Minimum quantity Lubrication(MQL)is a sustainable lubrication system that is famous in many machining systems.It involve the spray of an infinitesimal amount of mist-like lubricants during machining processes.The MQL ...Minimum quantity Lubrication(MQL)is a sustainable lubrication system that is famous in many machining systems.It involve the spray of an infinitesimal amount of mist-like lubricants during machining processes.The MQL system is affirmed to exhibit an excellent machining performance,and it is highly economical.The nanofluids are understood to exhibit excellent lubricity and heat evacuation capability,compared to pure oil-based MQL system.Studies have shown that the surface quality and amount of energy expended in the grinding operations can be reduced considerably due to the positive effect of these nanofluids.This work presents an experimental study on the tribological performance of SiO_(2)nanofluid during grinding of Si_(3)N_(4)ceramic.The effect different grinding modes and lubrication systems during the grinding operation was also analyzed.Different concentrations of the SiO_(2)nanofluid was manufactured using canola,corn and sunflower oils.The quantitative evaluation of the grinding process was done based on the amount of grinding forces,specific grinding energy,frictional coefficient,and surface integrity.It was found that the canola oil exhibits optimal lubrication performance compared to corn oil,sunflower oil,and traditional lubrication systems.Additionally,the introduction of ultrasonic vibrations with the SiO_(2)nanofluid in MQL system was found to reduce the specific grinding energy,normal grinding forces,tangential grinding forces,and surface roughness by 65%,57%,65%,and 18%respectively.Finally,regression analysis was used to obtain an optimum parameter combinations.The observations from this work will aid the smooth transition towards ecofriendly and sustainable machining of engineering ceramics.展开更多
Elucidating the complex interactions between the work material and abrasives during grinding of gallium nitride(GaN)single crystals is an active and challenging research area.In this study,molecular dynamics simulatio...Elucidating the complex interactions between the work material and abrasives during grinding of gallium nitride(GaN)single crystals is an active and challenging research area.In this study,molecular dynamics simulations were performed on double-grits interacted grinding of GaN crystals;and the grinding force,coefficient of friction,stress distribution,plastic damage behaviors,and abrasive damage were systematically investigated.The results demonstrated that the interacted distance in both radial and transverse directions achieved better grinding quality than that in only one direction.The grinding force,grinding induced stress,subsurface damage depth,and abrasive wear increase as the transverse interacted distance increases.However,there was no clear correlation between the interaction distance and the number of atoms in the phase transition and dislocation length.Appropriate interacted distances between abrasives can decrease grinding force,coefficient of friction,grinding induced stress,subsurface damage depth,and abrasive wear during the grinding process.The results of grinding tests combined with cross-sectional transmission electron micrographs validated the simulated damage results,i.e.amorphous atoms,high-pressure phase transition,dislocations,stacking faults,and lattice distortions.The results of this study will deepen our understanding of damage accumulation and material removal resulting from coupling between abrasives during grinding and can be used to develop a feasible approach to the wheel design of ordered abrasives.展开更多
Grinding,a critical precision machining process for difficult-to-cut alloys,has undergone continual technological advancements to improve machining efficiency.However,the sustainability of this process is gaining heig...Grinding,a critical precision machining process for difficult-to-cut alloys,has undergone continual technological advancements to improve machining efficiency.However,the sustainability of this process is gaining heightened attention due to significant challenges associated with the substantial specific grinding energy and the extensive heat generated when working with difficult-to-cut alloys,renowned for their exceptional physical and mechanical properties.In response to these challenges,the widespread application of massive coolant in manufacturing industries to dissipate grinding heat has led to complex post-cleaning and disposal processes.This,in turn,has resulted in issues such as large energy consumption,a considerable carbon footprint,and concerns related to worker health and safety,which have become the main factors that restrict the development of grinding technology.This paper provides a holistic review of sustainability in grinding difficult-to-cut alloys,encompassing current trends and future directions.The examination extends to developing grinding technologies explicitly tailored for these alloys,comprehensively evaluating their sustainability performance.Additionally,the exploration delves into innovative sustainable technologies,such as heat pipe/oscillating heat pipe grinding wheels,minimum quantity lubrication,cryogenic cooling,and others.These groundbreaking technologies aim to reduce dependence on hazardous coolants,minimizing energy and resource consumption and carbon emissions associated with coolant-related or subsequent disposal processes.The essence of these technologies lies in their potential to revolutionize traditional grinding practices,presenting environmentally friendly alternatives.Finally,future development trends and research directions are put forward to pursue the current limitation of sustainable grinding for difficult-to-cut alloys.This paper can guide future research and development efforts toward more environmentally friendly grinding operations by understanding the current state of sustainable grinding and identifying emerging trends.展开更多
[Objectives] This study was conducted to improve the nutritional value of soybean milk, enrich the variety and taste of soybean milk, and find healthy food that is more conducive to people s nutritional needs. [Method...[Objectives] This study was conducted to improve the nutritional value of soybean milk, enrich the variety and taste of soybean milk, and find healthy food that is more conducive to people s nutritional needs. [Methods] Whole soybean milk was prepared by grinding with a grinding wheel at a low concentration (low-concentration grinding) and a stainless steel mill at a high concentration (high-concentration grinding). The sensory, physical and chemical characteristics and anti-nutritional factors of whole soybean milk produced by different grinding methods were studied. [Results] Compared with low-concentration grinding, the protein content in soybean milk prepared by high-concentration grinding increased by 24%, and the dietary fiber content increased by 74.7%. Before and after high-pressure homogenization, the particle size D(4, 3) of soybean milk prepared by low-concentration grinding was 212.1 and 93.59 μm, respectively, and the particle size D(4, 3) of soybean milk prepared by high-concentration grinding was 134.0 and 64.64 μm, respectively. The trypsin inhibitor activity and phytic acid content of soybean milk prepared by high-concentration grinding were significantly lower than those of soybean milk prepared by low-concentration grinding. [Conclusions] This study improves the diet structure of the broad masses of people, strengthens people s physique, and provides a new idea for the implementation and development of China s "Soybean Action Programme".展开更多
Fatigue properties are crucial for critical aero-engine components in extreme serviceenvironments,which are significantly affected by surface integrity(SI)indexes(especially surface topography,residual stressσ_(res),...Fatigue properties are crucial for critical aero-engine components in extreme serviceenvironments,which are significantly affected by surface integrity(SI)indexes(especially surface topography,residual stressσ_(res),and microhardness)after machining processes.Normal-direction ultrasonic vibration-assisted face grinding(ND-UVAFG)has advantages in improving the machinability of Inconel 718,but there is a competitive relationship between higher compressiveσ_(res)and higher surface roughness R_(a)in affecting fatigue strength.The lack of a quantitative relationship between multiple SI indexes and fatigue strength makes theindeterminacy of a regulatory strategy for improving fatigue properties.In this work,a model of fatigue strength(σ_f)_(sur)considering multiple SI indexes was developed.Then,high-cycle fatigue tests were carried out on Inconel 718 samples with different SI characteristics,and the influence of ND-UVAFG process parameters on SI was analyzed.Based on SI indexes data,the(σ_f)_(sur)distribution in the grinding surface layer for ND-UVAFG Inconel 718 samples was determined using the developed model,and then the fatigue crack initiation(FCI)sites were furtherpredicted.The predicted FCI sites corresponded well with the experimental results,therebyverifying this model.A strategy for improving the fatigue life was proposed in this work,which was to transfer the fatigue source from the machined surface to the bulk material by controlling the SI indexes.Finally,a critical condition of SI indexes that FCI sites appeared on the surface or in bulk material was given by fitting the predicted results.According to the critical condition,an SI field where FCI sites appeared in the bulk material could be obtained.In this field,thefatigue life of Inconel 718 samples could be improved by approximately 140%.展开更多
