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High-speed tracked vehicle model order reduction for static and dynamic simulations

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Defence technology（防务技术） 2024年第8期38卷 89-110页

作者： Luca dimauro Simone Venturini Antonio Tota Enrico Galvagno Mauro Velardocchia department of Mechanical and Aerospace Engineering Politecnico di TorinoCorso Duca degli Abruzzi2410129TorinoItaly

In this paper, a model order reduction strategy is adopted for the static and dynamic behaviour simulation of a high-speed tracked vehicle. The total number of degree of freedom of the structure is condensed through a selection of interface degrees of freedom and significant global mode shapes, for an approximated description of vehicle dynamic behaviour. The methodology is implemented in a customised open-source software to reduce the computational efforts. The modelled tracked vehicle includes the sprung mass, the unsprung masses, connected by means of torsional bars, and all the track assemblies, composing the track chain. The proposed research activity presents a comprehensive investigation of the influence of the track chain, combined with longitudinal vehicle speed, on statics and vehicle dynamics, focusing on vertical dynamics. The vehicle response has been investigated both in frequency and time domain. In this last case road-wheel displacements are assumed as inputs for the model, under different working conditions, hence considering several road profiles with different amplitudes and characteristic excitation frequencies. Simulation results have proven a high fidelity in model order reduction approach and a significant contribution of the track chain in the global dynamic behaviour of the tracked vehicle.

关键词： Tracked vehicle dynamics Rubber characteristics Component mode synthesis Modal analysis Open-source

Memristors-coupled neuron models with multiple firing patterns and homogeneous and heterogeneous multistability

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Chinese Physics B 2024年第10期33卷 176-189页

作者： Xuan Wang Santo Banerjee Yinghong Cao Jun Mou School of Information science and Engineering Dalian Polytechnic UniversityDalian 116034China department of Mathematical sciences Giuseppe Luigi LagrangePolitecnico di TorinoCorso Duca degli Abruzzi 24TorinoItaly

Memristors are extensively used to estimate the external electromagnetic stimulation and synapses for *** this paper,two distinct scenarios,i.e.,an ideal memristor serves as external electromagnetic stimulation and a locally active memristor serves as a synapse,are formulated to investigate the impact of a memristor on a two-dimensional Hindmarsh-Rose neuron *** simulations show that the neuronal models in different scenarios have multiple burst firing *** introduction of the memristor makes the neuronal model exhibit complex dynamical ***,the simulation circuit and DSP hardware implementation results validate the physical mechanism,as well as the reliability of the biological neuron model.

关键词： memristor multistability Hamilton energy firing pattern Neuron model hardware implementation

An innovative heterogeneous transfer learning framework to enhance the scalability of deep reinforcement learning controllers in buildings with integrated energy systems

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Building Simulation 2024年第5期17卷 739-770页

作者： Davide Coraci Silvio Brandi Tianzhen Hong Alfonso Capozzoli politecnico di torino Department of EnergyTEBE research groupBAEDA Lab.Corso Duca degli Abruzzi 24Torino10129Italy Building technology and Urban Systems division Lawrence Berkeley National LaboratoryOne Cyclotron RoadBerkeleyCA 94720USA

Deep Reinforcement Learning(DRL)-based control shows enhanced performance in the management of integrated energy systems when compared with Rule-Based Controllers(RBCs),but it still lacks scalability and generalisation due to the necessity of using tailored models for the training *** Learning(TL)is a potential solution to address this ***,existing TL applications in building control have been mostly tested among buildings with similar features,not addressing the need to scale up advanced control in real-world scenarios with diverse energy *** paper assesses the performance of an online heterogeneous TL strategy,comparing it with RBC and offline and online DRL controllers in a simulation setup using EnergyPlus and *** study tests the transfer in both transductive and inductive settings of a DRL policy designed to manage a chiller coupled with a Thermal Energy Storage(TES).The control policy is pre-trained on a source building and transferred to various target buildings characterised by an integrated energy system including photovoltaic and battery energy storage systems,different building envelope features,occupancy schedule and boundary conditions(e.g.,weather and price signal).The TL approach incorporates model slicing,imitation learning and fine-tuning to handle diverse state spaces and reward functions between source and target *** show that the proposed methodology leads to a reduction of 10% in electricity cost and between 10% and 40% in the mean value of the daily average temperature violation rate compared to RBC and online DRL ***,online TL maximises self-sufficiency and self-consumption by 9% and 11% with respect to ***,online TL achieves worse performance compared to offline DRL in either transductive or inductive ***,offline Deep Reinforcement Learning(DRL)agents should be trained at least for 15 episodes to reach the same level of performance as the online

关键词： transfer learning reinforcement learning building control building energy management

Improvement of Surface Mechanical and Tribological Characteristics of L-PBF Processed Commercially Pure Titanium through Ultrasonic Impact Treatment

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Acta Metallurgica Sinica(English Letters) 2024年第6期37卷 1034-1046页

