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A Fixed-Point Fast Sweeping WENO Method with Inverse Lax-Wendroff Boundary Treatment for Steady State of Hyperbolic Conservation Laws
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作者 Liang Li Jun Zhu +1 位作者 Chi-Wang Shu Yong-Tao Zhang 《Communications on Applied Mathematics and Computation》 2023年第1期403-427,共25页
Fixed-point fast sweeping WENO methods are a class of efficient high-order numerical methods to solve steady-state solutions of hyperbolic partial differential equations(PDEs).The Gauss-Seidel iterations and alternati... Fixed-point fast sweeping WENO methods are a class of efficient high-order numerical methods to solve steady-state solutions of hyperbolic partial differential equations(PDEs).The Gauss-Seidel iterations and alternating sweeping strategy are used to cover characteristics of hyperbolic PDEs in each sweeping order to achieve fast convergence rate to steady-state solutions.A nice property of fixed-point fast sweeping WENO methods which distinguishes them from other fast sweeping methods is that they are explicit and do not require inverse operation of nonlinear local systems.Hence,they are easy to be applied to a general hyperbolic system.To deal with the difficulties associated with numerical boundary treatment when high-order finite difference methods on a Cartesian mesh are used to solve hyperbolic PDEs on complex domains,inverse Lax-Wendroff(ILW)procedures were developed as a very effective approach in the literature.In this paper,we combine a fifthorder fixed-point fast sweeping WENO method with an ILW procedure to solve steadystate solution of hyperbolic conservation laws on complex computing regions.Numerical experiments are performed to test the method in solving various problems including the cases with the physical boundary not aligned with the grids.Numerical results show highorder accuracy and good performance of the method.Furthermore,the method is compared with the popular third-order total variation diminishing Runge-Kutta(TVD-RK3)time-marching method for steady-state computations.Numerical examples show that for most of examples,the fixed-point fast sweeping method saves more than half CPU time costs than TVD-RK3 to converge to steady-state solutions. 展开更多
关键词 Fixed-point fast sweeping methods Multi-resolution WENO schemes Steady state ILW procedure Convergence
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An adaptive finite-difference method for seismic traveltime modeling based on 3D eikonal equation
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作者 Bao-Ping Qiao Qing-Qing Li +2 位作者 Wei-Guang He Dan Zhao Qu-Bo Wu 《Petroleum Science》 SCIE EI CAS CSCD 2024年第1期195-205,共11页
3D eikonal equation is a partial differential equation for the calculation of first-arrival traveltimes and has been widely applied in many scopes such as ray tracing,source localization,reflection migration,seismic m... 3D eikonal equation is a partial differential equation for the calculation of first-arrival traveltimes and has been widely applied in many scopes such as ray tracing,source localization,reflection migration,seismic monitoring and tomographic imaging.In recent years,many advanced methods have been developed to solve the 3D eikonal equation in heterogeneous media.However,there