Ceramic matrix composites(CMCs)are highly promising materials for the next generation of aero-engines.However,machining of CMCs suffers from low efficiency and poor surfacefinish,which presents an obstacle to their wide...Ceramic matrix composites(CMCs)are highly promising materials for the next generation of aero-engines.However,machining of CMCs suffers from low efficiency and poor surfacefinish,which presents an obstacle to their wider application.To overcome these problems,this study investigates high-efficiency deep grinding of CMCs,focusing on the effects of grinding depth.The results show that both the sur-face roughness and the depth of subsurface damage(SSD)are insensitive to grinding depth.The material removal rate can be increased sixfold by increasing the grinding depth,while the surface roughness and SSD depth increase by only about 10%.Moreover,it is found that the behavior of material removal is strongly dependent on grinding depth.As the grinding depth is increased,fibers are removed in smaller sizes,with thefiber length in chips being reduced by about 34%.However,too large a grinding depth will result in blockage by chip powder,which leads to a dramatic increase in the ratio of tangential to normal grinding forces.This study demonstrates that increasing the depth of cut is an effective approach to improve the machining efficiency of CMCs,while maintaining a good surfacefin-ish.It provides the basis for the further development of high-performance grinding methods for CMCs,which should facilitate their wider application.展开更多
The distributed flexible job shop scheduling problem(DFJSP)has attracted great attention with the growth of the global manufacturing industry.General DFJSP research only considers machine constraints and ignores worke...The distributed flexible job shop scheduling problem(DFJSP)has attracted great attention with the growth of the global manufacturing industry.General DFJSP research only considers machine constraints and ignores worker constraints.As one critical factor of production,effective utilization of worker resources can increase productivity.Meanwhile,energy consumption is a growing concern due to the increasingly serious environmental issues.Therefore,the distributed flexible job shop scheduling problem with dual resource constraints(DFJSP-DRC)for minimizing makespan and total energy consumption is studied in this paper.To solve the problem,we present a multi-objective mathematical model for DFJSP-DRC and propose a Q-learning-based multi-objective grey wolf optimizer(Q-MOGWO).In Q-MOGWO,high-quality initial solutions are generated by a hybrid initialization strategy,and an improved active decoding strategy is designed to obtain the scheduling schemes.To further enhance the local search capability and expand the solution space,two wolf predation strategies and three critical factory neighborhood structures based on Q-learning are proposed.These strategies and structures enable Q-MOGWO to explore the solution space more efficiently and thus find better Pareto solutions.The effectiveness of Q-MOGWO in addressing DFJSP-DRC is verified through comparison with four algorithms using 45 instances.The results reveal that Q-MOGWO outperforms comparison algorithms in terms of solution quality.展开更多
BACKGROUND Extraction of impacted third molars often leads to severe complications caused by damage to the inferior alveolar nerve(IAN).AIM To proposes a method for the partial grinding of an impacted mandibular third...BACKGROUND Extraction of impacted third molars often leads to severe complications caused by damage to the inferior alveolar nerve(IAN).AIM To proposes a method for the partial grinding of an impacted mandibular third molar(IMM3)near the IAN to prevent IAN injury during IMM3 extraction.METHODS Between January 1996 and March 2022,25 patients with IMM3 roots near the IAN were enrolled.The first stage of the operation consisted of grinding a major part of the IMM3 crown with a high-speed turbine dental drill to achieve sufficient space between the mandibular second molar and IMM3.After 6 months,when the root tips were observed to be away from the IAN on X-ray examination,the remaining part of the IMM3 was completely removed.RESULTS All IMM3s were extracted easily without symptoms of IAN injury after extraction.CONCLUSION Partial IMM3 grinding may be a good alternative treatment option to avoid IAN injury in high-risk cases.展开更多
The energy-saving renovation of existing residential buildings is a crucial measure to achieve the strategic goal of energy conservation and emission reduction in China and build ecologically livable cities.This artic...The energy-saving renovation of existing residential buildings is a crucial measure to achieve the strategic goal of energy conservation and emission reduction in China and build ecologically livable cities.This article focuses on the perspective of subject behavior,starting from analyzing the current situation and difficulties of the operation of the energy-saving renovation market for existing residential buildings in China,drawing on the practical experience of the operation of the existing residential building energy-saving renovation market abroad.Based on principles such as systematicity,humanization,feasibility,and sustainability,the article constructs an operation optimization system of the existing residential building energy-saving renovation market from the perspective of subject behavior.In order to provide a reference for the healthy and orderly operation of the existing residential building energy-saving renovation market,this paper proposes implementation strategies for optimizing the operation of the existing residential building energy-saving renovation market.Suggestions are proposed from four aspects:optimizing the market environment,innovating the financing model,building the information sharing platform,and utilizing the synergies of the main subjects.展开更多
The development of the construction industry is shifting towards low-carbon construction,so it is necessary to improve and optimize related construction concepts,methods,and processes.By improving resource and energy ...The development of the construction industry is shifting towards low-carbon construction,so it is necessary to improve and optimize related construction concepts,methods,and processes.By improving resource and energy control efficiency in building projects,minimizing construction waste,and reducing environmental impact,a foundation for the sustainable development of the industry can be established.This paper mainly analyzes the significance of low-carbon energy-saving construction technology and the control factors of construction,summarizes the status quo of the development of building energy-saving construction,and puts forward strategies for applying building energy-saving construction technology.These strategies serve to achieve low-carbon and energy-saving goals to promote the healthy development of energy-saving construction.展开更多
The conventional process of building construction is associated with issues such as the waste of construction materials and environmental pollution.Sustainable development highlights the importance of energy conservat...The conventional process of building construction is associated with issues such as the waste of construction materials and environmental pollution.Sustainable development highlights the importance of energy conservation and eco-friendly practices.It is essential to use energy-efficient and green materials in building designs to ensure the healthy growth of construction companies.This article discusses the advantages and principles of incorporating energy-saving materials in architectural design.It examines the strategies and critical control points for using energy-saving materials in architectural design,offering guidance for the sustainable development of the construction industry.展开更多
Green energy conservation is the mainstream trend in the current development of the construction industry.The application of energy-saving technology in building electrical system design can effectively reduce energy ...Green energy conservation is the mainstream trend in the current development of the construction industry.The application of energy-saving technology in building electrical system design can effectively reduce energy consumption,avoid unnecessary energy consumption,and truly achieve energy conservation and environmental protection.Based on this,the article elaborates on the principles of energy-saving design in building electrical systems,and actively explores the application of energy-saving technologies from different perspectives such as optimizing power supply and distribution system design,adopting high-efficiency energy-saving lighting equipment,applying renewable energy,promoting smart home technology,and improving the efficiency of building electrical equipment.展开更多
