Liquid vortexes and flows induced by femtosecond laser ablation in liquid governing formation of circular and crisscross LIPSS

Orientations of laser induced periodic surface structures(LIPSS)are usually considered to be governed by the laser polarization state.In this work,we unveil that fluid dynamics induced by femtosecond(fs)laser ablation in liquid(fs-LAL)can easily break this polarization restriction to produce irregular circular-LIPSS(CLIPPS)and crisscross-LIPSS(CCLIPSS).Fs laser ablation of silicon in water shows formation of diverse LIPSS depending on ablation conditions.At a high power of 700 mW(repetition rate of 100 kHz,pulse duration of 457 fs and wavelength of 1045 nm),single/twin CLIPSS are produced at the bottom of macropores of several microns in diameter due to the formation of strong liquid vortexes and occurrence of the vortex shedding effect.Theoretical simulations validate our speculation about the formation of liquid vortex with an ultrahigh static pressure,which can induce the microstructure trenches and cracks at the sidewalls for fs-LAL of Si and tungsten(W)in water,respectively.At a low power of 50 mW,weak liquid vortexes are produced,which only give birth to curved LIPSS in the valleys of grooves.Consequently,it is deduced that liquid vortex plays a crucial role in the formation of macropores.Mountain-like microstructures induce complex fluid dynamics which can cause the formation of CCLIPSS on them.It is believed that liquid vortexes and fluid dynamics presented in this work open up new possibilities to diversify the morphologies of LIPSS formed by fs-LAL.

Relationship Between Watershed Landscape Pattern Change and Runoff-Sediment in Wind-Water Erosion Crisscross Region

This paper selected the typical wind-water erosion crisscross region Xiliugou watershed for research to reveal the impact of the landscape pattern change of the underlying surface in wind-water erosion crisscross region where soil erosion is most serious on rainfall and runoff as well as erosion and sediment.Based on the Landsat TM image data and measured data of runoff-sediment in that watershed,the paper analyzed the characteristics of watershed landscape pattern change and runoff-sediment and explored the relationship between landscape index and runoff-sediment yield by means of GIS and Fragstats.The results were included as follows.(1)Grassland was the dominant landscape.In terms of the number of patches and area change rate,from 1985 to 2010,cultivated land,forest land and construction land were most stable,followed by unused land.Unused land,grassland and cultivated land experienced the most dramatic conversion and maximally affected by human activities.(2)The inter-annual difference between annual runoff and annual sediment load was significant.Compared with the annual sediment load,the trend of decreasing runoff was more obvious.The correlation coefficient of runoff-sediment was 0.67,representing a significant correlation.(3)There was a significant correlation between the landscape index and runoff-sediment.The runoff was negatively correlated with the largest patch index,patch cohesion index,aggregation index and contagion index,but positively correlated with landscape morphology index and landscape division index.And the sediment was negatively correlated with the contagion index,aggregation index and plaque cohesion index,but positively correlated with other landscape indexes.The results indicate that with the increase of the largest patch index,patch cohesion index and aggregation index,the rainfall infiltration capacity increase obviously and the soil erosion reduce significantly.Therefore,increasing the largest patch index,patch cohesion and aggregation index of the watershed landscape can enhance the function of water storage and soil conservation as well as ecological optimization in the windwater erosion crisscross region.The results can provide theoretical support for the ecological environment construction and comprehensive utilization of water and soil resources.

Shielding Effect and Emission Criterion of a Screw Dislocation Near an Interfacial Crisscross Crack

Shielding effect and emission criterion of a screw dislocation near an interracial crisscross crack are dealt within this paper. Utilizing the conformal mapping technique, the closed-form solutions are derived for complex potentialsand stress fields due to a screw dislocation located near the interracial crisscross crack. The stress intensity factor onthe crack tips and the critical stress intensity factor for dislocation emission are also calculated. The influence of theorientation of the dislocation and the morphology of the crisscross crack as well as the material elastic dissimilarity onthe shielding effect and the emission criterion is discussed in detail. The results show that positive screw dislocations canreduce the stress intensity factor of the interracial crisscross crack tip (shielding effect). The shielding effect increases withthe increase of the shear modulus of the lower half-plane, but it decreases with the increase of the dislocation azimuthangle and the distance between the dislocation and the crack tip. The critical loads at infinity for dislocation emissionincreases with the increase of emission angle and the vertical length of the crisscross crack, and the most probable anglefor screw dislocation emission is zero. The present solutions contain previous results as special cases.

