Simple and efficient solutions to the problems associated with acoustic echo cancellation

This dissertation is a collection of papers that addresses several important problems associated with acoustic/line echo cancellation (AEC/LEC), specifically double-talk and echo-path change detection. A double-talk detector is used to freeze AEC filter\u27s adaptation during periods of near-end speech. This dissertation presents three different novel double-talk detection schemes. Simulations demonstrate the efficiency of the proposed algorithms --Abstract, page iii

Transmission and Distribution Co-Simulation and Applications

As the penetration of flexible loads and distributed energy resources (DERs) increases in distribution networks, demand dispatch schemes need to consider the effects of large-scale load control on distribution grid reliability. Thus, we need demand dispatch schemes that actively ensure that distribution grid operational constraints are network-admissible and still deliver valuable market services. In this context, this work develops and evaluates the performance of a new network-admissible version of the device-driven demand dispatch scheme called Packetized Energy Management (PEM). Specifically, this work develops and investigates the live grid constraint-based coordinator and metrics for performance evaluation. The effects of grid measurements for a practical-sized, 2,522-bus, unbalanced distribution test feeder with a 3000 flexible kW-scale loads operating under the network-admissible PEM scheme is discussed. The results demonstrate the value of live grid measurements in managing distribution grid operational constraints while PEM can effectively deliver frequency regulation services. Increased penetration of flexible loads and DERs on distribution system (DS) will lead to increased interaction of transmission and distribution (T&D) system operators to ensure reliable operation of the interconnected power grids, as well as the control actions at LV/MV grid in aggregation will have significant impact on the transmission systems (TS). Thus, a need arises to study the coupling of the transmission and distribution (T&D) systems. Therefore, this work develops a co-simulation platform based on decoupled approach to study integrated T&D systems collectively. Additionally, the results of a decoupled method applied for solving T&D power flow co-simulation is benchmarked against the collaborator developed unified solution which proves the accuracy of the decoupled approach. The existing approaches in the literature to study steady-state interaction of TS-DS have several shortcomings including that the existing methods exhibit scalability, solve-time and computational memory usage concerns. In this regard, this work develops comprehensive mathematical models of T&D systems for integrated power flow analysis and brings advancements from the algorithmic perspective to efficiently solve large-scale T&D circuits. Further, the models are implemented in low-cost CPU-GPU hybrid computing platform to further speed up the computational performance. The efficacy of the proposed models, solution algorithms, and their hardware implementation are demonstrated with more than 13,000 nodes using an integrated system that consists of 2383-bus Polish TS and multiple instances of medium voltage part of the IEEE 8,500-node DS. Case studies demonstrate that the proposed approach is scalable and can provide more than tenfold speed up on the solve time of very large-scale integrated T&D systems. Overall, this work develops practically applicable and efficient demand dispatch coordinator able to integrate DERs into DS while ensuring the grid operational constraints are not violated. Additionally, the dynamics introduced in the DS with such integration that travels to TS is also studied collectively using integrated T&D co-simulation and in the final step, a mathematically comprehensive model tackles the scalability, solve-time and computational memory usage concerns for large scale integrated T&D co-simulation and applications

Chemical Profiling Of Exhaled Breath from Cystic Fibrosis Subjects Using Comprehensive Two-Dimensional Gas Chromatography

University of Technology Sydney. Faculty of Science.Chronic lung infections are the leading cause of death in subjects with cystic fibrosis (CF). To date, sputum culture is the most common technique for the diagnosis of lung infections in adult CF subjects. However, it requires several days or longer to obtain culture results. Therefore, a rapid diagnostic technique for lung infections would significantly improve CF healthcare. During recent decades, exhaled breath analysis has attracted interest as a rapid and non-invasive tool for the diagnosis of non-communicable diseases such as cancers and heart diseases. However, there is limited progress in the diagnosis of infectious diseases such as lung infections in CF subjects using volatile organic compounds (VOCs) as biomarkers of infection. In this study, sputum and breath samples were collected from CF subjects and healthy controls (only breath) and profiled for VOCs using comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC×GC–TOFMS). Multivariate analyses (e.g. principal component analysis and linear discriminant analysis (LDA)) were then performed to allow differentiation between: (i) CF subjects and healthy controls and (ii) CF subjects with/without infections and those with no known lung infections as confirmed using their sputum culture results. This study identified a set of 16 VOCs which allowed differentiation between CF subjects and healthy controls. In particular, healthy controls were classified with 98% accuracy, while CF subjects were classified with 92% accuracy. It is important to note that all of the CF subjects that participated in this study are significantly different from control groups, not only in terms of their lung infection status but also in terms of numerous other factors (e.g. diet, lifestyle, medications, and other health complications). These factors can also impact the breath profiles obtained from the study group (CF subjects). The analysis of matching sputum and breath samples collected from CF subjects provided a set of 24 core VOCs common between both sample types. LDA performed using these VOCs provided accurate classification of CF subjects according to their lung infection status (i.e. CF subjects with/without infection). The outcome of LDA also showed that these common VOCs have better classification accuracy than the entire profile of the VOCs detected in sputum and breath samples. Finally, the comparison of breath profiles between CF subjects with/without infection and those with no known lung infection showed that it is also possible to allow differentiation between these contrasting groups using breath VOCs profiles

