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<p>A digital microfluidic biochip (DMFB) is a device that digitizes fluidic samples into tiny droplets and operates chemical processes on a single chip. Movement control of droplets can be realized by using electrowetting-on-dielectric (EWOD) technology. DMFBs have high configurability, high sensitivity, low cost and reduced human error as well as a promising future in the applications of point-of-care medical diagnostic, and DNA sequencing. As the demands of scalability, configurability and portability increase, a new DMFB architecture called Microelectrode Dot Array (MEDA) has been introduced recently to allow configurable electrodes shape and more precise control of droplets.</p> <p>The objective of this work is to investigate a routing algorithm which can not only handle the routing problem for traditional DMFBs, but also be able to route different sizes of droplets and incorporate diagonal movements for MEDA. The proposed droplet routing algorithm is based on 3D-A* search algorithm. The simulation results show that the proposed algorithm can reduce the maximum latest arrival time, average latest arrival time and total number of used cells. By enabling channel-based routing in MEDA, the equivalent total number of used cells can be significantly reduced. Compared to all existing algorithms, the proposed algorithm can achieve so far the least average latest arrival time.</p>

Phased array antenna has been used for a variety of military and civil applications, over the past five decades. Being structurally conformal and flexible, phased array antenna is highly suitable for mobile applications. Besides, it can form the agile or shaped beams required for interference cancellation or multifunction systems. Moreover, the spatial power combination property increases the effective radiated power of a transmitter phased array system. Similarly, in a receiver phased array, beamforming increases the signal to noise ratio by coherent integration of the desired signals. Despite its impressive potentials and properties, phased array antenna has not become a commercial product yet. Cost and complexity of phased array antenna are beyond the scales of consumer electronics devices. Furthermore, calibration is an essential requirement of such a complex system, which is a fairly time-consuming process and requires skilled man power. Moreover, the narrow bandwidth of microwave components degrades the broadband performance of phased array system. Finally, the majority of the beamforming algorithms developed so far have preconditions, which make them unsuitable for a low-cost system. The objective of this thesis is to provide a novel cost-effective solution to minimize the system complexity of the future intelligent antenna systems, without sacrificing the performance. This research demonstrates that a powerful, robust beamforming algorithm, integrated in an efficient single-receiver architecture, constitutes the essence of a low-cost phased array antenna. Thus, a novel beamforming technique, called Zero-knowledge algorithm is developed. It is investigated, both theoretically and experimentally, that the proposed algorithm can compensate for the hardware errors and imperfections of the low-cost components of the system. Zero-knowledge beamforming algorithm possesses significant properties. Neither a priori knowledge of the incoming signal direction, nor the exact characteristics of the phase control network are required in this method. Proper adjustment of the parameters, makes this algorithm appropriate for mobile systems, particularly those installed on vehicles. The algorithm alleviates the drawbacks of analog phase shifters, such as imbalanced insertion loss and fabrication tolerances. Furthermore, this algorithm can serve as the core of a direction-of-arrival estimation technique, which senses the minor deflections of the array heading. For broadband applications optical delay lines must be used in the phase control network of the phased array systems, which are costly. Nevertheless, employing miniaturized delay lines can significantly reduce the device area, and consequently, the fabrication cost. Thus, in this research four types of miniaturized optical delay lines, designed in slow-wave structures, are analyzed, which can provide a large delay per length. In addition, two novel optical beamforming techniques, based upon the properties of Zero-knowledge algorithm, are developed for transmitter and receiver phased arrays.

