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1

One cause of pulse-like anomalies observed at Guza before the Wenchuan earthquake

Zhou C., Wang Q., Zhu L., Wang C.

Acta Geophysica

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2018

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Vol. 66, no. 5

833--842

EN

Many precursor-like anomaly observations prior to the Wenchuan earthquake were reported and analyzed, especially the abnormal strain pulses observed at the Guza station, but there are few discussions of the causes. Stick–slip motion is the basis for description of a great variety of phenomena characterized by the presence of sliding friction. In this article, perturbed Sine–Gordon (SG) equation is established from Bykov’s unsteady-state slip model. Stable solitary solutions of displacement and strain dimension are obtained and nonlinear pulse propagation is simulated using finite-difference modeling, while numerical stability is obtained by the flux-corrected transport method. Considering the solution of SG equation as initial source, a comparison between the modeling results and actual data at the Guza station gives one possible interpretation for this anomaly. During the seismogenic process of the Wenchuan earthquake, faults may likely occur as stick–slip tectonic movements which might be described by SG equation and would generate solitary wave signal. This kind of pulse experiences a forward tilting distortion due to nonlinear effect of the Earth and is received by the borehole strainmeter. Two kinds of nonlinear effects could lead to these special pulses. One is the nonlinear effects in the wave propagation process, and the other is effects of friction and stress in the process of unsteady-state slip. Because of the convergence effect of pulse, the wave would be collapsed at a certain time due to an excessive increase in the tilt angle. Hence, this kind of pulse cannot propagate for a long distance.

2

One shot profilometry using iterative two-step temporal phase-unwrapping

Du G., Wang M., Zhou C., Si S., Li H., Lei Z., Li Y.

Optica Applicata

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2017

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Vol. 47, nr 1

97--110

EN

This paper reviews two techniques that have been recently published for three-dimensional profilometry and proposes one shot profilometry using iterative two-step temporal phase-unwrapping by combining the composite fringe projection and the iterative two-step temporal phase unwrapping algorithm. In temporal phase unwrapping, many images with different frequency fringe pattern are needed to project, which would take much time. In order to solve this problem, Ochoa proposed a phase unwrapping algorithm based on phase partitions using a composite fringe. However, we found that the fringe order determined through the construction of phase partitions tended to be imprecise. Recently, we proposed an iterative two-step temporal phase unwrapping algorithm, which can achieve high sensitivity and high precision shape measurement. But it needs multiple frames of fringe images which would take much time. In order to take into account both the speed and accuracy of three-dimensional shape measurement, we get a new, and more accurate unwrapping method based on a composite fringe pattern by combining these two techniques. This method not only retains the speed advantage of Ochoa’s algorithm, but also greatly improves its measurement accuracy. Finally, the experimental evaluation is conducted to prove the validity of the proposed method.

3

Improved method for phase wraps reduction in profilometry

Du G., Wang M., Zhou C., Si S., Li H., Lei Z., Li Y.

Optica Applicata

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2017

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Vol. 47, nr 2

295--306

EN

In order to completely eliminate, or greatly reduce the number of phase wraps in 2D wrapped phase map, Gdeisat and co-workers proposed an algorithm, which uses shifting the spectrum towards the origin. But the spectrum can be shifted only by an integer number, meaning that the phase wraps reduction is often not optimal. In addition, Gdeisat’s method will take much time to make the Fourier transform, inverse Fourier transform, select and shift the spectral components. In view of the above problems, we proposed an improved method for phase wraps elimination or reduction. First, the wrapped phase map is padded with zeros, the carrier frequency of the projected fringe is determined by high resolution, which can be used as the moving distance of the spectrum. And then realize frequency shift in spatial domain. So it not only can enable the spectrum to be shifted by a rational number when the carrier frequency is not an integer number, but also reduce the execution time. Finally, the experimental results demonstrated that the proposed method is feasible.

4

Research on community garden practice - taking ‘the Kid’s Garden’ in Hunan Agricultural University as an example

Zhou Z., Huang Y., Zhou C.

Architektura Krajobrazu

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2017

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nr 3

34--43

EN

As a form of urban green space, community gardens have provided urban residents with various environments, to satisfy their social, economic and health interests. For the purposes of creating public, open and shared spaces, this article summarizes and contrasts the history of the community garden development in Europe and America, while analyzing the development situation of China as well. Taking “the Kid’s Garden” in Hunan Agricultural University as an example, the authors discuss the whole practice process in three aspects: the layout design, the construction process, and the operation and maintenance plan. Finally, the conclusion of the article presents a community garden building model, which is supported by universities with the goals to reward the society, as well as to provide a win-win result between practice and teaching. This experience is hoped to popularize community gardens and to make a contribution towards a harmonious society.

5

Artificial Bee Colony Algorithm for the Protein Structure Prediction Based on the Toy Model

Li Y., Zhou C., Zheng X.

