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1

Effects of service environment and pre‑deformation on the fatigue behaviour of 2524 aluminium alloy

Chen Y. Q., Zhang H., Pan S. P., Song Y. F., Liu X., Liu W. H.

Archives of Civil and Mechanical Engineering

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2020

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Vol. 20, no. 1

56--71

EN

The effects of service environment and pre-deformation on the fatigue behaviour of 2524 alloy were investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and fatigue tests. The results indicate that the fatigue crack-growth rate (FCGR) of the alloy in an aqueous environment increases with temperature ranging from 0 to 90 °C. At the same stress intensity factor range (ΔK), the FCGR of the alloy in an argon environment is the smallest, followed by that in air, and a 3.5% NaCl fog environment, while that in an exfoliation corrosion (EXCO) solution is the largest. A pre-deformation of 2% can significantly enhance the fatigue crack propagation resistance of this alloy in argon, air, and 3.5% NaCl fog environments, while 5% pre-deformation weakens the fatigue crack propagation resistance of the alloy accordingly. The pre-deformation effect on the FCGR of alloy in the EXCO solution environment is limited.

2

UV-Vis spectroscopic detection coupled with chemometrics for the measurement of mixed organic acids in water samples enriched by radial electric focusing solid phase extraction

Guo Y., Liu X., Liu J., Bian X., Zhang Q., Pan J., Wan D.

Metrology and Measurement Systems

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2018

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Vol. 25, nr 2

317--329

EN

Due to the difficulty of detecting traces of organic acid mixture in an aqueous sample and the complexity of resolving UV-Vis spectra effectively, a combinatory method based on a self-made radical electric focusing solid phase extraction (REFSPE) device, UV-Vis detection and partial least squares (PLS) calculation is proposed here. In this study, REFSPE was used to enhance the extraction process of analytes between the aqueous phase and the membrane phase to enrich the trace of mixed organic acid efficiently. Then, the analytes, which were eluted from the adsorption film by ethanol with the assistance of an ultrasonic cleaning machine, were detected with UV-Vis spectrophotometry. After that, the PLS method was introduced to solve the problem of overlapping peaks in UV-Vis spectra of mixed substances and to quantify each compound. The linearly dependent coefficients between the predicted value of the model and the actual concentration of the sample were all higher than 0.99. The limit values of detection for benzoic acid, phthalic acid and p-toluene sulfonic acid were found at 9.9 μg/L, 12.2 μg/L and 13.8 μg/L with the relative recovery values between 84.8% and 117.9%. The RSD (n = 20) values of each component are 1.17%, 1.11% and 0.86%, respectively. Therefore, the proposed combined method can determine traces of complex materials in an aqueous sample efficiently and has wonderful potential applications.

3

Research on the Qualities of Cellulosic Yarn

Su X., Qin X., Liu X., Xie C., Xu B.

Fibres & Textiles in Eastern Europe

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2018

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Vol. 26, no. 1 (127)

30--35

EN

Cellulosic fibre is a kind of renewable fibre that has attracted more and more attention in textile processing recently. Yarn spinning is the first fundamental process in textile processing. Therefore, in this paper, taking viscose fibre and tencel fibre as examples, the qualities of cellulosic yarn were studied. Three kinds of pure viscose and tencel yarn: 14.6 tex (40S), 9.7 tex (60S) and 7.3 tex (80S), were spun on a ring spinning system modified with lattice apron compact spinning (LACS) and complete condensing spinning (CCS), respectively. The spun yarn qualities, yarn evenness, breaking strength and hairiness, were tested and comparatively analysed. Then two kinds of cellulosic blend yarn including 14.6 tex, 9.7 tex and 7.3 tex JC/R 60/40 yarn, and 14.6 tex, 9.7 tex and 7.3 tex JC/T 70/30 yarns were spun on a ring spinning system modified with CCS. The spun yarn evenness, breaking strength and hairiness were tested, and the cross sections of the spun yarns were presented using a Y172 Hardy’s thin cross-section sampling device. The results show that for both the pure viscose and tencel yarn, compared with LACS, CCS has better yarn evenness, a little lower yarn breaking strength and a little more hairiness, while the uniformity of yarn qualities are all improved. For the cellulosic blend yarn, compared with the pure cellulosic yarn, yarn evenness is worse, especially for the cotton and tencel blend yarn.

