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Search Results: 1 - 10 of 45429 matches for " Yan Zeng "
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Experimental Study on a New Corrosion and Scale Inhibitor  [PDF]
Defang Zeng, Huan Yan
Journal of Environmental Protection (JEP) , 2013, DOI: 10.4236/jep.2013.47077
Abstract:

The mixture consisted of benzotriazole (BTA), chitosan (CTS), polyacrylic acid and zinc salt has been investigated as a corrosion and scale inhibitor of A3 carbon steel in cooling water. The scale and corrosion inhibition efficiency was evaluated by static anti-scaling teat together with rotary coupon test. Compared with the phosphorus corrosion and scale inhibitor, the corrosion inhibition rate and scale inhibition rate of it increased respectively by 2.51% and 1.16%. As the corrosion and scale inhibitor is phosphate-free, it wont cause eutrophication, considering the product performance and environmental influence, the phosphate-free corrosion and scale inhibitor is superior to the traditional one.

The Functional Consequences of Relative Substrate Specificity in Complex Biochemical Systems
Yan Zeng
Frontiers in Genetics , 2011, DOI: 10.3389/fgene.2011.00065
Abstract: A biochemical activity, that is, enzymatic reaction or molecular interaction, frequently involves a molecule, for example, an enzyme, capable of interacting with numerous substrates or partners. Specificity is a fundamental property of biochemical activities, and relative specificity refers to the situation whereby a molecule interacts with multiple substrates or partners but with different affinities. Here, a hypothesis is proposed that any molecule, such as an enzyme, would have a range of preferences or relative specificity for its many native substrates, which differentially impacts the phenotypes of these substrates and hence shapes the relevant biological processes in vivo. While the mechanisms underlying the specific recognition between enzymes and individual substrates have been studied extensively, whether any enzyme exhibits intrinsic selectivity toward its ensemble of substrates is often overlooked, and whether this selectivity has any functional consequences is much less appreciated. There are, however, several lines of evidence in the literature that are consistent with the hypothesis and reviewed here. Furthermore, this hypothesis is supported by our analyses of a number of diverse biochemical systems at a large scale. Thus, the human microRNA processing machinery possesses relative specificity toward its hundreds of substrates, which might contribute to differential microRNA biogenesis; the promoter binding affinity of the transcription factor Ndt80 might regulate Ndt80 target mRNA expression in the budding yeast; Cdk1 kinase specificity might lead to variable substrate phosphorylation in vivo; and the density of HuR deposition to its thousands of RNA targets might partly explain differential RNA expression in human cells. It is proposed, therefore, that relative specificity is a universal property of complex biochemical systems and that the hypothesis could denote a general principle in biology.
Passive Localization Using Time Difference of Arrival and Frequency Difference of ArrivalWC  [PDF]
Xiansheng Guo, Yan Zhang, Botao Zeng
Journal of Computer and Communications (JCC) , 2018, DOI: 10.4236/jcc.2018.61007
Abstract:
In order to improve the accuracy and engineering feasibility of four-Satellite localization system, the frequency difference measurement is introduced to the four-Satellite TDOA (Time Difference of Arrival) localization algorithm. The TDOA/FDOA (Frequency Difference of Arrival) localization algorithm is used to optimize the GDOP (geometric dilution of precision) of four-Satellite localization. The simulation results show that the absolute position measurement accuracy has little influence on TDOA/FDOA localization accuracy as compared with TDOA localization. Under the same conditions, TDOA/FDOA localization has better accuracy and its GDOP shows more uniform distribution in diamond configuration case. The localization accuracy of four-Satellite TDOA/FDOA is better than the localization accuracy of four-Satellite TDOA.
A Humanoid Robot Gait Planning and Its Stability Validation  [PDF]
Jian Zeng, Haibo Chen, Yan Yin, Yan Yin
Journal of Computer and Communications (JCC) , 2014, DOI: 10.4236/jcc.2014.211009
Abstract:

Gait planning based on linear inverted pendulum (LIPM) on structured road surface can be quickly generated because of the simple model and definite physical meaning. However, over-simplifi- cation of the model and discontents of zero velocity and acceleration boundary conditions when robot starts and stops walking lead to obvious difference between the model and the real robot. In this paper, parameterized gait is planned and trajectories’ smoothness of each joint angle and centroid are ensured using the 3-D LIPM theory. Static walking method is used to satisfy zero velocity and acceleration boundary conditions. Besides, a multi-link model is built to validate the stability. Simulation experiments show that: despite of some deviation from the theoretical solution, the actual zero-moment point (ZMP) is still within the support polygon, and the robot walks steadily. In consequence, the rationality and validity of model simplification of LIPM is demonstrated.

