期刊文献+
共找到366篇文章
< 1 2 19 >
每页显示 20 50 100
Modified Exact Jacobian Semidefinite Programming Relaxation for Celis-Dennis-Tapia Problem
1
作者 赵馨 孔汕汕 《Journal of Donghua University(English Edition)》 CAS 2023年第1期96-104,共9页
A modified exact Jacobian semidefinite programming(SDP)relaxation method is proposed in this paper to solve the Celis-Dennis-Tapia(CDT)problem using the Jacobian matrix of objective and constraining polynomials.In the... A modified exact Jacobian semidefinite programming(SDP)relaxation method is proposed in this paper to solve the Celis-Dennis-Tapia(CDT)problem using the Jacobian matrix of objective and constraining polynomials.In the modified relaxation problem,the number of introduced constraints and the lowest relaxation order decreases significantly.At the same time,the finite convergence property is guaranteed.In addition,the proposed method can be applied to the quadratically constrained problem with two quadratic constraints.Moreover,the efficiency of the proposed method is verified by numerical experiments. 展开更多
关键词 Celis-Dennis-Tapia(CDT)problem quadratically constrained problem with two quadratic constraints semidefinite programming(sdp)relaxation method
在线阅读 下载PDF
基于SDP松弛的干扰资源优化分配技术研究 被引量:2
2
作者 陆文博 刘春生 周青松 《现代防御技术》 北大核心 2014年第6期167-172,共6页
提出一种基于semidefinite programming(简称SDP)松弛的干扰资源优化分配算法。在问题优化过程中首先对模型中非凸的约束条件进行松弛,变为凸约束,将原来的数学模型转化成SDP求解形式,利用内点算法对松弛后的模型求解。该算法利用解析... 提出一种基于semidefinite programming(简称SDP)松弛的干扰资源优化分配算法。在问题优化过程中首先对模型中非凸的约束条件进行松弛,变为凸约束,将原来的数学模型转化成SDP求解形式,利用内点算法对松弛后的模型求解。该算法利用解析的手段使得干扰资源优化分配问题中的NP难问题在多项式时间内得以解决,并且有较高的可靠性。仿真结果验证了算法的有效性。 展开更多
关键词 凸优化 sdp松弛 干扰资源 优化分配
在线阅读 下载PDF
基于矩阵分解的0-1二次规划的SDP松弛 被引量:2
3
作者 蔡伟荣 柳叶 罗和治 《浙江工业大学学报》 CAS 北大核心 2015年第5期582-586,共5页
0-1二次规划是整数规划中一类重要的最优化问题,广泛应用于工程、经济管理、金融和管理科学等许多重要领域.利用矩阵分解方法,给出了带线性约束的0-1二次规划的一个紧的SDP松弛.通过目标函数的矩阵分解并利用二次项的片段线性逼近技术,... 0-1二次规划是整数规划中一类重要的最优化问题,广泛应用于工程、经济管理、金融和管理科学等许多重要领域.利用矩阵分解方法,给出了带线性约束的0-1二次规划的一个紧的SDP松弛.通过目标函数的矩阵分解并利用二次项的片段线性逼近技术,得到了原问题的一个凸松弛.再利用锥优化对偶性,证明了寻找凸松弛中的最优参数问题可以归结为求解一个SDP问题,数值结果也表明该SDP松弛能提供原问题的一个更紧的下界. 展开更多
关键词 0-1二次规划 sdp松弛 矩阵分解 片段线性逼近
在线阅读 下载PDF
稳健交通均衡模型的SDP松弛 被引量:1
4
作者 张倩 张超 修乃华 《运筹与管理》 CSSCI CSCD 北大核心 2013年第1期1-8,共8页
交通均衡问题在城市交通管理中具有重要意义.研究均衡交通的目的是通过对稳定交通流进行量化分析,为决策者提供交通规划及管理的依据.Wardrop交通均衡原理是描述交通均衡问题的基石,本文在其扩展之一的稳健Wardrop(Robust Wardrop,简记... 交通均衡问题在城市交通管理中具有重要意义.研究均衡交通的目的是通过对稳定交通流进行量化分析,为决策者提供交通规划及管理的依据.Wardrop交通均衡原理是描述交通均衡问题的基石,本文在其扩展之一的稳健Wardrop(Robust Wardrop,简记为RW)互补均衡模型的基础上,将不确定因素的盒子约束改进为球约束,以改善原有模型的保守度.其次给出带有不确定因素的稳健Wardrop极小化形式及其确定性稳健对应模型(Robust Counterpart,简记为RC).最后通过SDP松弛手段将稳健对应模型(RC)松弛为容易的线性半定规划问题进行求解,并给出实例说明,为不确定因素影响下的交通均衡问题提供了一种新的有效模型及解法. 展开更多
关键词 运筹学 sdp交通均衡模型 半定松弛 交通均衡流
在线阅读 下载PDF
不确定平方和凸多项式优化的SDP松弛与鲁棒鞍点刻画 被引量:1
5
作者 谭玟 孙祥凯 《吉林大学学报(理学版)》 CAS 北大核心 2023年第3期525-530,共6页
考虑一类带不确定参数的平方和凸多项式优化问题.首先,借助鲁棒优化方法给出该不确定平方和凸多项式优化问题的鲁棒对等优化模型;然后,借助一类鲁棒型特征锥约束规格,建立该优化问题的精确半正定规划(SDP)松弛问题;最后,引入该不确定平... 考虑一类带不确定参数的平方和凸多项式优化问题.首先,借助鲁棒优化方法给出该不确定平方和凸多项式优化问题的鲁棒对等优化模型;然后,借助一类鲁棒型特征锥约束规格,建立该优化问题的精确半正定规划(SDP)松弛问题;最后,引入该不确定平方和凸多项式优化问题的Langrange函数,并借助平方和条件给出该不确定平方和凸多项式优化问题的鲁棒鞍点定理. 展开更多
关键词 平方和凸多项式优化 鞍点 平方和条件 sdp松弛问题
在线阅读 下载PDF
基于DC分解的非凸二次规划SDP近似解 被引量:1
6
作者 王延菲 郑小金 《应用数学与计算数学学报》 2009年第2期102-110,共9页
本文提出一类基于DC分解的非凸二次规划问题SDP松弛方法,并通过求解一个二阶锥问题得到原问题的近似最优解.我们首先对非凸二次目标函数进行DC分解,然后利用线性下逼近得到一个凸二次松弛问题,而最优的DC分解可通过求解一个SDP问题得到... 本文提出一类基于DC分解的非凸二次规划问题SDP松弛方法,并通过求解一个二阶锥问题得到原问题的近似最优解.我们首先对非凸二次目标函数进行DC分解,然后利用线性下逼近得到一个凸二次松弛问题,而最优的DC分解可通过求解一个SDP问题得到.数值试验表明,基于DC分解的SDP近似解平均优于经典SDP松弛和随机化方法产生的近似解。 展开更多
