Wyniki wyszukiwania - BazTech

1

A flexible control strategy for shoreto- ship power system in terms of gridconnected and off-grid switch

Ji Z., Zhao Z., Wang J., Lv Z.

Polish Maritime Research

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2018

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S 2

139--148

EN

There are promising application prospects for applying the shore power technology to the ships in the port for the purpose of pollution prevention. However, the grid-connection of the shore power supply to the ship power grid leads to current surges, damages the ship power consumption equipment, and results in the instability of the ship power grid system, which will seriously affect the reliability of the operation of the ship power grid system. In order to address this problem, the mathematical model of virtual synchronous generator is introduced in this paper. Then, a control method for the flexible grid-connection of the shore power supply to the ship power grid based on the virtual synchronous generator is proposed. Next, the output characteristics of the shore power supply are optimized to match the characteristics of the ship generator, which contributes to the flexible grid-connection of the shore power supply to the ship power grid system. The effectiveness and the feasibility of this method are verified by simulation and experiments.

2

An improved resonant thermal converter based on micro-bridge resonator

Dong L., Han J., Zhang P., Zhao Z., Cheng B., Han D.

Metrology and Measurement Systems

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2018

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Vol. 25, nr 4

715--725

EN

This paper presents the design, fabrication and testing of an improved thin-film thermal converter based on an electro-thermally excited and piezo-resistively detected micro-bridge resonator. The resonant thermal converter comprises a bifilar heater and an opposing micro-bridge resonator. When the micro-bridge resonator absorbs the radiant heat from the heater, its axial strain changes, then its resonant frequency follows. Therefore the alternating voltage or current can be transferred to the equivalent DC quantity. A non-contact temperature sensing mechanism eliminates heat loss from thermopiles and reduces coupling capacitance between the temperature sensor and the heater compared with traditional thin-film thermal converters based on thermopiles. In addition, the quasi-digital output of the resonant thin-film thermal converter eliminates such problems as intensity fluctuations associated with analogue signals output by traditional thin-film thermal converters. Using the fast-reversed DC (FRDC) method, the thermoelectric transfer difference, which determines the frequency-independent part of the ac-dc transfer difference, is evaluated to be as low as 1.1 · 10-6. It indicates that the non-contact temperature sensing mechanism is a feasible method to develop a high-performance thermal converter.

3

A novel method for 3D measurement of RFID multi-tag network using a machine vision system

Zhuang X., Yu X., Zhao Z., Zhang W., Liu Z., Lu D., Dong D.

Metrology and Measurement Systems

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2018

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Vol. 25, nr 3

475--486

EN

The three-dimensional (3D) coordinate measurement of radio frequency identification (RFID) multi-tag networks is one of the important issues in the field of RFID, which affects the reading performance of RFID multi-tag networks. In this paper, a novel method for 3D coordinate measurement of RFID multi-tag networks is proposed. A dual-CCD system (vertical and horizontal cameras) is used to obtain images of RFID multi-tag networks from different angles. The iterative threshold segmentation and the morphological filtering method are used to process the images. The template matching method is respectively used to determine the two-dimensional (2D) coordinate and the vertical coordinate of each tag. After that, the 3D coordinate of each tag is obtained. Finally, a back-propagation (BP) neural network is used to model the nonlinear relationship between the RFID multi-tag network and the corresponding reading distance. The BP neural network can predict the reading distances of unknown tag groups and find out the optimal distribution structure of the tag groups corresponding to the maximum reading distance. In the future work, the corresponding in-depth research on the neural network to adjust the distribution of tags will be done.

4

Effect of Alloying Elements on Plastic Workability and Corrosion Behavior of Ti-X (X = 6 Co, 8 Cr, 4 Fe, 6 Mn, 10 Mo, and 36 Nb) Binary Alloys

Zhao Z., Lee K.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 2B

1185--1190

EN

The purpose of this study was to investigate the effect of the alloying elements on the plastic workability and corrosion behavior of Ti-X (wt.%) (X = 6 Co, 8 Cr, 4 Fe, 6 Mn, 10 Mo, and 36 Nb) binary alloys. The alloys with a molybdenum equivalence of 10 wt.% were fabricated by a vacuum arc re-melting process and were then homogenized at a temperature 20°C greater than the beta transus temperature for 14.4 ks. The plastic workability was investigated under uniaxial cold rolling, while the corrosion behavior was examined in Ringer’s solution at 37°C. Among the Ti-X alloys, the Ti-8 wt.% Cr and Ti-6 wt.% Mn alloys showed an outstanding plastic workability and corrosion resistance, respectively.

5

Research on time-varying characteristics of testability index based on renewal process

Zhao Z., Qiu J., Liu G., Zhang Y.

