571 research outputs found

    Singapore River

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    Design and Implementation of an RF Data Communication System

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    Located just 8 miles northeast of Union College is Ballston Lake, a unique lake, which offers excellent research opportunities for faculty and students. The south basin of the lake is permanently stratified, and there has been no intermixing between water layers for thousands of years. The lower water layers contain no oxygen (anoxic). The Union College Geology Department is interested in a ten year study of Ballston Lake. Currently, there is no commercially available automatic system for collecting and transmitting data from a sensor package at the bottom of the lake to the lake shore and finally to Union College for long-term research purposes. For this project, I have designed and implemented a prototype for an RF data communication system between Ballston Lake and Union College. This system will be used as a part of the long-term water monitoring system for Ballston Lake. The system will allow users to collect and transmit the water property data automatically without having most of the tedious human involvement. In addition, the system will not only offer a large amount of data storage space but also provide a convenient technique to manage and analyze data to help answer numerous questions concerning this fascinating lake. The system design contain both hardware and software components. They both worked together to provide all essential characteristics to perform data transmission reliably between Ballston Lake and Union College. Several possibilities for each hardware component are explored carefully to meet system requirements. In order to communicate reliably between two sites, the Master/Slave protocol is designed and implement. The protocol has been verified working properly with error detection, receiver feedback and retransmission. Several different scenarios of data transmission protocol were tested in order to check the robustness of the protocol

    Numerical Flow Analysis of an Axial Flow Pump

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    This paper describes the detailed study of fluid flows in an axial pump that includes impeller and guide vanes. And the comparisons of flow simulations of the axial pump impeller with guide vanes and without guide vanes are carried out in this paper. In addition to this, the effect of number of guide blades on flow behaviours is analysed numerically. The computational results are performed by using one of CFD commercial software, Solidworks Flow Simulation. The input design data of the model pump are the flow rate of 0.2m3, head of 3m and the rotational speed of 1160 rpm. The outer and inner diameter of impeller is 0.3m and 0.15m respectively. . And the impeller with four blades is used in this paper. The guide blade number is varied to 5,7,9nbsp with the same input data and other geometric parameters keep constant. In this study, the nature of velocities and pressures in an axial flow pump is analysed. The comparisons are averaged flow velocities, static pressure rise, dynamic pressure and total pressure.nbs

    Gut microbiome is associated with multiple sclerosis activity in children

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    OBJECTIVE: To identify features of the gut microbiome associated with multiple sclerosis activity over time. METHODS: We used 16S ribosomal RNA sequencing from stool of 55 recently diagnosed pediatric-onset multiple sclerosis patients. Microbiome features included the abundance of individual microbes and networks identified from weighted genetic correlation network analyses. Prentice-Williams-Peterson Cox proportional hazards models estimated the associations between features and three disease activity outcomes: clinical relapses and both new/enlarging T2 lesions and new gadolinium-enhancing lesions on brain MRI. Analyses were adjusted for age, sex, and disease-modifying therapies. RESULTS: Participants were followed, on average, 2.1 years. Five microbes were nominally associated with all three disease activity outcomes after multiple testing correction. These included butyrate producers Odoribacter (relapse hazard ratio = 0.46, 95% confidence interval: 0.24, 0.88) and Butyricicoccus (relapse hazard ratio = 0.49, 95% confidence interval: 0.28, 0.88). Two networks of co-occurring gut microbes were significantly associated with a higher hazard of both MRI outcomes (gadolinium-enhancing lesion hazard ratios (95% confidence intervals) for Modules 32 and 33 were 1.29 (1.08, 1.54) and 1.42 (1.18, 1.71), respectively; T2 lesion hazard ratios (95% confidence intervals) for Modules 32 and 33 were 1.34 (1.15, 1.56) and 1.41 (1.21, 1.64), respectively). Metagenomic predictions of these networks demonstrated enrichment for amino acid biosynthesis pathways. INTERPRETATION: Both individual and networks of gut microbes were associated with longitudinal multiple sclerosis activity. Known functions and metagenomic predictions of these microbes suggest the important role of butyrate and amino acid biosynthesis pathways. This provides strong support for future development of personalized microbiome interventions to modify multiple sclerosis disease activity

