桂丰早龙眼开花习性和果实生长模型研究

【目的】探究龙眼新品系桂丰早在南宁产区的开花习性和果实生长数学模型,为制定高产优质栽培管理措施提供理论依据。【方法】通过系统研究桂丰早龙眼的开花习性、果实生长发育和主要品质指标的动态变化规律,选用4种理论生长方程对果实纵径、横径、果形指数、单果质量、果皮质量、果皮厚度、果核质量、果肉质量、可食率、可溶性固形物含量(TSS)10个指标进行拟合,以花后天数(x),各指标生长变化(y)构建非线性回归方程,以各指标增长速率(g)绘制导函数方程,确定果实生长和品质指标动态变化的最优数学模型。【结果】在南宁桂丰早的花期约为24 d,先开雄花,花后12 d雌花开放量达到最高峰,在雌花开花数量较多的花期开放的雄雌花比例为2∶1;各指标的最优拟合方程如下:果实纵径(y2)、单果质量(y4)、果肉质量(y8)、可食率(y9)和TSS(y10)为一元二次项方程(y2=-0.001 x^(2)+0.285 x+3.094、y4=-0.002 x^(2)+0.445 x-17.962、y8=-0.002 x^(2)+0.399 x-17.953、y9=-0.02 x^(2)+4.182 x-151.845和y10=-0.012 x^(2)+2.380 x-94.493);果实横径(y1)、果形指数(y3)和果皮厚度(y6)为一元三次项方程(y1=-2.405×10^(-5)x^(3)+0.003 x^(2)+0.146 x+2.067、y3=7.822×10^(-7)x^(3)-5.878×10^(-5)x^(2)-0.009 x+1.542和y6=6.551×10^(-7)x^(3)-0.019 x+1.610);果皮质量(y5)和果核质量(y7)为Logistic方程[(y5=2.75/(1+11.80 e^(-0.024)x)和y7=1.94/(1+1.70 e^(-0.031)x)];果实发育期间各指标的增长速率为:果实横径和果皮质量为逐渐递增到最高值后就逐渐递减;果形指数为逐渐递减到最低值后逐渐递增;果实纵径、单果质量、果核质量、果肉质量、可食率和TSS为逐渐递减;果皮厚度逐渐递增。相关和偏相关分析表明,除果皮厚度外,其余指标两两间大都呈显著或极显著相关。【结论】基于果实发育天数构建果实发育的曲线拟合方程和导函数能较好地反映桂丰早龙眼果实的生长发育动态,该生长模型的建立在桂丰早生产上可用于品质预测和指导制定合理的优质栽培技术措施。

锌铝合金热镀层合金层生长影响因素的研究

为了获得具有适当合金层厚度的锌铝合金镀层 ,本文采用三因子二次回归正交试验方法 ,对影响锌铝合金镀层整体耐腐蚀性能的合金层生长问题进行了研究 ,获得了合金层生长的数学模型 ,并对合金层的生成厚度与各影响因素的关系进行了探讨。分析了热浸镀锌铝合金的硅元素添加量、浸镀温度和浸镀时间对合金层生长厚度的影响。结果表明 :在实验研究范围内 ,随硅元素含量的增加 ,合金层厚度降低 ;随浸镀温度的升高 ,合金层厚度呈直线增加 ;随浸镀时间的延长 。

玛曲草原气候资源利用与牧草生产力的研究

用3阶多项式生长曲线数学模型拟合牧草产量各状况年的牧草生产力，与实际值吻合较好。模拟结果表明，最大生长率70．2kg／hm^2·小生长率1．6kg／hm^2·d；月最大产量2042．5kg／hm^2，月最小产量57．6kg／hm^2。生长季5～9月，旬t〉0qC的累积积温每增加1℃，最高状况年比最低状况年每旬增加干物重2．54kg／hm^2；旬累积降水量每增加1mm，最高状况年比最低状况年每旬增加干物重7．33kg／hm^2；旬累积日照时数每增加1h，最高状况年比最低状况年每旬增加干物重3．83kg／hm^2。考虑到倾向率变化的不同，旬累积降水量引起的产量变化是主要原因，旬累积积温次之，旬累积日照时数影响弱。高产年气候资源利用率高，低产年气候资源利用率低。

A niche model to predict Microcystis bloom decline in Chaohu Lake, China

Cyanobacterial blooms occur frequently in lakes due to eutrophication. Although a number of models have been proposed to forecast algal blooms, a good and applicable method is still lacking. This study explored a simple and effective mathematical-ecological model to evaluate the growth status and predict the population dynamics of Microcystis blooms. In this study, phytoplankton were collected and identified from 8 sampling sites in Chaohu Lake every month from July to October, 2010. The niche breadth and niche overlap of common species were calculated using standard equations, and the potential relative growth rates of Microcystis were calculated as a weighted-value of niche overlap. In July, the potential relative growth rate was 2.79 (a.u., arbitrary units) but then rapidly declined in the following months to -3.99 a.u. in September. A significant correlation (R=0.998, P<0.01) was found in the model between the net-increase in biomass of Microcystis in the field and the predicted values calculated by the niche model, we concluded that the niche model is suitable for forecasting the dynamics of Microcystis blooms. Redundancy analysis indicated that decreases in water temperature, dissolved oxygen and total dissolved phosphorus might be major factors underlying bloom decline. Based on the theory of community succession being caused by resource competition, the growth and decline of blooms can be predicted from a community structure. This may provide a basis for early warning and control of algal blooms.

