Practical Combinatorial Testing: Beyond Pairwise

With new algorithms and tools, developers can apply high-strength combinatorial testing to detect elusive failures that occur only when multiple components interact. In pairwise testing, all possible pairs of parameter values are covered by at least one test, and good tools are available to generate arrays with the value pairs. In the past few years, advances in covering-array algorithms, integrated with model checking or other testing approaches, have made it practical to extend combinatorial testing beyond pairwise tests. The US National Institute of Standards and Technology (NIST) and the University of Texas, Arlington, are now distributing freely available methods and tools for constructing large t-way combination test sets (known as covering arrays), converting covering arrays into executable tests, and automatically generating test oracles using model checking (http://csrc.nist.gov/acts). In this review, we focus on real-world problems and empirical results from applying these methods and tools.     

Beyond Brute Force: Testing Financial Software

Large software development projects that follow formal processes generally divide the work among separate roles on structured teams that tend to employ development staff whose technical expertise is domain-neutral. This is especially true of large outsourcing vendors. Yet, the end users' needs are expressed in the applied domain's specific concepts, terms, and logic. Testing financial software's functionality requires deep subject expertise and an understanding of quality assurance methods and processes. Thorough domain analysis, efficient test designs, specific methods, and well-prepared quality assurance staff are key elements for success.     

全尺寸结构试验应变数据线性化修正方法研究

针对全尺寸飞机结构静力/疲劳试验中的应变测量数据非线性化的问题,进行应变测量数据线性化修正方法研究,提出一种适用于全尺寸飞机结构静力/疲劳试验应变测量数据线性化修正方法并进行工程应用。结果表明,该方法明显提高应变测量数据的准确性,是可行和有效的。该方法为后续海量应变数据自动化处理软件的开发提供理论依据。     

Inclusion of Textual Documentation in the Analysis of Multidimensional Data Sets: Application to Gene Expression Data

Recently, biology has been confronted with large multidimensional gene expression data sets where the expression of thousands of genes is measured over dozens of conditions. The patterns in gene expression are frequently explained retrospectively by underlying biological principles. Here we present a method that uses text analysis to help find meaningful gene expression patterns that correlate with the underlying biology described in scientific literature. The main challenge is that the literature about an individual gene is not homogenous and may addresses many unrelated aspects of the gene. In the first part of the paper we present and evaluate the neighbor divergence per gene (NDPG) method that assigns a score to a given subgroup of genes indicating the likelihood that the genes share a biological property or function. To do this, it uses only a reference index that connects genes to documents, and a corpus including those documents. In the second part of the paper we present an approach, optimizing separating projections (OSP), to search for linear projections in gene expression data that separate functionally related groups of genes from the rest of the genes; the objective function in our search is the NDPG score of the positively projected genes. A successful search, therefore, should identify patterns in gene expression data that correlate with meaningful biology. We apply OSP to a published gene expression data set; it discovers many biologically relevant projections. Since the method requires only numerical measurements (in this case expression) about entities (genes) with textual documentation (literature), we conjecture that this method could be transferred easily to other domains. The method should be able to identify relevant patterns even if the documentation for each entity pertains to many disparate subjects that are unrelated to each other.     

State-of-the-art in Large-Scale Volume Visualization Beyond Structured Data

Volume data these days is usually massive in terms of its topology, multiple fields, or temporal component. With the gap between compute and memory performance widening, the memory subsystem becomes the primary bottleneck for scientific volume visualization. Simple, structured, regular representations are often infeasible because the buses and interconnects involved need to accommodate the data required for interactive rendering. In this state-of-the-art report, we review works focusing on large-scale volume rendering beyond those typical structured and regular grid representations. We focus primarily on hierarchical and adaptive mesh refinement representations, unstructured meshes, and compressed representations that gained recent popularity. We review works that approach this kind of data using strategies such as out-of-core rendering, massive parallelism, and other strategies to cope with the sheer size of the ever-increasing volume of data produced by today's supercomputers and acquisition devices. We emphasize the data management side of large-scale volume rendering systems and also include a review of tools that support the various volume data types discussed.     

