This paper explains how the optimized classrooms were selected and the results that were achieved by the optimizations carried out and finalized.The context of the research is the city of Concepción,in Chile.Virt...This paper explains how the optimized classrooms were selected and the results that were achieved by the optimizations carried out and finalized.The context of the research is the city of Concepción,in Chile.Virtual models of classrooms were evaluated using the Radiance software.We used a methodology that allowed us to determine the luminous conditions under different types of skies,seasons of the year and times of the day.The evaluation of the typologies was performed based on three defined criteria,in order to achieve the stated design objectives.We defined the optimal solutions for each orientation and,finally,we stated design recommendations for daylit classrooms to ensure the visual comfort of the students.These recommendations link all that found in the initial analysis with that found in the optimization stage.展开更多
Regional design is the design method based on the geographical characteristics, and the natural environment is basic factors. This paper puts forward to the regional product design thought patterns and makes some brie...Regional design is the design method based on the geographical characteristics, and the natural environment is basic factors. This paper puts forward to the regional product design thought patterns and makes some brief comments on its value and social significance of the design, in a long run, with exploratory guiding significance.展开更多
Micro diamond tools are indispensable for the efficient machining of microstructured surfaces.The precision in tool manufacturing and cutting performance directly determines the processing quality of components.The ma...Micro diamond tools are indispensable for the efficient machining of microstructured surfaces.The precision in tool manufacturing and cutting performance directly determines the processing quality of components.The manufacturing of high-quality micro diamond tools relies on scientific design methods and appropriate processing techniques.However,there is currently a lack of systematic review on the design and manufacturing methods of micro diamond tools in academia.This study systematically summarizes and analyzes modern manufacturing methods for micro diamond tools,as well as the impact of tool waviness,sharpness,and durability on machining quality.Subsequently,a design method is proposed based on the theory of cutting edge strength distribution to enhance tool waviness,sharpness,and durability.Finally,this paper presents current technical challenges faced by micro diamond tools along with potential future solutions to guide scientists in this field.The aim of this review is to contribute to the further development of the current design and manufacturing processes for micro diamond cutting tools.展开更多
Background and Aim:Despite their flaws,the low-cost but powerful economical solutions can ensure everyone has access to health.The main aim of this study is to extract characteristics of frugal innovation(FI)and socia...Background and Aim:Despite their flaws,the low-cost but powerful economical solutions can ensure everyone has access to health.The main aim of this study is to extract characteristics of frugal innovation(FI)and social innovation(SI)for Primary Health Centers(PHCs)in low resource settings(LRS)for sustainable development.We will use the gained insights to design the mobile primary healthcare infrastructure using FI and SI strategies.There is a lack of methodology to design sustainable healthcare infrastructure for LRS.There is a gap in the literature about building sustainable infrastructure to provide basic healthcare facilities essential to the community.This article studies several factors necessary for designing sustainable infrastructure from the lens of FI,SI,and sustainability to develop a mobile healthcare infrastructure for last-mile people.Methods:Started with purposive sampled case studies to find out factors and criteria that most affect the success for an innovation to be frugal,social,and sustainable.The established criteria were used to design,develop,and deploy the mobile Primary Health Center(mPHC).Moving forward,we tested the system designed with stakeholders to gather insights.At this stage we found the feedback loop from the stakeholders and the role of interdisciplinary discussions between experts,medical officers,nurses,patient,and other staff of PHCs during the design,development,deployment,and test stage to be useful in taking design decisions efficiently.Results:The designed healthcare infrastructure of mPHC through the aspects of FI and SI proves to be efficient in providing key healthcare services to LRS.Conclusion:Focusing on essential capabilities and optimizing performance with technology,methodologies,and processes reduces costs in an innovation.Focus on socially inclusive and rebalancing power disparities,overcome societal challenges and improve human capabilities will create a sustainable and novel solution.展开更多
This study investigates the traction performance and efficiency of a conical friction continuously variable trans-mission.A new mathematical model was developed and validated through experimental measurements using a ...This study investigates the traction performance and efficiency of a conical friction continuously variable trans-mission.A new mathematical model was developed and validated through experimental measurements using a custom-built test rig to predict these parameters accurately.The results showed a close correlation between the-oretical predictions and experimental data.Key findings include the impact of load on efficiency and the model’s ability to predict performance under various operating conditions.The study provides detailed insights into the dynamics of conical friction variator and demonstrates the model’s effectiveness in predicting real-world behav-ior.The developed model can assist in selecting optimal parameters during the design phase and can be applied to other developing variator systems to achieve maximum efficiency.展开更多
