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Search Results: 1 - 10 of 61794 matches for " Zhi Xu "
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A New ALS Based PMS Design and Its Evaluations  [PDF]
Zhi Xu, Daoqing Jiang
World Journal of Nuclear Science and Technology (WJNST) , 2016, DOI: 10.4236/wjnst.2016.61001
Abstract: Westinghouse company (WEC) had developed a Nuclear Regulatory Commission (NRC) approved advanced logic system (ALS) platform based on field programmable gate array (FPGA) technology as the next generation 1E class platform for protection and monitoring system (PMS) development for nuclear power plants. In compliance with the requirements of typical PMS functions, a new ALS based PMS is designed by overcoming the restrictions of communication modules etc. The consistency with data communication independence and isolation, deterministic, diversity requirements etc. is analyzed. The evaluations indicate the design meets the requirements and can be applied for coming projects.
A Minimal Periods Algorithm with Applications
Zhi Xu
Computer Science , 2009, DOI: 10.1007/978-3-642-13509-5_6
Abstract: Kosaraju in ``Computation of squares in a string'' briefly described a linear-time algorithm for computing the minimal squares starting at each position in a word. Using the same construction of suffix trees, we generalize his result and describe in detail how to compute in O(k|w|)-time the minimal k-th power, with period of length larger than s, starting at each position in a word w for arbitrary exponent $k\geq2$ and integer $s\geq0$. We provide the complete proof of correctness of the algorithm, which is somehow not completely clear in Kosaraju's original paper. The algorithm can be used as a sub-routine to detect certain types of pseudo-patterns in words, which is our original intention to study the generalization.
Multi-Shift de Bruijn Sequence
Zhi Xu
Computer Science , 2010,
Abstract: A (non-circular) de Bruijn sequence w of order n is a word such that every word of length n appears exactly once in w as a factor. In this paper, we generalize the concept to a multi-shift setting: a multi-shift de Bruijn sequence tau(m,n) of shift m and order n is a word such that every word of length n appears exactly once in w as a factor that starts at index im+1 for some integer i>=0. We show the number of the multi-shift de Bruijn sequence tau(m,n) is (a^n)!a^{(m-n)(a^n-1)} for 1<=n<=m and is (a^m!)^{a^{n-m}} for 1<=m<=n, where a=|Sigma|. We provide two algorithms for generating a tau(m,n). The multi-shift de Bruijn sequence is important in solving the Frobenius problem in a free monoid.
The Initial Parameters Design of the Voltage Source Converter Fed SMES  [PDF]
Xudong Song, Zhi Xu, Tieyuan Xiang
Smart Grid and Renewable Energy (SGRE) , 2010, DOI: 10.4236/sgre.2010.12013
Abstract: The initial parameters of the superconducting magnetic energy storage (SMES) fed by a voltage source converter (VSMES) are studied and the setting rules are designed in this paper. A time-domain simulation model is established by using the software PSCAD/EMTDC. Based on this model, the application of the VSMES in the power system is used to test the designed rules. The simulation results are valuable for the further research of the initial parameters design of the VSMES.
A Retrieval Matching Method Based Case Learning for 3D Model  [PDF]
Zhi Liu, Qihua Chen, Caihong Xu
Journal of Software Engineering and Applications (JSEA) , 2012, DOI: 10.4236/jsea.2012.57053
Abstract: The similarity metric in traditional content based 3D model retrieval method mainly refers the distance metric algorithm used in 2D image retrieval. But this method will limit the matching breadth. This paper proposes a new retrieval matching method based on case learning to enlarge the retrieval matching scope. In this method, the shortest path in Graph theory is used to analyze the similarity how the nodes on the path between query model and matched model effect. Then, the label propagation method and k nearest-neighbor method based on case learning is studied and used to improve the retrieval efficiency based on the existing feature extraction.
