HAZARD REGRESSION WITH PENALIZED SPLINE:THE SMOOTHING PARAMETER CHOICE AND ASYMPTOTICS

In this article, we use penalized spline to estimate the hazard function from a set of censored failure time data. A new approach to estimate the amount of smoothing is provided. Under regularity conditions we establish the consistency and the asymptotic normality of the penalized likelihood estimators. Numerical studies and an example are conducted to evaluate the performances of the new procedure.

Phenotypic and genetic parameter estimation of juvenile growth and bottom color traits in half-smooth tongue sole,Cynoglossus semilaevis

Half-smooth tongue sole（Cynoglossus semilaevis） is a commercially important fish species. There were no reports about accurate genetic parameters of growth traits in C. semilaevis, despite efforts aimed at the culture of this species. Therefore, the main goal of this study was to estimate the parameters for the early growth traits（total length, body depth and body weight） of C. semilaevis based on the data obtained from 80 families. The trait of fish with pure white bottom or not（named as the trait of bottom color） was also analyzed. All the heritabilities estimated for the traits were medium, which varied from 0.210 to 0.362. Genetic correlations among growth traits were highly positive, varying from 0.913 to 0.959, indicating that selection of one of the three traits would result in correlated increase in the others. Also, genetic correlations between bottom color and growth traits were positive and varying from 0.241 to 0.353, suggesting that selection for the bottom color can be utilized to enhance the selection of growth traits. In addition, fish from the top performing 16 full-sib families were selected as broodstock, based on the above analysis and the comparison of family breeding value. This research provides an important basic material to implement selective breeding in C. semilaevis.

D_∞-APPROXIMATION OF PRODUCT VARIATIONS OF TWO PARAMETER SMOOTH SEMIMARTINGALES

Let X be a two parameter smooth semimartingale and (?) be its process of the product variation. It is proved that (?) can be approximated as D_∞-limit of sums of its discrete product variations as the mesh of division tends to zero. Moreover, this result can be strengthen to yield the quasi sure convergence of sums by estimating the speed of the convergence.

Cyclic Lattices, Ideal Lattices and Bounds for the Smoothing Parameter

In this article, we introduce the discrete subgroup in ℝn as preliminaries first. Then we provide some theories of cyclic lattices and ideal lattices. By regarding the cyclic lattices and ideal lattices as the correspondences of finitely generated R-modules, we prove our main theorem, i.e. the correspondence between cyclic lattices in ℝn and finitely generated R-modules is one-to-one. Finally, we give an explicit and countable upper bound for the smoothing parameter of cyclic lattices.

基于鲁棒双参数指数平滑法的BDS卫星钟差预报

为提高北斗(BDS)卫星钟差预报精度与稳定性,基于BDS卫星钟工作原理与数据特征,提出了一种基于鲁棒双参数指数平滑法的BDS卫星钟差预报方法。将双参数指数平滑法引入BDS钟差预报,并通过鲁棒化建模与优化初始值选取方式提升了双参数指数平滑法的抗差与适应能力,减小了数据异常干扰对钟差预报性能的影响。与常用的多项式模型、谱分析模型、灰色预测模型及超快速钟差预报产品进行对比分析,结果表明:所提方法适用于不同BDS轨道与类型的卫星钟差预报,取得了良好的预报精度与稳定性,其对BDS卫星钟的6h平均预报精度分别提升了40.3%、31.7%、63.6%和36.6%,预报稳定性分别提升了43.8%、38.9%、65.4%和33.1%。

一种适用宽速域冲击的明胶鸟弹数值建模方法

明胶鸟弹在不同撞击速度下表现出不同的响应特性。为解决传统明胶鸟弹本构表征方法在不同速度范围内不能通用的问题,开展了330 g明胶鸟弹以70~190 m/s速度、60°或90°入射刚性铝合金平板试验,记录了冲击力数据及撞击形貌。结果表明,随着撞击速度的提高,鸟弹碎裂得更充分,碎块体积减小。利用LS-DYNA建立了自适应FEM-SPH(finite element method-smoothed particle hydrodynamics)鸟体模型。依据试验结果反演得到一组鸟体本构参数:切线模量为1.33MPa,剪切模量为115.95MPa,Murnaghan状态方程参数γ为10.49,k_(0)为69.77 MPa,体积模量为246.4 MPa,失效塑性应变为1.15,初始屈服应力为0.21 MPa。仿真结果与试验结果具有很好的一致性,冲击力峰值的相对误差在2%以内,冲量的相对误差在10%以内。自适应FEM-SPH鸟体模型具有比SPH模型和拉格朗日模型更高的精度。由自适应模型得到的Hugoniot压强与理论结果具有相同的变化趋势,滞止压强与理论值较接近。

