Wyniki wyszukiwania - BazTech

1

Fifth-generation bike-sharing systems: examples from Poland and China

Chen F., Turoń K., Kłos M., Czech P., Pamuła W., Sierpiński G.

Zeszyty Naukowe. Transport / Politechnika Śląska

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2018

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z. 99

05--13

EN

The article is focused on sustainable transport development solutions in cities, such as bike-sharing systems. We discuss the main principles of bike-sharing, its generations, types, and benefits to system users and entire urban transport systems. The aim of the article is to present a comparison of bike-sharing systems found in Polish and Chinese cities. The authors also consider new market practices, which can be implemented when introducing or improving current bike-sharing systems.

2

Picea schrenkiana tree-ring chronologies development and vegetation index reconstruction for the Alatau Mountains, Central Asia

Zhang T., Zhang R., Lu B., Mambetov B. T., Kelgenbayev N., Dosmanbetov D., Maisupova B., Chen F., Yu S., Shang H., Huang L.

Geochronometria

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2018

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Vol. 45, no. 1

107--118

EN

In this study, a total of 176 tree cores from Schrenk spruce (Picea schrenkiana) were used to establish a tree-ring chronology and a 167-year July–October normalized differential vegetation index (NDVI) for the Alatau Mountains in Central Asia was reconstructed using this newly developed chronology. The tree-ring based NDVI reconstruction tracks the observed data well (r=0.577, p<0.01, n=25) and precisely captures the drought events recorded in historical documents that occurred over a large area in 1917 and 1938. After applying a 21-year moving average, three dense (1860–1870, 1891–1907, and 1950–1974) and three sparse (1871–1890, 1908–1949, and 1975–2006) vegetation coverage periods were found in this reconstruction. Spatial correlation proves that the reconstructed NDVI series contains climatic signals representative for a large area including southern Kazakhstan. Although a comparison between this reconstruction and four climatic reconstructions for southeastern Kazakhstan, Nilka (in the Ili region), the Issyk Lake, and the Aksu region reveals similar variations, the coherence between these reconstructions become weak with the increase in spatial distance from north to south. In addition to the local representation, it was also demonstrated that the newly developed NDVI index can indicate the large-scale circulations over Eurasia, with the higher NDVI associated with stronger westerly winds from the Atlantic to the Alatau Mountains, and the lower NDVI associated with the weaker winds.

3

Determination of the aglycon moieties of glycosidically bound compounds in Flos Chrysanthemi by GC × GC–TOFMS

Zhou Y., Huang G., Li X., Chen F., Liu H., Yang Y., Fan Z., Jiang J., Yang J.

Acta Chromatographica

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2018

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Vol. 30, no. 3

195--199

EN

A credible method for determination of the aglycon moieties of glycosidically bound aroma compounds in Flos Chrysanthemi by comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry (GC × GC–TOFMS) has been proposed. The aglycon moieties of glycosidically bound aroma compounds were isolated using methyl-tert-butyl ether (MTBE) extraction following enzymatic hydrolysis. The GC × GC–TOFMS analysis was performed to comprehensively identify different forms of the released aroma components in Flos Chrysanthemi. The result shows that the limit of detection of the released aglycon moieties ranged from 0.3 to 3.1 ng/mL, the recovery of the released 1-octanol was better than 98.3%, and the intra-day and inter-day precisions of this method were 0.2 to 8.9% and 1.3 to 9.1%, respectively. The proposed method was applied to the analysis of four types of Flos Chrysanthemi (Chuju, Boju, Hangju, and Gongju). A total of 60 aglycon moieties of interest were identified in the four types of Flos Chrysanthemi. These aglycones mainly consisted of aliphatic, aromatic, monoterpene, C13-norisoprenoids, and miscellaneous compounds.

4

A simple HPLC method for the determination of butorphanol tartrate and ondansetron hydrochloride in patient-controlled analgesia solution

Fang B., Wang L., Chen F., Li P., Shi X.

