TORSIONAL VIBRATIONS OF A RIGID CIRCULAR PLATE ON SATURATED STRATUM OVERLAYING BEDROCK

The torsional vibration of a rigid plate resting on saturated stratum overlaying bedrock has been analysed for the first time. The dynamic governing differential equations for saturated poroelastic medium are solved by employing the technology of Hankel transform. By taking into account the boundary conditions, the dual integral equations of torsional vibration of a rigid circular plate are established, which are further converted into a Fredholm integral equation of the second kind. Subsequently, the dynamic compliance coefficients of the foundation on saturated stratum, the contact shear stress under the foundation and the angular amplitude of the foundation are evaluated. Numerical results indicate that, when the dimensionless height is bigger than 5, saturated stratum overlaying bedrock can be treated as saturated half space approximately. When the dimensionless frequency is low, the permeability of the soil must be taken into account. Furthermore, when the vibration frequency is a constant, the height of the saturated stratum has a slight effect on the dimensionless contact shear stress under the foundation.

Microstructures and wear resistance of high boron and low carbon ferroalloy using hybrid powder/wire overlaying method

The high boron alloy surfacing layer was easily cracked due to its insufficient toughness by using hybrid powder/ wire overlaying method. In order to explore the cracked mechanism, the microstructures and the wear resistance of the samples with different boron contents were studied. Further, phases analysis, microhardness, macrohardness and wear test were also carried out. The boron content depended microstructures were observed. The precipitation of the Fe2B, Fe3 （ C, B）, Fe23 （C, B）6 were increased with the increase of boron content. It was found that the wear resistance was independent of the macrohardness as the macrohardness increased firstly and then remained steady at -62 HRC. However, the wear resistance was depended on the boron contents, and which increased with the increase of the boron contents. The abrasive loss mechanism changed from plastic deformation removal to fracture removal.

Application of DEM overlaying technique in surface subsidence identification─a case study in Ruqigou coal mining area of Ningxia,China

Subsidence occurred in many parts of the world. particularly in densely populated deltaic regions, causing extremely expensive damage. It can be resulted from natural causes. man-made induced causes, or other mixed causes. For identifying surface subsidence, many techniques have been employed, for example, geodetic monitoring, airborne laser subsidence measurement system,differential S.A.R., interferometry DGPS, and satellite radar measurements. However. all these methods require large time span and a large amount of field work. With the development of GIS techniques, identification of surface subsidence is becoming a relative easy problem. Ruqigou coal mining area was selected as a case study to identify the surface subsidence with DEM (digital elevation model) overlaying techniques. The result shows that DEM overlaying technique is a very useful method on surface subsidence identification. The accuracy of the results are largely dependent on the precision of the data-input.

Study on the rupture characteristics of the overlaying soil with soft interlayer due to fault bedrock dislocation

In this paper, the rupture characteristics of the overlaying soil with soft interlayer were studied by plane-strain finite element method. From the results, it can be shown that the existence of soft layer separates rupture process of the overlaying soil into two phases. The depth of a buried soft interlayer will influence the rupture process and the rupture range of the overlaying soil. The deeply buried soft interlayer would bring about a wider range of surface failure. In addition, the thickness of the soft layer also has effect on the rupture process and rupture range of the overlaying soil.

Stability Assessment of Open Stope under Overlaying Mined-Out Regions at Modi Taung Gold Mine, Myanmar

Stability assessment is one of the most important issues in mining ground control. Mine development and/or production instability can cause production delay, loss of reserves, as well as injury to miners. Within the scope of this study, a series of open stope’s instability under the influence of overlaying mined-out regions were carried out with different mining scenarios at Modi Taung gold mine which is operated by National Prosperity Gold Production Group Limited (NPGPGL) in Myanmar. NPGPGL has been developing stopes up to 150 m from the surface at Shwesin vein system, and the mining activities are going to continue to deeper levels to fulfill the ore mineral supply. Creating a new stope opening under overlaying mined-out regions is not easy considering the instability of mined-out regions can affect the stope. The instability of new stope opening is not only due to its own induced stress but also the strong influence by the mined-out regions situated on upper part of the stope. Therefore, the understandings of ground behaviors and failure mechanisms of new stope opening due to the influence of overlaying mined-out regions are paramount to be studied. This paper describes in detail the strength factor and failure zones under the overlaying mined-out regions with different mine conditions by using numerical simulations, 3D finite difference software (FLAC 3D).

