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1
Посохов, Игорь Михайлович. "Комплексный анализ и рейтинговая оценка финансового состояния корпорации". Thesis, World Press, Чешская республика, 2013. http://repository.kpi.kharkov.ua/handle/KhPI-Press/29358.
Повний текст джерела
2
Thomas, Michael Patrick. "Long term extrapolation and hedging of the South African yield curve." Diss., Pretoria : [s.n.], 2009. http://upetd.up.ac.za/thesis/available/etd-06172009-085254.
Повний текст джерела
3
Bonifacio, Henry F. "Estimating particulate emission rates from large beef cattle feedlots." Diss., Kansas State University, 2013. http://hdl.handle.net/2097/15530.
Повний текст джерелаАнотація:
Doctor of PhilosophyDepartment of Biological and Agricultural Engineering
Ronaldo G. Maghirang
Emission of particulate matter (PM) and various gases from open-lot beef cattle feedlots is becoming a concern because of the adverse effects on human health and the environment; however, scientific information on feedlot emissions is limited. This research was conducted to estimate emission rates of PM[subscript]10 from large cattle feedlots. Specific objectives were to: (1) determine feedlot PM[subscript]10 emission rates by reverse dispersion modeling using AERMOD; (2) compare AERMOD and WindTrax in terms of their predicted concentrations and back-calculated PM[subscript]10 emission rates; (3) examine the sensitivity of both AERMOD and WindTrax to changes in meteorological parameters, source location, and receptor location; (4) determine feedlot PM[subscript]10 emission rates using the flux-gradient technique; and (5) compare AERMOD and computational fluid dynamics (CFD) in simulating particulate dispersion from an area source. PM[subscript]10 emission rates from two cattle feedlots in Kansas were determined by reverse dispersion modeling with AERMOD using PM[subscript]10 concentration and meteorological measurements over a 2-yr period. PM[subscript]10 emission rates for these feedlots varied seasonally, with overall medians of 1.60 and 1.10 g /m[superscript]2 -day. Warm and prolonged dry periods had significantly higher PM emissions compared to cold periods. Results also showed that the PM[subscript]10 emissions had a diurnal trend; highest PM[subscript]10 emission rates were observed during the afternoon and early evening periods. Using particulate concentration and meteorological measurements from a third cattle feedlot, PM[subscript]10 emission rates were back-calculated with AERMOD and WindTrax. Higher PM[subscript]10 emission rates were calculated by AERMOD, but their resulting PM[subscript]10 emission rates were highly linear (R[superscript]2 > 0.88). As such, development of conversion factors between these two models is feasible. AERMOD and WindTrax were also compared based on their sensitivity to changes in meteorological parameters and source locations. In general, AERMOD calculated lower concentrations than WindTrax; however, the two models responded similarly to changes in wind speed, surface roughness, atmospheric stability, and source and receptor locations. The flux-gradient technique also estimated PM[subscript]10 emission rates at the third cattle feedlot. Analyses of PM[subscript]10 emission rates and meteorological parameters indicated that PM[subscript]10 emissions at the feedlot were influenced by friction velocity, sensible heat flux, temperature, and surface roughness. Based on pen surface water content measurements, a water content of at least 20% (wet basis) significantly lowered PM[subscript]10 emissions at the feedlot. The dispersion of particulate from a simulated feedlot pen was predicted using CFD turbulence model ([kappa]-[epsilon] model) and AERMOD. Compared to CFD, AERMOD responded differently to wind speed setting, and was not able to provide detailed vertical concentration profiles such that the vertical concentration gradients at the first few meters from the ground were negligible. This demonstrates some limitations of AERMOD in simulating dispersion for area sources such as cattle feedlots and suggests the need to further evaluate its performance for area source modeling.
4
Saw, Yoo-Sok. "Nonlinear rate control techniques for constant bit rate MPEG video coders." Thesis, University of Edinburgh, 1997. http://hdl.handle.net/1842/1381.
Повний текст джерелаАнотація:
Digital visual communication has been increasingly adopted as an efficient new medium in a variety of different fields; multi-media computers, digital televisions, telecommunications, etc. Exchange of visual information between remote sites requires that digital video is encoded by compressing the amount of data and transmitting it through specified network connections. The compression and transmission of digital video is an amalgamation of statistical data coding processes, which aims at efficient exchange of visual information without technical barriers due to different standards, services, media, etc. It is associated with a series of different disciplines of digital signal processing, each of which can be applied independently. It includes a few different technical principles; distortionrate theory, prediction techniques and control theory. The MPEG (Moving Picture Experts Group) video compression standard is based on this paradigm, thus, it contains a variety of different coding parameters which may result in different performance depending on their values. It specifies the bit stream syntax and the decoding process as its normative parts. The encoder details remain nonnormative and are configured by a specific design. This means that the MPEG video encoder has a great deal of flexibility in the aspects of performance and implementation. This thesis deals with control techniques for the data rate of compressed video, which determine the encoding efficiency and video quality. The video rate control is achieved by adjusting quantisation step size depending on the occupancy of a transmission buffer memory which stores the compressed video data for a specific period of time. Conventional video rate control techniques have generally been based either on linear predictive or on control theoretic models. However, this thesis takes a different view on digital video and MPEG video coding, and focuses on the non-stationary and nonlinear nature of realistic moving pictures. Furthermore, considering the MPEG encoding structure involved in the different disciplines, A series of improvements for video rate control are proposed, each of which enhances the performance of the MPEG encoder. A nonlinear quantisation control technique is investigated, which controls the buffer occupancy with the quantiser using a series of nonlinear functions. Linear and nonlinear feed-forward networks are also employed to control the quantiser. The linear combiner is used as a linear estimator and a radial basis function network as a nonlinear one. Finally, fuzzy rulebased control is applied to exploit the advantages of the nonlinear control technique which is able to provide linguistic judgement in the control mechanism. All these techniques are employed according to two global approaches (feedforward and feedback) applied to the rate control. The performance evaluation is carried out in terms of controllability over bit rate variation and video quality, by conducting a series of simulations.
5
Heap, John. "Enhanced techniques for complex interest rate derivatives." Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.506270.
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6
Handcock, Jason Anthony. "Video compression techniques and rate-distortion optimisation." Thesis, University of Bristol, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326726.
Повний текст джерела
7
Yu, Yong. "Time domain equalizer design based on multi-rate technique." Thesis, University of Ottawa (Canada), 2002. http://hdl.handle.net/10393/6310.
Повний текст джерелаАнотація:
Discrete Multitone is adopted in Digital Subscriber Line to offer high-speed data communication on the UTP channel. To combat the channel distortion, DMT system employed Time Domain Equalizer and Cyclic Prefix. In this thesis, we analyze different existing time domain equalizer design methods and their performances are compared based on our simulation results. Modification of the current method is proposed and significant performance improvement is obtained. Multi-rate equalization is studied theoretically, which enables us to achieve zero ISI channels that can be used not only in DMT system but also in all other communication systems. Our simulation results show that the new design method is superior and practical.
8
Watson, Vincent C. "Angular rate estimation by multiplicative Kalman filtering techniques." Thesis, Monterey, Calif. : Naval Postgraduate School, 2003. http://handle.dtic.mil/100.2/ADA420668.
Повний текст джерелаАнотація:
Thesis (M.S. in Astronautical Engineering)--Naval Postgraduate School, December 2003."December 2003". Thesis advisor(s): Cristi, Roberto ; Agrawal, Brij. Includes bibliographical references (p. 53). Also available online.
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Monk, Scott. "Neural response modelling and spike rate estimation techniques." Thesis, McGill University, 2014. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=123255.
