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Cloud-Based Optimal Control of Individual Borehole Heat Exchangers in a Geothermal Field

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Journal of Thermal Science 2022年第5期31卷 1253-1265页

作者： STOFFEL Phillip KÜMPEL alexander MÜLLER Dirk RWTH Aachen University E.ON Energy Research CenterInstitute for Energy Efficient Buildings and Indoor Climate52074 AachenGermany

Integrating renewable energy sources is a crucial component in reducing CO_(2) emissions in the building sector. In particular, shallow geothermal energy is expected to play a significant role in the regenerative energy supply of buildings. An effective control strategy for the geothermal field is crucial to reduce the overall energy consumption. This paper analyzes the benefits of controlling an existing field’s individual borehole heat exchangers(BHE) using nonlinear model predictive control(NMPC) and moving horizon estimation. The considered geothermal field consists of 41 BHEs and is used for heating and cooling. Each BHE is equipped with temperature sensors for in-and outflow and has individually controllable valves, while a central hydraulic pump feeds all BHEs. The sensor measurements are accessed through a cloud platform, enabling also set point writing for the pump speed and the valve positions. To control the BHEs individually, we propose a two-stage process. In the calibration stage, a moving horizon estimator estimates the actual borehole and ground temperatures for each BHE. In the second stage, first, a nonlinear model predictive controller optimizes the number of active BHEs necessary to meet the buildings’ energy demand. With the estimated ground temperatures as a basis, it is determined which BHEs shall be(de)-activated. The active BHEs are fed with a fixed volume flow of 24 L/min to ensure turbulent heat transfer. To reduce the power usage of the pumps, an optimal control problem based on a simple hydraulic model of the geothermal field is used. The methodology is analyzed through simulations first and then validated experimentally. The results show that half or more of the BHEs could be deactivated most of the time, leading to 67% savings in electricity consumption by the hydraulic pump. The experimental validation confirms the high energy saving potential of the proposed methodology, reducing the consumption of electrical energy by 71%. Additiona

关键词： geothermal energy moving horizon estimation model predictive control operation optimization optimal control

Power absorption,plasma parameters and wave structure in inductive RF plasma source with low value external magnetic field

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Plasma Science and Technology 2020年第11期22卷 60-73页

作者： Elena KRALKINA Konstantin VAVILIN Ilya ZADIRIEV alexander NIKONOV Physical Electronics Department Faculty of PhysicsLomonosov Moscow State UniversityMoscow 119991Russia

The efficiency of radio-frequency(RF)power absorption,RF magnetic field structure and plasma parameters were measured in cylindrical inductive RF plasma sources 20 cm in diameter and 22,32,53 cm in length with a low value external magnetic *** experiments were carried out in argon at pressures of 13-140 m *** RF power supply changed from 200 W to 800 *** spiral antenna was used for sustaining the *** was shown that efficiency of RF power absorption depended nonlinearly on the external magnetic field *** maximal values of the RF power absorption efficiency,the axial distributions of longitudinal Bzand azimuthal Bφcomponents of RF magnetic field manifested the formation of the partially standing wave with a half wavelength close to 8 *** the same conditions,the axial dependence of the radial RF magnetic field component Brdiffered *** was concluded that the Bz and Bφamplitudes were largely determined by the RF field of Trivelpiece-Gould wave,while Br amplitude represented the radial RF field of the helicon wave.

关键词： radio-frequency plasma helicon Trivelpiece-Gould waves inductive discharge

Optical in vivo and ex vivo imaging of glioma cells migration via the cerebral vessels:Prospective clinical application of the beta2-adrenoreceptors blockade for glioma treatment

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Journal of Innovative Optical Health Sciences 2018年第4期11卷 98-107页

作者： Olga Pavlova alexander Shirokov alexander Fomin Nikita Navolokin Andrey Terskov alexander Khorovodov Anton Namykin Alexey Pavlov Valery Tuchin Oxana Semyachkina-Glushkovskaya Interdisciplinary Center of Critical Technologies in Medicine Saratov State University 83 Astrakhanskaya Str.Saratov 410012Russia Institute of Biochemistry and Physiology of Plants and Microorganisms Russian Academy of Sciences13 Entuziastov Ave.Saratov 410049Russia Saratov State Medical University 112 Bolshaya Kazachia Str. Saratov 410012Russia Department of Optics and Biophotonics Saratov State University 83 Astrakhanskaya Str.Saratov 410012Russia Yuri Gagarin State Technical University of Saratov 77 Politechnicheskaya Str. Saratov 410054Russia Laboratory of Laser Diagnostics of Technical and Living Systems Institute of Precision Mechanics and Control of RAS 24 Rabochaya Str.Saratov 410028Russia Laboratory of Biophotonics Tomsk State University 36 Lenin's Ave.Tomsk 634050Russia

