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Tensile strength behavior of cement-stabilized dredged sediment reinforced by polypropylene fiber

Frontiers of Structural and Civil Engineering 2024年第3期18卷 380-392页

作者： Lei LANG Jiangshan LI Xin CHEN Lijun HAN Ping WANG State Key laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicChinese Academy of SciencesWuhan 430071China Hubei Provincial Key laboratory of Contaminated Sludge and Soil Science and Engineering Wuhan 430071China University of Chinese Academy of Sciences Beijing 100049China

This study evaluated the feasibility of using polypropylene fiber(PF)as reinforcement in improving tensile strength behavior of cement-stabilized dredged sediment(CDS).The effects of cement content,water content,PF content and length on the tensile strength and stress–strain behavioral evolutions were evaluated by conducting splitting tensile strength tests.Furthermore,the micro-mechanisms characterizing the tensile strength behavior inside PF-reinforced CDS(CPFDS)were clarified via analyzing macro failure and microstructure images.The results indicate that the highest tensile strengths of 7,28,60,and 90 d CPFDS were reached at PF contents of 0.6%,1.0%,1.0%,and 1.0%,exhibiting values 5.96%,65.16%,34.10%,and 35.83%higher than those of CDS,respectively.Short,3 mm,PF of showed the best reinforcement efficiency.The CPFDS exhibited obvious tensile strain-hardening characteristic,and also had better ductility than CDS.The mix factor(C_(C)^(a)/C_(w)^(b))and time parameter(q_(t0)(t))of CDS,and the reinforcement index(k_(t-PF))of CPFDS were used to establish the tensile strength prediction models of CDS and CPFDS,considering multiple factors.The PF“bridge effect”and associated cementation-reinforcement coupling actions inside CPFDS were mainly responsible for tensile strength behavior improvement.The key findings contribute to the use of CPFDS as recycled engineering soils.

关键词： dredged sediment chemical stabilization fiber reinforcement splitting tensile strength micro-mechanisms

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Tuning mechanical behaviors of highly entangled hydrogels with the random distribution of mobile entanglements

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Applied Mathematics and mechanics(English Edition) 2024年第2期45卷 277-294页

作者： Jinlong LIU Di LU Bin CHEN Department of Engineering mechanics Zhejiang UniversityHangzhou 310027China Beijing System Design Institute of Electro-mechanic Engineering Beijing 100854China Intelligent Robotic Research Center Zhejiang LaboratoryHangzhou 310027China Key laboratory of Soft Machines and Smart Devices of Zhejiang Province Hangzhou 311100China

Highly entangled hydrogels exhibit excellent mechanical properties,including high toughness,high stretchability,and low hysteresis.By considering the evolution of randomly distributed entanglements within the polymer network upon mechanical stretches,we develop a constitutive theory to describe the large stretch behaviors of these hydrogels.In the theory,we utilize a representative volume element(RVE)in the shape of a cube,within which there exists an averaged chain segment along each edge and a mobile entanglement at each corner.By employing an explicit method,we decouple the elasticity of the hydrogels from the sliding motion of their entanglements,and derive the stress-stretch relations for these hydrogels.The present theoretical analysis is in agreement with experiment,and highlights the significant influence of the entanglement distribution within the hydrogels on their elasticity.We also implement the present developed constitutive theory into a commercial finite element software,and the subsequent simulations demonstrate that the exact distribution of entanglements strongly affects the mechanical behaviors of the structures of these hydrogels.Overall,the present theory provides valuable insights into the deformation mechanism of highly entangled hydrogels,and can aid in the design of these hydrogels with enhanced performance.

关键词： highly entangled hydrogel constitutive theory entanglement gamma distribution

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Fluid-structure interaction simulation for multi-body flexible morphing structures

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Chinese Journal of Aeronautics 2024年第2期37卷 137-147页

作者： Wenzhi GUO Yongtao SHUI Lu NIE Gang CHEN State Key laboratory of Strength and Vibration for mechanic Structures School of Aerospace EngineeringXi’an Jiaotong UniversityXi’an 710049China China Academy of Launch Vehicle Technology Beijing 100076China China Academy of Aerospace Science and Innovation Beijing 100086China Shannxi Key laboratory of Service Environment and Control for Flight Vehicles Xi’an Jiaotong UniversityXi’an 710049China

The multi-body flexible morphing airfoil can improve the aerodynamic characteristics based on different flight missions continuously.Recently researches have focused on the unsteady aerodynamic characteristics of flexible wings under passive actuation.However,the unsteady aerodynamic characteristics with the fluid-structure interaction effects in the multi-body active actuation process of morphing airfoil deserve further investigation.In this paper,a fluid-structure coupled simulation method for multi-body flexible morphing airfoil with active actuation subsystem was investigated,and the aerodynamic characteristics during deformation were compared with different skin flexibility,flow field environment,actuation mode and actuation time.The numerical results show that for the steady aerodynamic,the skin flexibility can improve the stability efficiency.In the unsteady process,the change trend of the transient lift coefficient and pitching moment are consistent with those of the active drive characteristics,while the instantaneous lift-drag ratio coefficient is greatly affected by the driving mode and can be improved by increasing the driving duration.

