Modulating charge separation and transfer for high-performance photoelectrodes via built-in electric field

Constructing a built-in electric field has emerged as a key strategy for enhancing charge separation and transfer,thereby improving photoelectrochemical performance.Recently,considerable efforts have been devoted to this endeavor.This review systematically summarizes the impact of built-in electric fields on enhancing charge separation and transfer mechanisms,focusing on the modulation of built-in electric fields in terms of depth and orderliness.First,mechanisms and tuning strategies for built-in electric fields are explored.Then,the state-of-the-art works regarding built-in electric fields for modulating charge separation and transfer are summarized and categorized according to surface and interface depth.Finally,current strategies for constructing bulk built-in electric fields in photoelectrodes are explored,and insights into future developments for enhancing charge separation and transfer in high-performance photoelectrochemical applications are provided.

Theoretical Framework for a Polymorphic Network Environment

The question of whether an ideal network exists with global scalability in its full life cycle has always been a first-principles problem in the research of network systems and architectures.Thus far,it has not been possible to scientifically practice the design criteria of an ideal network in a unimorphic network system,making it difficult to adapt to known services with clear application scenarios while supporting the ever-growing future services with unexpected characteristics.Here,we theoretically prove that no unimorphic network system can simultaneously meet the scalability requirement in a full cycle in three dimensions—the service-level agreement(S),multiplexity(M),and variousness(V)—which we name as the“impossible SMV triangle”dilemma.It is only by transforming the current network development paradigm that the contradiction between global scalability and a unified network infrastructure can be resolved from the perspectives of thinking,methodology,and practice norms.In this paper,we propose a theoretical framework called the polymorphic network environment(PNE),the first principle of which is to separate or decouple application network systems from the infrastructure environment and,under the given resource conditions,use core technologies such as the elementization of network baselines,the dynamic aggregation of resources,and collaborative software and hardware arrangements to generate the capability of the“network of networks.”This makes it possible to construct an ideal network system that is designed for change and capable of symbiosis and coexistence with the generative network morpha in the spatiotemporal dimensions.An environment test for principle verification shows that the generated representative application network modalities can not only coexist without mutual influence but also independently match well-defined multimedia services or custom services under the constraints of technical and economic indicators.

Facile Synthesis of FePS3 Nanosheets@MXene Composite as a High-Performance Anode Material for Sodium Storage

Searching for advanced anode materials with excellent electrochemical properties in sodium-ion battery is essential and imperative for next-generation energy storage system to solve the energy shortage problem.In this work,two-dimensional(2D)ultrathin FePS3 nanosheets,a typical ternary metal phosphosulfide,are first prepared by ultrasonic exfoliation.The novel 2D/2D heterojunction of FePS3 nanosheets@MXene composite is then successfully synthesized by in situ mixing ultrathin MXene nanosheets with FePS3 nanosheets.The resultant FePS3 nanosheets@MXene hybrids can increase the electronic conductivity and specific surface area,assuring excellent surface and interfacial charge transfer abilities.Furthermore,the unique heterojunction endows FePS3 nanosheets@MXene composite to promote the diffusion of Na^+ and alleviate the drastic change in volume in the cyclic process,enhancing the sodium storage capability.Consequently,the few-layered FePS3 nanosheets uniformly coated by ultrathin MXene provide an exceptional reversible capacity of 676.1 mAh g^−1 at the current of 100 mA g^−1 after 90 cycles,which is equivalent to around 90.6% of the second-cycle capacity(746.4 mAh g^−1).This work provides an original protocol for constructing 2D/2D material and demonstrates the FePS3@MXene composite as a potential anode material with excellent property for sodium-ion batteries.

