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Bergeron, André 1967. "Multiple-step gaze shifts reveal gaze position error in brainstem". Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=82831.
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The superior colliculus (SC) is a structure that is implicated in the control of visual orienting behaviors. The SC contains a motor map which encodes saccade vectors topographically. Small saccades are encoded rostrally, larger ones caudally. More recently, it was shown that the rostral part of the SC contains a specialized "fixation zone". A group of cells located in the rostral SC have been called SC fixation neurons (SCFNs). SCFNs via projections to "omni-pause" neurons (OPNs) seem to play an important role during fixation behavior by holding gaze on target for a certain period of time through inhibition of the gaze saccade generator. By comparison, the caudal SC generates saccadic commands via its direct connections to the gaze saccade generator. When the head is unrestrained, large gaze shifts are generally made with the contribution of eye and head (gaze = eye-in-head + head-in-space). For a gaze shift executed in one step, gaze, eye, and head trajectories are very stereotyped; each part of the trajectory is correlated in time to another. Consequently, it is difficult to relate brainstem cells activity to a specific trajectory. A differentiation between the trajectories can be obtained by the use of multiple-step gaze-shifts that cats often use naturally. Multiple-step gaze shifts are gaze displacements that are composed of a variable number of gaze saccades separated by periods of steady fixation. The main goal of this thesis was to relate cell activity of both SC cells and OPNs with specific features of the multiple-step gaze shifts. The study of SC cells during multiple-step gaze shifts revealed that neither SCFNs nor cells on the SC motor map encode the complex motor sequence of steps and plateaus in multiple step gaze shifts. They are concerned with keeping track of the difference between current gaze position and the final intended gaze destination independently of how the gaze displacement is achieved. This finding challenges
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Temple, Thomas J. (Thomas John). "Autonomous error bounding of position estimates from GPS and Galileo". Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/37884.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2006.Includes bibliographical references (p. 79-81).
In safety-of-life applications of satellite-based navigation, such as the guided approach and landing of an aircraft, the most important question is whether the navigation error is tolerable. Although differentially corrected GPS is accurate enough for the task most of the time, anomalous measurement errors can create situations where the navigation error is intolerably large. Detection of such situations is referred to as integrity monitoring. Due to the non:stationary nature of the error sources, it is impossible to predetermine an adequate error-bound with the required confidence. Since the errors at the airplane can be different from the errors at reference stations, integrity can't be assured by ground monitoring. It is therefore necessary for the receiver on the airplane to autonomously assess the integrity of the position estimate in real-time. In the presence of multiple errors it is possible for a set of measurements to remain self-consistent despite containing errors. This is the primary reason why GPS has been unable to provide adequate integrity for aircraft approach. When the Galileo system become operational, there will be many more independent measurements. The more measurements that are available, the more unlikely it becomes that the errors happen to be self-consistent by chance. This thesis will quantify this relationship.
(CONT.) In particular, we determine the maximum level of navigation error at a given probability as a function of the redundancy and consistency of the measurements. Rather than approach this problem with statistical tests in mind, we approach this as a machine learning problem in which we empirically determine an optimal mapping from the measurements to an error bound. In so doing we will examine a broader class of tests than has been considered before. With a sufficiently large and demanding training data, this approach provides error-bounding functions that meet even the strictest integrity requirements of precision approaches. We determine the optimal error-bounding function and show that in a GPS + Galileo constellation, it can meet the requirements of Category I, II and III precision approach-a feat that has proven difficult for GPS alone. This function is shown to underestimate the level of error at a rate of less than 10-7 per snapshot regardless of the pseudorange error distribution. This corresponds to a rate of missed detection of less than 10-9 for all approach categorizations. At the same time, in a 54 satellite constellation, the level of availability for Category I precision approaches availability exceeds 99.999%. For Category II and III precision approaches, it can provide availability exceeding 99.9% with either a 60 satellite constellation, or with a modest improvement over existing LAAS corrections.
by Thomas J. Temple.
S.M.
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Kuratomi, Alejandro. "GNSS Position Error Estimated by Machine Learning Techniques with Environmental Information Input". Thesis, KTH, Skolan för industriell teknik och management (ITM), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-262692.
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In Intelligent Transport Systems (ITS), specifically in autonomous driving operations, accurate vehicle localization is essential for safe operations. The localization accuracy depends on both position and positioning error estimates. Technologies aiming to improve positioning error estimation are required and are currently being researched. This project has investigated machine learning algorithms applied to positioning error estimation by assessing relevant information obtained from a GNSS receiver and adding environmental information coming from a camera mounted on a radio controlled vehicle testing platform. The research was done in two stages. The first stage consists of the machine learning algorithms training and testing on existing GNSS data coming from Waysure´s data base from tests ran in 2016, which did not consider the environment surrounding the GNSS receiver used during the tests. The second stage consists of the machine learning algorithms training and testing on GNSS data coming from new test runs carried on May 2019, which include the environment surrounding the GNSS receiver used. The results of both stages are compared. The relevant features are obtained as a result of the machine learning decision trees algorithm and are presented. This report concludes that there is no statistical evidence indicating that the tested environmental input from the camera could improve positioning error estimation accuracy with the built machine learning models.Inom Intelligenta transportsystem (ITS), specifikt för självkörande fordon, så är en exakt fordonspositionering en nödvändighet för ökad trafiksäkerhet. Positionsnoggrannheten beror på estimering av både positionen samt positionsfelet. Olika tekniker och tillämpningar som siktar på att förbättra positionsfeluppskattningen behövs, vilket det nu forskas kring. Denna uppsats undersöker olika maskininlärningsalgoritmer inriktade på estimering av positionsfel. Algoritmerna utvärderar relevant information från en GNSS-mottagare, samt information från en kamera om den kringliggande miljön. En GNSS-mottagare och kamera monterades på en radiostyrd mobil testplattform för insamling av data. Examensarbetet består av två delar. Första delen innehåller träning och testning av valda maskininlärningsalgoritmer med GNSS-data tillhandahållen av Waysure från tester gjorda under 2016. Denna data inkluderar ingen information från den omkringliggande miljön runt GNSS-mottagaren. Andra delen består av träning och testning av valda maskininlärningsalgoritmer på GNSS-data som kommer från nya tester gjorda under maj 2019, vilka inkluderar miljöinformation runt GNSS-mottagaren. Resultaten från båda delar analyseras. De viktigaste egenskaper som erhålls från en trädbaserad modell, algoritmens beslutsträd, presenteras. Slutsatsen från denna rapport är att det inte går att statistiskt säkerställa att inkludering av information från den omkringliggande miljön från en kamera förbättrar noggrannheten vid estimering av positionsfelet med de valda maskininlärningsmodellerna.
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Chretien, Ludovic. "POSITION SENSORLESS CONTROL OF NON-SALIENT PERMANENT MAGNET SYNCHRONOUS MACHINE". University of Akron / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=akron1145286531.
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Ronquist, Anton y Birger Winroth. "Estimation and Compensation of Load-Dependent Position Error in a Hybrid Stepper Motor". Thesis, Linköpings universitet, Reglerteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-129554.
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Hybrid stepper motors are a common type of electric motor used throughout industry thanks to its low-cost, high torque at low speed and open loop positioning capabilities. However, a closed loop control is often required for industrial applications with high precision requirements. The closed loop control can also be used to lower the power consumption of the motor and ensure that stalls are avoided. It is quite common to utilise a large and costly position encoder or resolver to feedback the position signal to the control logic. This thesis has explored the possibility of using a low-cost position sensor based on Hall elements. Additionally, a sensorless estimation algorithm, using only stator winding measurements, has been investigated both as a competitive alternative and as a possible complement to the position sensor. The thesis work summarises and discusses previous research attempts to adequately measure or estimate and control the hybrid stepper motors position and load angle without using a typical encoder or resolver. Qualitative results have been produced through simulations prior to implementation and experimental testing. The readings from the position sensor is subject to noise, owing to its resolution and construction. The position signal has been successfully filtered, improving its accuracy from 0.56° to 0.25°. The output from the sensorless estimation algorithm is subject to non-linear errors caused by errors in phase voltage measurements and processing of velocity changes. However, the dynamics are reliable at constant speeds and could be used for position control.
