基于STAR-CCM+的船舶喷涂车间流固耦合模拟对比

目的对辐射采暖和热风采暖下的船舶喷涂车间和车间内固体工件表面温度进行对比分析,为船舶喷涂时选择采暖方式提供参考.方法通过STAR-CCM+5.02中新增的3D-CAD功能建立车间模型,选用软件中的辐射换热模型、对流换热模型以及耦合求解器,结合不同数据,模拟得到适合喷涂的结果.结果辐射采暖车间内温度基本稳定在23~24℃,固体表面温度在20℃左右,车间内气流速度达到0.20~0.30 m/s;热风采暖车间内温度基本稳定在18~23℃,固体表面温度在18~22℃,车间内气流速度达到0.35~0.50 m/s.结论辐射换热下车间内温度分布更均匀,气流组织速度更适合喷涂,而纯热风采暖下车间内温度会产生较大的梯度,气流组织受扰动较大,不利于喷涂.     

采暖地板对室内人体热辐射的理论计算模型

在基本假设和"人体柱"模型的基础上,建立采暖地板对室内人体热辐射的理论计算模型.利用该理论模型,对矩形等温地板的采暖辐射特性进行计算分析.结果表明,人体在室内不同位置所受到的热辐射量是不均匀的.在地板中心处,人体所受到的热辐射量最大,而在地板角点处,人体所受到的热辐射量最少.将人体工作和停留时间长的区域靠近地板中心区布置,可提高辐射采暖的能量利用效率;将热媒质从地板周边逐渐向中心盘旋引入,可使地板周边有较高的表面温度,提高室内辐射采暖的均匀性.     

地板辐射采暖传热模型修正及散热因素分析

楼板向下散热量和内外墙体温度差异较大时,利用现有的模型计算地板辐射采暖系统地面温度分布导致误差较大.通过分析内外墙和楼板对地板辐射采暖系统传热的影响,找出零热面模型的不足,修正了传热模型,并分析影响采暖盘管的散热因素.研究结果表明, (1)内外墙体的壁温相差大时,零热面模型误差偏大,则内外墙边界条件设为第一类边界条件较合理;(2)楼板下表面设为由辐射换热等效的第三类边界条件较合理;(3)管径增大导致地板表面温度增加趋势减小.管间距、热水温度增大导致供热区域地板表面温度分布呈周期性变化逐渐明显.且管间距变大导致其周期增加、热水温度变大导致其振幅增加.选择合适的地板层材料才能保证舒适的地面温度.     

地板辐射采暖盘管泄漏传热模型及数值模拟

低温热水地板辐射采暖盘管对系统的安全运行具有重要意义。由于室内装修等施工作业造成地板辐射采暖盘管缺陷,从而导致系统运行时泄漏事故的发生,为减低此类事故的危害性及时判定泄漏点位置对防止泄漏的扩散尤为重要。本文通过分析地板辐射采暖盘管泄漏特性,建立盘管泄漏过程传热传质模型,并利用FLUENT软件模确定盘管泄漏前后地板和水泥层表面温度场分布情况。研究结果表明：（1）盘管泄漏初期,水泥层表面原始温度场迅速被破坏,而整个地板表面变化较弱;随着泄漏时间的加长,地板表面温度场也造成破坏,可以通过其表面温度场明显判断泄漏点位置。（2）泄漏影响区域主要由三个区域组成,在泄漏口附近较大区域为1区恒定高温区,温度梯度变化较小;临近1区外为2区温度梯度区,温度梯度变化剧烈;受泄漏影响较弱区域为3区地板稳态温度区,其温度主要由原始地板温度场控制。     

模块带腔地板辐射供暖系统数值模拟

为建立验证并完善模块带腔地板辐射供暖系统的CFD数值计算模型,运用数值计算模型对影响模块带腔地板辐射供暖系统的参数进行分析.建立模块带腔地板辐射供暖系统的计算模型,利用CFD软件进行模拟计算,分析供回水温度变化时地板表面平均温度,并与实验测得的数据进行对比,验证模型的正确性.利用验证后的模型,分析盘管间距对地板表面温度的影响.结果表明:所建立的CFD数值计算模型与计算方法是可行的;在供回水平均温度相同情况下,地板平均温度模拟结果与测试结果均存在1℃左右偏差,但相对偏差可以控制在5%以内.结论:盘管间距越大,模块带腔地板辐射供暖系统地板表面温度相对越低,间距对本系统的影响不可忽视.     

