The Influence of PZT Actuators Positioning in Active Structural Acoustic Control

This paper deals with the effect of secondary actuator positioning in an active structural acoustics control (ASAC) experiment. The ASAC approach is based on minimizing the sound radiation from structures to the far field by controlling the structural vibrations. In this article a rectangular steel plate structure was assumed with one secondary actuator attached to it. As a secondary actuator, a specially designed piezoelectric stripe actuator was used. We studied the effect of the position of the actuator on the pattern and on the radiated sound field of the structural vibration, with and without active control. The total radiated power was also measured. The experimental data was confronted with the results obtained by a numerical solution of the mathematical model used. For the solution, the finite element method in the ANSYS software package was used.

The computer support of diagnostics of circle crystallizers

This paper is focused on computer aided technological processes of continuous steel casting devices. The paper characterized the fundamental aspects of creating computer aided control process of continuous steel casting operations. There is in detail described software system AMKO (Algorithm Modelling conicities). The importance of software AMKO consists in extending the usability of copper enclosure in the case of its weariness and the possibility of its further use. Using this software to create graphical model of the wear, which shows the conicity of the studied mold along all its lengths and specifies the possibility of its further use in various compositions sequences. Such modelling and prediction is possible with usage of cybernetic modelling principles and methods known as soft-computing

Microstructure and Microhardness of Fiber Laser Welded Dual-Phase Steels with High-Strength Low-Alloy Steels

The fiber laser welding of dual-phase DP980 steels with high-strength low-alloy LA340 steels was studied with a concentration on microstructure, microhardness, and tensile properties of butt joints.Рассматривается сварка волоконным лазером двухфазных сталей DP980 с высокопрочными низколегированными сталями LA340, при этом особое внимание уделяется микроструктуре, микротвердости и свойствам растяжения стыковых соединений

Formability of Tailor-Welded Blanks from Dual-Phase and Bake-Hardened Steels with a Planar Anisotropy Influence

The formability of two types of tailor-welded blanks was analyzed with the concentration on the effects of planar anisotropy on eras forming of deep-drawn parts. The first tailor-welded blank consisted of bake-hardened BH220 steel with different rolling directions, which is applied to the surface car body parts. The second one consisted of dual-phase DP600 steel with different rolling directions, which is applied to supporting parts of automobiles. Stress-strain characteristics of experimental steel sheets were measured using the tensile tests and used in the respective simulations. Simulations via the Dynaform software were compared to the experimental values measured during the deep-drawing process of rectangular boxes.Анализируются формообразующие свойства нестандартных сварных заготовок с акцентом на влияние плоскостной анизотропии на возникновение волнистости в деталях глубокой вытяжки. Одна нестандартная сварная заготовка выполнена из термозакаливаемой стали BH220 с разным направлением прокатки и применяемая в кузовных деталях автомобиля, другая из двухфазной стали DP600 также с разным направлением прокатки и применяемая в несущих элементах конструкции автомобиля. Деформационно-прочностные характеристики листов экспериментальной стали измеряли при испытаниях на растяжение и использовали при моделировании. Результаты моделирования с помощью программного комплекса Dynaform сравнивали с экспериментальными значениями, полученными при глубокой вытяжке прямоугольных коробчатых деталей

Fiber Laser Welding of Dual-Phase and Bake-Hardened Steels

Microstructural changes and microhardness profiles of laser-welded dual-phase DP600 and bakehardened 220BH steels were evaluated. The joints of these steels were butted with different welding parameters. They exhibited the microstructural changes, from ferrite and martensite in dual-phase steels or ferrite in bake-hardened steels to acicular ferrite, bainite and martensite in the fusion and heat-affected zones of the weld joints. As a result of welding, microhardness increases significantly in the fusion zones and even more in the heat-affected zones near DP600 steel

Kombinace kvalitativních metod při výzkumu tacitních znalostí manažerů

Tacitní znalosti jsou považovány za významnou součást profesních kompetencí, za skrytý potenciál subjektu, který se projevuje při řešení sociálních situací. Závažným problémem je, jak proces utváření tacitních znalostí v profesních, zejména sociálních situacích probíhá.Autoři informují o kombinaci kvalitativních metod při výzkumu tacitních znalostí manažerů. Využili při něm polostrukturovaný rozhovor, metodu dotazníkovou a metodu ohniskové skupiny. Referují o výsledcích první etapy výzkumu a poukazují na možnosti aplikace dalších metod: situační Wagnerův test (dotazník), projektivní techniky a metodu tzv. stimulovaného vybavování profesních situací zaznamenaných na videozáznamu

