Optimization Model for School Transportation Based on Supply-Demand Analyses

This paper presents a new conception model of school transportation supply-demand ratio (STSDR) in order to define the number of school buses needed in a limited area and to describe the conditions of school transport system. For this purpose, a mathematical equation was elaborated to simulate the real system based on the school transport conditions and on the estimated results of STSDR from 15 zones of Cuenca city in Ecuador. The data used in our model was collected from several diverse sources (i.e. administrative data and survey data). The estimated results have shown that our equation has described efficiently the school transport system by reaching an accuracy of 96%. Therefore, our model is suitable for statistical estimation given adequate data and will be useful in school transport planning policy. Given that, it is a support model for making decisions which seek efficiency in supply and demand balance.

The superiority of multi-trait models with genotype-by-environment interactions in a limited number of environments for genomic prediction in pigs

Background: Different production systems and climates could lead to genotype-by-environment(G × E) interactions between populations, and the inclusion of G × E interactions is becoming essential in breeding decisions. The objective of this study was to investigate the performance of multi-trait models in genomic prediction in a limited number of environments with G × E interactions.Results: In total, 2,688 and 1,384 individuals with growth and reproduction phenotypes, respectively, from two Yorkshire pig populations with similar genetic backgrounds were genotyped with the PorcineSNP80 panel.Single-and multi-trait models with genomic best linear unbiased prediction(GBLUP) and BayesC π were implemented to investigate their genomic prediction abilities with 20 replicates of five-fold cross-validation.Our results regarding between-environment genetic correlations of growth and reproductive traits(ranging from 0.618 to 0.723) indicated the existence of G × E interactions between these two Yorkshire pig populations. For single-trait models, genomic prediction with GBLUP was only 1.1% more accurate on average in the combined population than in single populations, and no significant improvements were obtained by BayesC π for most traits. In addition, single-trait models with either GBLUP or BayesC π produced greater bias for the combined population than for single populations. However, multi-trait models with GBLUP and BayesC π better accommodated G × E interactions,yielding 2.2% – 3.8% and 1.0% – 2.5% higher prediction accuracies for growth and reproductive traits, respectively,compared to those for single-trait models of single populations and the combined population. The multi-trait models also yielded lower bias and larger gains in the case of a small reference population. The smaller improvement in prediction accuracy and larger bias obtained by the single-trait models in the combined population was mainly due to the low consistency of linkage disequilibrium between the two populations, which also caused the BayesC π method to always produce the largest standard error in marker effect estimation for the combined population.Conclusions: In conclusion, our findings confirmed that directly combining populations to enlarge the reference population is not efficient in improving the accuracy of genomic prediction in the presence of G × E interactions, while multi-trait models perform better in a limited number of environments with G × E interactions.

Detection of QTL(quantitative trait loci) associated with wood density by evaluating genetic structure and linkage disequilibrium of teak

To find the quantitative trait loci associated with wood density in teak(Tectona grandis L.f.), 21 co-dominant markers including 13 site specific recombinase and 8 EST-based co-dominant markers designed from lignin biosynthesis genes were applied to 174 teak plus tree clones at the National Germplasm Bank, Chandrapur,India. The germplasm bank exhibited 10.6% coefficient of variation for wood densities with 84.5 ± 31.3 genetic polymorphism(%). The highly panmictic set of genotypes(FST= 0.035 ± 0.004) harbored 96.47 ± 0.40 genetic variability(%). The average allelic frequency of the 21 codominant markers was 0.65 ± 0.11 with 12.9% pairs of loci in significant LD(p\0.05, R^2 values [ 0.1), confirming their suitability for a strong marker-trait association study. The marker CCoAMT-1 was significantly(p\0.01) associated with wood density showing stability by both GLM and MLM models and explained 4.3% of the phenotypic effect. The marker from the EST representing CCoAMT can be further developed for gene-assisted selection of elite genotypes of teak with greater wood density. Therefore, we believe that the report will help accelerate the genetic improvement and advance the breeding program of the species.

How to estimate isotope fractionations of a Rayleigh-like but diffusion-limited disequilibrium process?