EARS: Intelligence-Driven Experiential Network Architecture for Automatic Routing in Software-Defined Networking

Software-Defined Networking(SDN)adapts logically-centralized control by decoupling control plane from data plane and provides the efficient use of network resources.However,due to the limitation of traditional routing strategies relying on manual configuration,SDN may suffer from link congestion and inefficient bandwidth allocation among flows,which could degrade network performance significantly.In this paper,we propose EARS,an intelligence-driven experiential network architecture for automatic routing.EARS adapts deep reinforcement learning(DRL)to simulate the human methods of learning experiential knowledge,employs the closed-loop network control mechanism incorporating with network monitoring technologies to realize the interaction with network environment.The proposed EARS can learn to make better control decision from its own experience by interacting with network environment and optimize the network intelligently by adjusting services and resources offered based on network requirements and environmental conditions.Under the network architecture,we design the network utility function with throughput and delay awareness,differentiate flows based on their size characteristics,and design a DDPGbased automatic routing algorithm as DRL decision brain to find the near-optimal paths for mice and elephant flows.To validate the network architecture,we implement it on a real network environment.Extensive simulation results show that EARS significantly improve the network throughput and reduces the average packet delay in comparison with baseline schemes(e.g.OSPF,ECMP).

ESMD-Flow: An Intelligent Flow Forwarding Scheme with Endogenous Security Based on Mimic Defense in Space-Air-Ground Integrated Network

The Space-Air-Ground Integrated Network(SAGIN) realizes the integration of space, air,and ground networks, obtaining the global communication coverage.Software-Defined Networking(SDN) architecture in SAGIN has become a promising solution to guarantee the Quality of Service(QoS).However, the current routing algorithms mainly focus on the QoS of the service, rarely considering the security requirement of flow. To realize the secure transmission of flows in SAGIN, we propose an intelligent flow forwarding scheme with endogenous security based on Mimic Defense(ESMD-Flow). In this scheme, SDN controller will evaluate the reliability of nodes and links, isolate malicious nodes based on the reliability evaluation value, and adapt multipath routing strategy to ensure that flows are always forwarded along the most reliable multiple paths. In addition, in order to meet the security requirement of flows, we introduce the programming data plane to design a multiprotocol forwarding strategy for realizing the multiprotocol dynamic forwarding of flows. ESMD-Flow can reduce the network attack surface and improve the secure transmission capability of flows by implementing multipath routing and multi-protocol hybrid forwarding mechanism. The extensive simulations demonstrate that ESMD-Flow can significantly improve the average path reliability for routing and increase the difficulty of network eavesdropping while improving the network throughput and reducing the average packet delay.

A Safe and Reliable Heterogeneous Controller Deployment Approach in SDN

Software-Defined Networking(SDN)provides flexible and global network management by decoupling control plane from data plane,and multiple controllers are deployed in the network in a logically centralized and physically distributed way.However,the existing approaches generally deploy the controllers with the same type in the network,which easily causes homogeneous controller common-mode fault.To this end,this paper proposes heterogeneous controller deployment in the SDN,considering the different types of controllers and relevant criteria(e.g.,delay,control link interruption rate,and controller fault rate).Then,we introduce a Safe and Reliable Heterogeneous Controller Deployment(SRHCD)approach,consisting of two stages.Stage 1 determines the type and the number of heterogeneous controllers required for the SDN network based on the dynamic programming.Stage 2 divides the SDN network into multiple subnets by k-means algorithm and improves the genetic algorithm to optimize the heterogeneous controller deployment in these SDN subnets to ensure reliable switch-controller communications.Finally,the simulation results show that the proposed approach can effectively reduce the control plane fault rate and increase the attack difficulties.Besides,the switch-controller delay has been lowered by 16.5%averagely.

All-Climate Aluminum-Ion Batteries Based on Binder-Free MOF-Derived FeS_(2)@C/CNT Cathode

Aluminum-ion batteries(AIBs)are promising next-generation batteries systems because of their features of low cost and abundant aluminum resource.However,the inferior rate capacity and poor all-climate performance,especially the decayed capacity under low temperature,are still critical challenges toward high-specific-capacity AIBs.Herein,we report a binder-free and freestanding metal-organic framework-derived FeS_(2)@C/carbon nanotube(FeS_(2)@C/CNT)as a novel all-climate cathode in AIBs working under a wide temperature window between−25 and 50℃ with exceptional flexibility.The resultant cathode not only drastically suppresses the side reaction and volu-metric expansion with high capacity and long-term stability but also greatly enhances the kinetic process in AIBs with remarkable rate capacity(above 151 mAh g^(−1) at 2 A g^(−1))at room temperature.More importantly,to break the bottleneck of the inherently low capacity in graphitic material-based all-climate AIBs,the new hierarchical conductive composite FeS_(2)@C/CNT highly promotes the all-climate performance and delivers as high as 117 mAh g^(−1) capacity even under−25°C.The well-designed metal sulfide electrode with remarkable performance paves a new way toward all-climate and flexible AIBs.

