The present study focuses on the flow of a yield-stress(Bingham)nanofluid,consisting of suspended Fe3O4 nanoparticles,subjected to a magnetic field in a backward-facing step duct(BFS)configuration.The duct is equipped...The present study focuses on the flow of a yield-stress(Bingham)nanofluid,consisting of suspended Fe3O4 nanoparticles,subjected to a magnetic field in a backward-facing step duct(BFS)configuration.The duct is equipped with a cylindrical obstacle,where the lower wall is kept at a constant temperature.The yield-stress nanofluid enters this duct at a cold temperature with fully developed velocity.The aim of the present investigation is to explore the influence of flow velocity(Re=10 to 200),nanoparticle concentration(ϕ=0 to 0.1),magnetic field intensity(Ha=0 to 100),and its inclination angle(γ=0 to 90)and nanofluid yield stress(Bn=0 to 20)on the thermal and hydrodynamic efficiency inside the backward-facing step.The numerical results have been obtained by resolving the momentum and energy balance equations using the Galerkin finite element method.The obtained results have indicated that an increase in Reynolds number and nanoparticle volume fraction enhances heat transfer.In contrast,a significant reduction is observed with an increase in Hartmann and Bingham numbers,resulting in quasi-immobilization of the fluid under the magnetic influence and radical solidification of this type of fluid,accompanied by the suppression of the vortex zone downstream of the cylindrical obstacle.This study sheds light on the complexity of this magnetically influenced fluid,with potential implications in various engineering and materials science fields.展开更多
Taking a C1x motor with a backward-facing step which can generate a typical corner vortex as a reference,a numerical methodology using large eddy simulation was established in this study.Based on this methodology,the ...Taking a C1x motor with a backward-facing step which can generate a typical corner vortex as a reference,a numerical methodology using large eddy simulation was established in this study.Based on this methodology,the position of the backward-facing step of the motor was computed and analyzed to determine a basic configuration.Two key geometrical parameters,the head cavity angle and submerged nozzle cavity height,were subsequently introduced.Their effects on the corner vortex motion and their interactions with the acoustic pressure downstream of the backward-facing step were analyzed.The phenomena of vortex acoustic coupling and characteristics of pressure oscillations were further explored.The results show that the maximum error between the simulations and experimental data on the dominant frequency of pressure oscillations is 5.23%,which indicates that the numerical methodology built in this study is highly accurate.When the step is located at less than 5/8 of the total length of the combustion chamber,vortex acoustic coupling occurs,which can increase the pressure oscillations in the motor.Both the vorticity and the scale of vortices in the downstream step increase when the head cavity angle is greater than 24°,which increases the amplitude of the pressure oscillation by maximum 63.0%.The submerged nozzle cavity mainly affects the vortices in the cavity itself rather than those in the downstream step.When the height of the cavity increases from 10 to 20 mm,the pressure oscillation amplitude under the main frequency increases by 39.1%.As this height continues to increase,the amplitude of pressure oscillations increases but the primary frequency decreases.展开更多
The events of the preceding two years have restructured the traditional systems of global governance which have dominated the international order since 1945.