Natural overlaying behaviors push the limit of planar cyclic deformation performance in few-layer MoS_(2) nanosheets

As a typical two-dimensional(2D)transition metal dichalcogenides(TMDCs)material with nonzero band gap,MoS_(2)has a wide range of potential applications as building blocks in the field of nanoelectronics.The stability and reliability of the corresponding nanoelectronic devices depend critically on the mechanical performance and cyclic reliability of 2D MoS_(2).Although an in situ technique has been used to analyze the mechanical properties of 2D materials,the cyclic mechanical behavior,that is,fatigue,remains a major challenge in the practical application of the devices.This study was aimed at analyzing the planar cyclic performance and deformation behavior of three-layer MoS_(2)nanosheets(NSs)using an in situ transmission electron microscopy(TEM)variable-amplitude uniaxial low-frequency and cyclic loading-unloading tensile acceleration test.We also elucidated the strengthening effect of the natural overlaying affix fragments(other external NSs)or wrinkle folds(internal folds from the NS itself)on cycling performances and service life of MoS_(2)NSs by delaying the whole process of fatigue crack initiation,propagation,and fracture.The results have been confirmed by molecular dynamics(MDs)simulations.The overlaying enhancement effect effectively ensures the long-term reliability and stability of nanoelectronic devices made of few-layer 2D materials.

面向未来低碳道路养护的超薄罩面功能性研究综述

Highway maintenance mileage reached 5.25 million kilometers in China by 2021.Ultra-thin overlay is one of the most commonly used maintenance technologies,which can significantly enhance the economic and environmental benefits of pavements.To promote the low-carbon development of ultrathin overlays,this paper mainly studied the mechanism and influencing factors of several ultra-thin overlay functions.Firstly,the skid resistance,noise reduction,rutting resistance,and crack resistance of ultrathin overlays were evaluated.The results indicated that the high-quality aggregates improved the skid and rutting resistance of ultra-thin overlay by 5%-20%.The optimized gradations and modified binders reduced noise of ultra-thin overlay by 0.4-6.0 dB.The high viscosity modified binders improved the rutting resistance of ultra-thin overlay by about 10%-130%.Basalt fiber improved the cracking resistance of ultra-thin overlay by more than 20%.Due to the thinner thickness and better road performance,the performance-based engineering cost of ultra-thin overlay was reduced by about 30%-40%compared with conventional overlays.Secondly,several environmentally friendly functions of ultra-thin overlay were investigated,including snow melting and deicing,exhaust gas purification and pavement cooling.The lower thickness of ultra-thin overlay was conducive to the diffusion of chloride-based materials to the pavement surface.Therefore,the snow melting effect of self-ice-melting was better.In addition,the ultra-thin overlay mixture containing photocatalytic materials could decompose 20%-50%of the exhaust gas.The colored ultra-thin overlay was able to reduce the temperature of the pavement by up to 8.1℃.The temperature difference between the upper and lower surfaces of the ultra-thin overlay containing thermal resistance materials could reach up to 12.8℃.In addition,numerous typical global engineering applications of functional ultra-thin overlay were summarized.This review can help better understand the functionality of ultra-thin overlays and promote the realization of future multi-functional and low-carbon road maintenance.

适配融媒体云平台的SDN技术应用探讨

国家广播电视总局在关于《广播电视融媒体云平台的建设技术实施指南》中提出,为了降低复杂度,宜使用软件定义网络(SDN),通过集中的控制器集群实现VXLAN的控制平面,使得网络部署维护更简单,运行更稳定。本文重点对SDN技术特点和应用进行剖析,并提出设计实施参考建议。

Prevention of carbon migration in 9% Cr/CrMoV dissimilar welded joint by adding tungsten inert gas overlaying layer

High chromium （9-12% Cr） steels with excellent heat resistance and CrMoV steels with good toughness were potential candidates for combined rotor for steam turbine operated over 620℃. Two welding techniques were used to fabricate 9% Cr and CrMoV dissimilar welded joint. The results show that the carbon migration only appears in the specimen using narrow gap submerged arc welding （NG-SAW） technique, yet it can be effectively prevented by adding tungsten inert gas （TlG） overlaying process before the NG-SAW. The carbon migration occurred in NG-SAW resulting from the sharp transition of the strong carbide-forming element Cr between the weld （-2.7 wt%） and the base metal （- 9 wt%）. On the contrary, the application of TIG overlaying layers can promote the diffusion of Cr element, and therefore result in its much smaller concentration gradient. That is to say, a gentle transition zone of Cr element can be created among the SAW weld, TIG overlaying layers and the base metal, which effectively prevents the carbon migration and therefore produces a decreased carbon concentration adjacent to the fusion line.

