Дисертації з теми "Physical signals"
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1
Li, Xiang. "PHYSICAL LAYER WATERMARKING OF DIRECT SEQUENCE SPREAD SPECTRUM SIGNALS." Cleveland State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=csu1368527408.
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2
Wong, Stephanie A. "Physical and Molecular Pathways Involved in Cellular Sensing of Mechanical Signals." Research Showcase @ CMU, 2016. http://repository.cmu.edu/dissertations/878.
Повний текст джерелаАнотація:
Mechanical properties of the extracellular environment provide important cues that regulate cell behavior. Particularly, the cellular response to substrate rigidity has become an important parameter to consider in disease treatment as well as tissue engineering. The goal of this thesis is to understand how adherent cells sense and respond to external rigidity cues. It has been challenging to study the mechanism that drives the preferential migration of cells towards stiffer substrates at a rigidity border due to difficulties in capturing cells as they transiently encounter a rigidity interface. Using a model system developed for testing cellular responses at a simulated rigidity border, I find that NIH 3T3 cells preferentially localize to the rigid portion of the model system. Cells use filopodia extensions to probe substrate rigidity in front of the leading edge and use substrate strain to determine whether the filopodia protrusions retract or expand to occupy the area. Myosin II mediated contractility is necessary to generate forces for both probing the substrate and retraction in response to substrate strain. Focal adhesion kinase null (FAK -/-) cells, known to be defective in durotaxis, are able to readily cross the rigidity border, while reexpression of focal adhesion kinase (FAK) rescues rigidity sensing. The model experimental system allows efficient analyses of conditions affecting rigidity sensing of cells. The results suggest that enhanced Rho activity, likely through Rho downstream effector mDia1, may underlie many rigidity sensing defects including those caused by FAK deficiency and microtubule disassembly. Additionally, I show that probing mechanisms at the front of a cell are used not only for probing rigidity but for sensing the state of migration. Design of a new checkerboard micropattern with alternating adhesive and non-adhesive areas revealed that the appearance of new traction forces and focal adhesions at the leading edge promotes the downregulation of pre-existing traction forces and focal adhesions that lag behind. These results suggest that in migrating cells continuous protrusion and mechanical probing directly in front of existing adhesions modulates traction force build up and serves as a key mechanism for regulating mechanical output in response to physical cues.
3
Kundu, Prantik. "Physical analysis of BOLD fMRI signals for functional brain mapping and connectomics." Thesis, University of Cambridge, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648842.
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4
Wiggins, Bryan Blake. "Using Induced Signals to Develop a Position-Sensitive Microchannel Plate Detector." Thesis, Indiana University, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10686059.
Повний текст джерелаАнотація:
A novel concept to provide position-sensitivity to a microchannel plate (MCP) is described. While several designs exist to make MCPs position sensitive, all these designs are based upon collection of the electrons. In contrast, this approach utilizes an induced signal as the electron cloud emanates from an MCP and passes a wire plane. We demonstrate the validity of the concept by constructing a device that provides single electron detection with 98 μm position resolution (FWHM) over an area of 50 mm × 50 mm. The characteristics of the detector are described through both bench-top tests and simulation. After characterization of the detector, the sense wire detector was utilized for slow-neutron radiography. Furthermore, we utilized our knowledge of position-sensitive techniques to realize a beam-imaging MCP detector useful for radioactive beam facilities.
5
Gray, Martha Lane. "Physical regulation of epiphyseal cartilage biosynthesis : responses to electrical, mechanical, and chemical signals." Thesis, Massachusetts Institute of Technology, 1986. http://hdl.handle.net/1721.1/17205.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Harvard-MIT Division of Health Sciences and Technology Program in Medical Engineering and Medical Physics, 1986.MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE.
Bibliography: leaves 194-205.
by Martha Lane Gray.
Ph.D.
6
Flodin, Mikael. "Determining upper limits on galactic ETI civilizations transmitting continuous beacon signals in the radio spectrum." Thesis, KTH, Fysik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-266824.
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7
Succo, Kelli Fredrickson. "Acoustic Intensity of Narrowband Signals in Free-Field Environments." BYU ScholarsArchive, 2017. https://scholarsarchive.byu.edu/etd/7092.
Повний текст джерелаАнотація:
The phase and amplitude gradient estimator (PAGE) method has proven successful in improving the accuracy of measured energy quantities over the p-p method, which has traditionally been used, in several applications. One advantage of the PAGE method is the use of phase unwrapping, which allows for increased measurement bandwidth above the spatial Nyquist frequency. However, phase unwrapping works best for broadband sources in free-field environments with high coherence. Narrowband sources often do not have coherent phase information over a sufficient bandwidth for a phase unwrapping algorithm to unwrap properly. In fact, phase unwrapping processing can cause significant error when there is no coherent signal near and above the spatial Nyquist frequency. However, for signals at any frequencies up to the spatial Nyquist frequency, the PAGE method provides correct intensity measurements regardless of the bandwidth of the signal. This is an improved bandwidth over the traditional method. For narrowband sources above the spatial Nyquist frequency, additional information is necessary for the PAGE method to provide accurate acoustic intensity. With sufficient bandwidth and a coherence of at least 0.1 at the spatial Nyquist frequency, a relatively narrowband source above the spatial Nyquist frequency can be unwrapped accurately. One way of using extra information, called the extrapolated PAGE method, uses the phase of a tone below the spatial Nyquist frequency and an assumption of a propagating field, and therefore linear phase, to extrapolate the phase above the spatial Nyquist frequency. Also, within certain angular and amplitude constraints, low-level broadband noise can be added to the field near a source emitting a narrowband signal above the spatial Nyquist frequency. The low-level additive broadband noise can then provide enough phase information for the phase to be correct at the frequencies of the narrowband signal. All of these methods have been shown to work in a free-field environment.
8
Jackson, David. "Exploiting Rogue Signals to Attack Trust-based Cooperative Spectrum Sensing in Cognitive Radio Networks." VCU Scholars Compass, 2013. http://scholarscompass.vcu.edu/etd/3072.
Повний текст джерелаАнотація:
Cognitive radios are currently presented as the solution to the ever-increasing spectrum shortage problem. However, their increased capabilities over traditional radios introduce a new dimension of security threats. Cooperative Spectrum Sensing (CSS) has been proposed as a means to protect cognitive radio networks from the well known security threats: Primary User Emulation (PUE) and Spectrum Sensing Data Falsification (SSDF). I demonstrate a new threat to trust-based CSS protocols, called the Rogue Signal Framing (RSF) intrusion. Rogue signals can be exploited to create the illusion of malicious sensors which leads to the framing of innocent sensors and consequently, their removal from the shared spectrum sensing. Ultimately, with fewer sensors working together, the spectrum sensing is less robust for making correct spectrum access decisions. The simulation experiments illustrate the impact of RSF intrusions which, in severe cases, shows roughly 40\% of sensors removed. To mitigate the RSF intrusion's damage to the network's trust, I introduce a new defense based on community detection from analyzing the network's Received Signal Strength (RSS) diversity. Tests show a 95\% damage reduction in terms of removed sensors from the shared spectrum sensing, thus retaining the benefits of CSS protocols.
9
Phua, Gailene. "Estimation of geometric properties of three-component signals for condition monitoring." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAT004.
Повний текст джерелаАнотація:
La plupart des méthodes de surveillance des systèmes sont basées sur l'analyse et la caractérisation de grandeurs physiques qui sont par nature tridimensionnelles. Tracées dans un repère euclidien à trois dimensions, ces grandeurs parcourent en fonction du temps une trajectoire dont les caractéristiques géométriques sont représentatives de l'état du système surveillé. Les techniques classiques de surveillance des systèmes étudient les grandeurs mesurées composante par composante, sans prendre en compte leur nature tridimensionnelle et les propriétés géométriques de leur trajectoire. Une part importante de l'information est ainsi ignorée. Dans le cadre de ce travail de recherche, on se propose de développer une méthode d'analyse et de traitement de grandeurs à trois composantes permettant de mettre en évidence les spécificités géométriques des données et de fournir une information complémentaire pour la surveillance des systèmes. La méthode proposée a été appliquée à deux cas différents : la surveillance des creux de tension des réseaux de puissance triphasés et la surveillance des défauts de roulement des machines électriques tournantes. Dans ces deux cas, les résultats obtenus sont prometteurs et montrent que les indicateurs géométriques estimés mènent à de l'information complémentaire qui peut être utile pour la surveillance des systèmesMost methods for condition monitoring are based on the analysis and characterization of physical quantities that are three-dimensional in nature. Plotted in a three-dimensional Euclidean space as a function of time, these quantities follow a trajectory whose geometric characteristics are representative of the state of the monitored system. Usual techniques of condition monitoring study the measured quantities component by component, without taking into account their three-dimensional nature and the geometric properties of their trajectory. A significant part of the information is thus ignored. In this research work, we would therefore like to develop a method for the analysis and processing of three-component quantities capable of highlighting the special geometric features of such data and providing complementary information for condition monitoring. The proposed method has been applied to two different cases: voltage dips monitoring in three-phase power networks and bearing faults monitoring in rotating electrical machines. In this two cases, the results obtained are promising and show that the estimated geometric indicators lead to complementary information that can be useful for condition monitoring
10
Viljoen, Suretha. "Analysis of crosstalk signals in a cylindrical layered volume conductor influence of the anatomy, detection system and physical properties of the tissues /." Diss., Pretoria : [s.n.], 2005. http://upetd.up.ac.za/thesis/available/etd-08082005-113739.
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11
Belle, Ashwin. "A Physiological Signal Processing System for Optimal Engagement and Attention Detection." VCU Scholars Compass, 2012. http://scholarscompass.vcu.edu/etd/394.