The Rayleigh distillation isotope fractionation(RDIF) model is one of the most popular methods used in isotope geochemistry. Numerous isotope signals observed in geologic processes have been interpreted with this model. The RDIF model provides a simple mathematic solution for the reservoir-limited equilibrium isotope fractionation effect. Due to the reservoir effect, tremendously large isotope fractionations will always be produced if the reservoir is close to being depleted. However, in real situations, many prerequisites assumed in the RDIF model are often difficult to meet. For instance, it requires the relocated materials, which are removed step by step from one reservoir to another with different isotope compositions(i.e., with isotope fractionation), to be isotopically equilibrated with materials in the first reservoir simultaneously. This ‘‘quick equilibrium requirement’’ is indeed hard to meet if the first reservoir is sufficiently large or the removal step is fast. The whole first reservoir will often fail to re-attain equilibrium in time before the next removal starts.This problem led the RDIF model to fail to interpret isotope signals of many real situations. Here a diffusion-coupled and Rayleigh-like(i.e., reservoir-effect included) separation process is chosen to investigate this problem. We find that the final isotope fractionations are controlled by both the diffusion process and the reservoir effects via the disequilibrium separation process. Due to its complexity, we choose to use a numerical simulation method to solve this problem by developing specific computing codes for the working model.According to our simulation results, the classical RDIF model only governs isotope fractionations correctly at the final stages of separation when the reservoir scale(or thickness of the system) is reduced to the order of magnitude of the quotient of the diffusivity and the separation rate. The RDIF model fails in other situations and the isotope fractionations will be diffusion-limited when the reservoir is relatively large, or the separation rate is fast. We find that the effect of internal isotope distribution inhomogeneity caused by diffusion on the Rayleigh-like separation process is significant and cannot be ignored. This method can be applied to study numerous geologic and planetary processes involving diffusion-limited disequilibrium separation processes including partial melting,evaporation, mineral precipitation, core segregation, etc.Importantly, we find that far more information can be extracted through analyzing isotopic signals of such ‘‘disequilibrium’’processes than those of fully equilibrated ones, e.g., reservoir size and the separation rate. Such information may provide a key to correctly interpreting many isotope signals observed from geochemical and cosmochemical processes.

Transmission Based Conditional Logistic Model for Testing Main and Interaction Effects

Transmission disequilibrium test (TDT) is a popular family based genetic association method. Under multiplicative assumption, a conditional logistic regression for matched pair, affected offspring with allele transmitted from parents and pseudo-offspring (control) with allele non-transmitted from parents, was built to detect the main effects of genes and gene-covariate interactions. When there exist genotype uncertainties, expectation-maximization (EM) algorithm was adopted to estimate the coefficients. The transmission model was applied to detect the association between M235T polymorphism in AGT gene and essential hypertension (ESH). Most of parents are not available in the 126 families from HongKong Chinese population. The results showed M235T is associated with hypertension and there is interaction between M235T and the case’s sex. The allele T is higher risk for male than female.

Estimation Methodology of Short-term Natural Rubber Price Forecasting Models

This study developed a short-term econometric model of world natural rubber price Standard Malaysia Rubber Grade 20 （SMR20）. Both single and simultaneous equations were utilized using monthly data from January 1990-December 2008 as estimation period and data from January 2009-June 2009 was used as an ex-ante forecast. The data were tested for unit root and Vector Error Correction and co-integration method was used to estimate the parameters of the model. The models specifications were developed in order to discover the inter-relationships between NR production, consumption and prices of SMR20 and to determine forecast price of SMR20. Comparative analysis between the single-equation specification and simultaneous supply-demand and price equation were made in terms of their estimation accuracy based on RMSE, MAE and （U-Thile） criteria. Ex-ante forecasts was carried out for the period of January 2009-June 2009. The results revealed that the values of the RMSE, MAE and U of simultaneous supply-demand and price equations model were comparatively smaller than the values generated by the single-equation model. These statistics suggest that the simultaneous equation of supply-demand and price model is more accurate and efficient measure in terms of its statistical criteria than the single-equation model in predicting the price of SMR20 in the next 6 months.

农村劳动力转移对耕地利用可持续集约化的影响

厘清农村劳动力转移与耕地利用可持续集约化之间的关系对于促进农业可持续发展具有重要意义。该研究基于1990—2020年中国省级面板数据,采用超效率SBM模型测算耕地利用可持续集约化水平,运用面板门槛模型探讨农村劳动力转移对耕地利用可持续集约化的影响效应。结果表明:1)1990—2020年中国耕地利用可持续集约化水平总体呈先下降后上升的趋势,区域间差异显著;2)农村劳动力转移对耕地利用可持续集约化存在非线性影响,当农村劳动力转移水平小于0.351时,农村劳动力转移不利于耕地利用可持续集约化的增长;超过这一门槛后,农村劳动力转移对耕地利用可持续集约化产生显著的增长效应;3)农村劳动力转移对耕地利用可持续集约化的影响存在非均衡效应,即农村劳动力转移对农业发达地区与平原地区的促进作用显著,但对农业欠发达地区与山地地区的促进作用尚不显著。基于此,应合理引导农村冗余劳动力非农转移,以推动耕地利用可持续集约化转型;同时,应注意耕地利用可持续集约化提升的自然环境禀赋与农业经济发展水平制约,因地制宜的探索适宜地区条件的耕地利用可持续集约化发展路径。

