Dissertations / Theses on the topic 'Locating array'

Seismicity occurs mainly around plate boundaries, but there are rare occurrences of large magnitude earthquakes with a plate. When and why these events occur is not well understood but they are capable of producing significant damage to these regions. Where these earthquakes occur, are known as intraplate seismic zones. In the American Midwest there are two seismically active intraplate seismic zones, the New Madrid and Wabash Valley seismic zones. Each of these zones is capable of producing large magnitude earthquakes though it has proven somewhat difficult to study intraplate seismicity because the reoccurrence intervals for intraplate events are much longer than interplate earthquakes, requiring a much longer timescale for study. One approach to avoid the longer timescale of observation is to focus on studying smaller events, which occur more often. However, these events will have their own disadvantages with less optimal signal-to-noise ratios which does not allow events to be located by the minimum three seismometers needed to triangulate the events epicenter. A potential solution to remedy this difficulty is to use methods using one-station events that go beyond the conventional ways of locating earthquakes and possibly improve locating microseismic events that normally go unnoticed. A small seismograph array was set up around Cedar Lake, in Makanda, Illinois. This location is situated southwest of the Wabash Valley seismic zone and north of the New Madrid seismic zone but is typically viewed as aseismic. The conventional method was used for finding events by triangulation on three months data from January 1, 2011 to March 31, 2011. Through triangulation there 14 events located in January, 10 in February, and 74 in March. In addition to triangulated events, event probabilities for one-station also applied events and located a few of these events via azimuth by utilizing three component seismometers. As a result the area closest to Cedar Lake exhibited a measurable amount of activity that was not detected through triangulation. Along the Pomona Fault there were numerous azimuth events located and a few triangulated events. A linear trend of events, both azimuth and triangulated, were depicted to possibly be an unknown fault in the areas that trend NW-SE through the north portion of Cedar Lake. The comparison of rainfall and seismicity suggest the possibility of a seasonal component in background seismicity. Through our study, utilizing the one-station events to locate areas of probability for events, and locating through azimuth, methods are able to improve upon when examining microseismicity in an intraplate setting.

This dissertation was conducted as part of the efforts related to WPI's Precision Personnel Location (PPL) project, the purpose of which is to locate emergency personnel in hazardous indoor environments using radio location techniques. The current PPL system prototype uses a radio transmitter worn by the personnel, indoors, and receivers on reference units, outdoors. This dissertation proposes a new system architecture with bidirectional radio transmissions to replace the current unidirectional system architecture. This allows the development of a synchronization scheme that can extract additional Time of Arrival (TOA) information for estimating the location of personnel. This dissertation also describes an extension of the multi-signal fusion technique previously used that incorporates this TOA information. At the cost of a more complicated mobile unit design, resultant benefits of this approach include rejection of signal reflectors as solutions, improved accuracy with limited reference unit geometries, improved noise rejection and significant computation reduction. In this dissertation the mathematical underpinnings of this approach are presented, a performance analysis is developed and the results are evaluated in the context of experimental data.

This dissertation introduces Inverse Synthetic Array Reconciliation Tomography (ISART), an algorithm that exploits the short-time accuracy of inertial navigation systems (INS) and the time-stability of radio frequency (RF) positioning algorithms to achieve a high level of positioning accuracy. Novel array processing and data fusion techniques are employed to acheive performance far greater than RF and INS algorithms previously developed. This research is directed toward addressing the need for a viable tracking solution for firefighters and other first responders in urban and indoor environments. The approaches in this work are fundamentally different from other RF-INS fusion approaches, in the way we combine INS data with RF data. Rather than simply fusing the measurements from two systems that are estimating position (or states directly related to position) we use the inertial navigation data to improve the accuracy of our RF estimates at the signal level, before integrating them into an overall fusion system through the use of an extended Kalman filter (EKF). This work outlines the theoretical basis for ISART, and shows the results of simulations that support the claimed accuracy improvement of the ISART algorithm over existing methods. The viability of ISART in real world settings is then examined through the results of three field tests what were conducted in support of this research.

Combinatorial Group Testing (CGT) is a process of identifying faulty interactions (“errors”) within a particular set of items. Error Locating Arrays (ELAs) are combinatorial designs that can be built from Covering Arrays (CAs) to not only cover all errors in a system (each involving up to a certain number of items), but to locate and identify the errors as well. In this thesis, we survey known results for CGT, as well as CAs, ELAs, and some other types of related arrays. More importantly, we give several new results. First, we give a new algorithm that can be used to test a system in which each component (factor) has two options (values), and at most two errors are present. We show that, for systems with at most two errors, our algorithm improves upon a related algorithm by Mart´ınez et al. in terms of both robustness and efficiency. Second, we give the first adaptive CGT algorithm that can identify, among a given set of k items, all faulty interactions involving up to three items. We then compare it, performance-wise, to current-best nonadaptive method that can identify faulty interactions involving up to three items. We also give the first adaptive ELA-building algorithm that can identify all faulty interactions involving up to three items when safe values are known. Both of our new algorithms are generalizations of ones previously given by Mart´ınez et al. for identifying all faulty interactions involving up to two items.

