期刊文献+
共找到2,596篇文章
< 1 2 130 >
每页显示 20 50 100
基于C4.5决策树算法的调度规则挖掘与应用
1
作者 姜宏广 周谧 杨溢 《红水河》 2026年第1期1-5,共5页
针对水库群优化调度因模型“黑箱”特性导致决策逻辑不透明、实际采纳困难的问题,笔者提出一种“先优化、后挖掘”的数据驱动范式。以岷江—大渡河流域水库群为例,首先基于57年长系列多目标优化调度结果,构建包含水位、入库流量及预见... 针对水库群优化调度因模型“黑箱”特性导致决策逻辑不透明、实际采纳困难的问题,笔者提出一种“先优化、后挖掘”的数据驱动范式。以岷江—大渡河流域水库群为例,首先基于57年长系列多目标优化调度结果,构建包含水位、入库流量及预见期流量等特征的样本集;进而采用C4.5决策树算法,按月训练并提取出直观的“if-then”形式调度规则。结果表明:所提取规则能有效捕捉系统的主要调度逻辑;在枯水期可显著提升发电量,多数电站枯水期发电量增幅达0.39%~15.34%,全年发电量亦保持稳定或略有提高;同时,规则调度使下游高场站在90%、95%和98%保证率下的枯水期最小日流量虽略低于原优化结果,但差距极小。研究表明,基于C4.5决策树的规则挖掘方法,能够将复杂的数值优化方案转化为可理解、可验证、可执行的调度知识,在保障综合效益的前提下,显著提升了调度决策的可解释性与工程可信度,为水库群智能调度提供了具有实用价值的技术途径。 展开更多
关键词 水库调度 决策树 c4.5算法 调度规则挖掘 可解释性 岷江—大渡河流域
在线阅读 下载PDF
Application Comparison of Association Rules and C4.5 Rules in Land Evaluation 被引量:3
2
作者 李亭 杨敬锋 陈志民 《Agricultural Science & Technology》 CAS 2010年第4期144-147,共4页
Association rules and C4.5 rules can overcome the shortage of the traditional land evaluation methods and improve the intelligibility and efficiency of the land evaluation knowledge.In order to compare these two kinds... Association rules and C4.5 rules can overcome the shortage of the traditional land evaluation methods and improve the intelligibility and efficiency of the land evaluation knowledge.In order to compare these two kinds of classification rules in the application,two fuzzy classifiers were established by combining with fuzzy decision algorithm especially based on Second General Soil Survey of Guangdong Province.The results of experiments demonstrated that the fuzzy classifier based on association rules obtain a higher accuracy rate,but with more complex calculation process and more computational overhead;the fuzzy classifier based on C4.5 rules obtain a slightly lower accuracy,but with fast computation and simpler calculation. 展开更多
关键词 Land evaluation Association rules c4.5 algorithm Fuzzy decision
在线阅读 下载PDF
The Convergence of the Steepest Descent Algorithm for D.C.Optimization 被引量:1
3
作者 SONG Chun-ling XIA Zun-quan 《Chinese Quarterly Journal of Mathematics》 CSCD 北大核心 2007年第1期131-136,共6页
Some properties of a class of quasi-differentiable functions(the difference of two finite convex functions) are considered in this paper. And the convergence of the steepest descent algorithm for unconstrained and c... Some properties of a class of quasi-differentiable functions(the difference of two finite convex functions) are considered in this paper. And the convergence of the steepest descent algorithm for unconstrained and constrained quasi-differentiable programming is proved. 展开更多
关键词 nonsmooth optimization D. C. optimization upper semi-continuous lower semi-continuous steepest descent algorithm CONVERGENCE
在线阅读 下载PDF
A Hybrid Multifarious Clustering Algorithm for the Analysis of Memmogram Images
4
作者 T. Velmurugan E. Venkatesan 《Journal of Computer and Communications》 2019年第12期136-151,共16页
A number of clustering algorithms were used to analyze many databases in the field of image clustering. The main objective of this research work was to perform a comparative analysis of the two of the existing partiti... A number of clustering algorithms were used to analyze many databases in the field of image clustering. The main objective of this research work was to perform a comparative analysis of the two of the existing partitions based clustering algorithms and a hybrid clustering algorithm. The results verification done by using classification algorithms via its accuracy. The