage stability perspective. A feature reduction technique, based on the analysis of generated data, is used to decrease the number of inputs fed to the ANN, decreasing the number of physical quantities that need to be measured. The major contribution of this work is the development of four different algorithms to control the VAR resources in a system. Four different objectives were also considered in this part of the work, namely: minimization of the number of control changes needed, minimization of the system power losses, minimization of the system's voltage deviations, and consideration of the computational time required. Each of the algorithms is iterative in nature and is designed to take advantage of a method of decoupling the load flow Jacobian matrix to decrease the time needed per iteration. The methods use sensitivity information derived from the load flow Jacobian and augmented with equations relating the desired control and dependent variables. The heuristic-sensitivity based method is compared to two GA-based methods using two different objective functions. In addition, a FL algorithm is added to the heuristic-sensitivity algorithm and compared to a PS-based algorithm. The last part of this dissertation presents the use of one of the GA-based algorithms to identify the size of shunt capacitor necessary to enhance the voltage profile of a system. A method is presented for utilizing contingency cases with this algorithm to determine required capacitor size.
246

Design and development of a composite ventral fin for a light aircraft / Justin Lee Pieterse

Pieterse, Justin Lee January 2015 (has links)
The AHRLAC aircraft is a high performance light aircraft that is developed and manufactured in South Africa by Aerosud ITC in partnership with Paramount. This aircraft is the first of its kind to originate from South Africa. The aircraft has a twin boom, tandem pilot seating configuration, with a Pratt and Whitney turbine-propeller engine in a pusher configuration. The main structure of the aircraft is a conventional metallic structure, while the fairings and some secondary structures are composite. This study will focus on the design and development of the composite ventral fin of the first prototype aircraft, the experimental demonstrator model (XDM). It is crucial to ensure that the ventral fin can function safely within the design requirements of the aircraft under the loads which the fin is likely to encounter. Preceding the design process, a critical overview of composite materials used in aircraft applications is provided. This will include the materials, manufacturing methods, analysis and similar work done in this field of study. The literature will be used in the study for decision-making and validation of proven concepts and methodologies. The first part of this study entailed choosing a suitable composite material and manufacturing method for this specific application. The manufacturing method and materials used had to suit the aircraft prototype application. The limitations of using composite materials were researched as to recognize bad practice and limit design flaws on the ventral fin. Once the material and manufacturing methods were chosen, ventral fin concepts were evaluated using computer aided finite element analysis (FEA) with mass, stiffness and strength being the main parameters of concern. The load cases used in this evaluation were given by the lead structural engineer and aerodynamicist. The calculations of these loads are not covered in detail in this study. The FEA input material properties used, were determined by material testing by the relevant test methods. The ventral fin concept started as the minimal design with the lowest mass. The deflections, composite failure and fastener failure were then evaluated against the required values. The concept was modified by adding stiffening elements, such as ribs and spars, until satisfactory results were obtained. In this way a minimal mass component is designed and verified that it can adequately perform its designed tasks under the expected load conditions. Each part used in the ventral fin assembly was not individually optimized for mass, but rather the assembly as a whole. The final concept was modelled using the computer aided design software, CATIA. This model used in combination with a ply book made it possible to manufacture the ventral fin in a repeatable manner. A test ventral fin was manufactured using the selected materials and manufacturing methods to validate the design methodology. In the next step the selected load cases were used in static testing to validate the FEM through comparison. The result of the study is a composite ventral fin of which the mass, stiffness and strength are suitable to perform its function safely on the first prototype AHRLAC aircraft. The study concludes on the process followed from material selection to FEA and detail design, in order for this same method to be used on other AHRLAC XDM composite parts. / M (Mechanical Engineering), North-West University, Potchefstroom Campus, 2015
247

Design and development of a composite ventral fin for a light aircraft / Justin Lee Pieterse