<p>HIV-1 relies on both viral and cellular host factors for expression of its genome. Tat specific factor 1 (Tat-SF1) was identified as a cellular cofactor required for enhanced transcription of HIV-1 <italic>in vitro</italic>. Insight into the role of Tat-SF1 in the HIV-1 lifecycle has previously been limited to immunodepletions and <italic>in vitro</italic> analyses or transient overexpression experiments. Here, we present studies that utilize RNA interference (RNAi) to reevaluate Tat-SF1's role in Tat transactivation and HIV-1 replication <italic>in vivo</italic>. We report that although Tat-SF1 depletion reduces HIV-1 infectivity, it does not affect Tat transactivation <italic>in vivo</italic>. However, Tat-SF1 depletion changes the levels of unspliced and spliced RNAs. We propose that Tat-SF1 has a novel role of post-transcriptionally regulating HIV-1 gene expression, possibly through alternative splicing.</p><p>The functions of Tat-SF1 in cellular gene expression are not well understood, so we utilized the stable cell lines constructed for our HIV-1 studies to investigate the cellular functions of Tat-SF1. To identify target genes of Tat-SF1, we employed a combination of RNAi and human exon arrays. These arrays, which survey both transcript-level and exon-level changes genome-wide, revealed approximately 1,400 genes with alternative exon usage after Tat-SF1 depletion (p&le;0.01). In contrast, 500 genes showed significant transcript-level changes (p&le;0.01), all with minimal fold changes. Computational analyses showed that genes with alternative exon usage after Tat-SF1 depletion were over-represented in the insulin signaling and ubiquitin mediated proteolysis biological pathways. Furthermore, there was approximately 2-fold enrichment of Tat-SF1 target genes among previously reported HIV-1 dependency factors. The type of exon choice affected by Tat-SF1 depletion exhibited a strong 5&rsquo; bias. Finally, a novel Tat-SF1 binding motif, GACGGG, was found to be over-represented among target genes and may play a functional role in first exon choice. Together, these data are the strongest evidence to date of Tat-SF1 functioning in both transcription and splicing of cellular genes.</p> / Dissertation

Conformal arrays possess certain desirable characteristics for deployment on unmanned aerial vehicles and other payload-limited platforms: aerodynamic design, minimal payload weight, increased field of view, and ease of integration with diverse sensor functions. However, the conformal arrays nonplanar geometry causes high adaptive losses in conventional space-time adaptive processing (STAP) algorithms. In this thesis, we develop a conformal array signal model and apply it to evaluate the performance of conventional STAP algorithms on simulated ground clutter data. We find that array-induced clutter nonstationarity leads to high adaptive losses, which greatly burden detection performance. To improve adaptive performance, we investigate the application of existing equivalent-linear-array transformations and develop novel deterministic and adaptive angle-Doppler compensation techniques, which align nonstationary clutter returns. Through the application of these techniques, we are able to nearly fully mitigate the nonstationary behavior yielding performance similar to that of a conventional planar array. Finally, we investigate the impact of array errors on the performance of conformal arrays, and propose several array calibration techniques as ameliorating solutions.

The use of seismic waves to detect subsurface targets such as landmines is a very promising technology compared to existing methods like Ground Penetrating Radar (GPR) and Electromagnetic Induction (EMI) sensing. The fact that seismic waves induce resonance in man-made targets, and hence more scattering, gives this method a natural ability to discriminate landmines from common types of clutter like rocks, wood, etc. Reflection and resonance from the targets can be used in imaging to detect the location of targets. However, existing methods require a large number of measurements for imaging and detection, which are expensive and time consuming. To reduce the number of measurements and enable faster detections, a new sensing strategy is proposed based on optimally maneuvering sensors. The system would operate in two main modes. In search mode, the goal would be to move on top of a target using the minimum number of measurements. Once the target is found, the system would switch to a detection mode to make its final decision. The seismic sensor system is an active system, where a seismic source generates the probing pulse. The waves reflected from buried targets are collected by an array of sensors placed on the surface, and then an imaging algorithm is used to estimate the target position. The performance bounds for this position estimate are derived in terms of the Fisher information matrix (FIM). This matrix gives the dependence of the target position estimate on the array position. Based on the FIM, the next optimal array position is determined by using the theory of optimal experiments. The next array position will be the one that reduces the uncertainty of the target position estimate the most. The whole array is moved to this new position, where the same steps are repeated. In this way, the target can be localized in a few iterations.