PL

Włókna celulozowe są włóknami odnawialnymi, które przyciągają ostatnio coraz więcej uwagi w dziedzinie przetwarzania tekstyliów. Przędzenie przędzy jest pierwszym podstawowym procesem w przetwarzaniu tkanin. W artykule, na przykładzie włókien wiskozowych i Tencel, zbadano właściwości przędz celulozowych. Badaniom poddano trzy rodzaje przędz: 14,6 tex (40S), 9,7 tex (60S) i 7.3 tex (80S) wyprzędzionych na pierścieniowym systemie przędzalniczym zmodyfikowanym za pomocą kompaktowego przędzenia kratowego (LACS) i pełnego przędzenia kondensacyjnego (CCS) . Zbadano i porównano następujące właściwości przędz: równość, wytrzymałość na rozrywanie i włochatość. Następnie wyprzędziono przędze: 14.6 tex i 9,7 tex i 7.3tex (JC/R 60/40; JC/T 70/30). Ocenie poddano równomierność, wytrzymałość na rozerwanie i włochatość, oraz przekroje poprzeczne wytworzonych przędz. Wyniki pokazały, że zarówno dla przędzy wiskozowej, jak i Tencel, przędze otrzymane przy zastosowaniu CCS, w porównaniu z LACS, miały lepszą równomierność, trochę gorszą wytrzymałość na zerwanie i trochę większą włochatość.

4

Effects of hole perpendicularity error on load distribution in single-lap double-bolt composite joints

Li R., Xiao R., Ge E., Gao H., Bao Y., Liu X.

Engineering Transactions

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2018

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Vol. 66, iss. 1

3--19

EN

Although automated machines are widely used in composite structure manufacturing, manually drilled holes are usually necessary due to spatial constrains and holes with perpendicularity errors are occasionally generated as a result. Considering the anisotropic properties of composite material, the influences of hole perpendicularity error on mechanical performances of composite joints are different from those of isotropic material. In this study, the effects of hole perpendicularity error on load distribution in single-lap double-bolt composite joints are discussed. A finite element model is first developed and verified both by analytical and experimental results. Parametric studies are then carried out taking into consideration bolt torque and hole perpendicularity error, represented by hole tilting direction and tilting angle. It is found that the hole tilting direction significantly affects on load distribution in composite joints. Although the loads taken by bolts are not significantly affected, it may make one composite plate take more than 60% of total loads. In addition, the influences of tilting angle on load distribution can be ignored in most cases, and as for the bolt torque, it is to enhance the influence of hole tilting direction.

5

Parametric study on cement treated aggregate panel under impact load

Ali S., Liu X., Thambiratnam D., Fawzia S., Gu Y., Wu J., Remennikov A.

Archives of Civil and Mechanical Engineering

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2018

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Vol. 18, no. 2

622--629

EN

The cement treated aggregate (CTA) is increasingly used as base or sub-base layer for pavement to withstand various traffic and dynamic loads. Under extreme events, the CTA layer of the pavement is expected to absorb significant amount of impact energies subjected to different loading conditions including accidents, mobile vehicles, heavy aircrafts, machinery, or even terrorist attack. However, no research has been found on the resistance of CTA under drop weight impact load. To fill up this gap, a detailed study was carried out to investigate the impact resistance of CTA under impact loading through both experimental and finite element analysis (FEA). Moreover, detailed parametric studies were carried out based on the validated model to determine the significance of selected key parameters on the impact resistance of CTA.

6

Research on the neuro-protective compounds in Terminalia chebula retz extracts in-vivo by UPLC–QTOF-MS

Zhang Y., Liu X., Gao S., Qian K., Liu Q., Yin X.

Acta Chromatographica

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2018

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Vol. 30, no. 3

169--174

EN

We have developed a strategy to analyze the components absorbed in the plasma and brain tissue of rats after intragastric administration of Terminalia chebula Retz extracts by ultra-performance liquid chromatography–quadrupole time-of-flight mass spectrometry (UPLC–QTOF-MS). Nine components (gallic acid, methyl gallate, ferulic acid, ethyl gallate, brevifolin carboxylic acid, ellagic acid, galloflavin, arjugenin, and arjunic acid) and four metabolites were identified in plasma, and five components (ethyl gallate, brevifolin carboxylic acid, ellagic acid, arjugenin, and arjunic acid) were identified in the rat brain based on their fragmentation behaviors. The components present in the plasma were associated with the antioxidant activity of T. chebula Retz, and the components absorbed in the brain were associated with its neuro-protective effects. This approach allowed us to rapidly determine the active components of T. chebula Retz and develop a method for its quality control. This analysis method showed good resolution and high sensitivity, and is a potentially powerful tool for the determination of effective components of natural products.

