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Flow regime maps are essential to gas-liquid flow applications in many industrial processes to accurately identify the flow regimes before estimating multiphase features. Flow regime classifications were originally based on visual observations of two-phase flow experiments. The observations were mapped on two-dimensional plots (called “flow regime maps”) and the boundaries between regimes determined. Over the years, different coordinates have been proposed for the maps (e.g., superficial velocities and momentum fluxes), in search for parameters that are independent of the given experimental set-up. This paper reports a study on developing new flow regime maps with a broader range of applications by using dimensionless parameter groups as the map coordinates. Various flow regime maps were developed with the use of different combinations of these parameter groups, then they were examined and assessed using datasets from published experimental research and the MultiFlowMet II project for validation. This initial feasibility study develops proof-of-concept flow regime maps that demonstrate the potential of dimensionless parameter groups to more accurately characterise multiphase flow in horizontal pipes, with the optimisation of these maps being considered in future works. The analysis revealed that combinations of the mixture Froude number (Frm) versus the ratio of gas superficial velocity to liquid superficial velocity (vSG/vSL), with the liquid phase Froude number (FrL) versus the gas phase Froude number (FrG) show potential for unambiguous identification and mapping of flow regimes, even for datasets with a wider range of operating conditions.

Concentrated Solar Power (CSP) technology stands out among other renewable energy sources not only because of its ability to address current energy security and environmental challenges but because its energy can be stored for future use. To ensure optimum performance in this system, the heat losses need to be evaluated for better design. This work studies the natural convection in the receiver absorber tube of a CSP plant taking into consideration the influence of neighboring absorbers. A 2-Dimensional model was adopted in this study. Initially, a single absorber tube was considered, it was subjected to heat flux at the top wall, the bottom wall was insulated and a temperature differential was set up at the lateral walls. The dimensionless forms of Navier-Stokes and energy equations were solved using the finite element formulation of COMSOL Multiphysics software. The result obtained for a single absorber tube showed good agreement with existing research works. This validated model was then extended to multiple absorber tubes (two to six absorber tubes). On the basis of the study, there is an observed increase in the intensity and dominance of convective heat transfer with an increase in the number of absorber tubes. This is occasioned by an increase in the average surface temperature as well as average Nusselt number. For the Rayleigh number of 104, 105 and 106, the average Nusselt number increases with the number of absorber tubes by 13.87 %, 6.26 %, and 1.55 %, respectively. This increment suggests effect of thermal interactions among the neighboring absorber tubes

Unconventional reservoirs are normally characterized by dual porous media, which has both multi-scale pore and fracture structures, such as low permeability or tight oil reservoirs. The seepage characteristics of such reservoirs is mainly determined by micro-fractures, but conventional laboratory experimental methods are difficult to measure it, which is attribute to the dynamic cracking of these micro-fractures. The emerging digital core technology in recent years can solve this problem by developing an accurate pore network model and a rational simulation approach. In this study, a novel pore-fracture dual network model was established based on percolation theory. Fluid flow in the pore of two scales, micro-fracture and matrix pore, were considered, also with the impact of micro-fracture opening and closing during flow. Some seepage characteristic parameters, such as fluid saturations, capillary pressure, relative permeabilities, displacement efficiency in different flow stage, can be predicted by proposed calculating method. Through these work, seepage characteristics of dual porous media can be achieved.

Estimation of withdrawal water and filtered sediment amounts are important to obtain maximum efficiency from an intake structure. The purpose of this study is to develop empirical equations to predict Water Capturing Performance (WCP) and Sediment Release Efficiency (SRE) for Coanda type intakes. These equations were developed using 216 sets of experimental data. Intakes were tested under six different slopes, six screens, and three water discharges. In SRE experiments, sediment concentration was kept constant. Dimensionless parameters were first developed and then subjected to multicollinearity analysis. Then, nonlinear equations were proposed whose exponents and coefficients were obtained using the Genetic Algorithm method. The equations were calibrated and validated with 70 and 30% of the data, respectively. The validation results revealed that the empirical equations produced low MAE and RMSE and high R2 values for both the WCP and the SRE. Results showed outperformance of the empirical equations against those of MNLR. Sensitivity analysis carried out by the ANNs revealed that the geometric parameters of the intake were comparably more sensitive than the flow characteristics.

This work presents a physics-based predictive model for temperature rise in cylindrical solids heated by constant-strength, periodic-motion heat source. The heat source motion path, heat transfer boundary conditions and solid dimension are considered in the theoretical model. Analytical solutions to both the infinite or finite length cylinders are constructed with respect to convection and corresponding boundary conditions. Dimensionless controlling parameters are discussed to reveal temperature field evolution. The predicted results in the temperature rise agreed well with the measured data for a Z-direction feeding drive screw shaft system. The proposed model provides an efficient and accurate design tool for engineering calculation and process-parameter planning through inverse analysis.

In this study, the tensile strength, impact strength, and the hardness of the weld are determined. A criterion is proposed for describing the effect of residual stress on the weld mechanical properties. Dimensionless parameters such as Rya (the average of residual stress over the material yield strength), Rym (the maximum residual stress over the material yield strength), Ru2 (the difference in the residual stress over the material ultimate strength), and Ru3 (the difference ratio between the maximum and minimum of three-dimensional residual stresses over the material ultimate strength) are presented to describe the influence of residual stresses on the actual mechanical behavior of the welded pipe. Maximum Rya criterion and lowest strength are obtained at the weld gap center on the external surface of the pipe. The sharp decline in Ru2 criteria is consistent with the severe reduction in impact strength perpendicular to the weld gap.

