7,269 research outputs found
Meditation Awareness Training (MAT) for work-related wellbeing and job performance: a randomised controlled trial
No full textDue to its potential to concurrently improve work-related wellbeing (WRW) and job performance, occupational stakeholders are becoming increasingly interested in the applications of meditation. The present study conducted the first randomized controlled trial to assess the effects of meditation on outcomes relating to both WRW and job performance. Office-based middle-hierarchy managers (n = 152) received an eight-week meditation intervention (Meditation Awareness Training; MAT) or an active control intervention. MAT participants demonstrated significant and sustainable improvements (with strong effect sizes) over control-group participants in levels of work-related stress, job satisfaction, psychological distress, and employer-rated job performance. There are a number of novel implications: (i) meditation can effectuate a perceptual shift in how employees experience their work and psychological environment and may thus constitute a cost-effective WRW intervention, (ii) meditation-based (i.e., present-moment-focussed) working styles may be more effective than goal-based (i.e., future-orientated) working styles, and (iii) meditation may reduce the separation made by employees between their own interests and those of the organizations they work for
Voorlopige resultaten proeven Zinkcon mat
No full textResultaten proeven met de Zinkcon mat in de stroomgoot in Lith op ware grootte.KWP-collectio
Applying the method of fundamental solutions to harmonic problems with singular boundary conditions
No full textThe method of fundamental solutions (MFS) is known to produce highly accurate numerical results for elliptic boundary value problems (BVP) with smooth boundary conditions, posed in analytic domains. However, due to the analyticity of the shape
functions in its approximation basis, theMFS is usually disregarded when the boundary functions possess singularities. In this work we present a modification of the classical MFS which can be applied for the numerical solution of the Laplace BVP with Dirichlet boundary conditions exhibiting jump discontinuities. In particular, a set of harmonic functions with discontinuous boundary traces is added to the MFS basis. The accuracy of the proposed method is compared with the results form the classical MFS.The financial support from Center for Computational and Stochastic Mathematics (CEMAT–IST) through Fundac¸ ˜ao para a Ciˆencia e a Tecnologia (FCT) projects PEst-OE/MAT/UI0822/2014 and EXCL/MAT-NAN/0114/2012 is gratefully acknowledged
Fotoreportage Samenstellen van de mat voor de grote legproef II
No full textFoto’s van het maken van een proefmat (gaasmat verschillende lagen met filtermateriaal), het oprollen van de mat; bij de fabriek in Kats
Variational Rashba Effect in GaAlAs/GaAs Heterojunctions
No full textThe Rashba alpha parameter at the Fermi energy of 2DEGs in AlGaAs/GaAs heterojunctions is calculated with a new variational solution to the multi-band envelope-function effective Schroedinger equation based on the 8-band kp Kane model for the bulk. Modified Fang-Howard trial wave-functions that depend on spin and satisfy spin-dependent boundary conditions, are introduced; and the spin splitting is obtained by minimizing the total energy of the 2DEG. The results are compared with simpler model calculations and shown, in particular, to be quite sensitive to the barrier penetration of the first subband wave-function in these heterojunctions
Variational analysis of the Rashba splitting in III-V semiconductor inversion layers
No full textA spin-dependent variational theory is used to analyze the Rashba spin-orbit splitting in two-dimensional electron gases formed in III-V semiconductor inversion layers. The spin split conduction subbands in CdTe/InSb, insulator/InAs, InP/InGaAs, InAlAs/InGaAs, and AlGaAs/GaAs heterojunctions are calculated. The theory, presented here in detail, is based on the 8 x 8 k . p Kane model and on the introduction of simple and convenient spin-dependent Fang-Howard trial functions, and leads to analytical expressions for the split subbands, as well as allows for a detailed knowledge of the Rashba spin-orbit coupling, including its explicit dependence on structure parameters and its decomposition into separate contributions. The Rashba coupling parameter and the population difference in the spin-split subbands, as experimentally determined from the beating pattern of the Shubnikov-de Haas (SdH) oscillations, are obtained as a function of the electron density (n(s)). The separate contributions to the particularly large Rashba splitting in CdTe/InSb heterojunctions are also computed and discussed. It is shown, for example, that due to the spin-dependent boundary conditions, the direct Rashba spin-orbit coupling term in the effective Hamiltonian dominates the splitting only for n(s) > 10(10) cm(-2) while it is the barrier penetration kinetic energy term that gives the largest contribution to the Rashba effect at lower densities
