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1

Defect solitons supported by kagome photonic lattices in biased photovoltaic-photorefractive crystals

Hui J., Lu K., Zhao C., Gao L., Chen W.

Optica Applicata

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2018

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Vol. 48, nr 3

349--359

EN

We report that defect solitons can be supported by kagome photonic lattices with a defect in biased photovoltaic-photorefractive crystals. For a positive defect, these defect solitons exist only in the semi-infinite bandgap and are stable in the low power region but unstable in the high power region. For a negative defect, these defect solitons exist in both of the semi-infinite bandgaps and the first bandgap. In the semi-infinite bandgap, low-power defect solitons are stable when the negative defect depth is low and unstable when the negative defect depth is high, moderate-power defect solitons are stable when the negative defect depth is high, and high-power defect solitons are unstable for all the negative defect depths. In the first bandgap, defect solitons are stable in all the power regions when the negative defect depth is low. When the negative defect depth is high, defect solitons are stable in the high power region and unstable in the low power region. On the other hand, these defect solitons are those studied previously in kagome photonic lattices with a defect in biased non-photovoltaic-photorefractive crystals when the bulk photovoltaic effect is negligible and those in kagome photonic lattices with a defect in photovoltaic-photorefractive crystals when the external bias field is absent.

2

Simultaneous removal of SO2 and NOx from sintering flue gas using ammonia-Fe(II)EDTA combined with electrolytic regeneration

Liang Y., Yao X., Quin L., Chen W., Han J.

Environment Protection Engineering

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2018

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Vol. 44, nr 2

19--36

EN

Sulfur dioxide and nitrogen oxide are health hazardous gases, which contribute to the formation of submicron acidic particulates. To reduce SO2 and NOx emission from the sintering flue gas, the combination of ammonia-Fe(II)EDTA solution scrubbing with Fe(III) electrolytic regeneration is proposed. The above method has the following advantages: direct conversion of NOx and SO2 to harmless N2 and SO4 2−, recovery of the by-product (NH4)2SO4), simultaneous removal of NOx and SO2 emission from flue gas in the reactor. The effect of the pH, initial Fe(II)EDTA concentration, and voltage on the desulfurization and denitration efficiencies was investigated using a bench-scale reactor. The maximal desulfurization and denitration efficiencies were 98% and 52%, respectively. The optimum parameters were pH ˃ 5.0, 2.1 V, and 0.05 mol·dm–3 Fe(II)EDTA concentration. SO2 and NOx removal from the sintering flue gas by ammonia-Fe(II)EDTA solution scrubbing combined with electrolytic regeneration was also demonstrated in a pilot-scale reactor.

3

Generalized Stockwell transform and SVD-based epileptic seizure detection in EEG using random forest

Zhang T., Chen W., Li M.

Biocybernetics and Biomedical Engineering

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2018

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Vol. 38, no. 3

519--534

EN

Purpose: Visual inspection of electroencephalogram (EEG) records by neurologist is the main diagnostic method of epilepsy but it is particularly time-consuming and expensive. Hence, it is of great significance to develop automatic seizure detection technique. Methods: In this work, a seizure detection approach, synthesizing generalized Stockwell transform (GST), singular value decomposition (SVD) and random forest, was proposed. Utilizing GST, the raw EEG was transformed into a time–frequency matrix, then the global and local singular values were extracted by SVD from the holistic and partitioned matrices of GST, respectively. Subsequently, four local parameters were calculated from each vector of local singular values. Finally, the global singular value vectors and local parameters were respectively fed into two random forest classifiers for classification, and the final category of a testing EEG was voted based on sub-labels obtained from the trained classifiers. Results: Four most common but challenging classification tasks of Bonn EEG database were investigated. The highest accuracies of 99.12%, 99.63%, 99.03% and 98.62% were achieved using our presented technique, respectively. Conclusions: Our proposed technique is comparable or superior to other up-to-date methods. The presented method is promising and able to handle with kinds of epileptic seizure detection tasks with satisfactory accuracy.

4

Development and validation of UPLC–MS/MS method for determination of eupatilin in rat plasma and its application in a pharmacokinetics study

Geng P., Luo X., Peng X., Lin Z., Chen W., Zhang J., Wen C., Hu L., Hu S.

