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1
Takeo, Takashi, Masato Kawaguchi, Taichi Ishihara, and Toru Matsuzaki. "Effectiveness of Magnetic Sheets in Suppressing Magnetic Leakage in Automobile Wireless Energy Transfer Systems." Advances in Science and Technology 90 (October 2014): 51–56. http://dx.doi.org/10.4028/www.scientific.net/ast.90.51.
Повний текст джерелаАнотація:
Recently, wireless energy transfer techniques are being developed for hybrid (HEV) or electric (EV) vehicles. However, without taking any measures, magnetic field strength around energy transfer systems that employ solenoid type antennas is known to exceed regulated values in most countries. In this study, the application of magnetic sheets, which are widely used as EMC components, is proposed to suppress the magnetic field leakage from an automobile energy transfer system and the ability of magnetic leakage suppression with the magnetic sheet has been evaluated by means of electromagnetic simulation. Through these investigations, desirable system arrangements are discussed. As a result, if combined with a metal plate, non-conductive magnetic materials having large permeability has been found to be preferable.
2
DAHLBURG, RUSSELL B. "Transition to turbulent electric current sheet reconnection." Journal of Plasma Physics 57, no. 1 (January 1997): 35–45. http://dx.doi.org/10.1017/s0022377896005247.
Повний текст джерелаАнотація:
Electric current sheets develop in the solar corona when different flux systems come into contact. At these sheets magnetic energy is transformed into heat and kinetic energy by means of reconnection. We have previously demonstrated how to accelerate neutral sheet energy conversion by means of a transition to turbulent reconnection via ideal, three-dimensional secondary instabilities, as conjectured by Montgomery. In this paper we describe how our previous results are modified by the presence of a finite mean sheetwise magnetic field. We find a stabilization from this field, due to a decrease in energy transfer from the basic magnetic field to the three-dimensional perturbed fields. An increase in perturbed dissipative energy losses is also observed.
3
Herzfeld, Ute C., James Fastook, Ralf Greve, Brian McDonald, Bruce F. Wallin, and Phillip A. Chen. "On the influence of Greenland outlet glacier bed topography on results from dynamic ice-sheet models." Annals of Glaciology 53, no. 60 (2012): 281–93. http://dx.doi.org/10.3189/2012aog60a061.
Повний текст джерелаАнотація:
AbstractPrediction of future changes in dynamics of the Earth’s ice sheets, mass loss and resultant contribution to sea-level rise are the main objectives of ice-sheet modeling. Mass transfer from ice sheet to ocean is, in large part, through outlet glaciers. Subglacial topography plays an important role in ice dynamics; however, trough systems have not been included in bed digital elevation models (DEMS) used in modeling, because their size is close to the model resolution. Using recently collected CReSIS MCoRDs data of subglacial topography and an algorithm that allows topographically and morphologically correct integration of troughs and trough systems at any modeling scale (5 km resolution for SeaRISE), an improved Greenland bed DEM was developed that includes Jakobshavn Isbræ, Helheim, Kangerdlussuaq and Petermann glaciers (JakHelKanPet DEM). Contrasting the different responses of two Greenland ice-sheet models (UMISM and SICOPOLIS) to the more accurately represented bed shows significant differences in modeled surface velocity, basal water production and ice thickness. Consequently, modeled ice volumes for the Greenland ice sheet are significantly smaller using the JakHelKanPet DEM, and volume losses larger. More generally, the study demonstrates the role of spatial modeling of data specifically as input for dynamic ice-sheet models in assessments of future sea-level rise.
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Roy, Rajarshi, Ranjit Thapa, Shibsankar Biswas, Subhajit Saha, Uttam Kumar Ghorai, Dipayan Sen, E. Mathan Kumar, et al. "Resonant energy transfer in a van der Waals stacked MoS2 – functionalized graphene quantum dot composite with ab initio validation." Nanoscale 10, no. 35 (2018): 16822–29. http://dx.doi.org/10.1039/c8nr04412k.
Повний текст джерела
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Porter, Michael A., Dennis H. Martens, Thomas Duffy, and Sean McGuffie. "High-Temperature Heat Exchanger Tube-Sheet Assembly Investigation With Computational Fluid Dynamics." Journal of Pressure Vessel Technology 129, no. 2 (November 20, 2006): 313–15. http://dx.doi.org/10.1115/1.2716436.
Повний текст джерелаАнотація:
Many modern sulfur recovery unit process waste heat recovery exchangers operate in high-temperature environments. These exchangers are associated with the thermal reactor system where the tube-sheet–tube-ferrule assemblies are exposed to gasses at temperatures approaching 3000°F. Because sulfur compounds are present in the process gas, the carbon steel tube sheet and tubes in the assembly will be deteriorated by sulfidation as the operating metal temperature rises above 600°F. Ferrule systems are used to protect the carbon steel from exposure to excessive temperatures. The temperature distribution in the steel tube-sheet–tube-ferrule system is affected by process gas flow and heat transfer through the assembly. Rather than depend on “assumed” heat transfer coefficients and fluid flow distribution, a computational fluid dynamics investigation was conducted to study the flow fields and heat transfer in the tube-sheet assembly. It was found that the configuration of the ferrule installation has a large influence on the temperature distribution in the steel materials and, therefore, the possible sulfidation of the carbon steel parts.
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Hayat, T., Z. Iqbal, and M. Mustafa. "Flow of a Second Grade Fluid over a Stretching Surface with Newtonian Heating." Journal of Mechanics 28, no. 1 (March 2012): 209–16. http://dx.doi.org/10.1017/jmech.2012.21.
Повний текст джерелаАнотація:
ABSTRACTThis article describes the boundary layer flow and heat transfer in a second grade fluid over a stretching sheet. Heat transfer analysis is carried out in the presence of a Newtonian heating. The partial differential systems have been transformed into the ordinary differential systems by appropriate relations. Homotopy analysis method (HAM) is used for the solutions. Graphical and tabulated results are presented to see the significance of influential parameters on the velocity and temperature fields. It is seen that temperature profiles and heat transfer rate significantly increase by increasing the conjugate parameter (γ) for Newtonian heating.
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Asensio, M. C., and J. Seyed-Yagoobi. "Simulation of Paper-Drying Systems With Incorporation of an Experimental Drum/Paper Thermal Contact Conductance Relationship." Journal of Energy Resources Technology 115, no. 4 (December 1, 1993): 291–300. http://dx.doi.org/10.1115/1.2906435.
Повний текст джерелаАнотація:
A theoretical model for simulation of conventional steam-heated cylinder dryers is developed by considering the heat and mass transfer in a porous sheet during drying. Expressions for sheet shrinkage as a function of mass of water removed and for reductions in sheet porosity are derived for inclusion in the model. The interface thermal contact conductance of moist paper handsheet/metal interfaces has been experimentally investigated. A resulting empirical correlation, representing the thermal contact conductance between the cast iron dryer surface and paper web, is incorporated into the drying simulation model to reflect reductions in heat input to the sheet during drying. Finite difference techniques are used to obtain the numerical solutions. Average sheet moisture content and temperature along the length of the dryer section as well as average evaporation rates per cylinder are predicted by the model. Consideration of the internal dynamics of the drying process allows profiles of sheet moisture content, temperature, liquid flux, and vapor flux through the sheet thickness to be developed throughout the dryer section. Drying results are consistent with actual production cases. The model can be used to design dryer sections, study changes in operating conditions or in layout of a multi-cylinder dryer, or simulate the application of enhanced drying devices to a conventional drying section. The effect of the drum/paper contact conductance on drying rates and resultant dryer section requirements is provided as an example application of the model.
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Hisatomi, Takashi, and Kazunari Domen. "(Invited) Particulate Photocatalyst Systems for Sunlight-Driven Water Splitting." ECS Meeting Abstracts MA2018-01, no. 31 (April 13, 2018): 1891. http://dx.doi.org/10.1149/ma2018-01/31/1891.
