Dissertations / Theses on the topic 'Sensor measurements'
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Yeo, Chin Liong. "Command Wire Sensor Measurements." Thesis, Monterey, California. Naval Postgraduate School, 2012. http://hdl.handle.net/10945/17483.
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Approved for public release; distribution is unlimitedAfter the recent success in jamming wireless improvised explosive devices (IEDs), the threat nowadays has shifted towards the use of buried command wires. A capability to immediately detect the presence of a command wire would be of great value to the troops on the ground. The major challenge of a command wire sensor is to detect the wire in clutter and achieve a high probability of detection without large number of false alarms. The objective of this thesis is to investigate the wire scattering behavior and clutter characteristics through measurements performed in the NPS anechoic chamber. The research has successfully resolved the various multipath components within the anechoic chamber. The transmit-receive coupling between the antennas was reduced through the appropriate use of absorbers. Various wire scattering and clutter characteristics were established through the measurement results. In addition, the measurement results have also demonstrated close-in clutter rejection by utilizing time gating. Recommendations for future work were proposed to gather more data to support the ongoing NPS research on the Command Wire Sensor design.
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Curatu, Costin. "Wavefront Sensor for Eye Aberrations Measurements." Doctoral diss., University of Central Florida, 2009. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2274.
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Ocular wavefront sensing is vital to improving our understanding of the human eye and to developing advanced vision correction methods, such as adaptive optics, customized contact lenses, and customized laser refractive surgery. It is also a necessary technique for high-resolution imaging of the retina. The most commonly used wavefront sensing method is based on the Shack-Hartmann wavefront sensor. Since Junzhong Liang's first application of Shack-Hartmann wavefront sensing for the human eye in 1994, the method has quickly gained acceptance and popularity in the ophthalmic industry. Several commercial Shack-Hartmann eye aberrometers are currently available. While the existing aberrometers offer reasonable measurement accuracy and reproducibility, they do have a limited dynamic range. Although rare, highly aberrated eyes do exists (corneal transplant, keratoconus, post-lasik) that cannot be measured with the existing devices. Clinicians as well as optical engineers agree that there is room for improvement in the performance of these devices "Although the optical aberrations of normal eyes have been studied by the Shack-Hartmann technique, little is known about the optical imperfections of abnormal eyes. Furthermore, it is not obvious that current Shack-Hartmann aberrometers are robust enough to successfully measure clinically abnormal eyes of poor optical quality" Larry Thibos, School of Optometry, Indiana University. The ultimate goal for ophthalmic aberrometers and the main objective of this work is to increase the dynamic range of the wavefront sensor without sacrificing its sensitivity or accuracy. In this dissertation, we attempt to review and integrate knowledge and techniques from previous studies as well as to propose our own analytical approach to optimizing the optical design of the sensor in order to achieve the desired dynamic range. We present the underlying theory that governs the relationship between the performance metrics of the sensor: dynamic range, sensitivity, spatial resolution, and accuracy. We study the design constraints and trade-offs and present our system optimization method in detail. To validate the conceptual approach, a complex simulation model was developed. The comprehensive model was able to predict the performance of the sensor as a function of system design parameters, for a wide variety of ocular wavefronts. This simulation model did confirm the results obtained with our analytical approach. The simulator itself can now be used as a standalone tool for other Shack-Hartmann sensor designs. Finally, we were able to validate our theoretical work by designing and building an experimental prototype. We present some of the more practical design aspects, such as illumination choices and tolerance analysis methods. The prototype validated the conceptual approach used in the design and was able to demonstrate a vast increase in dynamic range while maintaining accurate and repeatable measurements.Ph.D.
Optics and Photonics
Optics and Photonics
Optics PhD
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Ragnarsson, David. "Sensor Integration for High Temperature Measurements." Thesis, Luleå tekniska universitet, EISLAB, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-64544.
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In today's mining industry, most of the sensor measurements in high temperature environments are expensive and the sensors are not well integrated with the materials treated in the hot temperatures. The conditions can vary much between the sensors location and where the materials are located. It is crucial to have high performance measurements to reach a more optimized control over the oven. A more optimized process gives a better combustion which decreases the fuel consumption and is more energy efficient. To increase the performance of these measurements, it is necessary to have wireless sensor systems, which can be well integrated with the materials and have a low cost. This so there is no need to use same system several times and it shouldn't matter if it gets destroyed in the oven. In this thesis, the focus lies on building the electronics and software for controlling a wide band oxygen sensor. The electronics are built by components with an upper temperature limit of 125 ◦C or above. The sensor itself is supposed to be heated up by an internal heating element. However, in these experiments, it is heated up by the surroundings in the oven. A major challenge in the work was the design of the control loop to keep the sensor in a correct and stable operating point. When initial oxygen measurements were compared with reference measurement done simultaneously in the oven, it didn't match well. These differences were shown to be caused by different locations of the sensor and the reference measurements. Further measurements in a live industrial setting confirmed the functionality of the system.
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Deleskog, Viktor. "Sensor Localization Calibration of Ground Sensor Networks with Acoustic Range Measurements." Thesis, Linköpings universitet, Reglerteknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-81655.
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Advances in the development of simple and cheap sensors give new possibilities with large sensor network deployments in monitoring and surveillance applications. Commonly, the sensor positions are not known, specifically, when sensors are randomly spread in a big area. Low cost sensors are constructed with as few components as possible to keep price and energy consumption down. This implies that self-positioning and communication capabilities are low. So the question: “How do you localize such sensors with good precision with a feasible approach?” is central. When no information is available a stable and robust localization algorithm is needed. In this thesis an acoustic sensor network is considered. With a movable acoustic source a well-defined and audible signal is transmitted at different spots. The sensors measure the time of arrival which corresponds to distance. A two-step sensor localization approach is applied that utilizes the estimated distances. A novel approach in the first step is presented to incorporate more measurements and gain more position information. Localization and ranging performance is evaluated with simulations and data collected at field trials. The results show that the novel approach attains higher accuracy and robustness.
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Velander, Jacob. "Microwave Sensor Measurements And Human Tissue Characterization." Thesis, Uppsala universitet, Fasta tillståndets elektronik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-309560.
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Padmanabhan, Aravind. "Silicon micromachined sensors and sensor arrays for shear-stress measurements in aerodynamic flows." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/10257.
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Schmid, Wolf. "Consumption measurements on SnO 2 sensors in low and normal oxygen concentration." [S.l. : s.n.], 2004. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB11126585.
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Konstatinos, Sasloglou. "Channel measurements and modelling for sensor network applications." Thesis, University of Strathclyde, 2010. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=12833.
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Kok, Manon. "Probabilistic modeling for sensor fusion with inertial measurements." Doctoral thesis, Linköpings universitet, Reglerteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-133083.