perfor-mance of clustering and classification algorithms were carried out in this work based on the tumor identification, cluster quality and other parameters like run time and volume complexity. Some of the well known classification algorithms were used to find the accuracy of produced results of the clustering algorithms. The performance of the clustering algorithms proved mean-ingful in many domains, particularly k-Means, FCM. In addition, the proposed multifarious clustering technique has revealed their efficiency in terms of performance in predicting tumor affected regions in mammogram images. The color images are converted in to gray scale images and then it is processed. Finally, it is identified the best method for the analysis of finding tumor in breast images. This research would be immensely useful to physicians and radiologist to identify cancer affected area in the breast. 展开更多
关键词 Medical IMAGES HYBRID Clusteing algorithm K-MEANS algorithm Fuzzy C MEANS algorithm Classification algorithms
在线阅读 下载PDF
Research of Improved Fuzzy c-means Algorithm Based on a New Metric Norm 被引量:2
5
作者 毛力 宋益春 +2 位作者 李引 杨弘 肖炜 《Journal of Shanghai Jiaotong university(Science)》 EI 2015年第1期51-55,共5页
For the question that fuzzy c-means(FCM)clustering algorithm has the disadvantages of being too sensitive to the initial cluster centers and easily trapped in local optima,this paper introduces a new metric norm in FC... For the question that fuzzy c-means(FCM)clustering algorithm has the disadvantages of being too sensitive to the initial cluster centers and easily trapped in local optima,this paper introduces a new metric norm in FCM and particle swarm optimization(PSO)clustering algorithm,and proposes a parallel optimization algorithm using an improved fuzzy c-means method combined with particle swarm optimization(AF-APSO).The experiment shows that the AF-APSO can avoid local optima,and get the best fitness and clustering performance significantly. 展开更多
关键词 fuzzy c-means(FCM) particle swarm optimization(PSO) clustering algorithm new metric norm
原文传递
Study on Prediction Model of Number of Rainstorm Days in Summer Based on C5.0 Decision Tree Algorithm
6
作者 Shi Yimin Chen Weiwei Zhu Yunfeng 《Meteorological and Environmental Research》 CAS 2019年第2期56-60,共5页
Based on the data of daily precipitation in Lianyungang area from 1951 to 2012 and various climate signal data from the National Climate Center website and the NOAA website,a model for predicting whether the number of... Based on the data of daily precipitation in Lianyungang area from 1951 to 2012 and various climate signal data from the National Climate Center website and the NOAA website,a model for predicting whether the number of rainstorm days in summer in Lianyungang area is large was established by the classical C5. 0 decision tree algorithm. The data samples in 48 years( accounting for about 80% of total number of samples)was as the training set of a model,and the training accuracy rate of the model was 95. 83%. The data samples in the remaining 14 years( accounting for about 20% of total number of samples) were used as the test set of the model to test the model,and the test accuracy of the model was 85. 71%. The results showed that the prediction model of number of rainstorm days in summer constructed by C5. 0 algorithm had high accuracy and was easy to explain. Moreover,it is convenient for meteorological staff to use directly. At the same time,this study provides a new idea for short-term climate prediction of number of rainstorm days in summer. 展开更多