Повний текст джерелаАнотація:
Sunlight-driven water splitting has been studied actively for production of renewable solar hydrogen as a storable and transportable energy carrier [1-3]. Both the efficiency and the scalability of water-splitting systems are important factors for practical utilization of renewable solar hydrogen because of the low areal density of solar energy. Particulate photocatalyst systems do not involve any secure electric circuit and thus can be spread over a wide area by inexpensive processes potentially. In this regard, activation of particulate photocatalysts and development of their reaction systems are important subjects. A semiconductor photocatalyst can split water into hydrogen and oxygen thermodynamically when the band gap straddles the potentials of the hydrogen evolution reaction (0 V vs. RHE) and the oxygen evolution reaction (+1.23 V vs. RHE). In addition, it is generally necessary to modify photocatalysts with appropriate cocatalysts in order to facilitate charge separation and surface redox reactions. The authors’ group has studied various semiconducting materials including oxides, (oxy)nitrides, and (oxy)chalcogenides for photocatalytic water splitting [1]. Recently, we have found that doping Al into SrTiO3 boosts the water splitting activity by two orders of magnitude [4]. The resultant Al-doped SrTiO3 achieved an apparent quantum yield (AQY) of 30% at 360 nm. Through the optimization of the preparation and modification methods of Al-doped SrTiO3, the AQY of photocatalytic water splitting has been upgraded to 56% and higher at 365 nm. Processing of such particulate photocatalysts into potentially extensible forms is to be presented [5]. Two different photocatalysts can also be combined so that hydrogen and oxygen are generated on the different photocatalysts [1,3]. Recently, the authors’ group has developed particulate photocatalyst sheets consisting of the hydrogen evolution photocatalyst (HEP) and the oxygen evolution photocatalyst (OEP) embedded into conductive layers by particle transfer [6-11]. A photocatalyst sheet consisting of La- and Rh-codoped SrTiO3 as the HEP and Mo-doped BiVO4 as the OEP embedded into a carbon conductor exhibits a solar-to-hydrogen energy conversion efficiency of 1.0% at ambient pressure [10]. The photocatalyst sheet shows significantly higher water splitting activity than the corresponding powder suspension systems, because the conductor layer transfers photogenerated electrons between photocatalyst particles effectively. In addition, evolution of hydrogen and oxygen in close proximity allows to prevent generation of pH gradient during the water splitting reaction. Therefore, the photocatalyst sheet is scalable directly without sacrificing the high activity. However, the absorption edge wavelengths of La- and Rh-codoped SrTiO3 and Mo-doped BiVO4 are 520 nm at most. It is necessary to utilize photocatalysts with longer absorption edge wavelengths to pursuit higher STH values. We have found that some (oxy)chalcogenides and (oxy)nitrides with narrower band gap energies are applicable as the HEP and the OEP of particulate photocatalyst sheets. In this talk, recent progress and future challenges in photocatalytic water splitting and system development will be presented. Hisatomi et al., Chem. Soc. Rev. 2014, 43, 7520. Hisatomi et al., Catal. Lett. 2015, 145, 95. Hisatomi et al., Faraday Discuss. 2017, 198, 11. Ham et al., J. Mater. Chem. A 2016, 4, 3027. Xiong et al., Catal. Sci. Technol. 2014, 4, 325. Minegishi et al., Chem. Sci. 2013, 4, 1120. Wang et al., J. Catal. 2015, 328, 308 Wang et al., Nat. Mater. 2016, 15, 611 Wang et al., Faraday Discuss. 2017, 197, 491 Wang et al., J. Am. Chem. Soc. 2017, 139, 1675. Hisatomi et al., Curr. Opin. Electrochem. 2017, 2, 148.
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Khan, Muhammad Ijaz, Ahmed Alsaedi, Salman Ahmad, and Tasawar Hayat. "Computational analysis of nanofluid and hybrid nanofluid in Darcy’s squeezing flow with entropy optimization." International Journal of Numerical Methods for Heat & Fluid Flow 29, no. 9 (September 2, 2019): 3394–416. http://dx.doi.org/10.1108/hff-02-2019-0133.
Повний текст джерелаАнотація:
Purpose This paper aims to examine squeezing flow of hybrid nanofluid inside the two parallel rotating sheets. The upper sheet squeezes downward, whereas the lower sheet stretches. Darcy’s relation describes porous space. Hybrid nanofluid consists of copper (Cu) and titanium oxide (TiO2) nanoparticles and water (H2O). Viscous dissipation and thermal radiation in modeling are entertained. Entropy generation analysis is examined. Design/methodology/approach Transformation procedure is implemented for conversion of partial differential systems into an ordinary one. The shooting scheme computes numerical solution. Findings Velocity, temperature, Bejan number, entropy generation rate, skin friction and Nusselt number are discussed. Key results are mentioned. Velocity field increases vs higher estimations of squeezing parameter, while it declines via larger porosity variable. Temperature of liquid particles enhances vs larger Eckert number. It is also examined that temperature field dominates for TiO2-H2O, Cu-H2O and Cu-TiO2-H2O. Magnitude of heat transfer rate and skin friction coefficient increase against higher squeezing parameter, radiative parameter, porosity variable and suction parameter. Originality/value The originality of this paper is investigation of three-dimensional time-dependent squeezing flow of hybrid nanomaterial between two parallel sheets. To the best of the authors’ knowledge, no such consideration has been carried out in the literature.
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Ramesh, G. K., B. J. Gireesha, and C. S. Bagewadi. "Heat Transfer in MHD Dusty Boundary Layer Flow over an Inclined Stretching Sheet with Non-Uniform Heat Source/Sink." Advances in Mathematical Physics 2012 (2012): 1–13. http://dx.doi.org/10.1155/2012/657805.
Повний текст джерелаАнотація:
This paper presents the study of momentum and heat transfer characteristics in a hydromagnetic flow of dusty fluid over an inclined stretching sheet with non-uniform heat source/sink, where the flow is generated due to a linear stretching of the sheet. Using a similarity transformation, the governing equations of the problem are reduced to a coupled third-order nonlinear ordinary differential equations and are solved numerically by Runge-Kutta-Fehlberg fourth-fifth-order method using symbolic software Maple. Our numerical solutions are shown to agree with the available results in the literature and then employ the numerical results to bring out the effects of the fluid-particle interaction parameter, local Grashof number, angle of inclination, heat source/sink parameter, Chandrasekhar number, and the Prandtl number on the flow and heat transfer characteristics. The results have possible technological applications in liquid-based systems involving stretchable materials.
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Ahmad, Sohail, Muhammad Ashraf, and Kashif Ali. "Nanofluid flow comprising gyrotactic microbes through a porous medium - a numerical study." Thermal Science, no. 00 (2020): 332. http://dx.doi.org/10.2298/tsci190712332a.
Повний текст джерелаАнотація:
Researchers have significantly contributed to heat transfer field and always made out much effort to find new solutions of heat transfer augmentation. In the concerned work, we have presented a novel study regarding heat and mass transfer flow of nanofluid in the presence of gyrotactic microbes through a porous medium past a stretching sheet. The nonlinear coupled ODEs are obtained after applying the persuasive tool of similarity transformation on governing model PDEs and then tackled numerically by exploiting the SOR (Successive over Relaxation) parameter method. The outcomes of assorted parameters for the flow are surveyed and discussed through graphs and tables. A graphical comparison is correlated with previously accomplished study and examined to be in an exceptional agreement. The culminations designate that the bioconvection Peclet number and microorganism concentration difference parameter enhance density of the motile microorganisms. Moreover, porosity parameter substantially increases shear stress on sheet surface. The addition of nanoparticles in microorganisms is beneficial to improvise the thermal efficiency of many systems like bacteria powered micro-mixers, microfluidics devices like micro-volumes and enzyme biosensor, microbial fuel cells and bio-microsystems like chip-shaped microdevices.
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Patil, Mamata, Mahesha, and C. S. K. Raju. "Convective conditions and dissipation on Tangent Hyperbolic fluid over a chemically heating exponentially porous sheet." Nonlinear Engineering 8, no. 1 (January 28, 2019): 407–18. http://dx.doi.org/10.1515/nleng-2018-0003.
Повний текст джерелаАнотація:
Abstract In this present analysis we investigated the steady-state magnetohydrodynamic boundary layer flow of tangent hyperbolic fluid over an exponentially stretching surface in the presence of heat source and chemical reaction. The chemical reaction with combination of exponential surface has significance in many industrial and manufacturing systems. The partial nonlinear differential equations are transformed into ordinary differential equations by using the similarity conversion and the accomplished boundary layer ordinary differential equations are elucidated numerically by using Shooting technique. The effects of numerous non-dimensional governing factors on velocity, temperature and concentration profiles were depicted graphically and analyzed in detail. The numerically computed results of Skin friction factor, Nusselt and Sherwood numbers are presented in tabular form for suction and injection cases separately.Heat transfer rate at the surface increases with increasing values of power law of index and whereas it declines with the magnetic field, heat source and chemical reaction parameters. It observed that Biot number enhances the skin friction, Nusselt number and decrease the Sherwood number.Heat transfer rate and mass transfer rate increases and skin friction decreases with increasing Eckert number.