关键词 非凸二次规划问题 凸二次约束 sdp松弛 DC分解方法 随机化方法
在线阅读 下载PDF
A DUAL-RELAX PENALTY FUNCTION APPROACH FOR SOLVING NONLINEAR BILEVEL PROGRAMMING WITH LINEAR LOWER LEVEL PROBLEM 被引量:7
7
作者 万仲平 王广民 吕一兵 《Acta Mathematica Scientia》 SCIE CSCD 2011年第2期652-660,共9页
The penalty function method, presented many years ago, is an important nu- merical method for the mathematical programming problems. In this article, we propose a dual-relax penalty function approach, which is signifi... The penalty function method, presented many years ago, is an important nu- merical method for the mathematical programming problems. In this article, we propose a dual-relax penalty function approach, which is significantly different from penalty func- tion approach existing for solving the bilevel programming, to solve the nonlinear bilevel programming with linear lower level problem. Our algorithm will redound to the error analysis for computing an approximate solution to the bilevel programming. The error estimate is obtained among the optimal objective function value of the dual-relax penalty problem and of the original bilevel programming problem. An example is illustrated to show the feasibility of the proposed approach. 展开更多
关键词 Nonlinear bilevel programming penalty function approach dual-relax strategy
在线阅读 下载PDF
The dynamic relaxation form finding method aided with advanced recurrent neural network 被引量:1
8
作者 Liming Zhao Zhongbo Sun +1 位作者 Keping Liu Jiliang Zhang 《CAAI Transactions on Intelligence Technology》 SCIE EI 2023年第3期635-644,共10页
How to establish a self‐equilibrium configuration is vital for further kinematics and dynamics analyses of tensegrity mechanism.In this study,for investigating tensegrity form‐finding problems,a concise and efficien... How to establish a self‐equilibrium configuration is vital for further kinematics and dynamics analyses of tensegrity mechanism.In this study,for investigating tensegrity form‐finding problems,a concise and efficient dynamic relaxation‐noise tolerant zeroing neural network(DR‐NTZNN)form‐finding algorithm is established through analysing the physical properties of tensegrity structures.In addition,the non‐linear constrained opti-misation problem which transformed from the form‐finding problem is solved by a sequential quadratic programming algorithm.Moreover,the noise may produce in the form‐finding process that includes the round‐off errors which are brought by the approximate matrix and restart point calculating course,disturbance caused by external force and manufacturing error when constructing a tensegrity structure.Hence,for the purpose of suppressing the noise,a noise tolerant zeroing neural network is presented to solve the search direction,which can endow the anti‐noise capability to the form‐finding model and enhance the calculation capability.Besides,the dynamic relaxation method is contributed to seek the nodal coordinates rapidly when the search direction is acquired.The numerical results show the form‐finding model has a huge capability for high‐dimensional free form cable‐strut mechanisms with complicated topology.Eventually,comparing with other existing form‐finding methods,the contrast simulations reveal the excellent anti‐noise performance and calculation capacity of DR‐NTZNN form‐finding algorithm. 展开更多
关键词 dynamic relaxation form‐finding noise‐tolerant zeroing neural network sequential quadratic programming TENSEGRITY
在线阅读 下载PDF
ON SOME PROPERTIES OF SOLUTIONS TO SEMIDEFINITE PROGRAMMING
