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Design and Development of Hydraulic Disc Brake Systems for Well Servicing Rig Drawworks 被引量:1
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作者 Gao xiangqian and Zhou Yongxia(Research Institute of petroleum Exploration and Development, CNPC) 《China Oil & Gas》 CAS 1996年第3期170-171,共2页
DesignandDevelopmentofHydraulicDiscBrakeSystemsforWellServicingRigDrawworksGaoxiangqianandZhouYongxia(Resear... DesignandDevelopmentofHydraulicDiscBrakeSystemsforWellServicingRigDrawworksGaoxiangqianandZhouYongxia(ResearchInstituteofpetr... 展开更多
关键词 DRILLING rig MACHINERY WELL servicing
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ANALYSIS ON A TYPE OF SERVICING MACHINES MODEL WITH REPAIRABLE SERVICE STATION
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作者 朱翼隽 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 1997年第2期153-159,共7页
This paper deals with a type of servicing machines model, which service station has a life time of the kth Er-langian distribution and can be repaired just like a new one. The cyclic time and the inefficiency quantiti... This paper deals with a type of servicing machines model, which service station has a life time of the kth Er-langian distribution and can be repaired just like a new one. The cyclic time and the inefficiency quantities of this system in equilibrium are obtained. 展开更多
关键词 queuing theory DISTRIBUTION Erlangian distribution repairable service station cyclic time inefficiency quantities
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Effectiveness-based orbital optimization for servicing spacecraft
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作者 蔡远文 申功勋 +1 位作者 于小红 李岩 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2011年第2期113-118,共6页
Effectiveness-based system development is an essential technology developing concept advanced by some countries,such as the U.S.A.Making use of Analytic Hierarchy Process,this paper brings forward a methodology for or... Effectiveness-based system development is an essential technology developing concept advanced by some countries,such as the U.S.A.Making use of Analytic Hierarchy Process,this paper brings forward a methodology for orbital optimization based on effectiveness in the case of the orbital deployment for the Servicing Spacecraft(SSC),which needs to accomplish many types of tasks and whose orbit is affected by kinds of factors with contradictions in orbital parameter selection.Firstly,the possible tasks of SSC are decomposed and their degrees of importance are given by the times,probabilities,values of their applications.Then,the supporting capabilities are discussed from the viewpoint of orbit design,and the determination of their weights is put forward.Finally,the relationships between the orbital parameters and the effectiveness are established by using effective function,and three synthesizing methods for a single task and its capabilities are presented. 展开更多
关键词 servicing spacecraft orbital deployment orbital maneuver effective function Analytic Hierarchy Process
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Multi-Feature Fusion Based Relative Pose Adaptive Estimation for On-Orbit Servicing of Non-Cooperative Spacecraft
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作者 Yunhua Wu Nan Yang +1 位作者 Zhiming Chen Bing Hua 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2019年第6期19-30,共12页
On-orbit servicing, such as spacecraft maintenance, on-orbit assembly, refueling, and de-orbiting, can reduce the cost of space missions, improve the performance of spacecraft, and extend its life span. The relative s... On-orbit servicing, such as spacecraft maintenance, on-orbit assembly, refueling, and de-orbiting, can reduce the cost of space missions, improve the performance of spacecraft, and extend its life span. The relative state between the servicing and target spacecraft is vital for on-orbit servicing missions, especially the final approaching stage. The major challenge of this stage is that the observed features of the target are incomplete or are constantly changing due to the short distance and limited Field of View (FOV) of camera. Different from cooperative spacecraft, non-cooperative target does not have artificial feature markers. Therefore, contour features, including triangle supports of solar array, docking ring, and corner points of the spacecraft body, are used as the measuring features. To overcome the drawback of FOV limitation and imaging ambiguity of the camera, a "selfie stick" structure and a self-calibration strategy were implemented, ensuring that part of the contour features could be observed precisely when the two spacecraft approached each other. The observed features were constantly changing as the relative distance shortened. It was difficult to build a unified measurement model for different types of features, including points, line segments, and circle. Therefore, dual quaternion was implemented to model the relative dynamics and measuring features. With the consideration of state uncertainty of the target, a fuzzy adaptive strong tracking filter( FASTF) combining fuzzy logic adaptive controller (FLAC) with strong tracking filter(STF) was designed to robustly estimate the relative states between the servicing spacecraft and the target. Finally, the effectiveness of the strategy was verified by mathematical simulation. The achievement of this research provides a theoretical and technical foundation for future on-orbit servicing missions. 展开更多