Pieterse, Justin Lee January 2015 (has links)
The AHRLAC aircraft is a high performance light aircraft that is developed and manufactured in South Africa by Aerosud ITC in partnership with Paramount. This aircraft is the first of its kind to originate from South Africa. The aircraft has a twin boom, tandem pilot seating configuration, with a Pratt and Whitney turbine-propeller engine in a pusher configuration. The main structure of the aircraft is a conventional metallic structure, while the fairings and some secondary structures are composite. This study will focus on the design and development of the composite ventral fin of the first prototype aircraft, the experimental demonstrator model (XDM). It is crucial to ensure that the ventral fin can function safely within the design requirements of the aircraft under the loads which the fin is likely to encounter. Preceding the design process, a critical overview of composite materials used in aircraft applications is provided. This will include the materials, manufacturing methods, analysis and similar work done in this field of study. The literature will be used in the study for decision-making and validation of proven concepts and methodologies. The first part of this study entailed choosing a suitable composite material and manufacturing method for this specific application. The manufacturing method and materials used had to suit the aircraft prototype application. The limitations of using composite materials were researched as to recognize bad practice and limit design flaws on the ventral fin. Once the material and manufacturing methods were chosen, ventral fin concepts were evaluated using computer aided finite element analysis (FEA) with mass, stiffness and strength being the main parameters of concern. The load cases used in this evaluation were given by the lead structural engineer and aerodynamicist. The calculations of these loads are not covered in detail in this study. The FEA input material properties used, were determined by material testing by the relevant test methods. The ventral fin concept started as the minimal design with the lowest mass. The deflections, composite failure and fastener failure were then evaluated against the required values. The concept was modified by adding stiffening elements, such as ribs and spars, until satisfactory results were obtained. In this way a minimal mass component is designed and verified that it can adequately perform its designed tasks under the expected load conditions. Each part used in the ventral fin assembly was not individually optimized for mass, but rather the assembly as a whole. The final concept was modelled using the computer aided design software, CATIA. This model used in combination with a ply book made it possible to manufacture the ventral fin in a repeatable manner. A test ventral fin was manufactured using the selected materials and manufacturing methods to validate the design methodology. In the next step the selected load cases were used in static testing to validate the FEM through comparison. The result of the study is a composite ventral fin of which the mass, stiffness and strength are suitable to perform its function safely on the first prototype AHRLAC aircraft. The study concludes on the process followed from material selection to FEA and detail design, in order for this same method to be used on other AHRLAC XDM composite parts. / M (Mechanical Engineering), North-West University, Potchefstroom Campus, 2015
248

High performance latent dirichlet allocation for text mining

Liu, Zelong January 2013 (has links)
Latent Dirichlet Allocation (LDA), a total probability generative model, is a three-tier Bayesian model. LDA computes the latent topic structure of the data and obtains the significant information of documents. However, traditional LDA has several limitations in practical applications. LDA cannot be directly used in classification because it is a non-supervised learning model. It needs to be embedded into appropriate classification algorithms. LDA is a generative model as it normally generates the latent topics in the categories where the target documents do not belong to, producing the deviation in computation and reducing the classification accuracy. The number of topics in LDA influences the learning process of model parameters greatly. Noise samples in the training data also affect the final text classification result. And, the quality of LDA based classifiers depends on the quality of the training samples to a great extent. Although parallel LDA algorithms are proposed to deal with huge amounts of data, balancing computing loads in a computer cluster poses another challenge. This thesis presents a text classification method which combines the LDA model and Support Vector Machine (SVM) classification algorithm for an improved accuracy in classification when reducing the dimension of datasets. Based on Density-Based Spatial Clustering of Applications with Noise (DBSCAN), the algorithm automatically optimizes the number of topics to be selected which reduces the number of iterations in computation. Furthermore, this thesis presents a noise data reduction scheme to process noise data. When the noise ratio is large in the training data set, the noise reduction scheme can always produce a high level of accuracy in classification. Finally, the thesis parallelizes LDA using the MapReduce model which is the de facto computing standard in supporting data intensive applications. A genetic algorithm based load balancing algorithm is designed to balance the workloads among computers in a heterogeneous MapReduce cluster where the computers have a variety of computing resources in terms of CPU speed, memory space and hard disk space.
249

