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71.
Klaus Timmel Sven Eckert Gunter Gerbeth 《Metallurgical and Materials Transactions B》2011,42(1):68-80
This article describes laboratory experiments aimed at investigations of flow structures and related transport processes in
the continuous-casting mold under the influence of an external direct current (DC) magnetic field. The main value of cold
metal laboratory experiments consists in the capabilities to obtain quantitative flow measurements with a reasonable spatial
and temporal resolution. The experimental results presented here were obtained using a physical model operating with the room-temperature
alloy GaInSn. According to the concept of the electromagnetic brake, the impact of a DC magnetic field on the outlet flow
from the submerged entry nozzle (SEN) has been studied up to Hartmann numbers of approximately 400. The effect of the magnetic
field on the flow structure turned out to be complex. The flow measurements do not manifest a general braking effect, which
would be expected as an overall damping of the flow velocity and the related fluctuations all over the mold volume. Variations
of the wall conductivity showed a striking impact on the resulting flow structures. The experiments provide a substantial
database for the validation of respective numerical simulations. 相似文献
72.
73.
We prove a general monotonicity result about Nash flows in directed networks, which generalizes earlier results and can be
used for the design of truthful mechanisms in the setting where each edge of the network is controlled by a different selfish agent, who incurs costs when her edge
is used. 相似文献
74.
Optimal design applications are often modeled by using categorical variables to express discrete design decisions, such as
material types. A disadvantage of using categorical variables is the lack of continuous relaxations, which precludes the use
of modern integer programming techniques. We show how to express categorical variables with standard integer modeling techniques,
and we illustrate this approach on a load-bearing thermal insulation system. The system consists of a number of insulators
of different materials and intercepts that minimize the heat flow from a hot surface to a cold surface. Our new model allows
us to employ black-box modeling languages and solvers and illustrates the interplay between integer and nonlinear modeling
techniques. We present numerical experience that illustrates the advantage of the standard integer model. 相似文献
75.
76.
77.
78.
Chest compression is a vital part of cardiopulmonary resuscitation (CPR). This paper demonstrates how the compression depth can be estimated using the principles of inertia navigation. The proposed method uses accelerometer sensors, one placed on the patient's chest, the other beside the patient. The acceleration-to-position conversion is performed using discrete-time digital signal processing (DSP). Instability problems due to integration are combated using a set of boundary conditions. The proposed algorithm is tested on a mannequin in harsh environments, where the patient is exposed to external forces as in a boat or car, as well as improper sensor/patient alignment. The overall performance is an estimation depth error of 4.3 mm in these environments, which is reduced to 1.6 mm in a regular, flat-floor controlled environment. 相似文献
79.
Bühling S Wyrowski F 《Journal of the Optical Society of America. A, Optics, image science, and vision》2002,19(12):2414-2423
Diffractive beam-splitting elements are typically designed for replicating beams on positions belonging to an equidistant grid in the spatial spectrum. The parameter of the output grid follows directly from the period of the beam-splitter transmission through the grating equation. Our objective is to develop design strategies allowing a more accurate positioning of the replicated beams. Issues occurring when the output grid parameter is decreased below the output beam width are discussed and shown to be avoidable. Furthermore, a design algorithm is introduced, which permits an arbitrary positioning of the replicated beams. This algorithm is constructed for high computational efficiency by utilizing fast Fourier transform operations in the major part of its iterations. 相似文献
80.
Problem analysis is an important, but mainly neglected part of the problem‐solving process. The theory of inventive problem solving (TRIZ) offers an instrument called function analysis to conduct problem analysis, which is especially useful for exploring a problem. This process is based on an idea applied in different creativity techniques, saying that behind one problem statement many problem formulations may occur, which allows for evaluation and selection of those problem formulations before looking for problem solutions. The application of function analysis as a tool for teams is recommended for a number of reasons. In so doing so, two main questions arise: (i) Should function analysis be used with the help of an external moderator? and: (ii) Should it be applied with currently available special software? After introducing the basics of function analysis this article provides key findings deducted from an experiment addressing these questions. An important result is the remarkable learning effect, which occurs while using function analysis in teams. By applying function analysis in R&D, companies will be able to get deeper and team‐based problem explorations, which may lead to maturing problem solutions. 相似文献