Performance Analysis of Intelligent Reflecting Surface Assisted Wireless Communication System

In this paper,we investigate the end-to-end performance of intelligent reflecting surface(IRS)-assisted wireless communication systems.We consider a system in which an IRS is deployed on a uniform planar array(UPA)configuration,including a large number of reflecting elements,where the transmitters and receivers are only equipped with a single antenna.Our objective is to analytically obtain the achievable ergodic rate,outage probability,and bit error rate(BER)of the system.Furthermore,to maximize the system’s signal-to-noise ratio(SNR),we design the phase shift of each reflecting element and derive the optimal reflection phase of the IRS based on the channel state information(CSI).We also derive the exact expression of the SNR probability density function(p.d.f.)and show that it follows a non-central Chi-square distribution.Using the p.d.f.,we then derive the theoretical results of the achievable rate,outage probability,and BER.The accuracy of the obtained theoretical results is also verified through numerical simulation.Itwas shown that the achievable rate,outage probability,and BER could be improved by increasing the number of reflecting elements and choosing an appropriate SNR regime.Furthermore,we also find that the IRS-assisted communication system achieves better performance than the existing end-to-end wireless communication.

The effect of anisotropic surface tension on the morphological stability of planar interface during directional solidification

This paper considers the effect of the anisotropic surface tension on the morphological stability of the planar interface during directional solidification. When the expression exhibiting the four-fold symmetry is included, the modified absolute stability criterion is obtained by employing the multi-variable expansion method. The linear stability analysis reveals that for the given temperature gradient, as the anisotropic surface tension parameter increases, the stability zone tends to decrease.

Research on Planar Development of Curved Surfaces

Development of curved surface is a useful tool in CAD(computer aided design) and CAGD(computer aided geometric design).This paper presents the algorithms for developing (flattening) a smooth continuous curved surface embedded in three dimensional space into a planar shape. First the definition of planar development of a curved surface is presented, and the distortions (at length and area) of development are discussed in this paper. Then several planar flattening methods of curved surface, and their advantages and disadvantages are analyzed in detail. For NURBS(non uniform rational basic spline) surfaces, which are broadly used in CAGD, we put forward a new planar developing algorithm, i.e. hybrid developing, and present the steps of the algorithm. At last, some examples are used to show the effectiveness of the algorithm.

A NOTE ON STRONG EMBEDDINGS OF MAXIMAL PLANAR GRAPHS ON NON ORIENTABLE SURFACES

In this paper, it is shown that for every maximal planar graph G=(V,E) , a strong embedding on some non orientable surface with genus at most |V(G)|-22 is admitted such that the surface dual of G is also a planar graph. As a corollary, an interpolation theorem for strong embeddings of G on non orientable surfaces is obtained.

The surface plasmon polariton dispersion relations in a nonlinear-metal-nonlinear dielectric structure of arbitrary nonlinearity

The analytic surface plasmon polaritons （SPPs） dispersion relation is studied in a system consisting of a thin metallic film bounded by two sides media of nonlinear dielectric of arbitrary nonlinearity is studied by applying a generalised first integral approach. We consider both asymmetric and symmetric structures. Especially, in the symmetric system, two possible modes can exist： the odd mode and the even mode. The dispersion relations of the two modes are obtained. Due to the nonlinear dielectric, the magnitude of the electric field at the interface appears and alters the dispersion relations. The changes in SPPs dispersion relations depending on film thicknesses and nonlinearity are studied.

Giant Goos–Hnchen shifts of waveguide coupled long-range surface plasmon resonance mode

A hybrid structure based on a planar waveguide （PWG） mode coupling a long-range surface plasmon resonance （LRSPR） mode is proposed to enhance the GH shift. Both the PWG mode and LRSPR mode can be in strong resonance, and these two modes can be coupled together due to the normal-mode splitting. The largest GH shift of PWG-coupled LRSPR structure is 4156 times that of the incident beam, which is 23 times and 3.6 times that of the surface plasmon resonance （SPR） structure and the LRSPR structure, respectively. As a GH shift sensor, the highest sensitivity of 4.68 x 107 λ is realized in the coupled structure. Compared with the sensitivity of the traditional SPR structure, the sensitivity of our structure is increased by more than 2 orders, which theoretically indicates that the proposed configuration can be applied to the field of high-sensitivity sensors in the future.