In the study, experimental and theoretical studies were carried out to assess the influence of the shapes of dents in the tank wall on the stress-strain state of the defect zone. By testing fragments of a cylindrical tank, it was found that the most appropriate expression is (5), which could take into account the leaching of the tank wall, resulting in a decrease in the stress concentration index. At the same time, during theoretical studies in this paper, it was found that polynomials determined the stress concentration coefficient, where the obtained analytical expression data were compared with the data determined numerically in the ANSYS program, and it was found that the spread was from 2% to 10%. According to the results of a numerical study of the stress-strain state of the dent zone in the tank wall, graphical dependences of the stress concentration coefficient on the dimensionless depth of the dent for various values of the dimensionless radius of the dents and do not exceed 2% of the indicators that are obtained. At the conclusion of the experimental and numerical studies, a conclusion was made about the degree of influence of the geometric dimensions of the dents on the stress concentration index.

To reveal the temperature rise evolution mechanism of isotropic media subjected to reciprocating motion constant-strength point heat source, various forms of analytical solutions are derived on the basis of differentiated relative scales, and non-dimensionalized parameters are designed to characterize the thermal distribution regularities by utilizing numerical calculations. Temperature rise curves of media subjected to a reciprocating motion point heat source allow similar quasi-steady-state characteristics to appear, which finally achieve a stable state, so that the values of surplus temperature oscillate around the constant time-average quantity. The time to reach quasi-steady state, the time-averaged quantity and the fluctuation amplitude of surplus temperature are comprehensively impacted by the dimensionless distance parameter γ, the convective heat transfer parameter ω and the velocity and travel parameter β. This work discusses influence rules of temperature evolution in various relative-scale media and further enriches the moving heat source theory.

Perched beaches are an attractive nourishment design alternative especially when either the site conditions or the characteristics of both the native and the borrow sands lead to a non-intersecting profile. The observation and suggestion of the use of this type of coastal defense scheme dates back to the 1960’s, as well as the international experience in its construction. However, in spite of its use and the field and laboratory studies performed to-date, no design engineering guidance is available to support its design. Key dimensionless parameters that will be able to explain the performance of perched beaches have been identified, linking basic design variables such as: the wave height and period, the crest width and height, the depth at the toe of the sill, and the sand settling velocity. An engineering 4-step conceptual design method has been anticipated. This work will be expanded by systematic mobile-bed physical model tests - to be performed in a 36 x 3 x 1.5 m wave flume -, with the goal of producing engineering preliminary functional design guidelines of perched beaches based on the key dimensionless parameters herein identified.

Film downflow from captured liquid without wave formation and its destruction is one of the most important aspects in the development of separation equipment. Consequently, it is necessary to create well-organized liquid draining in areas of captured liquid. Thus, the proposed 3D mathematical model of film downflow allows for the determination of the hydrodynamic parameters of the liquid film flow and the interfacial surface. As a result, it was discovered that the interfacial surface depends on the proposed dimensionless criterion, which includes internal friction stress, channel length, and fluid density. Additionally, equations for determining the averaged film thickness, the averaged velocity vectors over the film thickness, the longitudinal and vertical velocity components, and the initial angle of streamline deviation from the vertical axis were analytically obtained.

Machining parameters needed for stable, high-performance high-speed machining could be found using mathematical models that need accurate measurements of modal parameters of the machining system. In-process modal parameters, however, can slightly differ from those measured offline and this can limit the applicability of simple measurement methods such as impact hammer tests. To study and extract the in-process modal parameters, mathematical models are used to define two key dimensionless parameters and establish their relationships with each other and the modal parameters. Based on these relationships, the modal parameters are extracted using two analytical methods, the two-point method (TPM), and the regression method (RM). As shown with experimental studies, the RM extracts the modal parameters successfully and while being much faster than the existing iteration-based methods, it provides stability lobe predictions that match well the experimental results. Furthermore, it is noted that the natural frequency parameter is estimated with much better relative precision compared to the damping ratio and the modal stiffness parameters. © 2019 Elsevier Ltd The funding for this research has been provided by the Swedish knowledge foundation under a KKS-Hög grant. Support from SandvikCoromant and GKN Aerospace are gratefully acknowledged in this project. In addition to valuable recommendations about the experiments by Martin Magnevall and Mikael Lundblad from Sandvik Coromant and Anders Wretland and Stefan Cedergren from GKN Aerospace, Sandvik Coromant provided end-mills, and Andreas Lindberg from GKN Aerospace operated the five-axis CNC machine tool used in the tests described in sections 3.1 and 3.2. Surface topography measurements presented in 3.1 are performed by Mr. Goran Hallum from Filmetrics Europe GmbH.