Influence of Vegetation on Runoff and Sediment in Wind-water Erosion Crisscross Region in the Upper Yellow River of China

All characteristics of vegetation,runoff and sediment from 1960 to 2010 in the Xiliu Gully Watershed,which is a representative watershed in wind-water erosion crisscross region in the upper reaches of the Yellow River of China,have been analyzed in this study.Based on the remote sensing image data,and used multi-spectral interpretation method,the characteristics of vegetation variation in the Xiliu Gully Watershed have been analyzed.And the rules of precipitation,runoff and sediment's changes have been illuminated by using mathematical statistics method.What′s more,the influence mechanism of vegetation on runoff and sediment has been discussed by using the data obtained from artificial rainfall simulation test.The results showed that the main vegetation type was given priority to low coverage,and the area of the low vegetation coverage type was reducing year by year.On the country,the area of the high vegetation coverage type was gradually increasing.In a word,vegetation conditions had got better improved since 2000 when the watershed management project started.The average annual precipitation of the river basin also got slightly increase in 2000–2010.The average annual runoff reduced by 37.5%,and the average annual sediment reduced by 73.9% in the same period.The results of artificial rainfall simulation tests showed that the improvement of vegetation coverage could increase not only soil infiltration but also vegetation evapotranspiration,and then made the rainfall-induced runoff production decrease.Vegetation root system could increases the resistance ability of soil to erosion,and vegetation aboveground part could reduce raindrop kinetic energy and splash soil erosion.Therefore,with the increase of vegetation coverage,the rainfall-induced sediment could decrease.

Spatial distribution of surface rock fragment on hillslopes in a small catchment in wind-water erosion crisscross region of the Loess Plateau

The cover and size distributions of surface rock fragment in hillslopes were investigated by using digital photographing and treating technique in a small catchment in wind-water erosion crisscross region of the Loess Plateau. The results indicated that the maximal cover of rock fragment was pre-sented at mid-position in steep hillslope. Rock fragment presented a general decreasing-trend along the hillslope in gentle hillslope. Rock fragment cover was positively related to gradient, rock fragment size decreased generally along the hillslope, and the size reduced with the gradient. The mean size of rock fragment was at a range of 6―20 mm in the steep hillslope, rock fragment size > 50 mm was rarely presented. The covers of rock fragment at different positions were markedly related to the quantities of rock fragment < 40 mm. The area of rock fragment of 2―50 mm accounted for 60% or more of the total area, dominating the distribution of rock fragment in the hillslopes.

基于POA-GWO-CSO 算法的新能源电力系统精准切负荷控制多目标优化方法

为解决新能源电力系统因功率缺额引发系统频率、电压偏移等一系列安全问题,文章提出了一种基于POA-GWO-CSO算法的电力系统精准切负荷控制多目标优化方法。首先,从电力系统的安全性和经济性两个方面综合考虑电力系统稳定运行和分布式电源出力特性等各项约束条件,提出一种基于负荷分类的精准切负荷控制多目标优化模型;然后,为了增强传统鹈鹕优化算法(POA)全局与局部搜索能力之间的协调关系,克服优化算法在处理复杂问题时出现收敛过早、寻优范围不够、求解精度不高等问题,引入非线性惯性权重因子、灰狼优化算法(GWO)中狼群领导者策略以及纵横交叉法(CSO),对鹈鹕新的个体的位置进行更新;最后,基于改进后的IEEE33节点进行实证分析。分析结果表明,利用改进的POA-GWO算法对紧急切负荷模型进行求解,实现了系统经济性及稳定性的协调控制。

基于成本感知的边缘服务器部署方法

针对移动边缘计算(mobile edge computing,MEC)中边缘服务器(edge server,ES)供应商的成本预算问题,建立一种以最小化时延和部署成本为目标的数学模型。通过归一化方法将其转化为单目标优化问题,提出一种基于交叉算法的鲸鱼优化算法的边缘服务器部署方法;采用精英反向学习策略构造新种群,提高种群的多样性和全局收敛速度;采用改进的非线性收敛因子平衡算法的整体开发能力和局部探索能力;利用纵横交叉策略提高算法跳出局部最优的能力。使用上海电信基站的真实数据集进行仿真,其结果表明,与其它4种算法相比,该算法在时延和部署成本方面的表现均优于其它算法,系统成本下降了42.1%。