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In recent years, inertial sensors have undergone major developments. The quality of their measurements has improved while their cost has decreased, leading to an increase in availability. They can be found in stand-alone sensor units, so-called inertial measurement units, but are nowadays also present in for instance any modern smartphone, in Wii controllers and in virtual reality headsets. The term inertial sensor refers to the combination of accelerometers and gyroscopes. These measure the external specific force and the angular velocity, respectively. Integration of their measurements provides information about the sensor's position and orientation. However, the position and orientation estimates obtained by simple integration suffer from drift and are therefore only accurate on a short time scale. In order to improve these estimates, we combine the inertial sensors with additional sensors and models. To combine these different sources of information, also called sensor fusion, we make use of probabilistic models to take the uncertainty of the different sources of information into account. The first contribution of this thesis is a tutorial paper that describes the signal processing foundations underlying position and orientation estimation using inertial sensors. In a second contribution, we use data from multiple inertial sensors placed on the human body to estimate the body's pose. A biomechanical model encodes the knowledge about how the different body segments are connected to each other. We also show how the structure inherent to this problem can be exploited. This opens up for processing long data sets and for solving the problem in a distributed manner. Inertial sensors can also be combined with time of arrival measurements from an ultrawideband (UWB) system. We focus both on calibration of the UWB setup and on sensor fusion of the inertial and UWB measurements. The UWB measurements are modeled by a tailored heavy-tailed asymmetric distribution. This distribution naturally handles the possibility of measurement delays due to multipath and non-line-of-sight conditions while not allowing for the possibility of measurements arriving early, i.e. traveling faster than the speed of light. Finally, inertial sensors can be combined with magnetometers. We derive an algorithm that can calibrate a magnetometer for the presence of metallic objects attached to the sensor. Furthermore, the presence of metallic objects in the environment can be exploited by using them as a source of position information. We present a method to build maps of the indoor magnetic field and experimentally show that if a map of the magnetic field is available, accurate position estimates can be obtained by combining inertial and magnetometer measurements.
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Ackerman, James S. "Error analysis of sensor measurements in a small UAV." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2005. http://library.nps.navy.mil/uhtbin/hyperion/05Sep%5FAckerman.pdf.
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Thesis (M.S. in Engineering Science (Mechanical Engineering))--Naval Postgraduate School, September 2005.Thesis Advisor(s): Isaac I. Kaminer. Includes bibliographical references (p. 45). Also available online.
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Jing, Wenyang. "A Microfluidic Volume Sensor for Single-Cell Growth Measurements." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/34770.
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The multidisciplinary field of microfluidics has shown great promise for research at the interface of biology, chemistry, engineering, and physics. Laminar flow, versatile fabrication, and small length scales have made microfluidics especially well-suited for single-cell characterization. In particular, the evaluation of single-cell growth rates is of fundamental interest for studying the cell cycle and the effects of environmental factors, such as drugs, on cellular growth. This work presents aspects in the development of a microfluidic cell impedance sensor for measuring the volumetric growth rate of single cells and covers its application in the investigation of a new discovery relating to multidrug resistance in S. cerevisiae. While there are many avenues for the utilization and interpretation of growth rates, this application focused on the quantitative assessment of biological fitness—an important parameter in population genetics and mathematical biology. Through a combination of growth measurements and optics, this work concludes a novel case of bet-hedging in yeast, as well as the first ever case of bet-hedging in eukaryotic multidrug resistance.
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Moore, David Christopher 1981. "Robust distribution sensor network localization with noisy range measurements." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/30168.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.Includes bibliographical references (p. 73-74).
This thesis describes a distributed, linear-time algorithm for localizing sensor network nodes in the presence of range measurement noise and demonstrates the algorithm on a physical network. We introduce the probabilistic notion of robust quadrilaterals as a way to avoid flip ambiguities that otherwise corrupt localization computations. We formulate the localization problem as a two-dimensional graph realization problem: given a planar graph with approximately known edge lengths, recover the Euclidean position of each vertex up to a global rotation and translation. This formulation is applicable to the localization of sensor networks in which each node can estimate the distance to each of its neighbors, but no absolute position reference such as GPS or fixed anchor nodes is available. We implemented the algorithm on a physical sensor network and empirically assessed its accuracy and performance. Also, in simulation, we demonstrate that the algorithm scales to large networks and handles real-world deployment geometries. Finally, we show how the algorithm supports localization of mobile nodes.
by David Christopher Moore.
S.M.
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Li, Zeyuan. "Target localization using RSS measurements in wireless sensor networks." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/31356.
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The subject of this thesis is the development of localization algorithms for target localization in wireless sensor networks using received signal strength (RSS) measurements or Quantized RSS (QRSS) measurements. In chapter 3 of the thesis, target localization using RSS measurements is investigated. Many existing works on RSS localization assumes that the shadowing components are uncorrelated. However, here, shadowing is assumed to be spatially correlated. It can be shown that localization accuracy can be improved with the consideration of correlation between pairs of RSS measurements. By linearizing the corresponding Maximum Likelihood (ML) objective function, a weighted least squares (WLS) algorithm is formulated to obtain the target location. An iterative technique based on Newtons method is utilized to give a solution. Numerical simulations show that the proposed algorithms achieves better performance than existing algorithms with reasonable complexity. In chapter 4, target localization with an unknown path loss model parameter is investigated. Most published work estimates location and these parameters jointly using iterative methods with a good initialization of path loss exponent (PLE). To avoid finding an initialization, a global optimization algorithm, particle swarm optimization (PSO) is employed to optimize the ML objective function. By combining PSO with a consensus algorithm, the centralized estimation problem is extended to a distributed version so that can be implemented in distributed WSN. Although suboptimal, the distributed approach is very suitable for implementation in real sensor networks, as it is scalable, robust against changing of network topology and requires only local communication. Numerical simulations show that the accuracy of centralized PSO can attain the Cramer Rao Lower Bound (CRLB). Also, as expected, there is some degradation in performance of the distributed PSO with respect to the centralized PSO. In chapter 5, a distributed gradient algorithm for RSS based target localization using only quantized data is proposed. The ML of the Quantized RSS is derived and PSO is used to provide an initial estimate for the gradient algorithm. A practical quantization threshold designer is presented for RSS data. To derive a distributed algorithm using only the quantized signal, the local estimate at each node is also quantized. The RSS measurements and the local estimate at each sensor node are quantized in different ways. By using a quantization elimination scheme, a quantized distributed gradient method is proposed. In the distributed algorithm, the quantization noise in the local estimate is gradually eliminated with each iteration. Simulations show that the performance of the centralized algorithm can reach the CRLB. The proposed distributed algorithm using a small number of bits can achieve the performance of the distributed gradient algorithm using unquantized data.
