This paper presents an overview of the recent developments in hybrid wind-wave energy.With the focus on floating concepts,the possible configurations introduced in the literature are categorized and depicted,and the m...This paper presents an overview of the recent developments in hybrid wind-wave energy.With the focus on floating concepts,the possible configurations introduced in the literature are categorized and depicted,and the main conclusions obtained from the references are summarized.Moreover,offshore wind and wave resources are discussed in terms of complementarity and supplementarity,offering a new perspective to developing hybrid wind-wave energy systems that look for synergies not limited to maximizing power output.Then,the feasibility of the concepts under development is discussed in detail,with focus on technical feasibility,dynamic feasibility and limitations of the methods employed.The hybrid configurations that surpassed the experimental validation phase are highlighted,and the experimental results are summarized.By compiling more than 40 floating wind turbine concepts,new relations are drawn between power,wind turbine dimensions,platforms’draft and displacement,which are further related to the payload allowance of the units to accommodate wave devices and onboard power take-off systems.Bearing in mind that it is a challenge to model the exact dynamics of hybrid floating wind-wave platforms,this paper elucidates the current research gaps,limitations and future trends in the field.Lastly,based on the overview and topics discussed,several major conclusions are drawn concerning hybrid synergies,dynamics and hydrodynamics of hybrid platforms,feasibility of concepts,among other regards.展开更多
Mooring cable tension is a crucial parameter for evaluating the safety and reliability of a floating platform mooring system.The real-time mooring tension in an actual marine environment has always been essential data...Mooring cable tension is a crucial parameter for evaluating the safety and reliability of a floating platform mooring system.The real-time mooring tension in an actual marine environment has always been essential data that mooring system designers aim to acquire.To address the need for long-term continuous monitoring of mooring tension in deep-sea marine environments,this paper presents a mooring cable tension monitoring method based on the principle of direct mechanical measurement.The developed tension monitoring sensors were installed and applied in the mooring system of the"Yongle"scientific experimental platform.Over the course of one year,a substantial amount of in-situ tension monitoring data was obtained.Under wave heights of up to 1.24 m,the mooring tension on the floating platform reached 16.5 tons.Through frequency domain and time domain analysis,the spectral characteristics of mooring tension,including waveinduced force,slow drift force,and mooring cable elastic restoring force,were determined.The mooring cable elastic restoring force frequency was approximately half of that of the wave signal.Due to the characteristics of the hinge connection structure of the dual module floating platform,under some specific working conditions the wave-induced force was the maximum of the three different frequency forces,and restoring force was the smallest.展开更多
Online learning has taken root and with the advancement in technology more and more educators are embracing online learning.During the COVID-19 pandemic,with total shut down of face-to-face learning,the Kenyan governm...Online learning has taken root and with the advancement in technology more and more educators are embracing online learning.During the COVID-19 pandemic,with total shut down of face-to-face learning,the Kenyan government had moved learning online and remotely.To find out on how learners in remote areas were experiencing learning during the COVID-19 pandemic,a study was carried out using rapid ethnography design.Five final year secondary students were sampled.Data was collected through interviews,observations,and document analysis.This paper reports on the findings of online and remote learning platforms,which were available,accessed,and preferred by the learners in remote areas of Kenya during the pandemic.It also highlights the importance of e-learning platforms in addressing learning experiences and success.展开更多
The purpose of this study is to analyze factors affecting the purchasing behavior of low-income Vietnamese on e-commerce platforms.700 questionnaires were dispersed among universities,coffee shops,and Facebook communi...The purpose of this study is to analyze factors affecting the purchasing behavior of low-income Vietnamese on e-commerce platforms.700 questionnaires were dispersed among universities,coffee shops,and Facebook community groups in Vietnam.Respondents to the questionnaires were consumers of those places in Vietnam,which were randomly selected.Finally,SEM analysis was used on the data to test the hypotheses of the study.The study identified that“Subjective norms”and“Consumer attitudes”have no effect on shopping behavior on e-commerce platforms,while“Perceived behavioral control”is most affected and“Perceived risks”are least affected on shopping behavior.展开更多
