期刊文献+
共找到1,213篇文章
< 1 2 61 >
每页显示 20 50 100
Solving the Urban Domestic Waste Classification Dilemma from a Coalitional Game Perspective
1
作者 Yuhan Li Xuanqi Liu Xiujuan Wang 《Journal of Environmental Protection》 CAS 2023年第4期243-253,共11页
The effective classification of urban domestic waste is the key to achieve a “waste-free city” and provides an essential guarantee for resource utilization. This article takes a coalitional game perspective to study... The effective classification of urban domestic waste is the key to achieve a “waste-free city” and provides an essential guarantee for resource utilization. This article takes a coalitional game perspective to study the dilemmas in urban domestic waste separation from the cooperative interaction of residents, government, and enterprises. The study finds that urban domestic waste classification in China is currently facing many problems, focusing on: 1) insufficient consensus among residents, 2) shortage of input funds, 3) corporate profitability difficulties, 4) weak policy constraints, and 5) difficulties in integrating goals. In this regard, each participating body still needs to focus on collective interests, coalitional games, break the dilemma society, and promote the long-term management of urban domestic waste. 展开更多
关键词 Waste Classification coalitional Game Multiple Subjects
下载PDF
Coalitional game based resource allocation in D2D-enabled V2V communication
2
作者 MA Piming ZHAO Peng +3 位作者 BAI Zhiquan DONG Xu YANG Xinghai KWAK Kyungsup 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2023年第6期1508-1519,共12页
The joint resource block(RB)allocation and power optimization problem is studied to maximize the sum-rate of the vehicle-to-vehicle(V2V)links in the device-to-device(D2D)-enabled V2V communication system,where one fea... The joint resource block(RB)allocation and power optimization problem is studied to maximize the sum-rate of the vehicle-to-vehicle(V2V)links in the device-to-device(D2D)-enabled V2V communication system,where one feasible cellular user(FCU)can share its RB with multiple V2V pairs.The problem is first formulated as a nonconvex mixed-integer nonlinear programming(MINLP)problem with constraint of the maximum interference power in the FCU links.Using the game theory,two coalition formation algorithms are proposed to accomplish V2V link partitioning and FCU selection,where the transferable utility functions are introduced to minimize the interference among the V2V links and the FCU links for the optimal RB allocation.The successive convex approximation(SCA)is used to transform the original problem into a convex one and the Lagrangian dual method is further applied to obtain the optimal transmit power of the V2V links.Finally,numerical results demonstrate the efficiency of the proposed resource allocation algorithm in terms of the system sum-rate. 展开更多
关键词 coalitional game vehicle-to-vehicle(V2V)communication successive convex approximation(SCA) resource block(RB)allocation power allocation.
下载PDF
MAV/UAV task coalition phased-formation method 被引量:9
3
作者 JIAO Zhiqiang YAO Peiyang +2 位作者 ZHANG Jieyong ZHONG Yun WANG Xun 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2019年第2期402-414,共13页
The formation of the manned aerial vehicle/unmanned aerial vehicle(MAV/UAV) task coalition is considered. To reduce the scale of the problem, the formation progress is divided into three phases. For the task clusterin... The formation of the manned aerial vehicle/unmanned aerial vehicle(MAV/UAV) task coalition is considered. To reduce the scale of the problem, the formation progress is divided into three phases. For the task clustering phase, the geographical position of tasks is taken into consideration and a cluster method is proposed. For the UAV allocation phase, the UAV requirement for both constrained and unconstrained resources is introduced, and a multi-objective optimal algorithm is proposed to solve the allocation problem. For the MAV allocation phase, the optimal model is firstly constructed and it is decomposed according to the ideal of greed to reduce the time complexity of the algorithm. Based on the above phases, the MAV/UAV task coalition formation method is proposed and the effectiveness and practicability are demonstrated by simulation examples. 展开更多
关键词 TASK coalition formation TASK clustering unmanned AERIAL VEHICLE (UAV) ALLOCATION manned AERIAL VEHICLE (MAV) ALLOCATION
下载PDF
Coalition Formation for Multiple UAVs Cooperative Search and Attack with Communication Constraints in Unknown Environment 被引量:3
4
作者 Liu Zhong Gao Xiaoguang Fu Xiaowei 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI CSCD 2017年第6期688-699,共12页