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Kilic, Ergin. "Novel Position Measurement And Estimation Methods For Cnc Machine Systems". Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/2/12608762/index.pdf.
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Precision control of translational motion is vital for many CNC machine tools as the motion of the machinery affects the dimensional tolerance of the manufactured goods. However, the direct measurement along with the accurate motion control of machine usually requires relatively expensive sensors i.e. potentiometers, linear scales, laser interferometers. Hence, this study attempts to develop reference models utilizing low-cost sensors (i.e. rotary encoders) for accurate position estimation. First, an indirect measurement performance is investigated on a Timing Belt driven carriage by a DC Motor with a backlash included Gearbox head. An advanced interpolated technique is proposed to compensate the position errors while using indirect measurement to reduce the total cost. Then, a similar study was realized with a ball screw driven system. Next, a cable drum driven measurement technique is proposed to the machines which have long travel distance like plasma cutters. A test setup is proposed and manufactured to investigate the capstan drive systems. Finally, characteristics of Optical Mouse Sensors are investigated from different point of views and a test setup is proposed and manufactured to evaluate their performances in long terms. Beside all of these parts, motion control algorithms and motion control integrated circuits are designed and manufactured to realize experimental studies in a detailed manner.
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Eliasson, Mattias. "A Kalman filter approach to reduce position error for pedestrian applications in areas of bad GPS reception". Thesis, Umeå universitet, Institutionen för datavetenskap, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-92829.
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The number of GPS-enabled devices are growing rapidly. A large segment of the growth is coupled to the growth of smartphones. Some location-based applications are relatively simple, requiring only a rough position estimate. Other applications provide services where the usefulness of the application is directly connected to the accuracy of GPS positioning. Lifelogging, fitness, and navigation are some types of applications where precise location estimation greatly benefits the user. The GPS technology is available world wide and 24 hours per day. Its accuracy is not uniform, varying over time of day and place. Buildings can reflect or block the signal, the atmosphere delays it, satellite clock and orbit errors introduce bias. These are some of the error sources affecting GPS positioning. Many applications with need of high accuracy are used in everyday life. Users will eventually venture into areas unsuitable for GPS positioning. In these situations, these applications may not function sufficiently well. In this thesis, a data fusion method called the Kalman filter is evaluated as a means of improving the GPS positioning. A simple motion model is employed, tracking the position and velocity. The motion model utilizes sensors commonly available in a modern day smartphone. The Kalman filter will be evaluated through comparison to the raw data and a simple moving average filter. The results show that the Kalman filter is able to significantly reduce the variance compared to the raw data, but not significantly lower than the moving average filter.
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Sama, Michael P. "PRECISE EVALUATION OF GNSS POSITION AND LATENCY ERRORS IN DYNAMIC AGRICULTURAL APPLICATIONS". UKnowledge, 2013. http://uknowledge.uky.edu/bae_etds/14.
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A method for precisely synchronizing an external serial data stream to the pulse-per-second (PPS) output signal from a global navigation satellite-based system (GNSS) receiver was investigated. A signal timing device was designed that used a digital signal processor (DSP) with serial inputs and input captures to generate time stamps for asynchronous serial data based on an 58593.75 Hz internal timer. All temporal measurements were made directly in hardware to eliminate software latency. The resolution of the system was 17.1 µs, which translated to less than one millimeter of horizontal position error at travel speeds typical of most agricultural operations.
The dynamic error of a TTS was determined using a rotary test fixture. Tests were performed at angular velocities ranging from 0 to 3.72 rad/s and a radius of 0.635 m. Average latency from the TTS was shown to be consistently near 0.252 s for all angular velocities and less variable when using a reflector based machine target versus a prism target. Sight distance from the target to the TTS was shown to have very little effect on accuracy between 4 and 30 m. The TTS was determined to be a limited as a position reference for dynamic GNSS and vehicle auto-guidance testing based on angular velocity.
The dynamic error of a GNSS receiver was determined using the rotary test fixture and modeled as discrete probability density functions for varying angular velocities and filter levels. GNSS position and fixture data were recorded for angular velocities of 0.824, 1.423, 2.018, 2.618, and 3.222 rad/s at a 1 m radius. Filter levels were adjusted to four available settings including; no filter, normal filter, high filter, and max filter. Each data set contained 4 hours of continuous operation and was replicated three times. Results showed that higher angular velocities increased the variability of the distribution of error while not having a significant effect on average error. The distribution of error tended to change from normal distributions at lower angular velocities to uniform distributions at higher angular velocities. Internal filtering was shown to consistently increase dynamic error for all angular velocities.
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Suddapalli, Rajesh. "Aircraft position integrity for Differential Satellite-based Navigation in the presence of both bias and noise errors". Ohio University / OhioLINK, 2004. http://www.ohiolink.edu/etd/view.cgi?ohiou1108478721.
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MacCleery, Brian C. "Position Sensorless Implementation for a Linear Switched Reluctance Machine". Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/33856.
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The development of an add-on sensorless position estimator for a 4.8 m Linear Switched Reluctance Machine (LSRM) with minimal modifications to the transducer-based controller is investigated for the first time in this study. LSRMs require position feedback for closed-loop control but present a low cost, high energy efficiency alternative for linear actuation due to their rugged construction and single-sided excitation. Mechanical position transducers mounted on the vehicle are expensive and can impact reliability. The use of a sensorless position estimator removes all electronics from the passive vehicle, resulting in considerable reductions in cost, maintenance, and mechanical complexity.
This study examines the use of an add-on processor and data acquisition system for sensorless position estimation. An approach exploiting the active phase windings is used to preserve the normal operation of the transducer-based DSP controller with the goal of limiting reductions in high performance features such as force ripple reduction and velocity control [3]. The estimator system is retrofit to the transducer-based DSP controller by mimicking the output of a mechanical position sensor by emulating a Quadrature encoder. The feasibility and design issues for an add-on or retrofit position estimator are investigated. Although sensorless schemes for rotary Switched Reluctance Machines (SRMs) have been studied in detail, the problem of sensorless implementations for LSRMs has not been addressed. Experimental validation of the proposed sensorless estimation scheme is attempted, but closed-loop operation is not achieved successfully due to air gap fluctuations. In depth analysis of the sources and propagation of error is presented.Master of Science
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Mosa, H. "Enhancing the bit error rate performance of ultra wideband systems using time-hopping pulse position modulation in multiple access environments". Thesis, University of Salford, 2017. http://usir.salford.ac.uk/44272/.