13
Merrikh-Bayat, Farshad, and Mahdi Afshar. "Extending the Root-Locus Method to Fractional-Order Systems." Journal of Applied Mathematics 2008 (2008): 1–13. http://dx.doi.org/10.1155/2008/528934.
Повний текст джерелаАнотація:
The well-known root-locus method is developed for special subset of linear time-invariant systems known as fractional-order systems. Transfer functions of these systems are rational functions with polynomials of rational powers of the Laplace variables. Such systems are defined on a Riemann surface because of their multivalued nature. A set of rules for plotting the root loci on the first Riemann sheet is presented. The important features of the classical root-locus method such as asymptotes, roots condition on the real axis, and breakaway points are extended to fractional case. It is also shown that the proposed method can assess the closed-loop stability of fractional-order systems in the presence of a varying gain in the loop. Three illustrative examples are presented to confirm the effectiveness of the proposed algorithm.
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Qayyum, Sajid, Tasawar Hayat, Ahmed Alsaedi, and Bashir Ahmad. "Non-linear thermal radiation and magnetic field effects on the flow Carreau nanofluid with convective conditions." Thermal Science 24, no. 2 Part B (2020): 1217–28. http://dx.doi.org/10.2298/tsci180130307q.
Повний текст джерелаАнотація:
Main features of the present analysis is to investigate the MHD non-linear mixed convection flow of Carreau nanofluid. Flow is due to stretching sheet with thermal and solutal convective conditions. Intention in present analysis is to develop a model for nanomaterial. The non-linear ordinary differential systems are obtained. Homotopy algorithm leads to solutions development. Velocity, temperature, nanoparticles concentration, surface drag force, and heat and mass transfer rate are displayed and argued. It is revealed that qualitative behaviors of velocity and layer thickness are reverse for material and magnetic parameters. Temperature field and heat transfer rate are similar observation for thermal Biot numbers. Moreover qualitative behaviors of nanoparticles concentration and mass transfer rate are reverse for larger Brownian motion.
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Steckiewicz, Adam, Jacek Maciej Stankiewicz, and Agnieszka Choroszucho. "Numerical and Circuit Modeling of the Low-Power Periodic WPT Systems." Energies 13, no. 10 (May 22, 2020): 2651. http://dx.doi.org/10.3390/en13102651.
Повний текст джерелаАнотація:
This article presents a method for analysis of the low-power periodic Wireless Power Transfer (WPT) system, using field and circuit models. A three-dimensional numerical model of multi-segment charging system, with periodic boundary conditions and current sheet approximation was solved by using the finite element method (FEM) and discussed. An equivalent circuit model of periodic WPT system was proposed, and required lumped parameters were obtained, utilizing analytical formulae. Mathematical formulations were complemented by analysis of some geometrical variants, where transmitting and receiving coils with different sizes and numbers of turns were considered. The results indicated that the proposed circuit model was able to achieve similar accuracy as the numerical model. However, the complexity of model and analysis were significantly reduced.
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Jandaghi Shahi, Vahid, and Abolfazl Masoumi. "Integration of in-plane and out-of-plane dimensional variation in multi-station assembly process for automotive body assembly." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 234, no. 6 (December 23, 2019): 1690–702. http://dx.doi.org/10.1177/0954407019889455.
Повний текст джерелаАнотація:
Automotive body assembly systems contain multiple operations in multi-station processes. One of the most critical challenges for such manufacturing systems is dimensional quality, which is affected by the accumulation and propagation of variation caused by manufacturing imperfections. However, sheet metal part compliancy behavior makes the variation modeling method extremely intricate when both rigid (in-plane) and compliant (out-of-plane) variations are considered. This paper develops a more accurate variation propagation model to describe dimensional variation of sheet metal assembly in multi-station assembly system through involving both the variation types simultaneously as well as the impacts of assembly operations on each other. In this methodology, three sources of deviations—non-ideal parts, fixture errors, and assembly operations effects—are taken into account. The variation generated in every assembly operation (placing, clamping, fastening, and releasing steps) and the variation propagation through station-to-station interaction (repositioning) are analyzed by the transfer function mechanism. In the in-plane direction, the stream of variation analysis is adopted to obtain the rigid transfer function to describe the position and orientation relationships between part and assembly element errors. For the simulation of part deformation during the assembly process in the out-of-plane direction, the compliant transfer functions are extracted by variation response methodology. A nested state space model is used to integrate the overall assembly variation by updating part geometry after each assembly operation. The capability of proposed method is illustrated through a case study on an automotive body side assembly process.
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Partington, K. C., and C. G. Rapley. "Analysis and Simulation of Altimeter Performance for the Production of Ice Sheet Topographic Maps." Annals of Glaciology 8 (1986): 141–45. http://dx.doi.org/10.1017/s0260305500001324.
Повний текст джерелаАнотація:
Satellite-borne, radar altimeters have already demonstrated an ability to produce high-precision, topographic maps of the ice sheets. Seasat operated in a tracking mode, designed for use over oceans, but successfully tracked much of the flatter regions of the ice sheet to ± 72° latitude. ERS-1 will extend coverage to ± 82° latitude and will be equipped with an ocean mode similar to that of Seasat and an ice mode designed to permit tracking of the steeper, peripheral regions. The ocean mode will be used over the flatter regions, because of its greater precision. Altimeter performance over the ice sheets has been investigated through a study of Seasat tracking behaviour and the use of an altimeter performance simulator, with a view to assessing the likely performance of ERS-1 and the design of improved tracking systems. Analysis of Seasat data shows that lock was frequently lost, as a result of possessing a non-linear height error signal over the width of the range window. Having lost lock, the tracker frequently failed to transfer rapidly and effectively to track mode. Use of the altimeter performance simulator confirms many of the findings from Seasat data and it is being used to facilitate data interpretation and mapping, through the modelling of waveform sequence.
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Partington, K. C., and C. G. Rapley. "Analysis and Simulation of Altimeter Performance for the Production of Ice Sheet Topographic Maps." Annals of Glaciology 8 (1986): 141–45. http://dx.doi.org/10.3189/s0260305500001324.
Повний текст джерелаАнотація:
Satellite-borne, radar altimeters have already demonstrated an ability to produce high-precision, topographic maps of the ice sheets. Seasat operated in a tracking mode, designed for use over oceans, but successfully tracked much of the flatter regions of the ice sheet to ± 72° latitude. ERS-1 will extend coverage to ± 82° latitude and will be equipped with an ocean mode similar to that of Seasat and an ice mode designed to permit tracking of the steeper, peripheral regions. The ocean mode will be used over the flatter regions, because of its greater precision.Altimeter performance over the ice sheets has been investigated through a study of Seasat tracking behaviour and the use of an altimeter performance simulator, with a view to assessing the likely performance of ERS-1 and the design of improved tracking systems. Analysis of Seasat data shows that lock was frequently lost, as a result of possessing a non-linear height error signal over the width of the range window. Having lost lock, the tracker frequently failed to transfer rapidly and effectively to track mode. Use of the altimeter performance simulator confirms many of the findings from Seasat data and it is being used to facilitate data interpretation and mapping, through the modelling of waveform sequence.
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Schwarzer, T., and H. J. Bart. "Mass and Heat Transfer at Different Heat Exchange Surfaces and Their Suitability for Use in Thermal Desalination Plants." Open Chemical Engineering Journal 10, no. 1 (June 3, 2016): 74–86. http://dx.doi.org/10.2174/1874123101610010074.
Повний текст джерелаАнотація:
A new concept for small scale multi-stage distillation (MSD) desalination plants is presented allowing an installation in remote rural areal due to low maintenance, operating and investment costs. It is based on extensive studies on heat and mass transfer using 6 different condensation / heat transfer surfaces or material combinations. Basically all 6 condensation surfaces except glass are of a sheet metal or an expanded metal (to the evaporation side) in combination to an acid- and heat-resistant foil (on the salt water side). The basic experiments were performed in a "lab scale" unit to determine their thermodynamic and structural characteristics and user-friendliness. After validation in a prototype novel oxidic condensation surfaces (AF) and material combinations are in actual use in the new MSD systems, following the requirements, including a good wetting and condensation behavior and a good heat transfer.
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Meng, Tao, Linlin Tan, Ruying Zhong, Huiru Xie, and Xueliang Huang. "Research on Metal Foreign Object Detection of Electric Vehicle Wireless Charging System Based on Detection Coil." World Electric Vehicle Journal 12, no. 4 (October 19, 2021): 203. http://dx.doi.org/10.3390/wevj12040203.
