Dissolution of WO_(3) modified with IrO_(x) overlayers during photoelectrochemical water splitting

WO_(3),an abundant transition metal semiconductor,is one of the most discussed materials to be used as a photoanode in photoelectrochemical water-splitting devices.The photoelectrochemical properties,such as photoactivity and selectivity of WO_(3) in different electrolytes,are already well understood.However,the understanding of stability,one of the most important properties for utilization in a commercial device,is still in the early stages.In this work,a photoelectrochemical scanning flow cell coupled to an inductively coupled plasma mass spectrometer is applied to determine the influence of co-catalyst overlayers on photoanode stability.Spray-coatedWO_(3) photoanodes are used as a model system.Iridium is applied to the electrodes by atomic layer deposition in controlled layer thickness,as determined by ellipsometry and x-ray photoelectron spectroscopy.Photoactivity of the iridium-modified WO_(3) photoanodes decreases with increasing iridium layer thickness.Partial blocking of the WO_(3) surface by iridium is proposed as the main cause of the decreased photoelectrochemical performance.On the other hand,the stability of WO_(3) is notably increased even in the presence of the thinnest investigated iridium overlayer.Based on our findings,we provide a set of strategies to synthesize nanocomposite photoelectrodes simultaneously possessing high photoelectrochemical activity and photostability.

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。

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.

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.

Unravelling the role of the combined effect of metallic charge transfer channel and SiO_(x) overlayer in the Zr/Si-Fe_(2)O_(3):Au:SiO_(x) nanorod arrays to boost photoelectrochemical water splitting

Hematite(α-Fe_(2)O_(3)) based photoanodes have been extensively studied due to various intriguing features that make them viable candidates for a photoelectrochemical(PEC) water splitting photoanode.Herein,we propose a Zr-doped Fe_(2)O_(3) photoanode decorated with facilely spin-coated Au nanoparticles(NPs) and microwave-assisted attached Si co-doping in conjunction with a SiO_(x) overlayer that displayed a remarkable photocurrent density of 2.01 mA/cm^(2) at 1.23 V vs.RHE.The kinetic dynamics at the photoelectrode/-electrolyte interface was examined by employing systematic electrochemical investigations.The Au NPs played a dual role in increasing PEC water splitting.First,the Schottky interface that was formed between Au NPs and Zr-Fe_(2)O_(3) lectrode ensured the prevention of electron flow from the photoanode to the metal,increasing the number of available charges as well as suppressing surface charge recombination.Second,Au extracted photoholes from the bulk of the Zr-Fe_(2)O_(3) and transported them to the outer SiO_(x) overlayer,while the SiO_(x) overlayer efficiently collected the photoholes and promoted the hole injection into the electrolyte.Further,Si co-doping enhanced bulk conductivity by reducing bulk charge transfer resistance and improving charge carrier density.This study outlines a technique to design a metallic charge transfer path with an overlayer for solar energy conversion.

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。

Growth,coalescence,and etching of two-dimensional overlayers on metals modulated by near-surface Ar nanobubbles

The synthesis of high-quality ultrathin overlayers is critically dependent on the surface structure of substrates,especially involving the overlayer–substrate interaction.By using in situ surface measurements,we demonstrate that the overlayer–substrate interaction can be tuned by doping near-surface Ar nanobubbles.The interfacial coupling strength significantly decreases with near-surface Ar nanobubbles,accompanying by an“anisotropic to isotropic”growth transformation.On the substrate containing near-surface Ar,the growth front crosses entire surface atomic steps in both uphill and downhill directions with no difference,and thus,the morphology of the two-dimensional(2D)overlayer exhibits a round-shape.Especially,the round-shaped 2D overlayers coalesce seamlessly with a growth acceleration in the approaching direction,which is barely observed in the synthesis of 2D materials.This can be attributed to the immigration lifetime and diffusion rate of growth species,which depends on the overlayer–substrate interaction and the surface catalysis.Furthermore,the“round to hexagon”morphological transition is achieved by etching-regrowth,revealing the inherent growth kinetics under quasi-freestanding conditions.These findings provide a novel promising way to modulate the growth,coalescence,and etching dynamics of 2D materials on solid surfaces by adjusting the strength of overlayer–substrate interaction,which contributes to optimization of large-scale production of 2D material crystals.

