3-D finite element modeling for evolution of stress field and interaction among strong earthquakes in Sichuan-Yunnan region

Based on the latest achievement about activities of geological structure, a 3-D finite-element model containing four layers of upper crust, lower crust (two layers) and upper mantle is established in the paper. By repeated tests and revisions, the boundary conditions of the model are determined. And then the background stress field, the stress field caused by fault creep and the stress field triggered by strong earthquake in Sichuan-Yunnan region, as well as their dynamic variations are calculated. The results indicate that the latter earthquake often occurs in the area with positive Coulomb rupture stress change associated with the former one, the former earthquake has a triggering effect on the latter one to a certain extent, and strong earthquake often occur in groups under the background of high stress, which is of great significance for distinguishing seismic anomalies, as well as for improving the level of earthquake prediction.

Development and Application of a High-Performance Triangular Shell Element and an Explicit Algorithm in OpenSees for Strongly Nonlinear Analysis

The open-source finite element software,OpenSees,is widely used in the earthquake engineering community.However,the shell elements and explicit algorithm in OpenSees still require further improvements.Therefore,in this work,a triangular shell element,NLDKGT,and an explicit algorithm are proposed and implemented in OpenSees.Specifically,based on the generalized conforming theory and the updated Lagrangian formulation,the proposed NLDKGT element is suitable for problems with complicated boundary conditions and strong nonlinearity.The accuracy and reliability of the NLDKGT element are validated through typical cases.Furthermore,by adopting the leapfrog integration method,an explicit algorithm in OpenSees and a modal damping model are developed.Finally,the stability and efficiency of the proposed shell element and explicit algorithm are validated through the nonlinear time-history analysis of a highrise building.

Simulation of near-fault bedrock strong ground-motion field by explicit finite element method

Based on presumed active fault and corresponding model, this paper predicted the near-fault ground motion filed of a scenario earthquake （Mw=6 3/4 ） in an active fault by the explicit finite element method in combination with the source time function with improved transmitting artificial boundary and with high-frequency vibration contained. The results indicate that the improved artificial boundary is stable in numerical computation and the predicted strong ground motion has a consistent characteristic with the observed motion.

Study of Finite Element Modeling of Strong Earthquake Activities and Its Preliminary Application—Taking Southwest China as an Example

Based on research result concerning the preparation and activity of strong earthquakes in groups and using the finite element method, a finite element dynamic model for Southwest China is established in this paper. Using this model, the stress adjustment in the whole of the Southwest China region in response to the stress change due to strong earthquake occurrence is studied. The preliminary result shows that many strong earthquakes occurred in areas where the stress heightened after the last strong earthquake. So, the finite element model set up in this paper is useful for judging the regions where strong earthquakes are likely to occur in future.

Kinematic source model for simulation of near-fault ground motion field using explicit finite element method

This paper briefly reviews the characteristics and major processes of the explicit finite element method in modeling the near-fault ground motion field. The emphasis is on the finite element-related problems in the finite fault source modeling. A modified kinematic source model is presented, in which vibration with some high frequency components is introduced into the traditional slip time function to ensure that the source and ground motion include sufficient high frequency components. The model presented is verified through a simple modeling example. It is shown that the predicted near-fault ground motion field exhibits similar characteristics to those observed in strong motion records, such as the hanging wall effect, vertical effect, fling step effect and velocity pulse effect, etc.

ON ALMOST SURE CONVERGENCE OF WEIGHTED SUMS OF RANDOM ELEMENT SEQUENCES

We mainly study the almost sure limiting behavior of weighted sums of the form ∑ni=1 aiXi/bn , where {Xn, n ≥ 1} is an arbitrary Banach space valued random element sequence or Banach space valued martingale difference sequence and {an, n ≥ 1} and {bn,n ≥ 1} are two sequences of positive constants. Some new strong laws of large numbers for such weighted sums are proved under mild conditions.

ON STRONGLY REGULAR RINGS

?The multiplication semigroup of strongly regular ring R in the light of semigroup is researched,hence some properties of strongly regular rings are obtained. The non-division strongly regular ring R is anilpotent semisimple ring without identity element. It is neither the Artin ring nor the Noether ring. The setidempotents of ring R is an infinite set without the maximum and minimal conditions,it is a unions of someorder sets and hai a non-well-ordered order set at least.

IMPLICIT-EXPLICIT MULTISTEP FINITE ELEMENT-MIXED FINITE ELEMENT METHODS FOR THE TRANSIENT BEHAVIOR OF A SEMICONDUCTOR DEVICE

The transient behavior of a semiconductor device consists of a Poisson equation for the electric potential and of two nonlinear parabolic equations for the electron density and hole density. The electric potential equation is discretized by a mixed finite element method. The electron and hole density equations are treated by implicit-explicit multistep finite element methods. The schemes are very efficient. The optimal order error estimates both in time and space are derived.

