Wyniki wyszukiwania - Biblioteka Nauki

1

Airflow Characteristics during the Rotor Spun Composite Yarn Spinning Process

100%

Yang R. , Gao W. , Xue Y.

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tom Vol. 25, no. 5 (125)

13--17

EN

Rotor spun composite yarn shows compound performances when combined with staple fibres and filaments, such as excellent hand feeling as well as extreme elasticity and strength. Air characteristics including pressure and speed are critical factors of the rotor spun composite yarn spinning process. In this paper, air flow characteristics in a rotor composite yarn spinning unit are simulated and analysed by Ansys, and then verified by experiments. The results show that with the same spinning conditions, static pressure within the filament guide tube is lowest: -9 kPa and in rotor around -5 kPa. The speed of the airstream accelerates from the transfer channel inlet to the outlet, and reaches the largest value of 386 m/s at the outlet. As the rotor speed increases, the airflow velocity increases; the static pressure decreases; the breaking strength and CV of the composite yarn increase, and the breaking elongation and hairiness decrease according to the experiment results.

PL

Przędza kompozytowa charakteryzuje się doskonałym chwytem, a także wyjątkową elastycznością i wytrzymałością. Charakterystyka przepływu powietrza, w tym ciśnienie i prędkość, są czynnikami decydującymi o przędzeniu przędzy kompozytowej na przędzarce rotorowej. W artykule przeprowadzono stymulację i analizę charakterystyk przepływu powietrza, a następnie wyniki zweryfikowano eksperymentalnie. Prędkość strumienia powietrza przyspiesza od wlotu kanału przenoszenia do wylotu i osiąga największą wartość 386 m/s na wylocie. Gdy prędkość wirnika wzrasta, prędkość przepływu powietrza również wzrasta, a ciśnienie statyczne maleje, natomiast wytrzymałość na zerwanie przędzy kompozytowej wzrasta.

2

Yarn-Dyed Fabric Defect Detection Based On Autocorrelation Function And GLCM

100%

Zhu D. , Pan R. , Gao W. , Zhang J.

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tom Vol. 15, no. 3

226--232

EN

In this study, a new detection algorithm for yarn-dyed fabric defect based on autocorrelation function and grey level co-occurrence matrix (GLCM) is put forward. First, autocorrelation function is used to determine the pattern period of yarn-dyed fabric and according to this, the size of detection window can be obtained. Second, GLCMs are calculated with the specified parameters to characterise the original image. Third, Euclidean distances of GLCMs between being detected images and template image, which is selected from the defect-free fabric, are computed and then the threshold value is given to realise the defect detection. Experimental results show that the algorithm proposed in this study can achieve accurate detection of common defects of yarn-dyed fabric, such as the wrong weft, weft crackiness, stretched warp, oil stain and holes.

3

Theoretical Study of Yarn Torque Caused by Fibre Tension in the Spinning Triangle

88%

Su X. , Gao W. , Liu X. , Xie C. , Xu B.

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2014

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tom Vol. 22, no. 6 (108)

41—50

EN

The spinning triangle is a critical region in the spinning process of staple yarn, the geometry of which plays an important role in determining the physical performance and qualities of spun yarns, especially yarn torque. It has been shown that the fibre tension in the spinning triangle is the most influential factor governing the magnitude of yarn torque. Therefore, in this paper, a theoretical study of yarn torque caused by fibre tension in the spinning triangle is presented. Cases of yarn with one, two, three, four and five feeding strands were investigated, in which the arrangement of fibres was assumed as hexagonal close packing with a single core fibre, two core fibres, three core fibres, four core fibres, and five core fibres at the centre, respectively. Theoretical models of the fibre tension in spinning triangles and corresponding yarn residual torque due to the fibre tension are presented. As an application of the method proposed, 26.5 tex cotton yarns were taken as an example for numerical simulations. Fibre tension in the spinning triangles and corresponding yarn torque were simulated numerically using Matlab software.

