Dissertations / Theses on the topic 'Loads estimation'
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Kim, Hak Joon. "Estimation for tunnel lining loads." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq23005.pdf.
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Fowler, Christopher G. "Robust estimation of limit loads for cracked components." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0001/MQ42382.pdf.
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Modenese, Luca. "Biomechanics, musculoskeletal modelling, hip joint loads prediction, muscle force estimation." Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/39476.
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A musculoskeletal model of the lower limb has been implemented and assessed in order to be used as a predictive tool to quantify the hip contact force (HCF) vector acting between the femoral head and the pelvic acetabulum. The model is based on a published anatomical dataset, which has been critically revised and extended. The HCFs obtained through the model have been assessed at multiple levels of detail against measurements from instrumented prostheses from a publicly available dataset. In the first instance, a direct comparison has been undertaken in order to verify predicted HCF magnitudes close to the measured and muscle recruitment consistent with electromyographic activation profiles reported in the literature. Secondly, a trend validation was performed to ensure the correct behaviour of the model when the same daily living task (level walking) was performed with different modalities. Finally, a falsification of the model was performed by challenging it to predict the exact components of the measured hip contact forces for both level walking and stair climbing. The closest achievable predictions were also calculated, together with the accuracy of a conventional use of the model not exploiting a priori knowledge of the joint contact forces. Once the assessment of the model was completed, a dataset of anthropometric, kinematic and kinetic data was collected on eight young healthy subjects performing daily living activities. As a demonstration of the potential use of the dataset, a subject specific model was generated and used to estimate HCF direction and magnitude for level walking and stair climbing, the same activities investigated during model validation. The model was further extended in order to include the upper part of the body and potentially analyze full body kinematics and kinetics. A further modified version of the model was finally developed in order to be used in finite elements analyses or more generally in applications requiring equilibrated sets of muscle and joint forces acting on a bone structure, as the highly discretized representation of the muscles makes the model particularly suitable for this kind of use. The developed model has been implemented in the open source software OpenSim and is freely available for download and use in research.
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Lodhi, Muhammad S. "RESPONSE ESTIMATION OF REINFORCED CONCRETE COLUMNS SUBJECTED TO LATERAL LOADS." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1269631164.
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Mansor, Shuhaimi. "Estimation of bluff body transient aerodynamic loads using an oscillating model rig." Thesis, Loughborough University, 2006. https://dspace.lboro.ac.uk/2134/13208.
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A method for the estimation of transient aerodynamic data from dynamic wind tunnel tests has been developed and employed in the study of the unsteady response of simple automotive type bodies. The experimental setup consists of the test model mounted to the oscillating model facility such that it is constrained to oscillate with a single degree of freedom of pure yawing motion. The yaw position is recorded from a potentiometer and the time response provides the primary measurement. Analysis of the wind-off and wind-on response allows the transient aerodynamic loads to be estimated. The frequency of oscillation, (synonymous with the frequency of disturbing wind input) is modified by altering the mechanical stiffness of the facility. The effects of Reynolds number and oscillation frequency are considered and the model is shown to exhibit damped, self-sustained and self-excited behaviour. The transient results are compared with a quasi-steady prediction based on conventional tunnel balance data and presented in the form of aerodynamic magnification factor. The facility and analysis techniques employed are presented and the results of a parametric study of model rear slant angle and of the influence of C-pillar strakes is reported. The results are strongly dependent on shape but for almost all rear slant angles tested the results show that the transient response exceeds that predicted from steady state data. The level of unsteadiness is also significantly influenced by the rear slant angles. The addition of C-pillar strakes is shown to stabilise the flow with even small strakes yielding responses below that of steady state. From the simulation results the self-sustained oscillation is shown to occur when the aerodynamic damping cancels the mechanical damping. The unsteadiness in the oscillation can be simulated by adding band-limited white noise with an intensity close to that of the turbulence intensity found in the wake. From vehicle crosswind simulation results the aerodynamic yaw moment derivative and its magnification factor are shown to be the important parameters influencing the crosswind sensitivity and path deviation.
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Leitch, Katherine McArthur. "Estimating Tributary Phosphorus Loads Using Flow-Weighted Composite Storm Sampling." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/10078.
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Quantification of total phosphorus (TP) loads entering a lake or reservoir is important because phosphorus is most often the limiting nutrient in terms of algae growth, thus phosphorus can control the extent of eutrophication. Four methods for assessing the annual tributary phosphorus loads to two different Virginia reservoirs were analyzed, three methods that use tributary monitoring program data and one that uses land-use and rainfall data. In this project, one tributary has been extensively monitored for many years and served as a control on which the other methods were tested. The key difference between this research and previous studies is the inclusion of flow-weighted composite storm sampling instead of simple grab sample analyses of storm flow. Three of the methods employed flow stratification, and the impact of the base flow separation point was examined. It was found that the Regression Method developed in this research was the least sensitive to the base flow separation point, which is a valuable attribute because a wrong choice will not significantly affect the estimate. The Monte Carlo Method was found to underestimate the TP loads. The amount of rainfall impacted the accuracy of the methods, with more error occurring in a year with lower precipitation.Master of Science
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Neubert, Michael Christopher. "Estimation of Required Restraint Forces in Z-Purlin Supported, Sloped Roofs Under Gravity Loads." Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/44512.
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The current specification provisions for the prediction of lateral restraint forces in Z-purlin supported roof systems under gravity loads are in Section D3.1 of the 1996 AISI Cold-Formed Specification. The design equations contained in these provisions are empirical and based on statistical analysis. They were developed using elastic stiffness models of flat roofs and were verified by experimental testing. The provisions need refinement, because the treatment of roof slope and system effects is incorrect. Also, the current design provisions are based upon an assumed panel stiffness value, ignoring the significant difference in required restraint force that occurs when panel stiffness is varied.
Therefore, a new restraint force design procedure, having a stronger reliance on engineering principles, is proposed. This new treatment of the static forces in Z-purlin roofs led to a more accurate method of addressing roof slope. Elastic stiffness models, with varying roof slope, panel stiffness, and cross-sectional properties, were used to develop the proposed procedure. The basis of the procedure is to determine the lateral restraint force required for a single purlin system and then extend this result to systems with multiple restrained purlin lines. Roof slope is incorporated into the calculation of the single purlin restraint force, which includes eccentric gravity loads and forces induced by Z-purlin asymmetry. The procedure includes a system effect factor to account for the observed nonlinear increase in restraint force with the number of restrained purlins. An adjustment factor varies the predicted restraint force depending on the shear stiffness of the roof panel. The proposed procedure applies to five bracing configurations: support, third-point, midspan, quarter point, and third-point plus support restraints.Master of Science
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Carn, Cheril, and cheril Carn@dsto defence gov au. "The inverse determination of aircraft loading using artificial neural network analysis of structural response data with statistical methods." RMIT University. Aerospace, Mechanical and Manufacturing Engineering, 2007. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080109.090600.
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An artificial Neural Network (ANN) system has been developed that can analyse aircraft flight data to provide a reconstruction of the aerodynamic loads experienced by the aircraft during flight, including manoeuvre, buffet and distributed loading. For this research data was taken from the International Follow-On Structural Test Project (IFOSTP) F/A-18 fatigue test conducted by the Royal Australian Air Force and Canadian Forces. This fatigue test involved the simultaneous application of both manouevre and buffet loads using airbag actuators and shakers. The applied loads were representative of the actual loads experienced by an FA/18 during flight tests. Following an evaluation of different ANN types an Ellman network with three linear layers was selected. The Elman back-propagation network was tested with various parameters and structures. The network was trained using the MATLAB 'traingdx' function with is a gradient descent with momentum and adaptive learning rate back-propagation algorithm. The ANN was able to provide a good approximation of the actual manoeuvre or buffet loads at the location where the training loads data were recorded even for input values which differ from the training input values. In further tests the ability to estimate distributed loading at locations not included in the training data was also demonstrated. The ANN was then modified to incorporate various methods for the calculation and prediction of output error and reliability Used in combination and in appropriate circumstances, the addition of these capabilities significantly increase the reliability, accuracy and therefore usefulness of the ANN system's ability to estimate aircraft loading.To demonstrate the ANN system's usefulness as a fatigue monitoring tool it was combined with a formulae for crack growth analysis. Results inficate the ANN system may be a useful fatigue monitoring tool enabling real time monitoring of aircraft critical components using existing strain gauge sensors.
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Giri, Suman. "A Framework for Estimating Energy Consumed by Electric Loads Through Minimally Intrusive Approaches." Research Showcase @ CMU, 2015. http://repository.cmu.edu/dissertations/564.