Acta Chromatographica

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2018

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Vol. 30, no. 4

231--235

EN

Eupatilin, mainly derived from Artemisia asiatica (Asteraceae), is an O-methylated flavone with various bioactivities. In the present study, a validated ultra-performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) method was established for the quantification of eupatilin in rat plasma with the internal standard (IS) of tussilagone and the protein precipitation of plasma samples was performed using acetonitrile–methanol (9:1, v/v). The eupatilin and IS were eluted separately on a UPLC BEH C18 column (2.1 mm × 100 mm, 1.7 μm) with the gradient mobile phase consisted of 0.1% formic acid and acetonitrile. The protonated analytes were quantified by multiple reactions monitoring (MRM) mode with an electrospray ionization (ESI) source operated in positive ion mode. The calibration plots were found to be linear over the range from 2 to 1000 ng/mL for eupatilin in rat plasma. Both of the intra-day and inter-day precision variations (RSDs) were ≤13%. The recoveries of eupatilin in rat plasma were between 83.7% and 94.6%, and the accuracy of the method ranged from 95.8% to 107.6%. In addition, the validated method was applied to pharmacokinetic study of eupatilin after an intravenous dose of 2 mg/kg to rats.

5

Optimized design and analysis of offshore Beidou maritime foundation reinforcement system pseudolite ranging-codes

Su D., Zhou A., Zhou Z., Chen W.

Polish Maritime Research

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2017

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S 2

45--52

EN

Under the bad sea conditions and weak Beidou navigation signal environment, it is difficult to locate the ship on the sea, and the Beidou navigation system can’t work well. Beidou pseudolite system can improve the performance of Beidou navigation system as a navigation signal transmitter fixed on the ground, the signal of which can improve satellite positioning constellation structure, and improve the system availability reliability and precision. In order to ensure the interoperability and non-correlation of the Beidou pseudolite and the Beidou navigation system, the pseudolite ranging-codes should be selected in the same code space of the satellite ranging-codes and the residual pseudo random code generated by the 2 taps design scheme does not satisfy the performance requirements of the ranging-codes. To solve this issue, a combined design scheme with 3 taps is proposed, and 12 kinds of pseudolite ranging-codes are optimally selected according to the optimum design parameters of ranging-codes. The waveform and correlation of the selected pseudolite ranging-codes are analyzed by MATLAB, the acquisition simulation is carried out by using the new pseudolite ranging-codes. The experimental results show that the new 3-taps based ranging codes design scheme behaves a good balance, correlation and spectral characteristics.

6

Enhancing SO2 removal efficiency by lime modified with sewage sludge in a novel integrated desulfurization process

Qin L., Han J., Chen W., Liu Z., He M., Xing F.

Environment Protection Engineering

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2017

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Vol. 43, nr 4

17--27

EN

In China, the sintering process annually emitted around 1.5 million t SO2, representing 70% of SO2 produced from the iron and steel industry. Lime based sorbent was modified with municipal sewage sludge (MSS) and the influence of the modification on the desulfurization efficiency was investigated in a laboratory-scale novel integrated desulfurization (NID) reactor. The properties of modified sorbent were characterized by the Brunauer–Emmett–Teller (BET) analyzer and X-ray fluorescence (XRD) analyzer. BET surface area was increased from 17.48 to 46.68 m2g–1. when the MSS/lime ratio increased from 0 to 0.08. Ca4Al8Si8O32, Ca1.5SiO3.5, Na2Si2O5 and CaSiO3 found in the modified lime benefited for the increase of the BET surface area and pore volume. The effects of sewage sludge/CaO weight ratio, calcination temperature and hydration time on the desulfurization efficiency were also studied. SO2 removal efficiency was increased from 88.7% to 97.3% after using the lime modified with sewage sludge.

7

Application of MODWT and log-normal distribution model for automatic epilepsy identification

Li M., Chen W., Zhang T.