are still challenges for the stable and accurate calculation of first-arrival traveltimes in 3D strongly inhomogeneous media.In this paper,we propose an adaptive finite-difference(AFD)method to numerically solve the 3D eikonal equation.The novel method makes full use of the advantages of different local operators characterizing different seismic wave types to calculate factors and traveltimes,and then the most accurate factor and traveltime are adaptively selected for the convergent updating based on the Fermat principle.Combined with global fast sweeping describing seismic waves propagating along eight directions in 3D media,our novel method can achieve the robust calculation of first-arrival traveltimes with high precision at grid points either near source point or far away from source point even in a velocity model with large and sharp contrasts.Several numerical examples show the good performance of the AFD method,which will be beneficial to many scientific applications. 展开更多
关键词 3D eikonal equation Accurate traveltimes Global fast sweeping 3D inhomogeneous media Adaptive finite-difference method
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Sparse-Grid Implementation of Fixed-Point Fast Sweeping WENO Schemes for Eikonal Equations
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作者 Zachary M.Miksis Yong-Tao Zhang 《Communications on Applied Mathematics and Computation》 EI 2024年第1期3-29,共27页
Fixed-point fast sweeping methods are a class of explicit iterative methods developed in the literature to efficiently solve steady-state solutions of hyperbolic partial differential equations(PDEs).As other types of ... Fixed-point fast sweeping methods are a class of explicit iterative methods developed in the literature to efficiently solve steady-state solutions of hyperbolic partial differential equations(PDEs).As other types of fast sweeping schemes,fixed-point fast sweeping methods use the Gauss-Seidel iterations and alternating sweeping strategy to cover characteristics of hyperbolic PDEs in a certain direction simultaneously in each sweeping order.The resulting iterative schemes have a fast convergence rate to steady-state solutions.Moreover,an advantage of fixed-point fast sweeping methods over other types of fast sweeping methods is that they are explicit and do not involve the inverse operation of any nonlinear local system.Hence,they are robust and flexible,and have been combined with high-order accurate weighted essentially non-oscillatory(WENO)schemes to solve various hyperbolic PDEs in the literature.For multidimensional nonlinear problems,high-order fixed-point fast sweeping WENO methods still require quite a large amount of computational costs.In this technical note,we apply sparse-grid techniques,an effective approximation tool for multidimensional problems,to fixed-point fast sweeping WENO methods for reducing their computational costs.Here,we focus on fixed-point fast sweeping WENO schemes with third-order accuracy(Zhang et al.2006[41]),for solving Eikonal equations,an important class of static Hamilton-Jacobi(H-J)equations.Numerical experiments on solving multidimensional Eikonal equations and a more general static H-J equation are performed to show that the sparse-grid computations of the fixed-point fast sweeping WENO schemes achieve large savings of CPU times on refined meshes,and at the same time maintain comparable accuracy and resolution with those on corresponding regular single grids. 展开更多