9
作者 韩乔明 《Numerical Mathematics A Journal of Chinese Universities(English Series)》 SCIE 1997年第2期208-218,共11页
It is well known that for symmetric linear programming there exists a strictly complementary solution if the primal and the dual problems are both feasible. However, this is not necessary true for symmetric or general... It is well known that for symmetric linear programming there exists a strictly complementary solution if the primal and the dual problems are both feasible. However, this is not necessary true for symmetric or general semide finite programming even if both the primal problem and its dual problem are strictly feasible. Some other properties are also concerned. 展开更多
关键词 semide FINITE programming (sdp) linear programming (LP) STRICTLY feasible STRICTLY COMPLEMENTARY optimal pair.
在线阅读 下载PDF
LINEARIZATION RELAXATION PROCEDURE FOR A KIND OF N-DIMENSIONAL NONLINEAR OPTIMIZATION PROBLEM
10
作者 徐飞 王浣尘 《Journal of Shanghai Jiaotong university(Science)》 EI 1998年第2期91-94,共4页
This paper is concerned with a class of convex multivariable nonlinear program problems. By virtue of linearization philosophy, a linearization problem (LP) is constructed and theoretical equivalence between (LP) and ... This paper is concerned with a class of convex multivariable nonlinear program problems. By virtue of linearization philosophy, a linearization problem (LP) is constructed and theoretical equivalence between (LP) and the original problem established. Based on relaxation techniques an algorithm for solving (LP) is proposed, which is efficient from a computational viewpoint, since at each iteration the only program that needs to solve is a standard linear program. Furthermore, the optimality criterion is derived. The convergence analysis conducted in this paper indicates that the algorithm guarantees finite ε convergence. 展开更多
关键词 LINEARIZATION relaxation techniques NONLINEAR programming
在线阅读 下载PDF
Semidefinite programming approach for TDOA/GROA based source localization
11
作者 Yanshen Du Ping Wei Huaguo Zhang 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2015年第4期680-687,共8页
Time-differences-of-arrival (TDOA) and gain-ratios-of- arrival (GROA) measurements are used to determine the passive source location. Based on the measurement models, the con- strained weighted least squares (CWL... Time-differences-of-arrival (TDOA) and gain-ratios-of- arrival (GROA) measurements are used to determine the passive source location. Based on the measurement models, the con- strained weighted least squares (CWLS) estimator is presented. Due to the nonconvex nature of the CWLS problem, it is difficult to obtain its globally optimal solution. However, according to the semidefinite relaxation, the CWLS problem can be relaxed as a convex semidefinite programming problem (SDP), which can be solved by using modern convex optimization algorithms. Moreover, this relaxation can be proved to be tight, i.e., the SDP solves the relaxed CWLS problem, and this hence guarantees the good per- formance of the proposed method. Furthermore, this method is extended to solve the localization problem with sensor position errors. Simulation results corroborate the theoretical results and the good performance of the proposed method. 展开更多
关键词 gain ratios of arrival (GROA) time difference of arrival(TDOA) LOCALIZATION constrained weighted least squares (CWLS) semidefinite programming problem sdp).
