In this note, we study zeroes of Clifford algebra-valued polynomials. We prove that if such a polynomial has only real coefficients, then it has two types of zeroes： the real isolated zeroes and the spherical conjuga...In this note, we study zeroes of Clifford algebra-valued polynomials. We prove that if such a polynomial has only real coefficients, then it has two types of zeroes： the real isolated zeroes and the spherical conjugate ones. The total number of zeroes does not exceed the degree of the polynomial. We also present a technique for computing the zeroes.展开更多
The purpose of ibis paper is to study the distribution of zerocs of solutions of theneutral delay differential equations. An estimate is estublished for the distween betweenadjacenlt zeroes of the solutions of such eq...The purpose of ibis paper is to study the distribution of zerocs of solutions of theneutral delay differential equations. An estimate is estublished for the distween betweenadjacenlt zeroes of the solutions of such equations under less restritive hypotheses on the variable coefficients.The results obtained improve and extend scme known resultsin the literature.展开更多
While desalination is a key solution for global freshwater scarcity,its implementation faces environmental challenges due to concentrated brine byproducts mainly disposed of via coastal discharge systems.Solar interfa...While desalination is a key solution for global freshwater scarcity,its implementation faces environmental challenges due to concentrated brine byproducts mainly disposed of via coastal discharge systems.Solar interfacial evaporation offers sustainable management potential,yet inevitable salt nucleation at evaporation interfaces degrades photothermal conversion and operational stability via light scattering and pathway blockage.Inspired by the mangrove leaf,we propose a photothermal 3D polydopamine and polypyrrole polymerized spacer fabric(PPSF)-based upward hanging model evaporation configuration with a reverse water feeding mechanism.This design enables zero-liquiddischarge(ZLD)desalination through phase-separation crystallization.The interconnected porous architecture and the rough surface of the PPSF enable superior water transport,achieving excellent solar-absorbing efficiency of 97.8%.By adjusting the tilt angle(θ),the evaporator separates the evaporation and salt crystallization zones via controlled capillary-driven brine transport,minimizing heat dissipation from brine discharge.At an optimal tilt angle of 52°,the evaporator reaches an evaporation rate of 2.81 kg m^(−2) h^(−1) with minimal heat loss(0.366 W)under 1-sun illumination while treating a 7 wt%waste brine solution.Furthermore,it sustains an evaporation rate of 2.71 kg m^(−2) h^(−1) over 72 h while ensuring efficient salt recovery.These results highlight a scalable,energy-efficient approach for sustainable ZLD desalination.展开更多
With more and more IoT terminals being deployed in various power grid business scenarios,terminal reliability has become a practical challenge that threatens the current security protection architecture.Most IoT termi...With more and more IoT terminals being deployed in various power grid business scenarios,terminal reliability has become a practical challenge that threatens the current security protection architecture.Most IoT terminals have security risks and vulnerabilities,and limited resources make it impossible to deploy costly security protection methods on the terminal.In order to cope with these problems,this paper proposes a lightweight trust evaluation model TCL,which combines three network models,TCN,CNN,and LSTM,with stronger feature extraction capability and can score the reliability of the device by periodically analyzing the traffic behavior and activity logs generated by the terminal device,and the trust evaluation of the terminal’s continuous behavior can be achieved by combining the scores of different periods.After experiments,it is proved that TCL can effectively use the traffic behaviors and activity logs of terminal devices for trust evaluation and achieves F1-score of 95.763,94.456,99.923,and 99.195 on HDFS,BGL,N-BaIoT,and KDD99 datasets,respectively,and the size of TCL is only 91KB,which can achieve similar or better performance than CNN-LSTM,RobustLog and other methods with less computational resources and storage space.展开更多
Hainan Province in south China is the country’s second-largest island and the largest free trade port by area.It has entered a historic phase in China’s drive to promote high-level institutional opening up.On 18 Dec...Hainan Province in south China is the country’s second-largest island and the largest free trade port by area.It has entered a historic phase in China’s drive to promote high-level institutional opening up.On 18 December 2025,Hainan officially launched island-wide special customs operations,commonly referred to as“customs closure.”From that date,goods entering or leaving the island,except those traded with the Chinese mainland,are subject to simplified customs procedures and potentially reduced or zero tariffs.展开更多
