Wyniki wyszukiwania - BazTech

1

Prediction and validation for the aerodynamic noise of high-speed train power car

Jiang S., Yang S., Wu D., Wen B-Ch.

Transport Problems

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2018

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T. 13, z. 2

91--102

EN

The aerodynamic noise of high-speed train power car was investigated in this article. The full-scale power car was first modeled, and the external steady flow field was computed by a realizable k-ε turbulence model. The aerodynamic noise sources of the power car surface and the external transient flow field were then calculated by broadband noise source model and large eddy simulation (LES) model, respectively. The static pressures on the train surface were obtained from the results of the transient model. Considering the transient flow field, the far-field aerodynamic noise generated by the power car was finally derived from Lighthill-Curle theory. It was validated by means of on-line tests that have been performed along a real high-speed railway line. Through comparisons between simulations and measurements, it is shown that the simulation model gives reliable aerodynamic noise predictions. We foresee numerous applications for modeling and control of the aerodynamic noise in high-speed train.

2

Experiment on pressure characteristics of submerged floating tunnel with different section types under wave condition

Li Q., Jiang S., Chen X.

Polish Maritime Research

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2018

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S 3

54--60

EN

Submerged floating tunnel (SFT for short) is a special underwater traffic structure, and wave load is one of the main environmental loads of SFT structure. In this paper, the 1:60 physical model test of three kinds of SFT in a two-dimensional wave flume is tested. The effects of random irregular waves on the SFT structure under different wave heights and periods are discussed. The study shows that: (1) Compared with circular and polygonal sections, there are multiple local peaks in the elliptical section during the period. with the increase of wave height, the number of local peaks also increases. It suggests that the rotational moment plays an important role in the elliptical section which has a relatively small depth-width ratio. (2) The position of the maximum and minimum pressure in the three kinds of SFT sections is consistent. Their vertical wave forces are all larger than their horizontal wave forces. The increase of vertical wave force relative to horizontal wave force in polygon section is larger than that in elliptical section, and the difference in the circular section is the smallest. (3) Under the same traffic condition, the wave force of the elliptical and polygon section is smaller, but they are more sensitive to the change of wave height, and the increase is obvious. The distribution of wave force in the circular section is more uniform.

3

Development of a Larix principis-rupprechtii tree-ring width chronology and its climatic signals for the southern Greater Higgnan Mountains

Zhang T., Yu S., Yuan Y., Huang L., Jiang S.

Geochronometria

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2018

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Vol. 45, no. 1

1--9

EN

Forty-one living larch (Larix principis-rupprechtii) trees collected from two sampling sites in 1310–1530 m a.s.l. in the southern Greater Higgnan Mountains in the northeastern China are used to develop a regional tree-ring width chronology. The credible chronology spans 185 years from 1830 to 2014. The results of correlation analyses indicate that moisture is the main climatic factor controlling radial growth of larch trees in this mountainous area. Spatial correlation proves that the regional tree-ring width chronology contains climatic signals representative for a large area including the eastern Mongolian Plateau and Nuluerhu Mountains. A comparison between the newly developed chronology and a May–July Palmer Drought Severity Index (PDSI) reconstruction for the Ortindag Sand Land reveals similar variations, particularly in the low-frequency domain. The tree-ring records also capture a severe and sustained drying trend recorded in the 1920s across a wide area of northern China.

4

Fabrication and Characterization of Photochromic Spirooxazine/Polyvinylidene Fluoride Fiber Membranes via Electrospinning

Peng L., Guo R., Lan J., Jiang S.

Fibres & Textiles in Eastern Europe

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2018

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Vol. 26, no. 4 (130)

34--38

EN

In this study, photochromic spirooxazine material of N-methyl-3,3-dimethyl-9'-hydroxy-spiro[2H-indole-2-[3H] naphtho [2,1-b] [1,4] oxazine] was synthesised. Spirooxazine/PVDF fiber (SPF) membranes with different contents ofspirooxazine were successfully prepared by electrospinning. The SPF membranes were characterised by FTIR and SEM.The photochromic properties and contact angle of the SPF membranes were evaluated. The results show that the SPF membranes change from colorless to blue whenexposed to UV light, but they revert to their original colour after the UV light disappears. The colour difference and contact angle of the SPF membranes firstly increase and then decrease with a rise in the content of spirooxazine.

