Tesis: "Observer analysis"

1

Franco, Nicola. "Distributed Observer Analysis and Design". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/19642/.

Texto completo

Resumen

A Distributed observer design is described for estimating the state of a continuous-time, input free, linear system. This thesis explains how to construct the local estimators, which comprise the observer inputs and outputs, and it is shown which are the requirements to deal with this structure. Every agent senses an output signal from the system and distributes it across a fixed-time network to its neighbors. The information flow increases the capability of each agent to estimate the state of the system and uses collaboration to improve the quality of data. The proposed solution has several positive features compared to recent results in the literature, which include milder assumptions on the network connectivity and the maximum dimension of the state of each observer does not exceed the order of the plant. The conditions are reduced to certain detectability requirements for each cluster of agents in the network, where a cluster is identified as a subset of agents that satisfy specific properties. Instead, the dimension of each observer is reduced to the number of possible observable states of the system, collected by the agent and by the neighbors.

Los estilos APA, Harvard, Vancouver, ISO, etc.

2

Bravi, I. "INTER-OBSERVER AND INTRA-OBSERVER AGREEMENT IN THE ANALYSIS OF OESOPHAGEAL PH-IMPEDANCE TRACINGS". Doctoral thesis, Università degli Studi di Milano, 2013. http://hdl.handle.net/2434/216406.

Texto completo

Resumen

AIM Information resulting from oesophageal 24h pH-impedance monitoring (pH-MII) may have important consequences for patients’ management. Aims of this study were 1) to evaluate agreement for number of reflux episodes and symptom/reflux association indexes in MII-pH tracings analysis between and within three experienced observers working in different European Centers, 2) to evaluate the predictivity of a shorter manual analysis targeted to the two-minutes window periods before each symptomatic episode with regards to the traditional. MATERIAL AND METHODS Forty consecutive pH-MII tracings of patients (23 women, median age 55 years) referred for suspected oesophageal (n=24) or extra-oesophageal (n=16) GORD symptoms in two Northern Italian Centers were included (20 tracings/Center). After automatic analysis (MMS, Enschede, The Nederlands), tracings were duplicated and anonymized. Three expert observers blindly performed the traditional manual analysis on the 40 duplicated tracings, erasing or adding reflux episodes according to their judgment based on the Oporto Criteria. The first manual analysis was performed in a sequential order, the second one in a randomly assigned order. Subsequently a short manual analysis was also blindly performed. Values of both symptom association indexes (Symptom Index=S.I. and Symptom Association Probability=S.A.P.) were transformed into binary response (i.e. positive or negative). Inter- and intra-observer agreement was calculated with Cohen’s Coefficient (k) and/or with percentage of agreement. RESULTS Inter-observer agreement on acid reflux was excellent between the three observers for both S.I. and S.A.P. (K=1.0; 100%), whereas considering non-acid reflux it was high for S.I. (95%, 92.5% and 95% of concordance for observer 1,2 and 3 respectively) and moderate for S.A.P. (K=0.35; 85% between observer 1 and 2, K=0.36; 82.5% between observer 1 and 3, K=0.23; 87.5% between observer 2 and 3). Intra-observer agreement on acid reflux was good to excellent for both S.I. (K=0.77; 95% for observer 1 and 2 and K=1.0; 100% for observer 3), and S.A.P. (K=0.80; 95% , K=0.72; 92.5% and K=1.0; 100% for observer 1, 2 and 3 respectively). Intra-observer agreement on non-acid reflux was high for S.I. (97.5%, 95% and 97.5% of concordance for observer 1, 2 and 3 respectively) and moderate for S.A.P. (K=0.48; 85% and K=0.54; 90% for observer 1 and 3 and good for observer 2, K=0.79; 2.5%). Considering all the three observers the short analysis was predictive of the traditional one for both S.I., 88% and 98% of the tracings for acid and non-acid reflux, respectively and S.A.P., 99% and 97% of the tracings for acid and non-acid reflux, respectively. CONCLUSIONS We found a good inter- and intra-observer agreement for symptom/reflux association indexes, especially when considering acid reflux. Moreover we demonstrated that short analysis was highly predictive of the traditional manual analysis, suggesting that the short one could be used in routine clinical practice with considerable savings.

Los estilos APA, Harvard, Vancouver, ISO, etc.

3

Mpungose, Sandile Khayalethu Derrick. "Complete denture occlusion: intra and inter observer analysis". Thesis, University of Western Cape, 2014. http://hdl.handle.net/11394/3352.

Texto completo

Resumen

Magister Scientiae Dentium - MSc(Dent)
Aim: The aim of this study was to investigate the accuracy, intra- and inter-observer reliability of identifying occlusal markings made by articulating paper on complete dentures intra-orally. Methods: A series of photographs of 14 tissue borne complete dentures with occlusal markings was obtained. Articulating paper was used intra-orally at the delivery visit to make the occlusal markings. The denture sets were divided into two groups. Group 1 comprised pictures of the 14 complete lower dentures on their own, and group 2 comprised pictures of the same 14 lower dentures together with their opposing upper denture. The two groups of images were loaded into a Microsoft PowerPoint presentation as well as Keynote. Two experienced observers analysed the complete dentures independently and noted the number and distribution of the markings that they felt required adjustment. They differed, but discussed these and reached consensus. These data served as the control. Three groups of observers (10 per group) were then asked to analyse the occlusal markings of the 2 groups of denture images twice, with a two-week interval between each assessment. Before each subsequent assessment, the images were randomised by means of computer-generated random number sequence. The mean number of markings was established for each group and compared with the control mean. Intra-rater reliability was established by comparing the difference of the means of sequential observations for each rater by establishing the z-value. Inter-rater reliability within each group was established by means of analysis of variance. Results: Considering all the data, in only 17 instances (of the possible 60), did observers’ mean scores not differ from the control mean scores with good intra-rater reliability. In all other 43 instances the observers’ mean scores differed from the control mean scores and/or displayed poor intra-rater reliability. Considerable variation in inter-rater reliability was also found within every group of observers. Conclusion: The results indicate that observers are generally unable to reliably identify occlusal markings warranting occlusal adjustment, made by articulating paper on a lower complete denture. Clinical significance: Articulating paper should not be used intra-orally when delivering removable complete dentures.

Los estilos APA, Harvard, Vancouver, ISO, etc.

4

Al-Raisi, Seema F. A. R. "Machine learning-based human observer analysis of video sequences". Thesis, Loughborough University, 2017. https://dspace.lboro.ac.uk/2134/33581.

Texto completo

Resumen

The research contributes to the field of video analysis by proposing novel approaches to automatically generating human observer performance patterns that can be effectively used in advancing the modern video analytic and forensic algorithms. Eye tracker and eye movement analysis technology are employed in medical research, psychology, cognitive science and advertising. The data collected on human eye movement from the eye tracker can be analyzed using the machine and statistical learning approaches. Therefore, the study attempts to understand the visual attention pattern of people when observing a captured CCTV footage. It intends to prove whether the eye gaze of the observer which determines their behaviour is dependent on the given instructions or the knowledge they learn from the surveillance task. The research attempts to understand whether the attention of the observer on human objects is differently identified and tracked considering the different areas of the body of the tracked object. It attempts to know whether pattern analysis and machine learning can effectively replace the current conceptual and statistical approaches to the analysis of eye-tracking data captured within a CCTV surveillance task. A pilot study was employed that took around 30 minutes for each participant. It involved observing 13 different pre-recorded CCTV clips of public space. The participants are provided with a clear written description of the targets they should find in each video. The study included a total of 24 participants with varying levels of experience in analyzing CCTV video. A Tobii eye tracking system was employed to record the eye movements of the participants. The data captured by the eye tracking sensor is analyzed using statistical data analysis approaches like SPSS and machine learning algorithms using WEKA. The research concluded the existence of differences in behavioural patterns which could be used to classify participants of study is appropriate machine learning algorithms are employed. The research conducted on video analytics was perceived to be limited to few iii projects where the human object being observed was viewed as one object, and hence the detailed analysis of human observer attention pattern based on human body part articulation has not been investigated. All previous attempts in human observer visual attention pattern analysis on CCTV video analytics and forensics either used conceptual or statistical approaches. These methods were limited with regards to making predictions and the detection of hidden patterns. A novel approach to articulating human objects to be identified and tracked in a visual surveillance task led to constrained results, which demanded the use of advanced machine learning algorithms for classification of participants The research conducted within the context of this thesis resulted in several practical data collection and analysis challenges during formal CCTV operator based surveillance tasks. These made it difficult to obtain the appropriate cooperation from the expert operators of CCTV for data collection. Therefore, if expert operators were employed in the study rather than novice operator, a more discriminative and accurate classification would have been achieved. Machine learning approaches like ensemble learning and tree based algorithms can be applied in cases where a more detailed analysis of the human behaviour is needed. Traditional machine learning approaches are challenged by recent advances in the field of convolutional neural networks and deep learning. Therefore, future research can replace the traditional machine learning approaches employed in this study, with convolutional neural networks. The current research was limited to 13 different videos with different descriptions given to the participants for identifying and tracking different individuals. The research can be expanded to include any complicated demands with regards to changes in the analysis process.

Los estilos APA, Harvard, Vancouver, ISO, etc.

5

Liu, Chuang. "Relaxed stability analysis for fuzzy-model-based observer-control systems". Thesis, King's College London (University of London), 2016. https://kclpure.kcl.ac.uk/portal/en/theses/relaxed-stability-analysis-for-fuzzymodelbased-observercontrol-systems(082673fa-9a83-4cda-8622-9358ed8d7118).html.

Texto completo

Resumen

Fuzzy-model-based (FMB) control scheme is an efficient approach to conduct stability analysis for nonlinear systems. Both Takagi-Sugeno (T-S) FMB and polynomial fuzzy-model-based (PFMB) control systems have been widely investigated. In this thesis, the stability analysis of FMB control systems is conducted via Lyapunov stability theory. The main contribution of the thesis is improving the applicability of T-S FMB and PFMB control strategies by relaxing stability conditions and designing fuzzy observer-controller, which is presented in the following three parts: 1) The stability conditions of FMB control systems are relaxed such that the FMB control strategy can be applied to a wider range of nonlinear systems. For T-S FMB control systems, higher order derivatives of Lyapunov function (HODLF) are employed, which generalizes the commonly used first order derivative. For PFMB control systems, Taylor series membership functions (TSMF) are brought into stability conditions such that the relation between membership grades and system states is expressed. 2) Two types of T-S fuzzy observer-controller are designed such that the T-S FMB control strategy can be applied to systems with unmeasurable states. For the first type, the T-S fuzzy observer with unmeasurable premise variables is designed to estimate the system states and then the estimated states are employed for state-feedback control of nonlinear systems. Convex stability conditions are obtained through matrix decoupling technique. For the second type, the T-S fuzzy functional observer is designed to directly estimate the control input instead of the system states, which can reduce the order of the observer. A new form of fuzzy functional observer is proposed to facilitate the stability analysis such that the observer gains can be numerically obtained and the stability can be guaranteed simultaneously. 3) The polynomial fuzzy observer-controller with unmeasurable premise variables is designed for systems with unmeasurable states. Although the consideration of the polynomial fuzzy model and unmeasurable premise variables enhances the applicability of the FMB control strategy, it leads to non-convex stability conditions. Therefore, two methods are applied to derive convex stability conditions: refined completing square approach and matrix decoupling technique. Additionally, the designed polynomial fuzzy observer-controller is extended for systems where only sampled-output measurements are available. Furthermore, the membership functions of the designed polynomial observer-controller are optimized by the improved gradient descent method. Simulation examples are provided to demonstrate and verify the theoretical analysis.

Los estilos APA, Harvard, Vancouver, ISO, etc.

6

Spaulding, Raymond Leon. "Diet and observer bias in scat analysis of gray wolves". Thesis, The University of Arizona, 1996. http://hdl.handle.net/10150/291507.