面向新能源波动平抑的储能多参数等价折算配置方法

基于储能在参与调节新能源出力随机性和波动性的重要作用,针对由储能种类多样性和参数复杂性导致的储能选型和配置困难问题,提出了一种面向新能源波动平抑的储能快速选型与配置方法。首先,从储能的物理模型本质出发,综合考虑储能的多类型参数,提出了一种储能多参数等价折算的方法;该方法将储能的荷电状态(state of charge,SOC)、寿命、效率和初始投资成本等多参数对比等价折算为功率和容量的配置成本对比,对复杂参数关系进行综合量化表征,实现对储能价值的快速准确评估。然后,为保证新能源出力平滑,建立了不同时间尺度下的新能源波动平抑指标,提出了新能源波动平抑的储能优化配置模型。该模型以储能成本、限电损失费用和新能源波动越限惩罚费用最小化为目标,考虑系统的运行约束与储能约束,实现系统技术和经济性能的最优化。最后,根据某实际算例的波动平抑需求调研了多种应用广泛的储能系统,基于所提储能多参数等价折算方法对不同储能的技术经济参数进行分析与比较,验证了所提的储能选型配置方法和新能源波动平抑模型的有效性和适用性。

间隙约束悬臂梁系统的不连续分岔

间隙约束悬臂梁广泛应用在机械和工程设计中,其动态力学特性的优劣直接反映主机运行品质的高低,是决定主机能否安全和高效运行的关键因素.从多参数角度研究悬臂梁碰撞系统的动力学可实现系统的动态特性与功能目标的优化设计.考虑间隙约束悬臂梁系统,构建由光滑流映射复合的全局Poincaré映射及其Jacobi矩阵.应用数值方法获得各类吸引子在两参数平面的存在区域,结合数值仿真、延拓打靶法和胞映射研究相邻对称型周期1吸引子经混合运动域的转迁特征及共存吸引子的形成机理,揭示不稳定吸引子在系统动力学演化过程中的重要作用,以及不同类型的激变、迟滞、鞍结型周期倍化分岔和亚临界叉式分岔等不连续分岔行为.结果表明,在含对称间隙弹性碰撞系统中,周期吸引子的不连续分岔呈现9种不同的类型.叉式分岔使多吸引子共存更加普遍.两个反对称的不稳定周期轨道可引起两个共存的混沌吸引子同时发生内部激变.叉式型擦边分岔和9种不连续分岔的定义将进一步丰富非光滑系统动力学.

热处理对银包铜粉表面光滑度的影响

为解决银包铜粉在导电浆料中的应用问题,本文采用化学镀与浸涂法结合制备银包铜粉,通过控制热处理工艺来改善镀银层表面的平整光滑性,并利用扫描电镜、电阻测试仪等研究了热处理工艺对银包铜粉镀银层形貌、抗氧化性、导电性和吸油率的影响。研究发现:采用化学镀与浸涂法结合的方法,可以制备表面更光滑的银包铜粉;随着热处理温度的升高,银层愈加光滑平整;但当热处理温度为700℃时,银包铜粉会出现破裂团聚的现象,且随着热处理时间的延长,银包铜粉结构发生畸变和团聚。研究表明,控制热处理工艺可以改善银层表面平整光滑性,从而降低其在电子浆料中的吸油率,提高抗氧化性和导电性。当热处理温度为600℃,保温时间10 min时,制备得到的银包铜粉形貌最好,综合性能最佳。

基于随机森林算法的隧(巷)道光面爆破参数选择模型研究

为解决隧(巷)道光面爆破中参数选择困难的问题,构建了基于随机森林算法的隧(巷)道光面爆破参数选择模型。模型以围岩质量分级BQ、隧(巷)道断面面积、炮眼直径为输入参数,以最小抵抗线长度、炮眼间距、炮眼深度为输出参数。使用了24个训练样本、7个测试样本进行模型训练及测试,结果表明,炮眼间距、最小抵抗线长度、炮眼深度3个输出参数值与测试样本对应参数值之间的平均相对误差分别为17%、8.8%、22%,可见模型对于最小抵抗线长度的选择效果较好,对炮眼间距、炮眼深度的选择效果欠佳。

低地板有轨电车平稳性影响要素分析

针对某低地板有轨电车在车辆设计阶段平稳性指标超标的问题,从车辆参数和轨道激励两个方面进行原因探析。通过对车辆关键参数的优化分析可知:降低二系刚度和阻尼能够适当地改善车辆的运行平稳性,但过小的刚度和阻尼在工程应用中难以实现。通过对美国五级谱和德国高干扰谱进行时频域特征分析可知:轨道谱短波高频振动能量较大是有轨电车平稳性超标的原因,建议定期对钢轨进行打磨,以此来控制轨道短波的振动能量。