关键词： Fluid-structure interaction Multi-body dynamics modeling Flexible structures Aerodynamics Morphing wings

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Investigations of the mechanical response of dummy HTPB propellant grain under ultrahigh acceleration overload conditions using onboard flight-test measurements

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Defence Technology（防务技术） 2024年第2期32卷 473-484页

作者： Yiming Zhang Ningfei Wang Weihua Ma Ran Wang Long Bai Yi Wu School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China Beijing System Design Institute of Electro-mechanic Engineering Beijing 100854China Xi'an Changfeng Research Institute of Mechanism and Electricity Xi'an 710065China

In this paper,to study the mechanical responses of a solid propellant subjected to ultrahigh acceleration overload during the gun-launch process,specifically designed projectile flight tests with an onboard measurement system were performed.Two projectiles containing dummy HTPB propellant grains were successfully recovered after the flight tests with an ultrahigh acceleration overload value of 8100 g.The onboard-measured time-resolved axial displacement,contact stress and overload values were successfully obtained and analysed.Uniaxial compression tests of the dummy HTPB propellant used in the gunlaunched tests were carried out at low and intermediate strain rates to characterize the propellant's dynamic properties.A linear viscoelastic constitutive model was employed and applied in finite-element simulations of the projectile-launching process.During the launch process,the dummy propellant grain exhibited large deformation due to the high acceleration overload,possibly leading to friction between the motor case and propellant grain.The calculated contact stress showed good agreement with the experimental results,though discrepancies in the overall displacement of the dummy propellant grain were observed.The dynamic mechanical response process of the dummy propellant grain was analysed in detail.The results can be used to estimate the structural integrity of the analysed dummy propellant grain during the gun-launch process.

关键词： Gun-launched flight test Dummy HTPB propellant Onboard measurements Utrahigh overload mechanical response

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Shear Resistance of Siltous Sands Improved with Bridelia Tannins

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Geomaterials 2024年第1期14卷 1-11页

作者： Sinko Banakinao Soviwadan Drovou Komlan Lolo Kodjo Attipou Department of Civil Engineering Polytechnic School of Lomé University of Lomé Lomé Togo laboratory of Structure and mechanic of Materials (LaS2M) University of Lomé Lomé Togo

The ruin of several civil engineering works occurs due to shear rupture of the ground. When the stress is greater than the shear resistance, the internal friction angle and the cohesion of the soil loosen and rupture occurs. Cement and lime are often used to stabilize soils and improve soil strength. The costs and environmental problems of these technologies raise concerns and challenge researchers to innovate with clean, inexpensive materials, accessible to the most disadvantaged social classes. The question that this study seeks to answer is whether the binders derived from plant tannins, which also stabilize soils, improve the shear resistance of these soils. To do this, we determined for silty sand the shear parameters, notably the cohesion and the angle of internal friction in the non-stabilized state and when they are stabilized with the powder of the bark of the Bridelia under different water states. The results show that the addition of Bridelia powder to silty sand increases the cohesion of the soil by nearly 70.71% and the friction angle by 4.31%. But in unfavourable water conditions, the cohesion and internal friction angle of the silty sand material improved with Bridelia bark powder drops drastically by nearly 81.56%. but does not dissolve completely as for the same material. When it is not stabilized. This information is an invaluable contribution in the search for solutions to increase the durability of earthen constructions by improving the water-repellent properties of soils.

关键词： Silty Sand Bridelia Tannins Shear Resistance Cohesion Angle of Friction

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Enhanced photocatalytic performance of Bi_(2)O_(2)CO_(3)/Bi_(4)O_(5)Br_(2)/reduced graphene oxide Z-schemehe terojunction via a one-pot room-temperature synthesis

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Journal of Environmental Sciences 2024年第4期138卷 418-427页

作者： Xiaoge Wu Lei Yan Rongrong Qin Qikai Zhang Wei Yang Xiaozhi Wang Yongcai Zhang Min Luo Jianhua Hou College of Environmental Science and Engineering Yangzhou UniversityYangzhouJiangsu 225009China Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization Nanjing 210095China Beijing Xinfeng Aerospace Equipment Co. Ltd.Beijing 100854China Beijing System Design Institute of Electro-mechanic Engineering Beijing 100005China College of Chemistry and Chemical Engineering Ningxia UniversityYinchuanNingxia 750021China

