TTShuffle：一种区块链中基于两层洗牌的隐私保护机制

区块链隐私保护技术中的去中心化混币机制CoinJoin和CoinShuffle,分别因为代理节点不可信和节点需要层层传递加密而存在安全或效率低的问题,因此提出了TTShuffle,一种两层的隐私保护机制。首先将所有混币节点分成不同的组,通过层层加密在组内进行第一层洗牌,保护组内交易的敏感数据;然后由每个组派一个节点作为本组的代表,进行第二层的组间洗牌,保护所有组的敏感数据得到最后完整的交易内容。通过安全和实验分析表明,TTShuffle中40个混币参与者混币时间低于10 s,相比CoinShuffle机制提高了混币的效率,减少了混币时间,也确保了混币过程的隐私安全。     

一种通用的低成本QC-LDPC码译码结构

提出一种通用的QC-LDPC码译码器架构.该架构采用一种特殊的绑定结构和一个可配置的循环移位网络,实现了多码率变码长的LDPC译码,可以应用在多标准数字通信系统中.同时,该结构使存储单元的利用率提高了13倍.提出的可配置数据交换网络可以使存储单元和运算单元之间的连线规则化,降低了连线复杂度.基于该结构,本文实现了符合中国数字电视地面传输标准DTMB中LDPC译码器,在SMIC0.18um标准COMS工艺下,芯片面积约为8mm2;在时钟频率50MHz,迭代次数15次,8比特量化的条件下,吞吐率可达91Mbps.     

自由空间光互连洗牌型神经网络模型

首先介绍一种洗牌型自由空间光互连多层全互连神经网络模型。该模型的高神经元／权重比可以极大地压缩神经网络的互连权矩阵IWM（interconnectweightmatrix）。对于具有N2个神经元的单层二维全互连神经网络的IWM为N2×N2,而洗牌型全互连神经网络的IWM仅为4N2log2N。另外,洗牌型全互连神经网络整齐、简单的结构方便了网络的综合,特别是网络隐单元的综合,并且十分适合于神经网络的光学实现。然后描述了采用数字光技术实现光互连的洗牌型神经网络的系统模型、关键芯片结构以及关键技术。本文提出的模型和方法使实现与人脑神经网络规模（104量级）相当的实用化自适应光电子全互连神经网络成为可能。     

New strategy of the variable-structure finite control of controlled plants with time lags

A new strategy based on the feed-forward control method is proposed for control with variable structure. The strategy provides finite-length transient processes in a linear system with time delay. The strategy is based on combining closed-loop and programmable control, which is adjusted with reference to an isochrone with the time less than the transition time. Such a strategy provides an opportunity for the time of the transition processes to be minimal among all the possible ones.     

采用二元光学技术设计PS互连网络器件

介绍了一种利用二元光学技术设计制作二元 PS(Perfect Shuffle)互连网络器件的方法,这种器件可以很简单地实现二维光学 PS 网络,而且具有重量轻,微型化,性能稳定,互连效率高等特点.分析了二元 PS 器件的串音问题,互连效率以及菲涅耳透镜的相对孔径与波长,光刻极限之间的关系.     

一种基于密钥的水印嵌入位置置乱算法

提出了一种基于密钥的数字水印嵌入位置的置乱算法，该算法利用分组移位和混洗操作将水印嵌入位置进行多次置乱。算法简单，实现方便，嵌入位置随机分散，嵌入位置信息的安全仅依赖于一组密钥,在相当程度上达到了较理想的置乱效果,增加了系统的安全性。     

Bond-free DNA language classes

The absence of the ability to form a specified set of bonds in a collection of DNA strands is crucial in the design of experiments encoding algorithmic problems as single- or double-stranded DNA. Recently, the specification of the bonding types to be avoided has been formalized by defining bond-free properties. Bond-free properties generalize several bonding properties which have been studied in the context of DNA computing. In this paper, we consider a bond-free property as defining a class of languages. We study the properties of these classes of languages. We develop new unary operators on languages for characterizing bond-free properties exactly, using familiar code-theoretic equations. These new operators provide a new characterization of maximal bond-free properties as well. We also focus on relationships to classes of languages from the theory of codes. Research supported in part by a grant from NSERC.     

Rearrangeability of 7-stage 16 × 16 shuffle exchange networks

It has long been an outstanding conjecture that any (2n − 1)-stage shuffle exchange network (Omega network) is rearrangeable for 2 ⁿ × 2 ⁿ . Many researchers have failed to prove this conjecture, including a recent one established by Hasan. However, nobody has pointed out its fallacy. Therefore, as one of the objectives, this paper shall clarify this fact. Since the case of n = 3 has been proven by many researchers [1,2], this paper uses a constructive approach to prove that when n = 4, the 7-stage 16 × 16 shuffle exchange network is also rearrangeable. The paper also presents the model of a balanced tree to avoid internal conflict, the representation of permutations using a connection graph and loop graph, and the concepts of symmetry graph and identical transform. Based on graphic composition and bipartition, the permutations 16 × 16 are divided into five classes, with five assignment algorithms proposed. These algorithms are simpler, clearer and easier to program. The techniques used for n = 4 may provide hints for the general case of n > 4. __________ Translated from Acta Electronica Sinica, 2007, 35(10): 1875–1885 [译自: 电子学报]     

离合器从动盘性能对汽车耸车的影响

为了研究离合器从动盘性能对汽车耸车振动的影响,建立了传动系统-汽车整车的11自由度非线性动力学模型。模型考虑了离合器从动盘的扭转特性、干摩擦阻尼、离合器接合黏滑特性以及变速器轮齿啮合刚度。利用建立的模型计算汽车起步过程系统动力学响应,通过实车测试验证模型的正确性,分析离合器从动盘性能参数对耸车振动的影响。结果表明:汽车的耸车现象发生在离合器完全接合之后;耸车振动频率与传动系第2阶固有频率相近;提高静摩擦因数,降低从动盘转动惯量和2级扭转刚度,可以降低汽车在起步过程中的耸车振动。本研究的建模和分析方法,可以用来计算与分析离合器从动盘结构性能参数对整车耸车振动特性的影响。