1.Introduction Due to the continuous progress in surgical methodologies and the swift evolution of surgical tools,minimally invasive procedures have emerged as the dominant approach in urologic oncology surgeries.Nota...1.Introduction Due to the continuous progress in surgical methodologies and the swift evolution of surgical tools,minimally invasive procedures have emerged as the dominant approach in urologic oncology surgeries.Notably,robot-assisted surgery(RAS)has led to its extensive adoption in the surgical management of urinary system tumors due to its enhanced maneuverability,precision in suturing,and anastomotic capabilities.展开更多
With the growing importance of wearable and portable electronics in modern society and industry,researchers from all over the world have reported on advances in energy harvesting and self-powered sensing technologies....With the growing importance of wearable and portable electronics in modern society and industry,researchers from all over the world have reported on advances in energy harvesting and self-powered sensing technologies.The current review discusses recent developments in triboelectric platforms from a manufacturing perspective,including material,design,application,and industrialization.Manufacturing is an essential component of both industry and technology.The use of a proper manufacturing process enables cutting-edge technology in a lab-scale stage to progress to commercialization and popularization with scalability,availability,commercial advantage,and consistent quality.Furthermore,much literature has emphasized that the most powerful advantage of the triboelectric platform is its wide range of available materials and simple working mechanism,both of which are important characteristics in manufacturing engineering.As a result,different manufacturing processes can be implemented as needed.Because the practical process can have a synergetic effect on the fundamental development,resulting in the growth of both,the development of the triboelectric platform from the standpoint of manufacturing engineering can be further advanced.However,research into the development of a productive manufacturing process is still in its early stages in the field of triboelectric platforms.This review looks at the various manufacturing technologies used in previous studies and discusses the potential benefits of the appropriate process for triboelectric platforms.Given its unique strength,which includes a diverse material selection and a simple working mechanism,the triboelectric platform can use a variety of manufacturing technologies and the process can be optimized as needed.Numerous research groups have clearly demonstrated the triboelectric platform's advantages.As a result,using appropriate manufacturing processes can accelerate the technological advancement of triboelectric platforms in a variety of research and industrial fields by allowing them to move beyond the lab-scale fabrication stage.展开更多
Taking the cooperation between China and Pakistan as an example,this paper expounds on the current situation,governance concept,obstacles to cooperation,and differentiated policies of Western countries in the areas of...Taking the cooperation between China and Pakistan as an example,this paper expounds on the current situation,governance concept,obstacles to cooperation,and differentiated policies of Western countries in the areas of cybersecurity,the role of new e-commerce platforms,and digital sovereignty of BRICS countries.It aims to promote inter-governmental cooperation through civil dialogue and lead information technology cooperation among developing countries through the BRICS mechanism,as well as to collaborate to establish guidelines for global cybersecurity,new e-commerce platforms,and digital sovereignty.展开更多
In recent years,gig economy jobs-particularly those of food delivery and ride-hailing drivers-have rapidly emerged as a significant force in the labor market,reflecting the deep integration of China’s digital and rea...In recent years,gig economy jobs-particularly those of food delivery and ride-hailing drivers-have rapidly emerged as a significant force in the labor market,reflecting the deep integration of China’s digital and real economies.This paper examines how digital platforms that support the gig economy exercise directionality and dominance in labor matching,where the platform dictates which consumers workers serve,rather than allowing independent choice.While this platform-led matching may appear to limit consumer and worker autonomy,it actually arises from the platform’s central role in information flow and its technological capabilities,serving as a foundation for the platform’s ability to create large-scale employment through cross-side network effects.Using a theoretical model that integrates digital platforms,labor markets,and product markets,the paper explores how the efficiency of targeted matching affects employment creation.In the early stages of gig economy development,when targeted matching efficiency is low,improvements in assignment efficiency lead to a net increase in gig employment,worker income,and overall social welfare.However,in the later stages,as targeted matching efficiency improves,the potential for monopoly abuse by incumbent platforms may trigger a crowding-out effect,leading to unemployment,income inequality between platforms and workers,and higher commission fees.While fostering competition within platform markets offers benefits,policymakers should avoid excessively low entry barriers,as these can negatively impact incumbent platforms’decisions regarding labor,pricing,and technology investment.展开更多
