传输密度的L^(p,q)估计

研究了与两个概率测度μ和v之间的最优计划γ有关的传输密度σ_(γ)的绝对连续性和L^(p,q)可和性.更确切地说,如果μ∈L^(p,q),其中1≤p<+∞,1≤q<+∞以及v的支撑集合为有限点集,则有σ_(γ)∈L^(p,q).本文的证明主要利用经由位移内插μ_(t)给出了σ_(γ)的等价定义公式,σ_(γ)与μ_(t)的关系不等式,以及对位移内插μ_(t)进行的L^(p,q)估计.

基于遗传算法的网络传输异常数据检测方法

针对网络传输过程异常数据与标准数据之间存在相对误差的问题,提出基于遗传算法的网络传输异常数据检测方法。通过遗传网络布局形式,建立标准的遗传适应度函数,利用数据编码标签,处理异常数据;通过定义网络传输数据异常簇点的方式,确定数据信息的传输密度水平,结合相关性检测阈值,实现网络传输异常数据检测。实验结果表明,设计方法的异常数据校正误差指标的最大值未超过2.0×10-3MB,得出该方法有效降低了误差。

FIFO缓冲器在高密度传输中的应用

先进先出缓冲器(FIFO)可用于连接不同时钟的运算组件,作为资料传送的缓冲。HBA 投放的ChannelQ产品提供信道管理的功能,可在一个组件中提供多个 FIFO 缓冲的功能,对于高密度的通讯适配卡、视频卡、及控制卡,提供一个省空间、廉价、灵活管理、低功耗及稳定的FIFO解决方案。 电信设备朝高密度发展 对于电信运营商而言,网络应用需求的迅猛成长带来许多新商机,但是也带来许多技术操作及管理的困难。

弱网环境及人群高密度活动场景下使用聚合传输设备实现安全直播的研究

随着通信基础设施的完善以及网络编码传输设备的发展,使用多网聚合设备进行直播已成为电视台外场直播的重要技术手段,这给在弱网环境以及人群高密度的大型活动场景中直播信号的高质量传输带来严峻挑战。本文以杭州市广播电视台的实践为例,在设备技术、性能层面以及使用过程中的技巧和策略2个方面对弱网环境及人群高密度活动场景下的直播信号传输进行深入探讨。

融合大数据算法的网络信息安全系统设计

针对网络信息安全造成的损失,采用DM9000型号的以太网芯片作为控制器的主芯片,将网卡地址存放在具有可更改属性的只读存储器中,支持网络信息的加密传输。利用压缩感知的网络数据传输中心高密度信息安全存储方法,实现了网络数据高密度传输,并对信息安全存储。通过RSA算法和CBC算法实现数据信息的加密。试验结果表明,网络信息安全加密保护加密过程中平均耗时1500 ms左右,并且加密保护被解密数据所占比最低,在6%以下。系统安全性能高,并且运行速度快。

基于数字签名的实时数据流认证方法研究

针对实时数据流认证的时效性需求,研究了基于数字签名的实时数据流认证方案。在散列函数和数字签名技术的基础上,根据实时数据流的传输特点,提出了认证窗口的思想,设计了三种实时数据流认证方案,第一种方案由数据包自带认证信息;第二种方案由后数据包带前包认证信息;第三种方案由前数据包带后包认证信息。给出了各方案的认证结构和流程,并进行了仿真分析,分别从传输密度和认证窗口两个方面来研究认证效率,结果表明:在不同的传输密度条件下,各种方案各具优势,因此,应根据实时数据流的传输密度来动态选择认证方案和认证窗口,提高认证效率。

新建他激反激变换器方程及其解析解

本文引用文[1]的思路,寻找他激反激变换器的运行状态特征参量(磁通密度增量、剩余磁通密度和PWM占空比)与构成这一变换器的基本物理参量之间的函数关系。首先阐明由于频率给定,他激反激变换器稳态运行时会出现无剩磁工况和有剩磁工况两种。而后确定这两种工况下,磁路等效储能空间单位体积每个周期的传输能量(命名为"磁能传输密度")。在这基础上,分别建立和解出他激反激变换器在不同工况下稳定运行时应满足的方程。最后根据所得的解析解阐明这种变换器的特性。本文和文[1],以磁路分析为基础建立了一种新的反激变换器理论。

基于分形曲线近零密度声学超材料的声波调控研究

结合空间卷曲理念和分形自相似原理,提出了一种具有“之”字型特征的空间卷曲型声学超材料,利用等效参数法提取了该分形声学超材料结构单元的等效质量密度,结果表明,在特定的频率范围内该分形结构单元具有近零密度特性。有限元法分析结果表明,利用该近零密度分形结构单元进行特定的周期性排列后组成的声学超材料,可以在特定频率范围内实现高效调控声波的目的,例如实现声隐身、声隧穿、弯曲狭缝传输和波前整形,同时分析了这些声特殊现象的出现与近零密度声学超材料透射系数峰值频率的对应关系。最后进行了试验验证,利用3D打印技术加工制得1阶、2阶近零密度声学超材料单元样品,并测试其透射系数,通过对比可知,实测结果和有限元分析结果符合良好,证明了结果的准确性和所设计结构的有效性。

先驱,“驱”向不明?

