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Search Results: 1 - 10 of 34390 matches for " LU Hengjun "
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Lu Huiming,Wang Hengjun,Xie Yongsheng,

资源科学 , 1996,
Abstract: Autumn zero tillage experiment was carried out in places where soil and water loss is serious but terracing is impossible on the vast expanse of sloping land with yellow spongy soil in eastern section of Yanshan Mountains of Luanping. Results indicated that without practicing autumn tillage, soil scoured was reduced by 79. 3% in comparison to contrast area, surface runoff reduced by 18. 8%, soil moisture increased by about 1%, and soil alkali-soluble nitrogen and quick-acting. phosphorous increased by 1. 4 ppm and 38. 9 ppm respectively, yield increased by 2% to 10% and per hectare cost reduction due to zero tillage by 150-225 yuan. It is really quite promising to popularize zero tillage in the area.

Xie Yongsheng,Wang Hengjun,Lu Huiming,

资源科学 , 1996,
Abstract: Based on on-the-spot investigations and measurement, the paper gives a systematic analysis of the distribution of soil and water loss, and the amount of soil and water loss for different types of land use in the experimental areas of Luanping. Focuses for future soil and water conservation work in eastern section of Yanshan Mountains are identified as well.
Determination of 4 phenols in water by three phase hollow fiber microextraction coupled with high performance liquid chromatography