AS a metropolitan resident who is used to seeing towering buildings, an incessant stream of vehicles and people, I’ve always longed to have a taste of an ancient civilization, which is vigorous but exquisite, bold bu...AS a metropolitan resident who is used to seeing towering buildings, an incessant stream of vehicles and people, I’ve always longed to have a taste of an ancient civilization, which is vigorous but exquisite, bold but elegant, natural but mysterious. I realized my dream when I went to Xi’an, a capital with a history of over 1,000 years. Xi’an was once the capital for eleven dynasties, including the Zhou, Qin, Han and Tang. This is the place where China’s ancient civilization developed. Ancestors at Banpo created exquisite painted pottery; the Western Zhou Dynasty (about 1,066-771 B.C.) saw the height of the splendors of the bronze culture; the Qin Emperor Shi Huang (Qin Dynasty, from about 221-206 B.C.)展开更多
The paper presents our contribution to the full 3D finite element modelling of a hybrid stepping motor using COMSOL Multiphysics software. This type of four-phase motor has a permanent magnet interposed between the tw...The paper presents our contribution to the full 3D finite element modelling of a hybrid stepping motor using COMSOL Multiphysics software. This type of four-phase motor has a permanent magnet interposed between the two identical and coaxial half stators. The calculation of the field with or without current in the windings (respectively with or without permanent magnet) is done using a mixed formulation with strong coupling. In addition, the local high saturation of the ferromagnetic material and the radial and axial components of the magnetic flux are taken into account. The results obtained make it possible to clearly observe, as a function of the intensity of the bus current or the remanent induction, the saturation zones, the lines, the orientations and the magnetic flux densities. 3D finite element modelling provide more accurate numerical data on the magnetic field through multiphysics analysis. This analysis considers the actual operating conditions and leads to the design of an optimized machine structure, with or without current in the windings and/or permanent magnet.展开更多
A robust adaptive control approach is presented to improve the performance of the control scheme proposed in the authors＇ previous work, aiming at producing a low ripple hybrid stepping motor servo drive for precisio...A robust adaptive control approach is presented to improve the performance of the control scheme proposed in the authors＇ previous work, aiming at producing a low ripple hybrid stepping motor servo drive for precision profile tracking at a low speed. In order to construct a completely integrated control design philosophy to reduce torque ripple and at the same time to enhance tracking performance, the properties of nonlinear uncertainties in the system dynamics are uncovered, and then incorporated into the design of the controller. The system uncertainties concerned with ripple dynamics and other external disturbances are composed of two categories. The first category of uncertainties with linear parameterization arising from the detention effect is dealt with by the wellknown adaptive control method. A robust adaptive method is used to deal with the second category of uncertainties resulting from the non-sinusoidal flux distribution. The μ-modification scheme is used to cease parameter adaptation by the robust adaptive control law, thus ensuring that the trajectory tracking error asymptotically converges to a pre-specified boundary. Experiments are performed with a typical hybrid stepping motor to test its profile tracking accuracy. Results confirm the proposed control scheme.展开更多
Check dams are widely constructed on China's Loess Plateau,which had a total number of 58,776 by the end of 2019.Great achievements in check dam construction have been gained regarding the economic and environment...Check dams are widely constructed on China's Loess Plateau,which had a total number of 58,776 by the end of 2019.Great achievements in check dam construction have been gained regarding the economic and environmental impacts.This study reviews the remarkable benefits of check dams on the land reclamation and environmental improvement on the Loess Plateau,and sediment reduction entering the Yellow River.However,the flood incidents on check dams have been frequently reported for the past decades,which has attracted more attention in the context of climate change and extreme rainfall events recently.Advances in the flood migration techniques achieved by the research group led by the first author have been highlighted to migrate the breach risk of check dams due to floods.The“family tree method”has been proposed to determine the survival status and critical rainfall threshold of each check dam in the complicated dam system.An updated dam breach flood evaluation framework and the corresponding numerical algorithm(i.e.,DB-IWHR)have been developed.Moreover,innovative types of water-release facilities for check dams,including geobag stepped spillway and prestressed concrete cylinder pipe in the underlying conduit,have been proposed and developed.Finally,the perspectives concerning the check dam construction on the Loess Plateau have been put forward.展开更多
悦读·明其义Conquering challenges,embracing growth克服挑战,拥抱成长Personal growth is a continuous journey that involves learning and overcoming challenges.It helps us develop our skills and achieve our goals.For ...悦读·明其义Conquering challenges,embracing growth克服挑战,拥抱成长Personal growth is a continuous journey that involves learning and overcoming challenges.It helps us develop our skills and achieve our goals.For many,the journey begins with stepping out of our comfort zones and facing new challenges.Understanding ourselves is very important for personal growth.By knowing our strengths and weaknesses,we can find areas to improve.For example,if you have trouble speaking in public,you can join a speech club or practice in front of a mirror.This kind of self⁃reflection helps us see our limitations and turn them into opportunities for growth.展开更多
