High-efficiency sodium storage of Co_(0.85)Se/WSe_(2) encapsulated in N-doped carbon polyhedron via vacancy and heterojunction engineering

With the advantage of fast charge transfer,heterojunction engineering is identified as a viable method to reinforce the anodes'sodium storage performance.Also,vacancies can effectively strengthen the Na+adsorption ability and provide extra active sites for Na+adsorption.However,their synchronous engineering is rarely reported.Herein,a hybrid of Co_(0.85)Se/WSe_(2) heterostructure with Se vacancies and N-doped carbon polyhedron(CoWSe/NCP)has been fabricated for the first time via a hydrothermal and subsequent selenization strategy.Spherical aberration-corrected transmission electron microscopy confirms the phase interface of the Co_(0.85)Se/WSe_(2) heterostructure and the existence of Se vacancies.Density functional theory simulations reveal the accelerated charge transfer and enhanced Na+adsorption ability,which are contributed by the Co_(0.85)Se/WSe_(2) heterostructure and Se vacancies,respectively.As expected,the CoWSe/NCP anode in sodium-ion battery achieves outstanding rate capability(339.6 mAh g^(−1) at 20 A g^(−1)),outperforming almost all Co/W-based selenides.

Facile synthesis of the Mn_(3)O_(4)polyhedron grown on N-doped honeycomb carbon as high-performance negative material for lithium-ion batteries

Because of their large volume variation and inferior electrical conductivity,Mn_(3)O_(4)-based oxide anode materials have short cyclic lives and poor rate capability,which obstructs their development.In this study,we successfully prepared a Mn_(3)O_(4)/N-doped honeycomb carbon composite using a smart and facile synthetic method.The Mn_(3)O_(4)nanopolyhedra are grown on N-doped honeycomb carbon,which evidently mitigates the volume change in the charging and discharging processes but also improves the electrochemical reaction kinetics.More importantly,the Mn-O-C bond in the Mn_(3)O_(4)/N-doped honeycomb carbon composite benefits electrochemical reversibility.These features of the Mn_(3)O_(4)/N-doped honeycomb carbon(NHC)composite are responsible for its superior electrochemical performance.When used for Li-ion batteries,the Mn_(3)O_(4)/N-doped honeycomb carbon anode exhibits a high reversible capacity of 598 mAh·g^(−1)after 350 cycles at 1 A·g^(−1).Even at 2 A·g^(−1),the Mn_(3)O_(4)/NHC anode still delivers a high capacity of 472 mAh·g^(−1).This work provides a new prospect for synthesizing and developing manganese-based oxide materials for energy storage.

Unique NiFe–NiCoO2 hollow polyhedron as bifunctional electrocatalysts for water splitting

It is of significance to design of stable and cost-effective electrocatalyst for water splitting with high efficiency in an alkaline medium.The major obstacles for practical application of water splitting devices are lack of high-efficiency and low-cost electrocatalysts with low overpotential for both HER and OER.In this paper,we report a NiFe alloy decorated NiCoO2 hollow polyhedron(denoted as Ni Fe–Ni Co O2)by using[NiFe(CN)6]- intercalated NiCo–LDH as precursor.As evidenced by the electrochemical active surface area,the resultant Ni Fe–Ni Co O2 composite shows unique hollow nanostructure,which can not only provide abundant mass transport channels,but also increase the contact area of the NiFe–Ni Co O2 material with the electrolyte.The overpotential(η)demand is 286 mV for OER and 102 mV for HER at the current density of 10 mA/cm2 in an alkaline medium of 1 M KOH for the NiFe/NiCoO2 composite.This work provides a new pathway for preparation of the highly efficient bifunctional electrocatalysts for water splitting.

Ratio of In-Sphere Volume to Polyhedron Volume of the Great Pyramid Compared to Selected Convex Polyhedral Solids

The architecture of the Great Pyramid at Giza is based on fascinating golden mean geometry. Recently the ratio of the in-sphere volume to the pyramid volume was calculated. One yields as result RV = π ⋅ φ5, where is the golden mean. It is important that the number φ5 is a fundamental constant of nature describing phase transition from microscopic to cosmic scale. In this contribution the relatively small volume ratio of the Great Pyramid was compared to that of selected convex polyhedral solids such as the Platonic solids respectively the face-rich truncated icosahedron (bucky ball) as one of Archimedes’ solids leading to effective filling of the polyhedron by its in-sphere and therefore the highest volume ratio of the selected examples. The smallest ratio was found for the Great Pyramid. A regression analysis delivers the highly reliable volume ratio relation , where nF represents the number of polyhedron faces and b approximates the silver mean. For less-symmetrical solids with a unique axis (tetragonal pyramids) the in-sphere can be replaced by a biaxial ellipsoid of maximum volume to adjust the RV relation more reliably.