On 20 April 1994,China made its first o!cial full-function connection to the World Wide Web through a 64-kilobyte international leased line,marking the country’s formal entry into the global digital age.The year 2024...On 20 April 1994,China made its first o!cial full-function connection to the World Wide Web through a 64-kilobyte international leased line,marking the country’s formal entry into the global digital age.The year 2024 marked the 30th anniversary of the country’s entry into the internet era.展开更多
To address the widespread challenges of insufficient classroom participation,difficulty maintaining learning interest,and inaccurate learning outcome assessment in existing teaching models,this study introduces a hybr...To address the widespread challenges of insufficient classroom participation,difficulty maintaining learning interest,and inaccurate learning outcome assessment in existing teaching models,this study introduces a hybrid and dual-teacher classroom model.Based on big data and online platforms,this study constructs a music teaching resource system that integrates online micro-lessons,real-time interaction,virtual choirs,collaborative composition,and learning behavior tracking to enhance the openness and personalization of teaching.Through comparative experiments,the study focuses on changes in student knowledge acquisition,musical skills,learning interest,and classroom engagement.Results show that the experimental group significantly outperforms the control group in terms of improvement in knowledge test scores,rhythm and pitch performance,task completion rate,and scores on the learning motivation questionnaire.Differences are particularly prominent in interaction frequency and the expressiveness of the work.The study shows that Group A demonstrates significant improvement in all three dimensions:interest increases from 3.1 to 4.2;autonomous learning motivation increases from 3.0 to 4.1;emotional engagement increases from 3.2 to 4.3,demonstrating strong positive effects.Experimental Group B shows the greatest improvement,with interest increasing from 3.0 to 4.5,autonomous learning motivation from 2.9 to 4.4,and emotional engagement from 3.1 to 4.6,indicating the most significant improvements in learning attitudes and emotions.展开更多
The advancement of imaging resolution has made the impact of multi-frequency composite jitter in satellite platforms on non-collinear time delay and integration(TDI)charge-coupled device(CCD)imaging systems increasing...The advancement of imaging resolution has made the impact of multi-frequency composite jitter in satellite platforms on non-collinear time delay and integration(TDI)charge-coupled device(CCD)imaging systems increasingly critical.Moreover,the accuracy of jitter detection is constrained by the limited inter-chip overlap region inherent to non-collinear TDI CCDs.To address these challenges,a multi-frequency jitter detection method is proposed,achieving sub-pixel level error extraction.Furthermore,a multi-frequency jitter fitting approach utilizing a scale-adjustable sliding window is introduced.For composite multi-frequency jitter,spectral analysis decomposes the relative jitter error curve,while the scale-adjustable sliding window enables frequency-division fitting and modeling.Validation experiments using Gaofen-8(GF-8)remote sensing satellite imagery detected jitter at 0.65,20,and 100 Hz in the cross-track direction and at 0.5,100,and 120 Hz in the along-track direction,demonstrating the method’s precision in detecting platform jitter at sub-pixel accuracy(<0.2 pixels)and its efficacy in fitting and modeling for non-collinear TDI CCD imaging systems subject to multi-frequency jitter.展开更多
With the rapid development of the Internet and e-commerce,e-commerce platforms have accumulated huge amounts of user behavior data.The emergence of big data technology provides a powerful means for in-depth analysis o...With the rapid development of the Internet and e-commerce,e-commerce platforms have accumulated huge amounts of user behavior data.The emergence of big data technology provides a powerful means for in-depth analysis of these data and insight into user behavior patterns and preferences.This paper elaborates on the application of big data technology in the analysis of user behavior on e-commerce platforms,including the technical methods of data collection,storage,processing and analysis,as well as the specific applications in the construction of user profiles,precision marketing,personalized recommendation,user retention and churn analysis,etc.,and discusses the challenges and countermeasures faced in the application.Through the study of actual cases,it demonstrates the remarkable effectiveness of big data technology in enhancing the competitiveness of e-commerce platforms and user experience.展开更多