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This dissertation explores the problem of energy estimation in supervised Non-Intrusive Load Monitoring (NILM). NILM refers to a set of techniques used to estimate the electricity consumed by individual loads in a building from measurements of the total electrical consumption. Most commonly, NILM works by first attributing any significant change in the total power consumption (also known as an event) to a specific load and subsequently using these attributions (i.e. the labels for the events) to estimate energy for each load. For this last step, most proposed solutions in the field impart simplifying assumptions to make the problem more tractable. This has severely limited the practicality of the proposed solutions. To address this knowledge gap, we present a framework for creating appliance models based on classification labels and aggregate power measurements that can help relax many of these assumptions. Within the framework, we model the problem of utilizing a sequence of event labels to generate energy estimates as a broader class of problems that has two major components (i) With the understanding that the labels arise from a process with distinct states and state transitions, we estimate the underlying Finite State Machine (FSM) model that most likely generated the observed sequence (ii) We allow for the observed sequence to have errors, and present an error correction algorithm to detect and correct them. We test the framework on data from 43 appliances collected from 19 houses and find that it improves errors in energy estimates when compared to the case with no correction in 19 appliances by a factor of 50, leaves 17 appliances unchanged, and negatively impacts 6 appliances by a factor of 1.4. This approach of utilizing event sequences to estimate energy has implications in virtual metering of appliances as well. In a case study, we utilize this framework in order to substitute the need of plug-level sensors with cheap and easily deployable contacless sensors, and find that on the 6 appliances virtually metered using magnetic field sensors, the inferred energy values have an average error of 10:9%.
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Löfgren, Isabelle. "Interharmonic Analysis of Sustainable Energy Sources and Loads : Comparing two signal processing methods for estimation of interharmonics." Thesis, Högskolan Dalarna, Energiteknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:du-34236.
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In this report, studies on interharmonics from three different measurement sites are performed. The first site is a wind park with three turbines, where the measurements are performed at the point of common coupling of these three. The second site is a network which consists of a PV inverter and two types of EV chargers – a DC charger or an AC charger. Measurements are performed with three different set-ups in this site – only AC charger connected, only DC charger connected, and AC charger and PV inverter connected simultaneously. The third site where measurements were made is a microgrid using frequency control in order to signal how the microgrid should operate at the moment. The interharmonic analysis was conducted using desynchronized processing technique (DP) and Sliding-Window Estimation of Signal Parameters via Rotational Invariance Techniques (SlidingWindow ESPRIT or SWESPRIT). The result from the wind park is that closely and evenly spaced interharmonics can be seen when the current suddenly increases (could be fast variations in wind speed). It is however uncertain if these interharmonics are caused by spectral leakage or not since SWESPRIT estimates the fundamental frequency to vary drastically when wind speed varies. It is observed that the SWESPRIT estimation of fundamental frequency could be caused by sudden changes in phase angle as the current varies. Further investigation and analysis are needed. The result from the measurements on the site with EV chargers and a PV inverter is that eight distinct patterns can be observed. Some patterns appear to come from the upstream grid, while some appear to be caused by either one of the EV chargers or the PV inverter, or interaction between them. Further studies are needed. The result from the microgrid measurements is that two distinct patterns at high frequencies (above 1000 Hz) can be observed during grid connected mode and island mode, respectively. During transitions between grid connection and island mode or vice versa, the fundamental frequency varies drastically, and it is therefore hard to analyse potential interharmonics and draw inferences. Further studies are needed. Advantages and disadvantages, as well as ideas for improvements, of the two applied signal processing methods are discussed throughout the different case-studies.
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Dalane, Eirik. "Estimation of ALS wave-column impact loads for a semi-submersible and a simplified assessment of the associated structural response." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for marin teknikk, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-15493.
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Breaking waves that impacts with a platform column will give large impact loads. These loads are some of the largest loads acting on a platform during its lifetime. During the summer 2010, MARINTEK performed model tests on a semi-submersible, called Midgard, where these impact loads were measured at one of the platform columns. In this report, two methods have been used to predict the ALS impact loads from breaking waves. A numerical method based on DNV-RP-C205 and stochastic analysis of model test data. The uncertainty in each method has been assessed, and it was concluded that there is large uncertainties related to the problem of breaking wave impact. The ALS impact load predicted using stochastic analysis of model test data became almost twice as large as what was predicted using the numerical method. The main reason for this difference was that the numerical method used an estimated value for the horizontal velocity between the wave and the platform that was too small compared with the model tests. The different sensors measured impact force during the model tests has been compared. This showed that for a breaking wave that hit all the sensors, the sensor located highest on the column would experience largest impact while the lowest sensor would experience least impact force. The sensors horizontal location on the column was of less importance. Based on this information some load models was suggested. A simplified structural model was made of the column. Static and dynamic analyses were performed using the suggested load models. The dynamic effects were found to be small because the duration of the impact load was so much higher than the natural period of the column. The largest bending moment at the top of the column was compared with the column’s elastic moment capacity. It was found to be of little importance. This indicates that ALS impact loads from breaking waves do not give a significant contribution to global structural response.
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Smith, Benjamin A. "Model Free Human Pose Estimation with Application to the Classification of Abnormal Human Movement and the Detection of Hidden Loads." Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/28360.
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The extraction and analysis of human gait characteristics using image sequences are an important area of research. Recently, the focus of this research area has turned to computer vision as an unobtrusive way to analyze human motions. The applications for such a system are wide ranging in many disciplines. For example, it has been shown that visual systems can be used to identify people by their gait, estimate a subjectâ s kinematic configuration and identify abnormal motion. The focus of this thesis is a system that accurately classifies observed motions without the use of an explicit spatial or temporal model. The visual detection of hidden loads through passive visual analysis of gait is presented as a test of the system.
The major contributions of this thesis are in two areas. The first is a neural network based scheme that classifies walking styles based on simple image metrics obtained from a single, monocular gray scale image sequence. The powerful neural network classifier utilized in this system provides an efficient, robust and highly accurate classification using these image metrics. This eliminates the need for more complex and difficult to obtain measures that are required by many of the currently human visual analysis systems. This system uses computer vision and pattern recognition techniques combined with physiological knowledge of human gait to estimate an observed subjectâ s hip angle. The hip angle is then used to calculate a normality index of the gait. The hip angle estimate and normality index are then used as inputs to a neural network. It is shown through experiment that this system provides an accurate classification of four different walking styles observed by a single camera. Secondly, a computer vision based approach is presented that provides an accurate pose estimate without the use of an explicit spatial or temporal model. A hybrid fuzzy neural network is used to assign contour points of a silhouette to kinematically relevant groups. These labeled points are used to estimate the joint locations of the subject. The joint angles are shown to be good estimates as compared to ground truth angles provided by a motion capture system. The effectiveness of the system to distinguish between subtle gait differences is demonstrated by detecting the presence of hidden loads when carried by walking people.Ph. D.
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Moravej, Mohammadtaghi. "Investigating Scale Effects on Analytical Methods of Predicting Peak Wind Loads on Buildings." FIU Digital Commons, 2018. https://digitalcommons.fiu.edu/etd/3799.
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Large-scale testing of low-rise buildings or components of tall buildings is essential as it provides more representative information about the realistic wind effects than the typical small scale studies, but as the model size increases, relatively less large-scale turbulence in the upcoming flow can be generated. This results in a turbulence power spectrum lacking low-frequency turbulence content. This deficiency is known to have significant effects on the estimated peak wind loads.
To overcome these limitations, the method of Partial Turbulence Simulation (PTS) has been developed recently in the FIU Wall of Wind lab to analytically compensate for the effects of the missing low-frequency content of the spectrum. This method requires post-test analysis procedures and is based on the quasi-steady assumptions. The current study was an effort to enhance that technique by investigating the effect of scaling and the range of applicability of the method by considering the limitations risen from the underlying theory, and to simplify the 2DPTS (includes both in-plane components of the turbulence) by proposing a weighted average method. Investigating the effect of Reynolds number on peak aerodynamic pressures was another objective of the study.
The results from five tested building models show as the model size was increased, PTS results showed a better agreement with the available field data from TTU building. Although for the smaller models (i.e., 1:100,1:50) almost a full range of turbulence spectrum was present, the highest peaks observed at full-scale were not reproduced, which apparently was because of the Reynolds number effect. The most accurate results were obtained when the PTS was used in the case with highest Reynolds number, which was the1:6 scale model with a less than 5% blockage and a xLum/bm ratio of 0.78. Besides that, the results showed that the weighted average PTS method can be used in lieu of the 2DPTS approach. So to achieve the most accurate results, a large-scale test followed by a PTS peak estimation method deemed to be the desirable approach which also allows the xLum/bm values much smaller than the ASCE recommended numbers.
