轴向柱塞泵滑靴油膜动态仿真

对轴向柱塞泵滑靴润滑油膜的动态规律进行了数学建模,给出了缸体旋转一周,滑靴润滑油膜随缸体转角的变化.分析了滑靴润滑油膜与缸体转速及柱塞腔压力之间的变化规律.仿真结果表明:由转速所带来的动压效应对滑靴润滑油膜厚度影响较大.而离心力则显著影响滑靴的倾斜姿态,在离心力的倾覆力矩作用下,滑靴将沿径向向外倾斜,并且随着转速的提高倾斜程度加剧.     

A high-resolution environmental change record since 19 cal ka BP in Pumoyum Co,southern Tibet

A 380-cm-long sediment core was acquired from the deep water area of Pumoyum Co, southern Tibet. Twenty-five plant residue samples were selected, and organic carbon stable isotopes were obtained using the AMS ¹⁴C chronological method. The ¹⁴C age and carbon reservoir effect were calibrated with surface sedimentation rate measurements using ²¹⁰Pb dating. Results showed that the core sediment deposited over 19 cal ka BP. Based on a multi-proxy analysis of TOC and IC contents, grain size and pollen assemblage data, the palaeoclimatic evolution of Pumoyum Co was reconstructed since the last glacial. Pumoyum Co was a shallow lake prior to 16.2 cal ka BP; although the glacier around the lake began to melt due to increasing temperatures, climate was still cold and dry. In the interval of 16.2–11.8 cal ka BP, the sedimentary environment fluctuated drastically and frequently. Two cold-events occurred at 14.2 and 11.8 cal ka BP, and these may correspond to the Older Dryas and the Younger Dryas events, respectively. After 11.8 cal ka BP, Pumoyun Co developed into the deep lake as it is now. The lake water temperature was relatively lower at that time because of influx of cold water from glacial meltwater entering the lake. As a result, the multi-proxy indicators showed no sign of warm conditions. Comparisons between the sedimentary record of Pumoyum Co with that of other lakes of the same age in southern Tibet indicate a warmer climate following the last deglaciation influenced the southeastern Tibetan Plateau. These results imply that the southwest Asian monsoon gradually became stronger since the deglaciation during its expansion to the inner plateau. The glacial-supplied water of the lake responded sensitively to cold-events. The entire southern Tibet region was dominantly influenced climatically by the southwest Asian monsoon during the Holocene.     

分布式雷达超分辨成像的MUSIC方法

多重信号分类(MUSIC)方法已在单基地雷达的超分辨成像中得到较广泛的研究,然而将该方法直接应用到双/多基地形式的分布式雷达超分辨成像上,则会面临收发分置带来的散射信息解相关和波数相位分解等问题.为此利用三维空间平滑和双重线性插值对MUSIC方法进行了改进,给出了分布式雷达超分辨成像的最小信噪比显式表达及其快速计算公式,并据此分析了超分辨成像性能.仿真结果验证了这种基于收发分置形式的MUSIC超分辨成像方法的有效性.     

核反应堆压力容器模拟钢中纳米富Cu相的变形特征

提高了Cu含量的核反应堆压力容器(reactor pressure vessel,RPV)模拟钢样品,经过880 cC水淬、660℃调质处理和400℃1000～4000 h的等温时效处理,观察到纳米富Cu相的析出;随后进行20%～30%冷轧变形,采用萃取复型(extractionreplica,ER)和高分辨透射电镜(high resolution transmission electron microscopy,HRTEM)的方法研究纳米富Cu相的变形特征.研究结果表明,镶嵌在α-Fe基体中的纳米富Cu相,在冷轧变形时的变形机制较为复杂,存在多种变形方式.当纳米富Cu相的晶体处于有利取向时,可以跟随基体一起发生滑移变形,表现为"软"颗粒的特性;当晶体处于不利取向时,会发生孪生变形,甚至诱发马氏体相变,有时生成"轮毂辐条"状的孪晶结构,大大提高了纳米富Cu相继续变形时的抗力,表现为"硬"颗粒的特征,因而析出纳米富Cu相会产生明显的强化作用.     

附加失败率检验的长距离参考站网模糊度固定

对于长距离参考站网模糊度固定而言,Ratio检验和三角形模糊度闭合差(Triangle Ambiguities Closure Error,TACE)检验是最常用的两种模糊度检验手段,一般认为通过这两种检验后即可将模糊度固定。但事实上,在此情况下,模糊度被错误固定的情况经常出现。为此,本文提出了一种网解失败率(Network Failure Probability,NFP)检验方法,使用该方法可以计算出通过Ratio检验和TACE检验前提下参考站网模糊度固定的失败率。实验表明,当参考站数量小于等于8时,附加NFP检验后模糊度固定的正确率最高提高了25.4%,平均提高了8.1%,初始化成功率平均提高了4.3%。     

竖井井壁竖向附加力的理论计算方法

从弹性力学的空间轴对称问题出发,从理论上推导建立了竖井竖向附加力的应力表达式.分析该应力表达式可知,在竖向附加力作用下,井壁所受的径向、环向压应力值均为零,竖向附加力对井壁的作用主要体现为轴向压应力,且轴向应力在沿井壁厚度方向几乎无变化,因而可以将作用在井壁外侧的竖向附加力等效为作用在井壁横截面上的均布力.利用该应力表达式对某铁矿竖井井壁竖向附加力进行了计算,得到了井壁应力状况.     

乖讹-消解论下英语疑问句对校园幽默言语的诠释

基于乖讹-消解理论,探讨了英语疑问句在校园幽默言语的生成和理解中所起的作用,也进一步比较了无疑问句文本的幽默效果。分析结果表明,各种英语疑问句的使用可以充分解释校园幽默现象的乖讹识解过程,且起到铺垫、预设、增强幽默度等众多语用功能和良好交际效果,是幽默呈现的一个重要手段。     

计算晶体二阶示性面主轴的一种方法

介绍了由任意方向测试值来准确计算晶体主轴方向和主值的数值解法。以三斜晶系晶体为例，建立了数学模型及PASCAL程序流程图。实例证明该方法是简单有效的。     

浅谈三点法找动平衡在600MW机组轴流风机中的应用

简要分析了轴流风机振动的原因,结合实例,介绍了三点法对轴流风机作现场动平衡的基本原理和步骤,对此方法应用效果和优点作了说明。     

线性步进频率编码信号特性的研究

通过理论分析和实际计算,对线性步进频率编码信号(LSDFC)的模糊图、多普勒灵敏性和分辨力等特性进行了研究。结果表明这种信号易于产生和处理,适合用于要求大时宽大带宽的场合。