Since the launch of island-wide special customs operations at Hainan Free Trade Port(Hainan FTP),the proportion of “zero-tariff”imported goods has increased significantly from 21 to 74 percent, and high-quality good...Since the launch of island-wide special customs operations at Hainan Free Trade Port(Hainan FTP),the proportion of “zero-tariff”imported goods has increased significantly from 21 to 74 percent, and high-quality goods from Southeast Asia can enter Hainan at a more competitive price. If goods contain imported materials and achieve at least 30 percent added value through local processing,they can enter the Chinese mainland market with an exemption from import tariffs, effectively gaining market access across China.展开更多
2026年1月31日-2月4日,美国供热、制冷与空调工程师学会(ASHRAE)2026年冬季会议在美国拉斯维加斯隆重召开。来自全球数十个国家的行业专家、学者及工程师齐聚一堂,共同探讨建筑环境系统与能源工程领域的前沿技术与发展趋势。会议期间,AS...2026年1月31日-2月4日,美国供热、制冷与空调工程师学会(ASHRAE)2026年冬季会议在美国拉斯维加斯隆重召开。来自全球数十个国家的行业专家、学者及工程师齐聚一堂,共同探讨建筑环境系统与能源工程领域的前沿技术与发展趋势。会议期间,ASHRAE学会正式颁发了2026年度“Engineering Global Net Zero”创新奖。“Engineering Global Net Zero”创新奖(Innovation Award 2026)旨在表彰全球范围内在推动建筑环境领域可持续发展与技术创新方面作出卓越贡献的杰出个人,该奖项由美国供热、制冷与空调工程师学会(ASHRAE)组织评议。展开更多
The United Nations Sustainable Development Goal(SDG) 2 aims to achieve Zero Hunger by 2030.However,global hunger and food insecurity have continued to rise at an alarming rate(UN 2023).Subtropical regions are home to ...The United Nations Sustainable Development Goal(SDG) 2 aims to achieve Zero Hunger by 2030.However,global hunger and food insecurity have continued to rise at an alarming rate(UN 2023).Subtropical regions are home to more than 30% of the world's population,predominantly in developing countries where per capita farmland and food supply are only 40% of those in developed nations(FAO 2018).Meeting the Zero Hunger target amid ongoing population growth in these regions requires a substantial increase in agricultural production while minimizing soil degradation and adverse ecological impacts.This challenge is shared by many countries across South Asia,Africa,and Central and South America.展开更多
China launches island-wide special customs operations in Hainan FTP.China launched island-wide special customs operations in the Hainan Free Trade Port(FTP),the world’s largest FTP by area,on December 18,2025,allowin...China launches island-wide special customs operations in Hainan FTP.China launched island-wide special customs operations in the Hainan Free Trade Port(FTP),the world’s largest FTP by area,on December 18,2025,allowing freer entry of overseas goods,expanding zerotariff coverage,and introducing more business-friendly measures.展开更多
Hilly terrain pipeline is a common form of pipeline in oil and gas storage and transportation industry.Due to the hilly terrain influence, the liquid at the elbow of the gathering pipeline is easy to flow back and acc...Hilly terrain pipeline is a common form of pipeline in oil and gas storage and transportation industry.Due to the hilly terrain influence, the liquid at the elbow of the gathering pipeline is easy to flow back and accumulate to form slug flow, so it is necessary to remove the accumulated liquid by gas purging. In this paper, experiment is carried out in hilly terrain pipelines. Three flow patterns of stratified flow, slug flow and stratified entrained flow are observed. The process of gas purging accumulated liquid is divided into four stages, namely liquid accumulation, liquid rising, continuous outflow and tail outflow. At the same time, the flow pattern maps of each stage are drawn. The pressure drop signal is analyzed in time domain and frequency domain, and the contour map of pressure drop distribution is drawn. It is found that the ratio of range to average value can well distinguish the occurrence range of each flow pattern.Based on visualization, the transition process of slug flow to stratified flow and stratified entrained flow is studied, and the transition boundary prediction model is established. An image processing method is proposed to convert the image signal into a similarity curve, and PSD analysis is performed to calculate the slug frequency. The normal distribution is used to fit the slug frequency, and the predicted correlation is in good agreement with the experimental data.展开更多