Submitted by Aline Batista (alinehb.ufpel@gmail.com) on 2020-06-10T02:59:54Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao__Aline_Saupe_Abreu_PPGRH.pdf: 10249271 bytes, checksum: a28ae98d72a4afc871d8aca456a80377 (MD5) Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2020-06-10T04:16:20Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao__Aline_Saupe_Abreu_PPGRH.pdf: 10249271 bytes, checksum: a28ae98d72a4afc871d8aca456a80377 (MD5) Made available in DSpace on 2020-06-10T04:16:20Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao__Aline_Saupe_Abreu_PPGRH.pdf: 10249271 bytes, checksum: a28ae98d72a4afc871d8aca456a80377 (MD5) Previous issue date: 2019-02-19 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES Descarregadores de fundo são estruturas hidráulicas presentes em um grande número de barragens de pequeno e médio porte, essenciais para a remoção de sedimentos nestes empreendimentos. Eles são incorporados ao paramento de montante e na porção inferior do volume útil dos reservatórios com o objetivo de aumentar a capacidade de armazenamento de água e a vida útil do empreendimento em questão. O funcionamento dos descarregadores de fundo ocorre através da remoção do sedimento por meio da capacidade de arraste do escoamento, sendo o fenômeno de assoreamento, oriundo de atividades antrópicas e naturais das bacias hidrográficas, um processo gradativo e inerente aos diferentes aproveitamentos de reservação de água. Em diversos locais do mundo, em função de sua importância, estão sendo desenvolvidas diferentes metodologias de análise dimensional e estimativa do cone de remoção de sedimentos depositados em reservatórios considerando a eficiência limitada das estruturas de descarga de fundo. Desta forma, o presente trabalho visa contribuir para a caracterização experimental do comportamento hidrodinâmico dos descarregadores de fundo e seus principais parâmetros hidráulicos e sedimentológicos que favorecem a remoção de sedimentos de fundo, não consolidados. Foram utilizados três modelos físico-experimentais distintos com diferentes características de diâmetro definidas aos descarregadores, vazões de ensaio e carga hidráulica sobre essas estruturas, tendo sido avaliadas as novas conformações de fundo em 4 (quatro) diferentes tipos de materiais: areia, borracha processada, carvão Cardiff e carvão CATA. Através dos perfis batimétricos, formados após o acionamento das estruturas de remoção, foram desenvolvidos novos parâmetros adimensionais que estimam o alcance e a largura máxima do cone de remoção representativo do processo de desassoreamento dos reservatórios em condições de Pressure Flushing. Além disso, foram verificadas as estimativas definidas em literatura por Meshkati et al. (2010a) e (2010b), Meshkati et al. (2010) apud Emamgholizadeh et al. (2013), Fathi-Moghadam et al. (2010) e Emamgholizadeh e Fathi-Moghadam (2014), para as dimensões máximas do cone de remoção, bem como o volume máximo de sedimentos removidos. Os adimensionais de estimativa de cota ( ), comprimento ( ) e largura ( ) máximos apresentaram boas correlações quando aplicados aos resultados obtidos dos ensaios realizados nos 3 (três) modelos analisados, dentro da dispersão usualmente verificada em estudos de sedimentos, sendo as características das partículas um dos mais importantes parâmetros para a futura aplicabilidade dos adimensionais em escala de protótipo. Bottom outlets are hydraulic structures present in a large number of small and medium size dams, essential for sediment removal in these enterprises. They are incorporated to the upstream facing and in the lower portion of the useful volume of the reservoirs in order to increase the water storage capacity and the useful life of the enterprise in question. The operation of the bottom outlets occurs through the removal of sediment by the dragging capacity of the flow, being the phenomenon of silting, originating from anthropic and natural activities of the hydrographic basins, a gradual process inherent to the different uses of water reservation. In several places around the world, due to its importance, are being developed different methodologies of dimensional analysis and estimation of the cone of sediment removal deposited in reservoirs considering the limited efficiency of the bottom outlet structures. In this way, the present work aims to experimentally identify the hydrodynamic behavior of the bottom outlets and their main hydraulic and sedimentological parameters that favor the removal of unconsolidated bottom sediments. Three distinctive physical-experimental models were used with different geometry characteristics proposed for the dischargers, assay flows and hydraulic load under these structures, having been evaluated the new bottom conformations in 4 (four) different types of materials: sand, processed rubber, Cardiff coal and CATA coal. Through the bathymetric profiles, extracted after the activation of the removal structures, new dimensionless parameters were developed that estimate the reach and maximum width of the removal cone representative of the desilting process of the reservoirs under Pressure Flushing conditions. In addition, were verified the estimates defined in literature by Meshkatiet al. (2010a) and (2010b), Meshkati et al. (2010) in Emamgholizadeh et al. (2013), Fathi-Moghadam et al. (2010) and Emamgholizadeh and Fathi-Moghadam (2014), for the maximum dimensions of the removal cone, as well as the maximum volume of sediments removed. The dimensionless of estimate depth ( ), length ( ) and width ( ) maximum presented good correlations when applied to the results obtained from the essays performed in the 3 (three) models analyzed, within the dispersion usually verified in sediment studies, being the characteristics of the particles one of the most important parameters for the future applicability of the dimensionless in scale of prototype.