Weak-Group Unitary Space-Time Codes

We propose a construction technique for unitary space-time codes that use Givens rotation matrices. These constellations have a desirable weak group property that leads to reduced construction and decoding complexity. The newly constructed constellations have the best known diversity product and diversity sum for a wide range of constellation sizes and number of transmit antennas

Early Versus Delayed Feeding in Paediatric Patients Following Stoma Reversal in a Resource Limited Environment

Introduction: Institution of early enteral nutrition is essential after stoma reversal. There is no consensus on the time feeding should be started after closure of a stoma in children. It is established that after stoma reversal early achievement of full feed and early discharge affects the overall cost in resource limited countries. Materials and Methods: This Randomized control trial was conducted in the Paediatric Surgery Department of Services Hospital, Lahore. Over a period of 1 year, from April 2016 to March 2017, a total of 100 cases were included.  In group A, early feeding (after 36 to 48hours) and in group B delayed (after 5days) feeding was given to the patients. Time for restoration of full feed and length of hospital stay and complications were compared in both groups. Each patient was observed in the ward till discharge and followed up to 30 days in the out-patient department. The data was recorded and analyzed in SPSS version 20. Independent sample t-test was applied to obtain the p-value for comparing the means. P-value ≤ 0.05 was considered significant. Results:  In both groups age, weight and etiology of stoma was comparable.  The full feed was achieved within 56.66 ± 7.77 hours in group A and 156.76 ± 7.96 hours in group B (P<0.005). Mean length of hospital stay was 5.84 ± 0.84 days in group A, while it was 9.50 ± 0.76 days in group B (P<0.005). Conclusion: Early enteral feeding after stoma reversal is well tolerated and beneficial. It is suggested that early feeding protocol should be encouraged in a resource limited environment

Variable Regularized Fast Affine Projections

This paper introduces a variable regularization method for the fast affine projection algorithm (VR-FAP). It is inspired by a recently introduced technique for variable regularization of the classical, affine projection algorithm (VR-APA). In both algorithms, the regularization parameter varies as a function of the excitation, measurement noise, and residual error energies. Because of the dependence on the last parameter, VR-APA and VR-FAP demonstrate the desirable property of fast convergence (via a small regularization value) when the convergence is poor and deep convergence/immunity to measurement noise (via a large regularization value) when the convergence is good. While the regularization parameter of APA is explicitly available for on-line modification, FAP\u27s regularization is only set at initialization. To overcome this problem we use noise-injection with the noise-power proportional to the variable regularization parameter. As with their fixed regularization versions, VR-FAP is considerably less complex than VR-APA and simulations verify that they have the very similar convergence propertie

Consumption-Based CO2 Emissions on Sustainable Development Goals of SAARC Region

Consumption-based CO2 emission (CBE) accounting shows the possibility of global carbon leakage. Very little attention has been paid to the amount of emissions related to the consumption of products and services and their impact on sustainable development goals (SDGs), especially in the SAARC region. This study used a CBE accounting method to measure the CO2 emissions of five major SAARC member countries. Additionally, a Fully Modified Ordinary Least Square (FMOLS) and a causality model were used to investigate the long-term effects of the CBE and SDG variables between 1972 and 2015. The results showed that household consumption contributed more than 62.39% of CO2 emissions overall in the SAARC region. India had the highest household emissions, up to 37.27%, and Nepal contributed the lowest, up to 0.61%. The total imported emissions were the greatest in India (16.88 Gt CO2) and Bangladesh (15.90 Gt CO2). At the same time, the results for the long-term relationships between the CBEs and SDGs of the SAARC region showed that only the combustible renewables and waste (CRW) variable is significant for most of these countries. The sharing of the responsibility for emissions between suppliers and customers could encourage governments and policymakers to make global climate policy and sustainable development decisions,which are currently stalled by questions over geographical and past emission inequities

