Dissertations / Theses on the topic 'Multi-detectors'

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2009.
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. 140-148).
Single-photon-detector arrays can provide unparalleled performance and detailed information in applications that require precise timing and single photon sensitivity. Such arrays have been demonstrated using a number of single-photon-detector technologies, but the high performance of superconducting nanowire single photon detectors (SNSPDs) and the unavoidable overhead of cryogenic cooling make SNSPDs particularly likely to be used in applications that require detectors with the highest performance available. These applications are also the most likely to benefit from and fully utilize the large amount of information and performance advantages provided by a single-photon-detector array.Although the performance advantages of individual superconducting nanowire single photon detectors (SNSPDs) have been investigated since their first demonstration in 2001, the advantages gained by building arrays of multiple SNSPDs may be even more unique among single photon detector technologies. First, the simplicity and nanoscale dimensions of these detectors make it possible to easily operate multiple elements and to closely space these elements such that the active area of an array is essentially identical to that of a single element. This ability to eliminate seam-loss between elements, as well as the performance advantages gained by using multiple smaller elements, makes the multi-element approach an attractive way to increase the general detector performance (detection efficiency and maximum counting rate) as well as to provide new capabilities (photon-number, spatial, and spectral resolution). Additionally, in contrast to semiconductor-based single-photon detectors, SNSPDs have a negligible probability of spontaneously emitting photons during the detection process, eliminating a potential source of crosstalk between array elements.
(cont.) However, the SNSPD can be susceptible to other forms of crosstalk, such as thermal or electromagnetic interactions between elements, so it was important to investigate the operation and limitations of multi-element SNSPDs. This thesis will introduce the concept of a multi-element SNSPD with a continuous active area and will investigate its performance advantages, its potential drawbacks and finally its application to intensity correlation measurements.This work is sponsored by the United States Air Force under Contract #FA8721-05-C-0002. Opinions, interpretations, recommendations and conclusions are those of the authors and are not necessarily endorsed by the United States Government.
by Eric Dauler.
Ph.D.

This thesis investigates the measurement of spatial correlations of photon pairs generated through spontaneous parametric down-conversion with single-photon sensitive multi-pixel detectors. A custom designed and fabricated 8£1 fibre array detector for time to position multiplexing was characterised. This detector was then commissioned in an experiment measuring the spatial correlations of photon pairs in position, momentum and intermediate bases. The fibre array measured eight positions simultaneously with one Single-Photon Avalanche Diode, which led to an eight-fold increase in the data acquisition rate compared to traditional experiments, where a single SPAD was scanned across the detection plane. To capture all of the emitted light, an electron-multiplying CCD (EMCCD) camera was used. The spatial correlations were measured for the first time in momentumand position bases with a single-photon sensitive camera. Additionally, over 2500 spatial states were accessed,which, to date, is the highest number of accessed states, using the transverse positions of correlated photon pairs. The detected photon pairs were tested, if they fulfil the requirements of entanglement. The calculated variance product was 1 order of magnitude and almost three orders of magnitude below the classical limit of separability for the fibre array and the EMCCD camera respectively. Finally the image enhancement of using a correlated light source with a noise rejection algorithm was investigated experimentally and theoretically.

L’apparition de la segmentation électrique des détecteurs au GeHP et de l’électronique numérique a ouvert la voie à des applications prometteuses, telles que le tracking γ, l’imagerie γ ou la mesure bas bruit de fond, pour lesquelles une connaissance fine de la réponse du détecteur est un atout. L’IPHC a développé une table de scan utilisant un faisceau collimaté, qui sonde la réponse d’un détecteur dans tout son volume en fonction de la localisation de l’interaction. Elle est conçue pour utiliser une technique innovante de scan 3D, le Pulse Shape Comparison Scan, qui a été d’abord simulée afin de démontrer son efficacité. Un détecteur AGATA a été scanné de manière approfondie. Des scan 2D classiques ont permis, entre autres, de mettre en évidence des effets locaux de modification de la collection des charges, liés à la segmentation. Pour la première fois, une base de données 3D, complète, de formes d’impulsions fonction de la position d’interaction a été établie. Elle permettra notamment d’améliorer les performances du spectromètre AGATA
Recent developments of electrical segmentation of HPGe detectors, coupled with digital electronics have led to promising applications such as γ-ray tracking, γ-ray imaging or low-background measurements which will benefit from a fine knowledge of the detector response. The IPHC has developed a new scanning table which uses a collimated γ-ray beam to investigate the detector response as a function of the location of the γ-ray interaction. It is designed to use the Pulse Shape Comparison Scan technique, which has been simulated in order to prove its efficiency. An AGATA detector has been thoroughly scanned. 2D classical scans brought out, for example, local charge collection modification effects such as charge sharing, due to the segmentation. For the first time, a 3D, complete pulse-shape database has been established. It will especially allow to improve the overall AGATA array performances

Digital imaging systems for medical applications must bebased upon highly efficient detectors to ensure low patientdose. This is particularly important in screening mammographybecause of the large number healthy women that is examined. Amammography system must also provide high spatial and contrastresolution. Different approaches are compared in this thesis,and it is argued that a system based on photon countingdetectors in a scanned multi-slit geometry provides aperformance superior to established technologies.

The system is realized using silicon strip detectorsirradiated at a small angle relative to the wafer surface,thereby offering large absorption depth. A linear pixelarray isscanned across the breast to obtain the complete image.Pulse-processing electronics rejecting all detector andelectronics noise count the number of photons that aredetected, forming the pixel values of the image.

Optimization of the detector design is discussed in detail.The detector has been carefully simulated to investigate chargemotion and signal formation after photoninteraction. Based onthese simulations, the impact of the detector characteristicson the image quality has been evaluated.

Detectors have been manufactured and evaluated both assingle components and as part of experimental imaging devicesincluding custom readout electronics. Presented in this thesisare the measured detector characteristics including a verifi-cation of charge collection efficiency and confirmation thatthe quantum efficiency is 90% for a typical mammographyspectrum. Modulation transfer functions and noise power spectrawere recorded and the detective quantum efficiency calculated.A prototype mammography system was also assembled and themodulation transfer function recorded. The interpretation ofthe modulation transfer function and detective quantumefficiency is discussed for digital systems in general and fora scanned multi-slit system in particular.

Keywords:x-ray, imaging, silicon, detector, digital,mammography, scanning, photon counting.

The study of the symmetry energy under well controlled laboratory conditions serves to provide constraints for theoretical models covering a wide range of physical phenomena, from the neutron skin thickness of 208Pb to the structure and dynamics of neutron stars. Of particular interest at the present time is the density dependence of the symmetry energy. The INDRA-VAMOS (E503) experiment intends to extract constraints on the density dependence of the symmetry energy at low densities using isotopic scaling and isospin diffusion measurements. In this report the physics motivation and experiment will be discussed in detail, as well as the calibration of the detectors and recent changes to the analysis code.

In this thesis, I have developed a range of theoretical and numerical techniques for modelling the behaviour of partially coherent optical systems and multi-mode detectors. The numerical simulations were carried out for the ultra-low-noise Transition Edge Sensors (TESs) being proposed for use on the SAFARI instrument on the cooled aperture infrared space telescope SPICA (34 - 210 μm). The optical behaviour of the SAFARI system is described in terms of the optical modes of the telescope, as distinct from the optical modes of the detector. The performance of the TESs were assessed in terms of signal power, background power and photon noise. To establish a method for precisely characterising and calibrating ultra-low-noise TESs, a cryogenic test system was designed and engineered to measure the optical efficiencies of the SAFARI TESs. The multi-mode, partially coherent illumination conditions of the measurement system were engineered to be precisely the same as those of the telescope. A major difference between the test system and the telescope’s optics is that the telescope will have focusing elements, but the test system was designed to avoid focusing elements in order to keep the optical path as clean as possible. The theoretical formalism and numerical models were adapted accordingly to address this difference. The numerical simulations show that the test system could provide near identical optical performance as that of the telescope system even though the focusing elements were absent. I also performed experimental measurements to investigate the optical efficiencies of the multi-mode TESs. The detectors worked exceedingly well in all respects with satisfactory optical efficiencies. In addition, it has been shown that the optical model provides a good description of the optical behaviour of the test system and detectors. Further modal analysis was developed to study losses in the multi-mode horns. The optical behaviour of the waveguide-mounted thin absorbing films in the far-infrared was modelled using a mode-matching method.