空间低温冷屏蔽系统及表面温度分布研究

提出一种"空间冷屏蔽系统"模型,通过空间深冷剂的相变制冷可使空间飞行器表面温度低于100 K,30 min内使表面红外辐射强度低于0.5 W/m2;进而建立三维气液分离储液模型,并对分层储液结构进行单元传热数值模拟,分析单元模型的不同传热边界条件,将换热经验关联式应用于稳态传热数值模拟过程,从而获得冷屏表面温度及热流随液位变化的分布规律;然后建立单元实验模型并进行实验分析.模拟计算及实验结果表明:当分层储液高度小于100 mm时,实验温度梯度与数值模拟结果相似;实验系统的表面温度在地面15 min以内、空间30 min以内可以满足低温红外辐射特征要求;太阳能辐射强度和毛细材料对表面温度分布的均匀性及液氮维持时间有一定的影响.     

几种采暖系统应用于锡林郭勒盟典型民居效果对比

以热舒适度为主要参数分析研究锡林郭勒盟地区冬季常用三种室内采暖方式,即暖气采暖方式、低温热水地板辐射采暖方式和传统火炉子采暖方式。利用FLUENT软件模拟三种采暖方式在室内传热的温度场,由模拟结果绘制出三种采暖方式的室内温度分布曲线。通过比较三种采暖方式的室内温度分布曲线与人体舒适时室内温度分布曲线,结果表明,低温热水地板辐射采暖的室内温度分布曲线与人体舒适时室内温度分布曲线最相近。因此,建议当地居民在选择采暖方式时可优先选用低温热水地板辐射采暖。     

地板辐射采暖系统的特点及应用前景

低温地板辐射式采暖系统因其热舒适性高、卫生条件好、可利用热源多等优点被越来越多地应用在住宅、餐厅、商场等建筑以及室外路面、户外运动场的地面化雪等工程中。低温地板辐射采暖的优点地板辐射采暖是将加热盘管埋置于混凝土埋管层中,让低温热水在管内循环流动,加热整个地面,使表面温度升高,然后通过辐射和部分对流方式向室内散热的一种供暖方式。降低室内设计温度,节能效果明显。人体的舒适度取决于室内平均辐射温度(MRT)。当采用地板辐射采暖时,由于室内围护结构内表面温度的提高,其平均辐射温度也随之提高,一般MRT比室温Tn高1℃～…     

晶圆片快速热处理工艺中温度非均匀性研究

采用传导与辐射耦合传热模型,对晶圆片内传热过程进行了数值模拟,研究了热传输特性变化对于晶圆片表面温度非均匀性的影响.结果表明:硅与掺杂硅导热系数的提高有助于减小沿晶圆片表面的温差,而总的温度水平变化很小;当吸收系数从104降至103 m-1时,晶圆片顶部表面的温度水平和温差骤降,当吸收系数等于103 m-1时,温度水平和温差变化不大;发射率对于晶圆片顶部表面温度水平和温差具有主要影响,提高发射率可以轻易增加晶圆片表面的温度水平;使用改善后特性数据,总的温度水平较基础算例降低约200K.研究结果有助于认识快速热处理工艺中能量传输过程、改善温度监测和控制水平.     

低温热水地板辐射采暖供暖效果及节能优势分析

由于建筑节能的势在必行,低温热水地板辐射采暖在住宅中的应用越来越广泛,本文通过对低温热水地板采暖的传热计算,得出房间温度分布整体较均匀,温度场水平分布和垂直分布的差异较小,可改善人类居住环境的舒适性。并通过实测值与传热计算值的对比分析,说明地板以上0.5m处温度下降较大,0.5～2m处温度开始上升,但温度梯度较小。由此分析低温热水地板辐射采暖系统的建筑节能优势。     

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.     

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.     

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.     

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.     

A computer generator for randomly layered structures

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

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.     

Jane Eyre——A Feminist In The 19th Century

In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-