Texto completo

Resumen

I analyzed 1,182 gray wolf (Canis lupus) scats, representing summer diet in 1988-1990, collected from 9 packs in northwest Alaska. Using a linear regression model, I determined the biomass of prey species consumed using relative estimated bulk and frequency of occurrence of prey types in scats. There were no significant differences (P < 0.05) between methods in percent biomass of prey consumed and ranking of prey types. Caribou (Rangifer tarandus), moose (Alces alces), microtines, and birds composed 47.0, 21.9, 10.6, and 13.8%, of prey items, respectively. Ungulates composed 90.1%, birds 6.7%, and microtines 0.5% of biomass consumed. Ungulates composed 3.4%, birds 50.4%, and microtines 38.5% of numbers of individuals consumed. Significant (P < 0.05) observer bias was found in the detection and frequency of prey types in the analysis of 1,052 scats by multiple observers.

Los estilos APA, Harvard, Vancouver, ISO, etc.

7

El-Shafey, Mohamed Hassan. "Linear continuous-time system identification and state observer design by modal analysis". Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/28666.

Texto completo

Resumen

A new approach to the identification problem of linear continuous-time time-invariant systems from input-output measurements is presented. Both parametric and nonparametric system models are considered. The new approach is based on the use of continuous-time functions, the modal functions, defined in terms of the system output, the output derivatives and the state variables under the assumption that the order n of the observable system is known a priori. The modal functions are obtained by linear filtering operations of the system output, the output derivatives and the state variables so that the modal functions are independent of the system instantaneous state. In this case, the modal functions are linear functions of the input exponential modes, and they contain none of the system exponential modes unlike the system general response which contains modes from both the system and the input. The filters parameters, the modal parameters are estimated using linear regression techniques. The modal functions and the modal parameters of the output and its derivatives are used to identify parametric input-output and state models of the system. The coefficients of the system characteristic polynomial are obtained by solving n algebraic equations formed from the estimates of the modal parameters. Estimates of the parameters associated with the system zeros are obtained by solving another set of linear algebraic equation. The system frequency response and step response are estimated using the output modal function. The impulse response is obtained by filtering the estimated step response using the output first derivative modal parameters. A new method is presented to obtain the system poles as the eigenvalues of a data matrix formed from the system free response. The coefficients of the system characteristic polynomial are obtained from the data matrix through a simple recursive equation. This method has some important advantages over the well known Prony's method. The state modal functions are used to obtain a minimum-time observer that gives the continuous-time system state as a direct function of input-output samples in n sampling intervals.
Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate

Los estilos APA, Harvard, Vancouver, ISO, etc.

8

Bharath, Ranjeetha. "Nonlinear observer design and synchronization analysis for classical models of neural oscillators". Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/83684.

Texto completo

Resumen

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2013.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 37-38).
This thesis explores four nonlinear classical models of neural oscillators, the Hodgkin- Huxley model, the Fitzhugh-Nagumo model, the Morris-Lecar model, and the Hindmarsh-Rose model. Analysis techniques for nonlinear systems were used to develop a set of observers and perform synchronization analysis on the aforementioned neural systems. By using matrix analysis techniques, a study of biological background and motivation, and MATLAB simulation with mathematical computation, it was possible to do a preliminary contraction and nonlinear control systems structural study of these classical neural oscillator models. Neural oscillation and signaling models are based fundamentally on the biological function of the neuron, with behavior mediated through the channeling of ions across a cell membrane. The variable assumed to be measured for this study is the voltage or membrane potential, which could be measured empirically through the use of a neuronal force-clamp system. All other variables were estimated by using the partial state and full state observers developed here. Preliminary observer rate convergence analysis was done for the Fitzhugh-Nagumo system, and preliminary synchronization analysis was done for both the Fitzhugh-Nagumo and the Hodgkin- Huxley systems. It was found that by using a variety of techniques and mathematical matrix analyses methods (e.g. diagonal dominance or other norms), it was possible to develop a case-by-case nonlinear control systems approach to each particular system as a biomathematical entity.
by Ranjeetha Bharath.
S.B.

Los estilos APA, Harvard, Vancouver, ISO, etc.

9

Anisi, David A. "Online trajectory planning and observer based control". Licentiate thesis, Stockholm : Optimization and systems theory, Royal Institute of Technology, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4153.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

10

Christoph, Heilmair. "GPU-Based Visualisation of Viewshed from Roads or Areas in a 3D Environment". Thesis, Linköpings universitet, Informationskodning, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-130699.

Texto completo

Resumen

Viewshed refers to the calculation and visualisation of what part of a terrain isvisible from a given observer point. It is used within many fields, such as militaryplanning or telecommunication tower placement. So far, no general fast methodsexist for calculating the viewshed for multiple observers that may for instancerepresent a road within the terrain. Additionally, if the terrain contains over-lapping structures such as man-made constructions like bridges, most currentviewshed algorithms fail. This report describes two novel methods for viewshedcalculation using multiple observers for terrain that may contain overlappingstructures. The methods have been developed at Vricon in Linköping as a Mas-ter’s Thesis project. Both methods are implemented using the graphics program-ming unit and the OpenGL graphics library, using a computer graphics approach.Results are presented in the form of figures and images, as well as running timetables using two different test setups. Lastly, future possible improvements arealso discussed. The results show that the first method is a viable real-time solu-tion and that the second method requires some additional work.

Los estilos APA, Harvard, Vancouver, ISO, etc.

11

Regoli, Manuel. "Analysis of Flux Observers for Brushless Machines". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020.

Buscar texto completo

Resumen

In this thesis the observation of magnetic fluxes of brushless machines is investigated. Given the time varying nature of the equations that describe the brushless machines electrical behaviour, the stability of time varying systems is studied adopting Lyapunov theory. Three observers are proposed for the estimation of the fluxes: the Luenberger Observer, the Kalman Filter and the Extended Kalman Filter. These algorithms are implemented in Simulink. The solutions found are tested and verified using a full Model in the Loop available at the LEMAD (Laboratory for Electric Machine and Drives) of the University of Bologna. The observers are tested also with uncertainties in the resistance and inductances parameters, which is a common scenario in practice. A stability band for a diagonal observer gain, in discrete time, has been successfully found. In both the simulations with the known parameters and with variation of the statoric resistance, the estimated fluxes converge to the actual fluxes, but the RMS value of the error is better for the Extended Kalman Filter. For the simulations with the variations of the inductances, the estimation of the fluxes have worsened with more similar RMS error value among the three. In conclusion it was found that the Extended Kalman Filter has a better behaviour all around but it does not perform significantly better in the more realistic case. For this reason the proposed simpler Luenberger observer, designed using Lyapunov theory, can be a valid alternative.

Los estilos APA, Harvard, Vancouver, ISO, etc.

12

Evans, Jonah Wy. "Observer error in identifying species using indirect signs: analysis of a river otter track survey technique". Texas A&M University, 2003. http://hdl.handle.net/1969.1/5853.

Texto completo

Resumen

Indirect signs of species presence (e.g., tracks, scats, hairs) are frequently used to detect target species in occupancy, presence/absence, and other wildlife studies. Indirect signs are often more efficient than direct observation of elusive animals, making such signs well suited for long-term and broad-scale monitoring programs. However, error associated with misidentification of indirect signs can be high, and should be measured if meaningful inferences about population parameters are to be made. This study addressed the need for systematic approaches to estimate and minimize variation due to observer error in identifying indirect signs. I reanalyzed data from 4 replicates of a presence/absence survey of northern river otters (Lontra canadensis) that had been conducted by Texas Parks and Wildlife Department (1996-2003). Sixteen observers had recorded tracks at sample points under bridges (n = 250) distributed throughout 27 counties in the Piney-Woods ecoregion of east Texas. My objectives were to 1) determine if observers were a source of bias in the survey, 2) estimate the proportion of error associated with track identification skill, and 3) evaluate the use of an international certification procedure that measured observer tracking skill. The null hypothesis that observers had no effect on the variation in reported sign was rejected. Indeed, binary logistic regression tests indicated that observers were significantly associated with variation in reported track presence. Observers were not randomly distributed among bridge sites, and therefore were significantly correlated with 4 habitat variables that may have influenced heterogeneity in otter occupancy and probability of detection (watershed, vegetation-type, water-type, bridge-area). On average, experienced observers (n = 7) misidentified 44% of otter tracks, with a range of 0% to 100% correct detection. Also, 13% of the tracks of species determined to be 'otter-like' were misidentified as belonging to an otter. During the certification procedure, participants misidentified the tracks of 12 species as otter. Inaccurate identification of indirect signs is a likely source of error in wildlife studies. I recommend that observer skill in identification of indirect signs be measured in order to detect and control for observer bias in wildlife monitoring.

Los estilos APA, Harvard, Vancouver, ISO, etc.

13

Klaer, Neil E. y n/a. "Analysis of seabird by-catch in the Australian Fishing Zone using Japanese longline fishery observer data". University of Canberra. Applied Science, 1998. http://erl.canberra.edu.au./public/adt-AUC20060814.150108.

Texto completo

Resumen

Data collected by Australian observers, combined with logbook data supplied by all Japanese vessels fishing in the Australian Fishing Zone were used to estimate the total seabird catch and catch rates (and associated variances) within the Australian Fishing Zone by season and area. The species composition of subsamples of captured seabirds was used in conjunction with the estimates of total by-catch to provide estimates of by-catch by species. The total by-catch of all seabird species by Japanese longline within Australian waters was estimated to be 2,981 (cv 17%) for the 1992 fishing year, 3,590 (cv 15%) in 1993 and 2,817 (cv 19%) in 1994. However, the observed seabird bycatch may underestimate the total number of seabirds killed by 27%. The increase in total seabird by-catch between 1992 and 1993 is partly due to the use of monofilament nylon longline gear by two vessels in 1993, and the decrease from 1993 to 1994 was mainly due to a corresponding reduction in fishing effort. For the three years examined, 78% of the total seabird by-catch was albatrosses, with black-browed albatross (Diomedea melanophrys) and shy albatross (D. cauta) caught in the greatest numbers. Catches of yellow-nosed albatross (D. chlororhynchos), wandering albatross (D. exulans}, and grey-headed albatross (D. chrysostoma) were also substantial. The proportions of individual species caught showed considerable inter-annual variability. Most seabirds caught and killed by longline fishing are captured during line setting. Data collected by the observers were also used to determine the influence of various environmental factors and mitigation measures on seabird catch rates. Generalised linear models were used to determine the statistical significance of the effect of each factor on the seabird catch rate. Results show that the environmental factor that has the most influence is whether line setting was carried out at night or during the day. For the data examined, the chance of catching seabirds during day sets was five times greater than for night sets. For night sets, the chance of catching seabirds during the full half-phase of the moon was five times greater than during the new half-phase. Other environmental factors with significant effects were the area and season fished. Wind, cloud and sea conditions were not found to have a significant influence. Considerable variation in the seabird by-catch rate among vessels was found, which is probably due to differences in their implementation of mitigation measures, as well as the clumped distribution of seabirds by area and time. Interannual variation in the by-catch rate was found to be statistically significant but the differences among years was small in comparison to other factors. An examination of the influence of mitigation measures for sets made during the day in summer in the Tasmanian area showed that the level of bait thawing and unidentified factors related to individual vessels were most significant in determining the seabird by-catch rate, followed by the use of a bait throwing device. It was not possible to examine the influence of the use of bird scaring tori poles and lines as these were used during all sets examined in detail. For this data set, the amount of cloud cover had an influence, while moon phase, sea conditions and wind strength did not.

Los estilos APA, Harvard, Vancouver, ISO, etc.

14

Waldherr, Steffen. "Observability analysis and observer design for controlled population dynamics Beobachtbarkeitsanalyse und Beobachterentwurf für Populationsmodelle mit Eingang /". [S.l. : s.n.], 2005. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB12168118.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

15

Brand, Jonathan Frieman. "Staging Liver Fibrosis with Statistical Observers". Diss., The University of Arizona, 2016. http://hdl.handle.net/10150/612941.