Includes bibliographical references (leaves 118-123).
In this thesis we address the problem of improving the uplink capacity and the performance of a DS-CDMA system by combining MUD and turbo decoding. These two are combined following the turbo principle. Depending on the concatenation scheme used, we divide these receivers into the Partitioned Approach (PA) and the Iterative Approach (IA) receivers. To enable the iterative exchange of information, these receivers employ a Parallel Interference Cancellation (PIC) detector as the first receiver stage.

PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO
Para estabelecer com exatidão as curvas em eficiência de detectores a germânio, usam-se radionuclídeos que possuem decaimento complexo, como o 152 Eu e 133 Ba. Porém, por possuírem poucas linhas gama de boa intensidade e irregularmente distribuídas no espectro, esses radionuclídeos não podem ser usados sozinhos. Para superar tais dificuldades, o 166m Ho mostra-se conveniente como padrão único destinado à calibração em eficiência dos espectrômetros a germânio, pois decai por emissão b - , com emissões subseqüentes de 40 linhas gama intensas e bem distribuídas entre 80 e 1500 keV. Além disso, sua longa meia-vida (1200 anos) e raios X característicos entre 40 e 50 keV, o tornam um padrão excelente para calibração de detectores de germânio. É preciso, no entanto, conhecer com exatidão as probabilidades de emissão de fótons de suas principais linhas, uma vez que a literatura tem apresentado estes valores com discrepâncias. Neste trabalho é proposta uma metodologia para determinar, com rigor metrológico, a probabilidade de emissão de suas principais linhas, por meio do uso combinado de espectrometria gama e técnicas de coincidência (4pb-g ). Os resultados experimentais apresentaram-se convergentes em relação aos dados de outros autores, com incertezas menores ou compatíveis.
The efficiency and calibration curves as function of gamma- ray energy for a germanium detector are usually established by using many standard gamma-ray sources of radionuclides decaying with few gamma rays or radionuclides having complex decay scheme, as 152 Eu or 133 Ba. But these radionuclides cannot be used alone, because they have a few gamma lines with high intensity and these lines have a irregular distribution in the energy spectrum. 166m Ho is found to be a convenient single source for such calibration, because it decays by b - with subsequent emission of about 40 strong and well distributed gamma lines between 80 and 1500 keV. Moreover, its long half - life (1200 years) and X-rays characteristics between 40 and 50 keV makes it a good standard for calibration of germanium detectors. However, it is necessary to know with accuracy and precision the gamma ray intensities of their main lines, due to the fact that literature has showed discrepant values. Then, a methodology to determine the emission probability of its main lines is proposed by means of combined use of gamma spectrometry and coincidence 4pb - g techniques. The experimental results show consistence to the others authors, with lower or compatible uncertainties.
Para estabelecer con exactitud las curvas en eficiencia de detectores la germánio, se utilizan radionuclídeos que poseen decaimiento complejo, como el 152 Eu y 133 Ba. Sin embargo, como poseen pocas líneas gama de buena intensidad y irregularmente distribuidas en el espectro, esos radionúcleos no pueden ser usados separadamente. Para superar tales dificuldades, el 166m Ho muestra se conveniente como padrón único destinado a la calibración en eficiencia de los espectrómetros la germánio, pues decae por emisión b , con emisiones subsecuentes de 40 líneas gama intensas y bien distribuidas entre 80 y 1500 keV. Además, su larga media vida (1200 anos) y rayos X característicos entre 40 y 50 keV, el tornan un padrón excelente para calibración de detectores de germanio. Es preciso conocer con exactitud las probabilidades de emisión de fóptons de sus principales líneas, una vez que la literatura ha presentado estos valores con discrepancias. En este trabajo se propone una metodología para determinar, con rigor metrológico, la probabilidad de emisión de sus principales líneas, por medio del uso combinado de espectrometría gama y técnicas de coincidencia (4pb g ). Los resultados experimentales presentaran se convergentes en relación a los datos de otros autores, con incertezas menores o compatibles.

Doctor of Philosophy
Department of Mechanical and Nuclear Engineering
Douglas S. McGregor
The 3He gas shortage for neutron detection has caused an increase in research efforts to develop viable alternative technologies. 3He neutron detectors cover areas ranging from 10–1000 cm2 in cylindrical form factors and are ideal for many nuclear applications due to their high intrinsic thermal neutron detection efficiency (> 80%) and gamma-ray discrimination (GRR ≤ 1 x 10-6) capabilities. Neutron monitoring systems for nuclear security applications include Radiation Portal Monitors (RPM’s), backpack, briefcase, and hand-held sensors. A viable replacement technology is presented here and compares three neutron detectors, each with different neutron absorber materials, to current 3He standards. These materials include Li and/or B silica aerogels, LiF impregnated foams, and metallic Li foils. Additionally, other neutron absorbing materials were investigated in this work and include LiF coated Mylar, B foils, BN coated carbon foam, and BN coated plastic honeycomb. From theoretical calculations, the Li foil material showed the greatest promise as a viable 3He alternative, thus a majority of the research efforts were focused on this material. The new neutron detector was a multi-wire proportional counter (MWPC) constructed using alternating banks of anode wires and 95% enriched 6Li foils sheets spaced 1.63 cm apart. In total, six anode banks and five layers of foil were used, thus an anode wire bank was positioned on each side of a suspended foils. Reaction products from the 6Li(n,α)3H reaction were able to escape both side of a foil sheet simultaneously and be measured in the surrounding gas volume concurrently. This new concept of measuring both reaction products from a single neutron absorption in a solid-form absorber material increased the intrinsic thermal neutron detection efficiency and gamma-ray discrimination compared to coated gas-filled detectors. Three different sizes of Li foil MWPC neutron detectors were constructed ranging from 25–1250 cm2 and included detectors for RPM’s, backpacks, and hand-held systems. The measured intrinsic thermal neutron detection efficiency of these devices was approximately 54%, but it is possible to exceed 80% efficiency with additional foils. The gamma-ray discrimination abilities of the detector exceeded 3He tubes by almost three orders of magnitude (GRR = 7.6 x 10-9).