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Järvinen, T. (Topias). "Validation of cyber-physical systems in gas sensor measurements." Master's thesis, University of Oulu, 2016. http://urn.fi/URN:NBN:fi:oulu-201603171329.
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In this thesis a cyber-physical system for gas sensor measurements was constructed. In the design implementation, two different approaches were taken; we created a device for calibrating and testing the sensors and another device acting as independent battery-powered measurement platform. Both systems are compatible with a separate circuit (sensor)board coupled within the sensors. This board supports both commercial Taguchi-type and custom sensors. In addition, the circuit (sensor)board includes optional heater circuits for gas sensors as well as a separate temperature and humidity sensor. The devices utilize Arduino-based microcontrollers and a Raspberry Pi single board computer which were programmed to execute the specified functions. According to the nature of cyber-physical system, devices are able to save the data to a memory card and upload it to internet using the selected cloud service. In order to validate the specified functionality of the devices, gas sensors were fabricated by inkjet-printing platinum decorated tungsten(VI) oxide nanoparticles onto a substrate. The substrate was then wire bonded to a dual in-line package-compatible chip carrier. Test measurements and sensor calibration were carried out in a custom test chamber in hydrogen gas environmentTässä työssä valmistettiin kyberfyysinen järjestelmä kaasusensorimittauksille. Suunniteltu toteutus sisältää kaksi lähestymistapaa; yksi laite sensoreiden kalibrointiin ja testaukseen sekä toinen akkukäyttöinen, itsenäisenä mittausalustana toimiva laite. Sensorit sijoitettiin erilliselle piirilevylle joka oli yhteensopiva molempien järjestelmien kanssa. Tämä sensorikortti tukee sekä kaupallisia Taguchi-tyyppisiä sensoreita että itsetehtyjä sensoreita. Se sisältää myös valinnaiset lämmityspiirit kaasusensoreille sekä erillisen lämpötila- ja kosteussensorin. Laitteet hyödyntävät Arduino-pohjaisia mikrokontrollereita sekä Raspberry Pi -pienoistietokonetta jotka ohjelmointiin toteuttamaan vaaditut toiminnot. Noudattaen kyberfyysisien järjestelmien luonnetta laitteet tallentavat mittausdatan muistikortille ja lähettävät datan valittuun pilvipalveluun. Toiminnallisuuden todentamiseksi valmistettiin kaasusensoreita platinalla päällystetyistä wolframitrioksidi -nanopartikkeleista. Partikkelit tulostettiin substraatille mustesuihkutulostimella ja lankabondattiin dual in-line package-yhteensopivaan välikappaleeseen. Mittaukset tehtiin erikoisvalmisteisessa testikammiossa vetykaasussa
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Keef, James Lewis. "Hyper-Spectral Sensor Calibration Extrapolated from Multi-Spectral Measurements." Diss., The University of Arizona, 2008. http://hdl.handle.net/10150/193627.
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Hyper-spectral (HS) sensors are the instruments of choice for remote sensing applications involving environmental monitoring, littoral survey, and military assessment. Accurate band-to-band sensor radiometric calibration is critical for successful data mining of such HS spectral sets. Current calibration is often performed with methods not necessarily developed for HS applications. This work describes two advances which facilitate laboratory source calibrations. First, an analytical solution to the attenuation of flux within an integrating sphere, the best laboratory source of non-directional radiance for numerous radiometric applications, is given. Relative component attenuations due to integrating sphere coating, exit port escape, and atmospheric absorption are derived employing a geometrical PDF of summed probabilities. Equations providing the attenuation ratios and mean number of reflections for the three outcomes are obtained, yielding the three partial mean pathlengths and variances of all quantities. This work then describes an approach allowing accurate radiometric calibration of HS sensor bands using well-characterized and stable multi-spectral transfer radiometers. The resulting high-quality calibration enables the best representation of the truth spectral signature of the imaged scene. In order to obtain the best calibration with the least instrument complexity and expense, it is critical that the radiometer samples the source with the fewest samples at those optimal wavelengths which predict that source with the highest accuracy. The optimal source-specific bands are determined efficiently by application of the Direct Search methodology described here. Using the minimal selection of multi-spectral radiometer measurements obtained from the optimized transfer radiometer bands, one can obtain a complete and accurate calibration set for the continuum of calibration coefficients required for a robust HS application. Degradation of the prediction is documented for several typical error sources encountered with calibration, thereby defining limitations on the usefulness of the optimization approach.
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Etebari, Ali. "Wall shear measurements in arterial flows." Diss., Virginia Tech, 2006. http://hdl.handle.net/10919/27326.
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Cardiovascular disease is responsible for the majority of morbidity and mortality in the United States. Physiologically healthy flow rarely displays turbulent behavior, thereby maintaining normal shear levels. The presence of vortical flow structures, however, alters the hemodynamical characteristics within the system, which has significant effect upon shear stress (SS) and wall shear stress (WSS) levels, as well as particle residence times. The relationship between these hemodynamic parameters and vascular injury response is of great relevance to understanding the cardiovascular disease process.
In this work, new methods and algorithms are developed and presented for resolving, both globally and locally, the spatial and temporal variations of shear stress (SS) and WSS for in vitro models of the human cardiovascular system. Advancements in global measurements are based on improving the accuracy of SS and WSS estimation from time-resolved Digital Particle Image Velocimetry (DPIV) velocity measurements. A new velocity derivative method, the fourth-order noise-optimized compact-Richardson implicit scheme, has been developed, overcoming the obstacle of minimizing both the bias and random error in temporal/spatial derivative estimations. The resulting error is on the same order as the velocity measurement error for global measurements which results in an order of magnitude accuracy improvement. The method has been extended to WSS measurements, and combined with a new method of mirroring/reflecting a flow field over its boundary in order to achieve higher-order estimation. For moving boundaries an edge detection cross-correlation algorithm has been developed and characterized, yielding sub-pixel accuracy in measuring dynamic wall position prior to estimating WSS. An original microelectromechanical system (MEMS) WSS sensor capable of delivering high sensitivity, frequency response and accurate WSS measurements has been developed and characterized in this work.Ph. D.
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McCulloch, Scott. "Fibre optic microsensors for intracellular chemical measurements." Thesis, University of Strathclyde, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248617.
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Keramitsoglou, Iphigenia. "On measurements of upper tropospheric humidity." Thesis, Imperial College London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313660.
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Guo, Kai Chen. "Passive localization in quasi-synchronous sensor networks with sensor uncertainty and Non-Line of-Sight measurements." Thesis, University of Macau, 2017. http://umaclib3.umac.mo/record=b3691130.