The current research of abrasive belt grinding rail mainly focuses on the contact mechanism and structural design.Compared with the closed structure abrasive belt grinding,open-structured abrasive belt grinding has ex...The current research of abrasive belt grinding rail mainly focuses on the contact mechanism and structural design.Compared with the closed structure abrasive belt grinding,open-structured abrasive belt grinding has excellent performance in dynamic stability,consistency of grinding quality,extension of grinding mileage and improvement of working efficiency.However,in the contact structure design,the open-structured abrasive belt grinding rail using a profiling pressure grinding plate and the closed structure abrasive belt using the contact wheel are different,and the contact mechanisms of the two are different.In this paper,based on the conformal contact and Hertz theory,the contact mechanism of the pressure grinding plate,abrasive belt and rail is analyzed.Through finite element simulation and static pressure experiment,the contact behavior of pressure grinding plate,abrasive belt and rail under single concentrated force,uniform force and multiple concentrated force was studied,and the distribution characteristics of contact stress on rail surface were observed.The results show that under the same external load,there are three contact areas under the three loading modes.The outer contour of the middle contact area is rectangular,and the inner contour is elliptical.In the contact area at both ends,the stress is extremely small under a single concentrated force,the internal stress is drop-shaped under a uniform force,and the internal stress under multiple concentration forces is elliptical.Compared with the three,the maximum stress is the smallest and the stress distribution is more uniform under multiple concentrated forces.Therefore,the multiple concentrated forces is the best grinding pressure loading mode.The research provides support for the application of rail grinding with open-structured abrasive belt based on pressure grinding plate,such as contact mechanism and grinding pressure mode selection.展开更多
Currently,light-transmitting,energy-saving,and electromagnetic shielding materials are essential for reducing indoor energy consumption and improving the electromagnetic environment.Here,we developed a cellulose compo...Currently,light-transmitting,energy-saving,and electromagnetic shielding materials are essential for reducing indoor energy consumption and improving the electromagnetic environment.Here,we developed a cellulose composite with excellent optical transmittance that retained the natural shape and fiber structure of bamboo.The modified whole bamboo possessed an impressive optical transmittance of approximately 60%at 6.23 mm,illuminance of 1000 luminance(lux),water absorption stability(mass change rate less than 4%),longitudinal tensile strength(46.40 MPa),and surface properties(80.2 HD).These were attributed to not only the retention of the natural circular hollow structure of the bamboo rod on the macro,but also the complete bamboo fiber skeleton template impregnated with UV resin on the micro.Moreover,a multilayered device consisting of translucent whole bamboo,transparent bamboo sheets,and electromagnetic shielding film exhibited remarkable heat insulation and heat preservation performance as well as an electromagnetic shielding performance of 46.3 dB.The impressive optical transmittance,mechanical properties,thermal performance,and electromagnetic shielding abilities combined with the renewable and sustainable nature,as well as the fast and efficient manufacturing process,make this bamboo composite material suitable for effective application in transparent,energy-saving,and electromagnetic shielding buildings.展开更多
Grinding is a crucial process in machining workpieces because it plays a vital role in achieving the desired precision and surface quality.However,a significant technical challenge in grinding is the potential increas...Grinding is a crucial process in machining workpieces because it plays a vital role in achieving the desired precision and surface quality.However,a significant technical challenge in grinding is the potential increase in temperature due to high specific energy,which can lead to surface thermal damage.Therefore,ensuring control over the surface integrity of workpieces during grinding becomes a critical concern.This necessitates the development of temperature field models that consider various parameters,such as workpiece materials,grinding wheels,grinding parameters,cooling methods,and media,to guide industrial production.This study thoroughly analyzes and summarizes grinding temperature field models.First,the theory of the grinding temperature field is investigated,classifying it into traditional models based on a continuous belt heat source and those based on a discrete heat source,depending on whether the heat source is uniform and continuous.Through this examination,a more accurate grinding temperature model that closely aligns with practical grinding conditions is derived.Subsequently,various grinding thermal models are summarized,including models for the heat source distribution,energy distribution proportional coefficient,and convective heat transfer coefficient.Through comprehensive research,the most widely recognized,utilized,and accurate model for each category is identified.The application of these grinding thermal models is reviewed,shedding light on the governing laws that dictate the influence of the heat source distribution,heat distribution,and convective heat transfer in the grinding arc zone on the grinding temperature field.Finally,considering the current issues in the field of grinding temperature,potential future research directions are proposed.The aim of this study is to provide theoretical guidance and technical support for predicting workpiece temperature and improving surface integrity.展开更多
Graphene has superhigh thermal conductivity up to 5000 W/(m·K),extremely thin thickness,superhigh mechanical strength and nano-lamellar structure with low interlayer shear strength,making it possess great potenti...Graphene has superhigh thermal conductivity up to 5000 W/(m·K),extremely thin thickness,superhigh mechanical strength and nano-lamellar structure with low interlayer shear strength,making it possess great potential in mini-mum quantity lubrication(MQL)grinding.Meanwhile,ionic liquids(ILs)have higher thermal conductivity and better thermal stability than vegetable oils,which are frequently used as MQL grinding fluids.And ILs have extremely low vapor pressure,thereby avoiding film boiling in grinding.These excellent properties make ILs also have immense potential in MQL grinding.However,the grinding performance of graphene and ionic liquid mixed fluid under nano-fluid minimum quantity lubrication(NMQL),and its tribological mechanism on abrasive grain/workpiece grinding interface,are still unclear.This research firstly evaluates the grinding performance of graphene and ionic liquid mixed nanofluids(graphene/IL nanofluids)under NMQL experimentally.The evaluation shows that graphene/IL nanofluids can further strengthen both the cooling and lubricating performances compared with MQL grinding using ILs only.The specific grinding energy and grinding force ratio can be reduced by over 40%at grinding depth of 10μm.Work-piece machined surface roughness can be decreased by over 10%,and grinding temperature can be lowered over 50℃at grinding depth of 30μm.Aiming at the unclear tribological mechanism of graphene/IL nanofluids,molecular dynamics simulations for abrasive grain/workpiece grinding interface are performed to explore the formation mechanism of physical adsorption film.The simulations show that the grinding interface is in a boundary lubrication state.IL molecules absorb in groove-like fractures on grain wear flat face to form boundary lubrication film,and graphene nanosheets can enter into the grinding interface to further decrease the contact area between abrasive grain and workpiece.Compared with MQL grinding,the average tangential grinding force of graphene/IL nanofluids can decrease up to 10.8%.The interlayer shear effect and low interlayer shear strength of graphene nanosheets are the principal causes of enhanced lubricating performance on the grinding interface.EDS and XPS analyses are further carried out to explore the formation mechanism of chemical reaction film.The analyses show that IL base fluid happens chemical reactions with workpiece material,producing FeF_(2),CrF_(3),and BN.The fresh machined surface of workpiece is oxidized by air,producing NiO,Cr_(2)O_(3) and Fe_(2)O_(3).The chemical reaction film is constituted by fluorides,nitrides and oxides together.The combined action of physical adsorption film and chemical reaction film make graphene/IL nano-fluids obtain excellent grinding performance.展开更多