复杂文本网数据的主题建模进展

文中介绍了大规模文本网数据的主题建模研究的特点和近年来的重要进展.主题建模方法吸引了世界范围的广泛兴趣,并且促进了许多重要的数据挖掘、计算机视觉和计算生物应用系统的发展,包括文本自动摘要、信息检索、信息推荐、主题检测和追踪、自然场景理解、人体动作识别以及微阵列基因表达分析等.文中重点介绍文本网数据的4个主要特点以及对应的主题模型.文本网数据含有动态、高阶、多通路及分布式的结构,而之前的主题模型仅对部分的结构进行建模.而文中讨论了在三维马尔可夫模型的框架下统一对文本网数据的4个结构特点进行建模,并分析了结合三维马尔可夫模型和二型模糊系统对分布式单词计算和主题建模应用的可能性.除了对文本网数据的结构建模之外,还讨论了一些对三维马尔可夫模型能量最小化的机器学习算法.     

工程数据管理系统中的工程图档检索

工程数据管理系统 (EDMS) ,已在越来越多的现代企业中被推广应用。它使企业中的传统纸质工程图档及相关信息被数字化了的电子图档所替代。真正实现了企业内部的工程技术图档无纸化计算机管理。而工程图档的电子检索在整个EDMS中是一项十分重要的功能。它使被授权用户能通过网络从系统的共享数据库中快速、方便、灵活、安全地获得有用的信息。     

基于扩展有限状态机测试中测试输入数据自动选取的研究

扩展有限状态机(EFSM)模型是有限状态机(FSM)模型的一个扩展，它在FSM模型的基础上增加了变量、操作以及状态迁移的前置条件，通过EFSM我们可以更加精确地刻画软件系统的动态行为．基于EFSM的测试可以应用到许多领域，因此具有重要的研究价值和实际意义．许多研究人员已经提出了基于FSM测试的测试输入序列的构造方法，但基于EFSM的测试与FSM相比由于变量和状态迁移的前置条件的引入，增加了构造其测试输入的复杂性．我们认为基于EFSM测试的测试输入应该包含两个部分：即测试输入序列以及该输入序列上包含的输入变量的确定值(测试输入数据)．手工选取这些测试数据的工作十分繁琐，极大地增加了测试的花费，因此自动选取这些测试数据可以大大提高实际测试工作的效率．该文提出一种基于EFSM测试的测试数据自动选取方法，该方法利用两个关键的步骤：①区间削减和②分段梯度最优下降算法来自动选取测试数据．实验表明利用该方法可以自动选取大部分的测试数据，并且收敛速度较快；在某些无法得到确定解的情况下，区间削减也可以为测试人员提供一个较小的输入变量取值区间，方便了测试人员从中手工选择测试数据．     

Component-Trees and Multivalued Images: Structural Properties

Component-trees model the structure of grey-level images by considering their binary level-sets obtained from successive thresholdings. They also enable to define anti-extensive filtering procedures for such images. In order to extend this image processing approach to any (grey-level or multivalued) images, both the notion of component-tree, and its associated filtering framework, have to be generalised. In this article we deal with the generalisation of the component-tree structure. We define a new data structure, the component-graph, which extends the notion of component-tree to images taking their values in any (partially or totally) ordered set. The component-graphs are declined in three variants, of increasing richness and size, whose structural properties are studied.     

Big Data Based Self-optimization Networking: A Novel Approach Beyond Cognition

It is essential to satisfy class-specific QoS constraints to provide broadband services for new generation wireless networks. A self-optimization technique is introduced as the only viable solution for controlling and managing this type of huge data networks. This technique allows control of resources and key performance indicators without human intervention, based solely on the network intelligence. The present study proposes a big data based self optimization networking (BD-SON) model for wireless networks in which the KPI parameters affecting the QoS are assumed to be controlled through a multidimensional decision-making process. Also, Resource Management Center (RMC) was used to allocate the required resources to each part of the network based on made decision in SON engine, which can satisfy QoS constraints of a multicast session in which satisfying interference constraints is the main challenge. A load-balanced gradient power allocation (L-GPA) scheme was also applied for the QoS-aware multicast model to accommodate the effect of transmission power level based on link capacity requirements. Experimental results confirm that the proposed power allocation techniques considerably increase the chances of finding an optimal solution. Also, results confirm that proposed model achieves significant gain in terms of quality of service and capacity along with low complexity and load balancing optimality in the network.     

Query Languages for Data Exchange: Beyond Unions of Conjunctive Queries

The class of unions of conjunctive queries (UCQ) has been shown to be particularly well-behaved for data exchange; its certain answers can be computed in polynomial time (in terms of data complexity). However, this is not the only class with this property; the certain answers to any Datalog program can also can be computed in polynomial time. The problem is that both UCQ and Datalog do not allow negated atoms, as adding an unrestricted form of negation to these languages yields to intractability.     