Leveraging surface texturing to realize significant friction reduction at contact interfaces has emerged as a preferred technique among tribology experts,boosting tribological energy efficiency and sustainability.This...Leveraging surface texturing to realize significant friction reduction at contact interfaces has emerged as a preferred technique among tribology experts,boosting tribological energy efficiency and sustainability.This review systematically demonstrates optimization strategies,advanced manufacturing methods,typical applications,and outlooks of technical challenges toward surface texturing for friction reduction.Firstly,the lubricated contact models of microtextures are introduced.Then,we provide a framework of state-of-the-art research on synergistic friction optimization strategies of microtexture structures,surface treatments,liquid lubricants,and external energy fields.A comparative analysis evaluates the strengths and weaknesses of manufacturing techniques commonly employed for microtextured surfaces.The latest research advancements in microtextures in different application scenarios are highlighted.Finally,the challenges and directions of future research on surface texturing technology are briefly addressed.This review aims to elaborate on the worldwide progress in the optimization,manufacturing,and application of microtexture-enabled friction reduction technologies to promote their practical utilizations.展开更多
The mineralogical characteristics of tantalumniobium ores from Songzi were investigated using mineral liberation analyzer （MLA） and chemical analysis. In particular, the chemical composition, phase composition, part...The mineralogical characteristics of tantalumniobium ores from Songzi were investigated using mineral liberation analyzer （MLA） and chemical analysis. In particular, the chemical composition, phase composition, particle size, and dissemination characteristics of the ores were studied in detail. Results show that Ta2O5 and Nb2O5 have grades of 0.013 % and 0.011%, respectively. The main valuable minerals in the ores are tantalite, col- umbite, tantalum-niobite, and microlite, and the gangue minerals associated with tantalum-niobium minerals mainly include quartz, kaolinite, illite, feldspar, and mica among others. The minerals are embedded in a complex manner. Tantalum-niobium minerals with most particle sizes of -0.040 mm are disseminated in minerals, such as mica, illite, quartz, and partially intergrown with topaz and zircon, where they could not be easily liberated. Thus, the ores are classified as low-grade, micro-fine, and refractory tantalum-niobium ores. Based on this consideration, the process of classification-gravity concentration-magnetic separation-middlings regrinding and gravity concentration are finally determined and satisfactory indices are obtained. Two rough concentrates are produced： Concentrate I has Ta2O5 and Nb2O5 grades of 7.0292 % and 3.546 %, respectively, as well as recovery of 49.42 % and 35.46 %. By comparison, Concentrate Ⅱ has Ta2O5 and Nb2O5 grades of 7.0292 % and 3.546 %, respectively, as well as recovery of 49.42 % and 35.46 %.展开更多
Rechargeable zinc-air batteries(ZABs)are a promising energy conversion device,which rely critically on electrocatalysts to accelerate their rate-determining reactions such as oxygen reduction(ORR)and oxygen evolution ...Rechargeable zinc-air batteries(ZABs)are a promising energy conversion device,which rely critically on electrocatalysts to accelerate their rate-determining reactions such as oxygen reduction(ORR)and oxygen evolution reactions(OER).Herein,we fabricate a range of bifunctional M-N-C(metal-nitrogen-carbon)catalysts containing M-Nx coordination sites and M/MxC nanoparticles(M=Co,Fe,and Cu)using a new class ofγ-cyclodextrin(CD)based metal-organic framework as the precursor.With the two types of active sites interacting with each other in the catalysts,the obtained Fe@C-FeNC and Co@C-CoNC display superior alkaline ORR activity in terms of low half-wave(E1/2)potential(~0.917 and 0.906 V,respectively),which are higher than Cu@C-CuNC(~0.829 V)and the commercial Pt/C(~0.861 V).As a bifunctional electrocatalyst,the Co@C-CoNC exhibits the best performance,showing a bifunctional ORR/OER overpotential(ΔE)of~0.732 V,which is much lower than that of Fe@C-FeNC(~0.831 V)and Cu@C-CuNC(~1.411 V),as well as most of the robust bifunctional electrocatalysts reported to date.Synchrotron X-ray absorption spectroscopy and density functional theory simulations reveal that the strong electronic correlation between metallic Co nanoparticles and the atomic Co-N4 sites in the Co@C-CoNC catalyst can increase the d-electron density near the Fermi level and thus effectively optimize the adsorption/desorption of intermediates in ORR/OER,resulting in an enhanced bifunctional electrocatalytic performance.The Co@C-CoNC-based rechargeable ZAB exhibited a maximum power density of 162.80 mW cm^(−2) at 270.30 mA cm^(−2),higher than the combination of commercial Pt/C+RuO2(~158.90 mW cm^(−2) at 265.80 mA cm^(−2))catalysts.During the galvanostatic discharge at 10 mA cm^(−2),the ZAB delivered an almost stable discharge voltage of 1.2 V for~140 h,signifying the virtue of excellent bifunctional ORR/OER electrocatalytic activity.展开更多
A motorized spindle supported by active magnetic bearings（AMBs） is generally used for ultra-high-speed machining. Iron loss of radial AMB is very great owing to high rotation speed, and it will cause severe thermal ...A motorized spindle supported by active magnetic bearings（AMBs） is generally used for ultra-high-speed machining. Iron loss of radial AMB is very great owing to high rotation speed, and it will cause severe thermal deformation. The problem is particularly serious on the occasion of large power application, such as all electric aero-engine. In this study, a prototype motorized spindle supported by five degree-of-freedom AMBs is developed. Homopolar and heteropolar AMBs are independently adopted as radial bearings. The influences of the two types of radial AMBs on the dynamic characteristics of the motorized spindle are comparatively investigated by theoretical analysis, test modal analysis and actual operation of the system. The iron loss of the two types of radial AMBs is analyzed by finite element software and verified through run-down experiments of the system. The results show that the structures of AMB have less influence on the dynamic characteristics of the motorized spindle. However, the homopolar structure can effectively reduce the iron loss of the radial AMB and it is useful for improving the overall performance of the motorized spindle.展开更多