Fundamenta Informaticae

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2015

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Vol. 136, nr 3

241--252

EN

The protein structure folding is one of the most challenging problems in the field of bioinformatics. The main problem of protein structure prediction in the 3D toy model is to find the lowest energy conformation. Although many heuristic algorithms have been proposed to solve the protein structure prediction (PSP) problem, the existing algorithms are far from perfect since PSP is an NP-problem. In this paper, we proposed an artificial bee colony (ABC) algorithm based on the toy model to solve PSP problem. In order to improve the global convergence ability and convergence speed of the ABC algorithm, we adopt a new search strategy by combining the global solution into the search equation. Experimental results illustrate that the suggested algorithm can get the lowest energy when the algorithm is applied to the Fibonacci sequences and to four real protein sequences which come from the Protein Data Bank (PDB). Compared with the results obtained by PSO, LPSO, PSO-TS, PGATS, our algorithm is more efficient.

6

Comprehensive Evaluation Cloud Model for Ship Navigation Adaptability

Zhu M., Wen Y., Zhou C., Xiao C.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

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2014

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Vol. 8, no. 3

331--336

EN

In this paper, using cloud model and Delphi, we build a comprehensive evaluation cloud model to solve the problems of qualitative description and quantitative transformation in ship navigation adaptability comprehensive evaluation. In the model, the normal cloud generator is used to find optimal cloud models of reviews and evaluation factors. The weight of each evaluation factor is determined by cloud model and Delphi. The floating cloud algorithm is applied to aggregate the bottom level’s evaluation factors, and comprehensive cloud algorithm is used to aggregate the highest level’s evaluation factors to get comprehensive evaluation cloud model. Finally, evaluation result is got by matching comprehensive evaluation cloud model and optimal cloud model of reviews. As case study, the model is applied to the small LNG ship’s navigation adaptability in Southeast Asia. Compared with the fuzzy comprehensive evaluation method, the model proposed in this paper is more intuitive and reliable in comprehensive evaluation of the small LNG ship’s navigation adaptability.

7

Deflectometry for phase retrieval using a composite fringe

Liu T., Zhou C., Liu Y, Si S, Lei Z.

Optica Applicata

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2014

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Vol. 44, nr 3

451--461

EN

An improved deflectometry for wavefront measurement using a composite fringe is proposed to reduce the projection fringes and improve the accuracy. The single composite fringe contains four fringes in different directions. It goes through the tested objects and then is captured by a CCD camera. Two high frequency orthogonal fringe patterns and two single period orthogonal fringe patterns can be obtained from the composite fringe by fast Fourier transform. The unwrapping of the wrapped phase of the high frequency fringe is accomplished by the corresponding single period fringe using a heterodyne method. The wavefront is reconstructed by the integration of partial derivatives. Using only one fringe, the proposed method is more applicable to dynamic wavefront measurement. The experimental results demonstrate that the proposed method can retrieve the complex wavefronts more accurately.

8

EL and ITG Characterization of Large Areas Black Silicon Solar Cells VIA Screen Printing

Tang Y., Zhou C., Wang W., Zhou S., Zhao Y., Fei J., Cao H.

Przegląd Elektrotechniczny

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2013

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R. 89, nr 3b

95--97

EN

A simple process of texturing silicon (Si) surfaces using gold (Au)-catalyzed wet chemical etching was used to form black Si (BS) on a (100) p-type substrate. The surface became uniformly black after 6 min, with a resulting reflectivity of < 2% over the 400 nm to 1100 nm wavelength range. Large areas (153.18 cm2) of black Si solar cells (BSSCs) with an n+-p-p+ structure were also fabricated using conventional processes, including POCl3 diffusion, screen printing, and co-firing. The resulting cells were divided into two groups according to the emitter (46 and 37 [omega]/􀀀), and their output parameters were studied. The best convention efficiency (Eff) was < 10%. The open-circuit voltage (Voc) was particularly low because of poor surface passivation, and the shunt resistance (Rsh) linearly decreased with the series resistance (Rs). Electroluminescence (EL) and infrared thermography (ITG) measurements were conducted to characterize the BSSCs. Both the emissivity and temperature were low and nonuniform. Optimizing the fabrication process by reducing the etching depth and lowering the dopant sheet resistance led to significant improvement in Voc (~48 mV) and Eff (~3.8% absolute). EL and ITG measurements indicate that Rs is another important factor that accounts for the poor properties of the BSSCs.

PL

W artykule opisano proces teksturowania powierzchni krzemowej w procesie wytrawiania chemicznego z katalizatorem w formie złota, na potrzeby produkcji czarnego krzemu (BS) na podłożu p. Zastosowane rozwiązanie m. in. optymalizacji procesu teksturowania, poprzez redukcję głębokości wytrawiania dało znaczącą poprawę napięcia Voc oraz Eff. Wykonane badania wskazują, że rezystancja szeregowa Rs stanowi ważny czynnik wpływający na działanie ogniw słonecznych, zbudowanych z czarnego krzemu.

