Development and implementation of image fusion algorithms based on wavelets

Image fusion is a process of blending the complementary as well as the common features of a set of images, to generate a resultant image with superior information content in terms of subjective as well as objective analysis point of view. The objective of this research work is to develop some novel image fusion algorithms and their applications in various fields such as crack detection, multi spectra sensor image fusion, medical image fusion and edge detection of multi-focus images etc. The first part of this research work deals with a novel crack detection technique based on Non-Destructive Testing (NDT) for cracks in walls suppressing the diversity and complexity of wall images. It follows different edge tracking algorithms such as Hyperbolic Tangent (HBT) filtering and canny edge detection algorithm. The second part of this research work deals with a novel edge detection approach for multi-focused images by means of complex wavelets based image fusion. An illumination invariant hyperbolic tangent filter (HBT) is applied followed by an adaptive thresholding to get the real edges. The shift invariance and directionally selective diagonal filtering as well as the ease of implementation of Dual-Tree Complex Wavelet Transform (DT-CWT) ensure robust sub band fusion. It helps in avoiding the ringing artefacts that are more pronounced in Discrete Wavelet Transform (DWT). The fusion using DT-CWT also solves the problem of low contrast and blocking effects. In the third part, an improved DT-CWT based image fusion technique has been developed to compose a resultant image with better perceptual as well as quantitative image quality indices. A bilateral sharpness based weighting scheme has been implemented for the high frequency coefficients taking both gradient and its phase coherence in accoun

Single-Photon Generation via Four-Wave Mixing in a Thermal Rubidium Vapour at a High Magnetic Field

We present investigations of the nonlinear optical phenomenon of four-wave mixing (4WM) in a thermal vapour at a high magnetic field. The 5S$_{1/2}$, 5P$_{1/2}$, 5P$_{3/2}$, and 5D$_{3/2}$ terms in rubidium-87 are used. In a 0.62 T field, the optical transitions become separated by more than their Doppler width, effectively isolating a four-level system. Spontaneous 4WM in this system is used to generate herald-signal photon pairs and to realise a heralded single-photon source, as demonstrated by a Hanbury Brown—Twiss (HBT) experiment giving a $g^{(2)}(0)$ value of 0.35~$\pm$~0.02. We show that an increased correlation between herald and signal leads to a $g^{(2)}(0)$ value closer to zero, and we investigate the parameters that increase this correlation. We additionally characterise the parameters in the seeded 4WM system and show that working in the hyperfine Paschen—Back (HPB) regime leads to a good agreement between theory and experiment. The splitting of the seeded 4WM lineshape is used to extract an excited state dipole matrix element. We also study the background photons in our system, showing that they are partly a result of a collisional transfer process. We build a bespoke etalon lens filter to aid in filtering out these photons and show that the use of this filter improves the correlation between herald-signal photon pairs. In order to perform HBT experiments that take over twenty-four hours to run, we devise a novel laser locking scheme, named STROLL, that simultaneously stabilises the frequencies of two lasers to a two-photon transition over that time period. Difficulty with optimising the alignment of photons into a fibre leads us to also develop an innovative method of using machine learning for automatically aligning laser beams; we implement this method on a physical device, which we have named the Pi Auto-aligner

Data classification methodology for electronic noses using uniform manifold approximation and projection and extreme learning machine