Biocybernetics and Biomedical Engineering

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2017

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Vol. 37, no. 4

679--689

EN

In this paper, a novel approach based on the maximal overlap discrete wavelet transform (MODWT) and log-normal distribution (LND) model was proposed for identifying epileptic seizures from electroencephalogram (EEG) signals. To carry out this study, we explored the potentials of MODWT to decompose the signals into time-frequency sub-bands till sixth level. And demodulation analysis (DA) was investigated to reveal the subtle envelope information from the sub-bands. All obtained coefficients were then used to calculate LDN features, scale parameter (s) and shape parameter (m), which were fed to a random forest classifier (RFC) for classification. Besides, some experiments have been conducted to evaluate the performance of proposed model in the consideration of various wavelet functions as well as feature extractors. The implementation results demonstrated that our proposed technique has yielded remarkable classification performance for all the concerned problems and outperformed the reported methods in terms of the universality. The major finding of this research is that the proposed technique was capable of classifying EEG segments with satisfied accuracy and clinically acceptable computational time. These advantages have make our technique an attractive diagnostic and monitoring tool, which helps doctors in providing better and timely care for the patients.

8

Numerical test on polystyrene tunnel seismic-isolation material

He J., Chen W., Zhao W., Huang S., Yao Y.

Polish Journal of Chemical Technology

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2016

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Vol. 18, nr 3

122--127

EN

Stress-strain mechanical properties of polystyrene foam plastic material were tested under different loading conditions. An empirical constitutive model for describing metal materials was proposed for the polystyrene plastic foam. The static and dynamic tests results show that the ductility and watertightness of the polystyrene plastic foam are significantly improved. At the same time, in order to check its seismic-isolation property, the high-performance foam concrete as filling materials of Galongla tunnel in Tibet was simulated by FEM. The simulated results show that the polystyrene plastic foam can remarkably decrease the stress and the plastic zone in final lining, so it can effectively reduce the seismic damage of the tunnel. Considering the seismic-isolation property and low price of polystyrene plastic foam, it is a good reference for the anti-seismic design of tunnels in high intensity zones.

9

Method for improving sinusoidal quality of error diffusion binary encoded fringe used in phase measurement profilometry

Tian Z., Chen W., Su X.

Optica Applicata

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2016

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Vol. 46, nr 2

291--303

EN

Insufficient resolution of digital-light-processing projector will degrade the sinusoidal quality of the binary encoded fringe pattern because of less sampling points in a fringe period, which will degrade the measurement accuracy if it is used in phase measurement profilometry. Two resolutions are proposed in the paper. One is that a cylindrical lens is introduced in the projecting light path of the measurement system to improve sinusoidal quality of the binary encoded fringe by elliptical low-pass filtering of the system. The other one is that superposition of multi-frame binary encoded gratings with different microstructure is to reduce the binary image noise for improving the measurement accuracy. Simulations and experiments verify the validity of the above two methods.

10

Electrostatic Hazards Assessment of Nitramine Explosives: Resistivity, Charge Accumulation and Discharge Sensitivity

Peng Q., Cao W., Zhou W., He Z., Jiang W., Chen W.

Central European Journal of Energetic Materials

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2016

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Vol. 13, no. 3

755--769

EN

The electrostatic hazards of nitramine explosives (RDX, HMX) were assessed in this paper. The resistivities of different particle-size RDX and HMX were tested by a device designed and manufactured according to the standard ISO/IEC 80079-20-2:2016. This work shows that the resistivities of uncompacted RDX and HMX increase as the particle size decreases. Charging characteristics test experiments were also carried out using a so-called sieve method. Using this method, the influence of aperture size on charge accumulation of RDX was studied, and the characteristics of electrostatic accumulation of different particle-size RDX and HMX sieved with 50 mesh standard sieve were compared. The results show that the absolute value of the charge accumulation increases as the mesh number increases (i.e. the aperture size decreases), and increases as the particle size is decreased, indicating that nano-sized RDX and nano-sized HMX accumulate static electricity more easily than conventional micron-sized ones. Finally, the electrostatic discharge (ESD) sensitivity of nano-sized RDX and nano-sized HMX was investigated. Nano-sized nitramine explosives were found to have a higher ESD sensitivity than micron-sized ones.

11

Automatic epilepsy detection using wavelet-based nonlinear analysis and optimized SVM

Li M., Chen W., Zhang T.

