Artificial Neural Network and Wavelet Features Extraction Applications in Nitrate and Sulphate Water Contamination Estimation

This work expounds the review of non-destructive evaluation using near-field sensors and its application in environmental monitoring. Star array configuration of planar electromagnetic sensor is explained in this work for nitrate and sulphate detection in water. The experimental results show that the star array planar electromagnetic sensor was able to detect nitrate and sulphate at different concentrations. Artificial Neural Networks (ANN) is used to classify different levels of nitrate and sulphate contaminations in water sources. The star array planar electromagnetic sensors were subjected to different water samples contaminated by nitrate and sulphate. Classification using Wavelet Transform (WT) was applied to extract the output signals features. These features were fed to ANN consequently, for the classification of different levels of nitrate and sulphate concentration in water. The model is capable of distinguishing the concentration level in the presence of other types of contamination with a root mean square error (RMSE) of 0.0132 or 98.68% accuracy

Method for theoretically determining the locus and location of the transmission zeros in microwave filter networks

This dissertation presents a theoretical investigation of a practical method to determine quantitatively the locations and loci of complex transmission zeros (TZ\u27s) of positively and negatively cross-coupled RF or microwave bandpass filter networks. Bandpass filters can be effectively designed by adjusting the locations of TZ\u27s in the complex s-domain. To locate TZ\u27s, this practical method uses chain matrices for subsystems (discrete parts of the network) of the filter network, and can be extended to other types of filters with cross-coupled sections. An important result is that a complex doublet, triplet and/or quadruplet, (one-, two-, or four-pairs) of TZ\u27s are shown to result solely from the cross-coupled portion of the circuit. The several closed-forms of expressions called the TZ characteristic equation (TZCE) are obtained in terms of element values of the filter network. The locations and loci of TZ\u27s are obtained by solving the relevant equations. These TZCE\u27s are derived by taking advantage of the bridged-T structure for the cross-coupled part. The reason for this dissertation is to locate TZ\u27s without having to evaluate the entire transfer function, with all the infinite and DC TZ\u27s as well as the transmission poles (TP\u27s). In the first chapter, definitions of voltage transfer function and chain (ABCD) matrix are discussed to investigate terminated two-port system. The relation between cascaded chain matrices and voltage transfer function is shown. In the second chapter, a practical bandpass filter network with cross-coupled element is discussed in great detail. The derivations of TZ characteristic equations, the solutions of the equations, and the locations and loci of the TZ\u27s are discussed so that this approach can be extended to generalized networks, including those consisting of combinations of lumped and distributed elements. The transfer function results from a concatenation of chain matrices, and it is expressed as a ratio of rational polynomials, with PR and Hurwitz properties. The reduction of the transfer function into factored polynomials allows for location and identification of TZ\u27s. In the third and fourth chapters, the application of the theory is discussed. The denominator characteristic equation (CE) is solved to locate reflection zeros (RZ\u27s), referred to here in as transmission poles (TP\u27s). Note that this identity (TP\u27s == RZ\u27s) pertains only to the lossless cases. Further examination of lossy networks is part of the work planned in the future. Several examples of networks are introduced to find out location and locus of the transmission zeros, by directly considering the cancellation of the common terms in the numerator and denominator polynomials to obtain the canonical expressions of characteristic equations

Mechanics and applications of stretchable serpentine structures

Stretchable structures have been developed for various applications, including expandable coronary stents, deployable sensor networks and stretchable bio-mimetic and bio-integrated electronics. High-performance, stretchable electronics have to utilize high-quality and long-lasting inorganic electronic materials such as silicon, oxide dielectrics and metals, which are intrinsically stiff and often brittle. It is therefore an interdisciplinary challenge to make inorganic electronics stretchable while retaining their electronic functionality. Patterning stiff materials into serpentine-shaped wavy ribbons has become a popular strategy for fabricating stretchable inorganic electronics. However due to a lack of mechanics understanding, design of serpentine structures is still largely empirical, whether for freestanding or substrate supported serpentines. This dissertation systematically investigates the mechanics of serpentine structures with emphasis on the effects of serpentine geometry and substrate stiffness, which involves theoretical analysis, numerical simulation, and experimental validation. Our theory has successfully predicted the stretchability and stiffness of various serpentine shapes and has been applied to the optimization of serpentine designs under practical constraints. We are also the first to point out that not all geometric effects are monotonic and serpentines are not always more stretchable than linear ribbons. To manufacture high quality serpentine ribbons with high throughput and low cost, we have invented a “cut-and-paste” method to fabricate both metallic and ceramic serpentines. As a demonstration of our method, a noninvasive, tattoo-like multifunctional epidermal sensor system has been built for the measurement of electrophysiological signals, skin temperature, skin hydration, and respiratory rate. Engineering of epidermal stretchable antenna for wireless communication is also detailed and rationalized.Mechanical Engineerin