关键词 on-orbit servicing non-cooperative spacecraft multi-feature fusion fuzzy adaptive filter dual quaternion
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Randomization-based algorithms for servicing spacecraft motion planning on elliptical orbit
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作者 王平 郭继峰 崔乃刚 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2011年第3期68-73,共6页
Randomization-based motion planning algorithms are presented to solve problems of servicing spacecraft maneuvering in proximity to servicing targets on an elliptical orbit.The feasible trajectories of position and att... Randomization-based motion planning algorithms are presented to solve problems of servicing spacecraft maneuvering in proximity to servicing targets on an elliptical orbit.The feasible trajectories of position and attitude for spacecraft are obtained by these algorithms under a variety of constraints.The state transition matrix is applied to computation of relative motion on elliptical orbits without performing numerical integration.The pseudo body coordinate system is built for identifying the planners on three coordinate axes with different functions.Finally,motion planning algorithm for translation and attitude taking account of the dependent variable (i.e.time) is used to obtain feasible trajectories.As the simulation examples indicate,the effectiveness of these methods is verified for relative motion while getting close to large structures,and the paper concludes with a detailed analysis of the results. 展开更多
关键词 servicing spacecraft elliptical orbit RANDOMIZATION pseudo body coordinate system
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An introductory review of swarm technology for spacecraft on-orbit servicing 被引量:1
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作者 El Ghali Asri Zheng H.Zhu 《International Journal of Mechanical System Dynamics》 EI 2024年第1期3-21,共19页
This review paper presents a comprehensive evaluation and forward-looking perspective on the underexplored topic of servicing target objects using spacecraft swarms.Such targets can be known or unknown,cooperative or ... This review paper presents a comprehensive evaluation and forward-looking perspective on the underexplored topic of servicing target objects using spacecraft swarms.Such targets can be known or unknown,cooperative or uncooperative,and pose significant challenges in modern space operations due to their inherent complexity and unpredictability.Successfully servicing space objects is vital for active debris removal and broader on-orbit servicing tasks such as satellite maintenance,repair,refueling,orbital assembly,and construction.Significant effort has been invested in the literature to explore the servicing of targets using a single spacecraft.Given its advantages and benefits,this paper expands the discussion to encompass a swarm approach to the problem.This review covers various single-spacecraft approaches and presents a critical examination of the existing,although limited,body of work dedicated to servicing orbital objects using multiple spacecraft.The focus is also broadened to include some influential studies concerning the characterization,capture,and manipulation of physical objects by general multiagent systems,a subject with significant parallels to the core interest of this manuscript.Furthermore,this article also delves into the realm of simultaneous localization and mapping,highlighting its application within close-proximity operations in space,especially when dealing with unknown uncooperative targets.Special attention is paid to the benefits that this field can receive from distributed multiagent architectures.Finally,an exploration of the promising field of swarm robotics is presented,with an emphasis on its potential to revolutionize the servicing of orbital target objects.Concurrently,a survey of general research directly engaging swarms in the orbital context is conducted.This review aims to bridge the knowledge gap and stimulate further research in the underexplored domain of servicing space targets with spacecraft swarms. 展开更多
关键词 space robotics on-orbit servicing close-proximity operations guidance and navigation swarm robotics multiagent systems object capture and manipulation simultaneous localization and mapping