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Hegen, Peter. "Continuous Measurements of Core Body Temperature using Body Sensor Networks." Thesis, Linköpings universitet, Institutionen för datavetenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-85465.
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Long-term body temperature measurements for research and diagnosis are currently done in hospitals or specialized research labs. This method has several drawbacks: the use of wired ob- trusive sensors (e.g., rectal probes to measure the core body temperature) may be uncomfortable for patients. Furthermore, situations recorded in laboratory settings do not reflect reality as patients are not subject to their normal living environment. Furthermore, it is labor-intensive to regularly check upon patients and care for their well-being. Using small wireless sensor nodes in a body sensor network to measure body functions, one can mostly offset the limitations listed above. For this work, we have developed a wireless sensor node that uses an infrared thermopile as a sensor to unobtrusively measure the core temperature at the tympanic membrane. Due to their construction, these sensors are heavily dependent on the ambient temperature in the surroundings of the sensor packaging. While this does not affect their use in single-shot measurements (e.g., using an ear thermometer), it poses a challenge for continuous measurements, as common living environments do not have constant ambient air temperatures and people frequently commute between different places. These conditions may offset measurements significantly, an important problem for medical applications that require high accuracy. In this work, we employ infrared thermopiles in a body sensor network and characterize their behaviour in various situations, especially in the presence of varying environmental conditions. Based on our observations, we describe methods for post-processing measurements in order to compensate environmental changes and hence get results reflecting reality more closely. Our evaluation shows that these methods can offset the infrared thermopile’s weakness but need further work to achieve the degree of accuracy that is needed for medical applications.
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Seidel, Matthew Paul. "A SENSOR FOR IN SITU SPECTROPHOTOMETRIC MEASUREMENTS OF SEAWATER pH." The University of Montana, 2007. http://etd.lib.umt.edu/theses/available/etd-03282007-162542/.
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The design of small autonomous sensors for measuring parameters in the ocean has been an important area of research. The development of a seawater pH sensor which is highly accurate and precise has unlimited potential for oceanographic studies. A seawater instrument for pH measurements was built based upon the design of the SAMI-pH for freshwater. The performance of the freshwater design in a seawater setting was unknown. During a cruise in the Labrador Sea the first design of the SAMI-pH for seawater based upon the previous instrument design was tested. The results showed promise but indicated that improvements needed to be made to the stability and reproducibility of the instrument to achieve the desired accuracy of 0.002 pH units and precision of 0.001 pH units. Since a full scale optimization of the SAMI-pH had never been undertaken, multiple parameters were tested. The old Delrin flow cell was replaced with a custom made Z-cell, which improved the absorbance precision. A commercially available static mixer was used to produce reproducible mixing of the indicator and sample. The indicator concentration and indicator pH were optimized to maximize the linearity of the [mCP]T vs. pH plots and to reduce the flushing volume which increased the deployment length. A new method of calculating molar absorptivity ratios was evaluated and the SAMI-pH accuracy was found to be 0.0017 when compared to the Cary UV/Vis. The precision showed excellent improvement from 0.004 to 0.0007 with the new SAMI-pH design. In situ testing of two SAMI-pH instruments was completed at Scripps Institution of Oceanography. Agreement of -0.0047 pH units between the two SAMI-pH instruments during a 22-day period with 883 measurements illustrates the highly accurate and stable performance of the SAMI-pH. An alternative method for pH determination based on theoretical calculations was also tested. The average offset between pH values calculated from the linear extrapolation technique and the theoretical model was -0.0008 pH units illustrating that the linear extrapolation is a rigorous method for determining the pH of the solution.
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Alzaghal, Mohamad H. "Wireless sensor network channel propagation measurements and comparison with simulation." Thesis, Monterey, Calif. : Naval Postgraduate School, 2006. http://bosun.nps.edu/uhtbin/hyperion-image.exe/06Jun%5FAlzaghal.pdf.
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Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, June 2006.Thesis Advisor(s): Su, Weilian. "June 2006." Description based on title screen as viewed on March 12, 2008. Includes bibliographical references (p. 63-65). Also available in print.
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Shusteff, Maxim 1979. "A microfabricated hollow cantilever sensor for sub-nanoliter thermal measurements." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/87903.
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Fox, Emily Beth. "Detection and localization of aerosol releases from sparse sensor measurements." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/30371.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 111-114).
In this thesis we focus on addressing two aspects pertinent to biological release detection. The first is that of detecting and localizing an aerosolized particle release using a sparse array of sensors. The problem is challenging for several reasons. It is often the case that sensors are costly and consequently only a sparse deployment is possible. Additionally, while dynamic models can be formulated in many environmental conditions, the underlying model parameters may not be precisely known. The combination of these two issues impacts the effectiveness of inference approaches. We restrict ourselves to propagation models consisting of diffusion plus transport according to a Gaussian puff model. We derive optimal inference algorithms utilizing sparse sensor measurements, provided the model parameterization is known precisely. The primary assumptions are that the mean wind field is deterministically known and that the Gaussian puff model is valid. Under these assumptions, we characterize the change in performance of detection, time-to-detection and localization as a function of the number of sensors. We then examine some performance impacts when the underlying dynamical model deviates from the assumed model. In addition to detecting an abrupt change in particles in an environment, it is also important to be able to classify the releases as not all contaminants are of interest. For this reason, the second aspect of addressed is feature extraction, a stage where sensor measurements are reduced to a set of pertinent features that can be used as an input to the classifier.
(cont.) Shift invariance of the feature set is critical and thus the Dual Tree Complex Wavelet Transform (DT CWT) is proposed as the wavelet feature domain.
by Emily Beth Fox.
M.Eng.
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Kozlosky, E. S., D. H. Desrosiers, M. Glendening, and L. Morelli. "Auto Ranging Optical Sensor Suitable for High-Energy Laser Measurements." International Foundation for Telemetering, 1988. http://hdl.handle.net/10150/615027.
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International Telemetering Conference Proceedings / October 17-20, 1988 / Riviera Hotel, Las Vegas, NevadaThis paper presents the design and performance of an auto ranging optical sensor (AROS) built for space applications and capable of measuring pulsed optical energy over a wide range of pulse widths, energy levels and wavelengths. The AROS measures energy densities over seven orders of magnitude to a maximum of 0.2 J/cm² and can withstand 1 J/cm² without damage. In addition to its intended use as a laser sensor in multi-sensor arrays on target satellites, the AROS is well suited for laboratory use in the measurement and profiling of high-power laser beams.
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Lam, Yu-Zhi. "Biomedical sensor for transcutaneous oxygen measurements using thick film technology." Thesis, University of Southampton, 2003. https://eprints.soton.ac.uk/47492/.
