Contact analysis of MW wind turbine hub and bearing bolt connection

Using large finite element software MSC.Marc/Mentat, the contact analysis of bolted joints parts between the hub and the bearing of wind turbine is conducted for the contact stress suffering from the practical work load. The maximum stress acted on the bolt is obtained, and a detail contact analysis for this bolted joints parts is given. The accurate stress of bolts, bearing and hub is calculated. The FEA contact results are consistent with the theoretical calculation results, and the strength of materials meets the requirements, which means the structure is safe.     

花岗岩风化土物理特征曲线间的相关性研究

花岗岩风化壳水分及收缩特性的研究是花岗岩土体稳定性评价及侵蚀机理研究的基础。通过Van Genuchten(VG)模型对不同风化程度的花岗岩土壤的颗粒累积分布、土水特征曲线和收缩特征曲线进行拟合,分析曲线拟合参数间以及这些参数与基本物理性质间的线性及非线性相关关系。结果表明:VG模型可以很好地用于不同风化程度花岗岩风化土的颗粒组成、土水特征与收缩特征的拟合与预测;曲线拟合参数间具有一定的线性相关关系;曲线拟合参数与基本物理性质间具有一定的线性相关关系,其中土水特征曲线参数与土壤质地以及容重线性相关性较高,收缩特征曲线物理参数与基本物理性质间的线性相关性较收缩特征曲线其他参数高。此外,曲线拟合参数间以及这些参数与基本物理性质间具有一定的非线性相关关系,而关系多为二次、三次非线性相关。根据花岗岩风化土颗粒组成状况及其基本物理性质对其水分特征曲线及收缩特征曲线进行预测具有一定的可行性。     

Platelet-derived growth factor acts via both the Rho-kinase and p38 signaling enzymes to stimulate contraction in an in vitro model of equine wound healing

Horses are more prone to complications in the wound healing process than other species, and problems such as chronic inflammation, delayed epithelialization, poor wound contraction, and exuberant granulation tissue are commonly seen, particularly in wounds on the distal limbs. In comparison, wounds of the oral mucosa heal rapidly in a scarless fashion with a high degree of wound contraction. The effect of platelet-derived growth factor BB (PDGF), insulin-like growth factor (IGF)-1, and transforming growth factor β1 (TGFβ1) on the contraction of a fibroblast-populated collagen matrix (FPCM) as a model of equine wound contraction was investigated using equine oral fibroblasts. The fibroblasts were embedded into floating FPCM and treated with PDGF, IGF-1, and TGFβ1. The surface areas of the FPCM were determined daily for 5 d. Platelet-derived growth factor significantly stimulated the contraction of the FPCM at an optimal concentration of 10 ng/mL (P = 0.025). Insulin-like growth factor-1 and TGFβ1 did not significantly affect the contraction of the FPCM relative to the control. To elucidate the mechanisms by which PDGF stimulated contraction of FPCM, the Rho-kinase and p38 cell signaling pathways were blocked, resulting in a significant inhibition (P < 0.001) of PDGF-stimulated contraction. Platelet-derived growth factor BB is a potent stimulator of fibroblast migration, and hence the FPCM contraction generated here is probably a result of its effects on cell migration. The results of the present experiment suggest that this effect is stimulated via both the Rho-kinase and p38 signaling pathways in equine oral fibroblasts.     

