第二代玉米螟灾变性长期预报模型及其应用

本应用灰色系统灾变理论，对山东省荷泽地区1976～1992年第二代玉米螟虫株率构成的离散数列进行数据处理·用傲分方程进行拟合，建立丁第二代玉米螟虫株率的灰色系统GM(1，1)长期预报模型，为第二代玉米螟的研究和防浩规划提供科学的决策依据．     

用逐步二级分辨数学模型预测农业害虫种群动态

文章应用基本Ｆｉｓｈｅｒ准则下逐步二级分辨原理，对山东省临沂市１９６５～１９８６年（１９８０年除外）共２１年的第二代玉米螟虫株率的历史观测数据进行了数量分析，建立了３个逐步二级分辨数学模型。经对历史资料的回报验证，其历史符合率分别为９５．２４％、９２．３１％、１００％。将１９８７年、１９８８年观测数据作为独立样本进行试报，其预报结果与实际一致。     

玉米地膜与露地栽培主要性状的灰色关联分析

运用灰色系统理论的灰色关联分析方法,分别对西藏林芝地区玉米地膜与露地栽培主要性状与产量之间的关系进行了探讨.分析结果表明,两种种植方式都表现为果穗粒重对产量影响最大.在玉米地膜栽培条件下,果穗重、单株绿叶面积对其产量影响较大,株高、秃顶长对其产量影响较小;在玉米露天栽培条件下,百粒重、果穗重对其产量影响较大,秃顶长、单株绿叶面积对其产量影响较小.     

GM(1,1)模型在粮食产量预测中的应用

本文根据灰色系统理论，利用安徽省１９８８—１９９５年粮食产量资料，运用ＧＭ（１，１）灰色预测模型方法，对“九五”期间安徽省粮食产量进行动态预测，为实现“九五”规划中的粮食产量提供科学的理论依据．     

武安市二代棉铃虫卵发生量灰色超长期预测

本文运用灰色系统灾变预测理论，建立了武安市二代棉铃虫发生量预测模型．从而对武安市未来年份棉铃虫卵量进行预测．     

热定型织物残留收缩率的GM（1，1）模型

本文根据灰色系统理论分别建立了涤纶长丝滤布经、纬向残留收缩率随热处理温度变化的有残差识别的ＧＭ（１，１）模型，并进行了精度检验，检测精度为一级，为涤纶长丝滤布的热定型工艺提供了理论根据     

种群动力学中含有迁移的赤眼蜂－螟虫生态系统的平衡与稳定

种群动力学中含有迁移的赤眼蜂－螟虫生态系统的平衡与稳定谢胜利，刘永清（华南理工大学自动化系，广州５１０６４１）１引言与问题赤眼蜂一螟虫生态系统，是个典型的天敌与昆虫模型，赤眼蜂将其卵产于螟卵之内，以螟卵液为蜂幼虫之食饵，从而养育成子代蜂，且使已被寄生...     

对称灰色系统稳定性的一个简便判别法

本文利用矩阵谱半径小于１的一个充分条件，给出了对称灰色系统稳定性判别的一个简便方法。     

农业生产中化肥需要量的灰色预测

在分析了ＧＭ（１，１）模型局限性的基础上，推荐使用灰色Ｖｅｒｈｕｌｓｔ模型．在本文中，灰色Ｖｅｒｈｕｌｓｔ模型比ＧＭ（１，１）模型预测精度高，能广泛应用到实际问题中。     

回归分析方法在水稻螟虫发生期预报上的应用

螟虫是我国南方水稻产区的主要害虫之一,是农业生产的大敌.以江西为例,螟害严重的年份所造成的损失达二十亿斤之多.因此,做好螟虫防治工作,是贯彻农业“八字宪法”,确保水稻稳产高产的重要措施.而准确无误的预报,则是积极主动地做好防治工作的前提.螟虫为害以三化螟最甚,在江西每年出现四代.各代卵块盛孵期正是大田施药适合的时期,是防治的关键时刻.因此,我们以三化螟各代卵块盛孵初期(以下简称初盛孵)作为预报量,使用较有代表性的江西中部地区丰城县资料(见表1),通过回归分析方法,找出预报的定量表达式.     

