唐山市迁安三里河流域沙丘区风蚀因子研究

就河北省迁安市三里河流域大魏庄与白沙坡之间沙化土地,确定与研究该区风蚀气候因子和侵蚀性风能,提出相应治理对策,它将有利于该区的土壤改良、涵养水源、防止沙化扩张,以及对减轻春季沙尘暴的危害具有实际指导意义。     

灌区灌溉渠系分形特征研究

灌溉渠系是一种分形体，渠系的某部分渠段在某种程度上包含了整个渠系的信息。该文将分形理论引入到灌溉渠系的研究中，对其分形特征和分维数进行了分析，并运用盒计数法计算了漳河灌区灌溉渠系的分形维数。在此基础上，论证了渠系分形维数与其灌水模数的相关性，为灌区渠系布置优化设计提供了一定的理论依据。     

含水率对小麦粮堆弹塑性力学特性的影响

不同地区粮仓中粮堆的含水率会有较大的差异,为了明确含水率对粮仓设计参数的影响,通过三轴试验研究了含水率对小麦粮堆非线性强度、临界状态和模量等的影响规律。结果表明:不同含水率下小麦粮堆的峰值强度和残余强度符合非线性强度指标的Mohr-Coulomb强度准则;参考压力(100kPa)下峰值内摩擦角和残余内摩擦角随着含水率的增大呈线性增大,含水率每增加1%,峰值内摩擦角和残余内摩擦角分别增大0.22°和0.30°。小麦粮堆的临界状态特性符合剑桥弹塑性理论,偏应力随着平均法向应力的增大呈线性增大;峰值应力比和临界状态应力比随着含水率的增大呈线性增大;含水率每增加1%时,峰值应力比和临界状态应力比分别增大0.012和0.014。不同含水率下初始模量、割线模量与围压间可采用幂函数模型表示;参考压力下初始模量和割线模量均随着含水率的增大呈线性降低;含水率每增加1%,初始模量和割线模量分别降低0.98和0.25 MPa。     

葡萄的力学特性及有限元模拟

在建立单个葡萄力学模型的基础上，对其进行了有限元分析。通过模型计算与试验相结合的方法，确定出葡萄果肉的弹性模量。得出在压缩载荷作用下，葡萄内部的应力分布规律，为深入研究水果、蔬菜的微观组织损伤打下基础。经模型计算与试验结果相比较，得出表皮破裂是葡萄宏观破坏的主要形式，最大拉应力是造成葡萄机械损伤的主要原因。     

Closed-form Analytical Solution for Beam on Elastic Foundation with Different Tension and Compression Modulus

On the basis of the theory of different modulus, the closed-form analytical solution for beams on elastic foundations with different modulus has been derived. A comparison is made between the results of the analytical solution and those calculated from the classic mechanic theories, in which the tension modulus are equal to the compression modulus. It is shown from the numerical results that the ratio of compressive modulus to tensile modulus will greatly affect the elastic characteristic values,internal forces and flexibilities. The present theory satisfies the mechanical behavior of materials. The amount of materials can be economized through rational design by using the elastic theory of different modulus.     

Relationship Between Dynamic and Static Value of Elastic Modulus in Rock

Taking the deposited-layer rock and compacted-layer rock as study target,by elastic wave experiment and uniaxial compression experiment,the physics mechanics parameters and acoustics parameters of these rock are worked out; Based on it, by the correlativity is established between dynamic and static value of elastic modulus in rock of different lithology taking nonlinear fitting,it offers reference for the study of the drill and measuring well in the exploitation of oil. Influenced by the integrality and weathering breakage degree of rock,the biggish different is existed between dynamic elastic modulus gained by dynamical method and static elastic modulus obtained by static method,and the relationship between dynamic and static value of elastic modulus is approximatively expressed as a relationship of quadratic polynomial function.     

用拉压不同模量弹性理论分析座仓盖

飞机座仓盖是一个复杂的薄壳结构，其组成材料具有十分明显的拉压不同弹性模量性。笔者构造了拉压不同模量的薄壳有限元算法，对飞机座仓盖进行了整体力学分析，得到了一些全新的结论和力学规律。     

龙竹和绿竹竹材壁厚度方向的梯度力学性能

为探究竹材壁厚度方向的梯度特性，以产于云南的龙竹Dendrocalamus giganteus和产于浙江的绿竹Dendrocalamopsis oldhami为研究对象，将它们沿竹壁厚度方向分为若干个轴单板层，通过万能材料力学试验机测得竹材的表观弹性模量及2个轴单板层的弹性模量，并用拉格朗日插值法推算出其余任意层的弹性模量。通过复合材料力学方法构建了竹材表观弹性模量和各个轴单板层弹性模量之间内在关系的力学模型；由构建的力学模型推算得到的竹材表观弹性模量与试验机上测得的弹性模量基本吻合。图3表2参10     

Age-related change in shear elastic modulus of the thoracolumbar multifidus muscle in healthy Beagle dogs using ultrasound shear wave elastography

BackgroundMultifidus muscle stiffness decreases in patients with lumbar intervertebral disk herniation; however, age-related changes in humans have not been reported.ObjectivesThe reliability of ultrasound shear wave elastography in dogs, and changes in the shear elastic modulus of the thoracolumbar multifidus muscle with aging in dogs, were investigated.MethodsTwelve beagle dogs were divided into 2 groups based on the age of onset of intervertebral disk herniation: young (aged not exceeding 2 years; 1.3 ± 0.6 years old, n = 5) and adult (4.9 ± 1.2 years old, n = 7). The shear elastic modulus of the multifidus muscle, from the thirteenth thoracic spine to the fourth lumbar spine, was measured using ultrasound shear wave elastography. The length, cross-sectional area and muscle to fat ratio of the multifidus muscle, and the grade of intervertebral disk degeneration, were assessed using radiographic and magnetic resonance imaging examinations.ResultsThe length and cross-sectional area of the multifidus muscle increased caudally. In the young group, the shear elastic modulus of the multifidus muscle of the thirteenth thoracic spine was less than that of the third lumbar spine. In the adult group, the shear elastic modulus of the multifidus muscle of first and third lumbar spine was lower than that of the same site in the young group.ConclusionsUltrasound can be used to measure shear wave elastography of the thoracolumbar multifidus in dogs. If the multifidus muscle stiffness decreases, we should consider age-related change.     

软土复合地基综合变形模量理论计算与验证

地基变形模量可以采用现场试验、查表、压缩模量转换等多种方法确定，对软土复合弹性地基的地基变形模量的确定方法进行探讨，以现场试验数据验证了考虑软土处理方法、材料特性而建立的权重法计算模式是合适的。从而为软土地基处理后的复合地基上的结构内力计算提供参考依据。