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Search Results: 1 - 10 of 18824 matches for " Xiaogang Han "
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Monte Carlo Numerical Models for Nuclear Logging Applications
Fusheng Li,Xiaogang Han
Journal of Systemics, Cybernetics and Informatics , 2012,
Abstract: Nuclear logging is one of most important logging services provided by many oil service companies. The main parameters of interest are formation porosity, bulk density, and natural radiation. Other services are also provided from using complex nuclear logging tools, such as formation lithology/mineralogy, etc. Some parameters can be measured by using neutron logging tools and some can only be measured by using a gamma ray tool. To understand the response of nuclear logging tools, the neutron transport/diffusion theory and photon diffusion theory are needed. Unfortunately, for most cases there are no analytical answers if complex tool geometry is involved. For many years, Monte Carlo numerical models have been used by nuclear scientists in the well logging industry to address these challenges. The models have been widely employed in the optimization of nuclear logging tool design, and the development of interpretation methods for nuclear logs. They have also been used to predict the response of nuclear logging systems for forward simulation problems. In this case, the system parameters including geometry, materials and nuclear sources, etc., are pre-defined and the transportation and interactions of nuclear particles (such as neutrons, photons and/or electrons) in the regions of interest are simulated according to detailed nuclear physics theory and their nuclear cross-section data (probability of interacting). Then the deposited energies of particles entering the detectors are recorded and tallied and the tool responses to such a scenario are generated. A general-purpose code named Monte Carlo N– Particle (MCNP) has been the industry-standard for some time. In this paper, we briefly introduce the fundamental principles of Monte Carlo numerical modeling and review the physics of MCNP. Some of the latest developments of Monte Carlo Models are also reviewed. A variety of examples are presented to illustrate the uses of Monte Carlo numerical models for the development of major nuclear logging tools, including compensated neutron porosity, compensated density, natural gamma ray and a nuclear geo-mechanical tool.
Formation of hypereutectic silicon particles in hypoeutectic Al-Si alloys under the influence of high-intensity ultrasonic vibration
Xiaogang Jian,Qingyou Han
China Foundry , 2013,
Abstract: The modification of eutectic silicon is of general interest since fine eutectic silicon along with fine primary aluminum grains improves mechanical properties and ductilities. In this study, high intensity ultrasonic vibration was used to modify the complex microstructure of aluminum hypoeutectic alloys. The ultrasonic vibrator was placed at the bottom of a copper mold with molten aluminum. Hypoeutectic Al-Si alloy specimens with a unique in-depth profile of microstructure distribution were obtained. Polyhedral silicon particles, which should form in a hypereutectic alloy, were obtained in a hypoeutectic Al-Si alloy near the ultrasonic radiator where the silicon concentration was higher than the eutectic composition. The formation of hypereutectic silicon near the radiator surface indicates that high-intensity ultrasonic vibration can be used to influence the phase transformation process of metals and alloys. The size and morphology of both the silicon phase and the aluminum phase varies with increasing distance from the ultrasonic probe/radiator. Silicon morphology develops into three zones. Polyhedral primary silicon particles present in zone I, within 15 mm from the ultrasonic probe/radiator. Transition from hypereutectic silicon to eutectic silicon occurs in zone II about 15 to 20 祄 from the ultrasonic probe/radiator. The bulk of the ingot is in zone III and is hypoeutectic Al-Si alloy containing fine lamellar and fibrous eutectic silicon. The grain size is about 15 to 25 祄 in zone I, 25 to 35 祄 in zone II, and 25 to 55 祄 in zone III. The morphology of the primary ?Al phase is also changed from dendritic (in untreated samples) to globular. Phase evolution during the solidification process of the alloy subjected to ultrasonic vibration is described.
Effect of feeding ratios on the structure and electrochemical performance of graphite oxide/polypyrrole nanocomposites
YongQin Han,Bing Ding,XiaoGang Zhang
Chinese Science Bulletin , 2011, DOI: 10.1007/s11434-011-4646-1
Abstract: Graphite oxide (GO)/polypyrrole (PPy) nanocomposites (GPYs) were synthesized using in situ polymerization. The effect of the feeding ratios of pyrrole and GO on the structure and electrochemical performances of GPYs was investigated. The structure was characterized via Fourier-transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and X-ray diffraction. The electrochemical performance was characterized via cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. The results indicate that the more pyrrole is added to GO (with GO concentrations of 20% and 50%), the more agglomeration of both PPy and GO layers occurs. This is detrimental to the capacitance utilization of PPy. When the feeding ratio of GO:pyrrole is 80:20, PPys with nanofibrils are dispersed homogenously in/on the exfoliated layer of GO and the conductivity is enhanced. The capacitance utilization of PPy in a composite with a GO concentration of 80% (383 F/g) is higher than that of pure PPy (201 F/g), which indicates the presence of a synergistic effect between GO and PPy.
Research on the Improvement of Competitiveness of Chain Business Enterprises with the System Theory  [PDF]
Xiaogang Yang
Open Journal of Business and Management (OJBM) , 2016, DOI: 10.4236/ojbm.2016.43051
Abstract: Chain business enterprises face increasing competition. With the system theory, the competitiveness structure of chain business enterprises is analyzed, and practical methods and measures for the improvement of their competitiveness are provided.
