Wyniki wyszukiwania - BazTech

1

Homogenization of foil windings with globally supported polynomial shape functions

Bundschuh Jonas, Späck-Leigsnering Yvonne, De Gersem Herbert

Archives of Electrical Engineering

|

2024

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Vol. 73, nr 1

77--85

EN

In conventional finite element simulations, foil windings with thin foils and with a large number of turns require many mesh elements. This renders models quickly computationally infeasible. This paper uses a homogenized foil winding model and approximates the voltage distribution in the foil winding domain by globally supported polynomials. This way, the small-scale structure in the foil winding domain does not have to be resolved by the finite element mesh. The method is validated successfully for a stand-alone foil winding example and for a pot inductor example. Moreover, a transformer equipped with a foil winding at its primary side is simulated using a field-circuit coupled model.

2

Novel rheological modelling of thermosets and unidirectional monotropic fibre-reinforced thermoset matrix composites

Klasztorny Marian, Nycz Daniel B.

Composites Theory and Practice

|

2023

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R. 23, nr 1

3--21

EN

A refined, fully analytical rheological modelling of thermosetting polymers and unidirectional monotropic fibre-reinforced thermoset matrix (UFRT) composites is presented. New polymers and composites under normal conditions, fully relaxed from curing and post-curing stresses, are modelled. The theory includes quasi-static short-term/medium-term/long-term reversible rheological processes. Thermosets are isotropic materials exhibiting linearly viscoelastic shear strains and linearly elastic bulk strains. Fibres are monotropic (transversely isotropic) and linearly elastic materials. A generic function well reproducing the viscoelastic characteristics of thermosets and UFRT composites is a Mittag-Leffler fractional exponential function in an integral form. Coupled/uncoupled standard/inverse constitutive equations of linear rheology are formulated for thermosets and UFRT composites. The equations are mutually analytically transformable. New rheological models (coded H-R/H) for thermosets and UFRT composites are described by the smallest possible number of material constants. The thermoset is described by two independent elastic constants and three independent viscoelastic constants. The homogenized UFRT composite is described by five independent elastic constants and four independent viscoelastic constants, whereby two visco-elastic constants are common to the matrix and the composite. An improved homogenization theory of UFRT composites, based on analytical solutions of the selected tasks of the theory of linear elasticity, is formulated for monotropic fibres and positively validated experimentally. The viscoelastic constants of the thermoset are calculated analytically in an iterative loop using a long-term unidirectional tension creep experimental test. The viscoelastic constants of the UFRT composite are calculated analytically employing H-R/H shear/quasi-shear storage compliances and VECP (the viscoelastic-elastic correspondence principle) shear/quasi-shear storage compliances. The H-R/H rheological model was validated numerically for selected UFRT composites. The validation tests were performed on the enhanced reliability UFRT composites reported by Soden, Hinton, and Kaddour (Composites Science and Technology, 1998, 2002).

3

Zastosowanie wolnoobrotowego systemu mieszania w sekwencyjnych bioreaktorach porcjowych z osadem czynnym

Zaburko Jacek, Szulżyk-Cieplak Joanna, Widomski Marcin K., Łagód Grzegorz

Gaz, Woda i Technika Sanitarna

|

2022

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Nr 6

36--39

PL

Zaostrzające się wymogi, dotyczące jakości ścieków odprowadzanych do odbiornika, doprowadziły do opracowania wielu urządzeń wykorzystywanych podczas biologicznego oczyszczania. Obecne badania prowadzone w sektorze wodno-ściekowym skupiają się często na poszukiwaniu efektywnych energetycznie rozwiązań technicznych i technologicznych, wywierających jak najmniej negatywny wpływ na środowisko „przy jednoczesnym obniżeniu kosztów eksploatacyjnych. W systemach oczyszczania powszechnie wykorzystuje się właściwości struktur mikroorganizmów w postaci kłaczków osadu czynnego, które usuwają organiczne i biogenne związki zawarte w ściekach. Ważnym elementem powyższego rozwiązania jest zastosowanie układu mieszania i napowietrzania bioreaktorów w odpowiedniej konfiguracji. W oczyszczalni ścieków, z częścią biologiczną, działającej w technologii SBR, stosuje się wiele rodzajów urządzeń do mieszania. W niniejszym artykule przedstawiono zastosowanie innowacyjnego wolnoobrotowego systemu mieszania w sekwencyjnych bioreaktorach porcjowych, w których czynnikiem procesowym jest osad czynny.