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The measurement of the partial pressure of oxygen in arterial blood is essential for the analysis of a patient's respiratory condition. There are several commercially available methods and systems to measure this parameter transcutaneously. However, they tend to be cumbersome and costly. To overcome the disadvantages presented, a new type of sensor for transcutaneous blood gas measurement was investigated, employing thick film technology, which is an excellent technique to produce sensors in bulk, as it is cost effective and easy for reproducible fabrication. This thesis describes the application of thick film technology to the investigation and production of these sensors, which are small in size and readily disposable. Such advantages are greatly welcomed from the medical point of view. The devices under investigation were based on amperometry. Gold electrodes were printed on an alumina substrate and covered with a layer of electrolyte gel and then finally, with a membrane. An external silver/silver chloride reference electrode was also employed in this electrochemical cell set-up. The project also involved several electronic circuits to support the transcutaneous oxygen measurement. The main studies were concentrated on the materials employed as the electrolyte and membrane. Investigations were carried out to evaluate the performance of these devices in atmospheric and hydrated environment as well as under the influences of different temperatures. Detailed discussions of the results were presented and future work for the project is identified. The novel contributions towards this research work were categorized into two major modules. Firstly, in the heating module, a single element taking both the roles of a heating element and a feedback temperature sensor was employed for the wheatstone bridge circuit configuration to regulate the transcutaneous temperature. In addition, the oxygen sensing module included studies on the effectiveness of using Nafion polyelectrolytes to achieve amperometric measurements for transcutaneous oxygen monitoring. From the experimental results, the most promising choice for the thick film transcutaneous oxygen sensor was the prototype with Nafion as the electrolyte and PTFE as the membrane. The disposable prototype produced results achieving low manufacturing cost of approximately £1 and was able to make continuous measurement of up to 46 hours. It proved to be compact, non-biohazardous and portable with a good degree of user-friendliness. It also provided accurate and reproducible measurements of not more than 3% error. Thorough intensive research activities were carried out to overcome all existing problems in order to achieve the objectives of the research project. With more than 70% of the specifications being met, the positive results had presented a successful design for the fundamental version of the disposable transcutaneous oxygen sensor employing thick film fabrication processes.
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Zhang, Zheng. "RESISTIVE PULSE SENSORS FOR POLLEN PARTICLE MEASUREMENTS." University of Akron / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=akron1145070142.
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Chen, Hao. "End-to-end Delay Analysis and Measurements in Wireless Sensor Networks." Thesis, Mittuniversitetet, Institutionen för informationsteknologi och medier, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-16985.
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Wireless sensor networks have arrived because of further developments of themodern Internet, and this has been considered to be one of the most importanttechnologies of the 21st century. Currently, the wireless sensor network has becomean important technology in a variety of areas and is widely used in thefield of national defense, national security, environmental monitoring, trafficmanagement, anti-terrorism, anti-disaster, and so on. The majority of these applicationsrequire real-time communication as the WSNs are required to sendthe data to the data center within a specified time. In order to meet the real-timedemand for wireless sensor networks, this work mainly focuses on the analysisand measurement of the end-to-end delay, including both single-hop and multihopdelays. This thesis first analyzes the composition of the end-to-end delayand then describes the end-to-end delay measurement algorithms and methods.The measurement is implemented in TelosB motes within TinyOS. Finally thereport will show the evaluation of the end-to-end delay in wireless sensor networks.
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White, Julia. "OPTIC FIBER SENSOR FOR STRAIN MEASUREMENTS IN HIGH TEMPERATURE SENSING APPLICATIONS." International Foundation for Telemetering, 2017. http://hdl.handle.net/10150/626969.
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Optic fiber sensors are employed in a variety of applications for the remote measurement of various parameters such as strain, pressure, or temperature. These sensors offer an array of benefits as well including light weight, compactness, and high resolution. In particular, Fabry-Perot interferometers (FPIs) maintain these benefits and can also be made to withstand extremely high temperatures. This advantage of the FPI allows it to be used in harsh environments where many other tools for parameter measurement could not survive. An FPI strain sensor is constructed and tested which has the capabilities to be used at high temperatures of over 1000°C for applications in gas turbine engine testing. This paper discusses the need for high temperature strain sensors in engine testing and this sensor’s capabilities in this application.
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Brunt, T. A. "Stress measurements at the solid-liquid interface using a micromechanical sensor." Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.597031.
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This dissertation describes the development of atomic force microscope cantilevers as surface stress sensors for monitoring surface processes at the solid-liquid interface. Micromechanical bending-beams are highly sensitive stress sensors; stress changes as small as 10-4Nm-1 can be detected using this type of bending-beam, whereas typical stress changes associated with monolayer processes are 0.1-1Nm-1. As well as offering high sensitivity, micromechanical cantilevers have a fast response time (0.5ms in liquids) which means they are ideally suited for fast stress measurements. Textured (111) surfaces were prepared by thermal evaporation of Au onto one face of the Si3N4 cantilevers. These cantilevers were used as electrodes to monitor the stress changes associated with electrochemical processes, in conjunction with electrochemical measurements such as cyclic voltammetry and chronoamperometry. The potential-dependent adsorption of C1- and I- anions gave rise to stress changes of 0.5-1Nm-1, and in both cases, adsorption of the anion was associated with an increase in compressive surface stress. Underpotential deposition (UPD) of Pb and Ag on Au(111) has been studied in detail. For Pb UPD on Au(111) a compressive stress change of 1Nm-1 was measured on deposition of one monolayer. More detailed features in the surface stress-potential curve have been directly related to features in the cyclic voltammogram and known structural processes such as the potential-dependent compression of the Pb monolayer. The measured stress changes for Ag UPD on Au(111) were also 1Nm-1 and did not display a strong dependence on the nature of the anion present in the electrolyte.
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Vulli, Srikar. "Engine cylinder pressure reconstruction using neural networks and knock sensor measurements." Thesis, University of Sussex, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.436232.
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Don, Michael, and Tom Harkins. "Achieving High Resolution Measurements Within Limited Bandwidth Via Sensor Data Compression." International Foundation for Telemetering, 2012. http://hdl.handle.net/10150/581447.
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ITC/USA 2012 Conference Proceedings / The Forty-Eighth Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2012 / Town and Country Resort & Convention Center, San Diego, CaliforniaThe U.S. Army Research Laboratory (ARL) is developing an onboard instrument and telemetry system to obtain measurements of the 30mm MK310 projectile's in-flight dynamics. The small size, high launch acceleration, and extremely high rates of this projectile create many design challenges. Particularly challenging is the high spin rate which can reach 1400 Hz at launch. The bandwidth required to continuously transmit solar data using the current method for such a rate would leave no room for data from other sensors. To solve this problem, a data compression scheme is implemented that retains the resolution of the solar sensor data while providing room in the telemetry frame for other measurements.