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Zhong, Shan. "Measurement calibration/tuning & topology processing in power system state estimation." Texas A&M University, 2003. http://hdl.handle.net/1969.1/1595.
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State estimation plays an important role in modern power systems. The errors in the telemetered measurements and the connectivity information of the network will greatly contaminate the estimated system state. This dissertation provides solutions to suppress the influences of these errors.
A two-stage state estimation algorithm has been utilized in topology error identification in the past decade. Chapter II discusses the implementation of this algorithm. A concise substation model is defined for this purpose. A friendly user interface that incorporates the two-stage algorithm into the conventional state estimator is developed.
The performances of the two-stage state estimation algorithms rely on accurate determination of suspect substations. A comprehensive identification procedure is described in chapter III. In order to evaluate the proposed procedure, a topology error library is created. Several identification methods are comparatively tested using this library.
A remote measurement calibration method is presented in chapter IV. The un-calibrated quantities can be related to the true values by the characteristic functions. The conventional state estimation algorithm is modified to include the parameters of these functions. Hence they can be estimated along with the system state variables and used to calibrate the measurements. The measurements taken at different time instants are utilized to minimize the influence of the random errors.
A method for auto tuning of measurement weights in state estimation is described in chapter V. Two alternative ways to estimate the measurement random error variances are discussed. They are both tested on simulation data generated based on IEEE systems. Their performances are compared. A comprehensive solution, which contains an initialization process and a recursively updating process, is presented.
Chapter VI investigates the errors introduced in the positive sequence state estimation due to the usual assumptions of having fully balanced bus loads/generations and continuously transposed transmission lines. Several tests are conducted using different assumptions regarding the availability of single and multi-phase measurements. It is demonstrated that incomplete metering of three-phase system quantities may lead to significant errors in the positive sequence state estimates for certain cases. A novel sequence domain three-phase state estimation algorithm is proposed to solve this problem.
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Genest, Laurent. "Optimisation de forme par gradient en dynamique rapide." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEC022/document.
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Afin de faire face aux nouveaux challenges de l’industrie automobile, les ingénieurs souhaitent appliquer des méthodes d’optimisation à chaque étape du processus de conception. En élargissant l’espace de conception aux paramètres de forme, en augmentant leur nombre et en étendant les plages de variation, de nouveaux verrous sont apparus. C’est le cas de la résistance aux chocs. Avec les temps de calcul long, la non-linéarité, l’instabilité et la dispersion numérique de ce problème de dynamique rapide, la méthode usuellement employée, l’optimisation par plan d’expériences et surfaces de réponse, devient trop coûteuse pour être utilisée industriellement. Se pose alors la problématique suivante : Comment faire de l’optimisation de forme en dynamique rapide avec un nombre élevé de paramètres ?. Pour y répondre, les méthodes d’optimisation par gradient s’avèrent être les plus judicieuses. Le nombre de paramètres a une influence réduite sur le coût de l’optimisation. Elles permettent donc l’optimisation de problèmes ayant de nombreux paramètres. Cependant, les méthodes classiques de calcul du gradient sont peu pertinentes en dynamique rapide : le coût en nombre de simulations et le bruit empêchent l’utilisation des différences finies et le calcul du gradient en dérivant les équations de dynamique rapide n’est pas encore disponible et serait très intrusif vis-à-vis des logiciels. Au lieu de déterminer le gradient, au sens classique du terme, des problèmes de crash, nous avons cherché à l’estimer. L’Equivalent Static Loads Method est une méthode permettant l’optimisation à moindre coût basée sur la construction d’un problème statique linéaire équivalent au problème de dynamique rapide. En utilisant la dérivée du problème équivalent comme estimation du gradient, il nous a été possible d’optimiser des problèmes de dynamique rapide ayant des épaisseurs comme variables d’optimisation. De plus, si l’on construit les équations du problème équivalent avec la matrice de rigidité sécante, l’approximation du gradient n’en est que meilleure. De cette manière, il est aussi possible d’estimer le gradient par rapport à la position des nœuds du modèle de calcul. Comme il est plus courant de travailler avec des paramètres CAO, il faut déterminer la dérivée de la position des nœuds par rapport à ces paramètres. Nous pouvons le faire de manière analytique si nous utilisons une surface paramétrique pour définir la forme et ses points de contrôle comme variables d’optimisation. Grâce à l’estimation du gradient et à ce lien entre nœuds et paramètres de forme, l’optimisation de forme avec un nombre important de paramètres est désormais possible à moindre coût. La méthode a été développée pour deux familles de critères issues du crash automobile. La première est liée au déplacement d’un nœud, objectif important lorsqu’il faut préserver l’intégrité de l’habitacle du véhicule. La seconde est liée à l’énergie de déformation. Elle permet d’assurer un bon comportement de la structure lors du chocIn order to face their new industrial challenges, automotive constructors wish to apply optimization methods in every step of the design process. By including shape parameters in the design space, increasing their number and their variation range, new problematics appeared. It is the case of crashworthiness. With the high computational time, the nonlinearity, the instability and the numerical dispersion of this rapid dynamics problem, metamodeling techniques become to heavy for the standardization of those optimization methods. We face this problematic: ”How can we carry out shape optimization in rapid dynamics with a high number of parameters ?”. Gradient methods are the most likely to solve this problematic. Because the number of parameters has a reduced effect on the optimization cost, they allow optimization with a high number of parameters. However, conventional methods used to calculate gradients are ineffective: the computation cost and the numerical noise prevent the use of finite differences and the calculation of a gradient by deriving the rapid dynamics equations is not currently available and would be really intrusive towards the software. Instead of determining the real gradient, we decided to estimate it. The Equivalent Static Loads Method is an optimization method based on the construction of a linear static problem equivalent to the rapid dynamic problem. By using the sensitivity of the equivalent problem as the estimated gradient, we have optimized rapid dynamic problems with thickness parameters. It is also possible to approximate the derivative with respect to the position of the nodes of the CAE model. But it is more common to use CAD parameters in shape optimization studies. So it is needed to have the sensitivity of the nodes position with these CAD parameters. It is possible to obtain it analytically by using parametric surface for the shape and its poles as parameters. With this link between nodes and CAD parameters, we can do shape optimization studies with a large number of parameters and this with a low optimization cost. The method has been developed for two kinds of crashworthiness objective functions. The first family of criterions is linked to a nodal displacement. This category contains objectives like the minimization of the intrusion inside the passenger compartment. The second one is linked to the absorbed energy. It is used to ensure a good behavior of the structure during the crash
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Sanjab, Anibal Jean. "Statistical Analysis of Electric Energy Markets with Large-Scale Renewable Generation Using Point Estimate Methods." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/74356.
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The restructuring of the electric energy market and the proliferation of intermittent renewable-energy based power generation have introduced serious challenges to power system operation emanating from the uncertainties introduced to the system variables (electricity prices, congestion levels etc.). In order to economically operate the system and efficiently run the energy market, a statistical analysis of the system variables under uncertainty is needed. Such statistical analysis can be performed through an estimation of the statistical moments of these variables. In this thesis, the Point Estimate Methods (PEMs) are applied to the optimal power flow (OPF) problem to estimate the statistical moments of the locational marginal prices (LMPs) and total generation cost under system uncertainty. An extensive mathematical examination and risk analysis of existing PEMs are performed and a new PEM scheme is introduced. The applied PEMs consist of two schemes introduced by H.P. Hong, namely, the 2n and 2n+1 schemes, and a proposed combination between Hong's and M. E Harr's schemes. The accuracy of the applied PEMs in estimating the statistical moments of system LMPs is illustrated and the performance of the suggested combination of Harr's and Hong's PEMs is shown. Moreover, the risks of the application of Hong's 2n scheme to the OPF problem are discussed by showing that it can potentially yield inaccurate LMP estimates or run into unfeasibility of the OPF problem. In addition, a new PEM configuration is also introduced. This configuration is derived from a PEM introduced by E. Rosenblueth. It can accommodate asymmetry and correlation of input random variables in a more computationally efficient manner than its Rosenblueth's counterpart.Master of Science
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Yarali, Abdulrahman. "Peak load estimation using load research data." Diss., Virginia Tech, 1995. http://hdl.handle.net/10919/39154.
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Peak load estimation is a critical element in utility decision making. An electric utility must construct, maintain, and operate equipment sufficient to meet the peak, or maximum demand level. Electric utilities have utilized several methods of analyzing energy consumption which have yielded various levels of accuracy for estimating maximum demand.
