检索结果-南通市图书馆

Parameter estimation of the WMTD model

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics(A Journal of Chinese Universities) 2009年第4期24卷 379-388页

作者： luo ji QIU Hong-bing School of Mathematics and Statistics Zhejiang University of Finance and Economics Hangzhou 310018 China School of Finance and Statistics East China Normal University Shanghai 200241 China Department of Applied Mathematics Guangdong University of Technology Guangzhou 510006 China

The MTD （mixture transition distribution） model based on Weibull distribution （WMTD model） is proposed in this paper, which is aimed at its parameter estimation. An EM algorithm for estimation is given and shown to work well by some simulations. And bootstrap method is used to obtain confidence regions for the parameters. Finally, the results of a real example--predicting stock prices--show that the WMTD model proposed is able to capture the features of the data from thick-tailed distribution better than GMTD （mixture transition distribution） model.

关键词： Markov chain EM algorithm Weibull distribution bootstrap confidence region

The enigmatic ERH protein:its role in cell cycle,RNA splicing and cancer

在线全文

学校读者我要写书评

暂无评论

Protein & Cell 2013年第11期4卷 807-812页

作者： Meng-Tzu Weng ji luo Medical Oncology Branch Center for Cancer ResearchNational Cancer InstituteBethesdaMD 20892USA

Enhancer of rudimentary homolog(ERH)is a small,highly conserved protein among *** its discovery nearly 20 years ago,its molecular function has remained *** has been implicated to play a role in transcriptional regulation and in cell *** recently showed that ERH binds to the Sm complex and is required for the mRNA splicing of the mitotic motor protein ***-thermore,cancer cells driven by mutations in the KRAS oncogene are particularly sensitive to RNAi-mediated suppression of ERH function,and ERH expression is inversely correlated with survival in colorectal cancer pa-tients whose tumors harbor KRAS *** recent fi ndings indicate that ERH plays an important role in cell cycle through its mRNA splicing activity and is critically required for genomic stability and cancer cell survival.

关键词： enhancer of rudimentary homolog mRNA splicing mitosis CENP-E KRAS colorectal cancer

In-situ observations of dendritic fragmentation during directional solidification of Sn-10wt.% Bi alloy

在线全文

学校读者我要写书评

暂无评论

China Foundry 2019年第4期16卷 262-266页

作者： ji-hui luo College of Materials Science and Engineering Yangtze Normal University

The stray crystals seriously affect the properties of metals which fabricated by directional solidification(DS). In order to observe the formation of the stray crystals, the growth behavior of Sn-10 wt.%Bi alloy was observed by synchrotron X-ray imaging technique using self-developed directional solidification(DS) apparatus. The experimental results show that Sn–10 wt.%Bi alloy is oriented with the form of dendrites to grow into the liquid phase during the DS process, and dendrites are arranged neatly to form columnar crystal microstructures. It is also found that parts of the dendrite arms begin to crack. These cracked dendrites drift upward to grow up in front of the solid-liquid interface and form stray crystals.

关键词： Sn-Bi alloy syn chrotr on X-ray radiography di recti onal solidification den dritic fragme ntation

Effect of Dy substitution on the microstructure and magnetic properties of nanograin Nd-Fe-B single-phase alloys

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2010年第3期17卷 335-339页

作者： Zhi-an Chen ji luo Zhi-meng Guo School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China

Nanocrystalline single-phase alloys with the nominal compositions （at%） of Nd12.3-xDyxFe79.7Zr0.8Nb0.8Cu0.4B6.0 （x=0, 0.5, 1.5, and 2.5） were prepared by melt-spinning and subsequent annealing. X-ray diffraction analysis shows that the as-spun ribbons were mainly com- posed of the amorphous phase. A slight content of Dy stabilizes the amorphous phase during annealing treatment. The grain size becomes smaller and the coercivity of the annealed ribbon is gradually improved with the increase of Dy content. Excessive Dy is harmful to the remanence. It is found that no intergramtlar phase exists between the grains by high-resolution transmission electron microscopy, and the grain boundaries are crystallographically coherent in the optimally annealed sample. The optimum magnetic properties of remanence （Jr=1.09 T）, coercivity （Hei=1048 kA/m）, and maximum magnetic energy product （（BH）m=169.5 kJ/m3） are obtained from the x=0.5 ribbon in a post heat-treated state （700℃, 10 min）.

关键词： NdFeB magnets dysprosium nanocrystalline amorphous grain size magnetic properties

Receptivity of hypersonic boundary layer due to fast-slow acoustics interaction

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2015年第6期31卷 899-909页

作者： Jun Gao ji-Sheng luo Xue-Song Wu Department of Mechanics Tianjin University Department of Mathematics Imperial College London

The objective of receptivity is to investigate the mechanisms by which external disturbances generate unsta- ble waves. In hypersonic boundary layers, a new receptivity process is revealed, which is that fast and slow acoustics through nonlinear interaction can excite the second mode near the lower-branch of the second mode. They can generate a sum-frequency disturbance though nonlinear interaction, which can excite the second mode. This receptivity process is generated by the nonlinear interaction and the nonparal- lel nature of the boundary layer. The receptivity coefficient is sensitive to the wavenumber difference between the sumfrequency disturbance and the lower-branch second mode. When the wavenumber difference is zero, the receptivity coefficient is maximum. The receptivity coefficient decreases with the increase of the wavenumber difference. It is also found that the evolution of the sum-frequency disturbance grows linearly in the beginning. It indicates that the forced term generated by the sum-frequency disturbance resonates with the second mode.