Texto completo

Resumen

Chronic liver disease is a worldwide health problem, and hepatic fibrosis (HF) is one of the hallmarks of the disease. Pathology diagnosis of HF is based on textural change in the liver as a lobular collagen network that develops within portal triads. The scale of collagen lobules is characteristically on order of 1mm, which close to the resolution limit of in vivo Gd-enhanced MRI. In this work the methods to collect training and testing images for a Hotelling observer are covered. An observer based on local texture analysis is trained and tested using wet-tissue phantoms. The technique is used to optimize the MRI sequence based on task performance. The final method developed is a two stage model observer to classify fibrotic and healthy tissue in both phantoms and in vivo MRI images. The first stage observer tests for the presence of local texture. Test statistics from the first observer are used to train the second stage observer to globally sample the local observer results. A decision of the disease class is made for an entire MRI image slice using test statistics collected from the second observer. The techniques are tested on wet-tissue phantoms and in vivo clinical patient data.

Los estilos APA, Harvard, Vancouver, ISO, etc.

16

Anisi, David A. "On Cooperative Surveillance, Online Trajectory Planning and Observer Based Control". Doctoral thesis, KTH, Optimeringslära och systemteori, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-9990.

Texto completo

Resumen

The main body of this thesis consists of six appended papers. In the first two, different cooperative surveillance problems are considered. The second two consider different aspects of the trajectory planning problem, while the last two deal with observer design for mobile robotic and Euler-Lagrange systems respectively.In Papers A and B, a combinatorial optimization based framework to cooperative surveillance missions using multiple Unmanned Ground Vehicles (UGVs) is proposed. In particular, Paper A considers the the Minimum Time UGV Surveillance Problem (MTUSP) while Paper B treats the Connectivity Constrained UGV Surveillance Problem (CUSP). The minimum time formulation is the following. Given a set of surveillance UGVs and a polyhedral area, find waypoint-paths for all UGVs such that every point of the area is visible from a point on a waypoint-path and such that the time for executing the search in parallel is minimized. The connectivity constrained formulation extends the MTUSP by additionally requiring the induced information graph to be kept recurrently connected at the time instants when the UGVs perform the surveillance mission. In these two papers, the NP-hardness of both these problems are shown and decomposition techniques are proposed that allow us to find an approximative solution efficiently in an algorithmic manner.Paper C addresses the problem of designing a real time, high performance trajectory planner for an aerial vehicle that uses information about terrain and enemy threats, to fly low and avoid radar exposure on the way to a given target. The high-level framework augments Receding Horizon Control (RHC) with a graph based terminal cost that captures the global characteristics of the environment. An important issue with RHC is to make sure that the greedy, short term optimization does not lead to long term problems, which in our case boils down to two things: not getting into situations where a collision is unavoidable, and making sure that the destination is actually reached. Hence, the main contribution of this paper is to present a trajectory planner with provable safety and task completion properties. Direct methods for trajectory optimization are traditionally based on a priori temporal discretization and collocation methods. In Paper D, the problem of adaptive node distribution is formulated as a constrained optimization problem, which is to be included in the underlying nonlinear mathematical programming problem. The benefits of utilizing the suggested method for online trajectory optimization are illustrated by a missile guidance example.In Paper E, the problem of active observer design for an important class of non-uniformly observable systems, namely mobile robotic systems, is considered. The set of feasible configurations and the set of output flow equivalent states are defined. It is shown that the inter-relation between these two sets may serve as the basis for design of active observers. The proposed observer design methodology is illustrated by considering a unicycle robot model, equipped with a set of range-measuring sensors. Finally, in Paper F, a geometrically intrinsic observer for Euler-Lagrange systems is defined and analyzed. This observer is a generalization of the observer proposed by Aghannan and Rouchon. Their contractivity result is reproduced and complemented by a proof that the region of contraction is infinitely thin. Moreover, assuming a priori bounds on the velocities, convergence of the observer is shown by means of Lyapunov's direct method in the case of configuration manifolds with constant curvature.
QC 20100622
TAIS, AURES

Los estilos APA, Harvard, Vancouver, ISO, etc.

17

Ziegler, Alexander H. "CONSUMER EMBARRASSMENT – A META-ANALYTIC REVIEW AND EXPERIMENTAL EXAMINATION". UKnowledge, 2019. https://uknowledge.uky.edu/marketing_etds/9.

Texto completo

Resumen

This dissertation consists of two essays that discuss the influence of embarrassment on consumers. In the first essay, I examine consumers’ coping responses to embarrassment in a meta-analytic review. In essay two, I utilize an experimental approach to investigate the impact of embarrassing encounters on unrelated consumers who merely observe the situation. In the first essay, the meta-analysis is guided by findings in the literature that demonstrate embarrassment can both promote and detract from consumer well-being. However, despite being investigated for decades, little is known about how consumers cope with embarrassing situations, and when and why consumers respond in positive and negative ways. The meta-analysis draws on the transactional framework of appraisals and coping to analyze the extant literature, construing positive responses as problem-focused coping, and negative responses as emotion-focused coping. I examine both situational and trait factor moderators to explain variance in these divergent outcomes and to resolve competing findings. A meta-analysis of 93 independent samples (N = 24,051) revealed that embarrassment leads to both problem-focused coping (r = 0.21), which can promote consumer well-being, and emotion-focused coping (r = 0.23), which can detract from consumer well-being. The relationship between embarrassment and emotion-focused coping was particularly strong in emotionally intense situations that were out of a transgressor’s control, for female consumers, and for consumers with an individualist orientation. The relationship between embarrassment and problem-focused coping was particularly strong in emotionally intense situations for male and young consumers. The second essay investigates the influence of embarrassing situations on neutral observers of the situation. The extant literature suggests that a consumer who commits a social transgression will experience embarrassment if real or imagined others are present to witness the transgression. However, the parallel embarrassment experienced, in turn, by those observers lacks a theoretical account, since observers have committed no transgression and are not the subject of appraisal by others. I label this phenomenon observer embarrassment, and introduce perspective taking as the underlying process that leads to observer embarrassment. Across six studies, I use physiological, behavioral, and self-report measures to validate the presence of observer embarrassment, as well as the underlying perspective-taking mechanism. Specifically, the results demonstrate that observers are more likely to experience embarrassment when they imagine themselves as the transgressor (versus experience empathy for the transgressor), something more likely to occur when the observer and actor share a common identity. Thus, observer embarrassment is not an empathetic response to witnessing a social transgression, but rather an experience parallel to personal embarrassment of others.

Los estilos APA, Harvard, Vancouver, ISO, etc.

18

Lim, Thiow Yong Dennis. "A methodological approach for conducting a business case analysis of the Global Observer Joint Capability Technology Denomstration (JCTD)". Monterey, Calif. : Naval Postgraduate School, 2007. http://bosun.nps.edu/uhtbin/hyperion-image.exe/07Dec%5FLim%5FThiow.pdf.

Texto completo

Resumen

Thesis (M.S. in Operations Research)--Naval Postgraduate School, December 2007.
Thesis Advisor(s): Nussbaum, Daniel. "December 2007." Description based on title screen as viewed on January 23, 2008. Includes bibliographical references (p. 59-65). Also available in print.

Los estilos APA, Harvard, Vancouver, ISO, etc.

19

Thiow, Yong Dennis Lim. "A methodological approach for conducting a business case analysis of the Global Observer Joint Capability Technology Demonstration (JCTD)". Thesis, Monterey, California. Naval Postgraduate School, 2007. http://hdl.handle.net/10945/3114.

Texto completo

Resumen

The Global Observer is a Joint Capability Technology Demonstration (JCTD) initiative that is being managed by the United States Special Operations Command (US SOCOM). The JCTD Program seeks to accelerate the development and operational evaluation of mature advanced technologies to rapidly transition the new capability to military operations. The Global Observer is a liquid-hydrogen powered unmanned aircraft system that has been designed for deployment as a stratospheric satellite. It will provide an affordable, persistent presence over any designated area of interest for surveillance and communications relay missions. The purpose of this study is to analyze the cost savings, as well as the other benefits associated with the operational deployment of the Global Observer. This thesis will (1) Develop a model for performing business case analyses of JCTDs, including defining the methodical structure required in the business case report; and (2) Conduct the Global Observer JCTD business case analysis, including a baseline analysis and a comprehensive sensitivity analysis based on a developed operational scenario with 6 designated areas of operations, while comparing the performance with an existing analogous system, i.e., the RQ-4 Global Hawk.

Los estilos APA, Harvard, Vancouver, ISO, etc.

20

Thorstensson, Mirko. "Using Observers for Model Based Data Collection in Distributed Tactical Operations". Licentiate thesis, Linköping : Department of Computer and Information Science, Linköpings universitet, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-15620.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

21

Brand, Jonathan F., Lars R. Furenlid, Maria I. Altbach, Jean-Philippe Galons, Achyut Bhattacharyya, Puneet Sharma, Tulshi Bhattacharyya, Ali Bilgin y Diego R. Martin. "Task-based optimization of flip angle for fibrosis detection in T1-weighted MRI of liver". SPIE-SOC PHOTO-OPTICAL INSTRUMENTATION ENGINEERS, 2016. http://hdl.handle.net/10150/622346.

Texto completo

Resumen

Chronic liver disease is a worldwide health problem, and hepatic fibrosis (HF) is one of the hallmarks of the disease. The current reference standard for diagnosing HF is biopsy followed by pathologist examination; however, this is limited by sampling error and carries a risk of complications. Pathology diagnosis of HF is based on textural change in the liver as a lobular collagen network that develops within portal triads. The scale of collagen lobules is characteristically in the order of 1 to 5 mm, which approximates the resolution limit of in vivo gadolinium-enhanced magnetic resonance imaging in the delayed phase. We use MRI of formalin-fixed human ex vivo liver samples as phantoms that mimic the textural contrast of in vivo Gd-MRI. We have developed a local texture analysis that is applied to phantom images, and the results are used to train model observers to detect HF. The performance of the observer is assessed with the area-under-the-receiver-operator-characteristic curve (AUROC) as the figure-of-merit. To optimize the MRI pulse sequence, phantoms were scanned with multiple times at a range of flip angles. The flip angle that was associated with the highest AUROC was chosen as optimal for the task of detecting HF. (C) The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

Los estilos APA, Harvard, Vancouver, ISO, etc.

22

Delaunay, Tiphaine. "Adaptative observers for wave equations and associated discretizations : formulations and analysis". Electronic Thesis or Diss., Institut polytechnique de Paris, 2023. http://www.theses.fr/2023IPPAX120.