Повний текст джерелаАнотація:
Using point processes to model neural spike sequences allows the application of classical estimation techniques in their analysis. Estimation of the time varying rate at which spikes occur is often conducted to draw inference on the stimulus which triggered the response. Such estimation schemes are often founded on the assumption that spiking follows Poisson statistics, however, the observed firing rate is a product of both the stimulus and bio-physical properties of the neuron. A point process model for neural data must then incorporate dependency both on stimulus and intrinsic characteristics of the cell. To achieve this we modify the Poisson model such that it includes the refractory phenomenon observed in spiking behaviour. This results in a modified firing rate which is free from distortion caused by refractory effects. A Maximum Likelihood (ML) estimation technique for this adjusted firing rate which better represents some relation to the stimulus is presented. We propose and justify a parametric model to represent a broad class of arbitrary firing rates. The corresponding likelihood equation for the firing rate parameters given an observed spike sequence is derived, however, several numerical methods are required to findthe ML estimate. These techniques are presented in detail and include model order selection and non-convex optimization. An empirical study is conducted to determine which model selection rule, from several approaches found in the literature, is most accurate. Global maximization of the non-convex likelihood equation is carried out using a transformation method known as a filled function. Computer simulations show that our proposed estimator can potentially lead to more accurate estimates of firing rates, as opposed to a Poisson scheme, when the data is affected by a refractory period. Results demonstrate that the error is relatively constant across datasets influenced by a range of refractory periods, indicating the estimator is robust. Rate estimates on real neural data taken from various cortices also show improved goodness of fit when contrasted with results from the Poisson estimator. A brief performance comparison with other popular estimation schemes suggests superior estimates are produced by our proposed scheme.Un processus de point pour modeler des séquences de piques neuraux permet l'application des techniques d'estimation classiques dans leur analyse. L'estimation du taux variable de temps auquel les piques ont lieu est souvent faite afin de trouver l'inférence sur le stimulus qui déclenche la réaction. Ces schémas d'estimation sont souvent basés sur la suppositionque la fréquence de piques élevés suit les statistiques Poisson. Cependant, le taux depiques est un produit du stimulus et des propriétés biophysiques du neurone. Un modèle de processus de point pour les données neuraux doit intégrer la dépendance du stimulus etdes propriétés intrinsèques de la cellule. À cet effet, on modifie le modèle Poisson pour qu'il inclue le phénomène réfractaire observé dans le comportement piquant. Selon ce modèle ajusté, on présente la technique d'estimation Maximum de Vraisemblance (MV) pour letaux de tir qui provoque la réaction piquante. On propose et justifie un modèle paramétrique pour représenter des taux de tir arbitraireset extensifs. L'équation de vraisemblance correspondante pour les paramètres detaux de tir se produit quand une séquence piquante est dérivée. Néanmoins, plusieurs méthodes numériques sont requises pour trouver l'estimation du MV. Ces techniques sont présentées en détail et incluent la sélection d'ordre modèle et l'optimisation non convexe. Une étude empirique, menée afin de déterminer quelle règle de sélection de modèle etinspirée de plusieurs approches trouvées dans la littérature, est la plus exacte. La maximisation globale de l'équation de vraisemblance non convexe est menée en se servant d'une méthode de transformation qui est connue comme une fonction de remplissage. Des simulations informatiques montrent que notre estimateur proposé livre des estimations de taux de tir plus exactes qu'un schéma semblable de Poisson quand les données sont affectées par une période réfractaire. Les résultats démontrent que l'erreur est relativement constante à travers les ensembles de données influencés par plusieurs périodes réfractaires,ce qui indique un estimateur robuste. Les estimations de taux de tir sur des réelles données prises de plusieurs cortex montrent aussi une bonté de convenance (goodness of fit)lorsqu'elles sont contrastées avec les résultats de l'estimateur Poisson. Une comparaison de performance avec d'autres schémas d'estimation populaires suggère que des estimations supérieures sont produites par notre schéma proposé.
10
Mustapha, Azhar K. 1975. "Postfiltering techniques in low bit-rate speech coders." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/80589.
Повний текст джерелаАнотація:
Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1999.Includes bibliographical references (leaves 78-80).
by Azhar K. Mustapha.
M.Eng.
11
Melchor, Rodríguez Angel. "Contributions to heart rate variability and respiratory rate analysis through video imaging techniques." Doctoral thesis, Universitat Politècnica de Catalunya, 2019. http://hdl.handle.net/10803/665983.
Повний текст джерелаАнотація:
The present doctoral thesis proposes a series of methods that have as a general objective the non-contact evaluation of heart rate variability (HRV) and respiratory rate (BR) through video imaging. The proposal of this technique has emerged in the last few years as an alternative to the traditional measurement systems, which assess these and other physiological parameters through direct contact with the person’s body. Due to this condition, the traditional systems may cause some complications in people who present a sensitive or fragile skin, such as neonates or patients with burn injuries.
Furthermore, although the video imaging technique could be an excellent alternative, as in the cases mentioned above, it also aims at being a monitoring instrument for the general population in non-clinical environments. In fact, nowadays, the use of electronic devices such as the video cameras, smartphones, tablets and others, it starts being part of a healthy lifestyle. Thus, this promising technique, which could provide advantages such as the contactless measurement, portability, easy use and low-cost, it could be employed in the near future as part of the evaluation of the person’s health status in everyday life.
On the other hand, despite the aforementioned advantages, the measurements obtained by this technique may be greatly affected by factors such as the movement of the person, lighting conditions, camera settings, among others. Hence, an analysis of the influence of various factors and conditions is carried out in this research study in order to obtain a better insight of the scope and limitations of the technique. For this purpose, a series of methods were developed and implemented in which face detection and tracking algorithms are employed, as well as image and signal processing techniques.
The results obtained in each study are evaluated by using various statistical parameters and plots with the aim of measuring the agreement between the proposed methods and the reference systems. In general, the statistical analysis carried out shows a good level of agreement between the measurement systems. It is important to note the presence of an impact on the results, to a greater or lesser extent, by the factors and conditions analyzed in the different studies. In several cases, the results show a significant improvement in comparison with the data reported in related studies. By contrast, the results achieved in scenarios with a greater presence of artifacts show a decrease in the agreement of the measurements.
This contactless technique may eventually become an instrument to detect physical or psychological disorders in the future. Nevertheless, its use for this purpose will depend on the progress of the technique over the coming years, since it is still in the research and development phase. Therefore, more improvements are necessary to reach the reliability achieved by the current reference systems and, particularly, if its application in real-life scenarios is considered. The development of more robust algorithms is required in order to suppress, as much as possible, the contribution of artifacts present in a real environment. Consequently, the acquisition of measurements in several real-life scenarios, longer recordings, and the analysis of more factors that could influence the performance of the technique constitute some objectives for future work.En la presente tesis doctoral se proponen una serie de métodos los cuales tienen como objetivo general la evaluación sin contacto de la variabilidad de la frecuencia cardíaca y la frecuencia respiratoria mediante imagen de video. La propuesta de esta técnica ha surgido en los últimos años como una alternativa a los sistemas de medida tradicionales, los cuales evalúan estos y otros parámetros fisiológicos a través de contacto directo con el cuerpo de la persona. Debido a esta condición, los sistemas tradicionales podrían ocasionar algunas complicaciones en personas que presentan una piel sensible o frágil, tal como los recién nacidos o pacientes con lesiones por quemaduras. Además, aunque la técnica de imagen de video podría ser una excelente alternativa, como en los casos mencionados previamente, ésta también tiene como objetivo ser un instrumento de monitorización para la población en general en entornos no clínicos. De hecho, hoy en día, el uso de dispositivos electrónicos tales como las cámaras de video, teléfonos inteligentes, tabletas y otros, empieza a ser parte del seguimiento de un estilo de vida saludable. Así, esta prometedora técnica, la cual podría proporcionar ventajas tales como la medición sin contacto, portabilidad, fácil uso y bajo costo, podría ser utilizada en un futuro cercano como parte de la evaluación del estado de salud de una persona en la vida cotidiana. Por otra parte, a pesar de las ventajas mencionadas, las mediciones adquiridas mediante esta técnica pueden ser afectadas en gran medida por factores tales como el movimiento de la persona, las condiciones de iluminación, las ajustes de la cámara, entre otros. Por tanto, en este trabajo de investigación se lleva a cabo un análisis de la influencia de varios factores y condiciones para obtener una mejor comprensión del alcance y las limitaciones de la técnica. Para este propósito, se han desarrollado e implementado una serie de métodos en los cuales se aplicaron algoritmos de detección facial y seguimiento, así como también técnicas de procesamiento de imágenes y señales. Los resultados obtenidos en cada estudio son evaluados a través de distintos parámetros estadísticos y gráficos con el objetivo de medir el acuerdo entre los métodos propuestos y los sistemas de referencia. En general, el análisis estadístico llevado a cabo muestra un buen nivel de concordancia entre los sistemas de medida. Es importante tener en cuenta la presencia de un impacto en los resultados, en mayor o menor medida, por los factores y condiciones analizados en los distintos estudios. En varios casos, los resultados muestran una mejoría significativa en comparación con los datos reportados en estudios relacionados. Por el contrario, los resultados adquiridos en escenarios con una mayor presencia de artefactos muestran una disminución en el acuerdo de las medidas. Esta técnica sin contacto podría eventualmente convertirse en un instrumento para detectar trastornos físicos o psicológicos en el futuro. No obstante, su uso para este objetivo dependerá del progreso de la técnica en los próximos años, ya que ésta se encuentra aún en fase de investigación y desarrollo. Por lo tanto, mayores mejoras son necesarias para alcanzar la fiabilidad que se consigue con los sistemas de referencia actuales y, particularmente, si se plantea su aplicación en escenarios reales. El desarrollo de algoritmos más robustos es requerido a fin de suprimir, tanto como sea posible, la contribución de artefactos presentes en un entorno real. Por consiguiente, la adquisición de medidas en varios escenarios de la vida real, registros de más larga duración, y el análisis de una mayor cantidad de factores que podrían influir al desempeño de la técnica constituyen algunos de los objetivos para trabajo futuro
12
Smith, Tristan. "Predicting Emergency Room Readmission Rates Using Data Mining Techniques." Bowling Green State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1587485194751687.
