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1
Content available Research on capacity of mixed vessels traffic flow based on vessel-following theory
Zhao C., Yan H., Zhou G., Liu T.
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
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2022
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Vol. 16 No. 3
535--539
EN
In order to study the characteristics of mixed vessel traffic flow, based on classical head distance model and probability analysis, by studying the combination time head way of different vessel-following sequences, the capacity model of mixed vessels traffic flow was established. Through analyzing two representative types of vessels, research results indicate that the capacity of mixed traffic increase with the traffic flow speed in a certain speed range, but the increasing trend slow down. The closer length and inertial stopping distance of different kind vessels are, the more capacity of mixed traffic increases. And the influence of reaction time on the capacity is related to proportion of different kind vessels.
2
Content available Analysis on the process of ship striking the anti-collision pier
Zhao C., Yan H.
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
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2022
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Vol. 16 No. 3
501--504
EN
China's extensive inland navigable water system determines that inland navigation must be an important part of China's shipping industry. The collision process of ship striking the anti-collision pier is analyzed through simulation experiment in this paper. The results show that the collision process usually lasts less than 2 seconds, and the peak value of the collision force, friction and resultant force appears 0.5 after the start of the collision.
3
Content available Flotation kinetics and thermodynamic behavior of chalcopyrite and pyrite in high alkaline systems
Yan H., Yuan Q., Zhou L., Qiu T., Ai G.
Physicochemical Problems of Mineral Processing
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2018
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Vol. 54, iss. 3
901--910
EN
The monomineral flotation test and microcalorimetry were used to study the flotation kinetics and thermodynamic behavior of chalcopyrite and pyrite in high alkaline systems of lime and NaOH. The results showed that in these systems there were less hydrophilic substances on the chalcopyrite surface, so that the apparent activation energy of sodium butyl xanthate (SBX) adsorption on chalcopyrite surface was low. This promoted the adsorption of SBX and increased the flotation rate and recovery of chalcopyrite. In contrast, the hydrophilic Fe(OH)3 and SO42- formed by oxidation on the pyrite surface increased the adsorption activation energy of SBX. Thus, the flotation rate and recovery of pyrite were lower. Moreover, in the lime high alkaline system, the hydrophilic calcium film generated on the pyrite surface further hindered the adsorption of SBX, thereby further inhibiting pyrite in this environment. In other words, the lime high alkaline environment increased the apparent activation energy difference of SBX adsorption between chalcopyrite and pyrite compared to the NaOH system, facilitating the flotation separation of chalcopyrite and pyrite. The results can help with the theoretical research of flotation separation of other minerals, and provide guidance for developing low alkaline and lime-free pyrite depressants.
4
Content available Activating flotation of chalcopyrite using CuSO4 and H2O2 from the cyanide tailings
Ai G., Yan H., Qiu T., Liu C.
Physicochemical Problems of Mineral Processing
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2018
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Vol. 54, iss. 2
578--589
EN
The effects of CuSO4 and H2O2 on the flotation behavior of cyanide chalcopyrite were investigated by flotation tests, microcalorimetry and X-ray photoelectron spectroscopy (XPS). The underlying activation mechanism was studied in the perspective of micro-thermodynamics and surface properties. The flotation results indicated that cyanide chalcopyrite was strongly inhibited by sodium cyanide, with the maximum flotation recovery of 22.5% only. CuSO4 and H2O2 significantly improved the flotation of cyanide chalcopyrite, and the flotation recovery was increased to 92.28% and 84.35%, respectively. The micro-thermodynamics results indicated that the adsorption heat of butyl xanthate on cyanide chalcopyrite surface increased after the addition of CuSO4 and H2O2, as well as the reaction order. CuSO4 and H2O2 can significantly improve the adsorption of butyl xanthate on the surface of cyanide chalcopyrite by decreasing the apparent activation energy by 80.11% and 66.54%, respectively. XPS analysis indicated that the CuCN was generated on the surface of cyanide chalcopyrite, leading to the loss of sulfur and inhibiting the adsorption of collectors. As a result, the flotation of cyanide chalcopyrite was depressed. It is considered that, CuSO4 and H2O2 can improve the flotation of cyanide chalcopyrite by eleminating CuCN from its surface and increasing the concentration of S by 57.02% and 37.48%, respectively.