One of the pathways to attain NET ZERO is CO_(2)injection into deep saline aquifers(DSAs),which alters the saturation and pore pressure of the reservoir rocks,hence the effective stress,sʹ.This,in turn,would change th...One of the pathways to attain NET ZERO is CO_(2)injection into deep saline aquifers(DSAs),which alters the saturation and pore pressure of the reservoir rocks,hence the effective stress,sʹ.This,in turn,would change their geomechanical(i.e.peak deviatoric stress,elastic modulus,Poisson's ratio)and petrophysical(porosity and permeability)properties.Such a situation might trigger geo-hazards,like induced seismicity,ground deformation,caprock failure.Hence,reducing the risk of such hazards necessitates quantifying the spatial and temporal changes in sʹ,under specific CO_(2)and/or brine saturation,designated as S_(CO2)and S_(b),respectively,and resultant pore pressure.With this in view,a conceptual model depicting the reservoir,demarcated by five zones based on variations in saturation,pore-pressure,temperature,etc.,and the corresponding effective stress equations have been proposed based on the available literature.Furthermore,a critical review of literature has been carried out to decipher the limitations and contradictions associated with the findings from(i)laboratory studies to estimate S_(CO2)employing pwave velocity and electrical resistivity,(ii)analytical and numerical approaches for estimating the variation of pore-pressure in the reservoir rocks,and(iii)laboratory studies on variation in geomechanical and petrophysical properties under the conditions representative of the above-mentioned zones of the conceptual model.The authors consider that extensive experiments should be conducted on the rocks from different sources and tested under various conditions of the CO_(2)injection to validate the proposed model for the execution of risk-free CO_(2)storage in DSAs.展开更多
We study the two-dimensional(2D)Cauchy problem of nonhomogeneous Boussinesq system for magnetohydrodynamics convection without heat diffusion in the whole plane.Based on delicate weighted estimates,we derive the globa...We study the two-dimensional(2D)Cauchy problem of nonhomogeneous Boussinesq system for magnetohydrodynamics convection without heat diffusion in the whole plane.Based on delicate weighted estimates,we derive the global existence and uniqueness of strong solutions.In particular,the initial data can be arbitrarily large and the initial density may contain vacuum states and even have compact support.展开更多
When the proton exchange membrane fuel cell(PEMFC)system is running,there will be a condition that does not require power output for a short time.In order to achieve zero power output under low power consumption,it is...When the proton exchange membrane fuel cell(PEMFC)system is running,there will be a condition that does not require power output for a short time.In order to achieve zero power output under low power consumption,it is necessary to consider the diversity of control targets and the complexity of dynamic models,which brings the challenge of high-precision tracking control of the stack output power and cathode intake flow.For system idle speed control,a modelbased nonlinear control framework is constructed in this paper.Firstly,the nonlinear dynamic model of output power and cathode intake flow is derived.Secondly,a control scheme combining nonlinear extended Kalman filter observer and state feedback controller is designed.Finally,the control scheme is verified on the PEMFC experimental platform and compared with the proportion-integration-differentiation(PID)controller.The experimental results show that the control strategy proposed in this paper can realize the idle speed control of the fuel cell system and achieve the purpose of zero power output.Compared with PID controller,it has faster response speed and better system dynamics.展开更多
Dear Editor,This letter focuses on how an attacker can design suitable improved zero-dynamics (ZD) attack signal based on state estimates of target system. Improved ZD attack is to change zero dynamic gain matrix of a...Dear Editor,This letter focuses on how an attacker can design suitable improved zero-dynamics (ZD) attack signal based on state estimates of target system. Improved ZD attack is to change zero dynamic gain matrix of attack signal to a matrix with determinant greater than 1.展开更多
