Search results for "Computation"
showing 10 items of 7362 documents
A surface hopping algorithm for nonadiabatic minimum energy path calculations
2015
The article introduces a robust algorithm for the computation of minimum energy paths transiting along regions of near-to or degeneracy of adiabatic states. The method facilitates studies of excited state reactivity involving weakly avoided crossings and conical intersections. Based on the analysis of the change in the multiconfigurational wave function the algorithm takes the decision whether the optimization should continue following the same electronic state or switch to a different state. This algorithm helps to overcome convergence difficulties near degeneracies. The implementation in the MOLCAS quantum chemistry package is discussed. To demonstrate the utility of the proposed procedur…
Effect of kinks and concerted diffusion mechanisms on mass transport and growth on stepped metal surfaces
1997
Abstract We study the effect of kinks and concerted atomic mechanisms on diffusion processes relevant to metal-on-metal homoepitaxy on fcc metal surfaces vicinal to the fcc (100) direction. First, we carry out extensive finite-temperature molecular dynamics simulations based on the effective medium theory to search for diffusion mechanisms that dominate the mass transport perpendicular and parallel to step edges. Then, the energetics of these processes are studied by ground state calculations. Our results show that kinks play an important role for diffusion both across and along step edges. In particular, the combined effect of kinks and concerted exchange is found to be able to remove loca…
Evaluation of the Thermodynamic Performance of the Traditional Passive Systems
2011
The need to reduce urban consumption of energy in the buildings, one of the major energy waster resulting in emission of CO2, is pushing research in the field of building design to the appreciation of passive air-conditioning systems that can be integrated with conventional systems and determine, therefore, the so-called hybrid systems. Historically this passive systems were developed in the Mediterranean and in the Middle East area. Actually the research activity has been focused on this problem, through an approach that involves the application of design strategies and the development of computational tools and control systems. The synergy between current scientific knowledge, advanced ma…
Memetic Engineering for Permanent Education in Line with Sustainable Growth
2012
Given the recent point of view of the European Commission regarding the implementation of a new strategy for sustainable growth and jobs, this paper emphasises the opportunity and urgency of supporting the EU 2020 strategy, providing an appropriate educational tool for the knowledge society. The main objectives are: a. adapting memetic engineering expressed in terms of General System Theory to the teaching component of permanent education based on bounded rationality and "Just in Time"as key tools for fighting cognitive chaoplexity in the post-industrial era; b. facilitating the use of memetic engineering based on its double-faceted nature: as both positive and negative feedback; c. extendi…
About Objective 3-D Analysis of Airway Geometry in Computerized Tomography
2008
The technology of multislice X-ray computed tomography (MSCT) provides volume data sets with approximately isotropic resolution, which permits a noninvasive 3-D measurement and quantification of airway geometry. In different diseases, like emphysema, chronic obstructive pulmonary disease (COPD), or cystic fribrosis, changes in lung parenchyma are associated with an increase in airway wall thickness. In this paper, we describe an objective measuring method of the airway geometry in the 3-D space. The limited spatial resolution of clinical CT scanners in comparison to thin structures like airway walls causes difficulties in the measurement of the density and the thickness of these structures.…
Electronic structure trends of Möbius graphene nanoribbons from minimal-cell simulations
2014
Investigating topological effects in materials requires often the modeling of material systems as a whole. Such modeling restricts system sizes, and makes it hard to extract systematic trends. Here, we investigate the effect of M\"obius topology in the electronic structures of armchair graphene nanoribbons. Using density-functional tight-binding method and minimum-cell simulations through revised periodic boundary conditions, we extract electronic trends merely by changing cells' symmetry operations and respective quantum number samplings. It turns out that for a minimum cell calculation, once geometric and magnetic contributions are ignored, the effect of the global topology is unexpectedl…
SEAL: A Domain-Specific Language for Novice Wireless Sensor Network Programmers
2013
A lot of the prospective wireless sensor network users are novice programmers. Their experience in general-purpose programming languages is either limited or completely nonexistent. There are both financial and scientific incentives to empower these users and allow them to write sensor network applications on their own, rather than having to rely on a qualified computer science professional. We present SEAL, a sensor network programming language designed for novice programmers. SEAL manages to avoid computer science concepts that are hard to grasp for novices, while remaining suitable for typical sensor network application scenarios. The language is extensible in application-specific way, h…
Synthesis, chemical characterization, computational studies and biological activity of organotin(IV) compounds interacting with enzymes involoved in …
2015
Our studies deal with the synthesis, the chemical characterization of organotin(IV) complexes of molecules, as caffeic acid, interacting with enzymes involved in epigenetic regulation.
Three-dimensional phase unwrapping using the Hungarian algorithm.
2009
We propose a three-dimensional phase unwrapping technique that uses the Hungarian algorithm to join together all the partial residual loops that may occur in a wrapped phase volume. Experimental results have shown that the proposed algorithm is more robust and reliable than other well-known three-dimensional phase unwrapping algorithms. Additionally, the proposed algorithm is fast in terms of computational complexity, which makes it suitable for practical applications.
Simulation and Test of UAV Tasks With Resource-Constrained Hardware in the Loop
2021
Simulations are indispensable to reduce costs and risks when developing and testing algorithms for unmanned aerial vehicles (UAV) especially for applications in high risk scenarios like search and rescue (SAR) operations and post-disaster damage assessment. Many UAV applications require real-time tasks for which the timeliness of computations is fundamental. However, standard simulation tools are not guaranteed to run in sync with real-time events, leading to unreliable assessments of the ability of the target hardware to perform specific tasks. In this work we present a simulation and test system able to run UAV tasks on resource-constrained target hardware possibly adopted in these applic…