A NEW ALGORITHM FOR THE GENERATION OF k-AKY M SEQUENCES

A new algorithm for generating k-ary M sequences is given. In the algorithm a new method is used that the main cycle is extended by joining to it a subset of cycles instead of the classical one in which the main cycle is extended by joining to it one cycle. The algorithm reduces the times of choosing bridging states and accelerates the speed of joining cycles.     

A new algorithm for the generation ofk-AryM sequences

A new algorithm for generatingk-aryM sequences is given. In the algorithm a new method is used that the main cycle is extended by joining to it a subset of cycles instead of the classical one in which the main cycle is extended by joining to it one cycle. The algorithm reduces the times of choosing bridging states and accelerates the speed of joining cycles.     

产生k元M序列的一种新算法

本文给出了生成k元M序列的一种新的算法.该算法不再采用主圈并一个圈的经典并圈法,而是利用了主圈并一组共轭圈的新的并圈方法.这样减少了选择桥状态的次数,进而加快了并圈速度.     

All-digital delay-locked loop/pulsewidth-control loop with adjustable duty cycles

An all-digital delay-locked loop (DLL) and an all-digital pulsewidth-control loop (PWCL) with adjustable duty cycles are presented. For the DLL, by using the flash time-to-digital conversion, both the phase alignment and the duty cycle of the output clock are assured in 10 cycles. For the PWCL, the sequential time-to-digital conversion is adopted to reduce the required D-flip-flops and lock within 28 cycles. For both of the proposed circuits, the requirement of the input clock with 50% duty cycle is eliminated. The proposed circuits have been fabricated in a 0.35-/spl mu/m CMOS process. The proposed DLL generates the output clock with the duty cycle of 25%, 50% and 75%, and the operation frequency range is from 140 to 260 MHz. For the proposed PWCL, the duty cycle is adjusted from 30% to 70% in steps of 10%. The operation frequency range is from 400 to 600 MHz.     

Fatigue life evaluation of wire bonds in LED packages using numerical analysis

Reliability of LED packages is evaluated using several tests. When a thermal shock test, which is one of the reliability tests, is conducted, the most common failure mode is wire neck breakage. In order to evaluate the wire bonding reliability of LED packages, performing the thermal shock test is time-consuming. In this paper the wire bonding reliability for LED packages is evaluated by using numerical analysis. A wire bonding lifetime model for the thermal shock test was developed, which is based on Coffin-Manson fatigue law. The model was calibrated from fatigue data of thermal shock tests and volume averaging accumulated plastic strains. The accumulated plastic strains were calculated by using finite element analysis corresponding to the test conditions. The test conditions were changed by silicones, package sizes, wire bonding diameters, heights, and lengths. The calibrated model was used to estimate the number cycle to failure so that the wire bonding reliability for the thermal shock test was evaluated by performing the numerical analysis. Furthermore, we used a response surface methodology to study the relationship between the wire loop and the accumulated plastic strain to determine the optimal wire loop. The plastic strain was a function of diameter, height and length. At the optimal point, the number of cycle to failure for the thermal shock test was suggested using the wire bonding lifetime model.     

An efficient minimizing algorithm for sum of disjoint products

This paper presents an efficient algorithm for calculating system reliability by sum of disjoint products (sdp). Abraham and his successors yield relatively short system reliability formula. This new algorithm follows the philosophy of Abraham, but uses new rules to arrange the initial ordering of minipaths in outer loop and the ordering of terms in inner loop, and adopts multiple-variable inversion. The algorithm generates a shorter system reliability formula than any known sdp algorithm.     