关键词： Hypersonic boundary layer · Receptivity·Nonlinear interaction · Acoustic

A Novel Closed-Form Estimator for 3D Source Localization Using Angle of Arrivals and Gain Ratio of Arrivals 36

在线全文

学校读者我要写书评

暂无评论

A Novel Closed-Form Estimator for 3D Source Localization Usi...

Rapid chemical recycling of waste polyester plastics catalyzed by recyclable catalyst

第36届中国控制会议

作者： ji-an luo Zhi Wang Key Lab for IOT and Information Fusion Technology of Zhejiang Hangzhou Dianzi University State Kev Lab of Industrial Control Technology Zhejiang University

ISBN: (纸本)9781538629185

This paper presents a new closed-form solution for 3D source localization using the hybrid measurements of angles of arrival and gain ratios of *** the small Gaussian noise condition,we linearize the hybrid measurement equations to obtain a weighted least-squares solution and then the mean-square error matrix of the proposed method is *** analysis and simulations show that the proposed estimator can achieve the Cramer-Rao bound over the small error region.

关键词： Source Localization Closed-Form Solution Hybrid Measurements Angle of Arrival Gain Ratio of Arrival

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Green Chemical Engineering 2024年第2期5卷 257-265页

作者： Yu-ji luo jia-Yin Sun Zhi Li School of Physical Science and Technology ShanghaiTech UniversityShanghai201210China

Waste plastics are serious environmental threats due to their low degradability and low recycling *** and efficient waste plastics recycling technologies are urgently demanded for a sustainable ***,we report a rapid,closed-loop,and streamlined process to convert polyesters such as poly(ethylene terephthalate)(PET)back to its purified *** trifluoromethanesulfonic acid or metal triflates as the recyclable catalyst,polyesters such as PET can be completely depolymerized by simple carboxylic acids within 1 *** coupling this acidolysis with a subsequent hydrogenolysis process,the consumed carboxylic acid was recovered and the closed-loop of PET depolymerization could be *** catalysts and depolymerization agents are fully recycled while only PET and hydrogen are consumed.

关键词： Chemical recycling Waste polyester plastics Acidolysis Recyclable catalyst

Mercury accumulation and dynamics in montane forests along an elevation gradient in Southwest China

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2022年第9期34卷 1-10页

作者： Shufang Zeng Xun Wang Wei Yuan ji luo Dingyong Wang College of Resources and Environment Southwest UniversityChongqing 400715China State Key Laboratory of Environmental Geochemistry Institute of GeochemistryChinese Academy of SciencesGuiyang 550081China Key Laboratory of Mountain Surface Processes and Ecological Regulation Institute of Mountain Hazards and EnvironmentChinese Academy of Sciences&Ministry of Water ConservancyChengdu 610041China

Understanding atmospheric mercury(Hg) accumulation in remote montane forests is critical to assess the Hg ecological risk to wildlife and human health. To quantify impacts of vegetation, climatic and topographic factors on Hg accumulation in montane forests, we assessed the Hg distribution and stoichiometric relations among Hg, carbon(C), and nitrogen(N) in four forest types along the elevation of Mt. Gongga. Our results show that Hg concentration in plant tissues follows the descending order of litter > leaf, bark > root > branch > bole wood, indicating the importance of atmospheric Hg uptake by foliage for Hg accumulation in plants. The foliar Hg/C(from 237.0 ± 171.4 to 56.8 ± 27.7 μg/kg) and Hg/N(from 7.5 ± 3.9 to 2.5 ± 1.2 mg/kg) both decrease along the elevation. These elevation gradients are caused by the heterogeneity of vegetation uptake of atmospheric Hg and the variation of atmospheric Hg ° concentrations at different altitudes. Organic soil Hg accumulation is controlled by forest types, topographic and climatic factors, with the highest concentration in the mixed forest(244.9 ± 55.7 μg/kg) and the lowest value in the alpine forest(151.9 ±44.5 μg/kg). Further analysis suggests that soil Hg is positively correlated to C( r^(2) = 0.66) and N( r^(2) = 0.57), and Hg/C and Hg/N both increase with the soil depth. These stoichiometric relations highlight the combined effects from environmental and climatic factors which mediating legacy Hg accumulation and selective Hg absorption during processes of organic soil mineralization.

关键词： Mercury deposition Montane forest Mercury accumulation Climate impact

Mode decomposition of nonlinear eigenvalue problems and application in flow stability

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2014年第6期35卷 667-674页

作者：高军罗纪生 Department of Mechanics Tianjin University

Direct numerical simulations are carried out with different disturbance forms introduced into the inlet of a flat plate boundary layer with the Mach number 4.5. According to the biorthogonal eigenfunction system of the linearized Navier-Stokes equations and the adjoint equations, the decomposition of the direct numerical simulation results into the discrete normal mode is easily realized. The decomposition coefficients can be solved by doing the inner product between the numerical results and the eigenfunctions of the adjoint equations. For the quadratic polynomial eigenvalue problem, the inner product operator is given in a simple form, and it is extended to an Nth-degree polynomial eigenvalue problem. The examples illustrate that the simplified mode decomposition is available to analyze direct numerical simulation results.

关键词： nonlinear eigenvalue problem mode decomposition spatial mode adjoint equation orthogonal relationship