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1

Aerospace 3D textile preform analysis: experimental and mesomodeling

Saboktakin Abbasali, Izmir Hossein Safaei

Composites Theory and Practice

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2023

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R. 23, nr 3

118--122

EN

For the purpose of predicting how textile preforms affect the quality of the composite material and its performance, the stitched textile preform must be characterized. Experimental compaction analysis and finite element analysis of textile preforms are the main subjects of this paper. The formability parameters of a preform can be changed by the stitching process, according to research on the mechanical properties of preforms conducted during compression testing. The loaddeformation response, which is depicted in detail, had the greatest influence on preform deformation. Less fiber bundle undulation in the plane direction and more stitching thread undulation in the thickness direction were observed during compression of the stitched preform, whereas the stitching thread improved the resistance of the preform to compression loading.

2

Immobilization with Ca–Alg@gelatin hydrogel beads enhances the activity and stability of recombinant thermoalkalophilic lipase

Yildiz Dalginli Kezban, Atakisi Onur

Chemical and Process Engineering : New Frontiers

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2023

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Vol. 44, nr 1

art. no. e2

EN

This study aims at the immobilization and characterization of thermoalkalophilic lipases produced recombinantly from Bacillus thermocatenulatus BTL2 and Bacillus pumilus MBB03. For this purpose, immobilization of the produced enzymes in calcium-alginate@gelatin (Ca–Alg@gelatin) hydrogel beads, immobilization optimization and characterization measurements of the immobilized-enzyme hydrogels were conducted. Optimum temperature and pH values were determined for B. thermocatenulatus and B. pumilus MBB03 immobilized-enzyme hydrogels (60–70 °C, 55 °C and pH 9.5, pH 8.5). Thermal stability was determined between 65 °C and 60 °C of B. thermocatenulatus and B. pumilus MBB03 immobilized enzymes, respectively. The pH stability was determined between pH 7.0–11.0 at +4°C and pH 8.0–10.0 at +4 °C, respectively. In conclusion, the entrapment technique provided controlled production of small diameter hydrogel beads (~ 0:19 and ~ 0:29) with negligible loss of enzyme. These beads retained high lipase activity at high pH and temperature. The activity of Ca–Alg@gelatin-immobilized lipase remained relatively stable for up to three cycles and then markedly decreased. With this enzyme immobilization, it may have a potential for use in esterification and transesterification reactions carried out in organic solvent environments. We can conclude that it is one of the most promising techniques for highly efficient and economically competent biotechnological processes in the field of biotransformation, diagnostics, pharmaceutical, food and detergent industries.

3

On a characterization of exponential, Pearson and Pareto distributions via covariance and pseudo-covariance

Pawlas Piotr, Szynal Dominik

Demonstratio Mathematica

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2020

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Vol. 53, nr 1

285--291

EN

Properties of linear regression of order statistics and their functions are usually utilized for the characterization of distributions. In this paper, based on such statistics, the concept of Pearson covariance and the pseudo-covariance measure of dependence is used to characterize the exponential, Pearson and Pareto distributions.

4

Physicochemical characterization of the fuel by the ultrasound method

Soudani Said, Mekkaoui Mohammed, Nassar George, Derouiche Ziane

Computer Methods in Materials Science

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2020

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Vol. 20, No. 1

31--37

EN

After the successful experience made to show the close correlation between physicochemical parameters of a medium and their ultrasond's parameters,we use these results to design an ultrasond measuring bench that allows the physicochemical characterization of a medium from its ultrasond's parameters. The aim is to proceed at the physicochemical characterization of the various oils wells in the HASSI MESSAOUD zone petrolium of Algeria in oder to design with the hydraulic's departement of the university the appropriate extraction pumps at each well. Since it was difficult to obtain sample of the wells in question,we have treated engine oils which have the same characterization parameters as fuel

PL

Każde medium fizyczne, bez względu na to czy jest to ciało stałe, płyn czy gaz, jest charakteryzowane przez parametry fizykochemiczne, które są dla niego unikalne i różne od innych ośrodków. Ale może ono być także charakteryzowane przez akustyczne parametery, które są również unikalne. Te dwie charakterystyki są jak dwie strony tej samej monety. Na podstawie tej hipotezy w pracy zaproponowano projekt urządzenia pomiarowego umożliwiającego fizykochemiczną charakteryzację medium na podstawie parametrów ultradźwiękowych. Określono charakterystyki wybranych paliw wykorzystując standardowe metody wyznaczania parametrów fizycznych (lepkość, wskaźnik lepkości, gęstość, temperatura płynięcia, punkt zapłonu, %azotu, %cynku). Te same próbki scharakteryzowano przez wyznaczenie ich parametrów ultradźwiękowych (ściśliwość, wchłanianie, osłabienie, funkcja przejścia, impedancja akustyczna). Sformułowano dwie bazy danych: fizyczną i akustyczną. W dalszej kolejności przyjęto, że w celu wyznaczenia parametrów fizycznych dowolnej próbki z tego samego medium, wystarczy określić jego parametry ultradźwiękowe. Dlatego zastąpiono bazy parametrów fizycznych i chemicznych jedną bazą parametrów ultradźwiękowych. Celem tych prac była bardziej zaawansowana charakteryzacja olei w zakładach HASSI MESSAOUD w Algerii w celu zaprojektowania odpowiednich pomp wydobywczych dla każdego szybu naftowego. W związku z trudnościami w zdobyciu próbek z badanych szybów, w pracy wykorzystano oleje silnikowe o podobnych charakterystykach.