Повний текст джерела
13
Liu, Sam J. "Low bit-rate image and video compression using adaptive segmentation and quantization." Diss., Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/14850.
Повний текст джерела
14
Luo, Tao. "Interference suppression techniques for multi-rate CDMA communication systems." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ58958.pdf.
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15
Ong, Lay Teen. "Rate and power adaption techniques for wireless communication systems." Thesis, Cardiff University, 2007. http://orca.cf.ac.uk/54577/.
Повний текст джерелаАнотація:
Attaining the most spectrally efficient form of data transmission over a time- varying channel remains as fundamentally important target in wireless systems. Link adaptation (LA) is a promising approach to increase spectral efficiency. In general, the transmitter adjusts its parameter such as rate, power and coding in accordance with the channel state information (CSI) fed back from the receiver. Consequently, the accuracy of the CSI is prevalent in LA design. In this thesis, an investigation of the performance of a variable rate variable power (VRVP) multi-level quadrature amplitude modulation (MQAM) scheme is performed for a single antenna system. Then, a novel VRVP-MQAM system is proposed that employs a rate and power adaptation algorithm based on the statistical characterization of CSI imperfection. Instead of using the conventional signal-to-noise ratio (SNR) estimate as a CSI parameter, the proposed system is based on both an SNR estimate and a bit error rate (BER) estimate, as BER is a more direct representation for quality of service (QoS) of a communication system. The pro posed rate and power adaptation algorithm is then generalized to incorporate a pilot symbol assisted modulation (PSAM) based channel predictor. The BER and SNR estimates are then employed within a code division multiple access (CDMA) based rate and power adaptation system. Finally, the performances of the pro posed systems are shown to achieve higher spectral efficiency when compared to the alternative systems derived based on conventional approach. Another requirement in today's wireless digital communication systems is to provide services for integrated voice and data traffic. The QoS requirement for voice and data can be application specific. For example, real-time traffic is delay-constrained, whereas non-real time traffic has a relaxed requirement on delay but may be capacity-constrained. With this motivation, a rate and power adaptation technique is proposed for a multiple-input multiple-output (MIMO) based integrated voice and data service. On the basis of analytical and simulation results, the performance of the proposed scheme is assessed for a Rayleigh fading environment. Finally, the results demonstrated that the MIMO based system is suitable for integrate voice and data traffic with different requirements and specification.
16
Edirisinghe, Sumuda G. "Dispersion compensation techniques in high bit rate transmission systems." Thesis, University of Essex, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343578.
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Willis, C. A. "Continuous mass flow rate and velocity measurements of pneumatically conveyed powder." Thesis, Nottingham Trent University, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.354922.
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Park, Samuel M. "A Comparison of Machine Learning Techniques to Predict University Rates." University of Toledo / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1564790014887692.
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Wang, Junfang. "Efficient Positioning Technique for Multi-Interface Multi-Rate Wireless Mesh Networks." University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1289937715.
Повний текст джерела
20
Arias, Moran Cesar Augusto. "Spatio-temporal analysis of Texas shoreline changes using GIS technique." Thesis, Texas A&M University, 2003. http://hdl.handle.net/1969.1/408.
Повний текст джерелаАнотація:
One of the most important aspects of coastal management and planning programs that needs to be investigated is shoreline dynamics. Long-term coastal analysis uses historical data to identify the sectors along the coast where the shoreline position has changed. Among the information that can be obtained from these studies are the general trend of coasts, either advancing or retreating. The erosion or accretion rates at each location can be used to forecast future shoreline positions. The current techniques used to study shoreline evolution are generally based on transects perpendicular to a baseline at selected points. But these techniques proved to be less efficient along more complex shorelines, and need to be refined. A new and more reliable method, the topologically constrained transect method (TCTM), was developed for this study and tested using data available for three sectors of the Texas Gulf Coast. Output data generated from TCTM also allowed performing shoreline evolution analysis and forecasting based on historical positions. Using topological constrained transects, this study provides a new method to estimate total areas of accretion or erosion at each segment of the coastline. Reliable estimates of future gains or losses of land along the coast will be extremely useful for planning and management decisions, especially those related to infrastructure and environmental impacts, and in the development of coastal models. Especially important is the potential to quickly identify areas of significant change, which eliminates the need for preliminary random sample surveying, and concentrate higher-resolution analyses in the most significant places. The results obtained in this research using the new methodology show that the Texas coast generally experiences erosion, with anthropogenic factors responsible for accretion. Accretion areas are located near coastal infrastructure, especially jetties that block the along shore sediment transport. The maximum erosion rate obtained in the study area is 5.48 m/year. This value helps make us aware of the powerful dynamic of the sector.
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Prathipati, Rajesh Babu. "Energy efficient scheduling techniques for real-time embedded systems." Thesis, Texas A&M University, 2003. http://hdl.handle.net/1969.1/194.
Повний текст джерелаАнотація:
Battery-powered portable embedded systems have been widely used in many applications. These embedded systems have to concurrently perform a multitude of complex tasks under stringent time constraints. As these systems become more complex and incorporate more functionality, they became more power-hungry. Thus, reducing power consumption and extending battery lifespan while guaranteeing the timing constraints has became a critical aspect in designing such systems. This gives rise to three aspects of research: (i) Guaranteeing the execution of the hard real-time tasks by their deadlines, (ii) Determining the minimum voltage under which each task can be executed, and (iii) Techniques to take advantage of run-time variations in the execution times of tasks. In this research, we present techniques that address the above aspects in single and multi processor embedded systems. We study the performance of the proposed techniques on various benchmarks in terms of energy savings.
22
Esmaeili, Ali. "Advanced control techniques for the heart rate during treadmill exercise." Doctoral thesis, Universitat Autònoma de Barcelona, 2019. http://hdl.handle.net/10803/669563.
