Facsimile's false starts

The development of the 150-year-old facsimile concept is recounted. The factors that have made it such a popular technology are examined. Its evolution from use in niche markets only to broader use, and the shift of initiative in developing the technology to Japan in the 1980s, are discussed. Standards setting, advantages of facsimile, and legal issues are addressed     

On a recent stability conjecture

A recent conjecture on stability [1] is verified for a class of second-order systems and for a third-order system model.     

一九九八年狮子座强流星雨

１９９８年我国首次开展了了座强流量雨及其电离效应的无线电视测，结合国际流星组织收集的３８个国家的光学流星观测资料，初步证实：ａ）１９９８年狮子座强流星雨发生了爆发；ｂ）无线电流星最大出现率在２５００次／小时；ｃ）电离效应显著；ｄ）火流星，无线电流星和ｆｂＥｓ异常峰的峰值时刻差达１７－１９ｈ。由此推论；ａ）１９９８年狮子座流量雨发生了３次 “爆发”，其爆发的峰值时间分别是：１７日９：４０；１８日３：     

The strong converse theorem for hypothesis testing

The authors present the answer to a so-called converse problem by giving the explicit form of the power exponent. This strong converse should be regarded as completing a weak converse previously obtained by R.E. Blahut (1974)     

网络民航事件虚假评论的识别研究

互联网的开放性使得当前对于互联网上用户的评论内容没有质量控制机制,用户发表的内容中存在大量虚假评论,如何识别这些虚假评论信息成为重要问题。运用信息增益（ Information Gain, IG）,支持向量机（ Support Vector Machine, SVM）等方法对民航事件的评论进行特征提取和分类,识别虚假评论。通过对比4种不同的核函数,本文选定基于RBF核函数的SVM分类器进行虚假信息的分类识别,其F?measure值为90％,具有较优的分类效果。     

Two counterexamples to ?iljak's conjecture

?iljak's conjecture concerning the existence of the positive-definite symmetric solution with non-negative elements of the matrix Lypunov equation is shown to be not true in the general case. Two counterexamples to it are given.     

The false image of a line current within a conducting half-space

We show that the fields from a current line source, within a conducting-half-space, are only inadequately characterized by a positive real image in the air region. Such an assumption or assertion, as employed in previous electromagnetic compatibility (EMC) studies, is called into question. Buried cables are mentioned in particular     

A counterexample to a Voronoi constellation conjecture

Voronoi constellations are of interest because it is possible to save on signal power by choosing a lattice for which the second moment of the Voronoi region is close to that of a sphere with the same dimensionality. A Voronoi constellation based on the lattice partition Λ/Λ_s is the set of points in some translate Λ+a that fall within the Voronoi region R(Λ_s). G.D. Forney, Jr. (1989) proposed an algorithm for constructing Voronoi constellations and conjectured that this algorithm minimized the average signal power. A two-dimensional counterexample, to Forney's conjecture is presented     

Counterexample to a conjecture in multiprocessor scheduling

A counterexample to a conjecture on an upper bound to the execution time of a graph of tasks by the longest-path scheduling algorithm is presented.     

A conjecture on iterated three-point median filter

We prove the following conjecture: the N times iterated three-point median filter (1,1,1)^N is equal to a weighted median filter; we also prove that the weighted median filter is unique in certain sense     

Two proofs of Pinsker's conjecture concerning arbitrarily varyingchannels

M.S. Pinsker (1990) conjectured the following theorem: for an arbitrary varying channel (AVC), every rate below the random code capacity is achievable with deterministic list codes of constant list size, if the average error criterion is used. Two proofs of this theorem are given     

On the main conjecture on geometric MDS codes

A new way to attack the main conjecture on MDS codes for geometric codes is proposed. In particular, the conjecture for codes arising from curves of genus one or two when the cardinal of the ground field is large enough is proven     

Dispersive constant false alarm rate receiver

Search radars require a constant false alarm rate (CFAR) receiver to compensate for changes in noise and clutter levels. A CFAR circuit is described which uses matched dispersive delay lines flanking a hard limiter. The circuit's operation is discussed and plan-position indicator (PPI) photographs are shown which illustrate its effectiveness.     

The strong law of large numbers for sequential decisions underuncertainty

Combines optimization and ergodic theory to characterize the optimum long-run average performance that can be asymptotically attained by nonanticipating sequential decisions. Let {X_t} be a stationary ergodic process, and suppose an action b_t must be selected in a space ℬ with knowledge of the t-past (X₀, ···, X_t-1) at the beginning of every period t⩾0. Action b_t will incur a loss l(b_t, X_t) at the end of period t when the random variable X_t is revealed. The author proves under mild integrability conditions that the optimum strategy is to select actions that minimize the conditional expected loss given the currently available information at each step. The minimum long-run average loss per decision can be approached arbitrarily closely by strategies that are finite-order Markov, and under certain continuity conditions, it is equal to the minimum expected loss given the infinite past. If the loss l(b, x) is bounded and continuous and if the space ℬ is compact, then the minimum can be asymptotically attained, even if the distribution of the process {X_t} is unknown a priori and must be learned from experience     

Verifications of the Kalman conjecture for irrational transfer functions

The sufficient conditions for the Kalman conjecture to be satisfied given by Fannin and Rushing [1] are relaxed in such a way as to allow their approach to be applied to irrational transfer functions. Specific results for a class of systems containing transportation lag are presented.     

Proof of Rueppel's linear complexity conjecture (Corresp.)

Rueppel has conjectured that, for allngeq 1, the subsequence consisting of the firstndigits of the binary sequence(1,1,0,1,0,0,0,1,0^{7},1,0^{15},1, cdots )has linear complexitylfloor (n + 1)/2 rightfloor. This conjecture is proved, and a minimum length generator is found for eachn. The proof utilizes properties of an element in an extension field of the field of rational functions over GF(2).     

A proof of the spherical homeomorphism conjecture for surfaces

The human cerebral cortex is topologically equivalent to a sphere when it is viewed as closed at the brain stem. Due to noise and/or resolution issues, magnetic resonance imaging may see "handles" that need to be eliminated to reflect the true spherical topology. Shattuck and Leahy present an algorithm to correct such an image. The basis for their correction strategy is a conjecture, which they call the spherical homeomorphism conjecture, stating that the boundary between the foreground region and the background region is topologically spherical if certain associated foreground and background multigraphs are both graph-theoretic trees. In this paper, we prove the conjecture, and its converse, under the assumption that the foreground/background boundary is a surface.     

Predicting and eliminating built-in test false alarms

Failures detected by built-in test equipment (BITE) occur because a BITE measurement noise or bias as well as actual hardware failures. A quantitative approach is proposed for setting built-in test (BIT) measurement limits and this method is applied to the specific case of a constant failure rate system whose BITE measurements are corrupted by Gaussian noise. Guidelines for setting BIT measurement limits are presented for a range of system MTBF (mean time between failures) times and BIT run times. The technique was applied to a BIT for an analog VLSI test system with excellent results, showing it to be a powerful tool for predicting tests with the potential for false alarms. It was discovered that, for this test case, false alarms are avoidable     

一场有源天线引起的"虚惊"

2006年8月23日,青岛国际帆船赛正在如火如荼地举行。青岛市无线电监测站在对青岛流亭机场VHF塔台频率进行日常监测时,在118.8MHz频段发现了