How to construct small probabilistic roadmaps with a good coverage?

We investigate how we can construct small probabilistic roadmaps in a reasonable time while still keeping a good coverage and connectivity. We propose a new neighborhood-based method that can reduce the size of the roadmaps by filtering out unnecessary nodes. We then experimentally test it against a basic probabilistic roadmap planner and a visibility-based planner. We use both a uniform sampling and a bridge test sampling in our tests. The results show that the neighborhood-based method can reduce the number of nodes considerably. The neighborhood-based method is simple to implement, it works well with a uniform sampling, and it does not need any additional parameters when compared with the basic planner.     

Kernel selection in multi-class support vector machines and its consequence to the number of ties in majority voting method

Support vector machines are a relatively new classification method which has nowadays established a firm foothold in the area of machine learning. It has been applied to numerous targets of applications. Automated taxa identification of benthic macroinvertebrates has got generally very little attention and especially using a support vector machine in it. In this paper we investigate how the changing of a kernel function in an SVM classifier effects classification results. A novel question is how the changing of a kernel function effects the number of ties in a majority voting method when we are dealing with a multi-class case. We repeated the classification tests with two different feature sets. Using SVM, we present accurate classification results proposing that SVM suits well to the automated taxa identification of benthic macroinvertebrates. We also present that the selection of a kernel has a great effect on the number of ties.     

Incremental constraint modelling in a feature modelling system

The techniques of constraint propagation have recently been successfully applied to feature-based design. Because of their speed, constraint propagation methods allow incremental design and rapid local modifcations of the part. However, cyclic constraints cause serious problems to current constraint propagation algorithms. Variational geometric design systems can, in principle, manage these cases. Unfortunately, this typically requires complete re-evaluation of the underlying set of constraint equations, making the method unsuitable for interactive use. The proposed system aims to localize the problem of constraint solving and maintenance. The constraint graph of the part or assembly is divided into several independent partial graphs, subsystems. Afterwards, each subsystem is handled separately using a selected constraint solving technique for the subsystem.     

Application of oxygen-consumption calorimetry to non-combustibility testing

The feasibility of oxygen-consumption calorimetry to testing of non-combustibility of building materials is studied. The reasons for the ambiguities of the traditional test method are qualitatively discussed. The construction of the gas collecting system added to the conventional test apparatus is described and the necessary formulae for calculating the oxygen consumption and the simultaneously measured conventional test variables are compared. The results clearly suggest that oxygen-consumption calorimetry is a consistent and powerful method for determining the non-combustibility of building materials.     

Ray-casting and block model conversion using a spatial index

A spatial index is a data structure designed to facilitate spatial search, exemplified by the point-in-polyhedron inclusion problem. The 3D extensible cell (EXCELL) index is presented together with algorithms for spatial search and for converting a complex polyhedron (boundary representation) into an octree-like block model. We illustrate the techniques by an application to geometric mine modelling and demonstrate the efficiency of the approach by practical experiments.     

Large-scale compressed hydrogen storage as part of renewable electricity storage systems

Storing energy in the form of hydrogen is a promising green alternative. Thus, there is a high interest to analyze the status quo of the different storage options. This paper focuses on the large-scale compressed hydrogen storage options with respect to three categories: storage vessels, geological storage, and other underground storage alternatives. In this study, we investigated a wide variety of compressed hydrogen storage technologies, discussing in fair detail their theory of operation, potential, and challenges. The analysis confirms that a techno-economic chain analysis is required to evaluate the viability of one storage option over another for a case by case. Some of the discussed technologies are immature; however, this does not rule out these technologies; rather, it portrays the research opportunities in the field and the foreseen potential of these technologies. Furthermore, we see that hydrogen would have a significant role in balancing intermittent renewable electricity production.     

The relationship between cardiac reactivity in the laboratory and in real life.

Objective: An excessive cardiovascular response to acute stress is a probable risk factor for cardiovascular (CV) disease. Such reactivity is usually assessed from the CV response to laboratory stressors. However, if it is a risk factor, correlated responses must occur in real life. Design: In the present study, we investigated the relationship between the heart rate (HR) response to five laboratory stressors and HR reactivity in the field. Measures: HR variation, the response to a real life stressor (public speaking), and the increase in HR with periods of self-reported tense arousal. Ambulatory HR, activity and posture were measured continuously over a 7-hr period. Results: The HR increase to laboratory stressors did not relate to HR variation consistently, but it did relate to the other two field measures. Conclusion: The results suggested that a tendency to increased HR reactivity may be a risk factor for cardiovascular disease when combined with exposure to stress. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Tracing the equilibrium path beyond compound critical points

Procedures to handle critical points with coincident or nearly coincident buckling loads in a geometrically non‐linear continuation process are presented. The proposed branch switching algorithm is based on a Liapunov–Schmidt–Koiter‐type asymptotic reduction which is used for the prediction step into the post‐buckling range. A critical review of the existing methodology for the numerical treatment of post‐bifurcation branches at a multiple bifurcation point is also given. In the review the main emphasis is given to robustness, but also implementational issues and computational requirements are addressed. Some modifications to the existing algorithms are proposed in order to improve their robustness or efficiency. Numerical examples of a flat plate and a thin‐walled structure are shown. Copyright © 1999 John Wiley & Sons, Ltd.