7

Analysis of chloramphenicol in drinking water using an evaporation preparative step and isotope dilution liquid chromatography–tandem mass spectrometry

Li Y., Liu X., Zhang R., ZomPa D., Luo P., Tang L., Liu X., Zhou Y., Wen S.

Acta Chromatographica

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2018

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Vol. 30, no. 1

17--20

EN

A reliable isotope dilution method for the determination of chloramphenicol (CAP) in drinking water was developed by using an evaporation preparative step. Each sample was monitored by ultrahigh-pressure liquid chromatography (UHPLC) coupled to tandem mass spectrometry (MS/MS) using an electrospray ionization interface (ESI) in negative ion modes. Recoveries of spiked samples were in the range from 93.2% to 95.7% with intra-day relative standard deviation lower than 6.7% and inter-day relative standard deviation lower than 8.2%. Limit of quantification (LOD) was 0.002 ng/mL. The developed method was successfully applied to the analysis of CAP in drinking water of Shannan region of Tibet.

8

Thermal stability and mechanical properties of hybrid materials based on nitrocellulose grafted by aminopropylisobutyl polyhedral oligomeric silsesquioxane

Yang X., Wang Y., Li Y., Li Z., Song T., Liu X., Hao J.

Polimery

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2017

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T. 62, nr 7-8

576--587

EN

The need for improvement in nitrocellulose (NC) storage safety and convenience of application requires an increase in NC thermal stability and enhancement of its mechanical properties. To this aim, hybrid materials were synthesized by grafting NC with aminopropylisobutyl polyhedral oligomeric silsesquioxane (amino-POSS) using isophorone diisocyanate (IPDI) as a crosslinking agent. The structure and elemental composition of the resulting products were confirmed by Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (1H NMR and 29Si NMR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). It was found, based on the silicon mapping using energy dispersive X-ray spectroscopy (EDS), that amino-POSS was well dispersed in NC matrix. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) studies showed that hybrid amino-POSS-NC materials have higher thermal decomposition activation energy (Ea) compared to NC control sample. According to TGA results, the temperatures of 5 % weight loss (T5 %) and 50 % weight loss (T50 %) as well as the residual masses at 240 °C (CR240 °C), were increased as a result of NC modification with amino-POSS. As can be seen from the digital and scanning electron microscopy (SEM) images, the char layers of amino-POSS-NC hybrid materials after burning in air became more compact with increasing amino-POSS content. XPS studies have shown an increased content of the graphitized carbon in the char residues of the modified samples. The results of DSC, TGA, SEM and XPS studies have directly proved the enhancement of the thermal stability of amino-POSS-NC hybrid materials. In addition, tensile strengths and Young's moduli of amino-POSS-NC hybrid materials were increased gradually with the amino-POSS content in the uniaxial tensile tests. All these results show that the proposed modification of nitrocellulose improves the safety of manufacture and use of this material.

