干缩法、力学法、电学法测定木材纤维饱和点的研究

<正>本文利用干缩法、力学法、电学法分别对针叶树马尾松、阔叶树钩栗的纤维饱点作了测试,得出了与经典的纤维饱和点相近的数值,并对干缩法、力学法、电学法的测试方法作了探索。通过实验曲线和理论推导得出了干缩法测定纤维饱和点的简便公式,它不仅减轻了测量的工作量,而且进一步提高了测量精度。同时,对这三种测定方法的利弊进行了较系统的分析和比较。     

不同竹龄毛竹材纤维饱和点的测定

以毛竹为研究对象,采用力学法对不同竹龄毛竹的纤维饱和点计算进行了系统研究。结果表明：通过Boltzmann曲线拟合毛竹材力学性能得到的毛竹纤维饱和点较为合理,利 用4种力学性能指标所测得同一竹龄毛竹材纤维饱和点略有差异。纤维饱和点随竹龄的变化规律相同,即从0.5~1.5年生降幅明显,大于1.5年生后趋于稳定。     

日本落叶松幼龄材干缩性能轴向变异

测定了建始县长岭岗林场引种栽培的12a生日本落叶松标准木干缩性能指标，并分析了它们在轴向上的变异，结果表明：径向全干干缩率为4．63，弦向全干干缩率为6．82，径向气干干缩率为2．41，弦向气干干缩率为3．92，体积气干干缩率为6．49，以上指标在轴向不同部位差异不显著，但有由基部至梢部逐渐变小的趋势；全干差异干缩为1．47，气干差异干缩为1．62，在轴向变异不明显且相对较稳定；体积全干干缩率随轴向部位变化而差异显著，且主要存在于基部与近梢部之间．     

回收轮胎聚合物纤维混凝土干缩性能研究

为研究回收轮胎聚合物纤维(RTPF)对混凝土干缩性能的影响，对素混凝土、RTPF混凝土(体积分数分别为0.1%，0.2%，0.4%和0.8%)和聚丙烯纤维(PPF)混凝土(体积分数为0.1%)进行干缩试验和纤维作用机理分析.结果表明:不同掺量RTPF混凝土比素混凝土坍落度降低8.1%~62.2%，含气量增大11.2%~47.9%；RTPF混凝土的干缩率在0~7d时增长速率较快，之后逐渐平缓，RTPF的加入降低了混凝土干缩的早期增长速率；混凝土干缩率随RTPF掺量的增加出现先降低后升高的趋势，当RTPF体积分数为0.2%时混凝土干缩率出现最小值，不同掺量RTPF混凝土在7d和28d时的干缩率分别比素混凝土降低了14.2%~36.0%和2.9%~27.2%；相同体积分数(0.1%)下PPF混凝土的干缩率比RTPF混凝土低，在抑制混凝土干缩方面体积掺量0.2%的RTPF可替代体积掺量0.1%的PPF；扫描电子显微镜测试表明，RTPF可与混凝土基体有效黏结，并承担来自混凝土基体的收缩应力；通过干缩率的拟合值与实测值对比得到适合RTPF混凝土的干缩计算模型.     

汽蒸处理对青冈栎干缩系数及气体渗透性的影响

研究了常压、汽蒸处理对青冈栎（Cyclobalanopsis spp.)干缩系数，气体渗透性及含水率的影响，结果表明：青冈栎的径向、弦向和体积干缩系数在汽蒸处理5h后稍有增加；汽蒸处理后的顺纹渗透性处理前的2倍，处理前后的横纹渗透性基本不变，试材含水率降低5％左右。     

合成纤维织物和棉织物热风干燥特性的实验研究

采用合成纤维和棉织物作为实验样品，对纤维织物的热风干燥过程进行了实验研究，得到了在不同干燥工况条件下的纤维织物温度和干基含水率变化曲线，对合成纤维织物和棉织物的表面温度和干基含水率变化特性进行了仔细分析。在热风干燥中，织物温度与干基含水率均存在4个 阶段的变化，不同的织物具有不同的干燥特性。织物的干燥是在恒速干燥阶段完成，其干燥速率由水分表面气化速度所控制；纤维织物热风干燥的临界含水率约为10％左右，降低织物的临界含水率和延长织物的恒速干燥阶段时间均有助于提高织物的干燥质量。     

毛竹不同高度径向弯曲性能的变化

对竹材不同距地高度径向位置的弯曲性能进行了研究,并应用DENSE-LABX端面密度仪测定竹材沿端面的密度分布情况,分析了密度的变化与竹材弯曲力学性能的关系。结果表明:竹材的静曲强度(MOR)和弹性模量(MOE)沿径向均是从最内层竹黄处向竹青处逐渐增大,MOE的差异更加显著;竹材的弯曲性能随着密度的增大而增加,趋势接近于线性变化。     

利用有限样点重建原木外形的研究

讨论了利用有限样点数据重建原木外形的方法，给出了三次样条函数及抛物线方程的参数向量表达式，并分析了用这两条曲线分别拟合原木长向曲线及断面形态曲线的拟合误差。结果表明，采用抛物线调酸曲线拟合原木断在曲线在采样点为１２时是比较合适的，拟合的最大误差为３．６４％，平均误差为０．９３％；采用样条参数曲线拟合长向曲线在采样点为５１６点时误差水平较低，最大误差不超过５％，平均误差不超过１％。     

基于毛细孔张力理论的混凝土干缩模型

以毛细孔张力理论为基础,采用ANSYS有限元软件建立了混凝土内单个毛细孔的数值分析模型,对混凝土的干缩应变和干缩应力进行了模拟计算.假定混凝土内液体表面张力为定值,凹液面主曲率半径依次下降为不同值,利用ANSYS有限元软件计算毛细孔相应的径向收缩位移,据此计算单个毛细孔的体积干缩应变及相应混凝土的体积干缩应变.其次,计算当凹液面主曲率半径下降幅度不变,而使毛细孔隙内液体表面张力依次降低,利用同样的方法计算相应的单个毛细孔的体积干缩应变及相应混凝土的体积干缩应变.根据上述计算结果,分别绘制混凝土的体积干缩应变随混凝土毛细孔隙内凹液面主曲率半径及液体表面张力的变化曲线,从而近似地找出了混凝土干缩应变与毛细孔内液体表面张力、凹液面主曲率半径之间的关系.从微观角度建立了混凝土干缩应变的估算模型.     

纳米气体传感器灵敏度-温度曲线的拟合

通过试验测试了苯纳米气体传感器的灵敏度随温度变化的规律.在所得实验数据的基础上,应用Matlab软件对苯纳米气体传感器的灵敏度-温度特性曲线进行了拟合.对最小二乘法的分段多项式与三次样条曲线两种方法在传感器特性曲线拟合中的特点进行了理论分析及比较,发现两种方法的拟合精度虽然均为10-3,但分段多项式的拟合相对误差为±1.5％,各段拟合曲线连接点处出现断点现象;而三次样条函数的拟合相对误差仅为±0.5％,各段拟合曲线连续性好,整条曲线光滑.     

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.     

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.     

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.     

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.     

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.     

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-