This study investigates the seismic response mitigation of an offshore jacket platform via a novel damping system,the bidirectional tuned liquid column gas damper(BTLCGD).To efficiently model the complex platform stru...This study investigates the seismic response mitigation of an offshore jacket platform via a novel damping system,the bidirectional tuned liquid column gas damper(BTLCGD).To efficiently model the complex platform structure,an equivalent single degree of freedom approach was employed.Since the mass contribution of the first mode of the platform is more than 90%,this simplification significantly reduces the computational burden while maintaining accuracy.Therefore,this structure was modeled and analyzed on a scale of 1 to 36 using the Froudian law.To address the limitations of conventional tuned liquid column gas dampers(TLCGDs),which are susceptible to the directionality of seismic excitations,BTLCGD was proposed.This innovative damper is designed to operate effectively in two orthogonal directions,thereby improving seismic performance.Through numerical simulations,the performance of both TLCGD and BTLCGD was evaluated under seismic loading.The results demonstrated that BTLCGD significantly outperforms TLCGD in terms of reducing structural responses,particularly in the direction where TLCGD is ineffective.Furthermore,BTLCGD offers advantages in terms of installation and space requirements.The results of this research offer valuable perspectives into the design and implementation of effective damping systems for offshore structures,contributing to enhanced structural integrity and safety.展开更多
This study examined the development of technician teams on large-scale instrument platforms in universities,using the State Key Laboratory of Natural and Biomimetic Drugs in the Peking University School of Pharmaceuti...This study examined the development of technician teams on large-scale instrument platforms in universities,using the State Key Laboratory of Natural and Biomimetic Drugs in the Peking University School of Pharmaceutical Sciences as a case study.Data were collected through questionnaire surveys and interviews conducted in 2017,followed by a questionnaire survey in 2023,offering both subjective and objective insights.The evolution of the platform’s technician team over the past 5 years was analyzed,highlighting key experiences and identifying ongoing challenges.Recommendations to enhance technician team development include recruiting skilled faculty,clearly defining job responsibilities,and refining the assessment and incentive systems.展开更多
The paper presents an innovative approach to studying the reuse of a decommissioned natural gas production platformfor the seasonal storage and extraction of a hydrogen-methane(H2-CH4)mixture froma depleted reservoir....The paper presents an innovative approach to studying the reuse of a decommissioned natural gas production platformfor the seasonal storage and extraction of a hydrogen-methane(H2-CH4)mixture froma depleted reservoir.The reuse plan involves removing outdated equipment from the platform’s decks while retaining essential components such as wellheads and separators.Exploiting a depleted reservoir for the injection of an H_(2)-CH_(4) mixture requires a thorough understanding of its specific characteristics.This paper focuses on the engineering approach adopted in the basic design phase for such a conversion,providing recommendations and HSE guidelines.Given the hazardous nature of substances like hydrogen in the gas mixture,the paper also examines potential risk scenarios,particularly those involving containment loss.A qualitative and quantitative assessment of these risks is conducted to evaluate their impact on the structure and equipment.The results of this assessment serve as a foundation for later studies on layout optimization and domino effect prevention.Additionally,some critical scenarios are simulated using an innovative approach known as the Source Box Accident Model(SBAM),which was proposed in previous works.SBAM leverages Computational Fluid Dynamics(CFD)but decouples the accidental phenomenon into a release phase and a dispersion phase.This method overcomes the challenges conventional CFD tools face in assessing congested plant configurations,providing more precise estimations of gas cloud behavior.The simulation results indicate that the released gas remains within the platform deck domain,and the flammable cloud is significantly smaller than what traditional,simplified tools predict.展开更多
面向作物表型组大数据获取解析、作物种质资源表型鉴定等亟需高效率、智能化和低成本技术、装备及系统的问题,在系统梳理分析国内外农作物高通量表型平台相关技术产品研究现状的基础上,通过组织多学科的协同技术攻关,突破了作物表型组...面向作物表型组大数据获取解析、作物种质资源表型鉴定等亟需高效率、智能化和低成本技术、装备及系统的问题,在系统梳理分析国内外农作物高通量表型平台相关技术产品研究现状的基础上,通过组织多学科的协同技术攻关,突破了作物表型组大数据高通量获取和智能化解析中的关键技术难题,设计了具有自主知识产权的轻小敏捷型多传感器阵列、通用化成像单元和适用于多生境的固定式、移动式高通量表型平台装备,以及配套算法和软件平台,构建了农作物表型组大数据工厂成套技术装备体系。该体系由大田和设施作物高通量自主作业表型平台、室内器官和显微表型平台、大田和设施环境自动化种植管控设备、作物模型系统、数字孪生智慧管控平台和大数据计算服务中心等构成,可实现多生境、自动化、高通量、高效率、高精度的多源作物表型-环境数据协同采集,涵盖农作物群体、个体、器官和显微多重尺度,能够重建农林作物的三维形态结构并精准解析株型、产品、品质、抗性等表型组指标,是发展数字育种和智慧栽培的新一代信息化基础设施。农作物表型组大数据工厂技术装备体系创新了作物表型组大数据的产生、处理和服务模式,可为作物表型组理论技术的发展、基于AI for Science的平台化科研和工厂化的作物种质资源表型鉴定等提供体系化的技术装备支撑。展开更多
基金supported by the Portuguese Foundation for Science and Technology(Fundação para a Ciência e Tecnologia-FCT)it contributes to the Strategic Research Plan of the Centre for Marine Technology and Ocean Engineering(Grant No.UIDB/UIDP/00134/2020)funded the first author for his PhD Scholarship(Grant No.SFRH/BD/145602/2019).
