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Solution of scattering from rough surface with a 2D target above it by a hybrid method based on the reciprocity theorem and the forward-backward method 被引量:4
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作者 王运华 张彦敏 +1 位作者 贺明霞 郭立新 《Chinese Physics B》 SCIE EI CAS CSCD 2008年第10期3696-3703,共8页
This paper proposes a hybrid method based on the forward-backward method (FBM) and the reciprocity theorem (RT) for evaluating the scattering field from dielectric rough surface with a 2D target above it. Here, th... This paper proposes a hybrid method based on the forward-backward method (FBM) and the reciprocity theorem (RT) for evaluating the scattering field from dielectric rough surface with a 2D target above it. Here, the equivalent electric/magnetic current densities on the rough surface as well as the scattering field from it are numerically calculated by FBM, and the scattered field from the isolated target is obtained utilizing the method of moments (MOM). Meanwhile, the rescattered coupling interactions between the target and the surface are evaluated employing the combination of FBM and RT. Our hybrid method is first validated by available MOM results. Then, the functional dependences of bistatic and monostatic scattering from the target above rough surface upon the target altitude, incident and scattering angles are numerically simulated and discussed. This study presents a numerical description for the scattering mechanism associated with rescattered coupling interactions between a target and an underlying randomly rough surface. 展开更多
关键词 forward-backward method reciprocity theorem 2D target rough surface SCATTERING
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A Hybrid Backward Euler Control Volume Method to Solve the Concentration-Dependent Solid-State Diffusion Problem in Battery Modeling
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作者 Kudakwashe Chayambuka Grietus Mulder +1 位作者 Dmitri L. Danilov Peter H. L. Notten 《Journal of Applied Mathematics and Physics》 2020年第6期1066-1080,共15页
Several efficient analytical methods have been developed to solve the solid-state diffusion problem, for constant diffusion coefficient problems. However, these methods cannot be applied for concentration-dependent di... Several efficient analytical methods have been developed to solve the solid-state diffusion problem, for constant diffusion coefficient problems. However, these methods cannot be applied for concentration-dependent diffusion coefficient problems and numerical methods are used instead. Herein, grid-based numerical methods derived from the control volume discretization are presented to resolve the characteristic nonlinear system of partial differential equations. A novel hybrid backward Euler control volume (HBECV) method is presented which requires only one iteration to reach an implicit solution. The HBECV results are shown to be stable and accurate for a moderate number of grid points. The computational speed and accuracy of the HBECV, justify its use in battery simulations, in which the solid-state diffusion coefficient is a strong function of the concentration. 展开更多
关键词 Solid-State Diffusion Implicit methods backward Euler
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Iterative methods for a forward-backward heat equation in two-dimension
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作者 SUN Jie CHENG Xiao-liang 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 2010年第1期101-111,共11页
A finite difference method is introduced to solve the forward-backward heat equation in two space dimensions. In this procedure, the backward and forward difference scheme in two subdomains and a coarse-mesh second-or... A finite difference method is introduced to solve the forward-backward heat equation in two space dimensions. In this procedure, the backward and forward difference scheme in two subdomains and a coarse-mesh second-order central difference scheme at the middle interface are used. Maximum norm error estimate for the procedure is derived. Then an iterative method based on domain decomposition is presented for the numerical scheme and the convergence of the given method is established. Then numerical experiments are presented to support the theoretical analysis. 展开更多
关键词 Forward-backward heat equation coarse mesh iterative method.