The destruction of vertical cylindrical tanks results in both human and economic losses. Despite constant improvement of the manufacturing technology of cylindrical tanks, a complete analysis of the influence of various dents on stress-strain states was not performed. Dents are the most dangerous, unpredictable zones that are studied a little. It should be specially emphasized that there is no system to assess the stress concentrations in the dent zone, and the regulatory documents for the construction and operation of oil tanks do not take into account the stress-strain state in the dent. The paper presents the results of a finite element analysis of the stress-strain states of the cylindrical tanks with spherical dents. On the basis of the finite element analysis, approximate relationships are derived for stress concentration coefficients that can be used to calculate various sized cylindrical tanks with different dents. A cylindrical tank with a spherical dent is investigated. The reasons for dent formation are not considered. It is assumed that there are no residual stresses in the dent area. Simulating the stress-strain state of the tank, the conclusion is made that the greatest stresses are observed in the lower part of the dent. As in the lower part of the dent, the internal pressure of fuel oil is greater. At high values of the relative depth of the dent the maximum stresses are observed only at the lower boundary of the dent. An approximation technique for calculating the stress concentration factor in the dent is proposed. An approximate model of the stress concentration factor due to the dent size parameters is built for an example tank, Розглядаються результати скінченно-елементного аналізу напружено-деформованого стану циліндричного резервуару зі сферичними вм’ятинами. Отримано наближені залежності для коефіцієнтів концентрації напружень, які можуть бути використані при розрахунках циліндричних резервуарів зі сферичними вм’ятинами. Детально аналізується напружено-деформований стан резервуарів зі сферичними вм’ятинами, Разрушение вертикальных цилиндрических резервуаров приводит к человеческим и экономическим потерям. Несмотря на постоянное усовершенствование технологии производства резервуаров подробного анализа влияния различных вмятин на их напряженно-деформируемое состояние не было сделано. Вмятины – наиболее опасные области констhукции, которые мало исследованы. Особо следует подчеркнуть, что нет общих подходов для оценки концентрации напряжений в зоне вмятины и не разработаны регулирующие документы для конструирования емкостей, учитывающие напряженно-деформируемое состояние в области вмятины. В статье представлены результаты конечноэлементоного анализа напряженно-деформируемого состояния цилиндрических баков со сферическими вмятинами. С помощью конечноэлементного анализа получены приближенные формулы для оценки коэффициентов концентрации напряжений, которые могут использоваться для расчета различных емкостей с различными вмятинами. Предполагается, что в области вмятины нет остаточных напряжений. Из расчета напряженно-дефорируемого состояния сделан вывод, что наибольшие напряжения наблюдаются, если вмятина располагается в нижней части емкости. Это обусловлено тем, что в нижней части емкости больше величина внутреннего статического давления. Предложен приближенный подход для расчета коэффицентов концентрации напряжений. Получены приближенные формулы для оценки коэффициента концентрации напряжений.

The shock effects in laser shock processing of NiTi shape memory alloy were studied by dimensional analysis and finite element simulation. The essential dimensionless parameters controlling the residual stress distribution and plastically affected depth were found to be dimensionless pressure duration and peak pressure. By adopting the constitutive model considering the martensitic transformation and plasticity of deformation induced martensite, the influence of dimensionless parameters on the shock effects of shape memory alloy was studied numerically. The numerical results reveal the scaling law of shock effects on those dimensionless parameters quantitatively and the relationship between the plastically affected depth and peak pressure was validated with experimental results. A window of the optimal processing parameters could be obtained based on this study.

We study the dynamics of the rotational motion of a gyrostat satellite moving in the central Newtonian force field along a circular orbit. We propose a method for determining the equilibrium attitudes (equilibrium orientations) of a gyrostat satellite in the orbital coordinate system for given values of the gyrostatic moment vector and principal central moments of inertia, and obtain their existence conditions. For each equilibrium orientation, sufficient conditions for stability are obtained using a generalized energy integral such as a Lyapunov function. We conduct a detailed numerical analysis of domains where the stability conditions for equilibrium attitudes are satisfied depending on four dimensionless parameters of the problem. It is shown that the number of equilibrium attitudes of a gyrostat satellite for which the sufficient conditions of stability are satisfied in the general case varies from four to two with an increase in the magnitude of a gyrostatic moment. The results obtained in this paper can be used for constructing gravitational systems of control over the orientation of the Earth’s artificial satellites.

Wave overtopping at breakwaters is one of their essential hydraulic characteristics when determining the design crest level. This study concentrates on developing a new practical formula on predicting wave overtopping, by implementing two different statistical models, Multiple Linear Regression model (MLR) and Generalized Linear Regression model (GLM). The models consider dependency of overtopping on a wide variety of quantities and yield to simple forms of prediction. Such statistical analysis are performed on a set of data called CLASH (Crest Level Assessment of Coastal Structures by full scale monitoring, neural network prediction and Hazard Analysis on permissible wave overtopping) the most complete and available database on overtopping phenomena. Proposed equations are compared with most recently extracted as well as successful ones. Comprehensive assessments clearly show more accurate predictions in the case of mean overtopping at vertical seawalls.

Controlling the state of a Bose-Einstein condensate driven by a chirped frequency perturbation in a one-dimensional anharmonic trapping potential is discussed. By identifying four characteristic time scales in this chirped-driven problem, three dimensionless parameters ${P}_{1,2,3}$ are defined describing the driving strength, the anharmonicity of the trapping potential, and the strength of the particles interaction, respectively. As the driving frequency passes the linear resonance in the problem, and depending on the location in the ${P}_{1,2,3}$ parameter space, the system may exhibit two very different evolutions, i.e., the quantum energy ladder climbing (LC) and the classical autoresonance (AR). These regimes are analyzed both in theory and simulations with the emphasis on the effect of the interaction parameter ${P}_{3}$. In particular, the transition thresholds on the driving parameter ${P}_{1}$ and their width in ${P}_{1}$ in both the AR and LC regimes are discussed. Different driving protocols are also illustrated, showing efficient control of excitation and deexcitation of the condensate.

Experiments at the DIII-D tokamak have used dimensionless parameter scans to investigate the dependencies of intrinsic torque and momentum transport in order to inform a prediction of the rotation profile in ITER. Measurements of intrinsic torque profiles and momentum confinement time in dimensionless parameter scans of normalized gyroradius and collisionality are used to predict the amount of intrinsic rotation in the pedestal of ITER. Additional scans of Te/Ti and safety factor are used to determine the accuracy of momentum flux predictions of the quasi-linear gyrokinetic code TGLF. In these scans, applications of modulated torque are used to measure the incremental momentum diffusivity, and results are consistent with the E×B shear suppression of turbulent transport. These incremental transport measurements are also compared with the TGLF results. In order to form a prediction of the rotation profile for ITER, the pedestal prediction is used as a boundary condition to a simulation that uses TGLF to determine the transport in the core of the plasma. The predicted rotation is ≈20 krad/s in the core, lower than in many current tokamak operating scenarios. TGLF predictions show that this rotation is still significant enough to have a strong effect on confinement via E×B shear.

