Methods for synthesis of multiple-input translinear element networks

Translinear circuits are circuits in which the exponential relationship between the output current and input voltage of a circuit element is exploited to realize various algebraic or differential equations. This thesis is concerned with a subclass of translinear circuits, in which the basic translinear element, called a multiple-input translinear element (MITE), has an output current that is exponentially related to a weighted sum of its input voltages. MITE networks can be used for the implementation of the same class of functions as traditional translinear circuits. The implementation of algebraic or (algebraic) differential equations using MITEs can be reduced to the implementation of the product-of-power-law (POPL) relationships, in which an output is given by the product of inputs raised to different powers. Hence, the synthesis of POPL relationships, and their optimization with respect to the relevant cost functions, is very important in the theory of MITE networks. In this thesis, different constraints on the topology of POPL networks that result in desirable system behavior are explored and different methods of synthesis, subject to these constraints, are developed. The constraints are usually conditions on certain matrices of the network, which characterize the weights in the relevant MITEs. Some of these constraints are related to the uniqueness of the operating point of the network and the stability of the network. Conditions that satisfy these constraints are developed in this work. The cost functions to be minimized are the number of MITEs and the number of input gates in each MITE. A complete solution to POPL network synthesis is presented here that minimizes the number of MITEs first and then minimizes the number of input gates to each MITE. A procedure for synthesizing POPL relationships optimally when the number of gates is minimal, i.e., 2, has also been developed here for the single--output case. A MITE structure that produces the maximum number of functions with minimal reconfigurability is developed for use in MITE field--programmable analog arrays. The extension of these constraints to the synthesis of linear filters is also explored, the constraint here being that the filter network should have a unique operating point in the presence of nonidealities. Synthesis examples presented here include nonlinear functions like the arctangent and the gaussian function which find application in analog implementations of particle filters. Synthesis of dynamical systems is presented here using the examples of a Lorenz system and a sinusoidal oscillator. The procedures developed here provide a structured way to automate the synthesis of nonlinear algebraic functions and differential equations using MITEs.Ph.D.Committee Chair: Anderson, David; Committee Member: Habetler, Thomas; Committee Member: Hasler, Paul; Committee Member: McClellan, James; Committee Member: Minch, Bradle

Large scale reconfigurable analog system design enabled through floating-gate transistors

This work is concerned with the implementation and implication of non-volatile charge storage on VLSI system design. To that end, the floating-gate pFET (fg-pFET) is considered in the context of large-scale arrays. The programming of the element in an efficient and predictable way is essential to the implementation of these systems, and is thus explored. The overhead of the control circuitry for the fg-pFET, a key scalability issue, is examined. A light-weight, trend-accurate model is absolutely necessary for VLSI system design and simulation, and is also provided. Finally, several reconfigurable and reprogrammable systems that were built are discussed.Ph.D.Committee Chair: Hasler, Paul E.; Committee Member: Anderson, David V.; Committee Member: Ayazi, Farrokh; Committee Member: Degertekin, F. Levent; Committee Member: Hunt, William D

Bridges Structural Health Monitoring and Deterioration Detection Synthesis of Knowledge and Technology

INE/AUTC 10.0

Appendage development and early Distal-less regulation in arthropods: A study of the chelicerate Tetranychus urticae (Acarida)