关键词 Fixed-point fast sweeping methods Weighted essentially non-oscillatory(WENO)schemes Sparse grids Static Hamilton-Jacobi(H-J)equations Eikonal equations
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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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Fatigue crack growth rate test using a frequency sweep method 被引量:2
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作者 Xun ZHOU Xiao-li YU 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2008年第3期346-350,共5页
Fatigue crack propagation characteristics of a diesel engine crankshaft are studied by measuring the fatigue crack growth rate using a frequency sweep method on a resonant fatigue test rig. Based on the phenomenon tha... Fatigue crack propagation characteristics of a diesel engine crankshaft are studied by measuring the fatigue crack growth rate using a frequency sweep method on a resonant fatigue test rig. Based on the phenomenon that the system frequency will change when the crack becomes large, this method can be directly applied to a complex component or structure. Finite element analyses (FEAs) are performed to calibrate the relation between the frequency change and the crack size, and to obtain the natural frequency of the test rig and the stress intensity factor (SIF) of growing cracks. The crack growth rate i.e. da/dN-AK of each crack size is obtained by combining the testing-time monitored data and FEA results. The results show that the crack growth rate of engine crankshaft, which is a component with complex geometry and special surface treatment, is quite different from that of a pure material. There is an apparent turning point in the Paris's crack partition. The cause of the fatigue crack growth is also discussed. 展开更多
关键词 Crack growth rate Residual stress Frequency sweep method Engine crankshaft RELIABILITY
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A Modified Back/Forward Sweep Method Based on the Electricity Consumption Data
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作者 Yanlu Huang Yan Li +2 位作者 Feng Chen Xu Zheng Jing Tang 《Energy and Power Engineering》 2017年第4期176-182,共7页
With the development of distribution automation system, the centralized meter reading system has been adopted more and more extensively, which provides real-time electricity consumption data of end-users, and conseque... With the development of distribution automation system, the centralized meter reading system has been adopted more and more extensively, which provides real-time electricity consumption data of end-users, and consequently lays foundation for operating condition on-line analysis of distribution network. In this paper, a modified back/forward sweep method, which directly uses real-time electricity consumption data acquired from the centralized meter reading system, is proposedto realize voltage analysis based on 24-hour electricity consumption data of a typical transformer district. Furthermore, the calculated line losses are verified through data collected from the energy metering of the distribution transformer, illustrating that the proposed method can be applied in analyzing voltage level and discovering unknown energy losses, which will lay foundation for on-line analysis, calculation and monitoring of power distribution network. 展开更多
