Generating and characterizing the perfect elimination orderings of a chordal graph

We develop a constant time transposition “oracle” for the set of perfect elimination orderings of chordal graphs. Using this oracle, we can generate a Gray code of all perfect elimination orderings in constant amortized time using known results about antimatroids. Using clique trees, we show how the initialization of the algorithm can be performed in linear time. We also develop two new characterizations of perfect elimination orderings: one in terms of chordless paths, and the other in terms of minimal u-v separators.     

A software tool for generating graphics by means of P systems

The hand-made graphical representation of the configuration of a P system becomes a hard task when the number of membranes and objects increases. In this paper we present a new software tool, called JPLANT, for computing and representing the evolution of a P system model with membrane creation. We also present some experiments performed with JPLANT and point out new lines for the research in computer graphics with membrane systems.     

Snow depth inverted by scattering indices of SSM/I channels in a mesh graph

The accuracy of snow depth estimation is affected significantly by the regional surface type. We have developed a theoretical model of vector radiative transfer (VRT) for snowpack/vegetation canopies at SSM/I channels. The vegetation canopy is modelled by a layer of nonspherical particles, and the snowpack is modelled as a layer of dense spherical particles. By numerically solving two coupled VRT equations for multi-layer models of different surface types such as tree/snow, grass/snow and snowpack only, two scattering indices SI1 = T B19v - T B37v and SI2 = T B22v - T B85v are obtained for a variety of snow depths (SD) and ice-grain sizes. These results are combined as a mesh graph in the figure of SI1 versus SI2 . When the SSM/I TB data is observed, its location in the mesh graph can indicate the estimation of SD. Our results compare well with the SSM/I data of the U.S.A. east coast January blizzard, 1996.     

A combination of spectral graph theory and quantum genetic algorithm to find relevant set of electrodes for motor imagery classification

At present, more number of electrodes are used to develop brain computer interface (BCI) devices based on motor imagery. However, the number of trials for a given subject is usually less. Under this situation, the performance of motor imagery task classification may degrade. In this research work, we propose a combination of graph theoretic spectral method and quantum genetic algorithm (QGA) to obtain a subset of relevant and non-redundant electrodes for effective motor imagery task classification. Stationary Common Spatial Pattern method, which can handle non-stationarity issue, is used for extraction of features from the reduced set of electrodes. Support Vector Machine (SVM) is used as a classifier. Improvement in classification performance on publicly available dataset signifies efficacy of the proposed method. Friedman statistical test demonstrates that the performance of the proposed method is significantly better in comparison to existing CSP and its variants.     

Centralities of a network and its line graph: an analytical comparison by means of their irregularity

Given a network G, it is known that the Bonacich centrality of the bipartite graph B(G) associated with G can be obtained in terms of the centralities of the line graph L(G) associated with G and the centrality of the network G+gr (whose adjacency matrix is obtained by adding to the adjacency matrix A(G) the diagonal matrix D=b_ij, where b_ii is the degree of node i in G) and conversely. In this contribution, we use the centrality of G to estimate the centrality of G+gr and show that the error committed is bounded by some measure of the irregularity of G. This estimate gives an analytical comparison of the eigenvector centrality of G with the centrality of L(G) in terms of some irregularity measure of G.     

The development of competencies in manufacturing engineering by means of a deep-drawing tool

This paper presents a Computer-aided System known as the deep-drawing tool applied to the resolution of a combined deep-drawing and ironing process. The system allows the user for selecting input data for getting the formability of material to deep-drawing, selecting the process that provides the best solution from a technological perspective, optimizing the process for material waste, knowing the influence of the punch in the results and considering the process cost. In this manner, the tool allows developing competencies to students that apply scientific, technological, mathematical, economical and sustainable knowledge, with a global vision of the manufacturing processes and conciliating research and teaching. An industrial case has been considered and the proposed Computer-aided System has been tested with a brass alloy to demonstrate the system’s capability. The results obtained show significant improvements in the two variables analyzed, namely, total process time and total manufacturing cost. These aspects provide competencies to students in the manufacturing environment.     