Eksploatacja i Niezawodność

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2016

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Vol. 18, no. 3

457--468

EN

Testability indices are used in the phases of testability design and testability demonstration. This paper focuses on fault detection rate (FDR), which is the most widely used testability index. Leading hypothesis suggests that the value of FDR of a system is usually a certain value. However, few attempts have been made to research the statistical characteristics of FDR. Considering the fault occurrence process and test uncertainty, FDR is time varying and a special statistical process. Under the assumption of perfect repairs, we build a fault occurrence model based on the renewal process theory. Supposing that test uncertainty is mainly induced by test fault, the renewal process is employed to depict the occurrence process of test faults. Simultaneously, we depict the process of test state change and then construct the fault detection logic based on the digraph model. Combining the fault occurrence model and the fault detection logic, we focus on the expectation of FDR, which is one of the key statistical characteristics. By comparison, we introduce the calculation method of expectation of FDR in two cases, including without considering test uncertainty and considering test uncertainty. To validate the conclusions presented in this paper, we carry on a simulation case using an integrated controller. Based on the theoretic and simulating methods, the expectation of FDR tends to be a constant with the increase of time under the assumptions made in this paper. The statistical characteristic of FDR presented in this paper would be the basic theoretical guide to testability engineering.

PL

Wskaźniki testowalności wykorzystuje się w fazach projektowania oraz potwierdzania testowalności. Przedstawiony artykuł poświęcony jest wskaźnikowi wykrywalności błędów (fault detection rate, FDR), który jest najczęściej stosowanym wskaźnikiem testowalności. Wiodąca hipoteza sugeruje, że wartość FDR dla danego systemu jest zwykle wartością pewną. Istnieje jednak niewiele badań na temat statystycznych własności FDR. Biorąc pod uwagę proces występowania błędów oraz niepewność pomiarów, współczynnik FDR można opisać jako zmienny w czasie specjalny proces statystyczny. Przy założeniu naprawy doskonałej, zbudowaliśmy model występowania błędów w oparciu o teorię procesu odnowy. Przyjmując, że niepewność testową wywołują głównie błędy testowe, wykorzystaliśmy proces odnowy do zobrazowania procesu występowania błędów testowych. Jednocześnie przedstawiliśmy proces zmiany stanu testu, a następnie zbudowaliśmy logikę wykrywania błędów w oparciu o model grafu skierowanego. Łącząc model występowania błędów z logiką wykrywania błędów, opracowaliśmy metodę obliczania wartości oczekiwanej FDR, która jest jedną z najważniejszych własności statystycznych tego wskaźnika. Dla porównania, metodę obliczania wartości oczekiwanej FDR zastosowaliśmy w dwóch przypadkach, z uwzględnieniem i bez uwzględnienia niepewności testowej. Aby zweryfikować wnioski przedstawione w niniejszej pracy, przeprowadziliśmy symulację z wykorzystaniem zintegrowanego kontrolera. Obliczenia teoretyczne i symulacja pokazują, że wartość oczekiwana FDR wraz z upływem czasu staje się wartością stałą w warunkach założonych w niniejszej pracy. Przedstawiona w artykule charakterystyka statystyczna FDR stanowi jedną z podstaw teoretycznych inżynierii testowej.

6

Effect of dispersion order on the spectral degree of polarization of stochastic electromagnetic pulsed beams

Wang H., Ding C., Zhang Y., Zhao Z., Pan L.

Optica Applicata

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2014

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Vol. 44, nr 1

147--158

EN

The analytical expression for the cross-spectral density function of stochastic electromagnetic Bessel–Gauss pulsed beams through a dispersive aperture lens is derived and used to study the changes in the spectral degree of polarization in an optical focus system. The changes in the spectral degree of polarization at the focal plane and on the z-axis are performed in the case of dispersion-free, dispersion of the first, second, and higher orders, respectively. It is shown that the dispersion affects the peak value of the spectral degree of polarization, and the higher order dispersion leads to a more obvious effect on the peak value of the spectral degree of polarization at the focal plane. On the z-axis, the spectral degree of polarization in the dispersion-free case is different form that in the dispersion case, however, the dispersion of different orders almost has the same effect on the spectral degree of polarization. The results obtained in this paper may be crucial for high precision laser detection.

7

Marginal Discriminant Projection for Coal Mine Safety Data Dimensionality Reduction

Zhao Z., Qian J., Cheng J.

Przegląd Elektrotechniczny

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2012

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R. 88, nr 9b

79-83

EN

Marginal Fisher Analysis (MFA) is a novel dimensionality reduction algorithm. However, the two nearest neighborhood parameters are difficult to select when constructing graphs. In this paper, we propose a nonparametric method called Marginal Discriminant Projection (MDP) which can solves the problem of parameters selection in MFA. Experiment on several benchmark datasets demonstrated the effectiveness of our proposed method, and appreciate performance was achieved when applying on coal mine safety data dimensionality reduction.

PL

W artykule zaproponowano nieparametryczna metodę nazwaną MDOP (marginal discriminant projection) która pomaga rozwiązać problem selekcji danych w algorytmie MFA (marginal Fisher analysis). Metodę zastosowano do redukcji danych w systemach bezpieczeństwa klopalni węglowych.

8

Review of the Photodecomposition of Some Important Energetic Materials

Sun Y., Shu Y., Xu T., Shui M., Zhao Z., Gu Y., Wang X.