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Ali, Md Afsar. "In-process quality monitoring of laser welds using multi-sensor measurements /." The Ohio State University, 1999. http://rave.ohiolink.edu/etdc/view?acc_num=osu1488192447428925.
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Holmberg, Mei-Li, and Linnea Johansson. "Wavefront Sensor with Astigmatism Correction for Measurements on the Human Eye." Thesis, KTH, Skolan för teknikvetenskap (SCI), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-210856.
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When conducting experiments on the human eye it is sometimes required to correct some form of astigmatism. A fexible and cost effective way to achieve this is using two identical cross-cylinder lenses, as described in the article ‘Adaptive Astigmatism-Correcting Device for Eyepieces' by Arines and Acosta. When rotating these lenses the strength and angle can be adjusted to correct for different types of astigmatism.The measurements were made on two identical SR = +2 D, CR = - 4 D lenseson rotating mounts. A Shack-Hartmann wavefront sensor detected the change in a beam of collimated light directed through the lenses. Two types of measurements were conducted, to record the results of just the relative angle between the lenses and to find the aberrations the lenses themselves introduce to the system in combination with rotation. The two-lens-system we created adhered well to the theory and the results obtained by Arines and Acosta, although we obtained a slight variation in our values. The minimum cylindrical strength was close to -9 D and the aberrations were very small (< 0:01 μm). The reasons for these systematic errors are discussed but for the purposes of aiding in visual optics research this solution is well suited for its ease of use, and cost effectiveness.
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Ma, Aihui. "Synthesis and characterization of miniaturized fluorescence sensors for aqueous and cellular measurements." ScholarWorks@UNO, 2005. http://louisdl.louislibraries.org/u?/NOD,240.
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Thesis (Ph. D.)--University of New Orleans, 2005.Title from electronic submission form. "A thesis ... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Chemistry."--Dissertation t.p. Vita. Includes bibliographical references.
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Larsson, Olof. "Visual-inertial tracking using Optical Flow measurements." Thesis, Linköping University, Automatic Control, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-59970.
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Visual-inertial tracking is a well known technique to track a combination of a camera and an inertial measurement unit (IMU). An issue with the straight-forward approach is the need of known 3D points. To by-pass this, 2D information can be used without recovering depth to estimate the position and orientation (pose) of the camera. This Master's thesis investigates the feasibility of using Optical Flow (OF) measurements and indicates the benifits using this approach.
The 2D information is added using OF measurements. OF describes the visual flow of interest points in the image plane. Without the necessity to estimate depth of these points, the computational complexity is reduced. With the increased 2D information, the 3D information required for the pose estimate decreases.
The usage of 2D points for the pose estimation has been verified with experimental data gathered by a real camera/IMU-system. Several data sequences containing different trajectories are used to estimate the pose. It is shown that OF measurements can be used to improve visual-inertial tracking with reduced need of 3D-point registrations.
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Jones, Warren Anthony. "CONTROL OF DIFFUSING DUCT FLOWUSING ACTIVE VORTEX GENERATORSWITH HOT-FILM SENSOR MEASUREMENTS." NCSU, 2001. http://www.lib.ncsu.edu/theses/available/etd-20010528-224402.
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Experiments have been conducted using vane-type vortex generators to control flow separation and exit flow distortion in a diffusing duct. The primary purpose is to examine the feasibility of using surface-mounted hot-film sensors to determine the extent of exit flow distortion. The experimental set-up consists of a two-dimensional blow down type wind tunnel with a variable diffuser exit. One diffuser wall is curved to produce a Stratford-like pressure gradient. The wall's placement is adjustable such that the adverse pressure gradient can be adjusted to promote separation. An active vortex generator array that can be placed at three streamwise locations is used to reduce the extent of flow separation and exit distortion.Diffuser surface pressure and exit total pressure measurements are obtained and compared to the hot-film data. The time-averaged mean and rms voltages from the hot-film data are used as indicators of flow separation and exit flow distortion.Results show that, with the use of the vortex generators, high mean voltages and low levels of rms voltage correlate well with improved pressure recovery. Conversely, poorer pressure recovery is associated with lower mean voltages and higher rms values compared to the baseline cases. Increased total pressures at the diffuser exit are accompanied by increases in hot-film mean voltages. These indicate higher shear stresses, which also correspond to increased flow uniformity. Lower variations in the rms voltages compared to the baseline cases also correlated well with improved total pressures at the diffuser exit.
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Cai, Hang. "Detecting Data Manipulation Attacks on Physiological Sensor Measurements in Wearable Medical Systems." Digital WPI, 2018. https://digitalcommons.wpi.edu/etd-dissertations/502.
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Recent years have seen the dramatic increase of wearable medical systems (WMS) that have demonstrated promise for improving health monitoring and overall well-being. Ensuring that the data collected are secure and trustworthy is crucial. This is especially true in the presence of adversaries who want to mount data manipulation attacks on WMS, which aim to manipulate the sensor measurements with fictitious data that is plausible but not accurate. Such attacks force clinicians or any decision support system AI analyzing the WMS data, to make incorrect diagnosis and treatment decisions about the user’s health.
Given that there are different possible vulnerabilities found in WMS that can lead to data manipulation attacks, we take a different angle by developing an attack-agnostic approach, called Signal Interrelationship CApture for Physiological-process (SICAP), to detect data manipulation attacks on physiological sensor measurements in a WMS. SICAP approach leverages the idea that different physiological signals in the user’s body driven by the same underlying physiological process (e.g., cardiac process) are inherently related to each other. By capturing the interrelationship patterns between the related physiological signals, it can detect if any signal is maliciously altered. This is because the incorrect user data introduced by adversaries will have interrelationship patterns that are uncharacteris- tic of the individual’s physiological process and hence quite different from the ones SICAP expects. We demonstrate the efficacy of our approach in detecting data manipulation attacks by building different detection solutions for two commonly measured physiological sensor measurements in a WMS environment – electrocardiogram and arterial blood pressure.
The advantage of using this approach is that it allows for detection of data manipulation attacks by taking advantage of different types of physiological sensors, which already exist in typical WMS, thus avoiding the need of redundant sensors of the same type. Furthermore, SICAP approach is not designed to be stand-alone but provides the last line of defense for WMS. It is complementary to, and coexist with, any existing or future security solutions that may be introduced to protect WMS against data manipulation attacks.
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Maffei, Renan de Queiroz. "Translating sensor measurements into texts for localization and mapping with mobile robots." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2017. http://hdl.handle.net/10183/158403.