PL

W pracy otrzymano fotochromowy materiał spirooksazynowy N-metylo-3,3-dimetylo-9'-hydroksy-spiro [2H-indolo-2 - [3H] nafto [2,1-b] [1,4] oksazyny]. Za pomocą elektroprzędzenia wytworzono membrany z spiroksaksyny i fluorku poliwalildanu PVDF (SPF) o różnej zawartości spiroksaksyny. Błony SPF scharakteryzowano za pomocą FTIR i SEM. Oceniono właściwości fotochromowe i kąt zwilżania błon SPF. Wyniki pokazały, że membrany SPF zmieniają kolor z bezbarwnego na niebieski po ekspozycji na światło UV, ale powracają do swojego pierwotnego koloru po zaniku światła UV. Różnica barwy i kąt zwilżania membran SPF najpierw wzrastają, a następnie zmniejszają się wraz ze wzrostem zawartości spirooksazyny.

5

Comparison of compressive strength and electrical resistivity of cementitious composites with different nano- and micro-fillers

Jiang S., Zhou D., Zhang L., Ouyang J., Yu X., Cui X., Han B.

Archives of Civil and Mechanical Engineering

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2018

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Vol. 18, no. 1

60--68

EN

Cementitious composites with 0–1.5 wt.% Nano-SiO2 (NS), nano-TiO2 (NT), carbon nanotubes (CNTs), carbon nanofibers (CNFs) and carbon microfibers (CFs) are fabricated and tested. The enhancing effects of different fillers on the compressive strength and electrical resistivity of composites are compared, and the underlying modification mechanisms of fillers to composites are investigated by analyzing the difference in the morphology of fillers and rheology of composites. The compressive strength of composites containing 0.1% NS, 0.5% NT, 0.1% CNTs and 0.5% CFs by weight of cement presents approximately 12.5%, 20.8%, 16.8% and 21.4% higher than that of control sample, respectively. It is revealed that CFs also have improving effect on the compressive strength of composites besides flexural strength. When the composites with nano-fillers cannot be processed to ideal state, the reinforcing effect of nano-fillers is no better but even worse than that of micro-fillers. Composites with CNTs, CNFs and CFs possess good electrical conductivity. Composites with CNFs and CFs have a percolation threshold of electrical resistivity below 0.5%, while the percolation threshold of electrical resistivity of composites with CNTs is about 1%. Although CNFs do not have significant effect on compressive strength of composites, they have the best improvement to electrical resistivity.

6

Small Universal Spiking Neural P Systems with Homogenous Neurons and Synapses

Wu T., Wang Y., Jiang S., Shi X.

Fundamenta Informaticae

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2016

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Vol. 149, nr 4

451--470

EN

Spiking neural (SN, for short) P systems are a class of distributed parallel computing models inspired by the way in which neurons communicate with each other by means of electrical impulses. Recently, a new variant of SN P systems, called SN P systems with homogenous neurons and synapses (HRSSN P systems for short) was proposed, where the spiking and forgetting rules are placed on synapses instead of in neurons and each synapse has the same set of spiking and forgetting rules. This variant of SN P systems has already been proved to be Turing universal as both number generating and accepting devices. In this work, we consider the problem of looking for small universal HRSSN P systems. Specifically, a universal HRRSN P system with standard rules and weight at most 5 having 70 neurons is constructed as a device of computing functions; as a number generator, we find a universal system with standard rules and weight at most 5 having 71 neurons.

7

Unidirectional Torsion Properties of Single Silk Fibre

Jiang S., Cao G., Cai G., Xu W., Li W., Wang X.

