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1

Buckling and bending analyses of a novel functionally graded porous plate using Chebyshev-Ritz method

Chen D., Yang J., Kitipornchai S.

Archives of Civil and Mechanical Engineering

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2019

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Vol. 19, no. 1

157--170

EN

To address the interfacial failure problem while maintain the main advantageous features in layered sandwich structures, a novel functionally graded (FG) porous plate is proposed where the continuous gradient in material properties based on a graded porosity offers a smooth stress distribution along the plate thickness so that the remarkable stress mismatch that leads to interfacial failure in the conventional sandwich structures can be avoided. The FG porous plate is assumed to be made of closed-cell Aluminium foams with Young's modulus, shear modulus, mass density and Poisson's ratio varying across the thickness. The mechanical property of closed-cell solids is used to determine the relationship between porosity coefficient and mass density coefficient. Based on the first-order shear deformation plate theory, the governing equations are derived and then solved by employing Chebyshev polynomials based Ritz method. The uniaxial, biaxial and shear buckling loads, bending deflections and stresses are obtained for fully clamped and simply supported porous plates. Numerical results show that compared with the conventional layered sandwich plate with a uniform porous core, the proposed FG porosity can eliminate the stress mismatch and yield significantly improved buckling and bending performances, promoting the advance and application of porous structures in multiple engineering areas.

2

Generation of chirped microwave signal with any central frequency based on a nonuniformly spaced finite impulse response filter

Chen D., Wang R., Pu T., Xiang P., Fang T., Zheng J., Xiong J.

Optica Applicata

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2016

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Vol. 46, nr 3

399--408

EN

A novel optical approach to generating a chirped microwave signal by using a nonuniformly spaced finite impulse response filter is proposed and demonstrated. In this scheme, a narrowband Gaussian pulse is used as the original chirped-free signal, which is easy to be acquired. To eliminate the need of a wideband chirped-free signal, a mixer and a radio frequency signal are used to up-convert the spectrum of the original Gaussian signal. Therefore, the required frequency response can be calculated and reconstructed by a finite impulse response filter with nonuniformly spaced taps. Besides, a dual drive Mach–Zehnder modulator is used to realize single sideband modulation of the chirpedfree signal. Thus, the transfer function induced by the fiber dispersion is eliminated and the chirped microwave signal with any central frequency can be generated. In this paper, a design example of a filter with a central frequency of 10GHz is provided, and generation of the target chirped microwave signal is also demonstrated by numerical simulations.

3

Preliminary results of spatial distribution of uranium and thorium in soil profi les near a uranium industrial site, Guangdong province, China

Wang J., Liu J., Chen Y., Song G., Chen D., Xiao T., Li H., Wang C., Jiang F.

Nukleonika

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2016

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Vol. 61, No. 3

367--371

EN

Four soil profiles were collected from locations with different distances (5, 50, 250 and 1000 m) from a uranium mill tailings dam, Guangdong province, China, to investigate the pollution status of the soil in mining/ milling-related areas based on the contents of uranium (U) and thorium (Th), thus to understand the impacts of uranium industrial activities to the surroundings. The U and Th concentrations were determined by inductively coupled plasma mass spectrometry (ICP-MS) after conventional HF-HNO3-HClO4 digestion procedures. The results indicate that the soils within 50 m from uranium tailing were severely contaminated; those in 250 and 1000 m soil samples were observed to be with local background level even though these in 250 m had slightly higher U/Th ratios. Uranium concentrations varied from 5.50 ± 0.27 to 160.55 ± 8.03 mg/kg, with maximum values recorded in an intermediate layer of the 5-m distance soil profile. In comparison, the concentration of Th ranged from 6.02 ± 0.30 to 84.71 ± 4.24 mg/kg, with maximum values observed in the top layer of the 1000-m distance soil profile. The U/Th ratio varied from 0.15 to 11.99 compared with 0.20, 0.22 and 0.26 of the average for Guangdong province, national China and the world, respectively. The mean U/Th of four soil profiles showed a reduction with distance from the uranium mill tailing dam, suggesting the relatively large magnitude of uranium elevation in soils within limited distances.

