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Search Results: 1 - 10 of 79271 matches for " Zhaohua Liu "
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Modeling and Parameter Identification Involving 3-Hydroxypropionaldehyde Inhibitory Effects in Glycerol Continuous Fermentation
Zhaohua Gong,Chongyang Liu,Yongsheng Yu
Mathematical Problems in Engineering , 2012, DOI: 10.1155/2012/690587
Abstract: Mathematical modeling and parameter estimation are critical steps in the optimization of biotechnological processes. In the 1,3-propanediol (1,3-PD) production by glycerol fermentation process under anaerobic conditions, 3-hydroxypropionaldehyde (3-HPA) accumulation would arouse an irreversible cessation of the fermentation process. Considering 3-HPA inhibitions to cells growth and to activities of enzymes, we propose a novel mathematical model to describe glycerol continuous cultures. Some properties of the above model are discussed. On the basis of the concentrations of extracellular substances, a parameter identification model is established to determine the kinetic parameters in the presented system. Through the penalty function technique combined with an extension of the state space method, an improved genetic algorithm is then constructed to solve the parameter identification model. An illustrative numerical example shows the appropriateness of the proposed model and the validity of optimization algorithm. Since it is difficult to measure the concentrations of intracellular substances, a quantitative robustness analysis method is given to infer whether the model is plausible for the intracellular substances. Numerical results show that the proposed model is of good robustness.
ARR5 and ARR6 Mediate Tissue Specific Cross-talk between Auxin and Cytokinin in Arabidopsis  [PDF]
Aparna Kakani, Zhaohua Peng
American Journal of Plant Sciences (AJPS) , 2011, DOI: 10.4236/ajps.2011.24065
Abstract: Auxin and cytokinin interaction plays an essential role in a wide range of plant growth and developmental processes. The interaction consequence of the two hormones is highly tissue specific. The molecular mechanisms underlying the tissue specificity are largely unknown. Here we show that the cytokinin signaling pathway key components ARR5 and ARR6 respond to auxin with a highly tissue specific and contrasted pattern in Arabidopsis seedlings and calli in the presence of cytokinin. Our results suggest that the two highly homologous but functionally distinct genes, ARR5 and ARR6, play a critical role in mediating tissue specific interaction between auxin and cytokinin.
Optimal Control of a Fed-Batch Fermentation Involving Multiple Feeds
Chongyang Liu,Zhaohua Gong,Zhaoyi Huo,Bangyu Shen
Journal of Applied Mathematics , 2012, DOI: 10.1155/2012/245315
Abstract: A nonlinear dynamical system, in which the feed rates of glycerol and alkali are taken as the control functions, is first proposed to formulate the fed-batch culture of 1,3-propanediol (1,3-PD) production. To maximize the 1,3-PD concentration at the terminal time, a constrained optimal control model is then presented. A solution approach is developed to seek the optimal feed rates based on control vector parametrization method and improved differential evolution algorithm. The proposed methodology yielded an increase by 32.17% of 1,3-PD concentration at the terminal time.
Modeling of MEMS Gyroscope’s Non-Stationary Random Drift
Zhaohua Liu,Jiabin Chen,Yuliang Mao,Chunlei Song
Advances in Mathematical and Computational Methods , 2012, DOI: 10.5729
Abstract: The random drift is the most important factor affects MEMS Gyro’s precision and it is anon-stationary random signal. For improving precision of gyro and reducing effect of random drift,using grey GM(1,1) model to extract established tendency signal, using power spectral density(PSD) to identify and extract the hidden periodic weak signal, then using AR(3) to model gyro’srandom drift. As the example of LCG50 MEMS gyro, the simulation experimental results show thatusing this method can reduce the random drift and enhance precision of gyro.