在线阅读 下载PDF
A Lagrange Relaxation Based Approach to Solve a Discrete-Continous Bi-Level Model
12
作者 Zaida E. Alarcón-Bernal Ricardo Aceves-García 《Open Journal of Optimization》 2019年第3期100-111,共12页
In this work we propose a solution method based on Lagrange relaxation for discrete-continuous bi-level problems, with binary variables in the leading problem, considering the optimistic approach in bi-level programmi... In this work we propose a solution method based on Lagrange relaxation for discrete-continuous bi-level problems, with binary variables in the leading problem, considering the optimistic approach in bi-level programming. For the application of the method, the two-level problem is reformulated using the Karush-Kuhn-Tucker conditions. The resulting model is linearized taking advantage of the structure of the leading problem. Using a Lagrange relaxation algorithm, it is possible to find a global solution efficiently. The algorithm was tested to show how it performs. 展开更多
关键词 Bi-Level programming LAGRANGE relaxation Discrete-Continous LINEAR Bilevel
在线阅读 下载PDF
Nonconvex Quadratic Programming Method for k-Coloring Problem:Algorithm and Computation
13
作者 Cao Jiaming(Department of Transportation Engineering) ,Southwest Jiaotong University,Chengdu 610031, China 《Journal of Modern Transportation》 1994年第2期138-145,共8页
In this paper, we consider the socalled k-coloring problem in general case.Firstly, a special quadratic 0-1 programming is constructed to formulate k-coloring problem. Secondly, by use of the equivalence between above... In this paper, we consider the socalled k-coloring problem in general case.Firstly, a special quadratic 0-1 programming is constructed to formulate k-coloring problem. Secondly, by use of the equivalence between above quadratic0-1 programming and its relaxed problem, k-coloring problem is converted intoa class of (continuous) nonconvex quadratic programs, and several theoreticresults are also introduced. Thirdly, linear programming approximate algorithmis quoted and verified for this class of nonconvex quadratic programs. Finally,examining problems which are used to test the algorithm are constructed andsufficient computation experiments are reported. 展开更多
关键词 k-coloring problem quadratic 0-1 programming relaxed equivalence nonconvex quadratic programming linear programming approximatealgorithm
在线阅读 下载PDF
球约束加权极大极小离差问题的SDP松弛的注记
14
作者 张思颖 罗洪林 《重庆师范大学学报(自然科学版)》 CAS 北大核心 2020年第1期107-112,共6页
【目的】研究利用CVX软件有效求解球约束下的加权极大极小离差问题的SDP松弛模型。【方法】应用半定规划的强对偶定理和Gershgorin圆盘定理。【结果】证明了Haines等人给出的球形约束下离差问题的SDP松弛的解的存在性;同时提出了另一个... 【目的】研究利用CVX软件有效求解球约束下的加权极大极小离差问题的SDP松弛模型。【方法】应用半定规划的强对偶定理和Gershgorin圆盘定理。【结果】证明了Haines等人给出的球形约束下离差问题的SDP松弛的解的存在性;同时提出了另一个球形约束下的离差问题,并给出了它的SDP松弛模型的解的存在性证明。【结论】提出的新的证明方法为CVX中嵌入的SeDuMi和SDPT3这两种内点算法提供了有效求解SDP松弛模型的理论依据。 展开更多
关键词 半定规划松弛 球约束加权极大极小离差问题 Gershgorin圆盘定理 强对偶定理
原文传递
Unit Commitment with Production Cost Uncertainty: A Recourse Programming Method
15
作者 H. Borsenberger Ph. Dessante G. Sandou 《Journal of Energy and Power Engineering》 2011年第2期164-172,共9页
Many studies have considered the solution of Unit Commitment problems for the management of energy networks. In this field, earlier work addressed the problem in determinist cases and in cases dealing with demand unce... Many studies have considered the solution of Unit Commitment problems for the management of energy networks. In this field, earlier work addressed the problem in determinist cases and in cases dealing with demand uncertainties. In this paper, the authors develop a method to deal with uncertainties related to the cost function. Indeed, such uncertainties often occur in energy networks (waste incinerator with a priori unknown waste amounts, cogeneration plant with uncertainty of the sold electricity price...). The corresponding optimization problems are large scale stochastic non-linear mixed integer problems. The developed solution method is a recourse based programming one. The main idea is to consider that amounts of energy to produce can be slightly adapted in real time, whereas the on/off statuses of units have to be decided very early in the management procedure. Results show that the proposed approach remains compatible with existing Unit Commitment programming methods and presents an obvious interest with reasonable computing loads. 展开更多
关键词 Unit Commitment dynamic programming stochastic programming UNCERTAINTY energy management systems RECOURSE Lagrangian relaxation.
