Two approaches to on-line graphics systems

This article describes two types of software systems which provide an interface to users who wish to apply the power of interactive graphics to their specific problem. The systems are based on an 8K IMLAC PDS-1 minicomputer CRT display which provides sufficient processor power to handle display generation, management, and dynamic manipulation. The minicomputer software was first designed as an independent operating system which not only provides the user with high-speed timesharing access to the host computer, but also the resources of the local processor and its associated input/output devices. In this configuration, host compiled FORTRAN IV programs are loaded into the minicomputer through the timesharing link and executed independently from the host processor. A higher degree of processing is provided by the master-slave relationship between a local DEC PDP $\text{11}\text{40}$ minicomputer and the IMLAC. The user's FORTRAN IV program, executing in the PDP $\text{11}\text{40}$, directs an IMLAC graphics subsystem through subroutine calls. These systems provide the programmer with a foundation for a broad range of high level applications involving computer graphics.     

Two approaches to direct block-support conditional co-simulation

Change of support is a common issue in the geosciences when the volumetric support of the available data is smaller than that of the blocks on which numerical modeling is required. In this paper, we present two algorithms for the direct block-support simulation of cross-correlated random fields that are monotonic transforms of stationary Gaussian random fields. The first algorithm is a variation of sequential Gaussian co-simulation, in which each block value is simulated in turn, conditionally to the original data and to the previously simulated block values, while the second algorithm is based on spectral co-simulation in the framework of the discrete Gaussian change-of-support model. These two algorithms are implemented in computer programs and applied to a synthetic case study and to a mining case study. Their properties and performances are compared and discussed.     

Two approaches to the integration of heterogeneous data warehouses

In this paper we address the problem of integrating independent and possibly heterogeneous data warehouses, a problem that has received little attention so far, but that arises very often in practice. We start by tackling the basic issue of matching heterogeneous dimensions and provide a number of general properties that a dimension matching should fulfill. We then propose two different approaches to the problem of integration that try to enforce matchings satisfying these properties. The first approach refers to a scenario of loosely coupled integration, in which we just need to identify the common information between data sources and perform join operations over the original sources. The goal of the second approach is the derivation of a materialized view built by merging the sources, and refers to a scenario of tightly coupled integration in which queries are performed against the view. We also illustrate architecture and functionality of a practical system that we have developed to demonstrate the effectiveness of our integration strategies. A preliminary version this paper appeared, under the title “Integrating Heterogeneous Multidimensional Databases” [9], in 17th Int. Conference on Scientific and Statistical Database Management, 2005.     

Two different approaches to computer-aided teaching of microbial genetics

Two computer packages have been developed to teach bacterial genetics on an introductory genetics course for undergraduate students in biology. The first package, 'CONJUGACION', is designed to teach bacterial conjugation and its genetic outcomes. It includes four main parts. Firstly, a tutorial part presents a theoretical framework using screens of text and animated graphics. Secondly, an interactive concept application section requires students to carry out experiments for the determination of the correct sex and genotype of 10 bacterial strains. The third part uses the previously obtained data for simulating interrupted mating experiments and mapping the bacterial genome. Finally, an evaluation section allows the students to test their understanding through a series of multiple choice questions. The second package, 'LURIDEL', is intended for teaching the preadaptative character of mutation in bacterial populations on the basis of the fluctuation test of Luria and Delbrück. It simulates, graphically, the appearance of mutations in microbial cultures and gives results of simulated fluctuation experiments. Programs were written under the PCOS operating system in MBASIC extended to graphics for running on Olivetti M20 microcomputers.     

Two approaches to the mathematical modeling of detonation waves

The work is dedicated to the numerical investigation of different propagation regimes of a gaseous pulsating detonation wave using two approaches. In the first one, the problem is solved in the laboratory frame and the detonation is initiated near the closed end of the channel. In the second approach, the simulation is carried out in the shock-attached frame. For this purpose, a second approximation order algorithm for the integration of the shock evolution equation using the grid-characteristic method is proposed. The stable, weakly unstable, and irregular regimes of detonation wave propagation are investigated using both approaches. The qualitative and quantitative differences between the two approaches are put forward.     

Measuring structural similarity of semistructured data based on information-theoretic approaches

We propose and experimentally evaluate different approaches for measuring the structural similarity of semistructured documents based on information-theoretic concepts. Common to all approaches is a two-step procedure: first, we extract and linearize the structural information from documents, and then, we use similarity measures that are based on, respectively, Kolmogorov complexity and Shannon entropy to determine the distance between the documents. Compared to other approaches, we are able to achieve a linear run-time complexity and demonstrate in an experimental evaluation that the results of our technique in terms of clustering quality are on a par with or even better than those of other, slower approaches.     