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Ultra-Wide Band (UWB) technology is one of the possible solutions for future short-range indoor data communication with uniquely attractive features inviting major advances in wireless communications, networking, radar, imaging, and positioning systems. A major challenge when designing UWB systems is choosing a suitable modulation technique. Data rate, transceiver complexity, and BER performance of the transmitted signal are all related to the employed modulation scheme. Several classical modulation schemes can be used to create UWB signals, some are more efficient than others. These schemes are namely, Pulse Position Modulation (PPM), Pulse Amplitude Modulation (PAM), Binary Phase Shift Keying (BPSK), and On-Off Keying (OOK) are reviewed. In the thesis, the performance of PPM system, combined with Time Hopping Spread Spectrum (THSS) multiple access technique is evaluated in an asynchronous multiple access free space environment. The multiple access interference is first assumed to be a zero mean Gaussian random process to simulate the scenario of a multi user environment. An exact BER calculation is then evaluated based on the characteristic function (CF) method, for Time Hopping-Pulse Position Modulation Ultra Wide Band (TH-PPM UWB) systems with multiple access interference (MAI) in AWGN environment. The resulting analytical expression is then used to assess the accuracy of the MAI Gaussian Approximation (GA) first assumed. The GA is shown to be inaccurate for predicting BERs for medium and large signal-to-noise ratio (SNR) values. Furthermore, the analysis of TH-PPM system is further extended to evaluate the influence of changing and optimising some of the system or signal parameters. It can be shown how the system is greatly sensitive to variations in some signal parameters, like the pulse shape, the time-shift parameter associated with PPM, and the pulse length. In addition, the system performance can be greatly improved by optimising other system parameters like the number of pulses per bit, Ns, and the number of time slots per frame, Nh. All these evaluation are addressed through numerical examples. Then, we can say that, by improving signal or system parameters, the BER performance of the system is greatly enhanced. This is achieved without imposing exact complexity to the transceiver and with moderate computational calculations.
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McCafferty, Sean, Jason Levine, Jim Schwiegerling y Eniko T. Enikov. "Goldmann and error correcting tonometry prisms compared to intracameral pressure". BIOMED CENTRAL LTD, 2018. http://hdl.handle.net/10150/626542.
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Background: Compare Goldmann applanation tonometer (GAT) prism and correcting applanation tonometry surface (CATS) prism to intracameral intraocular pressure (IOP), in vivo and in vitro. Methods: Pressure transducer intracameral IOP was measured on fifty-eight (58) eyes undergoing cataract surgery and the IOP was modulated manometrically to 10, 20, and 40 mmHg. Simultaneously, IOP was measured using a Perkins tonometer with a standard GAT prism and a CATS prism at each of the intracameral pressures. Statistical comparison was made between true intracameral pressures and the two prism measurements. Differences between the two prism measurements were correlated to central corneal thickness (CCT) and corneal resistance factor (CRF). Human cadaver eyes were used to assess measurement repeatability. Results: The CATS tonometer prism measured closer to true intracameral IOP than the GAT prism by 1.7+/-2.7 mmHg across all pressures and corneal properties. The difference in CATS and GAT measurements was greater in thin CCT corneas (2.7+/-1.9 mmHg) and low resistance (CRF) corneas (2.8+/-2.1 mmHg). The difference in prisms was negligible at high CCT and CRF values. No difference was seen in measurement repeatability between the two prisms. Conclusion: A CATS prism in Goldmann tonometer armatures significantly improve the accuracy of IOP measurement compared to true intracameral pressure across a physiologic range of IOP values. The CATS prism is significantly more accurate compared to the GAT prism in thin and less rigid corneas. The in vivo intracameral study validates mathematical models and clinical findings in IOP measurement between the GAT and CATS prisms.
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Malm, Magdalena, Nina Kronqvist, Hanna Lindberg, Lindvi Gudmundsdotter, Tarek Bass, Fredrik Y. Frejd, Ingmarie Hoiden-Guthenberg et al. "Inhibiting HER3-Mediated Tumor Cell Growth with Affibody Molecules Engineered to Low Picomolar Affinity by Position-Directed Error-Prone PCR-Like Diversification". Uppsala universitet, Enheten för biomedicinsk strålningsvetenskap, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-202922.
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The HER3 receptor is implicated in the progression of various cancers as well as in resistance to several currently used drugs, and is hence a potential target for development of new therapies. We have previously generated Affibody molecules that inhibit heregulin-induced signaling of the HER3 pathways. The aim of this study was to improve the affinity of the binders to hopefully increase receptor inhibition efficacy and enable a high receptor-mediated uptake in tumors. We explored a novel strategy for affinity maturation of Affibody molecules that is based on alanine scanning followed by design of library diversification to mimic the result from an error-prone PCR reaction, but with full control over mutated positions and thus less biases. Using bacterial surface display and flow-cytometric sorting of the maturation library, the affinity for HER3 was improved more than 30-fold down to 21 PM. The affinity is among the higher that has been reported for Affibody molecules and we believe that the maturation strategy should be generally applicable for improvement of affinity proteins. The new binders also demonstrated an improved thermal stability as well as complete refolding after denaturation. Moreover, inhibition of ligand-induced proliferation of HER3-positive breast cancer cells was improved more than two orders of magnitude compared to the previously best-performing clone. Radiolabeled Affibody molecules showed specific targeting of a number of HER3-positive cell lines in vitro as well as targeting of HER3 in in vivo mouse models and represent promising candidates for future development of targeted therapies and diagnostics.
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Nounagnon, Jeannette Donan. "Using Kullback-Leibler Divergence to Analyze the Performance of Collaborative Positioning". Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/86593.
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Geolocation accuracy is a very crucial and a life-or-death factor for rescue teams. Natural
disasters or man-made disasters are just a few convincing reasons why fast and accurate
position location is necessary. One way to unleash the potential of positioning systems is
through the use of collaborative positioning. It consists of simultaneously solving for the
position of two nodes that need to locate themselves. Although the literature has addressed
the benefits of collaborative positioning in terms of accuracy, a theoretical foundation on the
performance of collaborative positioning has been disproportionally lacking.
This dissertation uses information theory to perform a theoretical analysis of the value of
collaborative positioning.The main research problem addressed states: 'Is collaboration always beneficial? If not, can we determine theoretically when it is and when it is not?'
We show that the immediate advantage of collaborative estimation is in the acquisition of
another set of information between the collaborating nodes. This acquisition of new
information reduces the uncertainty on the localization of both nodes. Under certain conditions, this reduction in uncertainty occurs for both nodes by the same amount. Hence collaboration is beneficial in terms of uncertainty.
However, reduced uncertainty does not necessarily imply improved accuracy. So, we
define a novel theoretical model to analyze the improvement in accuracy due to collaboration.
Using this model, we introduce a variational analysis of collaborative positioning to deter-
mine factors that affect the improvement in accuracy due to collaboration. We derive range
conditions when collaborative positioning starts to degrade the performance of standalone
positioning. We derive and test criteria to determine on-the-fly (ahead of time) whether it
is worth collaborating or not in order to improve accuracy.
The potential applications of this research include, but are not limited to: intelligent
positioning systems, collaborating manned and unmanned vehicles, and improvement of GPS applications.Ph. D.
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Alm, Patrik. "Test- retest reliability of a test for joint position sense in patients with mechanical low back pain". Thesis, Luleå tekniska universitet, Institutionen för hälsovetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-74996.
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Abstract Background:Low back pain has a reported lifetime prevalence of about 70% and tops the list of years lived with disease in the developed countries. There is still to date areas on the mechanisms driving pain andmovement system impairments not fully understood. For some areas the research are evident butclinically friendly methods lack. A new test for measuring joint position sense (JPS) in the lumbar spine is tested forreliability. Objectives:Aim of this study was to evaluate test-retest reliability on a new test measuring JPS, using two laser pointers attached to the vertebrates off L1 and S1. Design:Cross-sectional observational test-retest. Methods:82 participants, 41 with mechanical low back pain and 41 healthy controls, were tested for repositioning error two times with 30-60minutes between tests. Movement directions tested was; Flexion, extension, rotation right and rotation left in sitting. Intraclasscorrelation coefficient (ICC) was used for measuring relative reliability and standard error ofmeasurement (SEM) for absolute reliability. Results:ICC in the LBP group ranged from -0,51 – 0,94 and for the whole group -0,19 – 0,84. The SEM in the LBP group ranged from 0,1 – 2,9 (95%CI -5,6 – 6,4) and for the whole group 0,1 – 3,2 (95%CI -6,3 – 6,2). Conclusions:The test-retest reliability of this JPS test shows poor to moderate reliability. Measuring joint positioning sense by using two laser pointers attached to S1 and L1 as in this study has shown not to be reliable enough to be used in clinical tests or research and can therefore not be recommended.