Animals can differ in their individual movement behaviors during their daily displacements.Studies of animal movement patterns often disregard the need to understand individual variation in these patterns and the role...Animals can differ in their individual movement behaviors during their daily displacements.Studies of animal movement patterns often disregard the need to understand individual variation in these patterns and the role of this variation in shaping population distributions of movements.To assess the link between individual movements and population distributions,we radio-tracked 13 Fowler's Toads Anaxyrus fowleri in Long Point,Ontario,Canada,after their breeding season.We recorded individual coordinates every 30 min,from the moment they emerged from their burrows around dusk until they burrowed in the morning,and obtained a total of 157 movements.We used the resulting series of step lengths and turning angles in a Hidden Markov Model to estimate movement type as"directed"or"non-directed"We also assigned to each encounter one of 3 space-dependent movement states:"foraging""in transit'or"searching"and found that movement type and state switched within individuals irrespective of time during a single night.We find that switching between movement types varied throughout the night,leading to stochastic within-individual variation in movements,and the distribution of movement distances differed significantly among individuals.Movement states,however,were time-dependent,suggesting displacement routines were similar across individuals.Variation in movement behavior within individuals scales up to result in variation among individuals which,in turn,was found to shape the distribution of the sampled population.Our findings therefore underline the importance of a multi-scale approach in the study of movement.展开更多
Upgrading of abundant cellulosic biomass to isosorbide can reduce the dependence on limited fossil resources and provide a sustainable way to produce isosorbide,utilized for polymers,medicine and health care product s...Upgrading of abundant cellulosic biomass to isosorbide can reduce the dependence on limited fossil resources and provide a sustainable way to produce isosorbide,utilized for polymers,medicine and health care product synth-esis.This review comprehensively examines the key steps and catalytic systems involved in the conversion of cel-lulose to isosorbide.Initially,the reaction pathway from cellulose to isosorbide is elucidated,emphasizing three critical steps:cellulose hydrolysis,glucose hydrogenation,and the two-step dehydration of sorbitol to produce isosorbide.Additionally,the activation energy and acidic sites during cellulose hydrolysis,the impact of metal particle size and catalyst support on hydrogenation,and the effects of catalyst acidity,pore structure,and reaction conditions on sorbitol dehydration have been thoroughly examined.Finally,the progress made in cellulose con-version to isosorbide is summarized,current challenges are highlighted,and future development trends are pro-jected in this review.展开更多
As the beauty sector of China steps into a high-quality development stage,compliance has been an unavoidable topic in the industry.After the implementation of Regulations on Cosmetic Products Supervision and Managemen...As the beauty sector of China steps into a high-quality development stage,compliance has been an unavoidable topic in the industry.After the implementation of Regulations on Cosmetic Products Supervision and Management,a number of supporting regulations were published to make more strict and specific requirements on new product filing,efficacy claims,and label renewal.Each implementation of the regulations brings an elimination process.展开更多
China will diligently work towards peaking carbon dioxide emissions before 2030 and achieving carbon neutrality before 2060,according to the Government Work Report delivered at the opening of the third session of the ...China will diligently work towards peaking carbon dioxide emissions before 2030 and achieving carbon neutrality before 2060,according to the Government Work Report delivered at the opening of the third session of the 14th National People’s Congress in Beijing on 5 March.The country will take steps to respond to green trade barriers as it advances towards carbon neutrality,the report states.展开更多
Against the backdrop of China’s“dual-carbon”target,clean energy generation currently accounts for about 3.8 trillion kilowatt-hours,or 39.7 percent of total power generation,establishing a reasonable market trading...Against the backdrop of China’s“dual-carbon”target,clean energy generation currently accounts for about 3.8 trillion kilowatt-hours,or 39.7 percent of total power generation,establishing a reasonable market trading mechanism while enhancing the low-carbon economic benefits of the integrated energy system(IES)and optimizing the interests of various entities within the distribution system has become a significant challenge.Consequently,this paper proposes an optimization strategy for a low-carbon economy within a multi-agent IES that considers carbon capture systems(CCS)and power-to-gas(P2G).In this framework,the integrated energy system operator(IESO)acts as the primary leader,while energy suppliers(ES),energy storage operators(ESO),and load aggregators(LA)follow.At the level of low-carbon technology,a coupling model of P2G and CCS is developed,leading to the establishment of an IES that incorporates energy conversion and storage equipment.Economically,effective control of system carbon emissions in market trading is progressively established.Lastly,the trading decision model of the system is integrated within a master-slave game framework,utilizing an improved differential evolution algorithm in conjunction with the distributed equilibrium method of quadratic programming for solution.The calculation example demonstrates that the strategy safeguards the benefits for both parties in the game and achieves energy savings and carbon reduction for the system.展开更多