Central European Journal of Energetic Materials

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2012

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Vol. 9, nr 4

411-423

EN

The photodecomposition mechanisms of energetic materials vary with molecular structure, photodissociation wavelength, the phase of the material, experimental pressure and temperature etc. In this paper, the significant progress on photodecomposition studies of some important energetic materials achieved in recent years is introduced in detail, including nitromethane, DMNA (dimethylnitramine), TATB (1,3,5-triamino-2,4,6-trinitrobenzene), RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine), HMX (1,3,5,7-tetranitro-1,3,5,7- tetrazacycloctane) and CL-20 (2,4,6,8,10,12-hexanitrohexaazaisowurtzitane). The difficulties and prospects of photodecomposition research of energetic materials are also indicated.

9

A new composition theorem for sp-weighted pseudo almost periodic functions and applications to semilinear differential equations

Zhao Z., Chang Y., N'Guerekata G. M.

Opuscula Mathematica

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2011

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Vol. 31, no. 3

457-474

EN

In this paper, we establish a new composition theorem for Sp-weighted pseudo almost periodic functions under weaker conditions than the Lipschitz ones currently encountered in the literatures. We apply this new composition theorem along with the Schauder's fixed point theorem to obtain new existence theorems for weighted pseudo almost periodic mild solutions to a semilinear differential equation in a Banach space.

10

ZnO/MgO distributed Bragg reflectors

Huo B., Hu L., Zhang H., Zhao Z., Fu Q., Chen X.

Optica Applicata

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2009

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Vol. 39, nr 1

169--174

EN

ZnO/MgO distributed Bragg reflectors (DBRs) are grown by pulsed laser deposition. DBR samples grown at the same temperature and the same pressure show obvious reflections in transmission spectra. If there is a standing wave in the ZnO layers, it is evident that the full width at half maximum of the ZnO peak in photoluminescence spectra could be decreased when the sample reflects more photons whose wavelength is about 380 nm.

11

Nano-sized micelles formed by self-assembling of polylactide(ethylene glycol) block copolymers in aqueous solutions

Yang L., Zhao Z., Wei J., Li S.

Engineering of Biomaterials

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2007

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Vol. 10, no. 63-64

16-18

12

Frequency Spectrum of Laser Ultrasonic Signals from Fibers and Particles Suspensions

Zhao Z., Törmänen M., Myllylä R.

Molecular and Quantum Acoustics

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2006

|

Vol. 27

319-326

EN

This paper studied fiber and particle suspensions using pulsed laser-induced ultrasonic waves. By analyzing the power spectrum of these wide frequency ultrasonic waves propagating through different suspensions, the paper demonstrates that acoustic attenuation caused by fibers has a larger effect on high frequency than on low frequency components. Since this phenomenon was not observed in solutions containing fines and particles, it is useful for determining a solution's fiber consistency and for measuring fiber and fines fractions in paper pulp. Moreover, the experiment also showed that, relative to measuring attenuation amplitude, the measured power spectrum is less affected by fiber flock, micro air bubbles, acoustic coupling and temperatures.

13

Method for measuring optical parameters in weakly absorbing turbid media

Zhao Z., Törmänen M., Myllylä R.

Optica Applicata

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2004

|

Vol. 34, nr 4

647-656

EN

This article develops a simple, yet effective technique of measuring optical parameters in weakly absorbing turbid samples. Although based on diffusion theory, this technique largely relaxes its strict non-boundary and spot source requirements by choosing a suitable source-detector distance. moreover, the technique is applicable not only to liquid samples, but also to solids or on-line measurements. Experimental results demonstrate that, measured by this method, the reduced scattering coefficients of intralipid suspensions are in good agreement with those obtained by other autors. The paper also reports on the application of this technique to scattering measurements in pulp.

14

Method for Measuring Optical Parameters in Weakly Absorbing Turbid Media

Zhao Z., Törmänen M., Myllylä R.

Molecular and Quantum Acoustics

|

2004

|

Vol. 25

257-267

EN

This article develops a simple, yet effective technique of measuring optical parameters in weakly absorbing turbid samples. Although based on diffusion theory, this technique largely relaxes its strict non-boundary and spot source requirements by choosing a suitable source-detector distance. Moreover, the technique is applicable not only to liquid samples, but also to solids or on-line measurements. Experimental results demonstrate that, measured by this method, the reduced scattering coefficients of intralipid suspensions are in good agreement with those obtained by other authors. The paper also reports on the application of this technique to scattering measurements in pulp.

15

Pulsed Photoacoustic Investigations in Liquid and Tissue

Zhao Z., Myllylä R.

Molecular and Quantum Acoustics

|

2002

|

Vol. 23

451-462

EN

This paper focuses on pulsed photoacoustic (PA) generation on liquid and tissue by the thermal elastic mechanism. The paper first provides a theoretical presentation of PA amplitude, waveshape and optical scattering. Then a set of experiments is carried aut to demonstrate the presented amplitude expressions and to give a qualitative explanation of waveshapes. Finally, the paper introduces an application based on the pulsed PA technique for the determination of glucose in human blood.