文摘This paper presents an overview of the recent developments in hybrid wind-wave energy.With the focus on floating concepts,the possible configurations introduced in the literature are categorized and depicted,and the main conclusions obtained from the references are summarized.Moreover,offshore wind and wave resources are discussed in terms of complementarity and supplementarity,offering a new perspective to developing hybrid wind-wave energy systems that look for synergies not limited to maximizing power output.Then,the feasibility of the concepts under development is discussed in detail,with focus on technical feasibility,dynamic feasibility and limitations of the methods employed.The hybrid configurations that surpassed the experimental validation phase are highlighted,and the experimental results are summarized.By compiling more than 40 floating wind turbine concepts,new relations are drawn between power,wind turbine dimensions,platforms’draft and displacement,which are further related to the payload allowance of the units to accommodate wave devices and onboard power take-off systems.Bearing in mind that it is a challenge to model the exact dynamics of hybrid floating wind-wave platforms,this paper elucidates the current research gaps,limitations and future trends in the field.Lastly,based on the overview and topics discussed,several major conclusions are drawn concerning hybrid synergies,dynamics and hydrodynamics of hybrid platforms,feasibility of concepts,among other regards.
文摘Mooring cable tension is a crucial parameter for evaluating the safety and reliability of a floating platform mooring system.The real-time mooring tension in an actual marine environment has always been essential data that mooring system designers aim to acquire.To address the need for long-term continuous monitoring of mooring tension in deep-sea marine environments,this paper presents a mooring cable tension monitoring method based on the principle of direct mechanical measurement.The developed tension monitoring sensors were installed and applied in the mooring system of the"Yongle"scientific experimental platform.Over the course of one year,a substantial amount of in-situ tension monitoring data was obtained.Under wave heights of up to 1.24 m,the mooring tension on the floating platform reached 16.5 tons.Through frequency domain and time domain analysis,the spectral characteristics of mooring tension,including waveinduced force,slow drift force,and mooring cable elastic restoring force,were determined.The mooring cable elastic restoring force frequency was approximately half of that of the wave signal.Due to the characteristics of the hinge connection structure of the dual module floating platform,under some specific working conditions the wave-induced force was the maximum of the three different frequency forces,and restoring force was the smallest.
文摘Online learning has taken root and with the advancement in technology more and more educators are embracing online learning.During the COVID-19 pandemic,with total shut down of face-to-face learning,the Kenyan government had moved learning online and remotely.To find out on how learners in remote areas were experiencing learning during the COVID-19 pandemic,a study was carried out using rapid ethnography design.Five final year secondary students were sampled.Data was collected through interviews,observations,and document analysis.This paper reports on the findings of online and remote learning platforms,which were available,accessed,and preferred by the learners in remote areas of Kenya during the pandemic.It also highlights the importance of e-learning platforms in addressing learning experiences and success.
文摘The purpose of this study is to analyze factors affecting the purchasing behavior of low-income Vietnamese on e-commerce platforms.700 questionnaires were dispersed among universities,coffee shops,and Facebook community groups in Vietnam.Respondents to the questionnaires were consumers of those places in Vietnam,which were randomly selected.Finally,SEM analysis was used on the data to test the hypotheses of the study.The study identified that“Subjective norms”and“Consumer attitudes”have no effect on shopping behavior on e-commerce platforms,while“Perceived behavioral control”is most affected and“Perceived risks”are least affected on shopping behavior.