Damage Mechanism of Ultra-thin Asphalt Overlay(UTAO) based on Discrete Element Method

Aiming to analyze the damage mechanism of UTAO from the perspective of meso-mechanical mechanism using discrete element method(DEM),we conducted study of diseases problems of UTAO in several provinces in China,and found that aggregate spalling was one of the main disease types of UTAO.A discrete element model of UTAO pavement structure was constructed to explore the meso-mechanical mechanism of UTAO damage under the influence of layer thickness,gradation,and bonding modulus.The experimental results show that,as the thickness of UTAO decreasing,the maximum value and the mean value of the contact force between all aggregate particles gradually increase,which leads to aggregates more prone to spalling.Compared with OGFC-5 UTAO,AC-5 UTAO presents smaller maximum and average values of all contact forces,and the loading pressure in AC-5 UTAO is fully diffused in the lateral direction.In addition,the increment of pavement modulus strengthens the overall force of aggregate particles inside UTAO,resulting in aggregate particles peeling off more easily.The increase of bonding modulus changes the position where the maximum value of the tangential force appears,whereas has no effect on the normal force.

Modelling of debris-flow susceptibility and propagation: a case study from Northwest Himalaya

The geological and geographical position of the Northwest Himalayas makes it a vulnerable area for mass movements particularly landslides and debris flows. Mass movements have had a substantial impact on the study area which is extending along Karakorum Highway(KKH) from Besham to Chilas. Intense seismicity, deep gorges, steep terrain and extreme climatic events trigger multiple mountain hazards along the KKH, among which debris flow is recognized as the most destructive geohazard. This study aims to prepare a field-based debris flow inventory map at a regional scale along a 200 km stretch from Besham to Chilas. A total of 117 debris flows were identified in the field, and subsequently, a point-based debris-flow inventory and catchment delineation were performed through Arc GIS analysis. Regional scale debris flow susceptibility and propagation maps were prepared using Weighted Overlay Method(WOM) and Flow-R technique sequentially. Predisposing factors include slope, slope aspect, elevation, Topographic Roughness Index(TRI), Topographic Wetness Index(TWI), stream buffer, distance to faults, lithology rainfall, curvature, and collapsed material layer. The dataset was randomly divided into training data(75%) and validation data(25%). Results were validated through the Receiver Operator Characteristics(ROC) curve. Results show that Area Under the Curve(AUC) using WOM model is 79.2%. Flow-R propagation of debris flow shows that the 13.15%, 22.94%, and 63.91% areas are very high, high, and low susceptible to debris flow respectively. The propagation predicated by Flow-R validates the naturally occurring debris flow propagation as observed in the field surveys. The output of this research will provide valuable input to the decision makers for the site selection, designing of the prevention system, and for the protection of current infrastructure.

Enhancing transjugular intrahepatic portosystemic shunt procedure efficiency with digital subtraction angiography image overlay technology in esophagogastric variceal bleeding

BACKGROUND Transjugular intrahepatic portosystemic shunt(TIPS)is a pivotal intervention for managing esophagogastric variceal bleeding in patients with chronic hepatic schistosomiasis.AIM To evaluate the efficacy of digital subtraction angiography image overlay tech-nology(DIT)in guiding the TIPS procedure.METHODS We conducted a retrospective analysis of patients who underwent TIPS at our hospital,comparing outcomes between an ultrasound-guided group and a DIT-guided group.Our analysis focused on the duration of the portosystemic shunt puncture,the number of punctures needed,the total surgical time,and various clinical indicators related to the surgery.RESULTS The study included 52 patients with esophagogastric varices due to chronic hepatic schistosomiasis.Results demonstrated that the DIT-guided group expe-rienced significantly shorter puncture times(P<0.001)and surgical durations(P=0.022)compared to the ultrasound-guided group.Additionally,postoperative assessments showed significant reductions in aspartate aminotransferase,B-type natriuretic peptide,and portal vein pressure in both groups.Notably,the DIT-guided group also showed significant reductions in total bilirubin(P=0.001)and alanine aminotransferase(P=0.023).CONCLUSION The use of DIT for guiding TIPS procedures highlights its potential to enhance procedural efficiency and reduce surgical times in the treatment of esophagogastric variceal bleeding in patients with chronic hepatic schistoso-miasis.

基于云原生网络多态协同的技术研究

云原生网络是容器云的核心,部署在公有云、私有数据中心或混合云。不同基础设施环境导致底层网络存在差异,会对安全管控造成挑战。不同的云原生网络方案具有不同的容器适配成本,如NAT、负载均衡、低延时通信。CNI开源项目分为Overlay和Underlay两种流派:Overlay通过隧道技术构建独立容器网络,利用NAT实现通信转换,适用大多数场景,但对传统主机直用适配成本高;Underlay直接使用主机网络,限制较多但性能好、对传统主机应用的适配成本低。因此,设计一种基于开源CNI项目的多种Underlay CNI协同解决容器集群通信问题。实践表明优化设计可降低30%网络运维工作量。解决Underlay场景下IP分配、多网卡路由、宿主机连通性等问题,加强各Underlay CNI项目。协同多种CNI确保了集群网络连通性,利用物理网卡可降低通信延时约30%。

