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The interaction between a shaped charge jet and a single moving plate

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Defence Technology（防务技术） 2024年第1期31卷 1-13页

作者： Andreas Helte Jonas Lundgren Jonas Candle FOI WeaponsProtection and SecuritySE-16490StockholmSweden

Reactive armour is a very efficient add-on armour against shaped charge *** reactive armour consists of one or several plates that are accelerated by an *** but less violent acceleration of plates can also be achieved in a completely inert reactive *** be efficient against elongated jets,the motion of the plates needs to be inclined against the jet such that a sliding contact between the jet and the plates is *** sliding contact causes a deflection and thinning of the *** certain circumstances,the contact will become unstable,leading to severe disturbances on the *** disturbances will drastically reduce the jet penetration performance and it is therefore of interest to study the conditions that leads to an unstable *** studies on the interaction between shaped charge jets and flyer plates have shown that it is mainly the forward moving plate in an explosive reactive armour that is effective in disturbing the *** is usually attributed to the higher plate-to-jet mass flux ratio involved in the collision of the forward moving plate compared to the backward moving *** slow moving plates,as occurs in inert reactive armour,the difference in mass flux for the forward and backward moving plate is much lesser,and it is therefore of interest to study if other factors than the mass flux influences on the protection *** this work,experiments have been performed where a plate is accelerated along its length,interacting with a shaped charge jet that is fired at an oblique angle to the plate’s normal,either against or along the plate’s *** arrangement corresponds to a jet interacting with a flyer plate from a reactive armour,with the exception that the collision velocity is the same for both types of obliquities in these *** experiments show that disturbances on the jet are different in the two cases even though the collision velocities are the *** simulatio

关键词： Reactive armour Flyer plate Shaped charge jet

Mechanisms behind the environmental sensitivity of carbon fiber reinforced polytetrafluoroethylene(PTFE)

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Friction 2024年第5期12卷 997-1015页

作者： Pontus JOHANSSON P.MARKLUND M.BJORLING Y.SHI Division of Machine Element LuleåUniversity of TechnologyLuleåSE-97187Sweden

Carbon fiber reinforced polytetrafluoroethylene (CF/PTFE) composites are known for their exceptional tribological performance when sliding against steel or cast iron in inert gas environments. Compared to experiments in humid air, about an order of magnitude lower wear rate and several times lower coefficient of friction have been reported for tests conducted in dry nitrogen and hydrogen. Moreover, trace moisture has been shown to affect the friction and wear significantly of this tribosystem, although a possible effect of oxygen cannot be ruled out due to uncertainties regarding the oxygen concentrations. While several studies have pointed out the environmental sensitivity of CF/PTFE, the understanding of the underlying mechanisms are very limited. The objective of this research is to investigate the individual and combined effect of oxygen and moisture on the tribological behavior of CF/PTFE sliding against steel. Additionally, this study aims to elucidate the underlying mechanisms that govern the environmental sensitivity of the system. Climate-controlled three-pin-on-disc experiments were conducted in nitrogen atmospheres at various concentrations of oxygen and moisture. The tribological results clearly demonstrate that both moisture and oxygen contribute to increased friction and wear. However, the adverse effect was much more pronounced for oxygen than moisture. A qualitative method was developed to estimate the tribofilm coverage on the CF/PTFE surface. Results showed strong correlation between high coverage of strongly adhered tribofilm and low wear rate. Moreover, a loosely adhered tribofilm was observed on top of the CF/PTFE surface in presence of moisture. FTIR analysis indicated that the loosely adhered tribofilm found in the moisture-enriched environment contained a significant amount of adsorbed water, which may explain the lower coefficient of friction in presence of moisture compared to oxygen. The adsorbed water in the loosely adhered tribofilm coul

关键词： polymer composite tribofilm tribochemistry atmosphere

Development and evaluation of a vision driven sensor for estimating fuel feeding rates in combustion and gasification processes

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Energy and AI 2024年第1期15卷 44-54页

作者： YngveÖren Alexey sepman Ehsan Fooladgar Fredrik Weiland Henrik Wiinikka RIse AB Box 726 SE-94128PiteåSweden Energy Engineering Division of Energy ScienceLuleåUniversity of TechnologySE 97187LuleåSweden

A machine vision driven sensor for estimating the instantaneous feeding rate of pelletized fuels was developed and tested experimentally in combustion and gasification *** feeding rate was determined from images of the pellets sliding on a transfer chute into the *** the images the apparent area and velocity of the pellets were *** was determined by a segmentation model created using a machine learning framework and velocities by image registration of two subsequent *** measured weight of the pelletized fuel passed through the feeding system was in good agreement with the weight estimated by the *** observed variations in the fuel feeding correlated with the variations in the gaseous species concentrations measured in the reactor core and in the *** the developed sensor measures the ingoing fuel feeding rate prior to the reactor,its signal could therefore help improve process control.