Our increased reliance on localization devices such as GPS navigation has led to an increased demand for localization solutions in all environments, including indoors. Indoor localization has received considerable attention in the last several years for a number of application areas including first responder localization to targeted advertising and social networking. The difficult multipath encountered indoors degrades the performance of RF based localization solutions and so far no optimal solution has been published. This dissertation presents an algorithm called Coherent Array Reconciliation Tomography (CART), which is a Direct Positioning Algorithm (DPA) that incorporates signal fusion to perform a simultaneous leading edge and position estimate for a superior localization solution in a high multipath environment. The CART algorithm produces position estimates that are near optimal in the sense that they achieve nearly the best theoretical accuracy possible using an Impulse Radio (IR) Ultra-Wideband (UWB) waveform. Several existing algorithms are compared to CART including a traditional two step Leading Edge Detection (LED) algorithm, Singular value Array Reconciliation Tomography (SART), and Transactional Array Reconciliation Tomography (TART) by simulation and experimentation. As shown under heavy simulated multipath conditions, where traditional LED produces a limited solution and the SART and TART algorithms fail, the CART algorithm produces a near statistically optimal solution. Finally, the CART algorithm was also successfully demonstrated experimentally in a laboratory environment by application to the fire fighter homing device that has been a part of the ongoing research at Worcester Polytechnic Institute (WPI).

Wireless communication has enjoyed explosive growth over the past decade. As demands for increased capacity and quality grow, improved methods for harnessing the multipath wireless channel must be developed. The use of adaptive antenna arrays is one area that shows promise for improving capacity of wireless systems and providing improved safety through position location capabilities. These arrays can be used for interference rejection through spatial filtering, position location through direction finding measurements, and developing improved channel models through angle of arrival channel sounding measurements. This thesis provides an overview of the technical challenges involved in position location of wireless users and details the hardware development of a multi-sensor testbed at the Mobile and Portable Radio Research Group at Virginia Tech. This testbed is to be used for position location experiments as well as a host of other adaptive signal processing applications.
Master of Science

Active target location systems capable of measuring both range and bearing have niche applications, including maritime navigation where a seafaring vessel is manoeuvring in the vicinity of a harbour or an oil rig. Such systems can also be used to determine the location of other vessels for vessel-to-vessel personnel or material transfer. The usual approach is to combine FMCW radar with a mechanically or electrically steered beam, establishing both range and bearing to a target, respectively. The radar system described in this thesis is an innovative alternative approach, one that combines FMCW radar with a crossed-dipole antenna, which conveniently functions as a circular array, thereby simultaneously determining the range and bearing of an active target. By using phase mode excitation, neither mechanical nor electrical beam steering is required to locate the active target, as the receive antenna is able to monitor 360 in azimuth continually. However, due to the use of +1st and -1st order phase modes, the radar can only operate in an 180 sector unambiguously. The usual inherent problems with circular arrays being aected by multipath are also easily mitigated by the range resolution of the radar. This thesis describes in detail the development of a 2.44 GHz crossed-dipole antenna structure and its associated feed network. It also describes the first prototypes that led to its current form and goes on to discuss in detail the design and construction of the radar system and frequency shifted active target. Frequency shifting was implemented within the target to overcome the increased clutter power due to the omnidirectional receive antenna. However, firstly this thesis lays the foundation of radar theory, active targets, phase modes and basic antenna theory. Some of the literature associated with radars currently used in this type of scenario is also discussed. Appropriate analysis, modelling and experimental validation is conducted to assess system performance in relation to the predicted behaviour. The radar system was then tested in an open field, with the active target detected to a range of 125 m.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1998.
Includes bibliographical references (p. 219-221).
This document develops and evaluates the Location-Estimating, Null-Steering (LENS) algorithm for adaptive array beamforming in the case of a. known target location. Such beamformers are useful in spatial-filtering applications that enhance a desired target source while attenuating non-target, jammer sources in a given environment. Although LENS is designed for general beamforming purposes, this document em­phasizes the use of LENS to create a background-noise-reducing hearing aid. LENS processing is innovative in that it uses a novel robustness-control mechanism to yield a beamformer that avoids target cancellation under adverse conditions. Most traditional beamforming systems realize robustness control through the use of con­straints in the beamforming optimization, which is an approach that is both indirect and difficult to understand. LENS, on the other hand, achieves direct and obvious ro­bustness control by separating robustness control from the beamforming optimization in the following two-step procedure: first it solves a minima.By-constrained beamform­ing optimization in terms of the LENS parameter set [beta]_oct , and then it evaluates and ... The advantages of LENS processing are not limited to improved system robust­ness, however. Its design allows implementation using a relaxation-based approx­imation to direct-solution LENS procGssing (the LENS equiwdent of direct covari­ance matrix inversion processing for traditional systems). Simulations demonstrate that this relaxation-based implementation can combine efficient implementation, fast beamformer adaptation, and good beamforming performance, which is difficult to achieve with traditional systems.
by Joseph Gilles Desloge.
Ph.D.

An inadequate level of noise attenuation provided by a building element is frequently the result of a lack of completeness in the construction. This often invisible fault acts as a noise source in a room, so in order to undertake remedial work the source position must be found. Recently, near field noise intensity measurement has been the popular method for noise source location in buildings. This method of using intensity studies requires a grid of readings to be taken. An alternative method, the one used in this work, employs a different strategy. Here, the source location is identified by direction scanning of time delays at a number of microphones arranged in a regular three-dimensional array. A novel arrangement of seven microphones, in the shape of a wheel-brace, is used to measure the differences in time taken for the sound waves to travel from a source to the various microphones. The magnitudes of these time differences are combined and converted into the coordinates of the source, relative to an origin which is placed at the centre of the wheel-brace array. The mathematics for this conversion is derived and the errors in the experimental arrangement discussed. The use of this airay for the identification of faults in built structures is explored. A significant contribution is made to the knowledge of noise source location in buildings, since the microphone array is used to demonstrate the location of a noise source irrespective of the direction of the incoming noise. The use of computerised data collection is described for a budget system, where time was cheap, but equipment expensive. The accuracy of the technique would be improved considerably if state-of-the-art electronics were used to measure the lime differences. The feasibility, advantages and potential performance of a modem system, that could be assembled today, is described and discussed.