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Marano, Susan Aileen. "Smarticles: A Method for Identifying and Correcting Instability and Error Caused by Explicit Integration Techniques in Physically Based Simulations". DigitalCommons@CalPoly, 2014. https://digitalcommons.calpoly.edu/theses/1304.
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Using an explicit integration method in physically based animations has many advantages including conceptual and computational simplicity, however, it re- quires small time steps to ensure low numerical instability. Simulations with large numbers of individually interacting components such as cloth, hair, and fluid models, are limited by the sections of particles most susceptible to error. This results in the need for smaller time steps than required for the majority of the system. These sections can be diverse and dynamic, quickly changing in size and location based on forces in the system. Identifying and handling these trou- blesome sections could allow for a larger time step to be selected, while preventing a breakdown in the simulation.
This thesis presents Smarticles (smart particles), a method of individually de- tecting particles exhibiting signs of instability and stabilizing them with minimal adverse effects to visual accuracy. As a result, higher levels of error introduced from large time steps can be tolerated with minimal overhead. Two separate approaches to Smarticles were implemented. They attempt to find oscillating particles by analyzing a particle’s (1) past behavior and (2) behavior with re- spect to its neighbors along a strand. Both versions of Smarticles attempt to correct unstable particles using velocity dampening. Smarticles was applied to a two dimensional hair simulation modeled as a continuum using smooth particle hydrodynamic. Hair strands are formed by linking particles together using one of two methods: position based dynamics or mass-spring forces.
Both versions of Smarticles, as well as a control of normal particles, were directly compared and evaluated based on stability and visual fluidity. Hair particles were exposed to various forms of external forces under increasing time step lengths. Testing showed that both versions of Smarticles working together allowed an average increase of 18.62% in the time step length for hair linked with position based dynamics. In addition, Smarticles was able to significantly reduce visible instability at even larger time steps. While these results suggest Smarticles is successful, the method used to correct particle instability may jeopardize other important aspects of the simulation. A more accurate correction method would likely need to be developed to make Smarticles an advantageous method.
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McCafferty, Sean, Jason Levine, Jim Schwiegerling y Eniko T. Enikov. "Goldmann applanation tonometry error relative to true intracameral intraocular pressure in vitro and in vivo". BIOMED CENTRAL LTD, 2017. http://hdl.handle.net/10150/626266.
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Background: Goldmann applanation tonometry (GAT) error relative to intracameral intraocular pressure (IOP) has not been examined comparatively in both human cadaver eyes and in live human eyes. Futhermore, correlations to biomechanical corneal properties and positional changes have not been examined directly to intracameral IOP and GAT IOP. Methods: Intracameral IOP was measured via pressure transducer on fifty-eight (58) eyes undergoing cataract surgery and the IOP was modulated manometrically on each patient alternately to 10, 20, and 40 mmHg. IOP was measured using a Perkins tonometer in the supine position on 58 eyes and upright on a subset of 8 eyes. Twenty one (21) fresh human cadaver globes were Intracamerally IOP adjusted and measured via pressure transducer. Intracameral IOP ranged between 5 and 60 mmHg. IOP was measured in the upright position with a Goldmann Applanation Tonometer (GAT) and supine position with a Perkins tonometer. Central corneal thickness (CCT) was also measured. Results: The Goldmann-type tonometer error measured on live human eyes was 5.2 +/- 1.6 mmHg lower than intracameral IOP in the upright position and 7.9 +/- 2.3 mmHg lower in the supine position (p <.05). CCT also indicated a sloped correlation to error (correlation coeff. = 0.18). Cadaver eye IOP measurements were 3.1+/-2. 5 mmHg lower than intracameral IOP in the upright position and 5.4+/- 3.1 mmHg in the supine position (p <.05). Conclusion: Goldmann IOP measures significantly lower than true intracameral IOP by approximately 3 mmHg in vitro and 5 mmHg in vivo. The Goldmann IOP error is increased an additional 2.8 mmHg lower in the supine position. CCT appears to significantly affect the error by up to 4 mmHg over the sample size.
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Lhallabi, Abdessamad. "Evaluation des incertitudes dans la preparation et la realisation des traitements par radiotherapie transcutanee". Toulouse 3, 1987. http://www.theses.fr/1987TOU30076.
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Ozer, Huseyin Erman. "Air Data System Calibration For Military Transport Aircraft Modernization Program". Master's thesis, METU, 2013. http://etd.lib.metu.edu.tr/upload/12615690/index.pdf.
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This thesis presents the calibration processes of the pitot-static system, which is a part of the air data system of a military transport aircraft through flight tests. Tower fly-by method is used for air data system calibration. Altitude error caused by the position of the static port on the aircraft is determined by analyzing the data collected during four sorties with different weight, flap and landing gear configurations. The same data has been used to determine the airspeed measurement error. It has been shown that both the altitude and airspeed errors are within the allowable limits specified by FAR 25. Same method is also used for trailing cone calibration that is used for high altitude test flights for RVSM certification.
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Kilic, Ergin. "Structured Neural Networks For Modeling And Identification Of Nonlinear Mechanical Systems". Phd thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614735/index.pdf.
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Most engineering systems are highly nonlinear in nature and thus one could not
develop efficient mathematical models for these systems. Artificial neural
networks, which are used in estimation, filtering, identification and control in
technical literature, are considered as universal modeling and functional
approximation tools. Unfortunately, developing a well trained monolithic type
neural network (with many free parameters/weights) is known to be a daunting
task since the process of loading a specific pattern (functional relationship) onto a
generic neural network is proven to be a NP-complete problem. It implies that if
training is conducted on a deterministic computer, the time required for training
process grows exponentially with increasing size of the free parameter space (and
the training data in correlation). As an alternative modeling technique for
nonlinear dynamic systemsthis thesis proposed a general methodology for structured neural network topologies and their corresponding applications are realized. The main idea behind this (rather classic) divide-and-conquer approach is to employ a priori information on the process to divide the problem into its fundamental components. Hence, a number of smaller neural networks could be designed to tackle with these elementary mapping problems. Then, all these networks are combined to yield a tailored structured neural network for the purpose of modeling the dynamic system under study accurately. Finally, implementations of the devised networks are taken into consideration and the efficiency of the proposed methodology is tested on four different types of mechanical systems.
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Weigl, Martin. "Návrh nestandardních indukčtnostních a inkrementálních měřicích snímačů". Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230741.
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This diploma thesis consist of overview for position measuring methods and is mainly focused on design of non-standard inductive and incremental sensor. Specifications of those sensors is based on requirements set by MESING company. Also contains verification and testing measurement of completed sensor.
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Naab-Levy, Adam O. "Enhanced Distance Measuring Equipment Data Broadcast Design, Analysis, Implementation, and Flight-Test Validation". Ohio University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1449158180.
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Sandman, Aubrey Max. "Errors - a positive approach". Thesis, City University London, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.255353.
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Liao, James Yu-Chang. "Evaluating Multi-Modal Brain-Computer Interfaces for Controlling Arm Movements Using a Simulator of Human Reaching". Case Western Reserve University School of Graduate Studies / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=case1404138858.
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Sparnacci, Nicola. "Localizzazione e navigazione congiunta di droni". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/15758/.
