Characteristics and Mechanisms of Persistent Wet–Cold Events with Different Cold-air Paths in South China

We investigate the characteristics and mechanisms of persistent wet–cold events(PWCEs)with different types of coldair paths.Results show that the cumulative single-station frequency of the PWCEs in the western part of South China is higher than that in the eastern part.The pattern of single-station frequency of the PWCEs are“Yangtze River(YR)uniform”and“east–west inverse”.The YR uniform pattern is the dominant mode,so we focus on this pattern.The cold-air paths for PWCEs of the YR uniform pattern are divided into three types—namely,the west,northwest and north types—among which the west type accounts for the largest proportion.The differences in atmospheric circulation of the PWCEs under the three types of paths are obvious.The thermal inversion layer in the lower troposphere is favorable for precipitation during the PWCEs.The positive water vapor budget for the three types of PWCEs mainly appears at the southern boundary.

The Coordinated Influence of Indian Ocean Sea Surface Temperature and Arctic Sea Ice on Anomalous Northeast China Cold Vortex Activities with Different Paths during Late Summer

The Northeast China cold vortex(NCCV)during late summer(from July to August)is identified and classified into three types in terms of its movement path using machine learning.The relationships of the three types of NCCV intensity with atmospheric circulations in late summer,the sea surface temperature(SST),and Arctic sea ice concentration(SIC)in the preceding months,are analyzed.The sensitivity tests by the Community Atmosphere Model version 5.3(CAM5.3)are used to verify the statistical results.The results show that the coordination pattern of East Asia-Pacific(EAP)and Lake Baikal high pressure forced by SST anomalies in the North Indian Ocean dipole mode(NIOD)during the preceding April and SIC anomalies in the Nansen Basin during the preceding June results in an intensity anomaly for the first type of NCCV.While the pattern of high pressure over the Urals and Okhotsk Sea and low pressure over Lake Baikal during late summer-which is forced by SST anomalies in the South Indian Ocean dipole mode(SIOD)in the preceding June and SIC anomalies in the Barents Sea in the preceding April-causes the intensity anomaly of the second type.The third type is atypical and is not analyzed in detail.Sensitivity tests,jointly forced by the SST and SIC in the preceding period,can well reproduce the observations.In contrast,the results forced separately by the SST and SIC are poor,indicating that the NCCV during late summer is likely influenced by the coordinated effects of both SST and SIC in the preceding months.

Classification of Northeast China Cold Vortex Activity Paths in Early Summer Based on K-means Clustering and Their Climate Impact

The classification of the Northeast China Cold Vortex(NCCV)activity paths is an important way to analyze its characteristics in detail.Based on the daily precipitation data of the northeastern China(NEC)region,and the atmospheric circulation field and temperature field data of ERA-Interim for every six hours,the NCCV processes during the early summer(June)seasons from 1979 to 2018 were objectively identified.Then,the NCCV processes were classified using a machine learning method(k-means)according to the characteristic parameters of the activity path information.The rationality of the classification results was verified from two aspects,as follows:(1)the atmospheric circulation configuration of the NCCV on various paths;and(2)its influences on the climate conditions in the NEC.The obtained results showed that the activity paths of the NCCV could be divided into four types according to such characteristics as the generation origin,movement direction,and movement velocity of the NCCV.These included the generation-eastward movement type in the east of the Mongolia Plateau(eastward movement type or type A);generation-southeast longdistance movement type in the upstream of the Lena River(southeast long-distance movement type or type B);generationeastward less-movement type near Lake Baikal(eastward less-movement type or type C);and the generation-southward less-movement type in eastern Siberia(southward less-movement type or type D).There were obvious differences observed in the atmospheric circulation configuration and the climate impact of the NCCV on the four above-mentioned types of paths,which indicated that the classification results were reasonable.

Influence of Al addition on solidification path and hot tearing susceptibility of Mg-2Zn-(3+0.5 x)Y-x Al alloys

Hot tearing susceptibility(HTS)of Mg-2Zn-(3+0.5 x)Y-x Al(x=0,2 and 3 at%)alloys is predicted by using modified Clyne-Davies’model(CSC^(∗)).The solidification path,solidification characteristic temperatures and dendritic coherency solid fraction have been studied by double-thermocouple thermal analysis.The solidification contraction stress vs.temperature(and time)curves are measured by using a“T”type hot tearing permanent-mold.The results reveal that the CSC^(∗)prediction values are in good agreement with the experimental results.Moreover,Al_(2)Y phase acts as the heterogeneous nucleation core ofα-Mg and significantly influences the grain size.It has been observed that minimum grain size,optimal dendritic coherency and minimum HTS are exhibited by Mg-2Zn-(3+0.5 x)Y-x Al alloy(x=2).Furthermore,when Al content was increased to 3 at%,Al_(2)Y phase exhibited a peritectic reaction and transformed into a mixed structure of Al_(2)Y and Al+Al_(3)Y phases,which increased the HTS of the alloy due to reduced fine-grained Al_(2)Y content.