Two approaches to the dynamic analysis of foundation beams subjected to subtangential forces

In this paper the dynamic analysis of a foundation beam on a two parameter elastic soil is illustrated in the presence of subtangential follower force. The differential quadrature method and the integral variational formulation Rayleigh-Ritz method are employed. The limiting subtangential coefficient is calculated, which gives the boundary between static and dynamic instability. The paper ends with some numerical examples which confirm the usefulness of the proposed methods.     

A family of similarity measures between two strings

We present a class of similarity measures for quantitatively comparing two strings, that is, two linearly ordered sets of elements. The strings can be of different lengths, the elements come from a single alphabet, and an element may appear any number of times. The limiting values of each measure are 0, when two completely different strings are compared, and 1, when the two strings are identical. Applications of similarity measures are numerous in nonnumerical computations, such as in heuristic search processes in associative networks, in pattern recognition and classification, in game playing programs, and in music and text analysis. We offer a number of feasible measures from among which some are discarded on plausibility grounds. One can select the measure most adequate for one's needs on the basis of a few characteristic examples of strings compared and by considering the specific requirements of the application at hand.     

Unsupervised approaches for measuring textual similarity between legal court case reports

Artificial Intelligence and Law - In the domain of legal information retrieval, an important challenge is to compute similarity between two legal documents. Precedents (statements from prior cases)...     

Evaluation of two heuristic approaches to solve the ontology meta-matching problem

Nowadays many techniques and tools are available for addressing the ontology matching problem, however, the complex nature of this problem causes existing solutions to be unsatisfactory. This work aims to shed some light on a more flexible way of matching ontologies. Ontology meta-matching, which is a set of techniques to configure optimum ontology matching functions. In this sense, we propose two approaches to automatically solve the ontology meta-matching problem. The first one is called maximum similarity measure, which is based on a greedy strategy to compute efficiently the parameters which configure a composite matching algorithm. The second approach is called genetics for ontology alignments and is based on a genetic algorithm which scales better for a large number of atomic matching algorithms in the composite algorithm and is able to optimize the results of the matching process.     

Context-aware artifacts: two development approaches

To create context-aware artifacts, developers can choose a self-supported or infrastructure-based approach. This article surveys these approaches and their implementations in various devices, also considering associated challenges and future research directions. Creating context awareness generally follows two main approaches. In self-supported context awareness, designers build the ability to perceive context, reason with it, and act accordingly into the device or its dedicated hardware support. In infrastructure-supported context awareness, designers obtain context-aware capabilities by harnessing a hardware and software infrastructure external to and associated with the device's space. Such an infrastructure might implement the context-aware behavior of specific objects and devices or act as a general context-aware infrastructure.     

Restricted arc-connectivity of digraphs

Since interconnection networks are often modeled by graphs or digraphs, the edge-connectivity of a graph or arc-connectivity of a digraph are important measurements for fault tolerance of networks.The restricted edge-connectivity λ^′(G) of a graph G is the minimum cardinality over all edge-cuts S in a graph G such that there are no isolated vertices in G−S. A connected graph G is called λ^′-connected, if λ^′(G) exists.In 1988, Esfahanian and Hakimi [A.H. Esfahanian, S.L. Hakimi, On computing a conditional edge-connectivity of a graph, Inform. Process. Lett. 27 (1988), 195-199] have shown that each connected graph G of order n?4, except a star, is λ^′-connected and satisfies λ^′(G)?ξ(G), where ξ(G) is the minimum edge-degree of G.If D is a strongly connected digraph, then we call in this paper an arc set S a restricted arc-cut of D if D−S has a non-trivial strong component D₁ such that D−V(D₁) contains an arc. The restricted arc-connectivity λ^′(D) is the minimum cardinality over all restricted arc-cuts S.We observe that the recognition problem, whether λ^′(D) exists for a strongly connected digraph D is solvable in polynomial time. Furthermore, we present some analogous results to the above mentioned theorem of Esfahanian and Hakimi for digraphs, and we show that this theorem follows easily from one of our results.     