膨胀土胀缩裂隙演化及其扰动规律分析

为定量研究膨胀土胀缩裂隙的演化特征及其对土体的扰动规律,从而探究其引发工程和生态环境灾害的机理。论文对合肥膨胀土进行干湿循环-CT(computed tomography)扫描试验,从获取的CT图中提取灰度值以及灰度共生矩阵特征值:角二阶矩(angular second moment,ASM)和对比度(contrast,CON),研究在干湿循环作用下裂隙图像的灰度值及其纹理的变化规律;并通过三轴剪切试验研究了在干湿循环作用下膨胀土的强度特征。结果表明:1)图像灰度值随裂隙的发育状态而变化;初始阶段灰度值沿试样轴向分布比较离散,但在后期逐渐均匀,离散系数在3次干湿循环后达到最大值,比干湿循环前增加了106%,随后逐渐减小;2)ASM随干湿循环次数的增加而减小,并且在0°和90°方向上的值比在45°和135°方向上的值大9%;CON随干湿循环次数的增加而减小,并且在0和90°方向上的值比在45°和135°方向上的值小52%,其对纹理的方向差异性更加敏感;3)胀缩裂隙对原状膨胀土的结构性会造成破坏,强度劣化显著;在5次干湿循环后,2种土强度分别降低62%和46%,并且原状膨胀土与重塑膨胀土强度的差值也由347.3 kPa降至21.3 kPa;4)由ASM和CON定义的扰动函数与由土体原生联结结构强度定义的扰动函数,扰动过程中函数变化曲线吻合度高,故基于灰度共生矩阵特征值的扰动函数能很好地描述胀缩裂隙扰动下的膨胀土强度特性。     

奶牛输卵管平滑肌前列腺素类受体的分析研究

本研究选用了前列腺素类化合物(Prostaglandin E2（PGE2）、Prostaglandin F2α（PGF2α）、Prostaglandin D2（PGD2)）和受体选择性激动剂（Butaprost、U-46619）,用多道生理信号采集系统测定其对体外分离的奶牛输卵管峡部及壶腹部平滑肌收缩的影响,以此初步揭示受体的种类。结果发现,PGE2和Butaprost均抑制了奶牛输卵管峡部、壶腹部的自发性收缩运动,呈现明显的浓度依存性舒张反应;PGF2α在高浓度(1～10 μmol/L)下,使峡部和壶腹部的自发性收缩运动有了显著增强;PGD2在低浓度时轻微抑制了壶腹部平滑肌的收缩,但在高浓度(1～10 μmol/L)时加强了峡部和壶腹部平滑肌的收缩;U-46619从低浓度便引起了输卵管峡部和壶腹部平滑肌的强烈收缩。结果表明,EP4、EP2、FP、DP和TP受体同时存在于奶牛输卵管平滑肌上,能与内源性前列腺素类结合并参与调节输卵管平滑肌的自发性收缩。     

土壤胀缩运动对草原土壤的干扰作用

以松嫩羊草草原为对象,选取草原土壤裂缝边的土壤及植被,测试其理化性质。研究土壤胀缩运动对草原土壤及植被的干扰作用。结果表明,土壤开裂,加剧了水分蒸发,对植被根系产生撕裂作用,引起种群波动,使植被总密度和总生物量降低;而裂缝对物质的贮存作用及淋溶作用又改善了土壤理化性质,提高了缝内有机质含量,降低了pH值、电导率及含盐量,增大了翌年植被的总密度和总生物理。因此,土壤胀缩运动对草原能产生短期的干扰作用。     

Mycoplasma Hyorhinis in the Etiology of Serositis among Piglets

In a study on the involvement of Mycoplasma hyorhinis in serositis of piglets, 26 routine diagnostic animals, 3-7 weeks old, with distinct serofibrinous lesions in the pericardial, pleural and peritoneal cavities were examined. M. hyorhinis was isolated in 9 cases, non-haemolytic Escherichia coli in another 9 cases and in 4 cases both species were found. Neither of the microorganisms were found in the remaining 4 cases.The presence of M. hyorhinis in the serous cavities in the absence of non-haemolytic E. coli was always accompanied by a diagnosis of other disease conditions, mainly of the respiratory tract. In the cases infected with non-haemolytic E. coli complicating problems were absent.The pathogenicity of M. hyorhinis was further studied by inoculation of 2 young pigs in which the typical serofibrinous lesions of the serous cavities were produced. It therefore appears that M. hyorhinis can be regarded as a cause of polyserositis in piglets; under field conditions, however, the synergistic presence of other debilitating syndromes appears necessary for its haematogenous spread from the respiratory tract to the serous cavities.     

