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Friction 2024年第4期12卷 812-822页

作者： michałWASILCZUK michałWODTKE Faculty of Mechanical Engineering and Ship Technology Gdańsk University of TechnologyGdańsk 80-233Poland

In hydrodynamic bearings traditional bearing alloys:Babbitts and bronzes are most frequently *** sliding layers are sometimes applied as a valuable *** diamond-like carbon(DLC)coatings,which are also considered for certain applications may show some advantages,as *** material selection is of secondary importance in a full film lubrication regime it becomes important in mixed friction conditions,which is crucial for bearings with frequent starts and *** research aimed at studying the performance of fluid film bearings in the specific operating regime,including the transition to mixed friction,is described in the *** tests were carried out on four tilting pad bearings of different material compositions:Steel/bronze,DLC/steel,steel/polyether ether ketone(PEek),and steel/*** tests comprised stopping under load and reproduction of the Stribeck curve by decreasing rotational speed to very low values,and observing the changes of friction force during the transition to mixed friction *** of the transition conditions and other results showed clear differences between the tested bearings,illustrating the feasibility of less popular material compositions for bearings operating in specific *** specifically,the DLC/steel bearing was demonstrating superior performance,*** friction,transition to mixed friction occurring at higher load,and more stable performance at start-stop regime over the other tested bearings.

关键词： tilting pad thrust bearing experimental research start-stop regime polyether ether ketone(PEek) diamond-like carbon(DLC)coating metallic bearing alloys

Effect of presence of lifting pocket on the THD performance of a large tilting-pad thrust bearing

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Friction 2015年第4期3卷 266-274页

作者： Michel FILLON michałWODTKE michałWASILCZUK Institut Pprime CNRS-Universitéde Poitiers-ISAE-ENSMADépartement Génie Mécanique et Systèmes ComplexesBP 30169SP2MI86962 Futuroscope Chasseneuil CedexFrance Faculty of Mechanical Engineering Gdansk University of TechnologyGdanskPoland

Hydrostatic assistance is a commonly used method to improve limited load carrying ability of tilting-pad thrust bearings during transient states of operation of vertical shaft *** of special hydraulic equipment(as pumps,valves,etc.),it also requires manufacturing of special recesses/pockets at pad sliding surfaces,into which oil is injected under high *** allows to lift the rotor before start-up of the machine and form a hydrostatic film between pads and *** is a quite wide variety of geometry of recesses(shape,depth,and size)met in practical large bearing *** presence of a hydrostatic pocket(usually located in the sliding surface above the pivot area,where thin film,high oil pressure and temperature are observed)affects bearing performance under hydrodynamic *** theoretical researches,there is an almost common practice not to include hydrostatic recess in thermohydrodynamic(THD)or thermoelastohydrodynamic(TEHD)*** is probably due to the problems with obtaining solution for oil film geometry with pocket,the order of magnitude of the pocket depths being larger than gap *** this paper,an attempt was taken to study the effect of lifting pocket on THD performance of a large tilting-pad thrust bearing of Itaipu power *** performance was evaluated including recess shape for several cases of its *** results show that hydrostatic recess changes calculated bearing properties quite significantly,especially in vicinity of the pocket.

关键词： lifting pocket tilting-pad thrust bearing THD regime numerical simulations

Evaluating the impact of thermostat control strategies on the energy flexibility of residential buildings for space heating

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Building Simulation 2021年第5期14卷 1439-1452页

作者： Kun Zhang michaël Kummert Department of Mechanical Engineering Polytechnique MontrealMontrealCanada

Buildings can be operated in an energy-flexible manner while respecting occupant thermal *** energy flexibility of building operations,both in time and quantity,can be harnessed by the electrical grid for load *** the context of smart grid and intelligent buildings,the concept of energy flexibility in buildings broadens the existing demand management thinking from the top-down one-way control to two-way *** paper,extending studies on thermostat controls of heating and air conditioning systems for demand response,evaluates the impact of different control schemes on the energy flexibility of residential *** control strategies,Model Predictive Control(MPC)and Rule-Based Control(RBC),are investigated for a space heating system using co-simulation *** indicators are introduced and adapted from the literature to assess the control performances of the *** results show that different flexibility indicators favour different control strategies in this case *** demand response events of four hours,the MPC strategy presents two to three times of flexible energy than that of *** also delivers 20%more of maximum power reduction during the events against *** RBC strategy,on the other hand,is twice of MPC for flexible energy *** evaluation work can be beneficial to guide the control system design of new buildings or control retrofits of existing buildings that consider better grid-building interactions for the future.

