The Effect of the First order Responses of Mooring Line on the Second order Mooring Line Damping

In this paper we investigated the effect of the first order responses of mooring line on the second order mooring line damping.In the study of the slow oscillating of a moored floating structure by perturbation method in frequency domain,the second order equations of the mooring line are divided into non homogeneous and homogeneous equations.The solutions are related to the first order responses of mooring line and second order floating structure oscillation respectively.In order to find the effect of the first order responses of mooring line,the second order mooring line tension and damping were determined by solving the non homogeneous equation and homogeneous equation.From the results,we found,although the second order mooring line tension obtained from the non homogenous equation is quite small compared with the total second order mooring line tension,the damping contributed from both of them are in the same order in quantity.So,in predicting the second order mooring line damping,the effect of the solution related to the non homogeneous equation can not be omitted.

Second-Order Adjoint Sensitivity Analysis Methodology for Computing Exactly Response Sensitivities to Uncertain Parameters and Boundaries of Linear Systems: Mathematical Framework

This work presents the “Second-Order Comprehensive Adjoint Sensitivity Analysis Methodology (2nd-CASAM)” for the efficient and exact computation of 1st- and 2nd-order response sensitivities to uncertain parameters and domain boundaries of linear systems. The model’s response (i.e., model result of interest) is a generic nonlinear function of the model’s forward and adjoint state functions, and also depends on the imprecisely known boundaries and model parameters. In the practically important particular case when the response is a scalar-valued functional of the forward and adjoint state functions characterizing a model comprising N parameters, the 2nd-CASAM requires a single large-scale computation using the First-Level Adjoint Sensitivity System (1st-LASS) for obtaining all of the first-order response sensitivities, and at most N large-scale computations using the Second-Level Adjoint Sensitivity System (2nd-LASS) for obtaining exactly all of the second-order response sensitivities. In contradistinction, forward other methods would require (N2/2 + 3 N/2) large-scale computations for obtaining all of the first- and second-order sensitivities. This work also shows that constructing and solving the 2nd-LASS requires very little additional effort beyond the construction of the 1st-LASS needed for computing the first-order sensitivities. Solving the equations underlying the 1st-LASS and 2nd-LASS requires the same computational solvers as needed for solving (i.e., “inverting”) either the forward or the adjoint linear operators underlying the initial model. Therefore, the same computer software and “solvers” used for solving the original system of equations can also be used for solving the 1st-LASS and the 2nd-LASS. Since neither the 1st-LASS nor the 2nd-LASS involves any differentials of the operators underlying the original system, the 1st-LASS is designated as a “first-level” (as opposed to a “first-order”) adjoint sensitivity system, while the 2nd-LASS is designated as a “second-level” (rather than a “second-order”) adjoint sensitivity system. Mixed second-order response sensitivities involving boundary parameters may arise from all source terms of the 2nd-LASS that involve the imprecisely known boundary parameters. Notably, the 2nd-LASS encompasses an automatic, inherent, and independent “solution verification” mechanism of the correctness and accuracy of the 2nd-level adjoint functions needed for the efficient and exact computation of the second-order sensitivities.

Static response analysis of structures with interval parameters using the second-order Taylor series expansion and the DCA for QB

In this paper, based on the second-order Taylor series expansion and the difference of convex functions algo- rithm for quadratic problems with box constraints （the DCA for QB）, a new method is proposed to solve the static response problem of structures with fairly large uncertainties in interval parameters. Although current methods are effective for solving the static response problem of structures with interval parameters with small uncertainties, these methods may fail to estimate the region of the static response of uncertain structures if the uncertainties in the parameters are fairly large. To resolve this problem, first, the general expression of the static response of structures in terms of structural parameters is derived based on the second-order Taylor series expansion. Then the problem of determining the bounds of the static response of uncertain structures is transformed into a series of quadratic problems with box constraints. These quadratic problems with box constraints can be solved using the DCA approach effectively. The numerical examples are given to illustrate the accuracy and the efficiency of the proposed method when comparing with other existing methods.