4

Preparation of CaCO3-SiO2 composite with core-shell structure and its application in silicone rubber

Cui Ch., Ding H., Cao L., Chen D.

Polish Journal of Chemical Technology

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2015

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Vol. 17, nr 4

128--133

EN

A new CaCO3-SiO2 composite with core-shell structure was successfully prepared by mechano-chemistry method (MCM). SEM and FTIR indicated that SiO2 particles were homogeneously immobilized on the surface of CaCO3. The well dispersion of this CaCO3-SiO2 composite into silicone rubber can not only reduce the usage amount of SiO2, but also improve the mechanical properties of silicone rubber. By the calculation, the theoretical numbers of the SiO2 particles is about 10 times as large as that of CaCO3 particles in the CaCO3-SiO2 composite. Mixing CaCO3-SiO2 composite in silicone rubber can enhance the breaking strength of the silicone rubber about 18% as high as that when mixing the pure SiO2. And the elongation at break is about 14% less than that of adding the pure SiO2 sample.

5

A novel approach to photonic generation of periodic triangular radio frequency waveforms

Xiang P., Guo H., Chen D., Zhu H., Wu C.

Optica Applicata

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2015

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Vol. 45, nr 3

381--391

EN

A novel approach to photonic generation of triangular radio frequency waveforms with a tunable repetition rate is proposed and analyzed. In the proposed system, a continuous-wave light is modulated by a reference microwave signal through a polarization modulator, and then its output optical sidebands are manipulated by a microwave photonic filter with a negative tap. By properly adjusting the system parameters, full-duty-cycle triangular radio frequency waveforms can be generated after optical-to-electrical conversion, and its repetition rate (frequency) can be tuned in a wide range. A model describing the proposed system is derived, which is verified via computer simulations.

6

Optical generation of ultra-wideband signals with a reconfigurable spectral notch-band

Xiang P., Chen Y., Chen D., Zhao J.

Optica Applicata

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2014

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Vol. 44, nr 3

411--419

EN

A novel method for optical generation of ultra-wideband signals with a reconfigurable spectral notch-band is proposed. In the proposed system, ultra-wideband signals are generated in the optical domain and an optical tunable delay line is deployed to introduce a notch-band to the spectral profile of the generated ultra-wideband signals, which can effectively avoid the signal interference between ultra-wideband signals and pre-planned narrowband wireless signals used in wireless local area networks (WLAN). A theoretical model describing the proposed system is derived; the optical generation and fiber transmission of ultra-wideband signals with a reconfigurable notch-band are demonstrated via computer simulations.

7

Comparison and Analysis of Magnetic-Geared Permanent Magnet Electrical Machine at No-Load

Liu X., Chen D., Yi L., Zhang Ch., Wang M.

Archives of Electrical Engineering

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2014

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Vol. 63, nr 4

683--692

EN

Magnetic-geared permanent magnet (MGPM) electrical machine is a new type of machine by incorporating magnetic gear into PM electrical machine, and it may be in operation with low-speed, high-torque and direct-driven. In this paper, three types of MGPM machines are present, and a quantitative comparison among them is performed by finite element analysis (FEA). The magnetic field distribution, stable torque and back EMF are obtained at no-load. The results show that three types of MGPM machine are suitable for different application fields respectively according to their own advantages, such as high torque and back EMF, which form an important foundation for MGPM electrical machine research.

8

Effects of Mechanical Properties of Fabrics on Clothing Pressure

Chen D., Liu H., Zhang Q., Wang H.

Przegląd Elektrotechniczny

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2013

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R. 89, nr 1b

232--235

EN

To investigate how elastic modulus, elongation and relaxation time of fabric influence clothing pressure, the pressure on cylinder model was measured. The fabrics used were cotton spandex and polyester spandex elastic knitted fabric. The fabrics were sewed as 100mm high cylinders. The fabric cylinders with different elongation and with elongation 20% at different relaxation time pressed the cylinder model, and the pressure was measured. By analyzing data, it was found that clothing pressure increases linearly with the increase of fabric elongation basically when fabric elongation was within 60% . The clothing pressure exerted by fabric whose elastic modulus is greater is generally higher than that by fabric whose elastic modulus is lower when elongation was the same. The clothing pressure presents a trend of first order exponential decay with the passage of relaxation time, and the main pressure decrease happens within the first 30 minutes, subsequently, the pressure decreases slowly and tends to be stable ultimately. And the decrease caused by relaxation properties of fabric accounts for a little of total pressure.

