No description available.

A new glucose affinity sensor based on a homogeneous fluorescence resonance energy transfer (FRET) assay system was developed to monitor the competitive binding between concanavalin A (ConA) and dextran. The FRET quenching kinetics of the donor were analyzed from frequency-domain (FD) measurements as functions of both glucose and acceptor-protein concentrations using a Förster-type decay kinetics model. The results showed that the FD measurements and donor decay kinetics can indicate quantitative changes in the presence of glucose at concentrations ranging from 0 to 224 mg/dL. The second set of experiments proved the feasibility of performing analyte sensing with FD lifetime spectroscopy using microsphere-based sensors in multiple scattering solutions. A well characterized pH-sensitive fluorophore was entrapped in poly(ethylene glycol) microspheres. The particles were then immersed in a buffered polystyrene solution of various pH. Measurements of phase shift and modulation of the generated and multiply scattered fluorescent light were acquired as the modulation frequency of the incident excitation light varied from 10 to 120 MHz. After the measured data were analyzed with the coupled diffusion equations, the obtained lifetimes from the scattering measurements matched values from non-scattering measurements. Lastly, a new two-speed Monte Carlo (MC) simulation was developed to predict light propagation through the sensors and thus was used to evaluate these sensors and to design these sensors for implantation. The model used random packing structure and considered geometric optics and two light propagation speeds. Experimental measurements of phase-shift and modulation of excitation light were made on a cubic phantom with non-fluorescent resin microspheres of 74 µm diameter, and compared to those computed from the MC simulation. The results showed that the mean phase shift (PS) deviation was 0.736° and the mean amplitude deviation was 42%. Quantitative changes in detected fluorescence phase-shift and modulation were investigated for microsphere diameter, volume fraction, refractive index, and fluorophore lifetime. We also found that even though the sensitivity of PS change in the presence of scattering was the same as the value without scattering, the values of PS were magnified due to the scattering effects.

Abstract This thesis applies the method of finite-difference frequency -domain to solve the field when light propagating through the optical waveguide. Comparing with other method, method of finite-difference time-domain which required to be calculated with larger matrices and without any ideal approximate rapid solution, our method only needs to solve the joint equations. Method of finite-difference frequency -domain will be more efficient than method of finite- difference time-domain in optical waveguide simulation. However, all that we need to confer with are how to sample the effective indices for set grind points and the deal for the boundary conditions in partial differential equations, including electric wall, magnetic wall, absorption boundary and other boundary conditions, etc. Next, we confer with the difference deal between TE and TM waves respectively. Final, we confer with high-order finite-difference and the method for calculating extremely large area or extremely high precision in order to use the method of finite-difference frequency-domain to find the incident, reflective, and scattering fields by the fastest and the exactest procedures.

Single Carrier Frequency Domain Equalization (SC-FDE) utilize Time Division multiple Access with Zero-padding under ultra-wideband¡Ait can improve Inter-Block Interference(IBI) and Multi-Access Interference(MAI) to get good performance¡AThis system even can eliminate multi-access interference. Concept of TDMA can avoid the same time to transmit different user¡¦s data with zero-padding algorithm. This method can efficiency to solve multi-access interference. In this thesis, we will utilize property of two dimension to solve multi-access interference between each others. Zero-padding have good capability the same to Cyclic prefix and can save transmitter power. In this thesis, we will not use CDMA of method because it do not need to much analysis of mathematics, moreover, we can provide low cost and low complexity for system to get low error rate. Finally we to be aimed at improve IBI and MAI to simulation under ultra-wideband, then simulation will show thesis of method is high performance than traditional of method.

A continuous formulation to calculate the dynamic stiffness matrix of structural members with distributed masses is presented in detail and verified with some simple examples. The dynamic model of a specific bridge (the Marga-Marga bridge in Chile) was developed using this formulation, and the model was then used to obtain the transfer functions of the motions at different points of the bridge due to seismic excitation. The model included rubber pads, used for base isolation, as additional members. The transfer functions were obtained with and without rubber pads to investigate their effect. The dynamic stiffness of complete pile foundations was calculated by a semi-analytical solution with Poulos?? assumption. General observations on group effects under various conditions were obtained from the result of these studies. The dynamic stiffness of the pile foundations for the Marga-Marga bridge was then obtained and used to study the soil structure interaction effects on the seismic response of the bridge. Records obtained during a real earthquake were examined and interpreted in light of the results from all these analyses. Finally, conclusions and recommendations on future studies are presented.