In this study we evaluate meteoroid mass and its other properties based on the observed atmospheric trajectory. With account for aerodynamics, we formulate a problem by introducing key dimensionless parameters in the model, responsible for the drag, mass loss and rotation of meteoroid. The proposed model is suitable to categorize various impact events in terms of meteor survivability and impact damage and thus, to analyze consequences that accompany collisions of cosmic bodies with planetary atmosphere and surface. The different types of events, namely, formation of a massive single crater (Barringer, Lonar Lake), dispersion of craters and meteorites over a large area (Sikhote-Alin), absent of craters and meteorites, but huge damage (Tunguska) are considered as illustrative examples. The proposed approach helps to summarize the data on existing terrestrial impacts and to formulate recommendations for further studies valuable for planetary defence. It also significantly increases chances of successful meteorite recoveries in future. In other words, the study represents a 'cheap' possibility to probe cosmic matter reaching planetary surface and it complements results of sample-return missions bringing back pristine samples of the materials. © by Leonid I. Turchak 2015. *Corresponding author e-mail: turchak@ccas.ru. This work is supported by the Russian Foundation for Basic Research, project No. 13-07-00276 A and the Academy of Finland, project No. 260027. This paper is reported as a plenary lecture in the 12th National Congress on Theoretical and Applied Mechanics, 2013, Saints Constantine and Helena, Varna, Bulgaria.

In this article, a method to model the heat flux during quenching has been developed to bring out the effect of initial soaking temperature. Quench probes with a diameter of 20 mm and a length of 50 mm were prepared from 304 L stainless steel. These probes were quenched from different initial soaking temperatures ranging from 400 �Cto 950 �C in water. Time-temperature data were recorded during the quenching. The heat flux and temperature at the quenched surface were estimated based on the inverse heat-conduction method. The computation results showed that the peak in the heat flux increased with an increase in the initial soaking temperature of the probes. The heat flux was dependent on the initial soaking temperature. A model for the surface heat flux was proposed as a function of dimensionless parameters. The model could be used to compute the heat flux at different surface temperatures and was specified as a boundary condition to simulate the quenching for the particular material-quenchant combination. The model was verified by running a direct quenching simulation with heat fluxes computed at different surface temperatures using the proposed model as a boundary condition in ANSYS, a commercial finite element program. � The Minerals, Metals & Materials Society and ASM International 2009.

Розроблено математичну модель удосконаленого гасителя пульсацій тиску з автоматичним підстроюванням параметрів у безрозмірних конструктивних параметрах. Описано особливості його конструктивного виконання та принцип роботи. Розраховані значення його коефіцієнта гасіння і критерії: узагальнений гашення пульсацій тиску та масогабаритний. Запропоновано використовувати для багатокритеріальної оптимізації конструктивних параметрів гасителя узагальнений критерій гашення пульсацій тиску у якості основного. Узагальнений критерій гашення пульсацій тиску і масогабаритний доцільно використовувати для порівняння показників технічного рівня гасителів різних типів. The mathematical model of working process of the improved pulsation dampener of pressure with the automatic tuning of parameters in dimensionless structural parameters has been developed, which is based on the concentration of parameters on Т- and G- by similar schemes and takes into account gas content of working liquid, her temperature, the time variation of viscosity, coefficients of expenditure of relative inductive and active resistance of channels. The peculiarities of his structural execution and principle of work have been described. The efficiency of work of pulsation dampener of pressure in composition hydrounits has been proposed to estimate, except the coefficient of damping, by next criteria: by the generalized criterion of damping of pressure pulsation and criterion of weight and size. By results of mathematical modeling of working processes in by volume hydrounit, in which has been installed pulsation dampener of pressure with automatic tuning of parameters, have been received oscillograms of pressure pulsation at its input and output and has been set its coefficient of damping.

When a micron-sized magnetizable particle is introduced into a suspension of nanosized magnetic particles, the nanoparticles accumulate around the microparticle and form thick anisotropic clouds extended in the direction of the applied magnetic field. This phenomenon promotes colloidal stabilization of bimodal magnetic suspensions and allows efficient magnetic separation of nanoparticles used in bioanalysis and water purification. In the present work, the size and shape of nanoparticle clouds under the simultaneous action of an external uniform magnetic field and the flow have been studied in detail. In experiments, a dilute suspension of iron oxide nanoclusters (of a mean diameter of 60 nm) was pushed through a thin slit channel with the nickel microspheres (of a mean diameter of 50 μm) attached to the channel wall. The behavior of nanocluster clouds was observed in the steady state using an optical microscope. In the presence of strong enough flow, the size of the clouds monotonically decreases with increasing flow speed in both longitudinal and transverse magnetic fields. This is qualitatively explained by enhancement of hydrodynamic forces washing the nanoclusters away from the clouds. In the longitudinal field, the flow induces asymmetry of the front and the back clouds. To explain the flow and the field effects on the clouds, we have developed a simple model based on the balance of the stresses and particle fluxes on the cloud surface. This model, applied to the case of the magnetic field parallel to the flow, captures reasonably well the flow effect on the size and shape of the cloud and reveals that the only dimensionless parameter governing the cloud size is the ratio of hydrodynamic-to-magnetic forces - the Mason number. At strong magnetic interactions considered in the present work (dipolar coupling parameter α≥2), the Brownian motion seems not to affect the cloud behavior. © 2014 American Physical Society.