The structure of the all-d-metal alloy Ni_(50-x)Co_(x)Mn_(25)V_(25)(x=0–50)is investigated by using theoretical and experimental methods.The first-principles calculations indicate that the most stable structure of th...The structure of the all-d-metal alloy Ni_(50-x)Co_(x)Mn_(25)V_(25)(x=0–50)is investigated by using theoretical and experimental methods.The first-principles calculations indicate that the most stable structure of the Ni_2MnV alloy is face-centered cubic (fcc)type structure with ferrimagnetic state and the equilibrium lattice constant is 3.60A,which is in agreement with the experimental result.It is remarkable that replacing partial Ni with Co can turn the alloy from the fcc structure to the B2-type Heusler structure as Co content x>37 by using the melting spinning method,implying that the d–d hybridization between Co/Mn elements and low-valent elements V stabilizes the Heusler structure.The Curie temperature T_(C) of all-dmetal Heuser alloy Ni_(50-x)Co_(x)Mn_(25)V_(25)(x>37)increases almost linearly with the increase of Co due to that the interaction of Co–Mn is stronger than that of Ni–Mn.A magnetic transition from ferromagnetic state to weak magnetic state accompanying with grinding stress induced transformation from B2 to the dual-phase of B2 and fcc has been observed in these all-d-metal Heusler alloys.This phase transformation and magnetic change provide a guide to overcome the brittleness and make the all-d-metal Heusler alloy interesting in stress and magnetic driving structural transition.展开更多
The grinding and classification process is one of the key sub-processes in mineral processing, which influences the final process indexes significantly and determines energy and ball consumption of the whole plant. Th...The grinding and classification process is one of the key sub-processes in mineral processing, which influences the final process indexes significantly and determines energy and ball consumption of the whole plant. Therefore, optimal control of the process has been very important in practice. In order to stabilize the grinding index and improve grinding capacity in the process,a process model based on population balance model(PBM) is calibrated in this study. The correlation between the mill power and the operating variables in the grinding process is modelled by using the response surface method(RSM), which solves the problem where the traditional power modeling method relies on some unobservable mechanism-related parameters. On this basis, a multi-objective optimization model is established to maximize the useful power of the grinding circuit to improve the throughput of the grinding operation and improve the fraction of –0.074 mm particles in the hydrocyclone overflow to smooth the subsequent flotation operation. The elite non-dominated sorting genetic algorithm-II(NSGA-II) is then employed to solve the multi-objective optimization problem. Finally, subjective and objective weighting methods and integrated multi-attribute decision-making methods are used to select the optimal solution on the Pareto optimal solution set. The results demonstrate that the throughput of the mill and the fraction of –0.074 mm particles in the overflow of the cyclone are increased by 3.83 t/h and 2.53%, respectively.展开更多
Utilizing the hydrazine-assisted water electrolysis for energy-efficient hydrogen production shows a promising application, which relies on the development and design of efficient bifunctional electrocatalysts. Herein...Utilizing the hydrazine-assisted water electrolysis for energy-efficient hydrogen production shows a promising application, which relies on the development and design of efficient bifunctional electrocatalysts. Herein, we reported a low-content Pt-doped Rh metallene(Pt-Rhene) for hydrazine-assisted water electrolysis towards energy-saving hydrogen(H_(2)) production, where the ultrathin metallene is constructed to provide enough favorable active sites for catalysis and improve atom utilization.Additionally, the synergistic effect between Rh and Pt can optimize the electronic structure of Rh for improving the intrinsic activity. Therefore, the required overpotential of Pt-Rhene is only 37 mV to reach a current density of-10 mA cm^(-2) in the hydrogen evolution reaction(HER), and the Pt-Rhene exhibits a required overpotential of only 11 mV to reach a current density of 10 mA cm^(-2) in the hydrazine oxidation reaction(HzOR). With the constructed HER-HzOR two-electrode system, the Pt-Rhene electrodes exhibit an extremely low voltage(0.06/0.19/0.28 V) to achieve current densities of 10/50/100 mA cm^(-2) for energy-saving H_(2) production, which greatly reduces the electrolysis energy consumption. Moreover,DFT calculations further demonstrate that the introduction of Pt modulates the electronic structure of Rh and optimizes the d-band center, thus enhancing the adsorption and desorption of reactant/intermediates in the electrocatalytic reaction.展开更多
Micro-grinding with a spherical grinding head has been deemed an indispensable method in high-risk surgeries, such as neurosurgery and spine surgery, where bone grinding has long been plagued by the technical bottlene...Micro-grinding with a spherical grinding head has been deemed an indispensable method in high-risk surgeries, such as neurosurgery and spine surgery, where bone grinding has long been plagued by the technical bottleneck of mechanical stress-induced crack damage. In response to this challenge, the ultrasound-assisted biological bone micro-grinding novel process with a spherical grinding head has been proposed by researchers. Force modeling is a prerequisite for process parameter determination in orthopedic surgery, and the difculty in establishing and accurately predicting bone micro-grinding force prediction models is due to the geometric distribution of abrasive grains and the dynamic changes in geometry and kinematics during the cutting process. In addressing these critical needs and technical problems, the shape and protrusion heights of the wear particle of the spherical grinding head were frst studied, and the gradual rule of the contact arc length under the action of high-speed rotating ultrasonic vibration was proposed. Second, the mathematical model of the maximum thickness of undeformed chips under ultrasonic vibration of the spherical grinding head was established. Results showed that ultrasonic vibration can reduce the maximum thickness of undeformed chips and increase the range of ductile and bone meal removals, revealing the mechanism of reducing grinding force. Further, the dynamic grinding behavior of diferent layers of abrasive particles under diferent instantaneous interaction states was studied. Finally, a prediction model of micro-grinding force was established in accordance with the relationship between grinding force and cutting depth, revealing the mechanism of micro-grinding force transfer under ultrasonic vibration. The theoretical model’s average deviations are 10.37% in x-axis direction, 6.85% in y-axis direction, and 7.81% in z-axis direction compared with the experimental results. This study provides theoretical guidance and technical support for clinical bone micro-grinding.展开更多
文摘Minimum quantity Lubrication(MQL)is a sustainable lubrication system that is famous in many machining systems.It involve the spray of an infinitesimal amount of mist-like lubricants during machining processes.The MQL system is affirmed to exhibit an excellent machining performance,and it is highly economical.The nanofluids are understood to exhibit excellent lubricity and heat evacuation capability,compared to pure oil-based MQL system.Studies have shown that the surface quality and amount of energy expended in the grinding operations can be reduced considerably due to the positive effect of these nanofluids.This work presents an experimental study on the tribological performance of SiO_(2)nanofluid during grinding of Si_(3)N_(4)ceramic.The effect different grinding modes and lubrication systems during the grinding operation was also analyzed.Different concentrations of the SiO_(2)nanofluid was manufactured using canola,corn and sunflower oils.The quantitative evaluation of the grinding process was done based on the amount of grinding forces,specific grinding energy,frictional coefficient,and surface integrity.It was found that the canola oil exhibits optimal lubrication performance compared to corn oil,sunflower oil,and traditional lubrication systems.Additionally,the introduction of ultrasonic vibrations with the SiO_(2)nanofluid in MQL system was found to reduce the specific grinding energy,normal grinding forces,tangential grinding forces,and surface roughness by 65%,57%,65%,and 18%respectively.Finally,regression analysis was used to obtain an optimum parameter combinations.The observations from this work will aid the smooth transition towards ecofriendly and sustainable machining of engineering ceramics.