A coalition formation algorithm is presented with limited communication ranges and delays in unknown environment,for the performance of multiple heterogeneous unmanned aerial vehicles(UAVs)in cooperative search and at... A coalition formation algorithm is presented with limited communication ranges and delays in unknown environment,for the performance of multiple heterogeneous unmanned aerial vehicles(UAVs)in cooperative search and attack missions.The mathematic model of coalition formation is built on basis of the minimum attacking time and the minimum coalition size with satisfying resources and simultaneous strikes requirements.A communication protocol based on maximum number of hops is developed to determine the potential coalition members in dynamic network.A multistage sub-optimal coalition formation algorithm(MSOCFA)with polynomial time is established.The performances of MSOCFA and particle swarm optimization(PSO)algorithms are compared in terms of complexity,mission performance and computational time.A complex scenario is deployed to illustrate how the coalitions are formed and validate the feasibility of the MSOCFA.The effect of communication constraints(hop delay and max-hops)on mission performance is studied.The results show that it is beneficial to determine potential coalition members in a wide and deep range over the network in the presence of less delay.However,when the delays are significant,it is more advantageous to determine coalitions from among the immediate neighbors. 展开更多
关键词 multi-unmmaned aerial vehicles(UAVs) cooperative search and attack coalition formation communication constraints
下载PDF
Algorithm to Form Coalition in Multi-Agent Cooperation 被引量:1
5
作者 曹元大 李剑 《Journal of Beijing Institute of Technology》 EI CAS 2005年第2期117-120,共4页
In multi-agent systems, autonomous agents may form coalition to increase the efficiency of problem solving. But the current coalition algorithm is very complex, and cannot satisfy the condition of optimality and stabl... In multi-agent systems, autonomous agents may form coalition to increase the efficiency of problem solving. But the current coalition algorithm is very complex, and cannot satisfy the condition of optimality and stableness simultaneously. To solve the problem, an algorithm that uses the mechanism of distribution according to work for coalition formation is presented, which can achieve global optimal and stable solution in subadditive task oriented domains. The validity of the algorithm is demonstrated by both experiments and theory. 展开更多
关键词 multi-agent system(MAS) coalition coalition utility
下载PDF
Evaluation Model for Capability of Enterprise Agent Coalition Based on Information Fusion and Attribute Reduction 被引量:1
6
作者 Dongjun Liu Li Li Jiayang Wang 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2016年第2期23-30,共8页
For the issue of evaluation of capability of enterprise agent coalition,an evaluation model based on information fusion and entropy weighting method is presented. The attribute reduction method is utilized to reduce i... For the issue of evaluation of capability of enterprise agent coalition,an evaluation model based on information fusion and entropy weighting method is presented. The attribute reduction method is utilized to reduce indicators of the capability according to the theory of rough set. The new indicator system can be determined. Attribute reduction can also reduce the workload and remove the redundant information,when there are too many indicators or the indicators have strong correlation. The research complexity can be reduced and the efficiency can be improved. Entropy weighting method is used to determine the weights of the remaining indicators,and the importance of indicators is analyzed. The information fusion model based on nearest neighbor method is developed and utilized to evaluate the capability of multiple agent coalitions,compared to cloud evaluation model and D-S evidence method. Simulation results are reasonable and with obvious distinction. Thus they verify the effectiveness and feasibility of the model. The information fusion model can provide more scientific,rational decision support for choosing the best agent coalition,and provide innovative steps for the evaluation process of capability of agent coalitions. 展开更多
关键词 COMPREHENSIVE evaluation agent coalition CAPABILITY information FUSION ATTRIBUTE reduction system simulation
下载PDF
Coalition Formation in Weighted Simple-majority Games under Proportional Payoff Allocation Rules 被引量:1
7
作者 Zhi-Gang Cao Xiao-Guang Yang 《International Journal of Automation and computing》 EI 2009年第3期217-222,共6页
In this paper, we introduce a simple coalition formation game in the environment of bidding, which is a special case of the weighted majority game (WMG), and is named the weighted simple-majority game (WSMG). In W... In this paper, we introduce a simple coalition formation game in the environment of bidding, which is a special case of the weighted majority game (WMG), and is named the weighted simple-majority game (WSMG). In WSMG, payoff is allocated to the winners proportional to the players powers, which can be measured in various ways. We define a new kind of stability: the counteraction-stability (C-stability), where any potential deviating players will confront counteractions of the other players. We show that C-stable coalition structures in WSMG always contains a minimal winning coalition of minimum total power. For the variant where powers are measured directly by their weights, we show that it is NP-hard to find a C-stable coalition structure and design a pseudo-polynomial time algorithm. Sensitivity analysis for this variant, which shows many interesting properties, is also done. We also prove that it is NP-hard to compute the Holler-Packel indices in WSMGs, and hence in WMGs as well. 展开更多
关键词 Weighted majority games (WMG) coalition formation BIDDING C-stability NP-hard.