A Parameter Adaptive Method for Image Smoothing

Edge is the key information in the process of image smoothing. Some edges, especially the weak edges, are difficult to maintain, which result in the local area being over-smoothed. For the protection of weak edges, we propose an image smoothing algorithm based on global sparse structure and parameter adaptation. The algorithm decomposes the image into high frequency and low frequency part based on global sparse structure. The low frequency part contains less texture information which is relatively easy to smoothen. The high frequency part is more sensitive to edge information so it is more suitable for the selection of smoothing parameters. To reduce the computational complexity and improve the effect, we propose a bicubic polynomial fitting method to fit all the sample values into a surface. Finally, we use Alternating Direction Method of Multipliers (ADMM) to unify the whole algorithm and obtain the smoothed results by iterative optimization. Compared with traditional methods and deep learning methods, as well as the application tasks of edge extraction, image abstraction, pseudo-boundary removal, and image enhancement, it shows that our algorithm can preserve the local weak edge of the image more effectively, and the visual effect of smoothed results is better.

Adaptive linear active disturbance-rejection control strategy reduces the impulse current of compressed air energy storage connected to the grid

The merits of compressed air energy storage(CAES)include large power generation capacity,long service life,and environmental safety.When a CAES plant is switched to the grid-connected mode and participates in grid regulation,using the traditional control mode with low accuracy can result in excess grid-connected impulse current and junction voltage.This occurs because the CAES output voltage does not match the frequency,amplitude,and phase of the power grid voltage.Therefore,an adaptive linear active disturbance-rejection control(A-LADRC)strategy was proposed.Based on the LADRC strategy,which is more accurate than the traditional proportional integral controller,the proposed controller is enhanced to allow adaptive adjustment of bandwidth parameters,resulting in improved accuracy and response speed.The problem of large impulse current when CAES is switched to the grid-connected mode is addressed,and the frequency fluctuation is reduced.Finally,the effectiveness of the proposed strategy in reducing the impact of CAES on the grid connection was verified using a hardware-in-the-loop simulation platform.The influence of the k value in the adaptive-adjustment formula on the A-LADRC was analyzed through simulation.The anti-interference performance of the control was verified by increasing and decreasing the load during the presynchronization process.

基于多参数随机变化的高速动车组动力学指标分布研究

针对服役高速动车组关键悬挂部件动力学参数变化后动力学指标分布特征缺乏的问题,对运营里程为145万km的某型动车组的转臂节点径向和轴向刚度、抗蛇行减振器0.01和0.02 m·s^(-1)加载速度下的阻尼力进行测试和统计,结果均服从正态分布;建立并验证动车组参数化的动力学仿真模型,将转臂节点刚度和抗蛇行减振器阻尼力视为随机变量,构建基于改进拉丁超立方抽样的高速动车组动力学仿真方法,包含拉丁超立方抽样、轮轨型面与抽样结果组合、更换动车组仿真模型参数、动车组动力学仿真及动力学指标计算、动力学指标统计分析等内容。采用该方法进行动车组的动力学仿真计算,结果表明:服役近145万km的动车组脱轨系数、轮轴横向力和构架横向加速度随车轮磨耗的增加呈上升趋势,轮重减载率、垂向平稳性、横向平稳性指标呈先上升后下降趋势,但所有指标均未超限;脱轨系数、轮重减载率、轮轴横向力、横向平稳性指标、垂向平稳性指标及构架横向加速度均呈正态分布;脱轨系数分布范围为0.036~0.207,均值为0.075,标准差为0.020;轮重减载率分布范围为0.107~0.262,均值为0.164,标准差为0.036;轮轴横向力分布范围为4.209~16.701 kN,均值为8.438kN,标准差为2.221 kN;横向平稳性指标分布范围为1.351~2.469,均值为1.566,标准差为0.149,垂向平稳性指标分布范围为2.260~2.323,均值为2.273,标准差为0.005;构架横向加速度分布范围为0.906~3.994 m·s^(-2),均值为1.978 m·s^(-2),标准差为0.590 m·s^(-2)。

新冠疫情对我国股债市场的影响研究——基于ARIMA模型的实证分析

新冠疫情对全球金融市场产生了巨大影响,我国股票和债券市场也受到较大影响。研究新冠疫情对中国股债市场的影响,可以帮助投资者了解市场状况,规避风险,对其他地区的股债市场也具有借鉴意义。选择2019年9月9日至2020年4月1日的上证指数收盘价和国债指数收盘价数据进行分析,并以新冠疫情对股债市场造成冲击为分界点,将数据分为疫情冲击前和疫情冲击后两个时间段。具体思路为:使用疫情大规模暴发前的数据建立ARIMA模型和Holt两参数指数平滑预测模型,通过比较确定最优模型为ARIMA模型,然后使用ARIMA模型进行短期预测,将预测值和实际值进行对比分析,得出新冠疫情对股债市场收益的影响。结果表明:①在预测股票市场和债券市场收益方面,建立ARIMA模型要优于Holt两参数指数平滑法。②新冠疫情在短期内对股票市场产生负向作用,对债券市场产生正向作用,但随着时间的推移,股票市场和债券市场最终还是会趋于平衡状态。