Control and application of cooling path after rolling for hot strip based on ultra fast cooling

Hot rolled strip requires diverse and flexible control of cooling path in order to take full advantages of strengthening mechanisms such as fine grain strengthening, precipitation strengthening, and transformation strengthening, adapting to the development of advanced steel materials and the requirement of reduction-manufacturing. Ultra fast cooling can achieve a great range of cooling rate, which provides the means that the hardened austenite obtained in high temperature region can keep at different dynamic transformation temperatures. Meanwhile, through the rational allocation of the UFC （ultra fast cooling） and LFC （laminar flow cooling）, more flexible cooling path control and cooling strategy of hot rolled strip are obtained. Temperature distribution and control strategies under different cooling paths based on UFC are investigated. The process control temperature can be limited within 18 ℃, and the mechanical properties of the steels get a great leap forward due to the cooling paths and strategies, which can decrease costs and create great economic benefits for the iron and steel enterprises.

Influence of stress path change on the resistance to plastic deformation of cold rolled sheets

Flat workpieces have been tested in order to investigate the influence of stress path change （loading mode） while keeping strain path unchanged. These investigations are pertinent to the testing of cold rolled strips and to subsequent forming. The workpieces which first compressed by plane strain compression in thickness direction were then tested in perpendicular direction in order to measure the influence of strain and stress path. The tension workpieces came from flat die compression test at different deformation histories. Two different materials were investigated： 18/8 Ti stainless steel and AW-1050 aluminium. The results show that the plastic flow by tension in lengthwise direction after pre-strain by compression in thickness direction will begin at an appreciably lower stress than that of the workpieces unloaded after pre-compression. Comparing with two materials, it can be seen that both 18/8 Ti stainless steel and AW-1050 aluminium behave similarly. The drop in yield stress is lower for AW-1050 aluminium than that for 18/8 Ti stainless steel. However, reloading in different directions than in the precious step results in significantly higher strain hardening.

Expanding Hot Code Path for Data Cleaning on Software Graph

Graph analysis can be done at scale by using Spark GraphX which loading data into memory and running graph analysis in parallel.In this way,we should take data out of graph databases and put it into memory.Considering the limitation of memory size,the premise of accelerating graph analytical process reduces the graph data to a suitable size without too much loss of similarity to the original graph.This paper presents our method of data cleaning on the software graph.We use SEQUITUR data compression algorithm to find out hot code path and store it as a whole paths directed acyclic graph.Hot code path is inherent regularity of a program.About 10 to 200 hot code path account for 40%-99%of a program’s execution cost.These hot paths are acyclic contribute more than 0.1%-1.0%of some execution metric.We expand hot code path to a suitable size which is good for runtime and keeps similarity to the original graph.

乡村振兴背景下农产品冷链物流基础设施建设路径研究

加快农产品冷链物流基础设施建设是推动农产品冷链物流高质量发展,促进乡村产业振兴的重要途径。农产品冷链物流基础设施对延长农产品货架期和销售半径、降低损失率、构建全程冷链物流体系具有重要作用。在乡村振兴背景下,中国农产品冷链物流基础设施建设日益完善,但仍然存在总量不足、结构及分布不均衡、冷链意识有待提高、技术应用不足、标准体系不完善、发展政策落实不到位、建设主体能力不强等问题,应当从扶持建设主体、加强布局规划、提升冷链物流意识、推进先进技术应用等方面进行完善。

非冷链商品配送路径优化研究--以京东配送为例

如何有效降低商品配送成本是物流企业的关注重点,学界已就带时间窗的商品配送路径优化算法展开了相关研究,但相关算法还存在着过早陷入局部最优或无法收敛的问题。由此提出一种改进的变邻域遗传搜索算法(VNS-GA),以非冷链商品配送为研究对象,构造起求解物流配送车辆路径规划的数学模型。首先,以配送成本和缺货惩罚成本的最小化作为实现目标,构建了包括车辆使用成本、配送运输成本和时间窗口惩罚成本的配送路径优化模型;其次,运用变邻域遗传优化算法来实现多目标物流配送路径的优化;最后,以京东某北京配送中心的物流配送为例,运用MATLAB软件对VNS-GA算法模型的科学性及有效性进行仿真验证。经实证,VNS-GA算法与传统算法相比具有更好的全局和局部搜索能力。研究期望为配送车辆调度与配送路径规划提供更优的路径选择模型,从而降低物流配送成本和减少便利店因缺货造成的损失。