The Aral Sea was one of the largest lakes in the world before it started to shrink in the 1960s due to water withdrawal for agricultural irrigation. Precipitation decreased from 9.4 kmin 1960 to 3.2 km3 in 2009, and a...The Aral Sea was one of the largest lakes in the world before it started to shrink in the 1960s due to water withdrawal for agricultural irrigation. Precipitation decreased from 9.4 kmin 1960 to 3.2 km3 in 2009, and annual river inflow into the Aral Sea decreased from 31.5 km3 in 1998 to 5.2 km3 in 2009. Comparison on the hydrological data of the Aral Sea between 1960 and 2009 showed the evaporation, water surface area, and water volume decreased by 90%, 80%, and 88%, respectively. This study employs the observed values of water volume, precipitation, runoff, evaporation, and salinity to estimate water volume and salinity from 1960 to 2009, and the efficiency coefficients for predicted water volume and salinity are o.975 and 0.974, respectively. Regression equations calculated from the observed data are used to predict precipitation, runoff, evaporation, and salinity from 20lO to 2021, and the results are then applied in the estimation of water volume and salinity Our estimates suggest that salinity will increase to around 200 g/L and water volume will decrease to around 83 km3 in 2021.展开更多
Structural Health Monitoring(SHM)is the process of collecting,interpreting and analysing data from structures in order to determine its health status and the remaining life span.Composite materials have been extensive...Structural Health Monitoring(SHM)is the process of collecting,interpreting and analysing data from structures in order to determine its health status and the remaining life span.Composite materials have been extensively use in recent years in several industries with the aim at reducing the total weight of structures while improving their mechanical properties.However,composite materials are prone to develop damage when subjected to low to medium impacts(i.e.1-10 m/s and 11-30 m/s respectively).Hence,the need to use SHM techniques to detect damage at the incipient initiation in composite materials is of high importance.Despite the availability of several SHM methods for the damage identification in composite structures,no single technique has proven suitable for all circumstances.It must be noted that the amount of techniques available nowadays is too extensive to be comprehensively reviewed in a single paper.Therefore,the focus will be on techniques that can serve as a starting point for studies focusing on damage detection,localisation,assessment and prognosis on certain kinds of structures.Thus,the line of thought behind the search and the structure of this review is a result of objectives beyond the scope of the paper itself.Nevertheless,it was considered that,once the above was understood,an updated synopsis such as this could also be useful for other researchers in the same field.展开更多
Fe（II）/γ-Al2O3 powders synthesized using the dipping method were produced from a mixed aqueous solution containing aluminium oxide （γ-Al2O3） and iron（II）-precursor （FeSO4）, and used for photoFenton degradati...Fe（II）/γ-Al2O3 powders synthesized using the dipping method were produced from a mixed aqueous solution containing aluminium oxide （γ-Al2O3） and iron（II）-precursor （FeSO4）, and used for photoFenton degradation of phthalocyanine dyes （PCs） under ultraviolet （UV） irradiation in an up-flow fluidized bed. The catalysts were characterized by XRD, ESCA, BET, EDS and SEM. The results showed that Fe2＋ ion was compounded on the γ-Al2O3 carder. The effects of different reaction parameters such as catalyst activity, dosage and solution pH on the decolorization of PCs were assessed. Results indicated that maximum decolorization （more than 95%） of PCs occurred with 20 wt% Fe（II）/γ-Al2O3 catalyst （dosage of 60 g/L） using a combination of UV irradiation and heterogeneous Fenton system. The degradation efficiency of PCs increases as pH decreases, exhibiting a maximum efficiency at pH 3.5. The recycled catalyst was capable of repeating three runs without a significant decrease in treatment efficiency, and this demonstrated the stability and reusability of catalyst.展开更多
The application of mixed powders with different mass fraction on laser additive repairing(LAR)can be an effective way to guarantee the performance and functionality of repaired part in time.A convenient and feasible a...The application of mixed powders with different mass fraction on laser additive repairing(LAR)can be an effective way to guarantee the performance and functionality of repaired part in time.A convenient and feasible approach is presented to repair TA15 forgings by employing Ti6Al4V-xTA15 mixed powders in this paper.The performance compatibility of Ti6Al4V-xTA15 powders from the aspects of microhardness,tensile property,heat capacity,thermal expansion coefficient and corrosion resistance with the TA15 forgings was fully investigated.The primaryαlaths were refined and the volume fraction of the secondaryαphase was increased by increasing the mass fraction of TA15 in the mixed Ti6Al4V-xTA15 powders,leading to varied performances.In conclusion,the mixed Ti6Al4V-70%TA15(x=70%)powders is the most suitable candidate and is recommended as the raw material for LAR of TA15 forgings based on overall consideration of the compatibility calculations of the laser repaired zone with the wrought substrate zone.展开更多
