分布式工作流执行站点多目标随机决策

针对面向服务的企业(SOE)环境下工作流在分布式执行性能方面存在的不足,提出了一种基于随机决策的动态(运行时)执行站点优化方法。该方法以扩展服务工作流网,增加软约束和硬约束作为站点优化的基础,对环境的动态性和服务随机性进行分析,针对分片的四种结构,以组合服务质量最优为目标,建立多目标动态执行站点随机线性规划模型,并进行求解。应用实例验证了该方法的可用性。与现有工作相比,所提出的算法使工作流执行性能得到了明显提高,并消除了活动并行执行中存在的资源瓶颈。     

Cancellation of coherent artifacts in optical coherence tomography imaging

Coherent artifacts in optical coherence tomography (OCT) images can severely degrade image quality by introducing false targets if no targets are present at the artifact locations. Coherent artifacts can also add constructively or destructively to the targets that are present at the artifact locations. This constructive or destructive interference will result in cancellation of the true targets or in display of incorrect echo amplitudes of the targets. We introduce the use of a nonlinear deconvolution algorithm, CLEAN, to cancel coherent artifacts in OCT images of extracted human teeth. The results show that CLEAN can reduce the coherent artifacts to the noise background, sharpen the air-enamel and enamel-dentin interfaces, and improve the image contrast.     

应用于生产管理的工作流技术研究

参考目前国际上工作流方面的研究工作，对工作流内涵进行了扩展，给出了工作流系统的模型描述，结合Agent技术，将工作流技术应用于生产管理，并使用ECA规则控制工作流程的执行。最后构建了一个用于生产调度的工作流系统的框架，给出了工作流执行的规则和资源、角色的任务分配规则。     

The effects of transducer geometry on artifacts common to diagnostic bone imaging with conventional medical ultrasound

The portability, low cost, and non-ionizing radiation associated with medical ultrasound suggest that it has potential as a superior alternative to X-ray for bone imaging. However, when conventional ultrasound imaging systems are used for bone imaging, clinical acceptance is frequently limited by artifacts derived from reflections occurring away from the main axis of the acoustic beam. In this paper, the physical source of off-axis artifacts and the effect of transducer geometry on these artifacts are investigated in simulation and experimental studies. In agreement with diffraction theory, the sampled linear-array geometry possessed increased off-axis energy compared with single-element piston geometry, and therefore, exhibited greater levels of artifact signal. Simulation and experimental results demonstrated that the linear-array geometry exhibited increased artifact signal when the center frequency increased, when energy off-axis to the main acoustic beam (i.e., grating lobes) was perpendicularly incident upon off-axis surfaces, and when off-axis surfaces were specular rather than diffusive. The simulation model used to simulate specular reflections was validated experimentally and a correlation coefficient of 0.97 between experimental and simulated peak reflection contrast was observed. In ex vivo experiments, the piston geometry yielded 4 and 6.2 dB average contrast improvement compared with the linear array when imaging the spinous process and interlaminar space of an animal spine, respectively. This work indicates that off-axis reflections are a major source of ultrasound image artifacts, particularly in environments comprising specular reflecting (i.e., bone or bone-like) objects. Transducer geometries with reduced sensitivity to off-axis surface reflections, such as a piston transducer geometry, yield significant reductions in image artifact.     

D-optimal design of artifacts used in-machine software error compensation

A methodology for the design of artifacts used in software error compensation of rapid prototyping (RP) machines is presented. In software error compensation, an artifact is frequently utilized for measuring parametric errors of the machine axes. In the past, different artifacts have been used and designed in an ad hoc way. To date, no method is available to evaluate the design of an artifact based on its effect on the precision of the fitted models estimated using the artifact. This paper proposes a method to evaluate and improve the design of an artifact using design of experiments (DOE) techniques and numerical optimization. As demonstrated by the results, a D-optimality criterion optimized using simulated annealing techniques can be used to evaluate and improve the design of an artifact so that the components of the volumetric error are predicted more precisely, with the benefit of better error compensation over repeated use of the error models. Although in this paper the concept is only demonstrated for the SLA 250 RP machine, it can be applied to the design of any artifact used for machine error compensation.     