Relative Strong F Compactness and Relative Ultra-F Compactness in L-topological Spaces

In this paper, two concepts of relative compactness-the relative strong fuzzy compactness and the relative ultra-fuzzy compactness are defined in L-topological spaces for an arbitrary L-set. Properties of relative strong fuzzy sets and relative ultra-fuzzy compact sets are studied in detail and some characteristic theorems are given. Some examples are illustrated.

A FINITE ELEMENT MODEL FOR SEISMICITY INDUCED BY FAULT INTERACTION

On ths basis of interaction between faults, a finite element model for Southwest China is constructed,and the stress adjustment due to the strong earthquake occurrence in this region was studied. The preliminary results show that many strong earthquakes occurred in the area of increased stress in the model. Though the results are preliminary, the quasi 3D finite element model is meaningful for strong earthquake prediction.

川滇主要断裂带应力应变积累速率的三维有限元模拟:初步结果

川滇地区构造活动强烈,活动断裂众多,强震活动频繁.了解主要活动断裂的应力应变积累速率对于评估该区的长期地震危险性具有重要参考作用.本文新建立川滇地区及其主要活动断裂的三维黏弹性有限元模型,其中考虑了该区的岩石圈结构分层以及介质在水平和深度方向的不均匀性;采用1996—2018年的平均GPS水平速度场约束模型的侧边界,同时考虑川滇地块深部介质的拖曳力过程,模拟计算了构造加载作用下模型的动力学响应——区域变形特征和断裂的应力积累速率.模拟的位移场能很好拟合GPS观测的速度场,模拟的水平主应力方向在川滇块体和华南块体西缘与地震震源主应力方向相符,反映所建模型与模拟结果有较好的可信度.尝试将模拟的应力积累速率与基于GPS/GNSS观测的应变速率相结合,计算能反映区域地壳应变积累程度的弹性应变能密度分布;讨论了主要断裂带的背景应力、弹性应变能密度和库仑应力积累速率与M≥6.0地震发生的关系.结果显示除了模型边界附近的应力奇异地带外,川滇其余地区1996年以来M≥6.0地震大多数发生在模拟应力积累速率高或次高的断裂带(段),以及弹性应变能密度积累速率中偏高的断裂带(段).在模拟的背景应力速率高而且库仑应力增长快的龙门山断裂带南段和鲜水河断裂带最南段,分别在本文写作和定稿阶段发生2022年6月1日四川芦山M6.1地震和2022年9月5日四川泸定M6.8地震.认为研究区具有类似高或者次高的模拟应力和弹性应变能密度积累速率、但至今无强震发生和记录的断裂带(段),潜在的地震危险性需要关注.

重载与中强地震联合作用下的曲线独柱墩桥梁倾覆性分析

为探讨移动车辆和中强地震联合作用对曲线梁桥的抗倾覆影响,建立车-桥-地震分析模型,提出考虑地震作用的曲线梁桥车-桥耦合振动分析方法。以多跨曲线连续梁桥为研究对象,对比分析中强地震和重载车辆偏载组合作用下的支座反力和主梁倾覆时整体转角大小。研究地震动类型、峰值、车辆关键参数等因素对曲线梁桥倾覆稳定性的影响。结果表明:不同车辆和地震荷载组合会改变桥梁的受力情况,纵向间隔2 m的3辆100 t车辆以3 m/s速度行驶时,三跨曲线梁桥的倾覆最明显;综合考虑重载及地震联合作用,对抗倾覆性规范中的稳定系数计算公式进行了修正;分析了五跨曲线梁桥中墩支座偏心距对抗倾覆稳定系数的影响,计算结果表明中墩两相邻支座设置偏心时曲线桥最大抗倾覆系数为1.55。

