Kinetic-boosted CO_(2) electroreduction to formate via synergistic electric-thermal field on hierarchical bismuth with amorphous layer

Electrocatalytic converting CO_(2) into chemical products has emerged as a promising approach to achieving carbon neutrality.Herein,we report a bismuth-based catalyst with high curvature terminal and amorphous layer which fabricated via two-step electrodeposition achieves stable formate output in a wide voltage window of 600 mV.The Faraday efficiency(FE) of formate reached up to 99.4% at-0.8 V vs.RHE and it remained constant for more than 92 h at-15 mA cm^(-2).More intriguingly,FE formate of95.4% can be realized at a current density of industrial grade(-667.7 mA cm^(-2)) in flow cell.The special structure promoted CO_(2) adsorption and reduced its activation energy and enhanced the electric-thermal field and K^(+) enrichment which accelerated the reaction kinetics.In situ spectroscopy and theoretical calculation further confirmed that the introduction of amorphous structure is beneficial to adsorpting CO_(2)and stabling*OCHO intermediate.This work provides special insights to fabricate efficient electrocatalysts by means of structural and crystal engineering and makes efforts to realize the industrialization of bismuth-based catalysts.

Group-Consensus of Hierarchical Containment Control for Linear Multi-Agent Systems

The existing containment control has been widely developed for several years, but ignores the case for large-scale cooperation. The strong coupling of large-scale networks will increase the costs of system detection and maintenance. Therefore, this paper is concerned with an extensional containment control issue, hierarchical containment control. It aims to enable a multitude of followers achieving a novel cooperation in the convex hull shaped by multiple leaders. Firstly, by constructing the three-layer topology, large-scale networks are decoupled. Then,under the condition of directed spanning group-tree, a class of dynamic hierarchical containment control protocol is designed such that the novel group-consensus behavior in the convex hull can be realized. Moreover, the definitions of coupling strength coefficients and the group-consensus parameter in the proposed dynamic hierarchical control protocol enhance the adjustability of systems. Compared with the existing containment control strategy, the proposed hierarchical containment control strategy improves dynamic control performance. Finally, numerical simulations are presented to demonstrate the effectiveness of the proposed hierarchical control protocol.

Engineering hierarchical quaternary superstructure of an integrated MOF-derived electrode for boosting urea electrooxidation assisted water electrolysis

Controllable design of the catalytic electrodes with hierarchical superstructures is expected to improve their electrochemical performance.Herein,a self-supported integrated electrode(NiCo-ZLDH/NF)with a unique hierarchical quaternary superstructure was fabricated through a self-sacrificing template strategy from the metal–organic framework(Co-ZIF-67)nanoplate arrays,which features an intriguing well-defined hierarchy when taking the unit cells of the NiCo-based layered double hydroxide(NiCo-LDH)as the primary structure,the ultrathin LDH nanoneedles as the secondary structure,the mesoscale hollow plates of the LDH nanoneedle arrays as the tertiary structure,and the macroscale three-dimensional frames of the plate arrays as the quaternary structure.Notably,the distinctive structure of NiCo-ZLDH/NF can not only accelerate both mass and charge transfer,but also expose plentiful accessible active sites with high intrinsic activity,endowing it with an excellent electrochemical performance for urea oxidation reaction(UOR).Specially,it only required the low potentials of 1.335,1.368 and 1.388 V to deliver the current densities of 10,100 and 200 mA cm^(-2),respectively,much superior to those for typical NiCo-LDH.Employing NiCo-ZLDH/NF as the bifunctional electrode for both anodic UOR and cathodic HER,an energy-saving electrolysis system was further explored which can greatly reduce the needed voltage of 213 mV to deliver the current density of 100 mA cm^(-2),as compared to the conventional water electrolysis system composed of OER.This work manifests that it is prospective to explore the hierarchically nanostructured electrodes and the innovative electrolytic technologies for high-efficiency electrocatalysis.