用平面六边形割角的细分曲面生成方法

平面六边形是一种更契合自然并具有独特优点的多边形,找到一种方便实用的平面六边形细分格式是细分曲面研究领域中的基础工作之一。本文提出了一种平面六边形细分方法,对任意初始凸多面体网格,只用平面六边形进行割角细分,可以使得细分曲面光滑、保凸、具有插值性质,且细分过程中新增的面片都是平面六边形.我们将该方法简称为平面蜂窝细分.论文给出了平面蜂窝细分的拟线性四点格式几何规则及其细分矩阵,其几何意义直观,相应的算法简单、可行且数值稳定.论文分析了细分曲面的收敛性和光滑性,给出了C光滑性条件及其证明.为了提高细分曲面的光滑性,传统的方法是使边数不同的多边形面片按等比例收缩,该方法对于平面蜂窝细分没有预期效果并且无法处理三角形特殊面;论文给出了一种新方法,获得的割角参数使得细分曲面更加光滑,且可以统一处理三角形、四边形等特殊面,从而避免特殊点/面带来的局限性.论文还提出了平面蜂窝细分方法的一种推广和一种自然边界处理方法,并讨论了平直边界和退化情形下尖锐特征生成的方式,可用于细分任意可定向初始网格.文中给出了一些细分曲面的例子,并与经典的细分方法进行了比较,验证了新方法的有效性和具有的优点.

采用PSG牺牲层的空腔结构平坦化工艺

对基于微机电系统(MEMS)采用磷硅玻璃(PSG)牺牲层的空腔结构平坦化工艺进行了研究。探讨了抛光液体积流量、抛光压力、抛光液种类对牺牲层抛光速率、均匀性和硅槽台阶高度的影响,并对膜层表面质量进行分析和表征。结果表明:二氧化硅类抛光液体积流量控制在120 mL/min,此时抛光速率最高且有利于节约成本;优化了抛光压力工艺参数,当晶圆背压和保持环压力之比为0.76,即当晶圆背压为320 g/cm^(3),保持环压力为420 g/cm^(3)时,可有效地改善牺牲层薄膜的均匀性;引入二氧化铈类抛光液,采用两步抛光工艺,即粗抛时采用二氧化硅类抛光液,精抛时采用二氧化铈类抛光液,可以得到较为理想的台阶高度差;最后将化学机械抛光(CMP)后牺牲层表面形貌进行表征,得到较为优异的牺牲层薄膜质量。

一种三维曲面二维平面化技术

随着计算机技术的不断发展,异形形体的建筑成为建筑设计师美学灵感在现实世界的直观体现。三维曲面作为异形建筑形体不可或缺的一部分,然而按照曲面曲率生产的非标构件在安装定位时往往存在定位困难和安装尺寸偏差较大等问题。针对这一问题,对一种三维曲面二维平面化方法进行了研究,使用该种方法生成的二维单元板块模型进行精确定位和尺寸计算可以指导施工建造,避免了工程材料的浪费。验证结果表明:项目案例中采用在Grasshopper中控制划分数量后通过连接3个或4个单元角点的方式生成了有缝隙和无缝隙的2类二维平面单元板块,验证了该种方法具备较好的应用可行性。同时,分析了该种方法在应用过程中存在的问题并给出了解决方法,为三维曲面二维平面化提供了一种技术思路。

Effect of polishing parameters on abrasive free chemical mechanical planarization of semi-polar(1122) aluminum nitride surface

An abrasive free chemical mechanical planarization（AFCMP） of semi-polar（1122） Al N surface has been demonstrated. The effect of slurry p H, polishing pressure, and platen velocity on the material removal rate（MRR） and surface quality（RMS roughness） have been studied. The effect of polishing pressure on the AFCMP of the（1122） Al N surface has been compared with that of the（1122） Al Ga N surface. The maximum MRR has been found to be 562 nm/h for the semi-polar（1122） Al N surface, under the experimental conditions of 38 k Pa pressure,90 rpm platen velocity, 30 rpm carrier velocity, slurry p H 3 and 0.4 M oxidizer concentration. The best root mean square（RMS） surface roughness of 1.2 nm and 0.7 nm, over a large scanning area of 0.70×0.96 mm^2, has been achieved on AFCMP processed semi-polar（1122） AlN and（AlGaN） surfaces using optimized slurry chemistry and processing parameters.

SOME APPLICATIONS OF PLANAR GRAPH IN KNOT THEORY

The relationship between a link diagram and its corresponding planar graph is briefly reviewed. A necessary and sufficient condition is given to detect when a planar graph corresponds to a knot. The relationship between planar graph and almost planar Seifert surface is discussed. Using planar graph, we construct an alternating amphicheiral prime knot with crossing number n for any even number n 〉 4. This gives an affirmative answer to problem 1.66（B） on Kirby＇s problem list .

A PLANAR ANTENNA OF CONDUCTOR MODULATING PERIODIC STRUCTURE

A novel planar leaky-wave antenna of conductor modulating periodic structure formillimeter wave application is proposed.Using the theory of two-dimensional periodic admittancesurface,theoretical analysis,numerical calculation and experimental study are carried out for thiskind of antenna.A planar antenna of conductor modulating periodic structure is realized in 8mmwave band.It has an aperture area of 90×90mm^2.The measured performances of the antennaare good.

Planar-busting Curves on the Boundary of a Handlebody

Let Hn be an orientable handlebody of genus n. It has been proved that for n not less than 2, there exists an annulus-busting curve in δHm. In the present paper, we prove that for n not less than 2, there exists an essential simple closed curve C in OHm which intersects each essential planar surface in Hn non-emptily. Furthermore, we show that for n not less than 3, a pants-busting curve must also be an annulus-busting curve.