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A review of structures,verification,and calibration technologies of space robotic systems for on-orbit servicing 被引量:19
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作者 DING XiLun WANG YeCong +1 位作者 WANG YaoBing XU Kun 《Science China(Technological Sciences)》 SCIE EI CAS CSCD 2021年第3期462-480,共19页
Recently,with the rapid development of aerospace technology,an increasing number of spacecraft is being launched into space.Additionally,the demands for on-orbit servicing(OOS)missions are rapidly increasing.Space rob... Recently,with the rapid development of aerospace technology,an increasing number of spacecraft is being launched into space.Additionally,the demands for on-orbit servicing(OOS)missions are rapidly increasing.Space robotics is one of the most promising approaches for various OOS missions;thus,research on space robotics technologies for OOS has attracted increased attention from space agencies and universities worldwide.In this paper,we review the structures,ground verification,and onorbit kinematics calibration technologies of space robotic systems for OOS.First,we systematically summarize the development of space robotic systems and OOS programs based on space robotics.Then,according to the structures and applications,these systems are divided into three categories:large space manipulators,humanoid space robots,and small space manipulators.According to the capture mechanisms adopted,the end-effectors are systematically analyzed.Furthermore,the ground verification facilities used to simulate a microgravity environment are summarized and compared.Additionally,the on-orbit kinematics calibration technologies are discussed and analyzed compared with the kinematics calibration technologies of industrial manipulators with regard to four aspects.Finally,the development trends of the structures,verification,and calibration technologies are discussed to extend this review work. 展开更多
关键词 space robotic system on-orbit servicing large space manipulator humanoid space robot VERIFICATION kinematics calibration
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Performance deterioration modeling and optimal preventive maintenance strategy under scheduled servicing subject to mission time 被引量:14
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作者 Li Dawei Zhang Zhihua +1 位作者 Zhong Qianghui Zhai Yali 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2014年第4期821-828,共8页
Servicing is applied periodically in practice with the aim of restoring the system state and prolonging the lifetime. It is generally seen as an imperfect maintenance action which has a chief influence on the maintena... Servicing is applied periodically in practice with the aim of restoring the system state and prolonging the lifetime. It is generally seen as an imperfect maintenance action which has a chief influence on the maintenance strategy. In order to model the maintenance effect of servicing, this study analyzes the deterioration characteristics of system under scheduled servicing. And then the deterioration model is established from the failure mechanism by compound Poisson process. On the basis of the system damage value and failure mechanism, the failure rate refresh factor is proposed to describe the maintenance effect of servicing. A maintenance strategy is developed which combines the benefits of scheduled servicing and preventive maintenance. Then the optimization model is given to determine the optimal servicing period and preventive maintenance time, with an objective to minimize the system expected life-cycle cost per unit time and a constraint on system survival probability for the duration of mission time. Subject to mission time, it can control the ability of accomplishing the mission at any time so as to ensure the high dependability. An example of water pump rotor relating to scheduled servicing is introduced to illustrate the failure rate refresh factor and the proposed maintenance strategy. Compared with traditional methods, the numerical results show that the failure rate refresh factor can describe the maintenance effect of servicing more intuitively and objectively. It also demonstrates that this maintenance strategy can prolong the lifetime, reduce the total lifetime maintenance cost and guarantee the dependability of system. 展开更多
关键词 DEPENDABILITY Imperfect maintenance Preventive maintenance Reliability Scheduled servicing
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DDoS Attack Autonomous Detection Model Based on Multi-Strategy Integrate Zebra Optimization Algorithm
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作者 Chunhui Li Xiaoying Wang +2 位作者 Qingjie Zhang Jiaye Liang Aijing Zhang 《Computers, Materials & Continua》 SCIE EI 2025年第1期645-674,共30页