关键词 C5. 0 algorithm NUMBER of RAINSTORM DAYS PREDICTION model
在线阅读 下载PDF
An Active Rule Approach for Network Intrusion Detection with Enhanced C4.5 Algorithm
7
作者 L Prema RAJESWARI Kannan ARPUTHARAJ 《International Journal of Communications, Network and System Sciences》 2008年第4期314-321,共8页
Intrusion detection systems provide additional defense capacity to a networked information system in addition to the security measures provided by the firewalls. This paper proposes an active rule based enhancement to... Intrusion detection systems provide additional defense capacity to a networked information system in addition to the security measures provided by the firewalls. This paper proposes an active rule based enhancement to the C4.5 algorithm for network intrusion detection in order to detect misuse behaviors of internal attackers through effective classification and decision making in computer networks. This enhanced C4.5 algorithm derives a set of classification rules from network audit data and then the generated rules are used to detect network intrusions in a real-time environment. Unlike most existing decision tree based approaches, the spawned rules generated and fired in this work are more effective because the information-theoretic approach minimizes the expected number of tests needed to classify an object and guarantees that a simple (but not necessarily the simplest) tree is found. The main advantage of this proposed algorithm is that the generalization ability of enhanced C4.5 decision trees is better than that of C4.5 decision trees. We have employed data from the third international knowledge discovery and data mining tools competition (KDDcup’99) to train and test the feasibility of this proposed model. By applying the enhanced C4.5 algorithm an average detection rate of 93.28 percent and a false positive rate of 0.7 percent have respectively been obtained in this work. 展开更多
关键词 Decision Tree INTRUSION Detection KDD CUP DATASET ENHANCED c4.5
在线阅读 下载PDF
A New Speculative Execution Algorithm Based on C4.5 Decision Tree for Hadoop
8
作者 Yuanzhen Li Qun Yang +1 位作者 Shangqi Lai Bohan Li 《国际计算机前沿大会会议论文集》 2015年第1期83-84,共2页
As a distributed computing platform, Hadoop provides an effective way to handle big data. In Hadoop, the completion time of job will be delayed by a straggler. Although the definitive cause of the straggler is hard to... As a distributed computing platform, Hadoop provides an effective way to handle big data. In Hadoop, the completion time of job will be delayed by a straggler. Although the definitive cause of the straggler is hard to detect, speculative execution is usually used for dealing with this problem, by simply backing up those stragglers on alternative nodes. In this paper, we design a new Speculative Execution algorithm based on C4.5 Decision Tree, SECDT, for Hadoop. In SECDT, we speculate completion time of stragglers and also of backup tasks, based on a kind of decision tree method: C4.5 decision tree. After we speculate the completion time, we compare the completion time of stragglers and of the backup tasks, calculating their differential value, and selecting the straggler with the maximum differential value to start the backup task.Experiment result shows that the SECDT can predict execution time more accurately than other speculative execution methods, hence reduce the job completion time. 展开更多