Acta Chromatographica

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2018

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Vol. 30, no. 1

43--46

EN

A simple and rapid high-performance liquid chromatographic (HPLC) method was established for simultaneous determination of butorphanol tartrate and ondansetron hydrochloride in analgesic mixture samples used for patient-controlled analgesia (PCA). The separation of butorphanol tartrate and ondansetron hydrochloride in PCA solution was carried out on phenomenex C18 column (4.6 mm × 150 mm, 5 μm) using 50 mM sodium acetate (pH 4.0) buffer and acetonitrile (72:28, v/v). Flow rate was 1.0 mL min−1 with a column temperature of 30 °C, and detection wavelength was carried out at 280 nm and 306 nm. Validation of the method was made in terms of specificity, linearity, accuracy, and intra- and inter-day precision, as well as quantification and detection limits. The developed method was successfully used to evaluate the chemical stability of butorphanol tartrate and ondansetron hydrochloride in analgesic mixtures at the usual concentration used for PCA.

5

Microstructure and dielectric properties of La2O3 doped Ti-rich barium strontium titanate ceramics for capacitor applications

Zhang C., Chen F., Ling Z., Jian G., Li Y.

Materials Science Poland

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2017

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Vol. 35, No. 4

806--815

EN

Microstructure and dielectric properties of La2O3 doped Ti-rich barium strontium titanate ceramics, prepared by solid state method, were investigated with non-stoichiometric level and various La2O3 content, using XRD, SEM and LCR measuring system. With an increase of non-stoichiometric level, the unit cell volumes of perovskite lattices for the single phase Ti-rich barium strontium titanate ceramics increased due to the decreasing A site vacancy concentration V″A. The unit cell volume increased and then decreased slightly with the increasing La2O3 content. Relatively high non-stoichiometric level and high La2O3 content in Ti-rich barium strontium titanate ceramics contributed to the decreased average grain size as well as fine grain size distribution, which correspondingly improved the temperature stability of the relative dielectric constant. The relative dielectric constant єrRT, dielectric loss tanδRT and the maximum relative dielectric constant єrmax decreased and then increased with the increasing non-stoichiometric level. With the increase of La2O3 doping content, the relative dielectric constant єrRT increased initially and then decreased. The maximum relative dielectric constant єrmax can be increased by applying low doping content of La2O3 in Ti-rich barium strontium titanate ceramics due to the increased spontaneous polarization.

6

Isolation and purification of two tyrosinase inhibitors from camellia pollen by high-speed counter-current chromatography

Yang Y.-F., Lai X.-Y., Huang G.-L., Chen Y.-H., Du X.-P., Jiang Z.-D., Chen F., Ni H.

Acta Chromatographica

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2017

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Vol. 29, no. 4

477--483

EN

Bee pollen is a health food with a wide range of nutritional and therapeutic properties. However, the bioactive compounds of bee pollen have not been extensively revealed due to low efficacy in separation. High-speed counter-current chromatography (HSCCC) and solvent extraction were applied to separate tyrosinase inhibitors from camellia pollen in this study. The camellia pollen extracts prepared with petroleum ether, ethyl acetate, and n-BuOH have tyrosinase inhibitory activity. Acidic hydrolysis could promote the tyrosinase inhibitory activity of crude sample. Three fractions with tyrosinase inhibitory activity were separated from the hydrolysate by a one-step HSCCC procedure. Among the fractions, two chemicals were sufficiently purified and identified to be levulinic acid (LA) and 5-hydroxymethylfurfural (5-HMF). The recovery was 0.80 g kg -1 pollen for LA and 1.75 g kg -1 pollen for 5-HMF; and their purity was all over 98%. The study demonstrates that HSCCC method is powerful for preparative separation of tyrosinase inhibitors from camellia pollen.

7

An On-Line Method for Thermal Diffusivity Detection of Thin Films Using Infrared Video

Dong H., Zheng B., Chen F.