关键词： energy flexibility MPC grid-building interaction demand response

Occupational risk assessment based on employees’ knowledge and awareness of hazards in mining

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International Journal of Coal Science & Technology 2022年第5期9卷 113-123页

作者： michał Patyk Dagmara Nowak‑Senderowska Department of Mining Engineering and Work Safety Faculty of Civil Engineering and Resource ManagementAGH University of Science and TechnologyAl.Mickiewicza 3030-059 CracowPoland

Analyses and assessments of hazards occurring in work processes are carried out by teams,in which there is usually one representative of the personnel,as the embodiment of the active participation of employees in the assessment of occupational *** is why the article presents research on all employees’knowledge and awareness about risks in their work *** research was carried out in the form of an employee survey in one of the open-pit mines,at workstations dealing with the loading and transporting of excavated *** survey included a list of 40 hazards divided into four groups:(1)hazards related to machines and equipment used,(2)hazards related to exposure,(3)hazards with an impact extending beyond the workstation and(4)hazards of an ergonomic nuisance nature,where employees were required to indicate which hazards apply to their workplaces and determine their level of signifcance,probability of occurrence and the scale of possible *** this way,a hierarchical identifcation of threats occurring at the analyzed workplaces was made,and the obtained results were used to determine the amount of occupational risk both for specifc workstations and for the whole technological *** measures of the magnitude of occupational risk obtained using the proposed method have showed that,according to the respondents,greatest risks at the workstation are associated with moving machines and vehicles and with mobile *** important risks,which were often mentioned by employees,were those directly related to their health,i.e.,related to ergonomic nuisance and *** resulting from geological and mining conditions,considered typical for mining,were important for the surveyed miners but they were not the most important owing to proper prevention,good organization of work and high safety culture The active involvement of the crew in the process of assessing occupational hazards allowed to identify the signifcance of each hazard,in t

关键词： Hazards in mining Occupational risk assessment Employee survey Open-pit mining

Introducing a New Tool for Studying Unstable Systems

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International Journal of Automation and computing 2014年第6期11卷 580-587页

作者： Frantiek Gazdo Tomas Bata University in Zlín Faculty of Applied Informatics nam.T.G.Masaryka 5555760 01 Zlin Czech Republic

This paper presents the starting project of a web site focussed on unstable systems. It is a web-based database in a bilingual version(English/Czech), which can be used as an information database for models of unstable processes. The web site contains the mathematical models of such systems, including their simulation files together with basic information about the stability of dynamic systems. The paper outlines the motivation for the development of this database, presents its basic structure, and discusses several models from the site. The areas of prospective usage are also suggested together with the possible directions of further development of this project. The contribution ends with a case study using the database for control system analysis and design of the Amira inverted pendulum. The systematic polynomial approach is fruitfully utilised for the task together with some useful tools from the robust control theory.

关键词： Unstable systems stability modelling simulation database robust control polynomial approach

Calibration and uniqueness analysis of microparameters for DEM cohesive granular material

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International Journal of Mining Science and Technology 2022年第1期32卷 121-136页

作者： Songtao Ji Jurij Karlovšek School of Civil Engineering The University of QueenslandBrisbane 4067Australia