基于分布式纵横交叉-正余弦算法的多区域综合能源系统日前经济调度

综合能源系统由于地理位置分散,各区域能源禀赋、负荷特性存在差异,难免会出现资源配置不协调的问题。另外,各区域能源系统通常为不同能源运营商,以往集中式调度计算无法保护各区域数据隐私。针对复杂高维的综合能源系统经济调度问题,提出了一种分布式纵横交叉-正余弦算法(DCSO-SCA)。首先,将正弦余弦算法(SCA)加入到纵横交叉算法(CSO)中,提高了种群的多样性和算法的开发能力。其次,DCSO-SCA算法在不需要集中控制器的基础上,采用CSO-SCA独立实现区域调度并行优化,降低经济调度问题的求解维度,以完全分散的方式解决综合能源系统经济调度问题,保护各个区域的数据私密性。最后通过案例与其他技术进行对比,DCSO-SCA算法能得到高效益及低耗能的多区域综合能源系统经济调度方案。

黄土高原水蚀风蚀交错区不同生物结皮类型对土壤有机碳及其转化的影响

[目的]黄土高原水蚀风蚀交错区是典型的脆弱生态系统,该区域生物结皮广泛分布,生物结皮在土壤有机碳积累与转化发挥着关键作用,然而,生物结皮演替及微生物对土壤有机碳转化相关酶类的影响规律尚不明确。[方法]研究土壤有机碳-微生物-碳转化相关酶在生物结皮不同演替类型的变化规律,并运用SEM模型分析了三者之间的相互关系。[结果](1)生物结皮演替显著增加土壤有机碳含量和碳转化相关酶活性,且它们在结皮层(0-2 cm)中的含量均显著高于裸沙和2—5 cm土层(p<0.05);(2)结皮层细菌、真菌和放线菌数量在藓结皮中最高,其中放线菌、真菌数量在生物结皮演替呈显著增加趋势,结皮层中的细菌和真菌数量显著高于2—5 cm土层,但2—5 cm土层放线菌数量高于结皮层(藓结皮除外);(3)SEM模型表明,土壤有机碳、碳转化相关酶活性和微生物数量之间均呈现显著相关性。[结论]生物结皮的演替对土壤有机碳的积累为碳转化相关酶类和微生物提供丰富基质,促进微生物和酶活性提高,微生物对碳转化相关酶类起着重要的驱动作用,对维持生物结皮的碳平衡发挥着关键作用。

1970—2020年黄土高原水蚀风蚀交错区极端降水时空变化研究及驱动因素分析

黄土高原水蚀风蚀交错区作为中国北方典型的生态脆弱区,因其独特地形和气候条件,极端降雨事件对其环境和生态系统的影响更加突出。选取水蚀风蚀交错区28个气象站点,结合RClimDex模型计算11个极端降水指数,采用线性相关分析法、Mann-Kendall趋势检验法和小波交叉法,分析了1970—2020年黄土高原水蚀风蚀交错区极端降水事件时空分布特征,探讨了极端降水事件的驱动因素。结果表明:(1)1970—2020年水蚀风蚀交错区持续干燥日数(CDD)呈下降趋势,其余10个指数呈上升趋势,反映出近50a研究区极端降水事件的频率、量级和强度不断增加。交错区年降水量增加和极端降水事件增加具有密切关系,且极端降水事件增加主要是由中雨日数(R10)和大雨日数(R20)引起。(2)1970—2020年极端降水事件在全区整体为增加趋势,交错区中部和西南部极端降水事件显著发生,陕西段极端降水量和强度呈显著增加趋势且极端化程度更显著。(3)湿日总降水量(PRCPTOT)、暴雨日数(R25)、5d最大降水量(R5d)3个极端降水指数,与影响因子厄尔尼诺-南方涛动(ENSO)、东亚夏季风(EASM)和太阳黑子(SN)具有不同的功率,与SN的交叉小波变换功率最大,说明影响因子中SN和极端降水指数的相关性最高,SN对极端降水事件的影响最大。