The flight-structural dynamics of a high-aspect-ratio wing challenge the flight control design.This paper develops a reduced model of coupled dynamics with stability consideration.The structural dynamics are formulate...The flight-structural dynamics of a high-aspect-ratio wing challenge the flight control design.This paper develops a reduced model of coupled dynamics with stability consideration.The structural dynamics are formulated with dihedrals,and the central loads drive the deformation.The control-oriented model with essential coupled dynamics is formulated.Modal sensitivity anal-ysis and input–output pairing are performed to identify the control structure.Besides,an example of flight control design is provided to discuss the necessity of considering structural dynamics in controller design.Analytical coupled flight dynamics provide a system-theoretic approach for sta-bility and facilitate model-based control techniques.Simulation results reveal the characteristics of flight-structural coupled dynamics and demonstrate that the influence of flexible modes should be considered in control design,especially in lateral dynamics.展开更多
The article deals with the motion of the breech block carrier and the weapon casing of an automatic weapon mounted on a flexible carriage and the base of the weapon.Earlier works,which did not consider the dynamic pro...The article deals with the motion of the breech block carrier and the weapon casing of an automatic weapon mounted on a flexible carriage and the base of the weapon.Earlier works,which did not consider the dynamic properties of the base of the weapon,did not allow to reconcile the calculated and experimental results of the weapon casing displacement when shooting from firing rests.For the analysis of the motion of individual parts,the methods of mathematical modelling and firing experiments using a high-speed camera were chosen.Calculations show the best accord with experiment when modelling the system with 4 degrees of freedom.The oscillation of the system regarding the movement of the breech block carrier and the weapon casing was investigated under changed conditions of rate of fire,the use of a muzzle brake and different types of shock absorbers.The velocities and displacements of the weapon casing and the breech block carrier at different values of the impulse of the gases to the breech block carrier were determined.展开更多
Traditional clothing design models based on adaptive meshes cannot reflect.To solve this problem,a clothing simulation design model based on 3D image analysis technology is established.The model uses feature extractio...Traditional clothing design models based on adaptive meshes cannot reflect.To solve this problem,a clothing simulation design model based on 3D image analysis technology is established.The model uses feature extraction and description of image evaluation parameters,and establishes the mapping relationship between image features and simulation results by using the optimal parameter values,thereby obtaining a three-dimensional image simulation analysis environment.On the basis of this model,by obtaining the response results of clothing collision detection and the results of local adaptive processing of clothing meshes,the cutting form and actual cutting effect of clothing are determined to construct a design model.The simulation results show that compared with traditional clothing design models,clothing simulation design based on 3D image analysis technology has a better effect,with the definition of fabric folds increasing by 40%.More striking contrast between light and dark,the resolution increasing by 30%,and clothing details getting a more real manifestation.展开更多
Driven by the ever increasing demand in function integration,more and more next generation high value-added products,such as head-up displays,solar concentrators and intra-ocular-lens,etc.,are designed to possess free...Driven by the ever increasing demand in function integration,more and more next generation high value-added products,such as head-up displays,solar concentrators and intra-ocular-lens,etc.,are designed to possess freeform(i.e.,non-rotational symmetric)surfaces.The toolpath,composed of high density of short linear and circular segments,is generally used in computer numerical control(CNC)systems to machine those products.However,the discontinuity between toolpath segments leads to high-frequency fluctuation of feedrate and acceleration,which will decrease the machining efficiency and product surface finish.Driven by the ever-increasing need for high-speed high-precision machining of those products,many novel toolpath interpolation and smoothing approaches have been proposed in both academia and industry,aiming to alleviate the issues caused by the conventional toolpath representation and interpolation methods.This paper provides a comprehensive review of the state-of-the-art toolpath interpolation and smoothing approaches with systematic classifications.The advantages and disadvantages of these approaches are discussed.Possible future research directions are also offered.展开更多
To overcome the bottleneck of the one-way translation from VR （ virtual reality） to CAD in VR-based CAD system, this paper proposes a Web-based VR-CAD system WVCD （ Web-based virtual conceptual designer） to suppor...To overcome the bottleneck of the one-way translation from VR （ virtual reality） to CAD in VR-based CAD system, this paper proposes a Web-based VR-CAD system WVCD （ Web-based virtual conceptual designer） to support both customers＇and design team members＇involvement in the conceptual design and analysis activity over the Internet. It provides users with both parametric and freehand methods to create and edit 3D conceptual models with different levels of complexity in a VR environment intuitively without the need of switching between the VR environment and CAD tools. As a simple and low-cost VR-CAD system, WVCD can help to popularize and improve the Web-based collaborative conceptual design.展开更多
文摘This paper explains how the optimized classrooms were selected and the results that were achieved by the optimizations carried out and finalized.The context of the research is the city of Concepción,in Chile.Virtual models of classrooms were evaluated using the Radiance software.We used a methodology that allowed us to determine the luminous conditions under different types of skies,seasons of the year and times of the day.The evaluation of the typologies was performed based on three defined criteria,in order to achieve the stated design objectives.We defined the optimal solutions for each orientation and,finally,we stated design recommendations for daylit classrooms to ensure the visual comfort of the students.These recommendations link all that found in the initial analysis with that found in the optimization stage.