热循环加载条件下SMT焊点应力应变过程的有限元分析

ＳＭＴ焊 热循环条件下的应力应变过程分析是ＳＭＴ焊点可靠性的重要方向。本文采用粘弹塑性材料模式描述ＳｎＰｂ钎料的力学本构响应，对非城堡型ＬＣＣＣ焊蹼结构进行三维有限元分析，考察焊点在热循环加载过程中的应力应变等力学行为。研究结果表明，焊点钎料内的高应力发生在热循环的低温阶段，升降温过程中的蠕变和非弹性应变的累积显著，蠕变应变在非弹性应变中占主导地位，应力应变滞后环在热循环的最初几个周期内就能很快稳     

A low-noise fast-lock phase-locked loop with adaptive bandwidthcontrol

This paper presents a salient analog phase-locked loop (PLL) that adaptively controls the loop bandwidth according to the locking status and the phase error amount. When the phase error is large, such as in the locking mode, the PLL increases the loop bandwidth and achieves fast locking. On the other hand, when the phase error is small, this PLL decreases the loop bandwidth and minimizes output jitters. Based on an analog recursive bandwidth control algorithm, the PLL achieves the phase and frequency lock in less than 30 clock cycles without pre-training, and maintains the cycle-to-cycle jitter within 20 ps (peak-to-peak) in the tracking mode. A feed forward-type duty-cycle corrector is designed to keep the 50% duty cycle ratio over all operating frequency range     

电致生物效应高压脉冲源控制系统设计

为了提高电致生物效应高压脉冲源连续运行时的输出精度及可靠性,设计了一种基于嵌入式实时操作系统Small RTOS51的电致生物效应高压脉冲源控制系统。采用NEC8254-2低成本地实现频率、占空比可调PWM输出,以MAX526,MAX197分别实现D/A,A/D功能,构成高压脉冲源输出控制与反馈回路,并提出了一种改进的采样信号中位值滤波算法。与传统中位值滤波算法相比,该算法具有更高灵敏度,基于RTOS的程序设计,提高了系统的可靠性。实验结果表明:高压脉冲源在连续运行条件下输出精度稳定达到0.1%。     

On the suboptimality of iterative decoding for turbo-like and LDPC codes with cycles in their graph representation

In this paper, we focus on the suboptimality of iterative decoding on graphs with cycles, through examining the use of a reliability-based decoding algorithm for some concatenated codes with an interleaver, known as turbo-like codes. The a posteriori probabilities delivered by the iterative decoding are regarded as reliability information, and an efficient algorithm for the overall linear block code is applied at certain iterations. Simulation results show that the suboptimality of iterative decoding due to cycles can be at least partially compensated by this approach. Some insights about the potential additional coding gains achievable are investigated based on the characteristics of the constituent decoders. These characteristics are related to the nature of suboptimality in the overall iterative decoding. The effects of some code parameters and channel conditions on the behavior of iterative decoding are also studied for a better understanding of its suboptimality.     

Reliability optimization of communication networks using simulated annealing

Two concepts of communication network reliability are considered. The first one, the ‘s-t’ reliability, is relevant for communication between a source station and a terminal station as in the case of a two way telephone communication. The second one, the overall reliability, is a measure of simultaneous connectedness among all stations in the network. An algorthm is presented which selects the optimal set of links that maximizes the overall reliability of the network subject to a cost restriction, given the allowable node-link incidences, the link costs and the link reliabilities. The algorithm employs a variaton of the simulated annealing approach coupled with a hierarchical strategy to achieve the gobal optimum. For complex networks, the present algorithm is advantageous over the traditional heuristic procedures. The solutions of two representative example network optimization problems are presented to illustrate the present algorithm. The potential utilization of parallel computing strategies in the present algorithm is also identified.     