EN

Increasing demands on the quality of wastewater discharged to the receiving water have led to the development of many biological treatment devices. Current research in the water and wastewater sector often focuses on finding energy-efficient solutions that have the least negative impact on the environment while reducing operating costs. In wastewater treatment systems, it is common to utilize the properties of microbial structures in the form of activated sludge flocs that remove organic compounds and biogenic contained in wastewater. An important part of the solution is the mixing and aeration system configuration used. In the treatment plant operating in the SBR technology, there are many types of mixing devices that are used in the process of wastewater treatment. This paper presents the application of an innovative slow-speed mixing system in sequential batch bioreactors in which activated sludge is a process factor.

4

Effect of cold rolling on microstructure and hardness of annealed Al-Cu-Mg alloy

Liu Fei, Liu Zhiyi, He Guangyu

Archives of Civil and Mechanical Engineering

|

2022

|

Vol. 22, no. 2

art. no. e64, 1--17

EN

The dislocation slips during the hot- and cold-rolling processes, the texture evolution and the Goss-oriented grain refinement during the annealing of the Al-Cu-Mg alloy were investigated using optical microscope (OM), scanning electron microscope (SEM), electron back-scatter diffraction (EBSD), transmission electron microscope (TEM) and X-ray diffraction (XRD). Results shown that {111} <110> octahedral slip systems and {110} <111> non-octahedral slip systems can be activated during the hot- and cold-rolling. When the dislocation slips in {111} planes are suppressed, the cross-slip from the {111} planes to the {110} planes can be activated to coordinate deformation. The strain gradients between the adjacent grains of the alloy with the large cold rolling reduction during annealing are dramatically decreased by the strain homogenization, which suppresses the growth of {110} < 001 > Goss-oriented grains. The activation of {110} <111> slip systems may be led to the decrease of the intensity of {112} <111> Copper texture, and the effect of {110} <111> slip systems on the evolution of {001} < 100 > Cube texture is very small. With the increase of the cold rolling reduction and annealing temperature, the hardness of the annealed and rolled Al-Cu-Mg alloy all increases, strain hardening and grain refinement are responsible for the enhanced hardness.

5

Numerical modelling of modular high-temperature gas-cooled reactors with thorium fuel

Oettingen Mikołaj, Cetnar Jerzy

Nukleonika

|

2021

|

Vol. 66, No. 4

133--138

EN

The volumetric homogenization method for the simplified modelling of modular high-temperature gas-cooled reactor core with thorium-uranium fuel is presented in the paper. The method significantly reduces the complexity of the 3D numerical model. Hence, the computation time associated with the time-consuming Monte Carlo modelling of neutron transport is considerably reduced. Example results comprise the time evolutions of the effective neutron multiplication factor and fissionable isotopes (233U, 235U, 239Pu, 241Pu) for a few configurations of the initial reactor core.

6

An introduction of the planetary roller extruder technology on the example of the wood-plastic composites production

Sąsiedzki Tad

Modelowanie Inżynierskie

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2021

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T. 42, nr 73

42--47

EN

Planetary roller extruder with his excellent mass temperature control, homogenization and dispersion is used not only in the plastics industry, but in a wide range of physical processes like continuous mixing, reactive chemical processes as polymerization and decomposition, for example in the process of recycling. ENTEX developed in last few years new improved technical solutions for example for better degassing, higher torque transmission, laboratory applications and direct extrusion. With these new solutions we create significant cost savings due to reduction of energy consumption and reduction of production costs by simplifying production process. We can also improve final product quality by reducing the thermal and mechanical load on the material on the example of WPC composite (Wood-Plastic-Composites).

PL

Rynek kompozytów WPC stale rośnie i otwiera potencjał dla nowych producentów i nowych technologii. Również firma ENTEX Rust & Mitschke GmbH podjęła wyzwanie i oferuje swoją technologię mieszalnika planetarnego do wyżej wymienionych zastosowań. Ze względu na dużą powierzchnię styku, wysoce wydajne i precyzyjne możliwości ogrzewania lub chłodzenia przetwarzanego materiału oraz modułową budowę wytłaczarka planetarna jest w stanie uzyskać do 78% wypełnienia wiórkami drzewnymi w polimerze przy zachowaniu najwyższej jakości produktu końcowego.

