79 research outputs found
Особистісно-професійний імідж учителя початкової школи як інструмент суб'єкт-суб'єктної взаємодії
(uk) В статті проаналізовано здобутки педагогічного досвіду видатних педагогів минулого й результати сучасних наукових досліджень з метою пошуку ефективних засобів здійснення результативної педагогічної взаємодії в освітньому процесі. Розкрито сутність особистісно-професійного іміджу вчителя початкової школи.
Представлено наукові позиції дослідників педагогічного іміджу та проаналізовано їхні погляди на рольособистісно-професійного іміджу вчителя в процесі суб'єкт-суб'єктної взаємодії.(en) This paper analyzes the achievements of outstanding educators teaching experience of the past and the results of modern research to find effective means of implementing effective pedagogical interaction in the studying process. The meaning of personal and professional image of teacher of elementary school. Submitted by scientific researchers teaching positions and image analysis of their views on the role of student-teacher professional image in the process of subject-tosubject interaction
Predictor models for high-performance wheel loading
Autonomous wheel loading involves selecting actions that maximize the total
performance over many repetitions. The actions should be well adapted to the
current state of the pile and its future states. Selecting the best actions is
difficult since the pile states are consequences of previous actions and thus
are highly unknown. To aid the selection of actions, this paper investigates
data-driven models to predict the loaded mass, time, work, and resulting pile
state of a loading action given the initial pile state. Deep neural networks
were trained on data using over 10,000 simulations to an accuracy of 91-97,%
with the pile state represented either by a heightmap or by its slope and
curvature. The net outcome of sequential loading actions is predicted by
repeating the model inference at five milliseconds per loading. As errors
accumulate during the inferences, long-horizon predictions need to be combined
with a physics-based model.Comment: 22 pages, 19 figure
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Compact differential-fed planar filtering antennas
This paper proposes novel low-profile differential-fed planar antennas with embedded sharp frequency selectively. The antennas are compact and easy to integrate with differential devices without matching baluns. The antenna design is formulated as a topology optimization problem, where requirements on impedance bandwidth, directivity, and filtering are used as the design objectives. The optimized antennas operate over the frequency band 6.0-8.5 GHz. The antennas have reflection coefficients below -15 dB, cross-polarization levels below -42 dB, a maximum gain of 6.0 ± 0.5 dB, and a uniform directivity over more than 130° beamwidth angle in the frequency band of interest. In addition, the antennas exhibit sharp roll-off between the operational band and frequencies around the 5.8GHz WiFi band and the 10 GHz X-band. One antenna has been fabricated with a good match between simulation and measurement results. © 2019 by the authors. Licensee MDPI, Basel, Switzerland
A better compression driver? CutFEM 3D shape optimization taking viscothermal losses into account
The compression driver, the standard sound source for midrange acoustic
horns, contains a cylindrical compression chamber connected to the horn throat
through a system of channels known as a phase plug. The main challenge in the
design of the phase plug is to avoid resonance and interference phenomena. The
complexity of these phenomena makes it difficult to carry out this design task
manually, particularly when the phase-plug channels are radially oriented.
Therefore, we employ an algorithmic technique that combines numerical solutions
of the governing equations with a gradient-based optimization algorithm that
can deform the walls of the phase plug. A particular modeling challenge here is
that viscothermal losses cannot be ignored, due to narrow chambers and slits in
the device. Fortunately, a recently developed, accurate, but computationally
inexpensive boundary-layer model is applicable. We use this model, a level-set
geometry description, and the Cut Finite Element technique to avoid mesh
changes when the geometry is modified by the optimization algorithm. Moreover,
the shape calculus needed to compute derivatives for the optimization algorithm
is carried out in the fully discrete case. Applying these techniques, the
algorithm was able to successfully design the shape of a set of
radially-directed phase plugs so that the final frequency response surprisingly
closely matches the ideal response, derived by a lumped circuit model where
wave interference effects are not accounted for. This result may serve to
resuscitate the radial phase plug design, rarely used in today's commercial
compression drivers
Topology Optimization for Wave Propagation Problems
This thesis considers topology optimization methods for wave propagation problems. These methods make no a priori assumptions on topological properties such as the number of bodies involved in the design. The performed studies address problems from two different areas, acoustic wave propagation and microwave tomography. The final study discusses implementation aspects concerning the efficient solution of large scale material distribution problems. Acoustic horns may be viewed as impedance transformers between the feeding waveguide and the surrounding air. Modifying the shape of an acoustic horn changes the quality of the impedance match as well as the angular distribution of the radiated waves in the far field (the directivity). This thesis presents strategies to optimize acoustic devices with respect to efficiency and directivity simultaneously. The resulting devices exhibit desired far field properties and high efficiency throughout wide frequency ranges. In microwave tomography, microwaves illuminate an object, and measurements of the scattered electrical field are used to depict the object's conductive and dielectric properties. Microwave tomography has unique features for medical applications. However, the reconstruction problem is difficult due to strongly diffracting waves in combination with large dielectric contrasts. This thesis demonstrates a new method to perform the reconstruction using techniques originally developed for topology optimization of linearly elastic structures. Numerical experiments illustrate the method and produce good estimates of dielectric properties corresponding to biological objects. Material distribution problems are typically cast as large (for high resolutions) nonlinear programming problems over coefficients in partial differential equations. Here, the computational power of a modern graphics processing unit (GPU) efficiently solves a pixel based material distribution problem with over 4 million unknowns using a gradient based optimality criteria method