Scatter and Blurring Compensation in Inhomogeneous Media Using a Postprocessing Method
Yan Yan,Gengsheng L. Zeng
International Journal of Biomedical Imaging , 2008, DOI: 10.1155/2008/806705
Abstract: An efficient postprocessing method to compensate for the scattering and blurring effects in inhomogeneous medium in SPECT is proposed. A two-dimensional point spread function (2D-PSF) was estimated in the image domain to model the combination of these two physical effects. This 2D-PSF in the inhomogeneous medium is fitted with an asymmetric Gaussian function based on Monte Carlo simulation results. An efficient further blurring and deconvolution method was used to restore images from the spatially variant 2D-PSF kernel. The compensation is performed using a computer-simulated NCAT phantom and a flanged Jaszczak experimental phantom. The preliminary results demonstrate an improvement in image quality and quantity accuracy with increased image contrast (25% increase compared to uncompensated image) and decreased error (40% decrease compared to uncompensated image). This method also offers an alternative to compensate for scatter and blurring in a more time efficient manner compared to the popular iterative methods. The execution time for this efficient postprocessing method is only a few minutes, which is within the clinically acceptable range.
Intensity process and compensator: A new filtration expansion approach and the Jeulin--Yor theorem
Xin Guo,Yan Zeng
Mathematics , 2008, DOI: 10.1214/07-AAP447
Abstract: Let $(X_t)_{t\ge0}$ be a continuous-time, time-homogeneous strong Markov process with possible jumps and let $\tau$ be its first hitting time of a Borel subset of the state space. Suppose $X$ is sampled at random times and suppose also that $X$ has not hit the Borel set by time $t$. What is the intensity process of $\tau$ based on this information? This question from credit risk encompasses basic mathematical problems concerning the existence of an intensity process and filtration expansions, as well as some conceptual issues for credit risk. By revisiting and extending the famous Jeulin--Yor [Lecture Notes in Math. 649 (1978) 78--97] result regarding compensators under a general filtration expansion framework, a novel computation methodology for the intensity process of a stopping time is proposed. En route, an analogous characterization result for martingales of Jacod and Skorohod [Lecture Notes in Math. 1583 (1994) 21--35] under local jumping filtration is derived.
Non-recurrent parameter rays of the Mandelbrot set
Yan Gao,Jinsong Zeng
Mathematics , 2015,
Abstract: In this paper, we prove that any parameter ray at a non-recurrent angle $\theta$ lands at a non-recurrent parameter $c$ with $\theta$ a characteristic angle of $f_c$; and conversely, every non-recurrent parameter $c$ is the landing point of one or two parameter rays at non-recurrent angles, and these angles are exactly the characteristic angles of $f_c$.
Flatly Broadened and Highly Coherent Supercontinuum Generation by Induced Modulation Instability in ANDi-PCF  [PDF]
Chunfu Cheng, Yan Zeng, Yiwen Ou, Zhangyong Yang, Zehao Chen
Journal of Applied Mathematics and Physics (JAMP) , 2018, DOI: 10.4236/jamp.2018.64056
Abstract:
In this paper, a flatly broadened and highly coherent supercontinuum generation by induced modulation instability in ANDi-PCF is proposed. The numerical results show that the bandwidth of supercontinuun can be increased by increasing the modulation depth and the coherence property of supercontinuum can be improved with the optimal modulation frequency. A highly coherent supercontinuum with the 10 dB bandwidth of 1305 nm and the flatness of less than 10 dB can be obtained when seeding at the modulation depth of 0.3 and modulation frequency of 24 THz.
The Development and Application of Information Management System in Guangdong Medical Science Library
医学图书馆信息管理系统的开发与应用

Zeng Yan,
曾燕

现代图书情报技术 , 2004,
Abstract: This paper introduced the establishment and application of information managemen t system in Guangdong Medical Science Library.
A general model for estimating actual evaporation from non-saturated surfaces

QIU Xinfa,ZENG Yan,

地理学报 , 2002,
Abstract: Based on energy balance equation and mass transfer equation, a general model to estimate actual evaporation from non-saturated surfaces was derived. Making use of two concepts, "relative evaporation" and "relative drying power", a relationship was established to account for the departure from saturated conditions. Using this model, the actual evaporation (evapotranspiration) can be calculated without the need of potential evaporation estimation. Furthermore, the model requires only a few meteorological parameters that are readily and routinely obtainable at standard weather stations. Based on nearly 30 years data of 432 meteorological stations and 512 hydrological stations in China, in combined with GIS, nine typical river basins were selected. Using the data of the selected river basins, the model was tested. The results show that the actual evaporation rate can be estimated with an error of less than 10% in most areas of China, except few years in the Yellow River Basin.
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