Spatial pattern of modern sedimentation rate of Qinghai Lake and a preliminary estimate of the sediment flux
Hai Xu,XiaoYan Liu,ZhiSheng An,ZhaoHua Hou,JiBao Dong,Bin Liu
Chinese Science Bulletin , 2010, DOI: 10.1007/s11434-009-0580-x
Abstract: We investigated the spatiotemporal distribution of 137Cs radioactivity in surface sediment of Qinghai Lake, and developed the spatial pattern of sedimentation rate. The 137Cs inventory is higher near the estuary/bank area, but lower at the central lake. On the other hand, the average 137Cs activity is lower near the estuary/bank area, but higher at the central lake. The mass accumulation rate (MAR) and the fluxes and contents of the terrestrial detritus (e.g. SiO2, Fe2O3, and Ti) are higher near the estuary/bank area, but lower at the central lake. The chemical/biogenic deposits (e.g. the autogenic carbonates) take up higher fractions at the central lake. These suggest that the spatial pattern of recent sedimentation rate is dominated by the deposition of terrestrial detritus. The average MAR (0.0337g·cm 2·a 1) was estimated based on those of different cores of Qinghai Lake and was verified by a Ca mass-balance method. The fluxes of total lake sediments, terrestrial detritus, and direct atmospheric deposits were also estimated.
Spatial pattern of modern sedimentation rate of Qinghai Lake and a preliminary estimate of the sediment flux

Hai Xu,XiaoYan Liu,ZhiSheng An,ZhaoHua Hou,JiBao Dong,Bin Liu,

科学通报(英文版) , 2010,
Abstract: We investigated the spatiotemporal distribution of1 37Cs radioactivity in surface sediment of Qinghai Lake,and developed the spatial pattern of sedimentation rate.The1 37Cs inventory is higher near the estuary/bank area,but lower at the central lake.On the other hand,the average1 37Cs activity is lower near the estuary/bank area,but higher at the central lake.The mass accumulation rate(MAR) and the fluxes and contents of the terrestrial detritus(e.g.SiO2,Fe2O3,and Ti) are higher near the estuary/bank area,b...
Numerical blowup in two-dimensional Boussinesq equations
Zhaohua Yin
Physics , 2009,
Abstract: In this paper, we perform a three-stage numerical relay to investigate the finite time singularity in the two-dimensional Boussinesq approximation equations. The initial asymmetric condition is the middle-stage output of a $2048^2$ run, the highest resolution in our study is $40960^2$, and some signals of numerical blowup are observed.
A Hermite pseudospectral solver for two-dimensional incompressible flows on infinite domains
Zhaohua Yin
Physics , 2013, DOI: 10.1016/j.jcp.2013.10.039
Abstract: The Hermite pseudospectral method is applied to solve the Navier-Stokes equations on a two-dimensional infinite domain. The feature of Hermite function allows us to adopt larger time steps than other spectral methods, but also leads to some extra computation when the stream-function is calculated from the vorticity field. The scaling factor is employed to increase the resolution within the region of our main interest, and the aliasing error is fully removed by the 2/3-$rule$. Several traditional numerical experiments are performed with high accuracy, and some related future work on physical applications of this program is also discussed.
A New Approach to Abstract Machines - Introduction to the Theory of Configuration Machines
Zhaohua Luo
Mathematics , 2010,
Abstract: An abstract machine is a theoretical model designed to perform a rigorous study of computation. Such a model usually consists of configurations, instructions, programs, inputs and outputs for the machine. In this paper we formalize these notions as a very simple algebraic system, called a configuration machine. If an abstract machine is defined as a configuration machine consisting of primitive recursive functions then the functions computed by the machine are always recursive. The theory of configuration machines provides a useful tool to study universal machines.
Universal Algebra and Mathematical Logic
Zhaohua Luo
Mathematics , 2011,
Abstract: In this paper, first-order logic is interpreted in the framework of universal algebra, using the clone theory developed in three previous papers. We first define the free clone T(L, C) of terms of a first order language L over a set C of parameters in a standard way. The free right algebra F(L, C) of formulas over T(L, C) is then generated by atomic formulas. Structures for L over C are represented as perfect valuations of F(L, C), and theories of L are represented as filters of F(L). Finally Godel's completeness theorem and first incompleteness theorem are stated as expected.
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