关键词 LOW-VOLTAGE Distribution Network Back/Forward sweep method ELECTRICITY CONSUMPTION DATA On-Line Analysis and Calculation
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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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求解二阶锥绝对值方程组的惯性two-sweep迭代法
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作者 洪晓曼 唐嘉 《武夷学院学报》 2023年第9期1-6,共6页
提出一种求解二阶锥绝对值方程组(SOCAVE)的惯性two-sweep迭代法。通过引入一个惯性项和一个恒等式,在系统矩阵和迭代矩阵满足一定条件的情况下,分析该算法的收敛性,数值结果表明所提出的方法是可行且有效的。
关键词 two-sweep迭代法 二阶锥 绝对值方程 惯性项
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基于因素空间理论的扫类连环多分类算法
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作者 曾繁慧 王莹 +1 位作者 汪培庄 孙慧 《辽宁工程技术大学学报(自然科学版)》 CAS 北大核心 2024年第1期111-118,共8页
为解决多分类问题,基于因素空间理论中因素显隐的思想,在扫类连环分类算法基础上,定义类别的合并,提出因素显隐的合并扫类连环分类方法,给出算法步骤,并用数值算例进行分析;定义类别的两两组合,提出因素显隐的两两扫类连环分类方法,给... 为解决多分类问题,基于因素空间理论中因素显隐的思想,在扫类连环分类算法基础上,定义类别的合并,提出因素显隐的合并扫类连环分类方法,给出算法步骤,并用数值算例进行分析;定义类别的两两组合,提出因素显隐的两两扫类连环分类方法,给出算法步骤,并用数值算例进行分析。提出采用因素显隐的差额绝对值方法解决两个算法执行过程中出现的决策类别分不开的问题;对UCI数据集中3个实例与支持向量机作了算法对比分析,研究结果表明:提出的合并扫类连环分类方法、两两扫类连环分类方法实现了因素显隐,分类算法的精确度优于支持向量机。多分类学习的因素显隐研究结论拓展了因素空间的理论及应用研究。 展开更多
关键词 因素空间 因素显隐 扫类连环分类算法 合并扫类连环分类算法 两两扫类连环分类算法 差额绝对值法
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基于稀疏恢复的调频引信抗扫频干扰方法
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作者 杨瑾 郝新红 +1 位作者 乔彩霞 陈齐乐 《兵工学报》 EI CAS CSCD 北大核心 2024年第6期2044-2053,共10页
针对连续波调频引信在扫频式干扰作用下的早炸或者瞎火问题,提出基于时域干扰剔除及信号稀疏重构的抗干扰方法。通过时域异常值检测定位干扰位置和持续时间,并剔除异常数据抑制干扰对引信的影响;进一步地针对干扰剔除引起的信号时域稀疏... 针对连续波调频引信在扫频式干扰作用下的早炸或者瞎火问题,提出基于时域干扰剔除及信号稀疏重构的抗干扰方法。通过时域异常值检测定位干扰位置和持续时间,并剔除异常数据抑制干扰对引信的影响;进一步地针对干扰剔除引起的信号时域稀疏,建立基于稀疏正则项的差频信号重构优化方程,并提出基于交替方向乘子法的迭代重构算法;通过仿真和实测数据验证方法的性能。研究结果表明:该方法能够在信噪比-15 dB,置零样本率不高于70%的情况下,抑制扫频干扰的影响,准确实现目标距离-速度信息的获取,提高了调频引信抗扫频干扰能力。 展开更多
关键词 稀疏恢复 扫频干扰 调频引信 交替方向乘子法
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基于扫频电阻法的变压器绕组材质辨识方法及实验验证
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作者 陈俊晔 沈子伦 +3 位作者 李新宇 王亚伟 尹忠东 郑志曜 《科学技术与工程》 北大核心 2024年第2期584-594,共11页
变压器生产中“以铝代铜”现象危害电力系统运行安全,为了简单有效地辨别变压器绕组材质,提出了一种基于扫频电阻法的辨识方法和实验方案,并根据该方案搭建了一套变压器绕组材质检测系统。首先对基于扫频电阻法的辨识方法进行了相关理... 变压器生产中“以铝代铜”现象危害电力系统运行安全,为了简单有效地辨别变压器绕组材质,提出了一种基于扫频电阻法的辨识方法和实验方案,并根据该方案搭建了一套变压器绕组材质检测系统。首先对基于扫频电阻法的辨识方法进行了相关理论推导和证明,之后对基于该方法的检测系统性能进行了测试,最后对不同类型变压器进行了实验验证。实验结果表明该方法能够快速高效地辨别变压器绕组材质,具有较高的工程实用价值。 展开更多
关键词 铜铝变压器 扫频电阻法 趋肤效应 谐波电阻
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物流配送(集货)中运输车辆优化的Greedy Sweep算法 被引量:5
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作者 丁源 李引珍 《兰州交通大学学报》 CAS 2004年第6期140-142,共3页
运输在物流中具有十分重要的地位 ,同时运输车辆优化的问题是物流决策中的关键所在 .目前 ,运输工具购买及维护的昂贵使得物流管理的决策者在制定行车路线时 ,总是希望充分利用运输工具的运力 .就物流管理系统中运输工具利用和行车路线... 运输在物流中具有十分重要的地位 ,同时运输车辆优化的问题是物流决策中的关键所在 .目前 ,运输工具购买及维护的昂贵使得物流管理的决策者在制定行车路线时 ,总是希望充分利用运输工具的运力 .就物流管理系统中运输工具利用和行车路线优化制定问题 ,提出利用贪婪思想的扫描法 (TheSweepMethod)得到此问题的满意解 ,此算法简洁实用 。 展开更多
关键词 运输 车辆优化 物流管理 运输路线 贪婪 扫描法
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基于变分信号分解的脉冲多普勒雷达抗扫频式干扰方法
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作者 陈齐乐 钱鹏飞 +2 位作者 孔志杰 乔彩霞 张睿恒 《兵工学报》 EI CAS CSCD 北大核心 2024年第6期2076-2084,共9页