Energy efficient microwave processing is important for enhanced material processing. The microwave processing of a material is non-trivial due to the highly nonlinear process dynamics associated with the occurrence of constructive and destructive interferences, based on the sample dimension and material dielectric properties. Destructive interferences may lead to wasteful microwave heating which, however, can be avoided by suitable alteration of the interference pattern via sample dimensions and material dielectric properties. Thus, an energy efficient processing requires a priori information on the interference patterns as a function of sample dimension and material dielectric properties, in order to minimize the destructive interferences and maximize the heating rate with minimal hot spot formation. The current work is an attempt to establish the generalized microwave power absorption characteristics within circular samples of varying sizes and materials. The analysis has been performed based on three dimensionless parameters, Nw, fp and fw, where fp and fw capture the effect of dielectric properties, and Nw captures the effect of the sample dimension. It has been shown that the entire spectrum of power absorption characteristics can be classified into (i) thin ( N w ≤ 0.1 ) , (ii) intermediate ( 0.1 N w 3 / ( 2 π f p ) ) , and thick ( 2 π N w f p ( ≡ N p ) ≥ 3 ) regimes based on their unique features. Two real-time scenarios of static and rotating samples have been analyzed, and the effect of various parameters in each regime has been presented in detail. It has been shown that time dependent simulations of the wave propagation within rotating samples can be avoided, by devising an “equivalent static representation”, which has been established for the first time in this work. The current work also highlights the possible identification of efficient microwave processing via forecasting of heating dynamics (heating rates and hot spot formations) for a few test materials, based on the material invariant analysis as a function of Nw, fp and fw.

A large rectangular industrial duct consists of plates stiffened with parallel wide flange sections. The plates along with stiffeners acts to resist the pressure loads and to carry other loads to the supports. The behaviours of the components of large industrial ducts are significantly different from the behaviours on which the current design methods are based on. Investigation presented herein deals with the design methods for spacing stiffeners, proportioning stiffeners and calculating shear resistance of side panel. Current method of spacing stiffeners is based on large deflection plate theory. A parametric study was conducted on dimensionless parameters identified in order to benefit from membrane action in partially yielding plate for spacing stiffeners. Design equations were established in terms of dimensionless pressure, plate slenderness and normalized out-of-plane deflection for three cases namely; 0%, 16.5% and 33% of through thickness yielding of the plate. Results show that approximately 50% increase in stiffener spacing when yielding of 16.5% of thickness is permitted. Under suction type pressure load, the unsupported compression flange and restrained tension flange lead to distortional buckling of the stiffeners. The current methods do not address distortional buckling adequately. A parametric study on dimensionless parameters governing the behaviour and strength of stiffened plat panels was conducted. The study indicated that the behaviour and strength of the stiffened panels could be a function of web slenderness and overall slenderness of the stiffener. The study also identified the slenderness limit of stiffener web for which the stiffener reaches the yield moment capacity. This study demonstrated the conservatism of current method. Finally a method was established to calculate the strength of stiffened plate panel subjected lateral pressure. Side panels adjacent to the supports transfer large amount of shear to the supports and, in addition, resist internal pressure. Currently the design of side panels for shear is based on the methods used for the web of fabricated plate girders. The behaviour and the characteristics between the web of plate girder and the thin side panels are significantly different. A parametric study was conducted on dimensionless parameters identified. It was concluded that the plate slenderness dominates the normalized shear strength of stockier side panels. The aspect ratio and plate slenderness influence the normalized shear strength of slender side panels. Design methods to calculate the shear strength of side panels were proposed. Doctor of Philosophy (PhD)

Предложены упрощенные эквивалентные структурные схемы разомкнутых электромехатронных преобразователей (ЭМТП) с шаговыми электродвигателями (ШЭД) и локально-замкнутого ЭМТП с вентильными электродвигателями (ВЭД). Упрощение достигнуто принятием ряда корректных допущений. The simplified equivalent block diagrams opened of electro-mechatronic converters with electric step motors and locally-closed electro-mechatronic converters with brushless DC motors are offered. Simplification is reached by acceptance of some correct to-pushcheny. Смирнов Юрий Сергеевич – д-р техн. наук, профессор кафедры «Приборостроение», Южно-Уральский госу дарственный университет; Тел: (351)2679012. Smirnov Yury Sergeevich – PhD, professor of Instrument making Department of SUSU; Tel: (351)2679012

International audience; A normalized model for piezoelectric and electromagnetic vibration energy harvesters is described, allowing a unique expression of the harvested power to be written. The normalization used points out three characteristic parameters of any generator: its coupling coefficient, its losses coefficient and its mechanical quality factor. The evolution of the normalized harvested power is theoretically studied as a function of these parameters. Experimental results and a bibliographic study present typical orders of magnitude of coupling and losses coefficients values for piezoelectric and electromagnetic generators, and put forward unusual dualities: while piezoelectric generators have low coupling and low losses coefficients, electromagnetic generators exhibit high resistive losses compensated by high coupling coefficients. For both generators almost the same normalized power can be harvested with these dual parameters. Finally, the scaling effect is investigated: it is notably shown that the power density of an electromagnetic generator does not decrease proportionately with its volume as it is commonly accepted.