Biocybernetics and Biomedical Engineering

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2016

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Vol. 36, no. 4

708--718

EN

Aiming at the problems of low accuracy, poor universality and functional singleness for seizure detection, an effective approach using wavelet-based non-linear analysis and genetic algorithm optimized support vector machine (GA-SVM) is proposed to deal with five challenging classification problems in this study. Instead of the traditional discrete wavelet transform (DWT), we attempt to explore the ability of double-density discrete wavelet transform (DD-DWT) to decompose the original EEG into specific sub-bands. The Hurst exponent (HE) and fuzzy entropy (FuzzyEn) are extracted as input features and then fed into two classifiers. On using these ranking non-linear features, the GA-SVM configured with fewer features is found to achieve the prominent classification performance for various combinations such as AB-CD-E, A-D-E, ABCD-E, C-E and D-E, achieving accuracies of 99.36%, 99.60%, 99.40%, 100% and 100%, respectively. The results have indicated that our scheme is not only appropriate in solving problems with multiple classes but also of lower complexity and better expansibility. These characteristics would make this method become an attractive alternative for actual clinical diagnosis.

12

Privacy Issues in SOAP Message Exchange Pattern for Social Services

Chen W., Paik I., Hung P. C. K.

Fundamenta Informaticae

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2015

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Vol. 137, nr 2

253--271

EN

A Web service is defined as an autonomous unit of application logic that provides either some business functionality or information to other applications through an Internet connection. Web services are based on a set of eXtensible Markup Language (XML) standards such as Universal Description, Discovery and Integration (UDDI), Web Services Description Language (WSDL), and Simple Object Access Protocol (SOAP). NowadaysWeb services are becoming more and more popular for supporting different social applications, thus there are also increasing demands and discussions aboutWeb services privacy protection in information. In general, privacy policies describe an organization’s data practices on what information they collect from individuals (e.g., consumers) and what (e.g., purposes) they do with it. To enable privacy protection for Web service consumers across multiple domains and services, the World Wide Web Consortium (W3C) published a document called “Web Services Architecture (WSA) Requirements” that defines some specific privacy requirements for Web services as a future research topic. This paper presents a mathematical model to construct the privacy policies in SOAP Message Exchange Patterns (MEP) for social services. Further, this paper also presents the privacy policies in security tokens with SOAP messages.

13

Phase change of chlorite in reducing atmosphere

Liu X., Yu Y., Chen W., Liu X.

Physicochemical Problems of Mineral Processing

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2014

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Vol. 50, iss. 2

607--614

EN

Magnetizing roasting is an important pre-treatment technique for beneficiation of hematite and limonite ores. Reduction mechanisms of these iron minerals have been fully studied while the mechanism of reduction of chlorite is not well understood. In this study, a reduction roasting study examining the phase change of chlorite with roasting temperature was undertaken. The major finding from this study was that chlorite partially was reduced to magnetite by carbon at 750 ⁰C, and the newly formed magnetite was finely disseminated within quartz and olivine. It was demonstrated that these locked magnetite particles would be reported to iron concentrate by low intensity magnetic separation resulting in high impurity content, especially SiO2 and Al2O3 contents in the concentrate.

14

Virtual Physics Framework for Multi-Robot Chemical Plume Tracing under Ventilated Indoor Condition

Zou Y., Chen W., Luo D.

Przegląd Elektrotechniczny

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2013

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R. 89, nr 5

92-99

EN

This paper presents a virtual-physics based control framework for swarm robotic chemical plume tracing and source localization problem under ventilated indoor environment with complex turbulent conditions. The control force includes three kinds of effort, which are lattice formation force, plume tracing force, and obstacle avoidance force. The plume tracing and source identify strategy are based on the chemical mass flux passing through the robot colony. Simulation results show that the proposed control framework and tracing strategy can effectively navigate the multi-robot system to the chemical source emitter region. The virtual-physics based framework is highly flexible, endows the robot formation the properties of self-organization and self-repair. Compare to traditional approaches, the mass flux driven plume tracing can inhibit the robots from adhering to the obstacle-induced local density maxima and guide the robots forward to the real source region.