下载PDF
On the Coalitional Rationality and the Inverse Problem for Shapley Value and the Semivalues 被引量:1
8
作者 Irinel Dragan 《Applied Mathematics》 2017年第11期1590-1601,共12页
In cooperative game theory, a central problem is to allocate fairly the win of the grand coalition to the players who agreed to cooperate and form the grand coalition. Such allocations are obtained by means of values,... In cooperative game theory, a central problem is to allocate fairly the win of the grand coalition to the players who agreed to cooperate and form the grand coalition. Such allocations are obtained by means of values, having some fairness properties, expressed in most cases by groups of axioms. In an earlier work, we solved what we called the Inverse Problem for Semivalues, in which the main result was offering an explicit formula providing the set of all games with an a priori given Semivalue, associated with a given weight vector. However, in this set there is an infinite set of games for which the Semivalues are not coalitional rational, perhaps not efficient, so that these are not fair practical solutions of the above fundamental problem. Among the Semivalues, coalitional rational solutions for the Shapley Value and the Banzhaf Value have been given in two more recent works. In the present paper, based upon a general potential basis, relative to Semivalues, for a given game and a given Semivalue, we solve the connected problem: in the Inverse Set, find out a game with the same Semivalue, which is also coalitional rational. Several examples will illustrate the corresponding numerical technique. 展开更多
关键词 Shapley VALUE Banzhaf VALUE Semivalues INVERSE Problem POWER Game POWER Core coalitional RATIONALITY
下载PDF
Advocacy Coalition by External Actors and Strategies Used to Influence the Emergence of the National Nutrition Policy in Lao PDR 被引量:1
9
作者 Viengsamay Sengchaleun Mamane Abdoulaye Samri +1 位作者 Sengchanh Kounnavong Daniel Reinharz 《Health》 2021年第8期812-829,共18页
This article aims to explore the coalition of external actors and the strategies it deployed to influence the emergence of the National Nutrition Policy (NNP) in Lao People’s Democratic Republic (Lao PDR). The Advoca... This article aims to explore the coalition of external actors and the strategies it deployed to influence the emergence of the National Nutrition Policy (NNP) in Lao People’s Democratic Republic (Lao PDR). The Advocacy Coalition Framework and the conceptual model of Effective Advocacy Strategies for Influencing Government Nutrition Policy were used to frame the data collection and their analysis. Sources of information were semi-structured interviews conducted with government and external actors, as well as all available documents on nutrition policy in Laos. The commitment of the government to achieve the Millennium Development Goals (MDGs) and to leave the Least Developed Country status created a favorable condition to support the emergence of the NNP in Laos. This context was a driving force for the building of an effective and convincing coalition of United Nations agencies able to accompany the government in redefining health priorities. Various strategies were used by the coalition to this end, including generating, disseminating, and using scientific evidence, assisting the government with a budget and technical expertise, providing decision-makers with opportunities to learn from other countries, and building relationships with the key actor. External actors can be a major force to support the emergence of a public policy in Laos, but this requires a window of opportunity like what the MDGs have been able to bring. 展开更多
关键词 External Actors Advocacy coalition Strategy Influence Nutrition Policy Lao PDR
下载PDF
ANALYSIS OF GROUP MULTIUSER DETECTION BASED ON COALITION GAME THEORY 被引量:1
10
作者 Li Cuilian Yang Zhen 《Journal of Electronics(China)》 2009年第6期804-811,共8页
Coalition game theory is introduced to investigate the performance,fairness and stability of decorrelating group multiuser detection receiver,not only from the perspective of individual nodes,but also various coalitio... Coalition game theory is introduced to investigate the performance,fairness and stability of decorrelating group multiuser detection receiver,not only from the perspective of individual nodes,but also various coalitions and the whole system as well. Firstly,to derive how the system scale with coalition size,a stochastic model with transferable payoffs (stochastic TU-model) is provided. Secondly,to find the most preferred coalition structures from the view point of individual nodes,a model with Non-Transferable payoffs (NTU-model) is presented. Theoretical analysis and simulation results suggest that stochasticaly the grand coalition is payoff maximizing for the system as a whole,while individual nodes with good-conditioned channels may prefer local "win-win coalitions". 展开更多
