高湿模量粘胶短纤维牵伸机的研发

介绍了高湿模量粘胶短纤维的概念,分析了高湿模量粘胶短纤维牵伸机的主要工艺特点及其各功能部件的设计要点。

细旦高湿模量粘胶针织纱的研制

根据细旦高湿模量粘胶纤维的特性和针织用纱的质量要求,针对性地设计了15tex高湿模量粘胶纱的纺纱工艺、各工序工艺参数,并探讨了纺制中各工序技术关键及采取的措施。

高湿模量粘胶短纤维纺丝机的研发

介绍了高湿模量粘胶短纤维的概念,分析了高湿模量粘胶短纤维纺丝机的主要工艺特点及其各功能部件的设计要点。

基于粘弹性阻尼层随机性的自由阻尼层板的振动和阻尼分析

本文基于粘弹性阻尼层的随机性用MonteCarlo直接抽样法对自由阻尼层板的振动和阻尼进行了分析研究。分析中随机变量取正态分布。针对不同的阻尼层厚度分别考察了复弹性模量的实部、虚部、材料的损耗因子的影响。考察了整体性和局部单元性阻尼层厚度的影响。结果表明 ,粘弹性材料弹性模量的随机性对结构固有频率的影响不大 ,对模态损耗因子影响较大 ;不论是整体的还是局部单元的 ,阻尼层厚度的随机性对模态损耗因子的影响很显著。因此粘弹性阻尼层的随机性对抑制结构共振响应和声辐射的影响是较大的。阻尼层厚度局部单元随机性的影响表明了对阻尼结构采用随机分析的必要性。

固体推进剂粘弹泊松比的研究

分析了弹性油松比和粘弹油松比的不同概念和意义．推导出了拉伸松弛模量Ｅ（ｔ），体积松弛模量Ｋ（ｔ）和粘弹泊松比ν（ｔ）的相互积分方程关系式及其求解ν（ｔ）的数值积分算法．以Ｅ（ｔ），Ｋ（ｔ）的实测结果作为算例依据，求得一种改性双基推进剂的粘弹泊松比ν（ｔ）的结果、变化规律及其数学表达式．

原位测定土的复数模量的理论探讨

计算承受动荷载的地基基础体系的关键问题，是要正确估计土的动力性质。本文通过积分与微分形式的物理方程，选用复数形式解答场方程中的动力参数，并用波动法原位测定土的粘弹性模量。

松弛与蠕变力学特性转换关系的研究

本文首先论述了拉伸应力松弛模量Ｅ（ｔ）与拉伸蠕变柔量Ｄ（ｔ）之间的近似与精确转换关系式，提出一种诊断Ｄ（ｔ）的数值积分算法。通过应力松弛模量实验给出一种固体推进剂的Ｅ（ｔ）和Ｄ（ｔ）的实测与转换计算结果，计算结果有较小的误差具有重要的实用价值。

流变荷载试验曲线的模型识别及其应用

基于粘弹性理论,建立了流变荷载试验的Maxwell、广义Kelvin和Burgers3种流变模型的位移反演模式,并给出了根据现场试验流变曲线进行流变模型识别的简便方法。分析了岩体流变荷载试验曲线,给出了能反映试验区域内岩体变形规律的最佳流变模型,反演获得了试验区域内岩体的瞬时弹性模量、长期弹性模量、粘弹性模量和粘弹性系数。结果表明,描述试验点岩体在不同荷载级别情况下的最佳流变模型均为广义Kelvin模型,但其弹性模量有所差异,其量值范围为4194～5235MPa,平均弹性模量为4900.316MPa;平均长期弹性模量为3081.65MPa。计算表明所建立的反演公式是正确的,模型及参数识别过程简便、实用。