Повний текст джерелаАнотація:
Due to the open structure of wireless charging systems, foreign objects are inevitably involved. In the process of energy transfer, the intervention of metal foreign objects will cause the system to deviate from the normal operating point and even cause safety accidents. Therefore, metal foreign objects detection (MOD) technology is of considerable importance. In this paper, a metal foreign object detection system of a wireless power transfer (WPT) system based on the symmetrical detection coil was designed, and a MOD method based on frequency scanning is proposed. The coil size of the WPT system was designed based on SAE-J2954 standard. In addition, the suitable detection coil was installed at the transmitting coil. The system model was established in ANSYS simulation software, and 5 cm × 5 cm copper sheet and iron sheet were used as the metal to be detected. The result shows that the self-induction of the detection coil at the position of the foreign object can achieve a fluctuation of 52.46% and −34.72%, and the resonant frequency of the detection system is offset by 24.7% and −18.82%, respectively. Finally, the experimental platform of MOD system was built, and the effectiveness of the system was verified.
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Soleimani, Mohammad, and Mustafa Shadab. "Roles and functions of special purpose vehicles (SPV); a comparison between Islamic and conventional finance." Journal of Emerging Economies and Islamic Research 8, no. 1 (January 31, 2020): 1. http://dx.doi.org/10.24191/jeeir.v8i1.6219.
Повний текст джерелаАнотація:
The SPV (special purpose vehicle) is one of the key components of the securitization in both Islamic and conventional finance; however the details of how the transactions are implemented differ subject to the mode of securitization in Islamic and conventional finance. In conventional finance, the bank establishes a SPV and transfers its asset from its balance sheet to the SPV. The assets are used as the collateral for issuing securitized, debt-like instruments. Nevertheless, in Islamic finance mode of securitization, the SPV just services the cash flows for security holders and do participate in debt-issuance. This difference is originated from the risk-sharing principle in asset-based Islamic finance which contrasts with risk-transfer nature of an interest-based conventional finance and results in important differences in ownership right and valuation of SPVs in the two financial systems
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Gireesha, Bijjanal Jayanna, K. Ganesh Kumar, N. G. Rudraswamy, and S. Manjunatha. "Effect of Viscous Dissipation on Three Dimensional Flow of a Nanofluid by Considering a Gyrotactic Microorganism in the Presence of Convective Condition." Defect and Diffusion Forum 388 (October 2018): 114–23. http://dx.doi.org/10.4028/www.scientific.net/ddf.388.114.
Повний текст джерелаАнотація:
This article deals with the combined effects of viscous dissipation and convective condition on 3D flow, heat and mass transfer of a nanofluid over a stretching sheet by considering gyrotactic microorganism. Appropriate transformations yield the nonlinear ordinary differential systems. The resulting nonlinear system has been solved. Role of substantial parameters on flow fields as well as on heat, mass and microorganism transportation rates are determined and conferred in depth through graphs. It is found that, the larger values of bio-convection Schmidt number decreases the microorganisms profile.
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Chavez, Rosa-Hilda, Nicolas Flores-Alamo, and Javier de J. Guadarrama. "Experimental Evaluation of Sulfur Dioxide Absorption in Water Using Structured Packing." International Journal of Chemical Engineering 2012 (2012): 1–6. http://dx.doi.org/10.1155/2012/579381.
Повний текст джерелаАнотація:
An experimental study of hydrodynamic and mass transfer processes was carried out in an absorption column of 0.252 m diameter and 3.5 m of packed bed height developed by Mexican National Institute of Nuclear Research (ININby its acronym in Spanish) of stainless steel gauze corrugated sheet packing by means of SO2-air-water systems. The experiments results include pressure drop, flows capacity, liquid hold-up, SO2composition, and global mass transfer coefficient and mass transfer unit height by mass transfer generalized performance model in order to know the relationship between two-phase countercurrent flow and the geometry of packed bed. Experimental results at loading regimen are reported as well as model predictions. The average deviation between the measured values and the predicted values is±5% of 48-data-point absorption test. The development of structured packing has allowed greater efficiency of absorption and lower pressure drop to reduce energy consumption. In practice, the designs of equipment containing structured packings are based on approximations of manufacturer recommendations.
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Ismoen, Muhaimin, Radiah Bte Mohamad, R. Kandasamy, Suliadi Firdaus Sufahani, Fazlul Karim, and Muhamad Sabirin. "Numerical Investigation for Convective Heat Transfer of CNT Nano-Fluids over a Stretching Surface." Materials Science Forum 961 (July 2019): 148–55. http://dx.doi.org/10.4028/www.scientific.net/msf.961.148.
Повний текст джерелаАнотація:
The performance of carbon nanotube (CNT) nanofluids on convective heat transfer over a stretching sheet was investigated under thermal stratification and magnetic field effects. Water, engine oil and ethylene glycol are used as the base fluids. The governing equations are transformed into a system of coupled nonlinear ordinary differential equations using similarity transformations and solved numerically using the fourth-order Runge–Kutta–Fehlberg in conjunction to shooting method. The CNT nanofluids with an engine oil base fluid shows the highest thermal conductivity in comparison to ethylene glycol and water, respectively. Potential application of the thermal conductivity enhancement of CNT nanofluid is to increase the energy-efficient mechanical systems in heating, cooling and ventilation of the indoor environment.
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Kim, Hong Seok, Muammer Koc, and Jun Ni. "Determination of Proper Temperature Distribution for Warm Forming of Aluminum Sheet Materials." Journal of Manufacturing Science and Engineering 128, no. 3 (November 9, 2005): 622–33. http://dx.doi.org/10.1115/1.2162913.
Повний текст джерелаАнотація:
In warm forming of aluminum sheet materials, determination, realization, and maintenance of optimal temperature gradient is a key process parameter for increased formability. In this study, a two-phase procedure for efficient and accurate determination of proper temperature condition for warm forming of aluminum sheet metal blanks is presented using a hybrid 3D isothermal/non-isothermal finite element analysis (FEA) and design of experiments (DOE) approach. First, the relative trend, priority and overall temperature ranges of aluminum sheet metal blank regions are obtained using isothermal FE modeling and DOE techniques to reduce the analysis time significantly. In this phase, different temperature levels were assigned onto different regions of the deforming blank material (i.e., holding region, corner region, etc.). Heat transfer with the tooling and environment during the deformation process is ignored in order to achieve rapid predictions. Second, few additional non-isothermal FEAs, taking heat transfer into account, are conducted to validate and to refine the warm forming conditions based on the results from the isothermal FEA/DOE analysis. The proposed hybrid methodology offers rapid and relatively accurate design of warm forming process, especially for large parts that require 3D FE analysis. In addition, effects of forming speed (v), friction (μ), and blank holder pressure on formability are investigated. Increasing part formability is observed with decreasing punch speed and blank holder pressure while an optimal process window is found in case of varying friction coefficients.
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Mahal, B. S., D. E. R. Clark, and J. E. L. Simmons. "Mass-Spring Simulation of Deformation in Elastic Sheet Structures." Presence: Teleoperators and Virtual Environments 10, no. 3 (June 2001): 331–42. http://dx.doi.org/10.1162/105474601300343649.
Повний текст джерелаАнотація:
Traditionally, continuous deformable models are represented using control points that are arranged in a grid format. The interaction properties between these points are controlled via a series of interconnections that are used in physically based modeling to represent environmental effects within a simulation. These effects vary from the transfer of forces from one control point (or node) to its neighboring nodes, through to representing real-world forces such as friction and energy damping that affect any object placed in an uncontrolled environment. This paper presents a real-time, computationally inexpensive environment for accurate simulations of sheet materials on a personal computer. The approach described differs from other techniques through its novel use of multilayer sheet structures. The ultimate aim is to incorporate into the environment the capacity to simulate a range of temperatures. A pseudo-immersive “window on world” (WoW) environment is used to handle the implementation of the real-time, aesthetically accurate deformation algorithm (MaSSE-Mass-Spring Simulation Engine). The motion of the sheet is controlled by simulated gravity and through its interaction with a mouse-pointing device. In addition, the mouse may be used to manipulate the sheet. An obvious application of the environment is centered on mechanical engineering-based real-time simulations of heat-sensitive sheet materials. This would allow for a wide range of applications in virtual manufacturing.