Thesis (M.S. in Electrical Engineering and M.S. in Systems Engineering (Electronic Warfare))--Naval Postgraduate School, September 1990.
Thesis Advisor(s): Adler, Richard W. Second Reader: Jauregui, Stephen. "September 1990." Description based on title screen as viewed on December 18, 2009. DTIC Descriptor(s): Electronic Support Measures, Direction Finding, Propagation, Warfare, Models, Performance Tests, Paths, Theses, Reflection, Vertical Orientation, Electromagnetic Radiation, Coordinates, Communication And Radio Systems, Radio Waves, Antenna Arrays, Law Enforcement, Ionospheric Propagation, Triangulation, Mathematical Models, Ionosphere. Author(s) subject terms: Single-Sight-Location, Direction Finding, High Frequency, Numerical Electromagnetics Code. Includes bibliographical references (p. 116). Also available in print.

The detection of sound sources with microphone arrays can be enhanced through processing individual microphone signals prior to the delay and sum operation. One method in particular, the Phase Transform (PHAT) has demonstrated improvement in sound source location images, especially in reverberant and noisy environments. Recent work proposed a modification to the PHAT transform that allows varying degrees of spectral whitening through a single parameter, andamp;acirc;, which has shown positive improvement in target detection in simulation results. This work focuses on experimental evaluation of the modified SRP-PHAT algorithm. Performance results are computed from actual experimental setup of an 8-element perimeter array with a receiver operating characteristic (ROC) analysis for detecting sound sources. The results verified simulation results of PHAT- andamp;acirc; in improving target detection probabilities. The ROC analysis demonstrated the relationships between various target types (narrowband and broadband), room reverberation levels (high and low) and noise levels (different SNR) with respect to optimal andamp;acirc;. Results from experiment strongly agree with those of simulations on the effect of PHAT in significantly improving detection performance for narrowband and broadband signals especially at low SNR and in the presence of high levels of reverberation.

Grâce au développement rapide des communications sans fil, la localisation par empreinte digitale (LF) a favorisé des services géodépendants considérables dans le domaine de l’Internet des objets. Dans cette thèse, nous avons d’abord proposé le système EntLoc, qui adopte l’entropie de modélisation autorégressive (AR) de l’amplitude des informations d’état de canal (CSI) comme empreinte digitale de localisation. Il partage la simplicité structurelle de la force du signal reçu (RSS) tout en réservant les informations de canal statistique les plus spécifiques à l’emplacement. De plus, un système AngLoc amélioré est égalementconçu, dont l’empreinte digitale d’angle d’arrivée (AoA) supplémentaire peut être récupérée avec précision de la phase CSI grâce à un algorithme amélioré basé sur le sous-espace, qui sert à éliminer davantage les candidats au point de référence(RP) sujets aux erreurs. Dans la phase LF en ligne, en exploitant à la fois les informations d’amplitude et de phase CSI, un nouveau schéma de régression par noyau bivarié est proposé pour déduire précisément l’emplacement de la cible. Lesrésultats d’expériences approfondies en intérieur valident la performance de localisation supérieure de notre système proposé par rapport aux approches précédentes
With expeditious development of wireless communications, Location Fingerprinting (LF) has nurtured considerable indoor location based services in the field of Internet of Things. In this thesis, we first proposed EntLoc system, which adopts Autoregressive (AR) modeling entropy of the Channel State Information (CSI) amplitude as location fingerprint. It shares the structural simplicity of the Received Signal Strength (RSS) while reserving the most location-specific statistical channel information. Moreover, an upgraded AngLoc system is further designed, whose additional angle of arrival (AoA) fingerprint can be accurately retrieved from CSI phase through an enhanced subspace based algorithm, which serves to further eliminate the error-prone Reference Point (RP) candidates. In the LF online phase, by exploiting both CSI amplitude and phase information, a novel bivariate kernel regression scheme is proposed to precisely infer the target’s location. Results from extensive indoor experiments validate the superior localization performance of our proposed system over previous approaches