Fibres & Textiles in Eastern Europe

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2016

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Vol. 24, no. 3 (117)

26--30

EN

The unidirectional torsion properties of silk fibre were investigated on a purpose-built single fibre torsion tester. The torsional fracture angle and the number of cycles of torsion at breaking were recorded, and the effect of the gauge length and pretension together with the torsion speed on the torsion properties of single silk fibre was investigated in detail. Scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis and a tensile tester were used to understand the morphology, structure and tensile properties of silk fibre after torsion deformation. SME photos show that silk fibre exhibits a ribbon-like profile after torsion, and fracture tends to occur at both ends of the silk fibre, where a larger number of twists can be observed. The crystallinity calculated from XRD spectra of silk fibre increases from 26.11% to 34.10% after torsion. The breaking stress and strain decreases slightly with an increase in the gauge length. The breaking cycle increases linearly with an increase in the gauge length, while the actual torsional fracture angle decreases gradually at the same time. The torsional fracture angle together with the breaking cycle decreases gradually as the pretension increases. The fracture angle together with the breaking cycle increases with an increase in the torsion speed. Understanding the unidirectional torsion properties of single silk fibre will benefit its further application in specific areas where the fibre will be subject to frequent torsion and deformation.

PL

Badania przeprowadzono za pomocą specjalnie zbudowanego urządzenia do badania skrętu włókien. Badano kąt przełomu oraz ilość cykli doprowadzających do zerwania. Sprawdzano również wpływ długości próbki oraz wstępnego naprężenia. Oceniono wpływ długości próbki wstępnego naprężenia, szybkości skrętu na właściwości wytrzymałościowe włókien jedwabnych. Stosowano SEM, XRD dla określenia morfologii i struktury włókien. Stwierdzono, że włókna jedwabne po badaniu wykazują formę podobną do taśmy. Na podstawie XRD stwierdzono, że krystaliczność wzrasta od ok. 26% do 34% po skręceniu. Naprężenie zrywające i odkształcenia zmniejszają się lekko przy wzroście długości próbki.

8

Influence of composition on the structure and properties of SrO-Sb2O3-P2O5 low-melting sealing glasses

Nie H., Zhang J., Qi Y., Wang Z., Lin H., Jiang S.

Materials Science Poland

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2015

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Vol. 33, No. 4

862--866

EN

SrO-Sb2O3-P2O5 glass system was prepared by high temperature melting method. The effects of Sb2O3 and P2O5 content on the structure, thermal behavior and chemical durability of the glasses were studied by infrared spectrometer, thermal dilatometer, differential thermal analyzer and constant temperature water bath heating. It can be concluded that the characteristic temperatures of the glasses increased firstly and then decreased with the increasing of Sb2O3 content, whereas the tendency of the coefficient of thermal expansion (CTE) varied inversely. The crystallization ability of the glasses was significantly increased and the water resistance was reduced for Sb2O3 content of 35 mol % and 40 mol %. The glasses with 20 mol %, 25 mol % and 30 mol % Sb2O3 showed better performance in every respect than the others and the glasses containing 25 mol % Sb2O3, characterized by the best performance, can be chosen as host glasses for further research.

9

Study of structures and properties of ZnO-Sb2O3-P2O5-Na2O glasses

Qi Y., Wang Z., Zhai S, Jiang S., Lin H.

Materials Science Poland

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2014

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Vol. 32, No. 3

414--418

EN

The influence of ZnO substitution by 0 – 12 wt.% Na2O on the properties of ZnO–Sb2O3–P2O5–Na2O glasses has been investigated. The structure and properties of the glasses with the composition of (13.86–x)ZnO–57.93Sb2O3–28.21P2O5-xNa2O (x = 0 – 12 wt.%) were characterized by infrared spectra (IR), X-ray diffraction and differential thermal analysis (DTA). The results of IR indicated an increase in the intensity of symmetric vibrations of P–O–P bond, which was confirmed by the improvement of water durability with the increasing amount of Na2O in the range of 0 – 10 wt.%. Substitution of 10 wt.% Na2O led to the weight loss of the glass to 5.93 mg/cm-2 after immersion in deionized water at 50 °C for 24 h. The results of XRD showed that the ability of crystallization decreased, indicating the good thermal stability of the glass. The glass containing 8 wt.% Na2O had the best properties in every respect and might be an alternative to lead based glasses for the applications, providing further composition improvement.