基金supported by the National Natural Science Foundation of China(52375420,52005134 and51675453)Natural Science Foundation of Heilongjiang Province of China(YQ2023E014)+5 种基金Self-Planned Task(No.SKLRS202214B)of State Key Laboratory of Robotics and System(HIT)China Postdoctoral Science Foundation(2022T150163)Young Elite Scientists Sponsorship Program by CAST(No.YESS20220463)State Key Laboratory of Robotics and System(HIT)(SKLRS-2022-ZM-14)Open Fund of Key Laboratory of Microsystems and Microstructures Manufacturing(HIT)(2022KM004)Fundamental Research Funds for the Central Universities(Grant Nos.HIT.OCEF.2022024 and FRFCU5710051122)。
文摘Elucidating the complex interactions between the work material and abrasives during grinding of gallium nitride(GaN)single crystals is an active and challenging research area.In this study,molecular dynamics simulations were performed on double-grits interacted grinding of GaN crystals;and the grinding force,coefficient of friction,stress distribution,plastic damage behaviors,and abrasive damage were systematically investigated.The results demonstrated that the interacted distance in both radial and transverse directions achieved better grinding quality than that in only one direction.The grinding force,grinding induced stress,subsurface damage depth,and abrasive wear increase as the transverse interacted distance increases.However,there was no clear correlation between the interaction distance and the number of atoms in the phase transition and dislocation length.Appropriate interacted distances between abrasives can decrease grinding force,coefficient of friction,grinding induced stress,subsurface damage depth,and abrasive wear during the grinding process.The results of grinding tests combined with cross-sectional transmission electron micrographs validated the simulated damage results,i.e.amorphous atoms,high-pressure phase transition,dislocations,stacking faults,and lattice distortions.The results of this study will deepen our understanding of damage accumulation and material removal resulting from coupling between abrasives during grinding and can be used to develop a feasible approach to the wheel design of ordered abrasives.
基金Supported by National Natural Science Foundation of China(Nos.52205476,92160301)Youth Talent Support Project of Jiangsu Provincial Association of Science and Technology of China(Grant No.TJ-2023-070)+2 种基金Science Center for Gas Turbine Project(Grant No.P2023-B-IV-003-001)Fund of Prospective Layout of Scientific Research for the Nanjing University of Aeronautics and Astronautics of China(Grant No.1005-ILB23025-1A)Fund of Jiangsu Key Laboratory of Precision and Micro-Manufacturing Technology of China(Grant No.1005-ZAA20003-14).
文摘Grinding,a critical precision machining process for difficult-to-cut alloys,has undergone continual technological advancements to improve machining efficiency.However,the sustainability of this process is gaining heightened attention due to significant challenges associated with the substantial specific grinding energy and the extensive heat generated when working with difficult-to-cut alloys,renowned for their exceptional physical and mechanical properties.In response to these challenges,the widespread application of massive coolant in manufacturing industries to dissipate grinding heat has led to complex post-cleaning and disposal processes.This,in turn,has resulted in issues such as large energy consumption,a considerable carbon footprint,and concerns related to worker health and safety,which have become the main factors that restrict the development of grinding technology.This paper provides a holistic review of sustainability in grinding difficult-to-cut alloys,encompassing current trends and future directions.The examination extends to developing grinding technologies explicitly tailored for these alloys,comprehensively evaluating their sustainability performance.Additionally,the exploration delves into innovative sustainable technologies,such as heat pipe/oscillating heat pipe grinding wheels,minimum quantity lubrication,cryogenic cooling,and others.These groundbreaking technologies aim to reduce dependence on hazardous coolants,minimizing energy and resource consumption and carbon emissions associated with coolant-related or subsequent disposal processes.The essence of these technologies lies in their potential to revolutionize traditional grinding practices,presenting environmentally friendly alternatives.Finally,future development trends and research directions are put forward to pursue the current limitation of sustainable grinding for difficult-to-cut alloys.This paper can guide future research and development efforts toward more environmentally friendly grinding operations by understanding the current state of sustainable grinding and identifying emerging trends.
基金Supported by the Scientific Research Fund of Hunan Provincial Education Department(21A048)Graduate Student Research Innovation Project of Shaoyang University(CX2022SY080)Transverse project of Shaoyang University(2023HX37,2023HX43)。
文摘[Objectives] This study was conducted to improve the nutritional value of soybean milk, enrich the variety and taste of soybean milk, and find healthy food that is more conducive to people s nutritional needs. [Methods] Whole soybean milk was prepared by grinding with a grinding wheel at a low concentration (low-concentration grinding) and a stainless steel mill at a high concentration (high-concentration grinding). The sensory, physical and chemical characteristics and anti-nutritional factors of whole soybean milk produced by different grinding methods were studied. [Results] Compared with low-concentration grinding, the protein content in soybean milk prepared by high-concentration grinding increased by 24%, and the dietary fiber content increased by 74.7%. Before and after high-pressure homogenization, the particle size D(4, 3) of soybean milk prepared by low-concentration grinding was 212.1 and 93.59 μm, respectively, and the particle size D(4, 3) of soybean milk prepared by high-concentration grinding was 134.0 and 64.64 μm, respectively. The trypsin inhibitor activity and phytic acid content of soybean milk prepared by high-concentration grinding were significantly lower than those of soybean milk prepared by low-concentration grinding. [Conclusions] This study improves the diet structure of the broad masses of people, strengthens people s physique, and provides a new idea for the implementation and development of China s "Soybean Action Programme".