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du Toit, G. J. G., M. C. Ramphao, V. Parco, M. C. Wentzel, and G. A. Ekama. "Design and performance of BNR activated sludge systems with flat sheet membranes for solid-liquid separation." Water Science and Technology 56, no. 6 (September 1, 2007): 105–13. http://dx.doi.org/10.2166/wst.2007.643.
Повний текст джерелаАнотація:
The use of immersed membranes for solid-liquid separation in biological nutrient removal activated sludge (BNRAS) systems was investigated at lab scale. Two laboratory-scale BNR activated sludge systems were run in parallel, one a MBR system and the other a conventional system with secondary settling tanks. Both systems were in 3 reactor anaerobic, anoxic, aerobic UCT configurations. The systems were set up to have, as far as possible, identical design parameters such as reactor mass fractions, recycles and sludge age. Differences were the influent flow and total reactor volumes, and the higher reactor concentrations in the MBR system. The performances of the two systems were extensively monitored and compared to identify and quantify the influence of the membranes on system response. The MBR UCT system exhibited COD, FSA, TKN, TP and TSS removals that were consistently equivalent or superior to the conventional system. Better P removal in the MBR was attributed to lower observed P uptake in the anoxic zone. High nitrate loads to the anoxic reactor appeared to be the determining factor in stimulating P uptake. The MBR UCT system had a greater sludge production than the conventional system. This was partly attributable to the retention of all solids in the MBR reactor. For steady state design this increase is accommodated by increasing the influent unbiodegradable particulate COD fraction. Additionally an attempt was made to determine the Alpha values in the oxygen transfer rate. This paper briefly summarises and compares the results from both systems, and the conclusions that can be drawn from these results.
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Casamichele, L., F. Quadrini, and V. Tagliaferri. "Process-Efficiency Prediction in High Power Diode Laser Forming." Journal of Manufacturing Science and Engineering 129, no. 5 (January 31, 2007): 868–73. http://dx.doi.org/10.1115/1.2738124.
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The present work is an experimental investigation on the laser forming process of aluminum alloy and stainless-steel thin sheets. A high-power diode laser (HPDL) with a nonsymmetric spot configuration was employed at medium and low scanning rates. The tests were performed at different operating conditions: scanning rate, laser spot orientation, and laser beam power. The experimental results revealed the great influence of the laser spot orientation on the total bending angle and the harmful effect of the surface melting during heating. Spot orientation significantly affects the treated area extension during laser scanning. Employing an analytical thermo-mechanical model, a dimensionless processing map can be presented that allows the prediction of the sheet bending angle depending on the material properties and machining parameters. Dimensional terms of the processing map can be associated to efficiency terms for heat transfer and bending.
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Abraham, Annamma, and LS Rani Titus. "Boundary Layer Flow of Ferrofluid over a Stretching Sheet in the presence of Heat Source/Sink." Mapana - Journal of Sciences 10, no. 1 (June 30, 2011): 14–24. http://dx.doi.org/10.12723/mjs.18.2.
Повний текст джерелаАнотація:
The boundary layer flow of ferrofluid over a stretching sheet with heat source is considered. It is assumed that the magnetic field is sufficiently strong enough to saturate the ferrofluid and the variation of magnetization with temperature can be approximated by a linear function of temperature difference. The boundary layer approximation is used and the transformed governing differential equations are solved using the Shooting technique based on Runge - Kutta Fehlberg and Newton Raphson methods. The effects of various parameters on velocity profiles and wall heat transfer are presented graphically. The results have possible industrial applications in liquid based systems involving stretchable materials.
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Greenhalgh, Scott R., John H. McBride, John M. Bartley, R. William Keach, Brooks B. Britt, and Bart J. Kowallis. "Along-strike variability of thrust fault vergence." Interpretation 3, no. 3 (August 1, 2015): SX1—SX12. http://dx.doi.org/10.1190/int-2014-0182.1.
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The 3D kinematic evolution of thrust systems, in which vergence changes along strike, is poorly understood. This study uses 3D seismic data from Big Piney-LaBarge field, Wyoming, to examine the geometry and kinematics of two faults at the leading edge of the Hogsback thrust sheet, the frontal thrust of the Late Cretaceous Sevier fold-thrust belt. These thrusts lie along strike of each another and share an east-vergent detachment within the Cretaceous Baxter Shale. The two thrusts verge in opposite directions: The southern thrust verges eastward forming a frontal ramp consistent with major thrusts of the Sevier belt, whereas the northern thrust verges westward to form a type 1 triangle zone with the Hogsback thrust. The thrusts have strike lengths of 5 km (3.1 mi) and 8 km (5.0 mi), respectively, and they are separated by a transfer zone of less than 0.5 km (0.3 mi) wide. Strata in the transfer zone appear to be relatively undeformed, but reflections are less coherent here, which suggests small offsets unresolved by the seismic survey. Retrodeformable cross sections and a structure contour map on the Cretaceous Mesaverde Group indicate that shortening varies along strike, with a pronounced minimum at the transfer zone and greater shortening across the northern, west-vergent thrust (610 m [2000 ft]) than across the southern, east-vergent thrust (230 m [755 ft]). Mapping of these thrusts suggests that they propagated laterally toward each other to form a type 1 antithetic fault linkage in the transfer zone. Spatial patterns expressed in seismic attributes in and near the detachment horizon, which include waveform classification and spectral decomposition, suggest that stratigraphic variations may have pinned the detachment, thus localizing the transfer zone. Thickness variations in the thrust sheet also may have influenced the thrust geometry. Our study provides an analog for analysis of similar complex contractional belts around the world.
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Gutiérrez, Yael, Maria M. Giangregorio, April S. Brown, Fernando Moreno, and Maria Losurdo. "Understanding Electromagnetic Interactions and Electron Transfer in Ga Nanoparticle–Graphene–Metal Substrate Sandwich Systems." Applied Sciences 9, no. 19 (September 30, 2019): 4085. http://dx.doi.org/10.3390/app9194085.
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Plasmonic metal nanoparticle (NP)–graphene (G) systems are of great interest due their potential role in applications as surface-enhanced spectroscopies, enhanced photodetection, and photocatalysis. Most of these studies have been performed using noble metal NPs of silver and gold. However, recent studies have demonstrated that the noble metal–graphene interaction leads to strong distortions of the graphene sheet. In order to overcome this issue, we propose the use of Ga NPs that, due to their weak interaction with graphene, do not produce any deformation of the graphene layers. Here, we analyze systems consisting of Ga NP/G/metal sandwich coupling structures, with the metal substrate being, specifically, copper (Cu) and nickel (Ni), i.e., Ga NP/G/Cu and Ga NPs/G/Ni. We experimentally show through real-time plasmonic spectroscopic ellipsometry and Raman spectroscopy measurements of the quenching of the Ga NP localized surface plasmon resonance (LSPR) depending on the wetting of the graphene by the Ga NPs and on the electron transfer through graphene. Theoretical finite-difference time-domain (FDTD) simulations supportively demonstrate that the LSPR in such sandwich structures strongly depends on the contact angle of the NP with graphene. Finally, we also provide evidence of the electron transfer from the Ga NPs into the graphene and into the metal substrate according to the work function alignments. These considerations about the contact angle and, consequently, geometry and wetting of the metal NPs on graphene, are useful to guide the design of those plasmonic systems to maximize electromagnetic enhancement.
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Akbar, Noreen Sher, O. Anwar Beg, and Z. H. Khan. "Magneto-nanofluid flow with heat transfer past a stretching surface for the new heat flux model using numerical approach." International Journal of Numerical Methods for Heat & Fluid Flow 27, no. 6 (June 5, 2017): 1215–30. http://dx.doi.org/10.1108/hff-03-2016-0125.