在线阅读 下载PDF
基于互补约束和绝对值线性化松弛的日前无功计划优化
16
作者 黄华 徐泰山 +3 位作者 高宗和 柏琳 陆进军 涂孟夫 《电力系统自动化》 北大核心 2025年第3期156-169,共14页
为高效求解大规模非线性含多时段耦合绝对值约束和整数变量的日前无功计划优化问题,提出了一种基于互补约束和绝对值线性化松弛的两阶段优化算法。通过线性化方法松弛多时段耦合绝对值约束,并基于互补条件和离散变量等价转换,将原问题... 为高效求解大规模非线性含多时段耦合绝对值约束和整数变量的日前无功计划优化问题,提出了一种基于互补约束和绝对值线性化松弛的两阶段优化算法。通过线性化方法松弛多时段耦合绝对值约束,并基于互补条件和离散变量等价转换,将原问题转换为含互补约束的连续数学规划问题。将求解步骤分为两个阶段,并采用内点法依次求解。首先,不计互补约束,快速获得离散变量近似优化解;然后,求解含互补约束的完整模型以获得离散变量和连续变量的精确优化解。此外,为减少内点法迭代时综合海森矩阵的计算量,提出了一种快速稀疏存储计算方法。IEEE 118节点等标准测试系统和实际省级电网的仿真结果表明了所提算法的有效性、快速性及其在实际大规模电力系统的工程适用性。 展开更多
关键词 日前无功计划 动态无功优化 混合整数规划 绝对值线性化松弛 互补约束 内点法
在线阅读 下载PDF
协作速率分割多址接入辅助的多站通感一体化波束赋形设计
17
作者 李若光 王琰 +1 位作者 陈颖玚 韩光洁 《电子学报》 北大核心 2025年第5期1491-1499,共9页
本文提出了一种协作速率分割多址接入(Coordinated Rate-Splitting Multiple Access,CoRSMA)辅助的多站通信感知一体化(Integrated Sensing And Communication,ISAC)波束优化方案,以更为灵活地实现定制化的通信和感知业务.本文建立了各... 本文提出了一种协作速率分割多址接入(Coordinated Rate-Splitting Multiple Access,CoRSMA)辅助的多站通信感知一体化(Integrated Sensing And Communication,ISAC)波束优化方案,以更为灵活地实现定制化的通信和感知业务.本文建立了各基站(Base Station,BS)公有流和私有流的接收信号模型,以及感知回波信号模型,分析波束赋形向量与通信速率和感知信噪比(Signal-to-Noise Ratio,SNR)之间的关系.在保证特定区域感知性能的条件下,以最大化最差情况下用户设备(User Equipment,UE)的通信和速率为优化目标,对所有BS的波束赋形向量进行联合优化.为了有效求解所构建的优化问题,通过引入辅助变量,并结合连续凸逼近(Successive Convex Approximation,SCA)方法对原始优化问题的非凸目标和约束进行松弛转换,进一步利用半正定规划(Semi-Definite Programming,SDP)技术得到最优波束赋形.仿真结果显示,所提出的CoRSMA-ISAC系统在通信和感知性能上均优于基于空分多址接入(Spatial Divi-sion Multiple Access,SDMA)与非正交多址接入(Non-Orthogonal Multiple Access,NOMA)辅助的ISAC系统. 展开更多
关键词 通信感知一体化(ISAC) 速率分割多址接入(RSMA) 多站 波束赋形优化 非凸优化 连续凸逼近(SCA) 半正定规划(sdp)
在线阅读 下载PDF
基于拉格朗日松弛及子问题解耦动态规划的周机组组合快速求解方法 被引量:1
18