Повний текст джерелаАнотація:
L’objectiu d’aquest treball és el disseny d’un controlador de velocitat per a una cinta de córrer de manera que la freqüència cardíaca d’una persona que corre sobre ella segueixi un perfil determinat, potencialment variable en el temps, preespecificado pels metges per a la recuperació cardíaca de la persona. Inicialment es considera el model matemàtic que relaciona la velocitat de la cinta de córrer amb la freqüència cardíaca de la persona. Un dels aspectes importants del model és la determinació dels seus paràmetres. En aquest sentit, en primer lloc es tracta el problema de l’estimació paramètrica, que es formula com un problema d’optimització que és resolt amb una tècnica heurística coneguda com Particle Swarm Optimization (PSO). Aquesta és la primera vegada que aquesta tècnica s’utilitza en l’estimació de models cardíacs i és una de les contribucions de la tesi. A continuació, es dissenya un controlador en mode lliscant de tipus super-Twisting per dur a terme el control robust de la cinta en presència d’incertesa paramètrica i dinàmica no modelada. Els experiments numèrics duts a terme mostren que el algoritmes estimació emprat és capaç d’obtenir valors molt precisos per als paràmetres del sistema i que l’enfocament de control utilitzat obté un error de seguiment nul asimptòticament, aconseguint els objectius del control. En tots dos casos, la velocitat de la cinta es troba en el rang dels 2-4 km \/ h, rang que no s’ha utilitzat anteriorment en els treballs previs. Finalment, en l’última part d’aquest treball, es dissenya un controlador robust en temps discret. Inicialment es dissenya un controlador de tipus linealització per realimentació, però es mostra que la seva robustesa és pobre. Per resoldre aquest problema es proposa un altre mètode basat en l’estimació simultània estat-paràmetres. Tot i que els resultats obtinguts són prometedors, l’enfocament presenta algunes problemes com la no identificació dels paràmetres i la generació d’algunes oscil·lacions no a la sortida. Atès que l’aproximació del control lliscant amb super-Twisting ha proporcionat un gran resultat en temps continu, es proposa un controlador lliscant amb super-Twisting en el cas discret. Per a això, inicialment es dissenya un control lliscant per al sistema linealitzat i discretitzat. Es dissenya un control lliscant amb observador i el senyal de control es reconstrueix per mitjà d’un retenidor d’ordre zero (ZOH). No obstant això, el sistema és intrínsecament nolineal, de manera que s’estén el disseny al sistema nolineal discretitzat, per al qual s’aplica el controlador amb super-Twisting. El controlador proposat és capaç d’aconseguir un seguiment de la trajectòria excel·lent sense la presència de chattering i sense la necessitat d’un observador d’estat, el que és una de les contribucions de la tesi. En aquest cas també, la velocitat de la cinta es troba en el rang dels 2-4 km \/ h, rang que no s’ha utilitzat anteriorment en els treballs previs.El objetivo de este trabajo es el diseño de un controlador de velocidad para una cinta de correr de tal forma que la frecuencia cardíaca de una persona que corre sobre ella siga un perfil determinado, potencialmente variable en el tiempo, preespecificado por los médicos para la recuperación cardíaca de la persona. Inicialmente se considera el modelo matemático que relaciona la velocidad de la cinta de correr con la frecuencia cardíaca de la persona. Uno de los aspectos importantes del modelo es la determinación de sus parámetros. En este sentido, en primer lugar se trata el problema de la estimación paramétrica, que se formula como un problema de optimización que es resuelto con una técnica heurística conocida como Particle Swarm Optimization (PSO). Esta es la primera vez que esta técnica se utiliza en la estimación de modelos cardíacos y es una de las contribuciones de la tesis. A continuación, se diseña un controlador en modo deslizante de tipo super-twisting para llevar a cabo el control robusto de la cinta en presencia de incertidumbre paramétrica y dinámica no modelada. Los experimentos numéricos llevados a cabo muestran que el algoritmos estimación empleado es capaz de obtener valores muy precisos para los parámetros del sistema y que el enfoque de control utilizado obtiene un error de seguimiento nulo asintóticamente, consiguiendo los objetivos del control. En ambos casos, la velocidad de la cinta se encuentra en el rango de los 2-4 km\/h, rango que no se ha utilizado anteriormente en los trabajos previos. Finalmente, en la última parte de este trabajo, se diseña un controlador robusto en tiempo discreto. Inicialmente se diseña un controlador de tipo linealización por realimentación, pero se muestra que su robustez es pobre. Para resolver este problema se propone otro método basado en la estimación simultánea estado-parámetros. Aunque los resultados obtenidos son prometedores, el enfoque presenta algunas problemas como la no identificación de los parámetros y la generación de algunas oscilaciones no en la salida. Dado que la aproximación del control deslizante con super-twisting ha proporcionado un gran resultado en tiempo continuo, se propone un controlador deslizante con super-twisting en el caso discreto. Para ello, inicialmente se diseña un control deslizante para el sistema linealizado y discretizado. Se diseña un control deslizante con observador y la señal de control se reconstruye por medio de un retenedor de orden cero (ZOH). No obstante, el sistema es intrínsecamente nolineal, por lo que se extiende el diseño al sistema nolineal discretizado, para el que se aplica el controlador con super-twisting. El controlador propuesto es capaz de lograr un seguimiento de la trayectoria excelente sin la presencia de chattering y sin la necesidad de un observador de estado, lo que es una de las contribuciones de la tesis. En este caso también, la velocidad de la cinta se encuentra en el rango de los 2-4 km\/h, rango que no se ha utilizado anteriormente en los trabajos previos.
The objective of this work is to design a heart rate (HR) controller for a treadmill so that the HR of an individual running on it tracks a pre-specied, potentially time-varying profile specified by doctors for the cardiac recovery of the person. Initially, we consider a mathematical model relating the relationship between the speed of the treadmill and HR of the person running on it. An important issue in this model is the determination of its parameters. Thus, we first tackle the parameter estimation problem in this model which is formulated as an optimization one, that is solved through a heuristic technique known as Particle Swarm Optimization. This is the first time that this technique is used for the estimation of cardiac models and is a contribution of the thesis. Afterward, a super- twisting sliding mode controller is designed to perform the robust control of treadmill’s speed in the presence of potential unmodelled dynamics and parametric uncertainties. Numerical examples show that the estimation procedure is able to obtain accurate values for the system’s parameters while the proposed control approach is able to obtain zero tracking error without chattering, definitely achieving the control objectives. In both cases, the range of treadmill’s speed goesfrom 2 to 14 km\/h, range that is not usually employed in previous studies. Finally, in the last part of this work, the objective is to design a discrete-time robust controller. Initially, a feedback linearization-based controller is designed, but it has poor robustness properties. In order to solve this problem, we propose another method consisting in the Joint parameter-state estimation based-control. However, this approach does not identify the parameters and it offers some oscillations. To solve all of these problems and regarding the previous Chapter, we used the discrete-time sliding mode controller method to complete our study. In the first part of this Section, as designing a nonlinear model directly is hard, we decided to linearize the model and then discretize it. Furthermore, the continuous control is generated by a zero-order hold (ZOH). On the other hand, since the nonlinear relationship describes a better relation between HR and speed, a nonlinear model is used in the last part of this thesis. The final and best controller is a discrete-time super-twisting system that avoids chattering and achieves very good robustness and tracking in the system. The great systematic procedure to design of the controller, the perfect tracking and the avoidance of using an observer for this system are other advantages of this approach. The simulation results in this work that presented in the speed range of 2-14 km, a range that is not usually employed in previous studies to the control of the heart rate during treadmill exercise.
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Samingan, Ahmad Kamsani. "Minimum bit error rate multiuser detection techniques for DS-CDMA." Thesis, University of Southampton, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.398594.
Повний текст джерела
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Mehalic, Charles J. "Multiparameter forecasting techniques for the Marine Corps officer rate generator." Thesis, Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA241453.
Повний текст джерелаАнотація:
Thesis (M.S. in Operations Research)--Naval Postgraduate School, September 1990.Thesis Advisor(s): Read, Robert R. Second Reader: Whitaker, Lyn R. "September 1990." Description based on title screen as viewed on March 19, 2010. DTIC Identifier(s): Forecast, Seasonality, Attrition Estimation, Harrison, Winters, Bayesian, Expotential Smoothing, Shrinkage, Aggregation. Author(s) subject terms: Forecast, Attrition Estimation, Harrison, Winters, Bayesian, Seasonality, Expotential smoothing, Shrinkage, Aggregation. Includes bibliographical references (p. 100-101). Also available in print.
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Liga, G. "Digital techniques for ultra-high data rate optical fibre transmission." Thesis, University College London (University of London), 2017. http://discovery.ucl.ac.uk/1570380/.
Повний текст джерелаАнотація:
The exponential growth of the demand for higher data rates is pushing scientists to find ways to improve the internet infrastructure, which crucially relies on optical fibres. The main obstacle to increasing transmission rates of optical fibre systems is presented by the fibre Kerr nonlinear effect, which impairs signal transmission as the transmitted power is increased. Fortunately, optical coherent detection, in combination with digital signal processing techniques, have enabled more sophisticated digital receivers, tailored to the optical fibre channel. This thesis describes a comprehensive study on the performance of two digital receiver-side techniques: digital back-propagation (DBP) and maximum likelihood sequence detection (MLSD). DBP is the most widespread digital technique to mitigate fibre nonlinearity at the receiver. The performance of DBP, is assessed for long-haul, wide-bandwidth systems, highlighting theoretical gains and practical limitations. Analytical models to predict DBP performance are discussed and compared to numerical results. The impact of polarisation-mode dispersion on the capability of DBP to remove nonlinear impairments is investigated. The principles of detection theory are discussed in the context of the optical fibre nonlinear channel. Following such principles, MLSD strategies are studied and their performance analysed for unrepeatered systems. A close to optimum receiver scheme, using the Viterbi algorithm, is proposed and investigated for the first time in a singlespan fibre system. Finally, information-theoretic tools are used to predict achievable information rates of both receiver schemes, when employed in combination with forward error correction codes. In particular, pragmatic coded modulation schemes were examined to assess the potential of off-the-shelf channel codes. Both receiving strategies analysed were demonstrated to significantly outperform conventional receivers optimised for the additive white Gaussian noise channel. The results of this thesis provide a useful insight on the properties of the optical fibre channel and on the design of receivers aiming to maximise information rates through it.
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Majidi, Rabeeh. "DIGITALLY ASSISTED TECHNIQUES FOR NYQUIST RATE ANALOG-to-DIGITAL CONVERTERS." Digital WPI, 2015. https://digitalcommons.wpi.edu/etd-dissertations/275.