The classification and use of robust methodologies in sensor array applications of electronic noses (ENs) remain an open problem. Among the several steps used in the developed methodologies, data preprocessing improves the classification accuracy of this type of sensor. Data preprocessing methods, such as data transformation and data reduction, enable the treatment of data with anomalies, such as outliers and features, that do not provide quality information; in addition, they reduce the dimensionality of the data, thereby facilitating the tasks of a machine learning classifier. To help solve this problem, in this study, a machine learning methodology is introduced to improve signal processing and develop methodologies for classification when an EN is used. The proposed methodology involves a normalization stage to scale the data from the sensors, using both the well-known min-max approach and the more recent mean-centered unitary group scaling (MCUGS). Next, a manifold learning algorithm for data reduction is applied using uniform manifold approximation and projection (UMAP). The dimensionality of the data at the input of the classification machine is reduced, and an extreme learning machine (ELM) is used as a machine learning classifier algorithm. To validate the EN classification methodology, three datasets of ENs were used. The first dataset was composed of 3600 measurements of 6 volatile organic compounds performed by employing 16 metal-oxide gas sensors. The second dataset was composed of 235 measurements of 3 different qualities of wine, namely, high, average, and low, as evaluated by using an EN sensor array composed of 6 different sensors. The third dataset was composed of 309 measurements of 3 different gases obtained by using an EN sensor array of 2 sensors. A 5-fold cross-validation approach was used to evaluate the proposed methodology. A test set consisting of 25% of the data was used to validate the methodology with unseen data. The results showed a fully correct average classification accuracy of 1 when the MCUGS, UMAP, and ELM methods were used. Finally, the effect of changing the number of target dimensions on the reduction of the number of data was determined based on the highest average classification accuracy.This work was funded in part with resources from the Fondo de Ciencia, Tecnología e Innovación (FCTeI) del Sistema General de Regalías (SGR) from Colombia. The authors express their gratitude to the Administrative Department of Science, Technology, and Innovation–Colciencias with the grant 779–“Convocatoria para la Formación de Capital Humano de Alto Nivel para el Departamento de Boyacá 2017” for sponsoring the research presented herein. This study has been partially funded by the Spanish Agencia Estatal de Investigación (AEI)-Ministerio de Economía, Industria y Competitividad (MINECO), and the Fondo Europeo de Desarrollo Regional (FEDER) through research projects DPI2017-82930-C2-1-R and PGC2018-097257-B-C33; and by the Generalitat de Catalunya through research projects 2017-SGR-388 and 2017-SGR-1278.Peer ReviewedPostprint (published version

Millimeter-Wave Super-Regenerative Receivers for Wireless Communication and Radar

Today’s world is becoming increasingly automated and interconnected with billions of smart devices coming online, leading to a steep rise in energy consumption from small microelectronics. This coincides with an urgent push to transform global energy production to green energies, causing disruptions and energy shortages, and making the case for efficient energy use ever more pressing. Two major areas where high growth is expected are the fields of wireless communication and radar sensors. Millimeter-wave frequency bands are planned for fifth-generation (5G) and sixth-generation (6G) cellular communication standards, as well as automotive frequency-modulated continuous wave (FMCW) radar systems for driving assistance and automation. Fast silicon-based technologies enable these advances by operating at high maximum frequencies, such as the silicon-germanium (SiGe) heterojunction bipolar transistor (HBT) technologies. However, even the fastest transistors suffer from low and energy expensive gains at millimeter-wave frequencies. Rather than incremental improvements in circuit efficiency using conventional approaches, a disruptive revolution for green microelectronics could be enabled by exploring the low-power benefits of the super-regenerative receiver for some applications. The super-regenerative receiver uses a regenerative oscillator circuit to increase the gain by positive feedback, through coupling energy from the output back into the input. Careful bias and control of the circuit enables a very large gain from a small number of transistors and a very low energy dissipation. Thus, the super-regenerative oscillator could be used to replace amplifier circuits in high data rate wireless communication systems, or as active reflectors to increase the range of FMCW radar systems, greatly reducing the power consumption. The work in this thesis presents fundamental scientific research into the topic of energy-efficient millimeter-wave super-regenerative receivers for use in civilian wireless communication and radar applications. This research work covers the theory, analysis, and simulations, all the way up to the proof of concept, hardware realization, and experimental characterization. Analysis and modeling of regenerative oscillator circuits is presented and used to improve the understanding of the circuit operation, as well as design goals according to the specific application needs. Integrated circuits are investigated and characterized as a proof of concept for a high data rate wireless communication system operating between 140–220 GHz, and an automotive radar system operating at 60 GHz. Amplitude and phase regeneration capabilities for complex modulation are investigated, and principles for spectrum characterization are derived. The circuits are designed and fabricated in a 130 nm SiGe HBT technology, combining bipolar and complementary metal-oxide semiconductor (BiCMOS) transistors. To prove the feasibility of the research concepts, the work achieves a wireless communication link at 16 Gbit/s over 20 cm distance with quadrature amplitude modulation (QAM), which is a world record for the highest data rate ever reported in super-regenerative circuits. This was powered by a super-regenerative oscillator circuit operating at 180 GHz and providing 58 dB of gain. Energy efficiency is also considerably high, drawing 8.8 mW of dc power consumption, which corresponds to a highly efficient 0.6 pJ/bit. Packaging and module integration innovations were implemented for the system experiments, and additional broadband circuits were investigated to generate custom quench waveforms to further enhance the data rate. For radar active reflectors, a regenerative gain of 80 dB is achieved at 60 GHz from a single circuit, which is the best in its frequency range, despite a low dc power consumption of 25 mW