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In questa tesi vengono analizzati aspetti legati alla navigazione e localizzazione congiunta di Unmanned Aerial-Vehicle (UAV) per la ricerca della formazione ottimale in modo da minimizzare l'errore di stima della posizione di un target, situato in ambienti indoor piuttosto che outdoor. Attraverso l’uso di modelli d'osservazione realistici che tengono conto anche di eventuali scenari in cui vi sia un collegamento Non-Line of Sight (NLOS) tra target e UAV, vengono derivate le grandezze fondamentali legate al Cramér-Rao Lower Bound (CRLB) come la Fisher Information Matrix (FIM) e il Position Error Bound (PEB) per l’implementazione un algoritmo (centralizzato/distribuito) di ottimizzazione vincolata per il calcolo della formazione ottimale. Sono descritte metodologie e principi utili per creare un algoritmo di navigazione degli UAV tale che permetta di districarsi in ambienti caratterizzati dalla presenza di numerosi ostacoli (cluttered environments) e di evitare la collisione tra UAV, mantenendo condizioni di sicurezza. Nell'ipotesi in cui gli UAV siano in grado di comunicare e collaborare, vengono fornite le basi di teoria dei grafi per l'instaurazione della communication multi-hop rispettando i vincoli di massima latenza intrinseci alle applicazioni real-time quali la localizzazione di un target, aspetto non considerato in letteratura. I risultati hanno mostrato come il numero di UAV che compongono la rete giochi un ruolo fondamentale in termini di velocità di convergenza fissata l'accuratezza di localizzazione desiderata anche in presenza di un approccio distribuito single hop. Infatti, il numero di UAV utilizzati incide nel miglioramento dell'accuratezza di localizzazione sia nella versione centralizzata che distribuita dell'algoritmo. Attraverso i risultati delle simulazioni sono state ottenute importanti linee guida sul dimensionamento della rete di UAV al variare delle condizioni operative.
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Moore, Linda Jennifer. "Impact of Phase Information on Radar Automatic Target Recognition". University of Dayton / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1480434103611127.
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Love, Kimberly R. "Modeling Error in Geographic Information Systems". Diss., Virginia Tech, 2007. http://hdl.handle.net/10919/29900.
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Geographic information systems (GISs) are a highly influential tool in today's society, and are used in a growing number of applications, including planning, engineering, land management,and environmental study. As the field of GISs continues to expand, it is very important to observe and account for the error that is unavoidable in computerized maps. Currently, both statistical and non-statistical models are available to do so, although there is very little implementation of these methods.
In this dissertation, I have focused on improving the methods available for analyzing error in GIS vector data. In particular, I am incorporating Bayesian methodology into the currently popular G-band error model through the inclusion of a prior distribution on point locations. This has the advantage of working well with a small number of points, and being able to synthesize information from multiple sources. I have also calculated the boundary of the confidence region explicitly, which has not been done before, and this will aid in the eventual inclusion of these methods in GIS software. Finally, I have included a statistical point deletion algorithm, designed for use in situations where map precision has surpassed map accuracy. It is very similar to the Douglas-Peucker algorithm, and can be used in a general line simplification situation, but has the advantage that it works with the error information that is already known about a map rather than adding unknown error. These contributions will make it more realistic for GIS users to implement techniques for error analysis.Ph. D.
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Came, Elizabeth Gabrielle. "False positive recognition errors in Alzheimer's disease". Thesis, University of Sussex, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326920.
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Muthukumarasamy, Arulkumaran. "IMPACT OF MICROPHONE POSITIONAL ERRORS ON SPEECH INTELLIGIBILITY". UKnowledge, 2009. http://uknowledge.uky.edu/gradschool_theses/602.
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The speech of a person speaking in a noisy environment can be enhanced through electronic beamforming using spatially distributed microphones. As this approach demands precise information about the microphone locations, its application is limited in places where microphones must be placed quickly or changed on a regular basis. Highly precise calibration or measurement process can be tedious and time consuming. In order to understand tolerable limits on the calibration process, the impact of microphone position error on the intelligibility is examined. Analytical expressions are derived by modeling the microphone position errors as a zero mean uniform distribution. Experiments and simulations were performed to show relationships between precision of the microphone location measurement and loss in intelligibility. A variety of microphone array configurations and distracting sources (other interfering speech and white noise) are considered. For speech near the threshold of intelligibility, the results show that microphone position errors with standard deviations less than 1.5cm can limit losses in intelligibility to within 10% of the maximum (perfect microphone placement) for all the microphone distributions examined. Of different array distributions experimented, the linear array tends to be more vulnerable whereas the non-uniform 3D array showed a robust performance to positional errors.
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Yankelevich, Maya. "Attitudes Toward Holistic and Mechanical Judgment in Employee Selection: Role of Error Rate and False Positive and False Negative Error". Bowling Green, Ohio : Bowling Green State University, 2010. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=bgsu1269269662.
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Muthukumarasamy, Arulkumaran. "Impact of microphone positional errors on speech intellgibility [sic]". Lexington, Ky. : [University of Kentucky Libraries], 2009. http://hdl.handle.net/10225/1061.
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Thesis (M.S.)--University of Kentucky, 2009.Title from document title page (viewed on September 18, 2009). Document formatted into pages; contains: viii, 74 p. : ill. (some col.). Includes abstract and vita. Includes bibliographical references (p. 70-73).
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Bhatia, Shaleen. "Effect of Machine Positional Errors on Geometric Tolerances in Additive Manufacturing". University of Cincinnati / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1406820498.
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Jones, Angela C. "Why do we mipsell the middle of words? Exploring the role of orthographic texture in the serial position effect". [Kent, Ohio] : Kent State University, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=kent1246891489.
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Thesis (Ph.D.)--Kent State University, 2009.Title from PDF t.p. (viewed Jan. 26, 2010). Advisor: Jocelyn R. Folk. Keywords: spelling; orthography; serial position. Includes bibliographical references (p. 53-60)
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Achanta, Raghavendra. "Detection and correction of global positional system carrier phase measurement anomalies". Ohio : Ohio University, 2004. http://www.ohiolink.edu/etd/view.cgi?ohiou1089745184.
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Graziano, Analucia. "Responsabilidade civil médica por erro de diagnóstico: critérios para a identificação do erro de diagnóstico e o resultado falso-positivo e falso-negativo". Pontifícia Universidade Católica de São Paulo, 2010. https://tede2.pucsp.br/handle/handle/8924.