La façon dont l'eau s'écoule sous les glaciers joue un rôle majeur dans le couplage mécanique glace-roche qui définit les vitesses d’écoulement des glaciers. Aujourd'hui, notre compréhension de la physique de l'hydrologie sous-glaciaire est limitée et incertaine en raison de la rareté des mesures de terrain, qui ne représentent que partiellement l’hétérogénéité de l’environnement sous-glaciaire. L'objectif de mon doctorat est d'utiliser la sismologie passive pour surmonter les difficultés observationnelles et quantifier l’évolution des conditions de pression et de la configuration du réseau d’hydrologie sous glaciaire. De récents travaux montrent que l'écoulement turbulent d'eaux sous-glaciaire génère du bruit sismique dont l’étude donne accès aux propriétés hydrodynamique associées. Ces analyses ont été menées sur une courte période et il n’est pas certains qu’elles soient appropriées à l’étude de l’hydrologie sous-glaciaire sur les échelles de temps les plus représentative de son influence sur la dynamique glaciaire (saisonnières et diurnes). De plus, ces études ne considèrent pas de changements dans la configuration des réseaux hydrologique et il existe peu d’étude ayant localisé des sources de bruit sismique spatialement éparses et temporellement variables. Dans ce doctorat, j'aborde ces défis sismologiques afin de résoudre la dynamique de l'hydrologie sous-glaciaire.Nous avons acquis sur le glacier d'Argentière (Alpes) un jeu de données continu sur 2 ans permettant d’évaluer la puissance sismique induite par les flux d'eau sous-glaciaire et de la comparer à des mesures de la vitesse de glissement basale et du débit d'eau sous-glaciaire. Je montre que l'étude de la puissance sismique à [3-7] Hz donne accès aux propriétés l'hydrodynamique des flux d'eau sous-glaciaires sur des échelles de temps tant saisonnière qu’horaire et sur une gamme de débits de 0.25 à 10 m3/sec. Avec un cadre physique adéquat j'inverse, de ces observations, les gradients de pression et rayons hydrauliques associés et identifie une dynamique saisonnière des chenaux sous-glaciaire. À faible débit, les chenaux se comportent à l'équilibre et s'adaptent aux variations de débit par des changements de rayon hydraulique. À fort débit et forte variabilité diurne en apport d'eau, les chenaux se comportent hors équilibre et subissent de fortes variations du gradient de pression hydraulique qui maintiennent de fortes pression d'eau dans les cavités et favorisent des vitesses de glissement élevées.Nous avons mené une expérience d'un mois avec un réseau sismique dense, complétée par des mesures d'épaisseur et de vitesse de surface du glacier. Sur cette base j'ai développé une méthodologie pour relever le défi de localiser des sources de bruit sismique spatialement éparses et temporellement variables. Ce faisant, j'ai obtenu une carte du système de drainage sous-glaciaire ainsi que son évolution journalière. J’ai pu ainsi observer quand et où ce système est distribué à travers des cavités connectées et favorise le glissement du glacier ou alors localisé à travers des chenaux et limite le glissement. Parallèlement, je montre que l’analyse de l’amplitude sismique permets d’étudier les crevasses, les variations d’épaisseur ou l’anisotropie de manière complémentaire aux analyses de phase sismique.Le premier résultat de ce travail transdisciplinaire est que la sismique passive peut être utiliser pour quantifier l'évolution temporelle des conditions de pression et de géométrie des chenaux sous-glaciaires sur une saison de fonte complète. Le second est qu’un réseau sismique dense peut être utiliser pour résoudre la configuration spatiale du drainage sous-glaciaire et la transition d'un réseau distribué à un réseau localisé. Ces avancées ouvrent à l’étude de tel processus sur d’autre sites tels les calottes Groenlandaise et Antarctique mais aussi à l’étude d’écoulements au sein de systèmes géophysiques tels les volcans, les karts ou les glissements de terrain
The way in which water flows in the subglacial environment exerts a major control on ice-bed mechanical coupling, which strongly defines glacier sliding speeds. Today our understanding on the physics of the subglacial hydrology network is limited because of the scarcity of field measurements that yield a partial representation of the heterogeneous subglacial environment. The aim of my PhD work is to use passive seismology to help overcome common observational difficulties and quantify the evolution of the subglacial hydrology network pressure conditions and its configuration. Recent works show that subglacial turbulent water flow generates seismic noise that can be related to the associated hydrodynamics properties. These analyses were conducted over a limited period of time making it unclear whether such approach is appropriate to investigate seasonal and diurnal timescales, I.e. when subglacial water flow influences the most glacier dynamics. In addition, previous studies did not consider spatial changes in the heterogeneous drainage system, and until now, almost no study has located seismic noise sources spatially scattered and temporally varying. In this PhD work I address those seismological-challenges in order to resolve the subglacial hydrology dynamics in time and space.We acquired a 2-year long continuous dataset of subglacial-water-flow-induced seismic power as well as in-situ measured glacier basal sliding speed and subglacial water discharge from the Glacier d'Argentière (French Alps). I show that a careful investigation of the seismic power within [3-7] Hz can characterize the subglacial water flow hydrodynamics from seasonal to hourly timescales and across a wide range of water discharge (from 0.25 to 10 m3/sec). Combining such observations with adequate physical frameworks, I then inverted the associated hydraulic pressure gradient and hydraulic radii. I observed that the seasonal dynamics of subglacial channels is characterized by two distinct regimes. At low discharge, channels behave at equilibrium and accommodate variations in discharge mainly through changes in hydraulic radius. At a high discharge rate and with pronounced diurnal water-supply variability, channels behave out of equilibrium and undergo strong changes in the hydraulic pressure gradient, which may help sustain high water pressure in cavities and favor high glacier sliding speed over the summer.We then conducted a one-month long dense seismic-array experiment supplemented by glacier ice-thickness and surface velocity measurements. Using this unique dataset, I developed a novel methodology to overcome the challenge of locating seismic noise sources spatially scattered and temporally varying. Doing so, I successfully retrieve the first two-dimensional map of the subglacial drainage system as well as its day-to-day evolution. Using this map, I characterize when and where the subglacial drainage system is distributed through connected cavities, which favour rapid glacier flow versus localized through a channelized system that prevents rapid glacier flow. In addition, I also use high frequency seismic ground motion amplitude to study glacier features such as crevasses, thickness or ice anisotropy in a complementary way to what is traditionally done with seismic phase analysis.The first outcome of this cross-boundary PhD work is that one can analyse passive seismic measurements to retrieve the temporal evolution of subglacial channels pressure and geometry conditions over a complete melt-season. The second is that dense seismic array measurements can be used to resolve the subglacial drainage system spatial configuration and observe the switch from distributed to localized subglacial water flow. Such advances open the way for studying similar subglacial process on different sites and in particular in Greenland and Antarctica. This also concerns numerous sub-surface environment that host similar process such as volcanoes, karst, and landslides

