PET成像的加权最小二乘重建算法

针对正电子发射断层成像系统,提出一种基于加权最小二乘函数的迭代重建算法.与传统的梯度型算法不同,在迭代过程中,此算法利用当前迭代点构造辅助函数,使用辅助函数的最优解代替目标函数的最优解,获得新的迭代点.该算法自动满足非负约束,无需步长因子,保证目标函数单调递减,并且具有全局收敛性.使用模拟数据和真实医学诊断数据进行实验,结果表明:该算法与SA-WLS和ML-EM算法相比需要相同的运算时间,但是具有更快的收敛速度和更好的成像质量.     

基于不确定数据的频繁项查询算法

频繁项的查询是一项非常重要的技术,但在新兴的不确定数据领域却是一项新的研究课题.基于不确定数据,提出了一种新的频繁项定义,并提出了两条过滤规则,可以有效地减少检测数据的数量.最后提出高效的频繁项查询算法UFI,该算法通过找到概率求解中的递推规律,极大提高了单点检测效率.实验结果显示:提出的方法可以有效地减少候选集,降低搜索空间,改善在不确定数据上的查询性能.     

一种基于人工神经网络的基本块重排方法

基于程序的控制流动信息和体系结构跳转代价模型,使用人工神经网络预测控制流边的执行概率,利用子结构分析技术开展基本块重排.程序的控制流边信息被选择作为神经网络的训练数据,这些信息包含了该边的静态特征和动态行为之间的联系.基于弹性反馈反向传播(RPROP)神经网络,在UniCore处理器上实现了采用子结构分析的基本块重排算法.评测结果表明,此算法可获得与利用剖视信息的优化算法相同的程序性能优化效果,不依赖于剖视信息的特性,可很好地扩展该基本块重排算法的应用范围.     

基于改进鸽群优化和马尔可夫链的多无人机协同搜索方法

针对多无人机在协同搜索过程中存在重复搜索、目标静止、搜索效率低的问题,提出基于改进鸽群优化和马尔可夫链的多无人机协同搜索方法.首先,建立类似传感器探测范围的蜂窝状环境模型,降低对搜索区域的重复搜索;其次,建立满足高斯分布的马尔可夫链动态目标运动模型;然后,将柯西扰动引入基本鸽群优化算法的地图和指南针算子,高斯扰动引入地标算子,同时利用模拟退火机制保留次优个体,进而有效缓减基本鸽群优化算法易陷入局部最优的问题.最后,通过仿真实验将本文算法与其他群体智能算法进行比较,结果表明新型算法的合理性和有效性.      

基于定量关联规则树的分类及回归预测算法

为了解决基于Apriori的分类关联规则算法挖掘数值型数据时效率和准确率偏低的问题,提出基于定量关联规则树的分类及回归预测算法.采用改进的定量关联规则算法挖掘数值型数据生成关联规则库,并基于关联规则树结构实现分类及回归预测.研究结果表明:改进的Apriori定量关联规则挖掘算法提高了分类预测的准确率并降低了计算复杂度;而采用关联规则树结构可使分类与回归预测时间明显加快,提高了样本匹配学习的速度.      

等值面上的凸组合法

利用等值面上的凸组合法求解了线性规划问题 .首先借助于一般的起作用集法找到一非最优极点 ,再由此极点的等值面与容许集的交集得一锥 ,然后沿着由该锥的下降棱方向与 -c方向所作的凸组合方向作直线搜索得到一新迭代点 .重复以上步骤直至得到最优点为止     

支持多租约SaaS应用按需服务的负载均衡策略

负载均衡是支持多租约SaaS应用实现可扩展性的关键技术.针对现有的负载均衡策略无法适应多租约SaaS应用按需服务特点的问题,提出了一种支持多租约SaaS应用按需服务的负载均衡策略.基于对租约用户个性化需求的分析,建立了面向租约功能类型的服务器负载模型.面向租约用户非功能需求提出了系统资源预分配规则和算法,并基于系统资源配置方案提出了基于租约用户限制的执行请求分配算法.实验结果表明所提出的负载均衡策略在满足了用户需求的同时有效提高了多租约SaaS应用的整体性能.     

基于变邻域搜索的热轧圆钢批量调度多目标优化方法

针对热轧圆钢的批量调度问题,考虑实际生产中工艺规程和交货期对轧制单元连续加工的影响,建立了以最小化设备调整时间、拖期生产惩罚和钢种跳跃惩罚为优化目标的数学模型,并设计了一种嵌入EDD规则的变邻域搜索算法.算法首先结合模型的约束特征,采用约束满足技术生成初始解;根据实际生产需求,将最小化设备调整时间作为主要目标,设计变邻域搜索算法实现目标优化,其中,运用混合算子构造邻域结构和局部搜索,并引入模拟退火接受准则来控制迭代过程中产生的新解;同时,为了最小化拖期惩罚和钢种跳跃惩罚,在求解过程中嵌入了EDD规则以及钢种排序规则.实验结果表明,模型和算法是可行且有效的.      