The concept of Net Zero Carbon Buildings,which aims to reduce greenhouse gas emissions,is essential in addressing climate change.However,the development of such buildings in Thailand faces significant challenges,inclu...The concept of Net Zero Carbon Buildings,which aims to reduce greenhouse gas emissions,is essential in addressing climate change.However,the development of such buildings in Thailand faces significant challenges,including high construction costs,uncertain returns,and limited investment incentives.This study explores the factors influencing real estate developers’decisions to pursue Net Zero Carbon Buildings in Thailand,with a focus on physical,financial,and policy-related elements.Data collection was done with 388 respondents who are stakeholders,including developers,consultants,designers,and sustainability experts,through an online questionnaire,and analyzed using Multiple Regression Analysis.The independent variables in the analytical model consist of three groups of factors:physical buildings,climate finance,and climate policy.The results indicate that physical building factors,including building age,engineering systems,and design;climate finance factors,such as project cost increases,financial returns,and investment incentives;and climate policy factors,including government policies,international climate agreements,and carbon taxes,significantly influence development decisions.Government policies,building engineering systems,and financial incentives were identified as key positive drivers for investment,while carbon taxes and energy efficiency-focused designs were found to potentially discourage investment due to higher costs.The study concludes that substantial government support such as tax incentives,grants,and low-interest financing is critical to fostering investment in Net Zero Carbon Buildings.Additionally,raising awareness among developers and the private sector about the long-term benefits of these projects is essential to strengthening investment incentives.展开更多
In the context of an increasingly severe cybersecurity landscape and the growing complexity of offensive and defen-sive techniques,Zero Trust Networks(ZTN)have emerged as a widely recognized technology.Zero Trust not ...In the context of an increasingly severe cybersecurity landscape and the growing complexity of offensive and defen-sive techniques,Zero Trust Networks(ZTN)have emerged as a widely recognized technology.Zero Trust not only addresses the shortcomings of traditional perimeter security models but also consistently follows the fundamental principle of“never trust,always verify.”Initially proposed by John Cortez in 2010 and subsequently promoted by Google,the Zero Trust model has become a key approach to addressing the ever-growing security threats in complex network environments.This paper systematically compares the current mainstream cybersecurity models,thoroughly explores the advantages and limitations of the Zero Trust model,and provides an in-depth review of its components and key technologies.Additionally,it analyzes the latest research achievements in the application of Zero Trust technology across various fields,including network security,6G networks,the Internet of Things(IoT),and cloud computing,in the context of specific use cases.The paper also discusses the innovative contributions of the Zero Trust model in these fields,the challenges it faces,and proposes corresponding solutions and future research directions.展开更多
Understanding crash contributing factors is essential in safety management and improvement. These factors drive investment decisions, policies, regulations, and other safety-related initiatives. This paper analyzes fa...Understanding crash contributing factors is essential in safety management and improvement. These factors drive investment decisions, policies, regulations, and other safety-related initiatives. This paper analyzes factors that contribute to crash occurrence based on two national datasets in the United States (CISS and NASS-CDS) for the years 2017-2022 and 2010-2015, respectively. Three taxonomies were applied to enhance understanding of the various crash contributing factors. These taxonomies were developed based on previous research and practice and involved different groupings of human factors, vehicle factors, and roadway and environmental factors. Statistics for grouping the different types of factors and statistics for specific factors are provided. The results indicate that human factors are present in over 95% of crashes, roadway and environmental factors are present in over 45% of crashes, and vehicle factors are present in less than 2% of crashes. Regarding factors related to human error and vehicle maintenance, speeding is involved in over 25% of crashes, distraction is involved in over 20% of crashes, alcohol and drugs are involved in over 9% of crashes, and vehicle maintenance is involved in approximately 0.45% of crashes. Approximately 4.4% of crashes involve a driver who “looked but did not see.” Weather is involved in over 13% of crashes. Conclusions: The findings indicate that, consistent with previous research, human factors or human error are present in around 95% of crashes. Infrastructure and environmental factors contribute to about 45% of crashes. Vehicle factors contribute to only 1.67% - 1.71% of crashes. The results from this study could potentially be used to inform future safety management and improvement activities, including policy-making, regulation development, safe systems and systemic safety approaches to safety management, and other engineering, education, emergency response, enforcement, evaluation, and encouragement activities. The findings could also be used in the development of future Driver Assistance Technologies (DAT) systems and in enhancing existing technologies.展开更多