DnaJ-like protein gene sll1384 is involved in phototaxis in Synechocystis sp. PCC 6803
Zhi Chen,XuDong Xu
Chinese Science Bulletin , 2009, DOI: 10.1007/s11434-009-0674-5
Abstract: In Synechocystis sp. PCC 6803, gene sll1384 encodes a protein with a DnaJ domain at its N-terminal portion and a TPR domain at the C-terminal portion. An sll1384 mutant shows no difference from the wild type in adaptation to different temperatures, but almost completely loses its capability of phototactic movement. After complementation with sll1384, the mutant regains the phototaxis. As shown with electron microscopy, on the cell surface, mutant cells have pili that appear to be the same as that of the wild type. Also, the transformation efficiency remains unchanged in the mutant. It is postulated that Sll1384 regulates phototaxis of Synechocystis through protein-protein interaction. It is the first DnaJ-like protein gene identified in a cyanobacterium for a role in phototaxis.
Prox1 Facilitates Transfected CHO Cell Proliferation through Activation of the AKT Signaling Pathway
Shang-Zhi Xu
International Journal of Biomedical Science , 2011,
Abstract: The homeobox transcription factor Prox1 plays an important role in the development of many embryonic organs. Previous studies indicated that Prox1 facilitates hepatic progenitor-cells proliferation. However, the underlying mechanism of Prox1 in tumor genesis, formation, and progression are poorly understood and need to be exploited. Herein, Chinese Hamster Ovary (CHO) cells were transfected and over-expressed human recombinant Prox1 gene, and developed several stable cell lines of Prox1-CHO after screening. The results indicated that over expression of Prox1 increased CHO cell proliferation in comparison to GFP-CHO and parental CHO cells, and Prox1 increased Akt phosphorylation and up-regulated PI3 Kinase expression. An Akt specific inhibitor-AKTi-X (5 μM) and a PI3 K inhibitor-LY294002 (5 μM) were able to reverse AKT phosphorylation and PI3 K expression induced by Prox1, respectively. Furthermore, AKTi-X but LY-294002 decreased Prox1-CHO cell proliferations at 48 and 72 h. Our results suggest that over expression of Prox1 facilitates CHO cell proliferation via activation of the Akt signaling pathway. This finding provides new insights into the mechanism of Prox1 mediated tumor growth and metastasis where Prox1 is rich.
Multifractality can be a universal signature of phase transitions
Zhi Chen,Xiao Xu
Physics , 2013,
Abstract: Macroscopic systems often display phase transitions where certain physical quantities are singular or self-similar at different (spatial) scales. Such properties of systems are currently characterized by some order parameters and a few critical exponents. Nevertheless, recent studies show that the multifractality, where a large number of exponents are needed to quantify systems, appears in many complex systems displaying self-similarity. Here we propose a general approach and show that the appearance of the multifractality of an order parameter related quantity is the signature of a physical system transiting from one phase to another. The distribution of this quantity obtained within suitable (time) scales satisfies a $q$-Gaussian distribution plus a possible Cauchy distributed background. At the critical point the $q$-Gaussian shifts between Gaussian type with narrow tails and L$\acute{\text{e}}$vy type with fat tails. Our results suggest that the Tsallis $q$-statistics, besides the conventional Boltzmann-Gibbs statistics, may play an important role during phase transitions.
An NP-hardness Result on the Monoid Frobenius Problem
Zhi Xu,J. Shallit
Computer Science , 2008,
Abstract: The following problem is NP-hard: given a regular expression $E$, decide if $E^*$ is not co-finite.
Study on Characteristics of the Wheelchair-User Combination  [PDF]
Zerui Xiang, Jinyi Zhi, Shiyu Dong, Bochu Xu
Journal of Biosciences and Medicines (JBM) , 2016, DOI: 10.4236/jbm.2016.46002
To summarize the characteristics of wheelchair-user combination, this paper studied wheelchairs, wheelchair users, nursing staffs and interaction relationship between them. Firstly, the findings of some research on wheelchairs and wheelchair users were investigated, and the studies in four aspects of wheelchairs and their accessories, wheelchair users, wheelchairs and wheelchair users (man-machine system), and skills training for the performance of wheelchair were reviewed. Then “wheelchair-user combination” was put forward based on the relationship between wheelchairs and wheelchair users in real life, and the “wheelchair-user combination” was divided into “WUs-Ws system” and “WUs-Ws-NSs system” according to whether the nursing staffs were needed. Finally, this paper analytically studied the characteristics of wheelchair users, characteristics in use of wheelchair and characteristics of nursing staffs, as well as put forward the characteristics of the wheelchair-user combination.
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