PL

Poprawa bezpieczeństwa przechowywania nitrocelulozy (NC) wymaga zwiększenia jej stabilności termicznej, a wygoda używania poprawy właściwości mechanicznych. W tym celu zsyntetyzowano materiały hybrydowe, w których NC szczepiono oligomerycznym wielofunkcyjnym aminopropyloizobutylosilseskwioksanem (amino-POSS) stosując jako środek sieciujący izoforonodiizocyjanian (IPDI). Strukturę i skład otrzymanych materiałów potwierdzono za pomocą spektroskopii w podczerwieni z transformatą Fouriera (FT-IR), jądrowego rezonansu magnetycznego (1H NMR i 29SiNMR), dyfraktometrii rentgenowskiej (XRD) oraz spektroskopii fotoelektronów rentgenowskich (XPS). Na podstawie wyników badań mapowania Si, otrzymanych metodą spektroskopii dyspersji energii promieniowania rentgenowskiego (EDS), stwierdzono, że amino-POSS został dobrze zdyspergowany w matrycy NC. Badania stabilności termicznej przeprowadzone za pomocą różnicowej kalorymetrii skaningowej (DSC) wykazały, że materiały hybrydowe typu amino-POSS-NC charakteryzują się większymi wartościami energii aktywacji rozkładu termicznego (Ea) niż próbka kontrolna NC. Zgodnie z wynikami analizy termograwimetrycznej (TGA) wartości temperatury ubytku 5 % (T5 %) i 50% (T50 %) masy próbki oraz pozostałości masy w temperaturze 240 °C (CR240 °C) zwiększały się na skutek modyfikacji NC za pomocą amino-POSS. Według fotografii cyfrowych i fotografii wykonanych metodą skaningowej mikroskopii elektronowej (SEM) warstwy węglowe powstałe po spaleniu materiałów hybrydowych w powietrzu wraz ze zwiększeniem zawartości amino-POSS stawały się coraz bardziej zwarte, a wyniki badań XPS wykazały, że tworzyło się coraz więcej węgla w postaci grafitu. Wszystkie wyniki DSC, TGA, SEM i XPS dowodzą poprawy stabilności termicznej materiałów hybrydowych amino-POSS-NC. Stwierdzono także, że wytrzymałość na rozciąganie i moduł Young'a podczas prób jednoosiowego rozciągania materiałów hybrydowych rosną ze zwiększaniem się zawartości amino-POSS. Wyniki wszystkich przeprowadzonych badań dowodzą, że zaproponowana modyfikacja NC poprawia bezpieczeństwo wytwarzania i użytkowania tych materiałów w porównaniu z niemodyfikowanym NC.

9

Thermal aging of hydrogenated nitrile rubber – loss of additives and its influence on elasticity maintenance

Liu X., Zhao J., Yang R., Iervolino R., Barbera S.

Polimery

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2017

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T. 62, nr 7-8

588--598

EN

The thermal aging of hydrogenated nitrile rubber (HNBR) at elevated temperatures 125 and 150 °C was investigated. The changes of chemical structures, including functional groups and crosslinking density, and the changes of mechanical properties, including recovery from bending (RFB), tensile strength, elongation at break and Young's modulus, were determined. In addition, the loss of additives was analyzed by pyrolysis gas chromatography-mass spectrometry (Py-GC/MS). The aging procedure of HNBR exhibited two stages: loss of additives along with the deterioration of elasticity; obvious oxidation and extra crosslinking with further hardening and embrittlement. The relationship between the deterioration of elasticity and the loss of plasticizers was established. It was demonstrated that the failure of HNBR happened long before obvious oxidation and crosslinking of the rubber chains, and the loss of additives, especially the loss of plasticizers, was the main reason for the failure. Therefore, the elasticity recovery of aged HNBR immersed in the plasticizer (n-propyl palmitate as a model) was carried out. This treatment was demonstrated to be effective before obvious oxidation and crosslinking of HNBR occurred during the thermal aging.

PL

Badano starzenie termiczne uwodornionego kauczuku nitrylowego (HNBR) w temperaturze 125 i 150 °C. Określono zmiany struktur chemicznych, w tym grup funkcyjnych i gęstości usieciowania oraz zmiany właściwości mechanicznych, w tym powrotu poodkształceniowego po zginaniu (RFB), wytrzymałości na rozciąganie, wydłużenia przy zerwaniu i modułu Younga. Ponadto metodą pirolitycznej chromatografii gazowej z detekcją mas (Py-GC/MS) analizowano straty dodatków obecnych w kauczuku. Procedura starzenia się HNBR wykazywała dwa etapy: ubytek dodatków wraz z pogorszeniem elastyczności; wyraźne utlenianie i dodatkowe sieciowanie związane z dalszym utwardzaniem i zwiększaniem kruchości. Określono zależność pomiędzy zmniejszaniem się elastyczności a ubytkiem dodatków zmiękczających. Wykazano, że pogorszenie właściwości HNBR następowało znacznie wcześniej niż utlenianie i sieciowanie oraz było spowodowane utratą dodatków, a zwłaszcza plastyfikatorów. W związku z tym przeprowadzono próbę odtworzenia elastyczności starzonych próbek HNBR przez zanurzenie w plastyfikatorze (palmitynian n-propylu jako model). Obróbka ta okazała się skuteczna, pod warunkiem przeprowadzenia jej zanim podczas starzenia termicznego nastąpiło utlenianie i sieciowanie HNBR.

10

Synergism of octane phenol polyoxyethylene-10 and oleic acid in apatite flotation

Cheng R., Li C., Liu X., Deng S.