In this research, a new method, Nonlinear Load Research Estimation (NLRE), is proposed to estimate the peak load and load characteristics of individual and group of different customer classes. Load research data is used to develop KWHr-to-KW conversion factors, diversity factors, and average time-varying load data as a function of customer class, month, and type of day. Load research data is used to derive monthly load
shapes by customer class. These profiles are used to apportion customer KWHr usage among billing cycles according to the split indicated by test data. This parsed KWHr can be further allocated based on type of day to estimate weekday and weekend peak values.Ph. D.
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Seppälä, Anssi. "Load research and load estimation in electricity distribution /." Espoo : Technical Research Centre of Finland, 1996. http://www.vtt.fi/inf/pdf/publications/1996/P289.pdf.
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Eyisi, Chiebuka. "Load Estimation for Electric Power Distribution Networks." Master's thesis, University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5935.
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In electric power distribution systems, the major determinant in electricity supply strategy is the quantity of demand. Customers need to be accurately represented using updated nodal load information as a requirement for efficient control and operation of the distribution network. In Distribution Load Estimation (DLE), two major categories of data are utilized: historical data and direct real-time measured data. In this thesis, a comprehensive survey on the state-of-the-art methods for estimating loads in distribution networks is presented. Then, a novel method for representing historical data in the form of Representative Load Curves (RLCs) for use in real-time DLE is also described. Adaptive Neuro-Fuzzy Inference Systems (ANFIS) is used in this regard to determine RLCs. An RLC is a curve that represents the behavior of the load during a specified time span; typically daily, weekly or monthly based on historical data. Although RLCs provide insight about the variation of load, it is not accurate enough for estimating real-time load. This therefore, should be used along with real-time measurements to estimate the load more accurately. It is notable that more accurate RLCs lead to better real-time load estimation in distribution networks.
This thesis addresses the need to obtain accurate RLCs to assist in the decision-making process pertaining to Radial Distribution Networks (RDNs).This thesis proposes a method based on Adaptive Neuro-Fuzzy Inference Systems (ANFIS) architecture to estimate the RLCs for Distribution Networks. The performance of the method is demonstrated and simulated, on a test 11kV Radial Distribution Network using the MATLAB software. The Mean Absolute Percent Error (MAPE) criterion is used to justify the accuracy of the RLCs.M.S.E.E.
Masters
Electrical Engineering and Computing
Engineering and Computer Science
Electrical Engineering
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Dhananjay, Aditya Vasudev. "Load estimation in IEEE 802.11 wireless networks." [Ames, Iowa : Iowa State University], 2008.
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Nyberg, Tobias. "Torque-Based Load Estimation for Passenger Vehicles." Thesis, Linköpings universitet, Reglerteknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-179208.
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An accurate estimate of the mass of a passenger vehicle is important for several safety systems and environmental aspects. In this thesis, an algorithm for estimating the mass of a passenger vehicle using the recursive least squares methodis presented. The algorithm is based on a physical model of the vehicle and is designed to be able to run in real-time onboard a vehicle and uses the wheel torque signal calculated in the electrical control unit in the engine. Therefore no estimation of the powertrain is needed. This is one contribution that distinguishes this thesis from previous work on the same topic, which has used the engine torque. The benefit of this is that no estimation of the dynamics in the powertrain is needed. The drawback of using this method is that the algorithm is dependenton the accuracy of the estimation done in the engine electrical control unit. Two different versions of the recursive least squares method (RLS) have been developed - one with a single forgetting factor and one with two forgetting factors. The estimation performance of the two versions are compared on several different real-world driving scenarios, which include driving on country roads, highways, and city roads, and different loads in the vehicle. The algorithm with a single forgetting factor estimates the mass with an average error for all tests of 4.42% and the algorithm with multiple forgetting factors estimates the mass with an average error of 4.15 %, which is in line with state-of-the-art algorithms that are presented in other studies. In a sensitivity analysis, it is shown that the algorithms are robust to changes in the drag coefficient. The single forgetting factor algorithm is robust to changes in the rolling resistance coefficient whereas the multiple forgetting factor algorithm needs the rolling resistance coefficient to be estimated with fairly good accuracy. Both versions of the algorithm need to know the wheel radius with an accuracy of 90 %. The results show that the algorithms estimate the mass accurately for all three different driving scenarios and estimate highway roads best with an average error of 2.83 % and 2.69 % for the single forgetting factor algorithm and the multiple forgetting factor algorithm, respectively. The results indicate it is possible to use either algorithm in a real-world scenario, where the choice of which algorithm depends on sought-after robustness.
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FERREIRA, MARCELO PIERI. "ESTIMATION OF THE SHORTAGE EFFECTS IN LOAD FORECASTING." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2004. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=4545@1.
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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOREsta dissertação investiga os efeitos do racionamento de energia elétrica ocorrido no período entre junho de 2001 a fevereiro de 2002, nas previsões de energia das principais concessionárias brasileiras. Para tal, estudamos o desempenho de modelos lineares e não-lineares. Dentre os modelos lineares, analisamos os modelos ARIMA (p,d,q) de Box & Jenkins e os modelos de amortecimento exponencial de Holt & Winters. Dentre os modelos não-lineares, são abordadas técnicas de inteligência artificial tais como Redes Neurais e Lógica Fuzzy. Visto que o racionamento levou a previsões ineficientes, propomos alternativas para reduzir seu impacto. Por último, investigamos os impactos causados pela crise energética nas previsões doze passos à frente de carga elétrica provenientes de vinte e oito concessionárias. A base de dados é composta pelos valores observados e as previsões fornecidas pelo PREVCAR, um dos sistemas de previsão da cadeia oficial de programas do setor elétrico brasileiro. Por meio de um procedimento de Análise de Agrupamento utilizando Redes Neurais Artificiais do tipo SOM (Self Organizing Map) de Kohonen são estabelecidos os grupos de concessionárias que possuem os mesmos comportamentos diante do racionamento. Como resultado final, foram estimados fatores de redução das previsões causados pelo racionamento, que servem como base de cálculo para reduções nas previsões futuras em períodos de crise de abastecimento.
This dissertation aims at an exploratory study of impacts caused by the 2001 energy crisis on the current forecasts produced on a monthly basis for main distributing utilities. For that we show an accuracy study of the performance of the linear and non-linear models. It has been used, within the linear models class, the modeling approach of Box-Jenkins and exponential smoothing of Holt- Winters. Within the non-linear ones, it was chosen those based on artificial intelligence techniques, such as Fuzzy Logic and Artificial Neural Network. Due to the lack of accuracy of the models to cope with the discontinuities provoked by the crisis on the forecasts, some alternative tools to reduce the impact on the forecast errors are proposed. Finally, the impacts caused by the crisis on multiple steps ahead forecasts have also been investigated. It was taken the monthly forecasts produced by PREVCAR (one of official Brazilian load forecasting system), as well as the observed values covering the same period, to create the crisis response indices series for each one of the twenty and eight utilities included in the analysis. It was also used the well-known neural network based algorithm SOM (Self Organizing Maps) to classify the utilities into homogeneous groups, according to their response to the energy crisis. As a final result, for each group, it was estimated the reduction factors that can be used as a prior information in future energy supply crisis.
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Spjutare, Christian. "Aerodynamic Loads on External Stores - Saab 39 Gripen : Evaluation of CFD methods for estimating loads on external stores." Thesis, Linköping University, Applied Thermodynamics and Fluid Mechanics, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-54127.
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External stores mounted on aircraft generate loads which need to be estimated before first takeoff. These loads can be measured in a wind tunnel but since the possible store configurations are basically endless, testing them all is neither economically feasible nor time efficient. Thus, scaling based on geometrical similarity is used. This can, however, be a crude method. Stores with similar geometrical properties can still behave in different ways due to aerodynamic interference caused by adjacent surfaces.
To improve the scaling performance, this work focuses on investigating two CFD codes, ADAPDT and Edge. The CFD simulations are used to derive the difference in aerodynamic coefficients, or the Δ-effect, between a reference store and the new untested store. The Δ-effect is then applied to an existing wind tunnel measurement of the reference store, yielding an estimation of the aerodynamic properties for the new store.
The results show that ADAPDT, using a coarse geometry representation, has large difficulties predicting the new store properties, even for a very simple store configuration on the aircraft. Therefore it is not suited to use as a scaling tool in its present condition. Edge on the other hand uses a more precise geometry representation and proves to deliver good estimations of the new store load behavior. Results are well balanced and mainly conservative. Some further work is needed to verify the performance but Edge is the recommended tool for scaling.