10

Development of a two stroke direct injection jet ignition compressed natural gas engine

Boretti A., Jiang S.

Journal of Power Technologies

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2014

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Vol. 94, nr 3

145–-152

EN

A traditional two stroke engine with crankcase scavenging also adopting an exhaust reed valve and lamellar intake is modified to accommodate a high pressure Compressed Natural Gas (CNG) direct injector and has the traditional spark plug replaced by a jet ignition device of the same thread. The jet ignition device is a pre-chamber accommodating a Gasoline Direct Injection (GDI) injector operated with CNG and an 8 mm racing spark plug. The jet ignition pre-chamber is connected to the main chamber through calibrated orifices. The CNG is injected after the exhaust post closes. The GDI injector operated with CNG introduces a slightly rich amount of fuel in the pre-chamber. The spark plug discharge initiates the pre-chamber combustion that then propagates to the main chamber though multiple jets of high energy partially burned hot combustion products that quickly ignite the main chamber mixtures. The Computer Aided Design (CAD) model of the engine including the jet ignition device is discussed in detail. The Computer Aided Engineering (CAE) model of the engine is shown to produce efficiencies well in excess of 35% in the area of best operation. The load is controlled by fine tuning the injection and ignition events and increasing the overall air-fuel ratio. The solution offers an opportunity to produce an efficient alternative to four stroke engines with improved power density, running on alternative fuel having larger availability and better combustion properties and reduced pollution than traditional diesel and gasoline fuels.

11

Hollow fiber-based liquid phase microextraction combined with high performance liquid chromatography for determination of flavonoids in Ginkgo biloba and urine

Lu H., Wang X., Liu X., Jiang S.

Chemia Analityczna

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2009

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Vol. 54, No. 3

309-319

EN

A hollow fibre membrane-based liquid phase microextraction (HF-LPME) method for determination of flavonoids in Ginkgo biloba leaves was developed. Three flavonoids: quercetin, kaempferol, and isorhamnetin were extracted and then analysed by high performance •-:; liquid chromatography. The factors affecting HF-LPME, including concentration of donor ,; and acceptor phases, concentration of NaCl, extraction time, and stirring speed were systematically investigated. Under the optimum conditions, calibration plots of reasonable linearity were constructed in the analyte's concentration range of 10-100 μg L-1. Up to 200-fold enrichment factor for quercetin and up to tens of folds for kaempferol and isorhamnetin ' were obtained. The method was applied to determine the concentrations of flavonoids in urine and was proven to be an convenient sample preparation technique.

PL

Opracowano metodę oznaczania flawonoidów w liściach Ginkgo biloba za pomocą ^ mikroekstrakcji z fazy ciekłej przy użyciu membranowego wydrążonego włókna. Ekstra-howano i analizowano trzy flawonoidy: kwercetynę, kempferol i izorhamnetynę stosując wysokosprawną chromatografię cieczową. Systematycznie zbadano następujące czynniki wpływające na mikroekstrakcję: stężenie donora i akceptora, stężenie NaCl, czas ekstrakcji oraz szybkość mieszania. W optymalnych warunkach uzyskano liniowy wykres krzywej kalibracji w zakresie stężenia analitu od l O do 100 μg L-1. Współczynnik zatężenia wynosił do 200 razy w przypadku kwercetyny i do dziesiątek razy w przypadku kempferolu oraz izorhamnetyny. Opracowaną metodę zastosowano do oznaczania zawartości flawonoidów w moczu. Stwierdzono, że metoda jest odpowiednia do przygotowywania próbek.