Physicochemical Problems of Mineral Processing

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2017

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Vol. 53, iss. 2

1214--1227

EN

The addition of octane phenol polyoxyethylene-10 (OP-10) to oleic acid via a reagent-combination technology was carried out and it was shown that OP-10 exhibited synergistic effects in the flotation performance of oleic acid. Single-mineral flotation tests, zeta-potential measurements, total-organic-carbon determination, and scale-up of continuous tests using raw ore were also carried out. Single-mineral flotation tests showed that OP-10 exhibited virtually no collecting performance for apatite, but it improved the flotation performance of oleic acid following its addition to oleic acid in small amounts at low temperature. Zeta-potential measurements and total-organic-carbon determination results indicated that the addition of 2.5% OP-10 to oleic acid increased the absolute value of the apatite surface potential and improved adsorption of oleic acid on the apatite surface at low temperature. A scale-up of the continuous test showed that application of OP-10 with industrial fatty acids led to good synergistic effects and contributed to effective separation of phosphate ore.

11

Correlation between δ13C and δ15N in flying fish (Exocoetus volitans) muscle and scales from the South China Sea

Wu L., Xu L., Sun J., Wang X., Wei Y., Li Y., Liu X.

Oceanological and Hydrobiological Studies

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2017

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Vol. 46, No. 3

307--313

EN

We collected flying fish (Exocoetus volitans) from the South China Sea to determine whether fish scale isotope values correlate with those from muscle, and discuss relevant eco-environmental implications. A significant positive correlation was determined between fish scales and muscle δ13C and δ15N, rendering a fish scale an alternative to muscle tissue for stable isotope analysis. However, muscle and scale isotopic offsets should be fully considered when using δ13C and δ15N to analyze the actual trophic level of fish and their food source. The average offsets of δ13C and δ15N between muscles and scales are -2.1 ± 0.5‰ and 2.3 ± 0.6‰, respectively, though these values vary slightly with fish mass. Weak correlations were found between δ13C and δ15N, both in the flying fish muscle and scales, suggesting that other factors are influencing δ13C and δ15N. Fish δ15N also correlates with the size of individuals, while δ13C reflects the marine habitat. Based on our data, it appears that more eco-environmental processes can be revealed from modern or ancient flying fish scales.

12

Influence of Bi3+ content on photoluminescence of InNbO4:Eu3+,Bi3+ for white light-emitting diodes

Tang A., Gu L., Shao F., Liu X., Zhao Y., Chen H., Zhang H.

Materials Science Poland

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2017

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Vol. 35, No. 2

435--439

EN

A series of red-emitting phosphors InNbO4:Eu3+,Bi3+ was prepared by a high temperature solid-state reaction. The structure, size distribution and luminescence properties of the phosphors were respectively characterized by X-ray diffraction (XRD), laser particle size and molecular fluorescence spectrometer. The XRD results indicate that the phase-pure samples have been obtained and the crystal structure of the host has not changed under the Eu3+ and Bi3+ co-doping. The test of size distribution shows that the phosphor has a normal size distribution. The excitation spectra illustrate that the dominant sharp peaks are located at 394 nm (7F0→5L6) and 466 nm (7F0→5D2). Meanwhile, the emission spectra reveal that the phosphors excited by the wavelength of 394 nm or 466 nm have an intense red-emission line at 612 nm owing to the 5D0→(7F2 transition of Eu3+. Bi3+ doping has not changed the peak positions except the photoluminescence intensity. The emission intensity is related to Bi3+ concentration, and it is up to the maximum when the Bi3+-doping concentration is 4 mol%. Due to good photoluminescence properties of the phosphor, the InNbO4:0.04Eu3+,0.04Bi3+ may be used as a red component for white light-emitting diodes.

13

Research on Knitted Fabric Properties of Yak Cashmere and Cotton Blend Yarns

Qin X., Liang H., Wang G., Su X., Liu X.