Previous studies have shown that deep learning is very effective in detecting known attacks.However,when facing unknown attacks,models such as Deep Neural Networks(DNN)combined with Long Short-Term Memory(LSTM),Convol... Previous studies have shown that deep learning is very effective in detecting known attacks.However,when facing unknown attacks,models such as Deep Neural Networks(DNN)combined with Long Short-Term Memory(LSTM),Convolutional Neural Networks(CNN)combined with LSTM,and so on are built by simple stacking,which has the problems of feature loss,low efficiency,and low accuracy.Therefore,this paper proposes an autonomous detectionmodel for Distributed Denial of Service attacks,Multi-Scale Convolutional Neural Network-Bidirectional Gated Recurrent Units-Single Headed Attention(MSCNN-BiGRU-SHA),which is based on a Multistrategy Integrated Zebra Optimization Algorithm(MI-ZOA).The model undergoes training and testing with the CICDDoS2019 dataset,and its performance is evaluated on a new GINKS2023 dataset.The hyperparameters for Conv_filter and GRU_unit are optimized using the Multi-strategy Integrated Zebra Optimization Algorithm(MIZOA).The experimental results show that the test accuracy of the MSCNN-BiGRU-SHA model based on the MIZOA proposed in this paper is as high as 0.9971 in the CICDDoS 2019 dataset.The evaluation accuracy of the new dataset GINKS2023 created in this paper is 0.9386.Compared to the MSCNN-BiGRU-SHA model based on the Zebra Optimization Algorithm(ZOA),the detection accuracy on the GINKS2023 dataset has improved by 5.81%,precisionhas increasedby 1.35%,the recallhas improvedby 9%,and theF1scorehas increasedby 5.55%.Compared to the MSCNN-BiGRU-SHA models developed using Grid Search,Random Search,and Bayesian Optimization,the MSCNN-BiGRU-SHA model optimized with the MI-ZOA exhibits better performance in terms of accuracy,precision,recall,and F1 score. 展开更多
关键词 Distributed denial of service attack intrusion detection deep learning zebra optimization algorithm multi-strategy integrated zebra optimization algorithm
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Relationship between the use of smart medical services and mental health status
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作者 Elif Sarac 《World Journal of Psychiatry》 SCIE 2025年第1期21-25,共5页
In this editorial,I comment on the article by Zhang et al.To emphasize the importance of the topic,I discuss the relationship between the use of smart medical devices and mental health.Smart medical services have the ... In this editorial,I comment on the article by Zhang et al.To emphasize the importance of the topic,I discuss the relationship between the use of smart medical devices and mental health.Smart medical services have the potential to positively influence mental health by providing monitoring,insights,and inter-ventions.However,they also come with challenges that need to be addressed.Understanding the primary purpose for which individuals use these smart tech-nologies is essential to tailoring them to specific mental health needs and prefe-rences. 展开更多
关键词 Smart devices Medical service USAGE PEOPLE RELATIONSHIP Mental health status
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Efficient Cooperative Transmission over Satellite Internet for 6G
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《China Communications》 2025年第2期I0002-I0004,共3页
Satellite Internet,as a strategic public information infrastructure,can effectively bridge the limitations of traditional terrestrial network coverage,support global coverage and deep space exploration,and greatly enh... Satellite Internet,as a strategic public information infrastructure,can effectively bridge the limitations of traditional terrestrial network coverage,support global coverage and deep space exploration,and greatly enhance the range of network information services accessible to humans.With the transition of terrestrial mobile communication networks from the 5G era,which provides access to information anywhere,to the 6G era,which seeks to connect everything,the construction of satellite Internet,which promises a“network reaching everywhere and service is ubiquitous”,has become the consensus of the industry’s development and the focus of global scientific and technological innovation. 展开更多
关键词 INTERNET SERVICES SERVICE
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Services Oriented Education,Shape Service Thinking for Software Engineering Students
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作者 Shijun Liu Lizhen Cui Li Pan 《计算机教育》 2025年第3期87-94,共8页
