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Friction 2024年第3期12卷 375-395页

作者： Xiao YANG Heli LIU Lemeng ZHANG Yiran HU Denis J.POLITIS Mohammad M.GHARBI Liliang WANG Department of Mechanical Engineering Imperial College LondonLondon SW72AZUK Department of Mechanical and Manufacturing Engineering University of CyprusNicosia 1678Cyprus Quaker Houghton Deutschland GmbH Dortmund 44319Germany

The accurate representation of tribological boundary conditions at the tool–workpiece interface is crucial for analysis and optimization of formability,material flow,and surface quality of components during metal forming *** has been found that these tribological conditions vary spatially and historically with process parameters and contact *** time-dependent tribological behaviours are also known as transient tribological phenomena,which are widely observed during forming processes and many other manufacturing application ***,constant friction values are usually assigned to represent complex and dynamic interfacial conditions,which would introduce deviations in the relevant *** this paper,transient tribological phenomena and the contemporary understanding of the interaction between friction and wear are reviewed,and it has been found that these phenomena are induced by the transitions of friction mechanisms and highly dependent on complex loading conditions at the *** modelling techniques for transient behaviours for metal forming applications are also *** accurately describe the evolutionary friction values and corresponding wear during forming,the advanced interactive friction modelling has been established for different application scenarios,including lubricated condition,dry sliding condition(metal-on-metal contact),and coated system.

关键词： transient tribological phenomena interactive friction mechanism modelling techniques metal forming

Development of an experimental method for well-controlled blast induced traumatic limb fracture in rats

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Defence Technology（防务技术） 2024年第4期34卷 168-176页

作者： Luyang Xu Xiancheng Yu Clement DFavier Ibidumo Igah Thuy-Tien Nguyen Warren Macdonald Anthony MJ.Bull Centre for Blast Injury Studies Imperial College LondonLondonUnited Kingdom Department of Bioengineering Imperial College LondonLondonUnited Kingdom Dyson School of Design Engineering Imperial College LondonLondonUnited Kingdom Department of Trauma and Orthopaedics Royal Free London National Health Service Foundation TrustLondonUnited Kingdom

Heterotopic ossification(HO)is a consequence of traumatic bone and tissue damage,which occurs in 65%of military casualties with blast-associated ***,the mechanisms behind blast-induced HO remain *** models are used to study blast-induced HO,but developing such models is challenging,particularly in how to use a pure blast wave(primary blast)to induce limb fracture that then requires an *** studies,including our recent study,have developed platforms to induce limb fractures in rats with blast loading or a mixture of blast and impact ***,these models are limited by the survivability of the animal and repeatability of the *** this study,we developed an improved platform,aiming to improve the animal's survivability and injury repeatability as well as focusing on primary blast *** platform exposed only one limb of the rat to a blast wave while providing proper protection to the rest of the rat's *** obtained very consistent fracture outcome in the tibia(location and pattern)in cadaveric rats with a large range of size and ***,the rats did not obviously move during the test,where movement is a potential cause of uncontrolled *** further conducted parametric studies by varying the features of the design of the *** factors,such as how the limb is fixed and how the cavity through which the limb is placed is sealed,significantly affect the resulting *** platform and test setups enable well-controlled limb fracture induced directly by pure blast wave,which is the fundamental step towards a complete in vivo animal model for blast-induced HO induced by primary blast alone,excluding secondary and tertiary blast *** addition,the platform design and the findings presented here,particularly regarding the proper protection of the animal,have implications for future studies investigating localized blast injuries,such as blast induced brain and lung injuries.

关键词： Blast injury Biomechanics Heterotopic ossification Limb fracture Blast wave Animal model

Process engineering of demineralisation of moderate to high ash Indian coals through NaOH‑HCl leaching and HF leaching

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International Journal of Coal Science & Technology 2024年第2期11卷 111-122页

作者： Heena Dhawan D.K.Sharma ANRF Ministry of ScienceNew DelhiIndia Department of Energy Science and Engineering Indian Institute of Technology DelhiNew Delhi 110016India

Chemical leaching of coals would be required to produce cleaner coals for some special applications where physical benefi-ciation may not be effective *** would also help in recovering Li and rare earth metals besides in the sequestration of CO_(2).About 20 Indian coals having complexly distributed moderate to high ash contents were sequentially treated with various alkali–acid such as NaOH-HCl,HF,HCl,HCl-HF,and NaOH-HCl-HF *** aimed to establish and design the best stepwise sequential process for the highest degree of demineralisation through a chemical leaching *** and process intensification studies were carried *** than 80%demineralisation of Madhaipur and Neemcha coals was observed using the best sequential treatment designed *** repeated stepwise treatment of the alkali and the acid was also studied,which was found to significantly enhance the degree of demineralisation of *** integrated process of alkali–acid leaching followed by solvent extraction(Organo-refining)and vice versa of the treated coal was also studied for producing cleaner coals.