Fibres & Textiles in Eastern Europe

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2017

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Vol. 25, no. 4 (124)

31--35

EN

As a natural fibre, yak cashmere has attracted more and more attentions in textile processing due to its excellent properties, environmentally friendly characteristics and inexpensive prices. However, the direct processing of yak cashmere, especially pure yarn spinning, is difficult since the dispersion of the fibre length is large. Therefore, in this paper, yak cashmere and cotton blend yarns were spun. Compact Sirospun yarns with three different kinds of blending ratios; 70/30, 50/50 and 30/70, were spun, and corresponding spun yarn qualities: hairiness, breaking strength and evenness were tested. It is shown that with an increasing content of cotton, for the same yarn count spun, all properties tested were improved. Then the properties of corresponding knitted fabric, including the permeability, thickness, static voltage, warmth retention, whiteness, water permeability, bursting strength, elastic recovery, tensile properties, drape, wear resistance, pilling, anti-ultraviolet resistance and bending stiffness were measured and comparatively analysed. It is shown that with an increasing content of yak cashmere, the fabric is lighter and thinner, and the air permeability, warmth retention, wear resistance and pilling were all improved, while the strength and elongation properties as well as water permeability were worsened. Meanwhile the average weight distribution of yak cashmere and cotton in the yarn is beneficial for the fabric elastic recovery property and drape.

PL

Jako włókno naturalne, kaszmir przyciąga coraz więcej uwagi w przemyśle tekstylnym dzięki doskonałym właściwościom, przyjaznym dla środowiska cechom i niewysokim cenom. Jednakże bezpośrednie przetworzenie kaszmiru jakowego, a zwłaszcza przędzenia przędzy, jest trudne, ze względu na duży rozrzut długości włókien. Z tego powodu w przedstawionej pracy wytworzono przędze bawełniano-kaszmirowe o trzech różnych proporcjach: 70/30, 50/50 i 30/70. Wykazano, że wraz ze wzrastającą zawartością bawełny, badane właściwości tj. włochatość, wytrzymałość na rozerwanie i równomierność uległy polepszeniu. Zbadano także właściwości otrzymanych dzianin tj. przepuszczalność powietrza, grubość, napięcie statyczne, ciepłochronność, stopień bieli, przepuszczalność wody, wytrzymałość na rozerwanie, odprężenie, właściwości mechaniczne podczas rozciągania, układalność, odporność na ścieranie, pilling, oporność na promieniowanie ultrafioletowe i sztywność zginania. Wykazano, że wraz z rosnącą zawartością kaszmiru dzianiny są lżejsze i cieńsze, a przepuszczalność powietrza, ciepłochronność, odporność na ścieranie uległy poprawie, natomiast właściwości wytrzymałościowe i przepuszczalność wody uległy pogorszeniu.

14

Effects of Optimal Mordanting on the Bleaching and Spinning of Black Yak Fibres

Liu C., Su X., Xie C., Liu X.

Fibres & Textiles in Eastern Europe

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2017

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Vol. 25, no. 5 (125)

31--36

EN

In this paper, the orthogonal analysis method was adopted to analyse the optimal mordanting condition for the bleaching of black yak fibres. Without changing the subsequent oxidative/reducing bleaching technology, the optimal mordanting condition was as follows: per weight of water, the ferrous ion concentration is 16%, the sodium bisulfate concentration 3 g/l, the mordanting temperature 60 °C and the liquor pH value is 2. Based on the optimal mordanting condition, yak fibres were bleached. The properties of bleached and untreated yak fibres and yarns were tested by a fibre tensile tester, scanning electron microscopy, yarn strength tester, USTER Tester 5 and so on. By comparing the properties of untreated and bleached yak fibres and yarns, the effects of optimal mordanting on the bleaching and spinning of black yak fibres were presented. The results show that bleached yak fibres have poorer mechanical and morphology properties, and it is harder to felt for bleached fibres. For the spinning of 16.7 tex yarn, a complete condensing spinning system was adopted, and the performances of bleached fibre yarn decreased in the permissible range compared with the untreated fibre yarn.

PL

W celu określenia optymalnych warunków procesu zaprawiania włókien z wełny jaków zastosowano metodę analizy ortogonalnej. Określono optymalne parametry procesu zaprawiania tj.: stężenie jonu żelazawego na poziomie 16%, stężenie wodorosiarczanu sodu w ilości 3 g/l, temperaturę na poziomie 60 °C, a wartość pH roztworu na poziomie 2. Następnie włókna poddano procesowi bielenia. Oceniono właściwości mechaniczne włókien oraz dokonano analizy powierzchni włókien za pomocą SEM. Wyniki wykazały, że włókna poddane procesowi bielenia mają słabsze właściwości mechaniczne i morfologiczne. Do wytworzenia przędzy 16,7 tex zastosowano kompletny system przędzenia, a wydajność przędzenia przędzy bielonej zmniejszyła się w dopuszczalnym zakresie w porównaniu z przędzą nie poddaną obróbce.