基金support from the National Science Fund of China(52325506)the National Science and Technology Major Project(2017-VII-0002-0095)Fundamental Research Funds for the Central Universities(DUT22LAB501)。
文摘Fatigue properties are crucial for critical aero-engine components in extreme serviceenvironments,which are significantly affected by surface integrity(SI)indexes(especially surface topography,residual stressσ_(res),and microhardness)after machining processes.Normal-direction ultrasonic vibration-assisted face grinding(ND-UVAFG)has advantages in improving the machinability of Inconel 718,but there is a competitive relationship between higher compressiveσ_(res)and higher surface roughness R_(a)in affecting fatigue strength.The lack of a quantitative relationship between multiple SI indexes and fatigue strength makes theindeterminacy of a regulatory strategy for improving fatigue properties.In this work,a model of fatigue strength(σ_f)_(sur)considering multiple SI indexes was developed.Then,high-cycle fatigue tests were carried out on Inconel 718 samples with different SI characteristics,and the influence of ND-UVAFG process parameters on SI was analyzed.Based on SI indexes data,the(σ_f)_(sur)distribution in the grinding surface layer for ND-UVAFG Inconel 718 samples was determined using the developed model,and then the fatigue crack initiation(FCI)sites were furtherpredicted.The predicted FCI sites corresponded well with the experimental results,therebyverifying this model.A strategy for improving the fatigue life was proposed in this work,which was to transfer the fatigue source from the machined surface to the bulk material by controlling the SI indexes.Finally,a critical condition of SI indexes that FCI sites appeared on the surface or in bulk material was given by fitting the predicted results.According to the critical condition,an SI field where FCI sites appeared in the bulk material could be obtained.In this field,thefatigue life of Inconel 718 samples could be improved by approximately 140%.
基金supported by the National Natural Science Foundation of China(Grant Nos.92060203,52105453,and 92360304)the Science Center for Gas Turbine Project(No.P2022-A-IV-002-001).
文摘Ceramic matrix composites(CMCs)are highly promising materials for the next generation of aero-engines.However,machining of CMCs suffers from low efficiency and poor surfacefinish,which presents an obstacle to their wider application.To overcome these problems,this study investigates high-efficiency deep grinding of CMCs,focusing on the effects of grinding depth.The results show that both the sur-face roughness and the depth of subsurface damage(SSD)are insensitive to grinding depth.The material removal rate can be increased sixfold by increasing the grinding depth,while the surface roughness and SSD depth increase by only about 10%.Moreover,it is found that the behavior of material removal is strongly dependent on grinding depth.As the grinding depth is increased,fibers are removed in smaller sizes,with thefiber length in chips being reduced by about 34%.However,too large a grinding depth will result in blockage by chip powder,which leads to a dramatic increase in the ratio of tangential to normal grinding forces.This study demonstrates that increasing the depth of cut is an effective approach to improve the machining efficiency of CMCs,while maintaining a good surfacefin-ish.It provides the basis for the further development of high-performance grinding methods for CMCs,which should facilitate their wider application.
基金supported by the Natural Science Foundation of Anhui Province(Grant Number 2208085MG181)the Science Research Project of Higher Education Institutions in Anhui Province,Philosophy and Social Sciences(Grant Number 2023AH051063)the Open Fund of Key Laboratory of Anhui Higher Education Institutes(Grant Number CS2021-ZD01).
文摘The distributed flexible job shop scheduling problem(DFJSP)has attracted great attention with the growth of the global manufacturing industry.General DFJSP research only considers machine constraints and ignores worker constraints.As one critical factor of production,effective utilization of worker resources can increase productivity.Meanwhile,energy consumption is a growing concern due to the increasingly serious environmental issues.Therefore,the distributed flexible job shop scheduling problem with dual resource constraints(DFJSP-DRC)for minimizing makespan and total energy consumption is studied in this paper.To solve the problem,we present a multi-objective mathematical model for DFJSP-DRC and propose a Q-learning-based multi-objective grey wolf optimizer(Q-MOGWO).In Q-MOGWO,high-quality initial solutions are generated by a hybrid initialization strategy,and an improved active decoding strategy is designed to obtain the scheduling schemes.To further enhance the local search capability and expand the solution space,two wolf predation strategies and three critical factory neighborhood structures based on Q-learning are proposed.These strategies and structures enable Q-MOGWO to explore the solution space more efficiently and thus find better Pareto solutions.The effectiveness of Q-MOGWO in addressing DFJSP-DRC is verified through comparison with four algorithms using 45 instances.The results reveal that Q-MOGWO outperforms comparison algorithms in terms of solution quality.
文摘BACKGROUND Extraction of impacted third molars often leads to severe complications caused by damage to the inferior alveolar nerve(IAN).AIM To proposes a method for the partial grinding of an impacted mandibular third molar(IMM3)near the IAN to prevent IAN injury during IMM3 extraction.METHODS Between January 1996 and March 2022,25 patients with IMM3 roots near the IAN were enrolled.The first stage of the operation consisted of grinding a major part of the IMM3 crown with a high-speed turbine dental drill to achieve sufficient space between the mandibular second molar and IMM3.After 6 months,when the root tips were observed to be away from the IAN on X-ray examination,the remaining part of the IMM3 was completely removed.RESULTS All IMM3s were extracted easily without symptoms of IAN injury after extraction.CONCLUSION Partial IMM3 grinding may be a good alternative treatment option to avoid IAN injury in high-risk cases.
基金supported by the National Natural Science Foundation of China(Grant No.71872122)Late-stage Subsidy Project of Humanities and Social Sciences of the Education Department of China(Grant No.20JHQ095).
文摘The energy-saving renovation of existing residential buildings is a crucial measure to achieve the strategic goal of energy conservation and emission reduction in China and build ecologically livable cities.This article focuses on the perspective of subject behavior,starting from analyzing the current situation and difficulties of the operation of the energy-saving renovation market for existing residential buildings in China,drawing on the practical experience of the operation of the existing residential building energy-saving renovation market abroad.Based on principles such as systematicity,humanization,feasibility,and sustainability,the article constructs an operation optimization system of the existing residential building energy-saving renovation market from the perspective of subject behavior.In order to provide a reference for the healthy and orderly operation of the existing residential building energy-saving renovation market,this paper proposes implementation strategies for optimizing the operation of the existing residential building energy-saving renovation market.Suggestions are proposed from four aspects:optimizing the market environment,innovating the financing model,building the information sharing platform,and utilizing the synergies of the main subjects.
基金Research on Zero Emission Campus Construction Based on Plant Community Optimization(Project number:KJQN202305605)。
文摘The development of the construction industry is shifting towards low-carbon construction,so it is necessary to improve and optimize related construction concepts,methods,and processes.By improving resource and energy control efficiency in building projects,minimizing construction waste,and reducing environmental impact,a foundation for the sustainable development of the industry can be established.This paper mainly analyzes the significance of low-carbon energy-saving construction technology and the control factors of construction,summarizes the status quo of the development of building energy-saving construction,and puts forward strategies for applying building energy-saving construction technology.These strategies serve to achieve low-carbon and energy-saving goals to promote the healthy development of energy-saving construction.
文摘The conventional process of building construction is associated with issues such as the waste of construction materials and environmental pollution.Sustainable development highlights the importance of energy conservation and eco-friendly practices.It is essential to use energy-efficient and green materials in building designs to ensure the healthy growth of construction companies.This article discusses the advantages and principles of incorporating energy-saving materials in architectural design.It examines the strategies and critical control points for using energy-saving materials in architectural design,offering guidance for the sustainable development of the construction industry.