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Forward-backward热方程差分逼近的直接算法
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作者 叶兴德 《浙江大学学报(理学版)》 CAS CSCD 2002年第2期125-128,共4页
通过利用区域分解技术和并行算法的思想 ,把原问题分解为几个完全独立的子区域上的问题 ,并直接并行求解 ,然后把这些解作适当的线性组合 ,得到原问题的解 .给出了 Forward-
关键词 直接算法 Forward-backward热方程 有限差分方法 差分逼近 差分格式 区域分解技术 并行算法
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An IPC-based Prolog design pattern for integrating backward chaining inference into applications or embedded systems 被引量:2
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作者 Li Guoqi Shao Yuanxun +1 位作者 Hong Sheng Liu Bin 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2014年第6期1571-1577,共7页
Prolog is one of the most important candidates to build expert systems and AI-related programs and has potential applications in embedded systems. However, Prolog is not suitable to develop many kinds of components, s... Prolog is one of the most important candidates to build expert systems and AI-related programs and has potential applications in embedded systems. However, Prolog is not suitable to develop many kinds of components, such as data acquisition and task scheduling, which are also crucial. To make the best use of the advantages and bypass the disadvantages, it is attractive to integrate Prolog with programs developed by other languages. In this paper, an IPC-based method is used to integrate backward chaining inference implemented by Prolog into applications or embedded systems. A Prolog design pattern is derived from the method for reuse, whose principle and definition are provided in detail. Additionally, the design pattern is applied to a target system, which is free software, to verify its feasibility. The detailed implementation of the application is given to clarify the design pattern. The design pattern can be further applied to wide range applications and embedded systems and the method described in this paper can also be adopted for other logic programming languages. 展开更多
关键词 backward chaining inference Design method Embedded systems Inference engines Inter-process communication Prolog
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求解双层凸优化问题的Forward-Backward分裂算法
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作者 李明川 叶明露 《西华师范大学学报(自然科学版)》 2020年第1期46-51,共6页
Forward-Backward分裂算法是求解极大单调算子和问题以及极小化具有可分结构的凸函数和问题的有效算法。本文利用该算法在Hilbert空间中构造出了求解双层优化问题的分裂算法。与已有文献相比,所提算法不仅在参数的选取上更加灵活,而且... Forward-Backward分裂算法是求解极大单调算子和问题以及极小化具有可分结构的凸函数和问题的有效算法。本文利用该算法在Hilbert空间中构造出了求解双层优化问题的分裂算法。与已有文献相比,所提算法不仅在参数的选取上更加灵活,而且本文还证明了该算法生成的点列能收敛到双层优化问题的解。 展开更多
关键词 极大单调算子 双层优化 非扩张映射 Forward-backward算法 弱收敛列
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Solutions to general forward-backward doubly stochastic differential equations 被引量:1
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作者 朱庆峰 石玉峰 宫献军 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2009年第4期517-526,共10页
A general type of forward-backward doubly stochastic differential equations (FBDSDEs) is studied. It extends many important equations that have been well studied, including stochastic Hamiltonian systems. Under some... A general type of forward-backward doubly stochastic differential equations (FBDSDEs) is studied. It extends many important equations that have been well studied, including stochastic Hamiltonian systems. Under some much weaker monotonicity assumptions, the existence and uniqueness of measurable solutions are established with a incthod of continuation. Furthermore, the continuity and differentiability of the solutions to FBDSDEs depending on parameters is discussed. 展开更多
关键词 forward-backward doubly stochastic differential equations method of con-tinuation H-monotone
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Analysis of the Invariance and Generalizability of Multiple Linear Regression Model Results Obtained from Maslach Burnout Scale through Jackknife Method
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作者 Tolga Zaman Kamil Alakus 《Open Journal of Statistics》 2015年第7期645-651,共7页