Recent Advances in Printed Thin-Film Batteries

The rapidly increasing demand for wearable electronic devices has motivated research in low-cost and flexible printed batteries with diverse form factors and architectures.In the past,technological achieve-ments in the field have been emphasized,overlooking the industrial and market requirements.However,different applications require different battery chemistries and formats,that greatly impacts the manu-facturing process and competition landscape.These chemistries and formats should therefore be selected carefully to maximize the chances for commercial success.As some of these technologies are starting to be marketed for portable electronics,there is a pressing need to evaluate different printing technologies and compare them in terms of the processing constraints and product requirements of specific electronic devices.By evaluating the intrinsic strengths and current limitations of printed battery technologies,development pathways can be prioritized,and potential bottlenecks can be overcome to accelerate the path to market.

Closer:Scalable Load Balancing Mechanism for Cloud Datacenters

Cloud providers(e.g.,Google,Alibaba,Amazon)own large-scale datacenter networks that comprise thousands of switches and links.A loadbalancing mechanism is supposed to effectively utilize the bisection bandwidth.Both Equal-Cost Multi-Path(ECMP),the canonical solution in practice,and alternatives come with performance limitations or significant deployment challenges.In this work,we propose Closer,a scalable load balancing mechanism for cloud datacenters.Closer complies with the evaluation of technology including the deployment of Clos-based topologies,overlays for network virtualization,and virtual machine(VM)clusters.We decouple the system into centralized route calculation and distributed route decision to guarantee its flexibility and stability in large-scale networks.Leveraging In-band Network Telemetry(INT)to obtain precise link state information,a simple but efficient algorithm implements a weighted ECMP at the edge of fabric,which enables Closer to proactively map the flows to the appropriate path and avoid the excessive congestion of a single link.Closer achieves 2 to 7 times better flow completion time(FCT)at 70%network load than existing schemes that work with same hardware environment.

Impact of Partially Covered Vegetation on the Lateral Velocity Distribution of Open Channel Flow

The vegetation affects the flow process and water environment, thus drawing increasing attention to river environment management. Previous research is mainly focused on flow through vegetation in a channel with fully covered single-layer vegetation. However, in natural rivers, different heights’ vegetation often co-exists along one or two sides of a river. This paper experimentally studies how the flow velocity distribution is affected by the two different-layered vegetation allocated along two sides of an open-channel. The vegetation was simulated by dowels of two heights, 10 cm and 20 cm, and arranged in a parallel pattern along two sides of a flume under partially submerged conditions. The velocities along a cross-section were measured by Acoustic Doppler Velocimetry (ADV). The results of lateral velocity distribution show that a strong shear layer exists between vegetation and non-vegetation zones, indicating the retarding effect of vegetation. Meanwhile, as the flow depth increases, the relative velocity in the free flow zone decreases compared with that in the vegetated region, indicating that vegetation resistance to the flow decreases as increasing depth under the same vegetation configuration. These ?ndings would help understand the role of multi-layered vegetation in riparian management.

JUNO sensitivity on proton decay p→νK^(+)searches

The Jiangmen Underground Neutrino Observatory(JUNO)is a large liquid scintillator detector designed to explore many topics in fundamental physics.In this study,the potential of searching for proton decay in the p→νK^(+)mode with JUNO is investigated.The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification.Moreover,the excellent energy resolution of JUNO permits suppression of the sizable background caused by other delayed signals.Based on these advantages,the detection efficiency for the proton decay via p→νK^(+)is 36.9%±4.9%with a background level of 0.2±0.05(syst)±0.2(stat)events after 10 years of data collection.The estimated sensitivity based on 200 kton-years of exposure is 9.6×1033 years,which is competitive with the current best limits on the proton lifetime in this channel and complements the use of different detection technologies.

