Hybrid weighted bit flipping low density parity check decoding

Low density parity check codes (LDPC) exhibit near capacity performance in terms of error correction. Large hardware costs, limited flexibility in terms of code length/code rate and considerable power consumption limit the use of belief-propagation algorithm based LDPC decoders in area and energy sensitive mobile environment. Serial bit flipping algorithms offer a trade-off between resource utilization and error correction performance at the expense of increased number of decoding iterations required for convergence. Parallel weighted bit flipping decoding and its variants aim at reducing the decoding iteration and time by flipping the potential erroneous bits in parallel. However, in most of the existing parallel decoding methods, the flipping threshold requires complex computations.In this paper, Hybrid Weighted Bit Flipping (HWBF) decoding is proposed to allow multiple bit flipping in each decoding iteration. To compute the number of bits that can be flipped in parallel, a criterion for determining the relationship between the erroneous bits in received code word is proposed. Using the proposed relation the proposed scheme can detect and correct a maximum of 3 erreneous hard decision bits in an iteration. The simulation results show that as compared to existing serial bit flipping decoding methods, the number of iterations required for convergence is reduced by 45% and the decoding time is reduced by 40%, by the use of proposed HWBF decoding. As compared to existing parallel bit flipping decoding methods, the proposed HWBF decoding can achieve similar bit error rate (BER) with same number of iterations and lesser computational complexity. Due to reduced number of decoding iterations, less computational complexity and reduced decoding time, the proposed HWBF decoding can be useful in energy sensitive mobile platforms.     

面向新工科的计算机网络课程翻转教学

基于新工科教学,本文研究了计算机网络课程翻转教学模型和方法。首先通过课前翻转、课中翻转和课后翻转构建了面向新工科的计算机网络课程翻转教学模型,然后进行了面向新工科的翻转教学实践探索。教学实践分析结果表明,面向新工科的计算机网络课程翻转教学模型对计算机网络课程的教学质量提升具有一定的效果。     

An integral‐imaging three‐dimensional display with wide viewing angle

Abstract— The viewing angle and flipping areas of a conventional integral‐imaging three‐dimensional (3‐D) display were analyzed. The pitches of the elemental image and micro‐lens are identical. The more micro‐lenses used, the smaller the viewing angle becomes and the wider the flipping areas become. In this paper, an improved integral‐imaging 3‐D display is presented. The pitch of the elemental image is larger than that of the micro‐lens. The single‐viewing angles of all micro‐lenses converge and there are no flipping areas at the optimal viewing distance. Computational reconstructions of improved and conventional integral imaging were carried out, and experimental results demonstrate that improved integral‐imaging 3‐D displays have a wider viewing angle than the conventional ones and do not have flipping areas at the optimal viewing distance.     

翻转课堂在3DSMAX建模技术课程中的应用研究

The key to improve the quality of higher education is to renew the teaching idea and improve the teaching method. With the spread of flipping classroom teaching mode, a new way to solve the teaching quality in colleges and universities has emerged. By means of the 3DSMAX modeling technology course of computer major in our college and guided by the concept of flipping classroom teaching, this paper constructs a flipping classroom teaching mode based on the characteristics of college classroom to carry out teaching practice, and puts forward new ideas, hoping to provide reference for improving the quality of classroom teaching.     

附带翻转工位双边装配线蚁群算法优化设计

双边装配线应用广泛,翻转工位操作能有效降低部分零件装配难度与操作风险,但增加了设计难度。基于此,研究了附带翻转工位操作的挖掘机底盘双边装配线规划设计问题,针对该问题提出了一种改进蚁群算法求解。给出了问题求解的启发式任务分配规则,提出可采用启发式任务选择规则以提高算法收敛速率。进而分析某型挖掘机底盘装配线得出先后约束关系图,将问题抽象为双边装配线优化设计问题。随后,采用两种蚁群算法进行附带翻转工位的装配线优化,分析比较了两种算法因结构差异对优化结果所造成的影响。     

Weak coin flipping with small bias

This paper presents a quantum protocol that demonstrates that weak coin flipping with bias ≈0.239, less than 1/4, is possible. A bias of 1/4 was the smallest known, and followed from the strong coin flipping protocol of Ambainis in [33rd STOC, 2001] (also proposed by Spekkens and Rudolph [Phys. Rev. A 65 (2002) 012310]). Protocols with yet smaller bias ≈0.207 have independently been discovered by Ambainis (2001) and Spekkens and Rudolph [Phys. Rev. Lett. 89 (2002) 227901]. We also present an alternative strong coin flipping protocol with bias 1/4 with analysis simpler than that of Ambainis [33rd STOC, 2001].     