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Eskelinen, R. (Riku). "Runoff generation and load estimation in drained peatland areas." Doctoral thesis, Oulun yliopisto, 2017. http://urn.fi/urn:isbn:9789526214924.
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Abstract This thesis examined hydrological processes such as snowmelt and groundwater discharge in drained peatland areas in the boreal zone. The studied processes were measured in situ using environmental tracers. Further, performance of a treatment wetland was studied during snowmelt and high flow. A GIS model was developed to estimate groundwater seepage areas in peatland systems surrounding eskers. It was found that soil frost had a clear impact on water quality during snowmelt. This was evident as lower suspended sediments, water colour and dissolved organic carbon concentrations, among other changes. The treatment wetland was found to reduce the suspended solids load during the snowmelt period and late autumn, while reductions in phosphorus and nitrogen loads occurred during summer. A sampling algorithm was built to test how different sampling frequencies affected the estimation of suspended solid loads from the constructed wetland. The results showed increasing uncertainty for sparser sampling (from weekly to monthly sampling), but the uncertainty remained high even at weekly sampling. The GIS model was tested on two eskers and shown to give a fair estimate of groundwater discharge locations. It can thus be used for improving aquifer protection in boreal eskers related to the drainage networks surrounding them. However, to be applied more widely, further efforts are required. The findings in this thesis could be used to develop better water management policies for peat extraction areas, or other industries operating in similar soils and climate. For example, meltwater could be allowed to temporarily bypass treatment facilities in areas with deep soil frost penetration. The wetland study showed that peatland-based wetlands are a suitable approach for improving water treatment performance even under variable hydraulic loads. The uncertainty in the estimated load from a small peat extraction catchment was high, which might limit the use of such data for some purposes. Load estimation methods using the concentration data collected during previous years might be able to reduce the uncertainty, but if the uncertainty needs to be lowered substantially use of sensor technology might be the only viable approachTiivistelmä Tämä väitöskirja käsittelee lumensulannasta syntyvää valuntaa erilaisilla turvemailla ja pintavalutuskentän puhdistustehoa lumensulannan aikaan turvetuontantoalueella. Lisäksi työssä pohditaan miten erilainen näytteenottoohjelma vaikuttaa turvetuotantoalueilta arvioituun kiintoaine kuormitukseen ja kehitetään yleiseen paikkatietoaineistoon perustuva malli jolla on mahdollista ennustaa pohjaveden purkatumispaikkoja harjualueilla. Routaisella turvetuotantoalueelta kiintoaineen, värin ja liuenneen orgaanisen hiilen pitoisuudet olivat pieniä lumensulannan aikaan. Työssä seurattu pintavalutuskenttä vähensi kiintoainekuormitusta alapuoliseen vesistöön myös lumensulannan ja syksyn aikana. Ravinteiden osalta pintavalutuskentän toiminta oli parasta kesäaikaan, lumensulannan ja syksyn aikana havaittiin typen ja fosforin huuhtoutumista. Eri näytteenotto-ohjelmilla havaittiin olevan suuri vaikutus arvioituun kuormitukseen. Yleisesti voidaan sanoa epävarmuuden kasvavan kohti harvempaa näytteenotto väliä (viikoittainen-kuukausittainen), mutta, myös viikoittaisella näytteenotolla epävarmuus on huomattava. Kehitettyä paikka- tietomallia kokeiltiin kahdella harjulla jossa se pystyi antamaan suuntaa antavaa arvioita pohjaveden purkautumispaikoista. Työn tuloksia voidaan hyödyntää turvetuotannon tai muiden turvemailla tai niiden lähellä sijaitsevien teollisuuden vesistövaikutuksia arvioitaessa. Esimerkiksi routaisella turvemaalla voitaisiin harkita lumensulannasta aiheituvan valunnan ohijuoksutusta vesiensuojelurakenteista. Työssä todettiin myös pintavalutuskenttien toimivan vaihtelevan kuormituksen alaisena, sekä lumensulannan että syksyn aikaan. Arvioiduissa kuormituksissa erinäytteenottoväleillä havaitut suuret epävarmuudet saattavat rajoittaa laskelmien käyttöä joissakin tarkoituksissa. Epävarmuutta voidaan vähentää käyttämällä hyväksi edellisinä vuosina tehtyjä vedenlaatumittauksia. Luotettavin tapa epävarmuuden vähentämiseksi on jatkuvatoimisten vedenlaatumittareiden käyttäminen
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Zak, Susan K. "Estimating uncertainty of critical load models." Thesis, Lancaster University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.274231.
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Choudhary, P. A. "State estimation applied to gas distribution networks." Thesis, University of Manchester, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378007.
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The need to make more efficient use of energy resources by improved methods of control, the deferment of expensive pipework reinforcement or replacement and the requirement to accommodate different loading patterns on sections of the gas network have made the requirement for effective feedback control essential. Gas distribution systems are large and complex and a major problem in applying conventional feedback techniques is the cost and reliability of transmitting the data necessary for automatic control. In order to overcome these difficulties, state estimation techniques have been investigated as a means of providing information about a distribution system from a minimum number of measurement points. The theoretical background to the study is reviewed including the modelling technique and the results of experimental work which has been performed on a distribution network in order to verify the techniques developed are presented. The results show that state estimation techniques have considerable potential for this type of application.
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Moda, Hari Priya. "Non-Negative Least Square Optimization Model for Industrial Peak Load Estimation." Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/36003.
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Load research is the study of load characteristics on a power distribution system which helps planning engineer make decisions about equipment ratings and future expansion decisions. As it is expensive to collect and maintain data across the entire system, data is collected only for a sample of customers, where the sample is divided into groups based upon the customer class. These sample measurements are used to calculate the load research factors like kWHr-to-peak kW conversion factors, diversity factors and 24 hour average consumption as a function of class, month and day type. These factors are applied to the commonly available monthly billing kW data to estimate load on the system.
Among various customers on a power system, industrial customers form an important group for study as their annual kWHr consumption is among the highest. Also the errors with which the estimates are calculated are also highest for this class. Hence we choose the industrial class to demonstrate the Lawson-Hanson Non-Negative Least Square (NNLS) optimization technique to minimize the residual squared error between the estimated loads and the SCADA currents on the system. Five feeders with industrial dominant customers are chosen to demonstrate the improvement provided by the NNLS model. The results showed significant improvement over the Nonlinear Load Research Estimation (NLRE) method.Master of Science
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Xu, Yizheng. "Probabilistic estimation and prediction of the dynamic response of the demand at bulk supply points." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/probabilistic-estimation-and-prediction-of-the-dynamic-response-of-the-demand-at-bulk-supply-points(b9e427ec-7e5e-49a5-aec4-0f34032d71a9).html.
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The dynamic response of the demand is defined as the time-domain real and reactive power response to a voltage disturbance, and it represents the dynamic load characteristics. This thesis develops a methodology for probabilistic estimation and prediction of dynamic responses of the demand at bulk supply points. The main outcome of the research is being able to predict the contribution of different categories of loads to the total demand mix and their controllability without conducting detailed customer surveys or collecting smart meter data, and to predict the dynamic response of the demand without performing field tests. The prediction of the contributions of different load categories and their controllability and load characteristics in the near future (e.g., day ahead) plays an important role in system analysis and planning, especially in the short-term dispatch and control. However, the research related to this topic is missing in the publically available literature, and an approach needs to be developed to enable the prediction of the participation of different loads in total load mix, their controllability and the dynamic response of the demand. This research contributes to a number of areas, such as load forecasting, load disaggregation and load modelling. First, two load forecasting methodologies which have not been compared before are compared; and based on the results of comparison and considering the actual requirements in this research, a methodology is selected and used to predict both the real and reactive power. Second, a unique methodology for load disaggregation is developed. This methodology enables the estimation of the contributions of different load categories to the total demand mix and their controllability based on RMS measured voltage and real and reactive power. The confidence level of the estimation is also assessed. The methodology for disaggregation is integrated with the load forecasting tool to enable prediction of load compositions and dynamic responses of the demand. The prediction is validated with data collected from real UK power network. Finally, based on the prediction, an example of load shifting is used to demonstrate that different dynamic responses can be obtained based on the availability and redistribution of controllable devices and that load shifting decisions, i.e., demand side management actions, should be made based not only on the amount of demand to be shifted, but also on predicted responses before and after load shifting.
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Regulski, Pawel Adam. "Estimation of parameters of dynamic load models for voltage stability studies." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/estimation-of-parameters-of-dynamic-load-models-for-voltage-stabily-studies(db6176e0-c7df-4ad6-83f7-5772eb9f8421).html.