7

Numerical modelling of gabion retaining wall under loading and unloading

Grodecki Michał

Archives of Civil Engineering

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2021

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Vol. 67, nr 2

155--164

EN

Main goal of this paper is to present results of the numerical simulations of a real-scale gabion retaining wall tests. 4.5 m high wall was loaded and unloaded with water pressure, displacements of the crest of the wall were measured. Finite Element Method was used to simulate experiment and obtained results are compared with experimental ones. Usage of homogenized Coulomb-Mohr type continuum for gabions is proposed. Strength parameters of the model (cohesion and friction angle) are estimated on the base of large scale triaxial tests of the gabions and static tensile tests of the mesh. Influence of the “cut-off” condition on obtained results is analyzed. Elastic model for gabions is used for comparison of the results. Interface elements and truss joints between the gabions are used to simulate joints between gabions with limited strength. Good correlation between displacements obtained in experiment and numerical simulations was observed, especially in loading phase, so presented methodology of numerical modelling allows to model gabion retaining walls behavior close to the reality and could be used in engineering practice.

PL

Artykuł przedstawia wyniki symulacji numerycznych testów rzeczywistego muru oporowego z gabionów. Mur o wysokości 4.5 m był obciążany ciśnieniem wody i odciążany, mierzono przemieszczenia jego korony. Metoda Elementów Skończonych została wykorzystana do zasymulowania badań laboratoryjnych, porównano uzyskane wyniki z otrzymanymi doświadczalnie. Zaproponowano wykorzystanie zhomogenizowanego ośrodka typu Coulomba - Mohra do modelowania gabionów. Parametry wytrzymałościowe (kohezję i kąt tarcia wewnętrznego) oszacowano na bazie testów trójosiowych gabionów i testów statycznego rozciągania siatki. Analizowano wpływ warunku „cut-off” (braku nośności na rozciągania) na uzyskiwane wyniki. Dla porównania wykorzystano model sprężysty gabionów. Elementy kontaktowe i łączniki kratownicowe wykorzystano do zamodelowania połączeń pomiędzy gabionami o ograniczonej wytrzymałości. Zaobserwowano dobrą zgodność obliczonych numerycznie i pomierzonych laboratoryjnie przemieszczeń (szczególnie w fazie obciążenia), tak więc zaprezentowana metodologia pozwala na bliskie rzeczywistości zamodelowanie zachowania się konstrukcji z gabionów i może być wykorzystywana w praktyce inżynierskiej.

8

Synergistic effects of alloying, homogenization, and hot extrusion on the mechanical properties of as-cast Mg–Al–Ca magnesium alloys

Nasiri Zahra, Mirzadeh Hamed, Khorrami Mahmoud Sarkari, Emamy Massoud

Archives of Civil and Mechanical Engineering

|

2021

|

Vol. 21, no. 3

691--698

EN

Synergistic effects of partial replacement of Al with Ca, homogenization heat treatment, and hot extrusion on the microstructure and mechanical properties of Mg–(7-x)Al–xCa magnesium alloys were studied. The Mg17Al12 compound in Mg–7Al alloy, Mg17Al12 and Al2Ca compounds in AX52 alloy, Al2Ca and Mg–Al–Ca compounds in AX43 alloy, and Mg–Al–Ca compound in AX25 were characterized. The as-cast alloys were quite brittle with low strength values due to the deleterious effects of the continuous intergranular brittle constituents that completely masked the alloying effect. Homogenization resulted in the spheroidization of the eutectic constituents and gave the alloys some tensile ductility, which was remarkable for the AX43 alloy due to its fine grain size. Hot extrusion resulted in the fragmentation and dispersion of particles as well as formation of equiaxed, fine microstructures by the recrystallization processes, which led to the profound enhancements of the tensile properties in terms of both strength and elongation to failure. The product of strength and ductility of ~ 5500 MPa.% for the extruded AX43 alloy was far better than the value of ~ 314 MPa.% for the as-cast counterpart.