针对脉冲多普勒(Pulse Doppler,PD)雷达遭受扫频式干扰时,接收机被干扰信号饱和导致的雷达虚警或漏警问题,分析扫频式干扰作用下PD雷达中频信号特征,提出基于变分信号分解的PD雷达抗扫频式干扰方法。利用目标回波时域稀疏性及干扰信号... 针对脉冲多普勒(Pulse Doppler,PD)雷达遭受扫频式干扰时,接收机被干扰信号饱和导致的雷达虚警或漏警问题,分析扫频式干扰作用下PD雷达中频信号特征,提出基于变分信号分解的PD雷达抗扫频式干扰方法。利用目标回波时域稀疏性及干扰信号的频域窄带特性,通过极大极小惩罚项和2阶变分惩罚项分别约束中频信号中的目标回波脉冲串分量和干扰分量,设计了基于交替方向乘子法的迭代算法求解优化问题各分量。保留目标回波脉冲串分量,滤除扫频中频分量,从而抑制干扰对雷达的影响,并通过仿真和实测数据验证方法的有效性。研究结果表明:所提抗干扰方法在信干比-20 dB扫频式干扰作用下能够有效抑制扫频式干扰对PD雷达的影响,显著提高PD雷达的抗干扰性能。 展开更多
关键词 脉冲多普勒雷达 扫频式干扰 抗干扰方法 变分信号分解 交替方向乘子法
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无反馈通道自激扫掠喷嘴工作特性
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作者 王士奇 温泉 贾志刚 《推进技术》 EI CAS CSCD 北大核心 2024年第8期156-165,共10页
无反馈通道自激扫掠喷嘴仅在压力驱动下,通过两股射流在耦合腔内部的相互作用,就能在出口实现液柱喷射方向的自激发高频变化。为了探索此新型喷嘴在航空发动机内燃油喷射的应用潜力,本研究综合采用高速阴影成像法和二维数值模拟方法,研... 无反馈通道自激扫掠喷嘴仅在压力驱动下,通过两股射流在耦合腔内部的相互作用,就能在出口实现液柱喷射方向的自激发高频变化。为了探索此新型喷嘴在航空发动机内燃油喷射的应用潜力,本研究综合采用高速阴影成像法和二维数值模拟方法,研究了不同工作介质、不同缩比尺寸下,无反馈通道自激扫掠喷嘴的特征流速、工作频率、扫掠张角等参数随工作压降的响应变化情况。结果表明,无反馈通道自激扫掠喷嘴在较宽的工作压力范围(0.1~6 MPa)和特征尺寸范围(0.2~7 mm)内均能够实现稳定的自激发扫掠振荡喷射,产生30°以上的扫掠张角和5 kHz以上的振荡频率。无反馈通道自激扫掠喷嘴的扫掠张角基本不随压力和等比缩放特征尺寸而变化,但是其工作频率与其喉道处的特征流速成正比,与喉道宽度成反比,且其频率响应存在双模态现象。 展开更多
关键词 自激扫掠喷嘴 无反馈通道 流体振荡器 非定常数值模拟 高速阴影成像法
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广域电磁法压裂监测技术在致密砂岩气藏中的应用——以川中金秋气田为例
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作者 颜晓华 黄佳 李芳书 《非常规油气》 2024年第4期121-134,共14页
广域电磁法压裂监测技术通过监测压裂液注入地层后产生的电性变化引起的电磁响应,获取电磁时间差分异常,反映压裂液波及范围,进而分析缝网特征。该文介绍了广域电磁法压裂监测的基本原理及监测方式;为了搞清压裂改造效果,以川中金秋气... 广域电磁法压裂监测技术通过监测压裂液注入地层后产生的电性变化引起的电磁响应,获取电磁时间差分异常,反映压裂液波及范围,进而分析缝网特征。该文介绍了广域电磁法压裂监测的基本原理及监测方式;为了搞清压裂改造效果,以川中金秋气田为例,针对裂缝形态及扩展规律难以精准描述的问题,开展了广域电磁压裂监测。监测结果表明:1)金秋气田两侧压裂裂缝缝长合计超过300 m,波及面积大,整体改造效果较好,但各簇之间存在较强的非均质性;2)致密砂岩压裂时,产生数条主缝,之后一直沿着主缝方向不断扩张与延伸,最终压裂裂缝都呈现数个尖峰状突进的形态,且孔隙度和脆性指数越大,裂缝扩展更容易,波及长度更大;3)裂缝特征与簇孔、段长、簇间距、用液强度及加砂强度等施工参数有关,金秋气田合理的簇间距为9~10 m,合理的段长为80~100 m,合理的用液强度为16.5 m^(3)/m,合理的加砂强度为5.0~6.0 t/m。以上研究结果可指导后期压裂施工工艺进行优化调整。 展开更多
关键词 广域电磁法 压裂监测 波及范围 实时指导 工艺优化
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不同测试方法下的轮胎性能评价函数值研究
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作者 何菁 张凯凯 +3 位作者 王龙庆 李慧敏 王兆龙 刘诗毅 《橡胶科技》 CAS 2024年第6期352-356,共5页
以235/55R19轿车子午线轮胎为例,采用稳态力和力矩试验法与动态侧偏扫掠法进行对比试验,并计算轮胎的性能评价函数值。结果表明:稳态力和力矩试验法得到的侧偏角为1°,4°时的侧向力函数(F函数)、负荷转移敏感度函数(G函数)、... 以235/55R19轿车子午线轮胎为例,采用稳态力和力矩试验法与动态侧偏扫掠法进行对比试验,并计算轮胎的性能评价函数值。结果表明:稳态力和力矩试验法得到的侧偏角为1°,4°时的侧向力函数(F函数)、负荷转移敏感度函数(G函数)、回正力矩函数(AT函数)值随垂向负荷呈线性变化,趋势与动态侧偏扫掠法基本一致;但动态侧偏扫掠法回正力矩波动大,导致AT函数值随垂向负荷的增大而波动大;稳态力和力矩试验法与动态侧偏扫掠法下的F函数值和H函数值差异较小,但差异随着垂向负荷的增大而增大;2种方法的G函数值和AT函数值差异均较大。 展开更多
关键词 轮胎 性能评价函数 魔术公式 稳态力和力矩试验法 动态侧偏扫掠法
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松筋针点面结合扫散法治疗背肌筋膜炎的疗效观察
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作者 郭敏 《反射疗法与康复医学》 2024年第12期13-18,共6页
目的探讨松筋针点面结合扫散法治疗背肌筋膜炎的临床疗效。方法选取杭州市中医院淳安院区2019年1月—2023年12月收治的70例背肌筋膜炎患者为研究对象,按随机数字表法将其分为治疗组(n=34)和对照组(n=33)。对照组采用小针刀治疗,治疗组... 目的探讨松筋针点面结合扫散法治疗背肌筋膜炎的临床疗效。方法选取杭州市中医院淳安院区2019年1月—2023年12月收治的70例背肌筋膜炎患者为研究对象,按随机数字表法将其分为治疗组(n=34)和对照组(n=33)。对照组采用小针刀治疗,治疗组在对照组基础上联合松筋针点面结合扫散法治疗,两组均治疗2周。比较两组的疼痛情况、压痛条索面积、软组织症状量化评分、背部红外热成像温度、炎性因子和致痛因子水平及临床疗效。结果治疗后,治疗组疼痛分级指数、疼痛视觉模拟、现有疼痛强度评分均低于对照组,组间差异有统计学意义(P<0.05);治疗组压痛条索面积小于对照组,差异有统计学意义(P<0.05);治疗组痛疼、压痛、肿胀、功能障碍、感觉异常、失眠评分均低于对照组,组间差异有统计学意义(P<0.05);治疗组背部最高温度、最低温度、平均温度、温度差均低于对照组,组间差异有统计学意义(P<0.05);治疗组肿瘤坏死因子-α、白细胞介素-1β、白细胞介素-6及P物质水平均低于对照组,组间差异有统计学意义(P<0.05)。治疗组愈显率为82.29%,高于对照组的60.61%,差异有统计学意义(P<0.05)。两组治疗总有效率比较,差异无统计学意义(P>0.05)。结论松筋针点面结合扫散法是一种治疗背肌筋膜炎的有效方法,能有效改善患者的临床症状,降低炎症因子和致痛因子水平,提高临床疗效,具有一定的推广价值。 展开更多
关键词 背肌筋膜炎 松筋针 点面结合扫散法