XX

W artykule opisano metodę śledzenia smugi dymu chemicznego przy wykorzystaniu robotów oraz metodę wykrywania źródła dymu w pomieszczeniu wentylowanym przy zawirowaniu powietrza. Stosowane są trzy środki – określenie siatki, śledzenie dymu i eliminacja zjawiska. Roboty śledzące mogą się same organizować i naprawiać. W porównaniu do innych metod zaproponowana metoda zabezpiecza roboty przed zatrzymaniem się przy lokalnym maksimum i prowadzi je do źródła dymu.

15

Integrated design of observer based fault detection for a class of uncertain nonlinear systems

Chen W., Khan A, Q., Abid M., Ding S. X.

International Journal of Applied Mathematics and Computer Science

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2011

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Vol. 21, no 3

423-430

EN

Integrated design of observer based Fault Detection (FD) for a class of uncertain nonlinear systems with Lipschitz nonlinearities is studied. In the context of norm based residual evaluation, the residual generator and evaluator are designed together in an integrated form, and, based on it, a trade-off FD system is finally achieved in the sense that, for a given Fault Detection Rate (FDR), the False Alarm Rate (FAR) is minimized. A numerical example is given to illustrate the effectiveness of the proposed design method.

16

Ustalanie pozycji i naprowadzanie maszyn mikrotunelowych w czasie rzeczywistym

Shen X., Lu M., Chen W., Chan W.

Inżynieria Bezwykopowa

|

2010

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nr 1

54-60

PL

Rosnące zapotrzebowanie na podziemną infrastrukturę lepszej jakości i w większej ilości, w tym na instalację, konserwację i wymianę różnego rodzaju rur i kabli, przyczyniło się do szybkiego rozwoju i rosnącego wykorzystania technologii bezwykopowych w XX wieku. Zaawansowane tarcze drążące oraz maszyny służące do drążenia mikrotuneli pozwalają uzyskać większą kontrolę nad trasą i poziomem tunelu, a także przyczyniają się do przyspieszenia procesu drążenia Maszyny mikrotunelowe znalazły szerokie zastosowanie przede wszystkim w różnorodnych projektach obejmujących przeciskanie rur i drążenie mikrotuneli.

EN

Micro Tunnel Boring Machines (MTBM) have seen wide applications in pipe jacking and microtunnelling projects. Accurate MTBM positioning and attitude measurement are crucial to guiding the MTBM's advance, controlling line and level of the subsurface tunnel, and tracking MTBM's production progress. In this paper, we first evaluate pros and cons of available MTBM guidance systems. Our evaluation covers prevalent passive and active laser targeting systems for short and straight drives, along with gyroscope-based inertial navigation systems specifically designed for curve drive. We then propose a real-time, automated solution to MTBM guidance by application of state-of-the-art robotic total stations.

17

Gas temperature measurements using wavelength modulation spectroscopy at 1.39 žm

Cai T., Tan T., Wang G., Chen W., Gao X.

Optica Applicata

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2009

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Vol. 39, nr 1

13--29

EN

Gas temperature measurements in a combustion system by using wavelength modulation spectroscopy 2f ratio of two selected transitions method were presented for 1.39 žm. Wavelength modulation was performed at 35 kHz, and was superimposed on 500 Hz wavelength scans in order to recover full second-harmonic line shapes. H2O line-pair at 7164.901 cm-1 and 7165.215 cm-1 was selected for this measurement. The criteria of the line-pair selection were discussed. The sensitivity and accuracy of the sensor were demonstrated in a static cell in laboratory (over the temperature range of 400-1000 K, average bias ?T ~ 5 K). Burner experiments demonstrate the ability of our system forin situ measurements. The influence caused by variation of total pressure and species concentration in burning gas during combustion was also discussed.

18

Praktyczne podejście do oceny niezawodności aplikacji sieciowych

Li R., Kang R., Huang N., Chen W., Chen Y.

