Search results for "General Computer Science"
showing 10 items of 895 documents
Characterizing cavity-like spaces in active-site models of zeolites
2003
A method for the calculation of fractal surfaces of crystals is presented. The fractal dimension of fragments of zeolites is computed. Results compare well with reference calculations performed with program GEPOL. The active site of Bronsted acid zeolites is modelled by sets of Al–OH–Si units. These units form 2–12-membered rings. Topological indices for the different active-site models are computed. The comparison of calculations performed with programs GEPOL and SURMO2 allows computing the model indices. The cavity-like globularity and rugosity show sharp discontinuities for the ring with 6 units. Most cavity-like spaces show no fractal character. However, the 6–8-ring cavity-like spaces …
SQL Education
2020
Structured Query Language (SQL) skills are crucial in software engineering and computer science. However, teaching SQL effectively requires both pedagogical skill and considerable knowledge of the language. Educators and scholars have proposed numerous considerations for the betterment of SQL education, yet these considerations may be too numerous and scattered among different fora for educators to find and internalize, as no systematic mappings or literature reviews regarding SQL education have been conducted. The two main goals of this mapping study are to provide an overview of educational SQL research topics, research types, and publication fora, and to collect and propagate SQL teachi…
Registration of arbitrary multi-view 3D acquisitions
2013
International audience; To register 3D meshes representing smooth surfaces we track the 3D digitization system using photogrammetric techniques and calibrations. We present an example by digitizing a 800 mm x 600 mm portion of a car door. To increase the tracking accuracy the 3D scanner is placed in a cubic frame of side 0.5 m covered with 78 targets. The target frame moves in a volume that is approximately 1100 mm x 850 mm x 900 mm, to digitize the area of interest. Using four cameras this target frame is tracked with of an accuracy of 0.03 mm spatially and 0.180 mrad angularly. A registration accuracy between 0.1 mm and 2 mm is reached. This method can be used for the registration of mesh…
Pre-emption in resource-constrained project scheduling
2008
Abstract The Resource-Constrained Project Scheduling Project (RCPSP), together with some of its extensions, has been widely studied. A fundamental assumption in this basic problem is that activities in progress are non-preemptable. Very little effort has been made to uncover the potential benefits of discrete activity pre-emption, and the papers dealing with this issue have reached the conclusion that it has little effect on project length when constant resource availability levels are defined. In this paper we show how three basic elements of many heuristics for the RCPSP – codification, serial SGS and double justification – can be adapted to deal with interruption. The paper is mainly foc…
Justification and RCPSP: A technique that pays
2005
Abstract The objective of this paper is to show that justification is a simple technique that can be easily incorporated in diverse algorithms for the resource-constrained project scheduling problem––improving the quality of the schedules generated without generally requiring more computing time. The results of incorporating this technique in 22 different algorithms are shown. Fifteen of the new algorithms that use double justification outperform seven of the best heuristic algorithms that do not use justification. The tests have been performed on the standard test set j120 for the RCPSP generated using ProGen.
Design and implementation of a course scheduling system using Tabu Search
2002
Abstract Building a course timetable is a difficult and lengthy task which universities devote a large amount of human and material resources to every year. We have developed a computer package to solve this problem. The program runs on a PC and the user may set the objectives and parameters from among a wide range of possibilities. It has a user-friendly interface for the user to input the relevant data and obtain the corresponding results. The optimization process is based on a set of heuristic algorithms. The core is a Tabu Search procedure for which several strategies have been developed and tested in order to get a fast and powerful algorithm. The first tests of the package have produc…
A hybrid genetic algorithm for the resource-constrained project scheduling problem
2008
Abstract In this paper we propose a Hybrid Genetic Algorithm (HGA) for the Resource-Constrained Project Scheduling Problem (RCPSP). HGA introduces several changes in the GA paradigm: a crossover operator specific for the RCPSP; a local improvement operator that is applied to all generated schedules; a new way to select the parents to be combined; and a two-phase strategy by which the second phase re-starts the evolution from a neighbour’s population of the best schedule found in the first phase. The computational results show that HGA is a fast and high quality algorithm that outperforms all state-of-the-art algorithms for the RCPSP known by the authors of this paper for the instance sets j…
5G Functional Architecture and Signaling Enhancements to Support Path Management for eV2X
2019
Enhanced vehicle-to-everything (eV2X) communication is one of the most challenging use cases that the fifth generation (5G) of cellular mobile communications must address. In particular, eV2X includes some 5G vehicular applications targeting fully autonomous driving which require ultra-high reliability. The usual approach to providing vehicular communication based on single-connectivity transmission, for instance, through the direct link between vehicles (PC5 interface), often fails at guaranteeing the required reliability. To solve such a problem, in this paper, we consider a scheme where the radio path followed by eV2X messages can be proactively and dynamically configured to either trans…
Automatic Segmentation Using a Hybrid Dense Network Integrated With an 3D-Atrous Spatial Pyramid Pooling Module for Computed Tomography (CT) Imaging
2020
Computed tomography (CT) with a contrast-enhanced imaging technique is extensively proposed for the assessment and segmentation of multiple organs, especially organs at risk. It is an important factor involved in the decision making in clinical applications. Automatic segmentation and extraction of abdominal organs, such as thoracic organs at risk, from CT images are challenging tasks due to the low contrast of pixel values surrounding other organs. Various deep learning models based on 2D and 3D convolutional neural networks have been proposed for the segmentation of medical images because of their automatic feature extraction capability based on large labeled datasets. In this paper, we p…
Analysis of computer user behavior, security incidents and fraud using Self-Organizing Maps
2019
Abstract This paper addresses several topics of great interest in computer security in recent years: computer users’ behavior, security incidents and fraud exposure on the Internet, due to their high economic and social cost. Traditional research has been based mainly on gathering information about security incidents and fraud through surveys. The novelty of the present study is given by the use of Self-Organizing Maps (SOMs), a visual data mining technique. SOMs are applied to two data sets acquired using two different methodologies for collecting data about computer security. First, a traditional online survey about fraud exposure, security and user behavior was used. Second, in addition …