5

Analiza metod badań nieniszczących pod względem logistycznym

Szeleziński A., Muchowski T., Muc A.

Gospodarka Materiałowa i Logistyka

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2018

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nr 12

1154--1171, CD

PL

W pracy przeprowadzono analizę metod badań nieniszczących ze szczególnym wskazaniem na uwarunkowania logistyczne. Zalety badań nieniszczących spowodowały, że są one często uwzględniane w różnych systemach pomiarowych. Jednocześnie popularyzacja badań nieniszczących przyczyniła się do rozwoju nowych metod pomiarowych, a istniejące są nieustannie ulepszane i modernizowane. Każda ze stosowanych metod nieniszczących opiera się na innym zjawisku i wykorzystuje odmienne urządzenia. Artykuł opisuje najczęściej stosowane metody – przedstawia sposób wykonywania pomiarów oraz najczęstsze zastosowania.

EN

The paper presents an analysis of non-destructive testing methods with particular reference to logistic conditions. The advantages of non-destructive testing have caused that they are often included in various measurement systems. At the same time, the popularization of non-destructive testing has contributed to the development of new measurement methods, and existing ones are constantly improved and modernized. Each of the used non-destructive methods is based on a different phenomenon and uses different devices. The article describes the most commonly used methods - it presents the ways of making measurements and the most common applications.

6

Synthesis and characterization of poly(acrylic acid)/organo-modified nanohydroxyapatite nanocomposites: thermal, optical and biocompatibility properties

Diken M. E., Doğan S., Turhan Y., Doğan M.

Advances in Materials Science

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2018

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Vol. 18, nr 3(57)

54--67

EN

The aim of this study was to investigate the structural, thermal, optical and biocompatibility properties of poly(acrylic acid)(PAA)/organo-modified nanohydroxyapatite (OM-nHAp) nanocomposites synthesized by solvent intercalation method. The characterization of PAA/OM-nHAp nanocomposites was made by different techniques. SEM and TEM results showed that OM-nHAp particles were dispersed in the nanoscale into PAA matrix and that they were uniformly distributed within film. Glass transition temperature of PAA increased with OM-nHAp content. Ultraviolet (UV) absorbance experiments showed that PAA had a higher UV transmission than its nanocomposites. The biocompatibility of nanocomposites was also examined in simulated body fluid.

7

Metal-ceramic functionally graded materials – manufacturing, characterization, application

Chmielewski M., Pietrzak K.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2016

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Vol. 64, nr 1

151--160

EN

Functionally graded materials (FGMs) belong to a new, continuously developing group of materials, finding application in various branches of industry. The idea of freely designing their construction profile, restricted only by the available manufacturing techniques, enables obtaining materials with composition and structure gradients having unprecedented properties. In this paper, selected results of works carried out by the authors and relating to the application of the developed metal-ceramic composites were presented in order to manufacture functionally graded materials for target purposes. Gradient structures with various construction profiles that can play different roles were produced on the basis on the following material pairs: Cr-Al2O3, NiAl-Al2O3 and Cu-AlN. Manufacturing conditions, microstructure characteristics and selected properties, crucial from the point of view of future applications, were presented.

8

Wpływ domieszkowania na właściwości węglika krzemu (SiC) : przegląd

Racka-Szmidt K.

Elektronika : konstrukcje, technologie, zastosowania

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2015

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Vol. 56, nr 12

67-83

PL

W pracy przedstawiono przegląd literatury dotyczący domieszkowania węglika krzemu (SiC) – materiału półprzewodnikowego perspektywicznego dla szeregu istotnych zastosowań w sensoryce, spintronice, optoelektronice oraz w przyrządach półprzewodnikowych dużej mocy, wielkiej częstotliwości i wysokich temperatur. Zaprezentowano podstawowe parametry domieszek oraz ich wpływ na właściwości elektryczne, magnetyczne i optyczne SiC. Na tle doniesień literaturowych pokazano własne wyniki badań właściwości optycznych domieszkowanych kryształów SiC otrzymanych metodą transportu fizycznego z fazy gazowej (PVT).