Dear Editor,Sleep plays a vital role in physical health,influencing chronic diseases,memory,and overall quality of life[1,2].In recent years,the relationship between sleep health and physical activity has gained atten...Dear Editor,Sleep plays a vital role in physical health,influencing chronic diseases,memory,and overall quality of life[1,2].In recent years,the relationship between sleep health and physical activity has gained attention,with a particular focus on how daily step count affects various sleep metrics.展开更多
Today,the world is undergoing extremely rapid and profound changes.The Two Sessions held each March in Beijing provide an excellent opportunity to review the changes taking place in the world,reflect on the path China...Today,the world is undergoing extremely rapid and profound changes.The Two Sessions held each March in Beijing provide an excellent opportunity to review the changes taking place in the world,reflect on the path China has taken,its achievements and challenges,and evaluate future steps.展开更多
Advancements in artificial intelligence and big data technologies have led to the gradual emergence of intelligent ships,which are expected to dominate the future of maritime transportation.Supporting the navigation o...Advancements in artificial intelligence and big data technologies have led to the gradual emergence of intelligent ships,which are expected to dominate the future of maritime transportation.Supporting the navigation of intelligent ships,route planning technologies have developed many route planning algorithms that prioritize economy and safety.This paper conducts an in-depth study of algorithm efficiency for a route planning problem,proposing an intelligent ship route planning algorithm based on the adaptive step size Informed-RRT^(*).This algorithm can quickly plan a short route according to automatic obstacle avoidance and is suitable for planning the routes of intelligent ships.Results show that the adaptive step size Informed-RRT^(*) algorithm can shorten the optimal route length by approximately 13.05%while ensuring the running time of the planning algorithm and avoiding approximately 23.64%of redundant sampling nodes.The improved algorithm effectively circumvents unnecessary calculations and reduces a large amount of redundant sampling data,thus improving the efficiency of route planning.In a complex water environment,the unique adaptive step size mechanism enables this algorithm to prevent restricted search tree expansion,showing strong search ability and robustness,which is of practical significance for the development of intelligent ships.展开更多
Bionic microfluidics is garnering increasing attention due to the superior fluidic performance enabled by biomimetic microstructures.Inspired by the unique structures of young pumpkin stems,we fabricate helicoidally p...Bionic microfluidics is garnering increasing attention due to the superior fluidic performance enabled by biomimetic microstructures.Inspired by the unique structures of young pumpkin stems,we fabricate helicoidally patterned microchannels with precisely controlled morphologies using the projection micro-stereolithography(PμSL)-based 3D printing technique.Our helicoidally patterned microchannels achieve approximately twice the liquid lifting height compared to similarly sized smooth microchannels.This improvement is attributed to the enhanced capillary force.The additional meniscus formed between the helicoidally patterned microstructures significantly contributes to the increased capillary effects.Furthermore,the underlying mechanisms of fluidic performance in helicoidally patterned microchannels are theorized using a newly developed equation,which is also employed to optimize the geometric parameters and fluidic performance of the biomimetic helicoidal microchannels.Additionally,our biomimetic helicoidally patterned microchannels facilitate a significant step-lifting phenomenon,mimicking tall trees'transpiration.The fluidic performance of our biomimetic helicoidally patterned microchannels show promise for applications in enhanced liquid lifting,step-lifting,clean-water production,and others.展开更多
文摘The present study focuses on the flow of a yield-stress(Bingham)nanofluid,consisting of suspended Fe3O4 nanoparticles,subjected to a magnetic field in a backward-facing step duct(BFS)configuration.The duct is equipped with a cylindrical obstacle,where the lower wall is kept at a constant temperature.The yield-stress nanofluid enters this duct at a cold temperature with fully developed velocity.The aim of the present investigation is to explore the influence of flow velocity(Re=10 to 200),nanoparticle concentration(ϕ=0 to 0.1),magnetic field intensity(Ha=0 to 100),and its inclination angle(γ=0 to 90)and nanofluid yield stress(Bn=0 to 20)on the thermal and hydrodynamic efficiency inside the backward-facing step.The numerical results have been obtained by resolving the momentum and energy balance equations using the Galerkin finite element method.The obtained results have indicated that an increase in Reynolds number and nanoparticle volume fraction enhances heat transfer.In contrast,a significant reduction is observed with an increase in Hartmann and Bingham numbers,resulting in quasi-immobilization of the fluid under the magnetic influence and radical solidification of this type of fluid,accompanied by the suppression of the vortex zone downstream of the cylindrical obstacle.This study sheds light on the complexity of this magnetically influenced fluid,with potential implications in various engineering and materials science fields.