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Current environmental and economic trends have forced grid operators to maximize the utilization of the existing assets, which is causing systems to be operated closer to their stability limits than ever before. This requires, among other things, better knowledge and modelling of the existing power system equipment to increase the accuracy of the assessment of current stability margins.This research investigates the possibility of improving the quality of load modeling. The thesis presents a review of the traditional methods for estimation of load model parameters and proposes to use Improved Particle Swarm Optimization. Different algorithms are tested and compared in terms of accuracy, reliability and CPU requirements using computer simulations and real-data captured in a power system.Estimation of frequency and power components has also been studied in this thesis. A review of the existing methods has been provided and the use of an Unscented Kalman Filter proposed. This nonlinear recursive algorithm has been thoroughly tested and compared against selected traditional techniques in a number of experiments involving computer-generated signals as well as measurements obtained in laboratory conditions.
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Bengtsson, Fredrik. "Estimation of Indicated– and Load– Torque from Engine Speed Variations." Thesis, Linköping University, Department of Electrical Engineering, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-7097.
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The importance of control systems and diagnostics in vehicles are increasing and has resulted in several new methods to calculate better control signals. The performance can be increased by calculating these signals close to optimum, but that also require more and precise information regarding the system.
One of the wanted control signals are the crankshaft torque and the thesis presents two different methods to estimate this torque using engine speed variations. These methods are Modeling of the Crankshaft and Frequency Analysis. The methods are evaluated and implemented on for a four cylinder SAAB engine. Measurements are made in an engine test cell as well as a vehicle.
The results show that the Modeling of the Crankshaft method does not produce a satisfying estimation, with a difference of about 200% between estimated and calculated torque. On the other hand, the Frequency Analysis provides an accurate estimation of both mean and instantaneous indicated torque, with a maximum difference of ±20% between estimated and calculated torque.
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Kim, Jaeseok. "Automated matching control system using load estimation and microwave characterization." [Gainesville, Fla.] : University of Florida, 2008. http://purl.fcla.edu/fcla/etd/UFE0022883.
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Al-Wakeel, Ali. "Integrated load and state estimation using domestic smart meter measurements." Thesis, Cardiff University, 2016. http://orca.cf.ac.uk/93907/.
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The UK Government is promoting the decarbonisation of the power sector. The electrification of transport and heating, installation of distributed generators, development of smart grids and creation of an electricity and gas smart metering system are in progress. Higher penetrations of distributed generation and low carbon loads may lead to operational difficulties in distribution networks. Therefore, increased real-time monitoring and control becomes a necessary requirement. Distribution network operators will have available to them smart meter measurements to facilitate safe and cost-effective operation of distribution networks. This thesis investigates the application of smart meter measurements to extend the observability of distribution networks. Three main aspects were covered in this work: 1. The development of a cluster analysis algorithm to extract consumption patterns from smart meter measurements. The The k-means based cluster analysis algorithm was demonstrated on measurements that were obtained from the Irish Smart Metering Trials. Daily and segmented load profiles of individual and aggregated domestic smart meters were clustered. 2. The development of a load estimation method to estimate missing and future measurements of smart meters. The load estimation algorithm uses the outputs of the clustering algorithm; and investigates the application of different distance functions to estimate any lost measurements. Different durations of lost measurements were simulated to assess the accuracy of the estimated load. 3. The development of an integrated load and state estimation algorithm to extend the observability of distribution networks. The developed load estimator provides pseudo measurements to an Iteratively Re-Weighted Least Squares (IRWLS) state estimator. The capability of the IRWLS state estimator was investigated using measurements from a low voltage microgrid. The IEEE 33 bus medium voltage distribution network was used to assess the performance of the integrated load and state estimation algorithm. The developed load and state estimator was capable of estimating the voltage magnitude and phase angle, at each busbar of the distribution network, with high accuracy. For one hour of missing measurements, the Mean Absolute Percentage Error (MAPE) of the estimated voltage magnitude was less than 0.03%. For 24 hours of missing measurements, the estimated voltage magnitudes had a MAPE that was less than 0.5%.
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Muhunthan, Bala. "Traffic loads for estimating the endurances and residual strength of highway bridges /." Title page, abstract and contents only, 1996. http://web4.library.adelaide.edu.au/theses/09ENS/09ensm952.pdf.
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Jones, Amber Spackman. "Estimating Total Phosphorus and Total Suspended Solids Loads from High Frequency Data." DigitalCommons@USU, 2008. https://digitalcommons.usu.edu/etd/205.
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Frequently measured turbidity was examined as a surrogate for total phosphorus (TP) and total suspended solids (TSS) loads at two locations in the Little Bear River, Utah, USA. Using regression techniques, equations were developed for TP and TSS as functions of turbidity. The equations accounted for censored data, and additional explanatory variables to represent hydrological conditions were considered for inclusion in the equations. By using the resulting surrogate relationships with high frequency turbidity measurements, high frequency estimates of TP and TSS concentrations were calculated. To examine the effect of sampling frequency, reference loads were determined from the concentration records for two water years. The concentration records were artificially decimated to represent various frequencies of manual grab sampling from which annual loads were calculated and compared to the reference loads.
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Pallos, Lorant Laszlo. "Estimating population totals with auxiliary information with applications to electric utility load research." Diss., Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/24546.
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Borthwick, James Robert. "Mining haul truck pose estimation and load profiling using stereo vision." Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/21423.
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Earthmoving at surface mines centers around very large excavators (mining shovels) that remove material from the earth and place it into haul trucks. During this loading process, the truck may be inadvertently loaded in a manner that injures the truck driver, or that results in an asymmetrically loaded or overloaded truck. This thesis presents two systems which aim to assist with haul truck loading: 1) a stereo-vision based system that determines a haul truck's pose relative to the shovel housing as part of an operator loading assistance system, and 2) a system that can determine a haul truck's load volume and distribution as the truck is being loaded. The haul truck pose estimation system is significant in that it is the first six-degrees of freedom truck pose estimation system that is sufficiently fast and accurate to be applicable in an industrial mine setting. Likewise, it is the first time that a system capable of determining a haul truck's volume as it is being loaded has been described. To achieve this, a fast, resolution independent nearest neighbour search is presented and used within Iterative Closest Point (ICP) for point cloud registration. It also shown, for the first time, to the best of our knowledge, the possibility of using the Perspective-n-Point (PnP) pose estimation technique to estimate the pose a range-sensor derived point cloud model, and to use the same technique to verify the pose given by ICP. Camera errors, registration errors, pose estimation errors, volume estimation errors and computation times are all reported.
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Cleaveland, John P. "Loadcal : a microcomputer simulation for estimating heating and cooling loads for commercial buildings." Thesis, Georgia Institute of Technology, 1985. http://hdl.handle.net/1853/23099.
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Silva, Sérgio Ferreira da. "Identificação de torque de carga em motores de indução usando abordagem baseada em sistemas Fuzzy." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/18/18153/tde-03092007-092234/.
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Os motores de indução trifásicos são largamente usados em vários setores da indústria. O dimensionamento da potência adequada de um motor de indução ou assíncrono trifásico, em função do comportamento das cargas acopladas ao eixo, continua em alguns casos impreciso pela falta de conhecimento mais completo do comportamento das cargas. A proposta deste trabalho consiste na utilização de sistemas Fuzzy como uma alternativa aos métodos tradicionais para levantamento do comportamento de carga e, em processos de controle, onde há a necessidade de conhecimento do comportamento do conjugado aplicado ao eixo do motor, enfocando diversos tipos de cargas encontrados em indústrias. Resultados de simulações são apresentados para validar a proposta deste trabalho.The three phase induction motors are widely used in all industrial sectors. The selection procedure of the motor for a particular application is sometimes inaccurate due to the lack of complete knowledge about the load connected to its shaft. The proposal of this work consists of using Fuzzy system as an alternative tool to the classical methods for extraction of the load behavior and, in control process, where knowledge of the torque behavior applied to the motor shaft are need, focusing several types of loads found in industries. Simulation results are presented to validate the proposal of this work.
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Al-Othman, Abdul Rahman K. "Uncertainty modelling in power system state estimation." Thesis, Brunel University, 2004. http://bura.brunel.ac.uk/handle/2438/7889.