The purpose of this study was to examine the burnout levels of research assistants in Ondokuz Mayis University and to examine the results of multiple linear regression model based on the results obtained from Maslach ... The purpose of this study was to examine the burnout levels of research assistants in Ondokuz Mayis University and to examine the results of multiple linear regression model based on the results obtained from Maslach Burnout Scale with Jackknife Method in terms of validity and generalizability. To do this, a questionnaire was given to 11 research assistants working at Ondokuz Mayis University and the burnout scores of this questionnaire were taken as the dependent variable of the multiple linear regression model. The variable of burnout was explained with the variables of age, weekly hours of classes taught, monthly average credit card debt, numbers of published articles and reports, gender, marital status, number of children and the departments of the research assistants. Dummy variables were assigned to the variables of gender, marital status, number of children and the departments of the research assistants and thus, they were made quantitative. The significance of the model as a result of multiple linear regressions was examined through backward elimination method. After this, for the five explanatory variables which influenced the variable of burnout, standardized model coefficients and coefficients of determination, and 95% confidence intervals of these values were estimated through Jackknife Method and the generalizability of the parameter estimation results of these variables on population was researched. 展开更多
关键词 JACKKNIFE method INVARIANCE GENERALIZABILITY Maslach BURNOUT SCALE Multiple Linear Regression backward Elimination method
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A NEW PSEUDOSPECTRAL APPROXIMATION FOR THE FOWARD-BACKWARD HEAT EQUATION
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作者 叶兴德 江金生 《Acta Mathematica Scientia》 SCIE CSCD 1996年第2期121-128,共8页
In this paper,we propose a new numerical method which is a least squares approximaton based on pseudospectral method for the Forward-Backward heat equation. The existence and uniqueness of the solution of the least sq... In this paper,we propose a new numerical method which is a least squares approximaton based on pseudospectral method for the Forward-Backward heat equation. The existence and uniqueness of the solution of the least squares approximation are proved. Error estimates for this approximation are given,which show that tile order of convergence depends only on the regularity of tile solution and the right hand of the Forward-Backward heat equation. 展开更多
关键词 FORWARD-backward heat equation pseudospectral method the least
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An Implicit-Explicit Computational Method Based on Time Semi-Discretization for Pricing Financial Derivatives with Jumps
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作者 Yang Wang 《Open Journal of Statistics》 2018年第2期334-344,共11页
This paper considers pricing European options under the well-known of SVJ model of Bates and related computational methods. According to the no-arbitrage principle, we first derive a partial differential equation that... This paper considers pricing European options under the well-known of SVJ model of Bates and related computational methods. According to the no-arbitrage principle, we first derive a partial differential equation that the value of any European contingent claim should satisfy, where the asset price obeys the SVJ model. This equation is numerically solved by using the implicit- explicit backward difference method and time semi-discretization. In order to explain the validity of our method, the stability of time semi-discretization scheme is also proved. Finally, we use a simulation example to illustrate the efficiency of the method. 展开更多
关键词 SVJ Model of Bates Time SEMI-DISCRETIZATION Stability NO-ARBITRAGE Principle Implicit-Explicit backward Difference method
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STABILIZED NUMERICAL APPROXIMATIONS OF THE BACKWARD PROBLEM OF A PARABOLIC EQUATION
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作者 Han Houde(韩厚德) +1 位作者 Hu Gang(胡刚) 《Numerical Mathematics A Journal of Chinese Universities(English Series)》 SCIE 2001年第2期182-192,共11页
In this paper, the backward problem of a parabolic equation is considered. Three new stability estimates are given. Based on the new stability estimates, a regularization method is proposed for which error estimates a... In this paper, the backward problem of a parabolic equation is considered. Three new stability estimates are given. Based on the new stability estimates, a regularization method is proposed for which error estimates are available. The regularization method can be used for the numerical approximations of the original problem which will be shown by the numerical examples. 展开更多
关键词 backward PARABOLIC equation stability estimates REGULARIZATION method.
