Identifying routes and organizational practices for resilient performance: a study in the construction industry

Cognition, Technology & Work - Modern organizations live in a context of political, economic, technological, social and environmental changes for which they need to be prepared to adapt and...     

2-Covered paths by a set of antennas with minimum power transmission range

In this paper we describe and solve the following geometric optimisation problem: given a set S of n points on the plane (antennas) and two points A and B, find the smallest radial range r∈^ℜ+ (power transmission range of the antennas) so that a path with endpoints A and B exists in which all points are within the range of at least two antennas. The solution to the problem has several applications (e.g., in the planning of safe routes). We present an O(nlogn) time solution, which is based on the second order Voronoi diagram. We also show how to obtain a path with such characteristics.     

Modeling of noncatalytic fluid-solid reactions: The quasi-steady state assumption

An isothermal, topochemical model for noncatalytic fluid-solid reactions, in spherical pellets, is formulated, solved numerically, and investigated experimentally. The equations are transformed into dimensionless form in order to introduce characteristic dimensionless groups. The dimensionless groups represent the relative effects of the diffusional, fluid film transport, and chemical reaction rates on the system, as well as the ratio of the molar density of the reactant fluid to that of the reactant solid. The model is solved with and without the quasi-steady state assumption in order to investigate the effects of the values of the dimensionless groups on the error introduced by this assumption. The model, without the quasi-steady state assumption, is shown to be an accurate representation of a resin exchange system, and reduces to the quasi-steady state model for appropriate values of the dimensionless groups.     

A matrix model for the flow of control in prolog programs with applications to profiling

In Prolog the flow of control is relatively complex; four counts (which we call currents)—call, fail, succeed and redo—and two intrinsic properties—the failure and the ‘alternative’ probabilities—can be associated with every literal in a clause body. In this work we describe a new matrix model where those currents and properties are related at the literal, clause and predicate definition levels. This model is useful for predicate classification, execution profiling and program debugging. The application to profilers is discussed in detail.     

Exploring educational immersive videogames: an empirical study with a 3D multimodal interaction prototype

ABSTRACT

Gestural interaction devices emerged and originated various studies on multimodal human–computer interaction to improve user experience (UX). However, there is a knowledge gap regarding the use of these devices to enhance learning. We present an exploratory study which analysed the UX with a multimodal immersive videogame prototype, based on a Portuguese historical/cultural episode. Evaluation tests took place in high school environments and public videogaming events. Two users would be present simultaneously in the same virtual reality (VR) environment: one as the helmsman aboard Vasco da Gama’s fifteenth-century Portuguese ship and the other as the mythical Adamastor stone giant at the Cape of Good Hope. The helmsman player wore a VR headset to explore the environment, whereas the giant player used body motion to control the giant, and observed results on a screen, with no headset. This allowed a preliminary characterisation of UX, identifying challenges and potential use of these devices in multi-user virtual learning contexts. We also discuss the combined use of such devices, towards future development of similar systems, and its implications on learning improvement through multimodal human–computer interaction.     

Runtime verification of autopilot systems using a fragment of MTL- $${int }$$

International Journal on Software Tools for Technology Transfer - Current real-time embedded systems development frameworks lack support for the verification of properties using explicit time where...     

Linear programs in a simple reversible language

Very simple reversible programming languages can be useful for the study of reversible transformations. For this purpose we define simple reversible language (SRL), a very simple reversible language, and analyse its properties. The language SRL is similar to the “loop” languages that have been used by several authors to characterise the set of primitive recursive functions. There are, however, important differences: SRL has domain instead of and only reversible programs can be written in SRL. The reversibility of linear homogeneous SRL programs is related to the fact that the corresponding set of matrices has the algebraic structure of a group. We show that such programs implement exactly the linear transformations corresponding to the group of integer positive modular matrices, while in ESRL, an extended version of SRL, the set of transformations that can be implemented by linear homogeneous programs corresponds exactly to the group of integer modular matrices.     

SVM practical industrial application for mechanical faults diagnostic

A large percentage of the total induction motor failures are due to mechanical faults. It is well known that, machine’s vibration is the best indicator of its overall mechanical condition, and an earliest indicator of arising defects. Support vector machines (SVM) is also well known as intelligent classifier with strong generalization ability. In this paper, both, machine‘s vibrations and SVM are used together for a new intelligent mechanical fault diagnostic method. Using only one vibration sensor and only four SVM’s it was achieved improved results over the available approaches for this purpose in the literature. Therefore, this method becomes more attractive for on line monitoring without maintenance specialist intervention. Vibration signals turns out to occur in different directions (axial, horizontal or vertical) depending on the type of the fault. Thus, to diagnose mechanical faults it is necessary to read signals at various positions or use more them one accelerometer. From this work we also determined the best position for signals acquisition, which is very important information for the maintenance task.     

Linear optimal control problem of a system with circuit-free graph structure

We solve a linear optimal control problem with state and control restrictions by the method of region analysis, where the state equations describe the flow in a directed graph without a circuit. The results are used for the optimal control of a system of hydroelectric power plants.