检索结果-南通市图书馆

Journal of Environmental Sciences 2006年第1期18卷 76-82页

作者： hu Chun LIN lan-yu hu Xue-xiang Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beij ing 100085 China

The morphology of supported metal nanoparticles on TiO2/silical gel （TSO） and photothermal synergism were investigated for destruction of ethylene. During photocatalytic deposition of metal nanopartilces, the effects of pH and light intensity on the morphology of coated platinum, palladium, gold on TiO2/silical gel were studied. Moreover, these catalysts were characterized by TEM, UV-Vis DRS. The pH of preparing solution have strong influence on dispersion, size and sites of Pt, Pd and Au on TSO, which were controlled by the electrostatic binding of HPtCl5^- AuCl4^- and TiOH2^＋, Pd^2＋ and TiO^- respectively. Platinum, gold and palladium nanoparticles were uniformly highly dispersed on the titanol sites not silanol of TiO2/silical gel under pH=2, pH =9.9 respectively. For the photodegradation of ethylene, they show higher photothermal efficiency than those prepared with other pH conditions under UV illumination in a non-circulating photoreactor. The optimum weight loadings of Pt, Au, and Pd were 0.25 wt%, 0.5 wt%, 1 wt%, respectively. The synergistic effect enhanced ethylene removal and CO2 production. Thcse results verify that the best photothermal synergistic effect depends on the dispersion, size of noble metal nano-particles. FTIR analyses of the used Pt-, Pd-TSO catalysts indicated that no significant by-products were accumulated on the surface of the catalysts, leading to them longer lifetime.

关键词： photodeposition TiO2/silical gel noble metal dispersion photothermal synergism

Exponential Convergence in Probability for Empirical Means of Lévy Processes

在线全文

学校读者我要写书评

暂无评论

Acta Mathematicae Applicatae Sinica 2010年第3期26卷 481-488页

作者： Shu-lan hu Nian Yao Department of Statistics Zhongnan University of Economics and Law Wuhan 430073 China Department of Mathematics and Statistics Wuhan University Wuhan 430072 China

Let （Xt）t≥0 be a Lévy process taking values in R^d with absolutely continuous marginal distributions. Given a real measurable function f on R^d in Kato＇s class, we show that the empirical mean 1/t ∫ f（Xs）ds converges to a constant z in probability with an exponential rate if and only if f has a uniform mean z. This result improves a classical result of Kahane et al. and generalizes a similar result of L. Wu from the Brownian Motion to general Lévy processes.

关键词： L6vy processes exponential convergence in probability large deviations,functions with uniform mean

Fractional Coloring Planar Graphs under Steinberg-type Conditions

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2023年第5期39卷 904-922页

作者： Xiao lan hu Jia Ao LI School of Mathematics and Statistics&hubei Key Laboratory of Mathematical Sciences Central China Normal UniversityWuhan 430079P.R.China School of Mathematical Sciences and LPMC Nankai UniversityTianjin 300071P.R.China

A Steinberg-type conjecture on circular coloring is recently proposed that for any prime p≥5,every planar graph of girth p without cycles of length from p+1 to p(p-2)is Cp-colorable(that is,it admits a homomorphism to the odd cycle Cp).The assumption of p≥5 being prime number is necessary,and this conjecture implies a special case of Jaeger’s Conjecture that every planar graph of girth 2p-2 is Cp-colorable for prime p≥*** this paper,combining our previous results,we show the fractional coloring version of this conjecture is ***,the p=5 case of our fractional coloring result shows that every planar graph of girth 5 without cycles of length from 6 to 15 admits a homomorphism to the Petersen graph.

关键词： Fractional coloring circular coloring planar graphs girth homomorphism

Promising high-thermal-conductivity substrate material for high-power electronic device:silicon nitride ceramics

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2020年第5期39卷 463-478页

作者： Feng hu Zhi-Peng Xie Jian Zhang Zun-lan hu Di An State Key Laboratory of New Ceramics and Fine Processing School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China

High-thermal-conductivity silicon nitride ceramic substrates are indispensable components for nextgeneration high-power electronic devices because of their excellent mechanical properties and high thermal conductivities, which make them suitable for applications in complex and extreme environments. Here, we present an overview of the recent developments in the preparation of high-thermal-conductivity silicon nitride ceramics. First,the factors affecting the thermal conductivity of silicon nitride ceramics are described. These include lattice oxygen and grain boundary phases, as well the oxygen content of the crystal lattice, which is the main influencing ***, the methods to prepare high-thermal-conductivity silicon nitride ceramics are presented. Recent work on the preparation of high-thermal-conductivity silicon nitride is described in detail, including the raw materials used and the forming and sintering processes. Although great progress has been made, the development of a high-quality,low-cost fabrication process remains a challenge. Nevertheless, we believe that high-thermal-conductivity silicon nitride substrates are promising for massive practical applications in the next generation of high-power electronic devices.