基金sponsored by the National Natural ScienceFunds for Young Scholars (10901166)the Scientific Research Foundation for the Youth Scholars of Sun Yat-SenUniversitythe Research Grant of University of Macao on Applications of Hyper-Complex Analysis (cativo:7560)
文摘In this note, we study zeroes of Clifford algebra-valued polynomials. We prove that if such a polynomial has only real coefficients, then it has two types of zeroes： the real isolated zeroes and the spherical conjugate ones. The total number of zeroes does not exceed the degree of the polynomial. We also present a technique for computing the zeroes.
文摘The purpose of ibis paper is to study the distribution of zerocs of solutions of theneutral delay differential equations. An estimate is estublished for the distween betweenadjacenlt zeroes of the solutions of such equations under less restritive hypotheses on the variable coefficients.The results obtained improve and extend scme known resultsin the literature.
基金supported by National Key Research and Development Program of China(2022YFB3804902,2022YFB3804900)the National Natural Science Foundation of China(52203226,52161145406,42376045)the Fundamental Research Funds for the Central Universities(2232024Y-01,2232025D-02).
文摘While desalination is a key solution for global freshwater scarcity,its implementation faces environmental challenges due to concentrated brine byproducts mainly disposed of via coastal discharge systems.Solar interfacial evaporation offers sustainable management potential,yet inevitable salt nucleation at evaporation interfaces degrades photothermal conversion and operational stability via light scattering and pathway blockage.Inspired by the mangrove leaf,we propose a photothermal 3D polydopamine and polypyrrole polymerized spacer fabric(PPSF)-based upward hanging model evaporation configuration with a reverse water feeding mechanism.This design enables zero-liquiddischarge(ZLD)desalination through phase-separation crystallization.The interconnected porous architecture and the rough surface of the PPSF enable superior water transport,achieving excellent solar-absorbing efficiency of 97.8%.By adjusting the tilt angle(θ),the evaporator separates the evaporation and salt crystallization zones via controlled capillary-driven brine transport,minimizing heat dissipation from brine discharge.At an optimal tilt angle of 52°,the evaporator reaches an evaporation rate of 2.81 kg m^(−2) h^(−1) with minimal heat loss(0.366 W)under 1-sun illumination while treating a 7 wt%waste brine solution.Furthermore,it sustains an evaporation rate of 2.71 kg m^(−2) h^(−1) over 72 h while ensuring efficient salt recovery.These results highlight a scalable,energy-efficient approach for sustainable ZLD desalination.
基金supported by National Key R&D Program of China(No.2022YFB3105101).
文摘With more and more IoT terminals being deployed in various power grid business scenarios,terminal reliability has become a practical challenge that threatens the current security protection architecture.Most IoT terminals have security risks and vulnerabilities,and limited resources make it impossible to deploy costly security protection methods on the terminal.In order to cope with these problems,this paper proposes a lightweight trust evaluation model TCL,which combines three network models,TCN,CNN,and LSTM,with stronger feature extraction capability and can score the reliability of the device by periodically analyzing the traffic behavior and activity logs generated by the terminal device,and the trust evaluation of the terminal’s continuous behavior can be achieved by combining the scores of different periods.After experiments,it is proved that TCL can effectively use the traffic behaviors and activity logs of terminal devices for trust evaluation and achieves F1-score of 95.763,94.456,99.923,and 99.195 on HDFS,BGL,N-BaIoT,and KDD99 datasets,respectively,and the size of TCL is only 91KB,which can achieve similar or better performance than CNN-LSTM,RobustLog and other methods with less computational resources and storage space.