On the far-field properties of an acoustic horn
This report presents a derivation of an expression for time harmonic acoustic wave propagation in the far field for two and three space dimensions, and includes detailed descriptions of the numerical evaluation of the far-field pattern in some typical situations. The presentation covers all parts required for computing the far-field properties of acoustical devices, and the report is designed to function as a single reference for these computations.Design Optimizatio
On the far-field properties of an acoustic horn
This report presents a derivation of an expression for time harmonic acoustic wave propagation in the far field for two and three space dimensions, and includes detailed descriptions of the numerical evaluation of the far-field pattern in some typical situations. The presentation covers all parts required for computing the far-field properties of acoustical devices, and the report is designed to function as a single reference for these computations.Design Optimizatio
Topology Optimization for Wave Propagation Problems
This thesis considers topology optimization methods for wave propagation problems. These methods make no a priori assumptions on topological properties such as the number of bodies involved in the design. The performed studies address problems from two different areas, acoustic wave propagation and microwave tomography. The final study discusses implementation aspects concerning the efficient solution of large scale material distribution problems. Acoustic horns may be viewed as impedance transformers between the feeding waveguide and the surrounding air. Modifying the shape of an acoustic horn changes the quality of the impedance match as well as the angular distribution of the radiated waves in the far field (the directivity). This thesis presents strategies to optimize acoustic devices with respect to efficiency and directivity simultaneously. The resulting devices exhibit desired far field properties and high efficiency throughout wide frequency ranges. In microwave tomography, microwaves illuminate an object, and measurements of the scattered electrical field are used to depict the object's conductive and dielectric properties. Microwave tomography has unique features for medical applications. However, the reconstruction problem is difficult due to strongly diffracting waves in combination with large dielectric contrasts. This thesis demonstrates a new method to perform the reconstruction using techniques originally developed for topology optimization of linearly elastic structures. Numerical experiments illustrate the method and produce good estimates of dielectric properties corresponding to biological objects. Material distribution problems are typically cast as large (for high resolutions) nonlinear programming problems over coefficients in partial differential equations. Here, the computational power of a modern graphics processing unit (GPU) efficiently solves a pixel based material distribution problem with over 4 million unknowns using a gradient based optimality criteria method
Topology Optimization for Wave Propagation Problems
This thesis considers topology optimization methods for wave propagation problems. These methods make no a priori assumptions on topological properties such as the number of bodies involved in the design. The performed studies address problems from two different areas, acoustic wave propagation and microwave tomography. The final study discusses implementation aspects concerning the efficient solution of large scale material distribution problems. Acoustic horns may be viewed as impedance transformers between the feeding waveguide and the surrounding air. Modifying the shape of an acoustic horn changes the quality of the impedance match as well as the angular distribution of the radiated waves in the far field (the directivity). This thesis presents strategies to optimize acoustic devices with respect to efficiency and directivity simultaneously. The resulting devices exhibit desired far field properties and high efficiency throughout wide frequency ranges. In microwave tomography, microwaves illuminate an object, and measurements of the scattered electrical field are used to depict the object's conductive and dielectric properties. Microwave tomography has unique features for medical applications. However, the reconstruction problem is difficult due to strongly diffracting waves in combination with large dielectric contrasts. This thesis demonstrates a new method to perform the reconstruction using techniques originally developed for topology optimization of linearly elastic structures. Numerical experiments illustrate the method and produce good estimates of dielectric properties corresponding to biological objects. Material distribution problems are typically cast as large (for high resolutions) nonlinear programming problems over coefficients in partial differential equations. Here, the computational power of a modern graphics processing unit (GPU) efficiently solves a pixel based material distribution problem with over 4 million unknowns using a gradient based optimality criteria method
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