Comparative analysis of chromogenic vs clot based CDC modified, Nijmegen-Bethesda assay for detection of factor viii inhibitor titre

Background:-Inhibitors to infused factor VIII are the most significant complication of hemophilia treatment. These inhibitors are usually IgG antibodies, that react with FVIII in a time and temperature dependent manner. Coagulation factor VIII inhibitors can be detected by Chromogenic, clot based and immunological assays. However, there is lack of consensus as to what constitutes a positive inhibitor, including the appropriate cut-off for inhibitor measurement The main objective of this study is to compare the sensitivity and specificity of chromogenic Nijmegen Bethesda assay (CNBA) with Centre for disease control modified Nijmegen Bethesda (CDC-NBA) assay against the Reference control method (RCM).Materials and Methods: The Coagulometer used for inhibitor titre  quantification is Sysmex CS-5100. APTT reagent used isPathromtin SL supplied by seimensSeimens. All data were expressed as Mean ± SD. Statistical formulae were used for sensitivity and specificity calculations. Unpaired students t test was used whereever necessary and a P value of <0.05 is considered as statistical significanceResults: A total of 150 cases were tested for inhibitor titre using CNBA vs CDC-NBA. For low titre Inhibitor (<2 NBU), CNBA has 92% and 86% and CDC-NBA has 80 and 60% sensitivity and specificity respectively. These results show that CDC-NBA shows false positive results at low inhibitor titre. For High titre Inhibitor ( >2 NBU) CNBA has 88% and 80% and CDC-NBA has 85 and 70 % sensitivity and specificity respectively.Conclusion :- These results shows that CNBA is more sensitive and specific than CDC-NBA at both low and high inhibitor titre. Moreover chromogenic assays can differentiate factor specific inhibitor from nonspecific inhibitors like lupus anticoagulant and unfractionated heparin therapy.Keywords: Hemophilia, Bethesda assay, ELISA, Factor VIII, Inhibitor, Mixing studyAbbrevations: APLA- Antiphospholipid antibody syndrome, CDC:NBA- Centers for Disease Control and Prevention - Nijmegen-BethesdaAssay, CNBA:- chromogenic Nijmegen Bethesda assa

Linear and Nonlinear Noise Characterisation of Dual Stage Broadband Discrete Raman Amplifiers

We characterise the linear and nonlinear noise of dual stage broadband discrete Raman amplifiers (DRAs) based on conventional Raman gain fibres. Also, we propose an optimised dual stage DRA setup that lowers the impact of nonlinear noise (generated in the amplifier) on the performance of a transmission link (with 100-km amplifier spacing). We numerically analyse the design of a backward pumped cascaded dual stage 100-nm DRA with high gain (∼20 dB) and high saturated output power (>23 dBm). We show that the noise figure (NF) of the dual stage DRA is mainly dominated by the first stage irrespective of the type of gain fibre chosen in the second stage, and we also demonstrate that optimising the length and the type of Raman gain fibre can have significant impact on the size of inter/intrasignal nonlinearities generated. Here, we report a theoretical model to calculate the nonlinear noise power generated in transmission spans with dual stage DRAs considering piecewise signal power evolution through the Raman gain fibres. The predicted signal-to-noise ratio (SNR) performances are calculated from the combined contributions from NF and nonlinear product power obtained using the proposed analytical model for transmission systems deployed with 100-km transmission span compensated by different dual stage DRAs. Finally, an optimised IDF 6 km-SMF 10 km dual stage configuration has been identified using the theoretical model, which allows maximum SNR of 14.6 dB at 1000 km for 1 THz Nyquist wavelength division multiplexed signal and maximum transmission reach of 3400 km at optimum launch power assuming 8.5 dB HD-FEC limit of the Nyquist PM-QPSK signal