In recent years,service computing has been widely integrated into software development.Web service development,especially under the RESTful schema,needs to guide students in transferring from object-oriented to resour... In recent years,service computing has been widely integrated into software development.Web service development,especially under the RESTful schema,needs to guide students in transferring from object-oriented to resource-oriented architectural thinking and cultivating students’literacy in design thinking,design patterns,and development methods.This paper introduces the foundations of service thinking with a brief review of service sciences,the core features of service thinking,and how to train service thinking of students.It also introduces a case study in Shandong University in the construction of a service computing curriculum system,especially how to highlight the cultivation of service thinking in the design of service software system. 展开更多
关键词 Services oriented education Service thinking Service computing
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Good nurse characteristics tool:development and psychometric testing
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作者 Sina Valiee Syede Mona Nemati Kambiz Zehni 《Frontiers of Nursing》 2025年第1期57-66,共10页
Objective:The purpose of this study was to develop and psychometrically analyze the characteristics of the good nurse from the perspective of service recipients.Methods:The current research was conducted namely in 2 q... Objective:The purpose of this study was to develop and psychometrically analyze the characteristics of the good nurse from the perspective of service recipients.Methods:The current research was conducted namely in 2 qualitative and psychometric phases.In the first stage,the items of the questionnaire were designed by interviews with nursing service recipients,and in the next stage,construct validity,content validity,face validity,reliability,and internal consistency were all reviewed.Results:Based on the results of the content analysis of the interview with nursing service recipients and related literature review,an 80-item questionnaire was designed.After analyzing its content validity,40 items were validated and 40 were eliminated,which were prepared by using exploratory factor analysis,6 factors of attentive and communicative,patron and companionable,complete caregiver,safer and skillful,advocate and confidant.The reliability of the tool was assessed by applying Cronbach’s alpha method of 0.90.Conclusions:“The good nurse characteristics tool”could be used to assess the service receivers’point of view and provide useful information regarding nurses’performance to managers and nurses and will provide the basis for improving the quality of nursing services. 展开更多
关键词 IMAGE nurses nursing services PROFESSION PSYCHOMETRICS
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Prehospital critical care drug-therapy and 30-day mortality in patients with acute respiratory disease
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作者 Jesús Jurado-Palomo JoséLuis Martín-Conty +6 位作者 Begoña Polonio-López Cristina Rivera Picón Raúl López-Izquierdo Carlos del Pozo Vegas Pedro Ángel de Santos Castro Ancor Sanz-García Francisco Martín-Rodríguez 《World Journal of Emergency Medicine》 2025年第1期43-50,共8页
BACKGROUND: Prehospital medication is a reality, and the role of these therapies must be explored to assess their validity, especially for acute respiratory diseases, which are usually associated with increased morbid... BACKGROUND: Prehospital medication is a reality, and the role of these therapies must be explored to assess their validity, especially for acute respiratory diseases, which are usually associated with increased morbidity. The aim of this study was to examine the association of prehospital medication use with mortality in patients with acute respiratory disease.METHODS: A prospective, multicenter, emergency medical service(EMS) delivery cohort study was carried out in adults with unselected respiratory diseases managed by EMS who were transferred to the emergency department. From January 1, 2019, to October 31, 2023, six advanced life support units, thirty-eight basic life support units, and four hospitals in Spain participated in the study. Demographic data, vital signs, use of mechanical ventilation, prehospital respiratory diagnosis, and prehospital medication were collected. The primary outcome was 30-day in-hospital mortality.RESULTS: A total of 961 patients were included, with a mortality rate of 17.5%(168 patients). Age, an increasing number of comorbidities, the use of invasive mechanical ventilation(IMV), the use of major analgesics, hypnotics, and bicarbonate were risk factors. In contrast, elevated systolic blood pressure and Glasgow Coma Scale scores were found to be protective factors against mortality. The predictive capacity of the model reached an area under the curve(AUC) of 0.857(95% confidence interval [95% CI] 0.827–0.888).CONCLUSION: Our data revealed that IMV, major analgesics, hypnotics and bicarbonate administration were associated with elevated mortality. Adding prehospital drug therapy information to demographic variables and vital signs could improve EMS decision-making, allowing a better characterization of patients at risk of clinical worsening. 展开更多