Adaptive Signal Enhancement Unit for EEG Analysis in Remote Patient Care Monitoring Systems

In this paper we propose an efficient process of physiological artifact elimination methodology from brain waves (BW), which are also commonly known as electroencephalogram (EEG) signal. In a clinical environment during the acquisition of BW several artifacts contaminates the actual BW component. This leads to inaccurate and ambiguous diagnosis. As the statistical nature of the EEG signal is more non-stationery, adaptive filtering is the more promising method for the process of artifact elimination. In clinical conditions, the conventional adaptive techniques require many numbers of computational operations and leads to data samples overlapping and instability of the algorithm used. This causes delay in diagnosis and decision making. To overcome this problem in our work we propose to set a threshold value to diminish the problem of round off error. The resultant adaptive algorithm based on this strategy is Non-linear Least mean square (NL²MS) algorithm. Again, to improve this algorithm in terms of filtering capability we perform data normalization, using this algorithm several hybrid versions are developed to improve filtering and reduce computational operations. Using the method, a new signal enhancement unit (SEU) is realized and performance of various hybrid versions of algorithms examined using real EEG signals recorded from the subject. The ability of the proposed schemes is measured in terms of convergence, enhancement and multiplications required. Among various SEUs, the MCN²L²MS algorithm achieves 14.6734, 12.8732, 10.9257, 15.7790 dB during the artifact removal of RA, EMG, CSA and EBA components with only two multiplications. Hence, this algorithm seems to be better candidate for artifact elimination.     

Types for task-based access control in workflow systems

Task-based access control (TBAC) is a flexible security mechanism, which has been widely implemented in workflow management systems. In TBAC, permissions are assigned to tasks and users can only obtain the permissions during the execution of tasks. The authors aim at developing a method for formalising and analysing security properties of workflow systems under TBAC policy. To achieve this goal, the authors first present WFPI, workflow π-calculus. By adding task execution and submission primitives, and tagging each agent with its executing and distributing tasks,WFPI can flexibly represent the concepts and elements in workflow systems. Then, based on WFPI, a type system is proposed to ensure that the well-typed workflow systems can abide by the TBAC policy at run time, by avoiding run-time access violations. To the best of one?s knowledge, the present research is the first attempt to study workflow access control by process calculus and types.     

Truncation artifacts in tomographic reconstructions from projections

The artifacts in tomographic reconstructions from truncated sets of projections are analyzed. The shift-variant impulse response of the tomographic system for parallel-beam geometry is derived. A number of propositions are made describing the observed artifacts. A graphical scheme for the prediction of the location and shape of the truncation artifacts is presented and applied to reconstructions from simulated projections. The artifact analysis is applied to images obtained with the commonly used convolution backprojection reconstruction algorithms, and it is extended to reconstructions from fan-beam projections. The analysis is performed for the continuous imaging domain so as to separate the clipping artifacts clearly from those attributed to the digital implementation of the reconstruction algorithms.     

A Distributed Artifact Standard of Voltage

The artifact standard, an object which embodies the physical quantity to be standardized, has served the metrology community well. Its great merits are its stability and the precision with which it can be compared to other like artifacts. Its use as the basis of a measurement system is not without drawbacks however. Among these are: its definition may be arbitrary, it is maintained by a national or international standardizing laboratory and is not accessible to the user, and it is subject to loss or damage through accident, sabotage, or act of war. An extension of the NBS Volt Transfer Program is capable of providing what may be termed a "Distributed Artifact Standard" of dc voltage. Such a standard will maintain the value of the volt in the universe of artifact standards maintained by the standards laboratories of the measurement community. This standard has none of the objectionable properties cited. It is accessible, it is immune to loss or damage, and it can be certified in terms of the absolute standards maintained by the national standards institutes. The theoretical and empirical basis for such a distributed artifact standard is presented.     

面向服务的工作流分层映射模型

基于对面向服务的体系结构(SOA)下服务角色划分以及对当前分布式应用特征的分析,通过引入抽象资源和抽象服务的概念,提出了一个面向服务的将工作流划分为业务工作流(BWF) 、抽象工作流(AWF)和执行工作流(EWF)的工作流映射模型.它将业务工作流的部署、执行转换成两个映射--业务工作流到抽象服务工作流的映射和抽象服务工作流到执行服务工作流的映射 .这一模型为当前Internet上基于Web服务和Grid服务的分布式应用提供了一种动态的组织、部署和执行方案.此外重点探讨了实现该模型下多层次工作流计算机辅助映射的应用模板技术,应用模板定义了各个抽象资源和抽象服务在特定应用任务中必须遵从的约束及必须提供的相关元数据.     