In this work, multi-band (multi-color) detector structures considering different semiconductor device concepts and architectures are presented. Results on detectors operating in ultraviolet-to-infrared regions (UV-to-IR) are discussed. Multi-band detectors are based on quantum dot (QD) structures; which include quantum-dots-in-a-well (DWELL), tunneling quantum dot infrared photodetectors (T-QDIPs), and bi-layer quantum dot infrared photodetectors (Bi-QDIPs); and homo-/heterojunction interfacial workfunction internal photoemission (HIWIP/HEIWIP) structures. QD-based detectors show multi-color characteristics in mid- and far-infrared (MIR/FIR) regions, where as HIWIP/HEIWIP detectors show responses in UV or near-infrared (NIR) regions, and MIR-to-FIR regions. In DWELL structures, InAs QDs are placed in an InGaAs/GaAs quantum well (QW) to introduce photon induced electronic transitions from energy states in the QD to that in QW, leading to multi-color response peaks. One of the DWELL detectors shows response peaks at ∼ 6.25, ∼ 10.5 and ∼ 23.3 µm. In T-QDIP structures, photoexcited carriers are selectively collected from InGaAs QDs through resonant tunneling, while the dark current is blocked using AlGaAs/InGaAsAlGaAs/ blocking barriers placed in the structure. A two-color T-QDIP with photoresponse peaks at 6 and 17 µm operating at room temperature and a 6 THz detector operating at 150 K are presented. Bi-QDIPs consist of two layers of InAs QDs with different QD sizes. The detector exhibits three distinct peaks at 5.6, 8.0, and 23.0 µm. A typical HIWIP/HEIWIP detector structure consists of a single (or series of) doped emitter(s) and undoped barrier(s), which are placed between two highly doped contact layers. The dual-band response arises from interband transitions of carriers in the undoped barrier and intraband transitions in the doped emitter. Two HIWIP detectors, p-GaAs/GaAs and p-Si/Si, showing interband responses with wavelength thresholds at 0.82 and 1.05 µm, and intraband responses with zero response thresholds at 70 and 32 µm, respectively, are presented. HEIWIP detectors based on n-GaN/AlGaN show an interband response in the UV region and intraband response in the 2-14 µm region. A GaN/AlGaN detector structure consisting of three electrical contacts for separate UV and IR active regions is proposed for simultaneous measurements of the two components of the photocurrent generated by UV and IR radiation.

Thesis (Ph. D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2007.
Dr. William T. Rhodes, Committee Co-Chair ; Dr. John Buck, Committee Member ; Dr. William Hunt, Committee Member ; Dr. Stephen P. DeWeerth, Committee Member ; Dr. Ronald G. Driggers, Committee Member ; Dr. Gisele Bennett, Committee Chair.

In this thesis, we demonstrate an array of photodetection theory and techniques bridging the traditional discrete and continuous variable experimental domains. In quantum optics, the creation and measurement of states of light are intertwined and we present experimental architectures considering both aspects. We describe the measurement of mean photon numbers at optical sideband frequencies using homodyne detection. We use our technique to provide a direct comparison to photon-counting measurements and observe that our technique exhibits superior speed, dynamic range and mode selectivity compared to photon counters. Our analysis also rejects a semiclassical description of the vacuum state, with our observations supporting the quantum mechanical model. We create a new means of describing the detection ???signatures??? of multi-port networks of non-photon-number discriminating detectors. Our model includes the practical effects of loss and dark counts. We use this model to analyse the performance of the loopand balanced- time-division-multiplexed detector architectures in a projective measurement role. Our analysis leads us to describe a prescriptive recipe for the optimisation of each architecture. In light of contemporary technology, we conclude the balanced TDM detector is the better architecture. Our analysis is then extended to the tomographic reconstruction of an unknown optical state using multi-port photon-counting networks. Our new approach is successfully applied to the reconstruction of the photon statistics of weak coherent states and demonstrates reduced error and sensitivity to experimental parameter variations than established techniques. We report the development of a source of quadrature squeezed vacuum at 1550 nm, and characterise the squeezing observed at the first 3 free spectral ranges of the downconversion cavity. This is then used as a source of frequency-entangled photons for a projective photon subtraction operation described by our earlier theory. We propose a new hybrid time/frequency domain approach to homodyne detection and illustrate its application in characterising the prepared state. Our output state has a statistically significant single photon contribution and permits future experimentation in frequency basis quantum information.

Growing needs for precise manipulation in medical surgery, manufacturing automation and structural health monitoring have motivated development of high accuracy, bandwidth and cost-effective sensing systems. Among these is a class of multi-axis electromagnetic devices where embedded magnetic fields can be capitalized for compact position estimation eliminating unwanted friction, stiction and inertia arising from dedicated and separate sensing mechanisms. Using fields for position measurements, however, is a challenging 'inverse problem' since they are often modeled in the 'forward' sense and their inverse solutions are often highly non-linear and non-unique. A general method to design a multisensor system that capitalizes on the existing magnetic field in permanent magnet (PM) actuators is presented. This method takes advantage of the structural field symmetry and meticulous placement of sensors to discretize the motion range of a PM-based device into smaller magnetic field segments, thereby reducing the required characterization domain. Within these localized segments, unique field-position correspondence is induced using field measurements from a network of multiple-axis sensors. A direct mapping approach utilizing trained artificial neural networks to attain multi-DOF positional information from distributed field measurements is employed as an alternative to existing computationally intensive model based methods which are unsuitable for real-time control implementation. Validation and evaluation of this technique are performed through field simulations and experimental investigation on an electromagnetic spherical actuator. An inclinometer was used as a performance comparison and experimental results have corroborated the superior tracking ability of the field-based sensing system. While the immediate application is field-based orientation determination of an electromagnetic actuator, it is expected that the design method can be extended to develop other sensing systems that harnesses other scalar, vector and tensor fields.

This dissertation presents system and circuit development of the low-power multi-gigabit CMOS demodulator using analog and mixed demodulation techniques. In addition, critical building blocks of the low-power analog quadrature front-ends are designed and implemented using 90 nm CMOS with a targeted compatibility to the traditional demodulator architecture. It exhibits an IF-to-baseband conversion gain of 25 dB with 1.8 GHz of baseband bandwidth and a dynamic range of 23 dB while consuming only 46 mW from a 1 V supply voltage. Several different demodulators using analog signal processor (ASP) are implemented: (1) an ultra-low power non-coherent ASK demodulator is measured to demodulate a maximum speed of 3 Gbps while consuming 32 mW from 1.8 V supply; (2) a mere addition of 7.5 mW to the aforementioned analog quadrature front-end enables a maximum speed of 2.5 Gbps non-coherent ASK demodulation with an improved minimum sensitivity of -38 dBm; (3) a robust coherent BPSK demodulator is shown to achieve a maximum speed of 3.5 Gbps based on the same analog quadrature front-end with only additional 7 mW. Furthermore, an innovative seamless handover mechanism between ASP and PLL is designed and implemented to improve the frequency acquisition time of the coherent BPSK demodulator. These demodulator designs have been proven to be feasible and are integrated in a 60 GHz wireless receiver. The system has been realized in a product prototype and used to stream HD video as well as transfer large multi-media files at multi-gigabit speed.

Maximum-likelihood estimation or other probabilistic estimation methods are underused in many areas of applied gamma-ray imaging, particularly in biomedicine. In this work, we show how to use our understanding of stochastic processes in a scintillation camera and their effect on signal formation to better estimate gamma-ray interaction parameters such as interaction position or energy.To apply statistical estimation methods, we need an accurate description of the signal statistics as a function of the parameters to be estimated. First, we develop a probability model of the signals conditioned on the parameters to be estimated by carefully examining the signal generation process. Subsequently, the likelihood model is calibrated by measuring signal statistics for an ensemble of events as a function of the estimate parameters.In this work, we investigate the application of ML-estimation methods for three topics. First, we design, build, and evaluate a scintillation camera based on a multi-anode PMT readout for use with ML-estimation techniques. Next, we develop methods for calibrating the response statistics of a thick-detector gamma camera as a function of interaction depth. Finally, we demonstrate the use of ML estimation with a modified clinical Anger camera.