关键词 Drug-therapy MEDICATION PREHOSPITAL MORTALITY Emergency medical services
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International standards promote sustainable development of tourism
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作者 Jin Jili 《China Standardization》 2025年第1期42-49,共8页
The Ministry of Culture and Tourism(MCT)held a press conference on December 5,2024 in Beijing,inviting several guests to give a comprehensive introduction to ISO 14785:2024,Tourism and related services—Tourist inform... The Ministry of Culture and Tourism(MCT)held a press conference on December 5,2024 in Beijing,inviting several guests to give a comprehensive introduction to ISO 14785:2024,Tourism and related services—Tourist information services—Requirements and recommendations.The international standard was published by ISO recently,whose development was participated in by Chinese experts with great efforts. 展开更多
关键词 SERVICES TOURISM SUSTAINABLE
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The 3rd Education Standardization Development Forum marks a new chapter
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《China Standardization》 2025年第1期13-13,共1页
The Implementation Plan of Selection and Building of Pilot Colleges for SOP (Standard Operating Procedure) Standardization Talent Cultivation was released at the 3rd Education Standardization Development Forum on Dece... The Implementation Plan of Selection and Building of Pilot Colleges for SOP (Standard Operating Procedure) Standardization Talent Cultivation was released at the 3rd Education Standardization Development Forum on December 28, 2024, marking the establishment of service system for the pilot of integrated education of profession and standardization. 展开更多
关键词 FORUM EDUCATION SERVICE
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Train of Thought
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作者 AUGUSTO SOTO 《China Today》 2025年第2期42-43,共2页
With 2025 going to be a special year for China-Europe ties,2024 has provided many inspirations,from a milestone in the China-Europe train service to a new center for cooperation.THE Yiwu-Madrid freight railway route,t... With 2025 going to be a special year for China-Europe ties,2024 has provided many inspirations,from a milestone in the China-Europe train service to a new center for cooperation.THE Yiwu-Madrid freight railway route,the longest in the world,crisscrossing over 13,000 kilometers and covering eight countries,celebrated its 10th anniversary last November. 展开更多
关键词 SERVICE RAILWAY ANNIVERSARY
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China Travel: The New Fad
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作者 LI GANG 《China Today》 2025年第2期26-31,共6页
LAST year saw a robust increase in international visits to China due to the expansion of its visa-free policy,improvement in payment services,resumption of multiple direct flights,and construction of new infrastructur... LAST year saw a robust increase in international visits to China due to the expansion of its visa-free policy,improvement in payment services,resumption of multiple direct flights,and construction of new infrastructure.As China is opening up wider to the world,more foreign tourists are flocking to the country.As a means of cultural exchange,tourism allows people to experience first-hand the openness,inclusiveness,safety,stability,and prosperity of China.This in the end helps the country to build up its international image and soft power. 展开更多
关键词 POLICY China SERVICES
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国外绿色宣称之英国环境宣称指南(一)
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作者 吕秀媛 《中国洗涤用品工业》 2025年第2期78-83,共6页
1概述英国竞争与市场管理局(Competition and Markets Authority,CMA)于2021年9月份出版了《绿色宣称指南》(Guidance:Making environmental claims on goods and services),其内容包括企业遵守的原则、每项原则相关的应用实例以及其所... 1概述英国竞争与市场管理局(Competition and Markets Authority,CMA)于2021年9月份出版了《绿色宣称指南》(Guidance:Making environmental claims on goods and services),其内容包括企业遵守的原则、每项原则相关的应用实例以及其所依据的法律框架。但应注意该指南并非法律建议。 展开更多
关键词 AUTHORITY SERVICES 法律框架
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ISO/TS 9546 on third-party payment services released
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《China Standardization》 2025年第1期17-17,共1页
Third-party payment (TPP) is an evolving model of payment services provided by third-party payment service providers (TPPSPs) for every end user using a payment account in another entity. TPP plays an important role g... Third-party payment (TPP) is an evolving model of payment services provided by third-party payment service providers (TPPSPs) for every end user using a payment account in another entity. TPP plays an important role globally by complementing the offer of the traditional financial market players and contributes to the efficiency of payment transactions and financial systems. 展开更多
关键词 ISO/TS SERVICES FINANCIAL
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