3D Hierarchical Co–Al Layered Double Hydroxides with Long-Term Stabilities and High Rate Performances in Supercapacitors

Three-dimensional(3D) flower-like Co–Al layered double hydroxide(Co–Al-LDH) architectures composed of atomically thin nanosheets were successfully synthesized via a hydrothermal method in a mixed solvent of water and butyl alcohol. Owing to the unique hierarchical structure and modification by butyl alcohol, the electrochemical stability and the charge/mass transport of the Co–Al-LDHs was improved. When used in supercapacitors, the obtained Co–Al-LDHs deliver a high specific capacitance of 838 Fg^(-1) at a current density of 1 Ag^(-1)and excellent rate performance(753 Fg^(-1) at 30 Ag^(-1) and 677 Fg^(-1) at 100 Ag^(-1)), as well as excellent cycling stability with 95% retention of the initial capacitance even after 20,000 cycles at a current density of 5 Ag^(-1). This work provides a promising alternative strategy to enhance the electrochemical properties of supercapacitors.

Distributed Fault-Tolerant Containment Control for Nonlinear Multi-Agent Systems Under Directed Network Topology via Hierarchical Approach

This paper investigates the distributed fault-tolerant containment control(FTCC)problem of nonlinear multi-agent systems(MASs)under a directed network topology.The proposed control framework which is independent on the global information about the communication topology consists of two layers.Different from most existing distributed fault-tolerant control(FTC)protocols where the fault in one agent may propagate over network,the developed control method can eliminate the phenomenon of fault propagation.Based on the hierarchical control strategy,the FTCC problem with a directed graph can be simplified to the distributed containment control of the upper layer and the fault-tolerant tracking control of the lower layer.Finally,simulation results are given to demonstrate the effectiveness of the proposed control protocol.

Hierarchical molybdenum disulfide nanosheet arrays stemmed from nickel-cobalt layered double hydroxide/carbon cloth for highly-efficient hydrogen evolution reaction

The hierarchical structure of molybdenum disulfide(MoS2)nanosheet arrays stemmed from nickelcobalt layered double hydroxide(NiCo-LDH)/carbon cloth was prepared by growing the MoS_(2) nanosheet arrays onto the NiCo-LDH template which was pre-deposited onto the carbon cloth substrate.In this electrode configuration,carbon cloth is the three dimensional and conductive skeleton;NiCo-LDH nanosheets,as the template,ensure the oriented growth of MoS2 nanosheet arrays.Therefore,more MoS_(2) active sites are exposed and the catalyst exhibits good hydrogen evolution reaction activity.

Synthesis of Three-Dimensional Hierarchical Flower-Like Mg–Al Layered Double Hydroxides with Excellent Adsorption Performance for Organic Anionic Dyes

In this work,a facile and effective strategy to prepare three-dimensional(3D)hierarchical flower-like Mg–Al layered double hydroxides(3D-LDH)was developed via a one-step double-drop coprecipitation method usingγ-Al 2O 3particles as a template.The characterization and experimental results showed that the calcined product,3D-LDO,features a large specific surface area of 204.2 m^(2)/g,abundant active sites,and excellent adsorption performance for Congo red(CR),methyl orange(MO),and methyl blue(MB).The maximum adsorption capacities of 3D-LDO for CR,MO,and MB were 1428.6,476.2,and 1666.7 mg/g,respectively;such performance is superior to that of most reported adsorbents.The adsorption mechanism of organic anionic dyes by 3D-LDO was extensively investigated and attributed to surface adsorption,the memory effect of 3D-LDO,and the unique 3D hierarchical flower-like structure of the adsorbent.Recycling performance tests revealed that3D-LDO has satisfactory reusability for the three organic anionic dyes.

Discrete decision model and multi-agent simulation of the Liang Zong two-chain hierarchical organization in a complex project