The differential evolution(DE)algorithm was deployed to calibrate microparameters of the DEM cohesive granular material.4 macroparameters,namely,uniaxial compressive strength,direct tensile strength,Young’s modulus and Poisson’s ratio,can be calibrated to high *** best calibration accuracy could reach the sum of relative errors RE_(sum)<0.1%.Most calibrations can be achieved with RE_(sum)<5%within hours or RE_(sum)<1%within 2 *** on the calibrated results,microparameters uniqueness analysis was carried out to reveal the correlation between microparameters and the macroscopic mechanical behaviour of material:(1)microparameters effective modulus,tensile strength and normal-to-shear stiffness ratio control the elastic behaviour and stable crack growth,(2)microparameters cohesion and friction angles present a negative linear correlation that controls the axial strain and lateral strain prior to the peak stress,and(3)microparameters friction coefficient controls shear crack friction and slip mainly refers to the unstable crack *** of more macroparameters to regulate the material mechanical behaviour that is dominated by shear crack and slip motion is highlighted for future *** DE calibration method is expected to serve as an alternative method to calibrate the DEM cohesive granular material to its peak strength.

关键词： Discrete element method(DEM) Particle flow code(PFC) Differential evolution(DE) Parameter calibration Uniqueness analysis Post-peak behaviour

Peak systolic velocity Doppler of middle cerebral artery in small for gestational age （SGA） fetus

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Frontiers in Biology 2018年第5期13卷 389-393页

作者： Kobra Shojaei hora Motamed Mojgan Barati Associate Professor. Department of Obstetrics and Gynecology Faculty of Medicine Ahvaz Jundishapur University of Medical Sciences Ahvaz I. R Iran Resident Department of Obstetrics and Gynecology Student Research Committee Ahvaz Jundishapur University of Medical Sciences Ahvaz L R Iran

BACKGROUND： Small for gestational age （SGA） has high frequency which increases the risk of long-term adverse outcomes. Thus the aim of this study was to evaluate peak systolic velocity Doppler of middle cerebral artery （MCA） in SGA fetus in order to find appropriate method to diagnosis SGA sooner. MATERIALS and METHODS： This prospective longitudinal study was conducted on 90 pregnant women with a diagnosis of SGA fetus and 90 pregnant women with normal fetus. Then MCA and umbilical artery assessment were performed for all subjects and compared between two groups. RESULTS： Doppler assessment showed that umbilical artery PI was significantly higher in SGA group as compared to normal group （1.114-0.37 vs 0.984-0.18, P = 0.003）, while MCA PI was significantly lower in SGA group （1.77±0.44 vs 1.92±0.47, P = 0.028）. On the other hand, PSV did not differ between the groups （P = 0.592）. Moreover, we found that PSV was more in SGA group by grouping maternal age （〈 27 years）（P = 0.006）, and gestational age （〉 34 weeks）（P 〈 0.001）. CONCLUSION： The results of this study suggest that MCA PI decreased significantly in SGA fetuses, while UA PI increased in this group. Moreover, PSV increased in this group when evaluated in different subgroups （based on maternal age and gestational age）.

关键词： small for gestational age middle cerebral artery peak systolic velocity

Stochastic many-body calculations of moiréstates in twisted bilayer graphene at high pressures

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npj Computational Materials 2022年第1期8卷 89-98页

作者： Mariya Romanova Vojtěch Vlček Department of Chemistry and Biochemistry University of CaliforniaSanta BarbaraCA93106-9510USA

We introduce three developments within the stochastic many-body perturbation theory:efficient evaluation of off-diagonal self-energy terms,construction of Dyson orbitals,and stochastic constrained random phase *** stochastic approaches readily handle systems with thousands of *** use them to explore the electronic states of twisted bilayer graphene(tBLG)characterized by giant unit cells and correlated electronic *** document the formation of electron localization under compression;weakly correlated states are merely shifted in *** demonstrate how to efficiently downfold the correlated subspace on a model Hamiltonian with a screened frequency-dependent two-body *** the 6°tBLG system,the onsite interactions are between 200 and 300 meV under *** Dyson orbitals exhibit spatial distribution similar to the mean-field single-particle *** pressure,the electron-electron interactions increase in the localized states;however,the dynamical screening does not fully balance the dominant bare Coulomb interaction.