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SDN的医疗数据中心网络架构研究

随着网络规模不断增大,医疗数据中心烦琐和低效等问题日益凸显,SDN(Software Defined Network)的网络架构正好能解决这些问题。其通过核心技术OpenFlow分离控制层和数据层,实现对网络流量的灵活控制,使数据中心网络更加高效、便捷和智能。由于SDN的开放性,使得网络架构无须依赖底层网络设备,屏蔽了设备差异,用户也可以自定义网络规则,让网络更加灵活和智能。相比传统网络架构,SDN为网络管理提供了更多的便捷性和可操作性。

Remote sensing monitoring of the recent rapid increase in cultivation activities and its effects on desertification in the Mu Us Desert, China

The recent ecological improvement in the Mu Us Desert of China, largely attributed to large-scale afforestation projects, has created new opportunities for cultivation activities. However, the subsequent rapid increase in reclamation on desertification land and its impact on desertification have raised concerns. In this study, we first extracted data on cultivated land and desertification land in 1975,1990, 2000, 2005, 2010, 2015, and 2020 through the human-computer interaction visual interpretation method. By overlaying the cultivated land dynamics and desertification land, we subsequently explored the effect of cultivation activities on desertification in the Mu Us Desert during the six periods from 1975 to 2020(1975–1990, 1990–2000, 2000–2005, 2005–2010, 2010–2015, and 2015–2020). The results showed that cultivated land in the Mu Us Desert showed a fluctuating and increasing trend from 3769.26 km~2 in 1975 to 4865.73 km~2 in 2020, with 2010 as the turning point for the recent rapid increase. The main contributors included the large and regular patches distributed in Yuyang District and Shenmu of Shaanxi Province, and relatively smaller patches concentrated in Inner Mongolia Autonomous Region. The increased cultivated land from the reclamation on desertification land was dominated by moderate and severe desertification lands, and the decreased cultivated land that was transferred into desertification land as abandoned cultivated land was dominated by slight and moderate desertification lands. The effect of cultivation activities on desertification reversal(average area proportion of 10.61% for reversed desertification land) was greater than that of the development of desertification(average area proportion of 5.82% for developed desertification land). Nevertheless, compared to reversed desertification land,both the significant increase of developed desertification land during the periods of 2000–2005 and 2005–2010 and the insignificant decrease during the periods of 2005–2010, 2010–2015, and 2015–2020 implied a potential remobilization risk. Therefore, this study provides a significant theoretical reference for the formulation of ecological restoration projects and regional macroeconomic development policies by considering the influence of cultivation activities, to ensure the overall environmental stability and sustainability in desertification land where reclamation and abandonment activities have taken place.

Generation of Low-Delay and High-Stability Multicast Tree

Delay and stability are two key factors that affect the performance of multicast data transmission in a network.However,current algorithms of tree generation hardly meet the requirements of low delay and high sta-bility simultaneously.Given a general network,the generation algorithm of a multicast tree with minimum delay and maximum stability is an NP-hard problem,without a precise and efficient algorithm.To address these challenges,this paper studies the generation of low-delay and high-stability multicast trees under the model of spanning tree based on stability probability,degree-constrained,edge-weighted for multicast(T-SDE).A class of algorithms was proposed which creates the multicast tree greedy on the ratio of fan-out to delay(RFD)and probability of stability of terminal to obtain a high performance in multicast.The proposed algorithms greedily select terminals with a large RFD and a high probability of stability as forwarding nodes in the generation of the multicast tree,where the larger RFD and higher stability of upstream nodes are beneficial to achieve a low transmission delay and high stability in multicast.The proposed RFD can be compatible with the original model,which can take advantage of network connectivity during the generation of a multicast tree.This paper carries out simulation experiments on Matlab R2016b to measure the performance of the proposed algorithm.Experimental results show that the proposed algorithm can provide a smaller height,higher stability,and a lower transmission delay of the resulting multicast tree than other solutions.The spanning tree of the proposed algorithms can support low transmission delay and high stability in multicast transmission.