传统器物元素的现代性转化与应用

目的以传统与现代为范畴,以传统器物元素在休息凳中的设计应用为主线,探索传统器物元素在现代设计中的转化与应用的新思路。方法运用现代设计理论,审视传统器物元素的转化与应用存在的主要问题,即"有形元素的标签式复制、脱离具体环境的简单迁移、传统器物元素转化的二维倾向",并用解构分析法进行剖析,找寻解决问题的途径。结论传统器物元素的转化与应用是在具体环境下的"功能元素、审美元素、精神元素"相互影响和融合的重构。随着现代科技的发展,器物的材料和结构越来越优化,其简洁流畅的造型也符合现代工业的生产效率要求。传统器物元素只有将形式和现代材料、结构、工艺相结合,将功能置于首位,将繁缛的装饰进行简化,才能被时代所接受,才能在当下得到继承和发展。     

航电产品BIT研制流程设计与应用

如何合理地规划航电产品机内测试（built in test,BIT）的研制流程,是BIT设计尚需解决的重要问题．首先,分析了当前与BIT相关的研制流程,指出现有BIT设计流程存在的不足;其次,通过对BIT设计相关工作项目的梳理,确定了航电产品研制的方案阶段和初样/试样阶段的BIT设计工作项目;再次,结合航电产品研制工作流程,建立了融入产品整个研制周期的BIT设计工作流程．通过构建针对航电产品BIT研制的工作流程,提高了航电产品BIT设计工作的可操作性,BIT针对性强,节约了时间成本,降低了开发费用,并为航电产品BIT研制工作的流程化设计提供了参考范例．最后,以某综合控制管理系统的研制为案例,对该BIT研制流程进行了应用,验证了工作流程的有效性．     

基于子空间分解的脑电信号眼电伪迹自动去除方法研究

针对脑电信号中的眼电伪迹去除问题,提出了一种基于几何子空间分解的眼电伪迹去除方法。最大噪声分量分析帮助构建几何子空间并将多维脑电信号分解成一系列分量,利用眼电分量间的高相关度,使用Spearman秩相关准则确定相关程度从细节中实现眼电伪迹分量的抽取;将处理后各个分量投影回信号空间并进行重构,于是在无需记录眼电的情况下得到去除眼电伪迹后的脑电信号。为了验证该方法的有效性,分别对自行叠加眼电伪迹的脑电信号及实际测量的脑电信号进行了研究,结合脑地形图能量分布可视化的优势,结果表明该方法能够对脑电信号进行有效降噪。     

Hands-On Experiences: An Integral Part of Engineering Curriculum Reform

The concept of “hands-on” experiences, through Mechanical Dissection classes, as a part of engineering curriculum reform is presented. Mechanical Dissection in this context refers to a process of studying the function of a mechanical system and dismantling it in order to see how its specific function is realized. The functions of various components within the artifact and interaction between the components are also studied. Awareness of the design process, multiple solutions to a design problem, and the evolution of the technology of various artifacts and their components are focused upon. This is followed by systematic re-assembly of the artifact. The courseware and supporting laboratory modules were developed to address specific objectives. They provide the foundation for better understanding of sophomore, junior and senior courses, particularly the design oriented ones. Seven in-depth dissection modules form the basis of this course. These are a weighing scale, a money sorting machine, an electric lawn mower, an electric hand drill, a gasoline engine, a centrifugal pump and an eighteen speed bike. This course is targeted at freshman or sophomore level engineering students. Some of these modules can be simplified and transported to K-14 students. Assessment of this course has shown an overwhelming positive response from students in all aspects. This makes the course an integral part of engineering curriculum reform.     