Illustrative Application of the 2^nd-Order Adjoint Sensitivity Analysis Methodology to a Paradigm Linear Evolution/Transmission Model: Point-Detector Response

This work illustrates the application of the “Second Order Comprehensive Adjoint Sensitivity Analysis Methodology” (2nd-CASAM) to a mathematical model that can simulate the evolution and/or transmission of particles in a heterogeneous medium. The model response is the value of the model’s state function (particle concentration or particle flux) at a point in phase-space, which would simulate a pointwise measurement of the respective state function. This paradigm model admits exact closed-form expressions for all of the 1st- and 2nd-order response sensitivities to the model’s uncertain parameters and domain boundaries. These closed-form expressions can be used to verify the numerical results of production and/or commercial software, e.g., particle transport codes. Furthermore, this paradigm model comprises many uncertain parameters which have relative sensitivities of identical magnitudes. Therefore, this paradigm model could serve as a stringent benchmark for inter-comparing the performances of all deterministic and statistical sensitivity analysis methods, including the 2nd-CASAM.

Illustrative Application of the 2^nd-Order Adjoint Sensitivity Analysis Methodology to a Paradigm Linear Evolution/Transmission Model: Reaction-Rate Detector Response

This work continues the illustrative application of the “Second Order Comprehensive Adjoint Sensitivity Analysis Methodology” (2nd-CASAM) to a benchmark mathematical model that can simulate the evolution and/or transmission of particles in a heterogeneous medium. The model response considered in this work is a reaction-rate detector response, which provides the average interactions of particles with the respective detector or, alternatively, the time-average of the concentration of a mixture of substances in a medium. The definition of this model response includes both uncertain boundary points of the benchmark, thereby providing both direct and indirect contributions to the response sensitivities stemming from the boundaries. The exact expressions for the 1st- and 2nd-order response sensitivities to the boundary and model parameters obtained in this work can serve as stringent benchmarks for inter-comparing the performances of all (deterministic and statistical) sensitivity analysis methods.

A New Method of Construction of Robust Second Order Rotatable Designs Using Balanced Incomplete Block Designs

The following article has been retracted due to the investigation of complaints received against it. Title: A New Method of Construction of Robust Second Order Rotatable Designs Using Balanced Incomplete Block Designs Authors: Bejjam Re. Victorbabu, Kottapalli Rajyalakshmi. The above paper is a copy of Dr. Rabindra Nath Das’s former article, entitled '“Robust second order rotatable designs (Part I)”. The scientific community takes a very strong view on this matter and we solemnly withdrawn?the paper from the journal OJS. This paper published in OJS Vol.2 No.1, 39-47, 2012, has been retracted.

Application of Response Surface Methodology for Optimization of Fluoride Removal Mechanism by Newely Developed Biomaterial

The adsorption capacities of new biomaterials derived from lemon leaf (Citrus sp.) toward fluoride ions have been explored by varying different physicochemical parameters such as pH, initial concentration, adsorbent dose, contact time, stirring rate and temperature. The entire study was done through batch process. Maximum fluoride adsorption of 96.9% - 98.8% was achieved with an initial concentration of 10 mg/L. Langmuir isotherm model well expressed fluoride ad- sorption onto LLD-1, LLD-2 and LLD-3. According to correlation coefficient, the fluoride adsorption onto these 3 ad- sorbents was correlated well with pseudo-second-order kinetic model. From thermodynamic study, the spontaneous nature and feasibility of the adsorption process with negative enthalpy (&#916H0) value also supported the exothermic nature were shown. The rate of fluoride adsorption was mathematically described as a function of experimental parameters and was modeled through Box-Behnken (Response surface methodology). The results showed that the responses of fluoride adsorption were significantly affected by the quadratic term of pH, initial concentration, contact time and temperature and the statistical analysis was performed by ANOVA which indicated good correlation of experimental parameters.