基金Sponsored by the Natural Science Foundation of Shaanxi Province (Grant No. S2025-JC-YB-0532)the Practice and Innovation Funds for Graduate Students of Northwestern Polytechnical University (PF2024044)
文摘Taking a C1x motor with a backward-facing step which can generate a typical corner vortex as a reference,a numerical methodology using large eddy simulation was established in this study.Based on this methodology,the position of the backward-facing step of the motor was computed and analyzed to determine a basic configuration.Two key geometrical parameters,the head cavity angle and submerged nozzle cavity height,were subsequently introduced.Their effects on the corner vortex motion and their interactions with the acoustic pressure downstream of the backward-facing step were analyzed.The phenomena of vortex acoustic coupling and characteristics of pressure oscillations were further explored.The results show that the maximum error between the simulations and experimental data on the dominant frequency of pressure oscillations is 5.23%,which indicates that the numerical methodology built in this study is highly accurate.When the step is located at less than 5/8 of the total length of the combustion chamber,vortex acoustic coupling occurs,which can increase the pressure oscillations in the motor.Both the vorticity and the scale of vortices in the downstream step increase when the head cavity angle is greater than 24°,which increases the amplitude of the pressure oscillation by maximum 63.0%.The submerged nozzle cavity mainly affects the vortices in the cavity itself rather than those in the downstream step.When the height of the cavity increases from 10 to 20 mm,the pressure oscillation amplitude under the main frequency increases by 39.1%.As this height continues to increase,the amplitude of pressure oscillations increases but the primary frequency decreases.
文摘The events of the preceding two years have restructured the traditional systems of global governance which have dominated the international order since 1945.
文摘AS a metropolitan resident who is used to seeing towering buildings, an incessant stream of vehicles and people, I’ve always longed to have a taste of an ancient civilization, which is vigorous but exquisite, bold but elegant, natural but mysterious. I realized my dream when I went to Xi’an, a capital with a history of over 1,000 years. Xi’an was once the capital for eleven dynasties, including the Zhou, Qin, Han and Tang. This is the place where China’s ancient civilization developed. Ancestors at Banpo created exquisite painted pottery; the Western Zhou Dynasty (about 1,066-771 B.C.) saw the height of the splendors of the bronze culture; the Qin Emperor Shi Huang (Qin Dynasty, from about 221-206 B.C.)
文摘The paper presents our contribution to the full 3D finite element modelling of a hybrid stepping motor using COMSOL Multiphysics software. This type of four-phase motor has a permanent magnet interposed between the two identical and coaxial half stators. The calculation of the field with or without current in the windings (respectively with or without permanent magnet) is done using a mixed formulation with strong coupling. In addition, the local high saturation of the ferromagnetic material and the radial and axial components of the magnetic flux are taken into account. The results obtained make it possible to clearly observe, as a function of the intensity of the bus current or the remanent induction, the saturation zones, the lines, the orientations and the magnetic flux densities. 3D finite element modelling provide more accurate numerical data on the magnetic field through multiphysics analysis. This analysis considers the actual operating conditions and leads to the design of an optimized machine structure, with or without current in the windings and/or permanent magnet.
文摘A robust adaptive control approach is presented to improve the performance of the control scheme proposed in the authors＇ previous work, aiming at producing a low ripple hybrid stepping motor servo drive for precision profile tracking at a low speed. In order to construct a completely integrated control design philosophy to reduce torque ripple and at the same time to enhance tracking performance, the properties of nonlinear uncertainties in the system dynamics are uncovered, and then incorporated into the design of the controller. The system uncertainties concerned with ripple dynamics and other external disturbances are composed of two categories. The first category of uncertainties with linear parameterization arising from the detention effect is dealt with by the wellknown adaptive control method. A robust adaptive method is used to deal with the second category of uncertainties resulting from the non-sinusoidal flux distribution. The μ-modification scheme is used to cease parameter adaptation by the robust adaptive control law, thus ensuring that the trajectory tracking error asymptotically converges to a pre-specified boundary. Experiments are performed with a typical hybrid stepping motor to test its profile tracking accuracy. Results confirm the proposed control scheme.