基金supported by grants from the National Natural Science Foundation of China(No.82172741 to Ye D)Shanghai Municipal Health Bureau(No.2020CXJQ03 to Ye D)Xuhui District Hospital Local Cooperation Project(No.23XHYD-14 to Ye D).
文摘1.Introduction Due to the continuous progress in surgical methodologies and the swift evolution of surgical tools,minimally invasive procedures have emerged as the dominant approach in urologic oncology surgeries.Notably,robot-assisted surgery(RAS)has led to its extensive adoption in the surgical management of urinary system tumors due to its enhanced maneuverability,precision in suturing,and anastomotic capabilities.
基金supported by the National Research Foundation of Korea(NRF)(No.2021R1C1C2009703)supported by the National Research Foundation of Korea(NRF)Grant funded by the Korea government(MSIT)(RS-2024-00344920)supported by the Human Resources Development of the Korea Institute of Energy Technology Evaluation and Planning(KETEP)Grant funded by the Ministry of Trade,Industry and Energy of Korea(No.RS2023-00244330)。
文摘With the growing importance of wearable and portable electronics in modern society and industry,researchers from all over the world have reported on advances in energy harvesting and self-powered sensing technologies.The current review discusses recent developments in triboelectric platforms from a manufacturing perspective,including material,design,application,and industrialization.Manufacturing is an essential component of both industry and technology.The use of a proper manufacturing process enables cutting-edge technology in a lab-scale stage to progress to commercialization and popularization with scalability,availability,commercial advantage,and consistent quality.Furthermore,much literature has emphasized that the most powerful advantage of the triboelectric platform is its wide range of available materials and simple working mechanism,both of which are important characteristics in manufacturing engineering.As a result,different manufacturing processes can be implemented as needed.Because the practical process can have a synergetic effect on the fundamental development,resulting in the growth of both,the development of the triboelectric platform from the standpoint of manufacturing engineering can be further advanced.However,research into the development of a productive manufacturing process is still in its early stages in the field of triboelectric platforms.This review looks at the various manufacturing technologies used in previous studies and discusses the potential benefits of the appropriate process for triboelectric platforms.Given its unique strength,which includes a diverse material selection and a simple working mechanism,the triboelectric platform can use a variety of manufacturing technologies and the process can be optimized as needed.Numerous research groups have clearly demonstrated the triboelectric platform's advantages.As a result,using appropriate manufacturing processes can accelerate the technological advancement of triboelectric platforms in a variety of research and industrial fields by allowing them to move beyond the lab-scale fabrication stage.
文摘Taking the cooperation between China and Pakistan as an example,this paper expounds on the current situation,governance concept,obstacles to cooperation,and differentiated policies of Western countries in the areas of cybersecurity,the role of new e-commerce platforms,and digital sovereignty of BRICS countries.It aims to promote inter-governmental cooperation through civil dialogue and lead information technology cooperation among developing countries through the BRICS mechanism,as well as to collaborate to establish guidelines for global cybersecurity,new e-commerce platforms,and digital sovereignty.
基金supported by the National Social Science Fund of China(NSSFC)General Project“Research on the Mechanism of Monopoly Formation and Anti-Monopoly Regulation from the Perspective of Digital Economy”(Grant No.22BJY116)the Guangdong Provincial Natural Science Fund for Distinguished Young Scholars“Research on Carbon Trading Mechanisms under the Generalized Carbon Leakage Risk”(Grant No.2023B1515020068)the National Natural Science Foundation of China(NSFC)Key Project“Research on the Theory,Mechanism and Model of State-Owned Capital Mergers and Acquisitions”(Grant No.72132010).