关键词： Fuel feeding Process monitoring Image processing Neural network Combustion Gasification

Towards implementation of alloy-specific thermo-fluid modelling for laser powder-bed fusion of Mg alloys

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Journal of Magnesium and Alloys 2024年第6期12卷 2327-2344页

作者： Mohammad Hoseini-Athar Mikael Ersson Peter Hedström Department of Material Science and Engineering KTH Royal Institute of TechnologyStockholmSE-10044 Sweden

Multi-physics thermo-fluid modeling has been extensively used as an approach to understand melt pool dynamics and defect formation as well as optimizing the process-related parameters of laser powder-bed fusion(L-PBF).However,its capabilities for being implemented as a reliable tool for material design,where minor changes in material-related parameters must be accurately captured,is still in *** the present research,first,a thermo-fluid computational fluid dynamics(CFD)model is developed and validated against experimental *** the predicted material properties of the pure Mg and commercial ZK60 and WE43 Mg alloys,parametric studies are done attempting to elucidate how the difference in some of the material properties,i.e.,saturated vapor pressure,viscosity,and solidification range,can influence the melt pool *** is found that a higher saturated vapor pressure,associated with the ZK60 alloy,leads to a deeper unstable keyhole,increasing the keyhole-induced porosity and evaporation mass *** viscosity and wider solidification range can increase the non-uniformity of temperature and velocity distribution on the keyhole walls,resulting in increased keyhole instability and formation of ***,the WE43 alloy showed the best behavior in terms of defect formation and evaporation mass loss,providing theoretical support to the extensive use of this alloy in *** summary,this study suggests an approach to investigate the effect of materials-related parameters on L-PBF melting and solidification,which can be extremely helpful for future design of new alloys suitable for L-PBF.

关键词： Mg alloys Laser powder-bed fusion(L-PBF) Melt pool dynamics Computational fluid dynamics Fluid flow

Conducting Polymer-Based e-Refinery for Sustainable Hydrogen Peroxide Production

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Energy & Environmental Materials 2024年第2期7卷 334-342页

作者： Zhixing Wu Penghui Ding Viktor Gueskine Robert Boyd Eric Daniel G■owacki Magnus Odén Xaνier Crispin Magnus Berggren Emma M.Björk Mikhail Vagin Nanostructured Materials Department of PhysicsChemistry and Biology(IFM)Linköping UniversitySE 58183LinköpingSweden Laboratory of Organic Electronics Department of Science and Technology(ITN)Linköping UniversitySE 60174NorrköpingSweden

Electrocatalysis enables the industrial transition to sustainable production of chemicals using abundant precursors and electricity from renewable ***-centralized production of hydrogen peroxide(H_(2)O_(2))from water and oxygen of air is highly desirable for daily life and *** report an effective electrochemical refinery(e-refinery)for H_(2)O_(2)by means of electrocatalysis-controlled comproportionation reaction(2_(H)O+o→2HO),feeding pure water and oxygen *** nickel(Ⅱ)oxide(NiO)was used as electrocatalyst for oxygen evolution reaction(OER),producing oxygen at the *** polymer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS)drove the oxygen reduction reaction(ORR),forming H_(2)O_(2)on the *** reactions were evaluated in both half-cell and device *** performance of the H_(2)O_(2)e-refinery,assembled on anion-exchange solid electrolyte and fed with pure water,was limited by the unbalanced ionic *** of the operation conditions allowed a conversion efficiency of 80%.

关键词： conducting polymer hydrogen peroxide nickel(Ⅱ)oxide oxygen evolution reaction oxygen reduction reaction

How Does Stacking Pressure Affect the Performance of Solid Electrolytes and All-Solid-State Lithium Metal Batteries?

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Energy & Environmental Materials 2024年第4期7卷 93-98页

作者： Junwu Sang Bin Tang Yong Qiu Yongzheng Fang Kecheng Pan Zhen Zhou Interdisciplinary Research Center for Sustainable Energy Science and Engineering (IRC4se2) School of Chemical Engineering Zhengzhou University

All-solid-state lithium metal batteries (ASSLMBs) with solid electrolytes (ses)have emerged as a promising alternative to liquid electrolyte-based Li-ion batteries due to their higher energy density and ***,since ASSLMBs lack the wetting properties of liquid electrolytes,they require stacking pressure to prevent contact loss between electrodes and ses.

