Self-lifting scheme: new approach for generating and factoring wavelet filter bank

The authors presents a new lifting scheme, the self-lifting scheme, and prove that self-lifted wavelets based on orthogonal or biorthogonal wavelets remain biorthogonal. In contrast to self-lifting, the existing lifting scheme can be called cross-lifting. Compared with cross-lifting, the self-lifting scheme provides new approaches for constructing biorthogonal wavelets, as well as factorising wavelet filter bank (WFB). For constructing wavelets, the self-lifting-based method updates one part of a wavelet filter by the other part of the same filter and obtains two updated filters in one pass, whereas the cross-lifting based method updates one filter by another filter and obtains one updated filter in one pass. To factorise WFB, self-lifting takes one part of a filter as the factor to decompose the other part of the same filter and obtains two factorised filters in one pass, whereas crosslifting based one takes one part of a filter as the factor to decompose the corresponding part of the other filter and obtains one factorised filter in one pass. Several examples show how to use self-lifting scheme to produce new wavelets with desirable properties, how to factorise complex WFBs into simple lifting filter banks, how to implement self-lifting-based discrete wavelet transform (WT) in z-domain and in time domain and why lifting-based WT is superior to convolution-based one.     

Comments on “General Fourier solution and causality inattenuating media” by R.E. Duren

For original paper, see IEEE Trans. Electromagn. Compat., vol.35, no.1, p.43-8 (1994). When applying mathematics to physical problems one must satisfy the mathematical axioms and in addition the physical laws. Neither the mathematical axioms nor the physical laws can be listed comprehensively, but one does not need to concern oneself too much with mathematical axioms as long as one does not make a mathematical mistake. The physical laws must be introduced into a mathematical model of a physical process, which implies that one must know which physical laws are important in any particular case and one must be sure to actually introduce them. Confusion is caused by the practice of using physical sounding terms in applied mathematics. For instance, R.E. Duren calls a function of time “causal” if it is zero for values of the time variable below a certain threshold. No law prevents one from doing so, but such “causal” functions have no evident connection with the causality law of physics and no results about physical causality should be derived from them. How does one know that the causality law is a physical law that has to be introduced and not a mathematical axiom that is satisfied as long as one calculates correctly? To answer this question the present author considers the causality law in the following form: every effect requires a sufficient cause that occurred a finite time earlier (Harmuth, 1993). The use of the term “time” shows that one is dealing with a physical concept. Pure mathematics has no time variable or spatial variable but it has complex variables     

NASA's master plan

This paper describes how the author's leadership team was asked to help identify NASA's core strengths and activities and think hard about how each of them supports their mission. The purpose of the exercise is focus-and also direction. If a program or activity doesn't support one of NASA's three key objectives, one has to ask why one is doing it, even if one may be doing it rather well. Once one has focused on the activities that do fit into NASA's mission, one must make sure one is managing them in the best way possible. The first task is to examine what NASA is doing and why it is doing it.     

属性约简簇的优化选择

属性约简是粗糙集的一个重要应用.一个数据集往往含有多个属性约简,人们一般用启发式算法找到其中的一个,再通过实验的方法验证其有效性.面对多个属性约简,人们往往难以区别,缺乏有效的手段选取最优或较优的属性约简.使用多种概念漂移的度量指标和信息损失的度量方法比较了同一个知识系统中不同Pawlak约简之间的区别与联系.提出了属性约简重心的概念,并研究其性质.实验结果显示,在众多的属性约简中,离重心最近的属性约简在分类准确率方面具有较大的优势.概念漂移的度量指标和信息损失的度量方法有助于区分不同的属性约简,属性约简的重心有助于在众多的属性约简中选择最优或较优的一个.     

Performance study of non-orthogonal multiple access (NOMA) with triangular successive interference cancellation

Wireless Networks - The non-orthogonal multiple access (NOMA) allows allocating one carrier to more than one user at the same time in one cell. It is a promising technology to provide high...     

