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      • KCI등재

        Rhombohedraleorthorhombic phase coexistence and electrical properties of Ta and BaZrO3 co-modified (K, Na)NbO3 lead-free ceramics

        Binyu Zhang,Jiagang Wu,Xiaopeng Wang,Xiaojing Cheng,Jianguo Zhu,Dingquan Xiao 한국물리학회 2013 Current Applied Physics Vol.13 No.8

        The BaZrO3 and Ta have been used to improve piezoelectric properties of (K, Na)NbO3 ceramics by the construction of the phase boundary, and (1 x)K0.48Na0.52(Nb0.95Ta0.05)O3exBaZrO3 [(1 x)KNNTexBZ]ceramics were prepared by the conventional solid-state method. The effect of BZ content on their phase structure, microstructure, and electrical properties has been investigated. A rhombohedral and orthorhombic phase coexistence has been observed in the compositional range of 0.05 x 0.07. With increasing BZ content, their Tc and Toet values decrease gradually, and the dielectric constant increases linearly. The ceramic with x ¼ 0.06 exhibits an enhanced piezoelectric behavior (d33 w 193 pC/N and kp w 32.6%) because of the coexistence of two phases together with a dense microstructure. As a result,the construction of a rhombohedral and orthorhombic phase boundary is an effective way to improve the piezoelectric properties of KNN-based ceramics.

      • KCI등재

        Secure and Fine-grained Electricity Consumption Aggregation Scheme for Smart Grid

        ( Gang Shen ),( Yixin Su ),( Danhong Zhang ),( Huajun Zhang ),( Binyu Xiong ),( Mingwu Zhang ) 한국인터넷정보학회 2018 KSII Transactions on Internet and Information Syst Vol.12 No.4

        Currently, many of schemes for smart grid data aggregation are based on a one-level gateway (GW) topology. Since the data aggregation granularity in this topology is too single, the control center (CC) is unable to obtain more fine-grained data aggregation results for better monitoring smart grid. To improve this issue, Shen et al. propose an efficient privacy-preserving cube-data aggregation scheme in which the system model consists of two-level GW. However, a risk exists in their scheme that attacker could forge the signature by using leaked signing keys. In this paper, we propose a secure and fine-grained electricity consumption aggregation scheme for smart grid, which employs the homomorphic encryption to implement privacy-preserving aggregation of users’ electricity consumption in the two-level GW smart grid. In our scheme, CC can achieve a flexible electricity regulation by obtaining data aggregation results of various granularities. In addition, our scheme uses the forward-secure signature with backward-secure detection (FSBD) technique to ensure the forward-backward secrecy of the signing keys. Security analysis and experimental results demonstrate that the proposed scheme can achieve forward-backward security of user’s electricity consumption signature. Compared with related schemes, our scheme is more secure and efficient.

      • SCOPUSKCI등재

        Analysis of the Influence of Guide Vane Wrap Angle and Number of Blades on the Propulsion Performance of a Water-Jet Propeller

        Wei Han,JianDong Mi,SiCong Zhang,Jun Xu,BinYu Qin 한국유체기계학회 2021 International journal of fluid machinery and syste Vol.14 No.4

        For water-jet propellers, the geometry size of the guide vane change can effectively improve the performance of the pump. If other parameters remain unchanged, CFD numerical simulation of the guide vane number and wrap angle of the change can be used to effectively adjust the operation conditions of the pump. The relationship between the changes in pump head, pump efficiency, and water-jet propeller propulsive efficiency can be used, to find the best guide vane parameters to achieve the highest thrust efficiency. The calculation results show that an increase in the guide vane number coefficient and wrap angle coefficient will reduce size of the pump head. Meanwhile, an increase in the wrap angle coefficient and the guide vane number coefficient will reduce the propulsive efficiency of the whole water-jet propeller. In this experiment, it was found that the propulsion effect is best when the guide vane number coefficient remains unchanged and the wrap angle coefficient is 1.

      • Nonsubsampled Contourlet Transform Based Infrared Image Super-Resolution by Using Sparse Dictionary and Residual Dictionary

        Kangli Li,Wei Wu,Xiaomin Yang,Yingying Zhang,Binyu Yan,Wei Lu,Gwanggil Jeon 보안공학연구지원센터 2016 International Journal of Multimedia and Ubiquitous Vol.11 No.7

        Due to the limitation of hardware, Infrared (IR) image has low-resolution (LR) and poor visual quality. To enhance the Infrared image’s resolution, super-resolution (SR) is a good solution. However, the conventional SR methods have some drawbacks. Firstly, the trained dictionary is an unstructured dictionary, which may lead to worse results. Secondly, the representation of the image is too simple to effectively represent image. Finally, only one high-resolution (HR)-LR dictionary pair is adopted to infer HR IR image. However one HR-LR dictionary pair is not good enough to obtain good results. To resolve these problems, in this paper, firstly, the sparse dictionary is introduced into the IR image SR to get better results. Secondly, nonsubsampled contourlet transform (NSCT) is employed to obtain a better representation of IR image. Finally, to achieve better r-esults, two HR–LR sparse dictionary pairs, which consists of a primitive sparse dictionary pair and a residual sparse dictionary pair, instead of one HR-LR dictionary pair are adopted. The experiment results indicate that the subjective visual effect and objective evaluation acquire excellent performance in the proposed method. Besides, this method is superior to other methods.

      • KCI등재

        Phase structure, electrical properties, and stability of 0.96(K0.48Na0.52)1xLixNbO3e0.04Bi0.5Na0.5ZrO3 lead-free piezoceramics

        Xiaopeng Wang,Jia-gang Wu,Ting Zheng,Xiaojing Cheng,Binyu Zhang,Dingquan Xiao,Jian-guo Zhu 한국물리학회 2014 Current Applied Physics Vol.14 No.5

        In this work, 0.96(K0.48Na0.52)1xLixNbO3e0.04Bi0.5Na0.5ZrO3 lead-free piezoceramics were prepared using the conventional solid state reaction method in order to attain both a high TC and an enhanced d33. The effect of Li content on their phase structure, electrical properties, and stability was systematically investigated. These results indicate that adding Li could result in the increase of TC and the decrease of TOeT. Here we obtain the ceramics with an orthogonaletetragonal phase boundary in the composition of x ¼ 0.02, and then enhanced piezoelectric properties and a high Curie temperature (i.e., d33 w 255 pC/N, kp w 41%, and TC w 360 C) were observed, showing the realization of our objective. In addition, a good stability of piezoelectric and ferroelectric properties has been shown in such a material system.

      • MPC-based FTC with FDD against Actuator Faults of UAVs

        Bin Yu,Youmin Zhang,Yaohong Qu 제어로봇시스템학회 2015 제어로봇시스템학회 국제학술대회 논문집 Vol.2015 No.10

        The increasing development of unmanned aerial vehicles (UAVs) and the requirements of high autonomy and safety levels require that the controller of UAVs should possess fault-tolerant/reconfigurable function to accommodate unpredicted situations such as actuator faults, sensor faults, or aircraft damage. This paper addresses the partial loss of control effectiveness (LOE) of actuators in a quadrotor UAV using model predictive control (MPC) with terminal constraints, which allows to track a reference command even if in the presence of actuator faults. The proposed faulttolerant control system (FTCS) adopts MPC technique to design fault-tolerant controller and state-augmented Kalman filter (SAKF) to achieve fault detection and diagnosis (FDD) function. Simulation results based on a quadrotor UAV demonstrate that the proposed fault-tolerant controller has a good performance in accommodating actuator faults.

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