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Analucia Graziano.pdf: 1612461 bytes, checksum: 2ce241b7ad11213fb8d13755502b9632 (MD5)
Previous issue date: 2010-05-27In line with the idea of rule of law and consequent incompatibility with the irresponsibility of its members, the vast expansion of the area of liability is accompanied by the growing interest of society to find solutions that make effective compensation for damage. It forms new doctrine, concerned with protecting the citizens most vulnerable and helpless. It turns out that the increasing number of complaints begins to disrupt society in general, to increase the financial cost for the professional and the patient because of the increase especially in the application of more sophisticated laboratory tests and refusal to higher-risk procedures, contributing to a consolidation of defensive medicine. The aim of this paper is to provide measures to prevent the questioning of the patient-consumer for the health services used by it. Are brought to bear upon some criteria such as time, sensitivity and specificity of diagnostic method for identification of medical errors. The consent form is also shown as a measure capable of preventing the questions, eliminating or reducing some complications related to relationship conflict or miscommunication between doctor and patient. In the context of public institutions to private, is necessary a detailed analysis of the legal systems adopted. So rich, the issue is not limited to the material aspect, so deals some specific procedural rules, which directly influence the demand indemnification, as the burden of proof. Case law and doctrine and comparative national basis and reap the practical utility of each issue discussed
Em consonância com a idéia de Estado de direito e consequente incompatibilidade com a irresponsabilidade dos seus membros, a grande expansão da área da responsabilidade civil é acompanhada do crescente interesse da sociedade em buscar soluções que tornam efetiva a reparação do dano. Forma-se nova doutrina, preocupada com a proteção aos cidadãos mais frágeis e desamparados. Ocorre que o crescente número de queixas começa perturbar a sociedade em geral, por aumentar o custo financeiro para o profissional e para o paciente em razão especialmente do aumento no pedido de exames complementares mais sofisticados e recusa em procedimentos de maior risco, contribuindo para uma consolidação de uma medicina defensiva. O objetivo do presente trabalho é fornecer medidas capazes de prevenir os questionamentos do paciente-consumidor, relativos aos serviços de saúde utilizados por ele. São trazidos à baila alguns critérios como tempo, sensibilidade e especificidade do método de diagnóstico para a identificação do erro médico. O termo de consentimento esclarecido é também apontado como medida capaz de prevenir os questionamentos, eliminando ou reduzindo algumas causas ligadas a conflitos de relacionamento ou de falha de comunicação entre médico e paciente. No âmbito das instituições públicas a privadas, se faz necessária uma minuciosa análise sobre os regimes jurídicos adotados. De tão rico, o tema não se esgota no aspecto material, por isso pincela algumas particularidades processuais, que diretamente influenciam as demandas indenizatórias, tal como o ônus da prova. O estudo de mecanismos alternativos de recomposição dos acidentes médicos ajuda, também, a compreender melhor que a simples decisão de criar novas hipóteses de responsabilidade objetiva ou adotar um sistema alternativo de solidariedade nacional deve levar em conta a sua viabilidade em termos práticos, e não apenas teórico. Da jurisprudência e doutrina nacional comparada colhe-se o fundamento e a utilidade prática de cada questão discutida
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Karlstroem, Adriana. "Estimação de posição e quantificação de erro utilizando geometria epipolar entre imagens". Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/3/3152/tde-07012008-162341/.
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A estimação de posição é o resultado direto da reconstrução de cenas, um dos ramos da visão computacional. É também uma informação importante para o controle de sistemas mecatrônicos, e em especial para os sistemas robóticos autônomos. Como uma aplicação de engenharia, o desempenho de tal sistema deve ser avaliado em termos de eficiência e eficácia, medidas traduzidas respectivamente pelo custo de processamento e pela quantificação do erro. A geometria epipolar é um campo da visão computacional que fornece formalismo matemático e técnicas de reconstrução de cenas a partir de uma par de imagens, através de pontos correspondentes entre elas. Através deste formalismo é possível determinar a incerteza dos métodos de estimação de posição, que são relativamente simples e podem atingir boa precisão. Dentre os sistemas robóticos autônomos destacam-se os ROVs - do inglês \"Remotely Operated Vehicles\" - ou veículos operados remotamente, muito utilizados em tarefas submarinas, e cuja necessidade crescente de autonomia motiva o desenvolvimento de um sensor de visão com características de baixo consumo de energia, flexibilidade e inteligência. Este sensor pode consistir de uma câmera CCD e algoritmos de reconstrução de cena baseados em geometria epipolar entre imagens. Este estudo visa fornecer um comparativo de resultados práticos da estimação de posição através da geometria epipolar entre imagens, como parte da implementação de um sensor de visão para robôs autônomos. Os conceitos teóricos abordados são: geometria projetiva, modelo de câmera, geometria epipolar, matriz fundamental, reconstrução projetiva, re-construção métrica, algoritmos de determinação da matriz fundamental, algoritmos de reconstrução métrica, incerteza da matriz fundamental e complexidade computacional. Os resultados práticos baseiam-se em simulações através de imagens geradas por computador e em montagens experimentais feitas em laboratório que simulam situações práticas. O processo de estimação de posição foi realizado através da implementação em MATLAB® 6.5 dos algoritmos apresentados na parte teórica, e os resultados comparados e analisados quanto ao erro e complexidade de execução. Dentre as principais conclusões é apresentado a melhor escolha para a implementação de sensor de visão de propósito geral - o Algoritmo de 8 Pontos Correspondentes Normalizado. São apresentadas também as condições de utilização de cada método e os cuidados necessários na interpretação dos resultados.Position estimation is the direct result of scene reconstruction, one of computer vision\'s fields. It is also an important information for the control of mechanical systems - specially the autonomous robotic systems. As an engineering application, those systems\' performance must be evaluated in terms of efficiency and effectiveness, measured by processing costs and error quantification. The epipolar geometry is a field of computer vision that supply mathematical formalism and scene reconstruction techniques that are based on the correspondences between two images. Through this formalism it is possible to stipulate the uncertainty of the position estimation methods that are relatively simple and can give good accuracy. Among the autonomous robotic systems, the ROVs - Remotely Operated Vehicles - are of special interest, mostly employed in submarine activities, and whose crescent autonomy demand motivates the development of a vision sensor of low power consumption, flexibility and intelligence. This sensor may be constructed with a CCD camera and the scene reconstruction algorithms based on epipolar geometry. This work aims to build a comparison of practical results of position estimation through epipolar geometry, as part of a vision sensor implementation for autonomous robots. The theory presented in this work comprises of: projective geometry, camera model, epipolar geometry, fundamental matrix, projective reconstruction, metric reconstruction, fundamental matrix algorithms, metric reconstruction algorithms, fundamental matrix uncertainty, and computational complexity. The practical results are based on computer generated simulations and experimental assemblies that emulate practical issues. The position estimation was carried out by MATLAB® 6.5 implementations of the algorithms analyzed in the theoretical part, and the results are compared and analyzed in respect of the error and the execution complexity. The main conclusions are that the best algorithm choice for the implementation of a general purpose vision sensor is the Normalized 8 Point Algorithm, and the usage conditions of each method, besides the special considerations that must be observed at the interpretation of the results.
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Janavičius, Egidijus. "Veleno tipo detalių plokštumų padėčių paklaidų formavimasis". Master's thesis, Lithuanian Academic Libraries Network (LABT), 2006. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2006~D_20060613_191117-62543.
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E. Janavičius „Surface position errors formation for axel type parts”. Mechanical Engineering Master‘s Theses / Leader ass.prof J.Rimkus; Siauliai University, Chair of mechanical Technology. – Siauliai, 2006 – 31p. The investigation work „Surface position errors formation for axle type parts�� consists of 28 figures, 5 references. Subject of investigation is surface position errors of the parts. Aim of the investigation is formation of surface position errors in manufacturing process. Axel type parts surface position errors formation during treatment, are presented in the work. The surface position error chains are made with a help of graphs. It is hard to estimate what will be the eventual measurement after the part is fully made, because of the errors that appear in the manufacturing process. In this work were analyzed what surface position errors appears and disappears and witch stays after manufacturing process is over. Using graphs and incidentic matrix were analyzed different surface position errors occasions.
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Barré, Brent A. "Techniques for the Visualization of Positional Geospatial Uncertainty". ScholarWorks@UNO, 2013. http://scholarworks.uno.edu/td/1720.
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Geospatial data almost always contains some amount of uncertainty due to inaccuracies in its acquisition and transformation. While the data is commonly visualized (e.g. on digital maps), there are unanswered needs for visualizing uncertainty along with it. Most research on effectively doing this addresses uncertainty in data values at geospatial positions, e.g. water depth, human population, or land-cover classification. Uncertainty in the data’s geospatial positions themselves (positional uncertainty) has not been previously focused on in this regard. In this thesis, techniques were created for visualizing positional uncertainty using World Vector Shoreline as an example dataset. The techniques consist of a shoreline buffer zone to which visual effects such as gradients, transparency, and randomized dots were applied. They are viewed interactively via Web Map Service (WMS). In clutter testing with human subjects, a transparency-gradient technique performed the best, followed by a solid-fill technique, with a dots-density-gradient technique performing worst.
