101 research outputs found

    The Effect of Tidal Asymmetry and Temporal Settling Lag on Sediment Trapping in Tidal Estuaries

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    Over decades and centuries, the mean depth of estuaries changes due to sea-level rise, land subsidence, infilling, and dredging projects. These processes produce changes in relative roughness (friction) and mixing, resulting in fundamental changes in the characteristics of the horizontal (velocity) and vertical tides (sea surface elevation) and the dynamics of sediment trapping. To investigate such changes, a 2DV model is developed. The model equations consist of the width-averaged shallow water equations and a sediment balance equation. Together with the condition of morphodynamic equilibrium, these equations are solved analytically by making a regular expansion of the various physical variables in a small parameter. Using these analytic solutions, we are able to gain insight into the fundamental physical processes resulting in sediment trapping in an estuary by studying various forcings separately. As a case study, we consider the Ems estuary. Between 1980 and 2005, successive deepening of the Ems estuary has significantly altered the tidal and sediment dynamics. The tidal range and the surface sediment concentration has increased and the position of the turbidity zone has shifted into the freshwater zone. The model is used to determine the causes of these historical changes. It is found that the increase of the tidal amplitude toward the end of the embayment is the combined effect of the deepening of the estuary and a 37% and 50% reduction in the vertical eddy viscosity and stress parameter, respectively. The physical mechanism resulting in the trapping of sediment, the number of trapping regions, and their sensitivity to grain size are explained by careful analysis of the various contributions of the residual sediment transport. It is found that sediment is trapped in the estuary by a delicate balance between the M 2 transport and the residual transport for fine sediment (\emphws=0.2 mm s −1) and the residual, M 2 and M 4 transports for coarser sediment (\emphws=2 mm s − 1). The upstream movement of the estuarine turbidity maximum into the freshwater zone in 2005 is mainly the result of changes in tidal asymmetry. Moreover, the difference between the sediment distribution for different grain sizes in the same year can be attributed to changes in the temporal settling lag

    The Effect of Tidal Asymmetry and Temporal Settling Lag on Sediment Trapping in Tidal Estuaries

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    Over decades and centuries, the mean depth of estuaries changes due to sea-level rise, land subsidence, infilling, and dredging projects. These processes produce changes in relative roughness (friction) and mixing, resulting in fundamental changes in the characteristics of the horizontal (velocity) and vertical tides (sea surface elevation) and the dynamics of sediment trapping. To investigate such changes, a 2DV model is developed. The model equations consist of the width-averaged shallow water equations and a sediment balance equation. Together with the condition of morphodynamic equilibrium, these equations are solved analytically by making a regular expansion of the various physical variables in a small parameter. Using these analytic solutions, we are able to gain insight into the fundamental physical processes resulting in sediment trapping in an estuary by studying various forcings separately. As a case study, we consider the Ems estuary. Between 1980 and 2005, successive deepening of the Ems estuary has significantly altered the tidal and sediment dynamics. The tidal range and the surface sediment concentration has increased and the position of the turbidity zone has shifted into the freshwater zone. The model is used to determine the causes of these historical changes. It is found that the increase of the tidal amplitude toward the end of the embayment is the combined effect of the deepening of the estuary and a 37% and 50% reduction in the vertical eddy viscosity and stress parameter, respectively. The physical mechanism resulting in the trapping of sediment, the number of trapping regions, and their sensitivity to grain size are explained by careful analysis of the various contributions of the residual sediment transport. It is found that sediment is trapped in the estuary by a delicate balance between the M 2 transport and the residual transport for fine sediment (\emphws=0.2 mm s −1) and the residual, M 2 and M 4 transports for coarser sediment (\emphws=2 mm s − 1). The upstream movement of the estuarine turbidity maximum into the freshwater zone in 2005 is mainly the result of changes in tidal asymmetry. Moreover, the difference between the sediment distribution for different grain sizes in the same year can be attributed to changes in the temporal settling lag

    О возможности дистанционной диагностики дыхательной системы человека методом аускультации

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    Development of technical base, software, accumulated information on the diagnosis of the respiratory system provided the prerequisites for creating remote diagnostics of the human respiratory system through auscultation. The known methods do not solve the problem of determining auscultation points at patent´s housing without a diagnostic specialist. The purpose of this study is to develop a method for remote diagnostics of the respiratory system which provides ability to determine the points of auscultation without presence of a diagnostic specialist. The definition of auscultation points is provided using a computer program that allows to calculate the points´ coordinates based on the coordinates of points that determine the anatomical structure of the patient's torso. The patient or his assistant places the recording device at the auscultation points combining their images on the display with the image of the location of the recording device. The signal recorded at the auscultation point is remotely transmitted to a specialist for direct analysis and/or computer processing. The diagnostic module consists of two main units. The first unit contains a stethoscope, microphone, and amplifier connected to a mobile phone or other similar device containing an accelerometer. The patient or his assistant at the housing uses the unit. The second unit is a mobile phone with a mechanical marker or a computer with the ability to access the network in conjunction with the necessary software and is used remotely by a diagnostic specialist. The layout of the unit for recording and transmitting breath sounds was made. To avoid discrepancies in the diagnostic results the technical characteristics of the module elements must be normalized. Unified software is required for the module to function. The organizational tasks that need to be solved for the implementation of diagnostics are formulated. Use of the method of remote diagnostics of the respiratory system, providing the ability to determine points of auscultation without the direct presence of a diagnostic specialist and the module will allow increasing efficiency of treatment of pulmonary diseases reduce infection risks and economic costs