文摘Hainan Province in south China is the country’s second-largest island and the largest free trade port by area.It has entered a historic phase in China’s drive to promote high-level institutional opening up.On 18 December 2025,Hainan officially launched island-wide special customs operations,commonly referred to as“customs closure.”From that date,goods entering or leaving the island,except those traded with the Chinese mainland,are subject to simplified customs procedures and potentially reduced or zero tariffs.
文摘Since the launch of island-wide special customs operations at Hainan Free Trade Port(Hainan FTP),the proportion of “zero-tariff”imported goods has increased significantly from 21 to 74 percent, and high-quality goods from Southeast Asia can enter Hainan at a more competitive price. If goods contain imported materials and achieve at least 30 percent added value through local processing,they can enter the Chinese mainland market with an exemption from import tariffs, effectively gaining market access across China.
文摘2026年1月31日-2月4日,美国供热、制冷与空调工程师学会(ASHRAE)2026年冬季会议在美国拉斯维加斯隆重召开。来自全球数十个国家的行业专家、学者及工程师齐聚一堂,共同探讨建筑环境系统与能源工程领域的前沿技术与发展趋势。会议期间,ASHRAE学会正式颁发了2026年度“Engineering Global Net Zero”创新奖。“Engineering Global Net Zero”创新奖(Innovation Award 2026)旨在表彰全球范围内在推动建筑环境领域可持续发展与技术创新方面作出卓越贡献的杰出个人,该奖项由美国供热、制冷与空调工程师学会(ASHRAE)组织评议。
文摘The United Nations Sustainable Development Goal(SDG) 2 aims to achieve Zero Hunger by 2030.However,global hunger and food insecurity have continued to rise at an alarming rate(UN 2023).Subtropical regions are home to more than 30% of the world's population,predominantly in developing countries where per capita farmland and food supply are only 40% of those in developed nations(FAO 2018).Meeting the Zero Hunger target amid ongoing population growth in these regions requires a substantial increase in agricultural production while minimizing soil degradation and adverse ecological impacts.This challenge is shared by many countries across South Asia,Africa,and Central and South America.
文摘China launches island-wide special customs operations in Hainan FTP.China launched island-wide special customs operations in the Hainan Free Trade Port(FTP),the world’s largest FTP by area,on December 18,2025,allowing freer entry of overseas goods,expanding zerotariff coverage,and introducing more business-friendly measures.
基金supported by the Basic Science Center Program for Ordered Energy Conversion of the National Natural Science Foundation of China(No.52488201)the National Natural Science Foundation of China(No.52422606).
文摘Hilly terrain pipeline is a common form of pipeline in oil and gas storage and transportation industry.Due to the hilly terrain influence, the liquid at the elbow of the gathering pipeline is easy to flow back and accumulate to form slug flow, so it is necessary to remove the accumulated liquid by gas purging. In this paper, experiment is carried out in hilly terrain pipelines. Three flow patterns of stratified flow, slug flow and stratified entrained flow are observed. The process of gas purging accumulated liquid is divided into four stages, namely liquid accumulation, liquid rising, continuous outflow and tail outflow. At the same time, the flow pattern maps of each stage are drawn. The pressure drop signal is analyzed in time domain and frequency domain, and the contour map of pressure drop distribution is drawn. It is found that the ratio of range to average value can well distinguish the occurrence range of each flow pattern.Based on visualization, the transition process of slug flow to stratified flow and stratified entrained flow is studied, and the transition boundary prediction model is established. An image processing method is proposed to convert the image signal into a similarity curve, and PSD analysis is performed to calculate the slug frequency. The normal distribution is used to fit the slug frequency, and the predicted correlation is in good agreement with the experimental data.
