With the development of blockchain applications, demand for cross-chain technology has been increasing. Relay chain mode is the state-of-the-art and mainstream solution nowadays. However, the relay chain mode suffers from poor performance, which stems from its core facility - the relay chain. Therefore, guiding its improvement and parameters configuration is vital. Currently, there is no specialized performance model of the relay chain. The cross-chain scenario involves receiving transactions from blockchains and uniformly verifying them, while general blockchain models are not applicable for it. Relay chains are characterized by the following features: transaction arrival in batches with uncertain sizes, updating block headers for simplified payment verification (SPV), Byzantine fault tolerance (BFT) type protocol, and different packaging rules. This work first proposes an analytical framework for relay chain performance. It captures the mentioned features by constructing a batch-arrival and bulk-service model. We give a concrete calculation of the relay chain with practical BFT (PBFT) consensus and develop a method to arrive at the computational forms of two essential performance descriptors: system throughput and cross-chain transaction confirmation delay. Through this model, we can judge accurately whether the relay chain is overloaded, and eliminate the overload state by tuning the parameters; and we can evaluate the system performance under different traffic and design parameters. Finally, we verify the model through experiments. With our study, operators can configure the system parameters effectively and improve the relay chain to meet the requirements of practical use.

This article presents graph theoretic conditions for the controllability and accessibility of bilinear systems over the special orthogonal group, the special linear group and the general linear group, respectively, in the presence of drift terms. The controlled terms are assumed to take place between pairwise states. Such bilinear systems naturally induce two interaction graphs: one graph from the drift, and another from the controlled dynamics. As a result, the system controllability or accessibility becomes a property of the two graphs in view of the classical Lie algebra rank condition. We establish a systemic way of transforming the Lie bracket operations in the underlying Lie algebra, into specific operations of removing or creating links over the drift and controlled interaction graphs. As a result, we establish a series of graphical conditions for the controllability and accessibility of such bilinear systems, which rely only on the connectivity of the union of the drift and controlled interaction graphs. We present examples to illustrate the validity of the established results, and show that the proposed conditions are in fact considerably tight.

In this article, we study systems of Boolean equations over a network, where each node in the network possesses only one Boolean equation from the system. The Boolean equation assigned at any particular node is a private equation known to this node only, and the aim of this article is to develop distributed algorithms that allow all the nodes to obtain solutions to the network Boolean equations without exchanging their local Boolean equations. First, we observe that the Boolean equations can be locally lifted to a system of linear algebraic equations under a basis of Boolean vectors, which is distributedly solvable using existing distributed linear equation algorithms as a subroutine. Next, we construct a distributed Boolean equation solver by the nodes solving the lifted linear network equation for a number of randomly selected initial values, and then converting the algebraic solutions into solutions to the original Boolean equations by a novel Boolean vector search algorithm. We prove that for solvable Boolean equations, when the initial values of the nodes for the distributed linear equation solving step are independent identically distributed selected according to a uniform distribution in a high-dimensional cube, such an algorithm returns the exact solution set of the Boolean equations at each node with high probability. We also present an algorithm for distributed verification of the satisfiability of Boolean equations when the solvability is not known beforehand, and prove its correctness. Finally, we show that by utilizing linear equation solvers with differential privacy to replace the in-network computing routines, the distributed Boolean equation algorithms can be made differentially private

采用静态输入检测技术,提出并实现了一个模数转换器(ADC)单粒子效应评估测试系统.该系统基于面向仪器系统的外围组件互联扩展平台(PXI)搭建.利用PXI触发模式控制模块化仪器的高速响应,并采用实时判决的方法对ADC输出数据进行监测.基于该系统对一种自主研发的10位25 MS/s ADC进行单粒子效应辐照试验.试验结果表明,该系统能够准确、高效评估ADC抗辐照性能,为抗辐照ADC的加固设计提供支撑平台.