Metrology and Measurement Systems

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2016

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Vol. 23, nr 1

59--70

EN

A novel method for thermal diffusivity evolution of thin-film materials with pulsed Gaussian beam and infrared video is reported. Compared with common pulse methods performed in specialized labs, the proposed method implements a rapid on-line measurement without producing the off-centre detection error. Through mathematical deduction of the original heat conduction model, it is discovered that the area s, which is encircled by the maximum temperature curve rTMAX(θ), increases linearly over elapsed time. The thermal diffusivity is acquired from the growth rate of the area s. In this study, the off-centre detection error is avoided by performing the distance regularized level set evolution formulation. The area s was extracted from the binary images of temperature variation rate, without inducing errors from determination of the heat source centre. Thermal diffusivities of three materials, 304 stainless steel, titanium, and zirconium have been measured with the established on-line detection system, and the measurement errors are: −2.26%, −1.07%, and 1.61% respectively.

8

Tree-Ring Response to Snow Cover and Reconstruction of Century annual Maximum Snow Depth for Northern Tianshan Mountains, China

Qin L., Yuan Y., Zhang R., Wei W., Yu S., Fan Z., Chen F., Zhang T., Shang H.

Geochronometria

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2016

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Vol. 43, no. 1

9--17

EN

Heavy snowfall and extreme snow depth cause serious losses of human life and property in the northern Tianshan Mountains almost every winter. Snow cover is an important indicator of climate change. In this study, we developed five tree-ring-width chronologies of Schrenk spruce (Picea schrenkiana Fisch. et Mey) from the northern Tianshan Mountains using standard dendrochronological methods. Correlation analyses indicated that radial growth of trees in the northern Tianshan Mountains is positively affected by annual maximum snow depth. This relationship was validated and models of annual maximum snow depth back to the 18th century were developed. The reconstruction explains 48.3% of the variance in the instrumental temperature records during the 1958/59–2003/04 calibration periods. It indicates that quasi-periodic changes exist on 2.0–4.0-yr, 5.3-yr, 14.0-yr, and 36.0-yr scales. The reconstructed series shows that maximum snow depth exhibits obvious stages change, the periods characterized by lower maximum snow depth were 1809/10–1840/41, 1873/74– 1893/94, 1909/10–1929/30, 1964/65–1981/82, and the periods characterized by higher maximum snow depth were 1841/42–1872/73, 1894/95–1908/09, 1930/31–1963/64, and 1982/83–present. The lower period of annual maximum snow depth during the 1920s–1930s is consistent with the severe drought that occurred at this time in northern China. From the 1970s to the present, the maximum snow depth has increased clearly with the change to a warmer and wetter climate in Xinjiang. The reconstruction sheds new light on snow cover variability and change in a region where the climate history for the past several centuries is poorly understood.

9

A review of void formation and its effects on the mechanical performance of carbon fiber reinforced plastic

Liu X., Chen F.

Engineering Transactions

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2016

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Vol. 64, iss. 1

33--51

EN

Carbon fiber reinforced plastic (CFRP) is ideal for high performance of mechanical properties. However, during the manufacturing process of CFRP, defects or flaws can easily be introduced into the material, among which void is the most common one. Many factors contribute to the formation of void including the curing pressure, resin system, environmental conditions and so on, some of which are almost unavoidable. The presence of voids results in a reduction of the mechanical properties of CFRP, which has been the subject of many researchers for several decades. The aim of this paper is to summarize state-of-the-art studies on void formation and its effects on the mechanical properties of CFRP.

10

Tree-ring based temperature reconstruction for the west Qinling Mountains (China): linkages to the High Asia, solar activity and Pacific-Atlantic Ocean

Chen F., Yuan Y., Wei W., Yu S., Shang H., Zhang T., Zhang R., Wang H., Qin L.