基金The authors would like to acknowledge the grant of fellowship(DST/TMD/EWO/2K21/ACT/2021/02(G))under Project SHARP,received from the Department of Science and Technology,Government of India.
文摘One of the pathways to attain NET ZERO is CO_(2)injection into deep saline aquifers(DSAs),which alters the saturation and pore pressure of the reservoir rocks,hence the effective stress,sʹ.This,in turn,would change their geomechanical(i.e.peak deviatoric stress,elastic modulus,Poisson's ratio)and petrophysical(porosity and permeability)properties.Such a situation might trigger geo-hazards,like induced seismicity,ground deformation,caprock failure.Hence,reducing the risk of such hazards necessitates quantifying the spatial and temporal changes in sʹ,under specific CO_(2)and/or brine saturation,designated as S_(CO2)and S_(b),respectively,and resultant pore pressure.With this in view,a conceptual model depicting the reservoir,demarcated by five zones based on variations in saturation,pore-pressure,temperature,etc.,and the corresponding effective stress equations have been proposed based on the available literature.Furthermore,a critical review of literature has been carried out to decipher the limitations and contradictions associated with the findings from(i)laboratory studies to estimate S_(CO2)employing pwave velocity and electrical resistivity,(ii)analytical and numerical approaches for estimating the variation of pore-pressure in the reservoir rocks,and(iii)laboratory studies on variation in geomechanical and petrophysical properties under the conditions representative of the above-mentioned zones of the conceptual model.The authors consider that extensive experiments should be conducted on the rocks from different sources and tested under various conditions of the CO_(2)injection to validate the proposed model for the execution of risk-free CO_(2)storage in DSAs.
文摘We study the two-dimensional(2D)Cauchy problem of nonhomogeneous Boussinesq system for magnetohydrodynamics convection without heat diffusion in the whole plane.Based on delicate weighted estimates,we derive the global existence and uniqueness of strong solutions.In particular,the initial data can be arbitrarily large and the initial density may contain vacuum states and even have compact support.
基金Supported by the Major Science and Technology Projects in Jilin Province and Changchun City(20220301010GX).
文摘When the proton exchange membrane fuel cell(PEMFC)system is running,there will be a condition that does not require power output for a short time.In order to achieve zero power output under low power consumption,it is necessary to consider the diversity of control targets and the complexity of dynamic models,which brings the challenge of high-precision tracking control of the stack output power and cathode intake flow.For system idle speed control,a modelbased nonlinear control framework is constructed in this paper.Firstly,the nonlinear dynamic model of output power and cathode intake flow is derived.Secondly,a control scheme combining nonlinear extended Kalman filter observer and state feedback controller is designed.Finally,the control scheme is verified on the PEMFC experimental platform and compared with the proportion-integration-differentiation(PID)controller.The experimental results show that the control strategy proposed in this paper can realize the idle speed control of the fuel cell system and achieve the purpose of zero power output.Compared with PID controller,it has faster response speed and better system dynamics.
基金supported in part by the National Natural Science Foundation of China(61873106,62303109)Start-Up Research Fund of Southeast University(RF1028623002)Shenzhen Science and Technology Program(JCYJ20230807114609019)
文摘Dear Editor,This letter focuses on how an attacker can design suitable improved zero-dynamics (ZD) attack signal based on state estimates of target system. Improved ZD attack is to change zero dynamic gain matrix of attack signal to a matrix with determinant greater than 1.