An examination of two mental workload measurement approaches to understanding multimedia learning

This study reports on an examination of two measures of mental workload: the NASA-TLX and Paas’ Subjective Cognitive Load (SCL) measure. The goal was to assess the relative efficacy of the measures in the design and research of multimedia learning environments. Benchmarks based on the literature as to the goals for mental workload measurement in learning research are established. A multifaceted study was conducted which manipulated various aspects of mental workload in order to study the utility of these two measures in detecting changes in load and their relationship to learning outcomes. The results indicate that the weighted version of the NASA-TLX provided little additional value over the unweighted version of the measure. While both the NASA-TLX and SCL measures were sensitive to changes in both intrinsic and extraneous load, the study revealed differences in the measures based on levels of each of these load factors. The study also concludes that a better understanding of the third factor, germane load, will be needed to both expand the theoretical framework about mental workload in instructional settings and further understand the utility of these two measures.     

Two approaches to describing the turbulent exchange within the atmospheric surface layer

Two two-dimensional models that describe the interaction of an air flow with a heterogeneous vegetation cover within the atmospheric surface layer are presented. These models differ in the closure techniques used to obtain approximate solutions of the averaged system of the Navier?Stokes and continuity equations and also in the approaches applied to describe the interaction of the air flow with elements of vegetation. The first model is based on the one-and-a-half-order closure scheme and the interaction of an air flow with elements of vegetation is described using the viscous drag force. The second model uses the first-order closure scheme and the distribution of the wind velocity field near the boundaries between different vegetation communities is simulated by the theory of contrast structures (CSs). We also present the results of the numerical experiments to compare the developed models with respect to their ability to describe the wind-velocity field within the atmospheric surface layer above the different forms of vegetation cover heterogeneity, such as a forest belt and clear-cut areas.     

Two simple approaches to fabricate Au microlines on the outer surfaces of micropipettes

Various lithographic approaches have been developed to generate patterns on flat and non-flat surfaces. However, it still remains a challenge to produce patterns on irregular surfaces, such as on the curved tip of a glass micropipette. To overcome this challenge, we have developed two new approaches in this work, and explored the possibility of applying them to generate Au microlines on the outer surfaces of glass micropipettes. A glass micropipette includes a straight tube and a curved tip. In either approach, the outer surface of the glass micropipette was first thermally coated with a thin Au film. A photoresist (PR)-coated membrane was then pushed against this glass micropipette when the PR was still wet. During the contact, part of the PR was transferred from the membrane to the micropipette. After the membrane was removed, a continuous PR line was left on the outer surface of the glass micropipette. This line extended from the straight tube to the end of the curved tip. Another PR line was further generated on the other side of this micropipette using the same process. Finally, after the Au film was etched using the two PR lines as the masking patterns, followed by the removal of the PR using acetone, two Au lines were generated on the outer surface of the glass micropipette. The two approaches mainly differed in the ways of pressing the PR-coated membrane against the curved tip of the micropipette. In the first approach, a clip was applied for this purpose, while in the second approach a nitrogen flux was employed to make the membrane have intimate contact with the curved tip. To date, we have successfully fabricated Au lines on glass micropipettes of tip sizes down to 35 and 5???m, respectively, using the two approaches.     

Two new models for determining OWA operator weights

The determination of ordered weighted averaging (OWA) operator weights is a very crucial issue of applying the OWA operator for decision making. This paper proposes two new models for determining the OWA operator weights. The weights determined by the new models do not follow a regular distribution and therefore make more sense than those obtained by other methods.     

Upward drawings of triconnected digraphs

A polynomial-time algorithm for testing if a triconnected directed graph has an upward drkwing is presented. An upward drkwing is a planar drkwing such that all the edges flow in a common direction (e.g., from bottom to top). The problem arises in the fields of automatic graph drkwing and ordered sets, and has been open for several years. The proposed algorithm is based on a new combinatorial characterization that maps the problem into a max-flow problem on a sparse network; the time complexity isO(n+r ²⁾ , wheren is the number of vertices andr is the number of sources and sinks of the directed graph. If the directed graph has an upward drkwing, the algorithm allows us to construct one easily.This work was partially supported by the Progetto Finalizzato Sistemi Informatici e Calcolo Parallelo of the Italian National Research Council (CNR) Sottoprogetto 6, Infokit and by the ESPRIT II Basic Research Actions Program of the EC (project ALgorithms and COMplexity). An extended abstract of this paper has been presented in P. Bertolazzi and G. Di Battista, On Upward Drkwing Testing of Triconnected Digraphs,Proc. 7th ACM Symposium on Computational Geometry, pp. 272–280, 1991.     

On characterization of periodic digraphs

We investigate the problem of describing subgraphs of periodic digraphs. A necessary and sufficient condition is obtained for a digraph to be a subgraph of a periodic digraph.Translated from Kibernetika, No. 1, pp. 41–44, January–February, 1989.