9

Nonlinear homogenization of heterogeneous periodic plates of Reissner-Mindlin type

Pruchnicki Erick

Journal of Theoretical and Applied Mechanics

|

2020

|

Vol. 58 nr 2

317--323

EN

In this paper, we propose a multiscale finite-strain plate theory for a composite nonlinear plate described by a repetitive periodic heterogeneity. We consider two scales, the macroscopic scale is linked to the entire plate and the microscopic scale is linked to the size of the heterogeneity. At the macroscopic scale, we approximate the displacement field by the Reissner-Mindlin model. By considering the equivalence between variations of the macroscopic elastic energy at each point of the mid surface and the microscopic one, we deduce that the macroscopic stress resultants can be expressed in terms of the microscopic stress.

10

Influence of RVE geometrical parameters on elastic response of woven flax-epoxy composite materials

Ryzińska Grażyna, Janowski Grzegorz

Composites Theory and Practice

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2020

|

R. 20, nr 2

51--59

EN

In the case of polymer composites reinforced with natural fiber woven fabrics, microstructural calculations are extremely difficult to perform due to their characteristic variability, among others their mechanical properties. The aforementioned scientific problem has not been thoroughly investigated, hence the purpose of this work was to assess the possibilities of predicting the properties of a composite reinforced with flax woven fabric by micromechanical calculations using the Mori-Tanaka and the double inclusion homogenization models. In addition, the second important utilitarian problem that was undertaken in the work was assessment of the impact of the size of the representative volume element (RVE) on the obtained results. The analyses were carried out for composites based on epoxy resin reinforced with flax fabrics: plain, 2x2 twill and 3x1 twill types. Based on the performed calculations, it was found that the obtained results depend on the type of weave in the fabric used, the size of the RVE, the number of yarn bands in the RVE and the appropriately selected homogenization method. Guidelines useful for evaluating the optimal RVE size depending on the type of weave were formulated.

PL

W przypadku kompozytów polimerowych zbrojonych tkaninami z włókien naturalnych przeprowadzanie obliczeń mikrostrukturalnych jest wyjątkowo trudne do wykonania z uwagi na charakterystyczną dla nich zmienność, m.in. właściwości mechanicznych. Wspomniany problem naukowy nie jest dokładnie zbadany, stąd celem niniejszej pracy była ocena możliwości prognozowania właściwości kompozytu wzmacnianego tkaniną lnianą poprzez obliczenia mikromechaniczne z wykorzystaniem modelu homogenizacji Mori-Tanaka oraz Double Inclusion. Ponadto drugim istotnym problemem utylitarnym, który podjęto w pracy, była ocena wpływu wielkości reprezentatywnego elementu objętościowego (REO) na uzyskane wyniki. Analizy przeprowadzono dla kompozytów o osnowie żywicy epoksydowej zbrojnej tkaninami lnianymi o splocie: płóciennym, skośnym 2x2 oraz skośnym 3x1. Na podstawie przeprowadzonych obliczeń stwierdzono, że uzyskane wyniki zależą od rodzaju splotu w zastosowanej tkaninie, wielkości REO, ilości pasm przędzy w REO oraz odpowiednio dobranej metody homogenizacji. Sformułowano wskazówki przydatne do oceny optymalnego wymiaru REO w zależności od rodzaju splotu.

11

Numerical Investigation of the Influence of Pulsed Laser Deposited Tin Thin Film Morphology on Deformation Inhomogeneities

Perzyński K., Zych D., Sitko M., Madej Ł.

Archives of Metallurgy and Materials

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2020

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Vol. 65, iss. 2

713--720

EN

In vestigation of influence of TiN thin film morphology on deformation inhomogeneities is an overall subject of the research. Numerical modelling approach that was selected for the study is based on the digital material representation concept, which gives an opportunity to directly replicate columnar microstructure morphology of an investigated thin film. Particular attention in this paper is put on the discussion of the influence of cellular automata neighbourhood on thin-film digital morphologies and their further deformation behaviour. Additionally, an evaluation of representativeness aspects of the digital models, in particular, the analysis of the influence of a number of columns, their dimensions and variations in their properties on the material behaviour during compression tests is also presented. The non-periodic boundary conditions are assumed during the investigation. Obtained data in the form of equivalent stress distributions as well as homogenized stress-strain curves from analyzed case studies are presented and discussed within the paper.