12

Separation and quantification of flavonoid compounds in Rhododendron anthopogonoides Maxim by high-performance liquid chromatography

Zhao L., Ge J., Qiao C., Zhangi H., Jiang S.

Acta Chromatographica

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2008

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Vol. 20, no. 1

135-146

EN

A high-performance liquid chromatographic (HPLC) method has been developed for separation and quantitative analysis of flavonoid aglycones in Rhododendron anthopogonosides Maxim. Flavonoids in their bound forms were hydrolyzed with acid before HPLC analysis. Analytical samples were pretreated by solid-phase extraction on C18 reversed-phase cartridges. Optimum separation on a 4.6 mm × 250 mm i.d. C18 column was achieved by use of a 52:48 (v/v) mixture of methanol and an aqueous solution of 10 mm citric acid and 1 mm sodium dodecyl sulfate as mobile phase. The flow rate was 1.0 mL min-1 and the detection wavelength 360 nm. Five flavonoids, myricetin, quercetin, luteolin, kaempferol, and isorhamnetin, were separated with high resolution without use of gradient elution. The method was successfully used for efficient qualitycontrol analysis by quantifying flavonoids in R. anthopogonosides. Repeatability tests showed that intra-day and inter-day RSD was <10%. LOD of the five flavonoids were <0.85 µg mL-1. Recovery ranged from 90.2 to 112.5%, with RSD <11.1%.

13

HPLC analysis of flavonoids in Lamiophlomis rotata

Luo M., Ma H., Liu X., Jiang S.

Acta Chromatographica

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2008

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Vol. 20, no. 2

247-257

EN

A simple and precise high-performance liquid chromatographic (HPLC) method has been developed for analysis of flavonoids in Lamiophlomis rotata. HPLC conditions were optimized. Baseline separation was achieved by use of a binary gradient prepared from 100:0.2 (v/v) water-trifluoroacetic acid (component A), and acetonitrile (component B). The gradient was from 20 to 35% B in 10 min, hold at 35% B for 20 min, then from 35 to 70% B in 10 min. The injection volume was 10 µL, and the detection wavelength was 366 nm. Linearity and precision were investigated. When normal leastsquares linear regression (LSLR) was compared with weighted least-squares linear regression (WLSLR), values obtained by use of the latter were much closer to the actual values, over the whole range of concentration, than those obtained by use of the former. WLSLR was therefore used in this work. This HPLC method was successfully used for analysis of the flavonoids in Lamiophlomis rotata and could be effective for quality control of the plant.

14

Determination of chloramphenicol residues in honey by monolithic column liquid chromatography-mass spectrometry after use of quechers clean-up

Pan C., Zhang A., Chen S., Xu Y., Jiang S.

Acta Chromatographica

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2006

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No. 17

320-327

EN

An HPLC method with a monolithic column and detection by mass spectrometry has been established for determination of chloramphenicol in honey samples previously cleaned by use of a modification of the QuEChERS procedure. Honey samples were dissolved in water containing sodium chloride and extracted with acetonitrile. Further sample clean-up was performed by simple reversed-solid-phase dispersion with primary–secondary amine (PSA) adsorbent. Chloramphenicol (CAP) residues at ppb concentrations were detected by liquid chromatography–mass spectrometry (LC–MS), with electrospray ionization, in negative-ion mode. The mobile phase was methanol–0.2% aqueous ammonium acetate solution, 45:55 (v/v). Under these conditions CAP is eluted after ∼4 min and 8 min from a Merck RP-18e monolithic column and a conventional C18 column, respectively. Recovery at three fortification levels (0.2, 20, and 200 µg kg.1) was in the range 78–93% with RSD from 3.7 to 3.9%. The coefficient of determination, R2, was 0.9995 over a 0.1–100 µg L.1 linear range. Use of this method for determination of CAP in honey resulted in an LCL of 0.20 µg kg.1. The method was validated on the basis of EU decision 2002/657. CCá and CCâ for the honey matrix were 0.002 and 0.006 µg kg.1, so the method was fit for the purpose of monitoring commercial products or checking MRL compliance.