Повний текст джерелаАнотація:
In today’s high paced, hi-tech and high stress environment, with extended work hours, long to-do lists and neglected personal health, sleep deprivation has become common in modern culture. Coupled with these factors is the inherent repetitious and tedious nature of certain occupations and daily routines, which all add up to an undesirable fluctuation in individuals’ cognitive attention and capacity. Given certain critical professions, a momentary or prolonged lapse in attention level can be catastrophic and sometimes deadly. This research proposes to develop a real-time monitoring system which uses fundamental physiological signals such as the Electrocardiograph (ECG), to analyze and predict the presence or lack of cognitive attention in individuals during task execution. The primary focus of this study is to identify the correlation between fluctuating level of attention and its implications on the physiological parameters of the body. The system is designed using only those physiological signals that can be collected easily with small, wearable, portable and non-invasive monitors and thereby being able to predict well in advance, an individual’s potential loss of attention and ingression of sleepiness. Several advanced signal processing techniques have been implemented and investigated to derive multiple clandestine and informative features. These features are then applied to machine learning algorithms to produce classification models that are capable of differentiating between the cases of a person being attentive and the person not being attentive. Furthermore, Electroencephalograph (EEG) signals are also analyzed and classified for use as a benchmark for comparison with ECG analysis. For the study, ECG signals and EEG signals of volunteer subjects are acquired in a controlled experiment. The experiment is designed to inculcate and sustain cognitive attention for a period of time following which an attempt is made to reduce cognitive attention of volunteer subjects. The data acquired during the experiment is decomposed and analyzed for feature extraction and classification. The presented results show that to a fairly reasonable accuracy it is possible to detect the presence or lack of attention in individuals with just their ECG signal, especially in comparison with analysis done on EEG signals. The continual work of this research includes other physiological signals such as Galvanic Skin Response, Heat Flux, Skin Temperature and video based facial feature analysis.
12
Bsoul, Abed Al-Raoof. "PROCESSING AND CLASSIFICATION OF PHYSIOLOGICAL SIGNALS USING WAVELET TRANSFORM AND MACHINE LEARNING ALGORITHMS." VCU Scholars Compass, 2011. http://scholarscompass.vcu.edu/etd/258.
Повний текст джерелаАнотація:
Over the last century, physiological signals have been broadly analyzed and processed not only to assess the function of the human physiology, but also to better diagnose illnesses or injuries and provide treatment options for patients. In particular, Electrocardiogram (ECG), blood pressure (BP) and impedance are among the most important biomedical signals processed and analyzed. The majority of studies that utilize these signals attempt to diagnose important irregularities such as arrhythmia or blood loss by processing one of these signals. However, the relationship between them is not yet fully studied using computational methods. Therefore, a system that extract and combine features from all physiological signals representative of states such as arrhythmia and loss of blood volume to predict the presence and the severity of such complications is of paramount importance for care givers. This will not only enhance diagnostic methods, but also enable physicians to make more accurate decisions; thereby the overall quality of care provided to patients will improve significantly. In the first part of the dissertation, analysis and processing of ECG signal to detect the most important waves i.e. P, QRS, and T, are described. A wavelet-based method is implemented to facilitate and enhance the detection process. The method not only provides high detection accuracy, but also efficient in regards to memory and execution time. In addition, the method is robust against noise and baseline drift, as supported by the results. The second part outlines a method that extract features from ECG signal in order to classify and predict the severity of arrhythmia. Arrhythmia can be life-threatening or benign. Several methods exist to detect abnormal heartbeats. However, a clear criterion to identify whether the detected arrhythmia is malignant or benign still an open problem. The method discussed in this dissertation will address a novel solution to this important issue. In the third part, a classification model that predicts the severity of loss of blood volume by incorporating multiple physiological signals is elaborated. The features are extracted in time and frequency domains after transforming the signals with Wavelet Transformation (WT). The results support the desirable reliability and accuracy of the system.
13
Lott, Geoffrey Adam 1980. "Probing local conformation and dynamics of molecular complexes using phase-selective fluorescence correlation and coherence spectroscopy." Thesis, University of Oregon, 2010. http://hdl.handle.net/1794/10914.
Повний текст джерелаАнотація:
xv, 177 p. : ill. (some col.) A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number.When two or more fluorescent chromophores are closely spaced in a macromolecular complex, dipolar coupling leads to delocalization of the excited states, forming excitons. The relative transition frequencies and magnitudes are sensitive to conformation, which can then be studied with optical spectroscopy. Non-invasive fluorescence spectroscopy techniques are useful tools for the study of dilute concentrations of such naturally fluorescent or fluorescently labeled biological systems. This dissertation presents two phase-selective fluorescence spectroscopy techniques for the study of dynamical processes in bio-molecular systems across a wide range of timescales. Polarization-modulated Fourier imaging correlation spectroscopy (PM-FICS) is a novel phase-selective fluorescence spectroscopy for simultaneous study of translational and conformational dynamics. We utilize modulated polarization and intensity gratings with phase-sensitive signal collection to monitor the collective fluctuations of an ensemble of fluorescent molecules. The translational and conformational dynamics can be separated and analyzed separately to generate 2D spectral densities and joint probability distributions. We present results of PM-FICS experiments on DsRed, a fluorescent protein complex. Detailed information on thermally driven dipole-coupled optical switching pathways is found, for which we propose a conformation transition mechanism. 2D phase-modulation electronic coherence spectroscopy is a third-order nonlinear spectroscopy that uses collinear pulse geometry and acousto-optic phase modulation to isolate rephasing and nonrephasing contributions to the collected fluorescence signal. We generate 2D spectra, from which we are able to determine relative dipole orientations, and therefore structural conformation, in addition to detailed coupling information. We present results of experiments on magnesium tetraphenylporphyrin dimers in lipid vesicle bilayers. The 2D spectra show clearly resolved diagonal and off-diagonal features, evidence of exciton behavior. The amplitudes of the distinct spectral features change on a femtosecond timescale, revealing information on time-dependent energy transfer dynamics. This dissertation includes co-authored and previously published material.
Committee in charge: Hailin Wang, Chairperson, Physics; Andrew Marcus, Advisor, Chemistry; Stephen Gregory, Member, Physics; Michael Raymer, Member, Physics; Marina Guenza, Outside Member, Chemistry
14
Navrátil, Petr. "Modely systému LTE." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2013. http://www.nusl.cz/ntk/nusl-219984.
Повний текст джерелаАнотація:
Master’s thesis is focused on part of mobile network named LTE. Project is analyzes the LTE physical layer, which is divided into four basic parts: Physical channels and modulation, Multiplexing and channel coding, Physical layer procedures, Physical layer measurements. Every part is described by actual 3GPP standard [1]. To understand the problem is expected a reader basic knowledge of OFDM systems, which the LTE system uses. The next part of this master’s thesis is dedicated to mathematic model physical layer of system LTE, created by program Matlab. This model is designed to measure errors in data transmission.
15
Chadburn, Sarah Elizabeth. "Signals of early-universe physics in cosmology." Thesis, Durham University, 2013. http://etheses.dur.ac.uk/7008/.
Повний текст джерелаАнотація:
This is a thesis on theoretical cosmology. The first and largest part is a study of cosmic strings, in particular their dynamics and signals in higher dimensional spacetimes. The second part is a study of black holes in a quintessence background. Cosmic strings are predicted by models of the early universe. They were thought to arise, originally, from Grand Unified Theories, and more recently from brane inflationary models based in string theory. In Chapter 3 we find exact solutions for cosmic string loop trajectories in higher dimensions, and find the regions of parameter space for which cusps exist. We find that winding the internal dimensions slows the average velocity of string loops, and conjecture that the periodicity of internal space may contribute to self-intersections. In Chapter 4, we calculate the gravitational wave signal from cosmic string cusps in higher dimensions, and find it is much reduced relative to the 4D case. The main reason for this is the large reduction in the probability of cusps occurring on loops in higher dimensions, as well as a slight reduction in signal from individual cusps. In Chapter 5, we study cosmic string trajectories in warped spacetimes, such as may be found in realistic brane inflation models. We find that contrary to claims in the literature, the warping of the internal space does not prevent the internal motion of strings. The energy associated with the warping of spacetime means that the energy of a loop appears to change over time from our 4D perspective. Finally, in Chapter 6, we find an analytic, general-relativistic solution describing a black hole in a quintessence universe. Quintessence is a model of late-time cosmic acceleration in which expansion is sourced by a scalar field. Our solution shows the interaction between this scalar field and a black hole. The scalar field is shown to continue its cosmological "rolling" behaviour everywhere, including on the black hole event horizon, and the black hole is shown slowly to accrete scalar field. This is a perturbative solution valid throughout all of space but only over a finite period of time.
16
Lin, Tongyan. "Signals of Particle Dark Matter." Thesis, Harvard University, 2012. http://dissertations.umi.com/gsas.harvard:10273.
Повний текст джерелаАнотація:
This thesis explores methods of detecting dark matter particles, with some emphasis on several dark matter models of current interest. Detection in this context means observation of an experimental signature correlated with dark matter interactions with Standard Model particles. This includes recoils of nuclei or electrons from dark matter scattering events, and direct or indirect observation of particles produced by dark matter annihilation.Physics
17
Tang, Hong 1961. "Blurring in bar code signals." Diss., The University of Arizona, 1997. http://hdl.handle.net/10150/289067.