关键词 coalition game CORE Multiuser detection RATIONALITY
下载PDF
EIAS:An Efficient Identity-Based Aggregate Signature Scheme for WSNs Against Coalition Attack 被引量:1
11
作者 Yong Xie Fang Xu +3 位作者 Xiang Li Songsong Zhang Xiaodan Zhang Muhammad Israr 《Computers, Materials & Continua》 SCIE EI 2019年第6期903-924,共22页
Wireless sensor networks(WSNs)are the major contributors to big data acquisition.The authenticity and integrity of the data are two most important basic requirements for various services based on big data.Data aggrega... Wireless sensor networks(WSNs)are the major contributors to big data acquisition.The authenticity and integrity of the data are two most important basic requirements for various services based on big data.Data aggregation is a promising method to decrease operation cost for resource-constrained WSNs.However,the process of data acquisitions in WSNs are in open environments,data aggregation is vulnerable to more special security attacks with hiding feature and subjective fraudulence,such as coalition attack.Aimed to provide data authenticity and integrity protection for WSNs,an efficient and secure identity-based aggregate signature scheme(EIAS)is proposed in this paper.Rigorous security proof shows that our proposed scheme can be secure against all kinds of attacks.The performance comparisons shows EIAS has clear advantages in term of computation cost and communication cost when compared with similar data aggregation scheme for WSNs. 展开更多
关键词 Wireless sensor networks(WSNs) big data signature aggregation efficiency coalition attack
下载PDF
Multi-task Coalition Parallel Formation Strategy Based on Reinforcement Learning 被引量:6
12
作者 JIANG Jian-Guo SU Zhao-Pin +1 位作者 QI Mei-Bin ZHANG Guo-Fu 《自动化学报》 EI CSCD 北大核心 2008年第3期349-352,共4页
代理人联盟是代理人协作和合作的一种重要方式。形成一个联盟,代理人能提高他们的能力解决问题并且获得更多的实用程序。在这份报纸,新奇多工联盟平行形成策略被介绍,并且多工联盟形成的过程是一个 Markov 决定过程的结论理论上被证... 代理人联盟是代理人协作和合作的一种重要方式。形成一个联盟,代理人能提高他们的能力解决问题并且获得更多的实用程序。在这份报纸,新奇多工联盟平行形成策略被介绍,并且多工联盟形成的过程是一个 Markov 决定过程的结论理论上被证明。而且,学习的加强被用来解决多工联盟平行的代理人行为策略,和这个过程形成被描述。在多工面向的领域,策略罐头有效地并且平行形式多工联盟。 展开更多
关键词 强化学习 多任务合并 平行排列 马尔可夫决策过程
下载PDF
The Coalition Cooperative Game Method and Its Application in Multi-objective Optimization Design 被引量:1
13
作者 LI Bi-yan 《International Journal of Plant Engineering and Management》 2011年第2期125-128,共4页
This paper proposes a multi-objective optimization design method based on the coalition cooperative game theory where the three design goals have been seen as three game players. By calculating the affecting factors a... This paper proposes a multi-objective optimization design method based on the coalition cooperative game theory where the three design goals have been seen as three game players. By calculating the affecting factors and fuzzy clustering, the design variables are divided into different strategic spaces which belong to each player, then it constructs a payoff function based on the coalition mechanism. Each game player takes its own revenue function as a target and obtains the best strategy versus other players. The best strategies of all players consist of the strategy permutation of a round game and it obtains the final game solutions through multi-round games according to the convergence criterion. A multi-objective optimization example of the luff mechanism of compensative sheave block shows the effectiveness of the coalition cooperative game method. 展开更多
关键词 coalition cooperative game multi-objective optimization fuzzy clustering luff mechanism
下载PDF
Coalition Game Based Full-Duplex Concurrent Scheduling in Millimeter Wave Wireless Backhaul Network
14
作者 Haiyan Jiang Yong Niu +2 位作者 Jiayi Zhang Bo Ai Zhangdui Zhong 《China Communications》 SCIE CSCD 2019年第2期59-75,共17页