消除Gibbs现象的仿真研究

针对数字滤波器中存在的Gibbs现象．研究了改进窗函数与改变滤波因子截断长度综合法。鉴于该方法通带和阻带的截止频率不易控制的缺点,提出了消除Gibbs现象的一种伞新的方法即数据翻转法,该方法是对输入信号在没进入滤波器之前对其进行变换来尽量减少Gibbs现象带来的影响．仿真结果表明,与上述综合法相比,数据翻转法能更有效地消除Gibbs现象．     

《机械设计》课程基于翻转课堂教学模式的可行性分析

翻转课堂教学模式在提升教学质量、学生能力方面是一种有效的教学手段。在翻转之前要进行可行性分析,才能保证翻转课堂有效开展。本文以《机械设计》课程为翻转对象,主要从课程特点、教学资源、教学活动、教学评价、教学平台等角度进行可行性分析。提出进行翻转课堂教学之前,教师要做好充分教学准备,合理分析课程特点是否适合翻转、检查教学资源是否齐全、教学活动是否多样性,评价体系是否全面、客观,教学平台是否能满足翻转的要求,学生学习特征是否符合翻转模式,只有对翻转课堂准备条件进行科学分析,才能激发学生持续、有效的学习,才能达到翻转课堂的教学效果。     

Orthogonal Data Embedding for Binary Images in Morphological Transform Domain- A High-Capacity Approach

This paper proposes a data-hiding technique for binary images in morphological transform domain for authentication purpose. To achieve blind watermark extraction, it is difficult to use the detail coefficients directly as a location map to determine the data-hiding locations. Hence, we view flipping an edge pixel in binary images as shifting the edge location one pixel horizontally and vertically. Based on this observation, we propose an interlaced morphological binary wavelet transform to track the shifted edges, which thus facilitates blind watermark extraction and incorporation of cryptographic signature. Unlike existing block-based approach, in which the block size is constrained by 3times3 pixels or larger, we process an image in 2times2 pixel blocks. This allows flexibility in tracking the edges and also achieves low computational complexity. The two processing cases that flipping the candidates of one does not affect the flippability conditions of another are employed for orthogonal embedding, which renders more suitable candidates can be identified such that a larger capacity can be achieved. A novel effective Backward-Forward Minimization method is proposed, which considers both backwardly those neighboring processed embeddable candidates and forwardly those unprocessed flippable candidates that may be affected by flipping the current pixel. In this way, the total visual distortion can be minimized. Experimental results demonstrate the validity of our arguments.     

Quantum leader election

A group of n individuals \(A_{1},\ldots A_{n}\) who do not trust each other and are located far away from each other, want to select a leader. This is the leader election problem, a natural extension of the coin flipping problem to n players. We want a protocol which will guarantee that an honest player will have at least \(\frac{1}{n}-\epsilon \) chance of winning (\(\forall \epsilon >0\)), regardless of what the other players do (whether they are honest, cheating alone or in groups). It is known to be impossible classically. This work gives a simple algorithm that does it, based on the weak coin flipping protocol with arbitrarily small bias derived by Mochon (Quantum weak coin flipping with arbitrarily small bias, arXiv:0711.4114, 2000) in 2007, and recently published and simplified in Aharonov et al. (SIAM J Comput, 2016). A protocol with linear number of coin flipping rounds is quite simple to achieve; we further provide an improvement to logarithmic number of coin flipping rounds. This is a much improved journal version of a preprint posted in 2009; the first protocol with linear number of rounds was achieved independently also by Aharon and Silman (New J Phys 12:033027, 2010) around the same time.     