长期施肥对强筋专用小麦籽粒营养及磨粉品质性状的影响

【目的】分析不同施肥措施对小麦品质性状的影响,为优质小麦提供指导性建议。【方法】有机无机肥配合施用试验位于青岛农业大学莱阳长期定位试验站,始于1978年,共设9个处理,分别为不施肥对照(CK)、适量化肥氮138 kg/hm^(2) (N1)、适量有机肥30000 kg/hm^(2) (M1)、有机肥30000 kg/hm^(2)+化肥氮138 kg/hm^(2)(M1N1)、过量化肥氮276 kg/hm^(2) (N2)、过量有机肥60000 kg/hm^(2) (M2)、有机肥30000 kg/hm^(2)+化肥氮276 kg/hm^(2)(M1N2)、有机肥60000 kg/hm^(2)+化肥氮138 kg/hm^(2) (M2N1)、有机肥60000 kg/hm^(2)+化肥氮276 kg/hm^(2) (M2N2),其中N1和M1为等氮量处理,N2和M2为等氮量处理。于2021年小麦成熟期,取籽粒样测定了籽粒营养与加工品质指标。【结果】适量氮肥显著提高了小麦籽粒Fe、粗蛋白、干湿面筋含量,提高出粉率,且化肥的提升效果优于有机肥。N2显著降低了小麦淀粉含量,影响糊化特性;M2处理小麦籽粒各项品质指标较M1得到提升,糊化特性也得到相应改善。与单施化肥(N1、N2)、有机肥(M1、M2)相比,M2N1显著改善了小麦籽粒品质,M2N1与CK相比分别提高Fe (34.26%)、Zn (19.77%)、出粉率(7.98%)、粗蛋白含量(30.75%)、淀粉含量(12.82%)、峰值黏度(24.93%)、崩解值(14.81%)、回复值(27.64%)。相比于M2N1,M2N2则降低了Zn含量、出粉率、容重、粗蛋白、淀粉含量、糊化特性。相关性分析显示,面粉中支链淀粉、总淀粉、支链淀粉/直链淀粉与峰值黏度、谷值黏度、最终黏度呈极显著正相关,容重、硬度与峰值黏度、谷值黏度呈极显著负相关,直链淀粉与峰值黏度、谷值黏度、最终黏度呈负相关。【结论】单施化肥可以显著提升小麦出粉率、蛋白质和面筋含量等品质,单施有机肥改善小麦面粉淀粉含量和糊化特性的效果更好,有机肥与氮肥配施可同时提升小麦的营养和加工品质,综合各项指标,最有利于小麦品质的施肥措施为年施有机肥60000 kg/hm^(2)+化肥氮138 kg/hm^(2)。

强剪切对单层晶极薄带轧制变形行为的影响

为确定最优的极薄带轧制工艺,本研究深入分析了强剪切对轧制单层晶极薄带微观变形行为和晶体转动演化的影响。采用基于位错滑移机制的晶体塑性有限元模型进行模拟,最大异速比达到1.5。建立了晶粒取向随机分布的单层晶极薄带轧制模型,以探究少晶组织的晶界作用特性。结果表明:强剪切导致单层晶极薄带轧制微观变形和晶体转动表现出显著的局部化。强剪切促进了晶粒的剪切变形,使得晶界的协调变形能力增强。在轧制区施加强剪切变形,可使已启动滑移得到扩展,主滑移带缩窄分散形成新的次滑移带,滑移更加集中和各向异性。变形后晶粒取向主要绕箔材宽度方向发生转动和分散,强剪切使转动角度增大和分散点更加集中稳定。模拟表明强剪切严重影响单层晶极薄带轧制变形的各向异性,进而导致择优取向、滑移局部化以及非均匀应力-应变分布。

110 kV复合绝缘横担结构设计及工程应用研究

为在输电线路中推广复合绝缘横担,以110 kV输电线路改造工程为背景,提出了一种线路用复合绝缘横担设计方法。从复合绝缘横担的大风、覆冰、安装及断线四种工况荷载计算着手,对复合绝缘横担开展结构设计。采用有限元软件建立两拉-两压结构形式的力学分析模型,在四种工况下对横担进行力学计算,通过力学真型实验验证了复合绝缘横担结构的稳定性和安全性。该方法设计的复合绝缘横担满足该线路安全运行要求,并成功挂网多条110 kV输电线路;针对不同线路塔型设计工作量大、生产周期长的问题,开展典型化设计工作是未来发展的趋势。

弹载芯片在强冲击环境下的损伤边界

针对弹载芯片结构在强机械冲击环境下冲击响应谱损伤边界不确定和不准确的问题,将芯片等效为单自由度无阻尼系统并进行冲击响应分析,建立结构应力响应与伪速度冲击响应谱之间的联系;对弹载芯片结构在不同频率范围内冲击载荷下的响应进行分析,构造损伤边界并通过临界加速度信号对冲击响应谱损伤边界进行修正;采用有限元仿真软件对冲击载荷下的弹载芯片结构进行仿真分析,结果表明,临界应力值与修正后损伤边界符合较好。研究结果可以为集成电路在强机械冲击环境下的可靠性设计和失效分析提供理论依据。