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Effect of Richardson number on entropy generation over backward facing step
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作者 陈胜 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2012年第11期1431-1440,共10页
The flow over a backward facing step (BFS) has been taken as a useful proto- type to investigate intrinsic mechanisms of separated flow with heat transfer. However, to date, the open literature on the effect of Rich... The flow over a backward facing step (BFS) has been taken as a useful proto- type to investigate intrinsic mechanisms of separated flow with heat transfer. However, to date, the open literature on the effect of Richardson number on entropy generation over the BFS is absent yet, although the flow pattern and heat transfer characteristic both will receive significant influence caused by the variation of Richardson number in many prac- tical applications, such as in microelectromechanical systems and aerocrafts. The effect of Richardson number on entropy generation in the BFS flow is reported in this paper for the first time. The entropy generation analysis is conducted through numerically solving the entropy generation equation. The velocity and temperature, which are the inputs of the entropy generation equation, are evaluated by the lattice Boltzmann method. It is found that the distributions of local entropy generation number and Bejan number are significantly influenced by the variation of Richardson number. The total entropy gen- eration number is a monotonic decreasing function of Richardson number, whereas the average Bejan number is a monotonic increasing function of Richardson number. 展开更多
关键词 entropy generation backward facing step Richardson number latticeBoltzmann method
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北京城区冬季细颗粒物(PM_(2.5))中酚类衍生化合物污染特征及来源解析
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作者 尹中一 骆亮 +2 位作者 谷欣 赵文吉 李杏茹 《环境污染与防治》 北大核心 2025年第4期77-86,I0004,I0005,共12页
为了解北京市冬季大气细颗粒物(PM_(2.5))中酚类衍生化合物的污染特征,于2016年11月10日至2017年1月8日在北京市城区对PM_(2.5)样品进行昼夜采集,采用溶剂提取-衍生化-气相色谱/质谱(GC/MS)联用方法对样品进行处理和定性定量分析,共获取... 为了解北京市冬季大气细颗粒物(PM_(2.5))中酚类衍生化合物的污染特征,于2016年11月10日至2017年1月8日在北京市城区对PM_(2.5)样品进行昼夜采集,采用溶剂提取-衍生化-气相色谱/质谱(GC/MS)联用方法对样品进行处理和定性定量分析,共获取了10种酚类衍生化合物和3种糖类化合物的浓度。结果表明,酚类衍生化合物的平均总质量浓度为130.1 ng/m^(3),其中对羟基苯甲酸的平均质量浓度最高,香草醛的平均质量浓度最低。10种化合物夜间浓度明显高于日间,污染天浓度也均高于清洁天,主要是气象要素的变化对污染物存在较大的影响。芳香酸类和芳香醛类化合物与左旋葡聚糖呈显著的正相关关系,相关性系数(R^(2))分别为0.61和0.72,表明生物质燃烧是酚类衍生化合物的重要一次来源。根据比值分析法判断北京市生物质燃烧类型主要为硬木和草本植物。采样期间北京市PM_(2.5)主要来自蒙古的长距离传输和来自北京市西南部的太原和石家庄等地的短距离传输;潜在贡献源区分析表明,内蒙古、甘肃和宁夏北部以及北京市周边如保定、石家庄对北京市酚类衍生化合物污染的潜在贡献也不容忽视。 展开更多
关键词 生物质燃烧 酚类衍生化合物 昼夜变化 比值分析法 后向轨迹分析
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基于快速逐线计算模型的高超声速羽流红外辐射计算方法