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Localização e Mapeamento Simultâneos (SLAM), fundamental para robôs dotados de verdadeira autonomia, é um dos problemas mais difíceis na Robótica e consiste em estimar a posição de um robô que está se movendo em um ambiente desconhecido, enquanto incrementalmente constrói-se o mapa de tal ambiente. Provavelmente o requisito mais importante para localização e mapeamento adequados seja um preciso reconhecimento de local, isto é, determinar se um robô estava no mesmo lugar em diferentes ocasiões apenas analizando as observações feitas pelo robô em cada ocasião. A maioria das abordagens da literatura são boas quando se utilizam sensores altamente expressivos, como câmeras, ou quando o robô está situado em ambientes com pouco ambiguidade. No entanto, este não é o caso, por exemplo, quando o robô equipado apenas com sensores de alcance está em ambientes internos estruturados altamente ambíguos. Uma boa estratégia deve ser capaz de lidar com tais ambientes, lidar com ruídos e erros nas observações e, especialmente, ser capaz de modelar o ambiente e estimar o estado do robô de forma eficiente. Nossa proposta consiste em traduzir sequências de medições de laser em uma representação de texto eficiente e compacta, para então lidar com o problema de reconhecimento de local usando técnicas de processamento lingüísticos. Nós traduzimos as medições dos sensores em valores simples computados através de um novo modelo de observação baseado em estimativas de densidade de kernel chamado de Densidade de Espaço Livre (FSD). Estes valores são quantificados permitindo a divisão do ambiente em regiões contíguas de densidade homogênea, como corredores e cantos. Regiões são representadas de forma compacta por simples palavras descrevendo o valor de densidade espacial, o tamanho e a variação da orientação daquela região. No final, as cadeias de palavras compõem um texto, no qual se buscam casamentos de n-gramas (isto é, sequências de palavras). Nossa técnica também é aplicada com sucesso em alguns cenários de operação de longo-prazo, onde devemos lidar com objetos semi-estáticos (i.e. que se movem ocasionalmente, como portas e mobílias). Todas as abordagens foram avaliadas em cenários simulados e reais obtendo-se bons resultados.Simultaneous Localization and Mapping (SLAM), fundamental for building robots with true autonomy, is one of the most difficult problems in Robotics and consists of estimating the position of a robot that is moving in an unknown environment while incrementally building the map of such environment. Arguably the most crucial requirement to obtain proper localization and mapping is precise place recognition, that is, determining if the robot is at the same place in different occasions just by looking at the observations taken by the robot. Most approaches in literature are good when using highly expressive sensors such as cameras or when the robot is situated in low ambiguous environments. However this is not the case, for instance, using robots equipped only with range-finder sensors in highly ambiguous indoor structured environments. A good SLAM strategy must be able to handle these scenarios, deal with noise and observation errors, and, especially, model the environment and estimate the robot state in an efficient way. Our proposal in this work is to translate sequences of raw laser measurements into an efficient and compact text representation and deal with the place recognition problem using linguistic processing techniques. First, we translate raw sensor measurements into simple observation values computed through a novel observation model based on kernel-density estimation called Free-Space Density (FSD). These values are quantized into significant classes allowing the division of the environment into contiguous regions of homogeneous spatial density, such as corridors and corners. Regions are represented in a compact form by simple words composed of three syllables – the value of spatial density, the size and the variation of orientation of that region. At the end, the chains of words associated to all observations made by the robot compose a text, in which we search for matches of n-grams (i.e. sequences of words), which is a popular technique from shallow linguistic processing. The technique is also successfully applied in some scenarios of long-term operation, where we must deal with semi-static objects (i.e. that can move occasionally, such as doors and furniture). All approaches were evaluated in simulated and real scenarios obtaining good results.
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Kuschmierz, R., Y. Huang, J. Czarske, S. Metschke, F. Löffler, and A. Fischer. "3D shape measurements with a single interferometric sensor for insitu lathe monitoring." SPIE, 2015. https://tud.qucosa.de/id/qucosa%3A35040.
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Temperature drifts, tool deterioration, unknown vibrations as well as spindle play are major effects which decrease the achievable precision of computerized numerically controlled (CNC) lathes and lead to shape deviations between the processed work pieces. Since currently no measurement system exist for fast, precise and insitu 3d shape monitoring with keyhole access, much effort has to be made to simulate and compensate these effects. Therefore we introduce an optical interferometric sensor for absolute 3d shape measurements, which was integrated into a working lathe. According to the spindle rotational speed, a measurement rate of 2,500 Hz was achieved. In-situ absolute shape, surface profile and vibration measurements are presented. While thermal drifts of the sensor led to errors of several µm for the absolute shape, reference measurements with a coordinate machine show, that the surface profile could be measured with an uncertainty below one micron. Additionally, the spindle play of 0.8 µm was measured with the sensor.
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Börjeson, Charlie. "Design of a compact wavefront sensor for measurements on the human eye." Thesis, KTH, Tillämpad fysik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-284689.
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Wavefront sensors for measurements on human eyes are usually large, expensive and difficult to move. A compact wavefront sensor would be more cost-effective and versatile as is could be used in multiple systems. The aim of this thesis was to produce a more compact and portable wavefront sensor. A shorter telescope design for the wavefront sensor was proposed and checked theoretically and with computer simulations. An experimental arrangement comparing the proposed telescope design with a conventional telescope design was constructed. A compact wavefront sensor was built using off-the-shelf components and a few modified components. Tests with the compact wavefront sensor were made both on eye models and on human eyes. The compact wavefront sensor correctly measured the refractive errors of two eye models. It was also possible to perform measurements on human eyes, both in the central and peripheral visual fields, and higher order aberrations were confirmed. For positioning human eyes at the correct distance from the wavefront sensor an additional pupil camera was needed, which was not included in the system. Future improvements for the compact wavefront sensor are discussed.Vågfrontssensorer för mätningar på ögon är ofta mycket stora, dyra och svåra att transportera. En kompakt vågfrontssensor skulle vara kostnadseffektiv och flexibel eftersom den skulle kunna användas i flera olika system. Målet med detta examensarbete var att producera en mer kompakt och transportabel vågfrontssensor. En kortare teleskopvariant föreslogs och analyserades både teoretiskt och med datorsimuleringar. En experimentell uppsättning gjordes också för att jämföra den kortare teleskopdesignen med ett sedvanligt vågfrontssensorteleskop. En kompakt vågfrontssensor byggdes med standardkomponenter samt med några modifierade standardkomponenter. Tester med den kompakta vågfrontssensorn gjordes både på ögonmodeller och mänskliga ögon. Den kompakta vågfrontssensorn gav korrekta mätvärden på brytningsfelen på ögonmodellerna. Det gick bra att genomföra mätningar på mänskliga ögon, både i centrala och perifera synfältet, och högre ordningens aberrationer bekräftades. För att placera mänskliga ögon på korrekt avstånd från vågfrontssensorn krävdes en extra pupillkamera, som inte var inkluderad i den kompakta vågfrontssensorn. Framtida förbättringar för den kompakta vågfrontssensorn diskuteras.