Malignant gliomas are highly invasive tumors that 1use the cerebral vessels for invasion due to high vascular fragility of the blood--brain barrier(BBB).On one hand,glioma is characterized by the BBB disruption,on the other hand,drug brain delivery via the BBB is a big challenge in glioma *** limited information about vascular changes associated with glioma growth is a reason of slow progress in prevention of glioma ***,we present in vrivo and er vrivo study of the BBB disruption and glioma cells(GCs)migration in rats using fuorescence and confocal *** uncovered a local breach in the BBB in the main tumor mass but not within the border of normal and malignant cells,where the BBB was impermeable for high weight *** migr ation of GCs were observed via the cerebral vessels with the intact BBB that was associated with macrophages *** mechanisms underlying glioma progression remain umknown but there is an evidence that the sympathetic nervous system(SNS)via activation of vascular beta2-adrenoreceptors(B2-ADRs)can play an important role in tumor *** results clearly show an increase in the expression of vascular B2-ADRs and production of the beta arrestin-1-co-factor of B2-ADRs signaling pathway in rats with *** blockade of B2-ADRs reduces the BBB disruption,macrophages infiltration,GCs migration and increases survival *** data suggest that the blockade of B2-ADRs may be a novel adjuvant therapeutic strategy to reduce glioma progression and prevent metastasis。

关键词： Glioma macrophages blood-brain barrier beta-2 adrenoreceptors bet a arrestin-1

Processing Compressed Expanded Natural Graphite for Phase Change Material Composites

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Journal of Thermal Science 2023年第3期32卷 1213-1226页

作者： alexander BULK Adewale ODUKOMAIYA Ethan SIMMONS Jason WOODS National Renewable Energy Laboratory 15013 Denver West ParkwayGoldenCO 80401USA

Phase change materials(PCMs)are used in various thermal energy storage applications but are limited by their low thermal *** method to increase conductivity involves impregnating organic PCMs into highly porous conductive matrix *** these materials,compressed expanded natural graphite(CENG)matrices have received the most *** this attention,the effect that CENG processing has on PCM saturation and overall matrix thermal conductivity has not been fully ***,the effect of the heat treatment process used to expand intercalated graphite flakes is evaluated *** heat treatment temperatures yielded higher saturation rates and overall saturation at similar matrix *** example,increasing temperature from 300℃to 700℃resulted in approximately 60%-70%increase in pore saturation after 100 minutes of *** exposure time to heat treatment had less of an effect on PCM *** exposure time had negligible effect above 30 min and above 500℃heating ***,because the expanded graphite was found to oxidize around 700℃,the use of longer exposure time in manufacturing applications can be beneficial if a shortened impregnation time is *** treatment conditions did not impact thermal *** composite latent heat of fusion was also reduced approximately proportionally to the PCM mass fraction.A local maximum in axial thermal conductivity was observed at around 83%porosity,which is similar to previous *** observed conductivity at this maximum was a factor of 81 times greater than the conductivity of the PCM.

关键词： phase change materials thermal energy storage compressed expanded natural graphite thermal conductivity enhancement porous material sorptivity composite matrix

MicroRNAs as non-invasive diagnostic biomarkers for gastric cancer:Current insights and future perspectives

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World Journal of Gastroenterology 2018年第30期24卷 3313-3329页

作者： alexander Link Juozas Kupcinskas Department of Gastroenterology Hepatology and Infectious DiseasesOtto-von-Guericke University Institute for Digestive Research and Department of Gastroenterology Lithuanian University of Health Sciences

Non-invasive diagnostic biomarkers may contribute to an early identification of gastric cancer(GC) and improve the clinical ***,no sensitive and specific screening biomarkers are available yet and the currently available approaches are limited by the nature of the *** is a heterogenic disease with various distinct genetic and epigenetic events that occur during the multifactorial cascade of *** RNAs(mi RNAs) are commonly deregulated in gastric mucosa during the Helicobacter pylori infection and in stepwise manner from chronic gastritis,through preneoplastic conditions such as atrophic gastritis and intestinal metaplasia,to early dysplasia and invasive *** of mi RNAs in blood in 2008 led to a great interest on mi RNA-based diagnostic,prognostic biomarkers in *** this review,we provide the most recent systematic review on the existing studies related to mi RNAs as diagnostic biomarkers for ***,we systematically evaluate 75 studies related to differential expression of circulating mi RNAs in GC patients and provide novel view on various heterogenic aspects of the existing data and summarize the methodological ***,we highlight several important aspects crucial to improve the future translational and clinical research in the field.