智能流量积算仪计测技术探讨

目前智能流量积算仪的种类繁多,每种类型的流量积算仪的功能和使用方法各不相同,导致在检定过程中不能按单一类型智能流量积算的操作方法来开展其他类型的检定,从而导致检定的复杂和困难。本文通过一些实例分析对智能流量积算仪的校准/检定技术进行了探讨。     

业务流程时间性能定量分析

时间性能的定量分析是保证流程模型有效性和提高业务流程质量的关键.针对管理型流程的特点,基于任务活动执行时间为零或者服从指数分布的假设,建立了业务流程的广义随机工作流网模型,并利用广义随机Petri网和马尔可夫链理论来分析流程的时间性能,获得了流程平均执行时间的计算公式,最后给出了应用验证实例并和仿真结果进行了比较.     

一种改进的MRI图像刚性平移运动伪影的校正

在磁共振成像过程中由于患者的运动会在图像中造成运动伪影,从而造成图像的退化,严重影响临床诊断．本文对MRI图像刚性平移运动伪影提出了一个改进的后处理方法：首先用谱平移理论消除频率编码方向平移运动;然后建立模糊模型表示图像的背景并对其进行抑制,用数学形态学的方法确定图像的支撑域;最后以能量熵为收敛准则,用相位恢复算法对频率编码方向残余的子像素移动造成的伪影和相位编码方向的伪影进行消除．实验表明,应用本研究提出的方法能够明显地消除图像空间运动造成的伪影．     

Exploring the Approaches to Data Flow Computing

Architectures based on the data flow computing model provide an alternative to the conventional Von-Neumann architecture that are widely used for general purpose computing. Processors based on the data flow architecture employ fine-grain data-driven parallelism. These architectures have the potential to exploit the inherent parallelism in compute intensive applications like signal processing, image and video processing and so on and can thus achieve faster throughputs and higher power efficiency. In this paper, several data flow computing architectures are explored, and their main architectural features are studied. Furthermore, a classification of the processors is presented based on whether they employ either the data flow execution model exclusively or in combination with the control flow model and are accordingly grouped as exclusive data flow or hybrid architectures. The hybrid category is further subdivided as conjoint or accelerator-style architectures depending on how they deploy and separate the data flow and control flow execution model within their execution blocks. Lastly, a brief comparison and discussion of their advantages and drawbacks is also considered. From this study we conclude that although the data flow architectures are seen to have matured significantly, issues like data-structure handling and lack of efficient placement and scheduling algorithms have prevented these from becoming commercially viable.     

Validation of web service compositions

Web services support software architectures that can evolve dynamically. In particular, in this paper the focus is on architectures where services are composed (orchestrated) through a workflow described in the business process execution language (BPEL). It is assumed that the resulting composite service refers to external services through assertions that specify their expected functional and non-functional properties. On the basis of these assertions, the composite service may be verified at design time by checking that it ensures certain relevant properties. Because of the dynamic nature of Web services and the multiple stakeholders involved in their provision, however, the external services may evolve dynamically, and even unexpectedly. They may become inconsistent with respect to the assertions against which the workflow was verified during development. As a consequence, validation of the composition must extend to run time. In this work, an assertion language, called assertion language for BPEL process interactions (ALBERT), is introduced; it can be used to specify both functional and non-functional properties. An environment which supports design-time verification of ALBERT assertions for BPEL workflows via model checking is also described. At run time, the assertions can be turned into checks that a software monitor performs on the composite system to verify that it continues to guarantee its required properties. A TeleAssistance application is provided as a running example to illustrate our validation framework.     

Strategy of computed tomography sinogram inpainting based on sinusoid-like curve decomposition and eigenvector-guided interpolation

Projection incompleteness in x-ray computed tomography (CT) often relates to sparse sampling or detector gaps and leads to degraded reconstructions with severe streak and ring artifacts. To suppress these artifacts, this study develops a new sinogram inpainting strategy based on sinusoid-like curve decomposition and eigenvector-guided interpolation, where each missing sinogram point is considered located within a group of sinusoid-like curves and estimated from eigenvector-guided interpolation to preserve the sinogram texture continuity. The proposed approach is evaluated on real two-dimensional fan-beam CT data, for which the projection incompleteness, due to sparse sampling and symmetric detector gaps, is simulated. A Compute Unified Device Architecture (CUDA)-based parallelization is applied on the operations of sinusoid fittings and interpolations to accelerate the algorithm. A comparative study is then conducted to evaluate the proposed approach with two other inpainting methods and with a compressed sensing iterative reconstruction. Qualitative and quantitative performances demonstrate that the proposed approach can lead to efficient artifact suppression and less structure blurring.