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Purpose Sheet processing of magnetic nanomaterials is emerging as a new branch of smart materials’ manufacturing. The efficient production of such materials combines many physical phenomena including magnetohydrodynamics (MHD), nanoscale, thermal and mass diffusion effects. To improve the understanding of complex inter-disciplinary transport phenomena in such systems, mathematical models provide a robust approach. Motivated by this, this study aims to develop a mathematical model for steady, laminar, MHD, incompressible nanofluid flow, heat and mass transfer from a stretching sheet. Design/methodology/approach This study developed a mathematical model for steady, laminar, MHD, incompressible nanofluid flow, heat and mass transfer from a stretching sheet. A uniform constant-strength magnetic field is applied transversely to the stretching flow plane. The Buongiorno nanofluid model is used to represent thermophoretic and Brownian motion effects. A non-Fourier (Cattaneo–Christov) model is used to simulate thermal conduction effects, of which the Fourier model is a special case when thermal relaxation effects are neglected. Findings The governing conservation equations are rendered dimensionless with suitable scaling transformations. The emerging nonlinear boundary value problem is solved with a fourth-order Runge–Kutta algorithm and also shooting quadrature. Validation is achieved with earlier non-magnetic and forced convection flow studies. The influence of key thermophysical parameters, e.g. Hartmann magnetic number, thermal Grashof number, thermal relaxation time parameter, Schmidt number, thermophoresis parameter, Prandtl number and Brownian motion number on velocity, skin friction, temperature, Nusselt number, Sherwood number and nanoparticle concentration distributions, is investigated. Originality/value A strong elevation in temperature accompanies an increase in Brownian motion parameter, whereas increasing magnetic parameter is found to reduce heat transfer rate at the wall (Nusselt number). Nanoparticle volume fraction is observed to be strongly suppressed with greater thermal Grashof number, Schmidt number and thermophoresis parameter, whereas it is elevated significantly with greater Brownian motion parameter. Higher temperatures are achieved with greater thermal relaxation time values, i.e. the non-Fourier model predicts greater values for temperature than the classical Fourier model.
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Makukula, Z. G., P. Sibanda, S. S. Motsa, and S. Shateyi. "On New Numerical Techniques for the MHD Flow Past a Shrinking Sheet with Heat and Mass Transfer in the Presence of a Chemical Reaction." Mathematical Problems in Engineering 2011 (2011): 1–19. http://dx.doi.org/10.1155/2011/489217.
Повний текст джерелаАнотація:
We use recent innovative solution techniques to investigate the problem of MHD viscous flow due to a shrinking sheet with a chemical reaction. A comparison is made of the convergence rates, ease of use, and expensiveness (the number of iterations required to give convergent results) of three seminumerical techniques in solving systems of nonlinear boundary value problems. The results were validated using a multistep, multimethod approach comprising the use of the shooting method, the Matlab bvp4c numerical routine, and with results in the literature.
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Nurul Amira Zainal, Kohilavani Naganthran, and Roslinda Nazar. "Unsteady MHD Rear Stagnation-Point Flow of a Hybrid Nanofluid with Heat Generation/Absorption Effect." Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 87, no. 1 (September 7, 2021): 41–51. http://dx.doi.org/10.37934/arfmts.87.1.4151.
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The study of unsteady flow is essential in various engineering systems, for instance, the periodic fluid motion and start-up process. Therefore, this numerical study focuses on examining the unsteady magnetohydrodynamics (MHD) rear stagnation-point flow in Al2O3-Cu/H2O hybrid nanofluid past a permeable stretching/shrinking surface with the impact of heat generation/absorption. By choosing a suitable similarity transformation, partial differential equations are transformed into a system of nonlinear ordinary differential equations and solved using the bvp4c function in the MATLAB package. The effects of the solution domain’s operating parameters are analysed, and dual solutions are observable as the sheet shrinks. It is found that the addition of the suction parameter escalates the heat transfer efficiency. Eventually, the existence of the unsteadiness parameter and the heat generation/absorption effect significantly encourage heat transfer deterioration.
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Bopape, Mokgadi F., Tim Van Geel, Abhishek Dutta, Bart Van der Bruggen, and Maurice Stephen Onyango. "Numerical Modelling Assisted Design of a Compact Ultrafiltration (UF) Flat Sheet Membrane Module." Membranes 11, no. 1 (January 14, 2021): 54. http://dx.doi.org/10.3390/membranes11010054.
Повний текст джерелаАнотація:
The increasing adoption of ultra-low pressure (ULP) membrane systems for drinking water treatment in small rural communities is currently hindered by a limited number of studies on module design. Detailed knowledge on both intrinsic membrane transport properties and fluid hydrodynamics within the module is essential in understanding ULP performance prediction, mass transfer analysis for scaling-up between lab-scale and industrial scale research. In comparison to hollow fiber membranes, flat sheet membranes present certain advantages such as simple manufacture, sheet replacement for cleaning, moderate packing density and low to moderate energy usage. In the present case study, a numerical model using computational fluid dynamics (CFD) of a novel custom flat sheet membrane module has been designed in 3D to predict fluid flow conditions. The permeate flux through the membrane decreased with an increase in spacer curviness from 2.81 L/m2h for no (0%) curviness to 2.73 L/m2h for full (100%) curviness. A parametric analysis on configuration variables was carried out to determine the optimum design variables and no significant influence of spacer inflow or outflow thickness on the fluid flow were observed. The numerical model provides the necessary information on the role of geometrical and operating parameters for fabricating a module prototype where access to technical expertise is limited.
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Majdi, Hasan Shakir, Mahmoud A. Mashkour, Laith Jaafer Habeeb, and Ahmad H. Sabry. "Enhancement of energy transfer efficiency for photovoltaic (PV) systems by cooling the panel surfaces." Eastern-European Journal of Enterprise Technologies 4, no. 8(112) (August 31, 2021): 83–89. http://dx.doi.org/10.15587/1729-4061.2021.238700.
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The thermal coefficient of a solar photovoltaic (PV) panel is a value that is provided with its specification sheet and tells us precisely the drop in panel performance with rising temperature. In desert climates, the PV panel temperatures are known to reach above 70 degrees centigrade. Exploring effective methods of increasing energy transfer efficiency is the issue that attracts researchers nowadays, which also contributes to reducing the cost of using solar photovoltaic (PV) systems with storage batteries. Temperature handling of solar PV modules is one of the techniques that improve the performance of such systems by cooling the bottom surface of the PV panels. This study initially reviews the effective methods of cooling the solar modules to select a proper, cost-effective, and easy to implement one. An active fan-based cooling method is considered in this research to make ventilation underneath the solar module. A portion of the output power at a prespecified high level of battery state-of-charge (SOC) is used to feed the fans. The developed comparator circuit is used to control the power ON/OFF of the fans. A Matlab-based simulation is employed to demonstrate the power rate improvements and that consumed by the fans. The results of simulations show that the presented approach can achieve significant improvements in the efficiency of PV systems that have storage batteries. The proposed method is demonstrated and evaluated for a 1.62 kW PV system. It is found from a simultaneous practical experiment on two identical PV panels of 180 W over a full day that the energy with the cooling system was 823.4 Wh, while that without cooling was 676 Wh. The adopted approach can play a role in enhancing energy sustainability.
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Scheiner, Steve. "New ideas from an old concept: the hydrogen bond." Biochemist 41, no. 4 (August 1, 2019): 6–9. http://dx.doi.org/10.1042/bio04104006.
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Ongoing studies of the hydrogen bond (HB), in which a hydrogen (H) atom acts as a bridge between a pair of chemical groups, continues to offer new ideas about this interaction that have applications to biochemical processes. The ability of a proton to transfer within a HB can be controlled by conformational changes that cause small alterations to the HB geometry. The CH group, widely prevalent in biological systems, participates in HBs and contributes to the structure and stability of commonly occurring protein secondary structures such as the β-sheet. The concept of the HB has been extended to systems where the bridging proton is replaced by any of a large variety of electronegative atoms, in the form of halogen, chalcogen, pnicogen and tetrel bonds, with no loss of strength.
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Prasad, P. Durga, S. V. K. Varma, C. S. K. Raju, Sabir Ali Shehzad, and M. A. Meraj. "3D flow of Carreau polymer fluid over variable thickness sheet in a suspension of microorganisms with Cattaneo-Christov heat flux." Revista Mexicana de Física 64, no. 5 (August 31, 2018): 519. http://dx.doi.org/10.31349/revmexfis.64.519.
Повний текст джерелаАнотація:
Numerical study of three dimensional Carreau liquid flow with heat and mass transport features over a variable thickness sheet filled with microorganisms is analyzed. We considered the non-uniform heat sink or source and multiple slip effects. The governing non-linear partially differential expressions are developed into ordinary differential systems by using variable transformations. These expressions are solved numerically by using Runge-Kutta fourth order method connected with shooting methodology. A Parametric study is implemented to demonstrate the effects of Hartmann number, Prandtl number, Weissenberg number, Peclet number, chemical reaction and heat sink/source parameters on liquid velocity, temperature and concentration profiles. The quantities of physical interest are described within the boundary layer. From this analysis, we found that the magnetic parameter decrease the local Sherwood and local Nusselt numbers for both and cases. The constraint of chemical reaction enhances the mass transfer rate and decelerates the density of motile mass transfer rate. The space dependent and temperature dependent heat source/sink suppress the local Nusselt number.