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YU, JINSONG. "Development of Microfabricated Electrochemical Sensors for Environmental Parameter Measurements Applicable to Corrosion Evaluation and Gaseous Oxygen Detection." Case Western Reserve University School of Graduate Studies / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=case1206981091.
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Johari, Houri. "Development of MEMS Sensors for Measurements of Pressure, Relative Humidity, and Temperature." Digital WPI, 2003. https://digitalcommons.wpi.edu/etd-theses/815.
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Continued demands for better control of the operating conditions of structures and processes have led to the need for better means of measuring temperature (T), pressure (P), and relative humidity (RH). One way to satisfy this need is to use MEMS technology to develop a sensor that will contain, in a single package, capabilities to simultaneously measure T, P, and RH of its environment. Because of the advantages of MEMS technology, which include small size, low power, very high precision, and low cost, it was selected for use in this thesis. Although MEMS sensors that individually measure T, P, and RH exist, there are no sensors that combine all three measurements in a single package. In this thesis, a piezoresistive pressure sensor and capacitive humidity sensor were developed to operate in the range, of 0 to 2 atm and 0% to 100%, respectively. Finally, a polysilicon resistor temperature sensor, which can work in the range of -50ºC to 150ºC, was analyzed. Multimeasurement capability will make this sensor particularly applicable for point-wise mapping of environmental conditions for advanced process control. In this thesis, the development of sensors for such an integrated device is outlined. Selected results, based on the use of analytical, computational, and experimental solutions (ACES) methodology, particularly suited for the development of MEMS sensors, are presented for the pressure, relative humidity, and temperature sensors.
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Holst, Thomas Arthur. "Analysis of spatial filtering in phase-based microwave measurements of turbine blade tips." Thesis, Available online, Georgia Institute of Technology, 2005, 2005. http://etd.gatech.edu/theses/available/etd-05192005-165732/.
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Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2006.Littles, Jerrol W. Jr., Committee Member ; Johnson, W. Steven, Committee Member ; Kurfess, Thomas R., Committee Chair ; Melkote, Shreyes N., Committee Member.
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Ersvik, Johan. "Analysis of reliability and energy consumption in industrial wireless sensor networks." Thesis, Uppsala universitet, Signaler och System, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-177084.
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Wireless sensor networks have attracted the interest of the process industry. A process plant typically contains thousands of devices, monitoring or controlling the process. Today, all these devices are usually connected with wires. Using wireless technology simplifies deployment of new devices in a network and eliminates the need for extensive wiring. But wireless communication is also more sensitive than its wired counterpart. Therefore work is needed to make wireless sensor networks a viable option in many applications. Important issues are, for example, robustness, energy efficiency, and latency. One of the leading communication protocols for industrial wireless sensor networks is the WirelessHART protocol. This thesis investigates three ways of improving performance of the protocol, in terms of reliability and energy requirements. First, the structure of a WirelessHART packet is studied and the removal of certain fields is suggested to make the communication overhead smaller. Second, forward error correcting codes are evaluated using simulations in MATLAB. Third, measurement experiments in actual industrial environments are conducted where radio signals are transmitted and received. The variability of the received signal strength is measured and the effect that polarization diversity has on the signal variability is analyzed. The findings indicate that substantial improvements can be attained by employing polarization diversity, which can reduce channel variability and increase the expected signal strength significantly. The improvements in channel gain can be on the order of several tens of dB. The evaluations of forward error correcting codes show that the reliability is improved, with a channel gain of 3 dB. The study of the WirelessHART packet structure indicate that the packet sizes can be reduced by 15%. In turn, this also reduces energy requirements and packet error rates by 15%. This is equivalent to a gain in SNR on the order of a tenth of a dB.
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Arjyal, Bishwambhar Prasad. "In-situ stress/strain measurements in composites using an aramid fibre as sensor." Thesis, Queen Mary, University of London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.298789.
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Zhang, Kuiwei. "Surface roughness and displacement measurements using a fibre optic sensor and neural networks." Thesis, Brunel University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246145.
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Luz, Roman M. (Roman Manuel) 1979. "Design of an ultraviolet absorption spectroscopy oil concentration sensor for online HVAC measurements." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/30310.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005.Includes bibliographical references (p. 58).
Recent advances in the modeling and control of the vapor compression cycle has developed the need for a real time oil concentration rate (OCR) sensor. Because of its ability to give the most accurate online measurements of OCR, ultraviolet absorption spectroscopy has been selected as the measurement approach. Related work in this field is based on models that are unable to make accurate measurements down to zero percent oil concentration. Because of the extremely low OCR of modem HVAC units, the operating range of the sensor must be zero to one percent oil concentration. Improvements to prior models that employ Beer-Lambert's Law will allow the sensor to operate with improved accuracy over the entire operating range. This report details the design of the physical hardware, the analytical modeling, and the calibration methods to build and operate the OCR sensor.
by Roman M. Luz, III.
S.M.
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Mariotti, Davide. "Characterisation of a micro-plasma device sensor using electrical measurements and emission spectroscopy." Thesis, Ulster University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.395336.
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Shams, Arasto. "Sensor based measurements of a single phase AC/DC converter to estimate lifetime." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-282878.
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Maintenance of power electronic systems is of interest for larger systemsentirety. The reason is that they in turn could affect the whole system and cause failures if they are not functional. Maintenance of systems that are critical to be functional at all times is an area of research that is developing. For power electronics, there is more research needed in the specific area of when failures will occur and the health of the system. In the following thesis, research in the field is done to examine what causes the failures and how to prevent them at most. Further,a sensor based measurement system is developed to collect data in forms that are considered to be useful for the lifetime of the converter and the degradation. The data is further processed and analyzed with estimation methods relevant for the research.Underhåll av kraftelektronik är ett intressant område för ett större systems helhet. Orsaken är att det kraftelektroniska systemets funktionalitet kan påverka allt som är kopplat mot det och ge upphov till grövre problem för systemet i helhet. Generellt är underhåll avsystem,som är kritiska att vara funktionella,ett växande forskningsområde somutvecklas. Inom kraftelektroniken krävs det mer forskninggällandesystemets hälsa och vad som orsakaratt systemets funktionalitet misslyckas. Detta examensarbete syftar tillatt efterforska vad som orsakar att kraftelektroniska systemet misslyckas och hur dessa orsaker kan förhindras.Utöver detta är ett sensorbaserat system utvecklat för att samla data som anses vara relevanta för livslängden av systemet och dess degradering. Dataär behandlad och analyserad med estimeringmetoder relevanta för forskningen.