5
Content available remote Automatic identifying of maternal ECG source when applying ICA in fetal ECG extraction
Yu Q., Yan H., Song L., Guo W., Liu H., Si J., Zhao Y.
Biocybernetics and Biomedical Engineering
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2018
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Vol. 38, no. 3
448--455
EN
Independent component analysis (ICA) is usually used as a preliminary step for maternal electrocardiogram (ECG) QRS detection in fetal ECG extraction. When applying ICA to do this, a troublesome problem arises from how to automatically identify the separated maternal ECG component. In this paper we proposed a method called PRCH (short for Peak to peak entropy, R-R interval entropy, Correlation coefficient and Heart rate) for the automatic identifying. In the method, we defined four kinds of features, including amplitude, instantaneous heart rate, morphology and average heart rate, to characterize a signal, and determined some decision parameters through machine learning. Experiments and comparison with other three existed methods were given. Through taking metric F1 for evaluation, it showed that the proposed PRCH method has the highest identifying accuracy and generalization capability.
6
Content available remote Water Storage Changes over the Tibetan Plateau Revealed by GRACE Mission
Guo J., Mu D., Liu X., Yan H., Sun Z., Guo B.
Acta Geophysica
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2016
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Vol. 64, no. 2
463--476
EN
We use GRACE gravity data released by the Center for Space Research (CSR) and the Groupe de Recherches en Geodesie Spatiale (GRGS) to detect the water storage changes over the Tibetan Plateau (TP). A combined filter strategy is put forward to process CSR RL05 data to remove the effect of striping errors. After the correction for GRACE by GLDAS and ICE-5G, we find that TP has been overall experiencing the water storage increase during 2003-2012. During the same time, the glacier over the Himalayas was sharply retreating. Interms of linear trends, CSR’s results derived by the combined filter are close to GRGS RL03 with the Gaussian filter of 300-km window. The water storage increasing rates determined from CSR’s RL05 products in the interior TP, Karakoram Mountain, Qaidam Basin, Hengduan Mountain, and middle Himalayas are 9.7, 6.2, 9.1, –18.6, and –20.2 mm/yr, respectively. These rates from GRGS’s RL03 products are 8.6, 5.8, 10.5, –19.3 and –21.4 mm/yr, respectively.
7
Content available remote Implementation of Elastic Prestack Reverse-Time Migration Using an Efficient Finite-Difference Scheme
Yan H., Yang L., Dai H., Li X. Y.
Acta Geophysica
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2016
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Vol. 64, no. 5
1605--1625
EN
Elastic reverse-time migration (RTM) can reflect the underground elastic information more comprehensively than single-component Pwave migration. One of the most important requirements of elastic RTM is to solve wave equations. The imaging accuracy and efficiency of RTM depends heavily on the algorithms used for solving wave equations. In this paper, we propose an efficient staggered-grid finite-difference (SFD) scheme based on a sampling approximation method with adaptive variable difference operator lengths to implement elastic prestack RTM. Numerical dispersion analysis and wavefield extrapolation results show that the sampling approximation SFD scheme has greater accuracy than the conventional Taylor-series expansion SFD scheme. We also test the elastic RTM algorithm on theoretical models and a field data set, respectively. Experiments presented demonstrate that elastic RTM using the proposed SFD scheme can generate better images than that using the Taylor-series expansion SFD scheme, particularly for PS images. Furthermore, the application of adaptive variable difference operator lengths can effectively improve the computational efficiency of elastic RTM.
8
Content available Reliability analysis and optimization of equal load-sharing k-out-of-n phased-mission systems
Jiakai C., Yan H., Wei W.