7th International Conference on Quantum Theory and Symmetries, QTS7; Prague; Czech Republic; 7 August 2011 through 13 August 2011, The two circles theorem for hydrodynamic flow in annular domain bounded by two concentric circles is derived. Complex potential and velocity of the flow are represented as q-periodic functions and rewritten in terms of the Jackson q-integral. This theorem generalizes the Milne-Thomson one circle theorem and reduces to the last on in the limit q → ∞. By this theorem problem of vortex images in annular domain between coaxial cylinders is solved in terms of q-elementary functions. An infinite set of images, as symmetric points under two circles, is determined completely by poles of the q-logarithmic function, where dimensionless parameter q = r 2 2/r 1 2 is given by square ratio of the cylinder radii. Motivated by Möbius transformation for symmetrical points under generalized circle in complex plain, the system of symmetric spin coherent states corresponding to antipodal qubit states is introduced. By these states we construct the maximally entangled orthonormal two qubit spin coherent state basis, in the limiting case reducible to the Bell basis. Average energy of XYZ model in these states, describing finite localized structure with characteristic extremum points, appears as an energy surface in maximally entangled two qubit space. Generalizations to three and higher multiple qubits are found. We show that our entangled N qubit states are determined by set of complex Fibonacci and Lucas polynomials and corresponding Binet-Fibonacci q-calculus., TUBITAK, TBAG Project 110T679 and Izmir Institute of Technology

A comprehensive experimental investigation was carried out to understand the effect of vegetation in attenuating run-up over a plane slope of 1: 30 due to the propagation of cnoidal waves. Two different types of vegetation configurations, namely tandem and staggered, are considered. Dynamic pressures exerted along a vertical wall fronted by these two vegetation types were measured, and the typical variation of dimensionless peak pressures for different relative depths of submergence of the pressure ports is reported as a function of dimensionless parameters involving the vegetation and wave characteristics. Further, typical results on the variation of the dimensionless peak run-up versus the surf similarity parameter only for the staggered configuration are also herein reported. Finally, the percentage reduction in wave run-up and pressures on the wall due to the presence of wall fronted by vegetation are reported. � 2011 Copyright International Association for Hydro-Environment Engineering and Research.

The limited treatment available for Stewart platform characteristics leads to the lack of an efficient methodology for determining the optimum geometry for different tasks. In this paper, an effort is made to characterize the parameters for developing a reconfigurable Stewart platform for the contour generation application. A solution is provided through the formulation of dimensionless parameters in combination with a study on the generic parameters like configuration. The variable geometry approach for the reconfiguration of Stewart platform has been adopted for four different platforms, and a generic approach is formulated after studying different parameters. A stiffness model developed for contour generation application is used in tandem with this generic approach to identify the trajectory with maximum stiffness for complex contours. The proposed methodology provides a holistic approach to develop a complete set of design tool to choose the optimum geometry for any new reconfigurable Stewart platform to be developed. � 2008 Elsevier Ltd. All rights reserved.

For a reliable design of bolted joints, it is necessary to evaluate the actual fraction of the external load transmitted through the bolt. The stiffness of the bolt and the member of the joint decide the fractions of external load shared by the bolt and the member. Bolt stiffness can be evaluated simply by assuming the load flow to be uniform across the thickness and the deformation is homogeneous. Then, bolt may be modeled as a tension member and the stiffness can be easily evaluated. But, the evaluation of the member stiffness is difficult because of the heterogeneous deformation. In the present work, joint materials are assumed to be isotropic and homogeneous, and linear elastic axisymmetric finite element analysis was performed to evaluate the member stiffness. Uniform displacement and uniform pressure assumptions are employed in idealizing the boundary conditions. Wide ranges of bolt sizes, joint thicknesses, and material properties are considered in the analysis to evaluate characteristic behavior of member stiffness. Empirical formulas for the member stiffness evaluation are proposed using dimensionless parameters. The results obtained are compared with the results available in the literature. Copyright � 2009 by ASME.

We consider homogeneous turbulence in a conducting fluid that is exposed to a uniform external magnetic field while being sheared in fixed and rotating frames. We take both the frame-rotation axis and the applied magnetic field to be aligned in the direction normal to the plane of the mean shear. We find that a key parameter determining the structural morphology of the flow is the ratio of the time scale of the mean shear to the Joule time, τ shear/ τ m- When τ shear ≪ τ m, we find that the turbulence structures tend to align preferentially with the streamwise direction irrespective of the magnetic Reynolds number, R m. When τ shear ≫ τ m, we find that at low R m the turbulent eddies become elongated and aligned with the magnetic field, but at moderately high R m, there is partial streamwise alignment of the eddies. When τ shear ≈ τ m, we find that competing mechanisms tend to produce different structural anisotropies, and small variations in dimensionless parameters can have a strong effect on the structure of the evolving flow. For example, at R m ≪ 1, a preferential alignment of structures in the direction of the magnetic field emerges as the flow evolves, consistent with the predictions of the quasi-static approach. For R m ∼ 1, the structures are found to be equally aligned in the streamwise and spanwise direction at large times. However, when R m is moderately high (10 ≲ R m ≲ 50) this strong spanwise alignment is replaced by a preferential alignment of structures in the streamwise direction. Counter to intuition, we found evidence that strong rotation in combination with a spanwise magnetic field tends to promote a streamwise alignment of the eddies, at least when τ shear ≈ τ m. 1 231 236 231-236