关键词： Alkali–acid leaching Demineralisation Integrated process Rare earth elements

A stable CS-FEM for the static and seismic stability of a single square tunnel in the soil where the shear strength increases linearly with depth

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Journal of Rock Mechanics and Geotechnical Engineering 2022年第4期14卷 1253-1265页

作者： H.C.Nguyen L.Nguyen-Son Department of Civil and Environmental Engineering Imperial College LondonLondonUK Department of Civil Engineering and Industrial Design University of LiverpoolLiverpoolUK Faculty of Civil Engineering Ho Chi Minh City University of Technology(HUTECH)Ho Chi Minh CityViet Nam

A numerical procedure using a stable cell-based smoothed finite element method(CS-FEM)is presented for estimation of stability of a square tunnel in the soil where the shear strength increases linearly with *** kinematically admissible displacement fields are approximated by uniform quadrilateral elements in conjunction with the strain smoothing technique,eliminating volumetric locking issues and the singularity associated with the MohreCoulomb ***,a rich set of simulations was performed to compute the static stability of a square tunnel with different geometries and soil *** presented results are in excellent agreement with the upper and lower bound solutions using the standard finite element method(FEM).The stability charts and tables are given for practical use in the tunnel design,along with a newly proposed formulation for predicting the undrained stability of a single square ***,the seismic stability number was computed using the present numerical *** results reveal that the seismic stability number reduces with an increasing value of the horizontal seismic acceleration(a_(h)),for both cases of the weightless soil and the soil with unit ***,the link between the static and seismic stability numbers is described using corrective factors that represent reductions in the tunnel stability due to seismic *** is shown from the numerical results that the corrective factor becomes larger as the unit weight of soil mass increases;however,the degree of the reduction in seismic stability number tends to reduce for the case of the homogeneous ***,this advanced numerical procedure is straightforward to extend to three-dimensional(3D)limit analysis and is readily applicable for the calculation of the stability of tunnels in highly anisotropic and heterogeneous soils which are often encountered in practice.

关键词： Tunnels Stability Limit analysis Cell-based smoothed finite element method (CS-FEM) Second-order cone programming(SOCP)

Epidemiology of civilian blast injuries inflicted by terrorist bombings from 1970-2016

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Defence Technology（防务技术） 2018年第5期14卷 469-476页

作者： Danyal Magnus Mansoor A.Khan William G.Proud Institute of Shock Physics Blackett Laboratory Imperial College London Department of Surgery and Trauma Imperial College London St Mary's Hospital

An upsurge of terrorist activity has occurred in the past two decades. As part of this, explosive devices continue to be extensively deployed against civilians in wide-ranging environments. Bombings remain the leading worldwide cause of civilian fatalities due to terrorism. This demands an understanding of modern terrorist bombing trends to inform mitigation strategy. The objective of this study was to identify the occurrence and severity of bombings against civilian targets in diverse attack settings, and to establish corresponding blast injury profiles. Data was obtained from analysis of the Global Terrorism Database(GTD) and a meta-analysis of blast injury data derived from the PubMed database. Closed environment explosions were associated with significantly greater(p<0.05) mortality than in open spaces. The injury profiles were found to be influenced by attack setting, with higher rates of primary injury on trains and buses, and secondary injury in open space.