The angle of arrival estimation of multiple sources plays a vital role in the field of array signal processing as MIMO systems can be employed at both the transmitter and the receiver end and the system capacity, reliability and throughput can be significantly increased by using array signal processing. Almost all applications require accurate direction of arrival (DOA) estimation to localize the sources of the signals. Another important parameter of localization systems is the array geometry and sensor design which can be application specific and is used to estimate the DOA. In this work, various array geometries and arrival estimation algorithms are studied and then a new scheme for multiple source estimation is proposed and evaluated based on the performance of subspace and non-subspace decomposition methods. The proposed scheme has shown to outperform the conventional Multiple Signal Classification (MUSIC) estimation and Bartlett estimation techniques. The new scheme has a better performance advantage at low and high signal to noise ratio values (SNRs). The research work also studies different array geometries for both single and multiple incident sources and proposes a geometry which is cost effective and efficient for 3, 4, and 5 antenna array elements. This research also considers the shape of the ground plane and its effects on the angle of arrival estimation and in addition it shows how the mutual couplings between the elements effect the overall estimation and how this error can be minimised by using a decoupling matrix. At the end, a novel miniaturised multi element reconfigurable antenna to represent the receiver base station is designed and tested. The antenna radiation patterns in the azimuth angle are almost omni-directional with linear polarisation. The antenna geometry is uniplanar printed logspiral with striplines feeding network and biased components to improve the impedance bandwidth. The antenna provides the benefit of small size, and re-configurability and is very well suited for the asset tracking applications.

碩士
國立中正大學
電機工程所
95
A low cost and high accuracy indoor locating system using the newly proposed location method has been designed in this thesis. Combine lateration and angulation sensing techniques, the space can be treated as a polar coordinate system in which the tag position is determined by an angle and a distance. This system provides the following advantages. First, less than two locating nodes are required, which offer easy-to-setup infrastructure. Additionally, the multipath fading effect can be reduced significantly because of the high directivity of the phased antenna array. Therefore, the locating precision will be enhanced. Finally, the function of the tag circuitry is only echoing the received signal strength. Since there is no need for calculation capability, the cost and hardware complexity of the tag can be further reduces. The measurement results show a great locating accuracy of 50 cm within a 10 ×10 m2 region. Both switched-beam and steering-beam phased antenna array are constructed in this work. In switched-beam antenna array design, two multi-layer 4×4 Bulter Matrix integrated with a 2×4 patch antenna array are demonstrated. Eight beams steering into different direction are successfully induced. The scanning range is approximate 100° both horizontally and vertically, and the side-lobe level is better than -10dB. Furthermore, a low loss-variation (-9.8dB ~ -12.2dB) CMOS 360° reflection-type phase shifter has been designed and will be applied in the tunable steering-beam antenna array, where the system resolution will be further increased.

碩士
國立中正大學
電機工程所
95
This thesis presents a novel wireless indoor locating system based on the phased-antenna array technique. In the existing wireless indoor locating systems, the triangulation sensing technique is utilized to locate tag. The need of multiple locating nodes increases the infrastructure cost. Furthermore, the use of receiving signal strength indicator (RSSI) to estimate the relative distance results in inaccurate distance estimation. In this thesis, we combine the lateration and angulation sensing techniques to locate the tag precisely with the polar coordinate, which provides the following advantages. First, less than two locating nodes are required, which offer easy-to-setup infrastructure. Second, the multipath fading effect can be reduced significantly because of the inherent high directivity of the phased antenna array. Therefore, the locating precision will be enhanced. Third, the tag is only responsible for received signal strength transmitting the received signal strength and doesn’t need to calculate the location by itself, which reduces the tag hardware complexity. The proposed wireless indoor locating system has measured accuracy of 50 cm in a 10 ×10 m2 region, which is much better than the literatures reported. A CMOS Butler Matrix MMIC is also designed and implemented with standard 0.18-μm CMOS Technology. The measured insertion loss of 4.5 to 5 dB in each signal path and the phase distributions of 45°±3°, 135±5°, -45°±3°, -135±5° are obtained. By incorporating this CMOS Butler matrix MMIC in a phased-antenna array, four switched beams are generated at θ=-45°(2L)、θ=-15°(1L)、θ=15°(1R)、θ=45°(2R), respectively with the side lobe level greater than 8 dB.

abstract: This dissertation studies three classes of combinatorial arrays with practical applications in testing, measurement, and security. Covering arrays are widely studied in software and hardware testing to indicate the presence of faulty interactions. Locating arrays extend covering arrays to achieve identification of the interactions causing a fault by requiring additional conditions on how interactions are covered in rows. This dissertation introduces a new class, the anonymizing arrays, to guarantee a degree of anonymity by bounding the probability a particular row is identified by the interaction presented. Similarities among these arrays lead to common algorithmic techniques for their construction which this dissertation explores. Differences arising from their application domains lead to the unique features of each class, requiring tailoring the techniques to the specifics of each problem. One contribution of this work is a conditional expectation algorithm to build covering arrays via an intermediate combinatorial object. Conditional expectation efficiently finds intermediate-sized arrays that are particularly useful as ingredients for additional recursive algorithms. A cut-and-paste method creates large arrays from small ingredients. Performing transformations on the copies makes further improvements by reducing redundancy in the composed arrays and leads to fewer rows. This work contains the first algorithm for constructing locating arrays for general values of $d$ and $t$. A randomized computational search algorithmic framework verifies if a candidate array is $(\bar{d},t)$-locating by partitioning the search space and performs random resampling if a candidate fails. Algorithmic parameters determine which columns to resample and when to add additional rows to the candidate array. Additionally, analysis is conducted on the performance of the algorithmic parameters to provide guidance on how to tune parameters to prioritize speed, accuracy, or a combination of both. This work proposes anonymizing arrays as a class related to covering arrays with a higher coverage requirement and constraints. The algorithms for covering and locating arrays are tailored to anonymizing array construction. An additional property, homogeneity, is introduced to meet the needs of attribute-based authorization. Two metrics, local and global homogeneity, are designed to compare anonymizing arrays with the same parameters. Finally, a post-optimization approach reduces the homogeneity of an anonymizing array.
Dissertation/Thesis
Doctoral Dissertation Computer Science 2019