Modeling of subsurface irradiance reflectance fields especially in turbid coastal, harbor and lagoon waters has important applications in ecology, engineering and optical remote sensing. The present study aims at exploring many possible causes of variation in the proportionality factor f and analyzing its effect on the subsurface irradiance reflectance in different waters. A new model is then developed to estimate this optical property as a function of the absorption coefficient (a), backscattering coefficient (bb), incident illumination condition, and other wavelength-depth dependent factors. Implementation of this new model is examined for five types of waters with varying turbidity and chlorophyll. Model results are verified with in situ measurements data and compared with the results from existing models. Formulas already proposed for estimating R in the previous studies and generally expressed by R = 0.33(bb/(a + bb)) or R = f (b b/(a + bb)) where f = 0.975-0.629?0 (?0 is the incident photons just below the sea surface) work fairly well in clear oceanic waters, but yield large errors in turbid coastal and lagoon waters due to the use of a constant value 0.33 or the dimensionless parameter f which does not account for certain processes in the model (e.g., multiple scattering, depth-dependent changes in the diffuse components of solar radiation, and spectral variation in f). By contrast, the new model estimates the reflectances having good agreement with in situ data from just below the water surface and throughout the water column. The improved performance of the present model is because it includes a parameterization of the proportionality factor f which varies with wavelength and depends on the sun angle, inherent optical properties, and diffuse attenuation coefficients. Knowledge related to interrelationships between inherent optical properties and apparent optical properties can be used to study the variability of the subsurface reflectance in homogeneous and stratified coastal waters with respect to many possible causes of its variations. � 2014 Optical Society of America.

Kaplama endüstrisi, metalurjik alanda ağır metal iyonu ile kirletilmiş atık çözeltinin oluştuğu en önemli sektörlerden biridir. Deneysel çalışmalarda klasik sistemler yerine hızlı madde transferine olanak sağlayan hareketli katot ve hareketli hücre-katot sistemleri dizayn edilerek bu sistemlerin çalışma ve ekonomik parametreleri araştırılmıştır. Yuvarlanan katodlu hücrede bakır geri kazanmak amacıyla gerçekleştirilen deneyler sonucunda optimize edilen şartlarda nihai bakır konsantrasyonu 5 ppm’e düşmüştür. Bakırın %99.95’i %68 akım verimi ve 4.4 kWh/kg Cu enerji tüketimi ile geri kazanılmıştır. Aynı hücrede nikel geri kazanımı amacıyla yapılan deneysel çalışmaların sonucunda ; elektrolitin pH=5.5?0.05 değerinde, 50°C’de, 325 A/m2 akım yoğunluğunda, %74 akım verimiyle nikelin %90’ı 4.2 kWh/kg Ni enerji tüketimi ile geri kazanılmıştır. Döner silindir katotlarla gerçekleştirilen bakırsızlaştırma deneylerinde ise 5 g/l Cu2+ ve 7.5 g/l H2SO4 içeren elektrolitin 1000 A/m2 akım yoğunluğunda 60°C yaklaşık 90 dakikalık elektroliz işlemi sonucunda %80 akım verimi 3.2 kWh/kg Cu spesifik enerji tüketimi ile nihai konsantrasyon 3 ppm değerine düşmüştür. Düşük konsantrasyonlarda yüksek akım verimi; katodun üzerinde ayrışan dentritik yapıdaki bakırın katoda 1 mm mesafedeki bir sıyırıcı sayesinde katod yüzeyinden uzaklaştırılmasıyla sağlanmıştır. Böylece döner elektrod hem hücre içindeki hidrodinamik şartları iyileştirilirken hem de sıyırıcı sayesinde büyüyen yüzeyinden dolayı hücrede geçerli olan hidrodinamik şartlardaki teorik limit akımın 9-10 kat üstünde bu akım veriminde hissedilir ölçüde değiştirmeyecek kadar hidrojen çıkararak çalışabilmiştir., Plating industry is one of the most important sectors in the field of metallurgy, where great amounts of waste solutions laden with heavy metal ions materialize. Electrolysis systems used within the framework of this thesis are; mobile and packed-particle cathode cells, and rotating cathode cell. In copper recovery experiments, carried out with “Rollschichtzelle”, the final copper concentration dropped to 5 ppm from the initial value of 10 g/l Cu2+. A 99.95% of copper recovery was obtained at a 68% current efficiency and 4.4 kWh/kg Cu energy consumption. In the same cell, 90% of the nickel was recovered at a 74% current efficiency and 4.2 kWh/kg Ni energy consumption, from the solutions containing 2 g/l nickel initially. Conditions of the electrolysis were: pH = 5.5?0.05, 50?C temperature, 325 A/m2 current density and 5-mm-diameter cathode granules, occupying 450 cm3 volume. In copper recovery experiments, carried out with rotating cylindrical cathodes, final copper concentrations of 3 ppm were reached with 80 % current efficiency and 3.2 kWh/kg Cu specific energy consumption, by the electrolysis of solution containing 5 g/l Cu2+ and 7.5 g/l H2SO4 , at 60°C and 1000 A/m2 current density for 90 minutes. High current efficiencies, reached at low concentrations, could be achieved by scraping the dendrites of copper deposits with a Plexiglas plate, positioned and fixed exactly 1mm away from the cathode surface. The rotating electrode not only improves the hydrodynamic conditions in the cell but it also permits working at current densities which are 9 to10 times higher than the theoretical limiting current valid for the shiny cylindrical cathodes, by keeping the length of dendrites (and thus, the enlarged cathode surface) constant, on account of thee scraper. Meanwhile, hydrogen evolution was allowed to sustain up to a certain degree above which it would disturb the current efficiency noticeably., Doktora, PhD

On considère un écoulement laminaire permanent en convection naturelle engendré par des effets combinés de chaleur et de masse au voisinage d'une surface verticale humide chauffée par un flux constant q. Deux méthodes numériques sont présentées : la première, approchée, utilise les solutions affines qui décrivent les phénomènes en termes d'une variable de similitude et de quatre paramètres ; la seconde est une méthode implicite de différences finies. Une comparaison des deux méthodes est présentée afin de tester les approximations des solutions affines. Ces résultats théoriques sont ensuite comparés aux mesures expérimentales.