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influence of lubrication,tool steel composition,and topography on the high temperature tribological behaviour of aluminium

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Friction 2021年第1期9卷 155-168页

作者： Justine DECROZANT-TRiQUENAUX leonardo PELCASTRE Braham PRAKASH Jens HARDELL Machine Elements Lulea University of TechnologyLulea SE-97187Sweden Department of Mechanical Engineering Tsinghua UniversityBeijing 100084China

The use of high strength aluminium alloys,such as 6 XXX and 7 XXX series,is continuously increasing for automotive applications in view of their good strength-to-weight *** formability at room temperature is limited and they are thus often formed at high temperatures to enable production of complex *** challenges during hot forming of aluminium are the occurrence of severe adhesion and material transfer onto the forming *** negatively affects the tool life and the quality of the produced *** general,the main mechanisms involved in the occurrence of material transfer of aluminium alloys at high temperature are still not clearly ***,this study is focussed on understanding of the friction and wear behaviour during interaction of Al6016 alloy and three different tool steels in as-received and polished *** tribotests were carried out under dry and lubricated conditions,with two distinct lubricants,using a reciprocating friction and wear *** worn surfaces were analysed using scanning electron microscopy(SEM)and energy dispersive X-ray spectroscopy(EDS).The results showed a high dependence of friction and wear behaviour on the tool steel roughness as well as on the stability of the lubricant *** were found to develop in the contact zone and their capacity to improve the tribological behaviour is seen to be drastically impacted by the surface roughness of the tool *** the tribolayers failed,severe adhesion took place and led to high and unstable friction as well as material transfer to the tool steel.

关键词： friction wear high temperature tribology aluminium lubrication tribolayer

Biomechanical modeling of metal screw loadings on the human vertebra

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Acta Mechanica Sinica 2021年第2期37卷 307-320页

作者： leonardo Molinari Cristina Falcinelli Alessio Gizzi Alberto Di Martino Department of Engineering Campus Bio-Medico University of RomeVia A.del Portillo 21Rome 00128Italy Department of Biomedical and Neuromotor Science DiBiNEM University of BolognaBolognaItaly 1st Orthopaedic and Traumatologic Clinic IRCCS Istituto Ortopedico RizzoliBolognaItaly

During spinal fusion surgery,angled screw insertion can provide a more favorable stress distribution reducing failure events(screw breakage and loosening).Finite element(FE)analysis can be employed for identifying the optimal insertion path,preventing stress concentrations,and ensuring a lower failure *** this work,a patient-specific FE model of L4 vertebra,virtually implanted with two pedicle screws,was obtained from diagnostic images and numerically *** elastic,inhomogeneous,and isotropic material properties were assigned to bone based on density distributions reconstructed from the medical *** mechanical response of the screws-vertebra system was analyzed through a progressive damage procedure,considering a stress-based *** screws insertion angles were simulated,as well as physiological loading *** each loading case,screw orientation influences the fracture mechanism(i.e.,brittle or ductile one),as well as the fracture pattern and ***,stresses in trabecular bone and pedicle screws are significantly affected by the screw *** caudomedial trajectory indicates the most safe case,significantly reducing the stress concentrations in both trabecular bone and *** findings aim to furnish a useful indication to surgeons regarding the screws insertion angle,further reducing the failure risk and improving the clinical outcome of the fixation procedure.

关键词： Fracture mechanics Patient-specific FE modeling Vertebra mechanics Screw orientation Stress analysis

Determination of future land use changes using remote sensing imagery and artificial neural network algorithm:A case study of Davao City,Philippines

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Artificial intelligence in Geosciences 2023年第1期4卷 111-118页

作者： Cristina E.Dumdumaya Jonathan Salar cabrera College of information and Computing University of Southeastern PhilippinesBrgy.ObreroDavao CityPhilippines Faculty of Computing Data SciencesEngineering and TechnologyDavao Oriental State UniversityMati CityDavao Oriental8200Philippines

Land use and land cover(LULC)changes refer to alterations in land use or physical *** changes can be caused by human activities,such as urbanization,agriculture,and resource extraction,as well as natural phenomena,for example,erosion and climate *** changes significantly impact ecosystem services,biodiversity,and human *** this study,LULC changes in Davao City,Philippines,were simulated,predicted,and projected using a multilayer perception artificial neural network(MLP-ANN)*** MLP-ANN model was employed to analyze the impact of elevation and proximity to road networks(i.e.,exploratory maps)on changes in LULC from 2017 to *** predicted 2021 LULC map shows a high correlation to the actual LULC map of 2021,with a kappa index of 0.91 and a 96.68%*** MLP-ANN model was applied to project LULC changes in the future(i.e.,2030 and 2050).The results suggest that in 2030,the built-up area and trees are increasing by 4.50%and 2.31%,***,water will decrease by up to 0.34%,and crops is about to decrease by approximately 3.25%.in the year 2050,the built-up area will continue to increase to 6.89%,while water and crops will decrease by 0.53%and 3.32%,***,the results show that anthropogenic activities influence the land’s ***,the study illustrates how machine learning models can generate a reliable future scenario of land usage changes.