Eksploatacja i Niezawodność
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2015
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Vol. 17, no. 2
250--259
EN
There are many studies on k-out-of-n systems, load-sharing systems (LSS) and phased-mission systems (PMS); however, little attention has been given to load-sharing k-out-of-n systems with phased-mission requirements. This paper considers equal loadsharing k-out-of-n phased-mission systems with identical components. A method is proposed for the phased-mission reliability analysis of the studied systems based on the applicable failure path (AFP). A modified universal generating function (UGF) is used in the AFP-searching algorithm because of its efficiency. The tampered failure rate load-sharing model for the exactly k-out-of-n: F system is introduced and integrated into the method. With the TFR model, the systems with arbitrary load-dependent component failure distributions can be analyzed. According to the time and space complexity analysis, this method is particularly suitable for systems with small k-values. Two applications of the method are introduced in this paper. 1) A genetic algorithm (GA) based on the method is presented to solve the operational scheduling problem of systems with independent submissions. Two theorems are provided to solve the problem under some special conditions. 2) The method is used to select the optimal number of components to make the system reliable and robust.
PL
Istnieje wiele badań na temat systemów typu „k z n”, systemów z podziałem obciążenia (load-sharing systems, LSS) oraz systemów fazowych (tj. systemów o zadaniach okresowych) (phased-missionsystems, PMS); jak dotąd mało uwagi poświęcono jednak systemom typu „k z n” z podziałem obciążenia wymagającym realizacji różnych zadań w różnych przedziałach czasowych. Niniejszy artykuł omawia systemy fazowe typu „k z n” o równym podziale obciążenia przypadającego na identyczne elementy składowe. Zaproponowano metodę analizy niezawodności badanych systemów w poszczególnych fazach ich eksploatacji opartą na pojęciu właściwej ścieżki uszkodzeń (applicablefailurepath, AFP). W algorytmie wyszukującym AFP zastosowano zmodyfikowaną uniwersalną funkcję tworzącą (universal generating function, UGF), która cechuje się dużą wydajnością. Wprowadzono model manipulowanej intensywności uszkodzeń (tamperedfailurerate, TFR) elementów o równym podziale obciążenia dla systemu, w którym liczba uszkodzeń wynosi dokładnie k z n. Model ten włączono do proponowanej metody analizy niezawodności. Przy pomocy modelu TFR można analizować systemy o dowolnych rozkładach uszkodzeń części składowych, gdzie uszkodzenia są zależne od obciążenia. Zgodnie z analizą złożoności czasowej i przestrzennej, metoda ta jest szczególnie przydatna do modelowania układów o małych wartościach k. W pracy przedstawiono dwa zastosowania metody. 1) oparty o omawianą metodę algorytm genetyczny (GA) do rozwiązywania problemu harmonogramowania prac w systemach z niezależnymi podzadaniami. Sformułowano dwa twierdzenia pozwalające na rozwiązanie problemu w pewnych szczególnych warunkach. 2) Wybór optymalnej liczby elementów składowych pozwalającej na zachowanie niezawodności i odporności systemu.
9
Content available remote Acoustic Reverse-time Migration using Optimal Staggered-grid Finite-difference Operator Based on Least Squares
Yan H., Yang L., Liu H.
Acta Geophysica
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2015
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Vol. 63, no. 3
715--734
EN
Reverse-time migration (RTM) directly solves the two-way wave equation for wavefield propagation; therefore, how to solve the wave equation accurately and quickly is very important for RTM. The conventional staggered-grid finite-difference (SFD) operators are usually based on the Taylor-series expansion theory. If they are used to solve wave equation on a larger frequency content, a strong dispersion will occur, which directly affects the seismic image quality. In this paper, we propose an optimal SFD operator based on least squares to solve acoustic wave equation for prestack RTM, and obtain a new antidispersion RTM algorithm that can use short spatial difference operators. The synthetic and real data tests demonstrate that the least squares SFD (LSSFD) operator can mitigate the numerical dispersion, and the acoustic RTM using the LSSFD operator can effectively improve image quality comparing with that using the Taylor-series expansion SFD (TESFD) operator. Moreover, the LSSFD method can adopt a shorter spatial difference operator to reduce the computing cost.
10
Content available remote Equivalent water height extracted from GRACE gravity field model with robust independent component analysis
Guo J., Mu D., Yan H., Dai H.