The Advantages and Measures of Constructing Logistics Strategic Alliance for Chain Marketing Enterprises  [PDF]
Xiaogang Yang
American Journal of Industrial and Business Management (AJIBM) , 2016, DOI: 10.4236/ajibm.2016.67077
Abstract: The results indicated that the logistics strategic alliance has obvious advantages and benefits to economies of scale, and building strategic alliance of logistics is an effective way for the chain marketing enterprises to achieve economies of scale, which can enhance their core competitiveness. In this paper, the author pointed out the specific measures of the chain marketing enterprises to construct and consolidate logistics strategic alliance.
Education Marketing Research  [PDF]
Xiaogang Yang
Theoretical Economics Letters (TEL) , 2016, DOI: 10.4236/tel.2016.65111
Abstract: “Education marketing” is a new concept used in high frequency interiorly in recent years, but it has significantly different interpretations in the educational circles and business circles, extremely easy to cause the misuse and mix, which is not conducive to the development and application of this new subject of marketing. The analysis of this paper shows that: there are four essential differences in the understanding of “educational marketing” in the education and business circles and two suggestions are put forward to solve the problem.
Three Important Applications of Mathematics in Financial Mathematics  [PDF]
Xiaogang Yang
American Journal of Industrial and Business Management (AJIBM) , 2017, DOI: 10.4236/ajibm.2017.79077
Abstract: This paper analyzes the basic connotation of financial mathematics, financial mathematics through research development, control theory, differential game theory and capital asset pricing model from stochastic optimal, and discusses three important applications of mathematics in the financial field.
On the Emergence, Development and Prospect of Financial Mathematics  [PDF]
Xiaogang Yang
Modern Economy (ME) , 2017, DOI: 10.4236/me.2017.89078
Abstract: Since its emergence in 1980s, financial mathematics has developed into an interdisciplinary subject with independent theoretical system. On the one hand, financial mathematics has become the key technology that can be seen everywhere in finance. On the other hand, the development of Finance provides an important platform for the application of mathematics. The purpose of this paper is to analyze and summarize the emergence and development of financial mathematics, and to analyze the future of financial mathematics.
Optimization of filtering criterion for SEQUEST database searching to improve proteome coverage in shotgun proteomics
Xinning Jiang, Xiaogang Jiang, Guanghui Han, Mingliang Ye, Hanfa Zou
BMC Bioinformatics , 2007, DOI: 10.1186/1471-2105-8-323
Abstract: In this study, we implemented a machine learning approach known as predictive genetic algorithm (GA) for the optimization of filtering criteria to maximize the number of identified peptides at fixed false-discovery rate (FDR) for SEQUEST database searching. As the FDR was directly determined by decoy database search scheme, the GA based optimization approach did not require any pre-knowledge on the characteristics of the data set, which represented significant advantages over statistical approaches such as PeptideProphet. Compared with PeptideProphet, the GA based approach can achieve similar performance in distinguishing true from false assignment with only 1/10 of the processing time. Moreover, the GA based approach can be easily extended to process other database search results as it did not rely on any assumption on the data.Our results indicated that filtering criteria should be optimized individually for different samples. The new developed software using GA provides a convenient and fast way to create tailored optimal criteria for different proteome samples to improve proteome coverage.Because of the high sensitivity, mass spectrometry has been widely used for protein identification and characterization in proteome researches within the past decade[1,2]. Shotgun proteome approach, which is based on analysis using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS), can be applied to analyze complex protein mixtures directly even without any prior purification step. Large-scale proteome profiling using multidimensional LC-MS/MS has become increasingly applied for the analysis of many biological samples, including various mammalian tissues, cell lines, and serum/plasma [3-8]. In shotgun proteomics, complex protein mixtures are first digested by the enzyme (e.g. trypsin) to produce peptide mixtures. Then the peptide mixtures are subjected to extensive separations such as strong cation exchange chromatography (SCX) coupling with on-line or off-
Dynamics of the small-scale heterogeneity of the soil carbon and nitrogen resources associated with Caragana microphylla in Inner Mongolia degraded steppe

XIONG Xiaogang,HAN Xingguo,

生态学报 , 2006,
Abstract: 小叶锦鸡儿在内蒙古典型草原中有着广泛分布,从而对小空间尺度土壤资源异质性产生强烈影响。退化草原中小叶锦鸡儿能够通过克隆生长形成灌丛斑块,不同大小斑块对应于其发育的不同阶段。因此,通过对与不同大小灌丛斑块相关的土壤有机碳(SOC)、全氮(STN)空间分布状况的分析,能够推断内蒙古退化草原中、与小叶锦鸡儿相关的小尺度SOC与STN异质性动态。结果表明:在内蒙古退化草原中,就0-5cm,5-10cm,10-20cm 3个土壤层次,小叶锦鸡儿均导致了与灌丛斑块相关小尺度上SOC与STN分布的空间异质性,且随着灌丛斑块的发育,这种异质性均不断增强,其中土壤表层0-5cm碳氮资源异质性的增强最为强烈,表现在灌丛斑块内部相对于外部(或边缘)对SOC与STN富集程度均显著增加。这表明内蒙古退化草原中,随着灌丛斑块自身的扩展,与小叶锦鸡儿相关小尺度上土壤碳氮资源空间异质性趋于增强。
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