Повний текст джерелаАнотація:
When a bar code symbol is passed over a scanner, it is struck across by a fast moving laser beam. The laser light is scattered by the bar code. The total scattered power is modulated by the reflectivity of the bars and spaces in the symbol. A fraction of the scattered light is collected and focused onto a photodetector that converts the light variation into an electronic signal. The electronic signal is then digitized for analysis by a computer. The scanning and detection process can be modeled by a convolution of the laser beam profile and the bar code reflectivity function. The switching between states in the digitized bar code signal, which represents transitions from a space to a bar or vice versa, is determined by a zero-crossing point in the second derivative of the analog signal. The laser profile acts like a smoothing function. It blurs the analog electronic signal. If the width of the laser profile is less than the minimum width of bars and spaces in the bar code reflectivity function, the transition point is not affected by the location of its neighboring edges. If the laser profile is wider than the minimum width in the bar code, the transition point can be shifted due to the locations of its neighboring edges. The behavior of the shift of transition is analyzed here for all cases in a UPC symbol. It is found that the amount of shift in the transition point is almost the same for several different cases within the depth of field of the scanner. The knowledge of the behavior of transition point shift can be used to accurately compensate printing errors in an over-printed bar code. The modulation transfer function (MTF) of bar code scanning is the Fourier transform of the marginal function of the scanning laser beam. The MTF through focus for a scanning system is presented. By using an aperture with central obscuration in the laser focusing system, the high frequency resolution of bar code scanning can be enhanced and the depth of field of the scanner can be extended.
18
Xiang, Weichen. "Power allocation and signal labelling on physical layer security." Thesis, University of Newcastle upon Tyne, 2016. http://hdl.handle.net/10443/3399.
Повний текст джерелаАнотація:
Secure communications between legitimate users have received considerable attention recently. Transmission cryptography, which introduces secrecy on the network layer, is heavily relied on conventionally to secure communications. However, it is theoretically possible to break the encryption if unlimited computational resource is provided. As a result, physical layer security becomes a hot topic as it provides perfect secrecy from an information theory perspective. The study of physical layer security on real communication system model is challenging and important, as the previous researches are mainly focusing on the Gaussian input model which is not practically implementable. In this thesis, the physical layer security of wireless networks employing finite-alphabet input schemes are studied. In particular, firstly, the secrecy capacity of the single-input single-output (SISO) wiretap channel model with coded modulation (CM) and bit-interleaved coded modulation (BICM) is derived in closed-form, while a fast, sub-optimal power control policy (PCP) is presented to maximize the secrecy capacity performance. Since finite-alphabet input schemes achieve maximum secrecy capacity at medium SNR range, the maximum amount of energy that the destination can harvest from the transmission while satisfying the secrecy rate constraint is computed. Secondly, the effects of mapping techniques on secrecy capacity of BICM scheme are investigated, the secrecy capacity performances of various known mappings are compared on 8PSK, 16QAM and (1,5,10) constellations, showing that Gray mapping obtains lowest secrecy capacity value at high SNRs. We propose a new mapping algorithm, called maximum error event (MEE), to optimize the secrecy capacity over a wide range of SNRs. At low SNR, MEE mapping achieves a lower secrecy rate than other well-known mappings, but at medium-to-high SNRs MEE mapping achieves a significantly higher secrecy rate over a wide range of SNRs. Finally, the secrecy capacity and power allocation algorithm (PA) of finite-alphabet input wiretap channels with decode-and-forward (DF) relays are proposed, the simulation results are compared with the equal power allocation algorithm.
19
Chen, Dian. "Transmission line modelling (TLM) of physical systems." Thesis, University of Sheffield, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.361632.
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Ritter, David M., and Tina Dr Smilkstein. "Verification of Receiver Equalization by Integrating Dataflow Simulation and Physical Channels." DigitalCommons@CalPoly, 2017. https://digitalcommons.calpoly.edu/theses/1733.
Повний текст джерелаАнотація:
This thesis combines Keysight’s SystemVue software with a Vector Signal Analyzer (VSA) and Vector Signal Generator (VSG) to test receiver equalization schemes over physical channels. The testing setup, “Equalization Verification,” is intended to be able to evaluate any equalization scheme over any physical channel, and a decision-directed feed-forward LMS equalizer is used as an example. The decision-directed feed-forward LMS equalizer is shown to decrease the BER from 10-2 to 10-3 (average of all trials) over a CAT7 and CAT6A cable, both simulated and physical, for 1GHz and 2GHz carrier, and 80MHz data rate. A wireless channel, 2.4GHz Dipole Antenna, is also tested to show that the addition of the equalization scheme decreases BER from 10-5 to less than 10-5. Then the simulation and equalization parameters (LMS step size, PRBS, etc.) are changed to further verify the equalization scheme. The simulated channel BER results do not always match the physical channel BER results, but the equalization scheme does decrease BER for both wired and wireless channels.
Then transistor-based equalization model is created using both HDL SystemVue components and blocks easily implemented by transistors. The model is then verified using HDL, Spice, and SystemVue simulation. Overall this thesis accomplishes its goal of creating a testing setup, Equalization Verification, to show that adding a given simulated equalization scheme in SystemVue can improve the quality of the link, by decreasing BER by at least an order of magnitude, over a specific physical channel.
21
Li, Lefei. "Development and Evaluation of Transit Signal Priority Strategies with Physical Queue Models." Diss., The University of Arizona, 2006. http://hdl.handle.net/10150/193823.
Повний текст джерелаАнотація:
With the rapid growth in modern cities and congestion on major freeways and local streets, public transit services have become more and more important for urban transportation. As an important component of Intelligent Transportation Systems (ITS), Transit Signal Priority (TSP) systems have been extensively studied and widely implemented to improve the quality of transit service by reducing transit delay. The focus of this research is on the development of a platform with the physical queue representation that can be employed to evaluate and/or improve TSP strategies with the consideration of the interaction between transit vehicles and queues at the intersection.This dissertation starts with deterministic analyses of TSP systems based on a physical queue model. A request oriented TSP decision process is then developed which incorporates a set of TSP decision regions defined on a time-space diagram with the physical queue representation. These regions help identify the optimal detector location, select the appropriate priority control strategy, and handle the situations with multiple priority requests. In order to handle uncertainties in TSP systems arising in bus travel time and dwell time estimation, a type-2 fuzzy logic forecasting system is presented and tested with field data. Type-2 fuzzy logic is very powerful in dealing with uncertainty. The use of Type-2 fuzzy logic helps improve the performance of TSP systems. The last component of the dissertation is the development of a Colored Petri Net (CPN) model for TSP systems. With CPN tools, computer simulation can be performed to evaluate various TSP control strategies and the decision process. Examples for demonstrating the process of implementing the green extension strategy and the proposed TSP decision process are presented in the dissertation. The CPN model can also serve as an interface between the platform developed in this dissertation and the implementation of the control strategies at the controller level.
22
Becanovic, Vlatko. "Signal and image processing in engineering physics." Doctoral thesis, KTH, Physics, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-2979.
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23
Minerskjöld, Maxim. "Sensors, signals and systems for electromagnetic radiation experiments in physics /." Stockholm, 1998. http://www.lib.kth.se/abs98/mine0528.pdf.
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24
Syed, Asad Abbas. "Large Signal Physical Simulations of Si LD-MOS transistor for RF application." Thesis, Linköping University, The Department of Physics, Chemistry and Biology, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-2627.
Повний текст джерелаАнотація:
The development of computer aided design tools for devices and circuits has increased the interest for accurate transistor modeling in microwave applications. In the increasingly expanding wireless communication market, there is a huge demand for high performance RF power devices. The silicon LD- MOSFET transistor is dueto its high power performance is today widely used in systems such as mobile base stations, private branch exchanges (PBX), and local area networks (LAN) utilizing the bands between 0.9 to 2.5 GHz.
In this research we simulated LD-MOSFET transistor characteristics of the structure provided by Infineon technology at Kista, Stockholm. The maximum drain current obtained in the simulation was 400 mA at a gate voltage of 8 V. This value is somewhat higher than the measured one. This difference can be attributed to the parasitic effects since no parasitic effects were included in the simulations in the beginning. The only parasitic effect studied was by placing the source contact at the bottom of the substrate according to real commercial device. The matching between simulated and measured results were improved and maximum drain current was reduced to 300 mA/mm which was 30% higher than the measured drain current
The large signal RF simulations were performed in time-domain in our novel technique developed at LiU. This technique utilizes a very simple amplifier circuit without any passive components. Only DC bias and RF signals are applied to the gate and drain terminals, with the same fundamental frequency but with 180o phase difference. The RF signal at the drain acting as a short at higher harmonics. These signals thus also acted as an active match to the transistor. Large signal RF simulations were performed at 1, 2 and 3 GHz respectively. The maximum of drain current signal was observed at the maximum of drain voltage signal indicating the normal behavior of the transistor. At 1 GHz the output power was 1.25 W/mm with 63% of drain efficiency and 23.7 dB of gain. The out pout power was decreased to 1.15 W/mm and 1.1 W/mm at 2 and 3 GHz respectively at the same time the efficiency and gain was also decreased to 57% and 19 dB at 2 GHz and 51% and 15 dB at 3GHz respectively.
25
Lu, Xiaotao. "Cost-effective signal processing algorithms for physical-layer security in wireless networks." Thesis, University of York, 2016. http://etheses.whiterose.ac.uk/16043/.