Improved non-uniform subdivision scheme with modified Eigen-polyhedron

In this study,a systematic refinement method was developed for non-uniform Catmull-Clark subdivision surfaces to improve the quality of the surface at extraordinary points(EPs).The developed method modifies the eigenpolyhedron by designing the angles between two adjacent edges that contain an EP.Refinement rules are then formulated with the help of the modified eigenpolyhedron.Numerical experiments show that the method significantly improves the performance of the subdivision surface for non-uniform parameterization.

Fast,Exact and Robust Set Operations on Polyhedrons Using Localized Constructive Solid Geometry Trees

Regularized Boolean operations have been widely used in 3D modeling systems. However, evaluating Boolean operations may be quite numerically unstable and time consuming, especially for iterated set operations. A novel and unified technique is proposed in this paper for computing single and iterated set operations efficiently, robustly and exactly. An adaptive octree is combined with a nested constructive solid geometry （CSG） tree by this technique. The intersection handling is restricted to the cells in the octree where intersection actually occurs. Within those cells, a CSG tree template is instanced by the surfaces and the tree is converted to planebased binary space partitioning （BSP） for set evaluation; Moreover, the surface classification is restricted to the ceils in the octree where the surfaces only come from a model and are within the bounding-boxes of other polyhedrons. These two ways bring about the efficiency and scalability of the operations, in terms of runtime and memory. As all surfaces in such a cell have the same classification relation, they are classified as a whole. Robustness and exactness are achieved by integrating plane-based geometry representation with adaptive geometry predicate technique in intersection handling, and by applying divide-and-conquer arithmetic on surface classification. Experimental results demonstrate that the proposed approach can guarantee the robustness of Boolean computations and runs faster than other existing approaches.

Ferromagnetic Calculation of Terbium Dysprosium and Holmium with Polyhedron Electron Shell

Based on the regular polyhedron model of multi-electronic atom combined with the Bohr hypothesis, the following supposition is put forward: the electron momentum multiplied by the inscribed sphere radius of edges of each regular polyhedron is equal to the Planck constant. The relationship between saturation magnetization rates and Planck constants is determined, and the ferromagnetism of atoms is obtained from regular dodecahedron and regular hexahedron. Then, terbium, dysprosium, and holmium saturation magnetization rate are obtained from electronic regular polyhedron configuration. Derivation of matter wave formula is from thermodynamics, avoiding over speed of light.

The Atomic Regular Polyhedron Electronic Shell

The periodic table of elements is arranged based on a series of regular polyhedron. The stability of inert gas atoms can be explained by the distribution of electrons, as well as their motion and magnetic force structure. A magnetic force regular octahedron is proposed. It is a unique configuration that best satisfies the convergence of electrons moving in the same direction within regular polyhedra. In the case of an electrostatic force crust, the formal electron spin accounts for the crusts intrinsic magnetic moment exceeding the speed of light. If one is to consider that the electron has a magnetic outer layer and an electrostatic inner layer, then the question can be solved and abovementioned inference can provide the basis for magnetic force and momentum for the regular octahedron model. The electron periphery has twenty-petal adsorptive substances;the existence of adsorptive substance causes the magnetic force greater than the electrostatic force. Each electronic shell in the regular polyhedron is in accordance with the electron configuration of periodic table of elements;the kinetic track of each electron is a surface of regular polyhedron. The magnetic properties of iron, cobalt, and nickel can be explained by the regular dodecahedron electronic shell of an atom. The electron orbit converged from reverse direction can explain diamond. The adsorptive substances found in atomic nuclei and electrons are defined as magnetic particles called magnetons. The thermodynamic magneton theory can be better explained when it is analyzed using principles of thermodynamics, superconductivity, viscosity, and even in the creation of glass. The structure of the light is a helical line.

Solvothermal Synthesis of Polyhedron Cobalt Nanomaterials

Co nanostructure tetradecahedron shape like were prepared via a simple solvothermal route. The shape and size of Co nanopolyhedron were tuned by changing the volume composition of the solvents and the synthesis temperature. Phase purity was confirmed by X-ray diffraction （XRD） and crystal size was determined by scanning electron microscopy （SEM）. The magnetic hysteresis loops of the polyhedron wareneasured using a SQUID magnetometer at 5 and 300 K. The results show ferromagnetic characteristics with coercivities of 22 and 15 Oe, respectively.