Acta Geophysica
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2014
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Vol. 62, no. 4
953--972
EN
The Level-2 monthly GRACE gravity field models issued by Center for Space Research (CSR), GeoForschungs Zentrum (GFZ), and Jet Propulsion Laboratory (JPL) are treated as observations used to extract the equivalent water height (EWH) with the robust independent component analysis (RICA). The smoothing radii of 300, 400, and 500 km are tested, respectively, in the Gaussian smoothing kernel function to reduce the observation Gaussianity. Three independent components are obtained by RICA in the spatial domain; the first component matches the geophysical signal, and the other two match the north-south strip and the other noises. The first mode is used to estimate EWHs of CSR, JPL, and GFZ, and compared with the classical empirical decorrelation method (EDM). The EWH STDs for 12 months in 2010 extracted by RICA and EDM show the obvious fluctuation. The results indicate that the sharp EWH changes in some areas have an important global effect, like in Amazon, Mekong, and Zambezi basins.
11
Content available remote Tensile Properties of Regenerated Bamboo Yarn
Li L., Yan H.
Fibres & Textiles in Eastern Europe
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2012
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Vol. 20, no. 1 (90)
20-22
PL
Za pomocą HD021N badano właściwości wytrzymałościowe przędz 14.58 tex przy rożnych prędkościach rozciągania (100, 500, 1000, 2000, 3000, 4000 i 5000 mm/min). Stwierdzono, że charakterystyki częstotliwościowe wytrzymałości i wydłużenia miały rozkład normalny. Wytrzymałość na zerwanie zwiększała się przy wzroście prędkości rozciągania od 100 - 3000 mm/min, a następnie zmniejszała się ze wzrostem szybkości rozciągania. Czas zerwania zmniejszał się wraz ze wzrostem prędkości rozciągania. Opracowano model układu lepko-sprężystego o charakterystyce nieliniowej i zastosowano do symulacji zachowania się włókien przy rożnych szybkościach rozciągania. Stwierdzono, że błąd pomiędzy wartościami obliczonymi z modelu a uzyskanymi doświadczalnie jest bardzo mały i nie przekracza 3%.
EN
The tensile property of regenerated bamboo yarn of 14.58 tex was studied using an HD021N single yarn tensile tester at different tensile speeds (100, 500, 1000, 2000, 3000, 4000, and 5000 mm/min). It was observed that the distribution on diagrams of the breaking strengthfrequency and elongation at break frequency of yarn is normal. The breaking strength of the yarn increases when the tensile speed varies from 100 mm/min to 3000 mm/min, then the strength decreases greatly with an increase in tensile speed. The breaking time of the yarn decreases with an increase in tensile speed. A non-linear three-element viscoelastic model was used to simulate the tensile property of the yarn at various tensile rates. The relative error between the theoretical tenacity and actual tenacity is bound to be less than 3%.
12
Content available remote Properties comparison of GaN epilayers deposited under different growth temperatures
Wang P., Yan H., Cao B., Wei W., Gan Z., Liu Z.
Opto-Electronics Review
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2011
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Vol. 19, No. 1
30-33
EN
Undoped GaN epilayers were grown on c-plane sapphire substrates under different growth temperatures by metalorganic chemical vapour deposition (MOCVD). The optical and structural characteristics of these grown samples were studied and compared. It was found that the crystalline quality of GaN film deposited at 1050°C was better that of other samples. Photoluminescence spectra showed that the intensities of yellow luminescence band of the samples decreased as the growth temperature increased. All above test results demonstrate that high temperature deposition can serve as a good method for high-quality GaN epilayer growth and there exists an optimal growth temperature.
13
Content available remote Performance analysis of bit error rate for free space optical communication with tip-tilt compensation based on gamma-gamma distribution
Wu H., Yan H., Li X.
Optica Applicata
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2009
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Vol. 39, nr 3
533-545
EN
In this paper, the gamma - gamma probability distribution is used to model turbulent channels. The bit error rate (BER) performance of free space optical (FSO) communication systems employing on-off keying (OOK) or subcarrier binary phase-shift keying (BPSK) modulation format is derived. A tip-tilt adaptive optics system is also incorporated with a FSO system using the above modulation formats. The tip-tilt compensation can alleviate effects of atmospheric turbulence and thereby improve the BER performance. The improvement is different for different turbulence strengths and modulation formats. In addition, the BER performance of communication systems employing subcarrier BPSK modulation is much better than that of compatible systems employing OOK modulation with or without tip-tilt compensation.
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