不完备识别框架下的证据组合方法

证据理论应用中经常面临识别框架不完备问题。本文引入证据框架概念,把识别框架分为已知和未知两个部分,提出一种在识别框架不完备条件下表示和组合证据的开放识别框架方法。该方法能明确区分识别框架不完备与证据冲突两个不同概念,并合理解决了对未知命题集合的基本概率赋值问题,从而克服了D-S理论以及Smets的开放世界假设方法在处理不完备识别框架时存在的不足。     

Characteristics analysis and modeling of frame traffic in 802.11 wireless networks

In this paper, we analyze the impacts of different frame types on the self‐similarity and burstiness characteristics of the aggregated frame traffic in a real 802.11 wireless local area network (WLAN). We find that the impacts of different frame types are related to the mean frame sizes and the proportions of specified frame types in the aggregated frame traffic. Furthermore, we propose an analytical model to capture the relationship of self‐similarity characteristics between the aggregated frame traffic and different frame types. These new results provide an insight of frame traffic characteristics and some practical guidelines for developing new efficient algorithms to improve the common medium utilization and system throughput performance. Copyright © 2009 John Wiley & Sons, Ltd.     

Physical Frame Time-Slot Switching-A New Switching Technique over DWDM

The advent of dense wavelength division multiplexing (DWDM) raises the raw bit rate in a single fiber from a few Gigabits per second (Gbps) to tens of Terabits per second (Tbps), and enables the total bit rate in a single fiber reaching the order of magnitude of Tera bits. This achievement opens a new era for high-speed networks, and potentially, enables existing telephone, cable TV, and computer networks to be merged into a unified network. However, in a merged network, service requiremen…     

利用框架理论对信号进行重建

在Hilbert空间中讨论了框架的一些重要的性质,定义了一个框架算子,并讨论了该算子的性质。根据实际问题构造了一框架,使信号在此框架下的投影正好为非均匀采样值。给出了一种框架界的估计方法和重建原信号的迭代算法,最后,用仿真验证了此算法的有效性。     

Nonlocally Adaptive Pattern Classification Based Compressed Sensing for Video Recovery

Traditional video coding algorithms usually undergo several coding steps for each frame before transmission, which reduces the efficiency at the encoder. The compressed sensing (CS) as an innovative method in signal processing can make the encoder much easier than ever before, with which each frame only needs to multiply a projection matrix at the encoder, if the frame is sparse in a transform domain. Frames in a video usually exhibit sparsity in different parts on different bases; however, existing compressed sensing reconstruction methods usually recover a frame in a fixed set of bases for the entirety of the frame. Therefore, the frames cannot be recovered faithfully by the conventional CS reconstruction methods from a small number of measurements. In this paper, in order to rectify the flaw, we construct an initial estimation frame by motion estimation from neighboring frames and through the observation of the current frame. Then, nonlocally adaptive sparse signal presentation facilitation by a 2D piecewise autoregressive (AR) model is integrated into the reconstruction. The piecewise AR model is generated from the pattern classification of subimages of the initial estimation frame and its neighboring frames. An iterative procedure is proposed to recover a new estimated frame and its AR model alternatively, until the termination threshold is satisfied. The experimental results demonstrating the capabilities of the proposed method are presented.     

干涉测量框架结构设计及稳定性分析

干涉测量的面形重复精度一定程度上依赖于测量框架结构的稳定性,从测量框架高稳定性的使用要求出发,对测量框架的机械结构进行了设计。在此基础上针对检测框架在随机振动下的稳定性问题,建立了检测框架的有限元模型,以实际测量的随机振动速度功率谱密度(PSD)为激励,运用ANSYS有限元分析软件中的随机振动分析模块,对该结构的随机振动响应进行了分析计算。通过分析计算得出测量框架在随机振动下的稳定性为0.5144 nm,实验测量出5 s内的稳定性为0.653 nm,二者基本吻合。分析表明,测量框架的结构设计以及振动环境满足稳定性的指标要求。     

