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Search Results: 1 - 10 of 93583 matches for " Shi Tao Yu "
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Data spectroscopy: Eigenspaces of convolution operators and clustering
Tao Shi,Mikhail Belkin,Bin Yu
Statistics , 2008, DOI: 10.1214/09-AOS700
Abstract: This paper focuses on obtaining clustering information about a distribution from its i.i.d. samples. We develop theoretical results to understand and use clustering information contained in the eigenvectors of data adjacency matrices based on a radial kernel function with a sufficiently fast tail decay. In particular, we provide population analyses to gain insights into which eigenvectors should be used and when the clustering information for the distribution can be recovered from the sample. We learn that a fixed number of top eigenvectors might at the same time contain redundant clustering information and miss relevant clustering information. We use this insight to design the data spectroscopic clustering (DaSpec) algorithm that utilizes properly selected eigenvectors to determine the number of clusters automatically and to group the data accordingly. Our findings extend the intuitions underlying existing spectral techniques such as spectral clustering and Kernel Principal Components Analysis, and provide new understanding into their usability and modes of failure. Simulation studies and experiments on real-world data are conducted to show the potential of our algorithm. In particular, DaSpec is found to handle unbalanced groups and recover clusters of different shapes better than the competing methods.
Synthesis of biodiesel from Jatropha curcas L. seed oil using artificial zeolites loaded with CH3COOK as a heterogeneous catalyst  [PDF]
Wei Xue, You-Chun Zhou, Bao-An Song, Xia Shi, Jun Wang, Shi-Tao Yin, De-Yu Hu, Lin-Hong Jin, Song Yang
Natural Science (NS) , 2009, DOI: 10.4236/ns.2009.11010
Abstract: An environmentally benign process was devel-oped for the transesterification of Jatropha curcas L. seed oil with methanol using artificial zeolites loaded with potassium acetate as a heterogeneous catalyst. After calcination for 5 h at 823 K, the catalyst loaded with 47 wt.% CH3COOK exhibited the highest efficiency and best catalytic activity. The easily prepared cata-lysts were characterized by means of X-ray dif-fraction and IR spectroscopy, as well as Hammett indicator titration. The results revealed a strong dependence of catalytic activity on ba-sicity. The optimum reaction conditions for transesterification of J. curcas oil were also in-vestigated. The methyl ester content in the bio-diesel product exceeded 91% after 4h reaction at reflux temperature in the presence of 2% solid catalyst and no water washing process is needed during workup.
One-pot synthesis of spiroglycol
Jun Ming Xu, Fu Sheng Liu, Shi Tao Yu
Bulletin of the Chemical Society of Ethiopia , 2008,
Abstract: The synthesis of spiroglycol by one-pot reaction was studied using pentaerythritol, isobutyraldehyde and formaldehyde as starting materials. Under the optimum reacting conditions, the yield and purity of product were 93.6 % and 99.0 %, respectively. Compared to the synthesis methods reported in literatures, not only was the yield of product improved, but also two operating units were omitted. The product was characterized by 1H NMR and IR. KEY WORDS: One-pot synthesis, Spiroglycol, Pentaerythritol Bull. Chem. Soc. Ethiop. 2008, 22(1), 149-152.
mRNA enrichment protocols determine the quantification characteristics of external RNA spike-in controls in RNA-Seq studies
Tao Qing,Ying Yu,TingTing Du,LeMing Shi
Science China Life Sciences , 2013, DOI: 10.1007/s11427-013-4437-9
Abstract: RNA-Seq promises to be used in clinical settings as a gene-expression profiling tool; however, questions about its variability and biases remain and need to be addressed. Thus, RNA controls with known concentrations and sequence identities originally developed by the External RNA Control Consortium (ERCC) for microarray and qPCR platforms have recently been proposed for RNA-Seq platforms, but only with a limited number of samples. In this study, we report our analysis of RNA-Seq data from 92 ERCC controls spiked in a diverse collection of 447 RNA samples from eight ongoing studies involving five species (human, rat, mouse, chicken, and Schistosoma japonicum) and two mRNA enrichment protocols, i.e., poly(A) and RiboZero. The entire collection of datasets consisted of 15650143175 short sequence reads, 131603796 (i.e., 0.84%) of which were mapped to the 92 ERCC references. The overall ERCC mapping ratio of 0.84% is close to the expected value of 1.0% when assuming a 2.0% mRNA fraction in total RNA, but showed a difference of 2.8-fold across studies and 4.3-fold among samples from the same study with one tissue type. This level of fluctuation may prevent the ERCC controls from being used for cross-sample normalization in RNA-Seq. Furthermore, we observed striking biases of quantification between poly(A) and RiboZero which are transcript-specific. For example, ERCC-00116 showed a 7.3-fold under-enrichment in poly(A) compared to RiboZero. Extra care is needed in integrative analysis of multiple datasets and technical artifacts of protocol differences should not be taken as true biological findings.
One-pot synthesis of spiroglycol
Jun Ming Xu,Fu Sheng Liu,Shi Tao Yu
Bulletin of the Chemical Society of Ethiopia , 2008,
Abstract: The synthesis of spiroglycol by one-pot reaction was studied using pentaerythritol, isobutyraldehyde and formaldehyde as starting materials. Under the optimum reacting conditions, the yield and purity of product were 93.6 % and 99.0 %, respectively. Compared to the synthesis methods reported in literatures, not only was the yield of product improved, but also two operating units were omitted. The product was characterized by 1H NMR and IR.
