3,870 research outputs found

    A genetic algorithm for the vehicle routing problem with time windows

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    The objective of the vehicle routing problem (VRP) is to deliver a set of customers with known demands on minimum-cost vehicle routes originating and terminating at the same depot. A vehicle routing problem with time windows (VRPTW) requires the delivery be made within a speci¯c time frame given by the customers. Prins (2004) recently proposed a simple and e®ective genetic algorithm (GA) for VRP. In terms of average solution cost, it outperforms most published tabu search results. We implement this hybrid GA to handle VRPTW. Both the implementation and computational results will be discussed

    DEVELOPMENT OF A VERSATILE HIGH SPEED NANOMETER LEVEL SCANNING MULTI-PROBE MICROSCOPE

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    The motivation for development of a multi-probe scanning microscope, presented in this dissertation, is to provide a versatile measurement tool mainly targeted for biological studies, especially on the mechanical and structural properties of an intracellular system. This instrument provides a real-time, three-dimensional (3D) scanning capability. It is capable of operating on feedback from multiple probes, and has an interface for confocal photo-detection of fluorescence-based and single molecule imaging sensitivity. The instrument platform is called a Scanning Multi-Probe Microscope (SMPM) and enables 45 microm by 45 microm by 10 microm navigation of specimen with simultaneous optical and mechanical probing with each probe location being adjustable for collocation or for probing with known probe separations. The 3D positioning stage where the specimen locates was designed to have nanometer resolution and repeatability at 10 Hz scan speed with either open loop or closed loop operating modes. The fine motion of the stage is comprises three orthogonal flexures driven by piezoelectric actuators via a lever linkage. The flexures design is able to scan in larger range especially in z axis and serial connection of the stages helps to minimize the coupling between x, y and z axes. Closed-loop control was realized by the capacitance gauges attached to a rectangular block mounted to the underside of the fine stage upon which the specimen is mounted. The stage's performance was studied theoretically and verified by experimental test. In a step response test and using a simple proportional and integral (PI) controller, standard deviations of 1.9 nm 1.8 nm and 0.41 nm in the x, y and z axes were observed after settling times of 5 ms and 20 ms for the x and y axes. Scanning and imaging of biological specimen and artifact grating are presented to demonstrate the system operation. For faster, short range scanning, novel ultra-fast fiber scanning system was integrated into the xyz fine stage to achieve a super precision dual scanning system. The initial design enables nanometer positioning resolution and runs at 100 Hz scan speed. Both scanning systems are capable of characterization using dimensional metrology tools. Additionally, because the high-bandwidth, ultra-fast scanning system operates through a novel optical attenuating lever, it is physically separate from the longer range scanner and thereby does not introduce additional positioning noise. The dual scanner provides a fine scanning mechanism at relatively low speed and large imaging area using the xyz stage, and focus on a smaller area of interested in a high speed by the ultra-fast scanner easily. Such functionality is beneficial for researchers to study intracellular dynamic motion which requires high speed imaging. Finally, two high end displacement sensor systems, a knife edge sensor and fiber interferometer, were demonstrated as sensing solutions for potential feedback tools to boost the precision and resolution performance of the SMPM

    Analytic functions and complex integration

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    This paper presents some basic theory of analytic function. The class of analytic functions is formed by the complex functions of a complex variable which possess a derivative wherever the function is defined. Beginning with the definition of the derivative, the necessary and sufficient conditions for a function to be analytic at a point are developed. In order to prove that the derivative of an analytic function is itself analytic, the line integrals are defined. The exact differential and its relation to line integrals are discussed. Then Cauchy's theorem is stated. Since the proof of Cauchy's theorem is so complicated and can be found in most texts on complex variable, it is skipped. Lastly Cauchy's integral formula is developed. The formula is an ideal tool for the study of local properties of analytic functions. Particularly it helps to show that an analytic function has derivatives of all orders, which are then analytic. With this result, the converse of Cauchy's theorem, known as Morera's theorem, can be proved. Last, the paper discusses Liouville's theorem concerning entire function

    Innovative sponge-based moving bed-osmotic membrane bioreactor hybrid system using a new class of draw solution for municipal wastewater treatment

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    © 2016 Elsevier Ltd. For the first time, an innovative concept of combining sponge-based moving bed (SMB) and an osmotic membrane bioreactor (OsMBR), known as the SMB-OsMBR hybrid system, were investigated using Triton X-114 surfactant coupled with MgCl2 salt as the draw solution. Compared to traditional activated sludge OsMBR, the SMB-OsMBR system was able to remove more nutrients due to the thick-biofilm layer on sponge carriers. Subsequently less membrane fouling was observed during the wastewater treatment process. A water flux of 11.38 L/(m2 h) and a negligible reverse salt flux were documented when deionized water served as the feed solution and a mixture of 1.5 M MgCl2 and 1.5 mM Triton X-114 was used as the draw solution. The SMB-OsMBR hybrid system indicated that a stable water flux of 10.5 L/(m2 h) and low salt accumulation were achieved in a 90-day operation. Moreover, the nutrient removal efficiency of the proposed system was close to 100%, confirming the effectiveness of simultaneous nitrification and denitrification in the biofilm layer on sponge carriers. The overall performance of the SMB-OsMBR hybrid system using MgCl2 coupled with Triton X-114 as the draw solution demonstrates its potential application in wastewater treatment