Equivalence of a Nonoriented Line and a Pair of Oriented Lines in a Network

Equivalence of a nonoriented line and a pair of oriented lines (in the reliability-sene) is examined for four types of networks. Type I has one input node and one output node; type II has one input node and two or more output nodes; type II' has two or more input nodes and one input node; type III has two or more input nodes and two or more output nodes. For types I, II, II', every non-oriented line is equivalent to a pair of oriented lines with equal line-reliability. The result corresponds to the presumption that almost every one has taken for granted. However equivalence of such a replacement is not true for a type III network.     

A note on the evaluation of footnotes and other devices forbackground information in popular scientific texts

Do readers of popular scientific texts appreciate references to the original sources? If they do, which reference system is most preferred? In order to answer these questions, we did two experiments. In the first one, four versions of a short popular science article were created: one without references and three with references-one incorporated references in running text, one in a separated text block at the end, and one between parentheses. The parentheses version was rated highest. In the second experiment, two versions of another popular science article were evaluated: one with references in parentheses and one with references in footnotes. This time, the footnote version was rated highest. We conclude that there is reason to doubt the received wisdom that common readers prefer omitting references or incorporating them in running text. Readers seem to favor the ancient and much-maligned mechanism of the footnote for providing background information     

Microstrip Elliptic-Function Low-Pass Filters Using Distributed Elements or Slotted Ground Structure

This paper presents two microstrip elliptic-function low-pass filters, one using distributed elements and one using a slotted ground structure. The one using distributed elements consists of a microstrip line section in parallel with an interdigital capacitor; the other one using a slotted ground structure consists of a low-impedance microstrip line with a slotted ground structure cell under the center of the line. A transmission-line model and a full-wave simulation are used to calculate the inductance/capacitance values of the equivalent circuits. The design concept was validated through experiments showing good agreements with the full-wave simulated results.     

一种基于二分图最优匹配的镜头检索方法

镜头检索是基于内容的视频检索的重要内容.本文首次尝试将二分图的最优匹配用于镜头检索.与现有方法相比,本文提出的方法强调在一一对应的前提下,全面客观地度量两个镜头的相似度.把两个镜头的相似度度量建模为一个带权的二分图:镜头中的每一帧看成二分图的一个结点,两个镜头之间任意帧的相似值作为边的权值.在一一对应的前提下,利用最优匹配的Kuhn-Munkres算法求出该二分图的最大权,以此作为两个镜头的相似度.考虑到检索速度问题,提出了两个改进算法.实验对比结果证实了本文所提方法在镜头检索中的优异表现.     

Performance of distributed feedback lasers designed to favor the energy gap mode

Distributed feedback lasers with reflecting ends can support a mode in the energy gap that is exponentially confined to the end reflectors. This mode can become the lasing mode in a laser having one high reflecting and one low reflecting end. We have quantitatively compared the properties of such a laser to more conventional DFB lasers having two uncoated cleaved facets or one uncoated and one low reflecting facet. This comparison required computing a distribution of properties for each laser design because the phases of the two end reflections have random values. The gap mode is inherently compact, and the laser favoring this mode has extremely high single-mode selectivity, excellent quantum efficiency, and good resistance to external reflections, when only one Bragg length long. The conventional laser designs have less mode selectivity and require cavity lengths of about two Bragg lengths to reach their optimum performance.     

VBA在多Excel工作薄数据汇总的应用

利用Excel进行数据处理分析时,常需要对大量独立的具有相同表结构的原始工作薄中的数据进行汇总合并到一个工作薄的指定工作表中。通过VBA编程调用Excel对象在不打开源工作薄的情况下,将指定文件夹中所有工作薄中的某一工作表的数据汇总合并,并添加工作薄文件名称字段表明数据来源。可以将需要一天或几天重复性的打开-复制-粘贴等操作才能完成的任务,缩短为几分钟完成。     

Synthesis of oscillator circuits employing only one unity-gain amplifier

A simple method to synthesise oscillator circuits employing only one unity-gain amplifier is presented. It is shown that any oscillator formed by one inverting infinite-gain ideal amplifier looped back by a perfect band-reject filter will automatically give rise, through a simple transformation, to an oscillator circuit employing only one unity-gain amplifier. It is further shown that the passive network must be at least a third-order band-reject filter.     