Label flipping attacks against Naive Bayes on spam filtering systems

Label flipping attack is a poisoning attack that flips the labels of training samples to reduce the classification performance of the model. Robustness is used to measure the applicability of machine learning algorithms to adversarial attack. Naive Bayes (NB) algorithm is a anti-noise and robust machine learning technique. It shows good robustness when dealing with issues such as document classification and spam filtering. Here we propose two novel label flipping attacks to evaluate the robustness of NB under label noise. For the three datasets of Spambase, TREC 2006c and TREC 2007 in the spam classification domain, our attack goal is to increase the false negative rate of NB under the influence of label noise without affecting normal mail classification. Our evaluation shows that at a noise level of 20%, the false negative rate of Spambase and TREC 2006c has increased by about 20%, and the test error of the TREC 2007 dataset has increased to nearly 30%. We compared the classification accuracy of five classic machine learning algorithms (random forest(RF), support vector machine(SVM), decision tree(DT), logistic regression(LR), and NB) and two deep learning models(AlexNet, LeNet) under the proposed label flipping attacks. The experimental results show that two label noises are suitable for various classification models and effectively reduce the accuracy of the models.

     

Coin-based Secure Computations

International Journal of Information Security - In the history of cryptography, many cryptographic protocols have relied on random coin tosses to prove their security. Although flipping coins is...     

基于双核锁步的多核处理器SEU加固方法

以单粒子翻转为代表的软错误是制约COTS器件空间应用的主要因素之一;为了满足空间应用对高集成卫星电子系统抗辐照防护的要求,提出了一种面向通用多核处理器的单粒子翻转加固方法,通过软件层面双核互检,在不额外增加硬件开销的前提下,充分提高了COTS器件的可靠性,具有良好的可移植性和较强的工程实用价值;进行软件故障注入实验,在程序执行的关键节点注入错误信息,验证该双核互检方法实用性;实验结果表明双核互锁方法可以100%检测出系统中产生的单粒子翻转,抗软错误能力满足应用需要。     

A novel image watermarking in redistributed invariant wavelet domain

Most existing digital watermarking algorithms, which are based on the Discrete Wavelet Transform, are not robust to geometric distortions, even if for some special distortions, such as multiples of 90° rotation of integers and image flipping, which change the location of pixels but have no effect on the value of the image. Therefore, to solve the problem, according to Haar wavelet transform theory, the redistributed invariant wavelet domain is constructed and proofed in this paper; a novel image watermarking algorithm, based on the invariant domain, is proposed to eliminate such distortions. The experimental results showed that the proposed algorithm not only can resist the common image processing operations, but also successfully resist the distortions that result from multiples of 90° rotations of integers and image flipping.     

Algorithmic entropy of sets

In a previous paper a theory of program size formally identical to information theory was developed. The entropy of an individual finite object was defined to be the size in bits of the smallest program for calculating it. It was shown that this is −log₂ of the probability that the object is obtained by means of a program whose successive bits are chosen by flipping an unbiased coin. Here a theory of the entropy of recursively enumerable sets of objects is proposed which includes the previous theory as the special case of sets having a single element. The primary concept in the generalized theory is the probability that a computing machine enumerates a given set when its program is manufactured by coin flipping. The entropy of a set is defined to be −log₂ of this probability.     

规则低密度校验码的比特翻转解码算法研究

本文提出一种规则低密度校验码的比特翻转迭代解码算法。在解码算法的每一次迭代运算过程中,解码运算可以从总体上分为两个阶段：首先,满足可靠性要求的校验节点从与其相邻接的信息节点中选择一个信息比特作为翻转候选比特;然后,解码算法采用投票的方法对于这些候选翻转比特进行进一步的筛选。本算法由于对于最终翻转比特的选择结果是通过两次筛选而得到的,从而极大地降低了误翻的概率,加快了迭代解码算法的收敛速度,提高了系统的性能。另外,在第一阶段的比特选择过程中,我们综合校验节点所提供的校验检测信息和信道输出所提供的可靠性信息,提出了新的翻转比特选择标准。仿真结果表明,本文所提出的解码算法有着较好的性能,在解码运算复杂度和纠错性能之间提供了另外一个均衡。     

