Chetaev型约束的相对运动动力学系统Nielsen方程的Noether对称性与Noether守恒量

研究Chetaev型约束的相对运动动力学系统Nielsen方程的Noether对称性与Noether守恒量. 对Chetaev型约束的相对运动力学系统Nielsen方程的运动微分方程、Noether对称性定义和判据进行具 体的研究, 得到了Noether对称性直接导致的Noether守恒量的表达式. 最后举例说明结果的应用.     

弱非线性耦合二维各向异性谐振子的一阶近似Lie对称性与近似守恒量

用近似Lie对称性理论研究弱非线性耦合二维各向异性 谐振子的一阶近似Lie对称性与近似守恒量, 并以频率比为2:1的弱非线性耦合二维各向异性谐振子为例, 得到其6个一阶近似Lie对称性和一阶近似守恒量, 其中1个一阶近似守恒量实为系统的精确守恒量, 4个一阶近似守恒量为平凡的一阶近似守恒量, 只有1 个一阶近似守恒量为稳定的一阶近似守恒量.     

完整系统Appell方程Mei对称性的一种新的守恒量

研究完整系统Appell方程Mei对称性的一种新的守恒量.在群的无限小变换下,由完整系统Appell方程Mei对称性的定义和判据,得到用Appell函数表示的完整系统Appell方程Mei对称性的一种新的结构方程和新的守恒量.最后,举例说明结果的应用.     

基于数量折扣合同和缺货损失的EOQ模型的改进

经济订购批量模型假定需求率、单位持有成本、订货成本为常数下得到总成本最低的订购批量,这些参数常数化的假设在现实中通常难以满足.假定需求和订货费为不确定的、库存成本包括年固定成本(与订货量无关)和年可变成本(与订货量有关),用三角模糊数表示年需求和订货费,通过引入数量折扣合同来量化单位产品进价,分别在不允许缺货和考虑缺货损失两种情况下得到最佳订货量.最后的算例表明了模型的合理性.     

Method comparison on confidence interval construction for the slope in a linear measurement model with heteroscedastic errors

In analytical chemistry, the evaluation on performance accuracy of an analytical method is an important issue. When an adjusted or new method (test method) is developed, the linear measurement error model is commonly used to compare it with another reference method. For this routine practice, the measurements on the reference method can be placed on the x‐axis, whereas those of the test method on the y‐axis, then the slope of this linear relationship indicates the agreement between them and also the performance of the test method. Under the assumption that both variables are subject to heteroscedastic measurement errors, a novel approach based on the concepts of a generalized pivotal quantity (GPQ) is proposed to construct confidence intervals for the slope. Its performance is compared with two maximum likelihood estimation (MLE)‐based approaches through simulation studies. It is shown that the proposed GPQ‐based approach is capable of maintaining the empirical coverage probabilities close to the nominal level and yielding reasonable expected lengths. The GPQ‐based approach can be recommended in practical use because of its easy implementation and better performance than the MLE‐based approaches in most simulation scenarios. Two real datasets are given to illustrate the approaches. Copyright © 2011 John Wiley & Sons, Ltd.     

Unified Symmetry of Nonholonomic System of Non-Chetaev's Type in Event Space

The unified symmetry of a nonholonomic system of non-Chetaev's type in event space under infinitesimal transformations of group is studied.Firstly,the differential equations of motion of the system are given.Secondly,the definition and the criterion of the unified symmetry for the system are obtained.Thirdly,a new conserved quantity,besides the Noether conserved quantity and the Hojman conserved quantity,is deduced from the unified symmetry of a nonholonomic system of non-Chetaev's type.Finally,an example is given to illustrate the application of the result.     

Form Invariance and Conserved Quantity for Non-holonomic Systems with Variable Mass and Unilateral Constraints

The paper studies the form invariance and a type of non-Noether conserved quantity called Mei conserved quantity for non-holonomic systems with variable mass and unilateral constraints.Acoording to the invariance of the form of differential equations of motion under infinitesimal transformations,this paper gives the definition and criterion of the form invariance for non-holonomic systems with variable mass and unilateral constraints.The condition under which a form invariance can lead to Mei conservation quantity and the form of the conservation quantity are deduced.An example is given to illustrate the application of the results.     

生产井井间距离对增强型地热系统影响分析

为揭示生产井井间距离对增强型地热系统(EGS)的影响，以中国青海共和盆地增强型地热系统为研究对象，采用数值模拟方法，建立了考虑生产井井间距离不同的三维热-固-流耦合热采模型。分析得到生产井井间距离为600 m, 700 m, 800 m, 900 m, 1000 m对EGS温度场、产出流体温度、储层寿命、总产热量、最大主应力以及最大主应变影响规律。研究结果表明，随着热开采进行，储层裂隙周围岩体温度下降，产出温度随开采年限增加而降低；从产出温度、储层寿命和总产热量三方面考虑，最优生产井井间距离为800 m;生产井井间距离对第一主应力及第一主应变影响显著，应结合实际情况选择最优生产井井间距离。