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Zhihong Zhao,Jianfeng Zhao 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6
The energy storage system plays an important role in the distributed network, and the three-level converter has a smaller du/dt of output voltage compared with the two-level converter. This paper focus on the modeling and voltage balance control of a three-level energy storage system with dual active bridge dc-dc converter. The small signal model of the dual active bridge is proposed, which enables the output voltage and current to be controlled simultaneously. Besides, an improved voltage balancing technique for a three-level converter is presented, which makes a good tradeoff between the dc-link capacitor ripple voltage attenuation and the power device switching action reduction. Finally the system is tested by MATLAB/SIMULINK, and the experimental results are presented.
Asymmetric Key Pre-distribution Scheme for sensor networks
Zhihong Liu,Jianfeng Ma,Qiping Huang,SangJae Moon IEEE 2009 IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS Vol.8 No.3
<P>A key pre-distribution scheme is a method by which initially an off-line trusted authority distributes pieces of information among a set of users. Later, each member of a group of users can compute a common key for secure communication. In this paper we present an asymmetric key pre-distribution scheme. Instead of assuming that the network is comprised entirely of identical users in conventional key pre-distribution schemes, the network now consists of a mix of users with different missions, i.e., ordinary users and keying material servers. A group of users, using secret keys preloaded in their memory and public keying material retrieved from one keying material server, can compute a session key. The properties of this method are that, the compromise of keying material servers does not reveal any information about users' secret keys and the session keys of privileged subset of users; if computational assumptions are considered, each user has very low storage requirement. These properties make it attractive for sensor networks. We first formally define the asymmetric key pre-distribution scheme in terms of the entropy and give lower bounds on user's storage requirement and the public keying material size. Then, we present its constructions and applications for sensor networks.</P>
Study on Personalized Course Generation Based on Layered Recommendation Algorithm
Zhihong Wang 보안공학연구지원센터 2015 International Journal of Multimedia and Ubiquitous Vol.10 No.2
The paper introduces the concept of a layered recommendation system (LRS) based on multi-dimensional feature vectors to implement personalized course generation model and algorithms. In this work, we present a personalized course generation algorithm based on the multi-dimensional feature vectors (PCG-LRS) and hybrid applications by content-based recommendations and collaborative filtering recommendation algorithm to generate personalized curriculums. Based on this algorithm, we introduce the teaching outline as the basis of the initial generated course and the final learning goals. The knowledge base of the courses can be constructed from the teaching outline. The initial personalized knowledge models of students are generated by pre-tests. These personalized knowledge models are the base of personalized course generation. This algorithm not only helps teachers to develop the overall curriculum teaching plan and to generate the curriculum automatically, but also meets the learning requirements of each individual student with different knowledge and abilities. Additionally, the layered recommendation algorithm recommends content within a large-scale knowledge base repository and resource base implement at different levels. The personalized recommendation algorithm is divided into a number of steps, which achieves an effective dimensionality reduction, reduces the amount of computation, and improves the courses generated algorithm.
Zhihong Ma,Zhanjun Lv,Xiu-Fang Wang,Xiangyang Jing,Jianjun Cheng 한국유전학회 2014 Genes & Genomics Vol.36 No.4
Cis-regulatory elements are regions of DNAthat regulate the expression of genes located on that samemolecule of DNA. Though these elements are important forgene expression regulation, the functions of cis elementsremain largely unknown. To explore the mechanisms ofgene activation by short sequence enhancers, we examinedthe enhancer activity of short sequence DNA and itsderived sequences using a GFP expression system. Wefound that AA sequence (50-GTGAAATAAATGCAAATAAAGT) induced strong GFP gene expression, while7pieA (50-GTGAAAAAAATGCAAAAAAAGT) did not. We mutated the five T bases of the AA sequence to A, C orG. Our findings indicated that sequences retaining the 7thand/or 17th Ts possessed strong enhancer activity. RT-PCRand RNA synthesis inhibition analysis using actinomycin Drevealed that the enhanced GFP gene expression inducedby the AA sequence occurred at the transcriptional level. To determine whether the AA sequence formed a secondarystructure via atypical complementation, PAGE methodwas used, and the results showed that the AA sequenceformed a secondary structure. Our results support previousevidence that AATAAA is an important composition of ciselements (enhancer/promoter), and suggest that the formationof an unstable stem-loop structure via atypicalcomplementation may be a new mechanism of enhanceractivity.
Enhanced Supercapacitive Performance of Carbonized Polyaniline by Conducting Wrapping
Zhihong Luo,Xiangqun Zhuge,Yuzhen Zhao,Meixiao He,Lihua Zhu,Heiqing Tang,Kun Luo 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2015 NANO Vol.10 No.8
Functionalized carbon nanotubes (MWNT–COOH) was selected as conducting wrapping agent to prepare composites of MWNT–COOH and carbonized polyaniline (C–PANI), to improve the supercapacitive performance of C–PANI. The morphology was characterized by scanning electron microscope and transmission electron microscope which showed that C–PANI was trapped in the conductive network of MWNT–COOH. The electrochemical measurement results indicated the increased specific capacitance and enhanced cycling stability of C–PANI with the addition of MWNT–COOH. When the weight ratio of C–PANI and MWNT–COOH was 4:1, the specific capacitance of the composites was 149 F g-1, and the capacitance retention was 93.7% after 1000 charge–discharge cycling.
Zhihong Yang,Bing Li 국제구조공학회 2022 Structural Engineering and Mechanics, An Int'l Jou Vol.83 No.2
As the main lateral load resisting system in high-rise reinforced concrete structures, the mechanical performance of shear wall has a significant impact on the structure, especially for high-rise buildings. Steel corrosion has been recognized as an important factor affecting the mechanical performance and durability of the reinforced concrete structures. To investigate the effect on the seismic behaviour of corroded reinforced concrete shear wall induced by corrosion, analytical investigations and simulations were done to observe the effect of corrosion on the ultimate seismic capacity and drift capacity of shear walls. To ensure the accuracy of the simulation software, several validations were made using both non-corroded and corroded reinforced concrete shear walls based on some test results in previous literature. Thereafter, a parametric study, including 200 FE models, was done to study the influence of some critical parameters on corroded structural shear walls with boundary element. These parameters include corrosion levels, axial force ratio, aspect ratio, and concrete compressive strength. The results obtained would then be used to propose equations to predict the seismic resistance and drift capacity of shear walls with various corrosion levels.
A Common Bitmap Block Truncation Coding for Color Images Based on Binary Ant Colony Optimization
( Zhihong Li ),( Qiang Jin ),( Chin-chen Chang ),( Li Liu ),( Anhong Wang ) 한국인터넷정보학회 2016 KSII Transactions on Internet and Information Syst Vol.10 No.5
For the compression of color images, a common bitmap usually is generated to replace the three individual bitmaps that originate from block truncation coding (BTC) of the R, G and B channels. However, common bitmaps generated by some traditional schemes are not the best possible because they do not consider the minimized distortion of the entire color image. In this paper, we propose a near-optimized common bitmap scheme for BTC using Binary Ant Colony Optimization (BACO), producing a BACO-BTC scheme. First, the color image is compressed by the BTC algorithm to get three individual bitmaps, and three pairs of quantization values for the R, G, and B channels. Second, a near-optimized common bitmap is generated with minimized distortion of the entire color image based on the idea of BACO. Finally, the color image is reconstructed easily by the corresponding quantization values according to the common bitmap. The experimental results confirmed that reconstructed image of the proposed scheme has better visual quality and less computational complexity than the referenced schemes.