基于平面电极的非球面双液体透镜的设计与分析

为了研究易于实现、结构简单的非球面液体透镜结构,应用介电泳效应,设计了一款基于平面电极的非球面双液体透镜.利用Comsol,Matlab和Zemax软件,建立了所提出的非球面双液体透镜模型,分析了其在不同电压下的面型变化与成像特点,并与球面的双液体透镜模型进行了比较分析.结果表明,非球面双液体透镜的变焦范围大于球面的,前者的成像质量亦优于后者.而且,通过该非球面双液体透镜的器件制备与初步实验分析,获得了其成像分辨率可达40.318 lp/mm的结果.

三氯化铁-草酸体系不锈钢化学机械抛光液设计与优化

为提高柔性显示衬底不锈钢箔片化学机械抛光加工效率,研制一种三氯化铁-草酸型抛光液并用于304不锈钢衬底的化学机械抛光加工过程。设计正交优化试验,确定磨粒粒径、磨料含量、草酸含量和三氯化铁含量对材料去除率和表面粗糙度(S_(a))的影响显著性顺序,并重点探究三氯化铁和草酸对材料去除率的影响规律。利用优化后的抛光液精抛304不锈钢,其材料去除率高于560 nm/min,抛光30 min后Sa低于8 nm。相比现有抛光液的材料去除效率(226.56 nm/min),新抛光液的加工效率提升超过1倍。

一种通用的电路基本割集直接确定方法

实现了一种通用的电路基本割集直接确定方法,该方法依据自行定义的节点-节点关系矩阵、节点平面坐标矩阵以及支路分配规则,将原有向图改画为支路彼此不相交的三维有向图,通过三维闭合曲面切割,最终在三维空间形象地显示各基本割集及其方向,便于学生的直观理解。这种方法既适用于复杂的非平面电路,也可用于简单的平面电路,弥补了教材中现有方法(闭合平面切割法和依据定义的排除法)的不足。

增材制造数字化模型平面与非平面切片及路径规划研究进展

增材制造技术基于“离散-堆积”原理,通过对三维数字化模型进行数据预处理、切片与路径规划,并生成增材系统可识别的执行代码,驱动增材设备实现零件的快速制造,近年来,该技术在航空航天、汽车、船舶、医疗、建筑等行业得到了广泛应用。切片与路径规划是增材制造三维数字化模型数据处理的核心步骤,决定着制造过程的工艺变量、零件形状精度和性能。首先综述了目前增材制造中基于CAD模型、点云模型、STL模型、体素模型等多种数字化模型切片方法研究进展,并从各模型生成精度、切片算法原理、算法效率等方面展开了评述;其次,对平面与非平面的等厚度、变厚度、变方向及分区组合等多种切片算法,以及平面单区域、多区域、局部特征及非平面等多种路径规划算法进行了综述,初步分析和梳理了切片及路径规划算法的设计要点;最后,总结了目前增材制造数字化模型平面与非平面切片及路径规划的研究现状,并对其发展趋势进行了展望。

电子定域策略在实现平面四配位结构中的适用性:氮与碳的对比研究

本文通过对含有平面四配位氮团簇NLi_(3)E^(+)(E=N,P,As)和它们的平面四配位碳等电子体CLi_(3)E(E=N,P,As)进行详细地对比,研究了电子定域策略在设计含平面四配位氮团簇时的适应性.结果表明,NLi_(3)E^(+)团簇具有类似于CLi_(3)E的平面结构,且其平面性都是由一个定域的π键决定的.然而,与CLi_(3)E相比,NLi_(3)E^(+)明显具有更高的电子结构稳定性、热力学稳定性和动力学稳定性,这可以从更宽的HOMO-LUMO能隙(4.58~4.68 eV vs.2.10~2.74 eV)在CCSD(T)/aug-cc-pVTZ水平下较低的能量和DFT水平下的分子动力学模拟中表现出的更好刚性得到验证.结果表明,电子定域策略可能更适合设计中心原子为较高电负性且更倾向于形成定域键的平面多配位分子.在这些团簇中,NLi_(3)E^(+)的稳定性最好,更适合进行气相合成及后续的质谱选择和光谱表征.

带有平面边界凸曲面的无穷小刚性对偶问题的可解性

本文重新讨论了一类带有平面边界的凸曲面的无穷小刚性问题.找到该线性化等距嵌入系统和齐次线性化Gauss-Codazzi系统之间的对偶关系.主要找到了齐次线性等距嵌入系统的对偶问题及对偶边界条件,并证明了其具有非平凡解,再次验证了该类凸曲面具有无穷小非刚性。

Infinitesimal nonrigidity of convex surfaces with planar boundary

In the present paper infinitesimal nonrigidity of a class of convex surfaces with planar boundary is given. This result shows that if the image of the Gauss map of an evolution convex surface with planar boundary covers some hemisphere, this surface may be of infinitesimal nonrigidity for the isometric deformation of planar boundary.