时间窗约束下农产品物流配送路径优化研究

农产品需求量增加对物流配送提出较高挑战,基于此提出时间窗约束下农产品物流配送路径优化方法研究。依客户预期服务时间需求,取混合时间窗约束函数确定时间窗、物流配送车辆最大载重、配送路径长度与物流配送车辆约束条件,构建农产品物流配送路径优化模型;基于农产品物流配送需求改进传统遗传算法,求解构建模型,即获农产品物流配送路径优化结果。实验结果显示:相较生鲜农产品多车型冷链物流车辆路径优化,所提方法最优农产品物流配送路径获取迭代次数更少、配送路径长度更短、总成本更低,应用性能更佳。

云南冬季强降温过程冷空气路径及大气环流差异

基于云南125个测站日平均气温数据,判定了1961—2020年云南冬季95次强降温过程的4种冷空气路径,对比分析了不同路径冷空气对云南降温的影响及大气环流差异.结果表明,东北路径冷空气对云南降温幅度影响最剧烈、影响空间范围最广;偏东路径出现频率最高,偏东路径和偏北路径在降温幅度和影响范围上较为接近;东南路径降温幅度和影响范围最弱,出现频率最低.超前强降温日2 d时,东北路径欧亚大陆500 hPa位势高度场上正高度距平异常区域强度和面积、700 hPa反气旋距平环流强度和西伯利亚高压均为最强,东南路径最弱,偏东路径和偏北路径介于前二者之间.东北路径500 hPa上东亚槽横槽转竖特征最明显,偏东路径和偏北路径东亚槽槽底南压加深,但转竖特征不及东北路径明显;东南路径东亚槽底部较宽广;东北路径副高呈块状面积最小,其它3种路径副高则呈带状,偏东路径副高面积最大.700 hPa上东北路径和偏东路径在日本附近有较强海平面气压负距平发展,朝鲜半岛气旋距平环流较强,其西侧较强的偏北气流引导冷空气进入云南;东南路径和偏北路径在朝鲜半岛气旋距平环流及其西侧的偏北气流较弱.在200 hPa纬向风距平场上,东北路径急流轴附近正负距平区强度最强,偏东路径沿急流轴距平分布为西正东负;东南路径正负距平区强度最弱,负距平区主要分布在急流轴北侧,偏北路径负距平区分布在急流轴南北两侧.

晶界效应下的焊接热裂倾向判据适用性研究

材料焊接热裂倾向评判在产品制造中具有重要作用,以往热裂倾向判据并未考虑晶界效应,故其适用性一直是讨论的热点问题。文中以Al-Cu合金为例,通过多晶凝固定量相场模型获取熔池凝固过程枝晶形貌,提取凝固路径。基于凝固路径开展了目前常用热裂倾向判据的适用性研究,包含RDG判据、Clyne-Davies判据和Sindo Kou判据。研究发现,RDG判据同实际焊接热裂倾向一致,且裂纹产生主要受孤立晶界段枝晶间压力降主导;Clyne-Davies判据及Sindo Kou判据评判由于计算过程忽略部分孤立晶界区间段,导致评判结果出现失真。通过对三个判据的研究,为材料热裂倾向评判提供了参考。

多配送中心半开放式冷链物流配送路径优化

为了解决冷链物流服务的成本、质量以及运输产生的碳排放等问题,构建多中心半开放式冷链物流路径优化模型,并将各种动态变化融入该模型中。设计一种改进的NSGA-II算法并利用标准测试函数证实该算法具有较好的收敛性与多样性。通过算例实验,结果表明:与不考虑碳排放方案相比,考虑碳排放方案的配送成本增加了19.00%,运输距离减少了5.16%,碳排放成本降低了13.03%;与初始配送方案相比,实时优化方案的配送成本下降了29.78%,碳排放成本下降了23.19%,客户满意度增幅14.49%;与单配送中心模式相比,多配送中心模式的配送成本降低了27.30%,碳排放成本降低了48.89%,客户满意度提高了13.11%,从而为冷链物流企业带来一定的管理启示。