含有加州杏仁粉和烘焙酶制剂的面团体系的流变学特性研究

本文主要应用动态流变仪测定了美国加州杏仁粉(全脂和脱脂)百分含量分别为0%、12.5%、25%、37.5%和50%的面团的粘弹性模量(G″和G′)在频率和温度变化过程中所呈现出的变化趋势;以及在频率和温度相同的情况下,杏仁粉含量的变化对面团的G″和G′大小的影响;并进一步探索了淀粉酶处理对面团流变学特性的影响。结果表明:(1)在频率扫描过程中杏仁粉对面团的G″和G′都有明显的影响,含有全脂杏仁粉的面团的G″大于含有相同比例脱脂杏仁粉面团的G″,而含有全脂杏仁粉的面团的弹性模量G′却比含有相同比例脱脂杏仁粉的小,从而推断杏仁粉中的油脂对面团的流变学特性具有显著的影响;(2)在相同的频率时小麦粉面团的G″和G′比分别含有12.5%和25%的杏仁粉(全脂和脱脂)的面团的大,而分别含有37.5%和50%的杏仁粉的面团的G″和G′更大,这可能是由于杏仁蛋白质与小麦蛋白质发生了某种相互作用所致;(3)在升温过程中,添加全脂和脱脂杏仁粉都会使面团的G″和G′减小;在降温过程中,加入杏仁粉(全脂和脱脂)使面团的G′减小,但含有脱脂杏仁粉面团的G′大于含有全脂杏仁粉面团的G′,而加入杏仁粉对面团的G″在降温过程中的变化影响不显著;(4)在频率变化、升温和降温过程中,加入淀粉酶都会使面团的G″和G′减小。

一种适用于钢模的MR型水性脱模剂的研制与应用

采用α-Al_(2)O_(3)为研磨组分、乳化固体石蜡为修补组分、乳化液体石蜡为润滑组分,按m(研磨组分)∶m(修补组分)∶m(润滑组分)=1∶3∶5复配,并添加2%的防锈组分,制备了一种适用于钢模的MR型水性脱模剂。该脱模剂可以有效降低旧模板表面的粗糙度,达到新模的使用要求;可有效隔离混凝土与模板,改善了乳化油类水性脱模剂易粘模的缺点;可消除色斑污染,有效促进混凝土中气泡、水泡的排出,提高混凝土表面的平整光滑度,从而提高混凝土的表观质量。

A theoretical analysis of vertical dynamic response of large-diameter pipe piles in layered soil

Considering the viscous damping of the soil and soil-pile vertical coupled vibration,a computational model of large-diameter pipe pile in layered soil was established.The analytical solution in frequency domain was derived by Laplace transformation method.The responses in time domain were obtained by inverse Fourier transformation.The results of the analytical solution proposed agree well with the solutions in homogenous soil.The effects of the shear modulus and damping coefficients of the soil at both outer and inner sides of the pipe pile were researched.The results indicate that the shear modulus of the outer soil has more influence on velocity admittance than the inner soil.The smaller the shear modulus,the larger the amplitude of velocity admittance.The velocity admittance weakened by the damping of the outer soil is more obvious than that weakened by the damping of the inner soil.The displacements of the piles with the same damping coefficients of the outer soil have less difference.Moreover,the effects of the distribution of soil layers are analyzed.The results indicate that the effect of the upper soil layer on dynamic response of the pipe pile is more obvious than that of the bottom soil layer.A larger damping coefficient of the upper layer results in a smaller velocity admittance.The dynamic response of the pipe pile in layered soil is close to that of the pipe pile in homogenous soil when the properties of the upper soil layer are the same.

Singularities and Entropy in Bulk Viscosity Dark Energy Model

In this paper bulk viscosity is introduced to describe the effects of cosmic non-perfect fluid on the cosmos evolution and to build the unified dark energy （DE） with （dark） matter models. Also we derive a general relation between the bulk viscosity form and Hubble parameter that can provide a procedure for the viscosity DE model building. Especially, a redshift dependent viscosity parameter ζ ∝ λ0 ＋λ1（1 ＋z）n proposed in the previous work [X.H. Meng and X. Dou, Commun. Theor. Phys. B2 （2009） 377] is investigated extensively in this present work. Further more we use the recently released supernova dataset （the Constitution dataset） to constrain the model parameters. In order to differentiate the proposed concrete dark energy models from the well known ACDM model, statefinder diagnostic method is applied to this bulk viscosity model, as a complementary to the Om parameter diagnostic and the deceleration parameter analysis performed by us before. The DE model evolution behavior and tendency are shown in the plane of the statefinder diagnostic parameter pair {τ, s} as axes where the fixed point represents the A CDM model The possible singularity property in this bulk viscosity cosmology is also discussed to which we can conclude that in the different parameter regions chosen properly, this concrete viscosity DE model can have various late evolution behaviors and the late time singularity could be avoided. We also calculate the cosmic entropy in the bulk viscosity dark energy frame, and find that the total entropy in the viscosity DE model increases monotonously with respect to the scale factor evolution, thus this monotonous increasing property can indicate an arrow of time in the universe evolution, though the quantum version of the arrow of time is still very puzzling.