Geochronometria

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2014

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Vol. 41, no. 3

234--244

EN

We developed a Faxon fir (Abies faxoniana) tree-ring width chronology at the timberline in the western Qinling Mountains, China. Herein February–July mean temperature was reconstructed for Zhouqu in the western Qinling Mountains back to AD 1650 based on the standard chronology. The climate/tree-growth model accounts for 43.5% of the instrumental temperature variance during the period 1972–2006. Spatial correlation analyses with the gridded temperature data shows that the tem-perature reconstruction captures regional climatic variations over central and southeast China, and strong teleconnections with the nearby High Asia. There is a good agreement with cold and warm pe-riods previously estimated from tree-rings in Nepal, India and southwest China. The temperature re-construction indicates that there was pronounced cooling in Zhouqu during the Maunder Minimum (late 1600s to early 1700s). The cold period (1813–1827) of the temperature reconstruction coincide with the volcanic eruptions. Significant spectral peaks are found at 56.9, 22.3, 11.4, 2.9, 2.8, 2.6, 2.2 and 2.0 years. The spatial correlation patterns between our temperature reconstruction and SSTs of the Atlantic and Pacific Oceans suggest a connection between regional temperature variations and the atmospheric circulations. It is thus revealed that the chronology has enough potential to reconstruct the climatic variability further into the past.

11

Extraction of Discriminative Patterns from Skeleton Sequences for Accurate Action Recognition

Thanh T. T., Chen F, Kotani K., Le B.

Fundamenta Informaticae

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2014

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Vol. 130, nr 2

247--261

EN

Emergence of novel techniques devices e.g., MS Kinect, enables reliable extraction of human skeletons from action videos. Taking skeleton data as inputs, we propose an approach to extract the discriminative patterns for efficient human action recognition. Each action is considered to consist of a sequence of unit actions, each of which is represented by a pattern. Given a skeleton sequence, we first automatically extract the key-frames, and then categorize them into different patterns. We further use a statistical metric to evaluate the discriminative capability of patterns, and define them as local features for action recognition. Experimental results show that the extracted local descriptors could provide very high accuracy in the action recognition, which demonstrate the efficiency of our method in extracting discriminative unit actions.

12

The effect of surface functional groups of nanosilica on the properties of polyamide 6/SiO2 nanocomposite

Xu Q., Chen F., Li X., Zhang Z.

Polish Journal of Chemical Technology

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2013

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Vol. 15, nr 3

20-24

EN

The present study investigated the effect of the surface functional groups of nanosilica on the interfacial, crystallization, and thermal stability of polyamide 6/SiO2 (PA6/SiO2) nanocomposite, in which nanosilica was modified in situ with both 3-triethoxysilylpropylamine and 3-methacryloxypropyltrimethoxy silane¬ (KH-550 and KH-570). The FTIR analysis results showed the chemical bonding action between the reacting amino groups of nanosilica and end carboxyl groups of polyamide 6 enhanced with increasing the ratio of KH-550 and KH-570. The XRD spectrum indicated that the crystal structure of PA6/SiO2 nanocomposites tended to form α crystal type that was beneficial to an improvement of mechanical properties, and which was in agreement with the results of mechanical strength measurements. It was also found that crystallization temperature and crystallization rate of PA6/SiO2 nanocomposites were lower than that of neat polyamide 6.

13

Spectral degrees of cross-polarization of stochastic anisotropic electromagnetic beams in modified non-Kolmogorov atmospheric turbulence

Chen F., Chen J., Zhao Q., Chen Y, Xin Y., Li J., Pan H.

Optica Applicata

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2013

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Vol. 43, nr 4

773--783

EN

Based on the extended Huygens–Fresnel principle, variations in generalized Stokes parameters of stochastic anisotropic electromagnetic beams propagating through modified non-Kolmogorov atmospheric turbulence have been analyzed. The changes in generalized Stokes parameters with different turbulence parameters and source parameters were analyzed first. After that, the distributions of the spectral degrees of cross-polarization (SDCP) of isotropic beams and anisotropic beams were simulated. The results show that the profiles of distribution of SDCP of these two kinds of beams are very different in the near field, and will fluctuate through the propagation in atmospheric turbulence, but at last, when the propagation distance is long enough, the difference in the source makes a slight difference in the final profiles of SDCP in the output plane. They mainly depended on the turbulence perturbation, and in the weak turbulence, the profiles of final distribution show more flatter features.

