非等温空腔法确定固体材料的比辐射率

本文讨论一种确定固体材料比辐射率的方法。在被测材料的表面开一个圆柱形空腔,并在其背面均匀加热。联立求解腔壁的辐射换热和体内的热传导方程,求得温度场分布和腔底的有效辐射。结果表明,腔底的有效辐射是比辐射率、腔深和半径之比以及一个表示温度梯度的参数的函数。文中讨论了能量辐射和光子辐射两种情况。在实验中,用热象仪测量材料表面和腔底的有效辐射。由理论分析结果和实验测定的有效辐射,求得材料的比辐射率。     

敷设空腔覆盖层的水下弹性球壳散射特性

研究敷设空腔覆盖层的水下弹性球壳声散射特性对探测和识别水下目标具有重要意义。利用 COMSOL有限元软件对水下弹性球进行仿真,获得目标强度的数值解,通过与理论解对比验证了该方法可用于计算水下球形结构的声散射特性。通过对弹性球壳敷设覆盖层前后的目标强度进行仿真,对比结果指出敷设空腔覆盖层能有效降低球壳的目标强度。进一步讨论覆盖层材料参数和空腔结构变化对弹性球壳声散射特性的影响,结果表明：空腔比、覆盖层厚度和损耗因子值越大,目标强度越小;与圆柱、圆台空腔相比,圆锥空腔的目标强度最低。     

超声脉冲纵波在固体中传播的可视化研究

为了研究超声脉冲波在钢、铁等金属材料中的传播规律,我们采用和金属材料声速比较接近的k9玻璃作样品,利用研制的动态光弹系统,来观察超声脉冲纵波在玻璃中的传播,由此来模拟超声波在金属中的反射、散射等传播行为.对于利用超声脉冲波检测金属材料缺陷的理论提供了实验依据.     

超声波清洗技术的应用及优势

超声波是一种频率超出人类听觉范围17kHz以上的声波。其传播要依靠弹性介质。其传播时，使弹性介质中的粒子振荡。并通过介质按超声波的传播方向传递能量，这种波可分为纵向波和横向波。在固体内，两者都可以传送，而在气体和液体内，只有纵向波可以传送。     

混凝土材料动态球形空腔膨胀的数值模拟

为了验证固体中的空腔膨胀理论,基于混凝土三段式本构模型,用有限元方法对混凝土材料动态球形空腔膨胀进行了数值模拟.数值模拟结果表明,当空腔膨胀压力超过一定阈值后,空腔边界将以该压力对应的恒定速度膨胀,符合空腔膨胀理论中膨胀压力与边界膨胀速度的函数关系.进一步分析表明膨胀压力阈值与混凝土强度呈线性关系.混凝土中空腔边界到弹性波阵面之间的径向应力场分布与理论计算相符,证实了数值模拟的可靠性,揭示了空腔膨胀的物理过程.     

超声波对测法检测钢管混凝土

随着新型材料及超声波技术的日趋成熟,在近年的一些钢管材料运用中,出现了钢管混凝土的材料。为了快捷方便了解钢管中混凝土的质量,CECS21:2000中采用了超声波无损检测法中的对测法。运用这一方法可以方便地从超声波的时域波形和频谱曲线中分辨出直达纵波和沿钢管壁传播的面波,从而利用纵波声学参数达到检测钢管中混凝土质量好坏的目的。     

固体媒质中异质球形散射体的声散射特性

复合材料的物理性能和基材中填充物的复合状态有着密切的关系。应用声散射方法研究复合材料复合状态是材料评价的常用方法之一。在许多情况下，基材中的填充物呈现球状，因此对基材中球形填充物的散射研究是人们十分重视的研究课题。然而以前的研究中，大多数讨论了纵波或横波入射时单一球形固体、流体或真空腔体的散射特性，对同一基材中不同性质材料球形散射体的散射谱特性及影响散射谱的因素较少涉及。而后对复合材料的评价很有意义。首先介绍了固体中异质球形散射体的声散射理论模型，然后数值计算了同一基材中不同材料和散射体对入射平面声纵波的散射谱特性。结果表明，散射体的归一化散射截面谱同基材和散射体的声速在速度状态图上的相对位置有直接的关系；散射截面随频率的变化规律在低频区的特性主要反映了散射横波的性质，而在高频区则反映了散射纵波的特性。     

辐射腔体的空腔效应

由辐射性能一致的漫射表面组成的腔体,在温度一致的条件下,其辐射行为可以归结到由腔体开口的表现来描述,这就是所谓空腔效应。本文从辐射表面之间的换热规律出发,推导出反映空腔效应的定量概念－空腔因子,建立了空腔因子与腔体形状和腔体材料的关系。     

页岩各向异性的全光学检测

本文利用全光学方法对不同地区的页岩样本进行各向异性检测.利用激光在页岩等岩石中激发产生超声波,基于激光干涉原理对超声波速进行检测,从而获得页岩层理结构的各向异性分布特点.检测结果表明超声纵波波速与页岩层理结构吻合得很好.超声纵波沿页岩层理面传播时速度最大,垂直页岩层理面传播时速度最小,超声波速关于页岩层理方向以正弦规律对称分布.不同地区的页岩超声波速也不同.全光学检测方法可以实现对页岩层理结构的快速判断,根据在页岩中传播的超声波速可了解页岩的致密度及各向异性强度,对页岩储层的开发具有一定指导意义.     

空腔在激光闪光法测量比热中的应用

闪光法测量材料的导温系数、比热和导热系数由W.J.Parker等于1961年首次提出。由于该方法在测量导温系数方面具有许多优点,因此至今仍被广泛采用。但所提出的比热测量方法不仅精度低操作复杂,而且需要两次试验才能得到比热数据,因此无法实现快速综合测试。本文提出的测量比热新方法是基于空腔原理,其要点是在一个密闭的空腔上开一小孔,激光通过该小孔进入空腔内经多次反射后几乎全部被空腔吸收,因此可把空腔看成是一个对光的绝对吸收体。应用空腔原理实现对比热测量的要点是:首先应用一个比热为已知的壳体与样品共同组成一个空腔,二者之间相互绝热,当具有已知能量的激光进入空腔后,经过在腔内的多次反射,该能量最终将被壳体和样品吸收,壳体吸收的能量可通过测定壳体温升求得,因此样品吸收的能量及比热也可随之得到。由于激光是经过聚焦后进入空腔的,因此壳体上的小孔可以做得很小,从而大大减小了把空腔视为绝对吸收体所带来的误差。样品的导温系数可与比热同时测得,导热系数可通过比热、导温系数及密度计算出来。应用本方法测得了Fe、Ni、Cu、Mo等金属的室温比热、导温系数和导热系数,这些数据与有关文献一致。本方法与传统方法比较有如下特点; 1.能在单次激光脉冲作用下,同时获得比热、导温系数、导热系数三个热物理量。 2.样品表面无需特殊加工和处理。 3.比热测量的精度及可靠性高。     

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.     

A computer generator for randomly layered structures

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