关键词： microRNA biomarkers screening stomach gastric cancer systematic review blood serum plasma

Quasi-Lagrangian Acceleration of Eulerian Methods

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Communications in Computational Physics 2009年第9期6卷 743-757页

作者： Igor Kliakhandler alexander Kurganov Department of Mathematical Sciences Michigan Technological UniversityHoughtonMI 49931USA Mathematics Department Tulane UniversityNew OrleansLA 70118USA

We present a simple and efficient strategy for the acceleration of explicit Eulerian methods for multidimensional hyperbolic systems of conservation *** strategy is based on the Galilean invariance of dynamic equations and optimization of the reference frame,in which the equations are numerically *** optimal reference frame moves(locally in time)with the average characteristic speed of the system,and,in this sense,the resulting method is *** leads to the acceleration of the numerical computations thanks to the optimal CFL condition and automatic adjustment of the computational domain to the evolving part of the *** show that our quasi-Lagrangian acceleration procedure may also reduce the numerical dissipation of the underlying Eulerian *** leads to a significantly enhanced resolution,especially in the supersonic *** demonstrate a great potential of the proposed method on a number of numerical examples.

关键词： Eulerian methods quasi-Lagrangian method finite volume methods Galilean invariance

On the Analytical Models of Protoplanetary Formation in Extrasolar Systems

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Space(Science & Technology) 2022年第1期2022卷 422-440页

作者： alexander M.Krot Laboratory of Self-Organization System Modeling United Institute of Informatics ProblemsNational Academy of Sciences of Belarus6Surganov Str.220012 MinskBelarus

In this work,we consider a statistical theory for a cosmogonical body formation(so-called spheroidal body)to develop the analytical models of protoplanetary formation in extrasolar *** the framework of this theory,the models and evolution equations of the statistical mechanics have been proposed,while the well-known problem of gravitational condensation of infinite distributed cosmic substances has been *** paper derives the general equation of distribution of the specific angular momentum of forming protoplanets since the specific angular momentums(for particles or planetesimals)are averaged during a conglomeration process(under a planetary embryo formation).As a result,a new law for planetary distances(which generalizes Schmidt’s law)is derived *** paper develops also an alternative thermal emission of particles model of the formation of protoplanets in extrasolar *** the framework of this model,the equation for the thermal distribution function of the specific angular momentums of particles moving in elliptical orbits in the gravitational field is *** to this thermal escape model,only 0.8%of the total number of particles in the solar system composing the protoplanetary cloud has angular momentum 15.6 times higher than the angular momentum of the remaining 99%of *** conclusion agrees completely with the known fact of a nonuniform distribution of the angular momentums in our solar system noted by ter *** pointed out here,the exponential laws of planetary distances occur in some extrasolar systems.

关键词： momentum angular equation

Cross Correlators and Galilean Invariance in Fluctuating Ideal Gas Lattice Boltzmann Simulations

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Communications in Computational Physics 2011年第5期9卷 1315-1322页

作者： Goetz Kaehler alexander Wagner Department of Physics North Dakota State UniversityFargoND 58108USA

We analyze the Lattice Boltzmann method for the simulation of fluctuating hydrodynamics by Adhikari et al.[***.,71(2005),473-479]and find that it shows excellent agreement with theory even for small wavelengths as long as a stationary system is *** is in contrast to other finite difference and older lattice Boltzmann implementations that show convergence only in the limit of large *** particular cross correlators vanish to less than 0.5%.For larger mean velocities,however,Galilean invariance violations manifest themselves.

关键词： Lattice Boltzmann fluctuations Galilean invariance

Impact of Caudal Fin Shape on Thrust Production of a Thunniform Swimmer

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Journal of Bionic Engineering 2020年第2期17卷 254-269页

作者： alexander Matta Hodjat Pendar Francine Battaglia Javid Bayandor CRashworthiness for Aerospace Structures and Hybrids(CRASH)Lab Department of Mechanical and Aerospace EngineeringUniversity at BuffaloThe State University of New YorkBuffalo 14260USA Department of Biomedical Engineering and Mechanics Virginia Polytechnic Institute and State UniversityBlacksburg 24061USA Computational Research for Energy Systems and Transport(CREST)Lab Department of Mechanical and Aerospace EngineeringUniversity at BuffaloThe State University of New YorkBuffalo 14260USA

Tuna,known for high endurance cruising,have already inspired several underwater robots and swimming *** study uses a biomimetic robotic tuna to investigate how different caudal fin planform geometries affect the thrust production and flow structures during Body and/or Caudal Fin(BCF)*** robot was tethered to a circulating water tunnel,and swimming was simulated by moving water at a constant speed relative to the stationary *** differently shaped caudal fins were tested,one rectangular,one elliptical,and one ***,aspect ratio,and rigidity were kept constant between the three fins to ensure that the effect of caudal fin shape could be *** fins were tested at three freestream velocities and four Strouhal numbers(St)so that comparisons between the fins could be made for a variety of swimming *** swept fin,which is the tested caudal fin most similar to one found on a fusiform swimmer,had the greatest thrust potential at high St,followed by the elliptical *** rectangular fin generally produced the least *** was shown that in addition to producing the most thrust,the swept fin also best stabilized the leading edge vortex that developed during the second half of the stroke.

关键词： thunniform locomotion vortex formation caudal fin BCF swimming