    Electromigration of single metal atoms observed by scanning tunneling microscopy

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    The authors show in this letter that single metal atoms on a Ni(111) surface can be pushed by electromigration forces from a scanning tunneling microscope tip. This repulsive interaction is obsd. over a length scale of 6 nm. While for voltages above -300 mV the atoms are pulled by the microscope tip, the atoms are pushed away below this threshold. This migration is explained by a resonant scattering of strongly correlated electrons. At small voltages chem. forces are pulling the atom, while for larger voltages the at. manipulation is assisted by the tunneling current. [on SciFinder (R)

    The Effect of the Width of the Incident Pulse to the Dielectric Transition Layer in the Scattering of an Electromagnetic Pulse — A Qubit Lattice Algorithm Simulation

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    The effect of the thickness of the dielectric boundary layer that connects a material of refractive index n1 to another of index n2is considered for the propagation of an electromagnetic pulse. A qubit lattice algorithm (QLA), which consists of a specially chosen non-commuting sequence of collision and streaming operators acting on a basis set of qubits, is theoretically determined that recovers the Maxwell equations to second-order in a small parameter ϵ. For very thin boundary layer the scattering properties of the pulse mimics that found from the Fresnel jump conditions for a plane wave - except that the transmission to incident amplitudes are augmented by a factor of √n2/n1. As the boundary layer becomes thicker one finds deviations away from the Fresnel conditions and eventually one approaches the expected WKB limit. However there is found a small but unusual dip in part of the transmitted pulse that persists in time. Computationally, the QLA simulations still recover the solutions to Maxwell equations even when this parameter ϵ → 1. On examining the pulse propagation in medium n1, ϵ corresponds to the dimensionless speed of the pulse (in lattice units)

    Reflection and Transmission of Electromagnetic Pulses at a Planar Dielectric Interface: Theory and Quantum Lattice Simulations

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    There is considerable interest in the application of quantum information science to advance computations in plasma physics. A particular point of curiosity is whether it is possible to take advantage of quantum computers to speed up numerical simulations relative to conventional computers. Many of the topics in fusion plasma physics are classical in nature. In order to implement them on quantum computers, it will require couching a classical problem in the language of quantum mechanics. Electromagnetic waves are routinely used in fusion experiments to heat a plasma or to generate currents in the plasma. The propagation of electromagnetic waves is described by Maxwell equations with an appropriate description of the plasma as a dielectric medium. Before advancing to the tensor dielectric of a magnetized plasma, this paper considers electromagnetic wave propagation in a one-dimensional inhomogeneous scalar dielectric. The classic theory of scattering of plane electromagnetic waves at a planar interface, separating two different dielectric media, leads to Fresnel equations for reflection and transmission coefficients. In contrast to plane waves, this paper is on the reflection and transmission of a spatially confined electromagnetic pulse. Following an analytical formulation for the scattering of a Gaussian pulse, it is deduced that the maximum transmission coefficient for a pulse is √n2In1 times that for a plane wave; the incident and transmitted pulses propagate in dielectric media with refractive indices n1 and n2, respectively. The analytical theory is complemented by numerical simulations using a quantum lattice algorithm for Maxwell equations. The algorithm, based on the Riemann-Silberstein-Weber representation of the electromagnetic fields and expressed in terms of qubits, is an interleaved sequence of entangling operators at each lattice site and unitary streaming operators, which transmit information from one site to an adjacent lattice site. Besides substantiating results from the theory for Gaussian pulses, numerical simulations show their validity for non-Gaussian pulses. Apart from their time-asymptotic forms, the simulations display an interplay between the incident, reflected, and transmitted pulses in the vicinity of the transition region between two dielectric media

    Quantum Lattice Representation for the Curl Equations of Maxwell Equations

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    A quantum lattice representation (QLA) is devised for the initial value problem of one-dimensional (1D) propagation of an electromagnetic disturbance in a scalar dielectric medium satisfying directly only the two curl equations of Maxwell. It si found that only 4 qubits/node are required. The collision, streaming, and potential operators are determined so as to recover the two curl equations to second order. Both polarizations are considered.Comment: 11 pages, 10 figure

    Institutionalising smart city research and innovation: from fuzzy definitions to real-life experiments

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    By exploring and defining characteristics of a smart city research and innovation centre, we contribute to the discussion on smart city development capacity. To do so, using a qualitative method, we review definitions of the concept and map international groups and institutes affiliated with this domain. Our main result is an overview of global research centres dealing with smart cities. One of the key implications of this paper is that instead of a strict definition, the important aspect appears in the framing provided by the complex real-life challenges that require and enable cross-disciplinary research, even though the concept keeps evolving
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