带并行腔和重入约束的双臂集束型设备调度方法

为有效解决半导体制造业中带并行腔和重入约束的双臂集束型设备调度问题,提出一种以优化搜索为核心的调度方法.首先,引入优化FIFO (first in first out)搜索规则,并以系统总完工时间最小化作为目标,建立带并行腔和重入约束的四加工腔双臂集束型设备调度数学模型.在此基础之上,结合虚拟缓冲模块的概念,提出一种基于机械臂交换策略的优化搜索算法.最后,对所提出的算法进行仿真实验,实验结果表明该算法是可行且有效的.      

高炉炉衬侵蚀边界识别的数值模拟

利用非稳态热传导反问题(IHCP)数学模型研究了高炉监测热电偶数据与高炉炉衬侵蚀厚度的关系.求解此反问题采用了整个时间域上的空间距离步进迭代算法和离散软化过滤法.根据上海梅山钢铁厂3号高炉采集的热电偶数据,模拟计算得出高炉炉衬剩余厚度随时间的变化关系.模拟结果证明了边界识别算法的可行性及其广阔的应用前景.     

一种基于粒子群参数优化的改进蚁群算法及其应用

针对现有基于粒子群参数优化的改进蚁群算法耗时较大的问题,提出了一种新的解决方案.方案中采用一种全局异步与精英策略相结合的信息素更新方式,同时合理减少蚁群算法被粒子群算法调用一次所需的迭代代数.对日本旭川垃圾场巡查机器人路径规划问题仿真求解的结果表明,与其他算法相比,该改进算法具有比较明显的速度优势.      

基于混合编码策略的电弧炉冶炼钢种的碳含量预报模型

提出一种混合编码策略的遗传算法(GA)训练电炉钢碳含量神经网络预报模型。先采用二进制编码策略,再采用十进制编码策略继续优化预报模型的权阈值,这种混合编码策略综合了二进制编码搜索能力强和十进制编码变异量可任意小的优点。仿真结果表明,混合编码策略的遗传算法(GA)具有更快的收敛速度和更好的寻优性能。对100 t电弧炉冶炼0.85%～1.00%C的钢种,预报碳含量的精度为±0.04%时混合编码GA的命中率为96%,二进制编码GA的命中率为90%。     

基于支持向量机的边坡稳定性预测

为准确快速地对边坡进行稳定性分析,提出基于支持向量机(Support vector machine SVM)的稀土矿开采边坡的SVM预测模型,结合42个稀土矿开采边坡实际案例,并分别采用网格寻优算法、遗传算法(Genetic algorithm GA)、粒子群算法(Particle swarm optimization...     

Maximum a posteriori estimation with Good's roughness for three-dimensional optical-sectioning microscopy

The three-dimensional image-reconstruction problem solved here for optical-sectioning microscopy is to estimate the fluorescence intensity lambda(x), where x epsilon R3, given a series of Poisson counting process measurements [Mj(dx)]jJ = 1, each with intensity [formula: see text] with [formula: see text] being the point spread of the optics focused to the jth plane and sj(y) the detection probability for detector point y at focal depth j. A maximum a posteriori reconstruction generated by inducing a prior distribution on the space of images via Good's three-dimensional rotationally invariant roughness penalty [formula: see text] It is proven that the sequence of iterates that is generated by using the expectation maximization algorithm is monotonically increasing in posterior probability, with stable points of the iteration satisfying the necessary maximizer conditions of the maximum a posteriori solution. The algorithms were implemented on the DECmpp-SX, a 64 x 64 parallel processor, running at < 2 s/(64(3), 3-D iteration). Results are demonstrated from simulated as well as amoebae and volvox data. We study performance comparisons of the algorithms for the missing-data problems corresponding to fast data collection for rapid motion studies in which every other focal plane is removed and for imaging with limited detector areas and efficiency.     

Sequence database searches via de novo peptide sequencing by tandem mass spectrometry

A method is described for searching protein sequence databases using tandem mass spectra of tryptic peptides. The approach uses a de novo sequencing algorithm to derive a short list of possible sequence candidates which serve as query sequences in a subsequent homology-based database search routine. The sequencing algorithm employs a graph theory approach similar to previously described sequencing programs. In addition, amino acid composition, peptide sequence tags and incomplete or ambiguous Edman sequence data can be used to aid in the sequence determinations. Although sequencing of peptides from tandem mass spectra is possible, one of the frequently encountered difficulties is that several alternative sequences can be deduced from one spectrum. Most of the alternative sequences, however, are sufficiently similar for a homology-based sequence database search to be possible. Unfortunately, the available protein sequence database search algorithms (e.g. Blast or FASTA) require a single unambiguous sequence as input. Here we describe how the publicly available FASTA computer program was modified in order to search protein databases more effectively in spite of the ambiguities intrinsic in de novo peptide sequencing algorithms.     