文摘Regional design is the design method based on the geographical characteristics, and the natural environment is basic factors. This paper puts forward to the regional product design thought patterns and makes some brief comments on its value and social significance of the design, in a long run, with exploratory guiding significance.
基金the China Postdoctoral Science Foundation(No.2024M754169)Fundamentals of Equipment Technology(No.2212W22002)for the support of this work。
文摘Micro diamond tools are indispensable for the efficient machining of microstructured surfaces.The precision in tool manufacturing and cutting performance directly determines the processing quality of components.The manufacturing of high-quality micro diamond tools relies on scientific design methods and appropriate processing techniques.However,there is currently a lack of systematic review on the design and manufacturing methods of micro diamond tools in academia.This study systematically summarizes and analyzes modern manufacturing methods for micro diamond tools,as well as the impact of tool waviness,sharpness,and durability on machining quality.Subsequently,a design method is proposed based on the theory of cutting edge strength distribution to enhance tool waviness,sharpness,and durability.Finally,this paper presents current technical challenges faced by micro diamond tools along with potential future solutions to guide scientists in this field.The aim of this review is to contribute to the further development of the current design and manufacturing processes for micro diamond cutting tools.
文摘Background and Aim:Despite their flaws,the low-cost but powerful economical solutions can ensure everyone has access to health.The main aim of this study is to extract characteristics of frugal innovation(FI)and social innovation(SI)for Primary Health Centers(PHCs)in low resource settings(LRS)for sustainable development.We will use the gained insights to design the mobile primary healthcare infrastructure using FI and SI strategies.There is a lack of methodology to design sustainable healthcare infrastructure for LRS.There is a gap in the literature about building sustainable infrastructure to provide basic healthcare facilities essential to the community.This article studies several factors necessary for designing sustainable infrastructure from the lens of FI,SI,and sustainability to develop a mobile healthcare infrastructure for last-mile people.Methods:Started with purposive sampled case studies to find out factors and criteria that most affect the success for an innovation to be frugal,social,and sustainable.The established criteria were used to design,develop,and deploy the mobile Primary Health Center(mPHC).Moving forward,we tested the system designed with stakeholders to gather insights.At this stage we found the feedback loop from the stakeholders and the role of interdisciplinary discussions between experts,medical officers,nurses,patient,and other staff of PHCs during the design,development,deployment,and test stage to be useful in taking design decisions efficiently.Results:The designed healthcare infrastructure of mPHC through the aspects of FI and SI proves to be efficient in providing key healthcare services to LRS.Conclusion:Focusing on essential capabilities and optimizing performance with technology,methodologies,and processes reduces costs in an innovation.Focus on socially inclusive and rebalancing power disparities,overcome societal challenges and improve human capabilities will create a sustainable and novel solution.
基金supported by the Czech Technical University in Prague(Grant no.SGS23/108/OHK2/2T/12).
文摘This study investigates the traction performance and efficiency of a conical friction continuously variable trans-mission.A new mathematical model was developed and validated through experimental measurements using a custom-built test rig to predict these parameters accurately.The results showed a close correlation between the-oretical predictions and experimental data.Key findings include the impact of load on efficiency and the model’s ability to predict performance under various operating conditions.The study provides detailed insights into the dynamics of conical friction variator and demonstrates the model’s effectiveness in predicting real-world behav-ior.The developed model can assist in selecting optimal parameters during the design phase and can be applied to other developing variator systems to achieve maximum efficiency.