Optimal fuzzy PID controller with adjustable factors based on flexible polyhedron search algorithm

A new kind of optimal fuzzy PID controller is proposed, which contains two parts. One is an on line fuzzy inference system, and the other is a conventional PID controller. In the fuzzy inference system, three adjustable factors x p, x i , and x d are introduced. Their functions are to further modify and optimize the result of the fuzzy inference so as to make the controller have the optimal control effect on a given object. The optimal values of these adjustable factors are determined based on the ITAE criterion and the Nelder and Mead′s flexible polyhedron search algorithm. This optimal fuzzy PID controller has been used to control the executive motor of the intelligent artificial leg designed by the authors. The result of computer simulation indicates that this controller is very effective and can be widely used to control different kinds of objects and processes.

Two Algorithms for Fast Polyhedron Ray-Tracing

This note presents two fast polyhedron ray-tracing algorithms that can be applied not only in ray-convex polyhedron intersection, but also in ray-concave polyhedron intersection (Algorithm 2 permits polygons to contain internal loops of not).In the basis of surface trian gulation, Algorithm 1 can accelerate the surface normal vector interpolation by the intersection point's parameters. And besides, Algorithm 2 does not need any pre_procession such as surface triangulation. Moreover, it requires a few memories with more difficult operations such as division, extraction of roots and transcendental functions avoided entirely. Their simplicity and efficiency permit easy software or hardware implementation.

Ternary alloy and metal oxides embedded in yolk–shell polyhedrons as bifunctional oxygen electrocatalyst

To improve the efficiency of oxygen electrolysis,exploiting bifunctional electrocatalysts with excellent activity and stability is extremely important due to the four-electron transfer dynamics of oxygen evolution reaction(OER)and oxygen reduction reaction(ORR).Herein,a series of yolk-shell hollow polyhedrons(YHPs)embedded with NiCoFe ternary alloy and metal oxides,which are named YHP-x(x=1,2,3,4),were reported.By controlled etching multi-layered zeolitic imidazolate frameworks and following pyrolytic integration,YHPs are endowed with mass transfer tunnels,accessible inner active sites,and good electrical conductivity.Due to the synergetic effect of the alloy,metal oxides and the yolk-shell structure,YHP-1 exhibits excellent ORR performance with a half-wave potential of 0.79 V and YHP-2 displays superior OER performance with a low overpotential of 257 mV at 10 mA cm−2.The strategy described in this work can be extended to a number of hollow/yolk-shell electrocatalysts for water splitting and metal–air batteries.

Enhance gas-separation efficiency of mixed matrix membranes by lamellarly arranged metal-organic polyhedron

Eliminating the nonselective permeation path inside the mixed-matrix membranes(MMMs)is critical for fabrication of gas separation membranes.We demonstrate that by utilizing the phase separation of block copolymers,we are able to introduce metal-organic polyhedrons(MOPs)with precise pore sizes into a polymer matrix and form an ordered layered structure.We also prove that,by arranging MOP cages into a continuous nanosheet-like layer structure,we are able to generate repeated MOP-effective pathways and deplete the MOP-free permeation pathways,thus enhancing the gas-separation efficiency of MMMs.

灵活性资源聚合参考模型与量化指标体系

高比例新能源并网给电网带来了显著的波动性和不确定性,使受端电网面临可调节资源能力不足的问题,需要充分利用大量的灵活性资源参与电网调度并提供辅助服务。然而,灵活性资源的数量众多、分布广泛且特性各异,给资源的集中调控带来了新的挑战,需要以集群的形式对灵活性资源进行管理和调度。为了更加准确地评估集群在电网调控中的作用,需要将灵活性资源进行聚合,并根据应用需求采用适当的量化指标衡量其性能。基于灵活性资源集群在电网调度和电力市场中的应用需求,提出了评估灵活性资源集群可调节能力的量化指标体系。根据物理特性,将其分为类发电机特性、类储能特性和共有特性3类。为了实现不同应用场景下对集群灵活性指标的量化评估,构建了由等效发电机和等效储能所组成的灵活性资源集群的聚合参考模型。此聚合参考模型具有直观的物理意义和良好的多重嵌套特性,并适用于多种时间尺度和多种能量形式,可以被用于计算特定应用场景下的量化性能指标,以及应用于分布式资源集群的异步调度、综合能源系统的联合优化调度、虚拟电厂参与电力市场的投标报价等多个场景中。