一种张量域空间平滑解相干参数估计算法

为了提高传统空间平滑算法对相干信号的估计精度,提出了一种张量域空间平滑多重信号分类(Multiple Signal Classification,MUSIC)解相干算法。首先,利用四元数的正交特性重新构造极化域导向矢量;其次,考虑阵列接收数据固有的多维结构特征,构造三阶张量表示的阵列接收数据模型;接着,借鉴二维空间平滑算法的思想,在张量接收数据模型中构建三阶张量子阵块,再使该子阵块在张量域进行前向空间平滑,继而得到平滑后的张量协方差矩阵;最后,通过高阶奇异值分解(Higher-order Singular Value Decomposition,HOSVD)得到信号子空间,利用降维MUSIC算法对相干信号源的二维波达方向(Direction of Arrival,DOA)进行估计,并根据已经获得的DOA信息求解出相干信号的极化参数。仿真结果表明,在信噪比为0 dB以及快拍数为100的情况下,该算法的估计精度比空间平滑算法提高了约70%,成功分辨概率提高了约89%,且无需进行四维谱峰搜索,降低了算法的复杂度,对相干信号具有更高的估计精度和分辨能力。

混合直流系统中基于平波电抗器与限流电抗器参数优化的限流策略

直流线路正常运行过程中,平波电抗器可以减小电流纹波。当直流线路发生故障时,限流电抗器的快速投入可以抑制故障电流的上升速度。因此,考虑限流电抗器与平波电抗器的协同,不仅可以抑制故障电流的上升速度,而且能够降低直流断路器的切断容量。然而,受到投资成本和系统动态特性的制约,平波电抗器与限流电抗器的电感容量需要保持在合理的范围内。因此,对直流输电系统中平波电抗器和限流电抗器的容量进行优化配置,在保证限流能力的同时降低投资是十分有意义的。首先,建立了交直流混联系统的故障等效模型,并分析直流线路发生双极性短路时两端故障电流的特性。其次,建立了平波电抗器和限流电抗器的优化配置数学模型。最后,基于MATLAB仿真试验对所提限流策略进行了验证。

秦岭马白山隧道硬岩段光面爆破参数优化

光面爆破是硬岩隧道开挖的主要施工方法,由于破岩机理复杂,若爆破参数设计不合理,易导致硬岩隧道光面爆破成型控制较困难。西十高铁秦岭马白山隧道围岩以燕山期花岗岩为主,Ⅱ、Ⅲ级围岩占隧道全线70%以上。以该隧道工程为研究背景,针对原方案爆破后存在的隧道超欠挖、二次爆破施工等问题,利用ANSYS/LS-DYNA有限元软件对光面爆破成型控制进行数值模拟,分析硬岩隧道爆破应力波传播规律及围岩损伤情况,揭示爆破扰动下硬岩应力演化特征及变形破坏规律,提出光面爆破参数优化措施,有效改善爆破效果。该研究成果可为硬岩隧道全断面光面爆破开挖参数设计与施工提供借鉴。

基于遗传算法的隧道光面爆破参数优化模型研究

隧道光面爆破是一种控制爆破技术,能够保持新壁面平整而不受明显破坏。提出了一种基于遗传算法的隧道光面爆破参数优化模型,该模型以隧道光面爆破效果的综合评价函数为目标函数,以隧道开挖断面尺寸、岩性等级、地质条件等为约束条件,以周边孔间距、光爆层厚度、装药量等为决策变量,通过选择、交叉、变异等操作,不断产生新的个体,并根据适应度函数评价个体的优劣,最终得到最优或近似最优的隧道光面爆破参数。通过算例分析,验证了该模型的有效性和可行性,为隧道工程提供了合理且优化的光面爆破参数,提高了隧道质量和安全性。

Dynamic threshold for SPWVD parameter estimation based on Otsu algorithm

Time-frequency-based methods are proven to be effective for parameter estimation of linear frequency modulation （LFM） signals. The smoothed pseudo Winger-Ville distribution （SPWVD） is used for the parameter estimation of multi-LFM signals, and a method of the SPWVD binarization by a dynamic threshold based on the Otsu algorithm is proposed. The proposed method is effective in the demand for the estimation of different parameters and the unknown signal-to-noise ratio （SNR） circumstance. The performance of this method is confirmed by numerical simulation.