两总体的逐步统计分辨数学模型及其应用

本文介绍了基于马氏准则下逐步统计分辨数学模型的基本原理 .对山东省胶南市 1 985～ 1 994年共 1 0年的第二代玉米螟百株累计卵量及其影响因素的历史观测数据资料进行了数量分析 ,建立了 4个逐步统计分辨数学模型 :Y1( X) =-4 2 .7655X1+0 .0 357X2 -2 .731 5X3Y2 ( X) =-2 7.74 58X1-0 .0 50 6X2 -2 .1 548X3Y3( X) =-62 .0 1 1 0 X1-0 .1 668X2 -2 .4 681 X3Y4 ( X) =-1 9.550 7X1-0 .0 94 0 X2 -1 .3831 X3运用这些模型 ,对历史资料进行回报验证 ,其历史符号率分别为 90 %、1 0 0 %、1 0 0 %、90 % .将 1 995、1 996两年观测数据作为独立样本进行试报 ,其预报结果与实际一致 .     

基于信息熵的模糊物元模型预测玉米螟种群动态

利用模糊物元模型对玉米螟的种群动进行预测,在利用信息熵理论确定预报因子的权重的基础上构造了复合模糊物元模型,并根据往年资料构造出用于预测的关联度区间,以预测关联度映射的区间进行判决,这样避免了传统分级方法造成的主观误差,同时提高了预测的精度.     

Multiway Dependence in Exponential Family Conditional Distributions

Conditionally specified statistical models are frequently constructed from one-parameter exponential family conditional distributions. One way to formulate such a model is to specify the dependence structure among random variables through the use of a Markov random field (MRF). A common assumption on the Gibbsian form of the MRF model is that dependence is expressed only through pairs of random variables, which we refer to as the “pairwise-only dependence” assumption. Based on this assumption, J. Besag (1974, J. Roy. Statist. Soc. Ser. B36, 192–225) formulated exponential family “auto-models” and showed the form that one-parameter exponential family conditional densities must take in such models. We extend these results by relaxing the pairwise-only dependence assumption, and we give a necessary form that one-parameter exponential family conditional densities must take under more general conditions of multiway dependence. Data on the spatial distribution of the European corn borer larvae are fitted using a model with Bernoulli conditional distributions and several dependence structures, including pairwise-only, three-way, and four-way dependencies.     

Investigation of factors mediating the effectiveness of authentic projects in the teaching of elementary statistics

Four instructors used authentic research projects and related curriculum materials when teaching elementary statistics in secondary and undergraduate settings. Projects were authentic in that students selected their own variables, defined their own research questions, and collected and analyzed their own data. Classes using these projects were considered treatment groups in the study. Student outcomes measured were content knowledge, perceived usefulness of statistics, and statistics self-efficacy. These outcomes were compared with those of students taught by the same instructors in prior terms without authentic projects (the control groups). Although all three outcomes increased for the treatment group in both settings, simple t-tests indicated that these gains were not statistically significant. Variables were identified as potential factors mediating the effects of treatment, and multivariate and univariate models were then used to examine treatment, setting, instructor effects, and student achievement level as variables jointly contributing to these three outcomes. Follow-up analyses suggested that some treatment effects were significant in more restricted contexts (e.g., in certain settings for certain types of students). The models also suggest multiple significant interactions among treatment, setting, individual instructor, and student achievement level, particularly on affective outcomes.     

损伤对粘弹性矩形板非线性动力特性的影响

研究了考虑损伤效应的粘弹性矩形板在横向周期载荷作用下的非线性动力学问题．基于Von Karman方程、Boltzmann叠加原理和连续损伤力学理论,建立了以中面位移表示的考虑损伤效应的粘弹性薄板的非线性动力学方程,然后,应用有限差分法和Newmark法进行求解,并与相应的文献作出了比较．具体讨论了外载荷参数和板的几何尺寸对含损伤效应的粘弹性板非线性动力响应的影响．数值结果表明,考虑损伤效应时,结构的非线性动力响应会发生显著的变化．     

用可视化方法优化微生物培养基的营养条件

应用可视化方法,对生物发酵培养基的营养条件进行优化.以培养基组成构建多维向量空间,通过降维分析法将多维空间的拓扑结构展现在二维平面上,变成可视化图像,并自动产生目标函数等值线.从中得出同时满足各项指标值的最佳操作区域,并运用逆映射公式将得出最优化区域逆推到原高维空间,进而得到最优培养基组成.以锌酵母为例,介绍可视化方法优化全过程.     

