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Abstrakt

A review is given on a number of colloidal phenomena with special reference to their applicability to nanoparticles. Phenomena addressed include preparation, electric double layers and their characterization, electrokinetics, van der Waals and Lifshits forces, electric and steric particle interaction.

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Autorzy i Afiliacje

J. Lyklema

Abstrakt

Architectural structures’ nodal coordinates are significant to shape appearance; vertical overloading causes displacement of the joints resulting in shape distortion. This research aims to reshape the distorted shape of a double-layer spherical numerical model under vertical loadings; meanwhile, the stress in members is kept within the elastic range. Furthermore, an algorithm is designed using the fmincon function to implement as few possible actuators as possible to alter the length of the most active bars. Fmincon function relies on four optimization algorithms: trust-region reflective, active set, Sequential quadratic progra mming (SQP), and interior-point. The fmincon function is subjected to the adjustment technique to search for the minimum number of actuators and optimum actuation. The algorithm excludes inactive actuators in several iterations. In this research, the 21st iteration gave optimum results, using 802 actuators and a total actuation of 1493 mm.MATLAB analyzes the structure before and after adjustment and finds the optimum actuator set. In addition, the optimal actuation found in MATLAB is applied to the modeled structure in MATLAB and SAP2000 to verify MATLAB results.
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Autorzy i Afiliacje

Ahmed Manguri
1 2
ORCID: ORCID
Najmadeen Saeed
2 3
ORCID: ORCID
Aram Mahmood
4
ORCID: ORCID
Javad Katebi
4
ORCID: ORCID
Robert Jankowski
1
ORCID: ORCID

  1. Faculty of Civil and Environmental Engineering, Gdańsk University of Technology, 80-223 Gdańsk, Poland
  2. Civil Engineering Department, University of Raparin, Rania, Kurdistan Region, Iraq
  3. Civil Engineering Department, Tishk International University, Erbil, Kurdistan Region, Iraq
  4. Faculty of Civil Engineering, University of Tabriz, Tabriz, Iran

Abstrakt

Ceramic protective coats, for instance, on turbine blades, create a double-layer area with various thermophysical properties and they require metal temperature control. In this paper, it is implemented by formulating a Cauchy problem for the equation of thermal conductivity in the metal cylindrical area with a ceramic layer. Due to the ill posed problem, a regularization method was applied consisting in the notation of thermal balance for the ceramic layer. A spectral radius for the equation matrix was taken as the stability measure of the Cauchy problem. Numerical calculations were performed for a varied thickness of the ceramic layer, with consideration of the non-linear thermophysical properties of steel and a ceramic layer (zirconium dioxide). A polynomial was determined which approximates temperature distribution in time for the protective layer. The stability of solutions was compared for undisturbed and disturbed temperature values, and thermophysical parameters with various ceramic layer thickness. The obtained calculation results confirmed the effectiveness of the proposed regularization method in obtaining stable solutions at random data disturbance.
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Autorzy i Afiliacje

Michał Ciałkowski
1
Magda Joachimiak
1
Magdalena Mierzwiczak
1
Andrzej Frąckowiak
1
Aleksander Olejnik
2
Adam Kozakiewicz
2

  1. Poznan University of Technology, Institute of Thermal Engineering, Piotrowo 3a, 60-965, Poznan, Poland
  2. Military University of Technology, Sylwestra Kaliskiego 2, 00-908 Warszawa, Poland

Abstrakt

In this study, a SUS316L membrane having double layered pore structures was fabricated, and the pore characteristics were analyzed after coating with a spherical powder and a flake-shaped powder on a disk-shaped SUS316L support using a wet powder spraying process. The thickness of the coated layer was checked using an optical microscope, and air permeability was measured using a capillary flow porometer. When the coating amount was similar, the fine porous layer prepared using flake powder was thicker and showed higher porosity. In the case of a similar thickness, the case of using flake powder was half of the amount of spherical powder used. Therefore, it was confirmed that it is possible to manufacture a metal membrane having a high filter efficiency even with a small coating amount when using the flake powder.
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Autorzy i Afiliacje

Min-Jeong Lee
1 2
ORCID: ORCID
Hyeon-Ju Kim
1
ORCID: ORCID
Manho Park
3
ORCID: ORCID
Jung-Yeul Yun
1
ORCID: ORCID

  1. Korea Institute of Materials Science (KIMS), Metal Powder Department, Changwon 51508, Republic of Korea
  2. Pusan National University Department of Materials Science and Engineering, Republic of Korea
  3. R&D Center, ASFLOW Co. Ltd, Suwon, Republic of Korea

Abstrakt

The paper focuses on the static behavior of double-layered tensegrity grids. Due to the specific characteristics, like the self-stress states and infinitesimal mechanisms, tensegrities can be used as deployable structures. For such structures, the possibility of the control of the behavior is very important. The main purpose of the work is to prove that the control of tensegrity structures with mechanisms is possible. The stiffness of such structures is found to depend not only on the geometry and material properties, but also on the initial prestress level and external load. In the case, when mechanisms do not exist, structures are insensitive to the initial prestress. It is possible to control the occurrence of mechanisms by changing the support conditions of the structure. Grids built with modified Simplex modules are considered. Two-stage analysis is performed. Firstly, the presence of the characteristic tensegrity features is examined and then, on that basis, the structures are classified into one of two classes. Next, the influence of the level of initial prestress on the behavior of structures under static load is analyzed. To evaluate this behavior, a geometrically non-linear model is used.
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Autorzy i Afiliacje

Justyna Tomasik
1
ORCID: ORCID
Paulina Obara
1
ORCID: ORCID

  1. Kielce University of Technology, al. Tysiąclecia Państwa Polskiego 7, 25-314 Kielce, Poland

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