Eksploatacja i Niezawodność

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2009

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nr 4

17-27

PL

Wiele różnych aplikacji może być obsługiwanych przez tę samą sieć. Wymagania użytkowników i kryteria uszkodzeń mogą być odmienne dla różnych aplikacji. Ocena sieci winna być przeprowadzana z punktu widzenia aplikacji. W niniejszym artykule, zaproponowano metodologię oceny niezawodności aplikacji sieciowych opartą na indeksach warstwowych (layered indices). Pierwszym krokiem w omawianej metodzie jest osobne obliczenie niezawodności poszczególnych aplikacji w sieci. Następnie ocenia się niezawodność sieci biorąc pod uwagę związki pomiędzy różnymi aplikacjami. Jako swój wkład niniejszy artykuł (1) przedstawia naukową i praktyczną metodę oceny niezawodności aplikacji sieciowych; (2) tworzy hierarchiczną strukturę do oceny niezawodności aplikacji sieciowych; (3) proponuje i analizuje cztery kluczowe technologie-doboru komponentów, upraszczania sieci, modelowania profilu aplikacji oraz oceny niezawodności aplikacji; (44) ilustruje proponowany proces oceny na przykładzie sieci komputerowej.

EN

Many different applications may be handled by the same network. For different applications, the user requirements and failure criterions may be different. The network reliability assessment needs to be conducted from the "application" point of view. In this paper, a methodology for network application reliability assessment based on layered indices is proposed. Firstly, the individual application reliability is calculated for each application on the network. Then the network reliability is evaluated considering the relationships among different applications. The contributions of this paper are: (1) a scientific and practical network application reliability assessment method is proposed based on network applications; (2) a hierarchical structure for network application reliability assessment is constructed; (3) four key technologies, component selection, network simplification, application profile modeling, and application reliability assessment, are proposed and analyzed; (44) a computer network is used to illustrate the proposed assessment process.

19

Theoretical analysis of plastic zone of a circle crack under gigacycle fatigue regime

Wu T., Mo T., Chen W., Bayraktar E.

Archives of Computational Materials Science and Surface Engineering

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2009

|

Vol. 1, nr 4

245-251

EN

Purpose: Different kinds of alloys used in industry for structures and engine components are subjected to very high cycle fatigue (gigacycle regime) damage under the service conditions. In this study, fatigue damage evolution of some metallic-industrial alloys was investigated on very high cycle fatigue regime and calculation of the stress intensity factor (SIF) using finite element method (FEM) was realized under the ultrasonic vibration conditions. A formula of SIF vs. Cracks size and position of the crack has been developed. In fact, calculation of the SIF under ultrasonic vibrating fatigue has to be a function of amplitude instead of nominal stress as frequently used in traditional fatigue from Woehler. Design/methodology/approach: The specimens are tested at ultrasonic fatigue frequency of 20 kHz with a stress ratio of R=-1 (tension-compression) under load control. In order to control the displacement amplitude at the end of the amplifier was calibrated by optical sensor before each fatigue test. Failure mechanisms have been studied by means of the scanning electron microscope (SEM). The fracture origin and/or inclusions were identified by use of energy disperse analysis. Findings: An analytical approach was validated to calculate the stress intensity factor, KI, for the specimen specially designed for Gigacycle fatigue test. Practical implications: This heat source will be useful to position and size the small crack inside the specimen according to surface temperature variation with further heat transfer analysis. The relation between energy power and stress intensity factor helps to determine crack size and position from the temperature field on the specimen surface. Originality/value: Based on the SIF calculation and from classical fracture mechanics, dissipated energy of the plastic zone of the crack is derived and considered as heat source when the crack initiates.

20

Carbon dioxide detection using NIR diode laser based wavelength modulation photoacoustic spectroscopy

Li J., Liu K., Zhang W., Chen W., Gao X.

Optica Applicata

|

2008

|

Vol. 38, nr 2

341-352

EN

A photoacoustic sensor using a laser diode emitting near 1573 nm in combination with a dual-microphone resonant photoacoustic cell has been developed for carbon dioxide trace gas analysis at atmospheric pressure. Wavelength-modulation scheme and 1f detection for CO2 concentration measurements in Ar are demonstrated. The noise equivalent absorption sensitivity of NEAS(1? ) = 1.01×10-8 Wcm-1/Hz1/2, corresponding to a detection limit of 30 parts in 106 by volume (ppmv) for a 100 s integration time and 4.5 mW average laser power. The photoacoustic response of CO2 dependence on the buffer gases with different mixture ratio of Ar and N2 was investigated. Finally, the possibility to make use of the sensor for measurements of ambient CO2 is also presented.