关键词： Terrorism Bombings Blast injury Epidemiology Blast mitigation

The use of the node-based smoothed finite element method to estimate static and seismic bearing capacities of shallow strip footings

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Journal of Rock Mechanics and Geotechnical Engineering 2022年第1期14卷 180-196页

作者： H.C.Nguyen T.Vo-Minh Department of civil and environmental engineering imperial college londonuk Department of civil engineering and industrial design university of liverpoolliverpooluk Faculty of civil engineering ho chi minh city university of technology(hutech)ho chi minh cityviet nam

The node-based smoothed finite element method(NS-FEM)is shortly presented for calculations of the static and seismic bearing capacities of shallow strip footings.A series of computations has been performed to assess variations in seismic bearing capacity factors with both horizontal and vertical seismic *** results obtained agree very well with those using the slip-line method,revealing that the magnitude of the seismic bearing capacity is highly dependent upon the combinations of various directions of both components of the seismic *** upward vertical seismic acceleration reduces the seismic bearing capacity compared to the downward vertical seismic acceleration in *** addition,particular emphasis is placed on a separate estimation of the effects of soil and superstructure inertia on each seismic bearing capacity *** the effect of inertia forces arising in the soil on the seismic bearing capacity is non-trivial,and the superstructure inertia is the major contributor to reductions in the seismic bearing *** tables and charts are given for practical application to the seismic design of the foundations.

关键词： Limit analysis Node-based smoothed finite element method(NS-FEM) Second-order cone programming(SOCP) Seismic bearing capacity Strip footing

Determining a representative element volume for DEM simulations of samples with non-circular particles

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Particuology 2022年第9期20卷 29-43页

作者： Peter Adesina Catherine O'Sullivan Tokio Morimoto Masahide Otsubo Dept.of Civil and Environmental Engineering Imperial College LondonSouth KensingtonLondon SW72AZUK Institute of Industrial Science The University of Tokyo4-6-1 Komaba Meguro-kuTokyo 153-8505Japan

Numerical studies on the number of particles or system size required to attain a representative element volume(REV)for discrete element method(DEM)simulations of granular materials have almost always considered samples with spherical or circular *** study considers how many particles are needed to attain a REV for 2D samples of 2-disc cluster particles where the particle aspect ratio(AR)was systematically *** and loose assemblies of particles were *** minimum REV was assessed both by considering the repeatability of static packing characteristics and the shearing behaviour in biaxial compression tests,and by investigating the effect of sample size on the measured characteris-tics and observed shearing *** repeatability of the data considered generally improved with increasing sample *** packing characteristics of the dense samples were more repeatable suggest-ing that the minimum REV reduces with increasing packing *** minimum REV was observed to be sensitive to the characteristic *** the overall responses of the samples during shear deformation were similar irrespective of the sample sizes,the smaller the sample size,the higher the fluctuations observed in the *** of the coefficient of variation of the fluctuations around the critical state stress ratio can provide insight as to whether a REV is *** particle AR influences the effect of sample size on shearing characteristics and thus the minimum number of particles required to attain a REV;this can be explained by the influence of AR on the number of contacts within the samples.

关键词： DEM Representative element volume Non-circular particles Particle shape Granular materials

Changes in feeding selectivity of freshwater invertebrates across a natural thermal gradient

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Current Zoology 2018年第2期64卷 231-242页

作者： Timothy A. C. GORDON Joana NETO-CEREJEIRA Paula C. FUREY Eoin J. O'GORMAN imperial college london Silwood Park Campus Buckhurst Road Ascot Berkshire SL5 7PY UK Biosciences College of Life and Environmental Sciences University of Exeter Stocker Road Exeter EX4 4QD UK Department of Biology Saint Catherine University St Paul MN 55105 USA

Environmental warming places physiological constraints on organisms, which may be mitigated by their feeding behavior. Theory predicts that consumers should increase their feeding selectivity for more energetically valuable resources in warmer environments to offset the disproportionate increase in metabolic demand relative to ingestion rate. This may also result in a change in feeding strategy or a shift towards a more specialist diet. This study used a natural warming experiment to investigate temperature effects on the feeding selectivity of three freshwater invertebrate grazers： the snail Radix balthica, the blackfly larva Simulium aureum, and the midgefly larva Eukiefferiella minor. Chesson＇s Selectivity Index was used to compare the proportional abundance of diatom species in the guts of each invertebrate species with corresponding rock biofilms sampled from streams of different tem- perature. The snails became more selective in warmer streams, choosing high profile epilithic diatoms over other guilds and feeding on a lower diversity of diatom species. The blackfly larvae appeared to switch from active collector gathering of sessile high profile diatoms to more passive filter feeding of motile diatoms in warmer streams. No changes in selectivity were observed for the midgefly larvae, whose diet was representative of resource availability in the environment. These results suggest that key primary consumers in freshwater streams, which constitute a major portion of invertebrate biomass, can change their feeding behavior in warmer waters in a range of different ways. These patterns could potentially lead to fundamental changes in the flow of energy through freshwater food webs.