15

Effects of hole-perpendicularity error on joint stiffness of single-lap double-bolt composite joints

Liu X., Yang Y., Gao H., Bao Y., Li R., Chen L.

Engineering Transactions

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2017

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Vol. 65, iss. 2

289--305

EN

To investigate the influence of hole-perpendicularity error on stiffness of single-lap doublebolt composite joints, a finite element model was first created and validated by using the analogical mass-spring based model proposed by McCarthy et al. The model was then modified by introducing hole-perpendicularity error, with which the influences of hole-perpendicularity error, which is represented by hole-titling angle, hole-tilting direction, and bolt torque on the joint stiffness are studied. It is found that the hole-tilting direction causes the joint stiffness to either increase or decrease, which depends on the relation between the hole-tilting direction and the loading orientation. In addition, the hole-tilting angle strengthens the influence of hole-tilting direction and the bolt torque plays the most important role among the three factors in affecting the joint stiffness.

16

Optimized design of a high-power-density PM-assisted synchronous reluctance machine with ferrite magnets for electric vehicles

Liu X., Li Y., Liu Z., Ling T., Luo Z.

Archives of Electrical Engineering

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2017

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Vol. 66, nr 2

279--293

EN

This paper proposes a permanent magnet (PM)-assisted synchronous reluctance machine (PMASynRM) using ferrite magnets with the same power density as rareearth PM synchronous motors employed in Toyota Prius 2010. A suitable rotor structure for high torque density and high power density is discussed with respect to the demagnetization of ferrite magnets, mechanical strength and torque ripple. Some electromagnetic characteristics including torque, output power, loss and efficiency are calculated by 2-D finite element analysis (FEA). The analysis results show that a high power density and high efficiency of PMASynRM are obtained by using ferrite magnets.

17

New observations on wear mechanism of self-reinforced SiAlON ceramic tool in milling of Inconel 718

Hao Z. P., Fan Y. H., Lin J. Q., Ji F. F., Liu X.

Archives of Civil and Mechanical Engineering

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2017

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Vol. 17, no. 3

467--474

EN

Self-reinforced SiAlON ceramic tool materials, due to its unique properties such as high wear resistance, high hardness and low affinity with metal, is widely used in machining nickel-based alloy. The self-reinforced SiAlON ceramic tool was used in the experimental process of high speed milling nickel-based alloy Inconel718. The results obtained through observing the tool wear morphology and further analysis showed that when cutting speed vc = 50–200 m/min, abrasive wear and lamellar spalling was the main cause of tool wear. When cutting speed vc = 350, 500 m/min, the bond strength between β-SiAlON whisker and SiAlON matrix reduced, and then the tool material fell off, which led to the formation of hole and groove. When the hole and groove mark connected, the crack nucleation formed. The crack propagation resulted in fracture eventually. At last, according to the tool wear mechanism, tool wear model was established and the optimal cutting temperature range, which can lead to minimum tool wear in milling Inconel718 using self-reinforced SiAlON ceramic tool, was obtained.

18

The Response of Wetland Plant Communities to Disturbance : Alleviation through Symmetric Disturbance and Facilitation

Xu F., Li M., Zhou D., Liu X., Wang R., Guo W.

Polish Journal of Ecology

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2016

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Vol. 64, nr 3

327--338

EN

The study pays attention to disturbances in early successional communities of wetland vegetation. We conducted artificial disturbances in a community of Suaeda salsa and Phragmites australis in the Yellow River Delta (China). Eight types of disturbances combining mowing treatments with species treatments were applied. Removal of the standing litters of P. australis or not was defined as mowing treatments, and removal of two species solo or both was defined as species treatments. We sampled 80 quadrats from the treatments plots at different intervals after the disturbance to investigate plant height, abundance, aboveground biomass, the distance between plants to reflect the effect of disturbance on composition, structure, productivity, and function of the plant communities. The strategies of seedling emergence and height growth differed as the canopy changed. Biomass contribution of different species, combined with disturbance intensity, was the main factors that affected the productivity. Homogeneity of disturbance was better for maintaining the functions of plant community in compared with the competitiveness (C), stress-tolerance (S) and ruderality (C-S-R) signatures with the control. Facilitations were reflected by the stagger arrangements in relative growth rates of the two species and in plant-plant interactions calculated by a modified function of competition. Adapting to symmetric disturbance and developing facilitative interactions are important requirements for early succession terrestrial vegetation to establish and stabilize in the seriously saline environments of wetlands.