基于决策树的血液透析患者透析失衡综合征风险预测模型的构建

目的 应用卡方自动交互检测(CHAID)决策树算法构建血液透析患者透析失衡综合征的风险预测模型。方法 选取200例血液透析患者作为研究对象,将血液透析后发生透析失衡综合征的患者纳入发生组,未发生透析失衡综合征的患者纳入未发生组。收集并分析患者的临床资料,采用单因素和多因素Logistic回归分析法筛选血液透析患者发生透析失衡综合征的独立影响因素,基于独立影响因素和决策树模型构建血液透析患者发生透析失衡综合征的风险预测模型。结果 200例血液透析患者中,发生透析失衡综合征者40例,未发生透析失衡综合征者160例。多因素Logistic回归分析结果显示,年龄、尿素氮是血液透析患者发生透析失衡综合征的独立危险因素(OR>1,P<0.05),白蛋白是血液透析患者发生透析失衡综合征的独立保护因素(OR<1,P<0.05)。决策树模型显示,位于第1层的年龄是透析失衡综合征最重要的影响因素(样本分为3个亚群,年龄>56.5岁患者透析失衡综合征发生率为95.0%,远高于年龄≤56.5岁患者的发生率),位于第2层的白蛋白、尿素氮分别是年龄>55.5~56.5岁、年龄>56.5岁的影响因素。结论 分析透析失衡综合征的独立影响因素,并基于决策树构建风险预测模型,可预测血液透析患者发生透析失衡综合征的概率。

乳酸菌和双歧杆菌制剂对小鼠肠道菌群失调模型的调节作用

利用抗生素干扰小鼠肠道原籍菌群,建立小鼠肠道菌群失衡模型;并利用乳酸菌和双歧杆菌制剂对肠道菌群失调小鼠模型进行调节治疗。观察乳酸菌和双歧杆菌对肠道菌群失调模型的调节效果。选用不同浓度的头孢曲松钠,对小鼠进行灌胃。取盲肠和结肠内容物培养主要菌群变化。模型制备成功后利用乳酸菌和双歧杆菌进行菌群的治疗性调节,口服6周后,检测被检菌群的数量。结果不同剂量头孢曲松钠灌胃的小鼠盲肠体积均有所增大,模型组的优势菌的数量显著减少。通过口服乳酸菌和双歧杆菌制剂,可以适当的恢复乳酸菌和双歧杆菌的数量。与对照组比较差异显著。说明实验成功地制备了小鼠的肠道菌群失衡模型,模拟长期应用抗生素的机能环境,通过外源性的补充乳酸菌和双歧杆菌,对保持肠道菌群的平衡具有调节和修复作用。

一类非线性非均衡蛛网模型的动态分析

描述单商品市场价格波动的蛛网模型是动态经济分析中的经典模型 .文中对传统蛛网模型加以改进 ,建立一类需求函数为非线性函数、供给函数为线性函数、价格调节的非均衡蛛网模型 对该模型进行动态分析与稳定性分析 ,从而得到两个结论 一是模型不会出现 3以上周期运动和混沌现象 。

基于“三力模型”的国家高新区非均衡异化评价研究

在国家高新区非均衡发展的背景下,以产业评价"三力模型"为依据,从自主创新力、效益贡献力、国际竞争力三个维度设定了评价指标体系,采用相对偏差模糊矩阵法构建了国家高新区非均衡异化评价模型,并对56个国家高新区进行了实证分析,结论认为:我国国家高新区已进入六层分化的非均衡异动阶段,呈现出"三力"同步非均衡异化、发达→次发达城市依托选择、沿海→内陆空间层级异化布局的表现特征,并在此基础上提出了国家高新区均衡发展建议。