Повний текст джерелаАнотація:
Data privacy in traditional wireless communications is accomplished by cryptography techniques at the upper layers of the protocol stack. This thesis aims at contributing to the critical security issue residing in the physical-layer of wireless networks, namely, secrecy rate in various transmission environments. Physical-layer security opens the gate to the exploitation of channel characteristics to achieve data secure transmission. Precoding techniques, as a critical aspect in pre-processing signals prior to transmission has become an effective approach and recently drawn significant attention in the literature. In our research, novel non-linear precoders are designed focusing on the improvement of the physical-layer secrecy rate with consideration of computational complexity as well as the Bit Error Ratio (BER) performance. In the process of designing the precoder, strategies such as Lattice Reduction (LR) and Artificial Noise (AN) are employed to achieve certain design requirements. The deployment and allocation of resources such as relays to assist the transmission also have gained significant interest. In multiple-antenna relay networks, we examine various relay selection criteria with arbitrary knowledge of the channels to the users and the eavesdroppers. Furthermore, we provide novel effective relay selection criteria that can achieve a high secrecy rate performance. More importantly they do not require knowledge of the channels of the eavesdroppers and the interference. Combining the jamming technique with resource allocation of relay networks, we investigate an opportunistic relaying and jamming scheme for Multiple-Input Multiple-Output (MIMO) buffer-aided downlink relay networks. More specifically, a novel Relaying and Jamming Function Selection (RJFS) algorithm as well as a buffer-aided RJFS algorithm are developed along with their ability to achieve a higher secrecy rate. Relying on the proposed relay network, we detail the characteristics of the system, under various relay selection criteria, develop exhaustive search and greedy search-based algorithms, with or without inter-relay Interference Cancellation (IC).
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Ng, Trina Tsao-Tin. "Domain transformations for optical telecommunications signals." Thesis, University of Southampton, 2010. https://eprints.soton.ac.uk/301294/.
Повний текст джерелаАнотація:
In this thesis, the transformation of optical telecommunication signal waveforms between the temporal and spectral domains is investigated. Temporal optical Fourier transformations (TOFTs) are presented with the primary aim of mitigating distortions in high repetition rate telecommunication signals, by transferring them from the temporal domain into the frequency domain. Development of TOFT is extended to aid their suitability for other applications also. The TOFT is based on inducing cross-phase modulation on the signal to be transformed, using shaped parabolic pulses as the pump. To demonstrate the technique, various methods of generating parabolic pulses are investigated and considered for their suitability for TOFTs. Firstly, parabolic pulses are generated in a nonlinear fashion exploiting their natural evolution in a normally dispersive fibre. Compensation is performed on timing jitter signals using this method. In another configuration, parabolic pulses are generated with a superstructured fibre Bragg grating. The passive nature and the chirp free parabolics generated by the grating enabled greater flexibility in the experimental parameters thus improving the fidelity of the TOFT. Compensation of pulses distorted by second and third order dispersion is demonstrated. Unexpected results in the first two TOFT experiments led to further analysis and the derivation of the conditions for a complete TOFT. Sophisticated reconfigurable filters are used to convert an optical frequency comb (OFC) into one or more simultaneous pulse sources, each with a configurable shape and phase profile. Pulses generated using the OFC and reconfigurable filter are used to experimentally verify the new theory. The thesis also includes a presentation of a linear frequency resolved optical gating technique. The versatility of the technique was demonstrated through the characterisation of many of the pulses generated in this thesis, providing insight to their time-frequency domain relationships.
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Sundberg, Christel. "Signal to Noise Optimization in Front-EndElectronics for X-ray Imaging." Thesis, KTH, Fysik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-211906.
Повний текст джерела
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Faber, Joshua Aaron 1977. "Gravity wave signals from relativistic calculations of binary neutron star coalescence." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/8283.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2001.Includes bibliographical references (p. 153-162).
This thesis describes the design, testing, and implementation of a Lagrangian, post-Newtonian, smoothed particle hydrodynamics code used to study the gravitational wave signature produced by coalescing neutron star binary systems. Additionally, we have studied the properties of remnants which may be formed during the merger process. We have introduced a hybrid post-Newtonian formalism, which treats lowest order 1PN relativistic terms at a reduced strength, to make the problem numerically tractable, while treating the gravitational radiation reaction, which is the lowest order dissipative term in general relativity, at full strength. We compare the results of calculations with and without 1PN effects for initially synchronized binary systems, for neutron stars with polytropic equations of state, finding that relativistic corrections play an important role in the dynamical stability of such sytems and the resulting gravitational wave forms. Relativistic corrections also suppress mass shedding in these systems. Studies of initially irrotational binary systems demonstrated that our results are independent of the numerical resolution of the calculations. The power spectrum of the gravitational radiation produced during a merger is found to yield important information about the neutron star equation of state, the binary mass ratio, and other physical parameters of the system.
by Joshua Aaron Faber.
Ph.D.
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Kounek, Milan. "Model fyzické vrstvy systému LTE." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2013. http://www.nusl.cz/ntk/nusl-220269.
Повний текст джерелаАнотація:
Master’s thesis deals with the signal processing in LTE system, specifically focuses on the physical layer. The first part describes in detail the signal processing at the physical layer of the LTE system. Based on the acquired knowledge of signal processing is created a block diagram that graphically describes the process of the signal processing. Next part deals with the created mathematical model, which is programmed in Matlab. This section describes the limitations of the model, configuration options and view simulation results. The last part shows the results of simulations and analyzed the results.
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Голубничий, Олексій Георгійович, Алексей Георгиевич Голубничий та Alexei Holubnychyi. "Методологія синтезу та обробки узагальнених бінарних послідовностей Баркера для широкосмугових каналів зв’язку". Thesis, Національний авіаційний університет, 2020. https://er.nau.edu.ua/handle/NAU/44147.
Повний текст джерелаАнотація:
Дисертація на здобуття наукового ступеня доктора технічних наук за
спеціальністю 05.12.02 – «Телекомунікаційні системи та мережі». – Національний
авіаційний університет, Київ, 2019.
У дисертаційній роботі вирішується актуальна науково-технічна проблема синтезу
бінарних дискретно-кодованих послідовностей (ДКП), які є оптимальними за
мінімаксним критерієм щодо їх автокореляційної функції (АКФ), у частині синтезу
регулярних структур цих ДКП та їх комбінаторних систем в умовах обмежень на
максимальний рівень абсолютних значень бічних пелюсток їх АКФ (ДКП Баркера).
Вирішенням зазначеної проблеми у дисертації є новий синтезований тип ДКП –
узагальнені бінарні послідовності Баркера (УБПБ), які характеризуються регулярними
структурами, можуть бути синтезовані регулярними методами синтезу та утворюють
нові мультиплікативно комплементарні структури бінарних ДКП.
У роботі розроблено методологію синтезу та обробки УБПБ та їх
мультиплікативно комплементарних структур, яка у своєму складі містить розроблену
параметрично-критеріальну модифікацію EM-алгоритму з видаленням компонент
гаусівської змішаної моделі для аналізу кореляційних зв’язків у системах ДКП та
доведені теореми про його математичну сингулярність за певних умов такого
статистичного аналізу для обґрунтування введених у модифікації алгоритму
критеріїв, розроблені метод структуризації ДКП з апріорі невідомими внутрішніми
структурами, регулярний метод синтезу УБПБ, метод синтезу та сумісної обробки
мультиплікативно комплементарних структур УБПБ, метод декомпозиції структури
вихідного сигналу системи обробки мультиплікативно комплементарних УБПБ, метод39
оцінювання енергетичних параметрів ортогональних сигнально-кодових конструкцій
та завад при передаванні УБПБ. У дослідженні також обґрунтовано класифікацію
УБПБ, виявлено та досліджено системні властивості регулярних структур УБПБ та їх
АКФ, синтезовано повну систему математичних моделей для аналітичного опису
АКФ УБПБ, розроблено аналітичні моделі оцінювання показників якості передавання
повідомлень у телекомунікаційних системах при використанні УБПБ.Диссертация на соискание учёной степени доктора технических наук по специальности 05.12.02 – «Телекоммуникационные системы и сети». – Национальный авиационный университет, Киев, 2019. Диссертационная работа посвящена решению актуальной научно-технической проблемы синтеза бинарных дискретно-кодированных последовательностей (ДКП), оптимальных по минимаксному критерию в отношении их автокорреляционной функции (АКФ), в части синтеза регулярных структур этих ДКП и их комбинаторных систем в условиях ограничений на максимальный уровень абсолютных значений боковых лепестков их АКФ (ДКП Баркера). Решением указанной проблемы в диссертации является новый синтезированный тип ДКП – обобщённые бинарные последовательности Баркера (ОБПБ), которые характеризуются регулярными структурами, могут быть синтезированы регулярными методами синтеза и образовывают новые мультипликативно комплементарные структуры бинарных ДКП. В работе разработана методология синтеза и обработки ОБПБ и их мультипликативно комплементарных структур, которая в своём составе содержит разработанную параметрически-критериальную модификацию EM-алгоритма с удалением компонент гауссовской смешанной модели для анализа корреляционных связей в системах ДКП и доказанные теоремы о его математической сингулярности в определённых условиях такого статистического анализа для обоснования введённых в модификации алгоритма критериев, разработанные метод структуризации ДКП с априори неизвестными внутренними структурами, регулярный метод синтеза ОБПБ, метод синтезу и совместной обработки мультипликативно комплементарных структур ОБПБ, метод декомпозиции структуры сигнала на выходе системы обработки мультипликативно комплементарных ОБПБ, метод оценивания энергетических параметров ортогональных сигнально-кодовых конструкций и помех при передаче ОБПБ. В исследовании также обоснована классификация ОБПБ, выявлены и исследованы системные свойства регулярных структур ОБПБ и их АКФ, синтезирована полная система математических моделей для аналитического описания АКФ ОБПБ, разработаны аналитические модели оценивания показателей качества передачи сообщений в телекоммуникационных системах при использовании ОБПБ.
