Weak Noether Symmetry and non-Noether Conserved Quantities for General Holonomic Systems

A new kind of weak Noether symmetry for a general holonomic system is defined in such a way that the methods to construct Hojman conserved quantity and new-type conserved quantity are given. It turns out that we introduce a new approach to look for the conserved laws. Two examples are presented.     

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。