随着高级驾驶员辅助系统(advanced driver assistance systems,ADAS)中对高分辨率光检测和测距(light detection and ranging,LIDAR)技术的需求越来越高,文章提出一种应用于激光测距技术的去噪算法,该算法是一种完整的数字信号处理方法,用时间相关的单光子计数来进行飞行时间(time-of-flight,TOF)测距,该方法的核心是将原始光子存储在一个m×n的阵列中.该算法包括粗滤波、细滤波2个过程,在粗滤波中,将每16个光子作为一个组,首先编程为4×4子阵列,在子阵列块中,将汇总所有光子;然后逐块进行筛选.在细滤波中,对通过粗滤波选择的3个子阵列中的每个子阵列的16个数据进行卷积;然后在每个子阵列中逐个滤波来确定最大数量的光子.与在单光子统计直方图中执行逐条滤波的传统算法相比,该算法的效率提高了10倍以上.仿真实验结果表明,文中提出的方法大大提高了运算速度,同时精度仍然很高,可用于激光雷达芯片的实时信号处理.

对一种流水线型模数转换器(ADC)的时序电路进行了改进研究.改进时序延长了余量增益单元MDAC部分加减保持相位的时长,可以在不增加功耗与面积的情况下,将一种10位流水线型ADC在20 MS/s采样率下的有效位(ENOB)从9.3位提高到9.8位,量化精度提高了 5％;将该ADC有效位不低于9.3位的最高采样率从21 MS/s提高到29 MS/s,转换速度提高了 35％.ADC的采样频率越高,改进时序带来的效果越显著.该项技术特别适用于高速高精度流水线型ADC,也为其他结构ADC的高速高精度设计提供思路.

Opinion dynamics has recently attracted much attention, and there have been a lot of achievements in this area. This paper first gives an overview of the development of opinion dynamics on social networks. We introduce some classical models of opinion dynamics in detail, including the DeGroot model, the Krause model, 0 - 1 models, sign networks and models related to Gossip algorithms. Inspired by some real life cases, we choose the unit circle as the range of the individuals' opinion values. We prove that the individuals' opinions of the randomized gossip algorithm in which the individuals' opinion values are on the unit circle reaches consensus almost surely.

In this paper, a refraction and diffraction mixed compensation test optical path based on computergenerated hologram (CGH) has been proposed, and the combination of the CGH and aplanatic lens is realized to measure the off-axis segment in null test with focal reducing. The total length has been reduced to 1/4 to 1/8 of that of the conventional method. And the adjustment sensitivity of the small focus ratio segment has been improved. The distortion ratio of the interferogram of the large off-axis segment has been optimized from 12. 5 to 1. 25. The segments with different off-axis distances can be measured rapidly with high precision by replacing different computer-generated holograms and keeping every elements in place. The method is used to complete the processing and testing of a Phi 330 mm off-axis trial mirror, and the root mean square (RMS) value of the test surface figure is 0.0290 lambda (lambda is wavelength). The RMS value of the test surface figure is reduced to 0. 0267 lambda, by calibrating the aplanatic lens using a standard spherical mirror.

对高速ADC的测量技术进行了分析研究,提出了基于高速ADC AD9433的测量方案.系统阐述了两类模拟输入驱动电路原理,详细介绍了两种模拟驱动电路和时钟电路抖动的分析方法.将上述理论分析应用于AD9433测量方案,测量结果证明了上述理论分析的正确性.

Quarter-wave plate (QWP) is one of the most important components of dynamic interferometer and its retardation can influence the measurement accuracy, which is usually manifested as periodic ripple error in the measurement results. Based on Jones matrix, the error formula is deduced in this paper, and the error correction method by rotating the half-wave plate (HWP) to change the intensity distribution in the four phase-shifted interferograms is proposed. In the experiment, the ripple error can be effectively suppressed when the background intensity of four interferograms tend to be the same. The performance of dynamic interferometer can be significantly improved through the proposed method.