基于红黑隔离架构的网络安全设备设计

基于IP(Internet Protocol)技术的天地一体化网络数据传输易受非法攻击,基于IPSec(Internet Protocol Security)的传统网络安全设备采用单主机同时连接内网和外网处理单元进行设计,存在非授权用户通过外网直接访问受保护内网的风险。文中提出了一种基于红黑隔离架构的网络安全设备新方案。方案采用红黑分区的设计理念和基于Linux下IPSec框架的VPN(Virtual Private Network)技术,通过在红区实现传输数据、基于“五元组”的安全保密规则合法性验证以及IPSec ESP(Encapsulating Security Payload)协议封装与解封装变换,在黑区实现ESP封装加密数据的公网收发,在安全服务模块实现根据外部指令完成加密算法动态切换和ESP封装数据的加解密处理,并将安全服务模块作为红区和黑区之间数据交换的通道,达到内网和外网相互隔离且有效保障内网安全的目的。实验结果表明,基于红黑隔离架构的网络安全设备抗攻击能力强,加密算法可更换,在百兆带宽条件下1024 Byte包长加密速率大于50 Mbit·s^(-1)。

基于谱元法的近场地震动空间相干性分析

由于专门用于地震动空间相关性研究的台阵强震记录偏少,基于强震记录统计回归的经验模型发展受限,采用谱元程序SPECFEM2D合成了不同震源机制引起的近场强地震动。通过对地震动场模拟结果进行地震动空间相关性分析,着重比较了不同的震中距对地震动空间相关性的影响,给出了不同震中距对应的相干函数,并得到如下结论:基岩地震动的相干性随震中距的增加而降低;震中距小于或等于15 km时的相干系数大于倾滑断层结果,震中距大于15 km时的相干系数小于倾滑断层结果,但均大于走滑断层结果;基于地震动模拟结果得到的相干性高于基于实测记录的统计结果。

微肥对红锥幼苗生长及光合生理效应的影响

为揭示微肥在红锥育苗中的应用潜力,以红锥幼苗为试验材料,采用叶面喷施的方法,探讨了施用单一或复合性MnCl_(2)·H_(2)O(Mn)、FeSO_(4)·7H_(2)O(Fe)、ZnSO_(4)·7H_(2)O(Zn)、CuSO_(4)·5H_(2)O(Cu)等微肥对苗木生长及光合生理方面的影响。结果表明:在0~50 mg·L^(-1)施用范围内,单一性的Mn、Fe、Zn或Cu微肥对苗高增量均影响显著,但随着施用量增加,各微肥处理下苗高增量的变化趋势不同。其中,在Mn 30~50 mg·L^(-1)、Fe/Zn 30 mg·L^(-1)、Cu 10~20 mg·L^(-1)时,各微肥处理下苗高增量最大。在基于正交法设计的16个复合性微肥处理间,苗高增量差异显著,并以Mn 30 mg·L^(-1)+Fe 20 mg·L^(-1)+Zn 10 mg·L^(-1)+Cu 15 mg·L^(-1)微肥处理(MF14)下苗高的生长效果最好,苗高增量较未施肥对照(CK)处理增加了158.8%。施用复合性微肥对幼苗叶片光合日变化趋势无明显影响,净光合速率(Pn)峰值仍出现在10:00,但在光照最强的12:00—14:00,Pn较CK处理显著增大。与CK与MF14处理相比,在优化的Mn 30 mg·L^(-1)+Fe 20 mg·L^(-1)+Zn 10 mg·L^(-1)+Cu 10 mg·L^(-1)(OM)处理下,地上部分生物量增量与叶绿素含量最高,胞间二氧化碳浓度最低。研究认为,施用复合性微肥能明显改善红锥苗木生长质量与光合能力,并以30 mg·L^(-1)Mn+20 mg·L^(-1)Fe+10 mg·L^(-1)Zn+10 mg·L^(-1)Cu效果最好。

铸牢中华民族共同体意识下民族院校少数民族语言课程思政路径探索与实践

全面推进课程思政建设是落实立德树人根本任务的战略举措,而民族院校语言文字类课程思政建设则是增强大学生中华文化认同和铸牢中华民族共同体意识教育的重要途径。其中,少数民族语言等语言文字类课程蕴含着丰富的铸牢中华民族共同体意识内涵。因此,以少数民族语言课程思政为抓手,紧紧围绕增强民族院校大学生铸牢中华民族共同体意识这一主线,从课程专业知识及其关联内容中挖掘凝练中华民族共同体意识教育思政元素并进行隐性融入设计,在学生的课堂教学、田野调查实习、科研创新项目和毕业论文等方面,全面开展课程思政工作,可以有效地推进高校铸牢中华民族共同体意识教育。