Deep-Drawing Process Simulation for Tailor-Welded Blanks with an Elastic Blankholder

Application of tailor welded blanks is proved to be very effective in the current trend of body parts construction. However, their formability is limited to the differences of mechanical properties of individual tailor welded blanks parts. These differences result in non-constant material flow and a deflection of the weld line. This article is focused on the elimination of uneven material flow and weld line instability. The results have been obtained by means of laboratory measurements on the drawing tool as well as material simulation computed by LS-DYNA code. According to acquired results, it can be claimed that the blankholder force values and force distribution have a significant influence on the deep-drawing process of tailor welded blanks. The weld line direction in consideration of the blankholder area size has influence on the deflection value. The simulation provided a reliable prediction of tailor-welded blank formability.Показана эффективность использования нестандартных сварных заготовок при проектировании кузовных деталей. Однако их пластичность ограничена из-за разных механических характеристик отдельных деталей из таких заготовок, что приводит к непостоянной текучести материала и перемещению границы сплавления. Проведены лабораторные измерения вытяжки и моделирование материала с использованием программного комплекса LS-DYNA. Показано, что усилие прижима и его распределение существенно влияют на процесс глубокой вытяжки нестандартных сварных заготовок. С учетом размера площади прижима влияние на величину перемещения границы сплавления оказывает ее направление. При прогнозировании пластичности нестандартных сварных заготовок результаты моделирования были весьма надежными

Lattice-Boltzmann Method for Geophysical Plastic Flows

We explore possible applications of the Lattice-Boltzmann Method for the simulation of geophysical flows. This fluid solver, while successful in other fields, is still rarely used for geotechnical applications. We show how the standard method can be modified to represent free-surface realization of mudflows, debris flows, and in general any plastic flow, through the implementation of a Bingham constitutive model. The chapter is completed by an example of a full-scale simulation of a plastic fluid flowing down an inclined channel and depositing on a flat surface. An application is given, where the fluid interacts with a vertical obstacle in the channel.Comment: in W. Wu, R.I. Borja (Edts.) Recent advances in modelling landslides and debris flow, Springer Series in Geomechanics and Geoengineering (2014), ISBN 978-3-319-11052-3, pp. 131-14

A constant magnetocaloric response in FeMoCuB amorphous alloys with different FeB ratios

The magnetocaloric effect of Fe91−xMo8Cu1Bx (x = 15 , 17 , 20) amorphous alloys has been studied. The temperature of the peak of magnetic entropy change can be tuned by altering the Fe / B ratio in pk pk the alloy, without changing its magnitude, ILlSM I. The average contribution of the Fe atoms to ILlSM I increases with increasing B content. This is correlated with the increase in the low temperature mean magnetic moment of Fe. A recently proposed master curve behavior for the magnetic entropy change is also followed by these alloys and is common for all of them

The energy gap of intermediate-valent SmB6 studied by point-contact spectroscopy

We have investigated the intermediate valence narrow-gap semiconductor SmB6 at low temperatures using both conventional spear-anvil type point contacts as well as mechanically controllable break junctions. The zero-bias conductance varied between less than 0.01 mikrosiemens and up to 1 mS. The position of the spectral anomalies, which are related to the different activation energies and band gaps of SmB6, did not depend on the the contact size. Two different regimes of charge transport could be distinguished: Contacts with large zero - bias conductance are in the diffusive Maxwell regime. They had spectra with only small non-linearities. Contacts with small zero - bias conductance are in the tunnelling regime. They had larger anomalies, but still indicating a finite 45 % residual quasiparticle density of states at the Fermi level at low temperatures of T = 0.1 K. The density of states derived from the tunelling spectra can be decomposed into two energy-dependent parts with Eg = 21 meV and Ed = 4.5 meV wide gaps, respectively.Comment: 9 pages incl. 13 figure