一类具有非线性发生率的SIS传染病模型的定性分析

应用微分方程定性理论,研究了一类具有非线性发生率的SIS传染病模型.给出了该系统极限环的存在性、唯一性以及无病平衡点和地方病平衡点的全局渐近稳定性的充分条件.

Abstract：

An epidemiological model with nonlinear incidence is studied. By using the qualitative theory of ordinary differential equations, sufficient conditions are obtained for the existence and uniqueness of the limit cycles and the global asymptotic stability of the disease-free equilibrium and the endemic equilibrium to the system.     

Einstein-Aether引力理论中的后后牛顿光子方程

采用后牛顿近似方法讨论了Einstein-aether引力理论中光子的后后牛顿轨道方程.导出了光子方程中的后后牛顿修正项,当后牛顿参数c14=0和度规张量gij中的各项异性部分被忽略时,这套方程回到先前文献中出现的后后牛顿光线方程.比较本理论结论和当今空间引力实验中的实验结论,Einstein-aethr理论的后后牛顿近似可以得到验证.

Abstract：

The post-post-Newtonian equations of the photon in the Einstein-aether theory are discussed using the post-Newtonian approximation method. The partial differential equations of the post-post-Newtonian amendatory term of photon are deduced. When the post-Newtonian parameter c14 is equal to 0 and the anisotropic part of gij is neglected, the equations will be reduced to the post-post-Newtonian equations in previous literature. Compared with the experimental results obtained in the high precision spatial gravitational tests, the theoretical result in this paper verifies the post-post-Newtonian approximation of Einstein-aether theory.     

具有两种免疫来源的乙肝病毒模型的全局动力学

研究了免疫反应具有两种来源的乙肝病毒模型.通过对相应特征方程的分析,讨论了感染平衡态和未感染平衡态的局部稳定性,证明了基本再生数>1时疾病的持续性.通过几何方法的应用,得到了感染平衡点全局稳定性的充分条件.

Abstract：

In this paper,an HBV model with activated immune response of two sources is studied.By analyzing the corresponding characteristic equations,the local stability of an infected steady state and an uninfected steady state is discussed.It is proved that if the basic reproductive number is more than one,the disease is persistent.By applying a geometric method,sufficient conditions are obtained for the global stability of the endemic equilibrium.     

利用周期边界函数对弦振动方程混沌化

给出了用周期边界函数对一阶线性双曲方程混沌化的结果,利用迭代函数混沌特性的结论对该结果进行了严格的证明,并进一步对满足简单条件的初始函数做了数值模拟,模拟结果与理论结论相吻合.

Abstract：

The problem of chaotifying the hyperbolic systems of linear partial differential equations with periodic boundary functions is proposed in this paper.It is verified by the chaotic properties of iterative functions.Numerical simulation results well fit the theoretical analysis.     

Studies on Resource Management of Sanjiang Plain Groundwater with the Analytical Finite Method Based on Square Grid

This article established groundwater flows differential equation mathematical model of Sanjiang Plain on the hydrology theory foundation, and used the analysis finite element method to liner change the differential equation into the large-scale system of linear equations. It took linear equations as a part of constraint conditions of the optimized model, carried on the groundwater flow status equation and the optimized model the coupling, and carries on the solution with the Lingo software. The results indicated that this local shallow layer groundwater resources were rich and have the big development potential. But recent years water resources disposition was unreasonable and ground water mining quantity was oversized, these caused the region water flux to assume the drop tendency.     

一类中立型微分方程周期解的存在性与唯一性

利用Krasnoselskii不动点理论,结合分析的方法,对一类中立型微分方程存在周期解进行定性与定量研究,获得了这类微分方程周期解存在性与唯一性的充分条件.

Abstract：

Using the analytical method and utilizing Krasnoselskii's fixed point theory, this paper qualitatively and quantitatively study the existence of the periodic solutions for a class of neutral differential equation, and obtains some sufficient conditions of existence and uniqueness of periodic solutions for this class equations.     