Effects of Cone Angles on Nonlinear Vibration Responses of Functionally Graded Shells北大核心CSCD

The nonlinear vibration responses of functionally graded materials (FGMs) shells with different cone angles under external loads were studied. Firstly, the Voigt model was employed to describe the physical properties along the thickness direction of FGMs conical shells. Then, the motion equations were derived based on the 1st-order shear deformation theory, the von Kármán geometric nonlinearity and Hamilton’s principle. Next, the Galerkin method was applied to discretize the motion equations and the governing equations were simplified into a 1DOF nonlinear vibration differential equation under Volmir’s assumption. Finally, the nonlinear motion equations were solved with the harmonic balance method and the Runge-Kutta method, and the amplitude frequency response characteristic curves of the FGMs conical shells were obtained. The effects of different material distribution functions and different ceramic volume fraction exponents on the amplitude frequency response curves of conical shells were discussed. The bifurcation diagrams of conical shells with different cone angles, as well as time process diagrams and phase diagrams for different excitation amplitudes, were described. The motion characteristics were characterized by Poincaré maps. The results show that, the FGMs conical shells present the nonlinear characteristics of hardening springs. The chaotic motions of the FGMs conical shells are restrained and not prone to motion instability with the increase of the cone angle. The FGMs conical shell present a process from the periodic motion to the multi-periodic motion and then to chaos with the increase of the excitation amplitude. © 2022 Editorial Office of Applied Mathematics and Mechanics. All rights reserved.     

Compressive Properties of Pultruded Composites

The compressive properties of E-glass fiber/polyester resin matrix pultruded composites were measured using a short-block compression test fixture. Twenty specimens were tested in the pultrusion (longitudinal) direction and twenty more specimens in the transverse direction. Six specimens were tested at 30, 45, and 60° orientations to the pultrusion direction. Compressive properties such as the compressive modulus, compressive strength, Poisson ratio, and compressive failure strain were measured for both 6.3 and 12.7 mm thick pultruded sheet materials. The test specimens were rectangular with a length of 44.4 mm, width of 25.4 mm, and gage length of 25.4 mm. The test fixture was initially validated by measuring the axial strain distribution across the width of the specimen; from the beginning of loading up to the final failure, the distribution of strains across the specimen width was found to be very uniform. Back-to-back strain gages were also mounted on representative specimens. The end shortening was also measured on all specimens. The compressive strength data were analyzed both for the longitudinal and transverse directions using a two-parameter Weibull, lognormal, and normal distributions. The compressive properties are presented as functions of the specimen orientation angle for both thicknesses.     

DNA序列的特征数值及相似性分析

利用2维图表示DNA序列,计算与该图对应的距离矩阵,求出距离矩阵的不变量—距离矩阵主对角线以外的次对角线之和的平均值,进而得到了DNA序列的一种特征数值,利用这种新的特征数值,对DNA序列进行相似性比较,得到了与现有的资料符合很好的结果.     

A simulation study for the distribution law of relative moments of evolution

Nine selection‐survival strategies were implemented in a genetic algorithm experiment, and differences in terms of evolution were assessed. The moments of evolution (expressed as generation numbers) were recorded in a contingency of three strategies (i.e., proportional, tournament, and deterministic) for two moments (i.e., selection for crossover and mutation and survival for replacement). The experiment was conducted for the first 20,000 generations in 46 independent runs. The relative moments of evolution (where evolution was defined as a significant increase in the determination coefficient relative to the previous generation) when any selection‐survival strategy was used fit a Log‐Pearson type III distribution. Moreover, when distributions were compared to one another, functional relationships were identified between the population parameters, revealing a degeneration of the Log‐Pearson type III distribution in a one‐parametrical distribution that can be assigned to the chosen variable—evolution strategy. The obtained theoretical population distribution allowed comparison of the selection‐survival strategies that were used. © 2012 Wiley Periodicals, Inc. Complexity, 2012.