A wide dynamic range high-q high-frequency bandpass filter with an automatic quality factor tuning scheme

An 80 MHz bandpass filter with a tunable quality factor of 16∼44 using an improved transconductor circuit is presented. A noise optimized biquad structure for high-Q, high- frequency bandpass filter is proposed. The quality factor of the filter is tuned using a new quality factor locked loop algorithm. It was shown that a second-order quality factor locked loop is necessary and sufficient to tune the quality factor of a bandpass filter with zero steady state error. The accuracy, mismatch, and sensitivty analysis of the new tuning scheme was performed and analyzed. Based on the proposed noise optimized filter structure and new quality factor tuning scheme, a biquad filter was designed and fabricated in 0.25 μm BiCMOS process. The measured results show that the biquad filter achieves a SNR of 45 dB at IMD of 40 dB. The P-1dB compression point and IIP3 of the filter are -10 dBm and -2.68 dBm, respectively. The proposed biquad filter and quality factor tuning scheme consumes 58mW and 13 mW of power at 3.3 V supply.Ph.D.Committee Chair: Allen Phillip; Committee Member: Hasler Paul; Committee Member: Keezer David; Committee Member: Kenny James; Committee Member: Pan Ronghu

Classical ghost imaging with opto-electronic light sources: novel and highly incoherent concepts

In conventional imaging systems, the emitted light from a source interacts with an object and the intensity of the transmitted or reflected light is captured by a spatially resolving detector. In this thesis, a fundamentally different imaging principle has been studied, known as ghost imaging (GI). In contrast to conventional imaging, GI exploits the intensity correlations of light to form an image of an object. A ghost image is obtained by measuring the total intensity of the transmitted or reflected light of an illuminated object and the spatially resolved intensity of a highly-correlated reference beam which itself has never interacted with the object. The information of both intensities alone is not enough to form an image of the object. However, image reconstruction can be achieved by correlating the two intensities. Intriguingly, the spatial resolution of the ghost image is provided by the non-interacting reference beam. The work presented in this thesis joins into the continuous strive for making GI applicable to real-world sensing and imaging fields. The title: Classical ghost imaging with opto-electronic emitters, reflects one of the approaches to this objective. The second approach is what rather sets this thesis apart from other ongoing work on GI. Instead of utilizing state-of-the-art detection systems, novel GI configurations are developed

A Novel Low Complexity On body CVD Classifier ASIC Design Methodology

Due to increasing rate of cardiac disorders in developed and developing countries Continuous on body monitoring of ECG signal using the concept of IoT and Body Sensor Network has become the necessity. In this work we are proposing a novel low complex, low power algorithm and architecturefor E.C.G. classification which can be incorporated in present era of IOT and Body Sensor Network. Rather than going for Artificial Intelligence based pattern matching and complex DSP algorithm we have used the simplicity of Hurst exponent and Haar wavelet for filtering out anomalous E.C.G. signals and normal ones

Joint project: Retention of radionuclides relevant for final disposal in natural clay rock and saline systems: Subproject 2: Geochemical behavior and transport of radionuclides in saline systems in the presence of repository-relevant organics