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There has been explosion in the number of digital hearing aids on the market in the last five years. This master thesis deals with some basic issues related to Digital Hearing Aids and more specifically, with the matter of compression in hearing aid devices. The classic frequency-domain compression uses FFT processing and the ideal and practical FFT systems are described. The underlying theory of Multirate Filter Banks and the Polyphase Decomposition as an efficient way of implementing them are presented. A different prototype filter design is thoroughly described and is proposed since it provides a minimum combined approximation error. Moreover, the approximation of the time-domain post filter with gain coefficients being adapted at the frequency domain is done by an all pole filter of lower degree. The simulation results provide us an evaluation of the proposed technique. Our contribution has been the design of a low-delay FIR filter which is extremely crucial for real-time speech processing applications. / Η τεχνολογία ακουστικών βαρηκοΐας έχει προχωρήσει δραματικά τα τελευταία χρόνια. Η εισαγωγή της Ψηφιακής Επεξεργασίας Σήματος (DSP) στα ακουστικά βαρηκοΐας έχει οδηγήσει σε προχωρημένους αλγορίθμους επεξεργασίας σήματος στους τομείς της έρευνας και της αγοράς. Στη παρούσα μεταπτυχιακή εργασία, ασχολούμαστε με το ζήτημα της συμπίεσης στα Ψηφιακά Ακουστικά Βαρηκοΐας δηλαδή τη μείωση του εύρους των επιπέδων του ήχου που βρίσκονται στο περιβάλλον έτσι ώστε να «ταιριάζουν» μέσα στο περιορισμένο εύρος ενός ατόμου με μειωμένη ακοή. Παραθέτουμε μια μελέτη πάνω στις υπάρχουσες τεχνικές συμπίεσης στο συχνοτικό πεδίο με χρήση FFT (Fast Fourier Transform) για τη σχεδίαση συστημάτων συμπίεσης. Στη συνέχεια, κάνοντας μια εισαγωγή στις τράπεζες φίλτρων (Filter Banks) προτείνουμε τη σχεδίαση ενός prototype φίλτρου με μικρό σφάλμα προσέγγισης, απότομη ζώνη μετάβασης και υψηλή εξασθένιση στη ζώνη αποκοπής. Με αυτό τον τρόπο, η προτεινόμενη τεχνική σχεδίασης παρέχει σημαντικό κέρδος σε αντιπαράθεση με την προτεινόμενη τεχνική με χρήση FFT καθότι οδηγεί σε μείωση της διαρροής ενέργειας μεταξύ γειτονικών συχνοτικών ζωνών. Επιπλέον, μελετήθηκε και αξιολογήθηκε η προσέγγιση του FIR φίλτρου των κερδών συμπίεσης από ένα IIR Auto-Regressive φίλτρο μικρότερης τάξης. Η συμβολή μας στο σημείο αυτό είναι η σχεδίαση ενός FIR φίλτρου συμπίεσης με χαμηλή καθυστέρηση. Το χαρακτηριστικό της χαμηλής καθυστέρησης είναι ιδιαίτερα σημαντικό σε εφαρμογές σημάτων ομιλίας πραγματικού χρόνου όπως στη περίπτωση των ακουστικών βαρηκοΐας.

No description available.

The TLM was initially formulated and developed in the time domain. One key issue in a time domain analysis approach is the computational efficiency, where a single impulsive excitation could yield information over a wide frequency range. Also, it may be more natural and realistic to model non linear and frequency dispersive properties in the time domain rather than in the frequency domain. However, in some circumstances, frequency domain analysis may be more appealing. This might be due to the fact that the traditional teaching of electromagnetics emphasizes frequency domain concepts as frequency dispersive constitutive parameters, complex frequency dependent impedances and reflection coefficients. It might be even easier and more direct to be able to model these parameters in frequency domain rather than trying to synthesize an equivalent time domain model. The only limitation of frequency domain analysis, is that the analysis has to be repeated at every frequency point in the frequency range of interest. In this work, a new frequency domain TLM (FDTLM) approach is introduced which combines the superior features of both the time domain and the frequency domain TLM. The approach is based on a steady state analysis in the frequency domain using transient analysis techniques and hence is referred to as TFDTLM. In this approach, the link lines impedances are derived in the frequency domain and are chosen to model the frequency dispersive material parameters. The impedances and propagation constants are allowed to be complex and frequency dependent. Consequently, the TFDTLM can provide more accurate modeling for wave propagation in a frequency dispersive medium. The approach was inspired by the concept of bounce diagram in the time domain and the equivalent frequency domain bounce diagram. To make the TFDTLM approach computationally efficient as compared to other frequency domain TLM approaches, it was critical to maintain some relationship between the mesh response at one frequency point and any other frequency point. The goal was to be able to extract all the frequency domain information in a wide frequency range by performing only one simulation. To achieve this, the transitions between two adjacent cell in all media expressed by (exp(-gamma*L)) have to be expressed in terms of the propagation factor of some reference medium chosen to be the medium with the least propagation delay. This was done with the aid of a digital filter approximation that can be implemented iteratively inside the TLM mesh. The filter can be thought of as some type of compensation equivalent to the stubs in a time domain TLM, yet more accurate and more general. An important advantage of the TFDTLM is that it can easily be interfaced with existing time domain TLM schemes as well as absorbing boundary conditions originally developed for time domain TLM with the slightest modifications. The TFDTLM is implemented a three dimensional mesh and the superior performance of the new approach in modeling lossy inhomogeneous media is demonstrated. The new approach in addition to being computationally efficient as compared to other frequency domain TLM methods, has proven to have superior dispersion behavior in modeling lossy inhomogeneous media as compared to time domain TLM . / Ph. D.

A method, termed the fixed-poles method, is proposed to increase the spatial resolution of experimental modal analysis results so that the resolution of the results is typical of that found in finite element modelling. The fixed-poles procedure estimates the structure’s poles from a high frequency density, driving point frequency response function (FRF) measured with an accelerometer. Mode vectors are estimated from low frequency density, tightly spaced FRFs measured with a scanning laser velocimeter (SLV) using the poles estimated from the accelerometer FRF. In experiments with a beam, the SLV was used to measure the frequency response of the beam at 31 frequencies and 472 locations. A single, 800 frequency line FRF was measured with an accelerometer, and the locations of the system’s poles were estimated from the accelerometer FRF using the Rational Polynomial algorithm. Mode vectors were then estimated from the 472 SLV FRFs for the first 6 modes (1 rigid body + 5 flexible). A comparison of the results was given between the proposed method and a standard global parameter estimation technique. An investigation of the effect of the locations of the 31 measurement frequencies relative to resonances was also given. Conclusions were that the proposed method gives comparable results to a global approach in which the system’s poles were calculated only from the SLV measurements. The computational time required for the fixed-poles analysis proved to be significantly less than the global analysis, and the best results were obtained using near resonance SLV measurement frequencies. / Master of Science