基金the National Natural Science Foundation of China(Award No.07120016)support by the Dalian University of Technology(DUT)(Award Nos.82232022,82232043,and DUT22LAB404)AVIC Shenyang Aircraft Company(Award No.12020641 and 12020642)。
文摘Leveraging surface texturing to realize significant friction reduction at contact interfaces has emerged as a preferred technique among tribology experts,boosting tribological energy efficiency and sustainability.This review systematically demonstrates optimization strategies,advanced manufacturing methods,typical applications,and outlooks of technical challenges toward surface texturing for friction reduction.Firstly,the lubricated contact models of microtextures are introduced.Then,we provide a framework of state-of-the-art research on synergistic friction optimization strategies of microtexture structures,surface treatments,liquid lubricants,and external energy fields.A comparative analysis evaluates the strengths and weaknesses of manufacturing techniques commonly employed for microtextured surfaces.The latest research advancements in microtextures in different application scenarios are highlighted.Finally,the challenges and directions of future research on surface texturing technology are briefly addressed.This review aims to elaborate on the worldwide progress in the optimization,manufacturing,and application of microtexture-enabled friction reduction technologies to promote their practical utilizations.
基金financially supported by the National Science Foundation of China(No.51104034)the Fundamental Research Funds for the Central Universities(No.N130601003)the Program for New Century Excellent Talents in University of Ministry of Education of China
文摘The mineralogical characteristics of tantalumniobium ores from Songzi were investigated using mineral liberation analyzer （MLA） and chemical analysis. In particular, the chemical composition, phase composition, particle size, and dissemination characteristics of the ores were studied in detail. Results show that Ta2O5 and Nb2O5 have grades of 0.013 % and 0.011%, respectively. The main valuable minerals in the ores are tantalite, col- umbite, tantalum-niobite, and microlite, and the gangue minerals associated with tantalum-niobium minerals mainly include quartz, kaolinite, illite, feldspar, and mica among others. The minerals are embedded in a complex manner. Tantalum-niobium minerals with most particle sizes of -0.040 mm are disseminated in minerals, such as mica, illite, quartz, and partially intergrown with topaz and zircon, where they could not be easily liberated. Thus, the ores are classified as low-grade, micro-fine, and refractory tantalum-niobium ores. Based on this consideration, the process of classification-gravity concentration-magnetic separation-middlings regrinding and gravity concentration are finally determined and satisfactory indices are obtained. Two rough concentrates are produced： Concentrate I has Ta2O5 and Nb2O5 grades of 7.0292 % and 3.546 %, respectively, as well as recovery of 49.42 % and 35.46 %. By comparison, Concentrate Ⅱ has Ta2O5 and Nb2O5 grades of 7.0292 % and 3.546 %, respectively, as well as recovery of 49.42 % and 35.46 %.
基金supported by the Shenzhen Government’s Plan of Science and Technology(JCYJ20190808121407676 and 20200813142301001)National Natural Science Foundation of China(22178223 and 22262010)+1 种基金Guangxi Science and Technology Fund for Distinguished High-Talent Introduction Program(No.RZ2200002233AC22035091).
文摘Rechargeable zinc-air batteries(ZABs)are a promising energy conversion device,which rely critically on electrocatalysts to accelerate their rate-determining reactions such as oxygen reduction(ORR)and oxygen evolution reactions(OER).Herein,we fabricate a range of bifunctional M-N-C(metal-nitrogen-carbon)catalysts containing M-Nx coordination sites and M/MxC nanoparticles(M=Co,Fe,and Cu)using a new class ofγ-cyclodextrin(CD)based metal-organic framework as the precursor.With the two types of active sites interacting with each other in the catalysts,the obtained Fe@C-FeNC and Co@C-CoNC display superior alkaline ORR activity in terms of low half-wave(E1/2)potential(~0.917 and 0.906 V,respectively),which are higher than Cu@C-CuNC(~0.829 V)and the commercial Pt/C(~0.861 V).As a bifunctional electrocatalyst,the Co@C-CoNC exhibits the best performance,showing a bifunctional ORR/OER overpotential(ΔE)of~0.732 V,which is much lower than that of Fe@C-FeNC(~0.831 V)and Cu@C-CuNC(~1.411 V),as well as most of the robust bifunctional electrocatalysts reported to date.Synchrotron X-ray absorption spectroscopy and density functional theory simulations reveal that the strong electronic correlation between metallic Co nanoparticles and the atomic Co-N4 sites in the Co@C-CoNC catalyst can increase the d-electron density near the Fermi level and thus effectively optimize the adsorption/desorption of intermediates in ORR/OER,resulting in an enhanced bifunctional electrocatalytic performance.The Co@C-CoNC-based rechargeable ZAB exhibited a maximum power density of 162.80 mW cm^(−2) at 270.30 mA cm^(−2),higher than the combination of commercial Pt/C+RuO2(~158.90 mW cm^(−2) at 265.80 mA cm^(−2))catalysts.During the galvanostatic discharge at 10 mA cm^(−2),the ZAB delivered an almost stable discharge voltage of 1.2 V for~140 h,signifying the virtue of excellent bifunctional ORR/OER electrocatalytic activity.