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As a special case of the static state estimation problem, the load-flow problem is studied in this thesis. It is demonstrated that the non-linear load-flow formulation may be solved by real-coded genetic algorithms. Due to its global optimisation ability, the proposed method can be useful for off-line studies where multiple solutions are suspected. This thesis presents two methods for estimating the uncertainty interval in power system state estimation due to uncertainty in the measurements. The proposed formulations are based on a parametric approach which takes in account the meter inaccuracies. A nonlinear and a linear formulation are proposed to estimate the tightest possible upper and lower bounds on the states. The uncertainty analysis, in power system state estimation, is also extended to other physical quantities such as the network parameters. The uncertainty is then assumed to be present in both measurements and network parameters. To find the tightest possible upper and lower bounds of any state variable, the problem is solved by a Sequential Quadratic Programming (SQP) technique. A new robust estimator based on the concept of uncertainty in the measurements is developed here. This estimator is known as Maximum Constraints Satisfaction (MCS). Robustness and performance of the proposed estimator is analysed via simulation of simple regression examples, D.C. and A.C. power system models.
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Reddi, Yashren. "Modelling, estimation and control of a twin-helicopter slung load transportation system." Doctoral thesis, Faculty of Engineering and the Built Environment, 2018. http://hdl.handle.net/11427/29986.
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The development of a control system to transport and assemble cargo using two helicopters is presented in this thesis. It is more economical to use multiple lower cost helicopters in a coordinated manner to carry cargo than to use a single high performance helicopter for the transportation task. The reason for the generally higher cost of hiring high performance helicopters, is because they are not required often, and so, remain idle for most of their lifetime. Thus, using less specialised, lower performing helicopters to share the load is cheaper. Beyond just sharing the load of the cargo, the objective in this investigation is to control the attitude such that precise placement of the cargo can be made. This objective cannot be achieved using a single helicopter, unless a sophisticated tethering mechanism is developed. The installation of wind-turbine blades, powerline towers and radio masts in remote locations, are examples of where the application of this technology may be useful. The investigation of this thesis is around modelling, estimation and control of the twinhelicopter slung load transportation system. The title reflects the investigation that was required to be done to determine whether a scheme could be realisable. To test the concept, an experimental platform was developed. A small, light-weight and high performance avionics system was designed and interfaced to the helicopters. The experimentation was done indoors, and hence, the flying volume was limited. For the purpose of feedback and analysis, a motion capture system was developed to track the position and attitude of the helicopters. A high-fidelity mathematical model of a small-scale helicopter was developed. Estimation algorithms were then developed to optimally fuse the data from the instrumentation designed. The data was then used in a system identification exercise to find the parameters that capture the dynamics of the helicopter. The full constrained model of the twin-helicopter slung load dynamics was then developed. The high-fidelity multivariable, interacting system was then linearised to generate a set of uncertain plants. Unexpected resonant modes were investigated using modal analysis to understand their source. Robust controllers were designed using Quantitative Feedback Theory (QFT) for the individual helicopter attitude and altitude loops. A solution was found for the twin-helicopter load transportation system by decoupling the plant with a static pre-compensator and then designing a decentralised QFT controller for the 6 × 6 plant. The effort of this thesis is towards the (practical) realisation of a twin-helicopter aerial crane capable of attitude control; the architecture for the industrialisation of the twin-helicopter load transportation system is proposed.
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Crawford, Allan Charles. "Credit rationing with an individual short-side rule : estimation for business loans in Canada." Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/27060.
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It is generally accepted that rationing occurs in loan markets with demand of some borrowers exceeding desired supply by lenders at prevailing interest rates. Previous empirical studies of credit rationing use established disequilibrium econometric methods to estimate structural models of business loan markets. This study argues that existing disequilibrium techniques are not suitable for analyzing credit rationing since they ignore features of loan markets emphasized in the theoretical literature. While recent theory distinguishes between equilibrium and disequilibrium categories of credit rationing, existing empirical work allows only the latter to exist. In addition the traditional empirical model does not derive loan equations from micro foundations despite a theoretical focus on loan determination at the individual borrower level. Instead, equations are constructed by assuming aggregate loan quantity corresponds to the minimum of aggregate supply and demand. These inconsistencies with theory suggest that estimates of rationing from the traditional model are unreliable.
Unlike traditional methods the empirical model developed in this study derives aggregate equations from a micro approach to loan determination. Individual loan sizes are determined by the minimum of borrower-specific supply and demand functions and explicit aggregation across all borrowers gives estimating equations with desired properties. An attractive feature of the new model is that it yields the first estimates of equilibrium credit rationing. This allowance for both equilibrium and disequilibrium rationing, together with the micro foundations, means that the proposed model provides greater consistency between theoretical and applied work than has been previously possible. The new model is applied to the market for business loans from Canadian banks for the period 1968 to 1979. Results indicate that rationing is empirically significant as total rationing averages approximately one-third of aggregate flow demand for loans. Equilibrium rationing appears to be an important phenomenon since it exceeds disequilibrium rationing each period. However, intertemporal fluctuations in total rationing are caused primarily by changes in disequilibrium rationing. A comparison of the new and traditional models shows that rationing estimates are greater in the new approach with much of the difference attributable to the amount of equilibrium rationing in that model.Arts, Faculty of
Vancouver School of Economics
Graduate
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Park, Hee Mun. "Use of Falling Weight Deflectometer Multi-Load Level Data for Pavement Strength Estimation." NCSU, 2001. http://www.lib.ncsu.edu/theses/available/etd-20011120-151143.
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PARK, HEE MUN. Use of Falling Weight Deflectometer Multi-Load Level Data for Pavement Strength Estimation. (Under the direction of Y. Richard, Kim).The objective of this study is to describe a mechanistic-empirical approach to developing an analysis method for assessing pavement layer conditions and estimating the remaining life of flexible pavements using multi-load level Falling Weight Deflectometer (FWD) deflections. A dynamic finite element program, incorporating a stress-dependent soil model, was developed to generate the synthetic deflection database. Based on this synthetic database, the relationships between surface deflections and critical pavement responses, such as stresses and strains in each individual layer, have been established.A condition assessment procedure for pavement layers using multi-load level FWD deflections is presented in this study. The results indicate that the proposed procedure can estimate the base and subgrade layer conditions. However, large variations were observed in the relationships between the DBCI and desg values and the subgrade CBR values for aggregate base pavements. A FWD test with a load of 53 kN or less does not result in any apparent nonlinear behavior of the subgrade in aggregate base pavements. With regard to the condition assessment of the asphalt concrete (AC) layer, the AC layer modulus and the tensile strain at the bottom of the AC layer are found to be better indicators than the deflection basin parameter.The procedures for performance prediction of fatigue cracking and rutting are developed for flexible pavements. The drastically increasing trend in fatigue cracking with time may not be predicted accurately using the proposed procedure. Such trends may be due to the environmental effects and the inconsistent distress measurements. Predicted rut depths using both single and multi-load level deflections show good agreement with measured rut depths over a wide range of rutting potential. However, the procedure using single load level deflections consistently underpredicts the rut depths. This observation demonstrates that the rutting prediction procedure using multi-load level deflections can estimate an excessive level of rutting quite well and, thus, improve the quality of prediction for rutting potential in flexible pavements.
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Rydén, Patrik. "Estimation of the reliability of systems described by the Daniels Load-Sharing Model." Licentiate thesis, Umeå universitet, Matematisk statistik, 1999. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-46724.
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We consider the problem of estimating the failure stresses of bundles (i.e. the tensile forces that destroy the bundles), constructed of several statisti-cally similar fibres, given a particular kind of censored data. Each bundle consists of several fibres which have their own independent identically dis-tributed failure stresses, and where the force applied on a bundle at any moment is distributed equally between the unbroken fibres in the bundle. A bundle with these properties is an example of an equal load-sharing sys-tem, often referred to as the Daniels failure model. The testing of several bundles generates a special kind of censored data, which is complexly struc-tured. Strongly consistent non-parametric estimators of the distribution laws of bundles are obtained by applying the theory of martingales, and by using the observed data. It is proved that random sampling, with replace-ment from the statistical data related to each tested bundle, can be used to obtain asymptotically correct estimators for the distribution functions of deviations of non-parametric estimators from true values. In the case when the failure stresses of the fibres are described by a Weibull distribution, we obtain strongly consistent parametric maximum likelihood estimators of the distribution functions of failure stresses of bundles, by using the complexly structured data. Numerical examples illustrate the behavior of the obtained estimators.
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Ronquist, Anton, and Birger Winroth. "Estimation and Compensation of Load-Dependent Position Error in a Hybrid Stepper Motor." Thesis, Linköpings universitet, Reglerteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-129554.