高速SDH帧同步系统性能与同步码组选择

介绍了高速 SDH系统中的帧同步器的设计 ,分析了影响帧同步器性能的参数选择。在分析的基础上 ,以 STM- 4为例选择帧同步器参数和帧同步码组 ,实现了一种应用于高速SDH系统的并行帧同步器的设计。     

Frame relay in public networks

Frame relay is a significant networking technology in the current data networking environment. Given its inherent advantages, it is particularly well-suited to LAN interconnection. In a public network, frame relay has key advantages for end users in terms of performance and cost efficiency. The effectiveness of frame relay in public networks, the management of public frame relay networks, the evolution from frame to cell services, and product implementations are discussed. The advantages frame relay has over existing technologies are described     

一种新颖的自适应帧同步器方案设计

在分析并讨论现有几种帧同步检出技术的基础上,提出了一种新颖的自适应帧同步器方案,并进行了参数设计。自适应帧同步器可以在不同的工作环境中保持最佳工作状态,因此是一种较为理想的帧同步器。     

Optimal tight frames and quantum measurement

Tight frames and rank-one quantum measurements are shown to be intimately related. In fact, the family of normalized tight frames for the space in which a quantum-mechanical system lies is precisely the family of rank-one generalized quantum measurements on that space. Using this relationship, frame-theoretical analogs of various quantum-mechanical concepts and results are developed. The analog of a least-squares quantum measurement is a tight frame that is closest in a least-squares sense to a given set of vectors. The least-squares tight frame is found for both the case in which the scaling of the frame is specified (constrained least-squares frame (CLSF)) and the case in which the scaling is chosen to minimize the least-squares error (unconstrained least-squares frame (ULSF)). The well-known canonical frame is shown to be proportional to the ULSF and to coincide with the CLSF with a certain scaling     

数码相框技术综述:专利视角

随着数字化时代的到来,数码相框技术应运而生,通过对数码相框历年的专利技术进行分析,得出数码相框的主要区域分布情况和在中国的技术发展演进路线.随着云技术和智能终端的兴起,总结出融入了云技术的多功能数码相框是未来数码相框的必然发展趋势,其将会在市场上占据主导地位.希望对国内企业在数码相框方面的技术研发提供一些思路.     

Performance Evaluation of a Variable Frame Multiplexer for Integrated Switched Networks

A scheme which multiplexes long messages and single packets using a time-varying frame is presented. Long messages, generated from a fixed number of terminals, immediately access a main trunk, sharing a dynamically dedicated subchannel in a roundrobin fashion. Fixed size packets arrive with Poisson statistics in a FIFO queue and are served through the same trunk, using the remaining capacity. The two traffic categories share an integrated variable length frame. The frame length is determined by the volume of the increasing traffic at the beginning of the frame and cannot exceed a maximum value. Analysis of the performance of the system is carried out using finite population round-robin processor sharing andM/G/Nqueueing techniques. Simplifying modeling assumptions are checked with simulation. A comparison with fixed frame schemes demonstrates the superiority of the variable frame, in terms of more efficient bandwidth utilization.     

甚低速视频编码中PB帧技术的研究

本文首先对甚低速视频编码H.263的PB帧技术和H.263+所采用IPB帧技术进行性能分析,在此基础上,提出一种简单有效的B帧选取方法(称之为B帧熵最大选取法),其基本思路是根据信息论熵值理论定义B帧的熵,并根据熵值来选择信息量最大、对暴露区补偿最有意义的B帧,实验结果表明该方法在保留了H.263+的IPB帧的优点的同时,可获得更优的补偿效果。     

基于图像融合的运动前景检测方法

提出了一种有效的运动前景检测方法。该方法根据图像融合思想,将背景帧与监控视频的当前帧在R,G和B颜色通道分别进行融合,形成包含背景帧和当前帧视觉信息的单一融合图像。之后根据背景区域与前景运动目标在饱和度上存在较大差异的现象,使用大津算法分割融合图像的饱和度分量图,形成运动前景二值图。经形态学处理后,形成了目标区域较完整、背景干净的运动前景检测图。实验结果显示,该算法具有较好的前景检测性能,解决了背景减法过分依赖背景帧的缺陷。     

