Search results for "train"
showing 10 items of 4562 documents
Guaranteed tuning of PID controllers for parametric uncertain systems
2004
This paper presents a methodology for tuning the controller of a parametric uncertain plant in order to guarantee the satisfaction of specifications. These specifications are defined by means of an interval reference model that represents the set of satisfactory time or frequency behaviors. The controller synthesis is then formulated as a set-inclusion problem in the frequency domain. Interval techniques for the solution of constraint satisfaction problems are applied to design fixed-structure controllers in a guaranteed manner. In particular, PID controllers are considered since they are widely used in industry.
The impact of overshooting deep convection on local transport and mixing in the tropical upper troposphere/lower stratosphere (UTLS)
2015
Abstract. In this study we examine the simulated downward transport and mixing of stratospheric air into the upper tropical troposphere as observed on a research flight during the SCOUT-O3 campaign in connection to a deep convective system. We use the Advanced Research Weather and Research Forecasting (WRF-ARW) model with a horizontal resolution of 333 m to examine this downward transport. The simulation reproduces the deep convective system, its timing and overshooting altitudes reasonably well compared to radar and aircraft observations. Passive tracers initialised at pre-storm times indicate the downward transport of air from the stratosphere to the upper troposphere as well as upward tr…
Uncertainties in future climate predictions due to convection parameterisations
2013
Abstract. In the last decades several convection parameterisations have been developed to consider the impact of small-scale unresolved processes in Earth System Models associated with convective clouds. Global model simulations, which have been performed under current climate conditions with different convection schemes, significantly differ among each other in the simulated transport of trace gases and precipitation patterns due to the parameterisation assumptions and formulations, e.g. the computation of convective rainfall rates, calculation of entrainment and detrainment rates etc. Here we address sensitivity studies comparing four different convection schemes under alternative climate…
Nonsmooth Mechanics. Convex and Nonconvex Problems
1999
Nonlinear, multivalued and possibly nonmonotone relations arise in several areas of mechanics. A multivalued or complete relation is a relation with complete vertical branches. Boundary laws of this kind connect boundary (or interface) quantities. A contact relation or a locking mechanism between boundary displacements and boundary tractions in elasticity is a representative example. Material constitutive relations with complete branches connect stress and strain tensors, or, in simplified theories, equivalent stress and strain quantities. A locking material or a perfectly plastic one is represented by such a relation. The question of nonmonotonicity is more complicated. One aspect concerns…
Graph cut-based method for segmenting the left ventricle from MRI or echocardiographic images
2017
International audience; In this paper, we present a fast and interactive graph cut method for 3D segmentation of the endocardial wall of the left ventricle (LV) adapted to work on two of the most widely used modalities: magnetic resonance imaging (MRI) and echocardiography. Our method accounts for the fundamentally different nature of both modalities: 3D echocardiographic images have a low contrast, a poor signal-to-noise ratio and frequent signal drop, while MR images are more detailed but also cluttered and contain highly anisotropic voxels. The main characteristic of our method is to work in a 3D Bezier coordinate system instead of the original Euclidean space. This comes with several ad…
Development engineers’ work and learning as shared practice
2008
The field of workplace learning lacks empirical studies that view workplace practices as places for learning and see these practices in a critical light. Accordingly, the aim of this study is, first, to describe examples of everyday shared practice and consider what kinds of various conflicting aims and demands exist in it. Second, the purpose is to explore what and how it is possible to learn through these shared practices in the area of design and development work. The empirical material consists of ethnographic observations made in two organizations in Finland. Three thematic lines were extracted from field notes and transcribed work talk on the basis of ethnographic and adapted membersh…
Timing in methods for studying psychosocial factors at work
2014
In the present chapter we focus on time lags in panel studies investigating psychosocial factors and stressor-strain relationships. First, a framework of theoretical reasons for choosing specific time lags is provided, which is based on the work by Frese and Zapf (Methodological issues in the study of work stress: objective vs. subjective measurement of work stress and the question of longitudinal studies. In: Cooper CL, Payne R (eds) Causes, coping and consequences of stress at work. Wiley, Chichester, pp 375–411, 1988). Although this theoretical framework provides a clear rationale for time intervals, researchers are frequently mistaken using it to derive appropriate time lags. Second, an…
The effect of simulation exercises on the control of aggressive behaviour in children
1974
.— The subjects consisted of two. matched, extremely aggressive (experimental = ExG and control = CoG) groups of twelve 8–year-old boys. and of one criterion group (CrG) of extrovert, well-controlled boys. Video-tape recording of behaviour was used both in pretest (T1) and post-test (T2). Between T1 and T2 the ExG was submitted to simulation exercises of 8 lessons given in a period of four weeks. The exercises consisted in social problem solutions on the purely cognitive (imaginary and symbolic) level and in role-playing (behavioral level). The hypothesis was that the combination of cognitive training and observational learning with the aim of making children realise alternatives to aggress…
Why Is My Job So Stressful? Characteristics, Processes and Models of Stress at Work
2017
This chapter deals with the issue of job stress in relation to employee health, well‐being and performance. The chapter starts with an outline of job stress as a societal problem, illustrating current trends in society, the nature of work, and job stress. It continues with a discussion of the main perspectives on job stress, including bad and good stress, and of the potential role of individual differences in the job stress process. Next, an integrative process model of job stress is presented that will pave the way for a profound discussion of four prominent theoretical models on job stress: (1) the Demand‐Control‐Support Model, (2) the Effort‐Reward Imbalance Model, (3) the Job‐Demands Re…
Physical activity and health: Musculoskeletal issues
2007
Sarcopenia and osteoporosis, the complications of the age-related deterioration of the musculoskeletal system, result in increased risk of fracture, disability and death in old age. Consequently, the structure and function of skeletal muscle and bone and their adaptability are essential aspects of overall health, functional capacity and mobility during the whole lifespan. There is convincing clinical evidence that progressive resistance exercise training improves the properties of skeletal muscle in men and women across the age spectrum, thus providing a high reserve capacity for coping with the functional demands of physical tasks. Regarding bones, exercise is most effective during growth,…