Повний текст джерелаАнотація:
With the advance of technology and rapid growth of digital systems, low power high speed analog-to-digital converters with great accuracy are in demand. To achieve high effective number of bits Analog-to-Digital Converter(ADC) calibration as a time consuming process is a potential bottleneck for designs. This dissertation presentsa fully digital background calibration algorithm for a 7-bit redundant flash ADC using split structure and look-up table based correction. Redundant comparators are used in the flash ADC design of this work in order to tolerate large offset voltages while minimizing signal input capacitance. The split ADC structure helps by eliminating the unknown input signal from the calibration path. The flash ADC has been designed in 180nm IBM CMOS technology and fabricated through MOSIS. This work was supported by Analog Devices, Wilmington,MA. While much research on ADC design has concentrated on increasing resolution and sample rate, there are many applications (e.g. biomedical devices and sensor networks) that do not require high performance but do require low power energy efficient ADCs. This dissertation also explores on design of a low quiescent current 100kSps Successive Approximation (SAR) ADC that has been used as an error detection ADC for an automotive application in 350nm CD (CMOS-DMOS) technology. This work was supported by ON Semiconductor Corp, East Greenwich,RI.
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Irvine, James Moir. "Delta modulation techniques for low bit-rate digital speech encoding." Master's thesis, University of Cape Town, 1985. http://hdl.handle.net/11427/7587.
Повний текст джерелаАнотація:
Includes bibliography.Two new hybrid companding delta modulators for speech encoding are presented here. These modulators differ from the Hybrid Companding Delta Modulator (HCDM) proposed by Un et al in that the two new encoders employ Song Voice Adaptation as the basis of the instantaneous compandor, rather than Constant Factor adaptation. A detailed analysis of the performance, both objective and subjective, of these hybrid codecs has been carried out. Results show that overall the two codecs developed as part of this project are better than the HCDM codec. In addition the new codecs offer simpler implementation in digital hardware than the HCDM. A Computer Aided Test (CAT) system has been developed to simplify the design and test processes for speech codecs.
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Siviour, Clive Richard. "High strain rate properties of materials using Hopkinson bar techniques." Thesis, University of Cambridge, 2005. https://www.repository.cam.ac.uk/handle/1810/265474.
Повний текст джерелаАнотація:
This dissertation examines the high strain rate mechanical properties of polymers, polymer bonded explosives and solders. In addition, it examines experimental developments that will allow more detailed investigation of these properties in the future. The split Hopkinson pressure bar is a standard apparatus used to measure the mechanical strength of materials at strain rates between 500 and 10,000 s- 1 � Measurements are performed by dynamically loading a small cylindrical specimen between two rods that are instrumented with strain gauges. The data from these strain gauges are used to calculate stress and strain in the specimen as functions of time. Chapter two contains an account of the Hopkinson bar system and its application. The advantages and limitations of the system are presented and discussed. Once of these limitations, the time taken for the specimen to reach mechanical equilibrium, is examined in detail in chapter three. In chapter four the variation of strength with strain rate of two polymers, polycarbonate and polyvinyladine difluoride, is investigated. It is shown that at high stain rates their mechanical strength is increased by freezing out of low order molecular relaxations. Chapter five presents data from measurements made on polymer-bonded explosives. The effect of crystal size on the mechanical properties of the mixture is examined, and it is shown that the strength of the material varies as the inverse square root of crystal spacing. In chapter six measurements of the high strain rate properties of different solder materials are presented. These measurements were made to provide high quality experimental results for the development of material models for solder at high strain rates. Chapter seven presents results from the application of speckle metrology, a wellestablished technique for making optical measurements of displacements, to the Hopkinson bar system. Along with a line laser device for measuring specimen radius this allowed accurate measurements of the Poisson's ratio of Hopkinson bar specimens. In addition, speckle enabled a high rate Brazilian test with measurements of tensile strain. Finally, data are presented on the deformation of PBS9501, a polymer bonded explosive stimulant. The evolution of damage in the material is investigated using both the speckle and line laser techniques.
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Chun, Yang, Yang Hongling, and Zhou Jie. "STUDY ON HIGH-RATE TELEMETRY DATA REAL-TIME PROCESSING TECHNIQUES." International Foundation for Telemetering, 2000. http://hdl.handle.net/10150/608251.
Повний текст джерелаАнотація:
International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, CaliforniaOwing to rapid development of PC industry, personal computer has been surprisingly improved on reliability and speed and it has been applied to many fields, such as aerospace, satellite and telemetry applications. As we all known, two aspects decide how fast the PC-based data acquisition can be reached. One aspect is CPU processing and the other is I/O bandwidth. Indeed, the first aspect has changed increasingly insignificant because the frequency of CPU has exceeded 700MHz which can satisfy fully the need of high rate data processing. So I/O bandwidth is the only key factor of the high rate PC-based data acquisition and we must adopt efficient data buffer techniques to satisfy the demand of telemetry data entry. This paper presents a buffered data channel which use memory mapping, EPLD and Dual-Port SRAM techniques. The operation platform of this design is WINDOWS95/98 and the software includes device driver and real-time processing routines.
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鄧世健 and Sai-kin Owen Tang. "Implementation of Low bit-rate image codec." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1994. http://hub.hku.hk/bib/B31212670.
Повний текст джерела
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Gouvianakis, Nikolaos. "Speech coding at medium bit rates using analysis by synthesis techniques." Thesis, Loughborough University, 1989. https://dspace.lboro.ac.uk/2134/27741.
Повний текст джерела
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Bharadhwaj, Harsha. "Study and Realisation of Nyquist Rate Filters in Voltage Inverter Switch Technique." Thesis, Linköping University, Department of Electrical Engineering, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-6331.
Повний текст джерелаАнотація:
Low-sensitivity switched capacitor filters imitating 'R','L' and 'C' can be built by means of capacitances, ordinary switches and voltage inverter switches (VIS). These structures carry the inherent bilinear transformation of their doubly resistively terminated ladder reference filters. This one to one correspondence between the 's-domain' and the 'z-domain' results in the Nyquist criterion being the only limitation on the sampling frequency. This eliminates the necessity for oversampling and VIS filters can be designed for high operating rates.
Filters based on VIS principle were analysed in previous literatures in the 'phi-domain'. In this thesis work, a successful attempt has been made to formulate an analysis procedure for discrete-time filters based on VIS principle in the 'z-domain'. Significant details have been brought out in comparison with the respective reference filter. A fifth-order lowpass filter has been designed and implemented to exhibit the closeness to the bilinearly transformed continuous-time reference filter. Settling time analysis has been done to justify the need for filters using VIS principle as compared to the filters employing integrator based switched capacitor filter. It is shown that VIS filter can be made to settle within half the period required for a conventional integrator based switched capacitor filter.
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Vutukuru, Naresh Kumar Reddy. "Apparent dissolution rate enhancement of poorly-water soluble drugs by adsorption technique." Scholarly Commons, 2015. https://scholarlycommons.pacific.edu/uop_etds/269.
Повний текст джерелаАнотація:
Nearly 70% of the new chemical entities (NCE’s) discovered are poorly-water soluble drugs and the number of poorly-water soluble drugs are increasing rapidly in the drug discovery. Most of the NCE’s are lipophilic and have dissolution rate issues. Low dissolution rate of the drugs result in poor bioavailability. To overcome poor bioavailability, an adsorption technique is developed to enhance the apparent dissolution rate of poorly-water soluble drugs. In this study, two poor-water soluble model drugs, ibuprofen and carvedilol were used. Methanol, DMF, DMSO and PEG400 were used as solvents and microcrystalline cellulose was used as an adsorbent. Pure model drugs, physical mixtures and prepared composites were characterized by using FTIR, DSC, XRD and dissolution testing. Results showed that the composites prepared with solvents DMF, DMSO and PEG400 showed enhancement in dissolution rates of two model drugs. Characterization of the composites prepared by using non-volatile solvents showed successful conversion of crystalline model drugs into solution state. Whereas, composites prepared by using volatile solvent showed similar results like physical mixtures and pure drug. Ibuprofen composites containing DMF, DMSO and PEG400 showed 9.4, 7.4 and 1.8 folds of increase in apparent dissolution rate, respectively. Whereas carvedilol composites containing DMF and DMSO showed 11.52 and 3.4 folds of increase in apparent dissolution rate. Four months of stability study were conducted on prepared composites at both 40°C and room temperature. It was observed that prepared composites were stable after 4 months and exhibited similar dissolution rate. In conclusion, the use of non-volatile solvents disrupted the crystal structure but also retained the drug in solution state which in turn enhanced the apparent dissolution rate of model drugs used. From the observed results we conclude that this method has a potential to replace existing techniques to enhance the apparent dissolution rate of the drug and stability of the composites.
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Acharya, Subrata. "A dynamic slack management technique for real-time distributed embedded systems." Thesis, Texas A&M University, 2004. http://hdl.handle.net/1969.1/3173.