Sensitivity and Specificity of the Static-2002 in a Diverse Population

Wong, LeighAnn S. 01 January 2011 (has links)
Assessments designed to estimate the probability of sexual offense recidivism have gained popularity due to research that suggests these instruments are psychometrically sound for this purpose. The Static-2002 (Hanson & Thornton, 2003), an actuarial instrument of sexual recidivism, has been validated in specific populations, but in the absence of multicultural populations. It is necessary to establish the validity of the Static-2002 for a multicultural population, especially considering the increasing impetus to mandate measures of sexual recidivism. This study was designed to assess the predictive validity of the Static-2002 as an actuarial instrument that estimates the probability of sexual, violent, and general recidivism within a multicultural population. Recent criminal histories and de-identified archival records of 103 adult sex offenders were used to complete demographic questionnaires and to calculate retroactive predictive accuracy scores for the Static-2002. Records were obtained from a private practice office in South Florida, which provides outpatient treatment to conditionally released offenders. Hypothesis testing utilized a receiver operating characteristic area under the curve (ROC AUC) analysis to examine the discriminating power of the Static-2002 and to identify optimal cutoff values for each risk category. These cutoff values were then compared to the established Static-2002 risk categories to evaluate the cutoff scores' congruency. For this sample population, resulting ROC AUC values indicated the predictive accuracy of the Static-2002 to be moderate for any (including general; .67) offense recidivism, and high for violent recidivism (.74). However, the Static-2002 was ineffective for predicting sexual recidivism among this sample population since the predictive accuracy of the ROC area for sexual reoffenses was not statistically significant above chance (p = .07). The four Static-2002 risk categories derived for this study are: low, moderate-low, moderate-high, and high. When compared with the established Static-2002 risk categories, this study's risk categories were found to be mostly concurrent with the established categories. Similar to previous research, this study found that when the sample population differs racially/ethnically from the normed population (60% of this study's participants were Hispanic), the Static-2002 was ineffective for accurately predicting sexual reoffending. However, the Static-2002 effectively predicted violent and general recidivism with this sample population.
250

Robust pricing and hedging beyond one marginal

Spoida, Peter January 2014 (has links)
The robust pricing and hedging approach in Mathematical Finance, pioneered by Hobson (1998), makes statements about non-traded derivative contracts by imposing very little assumptions about the underlying financial model but directly using information contained in traded options, typically call or put option prices. These prices are informative about marginal distributions of the asset. Mathematically, the theory of Skorokhod embeddings provides one possibility to approach robust problems. In this thesis we consider mostly robust pricing and hedging problems of Lookback options (options written on the terminal maximum of an asset) and Convex Vanilla Options (options written on the terminal value of an asset) and extend the analysis which is predominately found in the literature on robust problems by two features: Firstly, options with multiple maturities are available for trading (mathematically this corresponds to multiple marginal constraints) and secondly, restrictions on the total realized variance of asset trajectories are imposed. Probabilistically, in both cases, we develop new optimal solutions to the Skorokhod embedding problem. More precisely, in Part I we start by constructing an iterated Azema-Yor type embedding (a solution to the n-marginal Skorokhod embedding problem, see Chapter 2). Subsequently, its implications are presented in Chapter 3. From a Mathematical Finance perspective we obtain explicitly the optimal superhedging strategy for Barrier/Lookback options. From a probability theory perspective, we find the maximum maximum of a martingale which is constrained by finitely many intermediate marginal laws. Further, as a by-product, we discover a new class of martingale inequalities for the terminal maximum of a cadlag submartingale, see Chapter 4. These inequalities enable us to re-derive the sharp versions of Doob's inequalities. In Chapter 5 a different problem is solved. Motivated by the fact that in some markets both Vanilla and Barrier options with multiple maturities are traded, we characterize the set of market models in this case. In Part II we incorporate the restriction that the total realized variance of every asset trajectory is bounded by a constant. This has been previously suggested by Mykland (2000). We further assume that finitely many put options with one fixed maturity are traded. After introducing the general framework in Chapter 6, we analyse the associated robust pricing and hedging problem for convex Vanilla and Lookback options in Chapters 7 and 8. Robust pricing is achieved through construction of appropriate Root solutions to the Skorokhod embedding problem. Robust hedging and pathwise duality are obtained by a careful development of dynamic pathwise superhedging strategies. Further, we characterize existence of market models with a suitable notion of arbitrage.

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