With the development of self-interference(SI) cancelation technology, full-duplex(FD) communication becomes possible. FD communication can theoretically double the spectral efficiency. When the time slot(TS) resources... With the development of self-interference(SI) cancelation technology, full-duplex(FD) communication becomes possible. FD communication can theoretically double the spectral efficiency. When the time slot(TS) resources are limited and the number of flows is large, the scheduling mechanism of the flows becomes more important. Therefore, the effectiveness of FD scheduling mechanism for the flows is studied in millimeter wave wireless backhaul network with the limited TS resources. We proposed a full duplex concurrent scheduling algorithm based on coalition game(FDCG) to maximize the number of flows with their QoS requirements satisfied. We transformed the problem of maximizing the number of flows with their QoS requirements satisfied into the problem of maximizing sum rate of concurrently scheduled flows in each slot. We obtained the scheduled flows with maximum sum rate in first slot by using coalition game.And then with certain restrictions, the maximum sum rate of concurrently scheduled flows can also be achieved in subsequent time slots. The simulation results show that the proposed FDCG algorithm canachieve superior performance in terms of the number of flows that meet their QoS requirements and system throughput compared with other three algorithms. 展开更多
关键词 MILLIMETER wave wireless BACKHAUL NETWORK coalition game CONCURRENT SCHEDULING maximum SUM rate
下载PDF
Coalition Emergency Response System, City Security and City Sustainable Development 被引量:1
15
作者 Weiliang Zeng Yanheng Zhu 《Chinese Business Review》 2005年第1期79-81,共3页
The relations among the establishment of Coalition Emergency Response System (CERS), city security and city sustainable development are analyzed in the article. According to the relation analysis, it is concluded th... The relations among the establishment of Coalition Emergency Response System (CERS), city security and city sustainable development are analyzed in the article. According to the relation analysis, it is concluded that cities should build up their CERS to deal with the thread of damage in China. The recommendations about the establishment of the system are also provided. 展开更多
关键词 coalition emergency response system city security city sustainable development
下载PDF
On Aspiration Solutions in Predicting Coalition Formationin Cooperative Games
16
作者 HUANG ZHENGAO AND WANG GUOQIU 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 1996年第4期475-486,共12页
This paper consists of two parts. The first part introduces the strict aspiration as a new aspiration solution concept, which is provedto be existent for any cooperative game. The second part deals with theunsolved p... This paper consists of two parts. The first part introduces the strict aspiration as a new aspiration solution concept, which is provedto be existent for any cooperative game. The second part deals with theunsolved problem put forward by Bennett by showing that there is atleast one payoff which is balanced, partnered and equal gains aspiration.The proof is algebraic and constructive, thus providing an algorithm forfinding such aspirations. 展开更多
关键词 Cooperative game coalition formation aspiration approach
下载PDF
Symptomatic Scaphotrapeziotrapezoid Carpal Coalition: The Natural History and a Surgical Option for Treatment
17
作者 M. Sajjad Athar George Aerialis +1 位作者 Neil Ashwood Gregory Bain 《Open Journal of Orthopedics》 2017年第5期127-139,共13页
Carpal coalitions are uncommon and are frequently asymptomatic. 15 Patients with persistent symptomatic scaphotrapeziotrapezoid (STT) carpal coalitions unresponsive to six months of conservative treatment with no hist... Carpal coalitions are uncommon and are frequently asymptomatic. 15 Patients with persistent symptomatic scaphotrapeziotrapezoid (STT) carpal coalitions unresponsive to six months of conservative treatment with no history of trauma went for further investigations. CT scans and bone scans revealed that coalition was the only abnormality to account for the patient’s ongoing problems. The senior authors explored the carpal coalition surgically excising the affected region and interposing capsular fibrous tissue. Histologically partial bony and cartilaginous bridging was evident with no features of degenerative arthritis being noted. Good or excellent subjective results were achieved in all patients at final review an average of 2.7 (1.0 - 4.2) years after surgery. All patients described significant reduction in visual analogue pain scores from an average of 71.5 to 18.4 points. The Green and O’Brien wrist scores improved from a mean of 58.2 to 94.2, with all patients returning to work with improved function. Normally carpal coalition is treated with arthrodesis or excision of part of the carpus. A further treatment option is outlined here with recreation of the joint space in symptomatic, isolated, nonsyndromic scaphotrapezio-trapezoidal coalition. 展开更多