A major goal of evolutionary developmental biology is to explore mechanisms and events underlying evolution of the myriad body plan morphologies expressed both genetically and phenotypically within the animal kingdom. Arthropods exhibit an astounding array of morphological diversity both within and between representative sub-phyla, thus providing an ideal phylum through which to address questions of body plan innovation and diversification. Major arthropod groups are recognised and defined by the distinct form and number of articulated appendages present along the antero-posterior axis of their segmented bodies. A great deal is known about the developmental genetics of limb development in the model insect Drosophila melanogaster, added to which, much comparative gene expression data and a growing body of functional genetic data is emerging for other arthropod species. Arthropod limb primordia are consistently marked by expression of the homeobox gene Distal-less (Dll), and the focus of this thesis is to compare signalling mediated by early Dll regulatory genes activity along antero-posterior and dorso-ventral embryonic axes during limb specification in Drosophila, with the activity of their orthologs in the widely disparate chelicerate, the spider mite Tetranychus urticae – interpreting new data with that available for other arthropods. Having made a detailed study of spider mite embryonic (and post-embryonic) development, to provide a basis for understanding mRNA transcription and protein activity patterns, I confirmed typical expression of Tetranychus Dll in prosomal limb primordia. I obtained limited results for the candidate antero-posterior positioning genes wingless and engrailed, although one of the two engrailed paralogs I identified is reportedly expressed in posterior segmental compartments, consistent with possible conservation of Engrailed-Wingless interactions in metameric patterning and positive regulation of Dll in arthropod limb specification. In Drosophila, wingless-dependent Dll transcription is restricted along the dorso-ventral axis by dorsal Dpp-mediated and ventral EGFR-mediated signalling gradients. Based on data from Tetranychus and other arthropods, neither dorsal nor ventral signalling regimes appear conserved outside the Drosophila system. Dll suppression in fly abdominal segments occurs due to powerful Hox (Ubx/AbdA) repression of the early Dll cis-regulatory element; this is discussed in relation to the independently evolved limbless chelicerate opisthosoma, informed by hypothetical scenarios of cis (regulatory DNA) and trans (coding sequence) evolution. Given practical difficulties and limitations encountered while working with spider mites, I offer a final assessment of the place of Tetranychus urticae as a non-model, and yet still valuable chelicerate species to consider carrying into the exciting future of evolutionary developmental biology.This doctoral research work was supported by the Biotechnology and Biological Sciences Research Council, the Newton Trust and Corpus Christi College Cambridge

Data comparison schemes for Pattern Recognition in Digital Images using Fractals

Pattern recognition in digital images is a common problem with application in remote sensing, electron microscopy, medical imaging, seismic imaging and astrophysics for example. Although this subject has been researched for over twenty years there is still no general solution which can be compared with the human cognitive system in which a pattern can be recognised subject to arbitrary orientation and scale. The application of Artificial Neural Networks can in principle provide a very general solution providing suitable training schemes are implemented. However, this approach raises some major issues in practice. First, the CPU time required to train an ANN for a grey level or colour image can be very large especially if the object has a complex structure with no clear geometrical features such as those that arise in remote sensing applications. Secondly, both the core and file space memory required to represent large images and their associated data tasks leads to a number of problems in which the use of virtual memory is paramount. The primary goal of this research has been to assess methods of image data compression for pattern recognition using a range of different compression methods. In particular, this research has resulted in the design and implementation of a new algorithm for general pattern recognition based on the use of fractal image compression. This approach has for the first time allowed the pattern recognition problem to be solved in a way that is invariant of rotation and scale. It allows both ANNs and correlation to be used subject to appropriate pre-and post-processing techniques for digital image processing on aspect for which a dedicated programmer's work bench has been developed using X-Designer

