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Search Results: 1 - 10 of 104290 matches for " Zhongzhen Zhang "
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An Efficient and Concise Algorithm for Convex Quadratic Programming and Its Application to Markowitz’s Portfolio Selection Model  [PDF]
Zhongzhen Zhang, Huayu Zhang
Technology and Investment (TI) , 2011, DOI: 10.4236/ti.2011.24024
Abstract: This paper presents a pivoting-based method for solving convex quadratic programming and then shows how to use it together with a parameter technique to solve mean-variance portfolio selection problems.
Performance of a Parallel Finite Difference Atmospheric General Circulation Model

Zhang Xin,Wang Bin,Ji Zhongzhen,
Zhang Xin
,Wang Bin,Ji Zhongzhen

大气科学进展 , 2001,
Abstract: A new version of the Institute of Atmospheric Physics (IAP) 9-Layer (9L) atmospheric general circulation model (AGCM) suitable for Massively Parallel Processor (MPP) has been developed. This paper presents the principles of the parallel code design and examines its performance on a variety of state-of-the-art parallel computers in China. Domain decomposition strategy is used to achieve parallelism that is implemented by Message Passing Interface (MPI). Only the one dimensional domain decomposition algorithm is shown to scale favorably as the number of processors is increased.
Parallel Computing of a Variational Data Assimilation Model for GPS/MET Observation Using the Ray-Tracing Method
Parallel Computing of a Variational Data Assimilation Model for GPS/MET Observation Using the Ray-Tracing Method

ZHANG Xin,LIU Yuewei,WANG Bin,JI Zhongzhen,
,LIU Yuewei,WANG Bin,JI Zhongzhen

大气科学进展 , 2004,
Abstract: The Spectral Statistical Interpolation (SSI) analysis system of NCEP is used to assimilate meteorological data from the Global Positioning Satellite System (GPS/MET) refraction angles with the variational technique. Verified by radiosonde, including GPS/MET observations into the analysis makes an overall improvement to the analysis variables of temperature, winds, and water vapor. However, the variational model with the ray-tracing method is quite expensive for numerical weather prediction and climate research. For example, about 4 000 GPS/MET refraction angles need to be assimilated to produce an ideal global analysis. Just one iteration of minimization will take more than 24 hours CPU time on the NCEP's Gray C90 computer. Although efforts have been taken to reduce the computational cost, it is still prohibitive for operational data assimilation. In this paper, a parallel version of the three-dimensional variational data assimilation model of GPS/MET occultation measurement suitable for massive parallel processors architectures is developed. The divide-and-conquer strategy is used to achieve parallelism and is implemented by message passing. The authors present the principles for the code's design and examine the performance on the state-of-the-art parallel computers in China. The results show that this parallel model scales favorably as the number of processors is increased. With the Memory-IO technique implemented by the author, the wall clock time per iteration used for assimilating 1420 refraction angles is reduced from 45 s to 12 s using 1420 processors. This suggests that the new parallelized code has the potential to be useful in numerical weather prediction (NWP) and climate studies.
Initialization and Simulation of a Typhoon Using 4-Dimensional Variational Data Assimilation-Research on Typhoon Herb(1996)

ZHANG Xiaoyan,WANG Bin,JI Zhongzhen,Qingnong XIAO,ZHANG Xin,
ZHANG Xiaoyan
,WANG Bin,JI Zhongzhen,Qingnong XIAO,ZHANG Xin