Thesis for a degree of Doctor of Technical Science in specialty 05.12.02 – «Telecommunication Systems and Networks». – National Aviation University. – Kyiv, 2019. The thesis is devoted to solving the actual scientific and engineering problem dealing with a synthesis of binary sequences, which are optimal by the minimax criterion with respect to their autocorrelation function, in terms of a synthesis of regular structures of these binary sequences and their combinatorial systems under additional restrictions on the peak sidelobe level of their autocorrelation function (Barker sequences). The solution of the problem, proposed in the thesis, boils down to a new synthesized kind of binary sequences – generalized binary Barker sequences, which are characterized by regular structures, can be synthesized by means of regular synthesis method and form new multiplicative complementary structures of binary sequences. The methodology of synthesis and signal processing of generalized binary Barker sequences and their multiplicative complementary structures, developed in the thesis, consists of: (a) the modification (parametric and criteria features) of the expectationmaximization (EM) algorithm with removing components of the Gaussian mixture model and additional clustering criteria for a statistical analysis of cross-correlations between sequences in a system for their further structuring, based on proved theorems on mathematical singularities in the log-likelihood function in the mentioned statistical analysis of cross-correlations; (b) the method of structuring binary sequences with a priori unknown structures, which provides selecting groups of binary sequences with interconnected structures and further detecting these interconnected structures in an explicit form; (c) the regular method for synthesis of generalized binary Barker sequences, based on the deterministic generation rules for these sequences; (d) the method for synthesis and joint signal processing of multiplicative complementary structures of generalized binary Barker sequences, based on the multiplication of results of matched filtering of signal components; (e) the method of a structural decomposition of output signal in signal processing system for multiplicative complementary generalized binary Barker sequences (an output signal can be represented by some number of separately taken partial lobes, each of which is characterized by constant mean value and variance of signal), which allows to perform a statistical analysis of output signal for noise immunity analysis, detection and other purposes in telecommunication system; (f) the method of estimation of energetic parameters of orthogonal signal-code constructions and noise on the physical layer of telecommunication system in case of use of generalized binary Barker sequences. The classification by types and subtypes of generalized binary Barker sequences, based on statistical clustering using the EM and k-means algorithms, is also justified in the research. The properties of regular structures of generalized binary Barker sequences and properties of their autocorrelation functions are detected and studied. A complete system of mathematical models for analytical description of the autocorrelation function of generalized binary Barker sequences is synthesized. The analytical models for estimation of quality characteristics on the physical layer of telecommunication system in case of use of generalized binary Barker sequences are developed. Spectral and detection features of generalized binary Barker sequences and their comparison with Golay complementary sequences are also studied in the research. In contrast with Golay complementary sequences, generalized binary Barker sequences provide larger values of the processing gain in sidelobes (by 4.1 dB for a considered case), which provides less noise in sidelobes and a lower number of errors of the first genus in the case of the use of generalized binary Barker sequences. At the same time, the main disadvantage of generalized binary Barker sequences in comparison with Golay complementary sequences is that the processing gain in the main central lobe is lower (by 8.9 dB for a considered case), which causes more noise in the main lobe and a greater number of errors of the second genus in the case of the use of generalized binary Barker sequences. With this, the compared systems of sequences are characterized by almost the same total bandwidth, and the fact that generalized binary Barker sequences also provide a lower pulse width in the main lobe after signal processing (by 1.5 times), which provides a greater maximum data transfer rate and spectral efficiency on the physical layer of spread-spectrum telecommunication system (up to 1.5 times). The research results were implemented in the production and research activities of the UkSATSE Flight Calibration & Rescue Service (Ukrainian State Air Traffic Services Enterprise «UkSATSE») and educational processes at the Faculty of Air Navigation, Electronics and Telecommunications (National Aviation University, Kyiv).
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Bertoncini, Crystal Ann. "Applications of pattern classification to time-domain signals." W&M ScholarWorks, 2010. https://scholarworks.wm.edu/etd/1539623559.
Повний текст джерелаАнотація:
Many different kinds of physics are used in sensors that produce time-domain signals, such as ultrasonics, acoustics, seismology, and electromagnetics. The waveforms generated by these sensors are used to measure events or detect flaws in applications ranging from industrial to medical and defense-related domains. Interpreting the signals is challenging because of the complicated physics of the interaction of the fields with the materials and structures under study. often the method of interpreting the signal varies by the application, but automatic detection of events in signals is always useful in order to attain results quickly with less human error. One method of automatic interpretation of data is pattern classification, which is a statistical method that assigns predicted labels to raw data associated with known categories. In this work, we use pattern classification techniques to aid automatic detection of events in signals using features extracted by a particular application of the wavelet transform, the Dynamic Wavelet Fingerprint (DWFP), as well as features selected through physical interpretation of the individual applications. The wavelet feature extraction method is general for any time-domain signal, and the classification results can be improved by features drawn for the particular domain. The success of this technique is demonstrated through four applications: the development of an ultrasonographic periodontal probe, the identification of flaw type in Lamb wave tomographic scans of an aluminum pipe, prediction of roof falls in a limestone mine, and automatic identification of individual Radio Frequency Identification (RFID) tags regardless of its programmed code. The method has been shown to achieve high accuracy, sometimes as high as 98%.
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Pedraza, Juan Manuel. "Signal and noise propagation in genetic circuits." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/34402.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, February 2006.Includes bibliographical references (p. 145-152).
Interactions between genes in living organisms are intrinsically stochastic. This not only gives rise to phenotypic variation in clonal populations of cells, but also fundamentally limits signaling fidelity and cellular memory. Accurately predicting noise propagation in gene networks is thus crucial for reverse engineering natural networks and designing reliable synthetic genetic circuits. To determine how noise propagates through gene networks we measure, in single bacterial cells, expression variability and correlations between genes in a cascade and correlations with a constitutive gene. We find that noise in a gene is determined by its intrinsic fluctuations, transmitted noise from upstream genes and global noise affecting all genes. Our results imply that the dominant noise sources can be external to any given gene and that even for networks in which no component has significant intrinsic noise, total noise can be significant due to amplification of global fluctuations. We develop a Langevin type model that explains the complex behaviour exhibited by the noises and correlations, and reveals the dominant noise sources from the biochemical characteristics of the individual genes. The model successfully predicts the noises and correlations as the network is systematically perturbed. It also indicates that the additional information from the protein expression distributions can be used to better determine the system parameters and provides the basis for a Monte Carlo simulation method, which allows for fast, approximate simulations of the distributions.
As an extension and proof of applicability of the approach, we choose a natural network, the E. Coli lactose uptake network, to predict the dynamic behaviour of the distributions. We measure population distributions of protein numbers as a function of time, and show that prediction of dynamic distributions requires only a few noise parameters from the steady state noise measurements in addition to the rates that characterize a deterministic model. Our results show that even though noise sources are ubiquitous and network dependent, the protein distributions and even their dynamic behavior can be predicted from basic parameters, and the simplicity of the formulae brings the promise of decoding and designing the genetic networks that control the function of all living cells.
by Juan Manuel Pedraza.
Ph.D.
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Low, Guang Hao. "Quantum signal processing by single-qubit dynamics." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/115025.
Повний текст джерелаАнотація:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Physics, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 117-125).
Quantum computation is the most powerful realizable model of computation, and is uniquely positioned to solve specialized problems intractable to classical computers. This quantum advantage arises from directly exploiting the strangeness of quantum mechanics that is fundamental to reality. As such, one expects our understanding of quantum processes in physical systems to be indispensable to the design and execution of quantum algorithms. We present quantum signal processing, which exploits the dynamics of simple quantum systems to perform non-trivial computations. Such systems applied as computational modules in larger quantum algorithms, offer a natural physical alternative to standard tasks such as the calculation of elementary functions with integer arithmetic. The quantum advantage of this approach, based on simple physics, is of significant practical relevance. In cases, arbitrary bits of precision may be emulated using only constant space. Moreover, the simplicity and performance of quantum signal processing is such that it is the final missing ingredient for realizing a number of optimal quantum algorithms, particularly in Hamiltonian simulation. Quantum signal processing realizes a useful fusion of analog and digital models of quantum computation. At the physical level, we focus on how even a simple two-level system - the qubit, computes through optimal discrete-time quantum control. Whereas quantum control is typically used to synthesize unitary quantum gates, we solve the synthesis problem of unitary quantum functions with a fully characterization of achievable functions, and efficient techniques for their implementation. This furnishes a surprisingly rich framework in the analog model of quantum computation for computing functions. The generality of this model is realized by many applications, often with no modification, to quantum algorithms designed for digital quantum computers, in particular for matrix manipulation. In this manner, we solve a number of open problem related to optimal amplitude amplification algorithms, optimally computing on matrices with a quantum computer, and the simulation of physical systems.
by Guang Hao Low.
Ph. D.
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Bouchikhi, Abdelkhalek. "Analyse des signaux AM-FM par Transformation d'Huang Teager: application à l'acoustique sous marine." Phd thesis, Université Rennes 1, 2010. http://tel.archives-ouvertes.fr/tel-00818032.