12

Microstructure and Mechanical Properties of Hot-deformed AlMg4 Alloys with the Variations of Mn, Fe, and Si Contents

Lee Da B., Kim Bong H., Choi Kweon H., Yang Seung Y., Kim Nam S., Ha Seong H., Yoon Young O., Lim Hyun K., Kim Shae, Hyun Soong K..

Archives of Metallurgy and Materials

|

2020

|

Vol. 65, iss. 4

1255--1259

EN

This paper aims to investigate the microstructural evolution and mechanical properties of hot-deformed AlMg4 alloys with Mn, Fe, and Si as the main impurities. For this purpose, solidification behavior and microstructural evolution during hot-rolling and heat-treatment processes are investigated by using theoretical calculations and experimental characterization. The crystallization and morphological transformation of intermetallic Al3 Fe, Al6 Mn, and Mg2 Si phases are revealed and discussed in terms of the variation in chemical composition. Following a homogenization heat-treatment, the effect of heat treatment on the intermetallic compounds is also investigated after hot-rolling. It was revealed that the Mg2 Si phase can be broken into small particles and spherodized more easily than the Al3 Fe intermetallic phase during the hot-rolling process. For the Mn containing alloys, both yield and ultimate tensile strength of the hot-rolled alloys increased from 270 to 296 MPa while elongation decreased from 17 to 13%, which can be attributed to Mn-containing intermetallic as well as dispersoid.

13

Finite element modelling of the hexagonal wire mesh

Grodecki M.

Archives of Civil Engineering

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2020

|

Vol. 66, nr 3

705--720

PL

Artykuł przedstawia wyniki symulacji numerycznych (wykonanych z wykorzystaniem Metody Elementów Skończonych MES) zachowania się stalowej splatanej sześciokątnej siatki używanej do budowy gabionów. Gabiony, wypełnione gruntem (najczęściej gruboziarnistym) są powszechnie używane w budownictwie, np. do budowy murów oporowych. Modelowano testy statycznego rozciągania siatki, uzyskane zależności siła – przemieszczenie porównano z literaturowymi wynikami badań laboratoryjnych. Zaobserwowano dobrą zgodność pomiędzy wynikami laboratoryjnymi a rezultatami symulacji numerycznych. Testowano trzy różne modele konstytutywne dla pojedynczego i podwójnego splecionego drutu. Specjalną uwagę poświęcono modelowaniu podwójnie splecionego drutu. Wykonano też symulacje zachowania się uszkodzonej siatki, analizowano spadek jej nośności i sztywności. Zaproponowano i wykalibrowano anizotropowy model membranowy dla siatki. Oszacowano parametry zhomogenizowanego ośrodka typu Coulomba – Mohra dla gabionu (siatki i wypełnienia). Model ten może być wykorzystywany w praktyce inżynierskiej do modelowania rzeczywistych konstrukcji gabionowych.

EN

This paper presents the results of Finite Element Method (FEM) modeling of double-twisted steel hexagonal wire mesh used to construct gabion cages. Gabion cages, filled with soil (usually rock particles) are commonly used in civil engineering (for example in order to form a retaining wall). Static tensile tests are modeled and the obtained force - displacements curves are compared with the laboratory test results (known from literature). Good accordance between numerical and laboratory test results is observed. Three different material models for single wire and double twist are tested. Special attention is paid to double-twist modelling. Simulations of the damaged mesh are also performed, strength and stiffness reduction is analyzed. Anisotropic membrane model for mesh is proposed and calibrated. Parameters for homogenized Coulomb - Mohr media for gabion (filling and mesh) are estimated. Such homogenized Coulomb - Mohr model could be used in engineering practice to model behaviour of real gabion structures.