基金co-supported by the National Natural Science Foundation of China (No. 51275238)a Project Funded by Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD) of China
文摘A motorized spindle supported by active magnetic bearings（AMBs） is generally used for ultra-high-speed machining. Iron loss of radial AMB is very great owing to high rotation speed, and it will cause severe thermal deformation. The problem is particularly serious on the occasion of large power application, such as all electric aero-engine. In this study, a prototype motorized spindle supported by five degree-of-freedom AMBs is developed. Homopolar and heteropolar AMBs are independently adopted as radial bearings. The influences of the two types of radial AMBs on the dynamic characteristics of the motorized spindle are comparatively investigated by theoretical analysis, test modal analysis and actual operation of the system. The iron loss of the two types of radial AMBs is analyzed by finite element software and verified through run-down experiments of the system. The results show that the structures of AMB have less influence on the dynamic characteristics of the motorized spindle. However, the homopolar structure can effectively reduce the iron loss of the radial AMB and it is useful for improving the overall performance of the motorized spindle.
文摘The Aral Sea was one of the largest lakes in the world before it started to shrink in the 1960s due to water withdrawal for agricultural irrigation. Precipitation decreased from 9.4 kmin 1960 to 3.2 km3 in 2009, and annual river inflow into the Aral Sea decreased from 31.5 km3 in 1998 to 5.2 km3 in 2009. Comparison on the hydrological data of the Aral Sea between 1960 and 2009 showed the evaporation, water surface area, and water volume decreased by 90%, 80%, and 88%, respectively. This study employs the observed values of water volume, precipitation, runoff, evaporation, and salinity to estimate water volume and salinity from 1960 to 2009, and the efficiency coefficients for predicted water volume and salinity are o.975 and 0.974, respectively. Regression equations calculated from the observed data are used to predict precipitation, runoff, evaporation, and salinity from 20lO to 2021, and the results are then applied in the estimation of water volume and salinity Our estimates suggest that salinity will increase to around 200 g/L and water volume will decrease to around 83 km3 in 2021.
文摘Structural Health Monitoring(SHM)is the process of collecting,interpreting and analysing data from structures in order to determine its health status and the remaining life span.Composite materials have been extensively use in recent years in several industries with the aim at reducing the total weight of structures while improving their mechanical properties.However,composite materials are prone to develop damage when subjected to low to medium impacts(i.e.1-10 m/s and 11-30 m/s respectively).Hence,the need to use SHM techniques to detect damage at the incipient initiation in composite materials is of high importance.Despite the availability of several SHM methods for the damage identification in composite structures,no single technique has proven suitable for all circumstances.It must be noted that the amount of techniques available nowadays is too extensive to be comprehensively reviewed in a single paper.Therefore,the focus will be on techniques that can serve as a starting point for studies focusing on damage detection,localisation,assessment and prognosis on certain kinds of structures.Thus,the line of thought behind the search and the structure of this review is a result of objectives beyond the scope of the paper itself.Nevertheless,it was considered that,once the above was understood,an updated synopsis such as this could also be useful for other researchers in the same field.
文摘Fe（II）/γ-Al2O3 powders synthesized using the dipping method were produced from a mixed aqueous solution containing aluminium oxide （γ-Al2O3） and iron（II）-precursor （FeSO4）, and used for photoFenton degradation of phthalocyanine dyes （PCs） under ultraviolet （UV） irradiation in an up-flow fluidized bed. The catalysts were characterized by XRD, ESCA, BET, EDS and SEM. The results showed that Fe2＋ ion was compounded on the γ-Al2O3 carder. The effects of different reaction parameters such as catalyst activity, dosage and solution pH on the decolorization of PCs were assessed. Results indicated that maximum decolorization （more than 95%） of PCs occurred with 20 wt% Fe（II）/γ-Al2O3 catalyst （dosage of 60 g/L） using a combination of UV irradiation and heterogeneous Fenton system. The degradation efficiency of PCs increases as pH decreases, exhibiting a maximum efficiency at pH 3.5. The recycled catalyst was capable of repeating three runs without a significant decrease in treatment efficiency, and this demonstrated the stability and reusability of catalyst.
基金Project(2019-00899-1-1)supported by the Ministry of Industry and Information Technology of ChinaProject(2021JM-060)supported by the Natural Science Foundation of Shaanxi Province,ChinaProject(3102019QD0409)supported by the Fundamental Research Funds for the Central Universities,China。
文摘The application of mixed powders with different mass fraction on laser additive repairing(LAR)can be an effective way to guarantee the performance and functionality of repaired part in time.A convenient and feasible approach is presented to repair TA15 forgings by employing Ti6Al4V-xTA15 mixed powders in this paper.The performance compatibility of Ti6Al4V-xTA15 powders from the aspects of microhardness,tensile property,heat capacity,thermal expansion coefficient and corrosion resistance with the TA15 forgings was fully investigated.The primaryαlaths were refined and the volume fraction of the secondaryαphase was increased by increasing the mass fraction of TA15 in the mixed Ti6Al4V-xTA15 powders,leading to varied performances.In conclusion,the mixed Ti6Al4V-70%TA15(x=70%)powders is the most suitable candidate and is recommended as the raw material for LAR of TA15 forgings based on overall consideration of the compatibility calculations of the laser repaired zone with the wrought substrate zone.