文摘The concept of Net Zero Carbon Buildings,which aims to reduce greenhouse gas emissions,is essential in addressing climate change.However,the development of such buildings in Thailand faces significant challenges,including high construction costs,uncertain returns,and limited investment incentives.This study explores the factors influencing real estate developers’decisions to pursue Net Zero Carbon Buildings in Thailand,with a focus on physical,financial,and policy-related elements.Data collection was done with 388 respondents who are stakeholders,including developers,consultants,designers,and sustainability experts,through an online questionnaire,and analyzed using Multiple Regression Analysis.The independent variables in the analytical model consist of three groups of factors:physical buildings,climate finance,and climate policy.The results indicate that physical building factors,including building age,engineering systems,and design;climate finance factors,such as project cost increases,financial returns,and investment incentives;and climate policy factors,including government policies,international climate agreements,and carbon taxes,significantly influence development decisions.Government policies,building engineering systems,and financial incentives were identified as key positive drivers for investment,while carbon taxes and energy efficiency-focused designs were found to potentially discourage investment due to higher costs.The study concludes that substantial government support such as tax incentives,grants,and low-interest financing is critical to fostering investment in Net Zero Carbon Buildings.Additionally,raising awareness among developers and the private sector about the long-term benefits of these projects is essential to strengthening investment incentives.
基金supported by the National Natural Science Foundation of China(Grants Nos.62473146,62072249 and 62072056)the National Science Foundation of Hunan Province(Grant No.2024JJ3017)+1 种基金the Hunan Provincial Key Research and Development Program(Grant No.2022GK2019)by the Researchers Supporting Project Number(RSP2024R509),King Saud University,Riyadh,Saudi Arabia.
文摘In the context of an increasingly severe cybersecurity landscape and the growing complexity of offensive and defen-sive techniques,Zero Trust Networks(ZTN)have emerged as a widely recognized technology.Zero Trust not only addresses the shortcomings of traditional perimeter security models but also consistently follows the fundamental principle of“never trust,always verify.”Initially proposed by John Cortez in 2010 and subsequently promoted by Google,the Zero Trust model has become a key approach to addressing the ever-growing security threats in complex network environments.This paper systematically compares the current mainstream cybersecurity models,thoroughly explores the advantages and limitations of the Zero Trust model,and provides an in-depth review of its components and key technologies.Additionally,it analyzes the latest research achievements in the application of Zero Trust technology across various fields,including network security,6G networks,the Internet of Things(IoT),and cloud computing,in the context of specific use cases.The paper also discusses the innovative contributions of the Zero Trust model in these fields,the challenges it faces,and proposes corresponding solutions and future research directions.
文摘Understanding crash contributing factors is essential in safety management and improvement. These factors drive investment decisions, policies, regulations, and other safety-related initiatives. This paper analyzes factors that contribute to crash occurrence based on two national datasets in the United States (CISS and NASS-CDS) for the years 2017-2022 and 2010-2015, respectively. Three taxonomies were applied to enhance understanding of the various crash contributing factors. These taxonomies were developed based on previous research and practice and involved different groupings of human factors, vehicle factors, and roadway and environmental factors. Statistics for grouping the different types of factors and statistics for specific factors are provided. The results indicate that human factors are present in over 95% of crashes, roadway and environmental factors are present in over 45% of crashes, and vehicle factors are present in less than 2% of crashes. Regarding factors related to human error and vehicle maintenance, speeding is involved in over 25% of crashes, distraction is involved in over 20% of crashes, alcohol and drugs are involved in over 9% of crashes, and vehicle maintenance is involved in approximately 0.45% of crashes. Approximately 4.4% of crashes involve a driver who “looked but did not see.” Weather is involved in over 13% of crashes. Conclusions: The findings indicate that, consistent with previous research, human factors or human error are present in around 95% of crashes. Infrastructure and environmental factors contribute to about 45% of crashes. Vehicle factors contribute to only 1.67% - 1.71% of crashes. The results from this study could potentially be used to inform future safety management and improvement activities, including policy-making, regulation development, safe systems and systemic safety approaches to safety management, and other engineering, education, emergency response, enforcement, evaluation, and encouragement activities. The findings could also be used in the development of future Driver Assistance Technologies (DAT) systems and in enhancing existing technologies.