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Adnan Asghar, Teh Yuan Ying, and Khairy Zaimi. "Two-Dimensional Mixed Convection and Radiative Al2O3-Cu/H2O Hybrid Nanofluid Flow over a Vertical Exponentially Shrinking Sheet with Partial Slip Conditions." CFD Letters 14, no. 3 (April 1, 2022): 22–38. http://dx.doi.org/10.37934/cfdl.14.3.2238.
Повний текст джерелаАнотація:
Hybrid nanofluid is considered a modern and improvised form of nanofluid which usually used to enhance the performance of heat transfer in fluid flow systems. Previous studies found hybrid nanofluid offered a wide range of applications and this opened up numerous new opportunities to further explore the unknown behaviour of hybrid nanofluid under different body geometries and physical parameters. This paper numerically studied a two-dimensional mixed convection and radiative Al2O3-Cu/H2O hybrid nanofluid flow over a vertical exponentially shrinking sheet with partial slip conditions. The main objective is to investigate the effect of mixed convection and radiation on the velocity and temperature profiles, as well as the effect of suction on reduced skin friction and reduced heat transfer with respect to solid volume fraction of copper, velocity, and thermal slips. Exponential similarity variables transformed the governing system of partial differential equations into a system of ordinary differential equations which is solved via MATLAB’s bvp4c solver. Outcomes showed that the value of the reduced heat transfer upsurges in the first solution but declines in the second solution when the velocity slip rises. The reduced heat transfer decreases in both dual solutions when thermal slip is enhanced. As the intensity of thermal slip increases, the reduced skin friction rises in the first solution and decreases in the second. As the mixed convection parameter increases, no obvious variation is noticed in the temperature distribution within the first solution, but increasing trend is observed within the second solution. An increment in the temperature distribution also observed within the dual solutions as the thermal radiation parameter increases. In summary, findings from this study are particularly useful to understand various behaviour of Al2O3-Cu/H2O hybrid nanofluid under the influence of mixed convection, radiation, and partial slip conditions when it flows over a vertical exponential shrinking sheet.
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Alam, Aftab, Dil Nawaz Khan Marwat, and Azhar Ali. "Flow of nano-fluid over a sheet of variable thickness with non-uniform stretching (shrinking) and porous velocities." Advances in Mechanical Engineering 13, no. 4 (April 2021): 168781402110129. http://dx.doi.org/10.1177/16878140211012913.
Повний текст джерелаАнотація:
Nano-fluid flow is maintained over a non-uniform porous plate of variable thickness with non-uniform stretching (shrinking) velocity. In real engineering systems, the conduction resistance of sheets is necessarily important, whereas, in typical analysis very thin walls are undertaken. The surface thickness is ignored in the classical studies of flow, heat, and mass transfer problems. However, it the compulsory component in many physical problems, therefore, we thoroughly examined the perceptiveness of the wall thickness on the field variables and the transport of heat and nano-particle between solid surfaces and fluids. The phenomenon of variable wall thickness is extensively investigated with the combination of other boundary inputs. The variable stretching and shrinking velocities of the plate may have linear and non-linear forms and the sheet is uniformly heated whereas the nanoparticles are uniformly distributed over its surface. The diffusion of heat and nanoparticles in the fluid are governed using the boundary layer PDE’s, which satisfy certain BC’s. A set of unseen transformations is generated for solving the system of boundary value PDE’s. In view of these new variables, we obtained a system of boundary value ODE’s and it contains several dimensionless numbers (parameters). It is worthy noticeable that the problem describes and enhances the behavior of all field quantities in view of the governing parameters. All the field quantities, rates of heat and mass transfer are evaluated and effects all the parameters are seen on them and they are significantly changed with the variation of these dimensionless quantities. New results are presented in different graphs and tables and thoroughly examined. The Thermophoresis force enhances both the temperature and concentration profiles, however, the concentration distribution of nanoparticles is abruptly changed with a small variation in this force. The concentration profiles are bell-shaped on the right and behaves like a normal distribution. On the other hand, the addition of more nanoparticles into the base fluids increased (decreased) the temperature (concentration) profiles. Moreover, the two different attitudes of wall thickness are also examined on filed variables. The significant features and diversity of modeled equations are scrutinized and we recovered the previous problems of mass and heat transfer in Nano-fluid from a uniformly heated sheet of variable (uniform) thickness with variable (uniform) stretching/shrinking and injection/suction velocities. Moreover, two different numerical solutions of the modeled equations are found. These solutions are compared in a table and exactly matched with each other.
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Rehman, Aysha, Azad Hussain, and Sohail Nadeem. "Assisting and Opposing Stagnation Point Pseudoplastic Nano Liquid Flow towards a Flexible Riga Sheet: A Computational Approach." Mathematical Problems in Engineering 2021 (May 15, 2021): 1–14. http://dx.doi.org/10.1155/2021/6610332.
Повний текст джерелаАнотація:
Nanofluids are used as coolants in heat transport devices like heat exchangers, radiators, and electronic cooling systems (like a flat plate) because of their improved thermal properties. The preeminent perspective of this study is to highlight the influence of combined convection on heat transfer and pseudoplastic non-Newtonian nanofluid flow towards an extendable Riga surface. Buongiorno model is incorporated in the present study to tackle a diverse range of Reynolds numbers and to analyze the behavior of the pseudoplastic nanofluid flow. Nanofluid features are scrutinized through Brownian motion and thermophoresis diffusion. By the use of the boundary layer principle, the compact form of flow equations is transformed into component forms. The modeled system is numerically simulated. The effects of various physical parameters on skin friction, mass transfer, and thermal energy are numerically computed. Fluctuations of velocity increased when modified Hartmann number and mixed convection parameter are boosted, where it collapses for Weissenberg number and width parameter. It can be revealed that the temperature curve gets down if modified Hartmann number, mixed convection, and buoyancy ratio parameters upgrade. Concentration patterns diminish when there is an incline in width parameter and Lewis number; on the other hand, it went upward for Brownian motion parameter, modified Hartmann, and Prandtl number.
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Golden, Matthew, John LoVerde, Wayland Dong, Samantha Rawlings, and Richard Silva. "Prediction of one-third-octave band sound and vibration levels from heavy-hard impacts." INTER-NOISE and NOISE-CON Congress and Conference Proceedings 263, no. 2 (August 1, 2021): 4692–700. http://dx.doi.org/10.3397/in-2021-2796.
Повний текст джерелаАнотація:
Noise and vibration due to dropping hard heavy weights is a common source of disturbance and complaint in residential, commercial, and mixed-use building types. The authors and others have worked on developing methodologies to accurately, repeatably, and conveniently measure heavy-hard impact noise and vibration in the field based on a standard weight drop. Separately, systems have been created to measure the force being injected into a building from heavy-hard impact. It has been shown that this force data can be used to successfully predict vibration levels in buildings if in-situ transfer functions are known. In this paper, the authors will present a novel one-third-octave band prediction method using the laboratory force data and a reference impact sheet to predict field performance without the need to measure transfer function. The method is evaluated using both noise and vibration measurements.
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Sivaraj, Chinnasamy, Vladimir E. Gubin, Aleksander S. Matveev, and Mikhail A. Sheremet. "Impacts of Uniform Magnetic Field and Internal Heated Vertical Plate on Ferrofluid Free Convection and Entropy Generation in a Square Chamber." Entropy 23, no. 6 (June 3, 2021): 709. http://dx.doi.org/10.3390/e23060709.
Повний текст джерелаАнотація:
The heat transfer enhancement and fluid flow control in engineering systems can be achieved by addition of ferric oxide nanoparticles of small concentration under magnetic impact. To increase the technical system life cycle, the entropy generation minimization technique can be employed. The present research deals with numerical simulation of magnetohydrodynamic thermal convection and entropy production in a ferrofluid chamber under the impact of an internal vertical hot sheet. The formulated governing equations have been worked out by the in-house program based on the finite volume technique. Influence of the Hartmann number, Lorentz force tilted angle, nanoadditives concentration, dimensionless temperature difference, and non-uniform heating parameter on circulation structures, temperature patterns, and entropy production has been scrutinized. It has been revealed that a transition from the isothermal plate to the non-uniformly warmed sheet illustrates a rise of the average entropy generation rate, while the average Nusselt number can be decreased weakly. A diminution of the mean entropy production strength can be achieved by an optimal selection of the Lorentz force tilted angle.