Повний текст джерелаАнотація:
La Décomposition Modale Empirique (EMD) est un outil de traitement de signal piloté par les données et dédié aux signaux non-stationnaires issus ou non de systèmes linéaires. L'idée de base de l'EMD est l'interpolation des extrema par des splines pour extraire de composantes oscillantes appelées modes empiriques intrinsèques (IMFs) et un résidu. Dans cette thèse, un nouvel algorithme de l'EMD est introduit où au lieu d'une interpolation rigide, un lissage est utilisé pour la construction des enveloppes supérieures et inférieures du signal à décomposer. Ce nouvel algorithme est plus robuste au bruit que l'EMD conventionnelle et réduit le nombre d'IMFs "artificielles" (sur-décomposition). En combinant le nouvel algorithme et la méthode de séparation d'énergie (ESA) basée sur l'Opérateur d'Energie de Teager-Kaiser (OETK), un nouveau schéma de démodulation des signaux AM-FM multi-composante appelé EMD-ESA est introduit. Différentes versions de l'EMD-ESA sont analysées en terme de performance. Pour l'analyse Temps-Fréquence (TF), une nouvelle formulation de la carte TF de l'EMD-ESA appelée Transformation de Teager-Huang (THT) est présentée. Cette nouvelle Représentation TF (RTF) ne présentant pas de termes d'interférences est comparée aux RTF classiques telles que le spectrogramme, le scalogramme, la distribution de Wigner-Ville Distribution (WVD), la Pseudo-WVD et la réallocation de la Pseudo-WVD. En combinant la nouvelle formulation de la THT et la transformée de Hough, une nouvelle méthode de détection des signaux multi-composante à modulation linéaire de fréquence dans le plan TF est présentée. Cette méthode de détection est appelée transformation de Teager-Huang-Hough (THHT). Les résultats de la THHT sont comparés à ceux de la transformée WVD-Hough. Finalement, l'analyse TF par THT et par des RTF classiques (WVD, spectrogramme, etc.) de signaux réels de rétrodiffusion par des coques cylindriques de dimensions et de caractéristiques physiques différentes est présentée. Les résultats obtenus montrent l'apport de la THT comme un outil TF.
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Navarro, Roy Daniel Alva. "Signals of new physics at the LHC and colliders of future generation." reponame:Repositório Institucional da UFABC, 2016.
Знайти повний текст джерелаАнотація:
Orientador: Prof. Dr. José Kenichi MizukoshiTese (doutorado) - Universidade Federal do ABC, Programa de Pós-Graduação em Física, 2016.
Searches for new physics beyond the Standard Model are important subjects at the current Run-2 of the Large Hadron Collider (LHC) and next generation colliders. In this context, we make independent studies of the phenomenology of a new hypothetical heavy Majorana neutrino (N) and a heavy spin-1 charged vector (W¿) at the LHC and a future 100 TeV very large hadron collider (VLHC), we also study the potential of the future International Linear Collider (ILC) to measure the rare h ! Z Higgs decay. Toward this end, the N production via the W fusion process is investigated and found it to be larger than the Drell-Yan production for mN > 1 TeV at the 14 TeV LHC and for mN > 770 GeV at the 100 TeV VLHC. Then we computed the discovery potential of the these colliders to discover an N using the same-sign dimuon channel. In the case of the h ! Z Higgs decay we investigated the Higgsstrahlung production at the 250 GeV ILC, we found that a sensitivity of 58% can be reached in the inclusive ¿Ê¿Ê X channel with 3 ab.1, where X denotes the inclusive decay of the Z boson from the Higgs. Finally, in the case of the W¿, we studied its contribution to the h ! Higgs decay process and constrained the strength of the W¿W¿h interaction. Finally, we study the Drell-Yan W¿ production with its decay to the Wh pair at the LHC.
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Fischer, Brian C. "Toward Understanding Resonant Volcanic Seismic Signals| Modelling Bubbly Flow in Magma." Thesis, University of Louisiana at Lafayette, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10682056.
Повний текст джерелаАнотація:
An important pursuit in volcanology is more accurate predictions of activity. One promising avenue for that pursuit is resonant seismic signals, and the data inherently contained in their resonance. As there is a strong correlation between such signals and the presence of gas, modelling the behavior of gas bubbles within a magmatic system is a critical step in this journey, as well as toward the overall understanding of the volcanic system.
I modelled clusters of bubbles using Boundary Element Method combined with Fast Multiple Method. The bubbles are three-dimensional polygonal meshes with triangular faces. The models are clusters of nearly 1000 bubbles arranged in rectangular prisms of dimensions 18x24x660, run with the long side at various angles, from 0° to 90°, to simulate bubbles nucleated from fresh magma injected into more mature magma. They were allowed to run until the meshes deformed too much, causing errors that render the simulations unviable from that point onward, which is long enough to see different behaviors emerge.
The models presented here show bubbles that behave in accordance with expectations based off of the properties of the Rayleigh-Taylor instability, which causes upwellings to develop in initially level clusters of buoyant materials, and show that above a critical angle of about 30°, the instability disappears. In addition, this behavior also helps explain processes behind Strombolian activity, with clusters above the critical angle developing into a vertical cluster of evenly-spaced plumes, rather than clusters below the critical angle, which develop into plumes at the same height which would reach the surface at roughly the same time.
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Miller, Corey Alexander. "Intelligent Feature Selection Techniques for Pattern Classification of Time-Domain Signals." W&M ScholarWorks, 2013. https://scholarworks.wm.edu/etd/1539623620.
Повний текст джерелаАнотація:
Time-domain signals form the basis of analysis for a variety of applications, including those involving variable conditions or physical changes that result in degraded signal quality. Typical approaches to signal analysis fail under these conditions, as these types of changes often lie outside the scope of the domain's basic analytic theory and are too complex for modeling. Sophisticated signal processing techniques are required as a result. In this work, we develop a robust signal analysis technique that is suitable for a wide variety of time-domain signal analysis applications. Statistical pattern classification routines are applied to problems of interest involving a physical change in the domain of the problem that translate into changes in the signal characteristics. The basis of this technique involves a signal transformation known as the Dynamic Wavelet Fingerprint, used to generate a feature space in addition to features related to the physical domain of the individual application. Feature selection techniques are explored that incorporate the context of the problem into the feature space reduction in an attempt to identify optimal representations of these data sets.
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Kudrins, Vitalijs. "Development of Software Library for Open Source GNSS Receiver with Focus on Physical Layer Signal Processing." Thesis, Luleå tekniska universitet, Rymdteknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-84772.
Повний текст джерелаАнотація:
In order to directly interface with signal broadcast by global navigation satellite systems (GNSS) – such as GPS or Galileo – for the purpose of calculating location, a potential user is required to extract great amount of information from interface control documents (ICD) as well as build custom software tools to process this information. This is time consuming and inefficient. Instead it would be great if such tools and information was readily available in one single project. This thesis addresses this issue by designing a universal data structure which is able to accommodate all necessary information to interface with any GNSS. Universal GNSS data structure is designed in such a way so that software tools can be entirely generic across all GNSS, i.e. do not include any functionality specific to only one GNSS. This is done by embedding certain logic parameters inside data structure itself, which determine how software tools behave. The data structure realized in the form of XML file with specific rules and syntax. Data from GPS and Galileo ICDs is scraped and compiled into XML file. A Rust tool-set is created to read XML file and extract information such as pseudo-random noise codes and navigation message structure. Using this information, it is possible to decode a raw bit stream broadcast by GNSS spacecraft, although currently additional tools need to be added to completely automatize this process.
39
Pontoni, Angèle. "Evolution of the signal induced by ChemCam on Mars as a function of focus." Thesis, Luleå tekniska universitet, Rymdteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-67735.
Повний текст джерелаАнотація:
ChemCam, mounted on the mast of the Mars Science Laboratory (MSL) rover, uses Laser-Induced Breakdown Spectroscopy (LIBS) to perform remote-sensing science on Mars. ChemCam’s telescope is used to simultaneously focus the laser on martian rocks up to 7 meters away from the rover and collect the light emitted as the plasma plume created on the target cools down. The light is then transmitted to three spectrometers located in the body of the rover, providing spectra from which the composition of the samples is inferred on the ground. Context images of the sampled targets are captured by the Remote Micro Imager (RMI) that completes the instrument. A hardware failure that occurred a bit more than two years into the mission caused the ChemCam instrument to lose its original autofocus ability. This resulted in a degraded performance mode for several months while the ChemCam team developed a new autofocus algorithm based on the RMI images. During this period of degraded performance, several observations with different focus conditions were made on each target. This unusual set of data provides the opportunity to study the influence of less-than-optimal focus conditions on the LIBS signal created on the target and analyzed by ChemCam. To this purpose, we look at both raw ChemCam spectra and post-processed products used for scientific analysis to investigate how the quality of the focus influences the LIBS signal and the quantitative predictions of the composition of the observed targets.
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Wissner-Gross, Zachary Daniel. "Signal variation in single particle aerosol mass spectrometry." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/40921.
Повний текст джерелаАнотація:
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics, 2007.Includes bibliographical references (p. 33-34).
Rapid and accurate detection of airborne micro-particles is currently an important problem in national security. One approach to such detection, bioaerosol mass spectrometry (BAMS), is currently under development at Lawrence Livermore National Laboratory. BAMS is a type of single particle aerosol mass spectrometry that rapidly records dual-polarity mass spectra of aerosolized micro-particles. However, the accuracy of the BAMS system is limited by various uncertainties, resulting in shot-to-shot variations in the mass spectra. I found that the variations in mass peak areas in BAMS spectra were significantly larger than those predicted by Poisson statistics based on the mean number of detected ions. Furthermore, these variations were surprisingly consistent as a function of peak area among synthetic, organic, and biological samples. For both positive and negative ions, the standard deviation in a peak's area was approximately proportional to the mean value of that area to the 0.9 power. Using the consistency of this data, I also developed a novel method for quantitatively evaluating the similarity between mass spectra using a chi-square factor. Peak area variations in other single particle aerosol mass spectrometers may be similarly analyzed and used to improve methods for rapid particle identification.
by Zachary Daniel Wissner-Gross.
S.B.