基金co-supported by the Natural Science Founda-tion of Jiangsu Province,China(No.BK20200437)the National Natural Science Foundation of China(No.62103187)the Fundamental Research Funds for the Cen-tral Universities,China(No.NT2022025).
文摘The flight-structural dynamics of a high-aspect-ratio wing challenge the flight control design.This paper develops a reduced model of coupled dynamics with stability consideration.The structural dynamics are formulated with dihedrals,and the central loads drive the deformation.The control-oriented model with essential coupled dynamics is formulated.Modal sensitivity anal-ysis and input–output pairing are performed to identify the control structure.Besides,an example of flight control design is provided to discuss the necessity of considering structural dynamics in controller design.Analytical coupled flight dynamics provide a system-theoretic approach for sta-bility and facilitate model-based control techniques.Simulation results reveal the characteristics of flight-structural coupled dynamics and demonstrate that the influence of flexible modes should be considered in control design,especially in lateral dynamics.
基金supported by the Research project VAROPS(Military autonomous and robotic assets)of the Ministry of Defence of The Czech Republicby the Specific Research Support Project(Grant No.SV22-201)financed from funds of the Ministry of Education,Youth and Sports of The Czech Republic。
文摘The article deals with the motion of the breech block carrier and the weapon casing of an automatic weapon mounted on a flexible carriage and the base of the weapon.Earlier works,which did not consider the dynamic properties of the base of the weapon,did not allow to reconcile the calculated and experimental results of the weapon casing displacement when shooting from firing rests.For the analysis of the motion of individual parts,the methods of mathematical modelling and firing experiments using a high-speed camera were chosen.Calculations show the best accord with experiment when modelling the system with 4 degrees of freedom.The oscillation of the system regarding the movement of the breech block carrier and the weapon casing was investigated under changed conditions of rate of fire,the use of a muzzle brake and different types of shock absorbers.The velocities and displacements of the weapon casing and the breech block carrier at different values of the impulse of the gases to the breech block carrier were determined.
文摘Traditional clothing design models based on adaptive meshes cannot reflect.To solve this problem,a clothing simulation design model based on 3D image analysis technology is established.The model uses feature extraction and description of image evaluation parameters,and establishes the mapping relationship between image features and simulation results by using the optimal parameter values,thereby obtaining a three-dimensional image simulation analysis environment.On the basis of this model,by obtaining the response results of clothing collision detection and the results of local adaptive processing of clothing meshes,the cutting form and actual cutting effect of clothing are determined to construct a design model.The simulation results show that compared with traditional clothing design models,clothing simulation design based on 3D image analysis technology has a better effect,with the definition of fabric folds increasing by 40%.More striking contrast between light and dark,the resolution increasing by 30%,and clothing details getting a more real manifestation.
基金the support from the UK Engineering and Physical Sciences Research Council (EPSRC) under the program (No. EP/K018345/1)the International Cooperation Program of China (No. 2015DFA70630)
文摘Driven by the ever increasing demand in function integration,more and more next generation high value-added products,such as head-up displays,solar concentrators and intra-ocular-lens,etc.,are designed to possess freeform(i.e.,non-rotational symmetric)surfaces.The toolpath,composed of high density of short linear and circular segments,is generally used in computer numerical control(CNC)systems to machine those products.However,the discontinuity between toolpath segments leads to high-frequency fluctuation of feedrate and acceleration,which will decrease the machining efficiency and product surface finish.Driven by the ever-increasing need for high-speed high-precision machining of those products,many novel toolpath interpolation and smoothing approaches have been proposed in both academia and industry,aiming to alleviate the issues caused by the conventional toolpath representation and interpolation methods.This paper provides a comprehensive review of the state-of-the-art toolpath interpolation and smoothing approaches with systematic classifications.The advantages and disadvantages of these approaches are discussed.Possible future research directions are also offered.
文摘To overcome the bottleneck of the one-way translation from VR （ virtual reality） to CAD in VR-based CAD system, this paper proposes a Web-based VR-CAD system WVCD （ Web-based virtual conceptual designer） to support both customers＇and design team members＇involvement in the conceptual design and analysis activity over the Internet. It provides users with both parametric and freehand methods to create and edit 3D conceptual models with different levels of complexity in a VR environment intuitively without the need of switching between the VR environment and CAD tools. As a simple and low-cost VR-CAD system, WVCD can help to popularize and improve the Web-based collaborative conceptual design.