关键词： LULC Artificial neural network Remote sensing Land use land cover prediction Multilayer perception Philippines

Oxidative effects of the harmful algal blooms on primary organisms of the food web

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BiOCELL 2019年第2期43卷 41-50页

作者： JOAQUiN cabrera PAULA MARiELA GONZALEZ SUSANA PUNTARULO Universidad de Buenos Aires Facultad de Farmacia y BioquimicaFisicoquimica.Buenos AiresArgentina CONiONi CETET-Universidad de Buenos Aires.instituto de Bioquimica y Medicina Molecular(iBi iBi MOLOL).Buenos Aires Argentina

Degraded water quality from nutrient pollution,physical,biological,and other chemical factors contributes to the development and persistence of many harmful algal blooms(HAB s).The complex dynamics of the HAB s is a challenge to marine ecosystems for the toxic effects *** consequences include fish,bird,and mammal mortality,respiratory or digestive tract problems,memory loss,seizures,lesions and skin irritation in many *** review is intended to briefly summarize the recent reported information on harmful marine toxin deleterious effects over the primary organisms of the food web,namely algae,zooplankton and *** focus is made on oxidative stress status of cells and *** though in situ field research is less controlled than laboratory studies,in which the organisms are directly exposed to the toxins under consideration,both types of approaches are required to fully understand such a complex *** top of that,the contribution of the increasing water temperatures in the sea,as a consequence of the global climate change,will be addressed as a topic for further studies,to evaluate the effect on regulating algal growth,species composition,trophic structure,metabolic stress and function of aquatic ecosystems.

关键词： Harmful algal toxins oxidative stress algae zooplankton invertebrates

Heat Transfer in internal Channel of a Blade:Effects of Rotation in a Trailing Edge Cooling System

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Journal of Thermal Science 2012年第3期21卷 236-249页

作者： Luca Andrei Antonio Andreini leonardo Bonanni Bruno Facchini Department of Energy Engineering "Sergio Stecco" University of Florence

The aerothermal performance of a trailing edge （TE） internal cooling system of a high pressure gas turbine blade was evaluated under stationary and rotating conditions. The investigated geometry consists of a 30：1 scaled model reproducing a typical wedge shaped discharge duct with one row of enlarged pedestals. The airflow pattern inside the device simulates a highly loaded rotor blade cooling scheme with a 90 [deg] turning flow from the radial hub inlet to the tangential TE outlet. Two different tip configurations were tested, the first one with a completely closed section, the second one with a 5 holes outlet surfaces discharging at ambient pressure. in order to assess rotation effects, a rotating test rig, composed of a rotating ann holding both the PMMA TE model and the instru mentation, was purposely developed and manufactured. A thin inconel heating foil and wide band Thermochromic Liquid Crystals are used to perform steady state heat transfer measurements on the blade pres sure side. A rotary joint ensures the pneumatic connection between the blower and the rotating apparatus; more over several slip rings are used for both instrumentation power supply and thermocouple connection. A parallel CFD analysis involving steadystate RANS modeling was conducted to allow an insight of the flow field inside the redirecting channel and the interpedestal ducts to better interpret the developing vortical structures. LowReynolds grid clustering permits to integrate up to the wall both the momentum and the thermal boundary layer. Calculations were performed by means of an inhouse developed pressure based solver exploiting the kco SST turbulence model implemented in the framework of the opensource finite volume discretization toolbox OpenFOAM~. Analyzed flow conditions correspond to Reynolds number of 20000 in the hub inlet section and angular speed varies to obtain rotation numbers in the range from 0 to 0.3. The orientation of the rotation axis is orthogonal to the heated s

关键词： heat transfer trailing edge pedestal rotation number OpenFOAM~ CFD TLC thermography

On the wavelet analysis of cutting forces for chatter identification in milling

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Advances in Manufacturing 2017年第2期5卷 130-142页

作者： Cesar Giovanni cabrera Anna Carla Araujo Daniel Alves Castello Department of Mechanical Engineering UniversidadeFederal do Rio de Janeiro Rio de Janeiro Brazil

Chatter vibrations in machining operations affect surface finishing and tool behaviour, particularly in the end-milling of aluminum parts for the aerospace industry. This paper presents a methodological approach to identify chatter vibrations during manufacturing processes. it relies on wavelet analyses of cutting force signals during milling operations. The cutting-force signal is first decomposed into an approximation/trend sub-signal and detailed subsignals, and it is then re-composed using modified subsignals to reduce measurement noise and strengthen the reference peak forces. The reconstruction of the cuttingforce signal is performed using a wavelet denoising pro- cedure based on a hard-thresholding method. Four experimental configurations were set with specific cutting parameters using a workpiece specifically designed to allow experiments with varying depths of cut. The experimental results indicate that resultant force peaks （after applying the threshold to the detailed sub-signals） are related to the presence of chatter, based on the increased correlation of such peaks and the surface roughness profiles, thereby reinforcing the applicability of the proposed method. The results can be used to control the online occurrence of chatter in end-milling processes, as the method does not depend on the knowledge of cutting geometry nor dynamic parameters.