光驱,驱动数字化进程 如果以1982年CD—DA正式推向市场为基准,纵观光存储产业发展历程,怎一个快字了得。CD—DA,即激光数字视盘一经问世即风摩全球。

基于Peano分形的亚波长尺度声学超材料

基于Peano分形曲线设计了亚波长尺度的二维分形结构,该结构在特定频率范围内具有负质量密度和负体积模量,利用S参数法和传递矩阵的方法计算出等效质量密度和等效体积模量。基于有限元方法研究了分形结构在特定频率范围内声波的调控特性如近零密度传输、声隐身、声隧穿和波前整形等,分析了这些声特性与分形结构透射系数峰值频率的对应关系。基于3D打印技术制作了分形结构样品,实测的透射系数与计算分析结果有很好的一致性,说明了分析方法的有效性。结果表明,设计出的超材料有着特殊的声学参数,在[0,1 600]Hz内有多条带隙,可以用于低频下的滤波和声调控。

Phase Transition for a Mixed Spin-1／2 and Spin-sB System with a Transverse CrystalField

The critical behaviors of a mixed spin-1/2 and spin-sB Ising system with a transverse crystal field are studiedby use of the effective-field theory with correlations. The effect of the transverse crystal field on transition temperaturesis investigated numerically for the honeycomb (z = 3) and square (z = 4) lattices. The results show that there is notricritical point for the system.

Effect of Dissipative Environments on Atomic-State Quantum Teleportation

In the paper, taking the atomic EPR entanglement of quantum teleportation of atomic state in thermal environment damping-density operator approach, and the average fidelities are channel state ｜φ = （1/√2）（｜00） ＋ ｜11〉） is more robust than ｜φ｜ they are subject to the dissipative environments. states as quantum channel, we investigate the fidelity and vacuum reservoir by means of quantum theory of calculated, the results show that the atomic quantum = （1/√2）（｜01〉 ＋ ｜10〉） in teleportation process when they are subject to the dissipative environments.

Superstructured α-Fe2O3 nanorods as novel binder-free anodes for high-performing fiber-shaped Ni/Fe battery

Fiber-shaped energy storage devices are indispensable parts of wearable and portable electronics.Aqueous rechargeable Ni/Fe battery is a very appropriate energy storage device due to their good safety without organic electrolytes, high ionic conductivity, and low cost. Unfortunately, the low energy density,poor power density and cycling performance hinder its further practical applications. In this study, in order to obtain high performance negative iron-based material, we first synthesized a-iron oxide(α-Fe2O3) nanorods(NRs) with superstructures on the surface of highly conductive carbon nanotube fibers(CNTFs), then electrically conductive polypyrrole(PPy) was coated to enhance the electron, ion diffusion and cycle stability. The as-prepared α-Fe2O3@PPy NRs/CNTF electrode shows a high specific capacity of 0.62 Ah cm-3 at the current density of 1 A cm-3. Furthermore, the Ni/Fe battery that was assembled by the above negative electrode shows a maximum volumetric energy density of 15.47 mWh cm-3 with228.2 mW cm-3 at a current density of 1 A cm-3. The cycling durability and mechanical flexibility of the Ni/Fe battery were tested, which show good prospect for practical application. In summary, these merits make it possible for our Ni/Fe battery to have practical applications in next generation flexible energy storage devices.

Decorating graphdiyne on ultrathin bismuth subcarbonate nanosheets to promote CO_(2)electroreduction to formate

Electrocatalytic reduction of CO_(2)is one of the most attractive approaches for converting CO_(2)into valuable chemical feedstocks and fuels.This work reports a catalyst comprising graphdiyne-decorated bismuth subcarbonate(denoted as BOC@GDY)for efficient electroreduction of CO_(2)to formate.The BOC@GDY shows a stable current density of 200 mA cm^(-2)at–1.1 V in a flow cell configuration,with a faradaic efficiency of 93.5%for formate.Experimental results show that the synergistic effect in BOC@GDY is beneficial for the CO_(2)adsorption affinity,the reaction kinetics and the selectivity for formate.In addition,in-situ X-ray absorption and Raman spectroscopy indicate that the electron-rich GDY could facilitate the reduction from Bi(Ⅲ)to Bi(0),thus leading to more active sites.We also demonstrate that the promoting effect of GDY in CO_(2)electroreduction can be further extended to other metal catalysts.To the best of our knowledge,such general promoting functions of GDY for CO_(2)electroreduction have not been documented thus far.