PL

Trójkąt przędzalniczy jest istotnym obszarem w procesie przędzenia przędzy z włókien odcinkowych, jego geometria odgrywa ważną rolę w wyznaczaniu właściwości fizycznych oraz jakościowych, zwłaszcza momentu obrotowego przędzy. Wykazano, że naprężenie włókien w trójkącie przędzalniczym znacząco wpływa na wielkość momentu przędzy. Badano przypadki powstawania trójkąta przędzalniczego z jednego, dwóch, trzech, czterech i pięciu strumieni włókien i przy różnych ilościach włókien w rdzeniu przędzy. Badano rozkłady włókien w przędzy oraz powstające siły naprężeń i momenty obrotowe. Sporządzono obliczenia komputerowe i odpowiednie wykresy dla przędzy bawełnianej 26.5 tex.

4

Dynamic Measurement of Foam-Sized Yarn Properties from Yarn Sequence Images

88%

Zhu B. , Li Z. , Cao X. , Liu J. , Gao W.

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tom Vol. 18, no. 3

314--322

EN

Unlike the normal sizing method, the foam sizing had been proven to be a low-add-on technology. To investigate the effect of foam sizing, film thickness, sized-yarn evenness, and size penetration rate were necessary to evaluate the performances of foam-sized yarns. However, the conventional image analysis of sized-yarn cross sections primarily relied on artificial testing with a low efficiency. This paper proposed a novel dynamic method to measure the sized-yarn properties including film thickness, sized-yarn evenness, and size penetration rate based on yarn sequence images captured from a moving yarn. A method of dynamic threshold module was adopted to obtain threshold for segmenting yarns in the sequence images. K-means clustering algorithm was applied to segment pixels of the images into yarn and background. To further remove burrs and noise in the images, two judgment templates were carried out to extract the information of yarn core. The film thickness, sized-yarn evenness, and size penetration rate were measured based on the yarn core of each frame in sequence images. In order to compare with the experimental results of the dynamic method, the yarn properties of the same samples were tested by static and artificial testing. Results revealed that the proposed method could efficiently and accurately detect the film thickness, sized-yarn evenness, and size penetration rate.

5

Prostaglandin D2 produced by hematopoietic prostaglandin D synthase contributes to LPS-induced fever

75%

Gao W. , Schmidtko A. , Wobst I. , Lu R. , Angioni C. , Geisslinger G.

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nr 2

145-150

EN

A large body of evidence has implicated prostaglandin E2 (PGE2) in fever production. However, the role of PGD2 in this context is only poorly understood. We therefore determined by LC-MS/MS analyses the content of PGD2 and PGE2 in cerebrospinal fluid (CSF), plasma and lungs of rats over 5 hours after fever induction by intraperitoneal injection of lipopolysaccharide (LPS, 50 µg/kg). Both PGD2 and PGE2 were detected in CSF, plasma and lungs of saline-treated control animals. The injection of LPS evoked fever and an increase of PGE2 in the CSF, while the CSF content of PGD2 was not significantly altered. However, both PGE2 and PGD2 levels were elevated in plasma and lungs after LPS injection. Interestingly, pretreatment with a novel selective inhibitor of hematopoietic prostaglandin D synthase (H-PGDS), EDJ300520 (10-40 mg/kg p.o.), selectively and dose-dependently prevented the LPS-induced increase of PGD2 in plasma and lungs but did not affect the PGE2 content. Most remarkably, EDJ300520 pretreatment led to an hypothermic response after LPS injection during the first 3 h and prevented fever induction. These data indicate that PGD2 produced peripherally by H-PGDS essentially contributes to LPS-induced fever.

6

Evaluation of an Intelligent Computer Method for the Automatic Mosaic of Sequential Slub Yarn Images

75%

Li Z. , Zhang N. , Wu Y. , Wang J. , Pan R. , Gao W.

