超超临界汽轮机高压缸旁路冷却系统冷却特性研究

采用耦合流动计算和共轭传热的数值方法研究了1 000MW超超临界汽轮机高压缸旁路冷却系统的冷却特性,给出了系统作用下高压缸内外缸和轴端平衡活塞等固体部件的温度场分布特性,对比了有/无内部旁路冷却系统在不同条件下高压缸的温度场。研究结果表明:超超临界汽轮机高压缸旁路冷却系统能有效冷却高压缸内缸和轴端平衡活塞,使整体温度水平明显下降,高压缸外缸温度略有上升,高压缸内缸在旁路冷却系统的作用下温度分布均匀;对于阶梯式平衡活塞的冷却作用,主要取决于3段汽封长度、汽封齿间隙及平衡活塞前径向间隙。     

6110型柴油机活塞温度场及底喷冷却研究

采用三维建模软件Pro/Engineer建立了活塞的三维模型,将模型导入Ansys中进行活塞温度场的数值模拟,得到活塞三维温度场的分布;经过底喷冷却后使得活塞燃烧室中心部位温度降低了34℃,第1环槽和第1环岸温度分别降低了8℃和12℃.活塞的底喷冷却一定程度上对活塞的结构设计和改进提供理论依据.     

冷却油腔位置改变对活塞温度场的影响

研究活塞冷却油腔位置改变对活塞温度场的影响.采用Pro/E软件建立德国1015型柴油机活塞的有限元模型(FEM).在性能计算的基础上确定了活塞顶等部位的热边界条件.利用ANSYS软件研究活塞振荡冷却油腔位置改变后,活塞各关键部位温度的变化规律及其对冷却油腔位置的敏感程度.结果表明,冷却油腔位置对活塞各部位温度的影响规律有较大的差别.冷却油腔位置改变对活塞第一环槽影响最大,不仅温度的变化速度有极值点,而且通过移动冷却油腔可以使第一环槽的温度降低约30℃.     

大型高炉合理炉缸冷却制度

合理的炉缸冷却制度是保证大型高炉长寿的基础,不同冷却制度对高炉炉缸的温度分布和侵蚀状况具有直接影响.结合某4000 m3级高炉,根据传热学理论建立了高炉炉缸、炉底温度场物理模型和数学模型,通过数值模拟对"大水量、小温差"和"小水量、大温差"这两种不同炉缸冷却制度进行了研究,分析了不同冷却制度对炉缸温度场、炉缸侵蚀状况及高炉寿命的影响.结果表明,在炉役初期砖衬较厚时,不同冷却制度对炉内温度分布的影响区别不大;随着砖衬的不断减薄,不同冷却制度对炉内温度分布的影响逐渐明显;当砖衬侵蚀到一定程度后,再好的冷却也无济于事,但采用"大水量、小温差"并加强冷却可以减缓砖衬的侵蚀,延长高炉寿命.     

风冷压缩机气缸热交换的实验研究

采用测温系统测量微型风冷空压机缸壁温度场的分布,在不同散热片高度条件下对缸壁温度及排气量、功率进行了测量。分析不同散热片高度对缸壁温度场、压缩机性能的影响。对实验数据采用线性回归方法,总结了缸壁平均温度随压比、进气温度和活塞行程变化的经验公式。     

发动机拉缸现象原因浅析

我矿是露天煤矿，全矿绝大部分工程机械配有柴油或汽油发动机。在多年的检修、鉴定、维护、保养等工作中，对发动机常见的故障之一，拉缸现象的原因，进行一定的研究和分析，并取得了一定的经验。所谓拉缸，是指气缸壁上沿活塞移动方向，出现一条条深浅不等的沟纹。严重时影响气缸的密封性，必须及时进行修理。在理论上的认识：拉缸是在无外来物的情况下，由于环表面与缸套内表面滑动接触时，在极小的面积上产生很高的温度所致，这一高温会进而引起环与缸壁间熔着，或当所产生的热量散失后，在活塞环上形成碳化物。这种碳化物或熔着物非常坚…     

振荡冷却活塞温度场及热机耦合分析

为分析内冷油腔对活塞的降温效果,对振荡冷却活塞在热负荷、机械负荷及热机耦合作用下的温度场及应力应变分布规律进行研究。采用VOF（volume of fluid）多相流模型、动网格技术等对活塞内冷油腔内机油的振荡传热过程进行Fluent数值模拟,得到内冷油腔各壁面换热系数;将结果映射到活塞固体表面,对活塞分别加载热负荷、机械负荷以及热机耦合作用,对比分析活塞在内冷油腔冷却前后的温度场变化,得到其热应力、机械应力以及耦合应力的变化规律。结果表明,采用内冷油腔进行冷却后,活塞各区域温度均有不同程度下降,其中活塞最高温度下降7.5%;活塞受热机耦合作用下的最大应力小于两者单独作用的结果之和;进行油腔振荡冷却后,活塞的热应力和耦合应力也有不同程度降低。所得到的活塞在内冷油腔冷却前后的应力分布规律,可为活塞内冷油腔的优化设计提供理论参考。     