文摘In recent years,gig economy jobs-particularly those of food delivery and ride-hailing drivers-have rapidly emerged as a significant force in the labor market,reflecting the deep integration of China’s digital and real economies.This paper examines how digital platforms that support the gig economy exercise directionality and dominance in labor matching,where the platform dictates which consumers workers serve,rather than allowing independent choice.While this platform-led matching may appear to limit consumer and worker autonomy,it actually arises from the platform’s central role in information flow and its technological capabilities,serving as a foundation for the platform’s ability to create large-scale employment through cross-side network effects.Using a theoretical model that integrates digital platforms,labor markets,and product markets,the paper explores how the efficiency of targeted matching affects employment creation.In the early stages of gig economy development,when targeted matching efficiency is low,improvements in assignment efficiency lead to a net increase in gig employment,worker income,and overall social welfare.However,in the later stages,as targeted matching efficiency improves,the potential for monopoly abuse by incumbent platforms may trigger a crowding-out effect,leading to unemployment,income inequality between platforms and workers,and higher commission fees.While fostering competition within platform markets offers benefits,policymakers should avoid excessively low entry barriers,as these can negatively impact incumbent platforms’decisions regarding labor,pricing,and technology investment.
文摘On 20 April 1994,China made its first o!cial full-function connection to the World Wide Web through a 64-kilobyte international leased line,marking the country’s formal entry into the global digital age.The year 2024 marked the 30th anniversary of the country’s entry into the internet era.
文摘To address the widespread challenges of insufficient classroom participation,difficulty maintaining learning interest,and inaccurate learning outcome assessment in existing teaching models,this study introduces a hybrid and dual-teacher classroom model.Based on big data and online platforms,this study constructs a music teaching resource system that integrates online micro-lessons,real-time interaction,virtual choirs,collaborative composition,and learning behavior tracking to enhance the openness and personalization of teaching.Through comparative experiments,the study focuses on changes in student knowledge acquisition,musical skills,learning interest,and classroom engagement.Results show that the experimental group significantly outperforms the control group in terms of improvement in knowledge test scores,rhythm and pitch performance,task completion rate,and scores on the learning motivation questionnaire.Differences are particularly prominent in interaction frequency and the expressiveness of the work.The study shows that Group A demonstrates significant improvement in all three dimensions:interest increases from 3.1 to 4.2;autonomous learning motivation increases from 3.0 to 4.1;emotional engagement increases from 3.2 to 4.3,demonstrating strong positive effects.Experimental Group B shows the greatest improvement,with interest increasing from 3.0 to 4.5,autonomous learning motivation from 2.9 to 4.4,and emotional engagement from 3.1 to 4.6,indicating the most significant improvements in learning attitudes and emotions.
文摘The advancement of imaging resolution has made the impact of multi-frequency composite jitter in satellite platforms on non-collinear time delay and integration(TDI)charge-coupled device(CCD)imaging systems increasingly critical.Moreover,the accuracy of jitter detection is constrained by the limited inter-chip overlap region inherent to non-collinear TDI CCDs.To address these challenges,a multi-frequency jitter detection method is proposed,achieving sub-pixel level error extraction.Furthermore,a multi-frequency jitter fitting approach utilizing a scale-adjustable sliding window is introduced.For composite multi-frequency jitter,spectral analysis decomposes the relative jitter error curve,while the scale-adjustable sliding window enables frequency-division fitting and modeling.Validation experiments using Gaofen-8(GF-8)remote sensing satellite imagery detected jitter at 0.65,20,and 100 Hz in the cross-track direction and at 0.5,100,and 120 Hz in the along-track direction,demonstrating the method’s precision in detecting platform jitter at sub-pixel accuracy(<0.2 pixels)and its efficacy in fitting and modeling for non-collinear TDI CCD imaging systems subject to multi-frequency jitter.
文摘With the rapid development of the Internet and e-commerce,e-commerce platforms have accumulated huge amounts of user behavior data.The emergence of big data technology provides a powerful means for in-depth analysis of these data and insight into user behavior patterns and preferences.This paper elaborates on the application of big data technology in the analysis of user behavior on e-commerce platforms,including the technical methods of data collection,storage,processing and analysis,as well as the specific applications in the construction of user profiles,precision marketing,personalized recommendation,user retention and churn analysis,etc.,and discusses the challenges and countermeasures faced in the application.Through the study of actual cases,it demonstrates the remarkable effectiveness of big data technology in enhancing the competitiveness of e-commerce platforms and user experience.