铸坯去向决策问题的建模与优化方法

 连铸-热轧界面的衔接、协调对于钢铁生产流程的高效、稳定运行有重要意义。针对连铸-热轧界面研究对于生产组织过程的简化处理而导致成果应用的局限性,提出一种以连铸出坯计划和热轧单元计划为对象,对实物铸坯的去向(加热炉、保温坑、板坯库)进行决策,并通过虚拟铸坯与实物铸坯的逐级匹配确定衔接方式(直接热装、热装、冷装)的优化方法。以热轧单元计划中直装和热装铸坯数最大化、直装和热装铸坯的传搁时间最小化为目标,考虑强制下线冷装要求、设备缓冲容量限制、实物铸坯-虚拟铸坯匹配规则、直装和热装铸坯传搁时间要求、铸坯上料必要运输时间等约束条件,建立了铸坯去向决策的整数非线性规划模型。设计了结合禁忌搜索的改进和声搜索算法求解模型,采用整数编码记录去向计划,通过模拟实物铸坯上料和虚拟铸坯匹配并装炉的过程进行解码,统计去向计划的目标函数值并计算评价值,利用禁忌搜索的局部寻优能力避免和声搜索早熟收敛,得到改进的和声搜索算法。以某钢铁企业热轧板带产线的生产数据进行测试,结果表明,铸坯去向决策模型可以提高直装率10.57%,提高热装率3.58%,直装和热装坯的传搁时间降低18.84%,并且改进和声搜索算法的最优评价值相比单一的禁忌搜索、和声搜索分别可以提升6.26%、4.51%,表明了模型和算法的有效性。     

Effects of Local Search Algorithms on Groundwater Remediation Optimization Using a Self-Adaptive Hybrid Genetic Algorithm

Genetic algorithms allow solution of more complex, nonlinear civil, and environmental engineering problems than traditional gradient-based approaches, but they are more computationally intensive. One way to improve algorithm performance is through inclusion of local search, creating a hybrid genetic algorithm (HGA). The inclusion of local search helps to speed up the solution process and to make the solution technique more robust. This paper focuses on the effects of different local search algorithms on the performance of two different HGAs developed in previous phases of this research, the self-adaptive hybrid genetic algorithm (SAHGA) and the enhanced SAHGA. The algorithms are tested on eight test functions from the genetic and evolutionary computation literature and a groundwater remediation design case study. The results show that the selection of the local search algorithm to be combined with the simple genetic algorithm is critical to algorithm performance. The best local search algorithm varies for different problems, but can be selected prior to solving the problem by examining the reduction in fitness standard deviation associated with each local search algorithm, and the time distribution associated to the local search algorithm.     

Representation of order information: An analysis of grouping effects in short-term memory.

Exps I–IV tested the independence model, 2 hierarchical models, and the dependence model of matrix relationships with a probed recall procedure in which 91 undergraduates were presented with a grouped sequence of items and were then required to recall the position and group of 1 of the items. This technique provided information about how well Ss correctly recalled both the group and position, the group only, the position only, and neither the group nor the position of an item. Findings reveal that when the items in a group were letters, digits, or musical notes, the data conformed to a hierarchical structure. When the nonalphanumeric characters were used, a matrix structure emerged. Exps V–VII required 50 undergraduates to judge the dissimilarity of 2 sequences of grouped items, the 2nd of which (the variation) was a reordering of the 1st (the original). The variation was made by reordering the groups in the original, reordering positions within groups, or reordering both groups and positions. Results show that when the members of a group were able to be encoded as single verbal units, the data supported a hierarchical system. When this was not possible, a matrix system fitted the data best. It is concluded that there is no general code for representing the order of grouped sequences and that the results are more compatible with a theory that postulates a number of specific subsystems in short-term memory, each with its own format for preserving order, than one that assumes a generalized order code. (42 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effective use of a novel rate-smoothing algorithm in atrial fibrillation by ventricular pacing

BACKGROUND: It is still unknown whether a fast heart rate or an irregular ventricular response in atrial fibrillation causes tachycardiomyopathy. Reduction in the variability of RR intervals without an increase in heart rate might be an alternative treatment when antiarrhythmic drugs fail to control the irregularity accompanying atrial fibrillation. SUBJECTS AND METHODS: Eight patients underwent temporary right ventricular pacing, using a novel rate-smoothing algorithm prior to DC cardioversion or His bundle ablation. A rate-smoothing algorithm was utilized by right ventricular apical stimulation. Spontaneous and paced RR intervals during atrial fibrillation were quantified and processed for statistical analysis. RESULTS: The rate-smoothing algorithm resulted in a substantial reduction in the variance of the RR intervals (slow mode 73.1%, fast mode 40.0%) and RR range (slow mode 49.3%, fast mode 34.3%). In contrast to previous algorithms, the mean heart rate during pacing intervention in atrial fibrillation did not change significantly to the heart rate directly preceding the pacemaker intervention (+2%). CONCLUSIONS: This initial study of the novel rate-smoothing algorithm shows that pacing intervention is a relatively safe, rapid and reliable alternative therapy for controlling irregular ventricular rhythms due to atrial fibrillation. Incorporation of the algorithm in implantable pacemakers appears justified, but demands further prospective studies in patients to evaluate relief of symptoms and reduction of tachycardiomyopathy due to atrial fibrillation.