大气科学进展 , 2003,
Abstract: The MM5 and its four dimensional variational data assimilation (4D-Var) system are used in thispaper. Based on the National Centers for Environmental Prediction/National Center for AtmosphericResearch (NCEP/NCAR) reanalysis data, the authors generate an optimal initial condition for a typhoonby using the bogus data assimilation (BDA) scheme. BDA is able to recover many of the structuralfeatures of typhoons including a warm-core vertex, the correct center position, and the strong circulation.As a result of BDA using a bogus surface low, dramatic improvement is achieved in the 72 h predictionof typhoon Herb. Through several cases, the initialization by BDA effectively generates the harmoniousinner structure of the typhoon, but which is lacking in the original analysis field. Therefore the intensityforecast is improved greatly. Some improvements are made in the track forecast, but more work still needsto be done.
GSK-3 Activity Is Critical for the Orientation of the Cortical Microtubules and the Dorsoventral Axis Determination in Zebrafish Embryos
Ming Shao, Yushuang Lin, Zhongzhen Liu, Ying Zhang, Lifeng Wang, Changbin Liu, Hongwei Zhang
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0036655
Abstract: The formation of dorsal-ventral (D–V) axis is the earliest event that breaks the radial symmetry and determines the bilateral body plan of a vertebrate embryo, however, the maternal control of this process is not fully understood. Here, we discovered a new dorsalizing window of acute lithium treatment, which covers only less than 10 minutes after fertilization. Lithium treatment in this window was not able to reverse the ventralized phenotype in tokkeabi (tkk) mutant embryos, and its dorsalizing activity on wild-type embryos was inhibited by nocodazole co-treatment. These evidences indicate that the underlying mechanism is independent of a direct activation of Wnt/β-catenin signaling, but depends on the upstream level of the microtubule mediated dorsal determinant transport. In order to identify the target of lithium in this newly discovered sensitive window, GSK-3 inhibitor IX as well as the IMPase inhibitor L690, 330 treatments were performed. We found that only GSK-3 inhibitor IX treatment mimicked the lithium treatment in the dorsalizing activity. Further study showed that the parallel pattern of cortical microtubules in the vegetal pole region and the directed migration of the Wnt8a mRNA were randomized by either lithium or GSK-3 inhibitor IX treatment. These results thus revealed an early and critical role of GSK-3 activity that regulates the orientation of the cortical microtubules and the directed transport of the dorsal determinants in zebrafish embryos.
Characterization and determination of six flavonoids in the ethnomedicine “Dragon’s Blood” by UPLC-PAD-MS
Tao Yi, Yina Tang, Jianye Zhang, Zhongzhen Zhao, Zhijun Yang, Hubiao Chen
Chemistry Central Journal , 2012, DOI: 10.1186/1752-153x-6-116
Abstract: An ultra performance liquid chromatography (UPLC) coupled with photodiode array detection (PAD) and electrospray ionization mass spectrometry (ESI-MS) method was developed for characterization and determination of six flavonoids in DB. A comprehensive validation of the developed method was conducted, and confirmed that the method presented good sensitivity, precision and accuracy. All linear regressions were acquired with R2 > 0.99, and the limits of detection ranged from 0.06 to 0.83 ng. The relative standard deviation (RSD) values were found to be within the range 1.4–3.8% for the method repeatability test. Recovery studies for the quantified compounds were found to be within the range 94.2–102.8% with RSD less than 4.9%. DB samples collected from different geographical regions were analyzed by the present method, and the results demonstrated that the contents of the six flavonoids in DB samples varied significantly. Three major active components among the six flavonoids, namely dracorhodin, (2S)-5-methoxyflavan-7-ol and (2S)-5-methoxy-6-methylflavan-7-ol, are suggested as the index for DB quality evaluation.Overall, the present hyphenation method is highly efficient and reliable, and hence suitable for the characterization and determination of the flavonoids of DB ethnomedicine.“Dragon’s Blood” (DB), a deep red resin secreted from the fruit of the Daemonorops draco tree, has long been used as an ethnomedicine in China to invigorate blood circulation for the treatment of traumatic injuries, blood stasis and pain [1,2]. Flavonoids [3,4] and resin terpenoid acids [5,6] are the main constituents of DB. Currently, the quality evaluation for DB medicine is based on the content of only one marker compound, namely dracorhodin, which is one of the bioactive compounds identified so far in DB [1].In recent years, pharmacologic studies have demonstrated that DB medicine exerts its clinical effects by inhibiting blood platelet aggregation [2,7], and more components of DB have
Some Study on Application of OpenMP in Mesoscale Meteorological Model-MM5

Zhang Xin,Ji Zhongzhen,Wang Bin,

气候与环境研究 , 2001,
Abstract: A new parallel programming standard-OpenMP is introduced in the beginning of this ar- ticle. Its advantage and disadvantage are known through comparison with some other parallel programming standards. The application of OpenMP in MM5 of PSU / NCAR is presented in detail. The parallel performance of both OpenMP and MPI have been tested on SGI Origin 2000. The result show that OpenMP is a simple and efficient parallel programming standard and especially suitable for meteorological sciences field.
Construction and numerical tests of the multi-conservation difference scheme
Bin Wang,Zhongzhen Ji
Chinese Science Bulletin , 2003, DOI: 10.1007/BF03184218
Abstract: A difference scheme with four conservation properties for solving the spherical barotropic shallow water equations is constructed, based on a proper formulae of the equations and a skillful correction on the spatial difference parts of the semi-discrete equations with which the number of the conservation properties of these equations is increased from three to four. Numerical tests are included, and good results are achieved in this study.
Constructions and Applied Examinations of a Kind of Square-Conservative Schemes in High Precision in the Time Direction
Ji Zhongzhen,Wang Bin,
Ji Zhongzhen
,Wang Bin

大气科学进展 , 1993,
Abstract: In order to meet the needs of work in numerical weather forecast and in numerical simulations for climate change and ocean current, a kind of difference scheme in high precision in the time direction developed from the completely square-conservative difference scheme in explicit way is built by means of the Taylor expansion. A numerical test with 4-wave Rossby-Haurwitz waves on them and an application of them on the monthly mean current the of South China Sea are carried out, from which, it is found that not only do the new schemes have high harmony and approximate precision but also can the time step of the schemes be lengthened and can much computational time be saved. Therefore, they are worth generalizing and applying.
Some Splitting Methods for Equations of Geophysical Fluid Dynamics
Ji Zhongzhen,Wang Bin,
Ji Zhongzhen
,Wang Bin

大气科学进展 , 1995,
Abstract: In this paper, equations of atmospheric and oceanic dynamics are reduced to a kind of evolutionary equation in operator form, based on which a conclusion that the separability of motion stages is relative is made and an issue that the tractional splitting methods established on the physical separability of the fast stage and the slow stage neglect the interaction between the two stages to some extent is shown. Also, three splitting patterns are summed up from the splitting methods in common use so that a comparison between them is carried out. The comparison shows that only the improved splitting pattern (ISP) can be in second order and keep the interaction well. Finally, the applications of some splitting methods on numerical simulations of typhoon tracks made clear that ISP owns the best effect and can save more than 80% CPU time.
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