abstract: Complex systems are pervasive in science and engineering. Some examples include complex engineered networks such as the internet, the power grid, and transportation networks. The complexity of such systems arises not just from their size, but also from their structure, operation (including control and management), evolution over time, and that people are involved in their design and operation. Our understanding of such systems is limited because their behaviour cannot be characterized using traditional techniques of modelling and analysis. As a step in model development, statistically designed screening experiments may be used to identify the main effects and interactions most significant on a response of a system. However, traditional approaches for screening are ineffective for complex systems because of the size of the experimental design. Consequently, the factors considered are often restricted, but this automatically restricts the interactions that may be identified as well. Alternatively, the designs are restricted to only identify main effects, but this then fails to consider any possible interactions of the factors. To address this problem, a specific combinatorial design termed a locating array is proposed as a screening design for complex systems. Locating arrays exhibit logarithmic growth in the number of factors because their focus is on identification rather than on measurement. This makes practical the consideration of an order of magnitude more factors in experimentation than traditional screening designs. As a proof-of-concept, a locating array is applied to screen for main effects and low-order interactions on the response of average transport control protocol (TCP) throughput in a simulation model of a mobile ad hoc network (MANET). A MANET is a collection of mobile wireless nodes that self-organize without the aid of any centralized control or fixed infrastructure. The full-factorial design for the MANET considered is infeasible (with over 10^{43} design points) yet a locating array has only 421 design points. In conjunction with the locating array, a ``heavy hitters'' algorithm is developed to identify the influential main effects and two-way interactions, correcting for the non-normal distribution of the average throughput, and uneven coverage of terms in the locating array. The significance of the identified main effects and interactions is validated independently using the statistical software JMP. The statistical characteristics used to evaluate traditional screening designs are also applied to locating arrays. These include the matrix of covariance, fraction of design space, and aliasing, among others. The results lend additional support to the use of locating arrays as screening designs. The use of locating arrays as screening designs for complex engineered systems is promising as they yield useful models. This facilitates quantitative evaluation of architectures and protocols and contributes to our understanding of complex engineered networks.
Dissertation/Thesis
Doctoral Dissertation Computer Science 2015

abstract: Modern computer systems are complex engineered systems involving a large collection of individual parts, each with many parameters, or factors, affecting system performance. One way to understand these complex systems and their performance is through experimentation. However, most modern computer systems involve such a large number of factors that thorough experimentation on all of them is impossible. An initial screening step is thus necessary to determine which factors are relevant to the system's performance and which factors can be eliminated from experimentation. Factors may impact system performance in different ways. A factor at a specific level may significantly affect performance as a main effect, or in combination with other main effects as an interaction. For screening, it is necessary both to identify the presence of these effects and to locate the factors responsible for them. A locating array is a relatively new experimental design that causes every main effect and interaction to occur and distinguishes all sets of d main effects and interactions from each other in the tests where they occur. This design is therefore helpful in screening complex systems. The process of screening using locating arrays involves multiple steps. First, a locating array is constructed for all possibly significant factors. Next, the system is executed for all tests indicated by the locating array and a response is observed. Finally, the response is analyzed to identify the significant system factors for future experimentation. However, simply constructing a reasonably sized locating array for a large system is no easy task and analyzing the response of the tests presents additional difficulties due to the large number of possible predictors and the inherent imbalance in the experimental design itself. Further complications can arise from noise in the system or errors in testing. This thesis has three contributions. First, it provides an algorithm to construct locating arrays using the Lovász Local Lemma with Moser-Tardos resampling. Second, it gives an algorithm to analyze the system response efficiently. Finally, it studies the robustness of the analysis to the heavy-hitters assumption underlying the approach as well as to varying amounts of system noise.
Dissertation/Thesis
Masters Thesis Computer Engineering 2018

碩士
大同大學
資訊工程研究所
91
In this thesis, we discuss the correlation between frequency, and position of sound signal and interval between microphones. For a given requirement and signal characteristics, we try to provide some guide to line to make optimum specification then get the best resolution. For the sound source localization, the delay of arrival (DOA) technique has been proposed few decades. The technique detects the signal wave delay in microphone pairs and use the delay time to compute the sound source direction.The cross-power spectrum phase (CSP) analysis and first wavefront detected method are usually used in DOA technique. The CSP analysis use the signal's phase different of microphone pair to calculate the sound source direction. The wavefront detected method is obtained the results by detecting the first wavefront. In the experiment, we adjust the sound's signal frequency, angle and interval between two microphones. The results would exhibit the interactive among these factors. From these results, some guide lines to decide some parameters of sound source location are given.

碩士
國立高雄應用科技大學
電機工程系博碩士班
102
In this thesis, we use a microphone array with blind source separation algorithm and time difference of arrival (TDOA) in far-situation to do multiple sound source localization and source number estimation. Most of the researches of multiple sound source localization are focused on the angle of source. However, there is a problem that the user cannot identify the corresponding angle of each sound source, and we name this problem as data association. To solve this problem, we use nonnegative matrix factor 2-D deconvolution (NMF2D) to separate the mixed single and then we can consider the multiple sound source localization as many independent sound sources localization. Therefore, we can calculate the corresponding angle of each sound source. We also use the interaural level difference (ILD) and TDOA to estimate the distance of each sound source. Finally, the multiple sound source localization system is programmed by LabVIEW 2012 software.