基于纵横交叉算法的新型电力系统惯量延迟优化控制策略

以同步发电机为主导的电力系统正在演变为以虚拟同步机(virtual synchronous generator,VSG)为主导的新型电力系统,电力系统的动态特性发生了重大变化。现阶段,绝大多数文献的研究场景是在无穷大电源的基础下,分析单机或多机并网系统的动态特性,对全部虚拟同步机为主导的电力系统动态特性研究较少。因此,先建立了全部虚拟同步机为主导的三机九节点系统的模型,通过微分方程仿真得到系统的动态特性曲线。然后,利用纵横交叉算法(crisscross optimization,CSO),延迟优化新型电力系统惯量,并与无优化控制系统作对比,在系统发生扰动后,优化后的系统振荡幅值变小,调节时间变小。最后,通过仿真验证了上述结论的正确性。

基于改进麻雀搜索算法的虚拟机放置方法

针对目前云数据中心存在资源利用率低、能源浪费严重的问题,提出一种基于改进麻雀搜索算法的虚拟机放置方法。针对基本麻雀搜索算法应用到虚拟机放置中存在易陷入局部最优、种群多样性不足等问题做出改进。在探索者位置更新后引入横纵交叉策略进行优化,改善算法在迭代前期就过早收敛于局部最优解的缺陷;将Levy飞行机制引入追随者位置更新中,扩大搜索范围,增加种群多样性;采用动态调节的透镜成像反向学习策略对种群个体求解反向解,增强种群逃离局部最优的能力。以降低能耗、资源浪费和SLA违背率为优化目标,采用基于模糊评估的方式对放置方案进行评价。实验结果显示,改进后的算法能减少资源浪费,提高服务质量,并且能显著降低能耗。

基于多元模态分解与多目标算法优化的深度集成学习模型的超短期风电功率预测

针对风电功率预测问题,提出了一种基于多元变分模态分解(multivariate variational mode decomposition,MVMD)、多目标纵横交叉优化(multi-objective crisscross optimization,MOCSO)算法和Blending集成学习的超短期风电功率预测。在数据处理阶段,为了保持各序列间的同步相关性以及分解后得到本征模态函数(intrinsic mode functions,IMF)分量个数和分量频率相匹配,使用MVMD对多通道原始数据进行同步分解。针对单一机器学习模型导致预测的全面性不足,且存在精度和鲁棒性低的问题,提出基于MOCSO算法动态加权的Blending集成学习模型。通过对递归神经网络、卷积神经网络、长短期记忆网络的预测结果进行动态加权集成,并通过MOCSO优化调整权重,以提高模型的预测准确性与稳定性。实验结果表明,所提预测模型不仅有效,且显著优于其他预测模型。

计及子区域能量互济的多区域综合能源系统优化调度

多区域综合能源系统由于地理位置不同,通常处于独立运行状态,各个区域间缺乏联系。针对这一现象,提出一种子区域能量互济的多区域综合能源系统模型,在满足各区域电热冷功率平衡的同时,实现区域间能量互济,并以系统的总运行成本最小为目标函数,利用纵横交叉算法对模型进行求解。通过对比多区域独立运行模式与计及子区域能量互济模式的仿真结果表明,计及子区域互济模式能够合理分配能源,减少综合能源系统对电网与天然气网的总需求量,从而有效提高经济效益。

双种群纵横交叉正弦余弦算法

针对基本正弦余弦算法在求解复杂优化问题时求解精度偏低,收敛速度慢及不能跳出局部最优等问题,提出了一种双种群纵横交叉正弦余弦算法。在初始化种群阶段引入Logistic混沌映射,使初始种群均匀分布;非线性调整转换参数并改进正弦余弦位置更新公式,以平衡算法全局搜索和局部开发的能力,加快算法的求解速度;采用双种群和择优选择策略,实现正弦余弦种群和纵横交叉种群优势互补、协同进化,提高算法跳出局部最优解的能力和算法收敛速度。采用23个基准测试函数对改进算法进行仿真实验,并与其它智能优化算法进行比较分析,结果表明改进算法有更好的优化性能。

基于自适应模态分解和融合双尺度注意力机制的时间卷积网络的超短期风电功率预测

针对风电功率强波动性限制预测精度的问题,提出一种基于自适应变分模态(adaptive variational mode decomposition,AVMD)和融合双尺度注意力(double-scale attention,DA)的时间卷积神经网络(temporal convolutional network,TCN)的超短期风电功率预测模型AVMD-DATCN。采用纵横交叉(crisscross optimization,CSO)算法对变分模态分解参数进行优化,提出动态混合熵(dynamic mixing entropy,DME)作为适应度函数以兼顾分解损失和分解子序列可预测性,将风电功率自适应分解为一系列稳定有序的子分量。针对各分量建立DATCN预测模型以充分挖掘潜在深层耦合非连续时序特征,将各分量预测值叠加重构得到最终预测结果。多角度对比实验结果表明,所提出模型的预测性能显著优于其他预测方法。