Recent years have brought many new developments in the processing of speech and acoustic signals. Yet, despite this, the process of acquiring signals has gone largely unchanged. Adding spatial diversity to the repertoire of signal acquisition has long been known to offer advantages for processing signals further. The processing capabilities of mobile devices had not previously been able to handle the required computation to handle these previous streams of information. But current processing capabilities are such that the extra workload introduced by the addition of mutiple sensors on a mobile device are not over-burdensome. How these extra data streams can best be handled is still an open question. The present work deals with the examination of one type of spatial processing technique, known as beamforming. A microphone array test platform is constructed and verified through a number of beamforming agorithms. Issues related to speech acquisition through microphones arrays are discussed. The algorithms used for verification are presented in detail and compared to one another.

Phased array coils are composed of several surface coils receiving individual element signals simultaneously. Each individual surface coil provides the equivalent of the coil diameter range, and higher SNR. Therefore, combining these non-interactive phased array coils, can achieve a wide range of scan areas, uniform sensitivity and better SNR. Therefore our experiment was performed with two different coils of quadrature coil and phased array coil. Phased array MRS data were compared using various combination approaches. Data acquired by quadrature coil was regarded as a standard to verify the reliability and accuracy of metabolite concentration. The aim of our study is to do eddy current correction before and after the combination of each element coil data with LCModel analysis for quantitative comparison of metabolite concentrations. Our result shows that doing eddy current correction for each phased array coil before signal combination can achieve higher reliability and accuracy of SNR and quantitative concentrations of MR spectra in vivo.

Bird¡¦s nest is the saliva from the Colloclia that have a lot of mucin and sialic acid. However the sialic acid is an important intermediate of influenza virus infection. In 2006, Guo et al was confirmed the Inhibitory effect of bird¡¦s nest extract on influenza virus infection. But the anti-virus component has not been isolated and purified. First, the bird's nest used in this study was proved to be a pure bird¡¦s nest by SDS-PAGE, sialic acid content and protein content. Qualification analysis by SDS-PAGE showed sample possessed three bands at about 50 kDa, 100 kDa and 150 kDa, by Warren assay showed sample possessed a sialic acid content about 10% of dry weight, by Kjeldahl method showed sample possessed a protein content about 50% of dry weight, and by fluorescence analysis in 365 nm showed sample emitted a blue-white light. According to the criteria on previous studies, the sample was considered to be a real and pure bird¡¦s nest. Subsequently, the sample was applied to pronase digestion and then separated by Bio-gel P2 for size exclusion chromatography. All fractions were performed carbohydrate analysis including sialic acid. In lectin blotting, Maackia amurensis agglutinin (MAA) lectin can interact with the fraction that suggest the structure of sialic acid is sialic acid-2,3 galactose in bird¡¦s nest. And carbohydrate membrane array to demonstrate the influenza virus of H5N1 and H1N1 can bind the fractions that suggest the antivirus effect of bird¡¦s nest. These fractions will be further analyzed by neutralization assay to study their antivirus effects in vitro.

Due to the improvement of luminous efficiency, LED has been applied in general lighting nowadays. However, the efficacy and life of high power LED lamps are degraded for the problem of overheat temperature of the chips. In accordance with the above reason, the thermal management has been important in LED application. The thesis aims to analyze the thermal problem of high power LED lamp by FEM. In the beginning, we analyzed the temperature curves and thermal stress curves of chips by changing the thickness of AuSn solder in 4 structures. According to the results, the better thickness range and structures were chosen. In the second step, the effect of different sizes of a vapor chamber on the different thermal conductivities of lamp system was discussed. Finally, we orthogonalized all the designed parameters by Taguchi orthogonal array method, and then found the optimal design by comparing the results with the initial analyses. In this study, we proposed a solution to improve the quality characteristics of LED lamp by Taguchi method. So the effect of each control factors on the performance was able to be determined. For different features of demand, the present study is helpful to achieve the ideal design in manufacturing. Key words: FEM, high power LED lamps, Taguchi orthogonal array method