基于云网POP的差异化云网络建设方案探讨

国家新型基础设施建设给各运营商带来了新的发展契机,纷纷布局以云网融合为特征的数据中心建设。本文重点分析运营商如何打造云网一体化网络服务提供点(Point of Presence,POP),满足不同客户差异化的入云或云间组网需求,实现云网能力端到端快速贯通,云资源池快速规模化部署,缩短云资源池或数据中心接入网络的建设和开通周期。

SRv6技术在SD-WAN专线上的应用研究及现网验证

传统软件定义广域网络(software-defined wide area network,SD-WAN)通过虚拟扩展局域网(virtual extensible local area network,VXLAN)/通用路由封装(generic routing encapsulation,GRE)/互联网安全协议(internet protocol security,IPSec)等隧道技术建立Overlay虚拟网络连接,网络质量受限于Underlay网络。为解决传统SD-WAN技术无法感知网络底层业务特性的问题,对SRv6协议进行研究,提出基于SRv6技术的新一代SD-WAN技术,并基于现网搭建测试环境进行验证,以期为相关人员提供参考。

网络5.0业务网架构研究

随着物联网、工业互联网等新兴业务的迅猛涌现,网络的确定性、安全性和资源调度等方面面临着重大挑战。然而,现有网络是“尽力而为”的模式,只管控网络资源,不管控业务或应用连接。网络5.0针对以上问题,提出了“创新协议、确定性网络、内生安全可信、自组织网络、算力网络”等解决方案,为未来全业务承载提供承载底座。网络5.0在架构层面,需解决现有业务承载的OTT方式,即业务的应用层与网络层的控制与匹配不足的问题。首先,分析了网络5.0业务网的4个关键创新动机;其次,创新性地提出了新的业务网架构,通过在现有网络承载层上叠加业务核心层,使网络具备动态的业务感知、业务连接、资源匹配和连接管控能力,内生解决了网络业务/应用Underlay+Overlay协同的确定性承载,又开创了基于用户体验和应用感知的新型业务和精细化网络运营模式;最后,列出了超算快线和不间断直播两个典型业务场景,为未来的网络研究方向提供了强有力的线索。

云平台框架下网络节点数据安全传输技术

在传统的数据传输过程中,由于缺乏对节点之间关联关系的分析,导致数据的丢包率较高。针对此问题,提出了云平台框架下网络节点数据安全传输技术。利用Overlay结构在连接组网各个接口中的作用,构建以其为基础并包含多个节点数据的网络拓扑抽象模型。在数据传输阶段分析传输数据的资源需求,然后利用网络的允许时延,调整网络拓扑模型中相邻阶段的运行频率,使得数据接口以相同的频率执行数据传输,保障数据的安全性。测试结果显示,云平台框架下网络节点数据传输技术的丢包率始终稳定在10.0%以内。

基于可视化学科多样性测度指数和主题模型的领域学科交叉知识图谱构建--以纳米科技领域为例

[目的/意义]基于文献计量学和文本挖掘方法探索与某领域相关的学科交叉知识图谱的新思路。[方法/过程]提出可视化学科多样性测度指数和主题模型的领域学科交叉知识图谱研究框架,基于Science Overlay Map和嵌入领域本体的LDAvis进行领域学科交叉知识图谱的构建,并以纳米科技领域为例,验证学科交叉知识图谱研究框架的有效性和适用性。[结果/结论]基于Science Overlay Map的领域学科交叉科学地图,从全学科的角度展示纳米科技领域与其他学科的交叉情况,基于LDAvis结合领域本体的学科交叉主题交互图则聚焦具体的学科交叉主题和主题之间的相互关系,二者的结合可以从宏观和微观上更清晰地把握纳米科技领域与其他学科的交叉情况。本研究可以弥补学科交叉主题识别结果不容易被解释的局限性,为领域学科交叉知识图谱研究提供了一种解决方案的新视角。

基于响应面法的不同配比沥青混凝土性能平衡优化设计

采用4种不同标号沥青及3种油石比制备12组沥青混合料,通过车辙试验、Overlay Tester(OT)试验以及动态模量试验评价其高温性能、低温性能和力学性能。采用响应面法对不同沥青混合料的高温性能、低温抗裂性能、疲劳性能和力学性能进行平衡性分析。结果表明,采用高油石比和低标号沥青可显著提高混合料的高温性能及力学性能且具有一定的抗裂性能,根据性能叠加图推荐了满足高模量沥青混凝土高温性能、抗裂性能与力学性能标准的沥青标号与油石比范围,其结果对于合理进行不同标号沥青混凝土配合比设计具有较大的参考价值。

基于SD-WAN的企业专线应用与实践

为满足各业务节点灵活的网络访问需求,对网络建设和运维提出了更高的要求,中国广电山东网络有限公司青岛市分公司探索了基于SD-WAN技术的新型企业专线建设,并根据实际应用场景进行了组网实践,为更多中小型企业广域网络系统的组网提供了借鉴和参考。