EN

The paper presents a review of the literature which concerns a doping of the silicon carbide (SiC) – a semiconductor material which is a prospective material for many of important applications in sensorics, spintronics, optoelectronics and for high-power, high-frequency and high-temperature semiconductor devices. Basic parameters of dopants and their influence on electrical, magnetic and optical properties of SiC have been presented. Own results of investigations of optical properties of doped SiC crystals, obtained by physical vapor transport method (PVT), have been shown on the background of the literature.

9

Lignitic fly ash byproducts from TPP Kostolac-B, Serbia and its usage

Tomanec R., Stefanovic M., Cablik V.

Inżynieria Mineralna

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2013

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R. 14, nr 2

91--97

EN

In this study, the fly ash taken from the lignite thermal power plant Kostolac-B, Kostolac, Serbia, is characterized and separated from its byproducts. Fly ash is composed of unburned carbon, iron compounds typically of magnetite, pozzolanic material and cenospheres. A systematic study is conducted to establish the optimum conditions for the separation of these materials from fly ash. In this context, concentration techniques such as magnetic, gravity separations (heavy liquids separation) and flotation are put forward. Finally the lightweight fraction, from which the magnetic minerals and the unburned coal substance were removed, as well as microspheres, is an excellent material for the production of building materials – blocks and bricks, for concrete mixtures, cement additives, for fly ash pelletization process using Portland cement binder and other purposes. The main elements (fractions of valuable components) of the fly ash that determine its usability are: the quantity of unburned carbon, content of iron compounds (typically of magnetite and haematite), the pozzolanic material, microsphere (cenospheres) content, size distribution, mechanical properties of the pellets etc. The preliminary investigations and accomplished tests exhibited satisfactory results.

PL

Streszczenie W artykule przedstawiono charakterystykę oraz wyniki badań nad wzbogacaniem popiołów lotnych ze spalania węgla w Ciepłowni Kostolac –B w miejscowości Kosolac w Serbii. Popioły lotne składają się z niedopału węgla, składników żelazo nośnych (najczęściej magnetyt, materiałów pucolanowych i cenosfer. Celem badań było określenie optymalnych warunków separacji popiołów. Badania przeprowadzono wykorzystując metody wzbogacania magnetycznego, grawitacyjnego(wzbogacanie w cieczy ciężkiej) i flotacji. W końcowym etapie wzbogacania uzyskano frakcję lekką, pozbawiona części magnetycznej i niedopału oraz ceno sfer, która może być wykorzysta na do produkcji materiałów budowlanych – bloczków, cegieł, betonu, dodatków do cementu, jako dodatek do procesu pelletyzacji z wykorzystaniem cementu portlandzkiego i podobnych zastosowań. Najważniejsze czynniki, które decydują o jakości popiołu są ilość niedopału, zawartość minerałów żelaza (magnetyt, hematyt), zawartość pucolanów i mikrosfer (ceno sfery), sklad ziarnowy, właściwości mechaniczne peletów itd. Wstępne badania i testy dały zadowalające wyniki.

10

Objective assessment for characterising the flatness of garment sewing stitches

Jiang H., Liu J., Chai Z., Wang C., Zhang M.

Autex Research Journal

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2013

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Vol. 13, no. 4

110--117

EN

In this paper, a novel classification method of assessing garment sewing stitch based on amended bi-dimensional empirical mode decomposition (ABEMD) has been introduced. Two parameters that characterise garment sewing stitch, average area and standard deviation, have been defined based on the grey value of pixels. Experimental results showed that when the window size is 512×128 pixels with regard to average area, the threshold can be decided as 6.00, 5.50, 5.30 and 4.00 for five different grades , respectively. Meanwhile, with regard to standard deviation, the threshold can be decided as 48.00, 40.00, 30.00 and 20.00, respectively. It is demonstrated that the parameters are effective in discriminating sewing stitch images in terms of the grades when used as inputs for the ABEMD. The performance of the algorithm on different garment status is significantly reliable.

11

Experimental study of power IGBT technologies at large range temperature

Fock-Sui-Too J. L., Chauchat B., Nicolau S., Madrid F., Austin P., Tounsi P., Mermet-Guyennet M.

Electronics and Telecommunications Quarterly

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2008

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Vol. 54, No 4

513-532

EN

Aeronautical power electronics applications impose high power density handling and device operation temperatures. SiC technology not being mature enough, the temperature limits of silicon devices must be pushed in order to increase current ranges and the amount of switched power. Device ageing is accelerated and there exist the risk of catastrophic failure by thermal runaway. In order to design correctly high temperature power systems, knowing the IGBT characteristics at extended temperature ranges (-55*C, +175*C) becomes essential. The present work describes an experimental setup and test procedure conceived to experiment with different available IGBT technologies at temperatures above the limits rated by manufacturers. The aim is to generate experimental data for the creation of accurate models with large temperature scale. This will ease prototyping for future development of IGBT modules in aircraft.