Different from the organization structure of complex projects in Western countries, the Liang Zong hierarchical organization structure of complex projects in China has two different chains, the chief-engineer chain and the general-director chain,to handle the trade-off between technical and management decisions. However, previous works on organization search have mainly focused on the single-chain hierarchical organization in which all decisions are regarded as homogeneous. The heterogeneity and the interdependency between technical decisions and management decisions have been neglected. A two-chain hierarchical organization structure mapped from a real complex project is constructed. Then, a discrete decision model for a Liang Zong two-chain hierarchical organization in an NK model framework is proposed. This model proves that this kind of organization structure can reduce the search space by a large amount and that the search process should reach a final stable state more quickly. For a more complicated decision mechanism, a multi-agent simulation based on the above NK model is used to explore the effect of the two-chain organization structure on the speed, stability, and performance of the search process. The results provide three insights into how, compared with the single-chain hierarchical organization, the two-chain organization can improve the search process: it can reduce the number of iterations efficiently; the search is more stable because the search space is a smoother hill-like fitness landscape; in general, the search performance can be improved.However, when the organization structure is very complicated, the performance of a two-chain organization is inferior to that of a single-chain organization. These findings about the efficiency of the unique Chinese-style organization structure can be used to guide organization design for complex projects.

A Multi-Agent School Simulation Based on Hierarchical Social Networks

The quality of K-12 education has been a very big concern for years. Previous methods studied only one or two factors, such as school choice, or teacher quality, on school performance. Therefore the results they provide can be limited. We propose a multi-agent approach to integrate multiple actors in a school system. These actors include teachers, students, supporting staffs and administrators. The interactions among these actors compose a hierarchical school social network. We first detect the hierarchical community structure in this school network by using an agglomerative hierarchical algorithm. Existing agglomerative hierarchical algorithms usually calculate similarity or dissimilarity between two clusters by using some measure of distance between pairs of observations. We, however, develop a method that calculates similarity based on social interactions between interactions is essential in multi-agent systems. Our algorithm is applied to 15 school districts in Bexar County, Texas, and it provides satisfying results on generating the hierarchical structure of all school districts. We then use the detected structure of the social network to evaluate the school system’s organization performance. We design and implement a funding evaluation model to decompose the funding policy task into subtasks and then evaluate these subtasks by using funding distribution policies from past years and looking for possible relationships between student performances and funding policies. Experiments in the 15 school districts in Bexar County show no significant correlation between student performance and the amount of the funding a school district received.

Hierarchical multicast with inter-layer random network coding

To maximize the aggregate throughput achieved in heterogeneous networks, this paper investigates inter-session network coding for the distribution of layered source data. We define inter-layer hierarchical random linear network codes （IHRLNC）, which not only take the flexibility of intersession network coding for layer mixing but also consider the strict priority inherent in the layered source data. Furthermore, we propose the inter-layer hierarchical multicast （IHM）, which performs IHRLNC in the network such that each sink can recover some source layers according to its individu- al capacity. To determine the optimal type of IHRLNC that should be performed on each edge in IHM, we formulate an optimization problem based on 0-1 integer linear programming, and propose a heuristic approach to approximate the optimal solution in polynomial time. Simulation results show that the proposed IHM can achieve throughput gains over the layered muhicast schemes.

Dye-Sensitized Solar Cells with An Electrophoresis-Deposited Layer of {001} Exposed Nanosheet-Based Hierarchical TiO_(2) Spheres

Anatase Ti0_(2) nanosheet-based hierarchical spheres(HSs)with nearly 100%exposed{001}facets were synthesized via a facile solvothermal process.Using these hierarchical spheres as a scattering layer on nanocrystaline TiO_(2)film,hi-layered dye-sensitized solar cells(DSSCs)have been fabricated by electrophoresis deposition method,which well preserved the fragile hierarchical structure.Owing to the superior dye adsorption and light scattering effect of HSs,an overall energy conversion efficiency of 7.38%is achieved,which is 26%higher than that of nanoparticle-based photoanode.

Multi-Layer Tree Hierarchical Architecture Based on Web Service

To solve the problem of the information share and services integration in population information system, we propose a multi-layer tree hierarchical architecture. The command （Web Service Call） is recursively muhicast from top layer of tree to bottom layer of tree and statistical data are gatbered from bottom layer to top layer. We implemented the architecture by using Web Services technology. In our implementation, client program is the requestor of Web Services, and all leaf nodes of the last layer are only the provider of Web Services. For those nodes of intermediate layers, every node is not only the provider of Web Services, but also the dispatcher of Web Services. We take population census as an cxample to describe the working flow of the architecture.