Texto completo

Resumen

Le contexte de cette thèse est l'étude de problèmes inverses pour les phénomènes de propagation d'onde sous l'angle de la théorie du contrôle, plus précisément la théorie de l'observation. Notre objectif est de formaliser, d'analyser et de discrétiser des stratégies appelées séquentielles en assimilation de données, où les observations sont prises en compte à mesure qu'elles sont disponibles. Le système résultant appelé observateur (ou estimateur séquentiel) se stabilise sur la trajectoire observée reconstruisant alors l'état et éventuellement des paramètres inconnus du système. Ici nous nous concentrons plus particulièrement sur la reconstruction de source au second membre d'une équation des ondes, un problème d'estimation qui peut apparaître comme intermédiaire en compléxité entre l'estimation d'état (ou de condition initiale) et l'identification de paramètres généraux. Dans ce cadre, nous proposons de définir dans un formalisme déterministe en dimension infinie, un estimateur dit de Kalman qui estime séquentiellement le terme source à identifier. Par les outils de programmation dynamique, nous montrons que cet estimateur séquentiel est équivalent à la minimisation d'une fonctionnelle, cette équivalence nous permettant d'en proposer l'analyse de convergence sous condition d'observabilité. Nous démontrons alors des inégalités d'observabilité pour différents types de source en combinant analyse fonctionnelle, méthodes des multiplicateurs et estimations de Carleman. Ces inégalités nous informent notamment sur le caractère éventuellement mal-posé des problèmes inverses de reconstruction que nous étudions et nous permettent d'en quantifier le degré et ainsi d'adapter les régularisation proposées. Nous comparons notamment des stratégies inverser-et-régulariser par opposition à regulariser-pour-inverser. Concernant les questions de discrétisation et leur analyse numérique, nous défendons l'idée de redéfinir ces observateurs associés à la minimisation de la fonctionnelle une fois que le modèle direct a été discrétisé. Cette approche discrétiser-puis-optimiser est avantageuse pour l'analyse par rapport à optimiser-puis-discrétiser. Il n'en reste pas moins que les inégalités d'observabilité doivent être étendues aux systèmes discrets. À ce propos, nous étendons en particulier des résultats de stabilisation exponentielle uniforme en la discrétisation pour des discrétisations par éléments finis de haut degré de l'équation des ondes
The context of this thesis is the study of inverse problems for wave propagation phenomena from a control theory perspective, more specifically using observation theory. Our goal is to formalize, analyze, and discretize strategies called sequential in data assimilation, where measurements are taken into account as they become available. The resulting system, called an observer (or a sequential estimator), stabilizes on the observed trajectory hence reconstructs the state and possibly some unknown parameters of the system. Here we focus in particular on source reconstruction on the right-hand side of our wave equation, an estimation problem intermediate in complexity between state estimation (or initial condition estimation) and the more general problem of parameter identification. In this context, we propose to define in a deterministic framework in infinite dimension a so-called Kalman estimator that sequentially estimates the source term to be identified. Using dynamic programming tools, we show that this sequential estimator is equivalent to the minimization of a functional. This equivalence allows us to propose convergence analysis under observability conditions. We then demonstrate observability inequalities for different source types by combining functional analysis, multiplier methods, and Carleman estimates. In particular, these inequalities inform us about the ill-poseness nature of the inverse reconstruction problems we study and allow us to quantify the degree of ill-posedness hence to propose adapted regularizations. In particular, we compare an invert-and-regularize strategies as opposed to regularize-to-invert. Concerning discretization issues and their analysis, we defend the idea of redefining these observers associated with the minimization of the functional once the direct model has been discretized. This discretize-then-optimize approach is advantageous for the analysis compared to optimize-then-discretize approach. Nevertheless, the observability inequalities need to be extended to discretized systems. In particular, in this context, we extend uniform exponential stabilization results to the discretization for high-order finite element discretizations of the wave equation

Los estilos APA, Harvard, Vancouver, ISO, etc.

23

GARRAFFA, Giovanni. "Real Time Localization Systems for autonomous navigation: Modelling, Analysis and Control". Doctoral thesis, Università degli Studi di Palermo, 2021. http://hdl.handle.net/10447/514955.

Texto completo

Resumen

Questo lavoro di tesi riguarda la derivazione di osservatori ibridi dello stato, analisi e controllo, di sistemi di localizzazione e navigazione in tempo reale (RTLS). In particolare, il framework dei sistemi ibridi è stato utilizzato per tener conto delle dinamiche continue e discrete coinvolte nel processo di stima e della natura sporadica e tempo randomica delle misure provenienti da vari sensori di distanza e/o inerziali. Analisi di convergenza sono state effettuate per dimostrare la stabilità delle soluzioni proposte e la capacità di filtraggio dei rumori presenti nelle misure. Il presente lavoro è corredato dai risultati delle prove sperimentali di laboratorio a conferma della validità delle soluzioni proposte.
This thesis work concerns the derivation of hybrid state observers, analysis and control, of real-time localization and navigation systems (RTLS). In particular, the hybrid systems framework was used to take into account the continuous and discrete dynamics involved in the estimation process and the sporadic and time-random nature of the measurements from various distance and / or inertial sensors. Convergence analyzes were carried out to demonstrate the stability of the proposed solutions and the filtering capacity of the noises present in the measurements. This work is accompanied by the results of the experimental laboratory tests confirming the validity of the proposed solutions.

Los estilos APA, Harvard, Vancouver, ISO, etc.

24

Morrell, Thomas J. "Analysis of "Observer Effect" in Logbook Reporting Accuracy for U.S. Pelagic Longline Fishing Vessels in the Atlantic and Gulf of Mexico". Thesis, NSUWorks, 2019. https://nsuworks.nova.edu/occ_stuetd/511.

Texto completo

Resumen

Commercial pelagic longline fishers within the U.S. Atlantic, Gulf of Mexico, and Caribbean are required to report all fishing interactions per each gear deployment to NOAA’s Vessel Logbook Program of the Southeast Fisheries Science Center to quantify bycatch, increase conservation efforts, and avoid jeopardizing the existence of vulnerable species listed under the Endangered Species Act (ESA). To provide additional accuracy, the Pelagic Observer Program (POP) of the SEFSC deploys professionally trained observers on longline vessels to produce a statistically reliable subset of longline fisheries data. A comparison of self-reported (“unobserved”) datasets versus observer-collected (“observed”) datasets showed a general consistency for most target species but non-reporting or under-reporting for a number of bycatch species and “lesser-valued” target species. These discrepancies between catch compositions and abundancies regarding targeted species, species of bycatch concern, and species of minimum economic value can provide insight into increased fisheries regulations, stricter requirements, or additional observer coverage.

Los estilos APA, Harvard, Vancouver, ISO, etc.

25

Tavakoli, Taba Seyedamir. "A systems approach to exploring professional performance of knowledge workers: A case study in radiology". Thesis, The University of Sydney, 2016. http://hdl.handle.net/2123/15471.

Texto completo

Resumen

There is an increasing demand internationally for ‘knowledge workers’ as this workforce is required to extensively use their knowledge and skills in performing complex specialised work. Long-term sustainability of knowledge workers has been very challenging for managers and policy makers because it requires development and conservation of a well-educated, highly skilled and effective workforce. The conventional approach in dealing with workforce management challenges has been typically to apply unit level standardisation and optimisation. In this regard, job performance of knowledge workers has been studied by various researchers through individualistic and atomistic perspectives. A systems approach in dealing with complex social systems, however, implies that understanding of the system’s individual components and their interactions as a whole are both imperative. This thesis presents a novel systems approach for exploring professional performance of knowledge workers by providing new models at micro and macro levels and operationalising them within a case study. The Australian radiology workforce was considered as the domain of the study because radiologists are recognised as a classic case of knowledge workers and their work mostly comprised of application of knowledge, particularly in the correct interpretation of medical images. This research provides new insights about understanding job performance of knowledge workers from a social/professional networks perspective, along with traditional view of personal/individual characteristics. A theory-driven job performance model at micro level (i.e. performance of individuals) is presented and then tested systematically in the case study. At the same time, Australian radiology system as a whole (i.e. workforce training, supply and demand) is examined at macro/system level in order to fill the gaps in understanding managerial challenges of the workforce. In order to analyse the Australian radiology system and its components at macro level, a system dynamics modelling approach was employed to test the balance between supply and demand of radiology workforce in the long term. The results showed that traditional models in radiology are unsustainable based on growing demand for services. Accordingly, some new system level strategies should be implemented for provision of a healthy workforce in future along any unit level optimisation, such as increasing radiologists’ performance. For examining the performance of radiologists, a comprehensive research study was designed for validating and verifying the theoretical model through both qualitative and quantitative studies. The participating radiologists also independently read a test set of mammographic cases and their observer performance in detecting breast cancers was measured. According to both the qualitative and the quantitative studies, social networks play a critical role in the job performance of knowledge workers. In the quantitative study, the model proposed in this thesis could explain almost 63.5% of the variance in the observer performance; 48% for the network factors, in comparison to 15.5% for the traditional measure of radiologists’ experience. Among different factors of egocentric social networks, job performance was positively associated with degree centrality and effective size, but negatively associated with constraint and hierarchy. The practical implication of this result is that developing and maintaining effective network links in the workplace and beyond should be considered of high value for the performance of knowledge workers. Overall, this thesis lays the foundation for a new direction of research into understanding knowledge workers, their workforce system challenges and their performance through a systems perspective. This direction can be pursued by researchers in radiology as well as researchers and policy makers in other knowledge work domains with the purpose of developing and maintaining a healthy system with effective workforce.

Los estilos APA, Harvard, Vancouver, ISO, etc.

26

Wattrus, Jane M. (Jane Marie). "Habitat Evaluation Procedures at Ray Roberts Lake: an Analysis of the Relationship with Ecological Indicators and a Study of Observer and Temporal Variability". Thesis, University of North Texas, 1993. https://digital.library.unt.edu/ark:/67531/metadc501233/.

Texto completo

Resumen

Habitat Evaluation Procedure data gathered at Ray Roberts Lake in 1989 and 1990 were analysed for temporal variability, observer variability and relationships between Habitat Units (HUs) and species density/diversity. observer variability within a group was analysed by cluster analysis and bootstrapping. Five out of 36 sites showed significant differences in Habitat Suitability Index (HSI) values within the group. A nonparametric Mann-Whitney test was used to analyze temporal variability. One of 6 sites showed a significant difference in HSI values between years. Using Spearman's Rank Correlation Coefficient, a correlation was found between indicator species density and HUs. No significant correlation was indicated between species diversity and HUs.

Los estilos APA, Harvard, Vancouver, ISO, etc.

27

Chakchouk, Mohamed. "Conceptiοn d'un détecteur de système mécatronique mobile intelligent pour observer des molécules en phase gazeuse en ΙR". Electronic Thesis or Diss., Normandie, 2024. http://www.theses.fr/2024NORMIR06.

Texto completo

Resumen

Ce travail anticipe que, dans un monde technologique numérique en constante expansion, les percées technologiques dans l'analyse des données collectées par des dispositifs spectroscopiques permettront l'identification presque instantanée d'espèces connues observées in-situ dans un environnement spécifique, laissant l'analyse approfondie nécessaire aux espèces non observées. La méthode dérivée de la technologie RBDO (Reliability Based Design Optimisation) sera utilisé pour implémenter une procédure d’intelligence artificielle afin d'identifier les espèces observées à partir d'un capteur IR mobile. Afin d'analyser avec succès les données obtenues, il est nécessaire d'assigner de manière appropriée les espèces moléculaires à partir des données IR observées en utilisant les modèles théoriques appropriés. Ce travail se concentre sur l'observation à partir d'appareils mobiles équipés de capteurs, d'antennes et d'électronique appropriés pour capturer et envoyer des données brutes ou analysées à partir d'un environnement spectroscopique IR intéressant. Il est donc intéressant voir indispensable de se concentrer sur les outils théoriques basés sur la symétrie pour l'analyse spectroscopique des molécules, ce qui permet d'identifier les fenêtres IR à choisir pour l'observation dans la conception de l'appareil. Ensuite, en ajustant les paramètres théoriques spectroscopiques aux fréquences observées, le spectre d'une espèce moléculaire peut être reconstruit. Une déconvolution des spectres observés est nécessaire avant l'analyse en termes d'intensité, de largeur et de centre de raie caractérisant une forme de raie. Une stratégie adéquate est donc nécessaire lors de la conception pour inclure l'analyse des données pendant la phase d'observation, qui peut bénéficier d'un algorithme d'intelligence artificielle pour tenir compte des différences dans la signature spectrale IR à cet égard, le pouvoir analytique des données de l'instrument peut être amélioré en utilisant la méthodologie d'optimisation de la conception basée sur la fiabilité (RBDO). Basée sur le comportement multiphysique de la propagation des incertitudes dans l'arbre hiérarchique du système, la RBDO utilise une modélisation probabiliste pour analyser l'écart par rapport à la sortie souhaitée comme paramètres de rétroaction pour optimiser la conception au départ. Le but de cette thèse est de traiter les paramètres de fenêtres d'observation IR, afin de traiter les questions de fiabilité au-delà de la conception mécatronique, pour inclure l'identification des espèces par l'analyse des données collectées
This work anticipates that, in an ever-expanding digital technology world, technological breakthroughs in the analysis of data collected by spectroscopic devices will allow the almost instantaneous identification of known species observed in-situ in a specific environment, leaving the necessary in-depth analysis of unobserved species. The method derived from RBDO (Reliability Based Design Optimization) technology will be used to implement an artificial intelligence procedure to identify observed species from a mobile IR sensor. To successfully analyze the obtained data, it is necessary to appropriately assign molecular species from the observed IR data using appropriate theoretical models. This work focuses on the observation from mobile devices equipped with appropriate sensors, antennas, and electronics to capture and send raw or analyzed data from an interesting IR spectroscopic environment. It is therefore interesting if not essential to focus on symmetry-based theoretical tools for the spectroscopic analysis of molecules, which allows to identify the IR windows to be chosen for observation in the design of the device. Then, by fitting the theoretical spectroscopic parameters to the observed frequencies, the spectrum of a molecular species can be reconstructed. A deconvolution of the observed spectra is necessary before the analysis in terms of intensity, width and line center characterizing a line shape. Therefore, an adequate strategy is needed in the design to include data analysis during the observation phase, which can benefit from an artificial intelligence algorithm to account for differences in the IR spectral signature. In this regard, the analytical power of the instrument data can be improved by using the reliability-based design optimization (RBDO) methodology. Based on the multi-physics behavior of uncertainty propagation in the hierarchical system tree, RBDO uses probabilistic modeling to analyze the deviation from the desired output as feedback parameters to optimize the design in the first place. The goal of this thesis is to address IR observation window parameters to address reliability issues beyond mechatronic design to include species identification through analysis of collected data

Los estilos APA, Harvard, Vancouver, ISO, etc.

