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Search Results: 1 - 10 of 12642 matches for " Xinlong Luo "
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A New Technique for Estimating the Lower Bound of the Trust-Region Subproblem  [PDF]
Xinlong Luo
Applied Mathematics (AM) , 2011, DOI: 10.4236/am.2011.24052
Abstract: Trust-region methods are popular for nonlinear optimization problems. How to determine the predicted reduction of the trust-region subproblem is a key issue for trust-region methods. Powell gave an estimation of the lower bound of the trust-region subproblem by considering the negative gradient direction. In this article, we give an alternate way to estimate the same lower bound of the trust-region subproblem.
Solving Large Scale Unconstrained Minimization Problems by a New ODE Numerical Integration Method  [PDF]
Tianmin Han, Xinlong Luo, Yuhuan Han
Applied Mathematics (AM) , 2011, DOI: 10.4236/am.2011.25069
Abstract: In reference [1], for large scale nonlinear equations , a new ODE solving method was given. This paper is a continuous work. Here has gradient structure i.e. , is a scalar function. The eigenvalues of the Jacobian of ; or the Hessian of , are all real number. So the new method is very suitable for this structure. For quadratic function the convergence was proved and the spectral radius of iteration matrix was given and compared with traditional method. Examples show for large scale problems (dimension ) the new method is very efficient.

Luo Xinlong,

计算数学 , 2003,
Abstract: In this paper, we provide a counter example for a successful method, i.e. IMP-BOT method 6], based on ODE for unconstrained optimization. And we obtain that methods based on BDF and the general trapezoidal metod for unconstrained optimization is bad efficient because these methods even if have A stability, not L stability.
Geometric Buildup Algorithms for Sensor Network Localization
Zhenzhen Zheng,Xinlong Luo,Zhijun Wu
Mathematical Problems in Engineering , 2012, DOI: 10.1155/2012/927031
Abstract: We present a geometric buildup algorithm for solving the sensor network localization problem with either accurate or noisy distance data. The algorithm determines the locations of the sensors, one at a time, by using the distances between the determined sensors and the undetermined ones. Each time, only a small system of distance equations needs to be solved and therefore, in an ideal case when the required distances are available for every sensor to be determined, the computation can be completed in steps if sensors are to be determined. An algorithm with two buildup phases is also implemented to handle not only noisy but also sparse distance data with for example only a few distant anchors. We show our test results and compare them with other approaches.
Risk Correlation Based on Time-Varying Copula Function and Extreme Value Theory  [PDF]
Xinlong Ji, Lu Zhou
Theoretical Economics Letters (TEL) , 2017, DOI: 10.4236/tel.2017.77151
Abstract: The dependence structure of financial assets in financial risk measurement is very important, the tail relations in particular. Authors of extant studies in this field tended to focus on the linear analysis of the financial assets, rarely considering nonlinear, asymmetric and thick-tail characteristics. Here, we apply the copulas connection function with time-varying factors to discuss the risk dependency relationship between financial assets. Moreover, we develop an SV-EVT model to fit variables’ marginal distribution combined with stochastic volatility and extreme value theory. Finally, we present an empirical comparative study of static and dynamic copula models applied to the sample comprising of the Chinese mainland A-shares and Hong Kong stock market. The results show that the CSJC copulas connection function describes the tail features of stock index better than the normal copulas connection function. Similarly, the time-varying model outperforms the static copulas model. Furthermore, we observe an asymmetry dependence change rule between Chinese mainland A-shares market and the Hong Kong stock market; the correlation of lower tail is significantly higher than that of the upper tail, and the bear market effect is remarkable. These findings indicate that time-varying Copulas-SV-EVT model can depict the correlation of financial asset tails exactly, and can thus be used to control investment risk and forecast abnormal fluctuations.
A fast and accurate initial alignment method for strapdown inertial navigation system on stationary base