关键词 SPECULATIVE EXECUTION c4.5 DECISION TREE HADOOP
在线阅读 下载PDF
Decision Tree and Naive Bayes Algorithm for Classification and Generation of Actionable Knowledge for Direct Marketing
9
作者 Masud Karim Rashedur M.Rahman 《Journal of Software Engineering and Applications》 2013年第4期196-206,共11页
Many companies like credit card, insurance, bank, retail industry require direct marketing. Data mining can help those institutes to set marketing goal. Data mining techniques have good prospects in their target audie... Many companies like credit card, insurance, bank, retail industry require direct marketing. Data mining can help those institutes to set marketing goal. Data mining techniques have good prospects in their target audiences and improve the likelihood of response. In this work we have investigated two data mining techniques: the Naive Bayes and the C4.5 decision tree algorithms. The goal of this work is to predict whether a client will subscribe a term deposit. We also made comparative study of performance of those two algorithms. Publicly available UCI data is used to train and test the performance of the algorithms. Besides, we extract actionable knowledge from decision tree that focuses to take interesting and important decision in business area. 展开更多
关键词 CRM Actionable KNOWLEDGE Data Mining c4.5 NAIVE BAYES ROC CLASSIFICATION
暂未订购
ALGORITHMS FOR A SYSTEM OF GENERALIZED MIXED EQUILIBRIUM PROBLEMS AND A COUNTABLE FAMILY OF SOME NONLINEAR MULTI-VALUED NONEXPANSIVE-TYPE MAPS
10
作者 Ogonnaya Michael ROMANUS Ukamaka Victoria NNYABA Monday Ogudu NNAKWE 《Acta Mathematica Scientia》 SCIE CSCD 2018年第6期1805-1820,共16页
In this paper, relaxed iterative algorithms of Krasnoselskii-type and Halpern-type that approximate a solution of a system of a generalized mixed equilibrium problem anda common fixed point of a countable family of to... In this paper, relaxed iterative algorithms of Krasnoselskii-type and Halpern-type that approximate a solution of a system of a generalized mixed equilibrium problem anda common fixed point of a countable family of totally quasi-C-asymptotically nonexpansivemulti-valued maps are constructed. Strong convergence of the sequence generated by thesealgorithms is proved in uniformly smooth and strictly convex real Banach spaces with Kadec-Klee property. Furthermore, several applications of our theorems are also presented. Finally,our theorems are significant improvements on several important recent results for this classof nonlinear problems. 展开更多
关键词 Halpern-type algorithm Krasnoselskii-type algorithm system of generalizedmixed equilibrium problems totally quasi-C-asymptotically nonexpansive multi-valued maps equally continuous maps
在线阅读 下载PDF
改进型C4.5算法在多波束点云自动消噪中的应用
11
作者 史俊明 卢清国 《海洋测绘》 北大核心 2025年第1期21-24,30,共5页
传统C4.5算法广泛应用于多波束测深系统中水深点与噪声点的自动分离,但是该算法中存在过拟合和属性相关性问题。为解决传统C4.5算法的缺陷,引入改进型C4.5算法,提出了通过计算属性依赖度更新数据集合的方法。首先通过点云之间的点特征... 传统C4.5算法广泛应用于多波束测深系统中水深点与噪声点的自动分离,但是该算法中存在过拟合和属性相关性问题。为解决传统C4.5算法的缺陷,引入改进型C4.5算法,提出了通过计算属性依赖度更新数据集合的方法。首先通过点云之间的点特征、区域特征、窗口特征等建立数据集合,并对连续特征属性进行离散化处理。然后构建决策树,利用信息增益率判断根节点(即确定最优属性划分),迭代更新,完成数据集合的分类,并对整体数据进行后剪枝处理。采用多种地形对本文算法训练效果进行交叉评定,证明本文算法的泛化能力和准确度较高。 展开更多
关键词 海洋测绘 多波束测深系统 改进型c4.5算法 信息增益率 属性依赖度 后剪枝
在线阅读 下载PDF
Agent Based Segmentation of the MRI Brain Using a Robust C-Means Algorithm
12
作者 Hanane Barrah Abdeljabbar Cherkaoui Driss Sarsri 《Journal of Computer and Communications》 2016年第10期13-21,共9页