    Оценка экономической эффективности использования накопителей электроэнергии в энергосистеме

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    The paper considers some aspects pertaining to an application of technologies for energy storage in electric power. Review of technical and cost characteristics of energy storage units has been given in the paper. The review reflects data of the energy storage units which are available and which are under development. The paper proposes an approach that permits to assess boundaries of economically reasonable application of energy storage systems in order to balance daily load curve of a power system.Рассмотрены некоторые аспекты применения технологий для накопления энергии в электроэнергетике. Приведен обзор технических и стоимостных характеристик накопителей как выполненных на основе известных решений, так и находящихся в стадии разработки. Предложен подход, позволяющий оценить границы экономической целесообразности применения устройств накопления электроэнергии для выравнивания суточного графика нагрузки энергосистемы

    АНАЛИЗ ВЛИЯНИЯ НАКОПИТЕЛЕЙ НА ПОТЕРИ ЭЛЕКТРОЭНЕРГИИ В ЭНЕРГОСИСТЕМЕ. Часть 2

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    Mathematical relationships characterizing a storage impact on energy losses in case of different charge/discharge power ratio in the device have been obtained in the paper. The relationships have used as a basis for calculations that have estimated changes in energy losses for a wide scope of variants pertaining to setting up reference conditions and charge/discharge power ratio of the storage. The obtained results have made it possible to compare various storage operational modes on the assumption of an energy losses reduction criterion.Получены математические зависимости, характеризующие влияние накопителей на потери электроэнергии при неравенстве мощностей заряда/разряда устройства. На их основе проведен ряд расчетов, оценивающих изменение потерь электроэнергии для широкого диапазона вариантов задания исходных режимов и мощностей заряда/разряда накопителя. C использованием полученных результатов осуществлено сопоставление различных вариантов работы накопителей исходя из критерия снижения потерь электроэнергии

    Spectral and kinetic features of thermoluminescence in hexagonal boron nitride powder after UV-irradiation

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    Thermally stimulated luminescence (TL) from UV-irradiated h-BN powder synthesized using carbamide technique was studied. Three TL peaks at T max = 380, 500 and 600 K during linear heating with 2 K/s rate in RT - 773 K temperature range were observed. It was found that the 2.90 and 3.25 eV emission bands, which were related with recombination centers on the basis of VN and BO--complexes, dominate in TL spectra of h-BN. Experimental TL glow curves were analyzed in terms of general order kinetics and energy parameters of responsible capture levels were estimated. It was shown, considering the independent data on the luminescent properties of hexagonal boron nitride in different structural states, that TL peaks at 380 K and 600 K were due to traps based on the one-boron and the three-boron centers with thermal depth EA = 0.7 and 1.0 eV, respectively. The possible origin of the trap with EA = 1.6 eV, responsible for the TL peak at 500 K, is discussed. © 2013 Elsevier B.V. All rights reserved

    О возможности дистанционной диагностики дыхательной системы человека методом аускультации