9

EL and ITG Characterization of Large Areas Black Silicon Solar Cells VIA Screen Painting

Tang Y., Zhou C., Wang W., Zhou S., Zhao Y., Liu X., Zhao L., Li H., Chen J., Yan B., Fei J., Cao H., Wu X.

Przegląd Elektrotechniczny

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2013

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R. 89, nr 1b

151--154

EN

A simple process of texturing silicon (Si) surfaces using gold (Au)-catalyzed wet chemical etching was used to form black Si (BS) on a (100) p-type substrate. The surface became uniformly black after 6 min, with a resulting reflectivity of < 2% over the 400 nm to 1100 nm wavelength range. Large areas (153.18 cm 2) of black Si solar cells (BSSCs) with an n + -p-p + structure were also fabricated using conventional processes, including POCl3 diffusion, screen printing, and co-firing. The resulting cells were divided into two groups according to the emitter (46 and 37 Ω/), and their output parameters were studied. The best convention efficiency (Eff) was < 10%. The open-circuit voltage (Voc) was particularly low because of poor surface passivation, and the shunt resistance (Rsh) linearly decreased with the series resistance (Rs). Electroluminescence (EL) and infrared thermography (ITG) measurements were conducted to characterize the BSSCs. Both the emissivity and temperature were low and nonuniform. Optimizing the fabrication process by reducing the etching depth and lowering the dopant sheet resistance led to significant improvement in Voc (~48 mV) and Eff (~3.8% absolute). EL and ITG measurements indicate that Rs is another important factor that accounts for the poor properties of the BSSCs.

PL

Do wytworzenia czarnego krzemu (BS) na podłożu typu p-Si(100) zastosowano prosty sposób teksturowania powierzchni krzemowej metodą chemicznej akwaforty na mokro z zastosowaniem, jako katalizatora, nanocząstek złota (Au). Podłoże staje się jednolicie czarne po 6 min, osiągając współczynnik odbicia < 2% w zakresie długości fali od 400 nm do 1100 nm. Wykonano również dużą powierzchnię czarnych krzemowych ogniw słonecznych (BSSC), ze strukturą n + - p -n +, konwencjonalnymi metodami obejmującymi dyfuzję POC13,drukowanie maski i wyżarzanie. Otrzymane ogniwa dzielą się na dwie grupy w zależności od emitera (46 i 37Ω/): zbadano ich wyjściowe parametry. Najlepsza uzyskana wydajność wynosi < 10%. Napięcie obwodu otwartego (Voc) jest szczególnie niskie z powodu słabej pasywacji powierzchni, a rezystancja równoległa (Rsh) liniowo maleje z rezystancją szeregową (Rs). Charakterystykę BSSC określają pomiary elektroluminescencji (EL) i tomografii w podczerwieni (ITG).Zarówno emisyjność jak i temperatura są niskie i niejednorodne. Optymalizacja procesu wykonana przez zmniejszenie głębokości akwaforty i obniżenie rezystancji warstwy domieszkowania prowadzi do znaczącej poprawy Voc (ok. 48mV) i Eff (ok. 3,8%).

10

Fisher’s linear discriminant (FLD) and support vector machine (SVM) in non-negative matrix factorization (NMF) residual space for face recognition

Zhou C., Wei X., Zhang Q., Fang X.

Optica Applicata

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2010

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Vol. 40, nr 3

693--704

EN

A novel method of Fisher’s linear discriminant (FLD) in the residual space is put forward for the representation of face images for face recognition, which is robust to the slight local feature changes. The residual images are computed by subtracting the reconstructed images from the original face images, and the reconstructed images are obtained by performing non-negative matrix factorization (NMF) on original images. FLD is applied to the residual images for extracting FLD subspace and the corresponding coefficient matrices. Furthermore, features are obtained by mapping the residual image to FLD subspace. Finally, the features are utilized to train and test support vector machines (SVMs) for face recognition. The computer simulation illustrates that this method is effective on the ORL database and the extended Yale face database B.

11

Fuzzy-Arithmetic-Based Lyapunov Synthesis in the Design of Stable Fuzzy Controllers: a Computing-With-Words Approach

Zhou C.

International Journal of Applied Mathematics and Computer Science

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2002

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Vol. 12, no 3

411-421

EN

A novel approach to designing stable fuzzy controllers with perception-based information using fuzzy-arithmetic-based Lyapunov synthesis in the frame of computing with words (CW) is presented. It is shown that a set of conventional fuzzy control rules can be derived from the perception-based information using the standard-fuzzy-arithmetic-based Lyapunov synthesis approach. On the other hand, a singleton fuzzy controller can be devised by using a constrained-fuzzy-arithmetic-based Lyapunov synthesis approach. Furthermore, the stability of the fuzzy controllers can be guaranteed by means of the fuzzy version of Lyapunov stability analysis. Moreover, by introducing standard and constrained fuzzy arithmetic in CW, the "words" represented by fuzzy numbers could be efficiently manipulated to design fuzzy controllers. The results obtained are illustrated with the design of stable fuzzy controllers for an autonomous pole balancing mobile robot.