碩士
國立高雄大學
電機工程學系碩士班
100
Most indoor location technology depended on RSSI (Received Signal Strength Indication) to measure the distance. However, in the indoor environment, a wireless receiver will suffer a fast fading induced from the multipath interference. Without a reliable RSSI–distance relationship, the accuracy of the distance prediction is usually poor. To solve this problem, this paper investigates the use of polarization and high directivity antenna array with the cell concept to provide a more reliable RSSI–distance relationship. In verification measurements, we select two typical environments, i.e., an office environment (the 407 Lab) and a corridor respectively. Using the proposed method to combine signal strength gradient identification with array antenna radiation pattern, it shows that the reliable RSSI–distance relationship could be predicted up to about 20m. So, for a cell size of about 40m for zigbee network, the user location can be accurately predicted.

碩士
國立暨南國際大學
資訊工程學系
98
In this thesis, we study the unusual sound source localization problem in an outdoor area. In an outdoor environment, the accuracy of sound source localization will be influenced by the wind velocity, the air temperature, and background noises. This work aims to develop a sound source localization method which is accuracy and robust against noise and is able to localize multiple sound sources having non-overlapping spectrums in the frequency domain. The probability density function (PDF) of the time delay of arrival (TDOA) between two signals is derived based on the PDF of the phase angle between two signals. The PDF of the phase angle is derived from a noise model of the input signals. According to the derived probabilistic model, possible locations of the sound sources can be computed. The mean-shift algorithm is used to find clusters of possible locations. Too small clusters are discarded and the centers of the remaining clusters represent the estimated locations of the sound sources. To test the proposed method, a uniform linear microphone array consisting four microphones is constructed to collect sound signals in an outdoor area. The experimental results show that, in a strictly single sound source scenario, the accuracy of the proposed method is comparable to a very popular method known as the phase transform (PHAT) technique. Furthermore, when the background noises, such as the sounds from insects and/or birds, are not negligible, the proposed method outperforms the PHAT method. Additionally, the experimental results of estimating two simultaneous sound sources show that the proposed method also can achieve considerable stability for detecting/localizing multiple sound sources provided that the sound sources have non-overlapping spectrums.

碩士
元智大學
電機工程研究所
88
It''s well known that the multibeam antenna arrays can improve the performance of cellular mobile communication systems in many features. In this thesis, the analysis and design of the multibeam antenna arrays are presented. The development and performance analysis on direction finding and position location applications are also investigated. Firstly, the basic theory of antenna array is described and the array patterns for different number of elements and interelement''s spacings are simulated. The relations among antenna directivity, beamwidth, side lobe level and scanned angle are also discussed. Secondly, the characteristics of two configurations of multibeam antenna array, the beam steering sectorized and the equal beamwidth, are analyzed and compared. The beam forming and beam scanning networks are realized. Finally, the performance of direction finding using the amplitude comparison of two beams is analyzed. The analysis results show that the wider the antenna beamwidth, the wider the simultaneous field of view, the less the angular gradient of error signal, the less the direction finding accuracy. The accuracy the position location based on the direction finding method depends on the direction finding accuracy and on the distance and geometrical relations between the mobile station and the base stations.

碩士
國立成功大學
地球科學系
103
How to determine the magnitude and the hypocenter in few seconds after an earthquake occurring are two of the most important issues in seismic hazard mitigation. Based on the on-site process, we installed two local early warning arrays in Ilan and Tainan City of the newly established Palert EEW network and adopted the waveform stacking method to enhance the coherent part of early arrivals. The MPd method is used to estimate the earthquake magnitude. By modifying the present Pd attenuation relationships, we show that the accuracy (S.D.V. = 0.28) of magnitude estimation for the on-site EEW mode can be siginificantly improved since the sensors of the nearly built Palert network aer installed inside the building. The earthquake location for EEW purpose is always a tough problem due to the complicated process and long reporting time. Therefore, we developed a new method to determine the hypocenter in a simple-calculating process. Different events will have different ranking list of the triggered stations due to the geographical distribution if the point source is assumed. We divided Taiwan region into many grids. Each grid is the preset hypocenter and has its own station ranking list as the pre-calculate database computed by the velocity model and 3-D ray tracing method. When an earthquake occurs, we use the real station ranking list to compare the database, and find the least difference grid as the hypocenter. Our results show comparable or better performing than the current operating rapid reporting and EEW systems in Taiwan.

No
Searching for and mapping the physical extent of unmarked graves using geophysical techniques has proven difficult in many cases. The success of individual geophysical techniques for detecting graves depends on a site-by-site basis. Significantly, detection of graves often results from measured contrasts that are linked to the background soils rather than the type of archaeological feature associated with the grave. It is evident that investigation of buried remains should be considered within a 3D space as the variation in burial environment can be extremely varied through the grave. Within this paper, we demonstrate the need for a multi-method survey strategy to investigate unmarked graves, as applied at a "planned" but unmarked pauper's cemetery. The outcome from this case study provides new insights into the strategy that is required at such sites. Perhaps the most significant conclusion is that unmarked graves are best understood in terms of characterization rather than identification. In this paper, we argue for a methodological approach that, while following the current trends to use multiple techniques, is fundamentally dependent on a structured approach to the analysis of the data. The ramifications of this case study illustrate the necessity of an integrated strategy to provide a more holistic understanding of unmarked graves that may help aid in management of these unseen but important aspects of our heritage. It is concluded that the search for graves is still a current debate and one that will be solved by methodological rather than technique-based arguments.