Bi_(2)O_(2)CO_(3)(BOC)/Bi_(4)O_5Br_(2)(BOB)/reduced graphene oxide(rGO)Z-scheme heterojunction with promising photocatalytic properties was synthesized via a facile one-pot room-temperature method.Ultra-thin nanosheets of BOC and BOB were grown in situ on r GO.The formed 2D/2D direct Z-scheme heterojunction of BOC/BOB with oxygen vacancies(OVs)effectively leads to lower negative electron reduction potential of BOB as well as higher positive hole oxidation potential of BOC,showing improved reduction/oxidation ability.Particularly,rGO is an acceptor of the electrons from the conduction band of BOC.Its dual roles significantly improve the transfer performance of photo-induced charge carriers and accelerate their separation.With layered nanosheet structure,rich OVs,high specific surface area,and increased utilization efficiency of visible light,the multiple synergistic effects of BOC/BOB/rGO can achieve effective generation and separation of the electron-holes,thereby generating more·O_(2)^(-)and h^(+).The photocatalytic reduction efficiency of CO_(2)to CO(12.91μmol/(g·hr))is three times higher than that of BOC(4.18μmol/(g·hr)).Moreover,it also achieved almost 100%removal of Rhodamine B and cyanobacterial cells within 2 hours.

关键词： Bi_(2)O_(2)CO_(3) Bi_(4)O_(5)Br_(2) Reduced graphene oxide Z-scheme heterojunction Photocatalysis CO_(2)reduction

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Study of Iron Ore Processing Technology of Tamir Gol Deposit in Mongolia

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Journal of Minerals and Materials Characterization and Engineering 2024年第3期12卷 165-188页

作者： Mаngal Delgermaa Lkhagva Byambadorj Ayurzana Purevdorj Department of Metallurgy and Production Engineering School of Mechanical Engineering and Transportation MUST Ulaanbaatar Mongolia Beren Metal Co. Ltd. Beren Grup Ulaanbaatar Mongolia Foundry Workshop Repair Mechanic Plant Erdenet Factory Erdenet Mongolia

Iron ore processing for steel production is crucial to the development and economy of Mongolia. Regardless of having abundant natural resources and raw materials, Mongolia almost doesn’t produce final products. So far, most mining and mineral beneficiation plants export raw materials only subjected to beneficiation process. Out of more than 200 deposits in Mongolia, 91 deposits had been explored with different methods and stages, and estimated the resource of 33 reserves. Without processing the iron ore, it is impossible to use it for steelmaking due to its high sulfur and phosphorus impurities. Therefore, to study the processing of iron ore deposits in Mongolia, we did a preliminary investigation of iron ore deposits and took samples from the Tamir Gol deposit with high silica and phosphorus content that is difficult to process. Then, conducted mineral analysis and determined the grain structure and beneficiation characteristics of Tamir Gol iron deposit. .

关键词： Resource Ore Structure Reserve Analysis Composition

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Concerns about the application of resistance exercise with blood-flow restriction and thrombosis risk in hemodialysis patients

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Journal of Sport and Health Science 2024年第4期13卷 548-558,F0003页

作者： Hugo de Luca Correa Lysleine Alves Deus Dahan da Cunha Nascimento Nicholas Rolnick Rodrigo Vanerson Passos Neves Andrea Lucena Reis Thais Branquinho de Araujo Carmen Tzanno-Martins Fernanda Silveira Tavares Luiz Sinesio Silva Neto Claudio Avelino Rodrigues Santos Paolo Lucas Rodrigues-Silva Fernando Honorato Souza Vitoria Marra da Motta Vilalva Mestrinho Rafael Lavarini dos Santos Rosangela Vieira Andrade Jonato Prestes Thiago dos Santos Rosa Post-graduate Program of Physical Education Catholic University of BrasıliaBrasılia 71966-700Brazil The Human Performance mechanic Lehman CollegeNew YorkNY 10011USA Clinical Group Home Dialysis Center and RenalClass Sao Paulo 01239-040Brazil Department of Medicine Catholic University of BrasıliaBrasılia 71966-700Brazil Faculty of Medicine Federal University of TocantinsTocantins 77001-090Brazil Embrapa Genetic Resources and Biotechnology Brasılia 70770-917Brazil Graduate Program of Genomic Sciences and Biotechnology Brasılia 71966-700Brazil