Optical quorum cycles for efficient communication

Many optical networks face heterogeneous communication requests requiring topologies to be efficient and fault tolerant. For efficiency and distributed control, it is common in distributed systems and algorithms to group nodes into intersecting sets referred to as quorum sets. We show efficiency and distributed control can also be accomplished in optical network routing by applying the same established quorum set theory. Cycle-based optical network routing, whether using SONET rings or p-cycles, provides the sufficient reliability in the network. Light-trails forming a cycle allow broadcasts within a cycle to be used for efficient multicasts. Cyclic quorum sets also have all pairs of nodes occurring in one or more quorums, so efficient, arbitrary unicast communication can occur between any two nodes. Efficient broadcasts to all network nodes are possible by a node broadcasting to all quorum cycles to which it belongs (\(O(\sqrt{N})\)). In this paper, we propose applying the distributed efficiency of the quorum sets to routing optical cycles based on light-trails. With this new method of topology construction, unicast and multicast communication requests do not need to be known or even modeled a priori. Additionally, in the presence of network link faults, greater than 99 % average coverage enables the continued operation of nearly all arbitrary unicast and multicast requests in the network. Finally, to further improve the fault coverage, an augmentation to the ECBRA cycle finding algorithm is proposed.     

AVS解码器环路滤波的优化及实现

AVS编解码器采用环路滤波去除块效应来提高图像质量,而环路滤波复杂度高、运算量大,且滤波过程数据访问频繁,严重影响了代码的执行效率.为提高解码速率,通过分析滤波算法特点,调整滤波结构,优化滤波算法,部分代码采用DSP汇编语言.结果表明与传统的C相比,缩短了代码运行时间,提高了执行速度,达到实时解码的要求.     

利用ACE值构造QC-LDPC码

为进一步提升中短码长下准循环低密度奇偶校验(Quasi-cyclic Low-density Parity-check,QC-LDPC) 码的纠错性能,提出了一种综合短环数目和环连通性的QC-LDPC码构造方法。首先,采用Golomb规则构造QC-LDPC码,对基矩阵中的部分元素进行替换预处理,初步降低短环数目;其次,采用所提的利用近似环外信息度（Approximate Cycle Extrinsic message degree,ACE）的消环掩模算法来优化QC-LDPC码,使得掩模后的校验矩阵具有较大的ACE平均值,最终完成QC-LDPC码的构造。该构造方法简单、通用性强,在短环数目和连通性间进行了平衡。与只考虑减少短环数目、增大围长等方法相比,该方法构造的QC-LDPC码有更加优异的纠错性能。     

A real-time algorithm for the approximation of level-set-based curve evolution.

In this paper, we present a complete and practical algorithm for the approximation of level-set-based curve evolution suitable for real-time implementation. In particular, we propose a two-cycle algorithm to approximate level-set-based curve evolution without the need of solving partial differential equations (PDEs). Our algorithm is applicable to a broad class of evolution speeds that can be viewed as composed of a data-dependent term and a curve smoothness regularization term. We achieve curve evolution corresponding to such evolution speeds by separating the evolution process into two different cycles: one cycle for the data-dependent term and a second cycle for the smoothness regularization. The smoothing term is derived from a Gaussian filtering process. In both cycles, the evolution is realized through a simple element switching mechanism between two linked lists, that implicitly represents the curve using an integer valued level-set function. By careful construction, all the key evolution steps require only integer operations. A consequence is that we obtain significant computation speedups compared to exact PDE-based approaches while obtaining excellent agreement with these methods for problems of practical engineering interest. In particular, the resulting algorithm is fast enough for use in real-time video processing applications, which we demonstrate through several image segmentation and video tracking experiments.     

求网络总可靠度的状态空间树法和精确分解算法

本文提出了求通信网络总可靠度的状态空间树法。它直接产生网络图的一个不交化树多层多项式,优点是计算量较小[计算时间复杂度为0(?),(?)为边数,n_1为叶数],所得表达式较短。在此基础上应用超图理论提出了求通信网络总可靠度的精确分解算法。用它进行网络图的m次分解,一台计算机所能计算的通信网络规模可以扩大m倍。     

Network restoration under a single link or node failure using Preconfigured Virtual Cycles