28

Pitarch, Pérez José Luis. "Contributions to fuzzy polynomial techniques for stability analysis and control". Doctoral thesis, Universitat Politècnica de València, 2014. http://hdl.handle.net/10251/34773.

Texto completo

Resumen

The present thesis employs fuzzy-polynomial control techniques in order to improve the stability analysis and control of nonlinear systems. Initially, it reviews the more extended techniques in the field of Takagi-Sugeno fuzzy systems, such as the more relevant results about polynomial and fuzzy polynomial systems. The basic framework uses fuzzy polynomial models by Taylor series and sum-of-squares techniques (semidefinite programming) in order to obtain stability guarantees. The contributions of the thesis are: ¿ Improved domain of attraction estimation of nonlinear systems for both continuous-time and discrete-time cases. An iterative methodology based on invariant-set results is presented for obtaining polynomial boundaries of such domain of attraction. ¿ Extension of the above problem to the case with bounded persistent disturbances acting. Different characterizations of inescapable sets with polynomial boundaries are determined. ¿ State estimation: extension of the previous results in literature to the case of fuzzy observers with polynomial gains, guaranteeing stability of the estimation error and inescapability in a subset of the zone where the model is valid. ¿ Proposal of a polynomial Lyapunov function with discrete delay in order to improve some polynomial control designs from literature. Preliminary extension to the fuzzy polynomial case. Last chapters present a preliminary experimental work in order to check and validate the theoretical results on real platforms in the future.
Pitarch Pérez, JL. (2013). Contributions to fuzzy polynomial techniques for stability analysis and control [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/34773
TESIS

Los estilos APA, Harvard, Vancouver, ISO, etc.

29

Hajji, Miled El. "Modélisation et analyse mathématiques pour les écosystèmes microbiens : approche par les systèmes dynamiques". Thesis, Montpellier 2, 2010. http://www.theses.fr/2010MON20117/document.

Texto completo

Resumen

Cette thèse s'adresse au problèmes relié au modélisation mathématique en culture continue et culture batch. Nous proposons et étudions, dans une première étape, des modèles mathématiques de quelques processus biologique en culture continue (Chemostat) permettant d'expliquer et de prévoir la coexistence et la coexistence pratique. Dans une deuxième étape, une série d'expériences de laboratoire sont munies en culture batch, et un modèle mathématique tenant compte du recyclage de substrat est proposé, analysé et validé sur des donnés expérimentales en culture pure et mixte prouvant la validité de la principe d'exclusion compétitive en culture batch
Cette thèse s'adresse au problèmes relié au modélisation mathématique en culture continue et culture batch. Nous proposons et étudions, dans une première étape, des modèles mathématiques de quelques processus biologique en culture continue (Chemostat) permettant d'expliquer et de prévoir la coexistence et la coexistence pratique. Dans une deuxième étape, une série d'expériences de laboratoire sont munies en culture batch, et un modèle mathématique tenant compte du recyclage de substrat est proposé, analysé et validé sur des donnés expérimentales en culture pure et mixte prouvant la validité de la principe d'exclusion compétitive en culture batch

Los estilos APA, Harvard, Vancouver, ISO, etc.

30

Çek, Mehmet Emre Savacı Ferit Acar. "Analysis of observed chaotic data/". [s.l.]: [s.n.], 2004. http://library.iyte.edu.tr/tezler/master/elektronikvehaberlesme/T000493.rar.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

31

Arslan, Ali Erkin. "Range Parameterized Bearings-only Tracking Using Particle Filter". Phd thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614888/index.pdf.

Texto completo

Resumen

In this study, accurate target tracking for bearings-only tracking problem is investigated. A new tracking filter for this nonlinear problem is designed where both range parameterization and Rao-Blackwellized (marginalized) particle filtering techniques are used in a Gaussian mixture formulation to track both constant velocity and maneuvering targets. The idea of using target turn rate in the state equation in such a way that marginalization is possible is elaborated. Addition to nonlinear nature, unobservability is a major problem of bearings-only tracking. Observer trajectory generation to increase the observability of the bearings-only tracking problem is studied. Novel formulation of observability measures based on mutual information between the state and the measurement sequences are derived for the problem. These measures are used as objective functions to improve observability. Based on the results obtained better understanding of the required observer trajectory for accurate bearings-only target tracking is developed.

Los estilos APA, Harvard, Vancouver, ISO, etc.

32

Ivanauskaitė, Deimantė. "Alveolar bone loss in radiographic modalities for diagnosis of periodontal disease". Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2011. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2011~D_20110621_164329-13939.

Texto completo

Resumen

Radiographic modalities are used in addition to clinical methods to gain information about the patients. In the examination of the periodontium, which is comprised of the gingiva, alveolar bone, periodontal ligament, and cementum, the radiographic examination plays an integral role for diagnosis of periodontal disease. The diagnosis periodontitis is based on a finding of alveolar bone loss. Changes of the alveolar bone can be assessed by different radiographic modalities, such as intraoral radiography (bitewing and periapical radiography) and panoramic radiography. Analysis of alveolar bone loss (alveolar bone level, detection of vertical bone defect and furcation involvement) in radiographic modalities and a systematic review could be helpful to suggest the more applicable radiographic methods for diagnosis of periodontal disease. The purpose of the present study was to examine diagnostic properties of panoramic radiography for the assessment of alveolar bone loss for the diagnosis of periodontal diseases as compare to posterior bitewing radiography. For 96 patients panoramic and posterior bitewing radiographs were performed and results of analysis of visibility of radiographic images and assessment of alveolar bone loss were compared. Also, the systematic review on diagnostic properties of panoramic radiography in the assessment of alveolar bone loss was performed. Based on the results of this study, recommendations for clinical practice and for research were proposed.
Rentgeniniai tyrimo metodai taikomi, kad būtų papildyti klinikinio tyrimo duomenys. Tiriant periodontą, kurį sudaro dantenos, dantinė atauga, periodonto raiščiai ir cementas, rentgeninis tyrimas svarbus diagnozuojant periodonto ligas, nes jo metu nustatomi dantinės ataugos pokyčiai. Dantinės ataugos pokyčiams vertinti daromos rentgeno nuotraukos taikant vidinių burnos rentgeno nuotraukų darymo metodus, t. y. kandimo ar dantų šaknų rentgeno nuotraukų darymo metodus, ir išorinės burnos rentgeno nuotraukos darymo metodą, t. y. panoraminės rentgeno nuotraukos darymo metodą. Atlikus dantinės ataugos pokyčių (kaulo lygio arba rezorbcijos, kaulo defekto ir tarpšaknio kaulo pažeidimų) analizę, taikant rentgeninius metodus, ir padarius sisteminę literatūros apžvalgą, galima būtų pasiūlyti tinkamiausią rentgeno metodą periodonto ligoms diagnozuoti. Šio darbo tikslas – ištirti ir palyginti panoraminės rentgeno nuotraukos ir kaplių bei krūminių dantų rentgeno nuotraukų darymo metodų diagnostikos ypatybes vertinant dantinės ataugos pokyčius periodonto ligoms diagnozuoti. Kiekvienam, iš 96 pacientų įtrauktų į tyrimą, buvo padaryta panoraminė rentgeno nuotrauka ir kaplių bei krūminių dantų kandimo rentgeno nuotraukos. Atlikta dantinės ataugos rentgeno atvaizdo vizualioji kokybė analizė ir vertinimai skirtingose rentgeno nuotraukose bei palyginti rezultatai. Padaryta sisteminė literatūros apžvalga apie panoraminės rentgeno nuotraukos vertę diagnozuojant periodonto ligas. Pagal šio tyrimo... [toliau žr. visą tekstą]

Los estilos APA, Harvard, Vancouver, ISO, etc.

33

Ivanauskaitė, Deimantė. "Periodonto ligų diagnozavimas: dantinės ataugos pokyčių analizė, taikant skirtingus rentgeninio tyrimo metodus". Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2011. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2011~D_20110621_164439-60541.

Texto completo

Resumen

Rentgeniniai tyrimo metodai taikomi, kad būtų papildyti klinikinio tyrimo duomenys. Tiriant periodontą, kurį sudaro dantenos, dantinė atauga, periodonto raiščiai ir cementas, rentgeninis tyrimas svarbus diagnozuojant periodonto ligas, nes jo metu nustatomi dantinės ataugos pokyčiai. Dantinės ataugos pokyčiams vertinti daromos rentgeno nuotraukos taikant vidinių burnos rentgeno nuotraukų darymo metodus, t. y. kandimo ar dantų šaknų rentgeno nuotraukų darymo metodus, ir išorinės burnos rentgeno nuotraukos darymo metodą, t. y. panoraminės rentgeno nuotraukos darymo metodą. Atlikus dantinės ataugos pokyčių (kaulo lygio arba rezorbcijos, kaulo defekto ir tarpšaknio kaulo pažeidimų) analizę, taikant rentgeninius metodus, ir padarius sisteminę literatūros apžvalgą, galima būtų pasiūlyti tinkamiausią rentgeno metodą periodonto ligoms diagnozuoti. Šio darbo tikslas – ištirti ir palyginti panoraminės rentgeno nuotraukos ir kaplių bei krūminių dantų rentgeno nuotraukų darymo metodų diagnostikos ypatybes vertinant dantinės ataugos pokyčius periodonto ligoms diagnozuoti. Kiekvienam, iš 96 pacientų įtrauktų į tyrimą, buvo padaryta panoraminė rentgeno nuotrauka ir kaplių bei krūminių dantų kandimo rentgeno nuotraukos. Atlikta dantinės ataugos rentgeno atvaizdo vizualioji kokybė analizė ir vertinimai skirtingose rentgeno nuotraukose bei palyginti rezultatai. Padaryta sisteminė literatūros apžvalga apie panoraminės rentgeno nuotraukos vertę diagnozuojant periodonto ligas. Pagal šio tyrimo... [toliau žr. visą tekstą]
Radiographic modalities are used in addition to clinical methods to gain information about the patients. In the examination of the periodontium, which is comprised of the gingiva, alveolar bone, periodontal ligament, and cementum, the radiographic examination plays an integral role for diagnosis of periodontal disease. The diagnosis periodontitis is based on a finding of alveolar bone loss. Changes of the alveolar bone can be assessed by different radiographic modalities, such as intraoral radiography (bitewing and periapical radiography) and panoramic radiography. Analysis of alveolar bone loss (alveolar bone level, detection of vertical bone defect and furcation involvement) in radiographic modalities and a systematic review could be helpful to suggest the more applicable radiographic methods for diagnosis of periodontal disease. The purpose of the present study was to examine diagnostic properties of panoramic radiography for the assessment of alveolar bone loss for the diagnosis of periodontal diseases as compare to posterior bitewing radiography. For 96 patients panoramic and posterior bitewing radiographs were performed and results of analysis of visibility of radiographic images and assessment of alveolar bone loss were compared. Also, the systematic review on diagnostic properties of panoramic radiography in the assessment of alveolar bone loss was performed. Based on the results of this study, recommendations for clinical practice and for research were proposed.

Los estilos APA, Harvard, Vancouver, ISO, etc.

