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Effect of carbon black on properties of 0–3 piezoelectric ceramic/cement composites
Huang Shifeng,Li Xue,Liu Futian,Chang Jun,Xu Dongyu,Cheng Xin 한국물리학회 2009 Current Applied Physics Vol.9 No.6
0–3 cement-based piezoelectric composites were fabricated using sulphoaluminate cement and piezoelectric ceramic [0.08Pb(Li1/4Nb3/4)O3 . 0.47PbTiO3 . 0.45PbZrO3] [P(LN)ZT] as raw materials by compressing technique. The influences of carbon black content on the piezoelectric and dielectric properties, electric conductivity and impedance were investigated. The results indicate that the piezoelectric strain constant d33 and piezoelectric voltage constant g33 of the composites increase gradually with a suitable carbon black addition. When the carbon black content is 0.3 wt%, both of the piezoelectric strain constant d33 and piezoelectric voltage constant g33 of the composite exist the maximum value, which are 17.45 pC N-1 and 36.3 mV m N-1, respectively. As the carbon black content increases, the dielectric constant εr, dielectric loss tanδ and electric conductivity σ of the composites all increase, while the impedance decreases. In the frequency range tested, the more the carbon black content, the higher the εr value. The planar electromechanical coupling coefficient Kp, the thickness electromechanical coupling coefficient Kt and the mechanical quality factor Qm are almost unaffected by the carbon black content.
Layered Formation-containment Control of Multi-agent Systems in Constrained Space
Dongyu Li,Shuzhi Sam Ge,Guangfu Ma,Wei He 제어·로봇·시스템학회 2020 International Journal of Control, Automation, and Vol.18 No.3
This paper addresses the layered formation-containment (LFC) problem for multiagents in the constrained space with a directed communication topology. The formation-containment problem is first defined using a layered framework, and a layered distributed finite-time estimator is proposed to acquire the target states for agents in each layer. Based on the proposed framework, the formation configuration and the mechanism of the information flow can be explored and designed naturally. To avoid collisions with borders, obstacles, as well as the other agents in the constrained space, an artificial potential function is designed based on the Dirac delta function. Further, a disturbance observer and adaptive neural networks (NNs) are applied to respectively tackle the external disturbance and the model uncertainties. The desired formation of each layer can be achieved while no collision occurs in the constrained space. The semi-global uniform ultimate boundedness of closed-loop errors is guaranteed by Lyapunov stability theory. Simulation results are given to show the effectiveness of the proposed approaches.
Research on Metadata Management in Cloud Computing
Dongyu Li 보안공학연구지원센터 2016 International Journal of Database Theory and Appli Vol.9 No.2
Existing metadata management methods bring about lower access efficiency in solving the problem of renaming directory. This paper proposes a metadata management method based on directory path redirection (named as DPRD) which includes the data distribution method based on directory path and the directory renaming method based on directory path redirection. Experiments show that DPRD effectively solves the lower access efficiency caused by the renaming directory.
Sustainable Development of Indonesia`s Agricultural Sector
( Eng Seng Chia ),( Dongyu Li ),( Xutong Ma ),( Jixi Wang ),( Yiting Wang ),( Jiaxu Zhu ) 한국시스템다이내믹스학회 2016 한국시스템다이내믹스 연구 Vol.17 No.4
The Indonesian agricultural output has been struggling to provide for the demand of the rising population in recent years owing to the sluggish growth rate in this sector as compared to the overall performance of the economy. While the current slash-and-burn technique widely employed by Indonesian peasants is able to boost the output in the short term, its negative implications on the environment and the constraints in available forest area casts doubts to its sustainability in the long run. As the results from our iThink model simulation has illustrated, the output will cease increasing and decline in about 90 years” time due to the drastic drop in forest coverage. Based on the sensitivity analysis of the affecting factors, three policy amendments are proposed to avert the gloomy perspective, namely increasing funding for Research and Development, curbing burning activities, and actively returning abandoned land to forests. With the effective implementation of the suggested policies, the growth in the agricultural sector will be steered back to a sustainable track, which is further confirmed by the model projection.
Tian Ai,Xiaojun Jiang,Hongmei Yu,Hong-Bo Xu,Dawei Pan,Qingyu Liu,Dongyu Chen,Jinyang Li 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.2
Two biosorbents were prepared using bamboo powder modified with mercaptoacetic acid and carbondisulfide, which exhibits strong adsorption properties for Cu2+ and Ni2+. The obtained materials were characterized byFTIR. Maximum adsorption for both metals was found to occur around pH 5.0-6.5. The kinetic data followed thepseudo-second-order model. The maximum adsorption capacities of Cu2+ and Ni2+ on mercaptoacetic acid modifiedbamboo powder determined from Langmuir isotherm were 103.97mg g−1 and 61.35mg g−1, respectively. While oncarbon disulfide modified bamboo powder were 128.21mg g−1 and 56.82mg g−1, respectively. The adsorption mechanismanalysis revealed that the most possible adsorption mode of Cu2+ was coordination, and Ni2+ was ion exchange. The obtained adsorbents could effectively remove Cu2+ and Ni2+ from industrial electroplating wastewater and could beused repeatedly for more than five cycles.
A Fault Diagnosis of ZPW-2000A Tuning Area based on the WNN
Dong Yu,Li Ya-lan,Nan Jie-long 보안공학연구지원센터 2015 International Journal of Multimedia and Ubiquitous Vol.10 No.3
With the rapid development of china railway, ZPW-2000A track circuit has been widely used. Tuning area, which is an important part of the ZPW-2000A track circuit, is not only the relationship between the signal transmission quality, and determine the effect of electrical insulation between adjacent sections. Therefore, the study of fault diagnosis aspects for tuning area is urgent and significant. In this paper, using the theory of transmission line a model of track circuit is built, the comparison of the actual data and experimental data of the track surface voltage envelope curve shows the correctness of this model. Owning to the good time-frequency characteristics of wavelet and the nonlinear mapping features of neural network, a fault diagnosis of ZPW-2000A tuning area based on the wavelet neural network(WNN) is proposed. Combined with the practical failure situation of railway site, the fault diagnosis method in this paper can accurately identify failure modes of tuning area.