为了处理宽动态范围的激光脉冲回波信号,设计了一种带有自适应增益控制技术的模拟前端.通过分段调节跨阻放大器的跨阻增益,实现了在1 μA～1 mA范围内输入电流与输出电压近似线性的关系.提出了自触发使能方法,可以在没有外部清零信号的情况下连续接收回波信号.提出了一种新型差分移位时刻鉴别电路,能有效减小行走误差.电路采用0.11 μm CMOS工艺设计,后仿真结果表明,--3 dB带宽为530 MHz,最大跨阻增益为103 dBΩ,等效输入噪声电流谱密度为6.47 pA·Hz-1/2@350 MHz,输入动态范围为60 dB,功耗小于100 mW.该模拟前端电路设计适用于飞行时间脉冲激光雷达.

为了研究硅通孔(TSV)转接板及重离子种类和能量对3D静态随机存储器(SRAM)单粒子多位翻转(MBU)效应的影响,建立了基于TSV转接板的2层堆叠3D 封装SRAM模型,并选取6组相同线性能量传递(LET)值、不同能量的离子(11B 与4He、28 Si 与19 F、58 Ni 与27Si、86 Kr与40Ca、107Ag与74Ge、181Ta与132Xe)进行蒙特卡洛仿真.结果表明,对于2层堆叠的TSV 3D封装SRAM,低能离子入射时,在Si路径下,下堆叠层SRAM 多位翻转率比上堆叠层高,在TSV(Cu)路径下,下堆叠层SRAM 多位翻转率比Si路径下更大;具有相同LET值的高能离子产生的影响较小.相比2D SRAM,在空间辐射环境中使用基于TSV转接板技术的3D 封装SRAM 时,需要进行更严格的评估.

Community search, also known as local community detection, is designed to obtain the community structure containing the given query nodes. At present, community search technology has been widely studied, but most of them ignore the effect of node attributes. Some studies propose attributed community search methods and usually adopt a two-phase approach. Generally, the subgraph with structure cohesiveness is obtained first and then the subgraph with keyword cohesiveness is returned as the final result on this basis. In practice, approaches of this kind may lead to incomplete or incorrect results, because information from one single aspect cannot accurately describe the feature of nodes. That is, topology information and attribute information of the network should be complementary. In this paper, we propose an attributed community model called RCS(Representation-based Community Search). Firstly we apply random-walk based representation learning technology to combine topology information and attribute information of nodes. Secondly we propose a new community model to formulate the problem that what is a good community based on the representation information. Then a series of algorithms are designed to fetch a cohesive community whose vertices are tightly connected and closely related to query nodes. Finally the effectiveness and efficiency of RCS are verified by extensive experiments on several real-world networks with ground-truth cnmmunities.

In dynamic interferometry, the retardation error of quarter-wave plate (QWP) causes inconsistency of the background intensity and the modulation of the four phase shift interferograms, which makes the periodic ripple error in the measurement results. In this paper, an iterative algorithm is proposed to solve this problem. Both simulations and experiments validated that the algorithm can effectively eliminate the ripple error in the measurement results with stable and quick convergence, therefore the measurement accuracy of the dynamic interferometer can be improved without any extra manual operation.

时间数字转换器(Time-to-Digital Converter,TDC)是一种将连续时间信号转换为数字信号输出的器件,是飞行时间(TOF)激光雷达中的关键部件.在利用计数器粗采样和多相位内插细采样的传统结构上,设计了一种基于相位内插的双级粗细结合型时间数字转换电路,并增加了双回波接收通路来接收多脉冲回波信号,在此基础上设计了一款17通道多路TDC系统芯片.芯片采用CMOS 0.11 μm工艺设计,版图面积为0.6 mm×3 mm.后仿真结果显示,在1.2 V电源下其功耗小于100 mW,单输入精度平均值为51.7 ps,动态范围为3.4 μm,且线性度良好.该TDC芯片适用于飞行时间脉冲激光雷达的信号计时.