距离矢量路由混合SDN网络的一致性更新

混合SDN网络作为SDN网络与传统网络的过渡形态,在保留传统网络服务的同时,兼有部分软件定义网络易于管理维护的特点,但混合SDN网络的更新问题一直没能找到有效的解决方法,特别是当距离矢量路由参与混合的情况.本文将分段路由技术引入混合SDN网络更新,提出了一种分段路由在混合SDN网络更新的应用方案,结合顺序更新与两步复制机制,设计LFCA算法.LFCA算法首先尝试用分段路由拼接最终路径并将最终路径信息封装入数据包包头.而对于不可拼接的数据流,LFCA算法构建了顾及更新远端效应的动态拓扑集并基于回溯原理来评估每一步更新操作,通过不断回溯比较来最终找到最长一致性更新序列,对于仍未完成更新的节点利用两步复制机制完成更新.经过实验验证,与之前算法相比,LFCA算法可以极大地节省算法时间开销与存储资源开销.

Unraveling structure evolution failure mechanism in MoS_(2)anode for improving lithium storage stability

2 H phase molybdenum disulfide(2 H-MoS_(2))possesses the two-dimensional layered structure and high theoretical capacity,presenting excellent lithiation-delithiation property.However,the violent capacity decay within dozens of cycles still remains a great challenge due to lacking of in-depth failure mechanism.Herein,a novel decay-recovery-decay failure phenomenon upon long-term cycles is reported for the first time,which originates from the slow size change of Mo nanoparticles(NPs).Decay stages are triggered by many irregular-shaped Mo NPs with the increasing size up to~15 nm,leading to prominent pseudocapacitance failure and capacity loss.Subsequent recovery stages are attributed to the pulverization of coarse Mo NPs through surface sulfurization and accompanying lithiation.To overcome the instability issue,proper modifiers should be introduced to restrain the spontaneous growth of Mo NPs,such as aluminum oxide(Al_(2)O_(3)).The strong Mo-Al_(2)O_(3)bond gradually"drags"Al_(2)O_(3)fragments into the active material as the cycle continuously proceeds,resulting in the efficient refinement and the reversible conversion between Mo and MoS_(2).Therefore,the enhanced cycling stability and the capacity retention are successfully achieved.It is expected to provide a new insight into the energy storage of transition metal chalcogenide anode materials in rechargeable batteries.

Sub-percent precision measurement of neutrino oscillation parameters with JUNO

JUNO is a multi-purpose neutrino observatory under construction in the south of China.This publication presents new sensitivity estimates for the measurement of the △m_(31)^(2),△m_(21)^(2),sin^(2)θ_(12),and sin^(2)θ_(13) oscillation parameters using reactor antineutrinos,which is one of the primary physics goals of the experiment.The sensitivities are obtained using the best knowledge available to date on the location and overburden of the experimental site,the nuclear reactors in the surrounding area and beyond,the detector response uncertainties,and the reactor antineutrino spectral shape constraints expected from the TAO satellite detector.It is found that the △m_(21)^(2) and sin^(2)θ_(12) oscillation parameters will be determined to 0.5%precision or better in six years of data collection.In the same period,the △m_(31)^(2) parameter will be determined to about 0.2%precision for each mass ordering hypothesis.The new precision represents approximately an order of magnitude improvement over existing constraints for these three parameters.

Fast network restoration with equivalent cooperative routing

Aiming at the problem of failure recovery in current networks,a fast failure recovery method based on equivalent cooperative routing is proposed.Firstly,the transmission path between the source and destination nodes is divided into several non-overlapping path segments.Next,backup paths are deployed for each link in the path segment through segmented routing technology,which ensures fast routing recovery after failure.Additionally,in order to avoid damaging the QoS of the data stream through the failure recovery process,the transmission is guaranteed by the intersegment QoS complement.The experimental results show that the proposed method has a low failure recovery delay under a relatively small flow table cost.