基金National Natural Science Foundation of China,Grant/Award Number:42330719National Natural Science Foundation of China,Grant/Award Number:U2443228+1 种基金Power Construction Corporation of China,Grant/Award Number:DJ-ZDXM-2021-51China Institute of Water Resources and Hydropower Research,Grant/Award Number:GE121003A0042022。
文摘Check dams are widely constructed on China's Loess Plateau,which had a total number of 58,776 by the end of 2019.Great achievements in check dam construction have been gained regarding the economic and environmental impacts.This study reviews the remarkable benefits of check dams on the land reclamation and environmental improvement on the Loess Plateau,and sediment reduction entering the Yellow River.However,the flood incidents on check dams have been frequently reported for the past decades,which has attracted more attention in the context of climate change and extreme rainfall events recently.Advances in the flood migration techniques achieved by the research group led by the first author have been highlighted to migrate the breach risk of check dams due to floods.The“family tree method”has been proposed to determine the survival status and critical rainfall threshold of each check dam in the complicated dam system.An updated dam breach flood evaluation framework and the corresponding numerical algorithm(i.e.,DB-IWHR)have been developed.Moreover,innovative types of water-release facilities for check dams,including geobag stepped spillway and prestressed concrete cylinder pipe in the underlying conduit,have been proposed and developed.Finally,the perspectives concerning the check dam construction on the Loess Plateau have been put forward.
文摘悦读·明其义Conquering challenges,embracing growth克服挑战,拥抱成长Personal growth is a continuous journey that involves learning and overcoming challenges.It helps us develop our skills and achieve our goals.For many,the journey begins with stepping out of our comfort zones and facing new challenges.Understanding ourselves is very important for personal growth.By knowing our strengths and weaknesses,we can find areas to improve.For example,if you have trouble speaking in public,you can join a speech club or practice in front of a mirror.This kind of self⁃reflection helps us see our limitations and turn them into opportunities for growth.
基金funded by grants from the Fonds de Recherche du Quebec-Nature et Technologies(FRQNT)to NJthe Ontario Ministry of Natural Resources and Forestrythe Ontario Ministry of Environment,Conservation and Parks,and the Natural Sciences and Engineering Research Council(NSERC)of Canada to DMG.
文摘Animals can differ in their individual movement behaviors during their daily displacements.Studies of animal movement patterns often disregard the need to understand individual variation in these patterns and the role of this variation in shaping population distributions of movements.To assess the link between individual movements and population distributions,we radio-tracked 13 Fowler's Toads Anaxyrus fowleri in Long Point,Ontario,Canada,after their breeding season.We recorded individual coordinates every 30 min,from the moment they emerged from their burrows around dusk until they burrowed in the morning,and obtained a total of 157 movements.We used the resulting series of step lengths and turning angles in a Hidden Markov Model to estimate movement type as"directed"or"non-directed"We also assigned to each encounter one of 3 space-dependent movement states:"foraging""in transit'or"searching"and found that movement type and state switched within individuals irrespective of time during a single night.We find that switching between movement types varied throughout the night,leading to stochastic within-individual variation in movements,and the distribution of movement distances differed significantly among individuals.Movement states,however,were time-dependent,suggesting displacement routines were similar across individuals.Variation in movement behavior within individuals scales up to result in variation among individuals which,in turn,was found to shape the distribution of the sampled population.Our findings therefore underline the importance of a multi-scale approach in the study of movement.
文摘Upgrading of abundant cellulosic biomass to isosorbide can reduce the dependence on limited fossil resources and provide a sustainable way to produce isosorbide,utilized for polymers,medicine and health care product synth-esis.This review comprehensively examines the key steps and catalytic systems involved in the conversion of cel-lulose to isosorbide.Initially,the reaction pathway from cellulose to isosorbide is elucidated,emphasizing three critical steps:cellulose hydrolysis,glucose hydrogenation,and the two-step dehydration of sorbitol to produce isosorbide.Additionally,the activation energy and acidic sites during cellulose hydrolysis,the impact of metal particle size and catalyst support on hydrogenation,and the effects of catalyst acidity,pore structure,and reaction conditions on sorbitol dehydration have been thoroughly examined.Finally,the progress made in cellulose con-version to isosorbide is summarized,current challenges are highlighted,and future development trends are pro-jected in this review.
文摘As the beauty sector of China steps into a high-quality development stage,compliance has been an unavoidable topic in the industry.After the implementation of Regulations on Cosmetic Products Supervision and Management,a number of supporting regulations were published to make more strict and specific requirements on new product filing,efficacy claims,and label renewal.Each implementation of the regulations brings an elimination process.