东北冷涡分类及其对内蒙古东部降水的影响

利用1981—2022年6—8月内蒙古119个国家气象观测站逐日降水资料和NCEP/NCAR逐日再分析资料,分析东北冷涡年际、年代际变化特征及东北冷涡分类对内蒙古东部降水的影响。结果表明:东北冷涡发生频次在1992年之前,较常年值显著偏多,之后显著偏少,2003年以后有增多的趋势,近十年发生频次偏多。将东北冷涡分为10类,中涡东北移是致使东部降水偏多最异常的冷涡类型,中涡东移是次异常的冷涡类型。东亚地区呈现“北高南低”环流型,内蒙古东部位于负位势高度距平区,中心位于东部偏南地区,乌拉尔山和鄂霍次克海阻塞高压偏强,副热带高压偏强,内蒙古东部地区受气旋性环流控制,低层水汽通量辐合,配合越赤道气流共同作用引导的西太平洋水汽输送到东部地区,是东部降水异常偏多的主要环流配置型。

基于客户满意度的低碳冷链多式联运路径优化

目的实现生鲜产品的高效配送,尽可能提高客户满意度。方法分析多式联运和冷链物流的特点,选择最优物流路径。在路径选择模型的建立中,结合客户对生鲜产品的质量及到货时间的满意程度,引入顾客满意度参数。同时响应国家“碳中和”政策的号召,在模型构建中考虑了低碳策略,以总成本最小、客户满意度最大为目标函数。以15个枢纽城市及公路、铁路、水路3种方式的冷链运输为例,将目前较新的帝企鹅算法与传统的启发式算法(遗传算法、粒子群算法)进行对比,并针对转运时间进行灵敏度分析。结果最优联运路线对应的客户满意度为0.96,转运时间的增加导致总成本上升、客户满意度下降和最优路径发生变化。结论帝企鹅算法在求解多式联运问题上具有较好的收敛速度和收敛精度,为多式联运承运人的决策提供了依据。转运时间的波动导致适应度函数发生变化,因此在兼顾客户满意度的前提下,选择合适的运输方式和路径,减少非必要的转运。

基于智能算法的社区团购配送路径优化

在线上购物配送环节中,综合考虑了碳排放成本、运输成本、货损成本、制冷成本、时间窗惩罚成本等多种成本因素,构建以总成本最小为目标的社区团购配送车辆路径优化模型。利用智能算法鲸鱼算法,对配送路径进行优化,验证了该算法的搜索能力和收敛性。

遂宁市农产品冷链物流高质量发展路径的研究——基于SWOT分析

随着人民对高品质生活的追求,农产品冷链物流的需求量呈现爆发式增长。遂宁市作为国家陆港型物流枢纽承载城市,在农产品冷链物流高质量发展过程中有自身的优劣势。本文采用SWOT分析方法,分析了遂宁市农产品冷链物流的政策优势、资源优势、交通优势;冷链物流的硬件建设、冷链物流技术和冷链物流设施设备劣势;冷链物流发展迎来成渝经济圈发展战略和市场繁荣的机遇;冷链物流被成渝极核虹吸、区域竞争压力巨大的威胁。提出“打通最先一公里”、夯实冷链物流交通网络和依托“一主四辅”枢纽布局,打造差异化配送中心的冷链物流高质量发展路径。

考虑速度时变的多配送中心医药冷链配送路径优化

随着医药冷链市场需求的迅速增长,越来越多的城市、企业采用多配送中心模式,因此研究多配送中心模式下的医药冷链路径优化以减少配送成本尤为重要。在实际配送过程中,由于交通拥堵问题,配送车辆无法保持恒定的速度,进而可能导致配送成本的增加。基于此,构建考虑时变速度的多配送中心医药冷链物流路径优化模型,并结合遗传算法与粒子群算法对模型进行求解。通过数值算例的结果表明了模型的合理性和算法的有效性。

考虑碳排放的冷链物流配送路径优化

在考虑传统经济成本的基础上增加考虑配送过程中可能产出的碳排放,并将其以碳排放成本的形式融入到目标函数中,建立考虑碳排放的冷链物流配送模型。通过动态调整启发因子和自适应信息素挥发因子对传统蚁群算法进行优化,提出一种新的改进蚁群算法。通过算例,将考虑碳排放与不考虑碳排放、改进与未改进蚁群算法的情况进行对比。结果表明,该模型和算法具有较好的寻优和收敛能力,可提高冷链物流企业经济效益。

基于物联网的农产品冷链物流路径规划方法

针对传统方法获取的路径信息不准确,故提出基于物联网的农产品冷链物流路径规划方法。采用物联网技术获取农产品冷链物流的路径信息,构建碳排放量目标函数、配送总成本目标函数和客户满意度目标函数,结合模糊数学方法和模糊层次分析方法对目标函数的权重系数进行计算,根据计算结果构建农产品冷链物流路径规划模型,并采用蚁群算法对路径规划模型进行求解,获取规划模型最优解,完成农产品冷链物流路径的规划。实验结果表明,所提方法规划的路径短、碳排放量低、总成本小、规划效果好。