In this paper, we study graphical conditions for structural controllability and accessibility of drifted bilinear systems over Lie groups. We consider a bilinear control system with drift and controlled terms that evolves over the special orthogonal group, the general linear group, and the special unitary group. Zero patterns are prescribed for the drift and controlled dynamics with respect to a set of base elements in the corresponding Lie algebra. The drift dynamics must respect a rigid zero-pattern in the sense that the drift takes values as a linear combination of base elements with strictly non-zero coefficients; the controlled dynamics are allowed to follow a free zero pattern with potentially zero coefficients in the configuration of the controlled term by linear combination of the controlled base elements. First of all, for such bilinear systems over the special orthogonal group or the special unitary group, the zero patterns are shown to be associated with two undirected or directed graphs whose connectivity and connected components ensure structural controllability/accessibility. Next, for bilinear systems over the special unitary group, we introduce two edge-colored graphs associated with the drift and controlled zero patterns, and prove structural controllability conditions related to connectivity and the number of edges of a particular color.

The image quality of an astronomical telescope degrades in observations if the misalignment of optical elements exists. The degredation is more severe in astronomical systems with large aperture and fast focal ratio. To solve this problem, the paper proposes an active alignment method for routine observations of telescopes. The proposed method here aims to maintain the image quality by quasi-real time corrections on both the position and attitude of the telescope secondary mirror via the computation of star images. Considering the ellipticity of the star images in multi-field-of-view, the proposed method uses the particle swarm optimization to iteratively solve the misalignment of the telescope optics, so as to correct the lower-order aberrations induced by the misalignment. The simulation in the paper is carried on with 1.6 m multi-channel photometric survey telescope, proving that the residual error of misalignment of the secondary mirror is less than 1%, within the tolerance range. Further simulation and experiment are carried out on the Three Antarctic Survey Telescopes (AST3-3) for the verification, proving that the proposed method is able to precisely solve the misalignment of the telescope optics.

为了实现对磁场信号的高精度检测,利用隧道磁阻式磁传感器,设计并实现了一种精确分辨微弱磁场场信号的锁相放大系统.使用方波调制传感器输出信号,并利用Σ-Δ型ADC实现平均下抽取结构,抑制方波带来的高次谐波干扰,提高了ADC的有效分辨率,降低了系统运算量.通过理论与实验分析,验证了系统可以有效抑制噪声与温漂对测量精度的影响,并可精确标定nT级磁场.

This paper presents graph theoretic conditions for the controllability and accessibility of bilinear systems over the special orthogonal group and the general linear group, respectively, in the presence of drift terms. Such bilinear systems naturally induce two interaction graphs: one graph from the drift, and another from the controlled dynamics. As a result, the system controllability or accessibility becomes a property of the two graphs in view of the classical Lie algebra rank condition. We establish a systemic way of transforming the Lie bracket operations in the underlying Lie algebra, into specific operations of removing or creating links over the drift and controlled interaction graphs. As a result, we establish a series of graphical conditions for the controllability and accessibility of such bilinear systems, which rely only on the connectivity of the union of the drift and controlled interaction graphs. We present examples to illustrate the validity of the established results, and show that the proposed conditions are in fact considerably tight.

In this paper, we propose distributed algorithms that solve a system of Boolean equations over a network, where each node in the network possesses only one Boolean equation from the system. The Boolean equation assigned at any particular node is a private equation known to this node only, and the nodes aim to compute the exact set of solutions to the system without exchanging their local equations. We show that each private Boolean equation can be locally lifted to a linear algebraic equation under a basis of Boolean vectors, leading to a network linear equation that is distributedly solvable. A number of exact or approximate solutions to the induced linear equation are then computed at each node from different initial values. The solutions to the original Boolean equations are eventually computed locally via a Boolean vector search algorithm. We prove that given solvable Boolean equations, when the initial values of the nodes for the distributed linear equation solving step are i.i.d selected according to a uniform distribution in a high-dimensional cube, our algorithms return the exact solution set of the Boolean equations at each node with high probability.