Les ensembles de détecteurs de rayon gamma de nouvelle génération, tel AGATA, utilisent des détecteurs multi-segmentés de germanium hyper-pur dans les expériences de physique nucléaire pour lesquelles une grande résolution et efficacité sont demandées. Ces caractéristiques sont obtenues par l’application des techniques d'analyse des formes d'impulsion et de tracking des rayons gamma. Ces dernières demandent une caractérisation volumétrique des détecteurs. À cet effet, l'IPHC a développé une table de scan qui utilise la technique Pulse Shape Comparison Scan (PSCS). Des simulations sont réalisées pour quantifier la précision de la technique PSCS et pour la valider. Elles sont appliquées sur un détecteur planaire pixelisé 3x3 et sur un détecteur symétrique d'AGATA de type S. La méthode est testée avec plusieurs énergies de rayons gamma et diverses statistiques d'entrée. Des scans réels sont aussi entrepris sur les deux détecteurs, qui sont totalement caractérisés. En particulier, un scan réalisé pour la première fois avec une source de rayons gamma de 152Eu, prouve la validité de certaines hypothèses sur lesquelles repose la technique de tracking
New generation gamma-ray detectors arrays, such as AGATA, employ multi-segmented high purity germanium detectors in experiments of nuclear physics that require high resolution and efficiency which are obtained thanks to the application of pulse-shape analysis and gamma-ray tracking. These techniques require full volume characterization of the position sensitive detectors. The IPHC developed a scanning table that uses the Pulse Shape Comparison Scan (PSCS) technique to perform this task. Simulations are performed to quantify the accuracy of the PSCS and to validate it.They are applied on a pixelated 3x3 planar detector and a symmetrical S-type AGATA detector. The method is tested with different gamma-ray energies and input statistics. Several real scans are performed as well on both detectors, which are fully characterized. In particular a scan with agamma-ray source of 152Eu, the first ever done, prove some assumptions on which the tracking technique is based

Mobile sensor networks have been shown to be a powerful tool for enabling a number of activities that require recording of environmental parameters at various spatial and temporal distributions. These mobile sensor networks could be implemented using a team of robots, usually called robotic sensor networks. This type of sensor network involves the coordinated control of multiple robots to achieve specific measurements separated by varied distances. In most formation measurement applications, initialization involves identifying a number of interesting sites to which mobility platforms, instrumented with a variety of sensors, are tasked. This process of determining which instrumented robot should be tasked to which location can be viewed as solving the task allocation problem. Unfortunately, a centralized approach does not fit in this type of application due to the fault tolerance requirements. Moreover, as the size of the network grows, limitations in bandwidth severely limits the possibility of conveying and using global information. As such, the utilization of decentralized techniques for forming new sensor topologies and configurations is a highly desired quality of robotic sensor networks. In this thesis, several distributed task allocation algorithms will be explained and compared in different scenarios. They are based on a market approach since our interest is not only to obtain a feasible solution, but also an efficient one. Also, an analysis of the efficiency of those algorithms using probabilistic techniques will be explained. Finally, the task allocation algorithms will be implemented on a real system consisted of a team of six robots and integrated in a complete robotic system that considers obstacle avoidance and path planning. The results will be validated in both simulations and real experiments.

Thesis (M.S.)--Kent State University, 2007.
Title from PDF t.p. (viewed Mar. 19, 2009). Advisor: Michael Rothstein. Keywords: intrusion detection systems, immune system, immune detectors, intrusion detection squad, multi-agent system. Includes bibliographical references (p. 62-66).

The objective of the research is to develop high-speed ADCs and mixed-signal demodulator for multi-gigabit communication systems using millimeter-wave frequency bands in standard CMOS technology. With rapid advancements in semiconductor technologies, mobile communication devices have become more versatile, portable, and inexpensive over the last few decades. However, plagued by the short lifetime of batteries, low power consumption has become an extremely important specification in developing mobile communication devices. The ever-expanding demand of consumers to access and share information ubiquitously at faster speeds requires higher throughputs, increased signal-processing functionalities at lower power and lower costs. In today’s technology, high-speed signal processing and data converters are incorporated in almost all modern multi-gigabit communication systems. They are key enabling technologies for scalable digital design and implementation of baseband signal processors. Ultimately, the merits of a high performance mixed-signal receiver, such as data rate, sensitivity, signal dynamic range, bit-error rate, and power consumption, are directly related to the quality of the embedded ADCs. Therefore, this dissertation focuses on the analysis and design of high-speed ADCs and a novel broadband mixed-signal demodulator with a fully-integrated DSP composed of low-cost CMOS circuitry. The proposed system features a novel dual-mode solution to demodulate multi-gigabit BPSK and ASK signals. This approach reduces the resolution requirement of high-speed ADCs, while dramatically reducing its power consumption for multi-gigabit wireless communication systems.

Thesis (M.S.)--Worcester Polytechnic Institute.
Keywords: basis functions; perfectly matched layers; PML; neck model; parallel plate resonator; finite element; circulator; glottal waveform; multi-transmission line; dielectric properties of human tissues; radiation currents; weighted residuals; non-acoustic sensor. Includes bibliographical references (p. 104-107).

Over the last decade, substantial research efforts have been dedicated towards the development of advanced laser scanning systems for discrimination in perimeter security, defence, agriculture, transportation, surveying and geosciences. Military forces, in particular, have already started employing laser scanning technologies for projectile guidance, surveillance, satellite and missile tracking; and target discrimination and recognition. However, laser scanning is relatively a new security technology. It has previously been utilized for a wide variety of civil and military applications. Terrestrial laser scanning has found new use as an active optical sensor for indoors and outdoors perimeter security. A laser scanning technique with moving parts was tested in the British Home Office - Police Scientific Development Branch (PSDB) in 2004. It was found that laser scanning has the capability to detect humans in 30m range and vehicles in 80m range with low false alarm rates. However, laser scanning with moving parts is much more sensitive to vibrations than a multi-beam stationary optic approach. Mirror device scanners are slow, bulky and expensive and being inherently mechanical they wear out as a result of acceleration, cause deflection errors and require regular calibration. Multi-wavelength laser scanning represent a potential evolution from object detection to object identification and classification, where detailed features of objects and materials are discriminated by measuring their reflectance characteristics at specific wavelengths and matching them with their spectral reflectance curves. With the recent advances in the development of high-speed sensors and high-speed data processors, the implementation of multi-wavelength laser scanners for object identification has now become feasible. A two-wavelength photonic-based sensor for object discrimination has recently been reported, based on the use of an optical cavity for generating a laser spot array and maintaining adequate overlapping between tapped collimated laser beams of different wavelengths over a long optical path. While this approach is capable of discriminating between objects of different colours, its main drawback is the limited number of security-related objects that can be discriminated. This thesis proposes and demonstrates the concept of a novel photonic based multi-wavelength sensor for object identification and position finding. The sensor employs a laser combination module for input wavelength signal multiplexing and beam overlapping, a custom-made curved optical cavity for multi-beam spot generation through internal beam reflection and transmission and a high-speed imager for scattered reflectance spectral measurements. Experimental results show that five different laser wavelengths, namely 473nm, 532nm, 635nm, 670nm and 785nm, are necessary for discriminating various intruding objects of interest through spectral reflectance and slope measurements. Various objects were selected to demonstrate the proof of concept. We also demonstrate that the object position (coordinates) is determined using the triangulation method, which is based on the projection of laser spots along determined angles onto intruding objects and the measurement of their reflectance spectra using an image sensor. Experimental results demonstrate the ability of the multi-wavelength spectral reflectance sensor to simultaneously discriminate between different objects and predict their positions over a 6m range with an accuracy exceeding 92%. A novel optical design is used to provide additional transverse laser beam scanning for the identification of camouflage materials. A camouflage material is chosen to illustrate the discrimination capability of the sensor, which has complex patterns within a single sample, and is successfully detected and discriminated from other objects over a 6m range by scanning the laser beam spots along the transverse direction. By using more wavelengths at optimised points in the spectrum where different objects show different optical characteristics, better discrimination can be accomplished.