14

The effect of the excess sludge pretreatment on biogas productivity

Bernat Katarzyna, Zielińska Magdalena, Kulikowska Dorota, Cydzik-Kwiatkowska Agnieszka, Wojnowska-Baryła Irena, Waszczyłko-Miłkowska Beata, Piotrowicz Beata

Technical Sciences / University of Warmia and Mazury in Olsztyn

|

2019

|

nr 22(1)

75--86

EN

To intensify biogas production during anaerobic stabilization of organic matter in sludge, pretreatment is applied. The effect of pretreatment of excess activated sludge (AS) and excess aerobic granular sludge (GS) on biogas productivity (BP) and composition was investigated. The sludge was pretreated with homogenization (6,500 rpm for 0.5 min (H0.5) and 1 min (H1.0)) or ultrasound disintegration at 20 kHz (50% amplitude for 2 min (D50%_2.0) and 4 min (D50%_4.0), and 100% amplitude for 4 min (D100%_4.0)). BP of AS of GS without pretreatment was 603.3±5 dm3/kg TS (793.4±7 dm3/kg VS); that was 200.6±4 dm3/kg TS (480.8±6 dm3/kg VS). With disintegration, the BP of AS increased by 7.8% (650.4±10 dm3/kg TS) (D50%_2.0) and 16.1% (700.6±11 dm3/kg TS) (D100%_4.0), and that of GS increased by 7.0% (214.0±5 dm3/kg TS) (D50%_2.0) and 16.0% (232.8±5 dm3/kg TS) (D100%_4.0). With homogenization, BP increased by 2.0-3.0% (AS) and 1.6-3.2% (GS).

15

Zastosowanie metody FMEA do oceny homogenizacji popiołu lotnego

Malindzakova Marcela

Przemysł Chemiczny

|

2019

|

T. 98, nr 11

1797--1801

PL

Metodę analizy rodzajów niepowodzeń i ich skutków FMEA (failure mode and effects analysis) zastosowano do oceny homogenizacji i zagęszczenia popiołu w celu identyfikacji „wąskich gardeł” tego procesu. Popiół zagęszczano cementem, który pobierano z silosu, po czym mieszano z wodą lub innymi środkami chemicznymi. Popiół lotny chemicznie stabilizowano, aby zapobiec przedostawaniu się zanieczyszczeń do środowiska. Do oceny nasilenia, występowania i wykrywania wad wykorzystano wskaźniki ryzyka RPN (risk priority numbers). Najwyższy wskaźnik ryzyka (243) wykazało zestalanie cementu w zbiorniku.

EN

The FMEA method was implemented for homogenization and compaction of ash to identify the bottle necks within the processes. The ash compaction was carried out by using a cement. It was pumped out of the silo, mixed with water or other chem. agents. The fly ash was chem. stabilized to avoid any addnl. leakage of pollutants into the environment. The risk priority nos. were used to assess the severity, occurrence and detection of failures. Solidification of cement in tank showed the highest risk priority no. (243).

16

Energetic Asymmetry Connected with Energy Flow Changes in Response to Eutrophication : A Study of Multiple Fish Species in Subtropical Shallow Lakes

Fu Hong, Zhang Huan, He Liang, Sha Yongcui, Zhao Kangshun, He Yuhan, Xu Jun

Polish Journal of Ecology

|

2019

|

Vol. 67, nr 4

305--315

EN

Energy flow is a central characteristic in all ecosystems, and it has attracted considerable scientific attention due to its significant effects on the stability of food webs. Lake ecosystems that undergo regime shifts (clear water phase, phytoplankton dominated changed into turbid water, macrophytes dominated or vice versa) are characterized by a series of transformation in trophic structure. Although previous studies have mainly focused on the causes and consequences of regime shifts in shallow lakes, studies about responses of energy flow changes to regime shifts is far from complete. In this paper, we estimated trophic position and benthivory (i.e. degree of benthivory) of seventeen fish species from seven shallow lakes. Our data show that the trophic position and benthivory of fish species in clear water phase are significantly higher than in turbid water. This finding might help spark some ideas for subtropical lake eutrophication treatment.

17

Identyfikacja czynników od działujących na proces homogenizacji i jakość produktu emulsyjnego

Paździor M.

Zeszyty Naukowe. Organizacja i Zarządzanie / Politechnika Śląska

|

2018

|

z. 118

457--468

EN

Emulsion products are widely used in various branches of industry. The quality of products based on emulsions depends significantly on the degree of their stability. Obtaining an emulsion unchanging in time is a difficult process to implement. It is depending on a number of factors. Despite many publications in this area so far, there is no development of a universal set of parameters that model stability of the emulsion product. The aim of the article is to examine what factors should be taken into account in designing the homogenization process and their systematics and indication of mutual connections. As a result of the research, the main and partial causes were diagnosed as a source of possible errors resulting in the unstable fatty emulsion. The analysis made it possible to identify significant nonconformities, the removal or limitation of which will translate into the quality of the emulsion product and the level of meeting the recipients' requirements.