PL

W artykule badaniom poddano cylindryczny model, wykonany z różnych rodzajów materiału. Oceniono wpływ współczynnika elastyczności, czas wydłużenia i ściągnięcia na ciśnienie wywierane przez tkaninę. Analiza danych wykazała, że wywierane ciśnienie rośnie liniowo wraz ze wzrostem wydłużenia, zwłaszcza do 60%. Ponadto jego zanik ma charakterystykę wykładniczą pierwszego rzędu a główny spadek następuje w ciągu pierwszych 30 min potem opada wolno.

9

Comparative Study of Ordered and Covering Information Systems

Wang C., He Q., Chen D., Hu Q.

Fundamenta Informaticae

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2013

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Vol. 123, nr 3

351--363

EN

Covering information systems and ordered information systems are two important types of information systems. In this paper the relationships between covering information systems and ordered information systems are first examined, and it is proved that these two types of information systems are isomorphic under given conditions and can be equivalently transformed into each other. Then, the approach to attribute reduction in ordered information systems is proposed. Based on the isomorphism and equivalence of transformation, the method of attribute reduction in a covering information system can be directly obtained according to the reduction approach in an ordered in- formation system. A practical example is employed to show that the proposed method is an effective technique to deal with complex data sets.

10

Catalytic decomposition of toluene over La1-xSr xMnO3/palygorskite synthesized catalysts

Song L., Chen T., Chen D., Chen Y., Xie J., Liu H.

Environment Protection Engineering

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2013

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Vol. 39, nr 3

31--42

EN

Palygorskite (PG) supported La1-xSrxMnO3 catalysts were fabricated by copreripitation. The catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), specific surface area (SSA) and H2 temperature programmed reduction (H 2-TPR). Catalytic activity for VOCs was examined by using toluene as a model compound. The results show that the surface area as well as mechanical strength of catalysts increase substantially after catalysts loaded in PG. XRD patterns show that after calcination at 700 0C, PG as a support in 9% LaMn03/PG and 9% La0.7Sr0.3MnO3/PG was transformed into amorphous phase and the morphology was not destroyed. It was well established that the main reductive components are factually Mn(III) or Mn(IV) oxides in catalysts based on the results of TPR. It was also found that Mn(IV) increases while Mn(III) reduces responding with the increasing amount of Sr. Toluene conversion rate of as-preparedμ% La1-xSr xMnO3/PG increases with the increasing values of x and μ when x=0-0.3 and μ = 3-9%. Toluene can be converted completely at 285 0C by 9% La0.7Sr0.3MnO3/PG catalyst while no significant change was observed after addition on the doping and loading amount of Sr. During a 100 h stability experiment of 9% La 0.7Sr0.3MnO3/PG catalyst, toluene removal was found to be above 95%.

11

A PCG-PSO Image Reconstruction Algorithm For Electrical Capacitance Tomography System

Chen Y., Cao J., Chen D.

Przegląd Elektrotechniczny

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2012

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R. 88, nr 9b

37-41

EN

To solve the ‘soft-field’ nature and the ill-posed problem in electrical capacitance tomography (ECT) technology, this paper first presents a preconditioned conjugate gradient iterative algorithm for electrical capacitance tomography (PCG), Then, the results of the PCG algorithm using PSO method for imaging gray scale compensation.

PL

Artykuł przedstawia algorytm PCG (preconditioned conjugate gradient) do rekonstrukcji obrazu w elektrycznej pojemnościowe tomografii. Skala szarosci jest rekonstruowanoa przy wykorzystanoiu algorytmu PSO (particle swarm optimization).