Reliability model of series-parallel systems

Markov models are used to obtain closed form solutions of the reliability of a series-parallel system. The system consists of two identical equipment in series. Each equipment has one component. To improve equipment reliability, extra component is connected in parallel with the original one. Therefore; each equipment is considered as 2-component fault-tolerant one. The component has a Poisson failure, and a repair of contant rate. The system fails if at least one equipment is out of order.     

A comparison between two methods to generate 1/fγnoise

Two methods to design 1/f^γnoise generators are reviewed and compared. The first one sums Lorentzian spectra obtained from the thermal noises of some resistors each one with a capacitor in parallel; the second one performs a proper filtering of a white-noise source. In that case, more precise considerations and more complete design rules are given.     

New constant-current controlled astable multivibrator for generating sawtooth and square waves

This article presents a now constant-current controlled astable multivibrator in which only one resistor and one capacitor is used, the other elements being transistors. The circuit consists of a constant-current source and the multivibrator itself. The multivibrator is specifically designed to have a simple three-stage direct-coupled transistor amplifier, with the output of the third stage fed back to the first stage and a capacitor connected across any two collectors. The switching action takes place by means of that capacitor. Linear sawtooth and square waves are generated simultaneously at the transistor collectors. Since only one resistor and one capacitor are required, this circuit is practical with IC fabrication.     

High-speed CAVLC encoder for H.264/AVC using parallel zig-zag scanning

A high-speed context-based adaptive variable length coding (CAVLC) encoder for H.264/AVC is presented. Since CAVLC scans residues in a block one by one to obtain the statistics of the data to be encoded, it requires a large number of cycles. In the proposed scheme, two residues are scanned in one cycle to reduce scanning time by half.     

用国产光纤器件为量子密钥传送建立网络

量子密钥传产达可以从根本上解决密钥传送,分配过程中的安全问题,其安全发现上物理学的基本原理来保证。光纤信道是目前除了自由空间艰外唯一能够实用的量子信道。本文提出了一个用通用国产光纤通信器件建立量子密钥收发单元的实用方案,并用此收发单元建立了点对点的光纤量子信道和一对多的光纤量子密钥网络。实测此收发单元完全达到设计要求。     

DOA and phase error estimation using one calibrated sensor in ULA

A new method is presented to effectively estimate the direction-of-arrival of a source signal and the phase error of a uniform linear array. Assuming that one sensor (except the reference one) has been calibrated, the proposed method appropriately reconstructs the data matrix and establishes a series of linear equations with respect to the unknown parameters through eigenvalue decomposition. The unknown parameters can be determined directly by the least squares method. Unlike the conventional methods, the proposed method only requires one calibrated sensor, which may not be consecutively spaced to the reference one. The computational complexity analysis is given and the effectiveness of the proposed method is validated by simulation results.     

Exploiting the attenuation of fiber-optic passive taps to createlarge high-capacity LANs and MANs

A local- or metropolitan-area network (LAN or MAN) that exploits the power losses of fiber-optic passive taps so that wavelengths can be reused in different portions of the network is proposed. This wavelength reuse makes it possible to design a large, high-capacity, multichannel network with many concurrent transmissions. An arbitrary number of nodes is supported by allowing packets to take multiple hops, when necessary, to reach their destinations. In one example configuration, there are two closed circular loops of fiber, one for transmissions in the clockwise direction and one for counterclockwise transmissions. Each node has one passive tap (per fiber), which is used for both a fixed-wavelength transmitter and a fixed-wavelength receiver     

Negative Tap Photonic Microwave Filter Based on a Mach–Zehnder Modulator and a Tunable Optical Polarizer

A negative tap photonic microwave filter based on a Mach-Zehnder modulator (MZM) and a tunable optical polarizer is proposed. In the proposed filter, the output light from the MZM, after experiencing a time delay difference between the two orthogonal modes in a polarization-maintaining fiber, is sent to the tunable optical polarizer. By adjusting the dc bias of the MZM and the polarization angle of the tunable polarizer with respect to the two orthogonal modes, two positive or one positive and one negative coefficient are generated. A theoretical analysis is presented which is verified by experiments. A two-tap microwave filter with two positive or one positive and one negative coefficient is demonstrated.