Повний текст джерелаАнотація:
This work presents a novel slack management technique, the Service Rate Based Slack Distribution Technique, for dynamic real-time distributed embedded systems targeting the reduction and management of energy consumption. Energy minimization is critical for devices such as laptop computers, PCS telephones, PDAs and other mobile and embedded computing systems simply because it leads to extended battery lifetime. Such systems being power hungry rely greatly upon the system design and algorithms for processing, slack and power management. This work presents an effcient dynamic slack management scheme for an energy aware design of such systems. The proposed Service Rate Based Slack Distribution Technique has been considered with two static(FCFS, WRR) and two dynamic(EDF, RBS) scheduling schemes used most commonly in distributed systems. A fault tolerance mechanism has also been incorporated into the proposed technique inorder to use the available dynamic slack to maintain checkpoints and provide for rollbacks on faults. Results show that in comparion to contemporary techniques, the proposed Service Rate Based Slack Distribution Technique provides for about 29% more perfor-mance/overhead savings when validated with real world and random benchmarks.
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Gupta, P., and V. B. Gadicha. "Enhancement of low quality degraded video using haar wavelet decomposition technique." Thesis, Sumy State University, 2017. http://essuir.sumdu.edu.ua/handle/123456789/55756.
Повний текст джерелаАнотація:
The point recommends the general system for
video improvement, object location and following continue
at the same time in an aggressive and helpful way .Video is a
gathering of successive pictures with a consistent time
interim. So video can give more data about the article when
situations are changing regarding time. Thusly, physically
taking care of recordings are entirely unimaginable. So
there is need of a computerized gadget to handle these
recordings. Numerous calculations and innovation have
been created to robotize video improvement and checking
the article in a video document. Video improvement with
item identification and following is a one of the testing
errand in PC vision. Additionally, following of an article
essentially includes two going before steps object
identification and item representation. Object discovery is
performed to check presence of items in video and to
correctly find that article .Object following is a procedure of
dividing a district of enthusiasm from a video scene and
monitoring its movement, position and impediment. The
following is performed by observing articles' spatial and
transient changes amid a video grouping, including its
nearness, position, size, shape, and so forth. Video
improvement with article following is utilized as a part of a
few applications, for example, video reconnaissance, robot
vision, movement observing.
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Solliec, Laurent. "Real time flow rate modelling in disturbed conditions from velocity profilers." Thesis, Strasbourg, 2013. http://www.theses.fr/2013STRAD052.
Повний текст джерелаАнотація:
L'installation de systèmes de mesure est d'une utilisation cruciale pour la gestion des réseaux d'assainissement ou des canaux d 'irrigation. La plupart des structures gouvernementales ou privées ainsi que les agglomérations s'équipent de systèmes de mesure de débit afin de se conformer avec la législation européenne. La plupart des débitmètres fournissent des données en temps réel i.e. l'information est transmise en permanence. aux centrales d'acquisition pour une gestion de l'architecture du système de canaux. La mesure en canaux ouverts est souvent ultrasonore. L'objectif de cette thèse est de proposer une méthode en temps réel afin de corréler les vitesses locales en une vitesse moyenne dans les conditions observables par les utilisateurs en canaux ouverts. Les thématiques impliquées à cette étude sont multiples: les techniques de mesure, l'hydrodynamique en canaux ouverts représentée par la turbulence (ici plus particulièrement les courants secondaires), les lois de paroi, le nombre de Froude ... l'ensemble de ces thématiques doit être investi en canaux pleinement développés où les conditions sont stables dans l'espace mais aussi pour des conditions perturbées telles que les structures hétérogènes ou transitoires.La technique de mesure est un point clé: quelle est la technique la plus applicable aux conditions de mesure i.e. les canaux étroits? Les canaux étroits varient très rapidement en tem1es de taux de remplissage : la technique la plus adaptée est le profileur ultrasonique.La compréhension des effets hydrodynamiques est essentielle afin de développer un modèle de conversion. Les canaux droits sont influencés par l'hydrodynamique des écoulements, la géométrie mais aussi et principalement par leurs interactions. En canaux droits, les courants secondaires sont primordiaux même s'ils se traduisent par un effet le plus observable : le dip-phénomène, i.e. la présence d'un maximum de vitesse non pas à la surface d'eau mais en dessous pour les canaux étroits. Ces courants secondaires sont fortement sensibles au rapport d'aspect, la géométrie et la variabilité de la rugosité le long de la paroi, passablement sensible à la rugosité et indépendant du nombre de Froude .Les perturbations, à l'aval desquelles sont installés les débitmètres ultrasonores, sont majoritairement représentées par les coudes et les jonctions. Dans les coudes, les tourbillons sont liés aux forces centrifuges (gros tourbillon) et la turbulence (petit tourbillon). Pour les jonctions, les tourbillons diffèrent des deux précédentes configurations avec la présence à l'aval de la jonction de 3 tourbillons (due à un étirement des tourbillons par l'arrivée latérale). Les capteurs ne sont pas installés directement au niveau de la perturbation mais à l'aval. Dans la littérature, les distances requises pour retrouver des conditions proches de l'écoulement pleinement développé devraient excéder environ 50 hauteurs d'eau. En pratique, ces distances sont plus proches de5-10 fois la largeur du canal ou du tirant d'eau. L'application de modèle basée sur l'écoulement pleinement développé corrélé à un capteur n'est pas recommandableThe installation of flow rate measurement systems is an important factor in regard to the management of sewer and irrigation networks. Most cities and infrastructure succeed in obtaining sufficient flow measurements to satisfy European Regulation rules. Most flow meters comprise real time systems; this means that the information is permanently transferred to a data base for the management and optimization of the particular network. The measurement technology deployed is typically ultrasound based. Within the number of measurement points a high percentage are often deficient and create specific difficulties (>75% of Venturi flumes are inaccurate according to Anglian Water, a UK water and wastewater company). The study presented here focuses on flow meters which calculate discharge using measurement of level, cross sectional area and the correlation of local velocity to generate a mean value. The aim of this thesis is to propose a real time method to enable determination of this “conversion” under realistic configurations which Users find in open channels. The synthesis of measurement points through an understanding of hydraulic conditions (Bonakdari, 2006) provides a method to create flow data allowing local point velocities to be converted into an overall mean value. The approach has limitations and may fail in industrial situations but can be used for very complex configurations. It also requires specialists with knowledge of the technique who are rarely available to Users. What is proposed here is an alternative method to Bonakdari for simpler configurations. The aim is to evaluate the flow rate with acceptable accuracy using these technics and to establish a relationship between local velocities and the mean velocity according to Regulatory requirements (8% are required in UK, 5 to 8% in Germany depending on area). The individual components are here: the measurement techniques; the hydrodynamics represented with the turbulence (secondary currents in open channels); the wall / roughness effects; the Froude number … for fully developed conditions where conditions become stable in space but for disturbed conditions, as well such as heterogeneous structures or transition conditions
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Sanabria, Montañez José Antonio. "A contribution to exchange rate forecasting based on machine learning techniques." Doctoral thesis, Universitat Ramon Llull, 2011. http://hdl.handle.net/10803/48492.
Повний текст джерелаАнотація:
El propòsit d'aquesta tesi és examinar les aportacions a l'estudi de la predicció de la taxa de canvi basada en l'ús de tècniques d'aprenentatge automàtic. Aquestes aportacions es veuen facilitades i millorades per l'ús de variables econòmiques, indicadors tècnics i variables de tipus ‘business and consumer survey’. Aquesta investigació s’organitza entorn d’una recopilació de quatre articles. L'objectiu de cadascun dels quatre treballs de recerca d'aquesta tesi és el de contribuir a l'avanç del coneixement sobre els efectes i mecanismes mitjançant els quals l'ús de variables econòmiques, indicadors tècnics, variables de tipus ‘business and consumer survey’, i la selecció dels paràmetres de models predictius són capaços de millorar les prediccions de la taxa de canvi.
Fent ús d'una tècnica de predicció no lineal, el primer article d'aquesta tesi es centra majoritàriament en l'impacte que tenen l'ús de variables econòmiques i la selecció dels paràmetres dels models en les prediccions de la taxa de canvi per a dos països. L'últim experiment d'aquest primer article fa ús de la taxa de canvi del període anterior i d'indicadors econòmics com a variables d'entrada en els models predictius.
El segon article d'aquesta tesi analitza com la combinació de mitjanes mòbils, variables de tipus ‘business and consumer survey’ i la selecció dels paràmetres dels models milloren les prediccions del canvi per a dos països. A diferència del primer article, aquest segon treball de recerca afegeix mitjanes mòbils i variables de tipus ‘business and consumer survey’ com a variables d'entrada en els models predictius, i descarta l'ús de variables econòmiques. Un dels objectius d'aquest segon article és determinar el possible impacte de les variables de tipus ‘business and consumer survey’ en les taxes de canvi.