12

Active phase-setting twin-frequency grating for 3D shape measurement based on an absolute phase unwrapping algorithm

Huang Z, Cao Y, Zhai A, Li Y, Chen D

Optica Applicata

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2012

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Vol. 42, nr 4

887--900

EN

An active phase-setting twin-frequency grating based on an absolute phase unwrapping algorithm is proposed to measure the object with a complex shape. Two sinusoidal components with a spacial period ratio are combined into a twin-frequency grating, and two different initial phases are preset in two sinusoidal components, one of which is constant in a low-frequency component and the other is related to the ratio of two periods in a high-frequency component. Using the active phase-setting twin-frequency grating, two wrapped phases can be obtained from nine frames of distorted patterns by a regular phase shifting. Thus, the high-quality wrapped phase of a high-frequency component can be unwrapped by using an absolute phase unwrapping algorithm. Compared with a previous study based on a non-integral twin-frequency grating, the proposed grating needs a less number of patterns and the absolute phase unwrapping algorithm is easier to implement, so the proposed method is time-saving. The experimental results demonstrate that these achievements saved 90 percent of time approximately.

13

Kernelized Fuzzy Rough Sets Based Yawn Detection for Driver Fatigue Monitoring

Du Y., Chen D., Hu Q., Ma P.

Fundamenta Informaticae

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2011

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Vol. 111, nr 1

65-79

EN

Driver fatigue detection based on computer vision is considered as one of the most hopeful applications of image recognition technology. The key issue is to extract and select useful features from the driver images. In this work, we use the properties of image sequences to describe states of drivers. In addition, we introduce a kernelized fuzzy rough sets based technique to evaluate quality of candidate features and select the useful subset. Fuzzy rough sets are widely discussed in dealing with uncertainty in data analysis. We construct an algorithm for feature evaluation and selection based on fuzzy rough set model. Two classification algorithms are introduced to validate the selected features. The experimental results show the effectiveness of the proposed techniques.

14

The effect of cryogenic treatment on the microstructure and mechanical properties of Cu46Zr46Al8 bulk metallic glass matrix composites

Ma G. Z., Chen D., Chen Z. H., Liu J. W., Li W.

Materials Science Poland

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2010

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Vol. 28, No. 2

595--601

EN

The influence of cryogenic treatment (CT) on the microstructure and mechanical properties of Cu46Zr46Al8 glassy matrix composite fabricated by the process copper of mould suction casting. The distribution and morphology of test samples of CuZr phase changed under CT. After CT, the second phase is distributed more homogenously, and the morphology was transformed from dendrites to plates. This change in the microstructure improved the mechanical properties of the composite. Although compression fracture was still the brittle mode, the compression fracture strength was improved greatly after CT. Due to the morphological changes, the microhardness was increased about 18.55% when the treatment time was 72 h.

15

Separation of two isomers of benzocarbazoles by ß-cyclodextrin modified micellar electrokinetic capillary chromatography

Shi X., Ma W., Chen D.

Chemia Analityczna

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2001

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Vol. 46, No. 3

433-438

EN

To optimize the separation conditions of the two isomers of benzocarbazoles, micellar electrokinetic capillary electrophoresis (MECC) was employed in this study. In this procedure, a fused silica capillary of 57 cm x 50 um (50 cm to detector) was used. Running buffer was 5.0 mmol 1(-1) aqueous sodium tetraborate solution containing 70 mmol1 (-1) sodium dodecyl sulfate (pH9.16) and 20 mmol 1(-1) p-cyclodextrin. The separation voltage and the pH value of the buffer were optimized. At the optimized separation conditions, the two isomers were separated well within 10 min. It is thus proved that MECC is an effective method for oil chemical exploration.

PL

W celu optymalizacji rozdzielania dwóch izomerów benzokarbazoli zastosowano mice-larną elektrokinetyczną kapilarną chromatografię. Stosowano kapilary z topionego kwarcu o wymiarach 57 cm x 50 urn, przy odległości 50 cm do detektora. Jako bufor zastosowano 5 mmol 1(-1) roztwór wodny tetraboranu sodowego, zawierający 70 mmol 1(-1)dodecylosiarczan sodowy (pH 9,16) i 20 mmol 1(-1) p-cykodekstrynę. Optymalizowano napięcie i wartość pH buforu. W wybranych warunkach rozdzielania oba izomery ulegają dobremu rozdzieleniu w ciągu 10 min co może być wykorzystane przy identyfikacji złóż ropy.