A New Method of Construction of Robust Second Order Slope Rotatable Designs Using Pairwise Balanced Designs

The following article has been retracted due to the investigation of complaints received against it. Title: A New Method of Construction of Robust Second Order Slope Rotatable Designs Using Pairwise Balanced Designs. Authors: Bejjam Re. Victorbabu, Kottapalli Rajyalakshmi.The paper is a copy of Dr. Rabindra Nath Das’s former article, entitled “Slope rotatability with correlated errors (Vol. 54, pp. 57-70, 2003)” and “Robust second order rotatable designs (Part I)”. The scientific community takes a very strong view on this matter and we treat all unethical behavior such as plagiarism seriously. This paper published in OJSVol.2 No.3, 319-327, 2012, has been removed from this site.

二阶Stokes波作用下多孔弹性海床动力响应解析解

基于二阶Stokes波理论,研究了非线性海洋波作用下多孔弹性海床的动力响应问题。利用Biot固结理论以及Verruijt储存方程,在笛卡尔坐标下建立了海床的控制方程。通过将海洋波函数拓展到复数域,采用严格的数学推导求得了海床动力响应的解析解,并将该解与既有解进行对比验证。最后分析了波浪和海床特征参数对海床有效应力、剪切应力和孔压分布的影响,结果表明波浪和海床的参数对海床动力响应具有显著的影响。其中波浪周期和水深对二阶Stokes波的二阶项有较大影响,渗透系数和剪切模量则分别影响海床动力响应的变化速率和幅值。

考虑电力负荷需求和分布式电源不确定性的配电网重构

随着可再生能源和可变负荷在配电系统中比例的逐步提高,配电网中电力流向的不确定性对最优网络拓扑结构的影响越来越显著。由于分布式发电和需求响应受时间因素影响,按单时段建模所得到的拓扑结构在一天中的不同时段难以达到最优。为解决这种不确定因素的影响,文章提出了一种基于二阶锥优化的配电网重构模型,进行计及需求响应的多时段潮流分析。基于实际配网系统所存在的“源-储-荷”结构,建立了以网络运行成本和开关运行成本为目标的约束条件,利用二阶锥松弛将非凸形式搜索空间转化为凸可行域,从而进行快速求解。在改进的IEEE 33节点配电网上进行测试分析,结果表明,文章提出的方法比传统方法具有更高的准确性和更快的求解速度。

基于响应面法的船舶节能导管优化设计

以水动力节能装置经典伴流补偿导管为研究对象,提出利用响应面模型综合评价导管设计参数并进行优化.以导管结构特征尺寸为设计参数,建立节能导管的参数化模型.以KP505螺旋桨和节能导管耦合的水动力计算结果为响应参数,生成响应面模型.将螺旋桨效率提升比作为优化目标,将导管结构特征尺寸阈值作为约束条件,基于二阶响应面模型对导管进行结构优化设计,并对优化结果进行仿真验证,证明响应面模型的可靠性.结果表明,优化后桨-管系统的效率提升比增大了37.82%,说明利用构建的响应面模型对节能导管进行优化合理有效,可为其他类型的节能导管设计提供参考.

水下爆炸作用下结构弹塑性动响应数值计算方法

针对水下爆炸强冲击载荷作用下结构塑性永久变形问题,建立流固耦合数值计算模型,采用二阶双重渐近法(DAA2)对流固耦合模型解耦,流体和结构数值模型利用分部法交错计算。流体部分对结构湿表面建立边界元模型,通过Newmark时间积分法求解二阶DAA方程;结构部分基于考虑弹塑性效应的任意参考构型理论建立了有限元运动方程,采用前增量位移时间积分法进行显式求解,避免流固耦合数据交互过程中的迭代修正以简化求解流程。对水下爆炸结构动响应问题进行数值模拟,并与理论及试验结果进行对比。结果表明,在水下爆炸产生的强冲击载荷作用下结构会发生永久塑性变形,本研究方法计算得到的位移、速度、应力等结构响应量与相关参考结果相吻合。表明发展的水下爆炸流固耦合求解方法可准确模拟强冲击载荷作用下的结构弹塑性动响应,拓展了DAA2方法的应用范围。