作者： Iman Ansarian Reza Taghiabadi Saeid Amini Mohammad Hossein Mosallanejad Luca Iuliano Abdollah Saboori department of Materials science and Metallurgy Imam Khomeini International University(IKIU)QazvinIran department of Mechanical Engineering University of KashanKashanIran Integrated Additive Manufacturing Center Department of Management and Production EngineeringPolitecnico di TorinoCorso Duca Degli Abruzzi 2410129TurinItaly

Multi-pass ultrasonic impact treatment(UIT)was applied to modify the microstructure and improve the mechanical and tribological characteristics at the near-surface region of commercially pure Ti(CP-Ti)specimens produced by the laser powder bed fusion(L-PBF)*** considerably refined the L-PBF process-related acicular martensites(α′-M)and produced a well-homogenized and dense surface microstructure,where the porosity content of 1-,3-,and 5-pass UITed samples was reduced by 43,60,and 67%,*** UITed samples showed an enhancement in their near-surface mechanical properties up to a depth of about 300μ*** nanoindentation results for the 3-pass UITed sample revealed an increase of about 53,45,and 220%in its nanohardness,H/E_(r),and H_(3)/E_(r)^(2)indices,*** stylus profilometry results showed that performing the UIT removed the L-PBF-related features/defects and offered a smooth *** roughness average(R_(a))and the skewness(R_(sk))of the 3-pass UITed sample were found to be lower than those of the L-PBFed sample by 95 and 223%,*** the UIT also enhanced the material ratio,where the maximum load-bearing capacity(~100%)in as-L-PBFed(as-built)and 3-pass UITed samples was obtained at 60-and 10-µm depths,*** tribological investigations showed that applying the UIT resulted in a significant reduction of wear rate and average coefficient of friction(COF)of *** instance,under the normal pressures of 0.05 and 0.2 MPa,the wear rate and COF of the 3-pass UITed sample were lower than those of the L-PBFed sample by 65 and 58%,and 20 and 17%,respectively.

关键词： Laser powder bed fusion Ultrasonic impact treatment Commercially pure Ti(CP-Ti) Surface mechanical properties Tribological properties

The effectiveness of different wear indicators in quantifying wear on railway wheels of freight wagons

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Railway Engineering science 2024年第3期32卷 307-323页

作者： Philipe Augusto de Paula Pacheco M.Magelli Matheus Valente Lopes Pedro Henrique Alves Correa N.Zampieri N.Bosso Auteliano Antunes dos Santos Federal Institute of the Southeast of Minas Gerais(IF Sudeste MG) Técnico PanamáStreet 45Santos DumontMG 36246-311Brazil Railway Laboratory(Lafer) Universidade Estadual de Campinas(UNICAMP)Mendeleyev Street 200CampinasSP 13083-872Brazil department of Mechanical and Aerospace Engineering Politecnico Di TorinoC.so Duca degli Abruzzi 2410129 TurinItaly

Railway infrastructure relies on the dynamic interaction between wheels and rails;thus,assessing wheel wear is a critical aspect of maintenance and *** paper focuses on the wheel-rail wear indicator T-gamma(Tγ).Amidst its use,it becomes apparent that Tγ,while valuable,fails to provide a comprehensive reflection of the actual material removal and actual contact format,which means that using only Tγas a target for optimization of profiles is not *** this work,three different freight wagons are evaluated:a meter-gauge and a broad-gauge heavy haul vehicles from South American railways,and a standard-gauge freight vehicle operated in Europe,with different axle loads and dissimilar new wheel/rail *** vehicles are subjected to comprehensive multibody simulations on various *** simulations aimed to elucidate the intricate relationship between different wear indicators:Tγ,wear index,material removal,and maximum wear depth,under diverse curves,non-compensated lateral accelerations(A_(nc)),and *** findings showed a correlation of 0.96 between Tγand wear depth and 0.82 between wear index and material removed for the outer *** the results,the Tγis better than the wear index to be used when analyzing wear depth while the wear index is more suited to foresee the material *** results also show the low influence of A_(nc)on wear index and Tγ.By considering these factors together,the study aims to improve the understanding of wheel-rail wear by selecting the best wear analysis approaches based on the effectiveness of each parameter.

关键词： Wear index Wear volume Wear modeling Dynamic simulation

Microstructure and Thermal Conductivity of Al–Graphene Composites Fabricated by Powder Metallurgy and Hot Rolling Techniques

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Acta Metallurgica Sinica(English Letters) 2017年第7期30卷 675-687页

作者： Abdollah Saboori Matteo Pavese Claudio Badini Paolo Fino department of applied science and technology Politecnico di Torino Corso Duca degli Abruzzi 24 10129 Turin Italy

The objective of this research is to improve the thermal conductivity and mechanical properties of Al/GNPs（graphene nanoplatelets） nanocomposites produced by classical powder metallurgy and hot rolling techniques. The microstructural evaluation confirmed the uniform dispersion of GNPs at low content and agglomeration at higher contents of GNPs. The structure of graphene was studied before and after the mixing and the Raman spectrum proofs that the wet mixing has a great potential to be used as a dispersion method. There was no significant peak corresponding to the Al_4C_3 formation in both the differential scanning calorimetry curves and X-ray diffraction patterns. The microstructural observation in both fabrication techniques showed grain refinement as a function of the GNPs content. Moreover, the introduction of the GNPs not only improved the Vickers hardness of the composites but also decreased their density. The thermal conductivity investigations showed that in both the press-sintered and hot-rolled samples, although the thermal conductivity of composites was improved at low GNPs contents, it was negatively affected at high GNPs contents.