文摘Green energy conservation is the mainstream trend in the current development of the construction industry.The application of energy-saving technology in building electrical system design can effectively reduce energy consumption,avoid unnecessary energy consumption,and truly achieve energy conservation and environmental protection.Based on this,the article elaborates on the principles of energy-saving design in building electrical systems,and actively explores the application of energy-saving technologies from different perspectives such as optimizing power supply and distribution system design,adopting high-efficiency energy-saving lighting equipment,applying renewable energy,promoting smart home technology,and improving the efficiency of building electrical equipment.
基金Supported by Fundamental Research Funds for the Central Universities of China (Grant No.2019JBM050)。
文摘The current research of abrasive belt grinding rail mainly focuses on the contact mechanism and structural design.Compared with the closed structure abrasive belt grinding,open-structured abrasive belt grinding has excellent performance in dynamic stability,consistency of grinding quality,extension of grinding mileage and improvement of working efficiency.However,in the contact structure design,the open-structured abrasive belt grinding rail using a profiling pressure grinding plate and the closed structure abrasive belt using the contact wheel are different,and the contact mechanisms of the two are different.In this paper,based on the conformal contact and Hertz theory,the contact mechanism of the pressure grinding plate,abrasive belt and rail is analyzed.Through finite element simulation and static pressure experiment,the contact behavior of pressure grinding plate,abrasive belt and rail under single concentrated force,uniform force and multiple concentrated force was studied,and the distribution characteristics of contact stress on rail surface were observed.The results show that under the same external load,there are three contact areas under the three loading modes.The outer contour of the middle contact area is rectangular,and the inner contour is elliptical.In the contact area at both ends,the stress is extremely small under a single concentrated force,the internal stress is drop-shaped under a uniform force,and the internal stress under multiple concentration forces is elliptical.Compared with the three,the maximum stress is the smallest and the stress distribution is more uniform under multiple concentrated forces.Therefore,the multiple concentrated forces is the best grinding pressure loading mode.The research provides support for the application of rail grinding with open-structured abrasive belt based on pressure grinding plate,such as contact mechanism and grinding pressure mode selection.
基金supported by the National Natural Science Foundation of China (Nos. 32071687 and 52273247)Jiangsu Qinglan Project
文摘Currently,light-transmitting,energy-saving,and electromagnetic shielding materials are essential for reducing indoor energy consumption and improving the electromagnetic environment.Here,we developed a cellulose composite with excellent optical transmittance that retained the natural shape and fiber structure of bamboo.The modified whole bamboo possessed an impressive optical transmittance of approximately 60%at 6.23 mm,illuminance of 1000 luminance(lux),water absorption stability(mass change rate less than 4%),longitudinal tensile strength(46.40 MPa),and surface properties(80.2 HD).These were attributed to not only the retention of the natural circular hollow structure of the bamboo rod on the macro,but also the complete bamboo fiber skeleton template impregnated with UV resin on the micro.Moreover,a multilayered device consisting of translucent whole bamboo,transparent bamboo sheets,and electromagnetic shielding film exhibited remarkable heat insulation and heat preservation performance as well as an electromagnetic shielding performance of 46.3 dB.The impressive optical transmittance,mechanical properties,thermal performance,and electromagnetic shielding abilities combined with the renewable and sustainable nature,as well as the fast and efficient manufacturing process,make this bamboo composite material suitable for effective application in transparent,energy-saving,and electromagnetic shielding buildings.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.52205481,51975305 and 52105457)Shandong Natural Science Foundation(Grant Nos.ZR2020ME158,ZR2023QE057,ZR2022QE028,ZR2021QE116,ZR2020KE027,and ZR2022QE159)+1 种基金Qingdao Science and Technology Planning Park Cultivation Plan(23-1-5-yqpy-17-qy)China Postdoctral Science Foundation(2021M701810).
文摘Grinding is a crucial process in machining workpieces because it plays a vital role in achieving the desired precision and surface quality.However,a significant technical challenge in grinding is the potential increase in temperature due to high specific energy,which can lead to surface thermal damage.Therefore,ensuring control over the surface integrity of workpieces during grinding becomes a critical concern.This necessitates the development of temperature field models that consider various parameters,such as workpiece materials,grinding wheels,grinding parameters,cooling methods,and media,to guide industrial production.This study thoroughly analyzes and summarizes grinding temperature field models.First,the theory of the grinding temperature field is investigated,classifying it into traditional models based on a continuous belt heat source and those based on a discrete heat source,depending on whether the heat source is uniform and continuous.Through this examination,a more accurate grinding temperature model that closely aligns with practical grinding conditions is derived.Subsequently,various grinding thermal models are summarized,including models for the heat source distribution,energy distribution proportional coefficient,and convective heat transfer coefficient.Through comprehensive research,the most widely recognized,utilized,and accurate model for each category is identified.The application of these grinding thermal models is reviewed,shedding light on the governing laws that dictate the influence of the heat source distribution,heat distribution,and convective heat transfer in the grinding arc zone on the grinding temperature field.Finally,considering the current issues in the field of grinding temperature,potential future research directions are proposed.The aim of this study is to provide theoretical guidance and technical support for predicting workpiece temperature and improving surface integrity.
基金Supported by Shandong Provincial Natural Science Foundation of China(Grant Nos.ZR2022ME208,ZR2020QE181)National Natural Science Foundation of China(Grant Nos.51705272,52005281)+1 种基金China Postdoctoral Science Foundation(Grant No.2018M642628)111 project(Grant No.D21017).