基于二阶注意力的Siamese网络视觉跟踪算法

为提升基于Siamese网络视觉跟踪算法的特征表达能力和判别能力,以获得更好的跟踪性能,提出了一种轻量级的基于二阶注意力的Siamese网络视觉跟踪算法。使用轻量级VGG-Net作为Siamese网络的主干,获取目标的深度特征;在Siamese网络的末端并行使用所提残差二阶池化网络和二阶空间注意力网络,获取具有通道相关性的二阶注意力特征和具有空间相关性的二阶注意力特征;使用残差二阶通道注意力特征和二阶空间注意力特征,通过双分支响应策略实现视觉跟踪。利用GOT-10k数据集对所提算法进行端到端的训练,并在OTB100和VOT2018数据集上进行验证。实验结果表明:所提算法的跟踪性能取得了显著提升,与基准算法SiamFC相比,在OTB100数据集上,精度和成功率分别提高了0.100和0.096,在VOT2018数据集上,预期平均重叠率(EAO)提高了0.077,跟踪速度达到了48帧/s。

考虑P-Δ效应的钢-混凝土混合塔筒动力响应分析

为了提高风电机组钢-混凝土混合塔筒动力响应的分析效率,将风电机组钢-混凝土混合塔筒视为自由端有集中质量的欧拉-伯努利悬臂梁,提出了动力响应的高效分析方法.该方法考虑了重力二阶效应(P-Δ效应)对整体结构的动力响应,以及钢材与混凝土对结构整体阻尼比的影响.通过与基于ABAQUS的有限元模拟结果进行对比,验证了所提出分析方法的有效性,并研究了P-Δ效应对整体动力响应的影响程度.对比结果表明:与忽略P-Δ效应相比,考虑P-Δ效应时理论分析结果更接近于有限元分析结果;理论分析结果与有限元分析结果关于位移、速度和加速度均方根的最大相对误差分别为3.09%、3.81%、4.63%.这表明所建立的风电机组钢-混凝土混合塔筒动力响应分析模型具有与有限元分析相当的计算精度.

基于MOGWO的45#钢表面激光抛光工艺参数多目标优化

目的提高45#钢表面激光抛光后的成形质量,提出一种激光抛光工艺参数多目标优化方法。方法构建基于功率、扫描速度、搭接距离的三因素三水平激光抛光试验,并分别应用粗糙度测量仪、显微硬度计和超景深三维显微镜测试抛光层的粗糙度、显微硬度和抛光层深度。基于试验数据,分别应用指数模型和二阶响应面模型构建抛光工艺参数与表面粗糙度、显微硬度、抛光深度的回归预测模型,并对2种模型的预测精度进行对比分析。采用多目标灰狼优化算法(MOGWO)结合优劣解距离法(TOPSIS)-CRITIC综合评价决策体系对抛光工艺参数进行寻优和多属性决策。结果二阶响应面模型具有更高的预测精度,能够更好地反映激光抛光工艺参数与各响应目标之间的映射关系。当功率为113W、扫描速度为3m/min、搭接距离为0.13 mm时,粗糙度值Ra从11.563μm降至5.713μm,降幅为50.59%,显微硬度从185.9HV0.5升至364.7HV0.5,升幅为96.18%,此时的抛光深度为0.051 mm,最大相对误差为7.84%。结论此方法可以为其他金属材料表面激光抛光质量预测模型的构建及工艺参数寻优提供借鉴。

宽带共形阵基于SRV约束的自适应波束设计

自适应波束形成可以有效抑制非期望信号方向上的干扰信号。针对采用节拍延迟线(Tapped Delay Line,TDL)结构和复数加权系数的宽带共形阵,本文提出一种基于空间响应偏差SRV(Spatial Response Variation)约束的自适应频率不变波束形成器(Frequency Invariant Beamformer,FIB)优化设计方法。该自适应FIB在参考频率上保持预测信号方向无偏响应以及旁瓣级恒定这2个限制条件下,根据对波束形成器输出功率值与平均空间响应偏差值这2项的加权和进行最小化处理的准则进行设计。通过将这种FIB设计问题转化为标准二阶锥规划(Second Order Cone Programming,SOCP)形式后,可以采用内点方法对其进行有效求解。仿真结果验证了本文方法对于宽带共形阵自适应FIB设计的有效性。