19

Generation of cyber-security reinforcement strategies for smart grid based on the attribute-based attack graph

Zhang B., Li Q., Zhang Y., Liu X., Ni Z.

Journal of Power Technologies

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2016

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Vol. 96, nr 3

170--177

EN

A smart grid is a kind of energy cyber-physical system (ECPS) with the interdependency of information and physicality. A cyber-attack gravely threatens the safe and stable operation of a physical power grid. Cyber-security reinforcement of smart grid has become a research issue. However, the information network scale of a smart grid is massive, and the generation of security reinforcement strategies has become a problem. Therefore, a generation method of security reinforcement strategies based on an attribute-based attack graph was proposed in this study. The method defined a smart grid based on premise and consequence attributes to form an attribute-based attack graph. With this graph, the method for the generation of security reinforcement strategies was transferred to the minimum dominating set of the attribute-based attack graph and solved to realize space reduction in the security reinforcement strategies. An algorithm for the generation of security reinforcement strategies was designed based on the greedy algorithm, and strategies for large-scale cyber security reinforcement of the smart grid were determined to eliminate the complexity and difficulty of this problem effectively. Through a simulation analysis of a large-scale node network, the efficiency of the generation method of reinforcement strategies based on the attribute based attack graph and minimum dominating set was verified. Results show that the proposed method can be used for security reinforcement of large-scale complicated networks of a smart grid.

20

Theoretical Study of the Effects of the General Division of a Ring Spinning Triangle on Fibre Tension

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

Fibres & Textiles in Eastern Europe

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2016

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Vol. 24, no. 2 (116)

37--43

EN

The geometry of a spinning triangle influences the distribution of fibre tension in it and affects the qualities of spun yarns. Spinning triangle division is one of the most effective measures and fruitful results have been achieved, such as Solospun technology. Therefore a theoretical study of the effects of general ring spinning triangle division on fibre tension is presented in this paper. The general case that the spinning triangle is divided into m parts including m - 1 parts of the primary triangle and one final triangle is investigated and two series of parameters: division proportions b i and triangle number at each part ni are introduced for i = 1, 2, ..., m - 1. Firstly a theoretical model of the fibre tension distributions at the front roller nip is given by using the principle of minimum potential energy. Secondly numerical simulations of fibre tension distributions in the spinning triangle with different division proportions b 1, b 2 and different numbers of primary triangles n1, n2 where m = 3 are presented. It is shown that the demarcation of fibre tension between any two adjacent primary triangles in the first part is decreased with an increasein b 1 or b 2 for the fixed n1 and n2. Meanwhile, for the fixed b 1 and b 2, the total magnitude of fibre tension is increased greatly with an decrease in n1, whereas it rises slightly with an increase in n2. Finally the effects of spinning triangle division on yarn qualities are analysed according to the numerical simulations and previous results.

PL

Geometria trójkąta skrętu ma wpływ na rozkład naprężeń włókien w trójkącie przędzenia i wpływa również na właściwości przędzy. Przędzalniczy podział trójkąta przędzenia jest jednym z bardziej skutecznych sposobów zmniejszenia naprężeń i daje owocne rezultaty. przeprowadzono teoretyczne rozważania dotyczące skutków podziału trójkąta skrętu na naprężenia włókien. W ogólnym przypadku założono, że trójkąt przędzenia został podzielony na m części. Analiza przeprowadzonych badań wykazała, że naprężenie pojedynczych włókien w podzielonym trójkącie skrętu może być określone poprzez naprężenie przędzenia, liczbę podzielonych części, liczbę pierwotnych trójkątów w każdej części, proporcję podziału, moduł sprężystości początkowej włókien (modułu Younga), przekrój poprzeczny, oraz szerokość i wysokość trójkąta skrętu w przędzeniu obrączkowym. Uwzględniając numeryczne symulacje oraz wcześniejsze rezultaty, przeanalizowano skutki wpływu podziału trójkąta skrętu w przędzeniu obrączkowym na jakość przędzy. Badania wykazały, że odpowiedni (właściwy) podział trójkąta skrętu może korzystnie wpłynąć na jakość przędzy.