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    Development of technical base, software, accumulated information on the diagnosis of the respiratory system provided the prerequisites for creating remote diagnostics of the human respiratory system through auscultation. The known methods do not solve the problem of determining auscultation points at patent´s housing without a diagnostic specialist. The purpose of this study is to develop a method for remote diagnostics of the respiratory system which provides ability to determine the points of auscultation without presence of a diagnostic specialist.The definition of auscultation points is provided using a computer program that allows to calculate the points´ coordinates based on the coordinates of points that determine the anatomical structure of the patient's torso. The patient or his assistant places the recording device at the auscultation points combining their images on the display with the image of the location of the recording device. The signal recorded at the auscultation point is remotely transmitted to a specialist for direct analysis and/or computer processing. The diagnostic module consists of two main units. The first unit contains a stethoscope, microphone, and amplifier connected to a mobile phone or other similar device containing an accelerometer. The patient or his assistant at the housing uses the unit. The second unit is a mobile phone with a mechanical marker or a computer with the ability to access the network in conjunction with the necessary software and is used remotely by a diagnostic specialist. The layout of the unit for recording and transmitting breath sounds was made. To avoid discrepancies in the diagnostic results the technical characteristics of the module elements must be normalized. Unified software is required for the module to function. The organizational tasks that need to be solved for the implementation of diagnostics are formulated.Use of the method of remote diagnostics of the respiratory system, providing the ability to determine points of auscultation without the direct presence of a diagnostic specialist and the module will allow increasing efficiency of treatment of pulmonary diseases reduce infection risks and economic costs. Развитие технической базы, программного обеспечения, а также накопленная информация по диагностике дыхательной системы обеспечили предпосылки для создания дистанционной диагностики дыхательной системы человека посредством аускультации. В известных методиках не решена проблема определения точек аускультации в домашних условиях без присутствия специалиста по диагностике. Целью настоящего исследования является разработка методики дистанционной диагностики дыхательной системы, обеспечивающая возможность определения точек аускультации без присутствия специалиста по диагностике.Для этого предусмотрено определение точек аускультации с использованием компьютерной программы, позволяющей вычислить их координаты на основе координат точек, определяющих анатомическое строение торса пациента. Пациент или его помощник устанавливают записывающее устройство в точки аускультации, совмещая на дисплее их изображения с изображением точки нахождения записывающего устройства. Записываемый в точке аускультации сигнал дистанционно передаётся специалисту для непосредственного анализа и/или компьютерной обработки. Диагностический модуль состоит из двух основных узлов. Первый содержит стетоскоп, микрофон и усилитель, соединённые с мобильным телефоном или другим аналогичным устройством, содержащим акселерометр. Узел используется пациентом или его помощником в домашних условиях. Второй узел представляет мобильный телефон с механическим маркером либо компьютер с возможностью выхода в сеть в совокупности с необходимым программным обеспечением и используется дистанционно специалистом по диагностике. Изготовлен макет узла записи и передачи звуков дыхания. Чтобы избежать расхождения результатов диагностики, технические характеристики элементов модуля необходимо нормировать. Для функционирования модуля требуется унифицированное программное обеспечение. Сформулированы организационные задачи, которые необходимо решить для внедрения диагностики.Использование разработанной методики дистанционной диагностики дыхательной системы, обеспечивающей возможность определения точек аускультации без присутствия специалиста по диагностике и соответствующего модуля позволит увеличить эффективность лечения пульмонологических заболеваний, уменьшить риски инфицирования и экономические затраты.

    Dynamics of Cryogenic Jets: Non-Rayleigh Breakup and Onset of Nonaxisymmetric Motions

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    We report development of generators for periodic, satellite-free fluxes of mono-disperse drops with diameters down to 10 mikrometers from cryogenic liquids like H_2, N_2, Ar and Xe (and, as reference fluid, water). While the breakup of water jets can well be described by Rayleigh's linear theory, we find jet regimes for H_2 and N_2 which reveal deviations from this behavior. Thus, Rayleigh's theory is inappropriate for thin jets that exchange energy and/or mass with the surrounding medium. Moreover, at high evaporation rates, axial symmetry of the dynamics is lost. When the drops pass into vacuum, frozen pellets form due to surface evaporation. The narrow width of the pellet flux paves the way towards various industrial and scientific applications.Comment: 4 pages, 4 figures, 1 table; final version to appear in Phys.Rev.Lett (minor changes with respect to v1

    Technical Design Report for the PANDA Solenoid and Dipole Spectrometer Magnets

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    This document is the Technical Design Report covering the two large spectrometer magnets of the PANDA detector set-up. It shows the conceptual design of the magnets and their anticipated performance. It precedes the tender and procurement of the magnets and, hence, is subject to possible modifications arising during this process.Comment: 10 pages, 14MB, accepted by FAIR STI in May 2009, editors: Inti Lehmann (chair), Andrea Bersani, Yuri Lobanov, Jost Luehning, Jerzy Smyrski, Technical Coordiantor: Lars Schmitt, Bernd Lewandowski (deputy), Spokespersons: Ulrich Wiedner, Paola Gianotti (deputy

    Feasibility studies of time-like proton electromagnetic form factors at PANDA at FAIR

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    Simulation results for future measurements of electromagnetic proton form factors at \PANDA (FAIR) within the PandaRoot software framework are reported. The statistical precision with which the proton form factors can be determined is estimated. The signal channel pˉpe+e\bar p p \to e^+ e^- is studied on the basis of two different but consistent procedures. The suppression of the main background channel, i.e.\textit{i.e.} pˉpπ+π\bar p p \to \pi^+ \pi^-, is studied. Furthermore, the background versus signal efficiency, statistical and systematical uncertainties on the extracted proton form factors are evaluated using two different procedures. The results are consistent with those of a previous simulation study using an older, simplified framework. However, a slightly better precision is achieved in the PandaRoot study in a large range of momentum transfer, assuming the nominal beam conditions and detector performance
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