基于加强概率控制策略的SAT局部搜索算法

局部搜索算法是目前求解SAT问题比较有效的方法,而Sattime算法是在SAT国际大赛中获得大奖的一种典型局部搜索算法。在Sattime算法的求解过程中,记录变元翻转事件流数据库,通过数据分析与模式挖掘,发现Sattime算法的局部搜索行为中会出现相邻搜索步选择同一个变元的现象,即所谓的回环现象,从而降低了求解效率。为解决此问题,提出两种概率控制策略：加强子句选择策略和加强变元选择策略,并将这两种策略应用到Sattime算法中,形成新的局部搜索算法Sattime-P。实验结果表明,与Sattime算法相比,改进后的Sattime-P算法求解效率有显著的提升。该方法也对其他局部搜索算法的改进具有参考价值。     

Specificity of damage recognition and catalysis of DNA repair

A common feature of DNA repair enzymes is their ability to recognize the damage independently of sequence in which they are found. The presence of a flipped out base inserted into the protein in several DNA-enzyme complexes suggests a contribution to enzyme specificity. Molecular simulations of damaged DNA indicate that the damage produces changes in DNA structure and changes the dynamics of DNA bending. The reduced bending force constant can be used by the enzyme to induce DNA bending and facilitate base flipping. We show that a thymine dimer (TD) containing DNA requires less energy to bend, lowering the barrier for base flipping. On the other hand, bending in DNA with U-G mismatch is affected only by a small amount and flipping is not enhanced significantly. T4 endonuclease V (endoV), which recognizes TD, utilizes the reduced barrier for flipping as a specific recognition element. In uracil DNA glycosylase (UDG), which recognizes U-G mismatches, base flipping is not enhanced and recognition is encoded in a highly specific binding pocket for the flipped base. Simulations of UDG and endoV in complex with damaged DNA provide insight into the essential elements of the catalytic mechanism. Calculations of pKas of active site residues in endoV and endoV-DNA complex show that the pKa, of the N-terminus is reduced from 8.01 to 6.52 while that of Glu-23 increases from 1.52 to 7.82. Thus, the key catalytic residues are in their neutral form. The simulations also show that Glu-23 is also H-bonded to O4' of the 5'-TD enhancing the nucleophilic attack on Cl and that Arg-26 enhances the hydrolysis by electrostatic stabilization but does not participate in proton transfer. In the enzyme-substrate complex of UDG, the role of electrostatic stabilization is played by His-268, whose pKa increases to 7.1 from 4.9 in the free enzyme. The pKa of Asp-145, the other important catalytic residue, remains around 4.2 in the free enzyme and in the complex. Thus, it can not act as a proton acceptor. In the complex the 3'-phosphate of uracil is stabilized next to Asp-145 by two bridging water molecules. Such a configuration activates one water molecule to act as a proton acceptor to produce a stabilizing hydronium ion and the other as a proton donor to produce the nucleophilic hydroxide. It appears that DNA glycosylases share commonalties in recognition of damage but differ in their catalytic mechanisms.     

On shape Delaunay tessellations

Shape Delaunay tessellations are a generalization of the classical Delaunay triangulation of a finite set of points in the plane, where the empty circle condition is replaced by emptiness of an arbitrary convex compact shape. We present some new and basic properties of shape Delaunay tessellations, concerning flipping, subgraph structures, and recognition.     

Controllability and stabilization of Boolean control networks by the auxiliary function of flipping

In this article, a hybrid method combining flip matrix approach and an open (or closed) loop control is proposed to study global controllability and stabilization of Boolean control networks (BCNs). First, the necessary and sufficient condition for global controllability of BCNs, by flipping some members of a perturbation set and under free control sequences, is proposed. After that, using a search algorithm, the minimal perturbation sets for global controllability (MS‐GCs) of the BCN are obtained. Next, we propose a necessary and sufficient criterion for global stabilization of BCNs by flipping some members of a perturbation set and under a state feedback control. Similarly, an algorithm is given to search for the minimal perturbation sets for global stabilization (MS‐GSs) of the BCN. Moreover, the time‐optimal MS‐GSs of the BCN are also obtained by an algorithm. Some examples are given to illustrate the effectiveness of the results.