14

Generalized Stokes parameters of random electromagnetic quasi-homogeneous beams on propagation

Chen J, Xin Y, Chen Y, Chen F, Zhao Q

Optica Applicata

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2013

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Vol. 43, nr 2

s. 205--216

EN

The expressions for the elements of the on-axis and transverse generalized Stokes parameters of random electromagnetic quasi-homogeneous beams on propagation are presented and are used to study the polarization properties of the beams. Some typical numerical calculations of the on-axis and transverse Stokes parameters, polarization properties of the beams on propagation are illustrated. The results show that for different sources all the on-axis parameters are identical in the near field and keep fixed values in the far field. But the transverse parameters are affected greatly by the properties of the source even in the near field. We have also found that the spatial profiles of the transverse parameters remain unchanged upon propagation.

15

Investigations on the degree of bleaching of quartz OSL signals using modern aeolian dust from western Loess Plateau, China

Fan T., Fan Y., Zhao H., Chen F., Lai Z.

Geochronometria

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2013

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Vol. 40, no. 3

165--176

EN

Optically Stimulated Luminescence signal of quartz extracted from modern aeolian dust with known maximum age (about decades) was analyzed in terms of degree of bleaching. The results of dose recovery tests show that the modified double single-aliquot regenerative-dose protocol with the early background subtraction is robust for dating these modern dusts using small aliquots. Bleach-ing of these dusts is discussed based on the distribution of De values in histograms, scatter plots of De versus sensitivity corrected natural OSL signal and comparison between measured De and expected De. The results indicate that most dusts were completely bleached but some dusts were not completely bleached. For those incompletely bleached dusts in Lanzhou area, the maximum OSL age overestimation is up to ~1 ka, which might be caused by fast deposition accompanied by heavy sand/dust storms. The research suggests that cautions should be given to OSL ages younger than 1 ka in the western China close to deserts.

16

Decomposition and Approximation of Loopy Bayesian Networks

Dong J., Chen F., Huo Y., Liu H.

Fundamenta Informaticae

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2013

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Vol. 125, nr 2

135--152

EN

This paper proposes a new method, conditional probability table (CPT) decomposition, to analyze the independent and deterministic components of CPT. This method can be used to approximate and analyze Baysian networks. The decomposition of Bayesian networks is accomplished by representing CPTs as a linear combination of extreme CPTs, which forms a new framework to conduct inference. Based on this new framework, inference in Bayesian networks can be done by decomposing them into less connected and weighted subnetworks. We can achieve exact inference if the original network is decomposed into singly-connected subnetworks. Besides, approximate inference can be done by discarding the subnetworks with small weights or by a partial decomposition and application of belief propagation (BP) on the still multiply-connected subnetworks. Experiments show that the decomposition-based approximation outperforms BP in most cases.

17

Reliability analysis of machining center based on the field data

Yang Z. J., Chen Ch. H., Chen F., Hao Q. B., Xu B. B.

Eksploatacja i Niezawodność

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2013

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Vol. 15, no. 2

147-155

EN

Machining center is the complex machinery, with high level automation and complicated structures, so there are lots of failures. When a random failure occurs, the failed machining center stops and causes a production line or even the whole workshop to stop functioning. The frequent failure leads to the low levels of reliability and production rate. In order to help users and manufacturers optimize maintenance policy to improve the reliability for machining center, this paper presents descriptive statistics of the failure data and develops the failure trend using power-law process, simultaneously establishes the routine inspection and regular inspection as well as the sequential preventive maintenance under maintenance cost constraints. The proposed model could be a useful tool to assess the current conditions, predict reliability and optimize the machining center maintenance policy.

PL

Centrum obróbkowe to skomplikowany mechanizm o wysokim poziomie automatyzacji oraz złożonej konstrukcji, w związku z czym ulega licznym uszkodzeniom. Przy wystąpieniu przypadkowej awarii, uszkodzone centrum obróbkowe przestaje działać i powoduje zatrzymanie linii produkcyjnej a nawet całego oddziału produkcyjnego. Częste awarie obniżają poziom niezawodności oraz tempo produkcji. Aby pomóc użytkownikom i producentom zoptymalizować politykę utrzymania ruchu w celu poprawy niezawodności centrów obróbkowych, w niniejszym artykule przedstawiono statystyki opisowe dotyczące danych o uszkodzeniach i opracowano trend uszkodzeń w oparciu o proces spełniający prawo potęgowe. Jednocześnie ustalono zasady rutynowej inspekcji i okresowych przeglądów, jak również sekwencyjnej obsługi zapobiegawczej przy ograniczonych wydatkach na utrzymanie ruchu. Proponowany model może być użytecznym narzędziem dla potrzeb oceny aktualnych warunków oraz przewidywania niezawodności w celu optymalizacji polityki utrzymania ruchu centrum obróbkowego.