41
Mettetal, Jerome Thomas II. "Signal processing and decision making in single cells." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/45445.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2008.Includes bibliographical references (p. 199-206).
Cells are not simple passive observers oblivious to their environment, but sense and adapt to environmental changes in order to thrive. In addition to sensing the presence of signals in the environment, cells can extract information relating to the dynamics and spatial location of these signals and implement a response to these extracellular perturbations. This work examines a variety of signal-processing and decision-making processes across several different organisms. To explore the connection between biological network topology and temporal signal processing, we study how periodic signals are propagated in the Hog1 osmotic response pathway of the budding yeast Saccharomyces cerevisiae. Utilizing systems identification tools from control engineering, we study how the cells rapidly and robustly maintain osmotic homeostasis. By measuring the expression level of key proteins we begin to understand how fluctuating environments regulate gene expression. The lac operon in Escherichia coli has the ability to display a bistable, "all-ornothing" response to sugar. To understand how noise drives transitions between these two stable states, we measure switching dynamics in a population of cells. A simple model is constructed that can make predictions about system behavior unavailable from a deterministic model. Further, by measuring individual switching events in a similar bistable system implemented in the Galactose utilization pathway of Saccharomyces cerevisiae, we find that correlations in switching times of related individuals can be explained in terms of correlations in levels of key regulatory proteins. Many single celled organisms, such as the slime mold Dictyostelium discoideum, can sense and respond to concentration gradients of extracellular signaling molecules. We find that the cells' ability to detect an extracellular signal is influenced by an asymmetric intracellular signal, which varies in direction and magnitude from cell-to-cell. Further, a model that accounts for both signals predicts the observed population response to directed stimuli.
(cont.) Finally, we explore a "bet-hedging" strategy for fluctuating environments with an engineered population of Saccharomyces cerevisiae cells that randomly switch between two phenotypes. Each phenotype is fit to one of two alternating environments. We find that to optimize fitness, cells must tune the phenotypic transition rates in accordance with the rate of environmental transitions.
by Jerome Thomas Mettetal, II.
Ph.D.
42
Rapoport, Benjamin Isaac. "Neural prosthetics for paralysis : algorithms and low-power analog architectures for decoding neural signals." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/39289.
Повний текст джерелаАнотація:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Physics, 2007.Includes bibliographical references (leaves 119-122).
This thesis develops a system for adaptively and automatically learning to interpret patterns of electrical activity in neuronal populations in a real-time, on-line fashion. The system is primarily intended to enable the long-term implantation of low-power, microchip-based recording and decoding hardware in the brains of human patients in order to treat neurologic disorders. The decoding system developed in the present work interprets neural signals from the parietal cortex encoding arm movement intention, suggesting that the system could function as the decoder in a neural prosthetic limb, potentially enabling a paralyzed person to control an artificial limb just as the natural one was controlled, through thought alone. The same decoder is also used to interpret the activity of a population of thalami neurons encoding head orientation in absolute space. The success of the decoder in that context motivates the development of a model of generalized place cells to explain how networks of neurons adapt the configurations of their receptive fields in response to new stimuli, learn to encode the structure of new parameter spaces, and ultimately retrace trajectories through such spaces in the absence of the original stimuli.
(cont.) Qualitative results of this model are shown to agree with experimental observations. This combination of results suggests that the neural signal decoder is applicable to a broad scope of neural systems, and that a microchip-based implementation of the decoder based on the designs presented in this thesis could function as a useful investigational tool for experimental neuroscience and potentially as an implantable interpreter of simple thoughts and dreams.
by Benjamin Isaac Rapoport.
S.M.
43
Oliveira, Alexandra Carvalho Antunes de [UNESP]. "New physics from warped compact extra dimensions: from model building to colliders signals." Universidade Estadual Paulista (UNESP), 2014. http://hdl.handle.net/11449/127595.
Повний текст джерелаАнотація:
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000837676.pdf: 5906522 bytes, checksum: 4d7d813fa9837e6b5a068271f434ec38 (MD5)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
No Modelo Padrão que descreve a física das partículas elementares e suas interações o campo de Higgs pode ser imaginado como um campo composto formado por uma força forte ainda desconhecida. Tal hípótese é bastante atrativa para completar o Modelo Padrão a altas energias. Problemas como hierarquia e naturalidade podem ser mais facilmente evitados. No contexto de uma força forte porém métodos de cálculo baseados em expansões perturbativas não tem mais validade. Uma alternativa para entender as propriedades básicas desse tipo de teoria é trabalhar em termos de teorias de gravitacão com dimensões extras. Nesta tese focamos no caso de uma dimensão espacial extra. Características genéricas desse tipo de cenário são a existência de partículas de gravidade massivas, associadas com a métrica penta-dimensional que acopla com o Modelo Padrão para matéria, levando a assinaturas diretas em colisores de partículas (como o LHC no CERN). Tais partículas de gravidade se acoplam com o setor de Higgs. A descoberta do bóson de higgs abriu um novo camp o de investigação para sua detecção direta, no estado final com dois bósons de higgs. Nós usamos técnicas de Monte Carlo para estudar as estratégias de análise que levariam a um melhor reconhecimento de novas ressonâncias que decaem em pares de bósons de higgs em colisores hadrônicos, que podem ser interpretadas como partículas de gravidade massivas. Finalmente apresentamos as buscas experimentais por tais ressonâncias realizadas no contexto do experimento CMS com dados retirados do primeiro run do LHC (com uma energia de centro de massa de 8 TeV)
The Higgs field of the Standard Model theory for elementary particles and interactions can be realized as a composite state from an underlying strong sector. Such hypothesis is very attractive as an ultraviolet completion of the Standard Model since it solves the hierarchy and avoids naturalness problems. The standard perturbative methods cannot be used in the context of strongly interacting theories, however thyose can be broadly describes in terms of extra dimensional models of gravity. We focus on the case of one additional Warped compact Extra Dimension (WED). The generic signatures of this scenario are the manifestation of heavy gravity particles, associated with the five dimensional metric, that couples with the Standard Model matter leading to direct collider signatures. The heavy gravity particles couples to the Higgs sector. The Higgs discovery had oponed a new investigation channel to LHC direct detection that is the di-higgs final state. We use Monte Carlo techniques to study the analysis strategies that would lead to a best recognition of new resonances decaying to a pair of higgses in hadron colliders, that can be interprets as the gravity particles. We finally present resonance searches performed with data taken by the CMS experiment on the 8 TeV LHC run. The results are interpreted as the gravity particles signatures in the WED context
CNPq: 141964/2009-0
44
OLIVEIRA, A. C. A. (. Alexandra Carvalho Antunes). "New physics from warped compact extra dimensions: from model building to colliders signals /." São Paulo, 2014. http://hdl.handle.net/11449/127595.
Повний текст джерелаАнотація:
Orientador: Rogério RosenfeldCo-orientador: Maxime Gouzevich
Banca: Eduardo Pontón Bayona
Banca: André Sznajder
Banca: Sérgio Ferraz Novaes
Banca: Oscar José Pinto Éboli
Resumo: No Modelo Padrão que descreve a física das partículas elementares e suas interações o campo de Higgs pode ser imaginado como um campo composto formado por uma força forte ainda desconhecida. Tal hípótese é bastante atrativa para completar o Modelo Padrão a altas energias. Problemas como hierarquia e naturalidade podem ser mais facilmente evitados. No contexto de uma força forte porém métodos de cálculo baseados em expansões perturbativas não tem mais validade. Uma alternativa para entender as propriedades básicas desse tipo de teoria é trabalhar em termos de teorias de gravitacão com dimensões extras. Nesta tese focamos no caso de uma dimensão espacial extra. Características genéricas desse tipo de cenário são a existência de partículas de gravidade massivas, associadas com a métrica penta-dimensional que acopla com o Modelo Padrão para matéria, levando a assinaturas diretas em colisores de partículas (como o LHC no CERN). Tais partículas de gravidade se acoplam com o setor de Higgs. A descoberta do bóson de higgs abriu um novo camp o de investigação para sua detecção direta, no estado final com dois bósons de higgs. Nós usamos técnicas de Monte Carlo para estudar as estratégias de análise que levariam a um melhor reconhecimento de novas ressonâncias que decaem em pares de bósons de higgs em colisores hadrônicos, que podem ser interpretadas como partículas de gravidade massivas. Finalmente apresentamos as buscas experimentais por tais ressonâncias realizadas no contexto do experimento CMS com dados retirados do primeiro run do LHC (com uma energia de centro de massa de 8 TeV)
Abstract: The Higgs field of the Standard Model theory for elementary particles and interactions can be realized as a composite state from an underlying strong sector. Such hypothesis is very attractive as an ultraviolet completion of the Standard Model since it solves the hierarchy and avoids naturalness problems. The standard perturbative methods cannot be used in the context of strongly interacting theories, however thyose can be broadly describes in terms of extra dimensional models of gravity. We focus on the case of one additional Warped compact Extra Dimension (WED). The generic signatures of this scenario are the manifestation of heavy gravity particles, associated with the five dimensional metric, that couples with the Standard Model matter leading to direct collider signatures. The heavy gravity particles couples to the Higgs sector. The Higgs discovery had oponed a new investigation channel to LHC direct detection that is the di-higgs final state. We use Monte Carlo techniques to study the analysis strategies that would lead to a best recognition of new resonances decaying to a pair of higgses in hadron colliders, that can be interprets as the gravity particles. We finally present resonance searches performed with data taken by the CMS experiment on the 8 TeV LHC run. The results are interpreted as the gravity particles signatures in the WED context
Doutor
45
Do, Van Long. "Sequential detection and isolation of cyber-physical attacks on SCADA systems." Thesis, Troyes, 2015. http://www.theses.fr/2015TROY0032/document.