Xinlong WANG,Gongxun SHEN,

控制理论与应用 , 2005,
Abstract: In this work,a fast an d accurate stationary alignment method for strapdown inertial navigation system (SINS) is proposed.It h as been demonstrated that the stationary alignment o f SINS can be improved by employing the multipositio n technique,but the alignment time of the azimuth error is relatively longer.Over here,the two-posi tion alignment principle is presented.On the basis of this SINS error model,a fast estimation algorithm of the azimuth error for the initial a lignment of SINS on stationary base is derived f ully from the horizontal velocity outputs and the output rates,and the novel azimuth error estimatio n algorithm is used for the two-position alignment. Consequently,the speed and accuracy of the SINS' s initial alignment is enhanced greatly.The computer simulation results illustrate the efficiency of this alignment method.
Numerical Investigations on Several Stabilized Finite Element Methods for the Stokes Eigenvalue Problem
Pengzhan Huang,Yinnian He,Xinlong Feng
Mathematical Problems in Engineering , 2011, DOI: 10.1155/2011/745908
Abstract: Several stabilized finite element methods for the Stokes eigenvalue problem based on the lowest equal-order finite element pair are numerically investigated. They are penalty, regular, multiscale enrichment, and local Gauss integration method. Comparisons between them are carried out, which show that the local Gauss integration method has good stability, efficiency, and accuracy properties, and it is a favorite method among these methods for the Stokes eigenvalue problem.
Multiscale analysis of heart beat interval increment series and its clinical significance
XiaoLin Huang,XinBao Ning,XinLong Wang
Chinese Science Bulletin , 2009, DOI: 10.1007/s11434-009-0596-2
Abstract: Analysis of multiscale entropy (MSE) and multiscale standard deviation (MSD) are performed for both the heart rate interval series and the interval increment series. For the interval series, it is found that, it is impractical to discriminate the diseases of atrial fibrillation (AF) and congestive heart failure (CHF) unambiguously from the healthy. A clear discrimination from the healthy, both young and old, however, can be made in the MSE analysis of the increment series where we find that both CHF and AF sufferers have significantly low MSE values in the whole range of time scales investigated, which reveals that there are common dynamic characteristics underlying these two different diseases. In addition, we propose the sample entropy (SE) corresponding to time scale factor 4 of increment series as a diagnosis index of both AF and CHF, and the reference threshold is recommended. Further indication that this index can help discriminate sensitively the mild heart failure (cardiac function classes 1 and 2) from the healthy gives a clue to early clinic diagnosis of CHF.
Complete Mitochondrial Genome of the Free-Living Earwig, Challia fletcheri (Dermaptera: Pygidicranidae) and Phylogeny of Polyneoptera
Xinlong Wan, Man Il Kim, Min Jee Kim, Iksoo Kim
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0042056
Abstract: The insect order Dermaptera, belonging to Polyneoptera, includes ~2,000 extant species, but no dermapteran mitochondrial genome has been sequenced. We sequenced the complete mitochondrial genome of the free-living earwig, Challia fletcheri, compared its genomic features to other available mitochondrial sequences from polyneopterous insects. In addition, the Dermaptera, together with the other known polyneopteran mitochondrial genome sequences (protein coding, ribosomal RNA, and transfer RNA genes), were employed to understand the phylogeny of Polyneoptera, one of the least resolved insect phylogenies, with emphasis on the placement of Dermaptera. The complete mitochondrial genome of C. fletcheri presents the following several unusual features: the longest size in insects is 20,456 bp; it harbors the largest tandem repeat units (TRU) among insects; it displays T- and G-skewness on the major strand and A- and C-skewness on the minor strand, which is a reversal of the general pattern found in most insect mitochondrial genomes, and it possesses a unique gene arrangement characterized by a series of gene translocations and/or inversions. The reversal pattern of skewness is explained in terms of inversion of replication origin. All phylogenetic analyses consistently placed Dermaptera as the sister to Plecoptera, leaving them as the most basal lineage of Polyneoptera or sister to Ephemeroptera, and placed Odonata consistently as the most basal lineage of the Pterygota.
Progress of Infrared Stealth Coating

Zhao Xinlong,Zhao Jing,

红外 , 2012,
Abstract: Infrared stealth technology is very important in military applications and the stealth coating material is a crucial part in the infrared stealth technology. Firstly, according to the Stefan-Boltzmann law and Kirchhoff law, the principle of infrared stealth is analyzed and the category of infrared stealth coating is presented. Through analysis of different influence factors of coating composition, the ideal coating structure with low infrared emissivity is derived. Then, the research progress of different infrared stealth materials is presented. Their development trend is predicted. The future research will include the fabrication of new stealth materials and the combination of various stealth technologies.
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