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Search Results: 1 - 10 of 104300 matches for " Zili Zhang "
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Multiplicativity of Perverse Filtration in Hilbert Scheme of Fibered Surfaces
Zili Zhang
Mathematics , 2015,
Abstract: Let $S\to C$ be projective surface with numerically trivial canonical bundle fibered onto a curve. We prove the multiplicativity of perverse filtration on $H^*(S^{[n]},\mathbb{Q})$ for the natural morphism $S^{[n]}\to C^{(n)}$. We also prove the multiplicativity for five families of Hitchin systems obtained in a similar way and compute the perverse numbers of the Hitchin moduli spaces. We show that the perverse numbers match the predictions of the numerical version of the de Cataldo-Hausel-Migliorini $P=W$ conjecture and of the conjecture by Hausel-Letellier-Villegas for small values of $n$.
Experimental Study on Vibration Control of Offshore Wind Turbines Using a Ball Vibration Absorber  [PDF]
Jie Li, Zili Zhang, Jianbing Chen
Energy and Power Engineering (EPE) , 2012, DOI: 10.4236/epe.2012.43021
Abstract: To minimize the excessive vibration and prolong the fatigue life of the offshore wind turbine systems, it is of value to control the vibration that is induced within the structure by implementing certain kinds of dampers. In this paper, a ball vibration absorber (BVA) is experimentally investigated through a series of shake table tests on a 1/13 scaled wind turbine model. The reductions in top displacement, top acceleration, bottom stress and platform stress of the wind turbine tower system subjected to earthquakes and equivalent wind-wave loads, respectively, with a ball absorber are examined. Cases of the tower with rotating blades are also investigated to validate the efficacy of this damper in mitigating the vibration of an operating wind turbine. The experimental results indicate that the dynamic performance of the tested wind turbine model with a ball absorber is significantly improved compared with that of the uncontrolled structure in terms of the peak response reduction.
Lift System Design of Tail-Sitter Unmanned Aerial Vehicle  [PDF]
Dizhou Zhang, Zili Chen, Junwei Lv
Intelligent Control and Automation (ICA) , 2012, DOI: 10.4236/ica.2012.34033
Abstract: The main advantage of tail-sitter unmanned aerial vehicle (UAV) are introduced. Three design solutions of rotor tail-sitter lift system of UAV have been presented and the respective control strategies and characteristics of three solutions are also analyzed in the paper, through the related experiments the design of twin-rotor lift system is verified, and its feasibility is proved. The characteristics and the applying background of the twin-rotor tail-sitter UAV are described in detail. Some useful conclusions of the lift system for tail-sitter UAV are obtained.
An Algebraic Method for the N-Queens Problem Based on Permutation Operation Group
Jun Zhang,Zili Zhang
International Journal of Computer Network and Information Security , 2011,
Abstract: to analyze N-Queens problem in permutation space, this paper defines isomorphic operations of permutation to dihedral group D4. With these operations to find elements within an orbit, two operations on orbits are also defined to generate new orbit from existing ones. Orbit signature is proposed to uniquely identify different orbits in orbit space. A search algorithm based on orbit signature is presented, and finally the effectiveness of the algorithm is illustrated by an example.
The optimal manufacturer’s reserve investment and government’s subsidy policy in emergency preparedness
Zili Zhang and Xiangyang Li
Journal of Inequalities and Applications , 2013, DOI: 10.1186/1029-242X-2013-62
Abstract: Emergency supplies are of great importance when coping with a disaster. The stockpiling and production of emergency supplies should depend on private manufacturers in some cases, and the government will offer the manufacturer a subsidy to encourage its investment on extra reserves. This study investigates the manufacturer’s optimal decision on reserve investment and the government’s optimal subsidy policy based on mathematical models. The results indicate that to gain maximum benefit, the manufacturer should allocate its funds on both physical material reserve and production capacity reserve according to the government’s subsidy policy, while the government should take note of the relation between subsidy policy and subsidy period to ensure the manufacturer’s provision level of emergency supplies.
Self-Tuning Optimal Predictors for Singular Discrete Stochastic Linear Systems

Zhang Huanshui,Deng Zili,

自动化学报 , 1996,
Abstract: Using the modern time series analysis method, this paper deals with the optimal and adaptive state stimation for the singular discrete stochastic linear systems. The optimal predictor is presented by converting the state estimation into the output prediction and noise estimation, and the asymptotic stability for the initial values of the optimal predictor is proved. The self-tuning predictor is also presented as the convariance matrixes are unknown in this paper. A simulation example shows its usefulness.
Self-Tuning Deconvolution Filter for Nonstationary Arma Signals

Deng Zili,Zhang Huanshui,

自动化学报 , 1994,
Abstract: Using the modern time series analysis,this paper presents a new self-tuning recursive deconvolution filter for unknown nonstationary ARMA input signal observed through a known linear system.It can be expressed by an ARMA innovation filter,and can be used to handle the nonminimum phase and unstable observation Systems.A Simulation example shows its effectiveness.
Prediction Algorithm for State Prediction Model
Zili Zhang,Hongwei Song,Yan Li,Hao Yang
Journal of Computers , 2012, DOI: 10.4304/jcp.7.2.507-513
Abstract: Dynamic Bayesian network is the extension of Bayesian network in solving time series problems .It can be well dealt with the time-varying multivariable problem. A state model is given based on Dynamic Bayesian network. The model can more accurately describe the relationship between the system state and the influencing factors. Single-step and multi-step prediction algorithms are given to predict the system state. The multi-step state prediction algorithm is achieved by extending time-slice. In this paper, the width of the reasoning is used to simplify the amount of data in the reasoning process.
Investigation of prior image constrained compressed sensing-basedspectral X-ray CT image reconstruction
Zhou Zhengdong, Yu Zili, Zhang Wenwen, Guan Shaolin
- , 2016, DOI: 10.3969/j.issn.1003-7985.2016.04.005
Abstract: To improve spectral X-ray CT reconstructed image quality, the energy-weighted reconstructed image xWbins and the separable paraboloidal surrogates(SPS)algorithm are proposed for the prior image constrained compressed sensing(PICCS)-based spectral X-ray CT image reconstruction. The PICCS-based image reconstruction takes advantage of the compressed sensing theory, a prior image and an optimization algorithm to improve the image quality of CT reconstructions. To evaluate the performance of the proposed method, three optimization algorithms and three prior images are employed and compared in terms of reconstruction accuracy and noise characteristics of the reconstructed images in each energy bin. The experimental simulation results show that the image xWbins is the best as the prior image in general with respect to the three optimization algorithms; and the SPS algorithm offers the best performance for the simulated phantom with respect to the three prior images. Compared with filtered back-projection(FBP), the PICCS via the SPS algorithm and xWbins as the prior image can offer the noise reduction in the reconstructed images up to 80.46%, 82.51%, 88.08% in each energy bin, respectively. Meanwhile, the root-mean-squared error in each energy bin is decreased by 15.02%, 18.15%, 34.11% and the correlation coefficient is increased by 9.98%, 11.38%, 15.94%, respectively.
On the mixed fractional Brownian motion
Mounir Zili
International Journal of Stochastic Analysis , 2006, DOI: 10.1155/jamsa/2006/32435
Abstract: The mixed fractional Brownian motion is used in mathematical finance, in the modelling of some arbitrage-free and complete markets. In this paper, we present some stochastic properties and characteristics of this process, and we study the α-differentiability of its sample paths.
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