    Beethoven's D Major Sonata for Cello and Piano, Op. 102 No. 2: an annotated performer's edition based on the suggestions of Bernard Greenhouse

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    Honorary Doctor of Music Bernard Greenhouse has earned a worldwide reputation as one of the leading cellists of our generation. As the founding cellist of the Beaux Arts Trio, he has garnered international acclaim for his supreme artistry; and as a teacher, he has exerted major influence on many of today's cellists. This dissertation documents Greenhouse's approach to music making in the context of his interpretation of Beethoven's Sonata in D major for Cello and Piano, Op. 102 No. 2. In a series of interviews by the undersigned, Greenhouse demonstrates ways to seize the sonata's dramatic impulses. He refers to his own studies with Pablo Casals when discussing his approach to interpretation. Among his many suggestions, he emphasizes the performer's role in "turning music into speech that can be understood." To this end, he provides techniques for clear enunciation and for creating dynamic inflections and rhythmic momentum in the music. This dissertation begins by surveying Greenhouse's contribution to cello playing and existing literature related to Beethoven's D-major sonata and Greenhouse. Then it documents Greenhouse's suggestions for the sonata in the form of commentaries and measure-by-measure annotations in a performer's edition of the score. More than a set of specific instructions for how to perform Beethoven's sonata, this dissertation seeks to describe an approach to string playing that can apply in a wide variety of musical contexts

    Cross-polarized photon-pair generation and bi-chromatically pumped optical parametric oscillation on a chip

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    Nonlinear optical processes are one of the most important tools in modern optics with a broad spectrum of applications in, for example, frequency conversion, spectroscopy, signal processing and quantum optics. For practical and ultimately widespread implementation, on-chip devices compatible with electronic integrated circuit technology offer great advantages in terms of low cost, small footprint, high performance and low energy consumption. While many on-chip key components have been realized, to date polarization has not been fully exploited as a degree of freedom for integrated nonlinear devices. In particular, frequency conversion based on orthogonally polarized beams has not yet been demonstrated on chip. Here we show frequency mixing between orthogonal polarization modes in a compact integrated microring resonator and demonstrate a bi-chromatically pumped optical parametric oscillator. Operating the device above and below threshold, we directly generate orthogonally polarized beams, as well as photon pairs, respectively, that can find applications, for example, in optical communication and quantum optics

    In Vivo Blood Glucose Quantification Using Raman Spectroscopy

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    We here propose a novel Raman spectroscopy method that permits the noninvasive measurement of blood glucose concentration. To reduce the effects of the strong background signals produced by surrounding tissue and to obtain the fingerprint Raman lines formed by blood analytes, a laser was focused on the blood in vessels in the skin. The Raman spectra were collected transcutaneously. Characteristic peaks of glucose (1125 cm(-1)) and hemoglobin (1549 cm(-1)) were observed. Hemoglobin concentration served as an internal standard, and the ratio of the peaks that appeared at 1125 cm(-1) and 1549 cm(-1) peaks was used to calculate the concentration of blood glucose. We studied three mouse subjects whose blood glucose levels became elevated over a period of 2 hours using a glucose test assay. During the test, 25 Raman spectra were collected transcutaneously and glucose reference values were provided by a blood glucose meter. Results clearly showed the relationship between Raman intensity and concentration. The release curves were approximately linear with a correlation coefficient of 0.91. This noninvasive methodology may be useful for the study of blood glucose in vivo

    Relative commutants of strongly self-absorbing C*-algebras

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    The relative commutant AAUA'\cap A^{\mathcal{U}} of a strongly self-absorbing algebra AA is indistinguishable from its ultrapower AUA^{\mathcal{U}}. This applies both to the case when AA is the hyperfinite II1_1 factor and to the case when it is a strongly self-absorbing C*-algebra. In the latter case we prove analogous results for (A)/c0(A)\ell_\infty(A)/c_0(A) and reduced powers corresponding to other filters on N\bf N. Examples of algebras with approximately inner flip and approximately inner half-flip are provided, showing the optimality of our results. We also prove that strongly self-absorbing algebras are smoothly classifiable, unlike the algebras with approximately inner half-flip.Comment: Some minor correction

    Automatic quantitative analysis of morphology of apoptotic HL-60 cells

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    Morphological identification is a widespread procedure to assess the presence of apoptosis by visual inspection of the morphological characteristics or the fluorescence images. The procedure is lengthy and results are observer dependent. A quantitative automatic analysis is objective and would greatly help the routine work. We developed an image processing and segmentation method which combined the Otsu thresholding and morphological operators for apoptosis study. An automatic determination method of apoptotic stages of HL-60 cells with fluorescence images was developed. Comparison was made between normal cells, early apoptotic cells and late apoptotic cells about their geometric parameters which were defined to describe the features of cell morphology. The results demonstrated that the parameters we chose are very representative of the morphological characteristics of apoptotic cells. Significant differences exist between the cells in different stages, and automatic quantification of the differences can be achieved
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