Evaluation of land suitability for Moringa oleifera tree cultivation by using Geospatial technology:The case of Dhidhessa Catchment,Abay Basin,Ethiopia

Land suitability analysis of Moringa oleifera tree cultivation is important to enhance its product,as the demand forthis tree for medicinal values and food sources is increasing worldwide.Therefore,this study aimed to assess suitableland for Moringa oleifera tree cultivation by using the integration of multi-criteria evaluation with geospatialtechnologies in the Dhidhessa catchment,western Ethiopia.Five parameters,namely:slope,land use and landcover(LULC),soil texture,land surface temperature,and rainfall data,were used in this study.The land suitabilityevaluation of Moringa oleifera is classified into three classes as highly suitable,moderately suitable,and notsuitable.The results revealed that,about 344.4 km2(12.2%)of the area is categorized into highly suitable,and2343.7 km2(83%)is moderately suitable for Moringa tree,whereas,137.2 km2(4.9%)is categorized as notsuitable for Moringa oleifera tree cultivation.Hence,based on the finding of the study,we suggested that farmers andother stakeholders can cultivate Moringa oleifera trees in the Dhidhessa catchment.

Determination of groundwater potential distribution in Kulfo-Hare watershed through integration of GIS, remote sensing, and AHP in Southern Ethiopia

Identification of groundwater potential areas(GPA)is important in regions facing surface water scarcity,as it assists in effective planning and utilization of groundwater for various purposes.This study employs the methods of remote sensing(RS),geographic information system(GIS)model,and analytical hierarchy process(AHP),multi-criteria decision analysis(MCDA)to locate and map the prospective groundwater areas in the Kulfo-Hare watershed.Seven significant groundwater influencing factors were selected for the determination of groundwater potential in the area:Geology,land use/land cover(LULC),soil,rainfall,slope,drainage density,and lineament density.By applying a five-class classification scheme(very low,low,moderate,high,and very high),the GIS models were used to define the distribution of groundwater potential areas in terms of area coverage(km^(2)),percentage and mapping.The results show that the groundwater potential(GWP)distribution in the research region is as follows:9.7%(6035.9 ha)classified as very high GWP,29.6%(18606 ha)classified as high,24.5%(15245 ha)classified as moderate,18.1%(11431 ha)as low and 18.1%(11492 ha)very low GWP,on the basis of the weighted overlay evaluation.Although a few regions are identifies as extremely low GWP,most of the study area is characterized by very high to moderate GWP.These findings provide valuable insight for sustainable groundwater planning by the government bodies,decision-makers,and private sectors.

A conformal titanyl phosphate amorphous overlayer for enhancing photoelectrochemical hydrogen peroxide production

Photoelectrochemical(PEC)H_(2)O_(2)production through water oxidation reaction(WOR)is a promising strategy,however,designing highly efficient and selective photoanode materials remains challenging due to competitive reaction pathways.Here,for highly enhanced PEC H_(2)O_(2)production,we present a conformal amorphous titanyl phosphate(a-TP)overlayer on nanoparticulate TiO_(2)surfaces,achieved via lysozyme-molded in-situ surface reforming.The a-TP overlayer modulates surface adsorption energies for reaction intermediates,favoring WOR for H_(2)O_(2)production over the competing O_(2)evolution reaction.Our density functional theory calculations reveal that a-TP/TiO_(2)exhibits a substantial energy uphill for the O·*formation pathway,which disfavors O_(2)evolution but promotes H_(2)O_(2)production.Additionally,the a-TP overlayer strengthens the built-in electric field,resulting in favorable kinetics.Consequently,a-TP/TiO_(2)exhibits 3.7-fold higher Faraday efficiency(FE)of 63%at 1.76 V vs.reversible hydrogen electrode(RHE)under 1 sun illumination,compared to bare TiO_(2)(17%),representing the highest FE among TiO_(2)-based WOR H_(2)O_(2)production systems.Employing the a-TP overlayer constitutes a promising strategy for controlling reaction pathways and achieving efficient solar-to-chemical energy conversion.