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Vishalakshi, Angadi Basettappa, Thippaiah Maranna, Ulavathi Shettar Mahabaleshwar, and David Laroze. "An Effect of MHD on Non-Newtonian Fluid Flow over a Porous Stretching/Shrinking Sheet with Heat Transfer." Applied Sciences 12, no. 10 (May 13, 2022): 4937. http://dx.doi.org/10.3390/app12104937.
Повний текст джерелаАнотація:
The current article explains the 3-D MHD fluid flow under the impact of a magnetic field with an inclined angle. The porous sheet is embedded in the flow of a fluid to yield the better results of the problem. The governing PDEs are mapped using various transformations to convert in the form of ODEs. The yielded ODEs momentum equation is examined analytically to derive the mass transpiration and then it is used in the energy equation and solved exactly by using various controlling parameters. In the case of multiple solutions, the closed-form exact solutions of highly non-linear differential equations of the flow are presented as viscoelastic fluid, which is classified as two classes, namely the second order liquid and Walters’ liquid B fluid. The results can be obtained by using graphical arrangements. The current work is utilized in many real-life applications, such as automotive cooling systems, microelectronics, heat exchangers, and so on. At the end of the analysis, we concluded that velocity and mass transpiration was more for Chandrasekhar’s number for both the stretching and shrinking case.
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Khan, N. A., and F. Naz. "Three dimensional flow and mass transfer analysis of a second grade fluid in a porous channel with a lower stretching wall." International Journal of Applied Mechanics and Engineering 21, no. 2 (May 1, 2016): 359–76. http://dx.doi.org/10.1515/ijame-2016-0022.
Повний текст джерелаАнотація:
AbstractThis investigation analyses a three dimensional flow and mass transfer of a second grade fluid over a porous stretching wall in the presence of suction or injection. The equations governing the flow are attained in terms of partial differential equations. A similarity transformation has been utilized for the transformation of partial differential equations into the ordinary differential equations. The solutions of the nonlinear systems are given by the homotopy analysis method (HAM). A comparative study with the previous results of a viscous fluid has been made. The convergence of the series solution has also been considered explicitly. The influence of admissible parameters on the flows is delineated through graphs and appropriate results are presented. In addition, it is found that instantaneous suction and injection reduce viscous drag on the stretching sheet. It is also shown that suction or injection of a fluid through the surface is an example of mass transfer and it can change the flow field.
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Haroun, Nageeb A. H., Sabyasachi Mondal, and Precious Sibanda. "Hydromagnetic Nanofluids Flow through a Porous Medium with Thermal Radiation, Chemical Reaction and Viscous Dissipation using the Spectral Relaxation Method." International Journal of Computational Methods 16, no. 06 (May 27, 2019): 1840020. http://dx.doi.org/10.1142/s0219876218400200.
Повний текст джерелаАнотація:
We investigate the convective heat and mass transfer in a magnetohydrodynamic nanofluid flow through a porous medium over a stretching sheet subject to heat generation, thermal radiation, viscous dissipation and chemical reaction effects. We have assumed that the nanoparticle volume fraction at the wall may be actively controlled. Two types of nanofluids, namely Cu-water and Al2O3-water are studied. The physical problem is modeled using systems of nonlinear differential equations which have been solved numerically using the spectral relaxation method. Comparing the results with those previously published results in the literature shows excellent agreement. The impact of porosity, heat generation, thermal radiation, magnetic field, viscous dissipation and chemical reaction on the flow field is evaluated and explained.
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Zeb, Hussan, Hafiz Abdul Wahab, Umar Khan, Amnah S. Al Juhani, Mulugeta Andualem, and Ilyas Khan. "The Velocity Slip Boundary Condition Effects on Non-Newtonian Ferrofluid over a Stretching Sheet." Mathematical Problems in Engineering 2022 (May 17, 2022): 1–20. http://dx.doi.org/10.1155/2022/1243333.
Повний текст джерелаАнотація:
In this work, radioactive heat transfer analysis in non-Newtonian Ferrofluid over a stretchable sheet is considered. Furthermore, the effects of Arrhenius activation energy, magnetic dipole, velocity slip, and mass convective boundary condition are taken into account. The governing model is transformed into coupled ordinary equations (ODEs) via a similarity transformation. The solution of these resulting ODEs systems are computed by Runge–Kutta method (RK-45). The influence of beneficial physical parameters on momentum, pressure, energy, and concentration profiles are presented. The major finding of this study is the variation of the velocity field is reduced for the higher values of velocity slip parameters A 1 and β 2 and fluid material parameter H . The temperature field increases for higher values of Rd and decreases for Pr . Here we concluded that, the increasing or decreasing of the concentration, temperature, and velocity field for various physical parameters can be seen in the result and discussion section in detail. The physical quantities such as skin friction, Nusselt, and Sherwood numbers are examined.
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Jarosch, A. H., and M. T. Gudmundsson. "A numerical model for meltwater channel evolution in glaciers." Cryosphere 6, no. 2 (April 16, 2012): 493–503. http://dx.doi.org/10.5194/tc-6-493-2012.
Повний текст джерелаАнотація:
Abstract. Meltwater channels form an integral part of the hydrological system of a glacier. Better understanding of how meltwater channels develop and evolve is required to fully comprehend supraglacial and englacial meltwater drainage. Incision of supraglacial stream channels and subsequent roof closure by ice deformation has been proposed in recent literature as a possible englacial conduit formation process. Field evidence for supraglacial stream incision has been found in Svalbard and Nepal. In Iceland, where volcanic activity provides meltwater with temperatures above 0 °C, rapid enlargement of supraglacial channels has been observed. Supraglacial channels provide meltwater through englacial passages to the subglacial hydrological systems of big ice sheets, which in turn affects ice sheet motion and their contribution to eustatic sea level change. By coupling, for the first time, a numerical ice dynamic model to a hydraulic model which includes heat transfer, we investigate the evolution of meltwater channels and their incision behaviour. We present results for different, constant meltwater fluxes, different channel slopes, different meltwater temperatures, different melt rate distributions in the channel as well as temporal variations in meltwater flux. The key parameters governing incision rate and depth are channel slope, meltwater temperature loss to the ice and meltwater flux. Channel width and geometry are controlled by melt rate distribution along the channel wall. Calculated Nusselt numbers suggest that turbulent mixing is the main heat transfer mechanism in the meltwater channels studied.
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Helwig, Martin, Steve Zimmer, Peter Lucas, Anja Winkler, and Niels Modler. "Multiphysics Investigation of an UltrathinVehicular Wireless Power Transfer Module for Electric Vehicles." Sustainability 13, no. 17 (August 31, 2021): 9785. http://dx.doi.org/10.3390/su13179785.
Повний текст джерелаАнотація:
The functional and spatial integration of a wireless power transfer system (WPTS) into electric vehicles is a challenging task, due to complex multiphysical interactions and strict constraints such as installation space limitations or shielding requirements. This paper presents an electromagnetic–thermal investigation of a novel design approach for an ultrathin onboard receiver unit for a WPTS, comprising the spatial and functional integration of the receiver coil, ferromagnetic sheet and metal mesh wire into a vehicular underbody cover. To supplement the complex design process, two-way coupled electromagnetic–thermal simulation models were developed. This included the systematic and consecutive modelling, as well as experimental validation of the temperature- and frequency-dependent material properties at the component, module and system level. The proposed integral design combined with external power electronics resulted in a module height of only 15mm. The module achieved a power of up to 7.2 kW at a transmission frequency of f0=85kHz with a maximum efficiency of 92% over a transmission distance of 110mm to 160mm. The proposed simulations showed very good consistency with the experimental validation on all levels. Thus, the performed studies provide a significant contribution to coupled electromagnetic and thermal design wireless power transfer systems.
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Motsa, S. S., P. Sibanda, J. M. Ngnotchouye, and G. T. Marewo. "A Spectral Relaxation Approach for Unsteady Boundary-Layer Flow and Heat Transfer of a Nanofluid over a Permeable Stretching/Shrinking Sheet." Advances in Mathematical Physics 2014 (2014): 1–10. http://dx.doi.org/10.1155/2014/564942.
Повний текст джерелаАнотація:
This paper introduces two novel numerical algorithms for the efficient solution of coupled systems of nonlinear boundary value problems. The methods are benchmarked against existing methods by finding dual solutions of the highly nonlinear system of equations that model the flow of a viscoelastic liquid of Oldroyd-B type in a channel of infinite extent. The methods discussed here are the spectral relaxation method and spectral quasi-linearisation method. To verify the accuracy and efficiency of the proposed methods a comparative evaluation of the performance of the methods against established numerical techniques is given.