关键词： climate change global warming diet Lymnaea peregra Simuliidae Chironomidae

Current and future pharmacological therapies for managing cirrhosis and its complications

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World Journal of Gastroenterology 2019年第8期25卷 888-908页

作者： David Kockerling Rooshi Nathwani Roberta Forlano Pinelopi Manousou Benjamin H Mullish Ameet Dhar Liver Unit/Division of Integrative Systems Medicine and Digestive Disease Imperial College London

Due to the restrictions of liver transplantation,complication-guided pharmacological therapy has become the mainstay of long-term management of *** article aims to provide a complete overview of pharmacotherapy options that may be commenced in the outpatient setting which are available for managing cirrhosis and its complications,together with discussion of current controversies and potential future ***/Medline/Cochrane Library were electronically searched up to December 2018 to identify studies evaluating safety,efficacy and therapeutic mechanisms of pharmacological agents in cirrhotic adults and animal models of ***-selective betablockers effectively reduce variceal re-bleeding risk in cirrhotic patients with moderate/large varices,but appear ineffective for primary prevention of variceal development and may compromise renal function and haemodynamic stability in advanced *** observational studies suggest protective,haemodynamically-independent effects of beta-blockers relating to reduced bacterial *** gut-selective antibiotic rifaximin is effective for secondary prophylaxis of hepatic encephalopathy;recent small trials also indicate its potential superiority to norfloxacin for secondary prevention of spontaneous bacterial *** remain the mainstay of uncomplicated ascites treatment,and early trials suggest alpha-adrenergic receptor agonists may improve diuretic response in refractory *** have not demonstrated clinical effectiveness in treating refractory ascites and may cause detrimental *** initial hepatotoxicity concerns,safety of statin administration has been demonstrated in compensated ***,statins are suggested to have protective effects upon fibrosis progression,decompensation and *** as to whether proton pump inhibitors cause gut-liver-brain axis dysfunction is *** evidence indicates that anticoa

关键词： Cirrhosis Beta-blockers Rifaximin Diuretics Statins Proton pump inhibitors Pharmacology

Future aircraft cabins and design thinking:optimisation ***-win scenarios

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Propulsion and Power Research 2013年第2期2卷 85-95页

作者： A.Hall T.Mayer I.Wuggetzer P.R.N.Childs royal college of art south kensington londonsw72euunited kingdom imperial college london south kensington londonsw72azunited kingdom airbus operations gmbh kreetslag 1021129 hamburgdeutschland

With projections indicating an increase in mobility over the next few decades andannual flight departures expected to rise to over 16 billion by 2050,there is a demand for theaviation industry and associated stakeholders to consider new forms of aircraft and *** requirements are recognized as a key driver in *** airline is the principalcustomer for the aircraft *** passenger is,in turn,the airline's principal customerbut they are just one of several stakeholders that include aviation authorities,airport operators,air-traffic control and security *** passenger experience is a key differentiator usedby airlines to attract and retain custom and the fuselage that defines the cabin envelope for thein-flight passenger experience and cabin design therefore receives significant attention for newaircraft,service updates and *** making in design is crucial to arrivingat viable and worthwhile cabin *** litle innovation will result in an aircraftmanufacturer and airlines using its products falling behind its *** much mayresult in an over-extension with,for example,use of immature technologies that do not havethe necessary reliability for a safety critical industry or sufficient value to justify the develop-ment *** multiple requirements associated with cabin design,can be viewed as an area for optimisation,accepting trade-offs between the various *** design,however,is often defined as developing a concept that resolves the contradictions and takes the solutiontowards a win-win *** our understanding and practice of design allows forbehaviors that enhance design thinking through divergence and convergence,the use ofabductive reasoning,experimentation and systems *** paper explores and definesthe challenges of designing the aireraft cabin of the future that will deliver on the multiplerequirements using experiences from the A350 XWB and future cabin design

关键词： Aircraft Cabin Design Optimisation Parameter Decision