This paper presents a design algorithm for networks with a restoration mechanism that provides failure-independent, end-to-end path protection to a set of given demands under a single link or node failure with a focus on optical networks. The restoration routes are provided on preconfigured cycles, where each of the demands is assigned a single restoration route and specific restoration wavelengths on a segment of one cycle (splitting is not allowed). The number of reserved restoration wavelengths may vary from one link to the next on a cycle; hence, we refer to these cycles as Preconfigured Virtual Cycles (PVCs). The network design algorithm consists of three major parts. The first part generates a large number of candidate PVCs. Our algorithm allows assignment of certain demands that have common failure scenarios to the same PVC. The second part selects a set of PVCs from among the candidates, attempting to minimize the total reserved restoration cost while ensuring that each demand is assigned to one PVC. This is achieved by solving a set covering problem followed by elimination of duplicate assignments. The third part resolves conflicts of wavelength assignments.     

The Extension of Universal Generating Function Method to Search for All One-to-Many $d$ -Minimal Paths of Acyclic Multi-State-Arc Flow-Conservation Networks

Evaluating network reliability is an important step in the planning, design, and control of systems. The acyclic multi-state-arc flow-conservation network (AMAFCN) is a special multi-state-arc flow-conservation network (MAFCN) of which each arc has independent, discrete, limited multi-states (capacities), and satisfied flow conservation. The AMAFCN is arranged in such a way that no flow leaving a node can return this node through any sequence of nodes, e.g. no cycles exist. For such networks, we are interested in evaluating the AMAFCN reliability, i.e. the probability that the flow from the source node to the sink node is equal to or greater than a demanded flow of units. A general method for the MAFCN/AMAFCN reliability evaluation is using minimal path/cut vectors with system state (called the -MP/-MC). In this study, we focused on developing an extension of the universal generating function method (UGFM) to find the entire one-to-many -MP before calculating the AMAFCN reliability between the source node, and some node subset (i.e. one-to-many reliability). The computational complexity of the proposed algorithm is also analyzed. Finally, one example is given to illustrate how entire one-to-many -MP are generated using the proposed algorithm. Then, all one-to-many reliabilities of this example are calculated.     

The effect of power cycling on the reliability of lead-free surfacemount assemblies

A power cycling in-test monitoring system has been constructed to test the reliability of eight different lead-free surface mount assemblies. The assemblies included SnAg3.8Cu0.7 and SnAg3.8Cu0.7X solder joints on OSP-Cu (organic solderability preservative on Cu), electroless NiAu, immersion Ag and immersion Sn board metallizations. One Pb containing assembly, Sn62PbAg2 on OSP-Cu board metallization, was included for comparison. The components on the assemblies were 1206 resistors (Sn100 metallization on the end terminals) and 100 lead QFP with gullwing leads (SnPb15 metallization). All assemblies experienced up to 5000 power cycles of ambient to 100°C with a 15 min dwell at each temperature. Solder joint reliability was evaluated by monitoring electrical resistance after each power cycle and examining mechanical strength and microstructure with number of power cycles. The 1206 resistors on four of the assemblies (one of which was the Pb containing assembly) exhibited electrical resistance increases after 4000 power cycles. All resistor samples decreased in strength by more than 70% at 5000 cycles and cracks appeared after 1000 power cycles. All gullwing lead solder joints exhibited good reliability over 5000 power cycles, with no resistance increase and no strength reduction. Small cracks appeared after 3000 power cycles     

Heterogeneous redundancies scheduling algorithm for mimic security defense

The scheduling of heterogeneous redundancies is one of the key lines of mimic security defense,but the existing scheduling strategies are lack of consideration about the similarity among redundancies and the scheduling algorithms are incomprehensive.A new scheduling algorithm called random seed & minimum similarity (RSMS) algorithm was proposed,which combined dynamics and reliability by determining a scheduling scheme with minimum global-similarity after choosing a seed-redundancy randomly.Theoretical analysis and simulation results show that RSMS algorithm possessed a far longer scheduling cycle than maximum dissimilarity algorithm,as well as a far lower failure rate than random scheduling algorithm,which represents an effective balance between dynamics and reliability.