关键词： interaction twisted stochastic

Thermostable Broad Band Polarizing PVA-Film: Theoretical and Experimental Investigations

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Chinese Journal of Structural Chemistry 2018年第2期37卷 186-197页

作者： SIYAMAK Shahab LIUDMILA Filippovich hora A.Almodarresiyeh MASOOME Sheikhi RAKESH Kumar Institute of Physical Organic Chemistry National Academy of Sciences of Belarus Institute of Chemistry of New Materials National Academy of Sciences of Belarus Belarussian State University ISEI BSU Minsk Young Researchers and Elite Club Gorgan Branch Islamic Azad University Department of Chemistry DAV University

In the present work, for the first time on the basis ofpoly （vinyl alcohol）（PVA）, 2- （4-dimethylaminostyryl）-l-ethylquinolinium iodide （quinaldine red （QR）） and trisodium （4E）-5-oxo- 1-（4-sulfonatophenyl）-4-[（4-sulfonatophenyl）hydrazono]-3 pyrazolecarboxylate （tartrazine （T））, thermostable polarizing film in a wide range of spectra （λmax=394-511 nm） with polarization efficiency （PE） = 98% in absorption maximum and stretching degree （Rs） = 3.5 was developed. The basic spectral-polarization parameters （polarization efficiency and transmittance） of oriented colored PVA-films were measured and discussed. During the work it was found that oriented PVA-films are the phenomenon of anisotropy of thermal conductivity （λ｜/λ⊥）. It is a very important parameter for the development of thermostable PVA-polarizing films. For the first time quantum-chemical calculations using density functional theory （DFT） approach for structural analysis and electronic spectrum of the QR were carried out via the B3LYP/dgdzvp and TDB3LYP/dgdzvp methods. Interpretation of absorption strips in visible region of spectrum was also reported. The excitation energies, electronic transitions and oscillator strengths for the studied structures have also been calculated （B3LYP/dgdzvp）. The NBO analysis and Mulliken atomic charges of the QR were carried out.

关键词： thermostable broad band polarizer fdm Quinaldine Red Tartrazine electronicspectrum anisotropy of thermal conductivity

Theoretical Study of Adsorption Behavior of Vemurafenib Drug over BNNT(5,5-9) as a Factor of Drug Delivery: a DFT Study

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Chinese Journal of Structural Chemistry 2020年第8期39卷 1422-1436,1358页

作者： MASOOME Sheikhi SIYAMAK Shahab hora Alhosseini Almodarresiyeh MEHRNOOSH Khaleghian RAKESH Kumar ALekSANDRA Strogova Young Researchers and Elite Club Gorgan BranchIslamic Azad UniversityGorganIran Belarusian State University ISEI BSUMinskRepublic of Belarus Institute of Physical Organic Chemistry National Academy of Sciences of Belarus13 Surganov Str.Minsk 220072Republic of Belarus Institute of Chemistry of New Materials National Academy of Sciences of Belarus36 Skarina Str.Minsk 220141Republic of Belarus Department of Materials and Metallurgy Engineering Meybod UniversityMeybodIran Department of Chemistry Islamshahr BranchIslamic Azad UniversityIslamshahrIran Department of Chemistry MCM DAV College Kangra Himachal Pradesh 176001(India)

In this research,a density functional theory(DFT)calculation was performed for investigation adsorption behavior of the anticancer drug Vemurafenib on BNNT(5,5-9)by using the M06-2X/6-31 G*level of theory in the solvent *** electronic spectra of the Vemurafenib drug,BNNT(5,5-9)and complex BNNT(5,5-9)/Vemurafenib in solvent water were calculated by Time Dependent Density Functional Theory(TD-DFT)for the study of adsorption *** non-bonded interaction effects of the Vemurafenib drug with BNNT(5,5-9)on the electronic properties,natural charges and chemical shift tensors have been also *** results display the change in title parameters after process *** to the natural bond orbital(NBO)results,the molecule Vemurafenib and BNNT(5,5-9)play as both electron donor and acceptor at the complex BNNT(5,5-9)/*** the other hand,the charge transfer occurs between the bonding,antibonding or nonbonding orbitals in two molecules drug and *** a consequence,BNNT(5,5-9)can be considered as a drug delivery system for the transportation of Vemurafenib as anticancer drug within the biological systems.

关键词： vemurafenib BNNT(5,5-9) DFT charge transfer NBO