低渗透油田提捞采油合理提捞周期的确定

根据低渗透油田提捞采油生产特点,考虑油层存在启动压力梯度和提捞井均压裂投产的实际,分提捞井注水收效和不收效两种情况,推导出了提捞井产量计算理论公式,能够计算提捞井目前和未来的提捞产量,克服了经验公式需要试井资料且不能预测未来提捞产量的缺陷。通过大庆朝阳沟油田提捞试验区实例验证,给出的理论公式计算误差在5%以内,能够满足工程计算的需要。在此基础上,结合经济评价,给出了提捞采油合理提捞周期的确定方法,计算了不同油价下的合理提捞周期,为油田经济有效开发提供了依据。     

Late Pleistocene glaciation of the Changbai Mountains in northeastern China

The Changbai Mountains （2749 m a.s.l.） in northeastern China are one of the typical mountain regions with glaciation since late Pleistocene as evidenced by well-preserved erosive and accumulative landforms at elevations above 2000 m a.s.l, formed by glaciers around the crater lake, Tianchi Lake. Cirque glaciers developed on both the inner and outer sides of the volcanic cone. Well-preserved cirques, glacial trough valleys, glacial threholds, polished surfaces of the glacial erratics and the moraine ridges indicate that several glaciation processes took place during the last glacial period in this region. Resuits of optically stimulated luminescence （OSL） dating on the moraine sediments, and the K/Ar, thermal ionization mass spectrometry （TIMS）, electronic spinning resonance （ESR） dating on the volcanic rocks suggest two periods of glacier advances. One is named the Black Wind Mouth glacier advance taking place on the west and north slopes of the volcanic cone at an elevation of 2000-2100 m a.s.l., which is dated to about 20 ka, being the result of the Last Glacial Maximum （LGM）. The other is named the Meteorological Station glacier advance at the elevation of 2400-2600 m a.s.l., dated to 11 ka during the late glacial period, and is tentatively correlated to the Younger Dryas stage. The scope of the former glacier advance is larger than that of the latter. Regional comparisons showed that the glacial sequences in the Changbai Mountains are similar to other glaciated areas in eastern Asia during the later part of the last glacial cycle.     

摩托车发动机VVT系统参数的设计与优化

针对中小排量摩托车发动机的特点,研制了可切换双进气正时参数VVT系统.以发动机工作过程循环模拟为基础,通过嵌入VVT机构运行模式和控制策略的系统参数,分析了VVT结构参数、控制参数、以及相应运转参数对发动机性能的影响,对VVT系统高速和低速工况的进气迟闭角、气阀升程、切换转速等参数进行了优化设计.研究表明,在JH125摩托车发动机上装载所设计的可切换双进气正时参数VVT系统,可有效提高其整个转速工况范围的动力性指标.     

太阳能斯特林热机循环热损失及热效率数值分析

基于实用施密特循环理论,在考虑流动阻力损失的基础上,建立太阳能斯特林热机的循环热损失及热效率数学模型.运用碟式太阳能斯特林热机的一个实例,着重分析了太阳能斯特林热机的各种热损失及热效率.研究结果表明：在各种热损失中,导热损失和穿梭传热损失所占的幅度相对较大,其中导热损失最显著.各种热损失与太阳能斯特林发动机的多种结构参数和设计性能参数密切相关,增加加热管内壁的温度,降低转速值可提高循环热效率.当热腔的温度大于750 K时,太阳能斯特林热机的循环热效率值将在卡诺效率值的65%~80%之间浮动.     

An Algorithm to Identify Positive Cycles in GPRs

The purpose of this paper is to identify cycles,and in particular positive cycle(s),in anactivity network under generalized precedence relations(GPRs).An algorithm is provided to searchfor such cycle(s).An improved depth-first search is adopted.An efficient arc-oriented representationis used in the algorithm to save on computer storage requirement.     

克星循环的探讨

本文就克星循环现象,在全序关系下讨论,给出克星循环出现可能性概率,循环核的结构形式,以及处理克星循环的方法。     

HCCI／SI复合模式汽油机闭环控制策略的整车驾驶循环评估

HCCI燃烧应用于实际车辆,面临燃烧闭环控制、动态过程控制及HCCI／SI模式过渡控制等难点问题．本文针对这些问题展开研究,基于GT—power软件建立了四缸HCCI／SI复合模式汽油机模型及轿车动力学模型,采用Simulink软件建立了HCCI／SI复合模式汽油机分层闭环控制器．通过典型驾驶过程以及NEDC循环的仿真,对HCCI／SI发动机闭环控制器的动态控制能力和模式切换控制能力进行了研究,详细考察了HCCUSI复合模式汽油机轿车的燃油经济性的改善效果．仿真结果表明,HCCI／SI复合模式汽油机及其控制器可以实现驾驶过程中HCCI与SI模式的比较平滑的过渡,满足车辆行驶的动力需求,并显示出良好的经济性,在整个NEDC循环中比原机节油12．2％．     

n-星上自同胚的迭代根

设n是个自然数,Xn={z∈C:zn∈[0,1]}是个n-星,F是Xn上的连续自映射.若存在Xn上的连续自映射f及自然数m≥2,使得fm=F,则称f是F的一个m阶迭代根.本文得到了Xn上任一自同胚具有m阶迭代根的条件.     

一类三次Kolmogorov系统的定性分析

研究一类三次Kolmogorov系统:{=x(A0+A1x-A3x2+A2y+A4xy)=y(-1+x2-y)(*)其中:A0>0,A3>0,A1,A2,A4不定号.对A1>0,A2<0,A4<0的情形,利用环域定理、Dulac函数法和张芷芬唯一性定理等手法得到系统(*)在第一象限内极限环存在、不存在及极限环的唯一性的充分条件.