In the last decade, the MRI (Magnetic Resonance Imaging) image segmentation has become one of the most active research fields in the medical imaging domain. Because of the fuzzy nature of the MRI images, many research... In the last decade, the MRI (Magnetic Resonance Imaging) image segmentation has become one of the most active research fields in the medical imaging domain. Because of the fuzzy nature of the MRI images, many researchers have adopted the fuzzy clustering approach to segment them. In this work, a fast and robust multi-agent system (MAS) for MRI segmentation of the brain is proposed. This system gets its robustness from a robust c-means algorithm (RFCM) and obtains its fastness from the beneficial properties of agents, such as autonomy, social ability and reactivity. To show the efficiency of the proposed method, we test it on a normal brain brought from the BrainWeb Simulated Brain Database. The experimental results are valuable in both robustness to noise and running times standpoints. 展开更多
关键词 Agents and MAS MR Images Fuzzy Clustering C-Means algorithm Image Segmentation
在线阅读 下载PDF
Optimal Approximation Algorithms for Reoptimization of Constraint Satisfaction Problems
13
作者 Victor Alex Mikhailyuk 《American Journal of Operations Research》 2013年第2期279-288,共10页
The purpose of reoptimization using approximation methods—application of knowledge about the solution of the initial instance I, provided to achieve a better quality of approximation (approximation ratio) of an algor... The purpose of reoptimization using approximation methods—application of knowledge about the solution of the initial instance I, provided to achieve a better quality of approximation (approximation ratio) of an algorithm for determining optimal or close to it solutions of some “minor” changes of instance I. To solve the problem Ins-Max-EkCSP-P (reoptimization of Max-EkCSP-P with the addition of one constraint) with approximation resistant predicate P exists a polynomial threshold (optimal) -approximation algorithm, where the threshold “random” approximation ratio of P). When the unique games conjecture (UGC) is hold there exists a polynomial threshold (optimal) -approximation algorithm (where and the integrality gap of semidefinite relaxation of Max-EkCSP-P problem Z) to solve the problem Ins-Max-EkCSP-P. 展开更多
关键词 C-Approximation algorithm REOPTIMIZATION APPROXIMATION Resistant Predicates INTEGRALITY Gap Unique GAMES CONJECTURE (UGC)
在线阅读 下载PDF
A 3-Dimensional Cargo Loading Algorithm for the Conveyor-Type Loading System
14
作者 Hyeonbin Jeong Young Tae Ryu +1 位作者 Byung Duk Song Sang-Duck Lee 《Computer Modeling in Engineering & Sciences》 2025年第3期2739-2769,共31页
This paper proposes a novel cargo loading algorithm applicable to automated conveyor-type loading systems.The algorithm offers improvements in computational efficiency and robustness by utilizing the concept of discre... This paper proposes a novel cargo loading algorithm applicable to automated conveyor-type loading systems.The algorithm offers improvements in computational efficiency and robustness by utilizing the concept of discrete derivatives and introducing logistics-related constraints.Optional consideration of the rotation of the cargoes was made to further enhance the optimality of the solutions,if possible to be physically implemented.Evaluation metrics were developed for accurate evaluation and enhancement of the algorithm’s ability to efficiently utilize the loading space and provide a high level of dynamic stability.Experimental results demonstrate the extensive robustness of the proposed algorithm to the diversity of cargoes present in Business-to-Consumer environments.This study contributes practical advancements in both cargo loading optimization and automation of the logistics industry,with potential applications in last-mile delivery services,warehousing,and supply chain management. 展开更多