关键词： Cutting force End milling Chatter Waveletfilter

A Low-carbon Operation Optimization Method of ETG-RiES Based on Adaptive Optimization Spiking Neural P Systems

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Protection and Control of Modern Power Systems 2024年第5期9卷 162-177页

作者： Tao Wang Zhu Huang Ruixuan Ying Luis Valencia-cabrera School of Electrical Engineering and Electronic information Xihua UniversityChengdu 610039China the Xiluodu Hydropower Plant China Yangtze Power Co.Ltd.Zhaotong 657300China the institute of Multidisciplnary Research for Ad-vanced Materials Tohoku UniversitySendai 980-8577Japan Department of Computer Science and Artificial intelligence University of SevilleAvda.Reina Mercedes s/n 41012Spain

To enhance multi-energy complementarity and foster a low carbon economy of energy resources,this paper proposes an innovative low-carbon operation opti-mization method for electric-thermal-gas regional inte-grated energy *** bolster the low-carbon operation capabilities of such systems,a coordinated operation framework is presented that integrates carbon capture devices,power to gas equipment,combined heat and power units,and a multi-energy storage *** address the challenge of high-dimensional constraint imbalance in the optimization process,a novel low-carbon operation opti-mization method is then *** new method is based on an adaptive single-objective continuous optimiza-tion spiking neural P system,specifically designed for this ***,simulation models of four typical schemes are established and employed to test and analyze the economy and carbon environmental pollution degree of the proposed system model,as well as the performance of the operation optimization ***,simulation results show that the proposed method not only considers the economic viability of the target integrated energy sys-tem,but also significantly improves the wind power utilization and carbon reduction capabilities.

关键词： Spiking neural P system power-to-gas membrane computing regional integrated energy system low-carbon operation optimization

Domenico Losurdo on Stalin:A Dialectical and Comparative Perspective on a Controversial Legacy

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Fudan Journal of the Humanities and Social Sciences 2024年第3期17卷 399-416页

作者： leonardo Pegoraro Melbourne Australia

This article explores the insights of the italian Marxist philosopher Domenico Losurdo on Stalin,with a focus on his controversial work:Stalin:History and Cri-tique of a Black *** sheds light on the metamorphosis of Stalin's image from a revered leader into a human monster”and challenges the equation of Stalin with Hitler(the“twin monsters theory”).He advocates for a balanced perspective that refutes the veneration-demonisation dichotomy and offers original criticism on various facets of the“black legend”:Stalin's alleged self-cult of personality;the common juxtaposition of Soviet Gulags with Nazi camps;and accusations of geno-cide against Ukrainians(known as the Holodomor)and *** article also highlights Losurdo's methodology,consisting of a comprehensive comparative approach that calls into question the liberal tradition to reveal parallels between its darker aspects and *** demonstrates how the twin monsters theory eventually serves to bolster liberalism's claim of moral ***,his work extends beyond Stalin to provide a wider assessment and criticism of most of the contemporary historiography's themes and approaches,revealing how history is often manipulated for political reasons.

关键词： Stalin Losurdo Communism Nazism Liberalism

Displacement Trends of Slow-moving Landslides: Classification and Forecasting

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Journal of Mountain Science 2014年第3期11卷 592-606页

作者： CASCiNi leonardo CALVELLO Michele GRiMALDi Giuseppe Maria Department of Civil Engineering University of Salerno

A framework is proposed to characterize and forecast the displacement trends of slow-moving landslides, defined as the reactivation stage of phenomena in rocks or fine-grained soils, with movements localized along one or several existing shear surfaces. The framework is developed based on a thorough analysis of the scientific literature and with reference to significant reported case studies for which a consistent dataset of continuous displacement measurements is available. Three distinct trends of movement are defined to characterize the kinematic behavior of the active stages of slow-moving landslides in a velocity-time plot: a linear trend-type i, which is appropriate for stationary phenomena; a convex shaped trend-type ii, which is associated with rapid increases in pore water pressure due to rainfall, followed by a slow decrease in the groundwater level with time; and a concave shaped trend-type iii, which denotes a non-stationary process related to the presence of new boundary conditions such as those associated with the development of a newly formed local slip surface that connects with the main existing slip surface. Within the proposed framework, a model is developed to forecast future displacements for active stages of trend-type ii based on displacement measurements at the beginning of the stage. The proposed model is validated by application to two case studies.

关键词： Slow-moving landslides Displacements forecast Trends of movement