Search results for "Calculus"
showing 10 items of 617 documents
Discretization estimates for an elliptic control problem
1998
An optimal control problem governed by an elliptic equation written in variational form in an abstract functional framework is considered. The control is subject to restrictions. The optimality conditions are established and the Ritz-Galerkin discretization is introduced. If the error estimate corresponding to the elliptic equation is given as a function like where h is the discretization parameter and is an integer, then the error estimates for the optimal control, for the optimal state and for the optimal value are obtained. These results are applied first for a Two-Point BVP and next for a 2D/3D elliptic problem as state equation. Next a spectral method is used in the discretization proc…
Guidance Trajectories for Spacecraft Rendezvous
2007
In a previous paper of Miele et al. (J. Optim. Theory Appl. 132(1), 2007), we employed the single-subarc sequential gradient-restoration algorithm to optimize the three-dimensional rendezvous between a target spacecraft in a planar circular orbit and a chaser spacecraft with an initial separation distance and separation velocity. The achieved continuous solutions are characterized by two, three, or four subarcs depending on the performance index (time, fuel) and the constraints. In this paper, based on the solutions in Miele et al. (J. Optim. Theory Appl. 132(1), 2007), we employ the multiple-subarc sequential gradient-restoration algorithm to produce pieced guidance trajectories implementa…
Obligations and Conditionals
2015
The paper considers two kinds of medieval obligational disputations (positio, rei veritas) and the medieval genre of sophismata in relation to the kinds of inferences accepted in them. The main texts discussed are the anonymous Obligationes parisienses from the early 13th century and Richard Kilvington’s Sophismata from the early 14th century. Four different kinds of warranted transition from an antecedent to a consequent become apparent in the medieval discussions: (1) the strong logical validity of basic propositional logic, (2) analytic validity based on conceptual containment, (3) merely semantic impossibility of the antecedent being true without the consequent, and (4) intuitively true…
Global conservative and multipeakon conservative solutions for the modified camassa-holm system with coupling effects
2014
Published version of an article in the journal: Mathematical Problems in Engineering. Also available from the publisher at: http://dx.doi.org/10.1155/2014/606249 This paper investigates the continuation of solutions to the modified coupled two-component Camassa-Holm system after wave breaking. The underlying problem is rather challenging due to the mutual coupling effect between two components in the system. By introducing a novel transformation that makes use of a skillfully defined characteristic and a set of newly defined variables, the original system is converted into a Lagrangian equivalent system, from which the global conservative solution is obtained, which further allows for the e…
The Moral Calculus of Vocational Passion in Digital Gaming
2019
The desire to “do what you love” energizes employment and engagement in creative industries such as digital gaming yet drains hobbyists and aspirants by normalizing expectations to sacrifice job security for passionate work. This article investigates how individuals regulate their aspirations through taken-for-granted trade-offs between vocational compromise and compensation. Multi-sited ethnographic fieldwork with players at fan conventions and recruitment events in North America suggests a moral calculus of corruption and sublimation between passion and profit, which can be traced back to industrialization’s cleavage of labor from recreation and its institution of hobbies as productive le…
A Cross-Cultural Perspective on the Privacy Calculus
2017
The “privacy calculus” approach to studying online privacy implies that willingness to engage in disclosures on social network sites (SNSs) depends on evaluation of the resulting risks and benefits. In this article, we propose that cultural factors influence the perception of privacy risks and social gratifications. Based on survey data collected from participants from five countries (Germany [ n = 740], the Netherlands [ n = 89], the United Kingdom [ n = 67], the United States [ n = 489], and China [ n = 165]), we successfully replicated the privacy calculus. Furthermore, we found that culture plays an important role: As expected, people from cultures ranking high in individualism found i…
Volume, energy and generalized energy of unit vector fields on Berger spheres: stability of Hopf vector fields
2005
We study to what extent the known results concerning the behaviour of Hopf vector fields, with respect to volume, energy and generalized energy functionals, on the round sphere are still valid for the metrics obtained by performing the canonical variation of the Hopf fibration.
Land surface air temperature retrieval from EOS-MODIS images
2014
The knowledge of the spatial and temporal patterns of surface air temperature (SAT) is essential to monitor a region's climate and meteorology, to quantify surface exchange processes, to improve climatic and meteorological model results, and to study health and economic impacts. This letter analyzed correlations between SAT and geophysical land surface variables, mainly land surface temperature (LST), to establish operative techniques to obtain spatially continuous land SAT maps from satellite data, unlike data provided by meteorological station networks. The correlations were analyzed by using EOS-MODIS images, meteorological station network data, and geographical variables. Linear regress…
Integrating resolution—like procedures with Lukasiewicz implication
1993
We discuss some conceptual and technical problems raised by the attempt of integrating resolution-like procedures with the use of Lukukasiewicz implication Min{1, 1 – [a] + [b]} in an environment of approximate reasoning modelled by fuzzy logics.
Bounding principles for elastic-plastic-creeping solids loaded below and above the shakedown limit
1982
Solids of elastic-perfectly plastic creeping material subjected to variable loads are considered within the infinitesimal displacement framework and a bounding principle is presented which holds below and above the shakedown limit. Through the choice of some free parameters, this principle generates a number of deformation bounds with practical meanings, some of wich coincide with known results for creeping and noncreeping material, while others constitute new results or generalizations of known results. The topic will be further studied in a subsequent paper [35].