关键词 CARPAL coalition Hand SYMPTOMATIC STT coalition CAPSULAR INTERPOSITION
下载PDF
Different Rationales of Coalition Formation and Incentives for Strategic Voting
18
作者 Eric Linhart Johannes Raabe 《Applied Mathematics》 2018年第7期836-860,共25页
Research on strategic voting has mainly focused on electoral system effects but largely neglected the impact of different rationales of coalition formation. Based on a formal model of rational party choice and a simul... Research on strategic voting has mainly focused on electoral system effects but largely neglected the impact of different rationales of coalition formation. Based on a formal model of rational party choice and a simulation study, we systematically investigate this impact and explore the implications. We show that the logic of the underlying coalition formation procedure clearly affects the degree to which the electorate is exposed to strategic incentives regarding the vote choice. The key implications are that sincere voting is more often in the voter’s best interest if parties are policy-seeking and if there is increased uncertainty during the stage of coalition formation. Furthermore, we explore how different types of coalition formation affect strategic incentives across the policy space. 展开更多
关键词 STRATEGIC VOTING coalitions DECISION THEORY Simulation
下载PDF
On the Coalitional Rationality of the Banzhaf Value and Other Non-Efficient Semivalues
19
作者 Irinel Dragan 《Applied Mathematics》 2015年第12期2069-2076,共8页
In the Inverse Set relative to a Semivalue, we are looking for a new game for which the Semivalue of the original game is coalitional rational. The problem is solved by means of the Power Game of the given game. The p... In the Inverse Set relative to a Semivalue, we are looking for a new game for which the Semivalue of the original game is coalitional rational. The problem is solved by means of the Power Game of the given game. The procedures of building the new game, as well as the case of the Banzhaf Value are illustrated by means of some examples. 展开更多
关键词 Semivalues POWER GAME POWER CORE coalitional RATIONALITY
下载PDF
On the Coalitional Rationality and the Egalitarian Nonseparable Contribution
20
作者 Irinel Dragan 《Applied Mathematics》 2019年第5期363-370,共8页
In earlier works we introduced the Inverse Problem, relative to the Shapley Value, then relative to Semivalues. In the explicit representation of the Inverse Set, the solution set of the Inverse Problem, we built a fa... In earlier works we introduced the Inverse Problem, relative to the Shapley Value, then relative to Semivalues. In the explicit representation of the Inverse Set, the solution set of the Inverse Problem, we built a family of games, called the almost null family, in which we determined more recently a game where the Shapley Value and the Egalitarian Allocations are colalitional rational. The Egalitarian Nonseparable Contribution is another value for cooperative transferable utilities games (TU games), showing how to allocate fairly the win of the grand coalition, in case that this has been formed. In the present paper, we solve the similar problem for this new value: given a nonnegative vector representing the Egalitarian Nonseparable Contribution of a TU game, find out a game in which the Egalitarian Nonseparable Contribution is kept the same, but it is colalitional rational. The new game will belong to the family of almost null games in the Inverse Set, relative to the Shapley Value, and it is proved that the threshold of coalitional rationality will be higher than the one for the Shapley Value. The needed previous results are shown in the introduction, the second section is devoted to the main results, while in the last section are discussed remarks and connected problems. Some numerical examples are illustrating the procedure of finding the new game. 展开更多
关键词 Shapley Value Egalitarian NONSEPARABLE CONTRIBUTION Inverse Set Family of ALMOST NULL GAMES coalitional RATIONALITY
下载PDF
上一页 1 2 61 下一页 到第
使用帮助 返回顶部