文摘This study investigates the seismic response mitigation of an offshore jacket platform via a novel damping system,the bidirectional tuned liquid column gas damper(BTLCGD).To efficiently model the complex platform structure,an equivalent single degree of freedom approach was employed.Since the mass contribution of the first mode of the platform is more than 90%,this simplification significantly reduces the computational burden while maintaining accuracy.Therefore,this structure was modeled and analyzed on a scale of 1 to 36 using the Froudian law.To address the limitations of conventional tuned liquid column gas dampers(TLCGDs),which are susceptible to the directionality of seismic excitations,BTLCGD was proposed.This innovative damper is designed to operate effectively in two orthogonal directions,thereby improving seismic performance.Through numerical simulations,the performance of both TLCGD and BTLCGD was evaluated under seismic loading.The results demonstrated that BTLCGD significantly outperforms TLCGD in terms of reducing structural responses,particularly in the direction where TLCGD is ineffective.Furthermore,BTLCGD offers advantages in terms of installation and space requirements.The results of this research offer valuable perspectives into the design and implementation of effective damping systems for offshore structures,contributing to enhanced structural integrity and safety.
文摘This study examined the development of technician teams on large-scale instrument platforms in universities,using the State Key Laboratory of Natural and Biomimetic Drugs in the Peking University School of Pharmaceutical Sciences as a case study.Data were collected through questionnaire surveys and interviews conducted in 2017,followed by a questionnaire survey in 2023,offering both subjective and objective insights.The evolution of the platform’s technician team over the past 5 years was analyzed,highlighting key experiences and identifying ongoing challenges.Recommendations to enhance technician team development include recruiting skilled faculty,clearly defining job responsibilities,and refining the assessment and incentive systems.
基金funded by the Italian Ministry of Environment and Energy Security(MASE)-Direzione Generale per le Fonti energetiche e Titoli Abilitativi(DGFTA).
文摘The paper presents an innovative approach to studying the reuse of a decommissioned natural gas production platformfor the seasonal storage and extraction of a hydrogen-methane(H2-CH4)mixture froma depleted reservoir.The reuse plan involves removing outdated equipment from the platform’s decks while retaining essential components such as wellheads and separators.Exploiting a depleted reservoir for the injection of an H_(2)-CH_(4) mixture requires a thorough understanding of its specific characteristics.This paper focuses on the engineering approach adopted in the basic design phase for such a conversion,providing recommendations and HSE guidelines.Given the hazardous nature of substances like hydrogen in the gas mixture,the paper also examines potential risk scenarios,particularly those involving containment loss.A qualitative and quantitative assessment of these risks is conducted to evaluate their impact on the structure and equipment.The results of this assessment serve as a foundation for later studies on layout optimization and domino effect prevention.Additionally,some critical scenarios are simulated using an innovative approach known as the Source Box Accident Model(SBAM),which was proposed in previous works.SBAM leverages Computational Fluid Dynamics(CFD)but decouples the accidental phenomenon into a release phase and a dispersion phase.This method overcomes the challenges conventional CFD tools face in assessing congested plant configurations,providing more precise estimations of gas cloud behavior.The simulation results indicate that the released gas remains within the platform deck domain,and the flammable cloud is significantly smaller than what traditional,simplified tools predict.
文摘面向作物表型组大数据获取解析、作物种质资源表型鉴定等亟需高效率、智能化和低成本技术、装备及系统的问题,在系统梳理分析国内外农作物高通量表型平台相关技术产品研究现状的基础上,通过组织多学科的协同技术攻关,突破了作物表型组大数据高通量获取和智能化解析中的关键技术难题,设计了具有自主知识产权的轻小敏捷型多传感器阵列、通用化成像单元和适用于多生境的固定式、移动式高通量表型平台装备,以及配套算法和软件平台,构建了农作物表型组大数据工厂成套技术装备体系。该体系由大田和设施作物高通量自主作业表型平台、室内器官和显微表型平台、大田和设施环境自动化种植管控设备、作物模型系统、数字孪生智慧管控平台和大数据计算服务中心等构成,可实现多生境、自动化、高通量、高效率、高精度的多源作物表型-环境数据协同采集,涵盖农作物群体、个体、器官和显微多重尺度,能够重建农林作物的三维形态结构并精准解析株型、产品、品质、抗性等表型组指标,是发展数字育种和智慧栽培的新一代信息化基础设施。农作物表型组大数据工厂技术装备体系创新了作物表型组大数据的产生、处理和服务模式,可为作物表型组理论技术的发展、基于AI for Science的平台化科研和工厂化的作物种质资源表型鉴定等提供体系化的技术装备支撑。