单层高框架结构自振特性的激光全息干涉试验研究

一、引言单层高框架结构在一些工程中,比如在高空间厂房、中小型水电站等建筑物,应用比较普遍。该结构的抗震设计有其特殊性。我们应用激光全息干涉法进行了钢架式水电站厂房、重力坝和240m高拱坝等建筑物的自振特性的研究,并与动有限元法相法合对高拱坝结构动应力进行了分析研究。将这种方法应用于单层高框架结构厂房的自振特性研究是一种新的尝试。     

基于量子测量的紧框架构造方法研究

根据经典领域中的有限维紧框架研究量子领域中紧框架构造方法。由于紧框架与秩一广义量子测量有一一对应关系，在量子领域中设计了两种基于量子广义测量的紧框架构造方法。研究表明，这两种最优量子紧框架能分别解决两种基本的量子态区分策略：最小差错区分和最优无错区分。最小差错区分给定的一组向量，应用最小二乘准则，用广义量子测量方法构造了基于LSM的最优量子紧框架。这种最优量子紧框架分为两种情况：一种是给定框架界的最小二乘框架（CLSF），另一种是选择最优框架界的的最小二乘框架（ULSF），最优框架界能最小化最小二乘误差。还用量子广义测量方法构造了基于最优无错区分的量子紧框架。最后举例对比了以上最优紧框架构造方法，ULSF为最优有限维紧框架。     

Stationary frame current regulation of PWM inverters with zero steady-state error

Current regulators for AC inverters are commonly categorized as hysteresis, linear PI, or deadbeat predictive regulators, with a further sub-classification into stationary ABC frame and synchronous d-q frame implementations. Synchronous frame regulators are generally accepted to have a better performance than stationary frame regulators, as they operate on DC quantities and hence can eliminate steady-state errors. This paper establishes a theoretical connection between these two classes of regulators and proposes a new type of stationary frame regulator, the P+Resonant regulator, which achieves the same transient and steady-state performance as a synchronous frame PI regulator. The new regulator is applicable to both single-phase and three phase inverters.     

内容自适应的低复杂度多参考帧快速选择算法

针对移动视频业务的市场需求和移动终端设备的性能局限,提出了一种基于时空内容自适应的低复杂度多参考帧快速选择算法。在对视频序列编码模式采用率和参考帧时空相关性统计分析的基础上,根据时空相邻块最优参考帧的分布情况等信息,排除可能性较小的参考帧,缩小当前编码块的候选参考帧范围。并设定自适应的参考帧选择代价阈值,以判断是否需要扩大搜索范围。实验结果表明,该算法能大幅降低H.264的编码计算量,平均可降低49.12%的编码时间,而且基本保持编码率失真性能不损失。     

一种运动自适应的帧内插算法

本文提出了一种运动自适应的帧内插算法,可以用于逐行扫描的数字视频系统中做帧速率转换。该算法首先采用了线性预测块匹配搜索算法来估计内插帧中每一个象素的运动矢量;然后对得到的运动场进行中值滤波和判别,剔除运动不一致或错误的运动矢量;最后沿着运动轨迹线性内插得到内插帧的象素值。仿真分析表明本文提出的算法,在一个大的搜索区域进行快速搜索和判别,可以有效地解决内插帧中快速运动目标的运动模糊和有切换帧时的图象重叠,提高了帧速率转换中内插帧的主观视觉质量。     

帧同步码最佳码长在航空通信中的应用分析

帧同步码最佳码长的确定是航空移动通信中提高通信效率的重要问题。文中针对航空移动通信中某类帧同步码码长对帧长以及重复开销的影响,提出一种尾序列有限状态的分析方法,通过分析总平均开销与帧同步码码长、帧总长度的关系,获得不同帧长下的帧同步码最佳码长。并对不同帧长下帧同步码最佳码长进行仿真分析,仿真结果表明该方法行之有效。