34

Woerner, Jeannette H. C. "Statistical analysis for discretely observed Lévy processes". [S.l. : s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=963699377.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

35

Koons, Bruce K. "Parameter estimation for series observed with round-off error". Diss., Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/54221.

Texto completo

Resumen

Time series data often is observed with measurement error. One type of measurement error almost always present is rounding error. A procedure is proposed for estimating parameters of a finite moving average time series which is observed only after rounding. Method of moments estimators are proposed for estimation of parameters of time series observed with general measurement error, including error, ε_n, which is correlated with the series X_t being measured. This procedure requires knowledge of the autocovariance function (ACF) of ε_t, and the cross covariances between X_t and ε_r. For rounding error, the rounding error series is shown to approach uniform white noise as the rounding interval width, R, approaches zero, and the cross correlations between X_t, and rounding error ε_t, are shown to approach zero as R -> 0. For both small R and large R, the ACF of ε_t, and the cross covariances between X_t and ε_t, are approximated. These values are then used to estimate the parameters of the moving average model for X_t when X_t is observed after rounding.
Ph. D.

Los estilos APA, Harvard, Vancouver, ISO, etc.

36

Vu, Hoang Giang. "Estimation and diagnostic of doubly-fed asynchronous wind generator". Thesis, Lyon 1, 2014. http://www.theses.fr/2014LYO10151.

Texto completo

Resumen

Dans ce mémoire de thèse nous présentons une méthodologie pour le diagnostic et la surveillance en ligne des éoliennes de l'état de l'ensemble machine électrique onduleur à partir de la mesure du champ magnétique continu. Ce travail est scindé en deux parties complémentaires. Dans la première partie, nous donnons quelques contributions concernant l'estimation de l'état et des paramètres pour certaines classes de systèmes non linéaires. Ces mêmes estimateurs ont été validés en simulation et sur un banc d'essai. La deuxième partie porte sur la mise en œuvre et la conception de deux bancs d'essai utilisés pour l'étude des défauts dans un système double alimentation MADA et un ensemble moteur électrique onduleur classique pour l'analyse des défauts du convertisseur. L'identification des paramètres et la technique de contrôle du système en boucle fermé est introduite pour l'application MADA. De plus, les capteurs virtuels sont conçus pour estimer la vitesse mécanique qui est utilisée pour calculer les fréquences caractéristiques défectueuses, et le signal de couple mécanique qui exerce une influence sur l'amplitude de certaines des signatures défectueux typiquement. Finalement, sur la base de la mise en équation théorique des signaux électriques avec défauts puis des simulations correspondantes, une comparaison avec l'expérimentation est réalisée pour valider la technique proposée. Ces travaux montrent l'avantage d'une telle technique dans la simplicité de l'instrumentation mis en œuvre
This doctoral thesis presents a methodology for the online condition monitoring of the electrical power drive in wind energy systems based on the local measurement of the DC-bus magnetic field. The work is divided into two complementary parts. In the first part, some contributions related to the estimation of the state and parameters for certain classes of nonlinear systems are provided. The estimators have been validated in simulation and on test benches. The second part focuses on the implementation and control design of two benchmarks used to study defects in a doubly-fed induction generator (DFIG) system and an induction motor power drive. In the former benchmark, the parameters identification of the induction machine and the controller design of the DFIG system are carried out. For the latter test bench, the notable work is to build an induction machine drive for the purpose of fault investigation, in which a PWM generator is developed to control and create the fault of the converter. Furthermore, virtual sensors are designed to estimate mechanical speed that is used to calculate the characteristic frequencies, and mechanical torque signal that has influence on the amplitude of some typical fault signatures. Finally, based on the theoretical aspect of the selected faults, the relevant simulations are developed and experiments are implemented on the benchmarks in order to validate the proposed technique. It has been shown that the diagnostic relying on the magnetic field measurement is feasible and offers various advantages such as simplicity and cost-effectiveness

Los estilos APA, Harvard, Vancouver, ISO, etc.

37

Richards, Frederick David. "Global analysis of predicted and observed dynamic topography". Thesis, University of Cambridge, 2019. https://www.repository.cam.ac.uk/handle/1810/284159.

Texto completo

Resumen

While the bulk of topography on Earth is generated and maintained by variations in the thickness and density of crust and lithosphere, a significant time-variable contribution is expected as a result of convective flow in the underlying mantle. For over three decades, this dynamic topography has been calculated numerically from inferred density structure and radial viscosity profiles. Resulting models predict ±2 km of long wavelength (i.e., ~ 20,000 km) dynamic topography with minor contributions at wavelengths shorter than ~ 5,000 km. Recently, observational studies have revealed that, at the longest wavelengths, dynamic topography variation is ~ 30% that predicted, with ±1 km amplitudes recovered at shorter wavelengths. Here, the existing database of water-loaded basement depths is streamlined, revised and augmented. By fitting increasingly sophisticated thermal models to a combined database of these oceanic basement depths and corrected heat flow measurements, the average thermal structure of oceanic lithosphere is constrained. Significantly, optimal models are consistent with invariable geochemical and seismological constraints whilst yielding similar values of mantle potential temperature and plate thickness, irrespective of whether heat flow, subsidence or both are fit. After recalculating residual depth anomalies relative to optimal age-depth subsidence and combining them with continental constraints from gravity anomalies, a global spherical harmonic representation is generated. Although, long wavelength dynamic topography increases by ~ 40% in the revised observation-based model, spectral analysis confirms that a fundamental discrepancy between observations and predictions remains. Significantly, residual depth anomalies reveal a ~4,000 km-scale eastward tilt across the Indian Peninsula. This asymmetry extends onshore from the high-elevation Western Ghats in the west to the Krishna-Godavari floodplains in the east. Calibrated inverse modelling of drainage networks suggest that the tilt of the peninsula grew principally in Neogene times with vertical motions linked to asthenospheric temperature anomalies. Uplift rates of up to 0.1 mm a⁻¹ place important constraints on the spatio-temporal evolution of dynamic topography and suggest that rates of transient vertical motion exceed those predicted by many modelling studies. Most numerical models excise the upper ~ 300 km of Earth's mantle and are unable to reconstruct the wavelength and rate of uplift observed across Peninsular India. By contrast, through conversion of upper mantle shear wave velocities to density using a calibrated anelastic parameterisation, it is shown that shorter wavelength (i.e., ≤ 5,000 km) dynamic topography, can mostly be explained by ±150°C asthenospheric temperature anomalies. Inclusion of anelastically corrected density structure in whole-mantle instantaneous flow models also serves to reduce discrepancy between predictions and observations of dynamic topography at long wavelengths. Residual mismatch between observations and predictions is further improved if the basal 300-600 km of large low shear wave velocity regions in the deep mantle are geochemically distinct and negatively buoyant. Finally, inverse modelling of geoid, dynamic topography, gravity and core-mantle boundary topography observations using adapted density structure suggests that geodynamic constraints can be acceptably fit using plausible radial viscosity profiles, contradicting a long-standing assertion that modest long wavelength dynamic topography is incompatible with geoid observations.

Los estilos APA, Harvard, Vancouver, ISO, etc.

38

Périssé, Amélie. "Color formulation algorithms improvement through expert knowledge integration for automotive effect paints". Thesis, Pau, 2020. http://www.theses.fr/2020PAUU3025.

Texto completo

Resumen

Aujourd’hui, le marché de la peinture automobile est gouverné par une demande pour des couleurs profondes et vives avec effets. Dans le domaine de la peinture automobile, l’exigence est très haute car la couleur est associée à un signe de qualité. Dans une collision classique, différentes parties du véhicule peuvent être endommagées avec généralement une partie de la carrosserie qui est touchée. La partie endommagée doit être réparée, poncée et préparée avant d’être repeinte. Pour réduire les coûts, le carrossier doit préparer une peinture avec un bon contretypage de teinte, et ce aussi vite que possible. Il s’agit donc pour la formulation de la peinture de réparation de reproduire les effets, aussi bien colorés que texturés, à partir de pigments absorbants ou à effets (particules d’aluminium, de nacre …). Il est relativement simple de qualifier les effets colorés à partir des courbes de réflectance puis des coordonnées CIELab. Cependant, la définition de la texture engendrée par les particules à effets est assez complexe et n’est encore qu’à ses prémices, avec des paramètres qui souvent ne correspondant pas aux phénomènes réellement perçus par l’œil humain. Dans le cadre de ce travail de thèse, la mobilisation de connaissances expertes à travers différentes sessions de tri libre et de brainstorming a permis la mise en évidence de descripteurs de texture réellement perceptifs. De plus, la mise en place de métriques de texture conçues à partir de préconisations réellement perceptives, a rendu possible l’obtention de valeurs correspondant à un observateur moyen pour chacun de ces paramètres descripteurs. Ces paramètres ayant été élaborés à partir des observations d‘évaluateurs expérimentés. La transposition de ces vérités terrain en descripteurs physiques de texture a permis l’obtention d’une corrélation entre le perceptible et le mesurable. Dans la procédure développée, l’œil humain a été remplacé par un appareil photo numérique agissant en qualité d’intégrateur tristimulaire d’informations radiométriques. En essayant de reproduire les conditions d’observation lors de la phase d’acquisition d’images, il a été ainsi possible de caractériser les phénomènes de texture par analyse d’image et de les corréler aux valeurs de l’observateur moyen préalablement défini
Nowadays, the automotive coating market is governed by a demand for deep and vibrant colors with effects. In this field, the requirement is very high because the color is associated with a sign of quality. In a typical collision, different parts of the vehicle may be damaged. The damaged part must be repaired, sanded and prepared before being painted. To reduce costs, the body shop must then prepare a paint with a good color matching, and thus as fast as possible. It is therefore necessary for the formulation of the repair coating to reproduce the effects, both colored and textured, from absorbent or effect pigments (aluminum particles, pearlescent materials …) from a characterization of the concerned vehicle coating. It is relatively simple to qualify the colored effects from the reflectance curves and then the CIELab coordinates. However, the description of the texturing effect generated by the distribution of effect particles at the microstructure scale is quite complex. The metrological approach of the perceptive properties is still at its beginnings. The parameters used do not necessarily correspond directly to the phenomena actually perceived by the human eye. As part of this thesis work, the mobilization of expert knowledge through various sessions of free sorting and brainstorming on coated samples made it possible to highlight really perceptive texture descriptors. These descriptors have been the subject of "objective" evaluations by experienced observers. They thus made it possible to associate a quantitative evaluation scale with each descriptor. This stage of the present thesis work allowed the establishment of ground truth data materialized by a set of reference samples representing different ordered levels of a descriptor. These ground truth data were then used to design a set of measurable physical texture descriptors that were directly correlated to perceptual scales constructed in the previous step. In the procedure developed, the human eye has been replaced by a digital camera acting as a tristimulus integrator of radiometric information. The image acquisition phase was a decisive step in the process: it was necessary to reproduce the conditions of evaluation of the properties perceived, recognized and retained during the various stages using expert human observers. It was then possible to characterize the texture phenomena by image analysis and to correlate them with the values of the previously defined mean observer

Los estilos APA, Harvard, Vancouver, ISO, etc.

39

Shiells, Helen. "Advanced multivariate statistical analysis of directly and indirectly observed systems". Thesis, University of Aberdeen, 2017. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=234061.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

40

Buchta, Luděk. "Kompenzace nelinearit při řízení střídavých pohonů". Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2019. http://www.nusl.cz/ntk/nusl-408028.

Texto completo

Resumen

Analysis of the dead-time effect and other nonlinearities of the voltage source inverter was carried out in the introduction of the doctoral thesis. Three compensation strategies for vector controlled PMSM were proposed based on the analysis. The voltage disturbance observer with cost function of current errors is based on the model of PMSM, known machine parameters and easily measurable quantities. The second observer which estimates the dq- axes currents and the value of the voltage error with one parameter only is designed based on the harmonic analysis and Kalman filter algorithm. The third method combines an adaptive approach with feedback and voltage disturbance observer that is based on the PMSM model. Furthermore, the two compensation methods for vector controlled induction motor were proposed. In the first case, the standard compensation strategy is extended by a harmonic compensator that suppresses the residual 6th harmonic component in dq- axes currents. The last strategy detects the polarity of the estimated phase currents that are obtained by the Kalman filter. All compensation strategies have been verified by MATLAB/Simulink simulations and by experiments on real drives.