Thin-layer Drying Characteristics and Modeling of Two Varieties Green Malt

Malting process includes steeping, germination and kilning of cereal grains in controlled conditions. The Kilning process is the most expensive stage of malting industry. In the present study, drying behavior of green malt of two different barley varieties （Sahra and Dasht） were evaluated at air temperatures ranging from 40 to 85 ℃, at constant air velocity of 6 m/s. The main objective of this research was to select the best drying equations, in order to use them for the calculation of drying time and energy consumption. For that the experimental data was fitted to five thin layer drying equations （Lewis, Henderson and Pabis, Page, Modified page and Two-term）. The coefficients of the equations were compared by three statistical parameters as residual sum of squares, standard error of estimate and mean relative deviation. The effect of temperature on the coefficients of the five selected equations was evaluated by linear regression. The results show that The Page model was found to be most suitable in describing the drying characteristics of green barley malt because of that has the lowest statistical parameters. The color of green barley malt was determined after drying using a spectro-colorimeter （Hunter Lab） in terms of Hunter L, a, and b values. Color measurement indicated that the AE index increased with an increase in drying air temperature.     

一类抽象半线性泛函微分方程的小时滞鲁棒稳定性

研究Banach空间X中的抽象半线性泛函微分方程d/dtx(t) = Ax(t)+F(t, x_t(·))的小时滞鲁棒稳定性,其中无界线性算子A在X上生成一个C0-半群T(t)_t≥0, F是非线性函数.在F是全局Lipschitz连续的条件下,利用算子半群理论以及扰动方法,证明了上述方程的解的指数稳定性对小时滞是鲁棒的.

Abstract：

The robust stability of the abstract semi-linear functional differential equationd/dtx(t)= Ax(t)+F(t, x_t(·))is considered in Banach space X, where the linear operator A generates a C_0-semigroup [T(t)]_t≥0in X, and F is a nonlinear function. Under the condition that F is globally Lipschitz continuous, and the robust stability of the above equation is proved with the operator semi-group theory and perturba-tion method.     

一类五阶非线性演化方程的广义孤立波解和周期解

应用指数函数法,借助计算机代数系统获得了包括五阶KdV方程、Sawada-Kotera方程和Kaup-Kupershmit方程在内的一类五阶非线性演化方程的广义孤立波解和周期解.结果表明,指数函数法结合符号计算已成为解决数学物理中非线性演化方程的强有力工具.

Abstract：

In this paper,the exp-function method is used to obtain generalized solitary wave solutions and periodic solutions for a class of fifth-order nonlinear evolution equations,which include different forms of fifth-order KdV equations,Sawada-Kotera equations and Kaup-Kupershmit equations.The results show that the exp-function method,with the help of symbolic computation,provides a powerful mathematical tool for solving nonlinear evolution equations in mathematical physics.     

浅谈饲料中有效能的测定技术

饲料中有效能是供动物生长发育的基础.不同动物所用的有效能体系不同,目前大多数动物采用消化能、代谢能体系,但随着研究的发展与深入,发现最能反映饲料有效能的是净能体系.无论哪种体系,采用合理的测定技术准确测定饲料中的有效能值显得尤其重要,通过对饲料有效能值的准确测定可以实现动物所需能量的精确供给,减少养殖成本,使经济效益最大化.文章综述了几种有效能评价体系的测定技术.     

高校贫困生认定工作面面观

国家贫困生资助政策实施以来,对贫困生帮助很大,同时在实际运行中还存在着一些问题。本文提出贫困生认定工作仍需要进一步采取各种相关配套措施,以推动和保障贫困生资助工作更好地开展。     

《河北农业大学学报》创刊年代考

清光绪二十八年(1902)河北农业大学前身—直隶农务学堂诞生,经几易其名,于1958年更名为河北农业大学至今。清光绪三十一年(1905)直隶高等农业学堂时期创办了《北直农话报》,清光绪三十四年(1908)更名为《直隶农务官报》,中华民国七年(1918)改出《农学月刊》,中华民国十七年(1928)易名为《河大农刊》,中华民国二十三年(1934)更名为《河北通俗农刊》,中华民国二十四年(1935)易名为《河北农林学刊》,1948年更名为《河北农学院研究专刊》,1959年更名为《河北农业大学学报》至今。《河北农业大学学报》前身诸刊都与现时的《河北农业大学学报》有着一脉相承的历史渊源,各刊之间联系紧密,连续性、继承性强。因此,《河北农业大学学报》的创刊时间应追溯至1905年创办的《北直农话报》。     