La prochaine génération d’instruments pour l'observation de la polarisation du fond diffus cosmologique est particulièrement exigeante en termes de nombre de détecteurs, de qualité de la mesure et d'efficacité de remplissage du plan focal. De plus, pour détecter les modes-B de polarisation provenant de l’inflation, il faut observer le ciel avec plusieurs bandes de fréquence afin de soustraire les avant-plans. Dans ce contexte, les détecteurs à inductance cinétique (KIDs) représentent une technologie très prometteuse en raison de leur grand facteur de multiplexage et de leur facilité de réalisation, tandis que le couplage avec une antenne peut fournir des solutions multi-bandes et double-polarisation dans un design compacte. Les KIDs à éléments localisés (LEKID) couplé à une antenne développé dans cette thèse sont sensibles à la polarisation avec deux sous-bandes à 140 GHz et 160 GHz chacune avec une bande passante de 10%. L'architecture proposée utilise une antenne à fente excitée par une ligne microruban et deux filtres passe-bande vers deux résonateurs. Ces derniers sont couplés capacitivement avec l'antenne et comprennent une ligne microruban en Aluminium comme absorbeur. Cette architecture est particulièrement simple à fabriquer, sans via et ne nécessite que de deux niveaux de métallisation. La transition ne nécessite aucun dépôt de diélectrique au-dessus du résonateur, évitant ainsi les limitations de toute source de bruit due au substrat non-monocristallin (TLS). En outre, la même technique de couplage peut être appliquée à de nombreux types d'antennes excitées par une ligne microruban, ce qui permet de s'adapter aux filtres passe-bande
Next generation telescopes for observing the Cosmic Microwave Background are demanding in terms of number of detectors and focal plane area filling efficiency. Moreover, foreground reduction in B-Mode polarimetry requires sky observation with multiple frequency bands. In this context KIDs are promising technology because of their large multiplexing rate, while antenna coupling can provide multi-band and dual-polarization solutions in compact design. The proposed polarization sensitive antenna-coupled LEKID is operating at 140 GHz and 160 GHz with a bandwidth of almost 10% for each sub-band. The design involves a microstrip excited slot antenna and two open-stub band-pass filters to direct the signal toward two resonators. These are lumped elements capacitively coupled to the antenna and include an Aluminium strip as absorber. The architecture proposed is particularly simple to fabricate, via-less and only involves two metallization levels. The transition doesn't require any dielectric deposition above the resonator, thus preventing limitations from any source of noise due to non-monocrystalline substrate (TLS). Furthermore, the same coupling technique can be applied to many types of microstrip excited antennas, which allow to accommodate band-pass filters

Le Dispositif d'Irradiation d'Agrégats Moléculaires (DIAM) est conçu pour l'étude de mécanismes de dissociation résultant de l'interaction de nanosystèmes moléculaires avec des protons de 20-150 keV. Une technique originale de spectrométrie de masse appelée COINTOF (Correlated Ion and Neutral Time Of Flight) permet la mesure corrélée du temps de vol des fragments neutres et chargés issus de la dissociation d'un système moléculaire sélectionné en masse. Une stratégie de traitement des signaux a été développée afin de pouvoir distinguer des fragments proches en temps (< 1ns). Les données collectées sont structurées dans le logiciel ROOT® pour l'analyse statistique des corrélations. Le fonctionnement de la technique COINTOF est illustré par des expériences de dissociation induite par collision d'agrégats d'eau protonés sur une cible gazeuse. La méthodologie d'analyse des données est exposée à travers l'étude du canal de dissociation du trimère d'eau protoné produisant l'ion chargé H3O+ et deux molécules d'eau. La distribution de la différence de temps de vol entre les deux fragments neutres est mesurée, mettant en évidence une énergie libérée de quelques eV. En parallèle, un second spectromètre de masse à temps de vol adapté à l'évolution du dispositif a été développé. Il associe un temps de vol linéaire et un temps de vol orthogonal et intègre un détecteur à position (ligne à retard). Des simulations ont démontré les potentialités du nouvel analyseur. Enfin, des travaux ont été menés au laboratoire R.-J. A. Lévesque (Université de Montréal) portant sur les capacités d'imagerie de détecteurs à position multi-pixel de la collaboration MPX-ATLAS.

Scale-invariant interest points have found several highly successful applications in computer vision, in particular for image-based matching and recognition. This paper presents a theoretical analysis of the scale selection properties of a generalized framework for detecting interest points from scale-space features presented in Lindeberg (Int. J. Comput. Vis. 2010, under revision) and comprising: an enriched set of differential interest operators at a fixed scale including the Laplacian operator, the determinant of the Hessian, the new Hessian feature strength measures I and II and the rescaled level curve curvature operator, as well as an enriched set of scale selection mechanisms including scale selection based on local extrema over scale, complementary post-smoothing after the computation of non-linear differential invariants and scale selection based on weighted averaging of scale values along feature trajectories over scale. A theoretical analysis of the sensitivity to affine image deformations is presented, and it is shown that the scale estimates obtained from the determinant of the Hessian operator are affine covariant for an anisotropic Gaussian blob model. Among the other purely second-order operators, the Hessian feature strength measure I has the lowest sensitivity to non-uniform scaling transformations, followed by the Laplacian operator and the Hessian feature strength measure II. The predictions from this theoretical analysis agree with experimental results of the repeatability properties of the different interest point detectors under affine and perspective transformations of real image data. A number of less complete results are derived for the level curve curvature operator.

QC 20121003

Image descriptors and scale-space theory for spatial and spatio-temporal recognition

The Large Ultraviolet/Optical/Infrared Surveyor (LUVOIR) is one of four large mission concepts currently undergoing community study for consideration by the 2020 Astronomy and Astrophysics Decadal Survey. LUVOIR is being designed to pursue an ambitious program of exoplanetary discovery and characterization, cosmic origins astrophysics, and planetary science. The LUVOIR study team is investigating two large telescope apertures (9- and 15-meter primary mirror diameters) and a host of science instruments to carry out the primary mission goals. Many of the exoplanet, cosmic origins, and planetary science goals of LUVOIR require high-throughput, imaging spectroscopy at ultraviolet (100 - 400 nm) wavelengths. The LUVOIR Ultraviolet Multi-Object Spectrograph, LUMOS, is being designed to support all of the UV science requirements of LUVOIR, from exoplanet host star characterization to tomography of circumgalactic halos to water plumes on outer solar system satellites. LUMOS offers point source and multi-object spectroscopy across the UV bandpass, with multiple resolution modes to support different science goals. The instrument will provide low (R = 8,000 - 18,000) and medium (R = 30,000 - 65,000) resolution modes across the far-ultraviolet (FUV: 100 - 200 nm) and near-ultraviolet (NUV: 200 - 400 nm) windows, and a very low resolution mode (R = 500) for spectroscopic investigations of extremely faint objects in the FUV. Imaging spectroscopy will be accomplished over a 3 x 1.6 arcminute field-of-view by employing holographically-ruled diffraction gratings to control optical aberrations, microshutter arrays (MSA) built on the heritage of the Near Infrared Spectrograph (NIRSpec) on the James Webb Space Telescope (JWST), advanced optical coatings for high-throughput in the FUV, and next generation large-format photon-counting detectors. The spectroscopic capabilities of LUMOS are augmented by an FUV imaging channel (100 - 200nm, 13 milliarcsecond angular resolution, 2 x 2 arcminute field-of-view) that will employ a complement of narrow-and medium-band filters. The instrument definition, design, and development are being carried out by an instrument study team led by the University of Colorado, Goddard Space Flight Center, and the LUVOIR Science and Technology Definition Team. LUMOS has recently completed a preliminary design in Goddard's Instrument Design Laboratory and is being incorporated into the working LUVOIR mission concept. In this proceeding, we describe the instrument requirements for LUMOS, the instrument design, and technology development recommendations to support the hardware required for LUMOS. We present an overview of LUMOS' observing modes and estimated performance curves for effective area, spectral resolution, and imaging performance. Example "LUMOS 100-hour Highlights" observing programs are presented to demonstrate the potential power of LUVOIR's ultraviolet spectroscopic capabilities.

