Search results for "boundary"
showing 10 items of 1626 documents
Robotic assistance for industrial sanding with a smooth approach to the surface and boundary constraints
2021
[EN] Surface treatment operations, such as sanding, deburring, finishing, grinding, polishing, etc. are progressively becoming more automated using robotic systems. However, previous research in this field used a completely automatic operation of the robot system or considered a low degree of human-robot interaction. Therefore, to overcome this issue, this work develops a truly synergistic cooperation between the human operator and the robot system to get the best from both. In particular, in the application developed in this work the human operator provides flexibility, guiding the tool of the robot system to treat arbitrary regions of the workpiece surface; while the robot system provides…
Balancing Flexibility and Coherence: Information Exchange in a Paper Machinery Project
1999
The problem of balancing coherence and flexibility in collaborative information system design is approached here with two pairs of concepts. Boundary objects can support communication for perspective taking between communities of practice. Conscripting devices can support communication for perspective making within a community of practice. These theoretical lenses are used to study the uses of the technical specification in paper machine projects. Our study showed that as a boundary object it provided enough flexibility to allow negotiations, and sufficient local structure, for carrying out work in both communities of practice, the customer and the manufacturer. As a conscription device in …
Electromagnetic Scattering by a Strip Grating with Plane-Wave Three-Dimensional Oblique Incidence by Means of Decomposition into E-Type and H-Type Mo…
1993
A numerical algorithm to analyze the plane-wave three-dimensional oblique incidence on a strip grating is presented. Electromagnetic field is decomposed into vector Floquet harmonics of the E-type and H-type modes. To impose boundary conditions on the incident, reflected and transmitted waves, two integral equations of Fredholm of first kind are obtained. These equations are solved numerically with the standard Galerkin procedure, and the convergence of the algorithm is examined numerically. Since the superficial current near the edges of a conducting strip have been taken into account, the computational algorithm shows a fast convergence. Results are compared with other numerical results a…
From Random Walker to Vehicular Traffic: Motion on a Circle
2014
Driving of cars on a highway is a complex process which can be described by deterministic and stochastic forces. It leads to equations of motion with asymmetric interaction and dissipation as well as to new energy flow law already presented at previous TRAFFIC AND GRANULAR FLOW meetings. Here we consider a model, where motion of an asymmetric random walker on a ring with periodic boundary conditions takes place. It is related to driven systems with active particles, energy input and depot. This simple model can be further developed towards more complicated ones, describing vehicular or pedestrian traffic. Three particular cases are considered, starting with discrete coordinate and time, the…
Aircraft-based operation of an aerosol mass spectrometer: Measurements of tropospheric aerosol composition
2006
The Aerodyne quadrupole aerosol mass spectrometer was deployed on the Falcon twin jet research aircraft operated by Deutsches Zentrum für Luft- und Raumfahrt (DLR). This was the first deployment of an AMS in a jet aircraft. Aerosol mass concentration measurements in the troposphere up to altitudes of about 11 km were performed within two measurement flights on 12 and 14 May 2003 over southern Germany. Background aerosol data were gained up to 6 km, while aircraft exhaust aerosol was be sampled at higher altitudes on 14 May, indicating the presence of sulfuric acid and unburned hydrocarbons in the exhaust particles. The boundary layer aerosol on 12 May was found to be composed of 49% organic…
On the influence of the physico-chemical properties of aerosols on the life cycle of radiation fogs
1991
A one-dimensional model of radiation fog with detailed microphysics is presented. Aerosols and cloud droplets are treated in a joint two-dimensional size distribution. Radiative fluxes are calculated as functions of the radiative properties of the time-dependent particle spectra. The droplet growth equation is solved by considering radiative effects. Turbulence is treated by means of a higher order closure model. The interaction between the atmosphere and the earth's surface is explicitly simulated. Three numerical sensitivity studies are performed to investigate the impact of the different physico-chemical properties of urban, rural and maritime aerosols on fog formation. Numerical results…
Matched asymptotic solution for the solute boundary layer in a converging axisymmetric stagnation point flow
2007
Abstract A novel boundary-layer solution is obtained by the method of matched asymptotic expansions for the solute distribution at a solidification front represented by a disk of finite radius R 0 immersed in an axisymmetric converging stagnation point flow. The detailed analysis reveals a complex internal structure of the boundary layer consisting of eight subregions. The development of the boundary layer starts from the rim region where the concentration, according to the obtained similarity solution, varies with the radius r along the solidification front as ∼ln 1/3 ( R 0 / r ). At intermediate radii, where the corresponding concentration is found to vary as ∼ln( R 0 / r ), the boundary …
Efficient finite-difference scheme for solving some heat transfer problems with convection in multilayer media
2000
Abstract An efficient finite-difference method for solving the heat transfer equation with piecewise discontinuous coefficients in a multilayer domain is developed. The method may be considered as a generalization of the finite-volumes method for the layered systems. We apply this method with the aim to reduce the 3D or 2D problem to the corresponding series of 2D or 1D problems. In the case of constant piecewise coefficients, we obtain the exact discrete approximation of the steady-state 1D boundary-value problem.
Thermoconvective instabilities in an inclined porous channel heated from below
2011
Abstract The thermoconvective instability in an inclined rectangular channel filled with a fluid saturated porous medium and heated from below with a uniform flux is investigated. A stationary parallel buoyant flow with a linear temperature change in the transverse direction is considered. The linear stability to transverse and longitudinal roll disturbances of this basic state is examined. The thermoconvective instability onset of transverse rolls occurs when the Darcy–Rayleigh number exceeds a critical value, that increases with the inclination angle. The critical Darcy–Rayleigh number is discontinuous at the inclination angle 23.4749° above the horizontal. It is shown that, when the incl…
Phase boundary dynamics of bubble flow in a thick liquid metal layer under an applied magnetic field
2020
Dynamic neutron radiography is used to observe the effect of a transverse magnetic field on argon bubbles rising through a thick layer of liquid gallium without interactions with the container walls.