旅游客车杆连接的真实形状对变形和应力计算的影响

传统的客车结构分析是将杆连接作为刚性的节点处理．本文提出一种考虑连接点真实形状的有限元分析，并计算了旅游客车底架箱形框架杆连接的具体形状对计算结果的影响．分析和实验均表明：忽略杆连接的真实形状会产生较大的误差．     

Communication between the distal interphalangeal joint and the navicular bursa in the horse at Computed Tomography Arthrography

Diffusion of drugs injected into the distal interphalangeal joint or the navicular (podotrochlear) bursa can influence diagnosis and treatment of foot pain. Previous anatomical and radiographic studies of the communication between these synovial structures have produced conflicting results and did not identify the location of any communication if present. This anatomic study aimed to assess the presence and site of communication between the distal interphalangeal joint and the navicular bursa in the horse by computed tomography arthrography. Sixty‐six pairs of cadaver forelimbs were injected with contrast medium into the distal interphalangeal joint and imaged by computed tomography arthrography. The presence of a communication, location of the communication and additional structural changes were assessed. Navicular bursa opacification occurred in 7 distal limbs (5.3%) following distal interphalangeal joint injection. One limb showed a communication through the T‐ligament and 6 limbs showed a communication through the distal sesamoidean impar ligament. In 3 cases, the communication through the distal sesamoidean impar ligament was associated with a distal border fragment. Our study showed that communication between the distal interphalangeal joint and navicular bursa is uncommon and inconsistent. Clinically, the presence of a communication could (1) influence the interpretation of diagnostic analgesia of the distal interphalangeal joint or the navicular bursa by facilitating the diffusion of local anaesthetic between these structures; (2) allow the drug and its potential adverse effects to spread from the treated synovial cavity to the non‐targeted synovial cavity; (3) be responsible for the failure of joint drainage in the case of sepsis.     

Associations between hoof shape and the position of the frontal plane ground reaction force vector in walking horses

AIMS: To determine the frontal plane position of the ground reaction force vector at its centre of pressure under the hoof of walking horses, and its projection through the distal limb joints, and to relate this to hoof geometric measurements.

METHODS: Reflective markers were glued to the forelimb hooves and skin of 26 horses, over palpable landmarks representing centres of the coffin, fetlock and carpal joints, and the dorsal toe at its most distal point. A 4-camera kinematic system recorded the position of these markers as the horse walked in hand across a force platform, to generate a frontal plane representation of the ground reaction force vector passing between the markers at the joints. The position of the vector was calculated as the relative distance between the lateral (0%) and medial (100%) markers at each joint. Digital photos were taken of the hoof in frontal and sagittal views to determine hoof geometric measurements. Associations between these and the position of the force vector at each joint were examined using Pearson correlation coefficients.

RESULTS: Mean vector position for both forelimbs at the toe, coffin, fetlock and carpal joint was 50.1 (SD 8.9), 53.0 (SD 9.2), 54.6 (SD 11.4) and 50.5 (SD17.3)%, respectively, of the distance between the lateral and medial sides of the joint in the frontal plane. Across all four joints, the vector position was slightly more medial (2–4%) for the right than left limb (p>0.05). Medial hoof wall angle was correlated (p<0.05) with force vector position at the fetlock (r=?0.402) and carpal (r=?0.317) joints; lateral hoof wall angle with vector position at the toe (r=0.288) and carpal (r=?0.34) joint, and medial hoof wall height with vector position at the fetlock (r=?0.306) and carpal (r=?0.303) joints.

CONCLUSION: The position of the two-dimensional frontal plane ground reaction force vector at the toe, and at the fetlock and carpal joints was associated with hoof shape. Mediolateral hoof balance has been shown in vitro to affect articular forces, which may be a factor in development of joint disease. The effect of hoof shape needs to be evaluated at faster gaits to determine the potential for joint injury in the presence of larger forces.