PL

Produkty emulsyjne znajdują szerokie zastosowanie w różnych gałęziach przemysłu. Jakość produktów wytwarzanych na bazie emulsji zależy istotnie od stopnia ich stabilności. Otrzymanie niezmiennych w czasie emulsji jest procesem trudnym do realizacji, zależnym od szeregu czynników. Mimo szeregu publikacji w tym zakresie dotychczas brak jest opracowania uniwersalnego zestawu parametrów modelujących stabilność produktu emulsyjnego. Celem artykułu jest zbadanie jakie czynniki należy uwzględnić przy projektowaniu procesu homogenizacji oraz ich systematyka i wskazanie wzajemnych powiązań. W wyniku przeprowadzonych badań zdiagnozowano przyczyny główne i cząstkowe stanowiące źródło ewentualnych błędów, skutkujących otrzymaniem niestabilnej emulsji tłuszczowej. Analiza umożliwiła określenie istotnych niezgodności, których usunięcie lub ograniczenie przełoży się na jakość produktu emulsyjnego oraz poziom spełnienia wymagań odbiorców.

18

Convergence of random oscillatory integrals in the presence of long-range dependence and application to homogenization

Lechiheb A., Nourdin I., Zheng G., Haouala E.

Probability and Mathematical Statistics

|

2018

|

Vol. 38, Fasc. 2

271--286

EN

This paper deals with the asymptotic behavior of random oscillatory integrals in the presence of long-range dependence. As a byproduct, we solve the corrector problem in random homogenization of onedimensional elliptic equations with highly oscillatory random coefficients displaying long-range dependence, by proving convergence to stochastic integrals with respect to Hermite processes.

19

Modelowanie w mikro- i makroskali nawijanej rury kompozytowej

Błachut A., Krysiak P.

Modelowanie Inżynierskie

|

2018

|

T. 35, nr 66

5--11

PL

W artykule przedstawiono procedurę modelowania w różnych skalach długości nawijanej rury kompozytowej. Modelowanie w skali mikro posłużyło do wyznaczenia efektywnych właściwości mechanicznych kompozytu jednokierunkowego (homogenizacja numeryczna), natomiast w skali makro wykonano uproszczony model nawijanej rury kompozytowej, w którym uwzględniono obszary o zmienionej orientacji włókna. Dane potrzebne do modelowania wyznaczono metodą eksperymentalną poprzez wykonanie zgładów z rzeczywistej struktury, obserwację przy użyciu skaningowego mikroskopu elektronowego oraz przetworzenie cyfrowe zdjęć.

EN

This publication presents the procedure of multiscale modeling. Model in micro scale was used to determine the effective mechanical properties of one-directional composite (numeric homogenization). Simplified model of wound composite pipe was made in macro scale. In presented simulation changed orientation of fibers were included. Informations needed for modeling were determinated by experimental method: perfomation of speciments from the real structure and observation of it by using a scanning electron microscope (with digital image processing).

20

Fourier variant homogenization treatment of single impulse boundary effect behaviour

Kula D., Wierzbicki E., Witkowska-Dobrev J., Wodzyński Ł.

Mechanics and Mechanical Engineering

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2018

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Vol. 22, nr 3

683--690

EN

Boundary effect behavior understood as near-boundary suppression of boundary fluctuation loads is described in various ways depending on the mathematical representation of solutions and the type of the center. In the case of periodic composites, the homogenization method is decisive here. In the framework of the Tolerance Averaging Approach, developed by prof. Cz. Wo´zniak leading to an approximate model of phenomena related to periodic composites this effect is described by a homogeneous part of differential equation for fluctuation amplitudes and usually this approximate description of the boundary effect behavior is restricted to a single fluctuation. In this paper, contrary to the previous elaborations, the boundary effect is developed in the variant of the tolerance thermal conductivity model in which the temperature field is represented by the Fourier expansions composed by an average temperature with infinite number of Fourier terms imposed on the average temperature as tolerance fluctuation suppressed in the framework of the boundary effect.