Detectors and sensors are an integral part of modern electronics and are crucial to highly sensitive applications. Metal-Insulator-Metal (MIM) tunnel junctions have been explored for the past five decades and are still being investigated due to its wide use of applications such as mixers, capacitors, detectors, rectifiers and energy conversion devices. In this research, various designs of thin film based tunnel junctions have been investigated and the optimum one picked for the purpose of a wide band detector up to 10GHz based on their sensitivities. A modified design with an isolation layer incorporating a self-aligning method to increase fabrication throughput was developed. A mask for the reliability testing of multiple devices with different areas was also developed. Nickel Oxide based insulators with different stoichiometries have been incorporated in the fabrication of the device to identify which stoichiometry gives the best performance for high frequency applications. Nickel Oxide (NiO), Zinc Oxide (ZnO) and the combination of the two have been deposited using reactive sputtering and investigated as insulator materials. The bilayer devices showed increased sensitivities at lower turn on voltages and very good efficiencies at 100MHz and 1GHz. Although, the MIM device provides a simple structure, some of the critical parameters required to quantify the device functionality are still being explored. Based on the parameters, a criterion was developed to help engineer a tunnel device for a desired detectivity.

Analytical ultracentrifugation (AUC) has made an important contribution to polymer and particle characterization since its invention by Svedberg (Svedberg and Nichols 1923; Svedberg and Pederson 1940) in 1923. In 1926, Svedberg won the Nobel price for his scientific work on disperse systems including work with AUC. The first important discovery performed with AUC was to show the existence of macromolecules. Since that time AUC has become an important tool to study polymers in biophysics and biochemistry. AUC is an absolute technique that does not need any standard. Molar masses between 200 and 1014 g/mol and particle size between 1 and 5000 nm can be detected by AUC. Sample can be fractionated into its components due to its molar mass, particle size, structure or density without any stationary phase requirement as it is the case in chromatographic techniques. This very property of AUC earns it an important status in the analysis of polymers and particles. The distribution of molar mass, particle sizes and densities can be measured with the fractionation. Different types of experiments can give complementary physicochemical parameters. For example, sedimentation equilibrium experiments can lead to the study of pure thermodynamics. For complex mixtures, AUC is the main method that can analyze the system. Interactions between molecules can be studied at different concentrations without destroying the chemical equilibrium (Kim et al. 1977). Biologically relevant weak interactions can also be monitored (K ≈ 10-100 M-1). An analytical ultracentrifuge experiment can yield the following information: • Molecular weight of the sample • Number of the components in the sample if the sample is not a single component • Homogeneity of the sample • Molecular weight distribution if the sample is not a single component • Size and shape of macromolecules & particles • Aggregation & interaction of macromolecules • Conformational changes of macromolecules • Sedimentation coefficient and density distribution Such an extremely wide application area of AUC allows the investigation of all samples consisting of a solvent and a dispersed or dissolved substance including gels, micro gels, dispersions, emulsions and solutions. Another fact is that solvent or pH limitation does not exist for this method. A lot of new application areas are still flourishing, although the technique is 80 years old. In 1970s, 1500 AUC were operational throughout the world. At those times, due to the limitation in detection technologies, experimental results were obtained with photographic records. As time passed, faster techniques such as size exclusion chromatography (SEC), light scattering (LS) or SDS-gel electrophoresis occupied the same research fields with AUC. Due to these relatively new techniques, AUC began to loose its importance. In the 1980s, only a few AUC were in use throughout the world. In the beginning of the 1990s a modern AUC -the Optima XL-A - was released by Beckman Instruments (Giebeler 1992). The Optima XL-A was equipped with a modern computerized scanning absorption detector. The addition of Rayleigh Interference Optics is introduced which is called XL-I AUC. Furthermore, major development in computers made the analysis easier with the help of new analysis software. Today, about 400 XL-I AUC exist worldwide. It is usually applied in the industry of pharmacy, biopharmacy and polymer companies as well as in academic research fields such as biochemistry, biophysics, molecular biology and material science. About 350 core scientific publications which use analytical ultracentrifugation are published every year (source: SciFinder 2008 ) with an increasing number of references (436 reference in 2008). A tremendous progress has been made in method and analysis software after digitalization of experimental data with the release of XL-I. In comparison to the previous decade, data analysis became more efficient and reliable. Today, AUC labs can routinely use sophisticated data analysis methods for determination of sedimentation coefficient distributions (Demeler and van Holde 2004; Schuck 2000; Stafford 1992), molar mass distributions (Brookes and Demeler 2008; Brookes et al. 2006; Brown and Schuck 2006), interaction constants (Cao and Demeler 2008; Schuck 1998; Stafford and Sherwood 2004), particle size distributions with Angstrom resolution (Cölfen and Pauck 1997) and the simulations determination of size and shape distributions from sedimentation velocity experiments (Brookes and Demeler 2005; Brookes et al. 2006). These methods are also available in powerful software packages that combines various methods, such as, Ultrascan (Demeler 2005), Sedift/Sedphat (Schuck 1998; Vistica et al. 2004) and Sedanal (Stafford and Sherwood 2004). All these powerful packages are free of charge. Furthermore, Ultrascans source code is licensed under the GNU Public License (http://www.gnu.org/copyleft/gpl.html). Thus, Ultrascan can be further improved by any research group. Workshops are organized to support these software packages. Despite of the tremendous developments in data analysis, hardware for the system has not developed much. Although there are various user developed detectors in research laboratories, they are not commercially available. Since 1992, only one new optical system called “the fluorescence optics” (Schmidt and Reisner, 1992, MacGregor et al. 2004, MacGregor, 2006, Laue and Kroe, in press) has been commercialized. However, except that, there has been no commercially available improvement in the optical system. The interesting fact about the current hardware of the XL-I is that it is 20 years old, although there has been an enormous development in microelectronics, software and in optical systems in the last 20 years, which could be utilized for improved detectors. As examples of user developed detector, Bhattacharyya (Bhattacharyya 2006) described a Multiwavelength-Analytical Ultracentrifuge (MWL-AUC), a Raman detector and a small angle laser light scattering detector in his PhD thesis. MWL-AUC became operational, but a very high noise level prevented to work with real samples. Tests with the Raman detector were not successful due to the low light intensity and thus high integration time is required. The small angle laser light scattering detector could only detect latex particles but failed to detect smaller particles and molecules due to low sensitivity of the detector (a photodiode was used as detector). The primary motivation of this work is to construct a detector which can measure new physico-chemical properties with AUC with a nicely fractionated sample in the cell. The final goal is to obtain a multiwavelength detector for the AUC that measures complementary quantities. Instrument development is an option for a scientist only when there is a huge potential benefit but there is no available commercial enterprise developing appropriate equipment, or if there is not enough financial support to buy it. The first case was our motivation for developing detectors for AUC. Our aim is to use today’s technological advances in microelectronics, programming, mechanics in order to develop new detectors for AUC and improve the existing MWL detector to routine operation mode. The project has multiple aspects which can be listed as mechanical, electronical, optical, software, hardware, chemical, industrial and biological. Hence, by its nature it is a multidisciplinary project. Again by its nature it contains the structural problem of its kind; the problem of determining the exact discipline to follow at each new step. It comprises the risk of becoming lost in some direction. Having that fact in mind, we have chosen the simplest possible solution to any optical, mechanical, electronic, software or hardware problem we have encountered and we have always tried to see the overall picture. In this research, we have designed CCD-C-AUC (CCD Camera UV/Vis absorption detector for AUC) and SLS-AUC (Static Light Scattering detector for AUC) and tested them. One of the SLS-AUC designs produced successful test results, but the design could not be brought to the operational stage. However, the operational state Multiwavelength Analytical Ultracentrifuge (MWL-AUC) AUC has been developed which is an important detector in the fields of chemistry, biology and industry. In this thesis, the operational state Multiwavelength Analytical Ultracentrifuge (MWL-AUC) AUC is to be introduced. Consequently, three different applications of MWL-AUC to the aforementioned disciplines shall be presented. First of all, application of MWL-AUC to a biological system which is a mixture of proteins lgG, aldolase and BSA is presented. An application of MWL-AUC to a mass-produced industrial sample (β-carotene gelatin composite particles) which is manufactured by BASF AG, is presented. Finally, it is shown how MWL-AUC will impact on nano-particle science by investigating the quantum size effect of CdTe and its growth mechanism. In this thesis, mainly the relation between new technological developments and detector development for AUC is investigated. Pioneering results are obtained that indicate the possible direction to be followed for the future of AUC. As an example, each MWL-AUC data contains thousands of wavelengths. MWL-AUC data also contains spectral information at each radial point. Data can be separated to its single wavelength files and can be analyzed classically with existing software packages. All the existing software packages including Ultrascan, Sedfit, Sedanal can analyze only single wavelength data, so new extraordinary software developments are needed. As a first attempt, Emre Brookes and Borries Demeler have developed mutliwavelength module in order to analyze the MWL-AUC data. This module analyzes each wavelength separately and independently. We appreciate Emre Brookes and Borries Demeler for their important contribution to the development of the software. Unfortunately, this module requires huge amount of computer power and does not take into account the spectral information during the analysis. New software algorithms are needed which take into account the spectral information and analyze all wavelengths accordingly. We would like also invite the programmers of Ultrascan, Sedfit, Sedanal and the other programs, to develop new algorithms in this direction.
Die analytische Chemie versucht die chemische Zusammensetzung, chemische und physikalische Eigenschaften von biologischen oder künstlichen Materialien zu bestimmen. Mit der Entwicklung deren Methoden können genauere Informationen über die Umweltverschmutzung, das Ozonloch, Proteinfunktionen und Wechselwirkungen im menschlichen Körper erlangt werden. Es sind eine Vielzahl von analytischen Techniken vorhanden, die durch Verbesserungen in der Mikroelektronik, Mechanik, Informatik und Nanotechnologie einer markanten Entwicklung unterworfen wurden. In dieser Arbeit wurde versucht die Detektionskapazität der analytischen Ultrazentrifuge zu erhöhen. Die analytische Ultrazentrifuge (AUZ) ist eine gut bekannte, sehr leistungsstarke Trennungsmethode. AUZ benutzt die Zentrifugalkraft zum Trennen von Stoffen. Die Probe kann für die Messung gelöst oder in einer Flüssigkeit dispergiert werden. Makromoleküle, Proteine und kolloidale Systeme in Lösung können in einer AUZ Zelle zwischen 1000-60000 Rotationen pro Minute zentrifugiert werden, wie beispielsweise in der kommerziellen Beckmann AUZ. Die Rotationsbeschleunigung entspricht 73-262mal der Erdschwerebeschleunigung (= 9.81 m s-2) für eine radiale Position von 6.5 Zentimeter. Diese Kraft ist der Schlüsselfaktor für die Fähigkeit der AUZ sogar kleine Moleküle und Ionen zu trennen. Die Experimente wurden bei kontrollierter Rotationsgeschwindigkeit und Temperatur ausgeführt. Drei verschiedene, neue Detektoren wurden im Rahmen dieser Arbeit konstruiert und getestet. Diese Detektoren haben die analytischen Informationen sehr verbessert. Dies wurde für Proteine, halbleitende Nanopartikel sowie auch für industrielle Produkte gezeigt.