Advances in efficient electrocatalysts based on layered double hydroxides and their derivatives

The explore and development of electrocatalysts have gained significant attention due to their indispensable status in energy storage and conversion systems, such as fuel cells, metal–air batteries and solar water splitting cells. Layered double hydroxides（LDHs） and their derivatives（e.g., transition metal alloys, oxides, sulfides, nitrides and phosphides） have been adopted as catalysts for various electrochemical reactions, such as oxygen reduction, oxygen evolution, hydrogen evolution, and COreduction, which show excellent activity and remarkable durability in electrocatalytic process. In this review, the synthesis strategies, structural characters and electrochemical performances for the LDHs and their derivatives are described. In addition, we also discussed the effect of electronic and geometry structures to their electrocatalytic activity. The further development of high-performance electrocatalysts based on LDHs and their derivatives is covered by both a short summary and future outlook from the viewpoint of the material design and practical application.

Hierarchical Ni-Al hydrotalcite supported Pt catalyst for efficient catalytic oxidation of formaldehyde at room temperature

Catalytic oxidation at room temperature is recognized as the most promising method for formaldehyde(HCHO)removal.Pt‐based catalysts are the optimal catalyst for HCHO decomposition at room temperature.Herein,flower‐like hierarchical Pt/NiAl‐LDHs catalysts with different[Ni2+]/[Al3+]molar ratios were synthesized via hydrothermal method followed by NaBH4 reduction of Pt precursor at room temperature.The flower‐like hierarchical Pt/NiAl‐LDHs were composed of interlaced nanoplates and metallic Pt nanoparticles(NPs)approximately 3–4 nm in diameter were loaded on the surface of the Pt/NiAl‐LDHs with high dispersion.The as‐prepared Pt/NiAl21 nanocomposite was highly efficient in catalyzing oxidation of HCHO into CO2 at room temperature.The high activity of the hierarchical Pt/NiAl21 nanocomposite was maintained after seven recycle tests,suggesting the high stability of the catalyst.Based on in situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)studies,a reaction mechanism was put forward about HCHO decomposition at room temperature.This work provides new insights into designing and fabricating high‐performance catalysts for efficient indoor air purification.

Hierarchical CoNi-LDH nanosheet array with hydrogen vacancy for high-performance aqueous battery cathode

Aqueous rechargeable multiple metal-ion storage battery (ARSB) has a large potential in energy storage devices due to their safe usage, low cost and high rate capability. Nevertheless, the performance of practical ARSB is largely restricted by low capacity and limited cathode materials. Herein, we demonstrate an efficient cathode material based on Co Ni-layered double hydroxide (LDH) nanosheets arrays with abundant hydrogen vacancy induced by electrochemical activation process for high performance of cations storage. Consequently, the electrochemical activated Co Ni-LDH (ECA-Co Ni-LDH) nanosheets arrays exhibit high metal ion (Li^(+), Na^(+), Zn^(2+), Mg^(2+) and Ca^(2+)) storage capacities, which is 9 times and 3 times higher that of unactivated Co Ni-LDH arrays and ECA-Co Ni-LDH without hierarchical structure, respectively.Moreover, the ECA-Co Fe-LDH also shows the possibility for practical applications in actual batteries.By coupling with a Fe_(2)O_(3)/C anode, the assembled aqueous battery delivered a large energy density of 184.4 Wh kg^(-1)at power density of 4 Wh kg^(-1) in high voltage range of 0–2 V. To our best knowledge, such high energy density and large working window of our assembled aqueous battery is exceeded other LDH-based aqueous battery or supercapacitor, and the energy density almost comparable than that of commercial Li-ion batteries. Moreover, almost no measurable capacitance losses can be detected even after 10000 cycles. In addition, this work also provides a strategy to develop a high energy density cathode for multiple metal-ion storage batteries.

Research on Comparison of Enterprise Financing Efficiency under Layered Background

This paper takes the innovative enterprises with substantial financing in2014-2016 as the research sample,uses the foundation layer enterprises under the same conditions as the contrast,and uses the data envelopment analysis to do empirical research. By comparing the comprehensive technical efficiency,pure technical efficiency and scale efficiency of the sample enterprises and the controlled enterprises,and through the analysis of slack variables of non DEA efficient enterprises,the reasons for the low efficiency and the improvement direction are pointed out. The results show that the financing efficiency of innovation layer enterprises is obviously higher than that of the underlying enterprises,and the financing efficiency has also improved in recent years,but there are still unstable factors,main problem of which is poor operating capacity of funds.

