7,186 research outputs found
Meditation Awareness Training (MAT) for work-related wellbeing and job performance: a randomised controlled trial
Get PDFDue 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
Effects of reynolds number on flow separation above generic half span transport aircraft model
No full textThe purpose of this study is to investigate the flow separation on UTM half model at 3 different Reynolds number which is 0.5 x 106, 1.0 x 106 and 1.5 x 106 which corresponds to speed, V = 20 m/s, 45 m/s and 65 m/s using pressure distribution method and flow visualization. The study was done to observe the flow separation for three different Reynolds number. The pressure distribution at 50% wing span was measured and plotted to observe the flow characteristic at angle of attack from 0 deg to 24 deg at three different Reynolds number. The pressure distribution on the wing was reduced to local lift coefficient and this data was compared to lift coefficient obtained from the balance data to study when the model reaches stall
An automated visual tracking measurement for quantifying wing and body motion of free-flying houseflies
No full textPioneering discoveries revealed that flying insects actively regulate body appendages such as wings, legs and abdomen to stay aloft. However, the initial stage of capturing their motion during flight is rather challenging and time-consuming, especially during the digitization of lengthy video images. Therefore, our development of an automated visual tracking system will greatly provide a full access to insect's body and wing dynamics during flight. By using the positional dataset obtained from the digitized images which earlier captured by an automated time-resolved high-speed videography, we thus further three-dimensionally reconstructed body and wing dynamics of housefly Musca domestica. We validated and further compared the automated digitization with manual tracking. Our analysis estimates that motions along z-axis yields higher differences (16 ± 28.19 µm for thorax and 13 ± 99.19 µm for wingtip) because it orthogonally points to the cameras, which lead to acceptable inaccuracies of calibration coefficients due to the limited depth of focus
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
The analysis of flow on round-edged delta wings
Get PDFThe flow around three-dimensional aircraft wings, including delta-wings is very complicated. Much experimental and numerical work has been performed to discover its complexity. To date, all numerical calculations on delta wings have been carried out for either fully laminar or fully turbulent boundary layers. The transition status of the boundary layer is considered unknown despite several efforts to identify transition from laminar to turbulent flow. One such study, called the International Vortex Flow Experiment – 2 (VFE-2), has been carried out by an international group and mainly focuses on the boundary layers on delta wings. The data from the VFE-2 experimentals potentially provide the location of transition on the upper and lower surfaces of the wing to guide associated numerical studies. The effects of Reynolds number, Mach number, angle of attack and the leading edge bluntness are also investigated.
Almost all delta wing studies to date have involved tests on wings with sharp leading edges and these have led to the conclusion that the flows are relatively independent of Reynolds number. In fact, most real wings have finite leading edge radii. Hence, the flow separation is no longer fixed at the leading edge, thus making the flow dependent on Reynolds number. This particular aspect has been studied extensively by the VFE-2 team.
As part of the VFE-2 project, Glasgow University constructed a delta wing with four different sets of leading edges. Small-, medium- and large-radius edges and a pair of sharp leading edges were constructed in order to compare results from four delta wing configurations. In the current study experiments were carried out on these wings in the 2.65 metre by 2.04 metre, closed circuit, Argyll Wind tunnel of Glasgow University. The models were mounted on a specially designed sting support structure that allowed them to be pitched around a constant centre of rotation throughout the experiments. Tests were conducted at speeds of 20.63 m/s and 41.23 m/s representing Reynolds numbers of 1 x 106 & 2 x 106 respectively, based on the mean aerodynamic chords of the wings. The tests were conducted in three phases. In the first phase, steady and unsteady forces and moments on all wings were measured at an angle of attack that varied from α =100 to 250. The forces and moments were captured at two sampling rates; i.e., 100 Hz and 8000 Hz. The second test series captured flow visualization data on the four wings. In these experiments, a mixture of Ondina oil and paraffin was combined with Dayglo powder and applied to the surfaces of the delta wings. The images of the flow topology on the wings were recorded. The final series of experiments involved Particle Image Velocimetry measurements. A stereo-PIV arrangement was applied in this experiment and two CCD-Cameras were positioned outside the test section for image capture.
The current study has identified interesting features of the interrelationship between the conventional leading edge primary vortex and the occurrence and development of the inner vortex on the round-edged delta wings. The inner vortex was first identified and verified by the VFE-2 team. The effects of Reynolds number, angle of attack and leading-edge radii on both vortices are discussed in detail. The steady balance data have shown that the normal force coefficients are sensitive to leading edge bluntness at moderate angles of attack but are less so at high angles of attack. In relation to this, the flow visualization images have also shown that the primary vortex origin is located further aft on the wing at higher leading edge bluntness. This impacts on the strength of the inner vortex which remains a significant flow feature until the primary vortex approaches the apex. The lateral extent of the inner vortex is very dependent on the primary vortex at the leading edge; i.e. the weakening of the primary vortex has positive effects on the inner vortex. Particle Image Velocimetry shows that the increase in leading edge bluntness significantly decreases the swirl magnitude of the primary vortex.
The results obtained from the current investigation provide considerable insight into the effects of Reynolds number, angle of attack and bluntness on the flow structures experienced by delta wings, with rounded leading edges. This work will, therefore, inform and guide future investigations of delta wing flows and has the potential to impact on future wing design
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
Computational Fluid Dynamic Simulation (CFD) and Experimental Study on Wing-external Store Aerodynamic Interference
Get PDFThe main objective of the present work is to study the effect of an external store to a subsonic fighter aircraft. Generally most modern fighter aircraft is designed with an external store installation. In this project a subsonic fighter aircraft model has been manufactured using a computer numerical control machine for the purpose of studying the effect of the external store aerodynamic interference on the flow around the aircraft wing. A computational fluid dynamic (CFD) and wind tunnel testing experiments have been carried out to ensure the aerodynamic characteristic of the model then certified the aircraft will not facing any difficulties in stability and controllability. In the CFD experiment, commercial CFD code is used to simulate the interference and aerodynamic characteristics of the model. Subsequently, the model together with an external store was tested in a low speed wind tunnel with test section sized 0.45 m×0.45 m. Result in the two-dimensional pressure distribution obtained by both experiments are comparable. There is only 12% deviation in pressure distribution found in wind tunnel testing compared to the result predicted by the CFD. The result shows that the effect of the external storage is only significant at the lower surface of the wing and almost negligible at the upper surface of the wing. Aerodynamic interference is due to the external storage were mostly evidence on a lower surface of the wing and almost negligible on the upper surface at low angle of attack. In addition, the area of influence on the wing surface by store interference increased as the airspeed increase
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