关键词： Silicon nitride ceramics High thermal conductivity Preparation technique

Pointwise convergence of some conjugate convolution operators with applications to wavelets

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics(A Journal of Chinese Universities) 2016年第3期31卷 320-330页

作者： hu lan SHI Xian-liang College of Mathematics and Computer Science Key Laboratory of High Performance Computing and Stochastic Information Processing (HPCSIP) (Ministry of Education of China) Hunan Normal University

In this paper, we discuss the pointwise convergence of conjugate convolution op- erators with some applications to wavelets. Some criteria of convergence at （C, 1） continuous points, Lebesgue points and almost every... 详细信息

关键词： Hilbert transform pointwise convergence wavelet

Determination of jumps for functions based on Malvar-Coifman-Meyer conjugate wavelets

在线全文

学校读者我要写书评

暂无评论

Science China Mathematics 2009年第3期52卷 443-456页

作者： SHI XianLiang hu lan College of Mathematics and Computer Science Hunan Normal UniversityChangsha 410081China

In this paper we discuss determination of jumps for non-periodic function based on Malvar-Cofiman-Meyer (MCM) conjugate wavelets. We prove the equality of Lukacs type. Furthermore we establish several criteria on conc... 详细信息

关键词： MCM conjugate series concentration factor jump 42A50 42A16

Exponential Convergence Rates of Markov Chains under a Weaken Minorization Condition

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2018年第12期34卷 1829-1836页

作者： Shu lan hu Xin Yu WANG School of Statistics and Mathematics Zhongnan University of Economics and Law Wuhan 430073 P. R. China School of Mathematics and Statistics Huazhong University of Science and Technology Wuhan 430074 P. R. China

In this paper, we obtain the quantitative bound of the exponential convergence rates of Markov chains under a weaken minorization condition, using the coupling method and the analytic approach. And also, we obtain the... 详细信息

关键词： Convergence rates Markov chains coupling method analytic approach

Weaknesses and improvements of a remote user authentication scheme using smart cards

在线全文

学校读者我要写书评

暂无评论

The Journal of China Universities of Posts and Telecommunications 2007年第3期14卷 91-94页

作者： hu lan-lan NIU Xin-xin YANG Yi-xian Information Security Center State Key Laboratory of Networking andSwitching Technology Beijing University of Posts and TelecommunicationsBeijing 100876 China

In 2005, Liu et al. proposed an improvement to Chien et al.＇s remote user authentication scheme, using smart cards, to prevent parallel session attack. This article, however, will demonstrate that Liu et al.＇s scheme is vulnerable to masquerading server attack and has the system＇s secret key forward secrecy problem. Therefore, an improved scheme with better security strength, by using counters instead of timestamps, is proposed. The proposed scheme does not only achieve their scheme＇s advantages, but also enhances its security by withstanding the weaknesses just mentioned.

关键词： authentication security smart cards

Feature Extraction and Dimensionality Reduction of Arc Sound under Typical Penetration Status in Metal Inert Gas Welding

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2012年第2期25卷 293-298页

作者： LIU Lijun lan hu ZHENG Hongyan JIAN Xiaoxia Ningbo Institute of Technology Zhejiang UniversityNingbo 315100China School of Material Science ＆ Engineering Harbin University of Science and TechnologyHarbin 150080China Rongcheng College Harbin University of Science and TechnologyRongcheng 264300China

Arc sound is well known as the potential and available resource for monitoring and controlling of the weld penetration status,which is very important to the welding process quality control,so any attentions have been paid to the relationships between the arc sound and welding *** non-linear mapping models correlating the arc sound to welding parameters have been established with the help of neural ***,the research of utilizing arc sound to monitor and diagnose welding process is still in its infancy.A self-made real-time sensing system is applied to make a study of arc sound under typical penetration status,including partial penetration,unstable penetration,full penetration and excessive penetration,in metal inert-gas（MIG） flat tailored welding with spray *** sound is pretreated by using wavelet de-noising and short-time windowing technologies,and its characteristics,characterizing weld penetration status,of time-domain,frequency-domain,cepstrum-domain and geometric-domain are ***,high-dimensional eigenvector is constructed and feature-level parameters are successfully fused utilizing the concept of primary principal component analysis（PCA）.Ultimately,60-demensional eigenvector is replaced by the synthesis of 8-demensional vector,which achieves compression for feature space and provides technical supports for pattern classification of typical penetration status with the help of arc sound in MIG welding in the future.

关键词： metal inert gas welding penetration arc sound feature extraction dimensionality reduction

An application of Chen's theorem to convergence of Fourier multiplier transforms

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics(A Journal of Chinese Universities) 2013年第4期28卷 455-464页

作者： SHI Xian-liang CHEN Yang hu lan College of Mathematics and Computer Science Key Laboratory of High Performance Computing and Stochastic Information Processing (HPCSIP) (Ministry of Education of China) Hunan Normal University

Let V be a star shaped region. In 2006, Colzani, Meaney and Prestini proved that if function f satisfies some condition, then the multiplier transform with the characteristic function of tV as the multiplier tends to f almost everywhere, when t goes to∞. In this paper we use a Theorem established by *** to show that if we change their multiplier, then the condition on f can be weakened.

关键词： Fourier transform multiplier summability convergence almost everywhere