An Agent-Based Reasoning of Impacts of Regional Climate Changes on Land Use Changes in the Three-River Headwaters Region of China
Tao Zhang,Jinyan Zhan,Juan Huang,Rui Yu,Chenchen Shi
Advances in Meteorology , 2013, DOI: 10.1155/2013/248194
Abstract: The land surface in Three-River Headwaters Region (TRHR), a typical ecological fragile zone of China, is quite sensitive to the climate changes which will destabilize certain ecosystem services valuable to the entire nation and neighboring countries. This study aimed to analyze the impacts of climate changes and agents’ adaptive behaviors on the regional land use changes with the agent based model (ABM). First, the main agents were extracted according to the production resources endowments and socioeconomic background. Then the agents’ land use behaviors were analyzed and parameterized. Thereafter, the ABM model was built to simulate the impacts of the climate changes on the regional land use changes and agents’ economic benefits. The results showed that the land use changes were mainly characterized by the increase of grassland and decrease of unused land area. Besides, the agents would get more wealth under the scenario without climate changes in the long term, even though the total income is lower than that under the scenario with climate changes. In addition, the sensitivity analysis indicated that the model is sensitive to the climatic conditions, market price of agricultural and animal husbandry products, government subsidies, and cost control. 1. Introduction Both the global and regional climate changes have greatly undermined the terrestrial landscapes, ecological processes, and ecosystem services [1–4], which have subsequently threatened not only the human societies but also the natural environment itself by the recondite feedback effects [5–8]. There have been dramatic changes in the climatic conditions of China, which will continue to last for a long time in the future. The atmospheric temperature of China has increased by 0.5–0.8°C in the 20th century, with the upper limit exceeding the global average level. Meanwhile, the precipitation has continuously decreased in northern part of China while increased greatly in the southern and southeast part of China. Additionally, the extreme climate and subsequent natural disasters have also showed a longitudinal distribution pattern. A number of researchers have reported the impacts of climate changes on various factors of the ecological and social systems [9, 10], such as terrestrial surface [10–12], the market price [13, 14], and externality of public goods and even the political negotiations among various stakeholders [15, 16]. Climate changes associated with human adaptive activities, especially the social agents’ decisions on land use, have exerted synergistic impacts on the land surface at
The Extended Bose Hubbard Model on the Two Dimensional Honeycomb Lattice
Jing Yu Gan,Yu Chuan Wen,Jinwu Ye,Tao Li,Shi-Jie Yang,Yue Yu
Physics , 2007, DOI: 10.1103/PhysRevB.75.214509
Abstract: We study the extended Bose-Hubbard model on a two-dimensional honeycomb lattice by using large scale quantum Monte Carlo simulations. We present the ground state phase diagrams for both the hard-core case and the soft-core case. For the hard-core case, the transition between $\rho=1/2$ solid and the superfluid is first order and the supersolid state is unstable towards phase separation. For the soft-core case, due to the presence of the multiple occupation, a stable particle induced supersolid (SS-p) phase emerges when $1/2<\rho<1$. The transition from the solid at $\rho=1/2$ to the SS-p is second order with the superfluid density scaling as $ \rho_{s} \sim \rho-1/2 $. The SS-p has the same diagonal order as the solid at $ \rho=1/2 $. As the chemical potential increasing further, the SS-p will turn into a solid where two bosons occupying each site of a sublattice through a first order transition. We also calculate the critical exponents of the transition between $\rho=1/2$ solid and superfluid at the Heisenberg point for the hard core case. We find the dynamical critical exponent $z=0.15$, which is smaller than results obtained on smaller lattices. This indicates that $ z $ approaches zero in the thermodynamic limit, so the transition is also first order even at the Heisenberg point.
Hai-Dong Ju,Xu-Tang Tao,Shi-Qing Xu,Wen-Tao Yu
Acta Crystallographica Section E , 2009, DOI: 10.1107/s1600536809014378
Abstract: In the title compound, C31H27N3, the cyclohexene ring has an envelope configuration. In the crystal structure, there is an 34 3 void around the inversion center, but the low electron density (0.13 e 3) in the difference Fourier map suggests no solvent molecule occupying this void. No hydrogen bonding is found in the crystal structure.
Effects of La addition on the microstructure and tensile properties of Al-Si-Cu-Mg casting alloys
Tao Lu,Ye Pan,Ji-li Wu,Shi-wen Tao,Yu Chen
- , 2015, DOI: https://doi.org/10.1007/s12613-015-1086-y
Abstract: The effects of La addition on the microstructure and tensile properties of B-refined and Sr-modified Al-11Si-1.5Cu-0.3Mg casting alloys were investigated. With a trace addition of La (0.05wt%–0.1wt%), the mutual poisoning effect between B and Sr can be neutralized by the formation of LaB6 rather than SrB6. By employing a La/B weight ratio of 2:1, uniform microstructures, which are characterized by well refined α-Al grains and adequately modified eutectic Si particles as well as the incorporation of precipitated strengthening intermetallics, are obtained and lead to appreciable tensile properties with an ultimate tensile strength of 270 MPa and elongation of 5.8%.
Bargmann Symmetry Constraint and Binary Nonlinearization of Super NLS-MKdV Hierarchy  [PDF]
Sixing Tao, Hui Shi
Journal of Modern Physics (JMP) , 2013, DOI: 10.4236/jmp.2013.45B002

An explicit Bargmann symmetry constraint is computed and its associated binary nonlinearization of Lax pairs is carried out for the super NLS-MKdV hierarchy. Under the obtained symmetry constraint, the n-th flow of the super NLS-MKdV hierarchy is decomposed into two super finite-dimensional integrable Hamiltonian systems, defined over the super-symmetry manifold R4N|2N with the corresponding dynamical variables x and tn. The integrals of motion required for Liouville integrability are explicitly given.

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