Los estilos APA, Harvard, Vancouver, ISO, etc.

41

Boström, Patrik. "Revisiting Observed Changes in Cloud Properties over Europe". Thesis, Uppsala universitet, Luft-, vatten och landskapslära, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-179997.

Texto completo

Resumen

The Earth’s atmosphere is a vulnerable system which is easily changed by micro- and macrophysical variations. Big decreases in pollution levels of sulfur dioxide over Central Europe from 1980s to 2000s led to decreased mass concentration of atmospheric solid and liquid particles. This gives the opportunity to investigate how these particles influence the atmosphere. Newly released satellite climatology data was used to analyze statistics of cloud properties during four years in the high polluted atmosphere (1985-88) and four years in the less polluted atmosphere (2004-07). These two periods were investigated in collaboration with Atmospheric Remote Sensing Unit of the research department of the Swedish Meteorological and Hydrological Institute (SMHI). Cloud top temperature of liquid clouds over polluted regions during the earlier period was colder by more than 2 K and more than 5 K for only optical thin liquid clouds. The changes in mass concentrations of atmospheric particles derived by the sulfur dioxide emissions are shown to be a highly possible factor to the observed cloud changes.
Jordens atmosfär är ett känsligt system som lätt förändras av mikro- samt makrofysikaliska variationer. Stora minskningar i föroreningsnivåer av svaveldioxid över centrala Europa från 1980 till 2000-talet ledde till minskade masskoncentrationer av fasta och flytande atmosfäriska partiklar. Detta ger en möjlighet att undersöka hur dessa partiklar påverkar atmosfären. Nyligen utvecklad klimatologisk satellitdata användes för att analysera statistik av molnegenskaper under fyra år i en högt förorenad atmosfär (1985-88) och fyra år i en mindre förorenad atmosfär (2004-07). De två perioderna undersöktes i samarbete med Enheten för atmosfärisk fjärranalys av forskningsavdelningen till Sveriges meteorologiska och hydrologiska institut (SMHI). Molntopptemperaturen för moln i vätskefas över förorenande områden under den tidigare perioden var mer än 2 K kallare och mer än 5 K kallare för endast optiskt tunna moln i vätskefas. Förändringarna i masskoncentrationer för atmosfäriska partiklar och droppar med svaveldioxidusläpp som ursprung visas vara högst möjliga att ligga bakom de observerade molnförändringarna.

Los estilos APA, Harvard, Vancouver, ISO, etc.

42

Littell, Ashley. "Spatio-Temporal Analysis of Observed Soil Moisture from Nebraska". TopSCHOLAR®, 2007. http://digitalcommons.wku.edu/theses/402.

Texto completo

Resumen

Soil moisture is a measure of the water content in a soil that is dependent upon precipitation, evapotranspiration, runoff, drainage, and irrigation. Nebraska is one of the few states that measures soil moisture in an extensive network that records weather variables on a daily basis. Daily soil moisture observations are collected from depths of 10, 25, 50, and 100 centimeters and analyzed in this research. Data from these stations are evaluated on the spatial and temporal scales using spatial interpolations, time-series analysis, and cross-correlations to better understand the variations of soil moisture in the Northern Great Plains. Spatial interpolation grids were created for May through October of 2005, after the data were grouped into datasets of weekly, biweekly, and monthly observations. These datasets were imported into a Geographic Information System (GIS) and the Ordinary Kriging method was applied for spatial interpolation. The interpolation parameters were set to create output surfaces of 4x4, 16x16, 32x32, and 64x64 kilometer grids for analysis of their variations. As expected, it is found that soil moisture content is higher in southeastern Nebraska and lower in the northwest. Changes in the grid size render small scale variations, however, the general pattern of estimated soil moisture distribution does not change. The temporal analysis concluded that the soil's physical properties have a much greater effect on soil moisture than a station's location within the east-west moisture gradient. Sandy soils were consistently drier, while silt and clay soils retained water for a longer duration. The topmost layer of soil experiences the greatest variation due to interactions with the surface boundary layer. The highest water content values for silty soils were observed in the summer months, while the highest values for sandy soils were observed in the spring and fall months. The most soil moisture variation occurs in the summer and fall, while the least amount of variation occurs in spring and winter. Cross-correlations, measuring the time-lag relationship, demonstrated the impact of soil physical properties on soil moisture by depth, the influence of precipitation on 10 and 25 cm depth soil moisture, and the impact of near-surface soil moisture on maximum surface temperature. A stronger relationship was observed between soil moisture and maximum surface temperatures than with precipitation and soil moisture at various depths.

Los estilos APA, Harvard, Vancouver, ISO, etc.

43

Chang, Yanling. "A leader-follower partially observed Markov game". Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/54407.

Texto completo

Resumen

The intent of this dissertation is to generate a set of non-dominated finite-memory policies from which one of two agents (the leader) can select a most preferred policy to control a dynamic system that is also affected by the control decisions of the other agent (the follower). The problem is described by an infinite horizon total discounted reward, partially observed Markov game (POMG). Each agent’s policy assumes that the agent knows its current and recent state values, its recent actions, and the current and recent possibly inaccurate observations of the other agent’s state. For each candidate finite-memory leader policy, we assume the follower, fully aware of the leader policy, determines a policy that optimizes the follower’s criterion. The leader-follower assumption allows the POMG to be transformed into a specially structured, partially observed Markov decision process that we use to determine the follower’s best response policy for a given leader policy. We then present a value determination procedure to evaluate the performance of the leader for a given leader policy, based on which non-dominated set of leader polices can be selected by existing heuristic approaches. We then analyze how the value of the leader’s criterion changes due to changes in the leader’s quality of observation of the follower. We give conditions that insure improved observation quality will improve the leader’s value function, assuming that changes in the observation quality do not cause the follower to change its policy. We show that discontinuities in the value of the leader’ criterion, as a function of observation quality, can occur when the change of observation quality is significant enough for the follower to change its policy. We present conditions that determine when a discontinuity may occur and conditions that guarantee a discontinuity will not degrade the leader’s performance. This framework has been used to develop a dynamic risk analysis approach for U.S. food supply chains and to compare and create supply chain designs and sequential control strategies for risk mitigation.

Los estilos APA, Harvard, Vancouver, ISO, etc.

44

Jaberansari, Negar. "Bayesian Hierarchical Models for Partially Observed Data". University of Cincinnati / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1479818516727153.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

45

Morris, David Charles. "Comparing job component validity to observed validity across jobs". CSUSB ScholarWorks, 2002. https://scholarworks.lib.csusb.edu/etd-project/2046.

Texto completo

Resumen

Five hundred and eighteen observed validity coefficients based on correlations between commercially available test data and supervisory ratings of overall job performances were collected in 89 different job titles. Using Dictionary of Occupational Title Codes, Job Component Validity (JUV) estimates based on similar job titles residing in the PAQ Service database were collected and averaged across the General Aptitude Test.

Los estilos APA, Harvard, Vancouver, ISO, etc.

46

Pourasghar-Lafmejani, Masoud. "On the fault diagnosis of dynamic systems using set-based approaches". Doctoral thesis, Universitat Politècnica de Catalunya, 2019. http://hdl.handle.net/10803/670997.

Texto completo

Resumen

Model-based Fault Detection and Isolation (FDI) is a major theoretical topic that is becoming increasingly to one of the most significant key features to increase safety and reliability of complex automatic control systems. Basically, model-based FDI relies on the use of a mathematical model to describe the system behavior. However, uncertainty remains always present when modelling a system since its effect is non-negligible even if there are no process faults. One way to deal with uncertainty is to assume its unknown-but-bounded description. Generally speaking, the uncertainty in so-called \emph{set-based approaches} is represented by a set that is unknown-but-bounded at each time instant. Set-based approaches can be classified into three main paradigms: interval observer approach, set-membership approach and set-invariance approach. In this thesis, the influence of the uncertainty is addressed using the set-based approaches considering a zonotopic representation. Moreover, this thesis presents both analysis and comparison of the set-based approaches for the state estimation and FDI frameworks with the goal of establishing the advantages and disadvantages of each approach, and also, to find out their relationship in a formal mathematical framework. However, the mentioned set-based approaches implicitly assume time-varying uncertainty. In the set-based approach, the propagation of the state set is affected by several problems such as the wrapping effect, temporal variance on uncertain parameters (or uncertain parameter time dependency) and range evaluation of an interval function, especially in the case of using the interval hull of the set at each iteration. Therefore, conservative and unstable results may be obtained (for even a stable system) when using the set-based approach in the simulation of the system with parametric time-invariant uncertainties. On the other hand, the approximated state set can be computed based on a set of point-wise trajectories. This type of approach is called \emph{trajectory-based approach}. Therefore, the uncertain parameter time dependency is preserved if the set of point-wise trajectories is generated using the mentioned trajectory-based approach.
La detección y el aislamiento de fallos (DAF) basado en modelos es un problema teórico importante que se está convirtiendo cada vez m ás en una de las características clave para aumentar la seguridad y abilidad de los sistemas de control autom ático complejos. Básicamente, la DAF basada en modelos utiliza un modelo m atem ático para describir el comportamiento del sistem a. Sin embargo, la incertidumbre permanece siempre presente cuando se modela un sistema, ya que su efecto no es despreciable, incluso si no hay fallos que afecten al sistema. Una form a de tener en cuenta la incertidumbre es asumir una descripción desconocida pero acotada. En términos generales, la incertidumbre en los llamados enfoques basados en conjuntos se representa mediante un conjunto que es desconocido pero acotado en cada instante de tiempo. Los enfoques basados en conjuntos se pueden clasicar en tres paradigmas principales: enfoque basado en observadores intervalares, enfoque de pertenencia al conjunto y enfoque basados en conjuntos invariante. En esta tesis, la inuencia de la incertidumbre se aborda utilizando los enfoques basados en conjuntos y representaciones zonotópicas de los mismos. Adem ás, esta tesis presenta tanto el análisis como la comparación de los enfoques basados en conjuntos para la estimación de estado con el objetivo de establecer las ventajas y desventajas de cada enfoque, y también, para descubrir su relación en un m arco matemático formal. Sin embargo, los mencionados enfoques basados en conjuntos suponen implícitamente una incertidumbre variante en el tiempo. En el enfoque basado en pertenencia a conjuntos, la propagación del conjunto de estados se ve afectada por varios problemas, como el efecto de del aum ento de incertidumbre, la varianza temporal de los parámetros inciertos (o la dependencia temporal de los parámetros inciertos) y la evaluación de rango de una función de intervalo, especialm ente cundo se usa el "lnterval Hull" en cada iteración. Por lo tanto, se pueden obtener resultados conservadores (incluso para un sistema estable) en la simulación del sistema con incertidumbres param étricas invariantes en el tiempo con el uso del enfoque basado en pertenencia a conjuntos. Por otro lado, el conjunto de estados aproximados se puede calcular con base en un conjunto de trayectorias puntuales. Este tipo de enfoque se denomina enfoque basado en trayectorias. Por lo tanto, la dependencia temporal del parámetro incierto se conserva si el conjunto de trayectorias puntuales se genera utilizando el mencionado enfoque basado en trayectorias
La detecció i aïllament de fallades basada en models (DAF) és un problema teòric important que està esdevenint cada cop més una de les característiques clau per augmentar la seguretat i la fiabilitat dels sistemes de control automàtic complexos. Bàsicament, la DAF basada en models es basa en l’ús d'un model matemàtic per descriure el comportament del sistema. Tanmateix, la incertesa roman sempre present quan es modelitza un sistema ja que el seu efecte no és insignificant, fins i tot si no hi ha fallades en el procés. Una forma de fer front a la incertesa és assumir una descripció desconeguda però acotada. En termes generals, la incertesa en els anomenats enfocaments basats en conjunts està representada per un conjunt desconegut però acotat en cada instant. Els enfocaments basats en conjunts es poden classificar en tres paradigmes principals: l'enfocament d'observadors d'intervals, l'enfocament de pertinença a conjunts i l'enfocament d’invariància. En aquesta tesi, s'aborda la influència de la incertesa mitjançant els enfocaments basats en conjunts fent servir una representació zonotòpica. A més, aquesta tesi presenta tant l’anàlisi com la comparació dels enfocaments basats en conjunts per a l’estimació de l'estat i la seva aplicació a DAF amb l'objectiu d'establir els avantatges i desavantatges de cada enfocament i, a més, conèixer la seva relació en un marc matemàtic formal. Tanmateix, els esmentats enfocaments basats en conjunts assumeixen implícitament una incertesa variable en el temps. En l'enfocament basat en conjunts, la propagació del conjunt d'estats es veu afectada per diversos problemes com l'efecte d'embolcall, la variació temporal dels paràmetres incerts (o la dependència en el temps dels paràmetres incerts) i l’avaluació del rang d'una funció intervalar, especialment en el cas d'utilitzar el "Interval Hull" del conjunt a cada iteració. Per tant, es poden obtenir resultats conservadors i inestables (fins i tot per a un sistema estable) en la simulació del sistema amb incerteses temporals invariants paramètriques amb l’ús del mètode basat en conjunts. D'altra banda, el conjunt d'estats aproximat es pot calcular a partir d'un conjunt de trajectòries puntuals. Aquest tipus d'enfocament s'anomena enfocament basat en trajectòries. Per tant, la dependència en el temps del paràmetres es conserva si el conjunt de trajectòries puntuals es generen utilitzant l'enfocament basat en trajectòries esmentat. Aquesta tesi inclou sis parts. La primera part, presenta l'estat de la tècnica i fa una introducció de les eines de recerca. La segona part proposa la relació matemàtica entre l'observador intervalar i els enfocaments de pertinença. La tercera part se centra en la integració dels enfocaments basats en observadors i d’invariància de conjunts en la seva aplicació a DAF caracteritzant la mínima fallada detectable i aïllable. La quarta part presenta el disseny d'un observador intervalar que millora la sensibilitat a les fallades respecte les pertorbacions. La cinquena part proposa el disseny robust d'observadors d'intervals per a sistemes incerts, subjectes a incerteses tant temporals com variables es el temps. L'última part presenta algunes conclusions, resumeix la investigació realitzada i estableix les bases per al treball futur