NANOSCALED CELLULOSE AND ITS CARBONACEOUS MATERIAL: APPLICATION AND LOCAL STRUCTURE INVESTIGATION

In this dissertation, cellulose nanocrystals three-dimensional morphology, size distribution, and the crystal structure were statistically and quantitatively investigated. Lognormal distribution was identified as the most likely for cellulose nanocrystals’ size distribution. Height and width dimensions were shown to decrease toward the ends from the midpoint of individual CNCs, implying a spindle-like shape. XRD analysis of crystallite size accompanied with TEM and AFM measurements revealed that the cross-sectional dimensions of individual switchgrass CNC were either rectangular or elliptical shape, with an approximately 3~5 nm [nanometer] lateral element length range. A sponge-like carbon aerogel from microfibril cellulose with high porosity, ultra-low density, hydrophobic properties, and reusability was synthesized. Carbon aerogels heat-treated at 700 and 900 oC [Celsius] were examined and compared. Sample C-700 (521 m2 /g [square meter/gram]) exhibits significantly higher BET surface area than Sample C-950 (149 m2 /g [square meter/gram]). It also achieved highest normalized sorption capacity (86 g/g [gram/gram]) for paraffin oil. The removal of hydrophilic function groups of carbon aerogel proved by FTIR results to its highly hydrophobic properties. The Oil absorption ability is favored by its highly porous 3D network structure with interconnected cellulose nanofibrils. Simultaneous effects of processing parameters (peak temperature, heating rate) for carbon aerogel processing were investigated using response surface methodology (RSM). Results indicated that the optimum conditions were: 300 °C [Celsius] of the peak temperature and 8.0 °C/min [Celsius/minute] of the heating rate with approximately 90.1 g/g [gram/gram] of the normalized oil absorption capacity. An electron microscopy investigation was performed to link the micro-structure and properties of carbonized cellulose and lignin with the structure of original biomass components. Structure details at micro and molecular levels have been investigated by scanning transmission electron microscopy (STEM). Atomic resolution images revealed the presence of random, fractured graphene fragments in carbonized cellulose (C-CNC) and of large domains of parallel stacked graphene in carbonized lignin (C-Lignin). The randomly arranged small graphene fragments in C-CNC create a network of interconnected micropores and mesopores and contribute to the increased BET surface area. Formation of parallel stacks of graphene structures is favored by the pre-existence of aromatic components in lignin

2020 Student Symposium Research and Creative Activity Book of Abstracts

The UMaine Student Symposium (UMSS) is an annual event that celebrates undergraduate and graduate student research and creative work. Students from a variety of disciplines present their achievements with video presentations. It’s the ideal occasion for the community to see how UMaine students’ work impacts locally – and beyond. The 2020 Student Symposium Research and Creative Activity Book of Abstracts includes a complete list of student presenters as well as abstracts related to their works

Feature Papers in Eng

This Special Issue is a collection of high-quality reviews and original papers from editorial board members, guest editors, and leading researchers discussing new knowledge or new cutting-edge developments in the field of engineering

Doctor of Philosophy

dissertationThe MAKER genome annotation and curation software tool was developed in response to increased demand for genome annotation services, secondary to decreased genome sequencing costs. MAKER currently has over 1000 registered users throughout the world. This wide adoption of MAKER has uncovered the need for additional functionalities. Here I addressed moving MAKER into the domain of plant annotation, expanding MAKER to include new methods of gene and noncoding RNA annotation, and improving usability of MAKER through documentation and community outreach. To move MAKER into the plant annotation domain, I benchmarked MAKER on the well-annotated Arabidopsis thaliana genome. MAKER performs well on the Arabidopsis genome in de novo genome annotation and was able to improve the current TAIR10 gene models by incorporating mRNA-seq data not available during the original annotation efforts. In addition to this benchmarking, I annotated the genome of the sacred lotus Nelumbo Nucifera. I enabled noncoding RNA annotation in MAKER by adding the ability for MAKER to run and process the outputs of tRNAscan-SE and snoscan. These functionalities were tested on the Arabidopsis genome and used MAKER to annotate tRNAs and snoRNAs in Zea mays. The resulting version of MAKER was named MAKER-P. I added the functionality of a combiner by adding EVidence Modeler to the MAKER code base. iv As the number of MAKER users has grown, so have the help requests sent to the MAKER developers list. Motivated by the belief that improving the MAKER documentation would obviate the need for many of these requests, I created a media wiki that was linked to the MAKER download page, and the MAKER developers list was made searchable. Additionally I have written a unit on genome annotation using MAKER for Current Protocols in Bioinformatics. In response to these efforts I have seen a corresponding decrease in help requests, even though the number of registered MAKER users continues to increase. Taken together these products and activities have moved MAKER into the domain of plant annotation, expanded MAKER to include new methods of gene and noncoding RNA annotation, and improved the usability of MAKER through documentation and community outreach