作者 刘与铮 丁涛 +6 位作者 肖杨 代江 田年杰 赵倩 唐翀 禤培正 程兰芬 《电力自动化设备》 北大核心 2025年第6期173-181,190,共10页
当前逐渐增大的电力系统规模和逐渐拓展的模拟周期使得快速求解机组组合问题面临巨大挑战。提出一种基于拉格朗日松弛和子问题解耦动态规划的周机组组合快速求解方法,以提高周机组组合计算效率。引入拉格朗日对偶乘子对原始问题中的耦... 当前逐渐增大的电力系统规模和逐渐拓展的模拟周期使得快速求解机组组合问题面临巨大挑战。提出一种基于拉格朗日松弛和子问题解耦动态规划的周机组组合快速求解方法,以提高周机组组合计算效率。引入拉格朗日对偶乘子对原始问题中的耦合约束进行松弛,并分解得到若干单机组子问题;构建单机组子问题的状态转移图及状态转移成本,利用动态规划算法计算单机组最优状态转移,以获得单机组子问题最优解;对问题进行迭代求解直至收敛,从而快速得到周机组组合结果。将所提方法应用于IEEE 118节点系统、IEEE 300节点系统和贵州电网,验证其优异的计算效率。 展开更多
关键词 拉格朗日松弛 动态规划 机组组合 次梯度优化算法 分解协调
在线阅读 下载PDF
线性乘积和规划问题的基于D.C.松弛的分支定界算法
19
作者 张博 王红雨 高岳林 《运筹学学报(中英文)》 北大核心 2025年第4期159-174,共16页
线性乘积和规划已出现在工程实践和管理科学等领域,是一类NP-难问题。针对该问题目标函数的特殊结构,将其重构为一个D.C.(difference of convex functions)规划问题。再利用凹函数的凸包络,构造出了一种D.C.松弛问题,并将其分解为两个... 线性乘积和规划已出现在工程实践和管理科学等领域,是一类NP-难问题。针对该问题目标函数的特殊结构,将其重构为一个D.C.(difference of convex functions)规划问题。再利用凹函数的凸包络,构造出了一种D.C.松弛问题,并将其分解为两个凸子问题。然后将该D.C.松弛与超矩形的标准二分法相结合,设计了新的分支定界算法,并分析了其理论收敛性和计算复杂度。最后,借助大量数值实验验证了该算法的有效性。 展开更多
关键词 全局优化 线性乘积和规划 分支定界 D.C.规划松弛技术
在线阅读 下载PDF
基于两阶段数学启发式方法优化AGV与作业调度问题
20
作者 黎林涛 张子凯 +1 位作者 胡一凡 张利平 《组合机床与自动化加工技术》 北大核心 2025年第10期183-188,共6页
随着作业车间智能化与信息化程度不断提升,自动导引车(automated guided vehicle,AGV)与作业任务同步执行,致使AGV分配、AGV搬运和机器加工顺序耦合度更强,求解面临挑战。为此,设计了离线与在线相结合的两阶段数学启发式算法解决AGV与... 随着作业车间智能化与信息化程度不断提升,自动导引车(automated guided vehicle,AGV)与作业任务同步执行,致使AGV分配、AGV搬运和机器加工顺序耦合度更强,求解面临挑战。为此,设计了离线与在线相结合的两阶段数学启发式算法解决AGV与作业集成调度问题。离线阶段通过双层编码策略生成多样化的调度样本库,并利用基因表达式编程(gene expression programming,GEP)挖掘调度知识;在线阶段应用调度知识筛选瓶颈工序,松弛部分瓶颈工序并通过混合整数规划模型迭代更新,实现快速优化。实验结果表明,所提方法在较短时间内稳定地优化大规模案例,且显著优于传统方法。 展开更多
关键词 AGV与作业调度 基因表达式编程 瓶颈工序松弛 数学启发式算法
在线阅读 下载PDF
上一页 1 2 19 下一页 到第
使用帮助 返回顶部