Los estilos APA, Harvard, Vancouver, ISO, etc.

47

Zhou, Bi Ting. "Testing for jumps of discretely observed processes :an empirical analysis". Thesis, University of Macau, 2015. http://umaclib3.umac.mo/record=b3335821.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

48

Krause, Maria. "High-sensitivity analysis of the Cygnus region observed with VERITAS". Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2017. http://dx.doi.org/10.18452/17750.

Texto completo

Resumen

Teilchenschauer können sowohl durch Photonen als auch durch geladene Teilchen erzeugt werden. Letztere kommen etwa 1000-mal häufiger vor als die durch Photonen erzeugten Teilchenschauer. Dies beeinflusst die Sensitivität des VERITAS-Experiments erheblich. Um diese gegenüber Gammastrahlung zu steigern, ist es notwendig, die Gamma-Hadron Separation zu verbessern. In dieser Dissertation wurde eine Analysemethode, basierend auf Boosted Decision Trees (BDTs), entwickelt und für die Analyse der Daten des VERITAS-Observatoriums optimiert. Das große Potential zur Unterscheidung von Teilchenschauern der Photonen und der Hadronen wird anhand ausführlicher Tests und systematischer Studien mit Simulationen von Gammastrahlung und Beobachtungsdaten der kosmischen Strahlung verdeutlicht. Im Vergleich zur Standardanalyse kann die Sensitivität mit Hilfe der BDT Methode deutlich erhöht werden. Die entwickelte und optimierte BDT Methode wird auf Beobachtungsdaten der Cygnus-Region angewandt. Diese ist eine der aktivsten sternbildenden Regionen unserer Galaxie und beherbergt eine Vielzahl von potentiellen kosmischen Teilchenbeschleunigern. Aufgrund der enormen Dichte an potentiellen Quellen sowie der hohen Wahrscheinlichkeit, neue Quellen zu detektieren und zu identifizieren, wurde die Cygnus-Region von April 2007 bis Juni 2012 mit VERITAS beobachtet. Die Beobachtungsdaten wurden mit einer für diese Himmelsregion optimierten Analysetechnik aufbereitet und ausgewertet. Vier Quellen hochenergetischer Gammastrahlung wurden detektiert: VER J2031+415, VER J2019+407, VER J2019+368 und VER J2016+371. Detaillierte spektrale Untersuchungen werden vorgestellt, gefolgt von einer Diskussion möglicher assoziierter Objekte in anderen Wellenlängenbereichen. Schließlich konnten mit Hilfe der verbesserten Sensitivität von VERITAS durch die BDT Methode niedrigere Obergrenzen für den Fluss der hochenergetischen Gammastrahlung von 50 potentiellen Gammastrahlungsquellen abgeleitet werden.
Particle showers can be generated by photons or charged cosmic rays. Before applying any selection requirements, showers initiated by cosmic rays are about 1000 times more common than those initiated by photons. This constitutes a vast amount of background events measured by VERITAS, limiting the sensitivity to gamma rays. To improve the separation power between gamma-ray and cosmic-ray showers, an analysis technique based on Boosted Decision Trees (BDTs) is developed. Extensive tests are performed to study the discrimination capabilities of the BDT method using cosmic-ray data and Monte-Carlo simulations of gamma rays. Compared to the VERITAS standard analysis, the BDT method improves the sensitivity of detecting gamma rays. The BDT method is applied to data obtained from observations of the Cygnus region, one of the most active star-forming regions of our Galaxy. It hosts numerous astrophysical objects capable of accelerating particles to extremely high energies, such as supernova remnants, pulsar wind nebula, binary systems, and associations of massive OB stars. The high density of potential sources and the information from multiwavelength observations led VERITAS to perform observations of the Cygnus region between April 2007 and June 2012. Four sources were detected in very-high-energy gamma rays: VER J2031+415, VER J2019+407, VER J2019+368, and VER J2016+371. They were analysed in detail and compared to possible counterparts measured at other wavelengths. The spectra of the three of the sources were fit to a power law. Two out of three spectra are consistent with those obtained in previous measurements, where the third one shows a softer spectral index than the published result. Finally, the greater sensitivity reached with the BDT method allowed the derivation of the most stringent upper limits to date on 50 potential gamma-ray sources.

Los estilos APA, Harvard, Vancouver, ISO, etc.

49

YOU, DAN. "Supervisory Control and Analysis of Partially-observed Discrete Event Systems". Doctoral thesis, Università degli Studi di Cagliari, 2021. http://hdl.handle.net/11584/308984.

Texto completo

Resumen

Nowadays, a variety of real-world systems fall into discrete event systems (DES). In practical scenarios, due to facts like limited sensor technique, sensor failure, unstable network and even the intrusion of malicious agents, it might occur that some events are unobservable, multiple events are indistinguishable in observations, and observations of some events are nondeterministic. By considering various practical scenarios, increasing attention in the DES community has been paid to partially-observed DES, which in this thesis refer broadly to those DES with partial and/or unreliable observations. In this thesis, we focus on two topics of partially-observed DES, namely, supervisory control and analysis. The first topic includes two research directions in terms of system models. One is the supervisory control of DES with both unobservable and uncontrollable events, focusing on the forbidden state problem; the other is the supervisory control of DES vulnerable to sensor-reading disguising attacks (SD-attacks), which is also interpreted as DES with nondeterministic observations, addressing both the forbidden state problem and the liveness-enforcing problem. Petri nets (PN) are used as a reference formalism in this topic. First, we study the forbidden state problem in the framework of PN with both unobservable and uncontrollable transitions, assuming that unobservable transitions are uncontrollable. For ordinary PN subject to an admissible Generalized Mutual Exclusion Constraint (GMEC), an optimal on-line control policy with polynomial complexity is proposed provided that a particular subnet, called observation subnet, satisfies certain conditions in structure. It is then discussed how to obtain an optimal on-line control policy for PN subject to an arbitrary GMEC. Next, we still consider the forbidden state problem but in PN vulnerable to SD-attacks. Assuming the control specification in terms of a GMEC, we propose three methods to derive on-line control policies. The first two lead to an optimal policy but are computationally inefficient for large-size systems, while the third method computes a policy with timely response even for large-size systems but at the expense of optimality. Finally, we investigate the liveness-enforcing problem still assuming that the system is vulnerable to SD-attacks. In this problem, the plant is modelled as a bounded PN, which allows us to off-line compute a supervisor starting from constructing the reachability graph of the PN. Then, based on repeatedly computing a more restrictive liveness-enforcing supervisor under no attack and constructing a basic supervisor, an off-line method that synthesizes a liveness-enforcing supervisor tolerant to an SD-attack is proposed. In the second topic, we care about the verification of properties related to system security. Two properties are considered, i.e., fault-predictability and event-based opacity. The former is a property in the literature, characterizing the situation that the occurrence of any fault in a system is predictable, while the latter is a newly proposed property in the thesis, which describes the fact that secret events of a system cannot be revealed to an external observer within their critical horizons. In the case of fault-predictability, DES are modeled by labeled PN. A necessary and sufficient condition for fault-predictability is derived by characterizing the structure of the Predictor Graph. Furthermore, two rules are proposed to reduce the size of a PN, which allow us to analyze the fault-predictability of the original net by verifying that of the reduced net. When studying event-based opacity, we use deterministic finite-state automata as the reference formalism. Considering different scenarios, we propose four notions, namely, K-observation event-opacity, infinite-observation event-opacity, event-opacity and combinational event-opacity. Moreover, verifiers are proposed to analyze these properties.

Los estilos APA, Harvard, Vancouver, ISO, etc.

50

Barlow, James Mathew. "Interpretation of observed atmospheric variations of CO2 and CH4". Thesis, University of Edinburgh, 2015. http://hdl.handle.net/1842/10507.

Texto completo

Resumen

The overarching theme of my thesis is understanding observed variations of northern hemisphere atmospheric carbon dioxide (CO2) and methane (CH4) concentrations. I focus my analysis on high-latitude observations of these gases, as there are large stores of carbon in boreal vegetation and tundra which are vulnerable to rapid warming in the Arctic. My thesis is split into two parts. First, I use the wavelet transform to spectrally decompose observed multi-decadal timeseries for CO2 and CH4. I perform a series of numerical experiments based on synthetic data in order to characterise the errors associated with the analysis. For CO2, I analyse the phase and amplitude of the detrended seasonal cycle of CO2 to infer changes about carbon uptake by northern vegetation. I do not find a long-term change in the length of the carbon uptake period despite significant changes in the spring and autumn phase. I do find an increase in the rate of peak uptake which coincides with the observed increase in seasonal amplitude. These results suggest that the carbon uptake period of boreal vegetation has become more intense but has not changed in length, which provides evidence for an increase in net uptake of CO2 in the high latitudes. For CH4, I test the hypothesis that an increase in Arctic wetland emissions could result in a decrease in the seasonal amplitude of CH4 in the high latitudes. This hypothesis is based on the fact that the seasonal minima of CH4 roughly coincides with the peak of high latitude wetland CH4 emissions. I find that the CH4 seasonal amplitude has significantly decreased at a number of high-latitude sites. However I also find that atmospheric transport appears to drive much of the variability in high-latitude CH4 and that transport could also be responsible for the observed changes in amplitude. I show that an increase in wetland emissions is likely to have a more pronounced effect on the high-latitude CH4 seasonal cycle in the future. In the second section of my thesis, I describe a series of experiments in collaboration with the UK Astronomy Technology Centre, in which I characterise a new instrument technology for satellite applications to observe changes in CO2 from low-Earth orbit. The proof of concepts experiments were performed with a bench top hyperspectral imager. I show that the instrument is able to capture clean spectra at the wavelengths required for CO2 with low levels of scattered light between spectra.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Tesis sobre el tema "Observer analysis"

Crea una cita precisa en los estilos APA, MLA, Chicago, Harvard y otros