中国南海神狐海域水合物储层井壁稳定可靠度分析

天然气水合物具有巨大的潜在经济和环境价值,其开发利用对国家能源安全和实现国家碳达峰碳中和的“双碳目标”具有战略意义。我国天然气水合物资源主要分布于南海海域,海洋环境的复杂性和隐蔽性使工程测量数据具有较大不确定性,影响钻井安全。目前未见有水合物储层井壁稳定可靠度研究。为定量评估在我国南海神狐海域水合物储层钻井风险,基于水合物储层钻井井壁稳定解析理论和南海神狐海域具体地质条件,结合可靠度分析方法中的改进一次二阶矩法和响应面法,研究南海神狐海域水合物储层钻井井壁失稳概率分布特征,分析该海域井壁失稳概率及安全钻井液压力窗口对主要参数均值和不确定性的敏感性,结果表明:(1)若测量数据足够精确,在我国南海神狐海域水合物储层进行钻井活动的安全性较高,安全钻井液压力窗口也较大。测量数据的不确定性增大将使井壁失稳概率显著升高,缩窄安全钻井液压力窗口。(2)较低的钻井液温度对降低井壁失稳概率略有帮助,且能明显地扩大安全钻井液压力窗口。(3)5个主要参数的均值和不确定性对井壁失稳概率的影响次序相同,均为初始地应力>初始内摩擦角>弹性模量比>初始黏聚力>初始弹性模量。实际工程中对初始地应力数据精确测量,能够显著提高水合物储层钻井井壁稳定性。

考虑需求响应的交直流混合配电网分布式光伏承载能力鲁棒评估方法

鲁棒优化通常采用多面体模型来描述分布式光伏出力的不确定性,却忽略了分布式光伏出力的时空相关性,为此,该文建立了分布式光伏的时空相关性多面体模型,提出了考虑需求侧响应的交直流混合配电网分布式光伏承载能力鲁棒评估方法。首先,建立分布式光伏出力不确定性的时空相关性多面体模型和电价激励型需求侧响应模型,以最大化分布式光伏并网容量为目标,考虑交直流混合配电网中多种运行约束和调节策略,建立交直流混合配电网分布式光伏承载能力两阶段鲁棒评估模型,并采用列与约束生成算法进行迭代求解。在70节点系统上验证了算法的有效性,仿真结果表明:不同的管理策略有助于提升交直流混合配电网的分布式光伏承载能力。

基于二阶锥规划的FIR最小主瓣差异波束形成

针对传统宽带数字波束形成器精度低、主瓣误差大、旁瓣峰值高的问题,研究了一种基于二阶锥规划的FIR最小主瓣差异波束形成方法。首先采用基于FIR滤波器结构设计出的波束形成器,将传统方法中的小数预延迟改进为整数预延迟与FIR滤波器结合,以提高精度。然后,通过引入滤波器系数,将旁瓣级与FIR滤波器的阻带衰减级联系在一起,并且采用全局优化的方法将传统方法中的2个凸优化问题合为1个凸优化问题,确保了所得解是综合最优解。最后,重新定义主瓣响应误差,提出基于旁瓣峰值约束Minimax主瓣差异的FIR波束形成器设计准则。仿真结果表明,所提方法在时、空、频域中的表现都优于传统宽带波束形成方法。

基于RCSA和二阶有限差分法的刀尖点频响函数预测研究

铣削系统动态特性参数对切削过程的稳定性起着非常重要的作用,而获取由刀具尖点频响函数表示的该参数是实现无颤振切削的先决条件。基于响应耦合子结构法,将铣削系统划分为主轴刀柄和刀具两个子系统,将刀具子系统进一步细分为刀杆和刀齿两个子系统。综合运用模态锤击实验和二阶有限差分法等辨析方法,考虑旋转响应的主轴刀柄末端频响函数,将铣刀简化为欧拉-伯努利梁,计算出铣刀子结构的频响函数,通过响应耦合获得铣削系统刀尖点频响函数,模型的正确性得到了实验验证。