Optimal control theory: A generic tool for identification and control of (bio-)chemical reactors

In this review paper the potential of optimal control theory for optimization in the time as well as in the space domain is highlighted. Various case studies in the area of (bio-)chemical reactors are discussed ranging from the dual problem of performance optimization and accurate parameter identification (time domain) to plug flow reactor optimization (space domain). Furthermore, it is illustrated that application of the Minimum Principle of Pontryagin to distributed parameter systems leads to extremal control profile structures (in the space domain) which are very similar to those obtained during optimization (in the time domain) of well mixed bioreactors. The analogy is reflected at various levels during analytical optimal control computations.     

囊泡表面氨基酸信号分子与维生素B6衍生物受体反应平衡常数的估计

为了构建一个新的以维生素B₆衍生物(PL⁺C₁₆)为受体、氨基酸为信号分子的人工细胞信号转导超分子体系,测定在40℃、pH值分别为7.0、8.0及9.0的缓冲液体系下,4种信号分子（甘氨酸、β-丙氨酸、γ-氨基丁酸、天冬氨酸）在不同初始浓度下与受体PL⁺C₁₆反应的吸光度,通过用MATLAB模型拟合工具包将其实验数据进行非线性拟合,估计反应的平衡常数K,定量考察了4种信号分子到达人工细胞膜载体表面与受体分子的结合能力。结果表明:不同pH值下,同一氨基化合物与受体PL⁺C₁₆反应的平衡常数K有明显差异,而在同一pH值下,不同氨基酸与受体的K值也有很大差别,其中pH值为9.0时,天冬氨酸的K值最大,与受体PL⁺C₁₆的结合能力最强。     

Analysis of utility and use of a web-based tool for digital signal processing teaching by means of a technological acceptance model

This paper presents an exploratory study about the development of a structural and measurement model for the technological acceptance (TAM) of a web-based educational tool. The aim consists of measuring not only the use of this tool, but also the external variables with a significant influence in its use for planning future improvements. The tool, designed with Shockwave™ and Macromedia Director™, is a web-based educational environment that has been applied as a teaching methodology in an undergraduate course involved with modern microprocessors architectures and applications. The proposed methodology may be extensible to similar tools and tries to fill the lack of scientific studies in the validation and acceptance of computer-based educational tools.     

Analysis of utility and use of a web-based tool for digital signal processing teaching by means of a technological acceptance model

This paper presents an exploratory study about the development of a structural and measurement model for the technological acceptance (TAM) of a web-based educational tool. The aim consists of measuring not only the use of this tool, but also the external variables with a significant influence in its use for planning future improvements. The tool, designed with Shockwave™ and Macromedia Director™, is a web-based educational environment that has been applied as a teaching methodology in an undergraduate course involved with modern microprocessors architectures and applications. The proposed methodology may be extensible to similar tools and tries to fill the lack of scientific studies in the validation and acceptance of computer-based educational tools.     

SimQPN—A tool and methodology for analyzing queueing Petri net models by means of simulation

The queueing Petri net (QPN) paradigm provides a number of benefits over conventional modeling paradigms such as queueing networks and generalized stochastic Petri nets. Using queueing Petri nets (QPNs), one can integrate both hardware and software aspects of system behavior into the same model. This lends itself very well to modeling distributed component-based systems, such as modern e-business applications. However, currently available tools and techniques for QPN analysis suffer the state space explosion problem, imposing a limit on the size of the models that are tractable. In this paper, we present SimQPN—a simulation tool for QPNs that provides an alternative approach to analyze QPN models, circumventing the state space explosion problem. In doing this, we propose a methodology for analyzing QPN models by means of discrete event simulation. The methodology shows how to simulate QPN models and analyze the output data from simulation runs. We validate our approach by applying it to study several different QPN models, ranging from simple models to models of realistic systems. The performance of point and interval estimators implemented in SimQPN is subjected to a rigorous experimental analysis.     