关键词： Aluminum Graphene Thermal conductivity Powder metallurgy Microstructure

Microstructure and Mechanical Performance of Ti-6Al-4V Lattice Structures Manufactured via Electron Beam Melting(EBM):A Review

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Acta Metallurgica Sinica(English Letters) 2020年第2期33卷 183-203页

作者： Giuseppe Del Guercio Manuela Galati Abdollah Saboori Paolo Fino Luca Iuliano department of Management and Production Engineering(diGEP) Politecnico di TorinoCorso Duca Degli Abruzzi 2410129 TurinItaly department of applied science and technology(disat) Politecnico di TorinoCorso Duca Degli Abruzzi 2410129 TurinItaly Integrated Additive Manufacturing Center(IAM)@Polito Politecnico Di TorinoCorso Duca Degli Abruzzi 2410129 TurinItaly

Electron beam melting(EBM) process is an additive manufacturing process largely used to produce complex metallic components made of high-performance materials for aerospace and medical ***,lattice structures made by Ti-6A1-4V have represented a hot topic for the industrial sectors because of having a great potential to combine lower weights and higher performances that can also be tailored by subsequent heat ***,the little knowledge about the mechanical behaviour of the lattice structures is limiting their *** present work aims to provide a comprehensive review of the studies on the mechanical behaviour of the lattice structures made of *** main steps to produce an EBM part were considered as guidelines to review the literature on the lattice performance:(1) design,(2) process and(3) post-heat ***,the correlation between the geometrical features of the lattice structure and their mechanical behaviour is *** addition,the correlation among the mechanical performance of the lattice structures and the process precision,surface roughness and working temperature are also *** investigation on the studies about the properties of heat-treated lattice structure is also conducted.

关键词： Electron beam melting(EBM) Additive manufacturing(AM) Lattice structures Ti–6Al–4V Mechanical properties Heat treatment

Development of AI-and Cu-based nanocomposites reinforced by graphene nanoplatelets： Fabrication and characterization

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Frontiers of Materials science 2017年第2期11卷 171-181页

作者： Abdollah SABOORI Matteo PAVESE Claudio BAdiNI Paolo FINO department of applied science and technology Politecnico Di Torino Corso Duca Degli Abruzzi 24 10129 Torino Italy

Aluminum and copper matrix nanocomposites reinforced by graphene nanoplatelets （GNPs） were successfully fabricated by a wet mixing method followed by conventional powder metallurgy. The uniform dispersion of GNPs within the metal matrices showed that the wet mixing method has a great potential to be used as a mixing technique. However, by increasing the GNPs content, GNPs agglomeration was more visible. DSC and XRD of AI/GNPs nanocomposites showed that no new phase formed below the melting point of AI. Microstructural observations in both nanocomposites reveal the evident grain refinement effect as a consequence of GNPs addition. The interfacial bonding evaluation shows a poor interfacial bonding between GNPs and AI, while the interfacial bonding between Cu and GNPs is strong enough to improve the properties of the Cu/GNPs nanocomposites. In both composites, the coefficient of thermal expansion decreases as a function of GNPs while, their hardness is improved by increasing the GNPs content as well as their elastic modulus.

关键词： nanocomposite aluminum copper graphene microstructure thermal expansion

From the elasticity theory to cosmology and vice versa

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science China(Physics,Mechanics & Astronomy) 2014年第4期57卷 597-603页

作者： LEVRINO Luca TARTAGLIA Angelo politecnico di torino Department of Applied Science and Technology Corso Duca degli Abruzzi 2410129 Torino Italy

The paper shows how a generalization of the elasticity theory to four dimensions and to space-time allows for a consistent description of the homogeneous and isotropic universe,including the accelerated *** analogy is manifested by the inclusion in the traditional Lagrangian of general relativity of an additional term accounting for the strain induced in the manifold(*** space-time)by the curvature,be it induced by the presence of a texture defect or by a matter/energy *** additional term is su?cient to account for various observed features of the universe and to give a simple interpretation for the so called dark ***,we show how the same approach can be adopted back in three dimensions to obtain the equilibrium configuration of a given solid subject to strain induced by defects or applied ***,it is shown how concepts coming from the familiar elasticity theory can inspire new approaches to cosmology and in return how methods appropriated to General Relativity can be applied back to classical problems of elastic deformations in three dimensions.

关键词： deformable solids cosmology elastic strain Lagrangian density and tensors