Spin-orbit interaction strength and anisotropy in III-V semiconductor heterojunctions
No full textThe spin-orbit interaction strength for electrons in III-V semiconductor heterojunctions and the corresponding in-plane anisotropy are theoretically studied, considering Rashba and Dresselhaus contributions. Starting from a variational solution of Kane's effective Hamiltonian for the Rashba-split subbands, the total spin-orbit splitting at the Fermi level of the two-dimensional electron gas in III-V heterojunctions is calculated analytically, as a function of the electron density and wave-vector direction, by adding the Dresselhaus contribution within quasidegenerate first-order perturbation theory. Available GaAs and InGaAs experimental data are discussed. Effects of the barrier penetration are identified, and the spin-orbit anisotropy is shown to be determined by more than one parameter, even in the small-k limit, contrary to the commonly used alpha/beta (where alpha is the Rashba and beta the Dresselhaus interaction) single-parameter picture. DOI: 10.1103/PhysRevB.87.08130
Variational Rashba splitting in two-dimensional electron gases in III-V semiconductor heterojunctions
No full textControl of the Rashba spin-orbit coupling in semiconductor two-dimensional electron gases (2DEGs) is of fundamental interest to the rapidly evolving semiconductor spintronics and depends on the detailed knowledge of the controversial interface and barrier penetration effects. Based on the 8x8 k center dot p Kane model for the bulk, we propose a spin-dependent variational solution for the conduction subbands of III-V heterojuctions, which reveals analytically the different contributions to the Rashba splitting and its dependency on heterostructure and band parameters as the band offset and effective masses. Perturbation expansions are used to derive renormalized parameters for an effective, simple, and yet accurate one band model. Spin-dependent modified Fang-Howard trial functions, which satisfy the spin-dependent boundary conditions, are then introduced. The subband splitting is given as a function of the variational parameter which is obtained minimizing the total energy of the 2DEG. Our calculations applied to InAlAs/InGaAs heterojunctions, where a near 20% increase in the splitting is observed due to the barrier penetration, are in good agreement with both experiment and exact numerical calculations. Well-known expressions in the limit of a perfect insulating barrier are exactly reproduced
The proposed goodyear modular mat type scrap tire floating breakwater
No full textScrap tires are proposed as a construction material for building large floating mat type breakwater devices. The Goodyear scrap tire floating breakwater assemblies are formed by securing together modular bundles of tightly interlocked scrap tires with high strength rope/cable, or special corrosion resistant steel rods. This construction procedure yields an easily installed, readily adaptable breakwater structure which has high energy absorbing capacity for normal loading conditions but which deforms and yields when subjected to overloads. The proposed designs rely on a modular bundle concept where a relatively few tires are secured together to form a small easily assemble de portable building unit which,serves as a basic building block from which giant breakwater devices can be constructed. Flotation is provided by placing a small amount of buoyant material in the crown of each tire or by filling approximately 10%) of the tires with buoyant foam. The design possibilities using scrap tire building modules are virtually limiless. Tires may be laced together to form large flat single or multiple thickness shallow mats. They may be stacked vertically in single or multiple thickness bundles like bricks in a wall to form curtain type barriers. Variutions in breakwater draft are made possible by adding modules above or below to vary the thickness and by combining constructions such as hanging a curtain on a mat structure. Also, mats with varying buoyancy may be moored on an incline for more efficient energy absorption
Application of MAT device to characterize the adhesive bonding strength of membrane in orthotropic steel deck bridges
No full textIn order to characterize adequately the adhesive bonding strength of the various membranes with surrounding materials on orthotropic steel decks and collect the necessary parameters for FE modeling, details of the Membrane Adhesion Test (MAT) have been introduced. Analytical constitutive relations of MAT device have been derived on the basis of Williams (1997). Furthermore, on the basis of experimental data obtained from MAT, ranking of the bonding characteristics of various membrane products is demonstrated as well as the role of other influencing factors, such as the types of substrate and test temperatures.Structural EngineeringCivil Engineering and Geoscience
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