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31.
Head and eye movements were simultaneously recorded during locomotory and pecking behavior of 4 pigeons, which were trained to traverse a conditioning chamber, with a pecking key and a food dispenser at each end. Each trial involved key pecking, walking, and feeding. Head movements were registered with a skull-mounted miniature accelerometer, and eye movements were recorded with implanted electrooculogram (EOG) electrodes. An almost perfect temporal coordination between head and eye movements was observed during both walking and feeding bouts. During walking, head movements primarily provide retinal image stability, and eye movements support visual scanning. During feeding, head movements mainly subserve the grasping of food items, and eye movements maintain visual fixation on them. Because the eyes are reflexively closed during the middle phase of pecks, the head and eye movements are then under ballistic control. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
32.
33.
A three-phase model for mixed columnar-equiaxed solidification 总被引:1,自引:0,他引:1
A three-phase model for mixed columnar-equiaxed solidification is presented in this article. The three phases are the parent
melt as the primary phase, as well as the solidifying columnar dendrites and globular equiaxed grains as two different secondary
phases. With an Eulerian approach, the three phases are considered as spatially coupled and interpenetrating continua. The
conservation equations of mass, momentum, species, and enthalpy are solved for all three phases. An additional conservation
equation for the number density of the equiaxed grains is defined and solved. Nucleation of the equiaxed grains, diffusion-controlled
growth of both columnar and equiaxed phases, interphase exchanges, and interactions such as mass transfer during solidification,
drag force, solute partitioning at the liquid/solid interface, and release of latent heat are taken into account. Binary steel
ingots (Fe-0.34 wt pct C) with two-dimensional (2-D) axis symmetrical and three-dimensional (3-D) geometries as a benchmark
were simulated. It is demonstrated that the model can be used to simulate the mixed columnar-equiaxed solidification, including
melt convection and grain sedimentation, macrosegregation, columnar-to-equiaxed-transition (CET), and macrostructure distribution.
The model was evaluated by comparing it to classical analytical models based on limited one-dimensional (1-D) cases. Satisfactory
results were obtained. It is also shown that in order to apply this model for industrial castings, further improvements are
still necessary concerning some details. 相似文献
34.
35.
A new prediction method with an interior light sensor for the workplane illuminance in daylighting control systems is introduced. Based on radiosity theory, the spatial distributions of daylight and electric light in the space are discussed and the prediction method is developed. An experimental verification of the technique is performed in an outdoor test-room for a double-glazed window system with a motorized venetian blind integrated between the two glazings. Electric light and daylight predictions were performed in accordance with the proposed method. The results showed that the electric light workplane illuminance can be predicted with high accuracy (±5 lux error with a linear correlation) and that the daylight workplane illuminance can be predicted within ±20 lux (with a linear correlation) for any sky conditions (overcast, clear sky, or variable) with the window system controlled to prevent direct daylight transmission. This method is useful for integrated control of motorized daylighting devices and dimmable electric lights. 相似文献
36.
Andreas Karageorghis 《Journal of scientific computing》1991,6(1):21-26
The way boundary conditions are imposed when applying Chebyshev collocation methods to Poisson and biharmonic-type problems in rectangular domains is investigated. It is shown that careful selection of the number of collocation points leads to a linear system ofn linearly independent equations inn unknowns. 相似文献
37.
Zusammenfassung Dieser Artikel beschreibt einige Erfahrungen und typische Problemstellungen mit Textmining in der Medizin und gibt einen Einblick
in aktuelle und zukünftige Herausforderungen in Forschung & Entwicklung. Interessant ist n?mlich, dass auch im ,,Multimedia-Zeitalter“
die meiste Information immer noch als ,,Text“ vorliegt. Mithilfe von statistischen und linguistischen Verfahren wird mit sogenannter
,,Textmining-Software“ versucht, aus Freitexten Information ,,heraus zu schürfen“ (deshalb ,,Textmining“). Allerdings ist
es damit noch nicht genug. Der n?chste Schritt besteht darin, die Information sowohl nutzbar als auch brauchbar zu machen.
Die jeweiligen End-Benutzerinnen und End-Benutzer müssen in die Lage versetzt werden, auf der Basis der gewonnenen Information
deren Wissen zu erweitern. In unserem konkreten Fall sollen damit Entscheidungen im Rahmen ?rztlichen Handelns unterstützt
werden. Probleml?sungen in diesem Bereich erfordern eine holistische Sicht- und Herangehensweise. Daher wird es immer wichtiger,
Erkenntnisse aus Informatik und Psychologie zusammenflie?en zu lassen und auf systemischer Ebene technologisch umzusetzen. 相似文献
38.
The cellulose solvent dimethyl sulfoxide (DMSO)/tetrabutylammonium fluoride trihydrate (TBAF) was
successfully applied as reaction medium for the synthesis of allyl cellulose by conversion of the polymer
with allyl chloride in the presence of solid NaOH. Samples with degree of substitution from 0.50 to 2.98
were accessible by varying the molar ratio anhydroglucose unit:allyl chloride:NaOH and reaction time. DMSO/TBAF
was found to be an efficient reaction medium for the preparation of highly functionalized samples from spruce
sulfite pulp with degree of polymerization of about 500 even in a scale of 50 g. The allyl cellulose samples
were characterized by means of FTIR- and NMR spectroscopy. Size exclusion chromatography revealed negligible
polymer degradation during synthesis and purification of the samples. 相似文献
39.
Until recently, numerical simulations of discontinuities in highly super-Alfvénic plasmas have been severely limited by comparatively crude resolution and accuracy. Significant progress in the numerical simulation of such plasmas was achieved with the recently implemented Central Weighted Essentially Non-Oscillatory (CWENO) scheme. Combining this technique with that of adaptive mesh refinement (AMR), we have developed a third-order numerical scheme, which is able to efficiently capture strong gradients on spatial scales being small compared to the overall scale of the plasma system considered. Here, we first describe important algorithmic aspects of the scheme as well as the physics included in it. Second, we present the results of various performance tests. And, third, we illustrate its application to ‘real world problems’ using the example of the dynamics of a Sedov-type explosion. 相似文献
40.
Measuring techniques for characterizing gas/liquid reactors . The article considers measuring techniques for the characterization of the phases in gas/liquid reactors. These include the velocity profile and turbulence in the continuous phase as well as holdup, size, and velocity of the dispersed phase. Also, methods for the determination of the specific interfacial area and the volumetric mass transfer coefficients are discussed. Measuring methods have made enormous advances in recent years. In spite of this, there is a lack of reliable methods, especially for use during reactions without disturbing the state of the reactor. It is suspected that probe technique will gradually fall into disuse and more and more attention will be focussed on contractless methods. This calls for further development of ultrasonic methods and methods relying on emission of light. 相似文献