关键词 3-dimensional loading automated loading system B2C logistics cargo loading algorithm conveyortype loading
在线阅读 下载PDF
基于WOA-BP-LSTM自编码器的CFRP薄壁C柱轴压响应预测
15
作者 牟浩蕾 张贾 +1 位作者 冯振宇 白春玉 《航空学报》 北大核心 2026年第4期112-124,共13页
针对航空器货舱下部碳纤维增强复合材料(CFRP)薄壁C柱在准静态轴压下的力-位移响应预测问题,提出了一种融合鲸鱼优化算法(WOA)、反向传播(BP)神经网络和长短期记忆(LSTM)自编码器的智能预测模型(WOA-BPLSTM自编码器模型)。通过CFRP薄壁... 针对航空器货舱下部碳纤维增强复合材料(CFRP)薄壁C柱在准静态轴压下的力-位移响应预测问题,提出了一种融合鲸鱼优化算法(WOA)、反向传播(BP)神经网络和长短期记忆(LSTM)自编码器的智能预测模型(WOA-BPLSTM自编码器模型)。通过CFRP薄壁C柱准静态轴压试验验证了有限元模型可靠性,其轴压响应评价指标误差均小于10%,基于该模型构建了包含700组变截面几何参数的力-位移响应数据集。采用LSTM自编码器实现力-位移响应特征降维与重建,随后采用BP神经网络对力-位移响应进行预测,并采用WOA进行神经网络参数优化。结果表明,LSTM自编码器实现了力-位移响应的高精度重建,测试集初始峰值压溃力和能量吸收的重建误差均小于3%,80%样本误差小于1%;优化后预测模型的力-位移响应预测精度显著提升,测试集平均绝对误差(MAE)降低17.55%,均方误差(MSE)降低31.77%,均方根误差(RMSE)降低17.47%,初始峰值压溃力和能量吸收的预测误差均小于8%,80%样本误差小于5%。该智能预测模型实现了变截面CFRP薄壁C柱轴压响应的快速精准预测并降低了计算成本,为其轴压响应研究提供了一种高效的参数-性能映射工具。 展开更多
关键词 CFRP薄壁C柱 轴压响应 LSTM自编码器 鲸鱼优化算法 BP神经网络
原文传递
基于改进动麦优化模糊C-均值的WSN分簇信誉路由算法
16
作者 韩冰青 温锦笑 《计算机应用研究》 北大核心 2026年第1期240-246,共7页
针对无线传感器网络中分簇不均、节点能耗高及路由安全性低等问题,提出一种基于改进动麦优化模糊C-means的WSN分簇信誉路由算法(IFCAOR)。首先利用改进的动麦算法优化模糊C-means算法的初始聚类中心,提高网络分簇效果。其次,在簇首选举... 针对无线传感器网络中分簇不均、节点能耗高及路由安全性低等问题,提出一种基于改进动麦优化模糊C-means的WSN分簇信誉路由算法(IFCAOR)。首先利用改进的动麦算法优化模糊C-means算法的初始聚类中心,提高网络分簇效果。其次,在簇首选举阶段,综合节点能量、距离等因素,动态选择簇首,实现负载均衡。最后,在数据传输阶段,采用单多跳轮询机制,并结合中继节点的负载、信誉值和路径衰减等构建路由适应度函数,利用改进动麦算法规划高效安全的传输路由,降低节点能耗并提高路由安全性。仿真结果表明,IFCAOR算法的网络生命周期较LEACH、IFCRA和HMABFOA分别提升93%、49.6%和34.3%,IFCAOR算法能有效平衡网络负载,延长网络生命周期。 展开更多
关键词 无线传感器网络 模糊C-均值 动麦优化算法 分簇路由 能耗均衡
在线阅读 下载PDF
基于H-C方法的地震发震断层快速识别——以2017年12月19日辽宁海城M4.4地震为例
17
作者 戴盈磊 张文静 +2 位作者 惠杨 王承伟 程应伟 《华南地震》 2026年第1期33-42,共10页
应用“先粗后细”的网格划分方案和CAP方法反演2017年12月19日辽宁海城M4.4地震震源机制解。基于震源—质心(H-C)方法快速测定其发震断层面。利用改进的DBSCAN算法自动识别海城、岫岩地区主要断层的几何参数,并结合该地区构造应力场给... 应用“先粗后细”的网格划分方案和CAP方法反演2017年12月19日辽宁海城M4.4地震震源机制解。基于震源—质心(H-C)方法快速测定其发震断层面。利用改进的DBSCAN算法自动识别海城、岫岩地区主要断层的几何参数,并结合该地区构造应力场给出它们的滑动性质。结果表明:海城M4.4地震最优质心位置为(40.4672°N,123.1494°E)。震源机制解走向288°,标准差5.80°,倾角81°,标准差5.69°,滑动角-13°,标准差5.71°,矩震级MW4.34,质心深度11 km,标准差0.38 km。联合P波初动解走向34.10°,倾角67.48°,滑动角-159.64°,及其他学者的资料得到该地震震源机制中心解为走向287.51°,倾角78.66°,滑动角-22.90°。以各机构给出的震源参数和不同震源机制进行的全部25次快速识别检验均显示震源机制解NWW走向的节面II是本次海城M4.4地震的主断层面。自动识别得到3个走滑断层和1个正断层。其中断层A和断层C分别是1975年海城MS7.3地震和1999年岫岩MS5.4地震的发震构造,断层B和断层D的参数特征也与前人的认识相符。 展开更多
关键词 海城M4.4地震 H-C方法 CAP方法 震源机制解 发震断层 改进的DBSCAN
在线阅读 下载PDF
应用C4.5算法构造客户分类决策树的方法 被引量:37
18
作者 王晓国 黄韶坤 +1 位作者 朱炜 李启炎 《计算机工程》 CAS CSCD 北大核心 2003年第14期89-91,共3页
客户等级划分是CRM中一个非常重要的方面,而决策树是进行分类分析的一个常用工具,该文主要讨论如何应用C4.5算法构造客户等级分类决策树及其在CRM中的应用。
关键词 决策树 客户关系管理 C 4.5
在线阅读 下载PDF
基于多层次模糊C-均值算法的个性化大数据分析服务
19
作者 吴淑英 《自动化与仪器仪表》 2026年第2期25-29,共5页
随着信息技术的飞速发展,海量大数据的分析和处理已成为各行各业的重要需求。为了应对这一挑战,研究基于多层次模糊C-均值(Fuzzy C-Means,FCM)算法对云储存平台进行个性化大数据分析服务,利用模糊聚类技术处理大规模数据集中的模糊性和... 随着信息技术的飞速发展,海量大数据的分析和处理已成为各行各业的重要需求。为了应对这一挑战,研究基于多层次模糊C-均值(Fuzzy C-Means,FCM)算法对云储存平台进行个性化大数据分析服务,利用模糊聚类技术处理大规模数据集中的模糊性和不确定性,并通过多层次的分析框架来提供定制化的数据分析结果。结果显示,在消费用户和免费用户的数据分析中,研究方法的最大误差分别为0.18和0.15。最大平均响应时间和最大平均分析时间分别为2.89 ms和2.75 ms。综上所述,研究方法在保持数据准确性的同时,有效处理了大数据中的异质性和复杂性,提高了数据处理效率,为大数据时代的智能分析提供了新的解决方案。 展开更多
关键词 大数据分析 模糊C-均值算法 多层次分析 聚类分析 个性化
原文传递
上一页 1 2 130 下一页 到第
使用帮助 返回顶部