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tom Vol. 26, no. 2 (128)

38--48

EN

This paper is the second part of a series reporting the recent development of a computerised method for automatic mosaic sequential yarn images. In our earlier work, an effective method for stitching sequence slub yarn images automatically was developed based on image processing and the normalised cross correlation (NCC) method. 100 image pairs of two kinds of slub yarn were measured in certain specific conditions, such as the frame rate, size of stitching template, etc., and the measurement results were evaluated with the manual method. In this paper, the effects of various influencing factors are numerically examined, including the stitching template size, threshold value, frame rate, and computing time of the mosaic algorithm. The feasibility and accuracy of the fully computerized method were evaluated further under the various influencing parameters. One hundred percent cotton ring spun single slub yarns of 27.8, 15.6, and 9.7tex were prepared and used for the evaluation. The measurement results obtained by the method proposed are analysed and compared with those measured manually by Adobe Photoshop. The experimental results show that the method proposed can accurately find the stitch position and has a high consistency with the manual method when the matching template is 100 × N pixels, the threshold value T1∈[20, 40] and T2∈[51, 80], and the frame rate is greater than 40fps.

PL

Artykuł jest drugą częścią serii opisującej opracowanie sekwencyjnej metody przetwarzania obrazu przędz ozdobnych. We wcześniejszej pracy opracowano skuteczną metodę oceny przędz w oparciu o przetwarzanie obrazu i znormalizowaną metodę korelacji krzyżowej (NCC). Zbadano w określonych warunkach (liczba klatek na sekundę, rozmiar szablonu szycia itp.) 100 par obrazów dwóch rodzajów przędz, a następnie oceniono wyniki pomiarów. Przeprowadzono eksperymenty mające na celu zbadanie wykonalności i dokładności proponowanej metody. W pracy przeanalizowano numerycznie wpływ różnych czynników tj. rozmiaru szablonu, wartości progowej, liczby klatek na sekundę i czasu obliczeń algorytmu mozaikowego. Wykonalność i dokładność w pełni skomputeryzowanej metody zostały poddane dalszej ocenie. Metodę manualnej segmentacji obrazu i metodę automatycznej identyfikacji powierzchni przędzy ozdobnej przy wykorzystaniu odpowiednio przygotowanego algorytmu opartego o techniki numeryczne. W metodzie ręcznej segmentacji wprowadzono zmienne oparte o prędkość odczytywania danych z obrazu, które następnie poddawano analizie. W metodzie automatycznej zaproponowano wprowadzenie innych bardzie przydatnych zmiennych do identyfikacji charakterystycznych cech strumienia włókien. Plan eksperymentu obejmował trzy rodzaje przędz bawełnianych wytworzonych na przędzarce obrączkowej (27,8, 15,6 i 9,7tex). Wyniki pomiarów zaproponowanej metody analizowano i porównywano z pomiarami wykonywanymi ręcznie. Wyniki eksperymentalne pokazały, że proponowana metoda może być z powodzeniem stosowana i ma wysoką zgodność z metodą ręczną, przy szablonie 100 x N pikseli, wartości progowej T1∈ [20, 40] i T2∈ [51, 80] oraz liczbie klatek na większej niż 40 klatek na sekundę.

7

Design and fabrication of an organic/inorganic hybrid co-planar waveguide electro-optic modulator

75%

Gao W. , Sun J. , Sun X. , Yan Y. , Gao L. , Zhang D.

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2009

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tom Vol. 39, nr 3

467-472

EN

We have successfully designed and demonstrated a co-planar waveguide (CPW) Mach-Zehnder (MZ) electro-optic (EO) modulator using a strip-loaded waveguide structure. The hybrid material, easily synthesized by sol-gel process, with a large EO coefficient of r33 = 50 pm/V and a long- -term stability at 80 °C for 200 hours is selected as the active layer. A simple and easily fabricated strip-loaded waveguide structure is designed for utilizing the EO material and reducing the coupling loss with optical fiber. The optimized design principles of the efficient transmission for such a modulator are discussed. The measured half-wave voltage V? of 8.5 V for the MZ modulator is gained at 1550 nm and shows a good agreement with the simulating result.