Modern civil structures as well as loads on them are still too complex to be accurately modeled or simulated. Therefore, structural failures and structural defects are NOT uncommon! More and more full-scale structural monitoring systems have been deployed in order to monitor how structures behave under various loading conditions. This research focuses on how to maximise benefits from such full-scale measurements by employing advanced digital signal processing techniques. This study is based on accelerometer and GPS data collected on three very different structures, namely, the steel tower in Tokyo, the long and slender suspension bridge in Hong Kong, and the tall office tower in Sydney, under a range of loading conditions, i.e., typhoon, earthquake, heavy traffic, and small scale wind. Systematic analysis of accelerometer and GPS data has demonstrated that the two sensors complement each other in monitoring the static, quasi-static and dynamic movements of the structures. It has also been confirmed that the Finite Element Model could under-estimate the natural frequencies of structures by more than 40% in some case. The effectiveness of using wavelet to de-noise GPS measurement has been demonstrated. The weakness and strengths of accelerometer and GPS have been identified and framework has been developed on how to integrate the two as well as how to optimize the integration. The three-dimensional spectral analysis framework has been developed which can track the temporal evolution of all the frequency components and effectively represents the result in the 3D spectrogram of frequency, time and magnitude. The dominant frequency can also be tracked on the 3D mesh to vividly illustrate the damping signature of the structure. The frequency domain coherent analysis based on this 3D analysis framework can further enhance the detection of common signals between sensors. The developed framework can significantly improve the visualized performance of the integrated system without increasing hardware costs. Indoor experiments have shown the excellent characteristics of the optical fibre Bragg gratings (FBGs) for deformation monitoring. Innovative and low-cost approach has been developed to measure the shift of FBG???s central wavelength. Furthermore, a schematic design has been completed to multiplex FBGs in order to enable distributed monitoring. In collaboration with the University of Sydney, the first Australian full-scale structural monitoring system of GPS and accelerometer has been deployed on the Latitude Tower in Sydney to support current and future research.

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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Trends toward increased integration and miniaturization of optical system components have created pressure to consolidate widely disparate analog and digital functions onto fewer and fewer chips with a goal of eventually built into a single mixed-signal chip. Yet, because of those performance requirements, the frontend circuit has traditionally used III-V compound semiconductor technologies, but the low-level of integration with other digital ICs limits the sustainability of such end products for short-distance applications. On the other hand, their CMOS counter parts, despite having such advantages as low power consumption, high yield that lowers the cost of fabrication, and a higher degree of integration, have not performed well enough to survive in such a noisy environment without sacrificing other important attributes. In this research, a high-speed CMOS preamplifier was designed and fabricated through TSMC 0.18/spl mu/m mixed-signal non-epi CMOS technology, and a 20/spl mu/m diameter InGaAs thin-film Inverted-MSM photodetector with a responsivity of 0.15A/W at a wavelength of 1550/spl mu/m was post-integrated onto the circuit. The circuit has a overall transimpedance gain of 60dB/spl Omega/, and bit-error-rate data and eye-diagram measurement results taken as high as 10Gbit/s are reported in this dissertation.

La localisation précise constitue une brique essentielle permettant aux véhicules de naviguer de manière autonome sur la route. Cela peut être atteint à travers les capteurs déjà existants, de nouvelles technologies (Iidars, caméras intelligentes) et des cartes haute définition. Dans ce travail, l'intérêt d'enregistrer et réutiliser des informations sauvegardées en mémoire est exploré. Les systèmes de localisation doivent permettre une estimation à haute fréquence, des associations de données, de la calibration et de la détection d'erreurs. Une architecture composée de plusieurs couches de traitement est proposée et étudiée. Une couche principale de filtrage estime la pose tandis que les autres couches abordent les problèmes plus complexes. L'estimation d'état haute fréquence repose sur des mesures proprioceptives. La calibration du système est essentielle afin d'obtenir une pose précise. En gardant les états estimés et les observations en mémoire, les modèles d'observation des capteurs peuvent être calibrés à partir des estimations lissées. Les Iidars et les caméras intelligentes fournissent des mesures qui peuvent être utilisées pour la localisation mais soulèvent des problèmes d'association de données. Dans cette thèse, le problème est abordé à travers une fenêtre spatio-temporelle, amenant une image plus détaillée de l'environnement. Le buffer d'états est ajusté avec les observations et toutes les associations possibles. Bien que l'utilisation d'amers cartographiés permette d'améliorer la localisation, cela n'est possible que si la carte est fiable. Une approche utilisant les résidus lissés a posteriori a été développée pour détecter ces changements de carte
Localization is an essential basic capability for vehicles to be able to navigate autonomously on the road. This can be achieved through already available sensors and new technologies (Iidars, smart cameras). These sensors combined with highly accurate maps result in greater accuracy. In this work, the benefits of storing and reusing information in memory (in data buffers) are explored. Localization systems need to perform a high-frequency estimation, map matching, calibration and error detection. A framework composed of several processing layers is proposed and studied. A main filtering layer estimates the vehicle pose while other layers address the more complex problems. High-frequency state estimation relies on proprioceptive measurements combined with GNSS observations. Calibration is essential to obtain an accurate pose. By keeping state estimates and observations in a buffer, the observation models of these sensors can be calibrated. This is achieved using smoothed estimates in place of a ground truth. Lidars and smart cameras provide measurements that can be used for localization but raise matching issues with map features. In this work, the matching problem is addressed on a spatio-temporal window, resulting in a more detailed pictur of the environment. The state buffer is adjusted using the observations and all possible matches. Although using mapped features for localization enables to reach greater accuracy, this is only true if the map can be trusted. An approach using the post smoothing residuals has been developed to detect changes and either mitigate or reject the affected features

