双层微穿孔管消声器传声损失理论计算与分析

基于一维平面波理论和微穿孔结构吸声理论,推导双层微穿孔管消声器传声损失理论模型,并将理论计算值与三维有限元声学仿真结果进行对比,利用消声器传声损失理论公式,对比双层和单层微穿孔管消声器的传声损失,分析内外层膨胀腔厚度对双层微穿孔管消声器声学特性的影响。研究结果表明:双层微穿孔管消声器在中低频的传声损失要大于单层微穿孔管消声器;增加内外层膨胀腔的厚度,可以提高双层微穿孔管消声器的消声特性;当双层膨胀腔总厚度固定,外层膨胀腔厚度大时,消声器在中低频的声学性能更好。     

摩托车排气消声器声学性能仿真及结构改进

针对某244S摩托车排气消声器,采用有限元法建立了该消声器的声场模型和流场模型,利用SYSNOISE软件对该消声器进行了三维声学仿真,在声场仿真基础上提出对原消声器的改进方案,优化了原消声器内部结构。通过对改进后的消声器进行仿真与台架试验对比,改进后的结构比原消声器在中、高频的消声能力有显著的改善,仿真和试验结果吻合较好,同时流场仿真结果显示,改进后消声器功率损失变化不大,表明对原消声器结构的改进是有效的。     

内燃式叉车排气消声器结构优化设计

为降低某3t内燃式叉车的排气噪声,在不改变消声器的外部结构的前提下,优化消声器的内部结构,改进排气消声器的性能指标。通过对消声器的网格分析,利用某声学仿真软件模拟计算改进前后两种消声器的传递损失。结果表明改进后的消声器比改进前的声学性能好,说明模拟软件在设计研发中的重要性,并为消声器的结构优化设计提供依据。     

基于响应面法的听小骨消声器的优化设计

为了改善听小骨消声器的消声性能,并减轻质量,以消声器低频和宽频的平均传递损失作为优化目标,以消声器的结构参数(进出口管道宽度、封闭腔深度、封闭腔长度)作为优化变量,消声器的质量作为约束条件,对其结构参数进行优化.建立了听小骨消声器的有限元模型,采用中心组合试验设计获得样本点,利用响应面法构造二次多项式响应面模型,并检验了响应面模型的拟合精度.将响应面模型和NSGA-Ⅱ遗传算法相结合对消声器的结构参数进行了优化.优化后消声器低频和宽频的消声性能得到改善,质量减轻,表明了响应面法和遗传算法相结合的消声器结构参数优化方法的有效性.     

大口径水消声器的设计及性能实验

提出了一种新型的流体脉动噪声消声器,其优点是直径小、安装方便、消声效果好,与膨胀腔式消声器相比有显著的优势;实验结果表明所设计的水消声器不仅结构紧凑,而且在很宽的频率范围内都有令人满意的消声效果;适用于安装在大口径管路上消除水泵以及阀门产生的流体噪声。     

小排量发动机消声器性能仿真计算与优化研究

为满足严格的汽车噪声法规以及对汽车舒适度的需求,课题组以某款汽油机消声器为研究对象,将传递损失作为消声性能的评价指标,基于ANSYS软件建立消声器有限元模型,并通过SYSNOIS软件对其模型进行分析计算。利用建模方法模拟分析消声器各个扩张腔的性能,通过模拟实验可以得出以下结论：实验测试消声器第一、第二扩张腔对中低频消声效果较差;由原排气消声器传递损失分析结果可知,第一、第二扩张腔进出口处增加内插管的结构方案最优。仿真结果表明：当进口内插管、出口内插管长度正好为扩张腔长度的0.5倍与0.25倍时,此结构优化方案可有效提高排气消声器的消声性能。     

手扶拖拉机排气消声器设计与试验研究

柴油机排气消声器的长度、直径及内部结构是其消声量的主要控制参数．本文根据所设计的多级扩张式消声器，通过实验研究以寻求各参数优化组合方案，为设计最佳消声效果的消声器提供依据     

横流穿孔管消声器声学及阻力特性的数值分析

横流穿孔管消声器具有较宽的消声频带和良好的消声性能,被广泛应用于汽车排气噪声控制。本文应用三维数值分析方法,研究了横流穿孔管消声器的声学及阻力特性。得出如下结论:穿孔率是影响声学和阻力损失的最重要参数;穿孔直径对声学性能影响较小但对阻力损失影响较大;膨胀腔尺寸和气流速度的改变对声学和阻力损失都产生一定的影响。     

对规则腔与非规则腔消声器声学特性的对比分析

利用计算流体动力学软件及声学仿真软件,进行规则腔及非规则腔消声器内部流体动力学仿真、压力损失计算和传递损失分析,获得了腔体长度一定,截面积相等的圆形截面、椭圆截面和矩形截面的声学特性。仿真结果表明,非规则腔相比于规则腔消声器,异形口截面消声器压力损失更大,消声效果更好。穿孔率对消声器降噪效果有影响,穿孔率为12%时,中高频段噪声降低3.4dB。该研究结果为非规则腔消声器的优化设计提供了参考依据。     

简单扩张式消声器的CFD仿真

用CFD软件FLUENT对两种不同结构形式的简单扩张腔消声器的速度场、压力场进行三维稳态流动数值模拟,研究相应压力损失随入口流速的变化趋势.研究结果表明:内插管对消声器的流场和压力损失有较大的影响,带内插管的消声器阻力损失比未带内插管的要小,原因是内插管对气流产生导流的效果.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to