Повний текст джерелаАнотація:
Cette thèse s’inscrit dans le cadre du projet « SCALA » financé par l’ANR à travers le programme ANR-11-SECU-0005. Son objectif consiste à surveiller des systèmes de contrôle et d’acquisition de données (SCADA) contre des attaques cyber-physiques. Il s'agit de résoudre un problème de détection-localisation séquentielle de signaux transitoires dans des systèmes stochastiques et dynamiques en présence d'états inconnus et de bruits aléatoires. La solution proposée s'appuie sur une approche par redondance analytique composée de deux étapes : la génération de résidus, puis leur évaluation. Les résidus sont générés de deux façons distinctes, avec le filtre de Kalman ou par projection sur l’espace de parité. Ils sont ensuite évalués par des méthodes d’analyse séquentielle de rupture selon de nouveaux critères d’optimalité adaptés à la surveillance des systèmes à sécurité critique. Il s'agit donc de minimiser la pire probabilité de détection manquée sous la contrainte de niveaux acceptables pour la pire probabilité de fausse alarme et la pire probabilité de fausse localisation. Pour la tâche de détection, le problème d’optimisation est résolu dans deux cas : les paramètres du signal transitoire sont complètement connus ou seulement partiellement connus. Les propriétés statistiques des tests sous-optimaux obtenus sont analysées. Des résultats préliminaires pour la tâche de localisation sont également proposés. Les algorithmes développés sont appliqués à la détection et à la localisation d'actes malveillants dans un réseau d’eau potableThis PhD thesis is registered in the framework of the project “SCALA” which received financial support through the program ANR-11-SECU-0005. Its ultimate objective involves the on-line monitoring of Supervisory Control And Data Acquisition (SCADA) systems against cyber-physical attacks. The problem is formulated as the sequential detection and isolation of transient signals in stochastic-dynamical systems in the presence of unknown system states and random noises. It is solved by using the analytical redundancy approach consisting of two steps: residual generation and residual evaluation. The residuals are firstly generated by both Kalman filter and parity space approaches. They are then evaluated by using sequential analysis techniques taking into account certain criteria of optimality. However, these classical criteria are not adequate for the surveillance of safety-critical infrastructures. For such applications, it is suggested to minimize the worst-case probability of missed detection subject to acceptable levels on the worst-case probability of false alarm and false isolation. For the detection task, the optimization problem is formulated and solved in both scenarios: exactly and partially known parameters. The sub-optimal tests are obtained and their statistical properties are investigated. Preliminary results for the isolation task are also obtained. The proposed algorithms are applied to the detection and isolation of malicious attacks on a simple SCADA water network
46
Barr, Giles David. "The separation of signals and background in a nucleon decay experiment." Thesis, University of Oxford, 1987. http://ora.ox.ac.uk/objects/uuid:f06155db-aa60-46dc-8d56-7ee55921e2ff.
Повний текст джерелаАнотація:
Two aspects of the problems encountered in searching for nucleon decay in the Soudan 2 detector are discussed. The types of event which are expected are discussed. The most common are Induced by gamma rays from the naturally occurring radioactive isotopes in the cavern rock. A calculation has been developed to predict the rates of such events in the detector and the results agree well when compared with measurements made underground. Some radioactive events cause Compton scattering in the wireplane region of the detector and prohibit the use of a simple multiplicity trigger. Such events have been studied. An electronic trigger system has been designed which will achieve a factor of 103 rejection of these events while remaining efficient for even the most difficult modes of proton decay (75% for p -> K +V ). It is predicted that radioactive triggers will occur at less than 3Hz when the full detector is operating. The neutrino induced background to proton decay has been simulated. The neutrino flux at the detector caused by cosmic ray induced showers in the atmosphere has been predicted. A comprehensive low energy (0.2 GeV to 20 GeV) Monte-Carlo neutrino event generator has been developed as a tool for background studies to proton decay. The Teinteraction of proton decay or neutrino interaction products in the parent nucleus is discussed. It is found that these reinteractions are quite probable, except for K⁺ and K° particles. Data from a low energy neutrino beam experiment has been studied and it is deduced that in some cases, the events seen in the detector will contain visible tracks associated with the disintegration of the parent nucleus. A background estimate for the mode p ➝ K+V from the neutrino interaction Vn ➝ μ~p is presented.
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Madan, Anuj. "Physical understanding of strained-silicon and silicon-germanium FETs for RF and mixed-signal applications." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/24758.
Повний текст джерелаАнотація:
Thesis (M. S.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2008.Committee Chair: John D. Cressler; Committee Member: John Papapolymerou; Committee Member: Shyh-Chiang Shen.
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Liu, Tingyang. "Concurrent substrate coupling noise modeling and active noise reduction methodology for mixed-signal physical design." Diss., The University of Arizona, 1999. http://hdl.handle.net/10150/284133.
Повний текст джерелаАнотація:
In mixed-signal ICs that integrate complex digital circuits together with high-performance analog circuits, signal contamination caused by substrate coupling noise is a critical issue. Fast digital transients can produce noise harmful to the sensitive analog circuits. The noise can be coupled from noisy devices and interconnects into the common substrate and coupled into analog devices. This noise coupling mechanism poses serious challenges toward the signal integrity of the mixed-signal design. The final performance of the ICs signal integrity is heavily dependent on layout schemes and the effectiveness of using noise reduction techniques. A hierarchical substrate coupling noise modeling technique that uses a gate-level lumped parasitic circuit model (for digital circuit layout) and concurrent real-time stimulating waveforms has been developed. This hierarchical approach make the concurrent substrate coupling noise analysis feasible under the current computational resource limitation. The gate-level parasitic extraction can avoid the intensive computation needed by detailed source/drain level modeling technique while keeping a reasonable accuracy with respect to parasitics. The parasitic extraction is also a separate process from the substrate three-dimensional mesh generation process. Therefore, this modeling technique can be easily used for evaluation of different physical design schemes. An innovate active noise reduction method, using the noise cancellation mechanism during the physical design phase to reduce the substrate coupling noise contamination, has also been developed. The fundamental idea of this method is to use the reversely amplified noise to achieve a "virtual" ground for the substrate. The noise is sampled from the substrate and reversely amplified and then re-injected into the substrate, by this method, up to 90% of the original noise can be eliminated. The active substrate coupling noise reduction method has the merit that it can be used together with traditional noise reduction methods such as guard ring deployment. Several test chips have been designed and fabricated to demonstrate the effectiveness of the substrate modeling and reduction methods. In the results section of this dissertation, results from both SPICE-based simulation and measurement from MOSIS 1.2 micron test chips are presented and analyzed.
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Bloomer, Edward Joseph. "A principal component analysis of gravitational-wave signals from extreme-mass-ratio sources." Thesis, University of Glasgow, 2010. http://theses.gla.ac.uk/1771/.
Повний текст джерелаАнотація:
The Laser Interferometer Space Antenna (LISA) will detect the gravitational wave emissions from a vast number of astrophysical sources, but extracting useful information about individual sources or source types is an extremely challenging prospect; the large number of parameters governing the behaviour of some sources make exhaustively searching this parameter space computationally expensive. We investigate the potential of an alternative approach, with a focus on detecting the presence of particular inspiraling binary source signals within a timeseries of gravitational wave data, and quickly providing estimates of their coalescence times. Specically, we use Principal Component Analysis (PCA) to identify redundancy within the parameter space of Extreme Mass Ratio Inspiral (EMRI) sources and construct a new, smaller parameter space containing only relevant signal information. We then create a simple search method based on how gravitational wave signals project into this new parameter space. Test cases indicate that a small number of principal components span a space occupied by the majority of EMRI spectrograms, but non-EMRI signals (including noise) do not inhabit this space. A PCA-based search method is capable of indicating the presence of gravitational waves from EMRI sources within a new test spectrogram. The results of our PCA-based searches show that the method could be used to provide initial estimates of EMRI coalescence times quickly, to be used as initial data for a more thorough search.
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Yang, Qiong Ph D. Massachusetts Institute of Technology. "Dynamics of gene expression and signal transduction in single cells." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/63008.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2009.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 141-146).
Each individual cell is a highly dynamic and complex system. Characterizing dynamics of gene expression and signal transduction is essential to understand what underlie the behavior of the cell and has stimulated much interest in systems biology. However, traditional techniques based on population averages 'wash out' crucial dynamics that are either out of phase among cells or are driven by stochastic cellular components[34]. In this work, we combined time-lapse microscopy, quantitative image analysis and fluorescent protein reporters, which allowed us to directly observe multiple cellular components over time in individual cells. In conjunction with mathematical models, we have investigated three dynamical systems, two of which are based on a long-term genealogical tracking method. First, we found that stochastic switching between different gene expression states in budding yeast is heritable[29]. This striking behavior only became evident using genealogical information from growing colonies. Our model based on burst induced correlation can explain the bulk of our results. In the next system investigated, we explored the interaction between biological oscillators. Especially, we used an abstract model to describe and predict the synchronization of cell cycles by the circadian clock. Simultaneous measurement of both circadian dynamics and cell cycle dynamics in individual cyanobacteria cells revealed the direct relationships between these two biological clocks and thus provided a clear evidence of 'circadian gating', in which circadian rhythms regulate the timing of cell divisions. Lastly, we studied the robustness of the network dynamics to the sequence changes and the changes of gene expression levels of embedding proteins by characterizing dynamic response of the well-conserved mitogen-activated protein kinase (MAPK) cascade to osmotic shock, combining experimental measurements and theoretical models.
by Qiong Yang.
Ph.D.