1,635 research outputs found
A variational approach to path estimation and parameter inference of hidden diffusion processes
We consider a hidden Markov model, where the signal process, given by a
diffusion, is only indirectly observed through some noisy measurements. The
article develops a variational method for approximating the hidden states of
the signal process given the full set of observations. This, in particular,
leads to systematic approximations of the smoothing densities of the signal
process. The paper then demonstrates how an efficient inference scheme, based
on this variational approach to the approximation of the hidden states, can be
designed to estimate the unknown parameters of stochastic differential
equations. Two examples at the end illustrate the efficacy and the accuracy of
the presented method.Comment: 37 pages, 2 figures, revise
Controller evaluations of the descent advisor automation aid
An automation aid to assist air traffic controllers in efficiently spacing traffic and meeting arrival times at a fix has been developed at NASA Ames Research Center. The automation aid, referred to as the descent advisor (DA), is based on accurate models of aircraft performance and weather conditions. The DA generates suggested clearances, including both top-of-descent point and speed profile data, for one or more aircraft in order to achieve specific time or distance separation objectives. The DA algorithm is interfaced with a mouse-based, menu-driven controller display that allows the air traffic controller to interactively use its accurate predictive capability to resolve conflicts and issue advisories to arrival aircraft. This paper focuses on operational issues concerning the utilization of the DA, specifically, how the DA can be used for prediction, intrail spacing, and metering. In order to evaluate the DA, a real time simulation was conducted using both current and retired controller subjects. Controllers operated in teams of two, as they do in the present environment; issues of training and team interaction will be discussed. Evaluations by controllers indicated considerable enthusiasm for the DA aid, and provided specific recommendations for using the tool effectively
The Impact of ICT Usage, Workplace Organisation and Human Capital on the Provision of Apprenticeship Training: A firm-level analysis based on Swiss panel data: a firm-level analysis based on Swiss panel data
Firstly, we investigated the determinants of a) the propensity of Swiss firms to provide apprenticeship training, and b) the intensity of training (measured by the employment share of apprentices). We primarily were interested in the relevance as explanatory factors of the three constituent elements of the “new firm paradigm” that emerged in the course of the last twenty years: intensive usage of ICT; redesign of workplace organisation; shift from lower to higher skills. We found that the skill composition of the workforce (including further training), ICT intensity and, to a lesser extent, workplace organisation are important drivers of apprenticeship-based skill formation, with stronger effects on training propensity than on training intensity. Secondly, we analysed the relationship between apprenticeship training and firm performance. It turned out that productivity and apprenticeships (training propensity or intensity) are negatively correlated. The study is relevant for training policy in advanced economies where the new firm paradigm plays a large and growing role
Investigation of Ca2+-dependent transport and sorting processes of soluble secreted proteins in the Golgi apparatus
Didaktisch-methodische Perspektiven auf nationale Stereotype: Facetten einer unterrichtspraktischen Konkretisierung
In this article we address a central theme of how lessons in German and Danish that sensitise students for national clichés (stereotypes) can be designed. By introducing the training aids that support a language teaching about German and Danish clichés, we move concrete materials and results from teaching lessons in German and Danish schools as well as other educational institutions in the centre of our focus. Programmatically, a didactic-methodical model of sensitisation, reflexion and criticism is explained. Theoretical and terminological differentiations on the subject areas stereotype and stereotyping and to dimensions of stereotypes refer to the topical linguistic and social-psychological research discussion. Thoughts on the verisi-militude of national stereotypes from a didactic view decide the contribution
An adaptive discretization method solving semi-infinite optimization problems with quadratic rate of convergence
Semi-infinite programming can be used to model a large variety of complex
optimization problems. The simple description of such problems comes at a
price: semi-infinite problems are often harder to solve than finite nonlinear
problems. In this paper we combine a classical adaptive discretization method
developed by Blankenship and Falk and techniques regarding a semi-infinite
optimization problem as a bi-level optimization problem. We develop a new
adaptive discretization method which combines the advantages of both techniques
and exhibits a quadratic rate of convergence. We further show that a limit of
the iterates is a stationary point, if the iterates are stationary points of
the approximate problems
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