一种6-DOF小行星着陆轨迹序列凸优化方法

针对6自由度的小行星动力着陆多约束轨迹优化问题,提出了一种基于序列凸优化的小行星着陆轨迹优化算法。首先采用多面体引力场模型计算小行星的引力场,其可用于描述任意形状的小行星引力场,且比质点群法和球谐函数展开法等方法计算精度更高。为了在凸约束下解决小行星着陆过程燃料消耗最优问题,通过对探测器动力学模型及其约束进行线性化和离散化,将原来的非凸连续时间优化问题转化为凸化的子问题,即二阶锥规划问题(SOCP);然后引入了虚拟控制项和信赖域,以增强算法的鲁棒性。通过在形状不规则小行星上的着陆模拟,验证了所提出算法的有效性,仿真结果满足各项约束条件,可实现高精度着陆和燃料消耗最优的目标。

基于图像八叉树的三维比例边界有限元多面体网格生成算法

基于图像八叉树方法,提出了平衡八叉树和多面体网格修剪相结合的三维比例边界有限元多面体网格算法,该算法根据结构尺寸建立恰好完全包含整个结构的立方体网格,再建立结构图像像素信息,根据像素信息,按照2∶1的平衡分割原则递归地进行等分,完成平衡八叉树网格生成。结构内单元网格完全保留,结构外单元网格删除,对于结构边界单元网格,提出采用面-立方体相交判断方法进行边界单元与结构边界相交面的筛选,搜寻结构单元与结构边界表面相交点,通过有序连接相交点形成边界单元切割面,再结合边界单元其他几个面,构成裁剪后的多面体单元。数值算例结果表明,基于本文算法生成的比例边界有限元网格计算结果具有较好的精度和边界适应性。

Functional substitution of coordination polyhedron in crystal structure of silicates

On the bases of the study of comparative crystal chemistry of silicates it has been concluded that the octahedra and square pyramids of Ti-0 and Zr-O play functional role of tetrahedra of Si-O in the construction of crystal structures. Therefore, those silicates may be named titano-and zircono-silicates. Because of the functional similarity of coordination polyhedra, the structures of cristobalite and feldspar have been compared with those of perovskite and garnet, respectively. As a new concept, the functional replacement of tetrahedra by octahedra and/or pyramids is defined by the authors of this paper for favorable comparison of relative crystal structures.

Uniform design over a convex polyhedron

A new method, called the simplex method, is proposed to generate the uniform design over a convex polyhedron in n-dimensional Euclidean

Porous carbon polyhedrons coupled with bimetallic CoNi alloys for frequency selective wave absorption at ultralow filler loading

Combining suitable microstructure and dielectric-magnetic synergy effect is conducive to achieve lightweight,broadband,and high-efficiency microwave absorbing materials within low filler loading.Herein,porous carbon polyhedrons coupled with bimetallic CoNi alloys were synthesized by using metalorganic frameworks(MOFs)as a template and subsequent pyrolysis treatment.Electromagnetic analysis indicated that the existence of metal Ni element could influence the wave attenuation capacity effectively,resulting in frequency selective wave absorption performance.Additionally,the pyrolysis temperature was also closely related to wave absorption intensity.The Co_(2)Ni_(1)/C/PVDF composites calcined at 800℃ possessed outstanding wave absorption performance at an ultra-low filler loading of 5 wt%.The minimum reflection loss value achieved-52 dB(10.8 GHz)under the matched thickness of 3 mm.Moreover,the broadest effective absorption bandwidth(RL<-10 dB)reached 6.2 dB(11.8-18 GHz)for Co/C-800/PVDF composites when the thickness turned into 2 mm.The remarkable wave attenuation ability was mainly ascribed to magnetic and dielectric loss,impedance matching as well as porous structure effect.

Synthesis and facet-dependent photocatalytic activity of strontium titanate polyhedron nanocrystals

Cubic-perovskite （SrTiO3） has a great potential to be utilized in a wide range of applications. However, currently very little is known about the shape and facet effects of SrTiO3 on their physicochemical properties. This is largely owing to the difficulties in controlling the morphology of facets during synthesis. Herein, we describe a facile route for the facet- and size-controlled fabrication of single- crystalline SrTiO3 triangular prisms with highly exposed {101} side faces and {111} end faces. Theoretical and experimental studies of their photocatalytic performance have shown that triangular prisms exhibit superior photocatalytic activities than nanocubes with exposed （001） faces for the degradation of organic contaminants, which may be primarily attributed to the much higher surface energy of {101} facets （2.97 J/m^2） and {111} facets （2.80 J/m^2） than of that of {001} facets （0.98 J/m^2）.