El tercer article d'aquesta tesi té els mateixos objectius que el segon, però amb l'excepció que l'anàlisi abasta les taxes de canvi de set països. El quart article de la tesi compta amb els mateixos objectius que l'article anterior, però amb la diferència que fa ús d'un sol indicador tècnic.
En general, l'enfocament d'aquesta tesi pretén examinar diferents alternatives per a millorar les prediccions del tipus de canvi a través de l'ús de màquines de suport vectorial. Una combinació de variables i la selecció dels paràmetres dels models predictius ajudaran a aconseguir aquest propòsit.El propósito de esta tesis es examinar las aportaciones al estudio de la predicción de la tasa de cambio basada en el uso de técnicas de aprendizaje automático. Dichas aportaciones se ven facilitadas y mejoradas por el uso de variables económicas, indicadores técnicos y variables de tipo ‘business and consumer survey’. Esta investigación está organizada en un compendio de cuatro artículos. El objetivo de cada uno de los cuatro trabajos de investigación de esta tesis es el de contribuir al avance del conocimiento sobre los efectos y mecanismos mediante los cuales el uso de variables económicas, indicadores técnicos, variables de tipo ‘business and consumer survey’, y la selección de los parámetros de modelos predictivos son capaces de mejorar las predicciones de la tasa de cambio. Haciendo uso de una técnica de predicción no lineal, el primer artículo de esta tesis se centra mayoritariamente en el impacto que tienen el uso de variables económicas y la selección de los parámetros de los modelos en las predicciones de la tasa de cambio para dos países. El último experimento de este primer artículo hace uso de la tasa de cambio del periodo anterior y de indicadores económicos como variables de entrada en los modelos predictivos. El segundo artículo de esta tesis analiza cómo la combinación de medias móviles, variables de tipo ‘business and consumer survey’ y la selección de los parámetros de los modelos mejoran las predicciones del cambio para dos países. A diferencia del primer artículo, este segundo trabajo de investigación añade medias móviles y variables de tipo ‘business and consumer survey’ como variables de entrada en los modelos predictivos, y descarta el uso de variables económicas. Uno de los objetivos de este segundo artículo es determinar el posible impacto de las variables de tipo ‘business and consumer survey’ en las tasas de cambio. El tercer artículo de esta tesis tiene los mismos objetivos que el segundo, pero con la salvedad de que el análisis abarca las tasas de cambio de siete países. El cuarto artículo de esta tesis cuenta con los mismos objetivos que el artículo anterior, pero con la diferencia de que hace uso de un solo indicador técnico. En general, el enfoque de esta tesis pretende examinar diferentes alternativas para mejorar las predicciones del tipo de cambio a través del uso de máquinas de soporte vectorial. Una combinación de variables y la selección de los parámetros de los modelos predictivos ayudarán a conseguir este propósito.
The purpose of this thesis is to examine the contribution made by machine learning techniques on exchange rate forecasting. Such contributions are facilitated and enhanced by the use of fundamental economic variables, technical indicators and business and consumer survey variables as inputs in the forecasting models selected. This research has been organized in a compendium of four articles. The aim of each of these four articles is to contribute to advance our knowledge on the effects and means by which the use of fundamental economic variables, technical indicators, business and consumer surveys, and a model’s free-parameters selection is capable of improving exchange rate predictions. Through the use of a non-linear forecasting technique, one research paper examines the effect of fundamental economic variables and a model’s parameters selection on exchange rate forecasts, whereas the other three articles concentrate on the effect of technical indicators, a model’s parameters selection and business and consumer surveys variables on exchange rate forecasting. The first paper of this thesis has the objective of examining fundamental economic variables and a forecasting model’s parameters in an effort to understand the possible advantages or disadvantages these variables may bring to the exchange rate predictions in terms of forecasting performance and accuracy. The second paper of this thesis analyses how the combination of moving averages, business and consumer surveys and a forecasting model’s parameters improves exchange rate predictions. Compared to the first paper, this second paper adds moving averages and business and consumer surveys variables as inputs to the forecasting model, and disregards the use of fundamental economic variables. One of the goals of this paper is to determine the possible effects of business and consumer surveys on exchange rates. The third paper of this thesis has the same objectives as the second paper, but its analysis is expanded by taking into account the exchange rates of 7 countries. The fourth paper in this thesis takes a similar approach as the second and third papers, but makes use of a single technical indicator. In general, this thesis focuses on the improvement of exchange rate predictions through the use of support vector machines. A combination of variables and a model’s parameters selection enhances the way to achieve this purpose.
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Kim, Hyun Soo Electrical Engineering & Telecommunications Faculty of Engineering UNSW. "Speech analysis techniques useful for low or variable bit rate coding." Awarded by:University of New South Wales. School of Electrical Engineering and Telecommunications, 2005. http://handle.unsw.edu.au/1959.4/22050.
Повний текст джерелаАнотація:
We investigate, improve and develop speech analysis techniques which can be used to enhance various speech processing systems, especially low bit rate or variable bit rate coding of speech. The coding technique based on the sinusoidal representation of speech is investigated and implemented. Based on this study of the sinusoidal model of speech, improved analysis techniques to determine voicing, pitch and spectral estimation are developed, as well as noise reduction technique. We investigate the properties and limitations of the spectral envelope estimation vocoder (SEEVOC). We generalize, optimize and improve the SEEVOC and also compare it with LP in the presence of noise. The properties and applications of morphological filters for speech analysis are investigated. We introduce and investigate a novel nonlinear spectral envelope estimation method based on morphological operations, which is found to be very robust against noise. This method is also compared with the SEEVOC method. A simple method for the optimum selection of the structuring set size without using prior pitch information is proposed for many purposes. The morphological approach is then used for a new pitch estimation method and for the general sinusoidal analysis of speech or audio. Many of the new methods are based on a novel systematic analysis of the peak features of signals, including the study of higher order peaks. We propose a novel peak feature algorithm, which measure the peak characteristics of speech signal in time domain, to be used for end point detection and segmentation of speech. This nonparametric algorithm is flexible, efficient and very robust in noise. Several simple voicing measures are proposed and used in a new speech classifier. The harmonic-plus-noise decomposition technique is improved and extended to give an alternative to the methods used in the sinusoidal analysis method. Its applications to pitch estimation, speech classification and noise reduction are investigated.
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Gover, Tobin. "Low bit rate imaging coding based on segmentation and vector techniques." Thesis, Imperial College London, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309221.
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Lillie, Andrew G. "Iterative receiver techniques for high data rate indoor wireless communication systems." Thesis, University of Bristol, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.419135.
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Shin, Eun-hee. "An Experimental Study of Techniques to Improve Response Rates of Mail Questionnarie." DigitalCommons@USU, 1992. https://digitalcommons.usu.edu/etd/6012.
Повний текст джерелаАнотація:
The study examined (a) which single technique (cover letter sponsorship, personalization, anonymity, or appeal) is most effective in increasing response rates with mail questionnaires, and (b) which combination of these selected techniques is most effective in increasing such response rates. Questionnaires concerning faculty evaluation were sent to a national sample of professors.
The present study found that identification of a university as the sponsor of the survey resulted in a significantly higher response rate than that obtained when the survey was sponsored by a private research institute. There was a significant increase in response rates when the cover letter was personalized, as opposed to an unpersonalized form letter. There were no significant differences in response rates attributable to (a) wether respondents were assured anonymity, and (b) the type of appeal used in the cover letter (personal or professional appeal). No significant interactions were found among any of the four techniques investigated. It was concluded from this study that judicious selection of the survey sponsor and use of cover letter personalization can improve the response rates of a mail questionnaire significantly, at least with the type of population and questionnaire significantly, at least with the type of population and questionnaire topic used in this study.
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Yang, Peiyu. "Experimental Techniques and Mechanical Behavior of T800/F3900 at Various Strain Rates." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1480601677646997.
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Shah, Tanvir H. "Rapid non-destructive techniques for assessing crop growth rates and nitrogen status." Thesis, University of Aberdeen, 1985. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU356158.