碩士
國立成功大學
地球科學系
104
INTRODUCTION Taiwan is located on the west of Circum-Pacific Seismic Zone. How to reduce earthquake damages is a very important work. EEW is one of method for seismic hazard mitigation. Quick estimation on magnitude and earthquake location after an earthquake occurring are two main tasks for EEW system. Palert is a new, MEMS-type and low-cost accelerometer and has installed more than 500 stations in Taiwan since June 2012. This high density of seismic station is benefit to EEW system, but its relatively low signal-to-noise ratio (S/N) would reduce the accuracy of estimation. Based on the result from Tsai et al. (2015), we create a new module for waveform stacking using Earthworm platform, which is free software from USGS. The result of this study suggests that real-time, on-line array stacking can enhance the S/N ratio and get more accurate estimated magnitude. In earthquake locating respect, we apply the travel-time sequence method (Tsai et al., 2015) to Palert EEW network. The travel-time sequence method uses 3-D velocity model and 3-D ray tracing technique to compute the travel time. In this study, we propose two ways to adjust the grid searching method. One is calculating the average of the points which are found from the first one to the first ten triggered stations. Another is cutting down the difference between the database and the real travel-time sequence of stations. The results show the feasibility of the method and provide additional locating earthquake method to the Palert EEW system. Method and Data Analysis (1) The new local on-line EEW arrays Earthworm is a free software from USGS and used to receive and manage real-time signals recorded by the field Palert stations. According to the result from Tsai et al. (2015), relatively low S/N ratio of Palert device would reduce the accuracy of estimation and the waveform stacking method can increase S/N ratio. Fig. 1 illustrates the Earthworm configuration of the Palert system. The shared memories are indicated by four circles. Three modules named PICK_EEW, TCPD, and DCSN were created for managing P-wave phase picking (PICK_EEW), trigger associations (PICK_EEW), hypocenter locations (TCPD), magnitude estimations (TCPD), and alert filtering prior to broadcasting (DCSN) by Chen et al. (2015a and b) (Fig. 1). In this study, we create a new module for cross-correlation and waveform stacking as shown in fig.2. To test the new structure of this study, we reply the 20160206 Meinong earthquake to the Palert EEW system and evaluate the performance on magnitude estimation. Fig.1 The mode of operation in Earthworm Fig.2 The mode of operation in Earthworm (2) The travel-time sequence method for locating earthquake for the local EEW arrays in Taiwan The high density of Palert in Taiwan is very useful in EEW. In this study, we apply the travel-time sequence method (Tsai et al., 2015) on it. This method use 3-D velocity model and pseudo-bending method to compute the travel time and compare the station sequence of event with database to locate the hypocenter quickly. However, the uncertainty of P-wave picking due to low S/N ratio may cause the location error. In this study, we propose two ways to modify the grid searching method. For increasing the truly point ratio, we calculate the average of the points which are found from the first one to the first ten triggered stations. Another way is shorten the difference between the station sequence of event and database to reduce the effect of above cases. Result and Discussion (1) The new local on-line EEW arrays The quality criteria for picking are described in the study of Chen et al. (2015a and b). The report from TCPD has 21 stations from 15 arrays in SW Taiwan. The result show that the S/N ratio after the stacking and the accuracy of estimated Mpd are better than before but the reporting time difference between the two methods is not obvious. It’s just 0.09±0.044 s. This result is enough to support that the new method is more suitable for Palert EEW system. (2) The travel-time sequence method for earthquake locating for the local EEW arrays in Taiwan After self-simulate of database, we decide to use 10 stations to locate events. In this study, we choose events from 2013 to 2015 with ML 〉 5. The result shows using two modified methods can get more accurate earthquake location. In inland events, the location error of Palert EEW system is 11 km and the best of this study is 8 km. In offshore events, the location error of Palert EEW system is 17 km and the best of this study is 20 km. The result show that if we can combine two types of location methods, it may provide a reliable, precise and stable earthquake location result. Conclusion (1) The new local on-line EEW arrays 1. We have established a new hybrid-type of EEW. 2. This hybrid-type of EEW based on local array can make the Palert EEW system more usable. 3. The array-based EEW system can provide more accurate estimate on earthquake magnitude. (2) The travel-time sequence method for earthquake locating for the local EEW arrays in Taiwan 1. The two modified grid searching method can effectively improve the coverage problem of Palert. 2. This method is more suitable for a region with a more complicated velocity structure. 3. The average arrival time of the tenth triggered station for all events is of about 8 seconds, which has the potentiality for Palert EEW system usage.

碩士
國立臺灣大學
地質科學研究所
102
Since there is no practical method for earthquakes prediction today, the main disaster prevention method is based on the seismic design of buildings. Earthquake early warning (EEW) is another effective way to reduce damage in real-time (Kanamori et al., 1997). Because EEW needs to provide reliable message in a short time, it is important to shorten the reporting time window by the improving of data process. In order to provide location and magnitude after an earthquake just happened, a low cost and high density EEW system has been developed and established by using the Palert seismometers in Taiwan (Wu et al., 2013). Due to the distribution of the stations, which detected the signals at first, is poor. It needs more than eight stations to get reliable information. Thus, it shortens the lead time before strong ground shaking. This study use the arrival-time order location (AOL) method, which introduced by Anderson in 1981, to improve the efficiency of Palert EEW system for earthquake location. At the same time, because of Palert has a relatively low signal-to-noise ratio (S/N) in τc (Kanamori, 2005, Wu and Kanamori, 2005a) determinations. So τc approach does not use in the Palet EEW system (Wu et al., 2013). This study try to use the signals stacking small arrays to enhance S/N ratio and try to use τc for magnitude estimation. Results shows that, AOL method can provide a reliable earthquake location by only using four to five stations. It can improve the EEW efficiency. By stacking the signals from small array can also get more accurate magnitude estimation usingτc. So that more information can be provided in on-site EEW warning purpose.