关键词： critical current density solid electrolyte solid-state lithium metal batteries stacking pressure

Influence of railway wheel tread damage on wheel-rail impact loads and the durability of wheelsets

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Railway Engineering Science 2024年第1期32卷 20-35页

作者： Michele Maglio Tore Vernersson Jens C.O.Nielsen Anders Ekberg Elena Kabo CHARMEC Department of Mechanical and Maritime SciencesChalmers University of TechnologySE‑41296 GothenburgSweden

Dynamic wheel-rail contact forces induced by a severe form of wheel tread damage have been measured by a wheel impact load detector during full-scale field tests at different vehicle *** on laser scanning,the measured three-dimensional damage geometry is employed in simulations of dynamic vehicle-track interaction to calibrate and verify a simulation *** relation between the magnitude of the impact load and various operational parameters,such as vehicle speed,lateral position of wheel-rail contact,track stiffness and position of impact within a sleeper bay,is *** calibrated model is later employed in simulations featuring other forms of tread damage;their effects on impact load and subsequent fatigue impact on bearings,wheel webs and subsurface initiated rolling contact fatigue of the wheel tread are *** results quantify the effects of wheel tread defects and are valuable in a shift towards condition-based maintenance of running gear,and for general assessment of the severity of different types of railway wheel tread damage.

关键词： Wheel tread damage Rolling contact fatigue cluster Field measurements Dynamic vehicle-track interaction Wheel-rail impact load Wheelset durability

Research progress in CALPHAD assisted metal additive manufacturing

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China Foundry 2024年第4期21卷 295-310页

作者： Ya-qing Hou Xiao-qun Li Wei-dong Cai Qing Chen Wei-ce Gao Du-peng He Xue-hui Chen Hang Su China Iron&Steel Research Institute Group Beijing 100081China Thermo-Calc Software AB SolnaSE-169Sweden KTH Royal Institute of Technology StockholmSE-100Sweden Central Iron and Steel Research Institute Beijing 100081China

Metal additive manufacturing(MAM)technology has experienced rapid development in recent *** both equipment and materials progress towards increased maturity and commercialization,material metallurgy technology based on high energy sources has become a key factor influencing the future development of *** calculation of phase diagrams(CALPHAD)is an essential method and tool for constructing multi-component phase diagrams by employing experimental phase diagrams and Gibbs free energy models of simple *** combining with the element mobility data and non-equilibrium phase transition model,it has been widely used in the analysis of traditional metal *** development of CALPHAD application technology for MAM is focused on the compositional design of printable materials,the reduction of metallurgical imperfections,and the control of microstructural *** endeavor carries considerable theoretical and practical *** paper summarizes the important achievements of CALPHAD in additive manufacturing(AM)technology in recent years,including material design,process parameter optimization,microstructure evolution simulation,and properties ***,the limitations of applying CALPHAD technology to MAM technology are discussed,along with prospective research directions.

关键词： metal additive manufacturing CALPHAD integrated computational material engineering powder bed fusion material design microstructure simulation

Site adaptation with machine learning for a Northern Europe gridded global solar irradiance product

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Energy and AI 2024年第1期15卷 265-278页

作者： sebastian Zainali Dazhi Yang Tomas Landelius Pietro Elia Campana Mälardalen University Department of Sustainable Energy SystemsVästerås SE 72123Sweden School of Electrical Engineering and Automation Harbin Institute of TechnologyHarbinHeilongjiangChina Swedish Meteorological and Hydrological Institute Norrköping SE 60176Sweden

Gridded global horizontal irradiance(GHI)databases are fundamental for analysing solar energy applications’technical and economic aspects,particularly photovoltaic ***,there exist numerous gridded GHI databases whose quality has been thoroughly validated against ground-based irradiance ***,databases that generate data at latitudes above 65˚are few,and those available gridded irradiance products,which are either reanalysis or based on polar orbiters,such as ERA5,COSMO-REA6,or CM SAF CLARA-A2,generally have lower quality or a coarser time resolution than those gridded irradiance products based on geostationary *** the high-latitude gridded GHI databases,the STRÅNG model developed by the Swedish Meteorological and Hydrological Institute(SMHI)is likely the most accurate one,providing data across *** further enhance the product quality,the calibration technique called"site adaptation"is herein used to improve the STRÅNG dataset,which seeks to adjust a long period of low-quality gridded irradiance estimates based on a short period of high-quality irradiance *** study introduces a novel approach for site adaptation of solar irradiance based on machine learning techniques,which differs from the conventional statistical methods used in previous *** machine-learning algorithms have been analysed and compared with conventional statistical approaches to identify Sweden’s most accurate algorithms for site *** irradiance data gathered from three weather stations of SMHI is used for training and *** results show that machine learning can substantially improve the STRÅNG model’s ***,due to the spatiotemporal heterogeneity in model performance,no universal machine learning model can be identified,which suggests that site adaptation is a location-dependant procedure.

关键词： Machine learning Global horizontal irradiance STRÅNG Site adaptation Agrivoltaic Sweden