生态旅游潜在客源市场特征的调查研究--以湖南永州金洞森林旅游开发为例

为探明客源市场生态旅游消费的潜在特征,采用问卷调查的形式,就长沙市居民对湖南金洞生态旅游开发的意向等问题进行抽样调查．结果显示,生态旅游符合人们“回归自然”的旅游新时尚,有着极大的开发空间,指出生态旅游的开发要注重环境保护和可持续发展．开发的产品要以休闲度假类的大众产品为主,开发生态旅游都市客源市场还要多种渠道并用,尤其是要注重媒体的宣传．     

探究板栗的科学贮藏方法

板栗属壳斗科栗属(Castanea mollisima Blume),其种子属于顽拗型种子,不耐贮藏。基于近年来板栗贮藏保鲜技术研究成果,从合理采收、贮前处理、贮藏方法等方面进行论述。     

动物疫苗接种异常反应的处理

动物疫病是畜牧业生产的大敌,要发展畜牧业生产就要防治动物疫病。但在疫苗接种时,经常出现正常反应外的其他不利于机体的反应,如废食、皮疹、休克、死亡等,正确处理或避开这些问题,对推行动物疫病的计划免疫,实施强制免疫,保护人畜安全具有十分重要的现实意义和作用。     

厚胶合板弹性模量预测模型

为了预测厚胶合板弹性模量,通过简化层合板理论,该文建立了胶合板弹性模量预测模型,并以单板条、经过涂胶热压处理的单板条和相同工艺条件下的单板层积材的弹性模量,采用4种不同铺层方式的19层桉树胶合板对模型进行了验证。结果表明:3种预测值与实测值的趋势一致,相关系数R2顺纹在0.86以上,横纹在0.88以上,但是精度不同。采用单板条弹性模量预测的胶合板弹性模量比实测值偏低;采用经过涂胶热压处理后的单板条弹性模量预测的胶合板弹性模量比实测值偏高;采用相同工艺条件下的单板层积材弹性模量预测的胶合板弹性模量与实测值偏差较小,顺纹平均误差为4.64%,横纹平均误差10.94%。因此,采用相同工艺条件下的单板层积材的弹性模量来预测胶合板的弹性模量是可行的。      

增强我国水果业出口竞争力的思考

分析了入世4年来,我国水果出口在量上实现了突破,但并没有实现质变的主要原因,指出我国水果业存在的问题。论述了引进外资对发展我国水果业的意义,并提出了具体可行的对策与建议。     

山茱萸多糖提取工艺优化及马钱苷含量测定

采用L（934）正交设计试验,对山茱萸浸提液中山茱萸多糖的酶水解法提取工艺进行了优化研究,并对浸提液的中有效成分马钱苷含量进行了HPLC法分析。结果表明,山茱萸多糖浸提的最佳工艺为：液料比1∶5,浸提时间4 h,浸提温度80℃,果胶酶添加量0.55 g/L。用HPLC法测定出的山茱萸浸提液中马钱苷平均含量为0.512 ...     

甘肃省日光温室生产发展对策的探讨

甘肃省设施农业发展历史悠久,古代创造了麦草覆盖生产韭 黄及泥碗护苗等传统设施农业技术,至今仍然受到农民欢迎,在 甘肃省中部应用面积约5万多hm2。建国后,甘肃设施农业获得 了新生,大致经历了三个阶段;第一阶段为引进应用北京改良式 温室阶段,时间在20世纪50-60年代;第二个阶段为塑料拱棚 与地膜覆盖栽培阶段,时间在20世纪70-80年代:第三阶段为