基于非平衡多相模型的含铝炸药爆速研究

通过对爆轰反应区中铝粉压力、温度弛豫时间的计算,发现爆轰产物压力是平衡的,温度是不平衡的。对传统CJ模型进行了改进,考虑爆轰产物的多相性和产物温度间的非平衡性,提出了一种新的计算含铝炸药爆速的模型。采用该模型对几种含铝炸药的爆速进行了计算,并与已有的实验数据进行了对比,计算结果优于传统CJ模型,与实验的误差在2%以内。

非均衡市场环境下投资性商品价格运行系统的稳定性分析

从投资者的投资行为特征出发,构建了基于投资者心理预期的投资性商品蛛网模型,运用现代经济控制论中的状态空间理论建立状态方程,对非均衡市场环境下投资性商品的价格运行系统实现稳定的条件展开分析。结果表明,非均衡市场环境下,市场对供需失衡的敏感程度位于一定区间内时,某一特定投资性商品的价格运行过程可实现渐近稳定;区间大小取决于投资者对预期收益的敏感程度以及供应商对商品前期价格的敏感程度,敏感程度越高,投资性商品价格运行越难趋于稳定。

预测控制理论应用于非均衡经济系统的分析

讨论了一种非均衡蛛网模型,应用预测控制理论,使系统稳定运行,保证供求差平稳跟踪预先给定的目标.定义了供求变化模式,研究了该模式中参数的选择对系统动态特性和鲁棒性的影响.仿真结果表明了该算法的优异性能.

基于客货运量的新疆城市等级体系分析

应用集中系数、区域非均衡系数、改进的重力模型对客货运量分别进行评价,并通过定性的方法对结果进行修正,得出结论:(1)新疆城市客货运的集中程度差异明显;(2)新疆客货运输的节点不一致,呈现出不同的变化趋势;(3)目前新疆基本形成以乌昌地区为中心,以"奎屯-乌苏"双核城市和喀什为次中心,以石河子、博乐、库尔勒、阿克苏、阜康为区域中心,其他城市为区域次中心的城市等级体系.

中国经济结构的演化及其增长效益的测度分析

改革开放以来,中国在经济总量和人均收入持续提高的同时,经济结构也发生了巨大的变化。经济结构的变化不仅是经济发展的一部分,而且也是经济持续增长的一个重要动力和源泉。本文通过对Feder非均衡经济增长模型的拓展,建立了一个可同时测度经济结构变化的增长效益和投资数量及其效率的增长效益的非均衡计量经济模型。模型的分析表明,工业化和城市化的交互作用所导致的经济结构变动对中国近三十年来的经济增长具有巨大的推动作用,是推动中国经济持续高速增长的一个主要动力。模型的分析也表明,投资建设中的浪费和资本使用效率的低下,是目前中国经济发展过程中亟待解决的主要问题。经济发展不仅需要关注GDP的增长,更应该关注社会财富的增长和积累。

双市场非均衡模型的建模方法──中国资本市场和货币市场非均衡模型

由于市场之间存在未被满足的需求和供给的溢出影响，要求考虑多市场的非均衡模型。本文建立具有数量调节和价格调节机制的双市场非均衡模型及其极大似然参数估计方法。作为应用和对中国非均衡经济的实证分析，建立了我国资本市场和货币市场的双市场非均衡模型。

非均衡最优规划模型解的经济政策意义

本文根据非均衡理论的最优规划模型 ,探讨了在凯恩斯失业均衡和抑制性通货膨胀均衡下 ,几个主要的经济变量P、W、G、T、M、A对于家庭消费C和产出Y (或就业L)的影响。主要的结论是 :在凯恩斯失业状态下 ,刺激消费的同时 ,积累仍不可忽视 ;计划经济国家长期过分注重积累的传统经济政策思想是不合理的 ;平衡或盈余的财政政策是计划经济国家的明智之举 ;

蒸发器自然循环推动力的影响因素

动力温度δt0是影响蒸发器自然循环推动力最重要的因素,利用δt0作为推动力计算模型的主要理论基础,分析过程不平衡性对该推动力的影响,提出了采用影响系数K1、K2、K3的修正模型,又推出了采用综合影响系数K的工程计算式.结果表明,采用该方法后使试验工作量减少,且计算结果更为可靠.

570矿区的水-岩同位素相互作用

文章研究５７０矿区流纹岩和花岗斑岩的氧同位素分布规律，探讨了水－岩氧同位素相互作用的地质意义，用缓冲开放系统模式估计了水－岩相互作用的持续时间。