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作者 徐建宇 周莉 +2 位作者 王占学 是介 史毫 《航空学报》 北大核心 2025年第8期113-127,共15页
为对临近空间高超声速飞行器羽流的红外辐射特性进行研究,构建了适用于临近空间羽流流场的红外辐射特性计算方法。首先采用非线性耦合本构关系模型对羽流流场进行数值仿真,检验了流场计算模型的准确性。其次采用全因子试验设计,通过逐... 为对临近空间高超声速飞行器羽流的红外辐射特性进行研究,构建了适用于临近空间羽流流场的红外辐射特性计算方法。首先采用非线性耦合本构关系模型对羽流流场进行数值仿真,检验了流场计算模型的准确性。其次采用全因子试验设计,通过逐线计算物理模型获取了46200组流场特性参数与吸收系数的数据,训练获得基于BP神经网络的快速逐线计算模型,模型最大平均绝对误差和决定系数分别为0.00365和0.9994,相比逐线计算物理模型计算速度提升了4个数量级。最后结合逆蒙特卡洛方法作为红外辐射传输方法,建立了高超声速飞行器羽流的红外辐射计算方法。采用建立的流场和红外辐射计算方法针对类X-51A飞行器巡航状态下羽流红外辐射特性进行了研究。研究表明,临近空间下高超声速羽流呈现出外热流包裹冷内流的现象,羽流边缘滞止区红外辐射更强,红外成像中呈现“剪刀”状,剪切层的变化影响羽流红外成像的特征。 展开更多
关键词 高超声速羽流 非线性耦合本构关系 逐线计算法 深度学习 逆向蒙特卡洛方法 红外辐射
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2015-2022年桂林PM_(2.5)外来输送特征及潜在源分析
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作者 叶子葳 王琛泉 +5 位作者 文建辉 卢德林 林清钰 陈春强 霍强 龙腾发 《广西科学》 北大核心 2025年第1期192-203,共12页
为揭示桂林PM_(2.5)时空分布特征与潜在来源,选取桂林2015-2022年PM_(2.5)质量浓度和气象要素监测数据,利用HYSPLIT模型(Hybrid Single Particle Lagrangian Integrated Trajectory Model)模拟桂林气团后向轨迹,结合聚类轨迹分析法和浓... 为揭示桂林PM_(2.5)时空分布特征与潜在来源,选取桂林2015-2022年PM_(2.5)质量浓度和气象要素监测数据,利用HYSPLIT模型(Hybrid Single Particle Lagrangian Integrated Trajectory Model)模拟桂林气团后向轨迹,结合聚类轨迹分析法和浓度权重轨迹分析法(CWT),解析不同季节PM_(2.5)潜在源区及其贡献强度。结果表明,桂林PM_(2.5)污染呈现逐年下降趋势;PM_(2.5)输送途径的季节特征明显,是导致桂林PM_(2.5)月际变化“冬高夏低、春秋居中”的一大因素。华中地区和广东、广西地区的污染输送是桂林城区PM_(2.5)的主要外来贡献源,桂林独特的地理位置和地形因素对该地区污染物的输送和扩散起着重要作用。本研究揭示了跨区域污染传输的机制以及局地气象与地形的耦合效应,可为区域联防联控和精准治污提供科学依据。 展开更多
关键词 PM_(2.5) 时空分布 后向轨迹聚类 浓度权重轨迹分析法
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CENTRAL LIMIT THEOREM FOR TEMPORAL AVERAGE OF BACKWARD EULER-MARUYAMA METHOD
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作者 Diancong Jin 《Journal of Computational Mathematics》 2025年第3期588-614,共27页
This work focuses on the temporal average of the backward Euler-Maruyama(BEM)method,which is used to approximate the ergodic limit of stochastic ordinary differential equations(SODEs).We give the central limit theorem... This work focuses on the temporal average of the backward Euler-Maruyama(BEM)method,which is used to approximate the ergodic limit of stochastic ordinary differential equations(SODEs).We give the central limit theorem(CLT)of the temporal average of the BEM method,which characterizes its asymptotics in distribution.When the deviation order is smaller than the optimal strong order,we directly derive the CLT of the temporal average through that of original equations and the uniform strong order of the BEM method.For the case that the deviation order equals to the optimal strong order,the CLT is established via the Poisson equation associated with the generator of original equations.Numerical experiments are performed to illustrate the theoretical results.The main contribution of this work is to generalize the existing CLT of the temporal average of numerical methods to that for SODEs with super-linearly growing drift coefficients. 展开更多