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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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A New Indicator Reaction and Its Application-Catalytic Determination of Ultratrace Amounts of Rhodium with Linear Sweep Voltammetry
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作者 WANG Li-sheng and JIANG Zhi-liang (Department of Chemistry, Guangxi Normal University, Guilin, 541004) 《Chemical Research in Chinese Universities》 SCIE CAS CSCD 1993年第1期85-90,共6页
Introduction Sensitive linear sweep voltammetry to have been applied to the catalytic kinetic analysis may be helpful for the application of some organic reagents to the analysis of inorganic ones by voltammetry, The ... Introduction Sensitive linear sweep voltammetry to have been applied to the catalytic kinetic analysis may be helpful for the application of some organic reagents to the analysis of inorganic ones by voltammetry, The catalytic reaction-linear sweep voltammetric method for the determination of noble metals, such as Ag, Os, Ru and Ir has been developed, but no report about the method for the determination of rhodium has been published so far. 展开更多
关键词 Linear sweep voltammetry Catalyti method RHODIUM Fast green
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Methods to Improve the Long Distance Time-Varying Channel Transmission Performance of Expendable Profiler
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作者 ZHENG Yu ZHANG Xiao-yang +2 位作者 WANG Xiao-rui GUO Xing-xin LI Hong-zhi 《China Ocean Engineering》 SCIE EI CSCD 2019年第6期753-761,共9页
To improve the transmission performance of XCTD channel, this paper proposes a method to measure directly and fit the channel transmission characteristics by using frequency sweeping method. Sinusoidal signals with a ... To improve the transmission performance of XCTD channel, this paper proposes a method to measure directly and fit the channel transmission characteristics by using frequency sweeping method. Sinusoidal signals with a frequency range of 100 Hz to 10 k Hz and an interval of 100 Hz are used to measure transmission characteristics of channels with lengths of 300 m, 800 m, 1300 m, and 1800 m. The correctness of the fitted channel characteristics by transmitting square wave, composite waves of different frequencies, and ASK modulation are verified. The results show that when the frequency of the signal is below 1500 Hz, the channel has very little effect on the signal. The signal compensated for amplitude and phase at the receiver is not as good as the uncompensated signal.Alternatively, when the signal frequency is above 1500 Hz, the channel distorts the signal. The quality of signal compensated for amplitude and phase at receiver is better than that of the uncompensated signal. Thus, we can select the appropriate frequency for XCTD system and the appropriate way to process the received signals. Signals below1500 Hz can be directly used at the receiving end. Signals above 1500 Hz are used after amplitude and phase compensation at the receiving end. 展开更多
关键词 expandable conductivity temperature depth(XCTD)profiler time-varying channel modeling frequency sweeping method amplitude and phase compensation transmission performance
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