Mathematical Modeling Algorithms for Creating New Materials with Desired Properties Using Nano-Hierarchical Structures

In the enormous and still poorly mastered gap between the macro level, where well developed continuum theories of continuous media and engineering methods of calculation and design operate, and atomic, subordinate to the laws of quantum mechanics, there is an extensive meso-hierarchical level of the structure of matter. At this level unprecedented previously products and technologies can be artificially created. Nano technology is a qualitatively new strategy in technology: it creates objects in exactly the opposite way—large objects are created from small ones [1]. We have developed a new method for modeling acoustic monitoring of a layered-block elastic medium with several inclusions of various physical and mechanical hierarchical structures [2]. An iterative process is developed for solving the direct problem for the case of three hierarchical inclusions of l, m, s-th ranks based on the use of 2D integro-differential equations. The degree of hierarchy of inclusions is determined by the values of their ranks, which may be different, while the first rank is associated with the atomic structure, the following ranks are associated with increasing geometric sizes, which contain inclusions of lower ranks and sizes. Hierarchical inclusions are located in different layers one above the other: the upper one is abnormally plastic, the second is abnormally elastic and the third is abnormally dense. The degree of filling with inclusions of each rank for all three hierarchical inclusions is different. Modeling is carried out from smaller sizes to large inclusions;as a result, it becomes possible to determine the necessary parameters of the formed material from acoustic monitoring data.

微通道换热器拓扑结构优化与性能研究

换热器结构拓扑优化可将传热强化设计问题转化为数学优化问题进行求解,对于设计新颖高效换热器具有重要价值。然而,拓扑优化数学模型难以直接解释优化结果的几何特征及相应强化机理。以传热量为目标,对微通道换热器进行拓扑优化设计,研究了不同参数对换热器强化结构特征和换热器性能的影响。结果表明,拓扑优化换热器的通道结构呈现多级分叉构型,分叉的数量随着入口Reynolds数、翅片传热效率和流体Prandtl数的增大而增多。在此基础上,采用耗散和边界层理论分析了拓扑优化分叉通道与流体边界层厚度的内在联系,为换热器结构强化设计提供了新的思路。

P2P网络环境下的一种高效搜索算法:Multilayer Light-Gossip

由于现有非结构化P2P网络路由协议均在应用层实现,缺乏缓存机制和对Internet底层通信子网路由资源的利用,存在可扩展性差和效率不高的问题·在基于层域结构的RLP2P网络环境下,将路由空间分为域间和域内两层,结合泛洪和生成树搜索方式的优点,提出并实现了一种Multilayer Light-Gossip分级搜索算法和域间基于正六边形的蜂窝路由探测策略,把网络中的搜索消息分为域间和域内扩散两类分级扩散,以一定的消息冗余保持网络的稳健性和搜索的有效性,使定位某种服务的工作量和查询范围从网络中的所有结点数降到域内的节点数·运用预测评估方法对级间路由消息进行预分组,使消息能够自适应地沿着一条在时间度量上距离尽量短的路径前进·实验结果表明,Multilayer Light-Gossip算法大幅提高搜索效率和减少冗余消息,在广域环境下具有良好的搜索性能和扩展性·

面阵投影增材制造技术自适应分层算法

增材制造采用“逐层叠加”的原理来成型制件,层厚越小,制件的表面质量越高,成型效率越低。为了调节制件成型效率与表面质量之间矛盾的问题,提出了基于STL制件法矢量的自适应分层算法。该算法先计算出与切面层相交的三角面片的法矢量与制造方向的夹角集,然后对夹角集的均值与最小值进行加权求和,依据加权求和后的角度关系,实现对制件进行自适应调整分层厚度。对同一制件分别采用本文算法及已知的4种算法进行分层,实验结果表明,这里算法能够有效平衡制件表面质量与成型效率之间的关系,较其余4种自适应分层算法,阶梯体积误差小且制件成型时间短。