Tunable dual-band nearly perfect absorption based on a compound metallic grating

Traditional metallic gratings and novel metamaterials are two basic kinds of candidates for perfect absorption. Comparatively speaking, metallic grating is the preferred choice for the same absorption effect because it is structurally simpler and more convenient to fabricate. However, to date, most of the perfect absorption effects achieved based on metamaterials are also available using an metallic grating except the tunable dual(multi)-band perfect absorption. To fill this gap, in this paper, by adding subgrooves on the rear surface as well as inside the grating slits to a free-standing metallic grating, tunable dual-band perfect absorption is also obtained for the first time. The grooves inside the slits is to tune the frequency of the Cavity Mode(CM) resonance which enhances the transmission and suppresses the reflectance simultaneously. The grooves on the rear surface give rise to the phase resonance which not only suppresses the transmission but also reinforces the reflectance depression effect. Thus, when the phase resonance and the frequency tunable CM resonance occur together, transmission and reflection can be suppressed simultaneously, dual-band nearly perfect absorption with tunable frequencies is obtained. To our knowledge, this perfect absorption phenomenon is achieved for the first time in a designed metallic grating structure.     

审美教育与大学建筑环境艺术的关系

审美教育是健全人格养成的重要途径,处于不可替代的重要地位.如今审美教育在高校被关注的形式主要是开设各种素质课程,然而如何更进一步拓宽学生的审美情趣,潜移默化地对他们进行美学熏陶是我们要探讨的问题.校园是大学精神的物质载体,学生在艺术氛围浓郁的环境中生活学习,他们对艺术的理解和鉴赏能力必然会逐步提高.在这方面,大学建筑环境艺术具有潜移默化的影响力.     

Analysis of release kinetics of ocular therapeutics from drug releasing contact lenses: Best methods and practices to advance the field

Several methods have been proposed to achieve an extended and controlled release of ocular therapeutics via contact lenses; however, the experimental conditions used to study the drug release vary greatly and significantly influence the release kinetics. In this paper, we examine variations in the release conditions and their effect on the release of both hydrophilic and hydrophobic drugs (ketotifen fumarate, diclofenac sodium, timolol maleate and dexamethasone) from conventional hydrogel and silicone hydrogel lenses. Drug release was studied under different conditions, varying volume, mixing rates, and temperature. Volume had the biggest effect on the release profile, which ironically is the least consistent variable throughout the literature. When a small volume (2–30 mL) was used with no forced mixing and solvent exchange every 24 h, equilibrium was reached promptly much earlier than solvent exchange, significantly damping the drug release rate and artificially extending the release duration, leading to false conclusions. Using a large volume (200–400 mL) with a 30 rpm mixing rate and no solvent exchange, the release rate and total mass released was significantly increased. In general, the release performed in small volumes with no force mixing exhibited cumulative mass release amounts of 3–12 times less than the cumulative release amounts in large volumes with mixing. Increases in mixing rate and temperature resulted in relatively small increases of 1.4 and 1.2 times, respectively in fractional mass released. These results strongly demonstrate the necessity of proper and thorough analysis of release data to assure that equilibrium is not affecting release kinetics. This is paramount for comparison of various controlled drug release methods of therapeutic contact lenses, validation of the potential of lenses as an efficient and effective means of drug delivery, as well as increasing the likelihood of only the most promising methods reaching in vivo studies.     

一种多级混沌同步通信系统

本文了蔡氏混沌同步通信系统的主要性质和局限性，提出了一种多级混沌安全通信系统，证明了该系统对传输信号可以完全重建，在有效带宽，失真特性及安全性和方面获得了改善。文中出了给利用该系统进行语音数据和静止图像数据传输的实例。     

从禅宗到迷宫般的沉醉：圆明园狮子林与苏州狮子林的历史与美学交往

18世纪后期,清高宗乾隆帝在北京圆明园的长春园北侧建造狮子林和西洋楼两处园林。他的狮子林仿建了以假山迷宫闻名的苏州名园狮子林,而西洋楼包含着一个巴洛克式迷宫与错觉透视的戏台。通过对元代至清代有关2个狮子林园的诗词和园记的现象学感知分析与历史诠释学解读,揭示了苏州狮子林园从元代的禅宗空间到明代的幻境,再到清代的沉醉迷宫的美学变迁,以及其对当代精神空间塑造的历史启迪与文化含义。     

具有几乎完美代数免疫的偶数元弹性函数构造

完美代数免疫(PAI)的布尔函数能够抵御代数攻击和快速代数攻击。PAI函数的构造是目前布尔函数研究最具挑战性的问题之一。利用布尔函数的双变元表达式和有限域理论,基于Carlet-Feng函数提出一种新的偶数元布尔函数的一般性构造。证明由该构造得到的函数具有一阶弹性和至少次优代数免疫度等密码学性质,给出其代数免疫度达到最优时的充分条件,并比较该类函数、Carlet-Feng函数和由一阶级联方式构造的函数在6~16之间的所有偶数变元下抵抗快速代数攻击能力。实验结果表明,该类函数能更好地抵抗快速代数攻击,且具有几乎完美的代数免疫性能。     

环境影响评价公众参与存在问题及完善对策研究

公众参与是环境影响评价过程中的重要部分,在环评中发挥着特殊作用。针对目前我国环境影响评价中公众参与的实施情况,本文对环境影响评价公众参与存在问题进行总结,并分析原因与借鉴国外经验,提出了颁布公众参与导则、健全环境信息公开制度、实施全过程的公众参与和切实保障公众参与的效力以及强化公众参与意识等完善对策。     

Uniform antiplane shear stress inside an anisotropic elastic inclusion of arbitrary shape with perfect or imperfect interface bonding

We consider an anisotropic elastic inclusion of arbitrary shape embedded inside an infinite dissimilar anisotropic elastic medium (matrix) subjected to a uniform antiplane shear loading at infinity. In contrast to the corresponding results from linear isotropic elasticity, we show that for certain anisotropic materials, despite the limitation of perfect bonding between the inclusion and its surrounding matrix, it is possible to design an arbitrarily shaped (not necessarily elliptic) inclusion so that the interior stress distribution is uniform provided the shear stress in the matrix (of dissimilar anisotropic material) is also uniform. Further, in the case when the bonding between the inclusion and the matrix is assumed to be imperfect, we show that for the stress distribution inside the inclusion to be uniform, the inclusion must be elliptical.     

Efficient parallel and sequential algorithms for 4-coloring perfect planar graphs

We present an efficient algorithm for 4-coloring perfect planar graphs. The best previously known algorithm for this problem takesO(n ^3/2) sequential time, orO(log⁴ n) parallel time withO(n³) processors. The sequential implementation of our algorithm takesO(n logn) time. The parallel implementation of our algorithm takesO(log³ n) time withO(n) processors on a PRAM.