Study of Water Movement in Unsaturated Copper Ore

Leaching is widely applied in the exploitation of depleted ores. In order to discover the law of leachant movement in the leaching process and calculating volumes and time intervals of spraying leachant,experiments and numerical simulation with the TOUGH2/EOS3 module were carried out in order to find out the principle of water movement in unsaturated copper ore. The results show that water volume increases at the same location over time,that copper ore tends to become saturated and that liquid velocity decreases at the same time as the distance from top in-creases. On the other hand,a comparison and analysis of our experimental and simulated results indicate that the EOS3 module could accurately simulate the water movement in an unsaturated state.

Fitting methods for relaxation modulus of viscoelastic materials

Based on viscoelastic theory, two new computational methods of solving linear equations and minimum value of the l-norm were put forward for transforming Kohlransch-William-Watts （KWW） function of viscoelastic materials to the generalized Maxwell model. The computational methods for the Maxwell model fitting were achieved in MATLAB software. It is found that fitting precision of the two methods is very high. The method of solving linear equations needs more fitting points and more numbers of Maxwell units. It makes the program of finite element analysis complex. While the method of solving minimum value of 1-norm can obtain very high precision only using less fitting points. These methods can fit not only experimental curve of KWW function, but also the experimental data directly.

Estimation of the van Genuchten Soil Water Retention Properties from Soil Textural Data

The van Genuchten (vG) function is often used to describe the soil water retention curve (SWRC) of unsaturated soils and fractured rock. The objective of this study was to develop a method to determine the vG model parameter m from the fractal dimension. We compared two approaches previously proposed by van Genuchten and Lenhard et al. for estimating m from the pore size distribution index of the Brooks and Corey (BC) model. In both approaches we used a relationship between the pore size distribution index of the BC model and the fractal dimension of the SWRC. A dataset containing 75 samples from the UNSODA unsaturated soil hydraulic database was used to evaluate the two approaches. The statistical parameters showed that the approach by Lenhard et al. provided better estimates of the parameter m. Another dataset containing 72 samples from the literature was used to validate Lenhard's approach in which the SWRC fractal dimension was estimated from the clay content. The estimated SWRC of the second dataset was compared with those obtained with the Rosetta model using sand, silt, and clay contents. Root mean square error values of the proposed fractal approach and Rosetta were 0.081 and 0.136, respectively, indicating that the proposed fractal approach performed better than the Rosetta model.

Experimental Study on the Viscoelastic Behaviors of Debris Flow Slurry

The rheological properties of most liquid in nature are between liquids and solids, including both elastic changes and viscosity changes, that is socalled ＂viscoelastic＂. Dynamic oscillatory test was used to quantitatively study the distinct viscoelastic behaviors of debris flow slurry in the shear stress conditions for the first time in this study. The debris flow slurry samples were from Jiangjiagou Ravine, Yunnan Province, China. The experimental results were found that at the low and middle stages of shearing, when the angular velocity 09〈72.46 s-1, the loss modulus （G was greater than the storage modulus （G3, i.e. G＂〉G＇. At the late stage of shearing, when the angular velocity co-72.46 s-x, the storage modulus was greater than or equal to the loss G = G, tan -〈 1 （where phase-shift modulus, i.e. ＇ 〉 ＂ angle 5=G＂,/G3, and the debris flow slurry was in a gel state. Therefore, the progress of this experimental study further reveals the mechanism of hyperconcentrated debris flows with a high velocity on low-gradient ravines.