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Hybrid stepper motors are a common type of electric motor used throughout industry thanks to its low-cost, high torque at low speed and open loop positioning capabilities. However, a closed loop control is often required for industrial applications with high precision requirements. The closed loop control can also be used to lower the power consumption of the motor and ensure that stalls are avoided. It is quite common to utilise a large and costly position encoder or resolver to feedback the position signal to the control logic. This thesis has explored the possibility of using a low-cost position sensor based on Hall elements. Additionally, a sensorless estimation algorithm, using only stator winding measurements, has been investigated both as a competitive alternative and as a possible complement to the position sensor. The thesis work summarises and discusses previous research attempts to adequately measure or estimate and control the hybrid stepper motors position and load angle without using a typical encoder or resolver. Qualitative results have been produced through simulations prior to implementation and experimental testing. The readings from the position sensor is subject to noise, owing to its resolution and construction. The position signal has been successfully filtered, improving its accuracy from 0.56° to 0.25°. The output from the sensorless estimation algorithm is subject to non-linear errors caused by errors in phase voltage measurements and processing of velocity changes. However, the dynamics are reliable at constant speeds and could be used for position control.
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Ryan, Keri Lynn Chopra Anil K. "Estimating the seismic response of base-isolated buildings including torsion, rocking, and axial-load effects /." Berkeley : Earthquake Engineering Research Center, University of California, 2005. http://nisee.berkeley.edu/elibrary/.
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Previously published as first author's thesis (Ph. D. in Engineering--University of California, Berkeley, 2004)."June 2005." Includes bibliographical references. Also available as an electronic document from the Earthquake Engineering Online Archive Earthquake: http://nisee.berkeley.edu/elibrary.
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Khan, Muhammad Ayaz. "State Estimation and Voltage Phasor Measurements in Distribution Networks." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018.
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The thesis faces the problem of the use of phasor measurement units (PMU) for the state estimation in distribution networks, and in particular the problem of a suitable phasor estimation in different buses of a distribution network in absence of proper time synchronization with the universal time reference. In particular, an approach recently proposed by Mingotti et al. to obtain an equivalent synchronization, starting from asynchronous measurement has been presented and tested. This method assumes the availability of a distributed measurement system where each remote unit is a power meter. The algorithm implemented in Matlab by Mingotti et al. has been studied and tested by a comparison with the load flow results provided by the Electromagnetic Transient Program (EMTP-RV). The algorithm adopts two different methods for voltage phasor estimation, the first calculate the phasors as a linear combination of measured voltages, the second makes use of the longitudinal equivalent impedances of the network branches. In order to tune the load flow calculation environment, different case studies have been analyzed, and in particular the European Medium Voltage distribution test network and the European Low voltage distribution test network proposed by CIGRE Task Force C6.04.02. During the analysis, for each bus, voltages, currents and phase displacements are calculated and compared with the benchmark results reported in the Cigré brochure. A four-buses network has been considered to test both methods of the above mentioned algorithm. The obtained results are very close to the one provided by EMTP. The accuracy of the algorithm appears to get worse in case of lightly loaded network, a behaviour that is justified by the small phase displacements that the voltages show in these condition. The studied equivalent synchronization procedure can be usefully implemented to achieve a widespread monitoring of a power network at affordable cost.
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Chen, Jiaxiong. "Power System State Estimation Using Phasor Measurement Units." UKnowledge, 2013. http://uknowledge.uky.edu/ece_etds/35.
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State estimation is widely used as a tool to evaluate the real time power system prevailing conditions. State estimation algorithms could suffer divergence under stressed system conditions. This dissertation first investigates impacts of variations of load levels and topology errors on the convergence property of the commonly used weighted least square (WLS) state estimator. The influence of topology errors on the condition number of the gain matrix in the state estimator is also analyzed. The minimum singular value of gain matrix is proposed to measure the distance between the operating point and state estimation divergence.
To study the impact of the load increment on the convergence property of WLS state estimator, two types of load increment are utilized: one is the load increment of all load buses, and the other is a single load increment. In addition, phasor measurement unit (PMU) measurements are applied in state estimation to verify if they could solve the divergence problem and improve state estimation accuracy.
The dissertation investigates the impacts of variations of line power flow increment and topology errors on convergence property of the WLS state estimator. A simple 3-bus system and the IEEE 118-bus system are used as the test cases to verify the common rule. Furthermore, the simulation results show that adding PMU measurements could generally improve the robustness of state estimation.
Two new approaches for improving the robustness of the state estimation with PMU measurements are proposed. One is the equality-constrained state estimation with PMU measurements, and the other is Hachtel's matrix state estimation with PMU measurements approach. The dissertation also proposed a new heuristic approach for optimal placement of phasor measurement units (PMUs) in power system for improving state estimation accuracy. In the problem of adding PMU measurements into the estimator, two methods are investigated. Method I is to mix PMU measurements with conventional measurements in the estimator, and method II is to add PMU measurements through a post-processing step. These two methods can achieve very similar state estimation results, but method II is a more time-efficient approach which does not modify the existing state estimation software.
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Estes, Steven Douglas. "Power system analysis suite for Windows." Thesis, This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-02132009-170931/.
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Johansson, Nils. "Estimation of fatigue life by using a cyclic plasticity model and multiaxial notch correction." Thesis, Linköpings universitet, Mekanik och hållfasthetslära, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-158095.
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Mechanical components often possess notches. These notches give rise to stress concentrations, which in turn increases the likelihood that the material will undergo yielding. The finite element method (FEM) can be used to calculate transient stress and strain to be used in fatigue analyses. However, since yielding occurs, an elastic-plastic finite element analysis (FEA) must be performed. If the loading sequence to be analysed with respect to fatigue is long, the elastic-plastic FEA is often not a viable option because of its high computational requirements. In this thesis, a method that estimates the elastic-plastic stress and strain response as a result of input elastic stress and strain using plasticity modelling with the incremental Neuber rule has been derived and implemented. A numerical methodology to increase the accuracy when using the Neuber rule with cyclic loading has been proposed and validated for proportional loading. The results show fair albeit not ideal accuracy when compared to elastic-plastic finite element analysis. Different types of loading have been tested, including proportional and non-proportional as well as complex loadings with several load reversions. Based on the computed elastic-plastic stresses and strains, fatigue life is predicted by the critical plane method. Such a method has been reviewed, implemented and tested in this thesis. A comparison has been made between using a new damage parameter by Ince and an established damage parameter by Fatemi and Socie (FS). The implemented algorithm and damage parameters were evaluated by comparing the results of the program using either damage parameter to fatigue experiments of several different load cases, including non-proportional loading. The results are fairly accurate for both damage parameters, but the one by Ince tend to be slightly more accurate, if no fitted constant to use in the FS damage parameter can be obtained.
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Irshad, Saba, and Purna Chandra Nepal. "Rise Over Thermal Estimation Algorithm Optimization and Implementation." Thesis, Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-4023.
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The uplink load for the scheduling of Enhanced-Uplink (E-UL) channels determine the achievable data rate for Wideband Code Division Multiple Access (WCDMA) systems, therefore its accurate measurement carries a prime significance. The uplink load also known as Rise-over-Thermal (RoT), which is the quotient of the Received Total Wideband Power (RTWP) and the Thermal Noise Power floor. It is a major parameter which is calculated at each Transmission Time Interval (TTI) for maintaining cell coverage and stability. The RoT algorithm for evaluation of uplink load is considered as a complex and resource demanding among several Radio Resource Management (RRM) algorithms running in a radio system. The main focus of this thesis is to study RoT algorithm presently deployed in radio units and its possible optimization by reducing complexity of the algorithm in terms of memory usage and processing power. The calculation of RoT comprises three main blocks a Kalman filter, a noise floor estimator and the RoT computation. After analyzing the complexity of each block it has been established that the noise floor estimator block is consuming most of the processing power producing peak processor load since it involves many complex floating point calculations. However, the other blocks do not affect the processing load significantly. It was also observed that some block updates can be reduced in order to decrease the average load on the processor. Three techniques are proposed for reducing the complexity of the RoT algorithm, two for the reduction of peak load and one for the reduction of average load. For reducing the peak load, an interpolation approach is used instead of performing transcendental mathematical calculations. Also, the calculations involving noise floor estimation are extended over several TTIs by keeping in view that the estimation is not time critical. For the reduction of average load, the update rate for the Kalman Filter block is reduced. Based on these optimization steps, a modified algorithm for RoT computation with reduced complexity is proposed. The proposed changes are tested by means of MATLAB simulations demonstrating the improved performance with consistency in the output results. Finally, an arithmetic operation count is done using the hardware manual of Power PC (PPC405) used in Platform 4, which gives a rough estimate of decrease in the percentage of calculations after optimization.saabairshad@gmail.com