Solving the kinematics and dynamics of a modular spatial hyper-redundant manipulator by means of screw theory

In this contribution, a systematic methodology for solving the kinematic and dynamic analyses of a modular spatial hyper-redundant manipulator built with an optional number of serially connected three-legged in-parallel manipulators are presented. First, the kinematics and dynamics of the base module are carried out using the theory of screws and the principle of virtual work. Next, the expressions obtained for the base module are extended without significant effort to the spatial hyper-redundant manipulator under study. Finally, the proposed methodology of analysis is applied to a 18 degrees of freedom hyper-redundant manipulator.     

Improving the accuracy of a flood forecasting model by means of machine learning and chaos theory

Monitoring natural environments is a challenging task on account of their hostile features. The use of wireless sensor networks (WSNs) for data collection is a feasible method since these domains lack any infrastructure. However, further studies are required to handle the data collected for a better modeling of behavior and thus make it possible to forecast impending disasters. In light of this, in this paper an analysis is conducted on the use of data gathered from urban rivers to forecast flooding with a view to reducing the damage it causes. The data were collected by means of a WSN in São Carlos, São Paulo State, Brazil, which gathered and processed data about the river level and rainfall by means of machine learning techniques and employing chaos theory to model the time series; this meant that the inputs of the machine learning technique were the time series gathered by the WSN modeled on the basis of the immersion theorem. The WSNs were deployed by our group in the city of São Carlos where there have been serious problems caused by floods. After the data interdependence had been established by the immersion theorem, the artificial neural networks were investigated to determine their degree of accuracy in the forecasting models.     

Recovery of missing information in graph sequences by means of reference pattern matching and decision tree learning

Algorithms for the analysis of graph sequences are proposed in this paper. In particular, we study the problem of recovering missing information and predicting the occurrence of nodes and edges in time series of graphs. Two different recovery schemes are developed. The first scheme uses reference patterns that are extracted from a training set of graph sequences, while the second method is based on decision tree induction. Our work is motivated by applications in computer network analysis. However, the proposed recovery and prediction schemes are generic and can be applied in other domains as well.     

N-(羟乙基)-一枝蒿酮酸酰胺的合成、结构表征及量子化学计算

以一枝蒿酮酸和乙醇胺为原料,在DCC,HOBt和DMAP作用下合成了N-(羟乙基)-一枝蒿酮酸酰胺衍生物,采用IR,1H NMR,ESI-MS技术表征,根据ESI-MS给出的碎片信息,解析了该化合物的裂解过程,并采用量子化学理论,在DFT-B3LYP/6-31G(d)基组下计算了该化合物的优化结构参数、电荷分布、分子总...     

Exploring activity theory as a tool for evaluating interactivity and learning in virtual environments for children

This paper explores the use of Activity Theory for the evaluation of user behaviour in immersive virtual environments. Specifically, the study of user behaviour focuses on interactivity, which is argued to be one of the most important processes that take place between a user and the system in virtual reality. The ultimate intention is to study the role and the effect of interactivity on learning and conceptual change and to examine how interaction and conceptual learning are related in the context of virtual environments developed primarily for informal educational settings. As a first step to this study, a set of exploratory experiments was carried out with children aged 7–12. The children were asked to complete tasks, such as the assembly of ancient columns from parts, which were designed to promote constructivist learning and explore the methods of carrying out in-depth experiments with children. This paper describes the analysis of these exploratory case studies from an Activity Theory perspective.

基于多色图的宗地信息历史回溯模型及实现

为解决宗地信息历史回溯问题,基于多色图理论,建立了宗地信息历史回溯模型,将宗地抽象为多色图中的节点,宗地间的变更关系抽象为多色图中的边,用节点和边的不同颜色分别表示宗地的不同状态及宗地间不同的变更关系;提出了回溯矩阵的赋值算法及历史回溯算法;设计了宗地变更业务相关数据结构,分析了计算机后台处理程序,开发了宗地变更业务的原型系统,表明了该模型和算法的可行性.     