文摘Graphene has superhigh thermal conductivity up to 5000 W/(m·K),extremely thin thickness,superhigh mechanical strength and nano-lamellar structure with low interlayer shear strength,making it possess great potential in mini-mum quantity lubrication(MQL)grinding.Meanwhile,ionic liquids(ILs)have higher thermal conductivity and better thermal stability than vegetable oils,which are frequently used as MQL grinding fluids.And ILs have extremely low vapor pressure,thereby avoiding film boiling in grinding.These excellent properties make ILs also have immense potential in MQL grinding.However,the grinding performance of graphene and ionic liquid mixed fluid under nano-fluid minimum quantity lubrication(NMQL),and its tribological mechanism on abrasive grain/workpiece grinding interface,are still unclear.This research firstly evaluates the grinding performance of graphene and ionic liquid mixed nanofluids(graphene/IL nanofluids)under NMQL experimentally.The evaluation shows that graphene/IL nanofluids can further strengthen both the cooling and lubricating performances compared with MQL grinding using ILs only.The specific grinding energy and grinding force ratio can be reduced by over 40%at grinding depth of 10μm.Work-piece machined surface roughness can be decreased by over 10%,and grinding temperature can be lowered over 50℃at grinding depth of 30μm.Aiming at the unclear tribological mechanism of graphene/IL nanofluids,molecular dynamics simulations for abrasive grain/workpiece grinding interface are performed to explore the formation mechanism of physical adsorption film.The simulations show that the grinding interface is in a boundary lubrication state.IL molecules absorb in groove-like fractures on grain wear flat face to form boundary lubrication film,and graphene nanosheets can enter into the grinding interface to further decrease the contact area between abrasive grain and workpiece.Compared with MQL grinding,the average tangential grinding force of graphene/IL nanofluids can decrease up to 10.8%.The interlayer shear effect and low interlayer shear strength of graphene nanosheets are the principal causes of enhanced lubricating performance on the grinding interface.EDS and XPS analyses are further carried out to explore the formation mechanism of chemical reaction film.The analyses show that IL base fluid happens chemical reactions with workpiece material,producing FeF_(2),CrF_(3),and BN.The fresh machined surface of workpiece is oxidized by air,producing NiO,Cr_(2)O_(3) and Fe_(2)O_(3).The chemical reaction film is constituted by fluorides,nitrides and oxides together.The combined action of physical adsorption film and chemical reaction film make graphene/IL nano-fluids obtain excellent grinding performance.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51671024 and 52088101)State Key Lab of Advanced Metals and Materials(Grant No.2019Z12)the Fundamental Research Funds for the Central Universities(Grant No.FRF-BD-20-12A)。
文摘The structure of the all-d-metal alloy Ni_(50-x)Co_(x)Mn_(25)V_(25)(x=0–50)is investigated by using theoretical and experimental methods.The first-principles calculations indicate that the most stable structure of the Ni_2MnV alloy is face-centered cubic (fcc)type structure with ferrimagnetic state and the equilibrium lattice constant is 3.60A,which is in agreement with the experimental result.It is remarkable that replacing partial Ni with Co can turn the alloy from the fcc structure to the B2-type Heusler structure as Co content x>37 by using the melting spinning method,implying that the d–d hybridization between Co/Mn elements and low-valent elements V stabilizes the Heusler structure.The Curie temperature T_(C) of all-dmetal Heuser alloy Ni_(50-x)Co_(x)Mn_(25)V_(25)(x>37)increases almost linearly with the increase of Co due to that the interaction of Co–Mn is stronger than that of Ni–Mn.A magnetic transition from ferromagnetic state to weak magnetic state accompanying with grinding stress induced transformation from B2 to the dual-phase of B2 and fcc has been observed in these all-d-metal Heusler alloys.This phase transformation and magnetic change provide a guide to overcome the brittleness and make the all-d-metal Heusler alloy interesting in stress and magnetic driving structural transition.
基金supported in part by the National Natural Science Foundation of China (62073342)the National Key Research and Development Program of China (2018YFB1701100)。
文摘The grinding and classification process is one of the key sub-processes in mineral processing, which influences the final process indexes significantly and determines energy and ball consumption of the whole plant. Therefore, optimal control of the process has been very important in practice. In order to stabilize the grinding index and improve grinding capacity in the process,a process model based on population balance model(PBM) is calibrated in this study. The correlation between the mill power and the operating variables in the grinding process is modelled by using the response surface method(RSM), which solves the problem where the traditional power modeling method relies on some unobservable mechanism-related parameters. On this basis, a multi-objective optimization model is established to maximize the useful power of the grinding circuit to improve the throughput of the grinding operation and improve the fraction of –0.074 mm particles in the hydrocyclone overflow to smooth the subsequent flotation operation. The elite non-dominated sorting genetic algorithm-II(NSGA-II) is then employed to solve the multi-objective optimization problem. Finally, subjective and objective weighting methods and integrated multi-attribute decision-making methods are used to select the optimal solution on the Pareto optimal solution set. The results demonstrate that the throughput of the mill and the fraction of –0.074 mm particles in the overflow of the cyclone are increased by 3.83 t/h and 2.53%, respectively.
基金financially supported by the National Natural Science Foundation of China (No. 21972126, 21978264, 21905250, and 22278369)the Natural Science Foundation of Zhejiang Province (No. LQ22B030012 and LQ23B030010)the China Postdoctoral Science Foundation (2021M702889)。
文摘Utilizing the hydrazine-assisted water electrolysis for energy-efficient hydrogen production shows a promising application, which relies on the development and design of efficient bifunctional electrocatalysts. Herein, we reported a low-content Pt-doped Rh metallene(Pt-Rhene) for hydrazine-assisted water electrolysis towards energy-saving hydrogen(H_(2)) production, where the ultrathin metallene is constructed to provide enough favorable active sites for catalysis and improve atom utilization.Additionally, the synergistic effect between Rh and Pt can optimize the electronic structure of Rh for improving the intrinsic activity. Therefore, the required overpotential of Pt-Rhene is only 37 mV to reach a current density of-10 mA cm^(-2) in the hydrogen evolution reaction(HER), and the Pt-Rhene exhibits a required overpotential of only 11 mV to reach a current density of 10 mA cm^(-2) in the hydrazine oxidation reaction(HzOR). With the constructed HER-HzOR two-electrode system, the Pt-Rhene electrodes exhibit an extremely low voltage(0.06/0.19/0.28 V) to achieve current densities of 10/50/100 mA cm^(-2) for energy-saving H_(2) production, which greatly reduces the electrolysis energy consumption. Moreover,DFT calculations further demonstrate that the introduction of Pt modulates the electronic structure of Rh and optimizes the d-band center, thus enhancing the adsorption and desorption of reactant/intermediates in the electrocatalytic reaction.
基金Supported by National Natural Science Foundation of China(Grant Nos.51975305,52105457,and 52205481)the Special Fund of Taishan Scholars Project(Grant No.tsqn202211179)+1 种基金Shandong Provincial Youth Talent Promotion Project(Grant No.SDAST2021qt12)Shandong Provincial Natural Science Foundation(Grant Nos.ZR2023QE057,ZR2022QE028,ZR2021QE116,and ZR2020KE027).
文摘Micro-grinding with a spherical grinding head has been deemed an indispensable method in high-risk surgeries, such as neurosurgery and spine surgery, where bone grinding has long been plagued by the technical bottleneck of mechanical stress-induced crack damage. In response to this challenge, the ultrasound-assisted biological bone micro-grinding novel process with a spherical grinding head has been proposed by researchers. Force modeling is a prerequisite for process parameter determination in orthopedic surgery, and the difculty in establishing and accurately predicting bone micro-grinding force prediction models is due to the geometric distribution of abrasive grains and the dynamic changes in geometry and kinematics during the cutting process. In addressing these critical needs and technical problems, the shape and protrusion heights of the wear particle of the spherical grinding head were frst studied, and the gradual rule of the contact arc length under the action of high-speed rotating ultrasonic vibration was proposed. Second, the mathematical model of the maximum thickness of undeformed chips under ultrasonic vibration of the spherical grinding head was established. Results showed that ultrasonic vibration can reduce the maximum thickness of undeformed chips and increase the range of ductile and bone meal removals, revealing the mechanism of reducing grinding force. Further, the dynamic grinding behavior of diferent layers of abrasive particles under diferent instantaneous interaction states was studied. Finally, a prediction model of micro-grinding force was established in accordance with the relationship between grinding force and cutting depth, revealing the mechanism of micro-grinding force transfer under ultrasonic vibration. The theoretical model’s average deviations are 10.37% in x-axis direction, 6.85% in y-axis direction, and 7.81% in z-axis direction compared with the experimental results. This study provides theoretical guidance and technical support for clinical bone micro-grinding.