基于纵横交叉算法的储能系统自适应控制策略

大量储能设备通过虚拟同步机(VSG)并入电网时,传统固定惯量和阻尼控制策略中,控制参数选取不当会造成调节时间长或超调量大,且无法充分发挥VSG控制灵活的优势。为此,提出了基于纵横交叉(CSO)算法的储能系统自适应控制策略,首先,建立了储能系统VSG系统,将储能VSG系统频率的误差与电压总谐波畸变率之和的最小值作为CSO的目标函数,并引入电池的荷电状态(SOE)约束求解最佳惯量以及阻尼,该算法收敛速度更快且有效地规避了参数局部解。在此基础上,设计一种改进的惯量阻尼自适应控制策略,有效地改善了VSG的动态性能。最后,通过Matlab/Simulink搭建仿真模型,验证了所提策略的有效性。

山东各地区输电线路基础型式选择分析

依据输电线路不同基础类型特性,采用全过程机械化施工方式,综合考虑山东地区地形地质,通过对不同地形(平原、丘陵、山地等)基础型式的选用进行技术经济对比,给出基础型式建议。对于平原地区,无水条件下,基础作用力在小于500kN和大于800kN时,推荐开挖基础;基础作用力在500~800kN时,推荐灌注桩基础;在基础作用力大于800kN,基础尺寸超过5.5m×5.5m(长×宽),埋深超过3.5m,考虑减少环水保破坏时,推荐灌注桩基础。在0m水地区,灌注桩基础更加符合环水保要求,推荐使用灌注桩基础。对于丘陵、山地地区,基础作用力小于260kN的普通土地区和软质岩地区土层覆盖大于5.0m时,推荐挖孔基础;基础作用力大于300kN的普通土地区和软质岩地区土层覆盖小于5.0m时,推荐岩石锚杆基础和挖孔基础。对于存在岩石地区,推荐开挖基础。对于山地硬质岩地区,根据岩性不同,推荐岩石锚杆基础、微型桩基础和挖孔基础。对于河网泥沼地区,推荐灌注桩基础。

基于改进纵横交叉算法的高速铁路牵引供电动态潮流计算

传统高速铁路牵引供电动态潮流计算方法标准差值偏移较大。本文提出基于改进纵横交叉算法的高速铁路牵引供电动态潮流计算。首先对牵引供电装置输出特性进行提取,随后对高速铁路牵引供电进行建模,基于高速铁路牵引供电建模,以列车牵引计算结果及行车计划为输入。最后基于改进纵横交叉算法对高速铁路牵引供电系统求解,实现高速铁路牵引供电动态潮流计算,实验结果表明该研究方法计算结果标准差值偏移量更小。

Double Enhanced Solution Quality Boosted RIME Algorithm with Crisscross Operations for Breast Cancer Image Segmentation

The persistently high incidence of breast cancer emphasizes the need for precise detection in its diagnosis.Computer-aided medical systems are designed to provide accurate information and reduce human errors,in which accurate and effective segmentation of medical images plays a pivotal role in improving clinical outcomes.Multilevel Threshold Image Segmentation(MTIS)is widely favored due to its stability and straightforward implementation.Especially when dealing with sophisticated anatomical structures,high-level thresholding is a crucial technique in identifying fine details.To enhance the accuracy of complex breast cancer image segmentation,this paper proposes an improved version of RIME optimizer EECRIME,denoted as the double Enhanced solution quality Crisscross RIME algorithm.The original RIME initially conducts an efficient optimization to target promising solutions.The double-enhanced solution quality(EESQ)mechanism is proposed for thorough exploitation without falling into local optimum.In contrast,the crisscross operations perform a further local exploration of the generated feasible solutions.The performance of EECRIME is verified with basic and advanced algorithms on IEEE CEC2017 benchmark functions.Furthermore,an EECRIME-based MTIS method in combination with Kapur’s entropy is applied to segment breast Infiltrating Ductal Carcinoma(IDC)histology images.The results demonstrate that the developed model significantly surpasses its competitors,establishing it as a practical approach for complex medical image processing.