Estimation of leaf and canopy water content in poplar plantations by means of hyperspectral indices and inverse modeling

This study investigates the applicability of empirical and radiative transfer models to estimate water content at leaf and landscape level. The main goal is to evaluate and compare the accuracy of these two approaches for estimating leaf water content by means of laboratory reflectance/transmittance measurements and for mapping leaf and canopy water content by using airborne Multispectral Infrared and Visible Imaging Spectrometer (MIVIS) data acquired over intensive poplar plantations (Ticino, Italy).At leaf level, we tested the performance of different spectral indices to estimate leaf equivalent water thickness (EWT) and leaf gravimetric water content (GWC) by using inverse ordinary least squares (OLS) regression, and reduced major axis (RMA) regression. The analysis showed that leaf reflectance is related to changes in EWT rather than GWC, with best results obtained by using RMA regression by exploiting the spectral index related to the continuum removed area of the 1200 nm water absorption feature with an explained variance of 61% and prediction error of 6.6%. Moreover, we inverted the PROSPECT leaf radiative transfer model to estimate leaf EWT and GWC and compared the results with those obtained by means of empirical models. The inversion of this model showed that leaf EWT can be successfully estimated with no prior information with mean relative errors of 14% and determination coefficient of 0.65. Inversion of the PROSPECT model showed some difficulties in the simultaneous estimation of leaf EWT and dry matter content, which led to large errors in GWC estimation.At landscape level with MIVIS data, we tested the performance of different spectral indices to estimate canopy water per unit ground area (EWT_canopy). We found a relative error of 20% using a continuum removed spectral index around 1200 nm. Furthermore, we used a model simulation to evaluate the possibility of applying empirical models based on appositely developed MIVIS double ratios to estimate mean leaf EWT at landscape level (). It is shown that combined indices (double ratios) yielded significant results in estimating leaf EWT at landscape level by using MIVIS data (with errors around 2.6%), indicating their potential in reducing the effects of LAI on the recorded signal. The accuracy of the empirical estimation of EWT_canopy and was finally compared with that obtained from inversion of the PROSPECT + SAILH canopy reflectance model to evaluate the potential of both methods for practical applications. A relative error of 27% was found for EWT_canopy and an overestimation of leaf with relative errors around 19%.Results arising from this remote sensing application support the robustness of hyperspectral regression indices for estimating water content at both leaf and landscape level, with lower relative errors compared to those obtained from inversion of leaf and 1D canopy radiative transfer models.     

A sound and complete theory of graph transformations for service programming with sessions and pipelines

Graph transformation techniques, the Double-Pushout (DPO) approach in particular, have been successfully applied in the modeling of concurrent systems. In this area, a research thread has addressed the definition of concurrent semantics for process calculi. In this paper, we propose a theory of graph transformations for service programming with sophisticated features such as sessions and pipelines. Through graph representation of CaSPiS, a recently proposed process calculus, we show how graph transformations can cope with advanced features of service-oriented computing, such as several logical notions of scoping together with the interplay between linking and containment. We first exploit a graph algebra and set up a graph model that supports graph transformations in the DPO approach. Then, we show how to represent CaSPiS processes as hierarchical graphs in the graph model and their behaviors as graph transformation rules. Finally, we provide the soundness and completeness results of these rules with respect to the reduction semantics of CaSPiS.     

Software for bone histomorphometry by means of a digitizer

A set of programs is described by which a consistent morphometry of bone sections can be performed. The programs are written in FORTRAN IV in a PDP 11/10 minicomputer, under the RT-11 operating system. The bone sections are run through the field of vision of the microscope using a scanning stage in one of several preselected courses at a magnification suitable for the parameters that are being put in. When input is completed, a print-out is produced with measured and derived parameters, personal data (protected by a code) and a comment file, all of which are stored for later retrieval and statistical evaluation. The programs were developed to be used in a system in which the bone sections are projected (by a projection microscope) onto a digitizer connected to the computer.