Testing for Structural Breaks at Unknown Time: A Steeplechase

This paper analyzes the role of common data problems when identifying structural breaks in small samples. Most notably, we survey small sample properties of the most commonly applied endogenous break tests developed by Brown et al. (J R Stat Soc B 37:149–163, 1975) and Zeileis (Stat Pap 45(1):123–131, 2004), Nyblom (J Am Stat Assoc 84(405):223–230, 1989) and Hansen (J Policy Model 14(4):517–533, 1992), and Andrews et al. (J Econ 70(1):9–38, 1996). Power and size properties are derived using Monte Carlo simulations. We find that the Nyblom test is on par with the commonly used F type tests in a small sample in terms of power. While the Nyblom test’s power decreases if the structural break occurs close to the margin of the sample, it proves far more robust to nonnormal distributions of the error term that are found to matter strongly in small samples although being irrelevant asymptotically for all tests that are analyzed in this paper.     

Homogeneity Testing for Unlabeled Data: A Performance Evaluation

In this paper, we address the problem of testing homogeneity for unlabeled pixels observed in a subimage. Homogeneity testing is an essential component in split-and-merge segmentation algorithm. Two types of homogeneity tests are involved: tests for labeled data when deciding on merges between regions and tests for unlabeled data when deciding whether to split a region. In our study, we focus on images that are modeled as a mosaic of uniform regions corrupted by additive Gaussian noise. Using this model, we present a statistical analysis on the performance of two commonly used approaches for testing homogeneity of unlabeled data based on the region/subregion similarity and the data dispersion, respectively. We also propose and evaluate a new hierarchical homogeneity testing scheme for unlabeled data. The most important finding of this study is that the tests based on region/subregion similarity have a low power on average of detecting inhomogeneity in unlabeled data.     

Inventor 文档特性快速生成及标题栏国标化技术

对于Inventor 零部件文档特性和工程图标题栏的信息生成,提出了面向对 象的API 访问方法。该方法以VB.NET 语言为开发工具,运用Add-In 的方式,把常用的文 档特性如设计人、审核、图样名称、零件代号等集成到一个简洁的自定义用户界面,提高了 特性的生成速度;同时对于Inventor 自身提供的标题栏GB1 进行处理,使比例、工艺等断 裂的数据得到重建,实现了工程图标题栏信息的快速生成及国标化,扩展了Inventor 终端用 户界面的功能。     

Verification of Safety Properties Using Integer Programming: Beyond the State Equation

The state equation is a verification technique that has been applied—not always under this name—to numerous systems modelled as Petri nets or communicating automata. Given a safety property P, the state equation is used to derive a necessary condition for P to hold which can be mechanically checked. The necessary conditions derived from the state equation are known to be of little use for systems communicating by means of shared variables, in the sense that many of these systems satisfy the property but not the conditions. In this paper, we use traps, a well-known notion of net theory, to obtain stronger conditions that can still be efficiently checked. We show that the new conditions significantly extend the range of verifiable systems.     

Beyond Music Sharing: An Evaluation of Peer-to-Peer Data Dissemination Techniques in Large Scientific Collaborations

The avalanche of data from scientific instruments and the ensuing interest from geographically distributed users to analyze and interpret it accentuates the need for efficient data dissemination. A suitable data distribution scheme will find the delicate balance between conflicting requirements of minimizing transfer times, minimizing the impact on the network, and uniformly distributing load among participants. We identify several data distribution techniques, some successfully employed by today’s peer-to-peer networks: staging, data partitioning, orthogonal bandwidth exploitation, and combinations of the above. We use simulations to explore the performance of these techniques in contexts similar to those used by today’s data-centric scientific collaborations and derive several recommendations for efficient data dissemination. Our experimental results show that the peer-to-peer solutions that offer load balancing and good fault tolerance properties and have embedded participation incentives lead to unjustified costs in today’s scientific data collaborations deployed on over-provisioned network cores. However, as user communities grow and these deployments scale, peer-to-peer data delivery mechanisms will likely outperform other techniques.     

数据融合技术在航空发动机试验中的应用

将分布图法和基于算术平均值与分批估计的数据融合方法应用到航空发动机试验稳态数据采集的性能计算中,使稳态数据更准确地反映发动机的性能.这种方法计算简单,易于实现,具有较高的可靠性,通过在某型航空发动机试车台的实际应用结果证明了该方法的有效性.