Viscoelastic deformation behavior of cement and emulsified asphalt mortar in China railway track system I prefabricated slab track

Under repeated train-induced loads, cement and emulsified asphalt mortar(CA mortar) as a viscoelastic material has a time-dependent deformation, part of which is irreversible. This could lead to debonding between the mortar layer and the track slab. Based on the theory of viscoelasticity and the analytical method of the time hardening law(THL), the viscoelastic deformation behavior of CA mortar was studied. Using ABAQUS, we established a solid model of China railway track system(CRTS) Ⅰ prefabricated slab track, with CA mortar at different initial Young’s moduli under cyclic loading corresponding to the influence of actual train loads. The results reveal that the fitted parameters of the THL for CA mortar are suitable for describing its viscoelastic deformation. As the initial Young’s modulus increases, the strain difference before and after cyclic loading gradually decreases, and the displacement difference increases from 0.2 mm to 0.6 mm. The deformation mainly occurs at the end of a mortar layer with longitudinal distribution of about 2.5 times the fasteners’ spacing. It follows that the viscoelastic performance of CA mortar is one of the most important reasons that cause debonding underneath the track slab. Therefore, we suggest that the adverse effects of viscoelastic behavior of CA mortar should be considered when researching such deformation and damage.

Study on the mechanical behavior of adhesive interface by digital image correlation

The shear modulus of the adhesive layer and the failure mode of adhesive structure on single lap joint specimens under tensile tests are investigated in this paper.The aluminum-aluminum adherends are bonded by two different adhesives:polydimethylsiloxane (PDMS) and epoxy.The full deformation fields are measured using the digital image correlation (DIC) method with the images on the middle part of the adhesive layer recorded by a high resolution microscope.Then,the shear modulus values of the two adhesives are calculated with a simple pure shear strain model.A numerical model is proposed to simulate the single lap joint structure under tensile load in comparison with the experimental results.The results show that this method can successfully estimate the shear modulus of the adhesive layer.The failure behavior of epoxy adhesive/adherend interface is also analyzed and discussed.

Mapping Soil Texture of a Plain Area Using Fuzzy-c-Means Clustering Method Based on Land Surface Diurnal Temperature Difference

The use of landscape covariates to variability of soil properties in similar estimate soil properties is not suitable topographic and vegetation conditions. for the areas of low relief due to the high A new method was implemented to map regional soil texture （in terms of sand, silt and clay contents） by hypothesizing that the change in the land surface diurnal temperature difference （DTD） is related to soil texture in case of a relatively homogeneous rainfall input. To examine this hypothesis, the DTDs from moderate resolution imagine spectroradiometer （MODIS） during a selected time period, i.e., after a heavy rainfall between autumn harvest and autumn sowing, were classified using fuzzy-c-means （FCM） clustering. Six classes were generated, and for each class, the sand （〉 0.05 mm）, silt （0.002-0.05 mm） and clay （〈 0.002 mm） contents at the location of maximum membership value were considered as the typical values of that class. A weighted average model was then used to digitally map soil texture. The results showed that the predicted map quite accurately reflected the regional soil variation. A validation dataset produced estimates of error for the predicted maps of sand, silt and clay contents at root mean of squared error values of 8.4%, 7.8% and 2.3%, respectively, which is satisfactory in a practical context. This study thus provided a methodology that can help improve the accuracy and efficiency of soil texture mapping in plain areas using easily available data sources.

Application of nanoindentation to investigate chemomechanical properties change of cement paste in the carbonation reaction

Nanoindentation technique was adopted to investigate the chemomechanical properties change of hardened cement paste before and after carbonation.It was found that the mean elastic modulus and mean hardness obviously increase after the carbonation reaction.Specifically,the probability of the elastic modulus showed a sharp reduction for the elastic modulus at the range of 7-34 and 83-160 GPa,in comparison of a large increase for the elastic modulus between 34-83 GPa.For the same reason,the probability of the hardness showed a large decrease when the hardness fell within 0.15-1.75 and 4.15-8.20 GPa and a dramatic increase for the hardness at the range of 1.75-4.15 GPa.In addition,low density C-S-H was affected by the carbonation degradation more seriously than high density C-S-H.The carbonation reaction led to distinct decrease of the number and size of unhydrated cement paste particles.