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Oldenborger, Greg Arthur. "Advances in electrical resistivity tomography : modeling, electrode position errors, time-lapse monitoring of an injection/withdrawal experiment, and solution appraisal /". ProQuest subscription required:, 2006. http://proquest.umi.com/pqdweb?did=1179956331&sid=1&Fmt=2&clientId=8813&RQT=309&VName=PQD.
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Thesis (Ph. D.)--Boise State University, 2006.Includes abstract and vita. Includes bibliographical references (leaves 319-331). Also available online via the ProQuest Digital Dissertations database.
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Yang, Le. "On the Use of Multiple Emitters to Improve the TDOA Source Localization Accuracy in the Presence of Random Sensor Position Errors". Thesis, University of Missouri - Columbia, 2019. http://pqdtopen.proquest.com/#viewpdf?dispub=13877178.
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Source localization using TDOA measurements has been an important research topic mainly because of its wide applications in practical localization systems. The TDOA localization accuracy is known to be very sensitive to the sensor position errors and even a small amount of sensor position errors can cause significant performance loss. This thesis considers the use of calibration emitters to improve the source location estimate from TDOAs when the sensor positions are subject to random errors. The principle behind is that with calibration emitters, extra TDOA measurements that contain information on the true sensor positions can be obtained and if properly exploited, they are able to mitigate the effect of sensor position errors and improve the source localization accuracy. This thesis investigates, in four different localization scenarios (scenarios (i)- (iv)), the effect of calibration TDOA measurements on the source localization accuracy and how to efficiently explore them in the localization algorithm design to achieve the optimum performance.
We consider in scenario (i) the TDOA localization of a source in the presence of sensor position errors when a calibration emitter at perfectly known position is available. The CRLB of the source location estimate for this case is derived and it indicates that the utilization of calibration TDOAs can lead to great improvement in localization accuracy over the case without a calibration emitter. The performance of the differential calibration (DC) method used in GPS to mitigate the effect of satellite position uncertainty and other errors using a calibration emitter is analyzed theoretically. It is shown that in general, the DC method cannot attain the CRLB accuracy. We then develop a novel algorithm that explores the TDOA measurements from both the calibration emitter and the unknown source to estimate the source location. The newly proposed solution is in closed-form and more importantly, we prove analytically that unlike the DC method, it can reach the CRLB accuracy under two mild conditions.
Scenario (ii) is practically more realistic than scenario (i) in the sense that besides the known sensor positions, the calibration positions also have random errors and the number of calibration emitters can be greater than one. We establish the CRLB of the source location estimate for this case and quantify the performance degradation due to the calibration position errors. The sensitivity of the source location estimate to the calibration position errors is investigated and the result indicates that the source localization accuracy can be severely degraded if the calibration position errors are simply ignored. Based on this observation, a closed-form TDOA localization algorithm that takes both the calibration position errors and the sensor position errors into account is developed. The proposed solution explores all the calibration TDOAs to improve performance and it is shown analytically to reach the CRLB accuracy under mild conditions.
In scenario (iii), multiple sources at unknown locations need to be localized from TDOA measurements when the sensor positions are not known accurately. This problem includes the scenario where a single source is located with calibration emitters at completely unknown positions as a special case. The multiple sources are assumed to be disjoint and for each source, a separate set of TDOA measurements is obtained. Recognizing that in literatures, only iterative methods are available for the multiple source localization problem, we propose a closed-form solution that does not require iterations and is computationally more attractive. The new concept of hypothesized source positions is introduced in the algorithm development. Through theoretical performance analysis, we show that the proposed solution is able to attain the CRLB localization accuracy under small noise conditions. The developed algorithm can also provide improved sensor positions as a byproduct. (Abstract shortened by ProQuest.)
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Tam, Kwok-yuen Tammy. "Decisional errors in positive and negative situations the role of self-regulatory focus on moral judgment /". Click to view E-thesis via HKUTO, 2006. http://sunzi.lib.hku.hk/hkuto/record/B37091591.
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Tam, Kwok-yuen Tammy y 譚珏涴. "Decisional errors in positive and negative situations: the role of self-regulatory focus on moral judgment". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B37091591.
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Ateya, Ismail Lukandu. "Precise determination of variable density contrasts, position of contact surfaces and corrections to the possible errors for an intermediate layer in Gravity Inversion Modeling". 京都大学 (Kyoto University), 2003. http://hdl.handle.net/2433/149081.
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Henderson, Samuel Hanchett. "Monte Carlo simulations for estimating uncertainty in GIS-derived base flood elevations arising from positional errors in vector data". [Florida] : State University System of Florida, 2000. http://etd.fcla.edu/etd/uf/2000/ane5951/henderson.pdf.
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Thesis (M.S.)--University of Florida, 2000.Title from first page of PDF file. Document formatted into pages; contains vii, 127 p.; also contains graphics. Vita. Includes bibliographical references (p. 122-126).
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Marchetti, Tania. "Il dettato per i francofoni: disciplina linguistica e culturale". Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amslaurea.unibo.it/7119/.
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Negli ultimi anni, l’introduzione di tipologie alternative di dettato ha permesso di superare il dettato tradizionale, un esercizio che opprimeva gli studenti, angosciati dal timore dell’errore, segno indelebile che sanziona la mancata acquisizione di una regola ortografica, e scoraggiati a migliorare per l’inappropriata constatazione di colpevolezza, e che, in quanto tale, rischiava di essere eliminato dall'istituzione scolastica. Le nuove tipologie di dettato, contraddistinte da specifiche finalità e caratterizzate da modalità innovative, consentono, infatti, di rivalutare questo esercizio: da mero strumento di valutazione, diviene un pratico momento di apprendimento. L’errore non è più considerato come il marchio che, agli occhi dell’insegnante, contrassegna in modo permanente l’alunno. La nozione di positività che si associa all'errore riconosce lo sforzo compiuto dall'alunno nel ricorrere alle conoscenze linguistiche in suo possesso poiché, seppure il suo ragionamento non abbia portato a scegliere la forma ortografica corretta, l’attività mentale, che implicitamente ha voluto creare una connessione logica tra aspetti linguistici distinti, testimonia che lo studio della lingua non è e non richiede unicamente un ingente lavoro di memorizzazione, diversamente da ciò che si è sempre creduto. L’insegnante è dunque chiamato ad affiancare lo studente guidandolo nell'analisi dei singoli passaggi del suo ragionamento per indicare come dovrà risolvere il problema, in una futura occorrenza di quella espressione, e arrivare così ad automatizzare le conoscenze linguistiche.
Inoltre, la recente valorizzazione del dettato ha attribuito altri pregi a questo insegnamento, quali l'acquisizione essenziale del rigore, della fiducia in se stessi e della modestia.
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Valton, Vincent. "Impaired reinforcement learning and Bayesian inference in psychiatric disorders : from maladaptive decision making to psychosis in schizophrenia". Thesis, University of Edinburgh, 2015. http://hdl.handle.net/1842/21097.