Crystallization Kinetics of Batch Spontaneous Nucleation of Potassium Nitrate

The batch cooling crystallization initiated from spontaneous nucleation for aqueous solution of potassium nitrate was studied. The concentration and transmittance data were acquired on line throughout the operation.Based on solute mass transfer in both liquid and solid phases, a kinetic model was deduced by assuming that the late period of primary nucleation resembles the initial period of the secondary nucleation. Nucleation and crystal growth stages were identified. Kinetic parameters were estimated piecewise from online experimental data and compared with those in literature. The estimated kinetic parameters for stages without apparent primary nucleation agreed well with those in literature. Further, a simulated concentration curve was also drawn from the estimated kinetic parameters and it matched well with that in experiment.

A Mathematical Model of Renal Blood Distribution Coupling TGF,MR and Tubular System

Objective：To investigate the relationship between renal blood distribution and the physiological activities of the kidney. Methods：A mathematical model is developed based on response （MR） Hagan-Poiseuille law and mass transport, coupling mechanics of myogenic tubuloglomerular feedback （TGF） and the tubular system in the renal medulla. The model parameters, including the permeability coefficients, the vascular lumen radius and the solute concentration at the inlet of the tubes, are derived from the experimental results. Simulations of the blood and water flow in the loop of Henel, the collecting duct and vas rectum, are carried out by the model of the tubular system in the renal medulla, based on conservations of water and solutes for transmural transport. Then the tubular model is coupled with MR and TGF mechanics. Results：The results predict the dynamics of renal autoregulation on its blood pressure and flow, and the distributions are 88.5% in the cortex, 10.3% in the medulla, and 1.2% at papilla,respectively. The fluid flow and solute concentrations along the tubules and vasa recta are obtained. Conclusion ：The present model could assess renal functions qualitatively and quantitatively and provide a methodological approach for clinical research.

机翼表面结冰热力学模型

基于Messinger控制体的思想建立了翼型表面的冰生长热力学模型,论述了模型的求解方法;采用边界层积分法计算LHTC(Local Heat Transfer Coefficient),并嵌入了粗糙度对表面换热的影响;计算得到的LHTC与文献中的结果做了比较验证。本文编制了冰形计算程序模块,集成到自主开发的预测软件中,模拟了不同结冰气象条件下,NACA0012翼型在4°攻角时表面槽状冰、混合冰、楔形冰的形成。数值模拟的结果与文献中提供的实验结果吻合良好,表明本文所用模型及方法可行且有效.

EFFECT OF TOXIC METAL ON THE STRUCTURAL DRY WEIGHT OF A PLANT： A MODEL

A two compartment mathematical model for the individual plant growth under the stress of toxic metal is studied. In the model it is assumed that the uptake of toxic metal by the plant is through root compartment. The toxic metal present in the soil interfere with the uptake and distribution of essential nutrients in plant causing decrease in the nutri- ent uptake eventually damaging the root structure. In the model it is further assumed that the resistance to nutrient transport from root to shoot compartment increases and nutrient use efficiency decreases due to the presence of toxic metal. In order to visualize the effect of toxic metal on plant growth, we have studied two models, that is, model for plant growth with no toxic effect and model for plant growth with toxic effect. From the analysis of the models the criteria for plant growth with and without toxic effects are derived. The numerical simulation is done using Matlab to support the analytical results.

Time delays in proliferation process for solid avascular tumor under the action of external inhibitors

In this paper a delayed mathematical model for tumor growth under the action of external inhibitors is studied. The delay represents the time taken for cells to undergo mitosis. External inhibitor means that an inhibitor is either developed from the immune system of the body or administered by medical treatment to distinguish with that secreted by tumor itself. Non-negativity of solutions is studied. Local and global stabilities of the stationary solutions are proved for some parameter values. The analysis of the effect of inhibitor＇s parameters on tumor＇s growth is presented. The results show that dynamical behavior of solutions of this model is similar to that of solutions for corresponding nondelayed model for some parameter values.

Growth of gas bubbles in the biotissues with convective acceleration

This paper presents formulae and explanation about the growth of a convective gas bubble in the blood and other tissues of divers who surface too quickly, concentration distribution around the growing bubble is also presented. The formulae are valid all over the growth stages, i.e. under variable ambient pressure while the diver is ascending, and under constant ambient pressure at diving stops or at sea level. The mathematical model is solved analytically by using the method of combined variables. The growth process is affected by tissue diffusivity, concentration constant and the initial void fraction, which is the dominant parameter. Results show that, the time of the complete growth, in the convective growth model, is shorter than those earlier presented by Mohammadein and Mohamed [Concentration distribution around a growing gas bubble in tissue, Math. Biosci. 225（1） （2010） 11-17] and Srinivasan et al. [Mathematical models of diffusion- limited gas bubble dynamics in tissue, J. Appl. Physiol. 86 （1999） 732-741] for the growth of a stationary gas bubble, this explains the effect of bubble motion on consuming the oversaturated dissolved gas from the tissue into growing bubble which leads to increment in the growth rate to be more than those presented in the previous stationary models.