Background:Hemodialysis(HD)per se is a risk factor for thrombosis.Considering the growing body of evidence on blood-flow restriction(BFR)exercise in HD patients,identification of possible risk factors related to the prothrombotic agent D-dimer is required for the safety and feasibility of this training model.The aim of the present study was to identify risk factors associated with higher D-dimer levels and to determine the acute effect of resistance exercise(RE)with BFR on this molecule.Methods:Two hundred and six HD patients volunteered for this study(all with a glomerular filtration rate of70 years old),and HD vintage.Furthermore,RE+BFR significantly increases D-dimer after 4 h.Patients with borderline baseline D-dimer levels(400-490 ng/mL)displayed increased risk of elevating D-dimer over the normal range(-500 ng/mL).Conclusion:These results identified factors associated with a heightened prothrombotic state and may assist in the screening process for HD patients who wish to undergo RE+BFR.D-dimer and/or other fibrinolysis factors should be assessed at baseline and throughout the protocol as a precautionary measure to maximize safety during RE+BFR.

关键词： Blood-flow restriction Chronic kidney disease Coagulation Hemodialysis Vascular occlusion exercises

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Response to Commentary by Dr. Matthew J. Clarkson on "Concerns on the application of blood-flow restriction resistance exercise and thrombosis risk in hemodialysis patients"

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Journal of Sport and Health Science 2024年第5期13卷 670-671页

作者： Hugo de Luca Corrêa Lysleine Alves Deus Dahan da Cunha Nascimento Nicholas Rolnick Rodrigo Vanerson Passos Neves Andrea Lucena Reis Thais Branquinho de Araújo Carmen Tzanno-Martins Fernanda Silveira Tavares Luiz Sinésio Silva Neto Cláudio Avelino Rodrigues Santos Paolo Lucas Rodrigues-Silva Fernando Honorato Souza Vitória Marra da Motta Vilalva Mestrinho Rafael Lavarini dos Santos Rosangela Vieira Andrade Jonato Prestes Thiago dos Santos Rosa Post-graduate Program of Physical Education Catholic University of BrasıliaBrasılia 71966-700Brazil The Human Performance mechanic Lehman CollegeNew YorkNY 10011USA Clinical Group Home Dialysis Center and RenalClass Sao Paulo 01239-040Brazil Department of Medicine Catholic University of BrasıliaBrasılia 71966-700Brazil Faculty of Medicine Federal University of TocantinsTocantins 77001-090Brazil Embrapa Genetic Resources and Biotechnology Brasılia 70770-917Brazil g Graduate Program of Genomic Sciences and Biotechnology Brasılia 71966-700Brazil

Dear editor:We sincerely thank Matthew J.Clarkson for his insightful commentary1 on our recent publication in the Journal of Sport and Health Science.2 Clarkson's pioneering work in the development and application of blood flow restriction (BFR) exercise protocols has undeniably laid the groundwork for subsequent investigations in this field,including our own.(3-6)His commentary not only highlights the relevance and timeliness of our study but also offers valuable perspectives on refining safety considerations for intradialytic BFR exercise among hemodialysis patients.

关键词： patients application flow

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Bioinspired Stretchable MXene Deformation-Insensitive Hydrogel Temperature Sensors for Plant and Skin Electronics

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Research 2024年第1期2023卷 389-401页

作者： Jun Wu Yinghui Li Shengshun Duan Zhehan Wang Xu Jing Yucheng Lin Di Zhu Wei Lei Qiongfeng Shi Li Tao Joint International Research laboratory of Information Display and Visualization School of Electronic Science and EngineeringSoutheast UniversityNanjingJiangsu 210096China School of Materials Science and Engineering Southeast UniversityNanjingJiangsu 210096China Center of 2D Materials and Devices Southeast UniversityNanjingJiangsu 210096China

Temperature sensing is of high value in the wearable healthcare,robotics/prosthesis,and noncontact physiological monitoring.However,the common mechanic deformation,including pressing,bending,and stretching,usually causes undesirable feature size changes to the inner conductive network distribution of temperature sensors,which seriously influences the accuracy.Here,inspired by the transient receptor potential mechanism of biological thermoreceptors that could work precisely under various skin contortions,we propose an MXene/Clay/poly(N-isopropylacrylamide)(PNIPAM)(MCP)hydrogel with high stretchability,spike response,and deformation insensitivity.The dynamic spike response is triggered by the inner conductive network transformation from the 3-dimensional structure to the 2-dimensional surface after water being discharged at the threshold temperature.The water discharge is solely determined by the thermosensitivity of PNIPAM,which is free from mechanical deformation,so the MCP hydrogels can perform precise threshold temperature(32℃)sensing under various deformation conditions,i.e.,pressing and 15%stretching.As a proof of concept,we demonstrated the applications in plant electronics for the real-time surface temperature monitoring and skin electronics for communicating between human and machines.Our research opens venues for the accurate temperature-threshold sensation on the complicated surface and mechanical conditions.

关键词： stretching proof precise

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