WEI Chao,LU Hengjun,CHEN Meilan,ZHU Yan,

色谱 , 2011,
Abstract: A method was investigated for the determination of 4 phenols in water by three phase hollow fiber microextraction coupled with high performance liquid chromatography. Some factors affecting the extraction efficiency were optimized, such as the nature of organic solvent, the concentration of acceptor phase, the pH value of donor phase, extraction time, stirring rate and salt concentration. The optimized conditions were as follows: 1-octanol was used as the organic solvent, the concentration of NaOH solution as acceptor phase was 0.09 mol/L, the pH value of donor phase was 4, the extraction time was 40 min, the stirring rate was 600 r/min and the NaCl concentration was 100 g/L. Under the optimal conditions, the detection limits (S/N=3) of phenol, 4-methylphenol, 2,4-dimethylphenol and 2-naphthol were 0.4, 0.4, 1.2 and 0.4 μg/L, and the enrichment factors were 111.6, 129.5, 71.0 and 175.6, respectively. The proposed method was applied for the determination of the 4 phenols in real environmental water samples and the spiked recoveries were in the range of 85.9%~119.0% at the spiked levels of 5 and 50 μg/L. The method is simple, rapid, accurate and suitable for the determination of phenols in water samples.
Global Existence and Asymptotic Behavior of Solutions to the Generalized Damped Boussinesq Equation
Yinxia Wang,Hengjun Zhao
Advances in Mathematical Physics , 2013, DOI: 10.1155/2013/364165
Abstract: We investigate the Cauchy problem for the generalized damped Boussinesq equation. Under small condition on the initial value, we prove the global existence and optimal decay estimate of solutions for all space dimensions . Moreover, when , we show that the solution can be approximated by the linear solution as time tends to infinity. 1. Introduction We investigate the Cauchy problem of the following generalized damped Boussinesq equation: with the initial value Here is the unknown function of and , , and are constants. The nonlinear term is a given smooth function of satisfying for . It is well known that the classical Boussinesq equation was derived by Boussinesq [1] in 1872 to describe shallow water waves, where is an elevation of the free surface of fluid and the constant coefficients and depend on the depth of fluid and the characteristic speed of long waves. It is interesting to note that this equation also governs nonlinear string oscillations. Taking into account dispersion and nonlinearity, but in real processes viscosity also plays an important role. Varlamov considered the following damped Boussinesq equation (see [2–4]): where and are constants. Under small condition on the initial value, Varlamov [2] obtained a classical solution to the problem (4), (2) by means of the application of both the spectral and perturbation theories. Moreover, large time asymptotics of this solution was also discussed. For the problem (4), (2) in one, two, and three space dimensions, existence and uniqueness of local solution are proved by Varlamov [3]. The author also showed that for discontinuous initial perturbations this solution is infinitely differentiable with respect to time and space coordinates for on a bounded time interval. Existence and uniqueness of the classical solution for the problem (4), (2) in two space dimensions was proved, and the solution was constructed in the form of a series. The major term of its long-time asymptotics is calculated explicitly, and a uniform in space estimate of the residual term was given (see [4]). The main purpose of this paper is to establish the following optimal decay estimate of solutions to (1), (2) for : for and . Here is assumed to be small. Moreover, when , we show that our solution can be approximated by the solution to the linearized problem, namely, the problem (1), (2) with . More precisely, when , we show that for and , where for and for . The study of the global existence and asymptotic behavior of solutions to hyperbolic-type equations has a long history. We refer to [5, 6] for hyperbolic equations,
Logarithmically Improved Blow up Criterion for Smooths Solution to the 3D Micropolar Fluid Equations
Yin-Xia Wang,Hengjun Zhao
Journal of Applied Mathematics , 2012, DOI: 10.1155/2012/541203
Abstract: Blow-up criteria of smooth solutions for the 3D micropolar fluid equations are investigated. Logarithmically improved blow-up criteria are established in the Morrey-Campanto space.
Automatically Discovering Relaxed Lyapunov Functions for Polynomial Dynamical Systems
Jiang Liu,Naijun Zhan,Hengjun Zhao
Mathematics , 2011,
Abstract: The notion of Lyapunov function plays a key role in design and verification of dynamical systems, as well as hybrid and cyber-physical systems. In this paper, to analyze the asymptotic stability of a dynamical system, we generalize standard Lyapunov functions to relaxed Lyapunov functions (RLFs), by considering higher order Lie derivatives of certain functions along the system's vector field. Furthermore, we present a complete method to automatically discovering polynomial RLFs for polynomial dynamical systems (PDSs). Our method is complete in the sense that it is able to discover all polynomial RLFs by enumerating all polynomial templates for any PDS.
Computing Semi-algebraic Invariants for Polynomial Dynamical Systems
Jiang Liu,Naijun Zhan,Hengjun Zhao
Computer Science , 2011,
Abstract: In this paper, we consider an extended concept of invariant for polynomial dynamical system (PDS) with domain and initial condition, and establish a sound and complete criterion for checking semi-algebraic invariants (SAI) for such PDSs. The main idea is encoding relevant dynamical properties as conditions on the high order Lie derivatives of polynomials occurring in the SAI. A direct consequence of this criterion is a relatively complete method of SAI generation based on template assumption and semi-algebraic constraint solving. Relative completeness means if there is an SAI in the form of a predefined template, then our method can indeed find one using this template.
Synthesizing Switching Controllers for Hybrid Systems by Continuous Invariant Generation
Deepak Kapur,Naijun Zhan,Hengjun Zhao
Computer Science , 2013,
Abstract: We extend a template-based approach for synthesizing switching controllers for semi-algebraic hybrid systems, in which all expressions are polynomials. This is achieved by combining a QE (quantifier elimination)-based method for generating continuous invariants with a qualitative approach for predefining templates. Our synthesis method is relatively complete with regard to a given family of predefined templates. Using qualitative analysis, we discuss heuristics to reduce the numbers of parameters appearing in the templates. To avoid too much human interaction in choosing templates as well as the high computational complexity caused by QE, we further investigate applications of the SOS (sum-of-squares) relaxation approach and the template polyhedra approach in continuous invariant generation, which are both well supported by efficient numerical solvers.
Argonaute proteins: potential biomarkers for human colon cancer
Lan Li, Chaohui Yu, Hengjun Gao, Youming Li
BMC Cancer , 2010, DOI: 10.1186/1471-2407-10-38
Abstract: Antibodies against human Argonaute proteins were prepared by immunizing rabbits with synthetic peptides derived from the sequences of Argonaute members. Then we constructed a tissue microarray containing 75 specimens from colon cancer and 75 specimens from adjacent non-cancer tissue, and assayed eight different proteins (EIF2C1, EIF2C2, EIF2C3, EIF2C4, PIWIL1, PIWIL2, PIWIL3 and PIWIL4) by immunohistochemistry on consecutive formalin-fixed tissue microarray sections.The expression of EIF2C1-4 and PIWIL1-4 was significantly higher in tumorous tissue than in adjacent tissue. Notably, a significant correlation was observed between the positive expression of EIF2C2, EIF2C3, EIF2C4, PIWIL4 and the presence of distant metastasis. Logistic regression analysis revealed that an increased expression of EIF2C1 and PIWIL2 was significantly associated with occurrence of colon cancer tissue compared with non-cancer tissue.Argonaute proteins are overexpressed in colon cancer relative to adjacent non-cancer tissue. The expression of EIF2C2-4 and PIWIL4 appears increased in advanced tumors with distant metastasis, suggesting it may promote tumor invasion. Furthermore, EIF2C1 and PIWIL2 might represent novel colon cancer markers with early diagnostic significance.Colon cancer is one of the most frequent and lethal malignancies worldwide, and the 5-year survival rate is less than 50% [1,2]. Given the high level in incidence rate and mortality rate of colon cancer, it would be important to better understand the biological basis of tumor development and progression, to develop markers for assessing onset or prediction of therapy outcome, as well as to identify targets for the development of novel therapies. Colon cancer may be considered the final step of a progressive imbalance between mucosal cell proliferation and apoptosis due to the activation of oncogenes and the inactivation of tumor suppressor genes [3-5]. The evaluation of the clinical utility of each of these genes would requi
Consideration on How to Deepen Reforms and Speed up Development of Chinese University Sci-tech Journals

HUANG Ting,WANG HengJun,

中国科技期刊研究 , 2008,
Abstract: 文章从当前的新形势和新任务分析了高校科技期刊深化改革,加快发展的重要性,从高校科技期刊管理体制、办刊理念和办刊思维等方面,分析了目前我国高校科技期刊改革发展存在的问题,并提出其改革发展的意见和建议。
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