The objective of this project was to study the influence of increased salinities on interaction processes in the system radionuclide – organics – clay – aquifer. For this purpose, complexation, redox, sorption, and diffusion studies were performed under variation of the ionic strength (up to 4 mol/kg) and the background electrolyte. The U(VI) complexation by propionate was studied in dependence on ionic strength (up to 4 mol/kg NaClO4) by TRLFS, ATR FT-IR spectroscopy, and DFT calculations. An influence of ionic strength on stability constants was detected, depending on the charge of the respective complexes. The conditional stability constants, determined for 1:1, 1:2, and 1:3 complexes at specific ionic strengths, were extrapolated to zero ionic strength. The interaction of the bacteria Sporomusa sp. MT-2.99 and Paenibacillus sp. MT-2.2 cells, isolated from Opalinus Clay, with Pu was studied. The experiments can be divided into such without an electron donor where biosorption is favored and such with addition of Na-pyruvate as an electron donor stimulating also bioreduction processes. Moreover, experiments were performed to study the interactions of the halophilic archaeon Halobacterium noricense DSM-15987 with U(VI), Eu(III), and Cm(III) in 3 M NaCl solutions. Research for improving process understanding with respect to the mobility of multivalent metals in systems containing humic matter was focused on the reversibility of elementary processes and on their interaction. Kinetic stabilization processes in the dynamics of humate complexation equilibria were quantified in isotope exchange studies. The influence of high salinity on the mobilizing potential of humic-like clay organics was systematically investigated and was described by modeling. The sorption of Tc(VII)/Tc(IV) onto the iron(II)-containing minerals magnetite and siderite was studied by means of batch sorption experiments, ATR FT-IR and X-ray absorption spectroscopy. The strong Tc retention at these minerals could be attributed to surface-mediated reduction of Tc(VII) to Tc(IV). An influence of ionic strength was not observed. The influence of ionic strength (up to 3 mol/kg) and background electrolyte (NaCl, CaCl2, MgCl2) on U(VI) sorption onto montmorillonite was studied. The U(VI) sorption is influenced by the background electrolyte, the influence of ionic strength is small. Surface complexation modeling was performed applying the 2SPNE SC/CE model. Surface complexation constants were determined for the NaCl and CaCl2 system and were extrapolated to zero ionic strength. Surface complexation in mixed electrolytes can be modeled applying surface complexation constants derived for pure electrolytes. The influence of citrate on U(VI) diffusion in Opalinus Clay was studied using Opalinus Clay pore water as background electrolyte. The diffusion parameter values obtained for the HTO through-diffusion and the U(VI) in-diffusion in the absence of citric acid were in agreement with literature data. In the presence of citric acid, U(VI) diffusion was significantly retarded, which was attributed to a change in speciation, probably U(VI) was reduced to U(IV). Larger-scale heterogeneous material effects on diffusive transport were investigated with PET. Diffusion parameters were derived by optimum fit of a FEM-model to the measurement. These parameters are in accordance with the results from 1D-through-diffusion experiments. Deviations from the simple transversal-isotropic behavior, which are identified as residuals from the model, are indications for heterogeneous transport on the mm-scale. PET measurements were also conducted in order to display the improvement of the EDZ with waterglass injections. These experiments enable to draw conclusions on the complex reactive transport process and thus an estimation of the achieved improvement of the barrier function. The image reconstruction procedure was largely improved, mainly with the aid of Monte-Carlo simulations, and now allows quantitative analysis and error estimation

Time resolved fluorescence of CdSe nanocrystals using single molecule spectroscopy

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2005.Vita.Includes bibliographical references.A wide variety of spectroscopic studies of CdSe nanocrystals (NCs) are presented in this thesis, all studying some aspect of the temporal evolution of NC fluorescence tinder different conditions. In particular the methods of single molecule spectroscopy are used in many experiments allowing the behavior of individual NCs to be resolved from the blurring effect of averaging over the ensemble. Studies of the excited state lifetime of band edge fluorescence from single NCs reveal multiexponential relaxation dynamics that stem from fluctuations of non-radiative decay rates for the band edge exciton. Analysis of these fluctuations allows us to extract single exponential dynamics by sampling only "maximum-intensity" photons, and we find that this single exponential decay is remarkably uniform across a wide variety of NC samples and sizes. We also investigate luminescence from multiexciton (e.g. biexciton and triexciton) states of nanocrystals at both the ensemble and single NC level.(cont.) Energy splittings, size and temperature dependencies, quantum yields and lifetimes of multiexciton states are measured and discussed. We show for the first time direct resolution of biexciton emission from single exciton emission using two different techniques, fluorescence line narrowing and single NC spectroscopy. We also study the non-classical light emission properties of single NCs and show how multiexciton emission leads to radiative quantum cascades of single photons in the emission of a single NC. Time resolved studies of fluorescence from NCs in solution environments conclude the thesis. The relationship between lifetime and quantum yield for non-homogeneous ensembles like NCs is studied in chapter 8. We show that a sub-population of non-luminescent nanocrystals can reduce the quantum yield of an ensemble of NCs even though the measured lifetime stays constant. A study of NCs in solution fluorescence correlation spectroscopy (FCS) is presented last. We find that FCS is a capable tool for distinguishing small differences in hydrodynamic radius of NCs in solution. We also find that blinking of NCs may have a significant impact on these FCS measurements.(cont.) An appendix to this thesis presents a general summary the lifetime of various samples CdSe and CdTe NCs.by Brent R. Fisher.Ph.D