18

Research on Solutions for Implement of Active Distribution Network

You Y., Liu D., Yu N., Pan F., Chen F.

Przegląd Elektrotechniczny

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2012

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R. 88, nr 12a

238-242

EN

Nowadays, distribution systems are facing the challenge to accommodate increasing quantities of Distributed Energy Resources (DERs), especially based on the intermittent renewable sources. So it is inevitable for distribution systems shifting from passive mode to active mode. This paper discusses some important issues for implementation of active distribution network (ADN) which is capable of allowing high penetration of renewable resources together with optimal operation by its flexible network, including planning for active distribution network considering renewable energy uncertainties, fully utilization of large scale intermittent renewable energy and active network management (ANM). Accordingly, some solutions are proposed to meet requirements of implement of active distribution network, basing on the issues aforementioned.

PL

W artykule omówiono zagadnienie implementacji aktywnej sieci przesyłowej, z naciskiem na wysoki poziom wykorzystania odnawialnych źródeł energii (OZE) poprzez zapewnienie elastyczności sieci. Przedstawiono rozwiązania dotyczące niestabilności generowanej przez OZE energii, optymalizacji pracy, maksymalnego wykorzystania generowanej energii oraz zarządzania siecią aktywną.

19

Research on Damage Mechanism of SCB Initiators under RF

Chen F., Zhou B., Qin Z, Shen R.

Przegląd Elektrotechniczny

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2012

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R. 88, nr 11a

188-190

EN

In order to elucidate the response characteristic of semiconductor bridge(SCB) initiators under radio frequency(RF), RF measurement system was used to test the RF sensitivity of SCBs, after that the energy stored in a 22?F was used to activate the SCB. It is inferred from the results of Bruceton-method firing experiment that RF energy does not damage the SCB chip, but can lead to the accidental ignition of SCB initiators or change the color of normal lead styphnate(NLS). RF can also passivate SCB significantly and the all-fire voltage increases from 6.71V to 7.72V. The experimental data of X-ray photoelectron spectroscopy(XPS) analysis, directly indicated that heat generated by RF changes the valence of Pb in NLS from +2 to +4. The decomposition of NLS is responsible for the loss in sensitivity of SCBs. The research results provide a theoretical guidance for the electromagnetic compatibility(EMC) design of SCB initiators.

PL

W artykule opisano badanie oddziaływania sygnałów częstotliwości radiowej (ang. Radio Frequency) na zapalniki zbudowane z mostka półprzewodnikowego. Przedstawiono omówienie teoretyczne oraz wyniki badań eksperymentalnych.

20

Research of Integrated Control Methods and its Simulation for Freeway Mainline and Related Ramp

Chen F., Jia Y., Li J.

Przegląd Elektrotechniczny

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2012

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R. 88, nr 1b

119-122

EN

To relieve traffic congestion during peak hours on freeways, various ramp metering models have been attempted for regulation of the inputs to freeway from entry ramps. Integrated control is a new development to find the combination of control measures for the best road performance and control effectiveness. In consideration of some weaknesses of current intelligent metering, this study proposes an innovative concept and associated local ramp metering approach. From results of a comparative case study with real world traffic flow data in Beijing, the new Intelligent control approach of freeway mainline and related ramp that is proven to significantly output from traditional models, particularly in regards to its effectiveness in minimizing the waiting time of multiple cycles.

PL

W artykule przeanalizowano słabości obecnie stosowanych metod do kontroli przepełnienia w czasie ruchu drogowego i zaproponowano nowa metodę oceny zwalniania tego ruchu. Zaproponowano też inteligentne metody kontroli tego ruchu w tym wjazdu na autostrady.