Les systèmes robotiques modulaires (MRS) font aujourd’hui l’objet de recherches très actives. Ils ont la capacité de changer la perspective des systèmes robotiques, passant de machines conçues pour effectuer certaines tâches à des outils polyvalents capables d'accomplir presque toutes les tâches. Ils sont utilisés dans un large éventail d'applications, notamment la reconnaissance, les missions de sauvetage, l'exploration spatiale, les tâches militaires, etc. Constamment, MRS est constitué de "modules" allant de quelques à plusieurs centaines, voire milliers. Chaque module implique des actionneurs, des capteurs, des capacités de calcul et de communication. Habituellement, ces systèmes sont homogènes où tous les modules sont identiques ; cependant, il pourrait y avoir des systèmes hétérogènes contenant différents modules pour maximiser la polyvalence. L’un des avantages de ces systèmes est leur capacité à fonctionner dans des environnements difficiles dans lesquels les schémas de travail contemporains avec intervention humaine sont risqués, inefficaces et parfois irréalisables. Dans cette thèse, nous nous intéressons à la robotique modulaire auto-reconfigurable. Dans de tels systèmes, il utilise un ensemble de détecteurs afin de détecter en permanence son environnement, de localiser sa propre position, puis de se transformer en une forme spécifique pour effectuer les tâches requises. Par conséquent, MRS est confronté à trois défis majeurs. Premièrement, il offre une grande quantité de données collectées qui surchargent la mémoire de stockage du robot. Deuxièmement, cela génère des données redondantes qui compliquent la prise de décision concernant la prochaine morphologie du contrôleur. Troisièmement, le processus d'auto-reconfiguration nécessite une communication massive entre les modules pour atteindre la morphologie cible et prend un temps de traitement important pour auto-reconfigurer le robot. Par conséquent, les stratégies des chercheurs visent souvent à minimiser la quantité de données collectées par les modules sans perte considérable de fidélité. Le but de cette réduction est d'abord d'économiser de l'espace de stockage dans le MRS, puis de faciliter l'analyse des données et la prise de décision sur la morphologie à utiliser ensuite afin de s'adapter aux nouvelles circonstances et d'effectuer de nouvelles tâches. Dans cette thèse, nous proposons un mécanisme efficace de traitement de données et de prise de décision auto-reconfigurable dédié aux systèmes robotiques modulaires. Plus spécifiquement, nous nous concentrons sur la réduction du stockage de données, la prise de décision d'auto-reconfiguration et la gestion efficace des communications entre les modules des MRS dans le but principal d'assurer un processus d'auto-reconfiguration rapide
Modular robotic systems (MRSs) have become a highly active research today. It has the ability to change the perspective of robotic systems from machines designed to do certain tasks to multipurpose tools capable of accomplishing almost any task. They are used in a wide range of applications, including reconnaissance, rescue missions, space exploration, military task, etc. Constantly, MRS is built of “modules” from a few to several hundreds or even thousands. Each module involves actuators, sensors, computational, and communicational capabilities. Usually, these systems are homogeneous where all the modules are identical; however, there could be heterogeneous systems that contain different modules to maximize versatility. One of the advantages of these systems is their ability to operate in harsh environments in which contemporary human-in-the-loop working schemes are risky, inefficient and sometimes infeasible. In this thesis, we are interested in self-reconfigurable modular robotics. In such systems, it uses a set of detectors in order to continuously sense its surroundings, locate its own position, and then transform to a specific shape to perform the required tasks. Consequently, MRS faces three major challenges. First, it offers a great amount of collected data that overloads the memory storage of the robot. Second it generates redundant data which complicates the decision making about the next morphology in the controller. Third, the self reconfiguration process necessitates massive communication between the modules to reach the target morphology and takes a significant processing time to self-reconfigure the robotic. Therefore, researchers’ strategies are often targeted to minimize the amount of data collected by the modules without considerable loss in fidelity. The goal of this reduction is first to save the storage space in the MRS, and then to facilitate analyzing data and making decision about what morphology to use next in order to adapt to new circumstances and perform new tasks. In this thesis, we propose an efficient mechanism for data processing and self-reconfigurable decision-making dedicated to modular robotic systems. More specifically, we focus on data storage reduction, self-reconfiguration decision-making, and efficient communication management between modules in MRSs with the main goal of ensuring fast self-reconfiguration process

The objective of this research is to present a low power modem technology for a high speed millimeter wave wireless system. The first part of the research focuses on a robust ASIC design methodology. There are several aspects of the ASIC flow that require special attention such as logical synthesis, timing driven physical placement, Clock Tree Synthesis, Static Timing Analysis, estimation and reduction of power consumption and LVS and DRC closure. The latter part is dedicated to high speed baseband circuits such as Coherent and Non coherent demodulator which are critical components of a multi-gigabit wireless communication system. The demodulator operates at input data rates of multiple gigabits per second, which presents the challenge of designing the building blocks to operate at speeds of multiple GHz. The high speed complex multiplier is a major component of the non coherent demodulator. As part of the coherent demodulator the complex multiplier derotates the input sequence by multiplying with cosine and sine functions, Costas error calculator computes the phase error in the derotated input signal. The NCO (Numerically controlled Oscillator) is a look up table based system used to generate the cosine and sine functions, used by the derotator.The CIC filter is used to decimate the costas error signal as the loop bandwidth is significantly smaller compared to the sampling frequency. All these modules put together form the coherent demodulator which is an integral part of the wireless communication system. An implementation of Serdes is also presented which acts as an interface between the baseband modules and the RF front end.

Changes in the gait characteristics, such as walking speed and stride length, of a person living at home can be used to presage cognitive decline, predict fall potential, monitor long-term changes in cognitive impairment, test drug regimens, and more. This thesis presents a novel approach to gait analysis in a smart-home environment by leveraging new advances in inexpensive sensors and embedded systems to create novel solutions for in-home gait analysis. Using a simple, non-invasive hardware system consisting entirely of wall-mounted infrared and radio frequency sensor arrays, data is collected on the gait of subjects as they pass by. This data is then analyzed and sent to a clinician for further study. The system is non-invasive in that it does not use cameras and could be built into the molding of a home so that it would be nearly invisible. In a finished prototype version, the system presented in this thesis could be used to analyze the gait characteristics of one or more subjects living in a home environment while ignoring the data of visitors and other non-subject cohabitants. The ability to constantly collect data from a home environment could provide thousands of observations per year for clinical analysis. Providing such a robust data set may allow people with gait impairment to live at home longer and more safely before transitioning to a care facility, have a reduced fall risk due to better prediction, and live a healthier life in old age.