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Computational modelling has been gaining an increasing amount of support from the neuroscience community as a tool to assay cognition and computational processes in the brain. Lately, scientists have started to apply computational methods from neuroscience to the study of psychiatry to gain further insight into the mechanisms leading to mental disorders. In fact, only recently has psychiatry started to move away from categorising illnesses using behavioural symptoms in an attempt for a more biologically driven diagnosis. To date, several neurobiological anomalies have been found in schizophrenia and led to a multitude of conceptual framework attempting to link the biology to the patients’ symptoms. Computational modelling can be applied to formalise these conceptual frameworks in an effort to test the validity or likelihood of each hypothesis. Recently, a novel conceptual model has been proposed to describe how positive symptoms (delusions, hallucinations and thought disorder) and cognitive symptoms (poor decision-making, i.e. “executive functioning”) might arise in schizophrenia. This framework however, has not been tested experimentally or against computational models. The focus of this thesis was to use a combination of behavioural experiments and computational models to independently assess the validity of each component that make up this framework. The first study of this thesis focused on the computational analysis of a disrupted prediction-error signalling and its implications for decision-making performances in complex tasks. Briefly, we used a reinforcement-learning model of a gambling task in rodents and disrupted the prediction-error signal known to be critical for learning. We found that this disruption can account for poor performances in decision-making due to an incorrect acquisition of the model of the world. This study illustrates how disruptions in prediction-error signalling (known to be present in schizophrenia) can lead to the acquisition of an incorrect world model which can lead to poor executive functioning or false beliefs (delusions) as seen in patients. The second study presented in this thesis addressed spatial working memory performances in chronic schizophrenia, bipolar disorder, first episode psychosis and family relatives of DISC1 translocation carriers. We build a probabilistic inference model to solve the working memory task optimally and then implemented various alterations of this model to test commonly debated hypotheses of cognitive deficiency in schizophrenia. Our goal was to find which of these hypotheses accounts best for the poor performance observed in patients. We found that while the performance at the task was significantly different for most patients groups in comparison to controls, this effect disappeared after controlling for IQ in one group. The models were nonetheless fitted to the experimental data and suggest that working memory maintenance is most likely to account for the poor performances observed in patients. We propose that the maintenance of information in working memory might have indirect implications for measures of general cognitive performance, as these rely on a correct filtering of information against distractions and cortical noise. Finally the third study presented in this thesis assessed the performance of medicated chronic schizophrenia patients in a statistical learning task of visual stimuli and measured how the acquired statistics influenced their perception. We find that patient with chronic schizophrenia appear to be unimpaired at statistical learning of visual stimuli. The acquired statistics however appear to induce less expectation-driven ‘hallucinations’ of the stimuli in the patients group than in controls. We find that this is in line with previous literature showing that patients are less susceptible to expectation-driven illusions than controls. This study highlights however the idea that perceptual processes during sensory integration diverge from this of healthy controls. In conclusion, this thesis suggests that impairments in reinforcement learning and Bayesian inference appear to be able to account for the positive and cognitive symptoms observed in schizophrenia, but that further work is required to merge these findings. Specifically, while our studies addressed individual components such as associative learning, working memory, implicit learning & perceptual inference, we cannot conclude that deficits of reinforcement learning and Bayesian inference can collectively account for symptoms in schizophrenia. We argue however that the studies presented in this thesis provided evidence that impairments of reinforcement learning and Bayesian inference are compatible with the emergence of positive and cognitive symptoms in schizophrenia.
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Waddington, Jonathan. "Human optokinetic nystagmus : a stochastic analysis". Thesis, University of Plymouth, 2012. http://hdl.handle.net/10026.1/1040.
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Optokinetic nystagmus (OKN) is a fundamental gaze-stabilising response in which eye movements attempt to compensate for the retinal slip caused by self-motion. The OKN response consists of a slow following movement made in the direction of stimulus motion interrupted by fast eye movements that are primarily made in the opposite direction. The timing and amplitude of these slow phases and quick phases are notably variable, but this variability is poorly understood. In this study I performed principal component analysis on OKN parameters in order to investigate how the eigenvectors and eigenvalues of the underlying components contribute to the correlation between OKN parameters over time. I found three categories of principal components that could explain the variance within each cycle of OKN, and only parameters from within a single cycle contributed highly to any given component. Differences found in the correlation matrices of OKN parameters appear to reflect changes in the eigenvalues of components, while eigenvectors remain predominantly similar across participants, and trials. I have developed a linear and stochastic model of OKN based on these results and demonstrated that OKN can be described as a 1st order Markov process, with three sources of noise affecting SP velocity, QP triggering, and QP amplitude. I have used this model to make some important predictions about the optokinetic reflex: the transient response of SP velocity, the existence of signal dependent noise in the system, the target position of QPs, and the threshold at which QPs are generated. Finally, I investigate whether the significant variability within OKN may represent adaptive control of explicit and implicit parameters. iii
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Dainty, Benjamin G. "Use of two-way time transfer measurements to improve geostationary satellite navigation :". Ft. Belvoir Defense Technical Information Center, 2007. http://handle.dtic.mil/100.2/ADA472457.
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Hakala, Tim. "Settling-Time Improvements in Positioning Machines Subject to Nonlinear Friction Using Adaptive Impulse Control". BYU ScholarsArchive, 2006. https://scholarsarchive.byu.edu/etd/1061.
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A new method of adaptive impulse control is developed to precisely and quickly control the position of machine components subject to friction. Friction dominates the forces affecting fine positioning dynamics. Friction can depend on payload, velocity, step size, path, initial position, temperature, and other variables. Control problems such as steady-state error and limit cycles often arise when applying conventional control techniques to the position control problem. Studies in the last few decades have shown that impulsive control can produce repeatable displacements as small as ten nanometers without limit cycles or steady-state error in machines subject to dry sliding friction. These displacements are achieved through the application of short duration, high intensity pulses. The relationship between pulse duration and displacement is seldom a simple function. The most dependable practical methods for control are self-tuning; they learn from online experience by adapting an internal control parameter until precise position control is achieved. To date, the best known adaptive pulse control methods adapt a single control parameter. While effective, the single parameter methods suffer from sub-optimal settling times and poor parameter convergence. To improve performance while maintaining the capacity for ultimate precision, a new control method referred to as Adaptive Impulse Control (AIC) has been developed. To better fit the nonlinear relationship between pulses and displacements, AIC adaptively tunes a set of parameters. Each parameter affects a different range of displacements. Online updates depend on the residual control error following each pulse, an estimate of pulse sensitivity, and a learning gain. After an update is calculated, it is distributed among the parameters that were used to calculate the most recent pulse. As the stored relationship converges to the actual relationship of the machine, pulses become more accurate and fewer pulses are needed to reach each desired destination. When fewer pulses are needed, settling time improves and efficiency increases. AIC is experimentally compared to conventional PID control and other adaptive pulse control methods on a rotary system with a position measurement resolution of 16000 encoder counts per revolution of the load wheel. The friction in the test system is nonlinear and irregular with a position dependent break-away torque that varies by a factor of more than 1.8 to 1. AIC is shown to improve settling times by as much as a factor of two when compared to other adaptive pulse control methods while maintaining precise control tolerances.
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Tuvinger, Patrik y Tomas Sobka. "Etiska Index : Vad är priset på ett gott samvete?" Thesis, Södertörns högskola, Företagsekonomi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:sh:diva-31904.
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Aim:The purpose of this study is to investigate whether an investor will have to s acrifice their expectations of return by investing in a responsible way. Theory: The thesis is based on the efficient market hypothesis through the modern portfolio theory to make it possible to test whether the investor will have to sacrifice return after taking into account of the risk. To measure the risk-adjusted return we used Sharpe ratio, the Modigliani-Modigliani (M2), Jensen's alpha, which later on is the basis for the study's results and conclusion. Method: The study is a quantitative survey with a deductive approach where the selected theories determined what data is collected. Based on these theories we construct a hypothesis that this study later intended to test. Data was collected from Bloomberg. Conclusion: The study shows that several ethical indexes have a higher return while at the same time showing a higher risk-adjusted return. This higher risk-adjusted return is not statistically significant except for a few of the measured markets. The study also shows that the ethical indexes generally have a lower 𝛽, which can be interpreted as a lower systematic risk. Meanwhile the tracking error / active risk is higher and the screened indexes therefore should not be compared with say, index funds. When taken into account the longer period active risk levels match actively managed funds. As in previous studies, this study did not show any significant difference in risk-adjusted returns but a higher risk.