关键词 Central limit theorem Temporal average ERGODICITY backward Euler-Maruyama method
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动态事件触发二阶多智能体系统的预定时间比例一致性
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作者 李诺 马小陆 +2 位作者 洪鹏 佘胜安 谭毅波 《安徽工业大学学报(自然科学版)》 2025年第3期287-297,305,共12页
针对一般线性二阶多智能体系统的协同控制问题,提出一种基于动态事件触发的分布式预定时间控制策略,重点解决系统在用户自定义时间内实现比例一致性的关键技术难题。通过反推法设计控制协议,在位置和速度状态中引入比例参数,使各智能体... 针对一般线性二阶多智能体系统的协同控制问题,提出一种基于动态事件触发的分布式预定时间控制策略,重点解决系统在用户自定义时间内实现比例一致性的关键技术难题。通过反推法设计控制协议,在位置和速度状态中引入比例参数,使各智能体在预定时间内快速实现比例一致,并可通过参数配置灵活实现普通一致性、二分一致性或分群一致性等多样化协同模式;同时构建基于内部动态变量的时变触发机制,实现事件触发条件的动态调整,降低系统能量耗散及控制器更新频次。基于代数图论、线性矩阵不等式以及Lyapunov稳定性理论,严格证明系统在预定时间内的收敛性及触发机制无Zeno行为的特性。数值仿真结果表明:相较于固定时间控制策略,本文策略的收敛时间更易获取和调节,收敛时间更接近预估值,且收敛速率及整体系统性能指标更优;与静态事件触发控制策略相比,在保证相同通信性能的前提下可有效降低系统能耗。特别地,本文研究利用生成式模型预测多智能体动态演化趋势、结合强化学习自主调节比例参数配置,增强了系统对未知扰动的适应能力。因此,本文研究不仅为多智能体系统协同控制提供了理论严谨的解决方案,同时为生成式人工智能技术的集成提供了潜在接口。 展开更多
关键词 比例一致性 预定时间 二阶多智能体系统 动态事件触发 反推法 线性系统 分布式控制 生成式人工智能
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发动机摩擦扭矩预测方法研究
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作者 钱人杰 卢嘉晖 《内燃机与配件》 2025年第1期6-8,共3页
提高发动机摩擦扭矩测量的准确性对发动机机械效率、燃油消耗率的提升有着极其重要的作用。当前稳态倒拖等方法对于台架试验边界条件的控制要求很高,试验过程往往会出现很多误差。本文基于稳态倒拖得到的摩擦扭矩与转速和机油温度的相关... 提高发动机摩擦扭矩测量的准确性对发动机机械效率、燃油消耗率的提升有着极其重要的作用。当前稳态倒拖等方法对于台架试验边界条件的控制要求很高,试验过程往往会出现很多误差。本文基于稳态倒拖得到的摩擦扭矩与转速和机油温度的相关性,提出一种新的摩擦扭矩预测方法。经过试验验证,该方法获得的全转速下的摩擦扭矩为测量值的1.0009倍,线性相关系数在0.99以上,具备一定的可靠性。利用发动机的瞬时油耗和负荷特性曲线可预测转速与摩擦扭矩的关联性,但该方法忽略了随着负荷带来的机油温度变化对摩擦扭矩的影响。 展开更多
关键词 发动机 倒拖法 摩擦扭矩 模型
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矩形域热传导方程逆时问题的一种正则化方法
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作者 王宇 孙伟 《哈尔滨理工大学学报》 北大核心 2025年第4期149-158,共10页
针对二维矩形域中带有只与空间位置有关源项的非齐次热传导方程的逆时问题,提出了一种正则化方法,此方法是一种已有正则化方法的扩展。首先,利用源项和终值数据的Fourier展开构造正则化问题,得到正则化解;其次,在不同的先验假设下,给出... 针对二维矩形域中带有只与空间位置有关源项的非齐次热传导方程的逆时问题,提出了一种正则化方法,此方法是一种已有正则化方法的扩展。首先,利用源项和终值数据的Fourier展开构造正则化问题,得到正则化解;其次,在不同的先验假设下,给出正则化参数先验选取策略和后验选取策略,也证明了方法的收敛性;最后,通过数值算例验证了该方法的有效性及可行性。 展开更多
关键词 不适定问题 热传导方程 逆时问题 正则化方法 误差估计
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某矿机械化进路式后退分步放顶采矿法的研究与应用
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作者 陈兴 《现代矿业》 2025年第1期24-27,共4页
烂泥沟金矿采用上向水平分层进路充填采矿方法,在回采过程中,因围岩破碎及超挖,造成最后一个分层高度不能按照原设计采矿方法回采。在确保安全前提下,为了降低采矿成本,增加采矿效率,降低损失及贫化指标,结合盘区采矿实际情况,将原来4... 烂泥沟金矿采用上向水平分层进路充填采矿方法,在回采过程中,因围岩破碎及超挖,造成最后一个分层高度不能按照原设计采矿方法回采。在确保安全前提下,为了降低采矿成本,增加采矿效率,降低损失及贫化指标,结合盘区采矿实际情况,将原来4层回采改为3层回采,最后一层分为2步回采。第一步采用前进式回采,第二步采用后退式分步放顶回采,凿岩、锚网、喷浆等全工序采用机械化施工。优化后采切工程减少70m,单个作业循环减少30%喷浆料,损失率降低0.2个百分点,贫化率降低了0.9个百分点,该采矿方法可为类似矿山提供参考。 展开更多
关键词 后退分步放顶采矿法 回采顺序 采矿方法优化
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