解钩风缸组装工艺性研究及优化设计

解钩风缸是动车组用密接式全自动车钩的重要装置,主要用于密接式全自动车钩的自动解编。在解钩风缸国产化过程中发现按图纸加工的缸筒组件和活塞组件组装时容易产生卡死现象,造成解钩风缸无法组装。本文通过研究解钩风缸缸筒组件和活塞组件组装过程中的几何关系,得到活塞组件与缸筒组件顺利组装的条件,使活塞组件顺利装入缸筒组件。该方法在生产实践中取得了良好的效果,可作为设计和校核此类产品的一种方法。     

超临界汽轮机中压透平级流动传热特性研究

通过采用耦合流场计算和共轭传热的数值方法,研究了超临界汽轮机高压缸冷却蒸汽对中压缸第一级固体部件的冷却特性及其对级气动性能的影响,同时对比了有无蒸汽冷却的中压缸第一级的流场和温度场.结果表明:蒸汽冷却技术可以有效地对中压缸第一级动叶叶片、叶根、转子及轮盘进行冷却.受到冷却孔的抽吸作用而进入冷却孔的冷却蒸汽对冷却孔及周围的叶根区域具有明显的冷却作用.在蒸汽冷却的作用下,中压缸第一级转子系统温度下降的最大幅度达80 K.部分冷却蒸汽进入中压缸第一级叶栅主流道并与主流掺混,从而使得根部反动度增大,动叶通道涡强度增加.所以,蒸汽冷却技术可以有效提高高温转子的运行寿命和安全的可靠性.     

基于有限元的发动机受热零件温度场分析

针对490柴油机燃烧室改型后各受热零件热负荷上升的问题,采用有限元方法对其进行温度场的计算分析.在应用VB高级计算机语言编程计算气缸内气体瞬时温度和瞬时放热系数作为有限元热分析边界条件的基础上,用UG软件对活塞、缸盖及缸套进行三维建模,并导入有限元软件ANSYS进行网格划分.在ANSYS软件中采用热分析单元对各零件的温度场进行了模拟计算.结果表明:该机活塞的最高温度出现在受燃气影响最大的燃烧室喉口位置,活塞整体温度分布沿轴线向下逐渐降低,第1道环槽处温度值偏高易出现热故障,在优化设计中应采取冷却或隔热措施;缸盖底板火力面的最高温度出现在受进排气影响最大而冷却困难的鼻梁区;缸套温度沿轴线方向从上往下逐渐降低.     

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.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

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.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

橡胶颗粒沥青混合料低温抗裂性试验研究

以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.     

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。     

Quantitative trait loci （QTLs） for quality traits related to protein and starch in wheat

Quality traits in wheat （Triticum aestirum L.） were studied by quantitative trait locus （QTL） analysis in a recombinant inbred line （RIL） population, a set of 131 lines derived from Chuan 35050 × Shannong 483 cross （ChSh）. Grains from RILs were assayed for 21 quality traits related to protein and starch. A total of 35 putative QTLs for 19 traits with a single QTL explaining 7.99-40.52% of phenotypic variations were detected on 10 chromosomes, 1D, 2A, 2D, 3B, 3D, 5A, 6A, 6B, 6D, and 7B. The additive effects of 30 QTLs were positive, contributed by Chuan 35050, the remaining 5 QTLs were negative with the additive effect contributed by Shannong 483. For protein traits, 15 QTLs were obtained and most of them were located on chromosomes 1 D, 3B and 6D, while 20 QTLs for starch traits were detected and most of them were located on chromosomes 3D, 6B and 7B. Only 7 QTLs for protein and starch traits were co-located in three regions on chromosomes 1D, 2A and 2D. These protein and starch trait QTLs showed a distinct distribution pattern in certain regions and chromosomes. Twenty-two QTLs were clustered in 6 regions of 5 chromosomes. Two QTL clusters for protein traits were located on chromosomes 1D and 3B, respectively, three clusters for starch traits on chromosomes 3D, 6B and 7B, and one cluster including protein and starch traits on chromosome 1D.     

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.     

The Analects and the Moment in Peking——The influence of a Confucian education system on the personality formation,the way of thinking and the fate of the main characters

0.Preface China has long been boasting of its colorful and immense culture which comprises of Taoism,Confucianism and Buddhism.The interwoven influence among the religions on Chinese way of thinking,on the nation＇s behavior in their social life throughout the long history is beyond list.