Manipulate energy transport via fluorinated spacers towards recordefficiency 2D Dion-Jacobson CsPbI_(3) solar cells

Two-dimensional(2D)Dion-Jacobson(D-J)-type cesium lead iodide CsPbI_(3) perform remarkably in terms of stability.However,the complex interactions between spacer and inorganic layers limit its excellent progress in perovskite solar cells(PSCs).Herein,starting from the considerable structural diversity of organic spacers,we engineer 2D CsPbI_(3) with fine-tuning functionalities.Specifically,for the first time we embedded fluorinated aromatic cations in 2D D-J CsPbI_(3),and successfully applied it into construction of high-performance PSCs.Compared with constitutive 1,4-diaminobenzene(PDA),the fluorinated 2-fluorobenzene-1,4-diamine(F-PDA)component greatly expands the dipole moment from 0.59 D to 3.47 D,which reduces the exciton binding energy of the system.A theoretical study shows that the spacer layer and inorganic plane are more enriched with charge accumulation in(F-PDA)Csn±1 Pb_(n)I_(3n+1).The results show that(F-PDA)Csn±1Pb_(n)I_(3n+1) demonstrates more significant charge transfer between organic and inorganic layers than(PDA)Csn±1 Pb_(n)I_(3n+1),and it is confirmed in the femtosecond transient absorption experiment.Moreover,the interactions of the fluorinated spacer with the[PbI_(6)]_(4)-plane effectively manipulate the crystallization quality,and thus the ion migration and defect formation of target 2D CsPbI_(3) are inhibited.As a result,we obtained a record power conversion efficiency(PCE)beyond 15%for 2D D-J(F-PDA)Cs_(3)Pb_(4)I_(13)(n=4)PSCs with significantly improved environmental stability compared with the three-dimensional(3D)counterparts.

Profile-broaden ultraviolet lasing from whispering gallery mode cavity in crown-like zinc oxide

The crown-like zinc oxide(Zn O)samples,which are composed of a hexagonal cap and a tower-like shaft,are prepared by vapor transport method.The hexagonal cap,working as a whispering gallery mode(WGM)resonant cavity,demonstrates density-dependent ultraviolet(UV)lasing emission with a broadened and squared photoluminescence(PL)profile under UV excitation at 355 nm.Theoretical analyses based on Fermi golden rule show that the broadened spectrum profile results from the special optical mode density characteristics in a WGM micro-cavity,which is in agreement with the observed results.

Massless and Massive Particle-in-a-Box States in Single- and Bi-Layer Graphene

Electron transport through short, phase-coherent metal-graphene-metal devices occurs via resonant transmission through particle-in-a-box-like states defined by the atomically-sharp metal leads. We study the spectrum of particle-in-a-box states for single- and bi-layer graphene, corresponding to massless and massive two-dimensional （2-D） fermions. The density of states D as a function of particle number n shows the expected relationships D（n） -n1/2 for massless 2-D fermions （electrons in single-layer graphene） and D（n） -constant for massive 2-D fermions （electrons in bi-layer graphene）. The single parameters of the massless and massive dispersion relations are found, namely Fermi velocity vF = 1.1 × 10^6 m/s and effective mass m＊ = 0.032 me, where me, is the electron mass, in excellent agreement with theoretical expectations.

Time-dependent density functional theory for quantum transport

The rapid miniaturization of elect, ronic devices motivates research interests in quantum transport.Recently time-dependent quantum transport has become an important research topic. Here we re- view recent progresses in the development of time-dependent density-functional theory for quantum transport including the theoretical foundation and numerical algorithms. In particular, the reducedsingle electron density matrix based hierarchical equation of motion, which can be derived from Liouville---von Neumann equation, is reviewed in details. The numerical implementation is discussed and simulation results of realistic devices will be given.

Eliminating the electric field response in a perovskite heterojunction solar cell to improve operational stability

Intrinsic and extrinsic ion migration is a very large threat to the operational stability of perovskite solar cells and is difficult to completely eliminate due to the low activation energy of ion migration and the existence of internal electric field.We propose a heterojunction route to help suppress ion migration,thus improving the operational stability of the cell from the perspective of eliminating the electric field response in the perovskite absorber.A heavily doped p-type(p^(+))thin layer semiconductor is introduced between the electron transporting layer(ETL)and perovskite absorber.The heterojunction charge depletion and electric field are limited to the ETL and p^(+)layers,while the perovskite absorber and hole transporting layer remain neutral.The p^(+)layer has a variety of candidate materials and is tolerant of defect density and carrier mobility,which makes this heterojunction route highly feasible and promising for use in practical applications.