文摘China will diligently work towards peaking carbon dioxide emissions before 2030 and achieving carbon neutrality before 2060,according to the Government Work Report delivered at the opening of the third session of the 14th National People’s Congress in Beijing on 5 March.The country will take steps to respond to green trade barriers as it advances towards carbon neutrality,the report states.
基金supported by the National Natural Science Foundation of China(No.52077137).
文摘Against the backdrop of China’s“dual-carbon”target,clean energy generation currently accounts for about 3.8 trillion kilowatt-hours,or 39.7 percent of total power generation,establishing a reasonable market trading mechanism while enhancing the low-carbon economic benefits of the integrated energy system(IES)and optimizing the interests of various entities within the distribution system has become a significant challenge.Consequently,this paper proposes an optimization strategy for a low-carbon economy within a multi-agent IES that considers carbon capture systems(CCS)and power-to-gas(P2G).In this framework,the integrated energy system operator(IESO)acts as the primary leader,while energy suppliers(ES),energy storage operators(ESO),and load aggregators(LA)follow.At the level of low-carbon technology,a coupling model of P2G and CCS is developed,leading to the establishment of an IES that incorporates energy conversion and storage equipment.Economically,effective control of system carbon emissions in market trading is progressively established.Lastly,the trading decision model of the system is integrated within a master-slave game framework,utilizing an improved differential evolution algorithm in conjunction with the distributed equilibrium method of quadratic programming for solution.The calculation example demonstrates that the strategy safeguards the benefits for both parties in the game and achieves energy savings and carbon reduction for the system.
文摘Dear Editor,Sleep plays a vital role in physical health,influencing chronic diseases,memory,and overall quality of life[1,2].In recent years,the relationship between sleep health and physical activity has gained attention,with a particular focus on how daily step count affects various sleep metrics.
文摘Today,the world is undergoing extremely rapid and profound changes.The Two Sessions held each March in Beijing provide an excellent opportunity to review the changes taking place in the world,reflect on the path China has taken,its achievements and challenges,and evaluate future steps.
文摘Advancements in artificial intelligence and big data technologies have led to the gradual emergence of intelligent ships,which are expected to dominate the future of maritime transportation.Supporting the navigation of intelligent ships,route planning technologies have developed many route planning algorithms that prioritize economy and safety.This paper conducts an in-depth study of algorithm efficiency for a route planning problem,proposing an intelligent ship route planning algorithm based on the adaptive step size Informed-RRT^(*).This algorithm can quickly plan a short route according to automatic obstacle avoidance and is suitable for planning the routes of intelligent ships.Results show that the adaptive step size Informed-RRT^(*) algorithm can shorten the optimal route length by approximately 13.05%while ensuring the running time of the planning algorithm and avoiding approximately 23.64%of redundant sampling nodes.The improved algorithm effectively circumvents unnecessary calculations and reduces a large amount of redundant sampling data,thus improving the efficiency of route planning.In a complex water environment,the unique adaptive step size mechanism enables this algorithm to prevent restricted search tree expansion,showing strong search ability and robustness,which is of practical significance for the development of intelligent ships.
基金supported by National Natural Science Foundation of China through Grant Nos.52495000,52332012 and 52176093partially supported by Beijing Huiyangdao Health Technology Co.,Ltd。
文摘Bionic microfluidics is garnering increasing attention due to the superior fluidic performance enabled by biomimetic microstructures.Inspired by the unique structures of young pumpkin stems,we fabricate helicoidally patterned microchannels with precisely controlled morphologies using the projection micro-stereolithography(PμSL)-based 3D printing technique.Our helicoidally patterned microchannels achieve approximately twice the liquid lifting height compared to similarly sized smooth microchannels.This improvement is attributed to the enhanced capillary force.The additional meniscus formed between the helicoidally patterned microstructures significantly contributes to the increased capillary effects.Furthermore,the underlying mechanisms of fluidic performance in helicoidally patterned microchannels are theorized using a newly developed equation,which is also employed to optimize the geometric parameters and fluidic performance of the biomimetic helicoidal microchannels.Additionally,our biomimetic helicoidally patterned microchannels facilitate a significant step-lifting phenomenon,mimicking tall trees'transpiration.The fluidic performance of our biomimetic helicoidally patterned microchannels show promise for applications in enhanced liquid lifting,step-lifting,clean-water production,and others.