Повний текст джерелаАнотація:
The broad aims of the study were to grow crops under different levels of nitrogen fertilizer, so that a range of crop growth rates and leaf chlorophyll concentrations could be made available for an investigation into the feasibility of monitoring the crop's growth and colour changes, using the spectral properties of the individual leaves and the leaf canopy. The literature concerned with the interaction of radiation with both single leaves and whole canopies was reviewed. In addition a few other promising techniques capable of revealing crop condition non-destructively were also mentioned. Specifically the aims were (a) to develop a robust optical technique for assaying chlorophyll content of plant leaves which would be able to compensate for factors which interfere with the independent absorption of leaf pigments and (b) to quantify leaf pigment concentrations of a crop independently from crop biomass. A standard laboratory spectrophotometer was interfaced to a microcomputer and its cell compartment modified for acquiring reflectance and absorption spectra of intact leaves. For crop canopy reflectance measurements a portable three-channel band-pass radiometer employing wide-band interference filters, silicon photodiode detectors, and integrated sample/hold circuits was designed and constructed. The instrument has the ability to provide simultaneous signal outputs of all three sensors for facilitating the measurement of crop canopy reflectance under conditions of fluctuating incoming radiation, as might occur on cloudy days. In addition to the band-pass radiometer a low cost system employing an inexpensive monochromator for obtaining reflectance spectra of crops in the visible/near-infrared wavelength range was constructed and tested. In this system the rapidly varying analogue output of the monochromator is converted to audio-frequencies for recording on an audio-cassette tape recorder. Demodulation and retrieval of the original monochromator output for computer processing is carried out back in the laboratory. Multiple linear regression of selected features of intact leaf absorption and reflectance spectra and their first order and second order derivatives yielded equations able to compensate for the non-pigment differences of leaves of maize, barley, french dwarf beans, sweet pepper, sunflower, and ornamental tobacco, and accurately predict leaf chlorophyll content. Some of the reported techniques for quantifying crop growth and results of crop reflectance behaviour were confirmed. Leaf pigment concentrations of small plots of barley could be assessed independently of crop biomass using oblique radiometer views of the crop canopy to eliminate the very large influence of the soil background reflectance.
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Azaiez, Asma. "Les singularités en temps fini pour les équations semi-linéaires des ondes." Thesis, Paris 13, 2014. http://www.theses.fr/2014PA132046.
Повний текст джерелаАнотація:
Cette thèse est dédiée à l’étude du phénomène d’explosion en temps fini pour les équations semi-linéaires des ondes. On traite deux modèles dans ce travail.Dans une première direction, on considère l’équation semi-linéaire des ondes à valeurs complexes avec une nonlinéarité en puissance. On caractérise d’abord toutes les solutions du problème stationnaire comme une famille à deux paramètres.Ensuite, on utilise une approche de système dynamique pour montrer que la solution en transformation auto-similaire s’approche d’une solution stationnaire particulière dans l’espace d’énergie, dans le cas des points non caractéristiques.Ceci donne le profil à l’explosion pour l’équation originale dans le cas non-caractéristique.Dans une seconde direction, on étudie l’exemple de l’équation des ondes avec source exponentielle critique en dimension 1. On généralise les résultats de Godin pour une classe de données initiales beaucoup plus grandes. On prouve des estimations à l’explosion pour tout point de l’espace et on donne une estimation optimale du taux d’explosion pour les points non-caractéristiquesThis thesis is devoted to the study of the finite time blow-up phenomena for the semilinear waves equations. We treat two models in this work.In the first part, we consider a complex-valued solution for the semilinear wave equation with power nonlinearity. We first characterize all the solutions of the associated stationary problem as a two-parameter family. Then, weuse a dynamical system formulation to show that the solution in self-similar variables approaches some particular stationary one in the energy norm, in the non-characteristic case. This gives the blow-up profile for the original equation in the non-characteristic case.The second part is dedicated to the study of the semilinear wave equation with exponential nonlinearity in one space dimension. We generalize the results of Godin to a much larger class of initial data. We prove blow-up estimates near any point and give an optimal bound on the blow-up rate near the non characteristic points
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Chung, San-Lin. "The generalised Geske-Johnson technique for the valuation of American options with stochastic interest rates." Thesis, Lancaster University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264117.
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Mesleh, Raed Yousef [Verfasser]. "Spatial modulation : a spatial multiplexing technique for efficient wireless data transmission / Raed Yousef Mesleh." Bremen : IRC-Library, Information Resource Center der Jacobs University Bremen, 2008. http://d-nb.info/1034966804/34.
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Rumana, Kashifa. "Novel Techniques to Determine Soil Evaporation Rates: Heat Pulse Probe and Automated Microlysimeter." DigitalCommons@USU, 2015. https://digitalcommons.usu.edu/etd/4227.
Повний текст джерелаАнотація:
Soil water evaporation is a critical component of both the surface energy balance and the hydrologic cycle, coupling heat and water transfer between land and atmosphere. Bare-soil evaporation and plant-soil-atmospheric interactions are important components of the water balance, especially in semiarid and arid regions. Soil evaporation has been thoroughly studied during the past century, yielding many methods and models.
However, none of the methods have adequately addressed the needs for in situ and real-time monitoring of soil evaporation. The objectives of this research project were to track soil water evaporation losses using two different methods: a heat pulse probe (HPP) array and a fully automated microlysimeter (FAML). The HPP consists of a heater needle and five thermistor needles; when rotated to an angle of 27.3° from a vertical orientation, it yielded temperature measurements every 3 mm within the soil profile. On the application of heat input to a resistance wire in the heater needle, the remaining thermistor needles measured the temperature response at a fixed distance of 6.5 mm from the heater. Results from our study demonstrate application of the sensible heat balance approach that provided reasonable estimates of subsurface evaporation rates. Inconsistencies due to the inability of the HPP to estimate evaporation rates in the near-surface "undetectable zone" are also reported in comparison to actual stage-2 evaporation based on the mass balance method. Additionally, deviations from the prescribed installation angle introduced errors when calculating the temperature gradient; hence, a vertical spacing algorithm was developed to resolve spacing errors. In the third chapter, a fully automated design is discussed based on the microlysimeter concept with the enhancement of an 8- cm deep lysimeter that was mounted on a 10 kg load cell for real-time monitoring diurnal evaporation rates from bare soil. The comparison with HYDRUS-1D simulation validated the FAML measured instantaneous evaporation rates with slight disparity toward the end of the experiment. Overall, this study shows two feasible methods for estimating real time evaporation rates in situ over prolonged periods with the aid of the HPP or the FAML. These tools can assist researchers with improved assessment of soil evaporation while taking into account proper correction methods.
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EcheverriÌa, Arjonilla Juan Carlos. "Non-stationary and fractal techniques for the analysis of heart rate variability." Thesis, University of Nottingham, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.396717.
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Abdul, Aziz Mohamad Kamree. "High data rate WLAN enhancement using multiple antennas and iterative processing techniques." Thesis, University of Bristol, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.413619.
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Sriratanaban, Chana. "Improved excitation techniques for fixed and variable rate CELP-based speech coding." Thesis, University of Surrey, 1999. http://epubs.surrey.ac.uk/843285/.
Повний текст джерелаАнотація:
The last decade has witnessed rapid growth and development within the telecommunication industry. This, in particular for speech coding, has been primarily driven by the enormous expansion of digital mobile communication. Whilst the available bandwidth in wired based terrestrial network is a relatively cheap and expandable resource, it becomes unavoidably limited in satellite or mobile communication systems. At the same time, a high quality speech communication system is preferred. This, on the other hand, requires high data rates. Therefore, key factors to design speech coder are both the optimisation of the bandwidth usage and provision of high quality of service. The research carried out in this thesis has mainly focused on the design and development of low to medium bit rate narrowband and wideband speech coding algorithms which are based on Analysis-by-Synthesis Linear Prediction Coding (AbS-LPC). In order to reduce the computational complexity as well as to improve the perceptual quality, the secondary excitation used in the developed coder is based on sparsely populated pulse vectors instead of a Gaussian codebook, used in the original famous Code Excited Linear Prediction (CELP) coder. The algorithms subsequently developed also incorporate a multi-rate operation i.e. speech and channel coding bit allocation can be varied for different level of error protection according to channel conditions. Moreover, the developed coder is designed to operate between 8 and 14 kb/s, at a gross bit rate of 22.8 kb/s in order to provide a reliable service in the existing mobile communication network. In addition to the multi-rate speech coders, a new approach to variable rate speech coder is presented. In this course of research, longer frame lengths are used when possible i.e. when the speech segment contains similar- characteristics. This is mainly to reduce the parameter updating rate, and hence the bit rate. Speech segmentation and voice classification are obtained via speech recognition. Different types of excitation are used for different voice classes in order to improve the speech quality and to further reduce the bit rate. However, some applications require very high quality speech which narrowband speech cannot offer. The work in this research also includes the development of wideband CELP coder that operates at much lower bit rate than the current standards whilst maintaining toll or near toll quality of speech.