木材裂纹尖端应力、应变场的数值分析

借助Ansys有限元软件,采用二维正交各项异性有限元模型,对带有裂纹的正交各向异性白桦试件进行3点弯曲的裂纹尖端应力、应变场的研究。为了较真实的反映裂纹尖端力学情况,分别采用在裂纹尖端进行有限元网格细化法和布置奇异单元法来模拟裂纹尖端奇异场,并将计算结果用Matlab平台下编写的后处理程序进行分析和比较。结果表明:2种方法均可满足工程实际的要求,但在裂纹尖端布置奇异单元法优于有限元网格细化法。     

骨碎补与续断配伍提取物对大鼠骨折修复研究

对骨折大鼠进行血钙浓度、血磷浓度、血清碱性磷酸酶(ALP)活性检测、X线片观测及生物力学测试,观察骨碎补总黄酮与续断总皂苷配伍用药对大鼠骨折愈合的作用.结果表明:该配伍用药促进了骨折部位钙盐的重新沉积,提高了血清ALP活性,与模型组相比,1周时复方高剂量组血钙浓度及血清ALP活性升高,达极显著(p<0.01),分别为3.48 mmol/L与34.17×10-2U/mL;促进骨痂的生成,增强骨强度;复方高剂量组在3周时,骨折断端开始消失,弯曲破坏载荷达6.877 N.说明骨碎补总黄酮与续断总皂苷配伍用药能显著促进骨折的愈合.     

农药微乳剂热力学稳定性微观机制研究

 利用冷冻断裂电镜研究方法研究了表观稳定的农药微乳剂的微观结构 ,并通过光散射技术测定了O/W型微乳剂分散质点的流体力学半径 ,同时还测定了相关样品的主要表观指标。试验结果表明 ,随着微乳体系中表面活性剂 /水 (w/w)比值的减小 ,微乳剂分散质点流体力学半径变大 ,直至成为双连续结构 ,并依此提出了一种农药微乳剂热力学稳定的可能机制。这一发现使得从微观机制上解释农药微乳剂的热力学稳定性 ,指导热力学稳定的农药微乳剂的研究开发 ,并从根本上解决农药水基化制剂热贮稳定性这一关键技术问题成为可能。     

苎麻茎叶的力学特性测试研究

为了揭示苎麻[Boehmeria nivea(L.)Gaudich.]茎叶连接力及其冲击断裂能量的分布规律,以收获期二麻为试验对象,参照GB/T 1040-2006及GB/T 1843-2008试验标准,采用HD-B604-S电脑伺服式拉力试验机与TF-2056B悬臂梁冲击试验机,对分布于不同部位的连接苎麻麻叶与茎秆的叶柄分别进行了静态拉力测试试验和动态冲击断裂试验,获取茎叶连接力和茎叶冲击断裂能。结果表明,中部茎叶连接力平均值最大,顶部次之,下部最小,茎叶连接力最大平均值为14.492 N;中部茎叶冲击断裂能平均值最大,顶部次之,下部最小,茎叶冲击断裂能最大平均值为0.042 J;中部与顶部的茎叶随叶柄直径增大,其连接力和冲击能量总体趋势逐渐增大而局部波动。该试验研究可为苎麻茎秆脱叶机构及苎麻联合收割脱叶机构设计提供理论依据。     

经后路椎弓根固定治疗胸腰椎骨折并脊髓损伤24例疗效分析

目的观察经后路椎弓根固定治疗胸腰椎骨折并脊髓损伤的疗效.方法所有患者在伤后6 h～10 d行后路切开复位、短节段椎弓根钉内固定术.本组全部病例术前、术后及随诊时均摄正侧位X片、CT或MR I扫描检查.结果经X片、CT检查,病椎高度恢复90%以上,伤前的后突畸形Cobb角平均为25.5°（11°～32°）,术后纠正至平均4.4°（1°～7°）.结论后路椎管减压椎弓根系统治疗胸腰椎骨折并脊髓损伤效果良好.     

碳酸盐岩底水气藏型储气库动态特征及水淹机制

储气库注采气能力、库容及工作气量是衡量储气库能力的重要指标,储气库动态特征分析是评价储气库能力的重要手段。基于某碳酸盐岩底水含硫气藏改建储气库(A储气库)的多周期注采生产情况,通过系统分析储气库运行动态特征,评价了水平井注采气生产能力,利用两种方法对储气库库容进行复核,分析了气藏H2S质量浓度变化,评价了脱硫运行方式,结果表明:该储气库单井产能高,库容落实程度高,具备高效开发潜力,但仍需探索脱硫运行方式。研究分析了A储气库生产中出现的AH1井水淹停产问题的形成机制,提出了恢复气井生产能力的具体方案,并成功应用于现场。研究成果对中国碳酸盐岩底水气藏型储气库生产运行及能力评价具有指导作用。(图1,表5,参20)     

Catastrophic scapular fractures in Californian racehorses: pathology, morphometry and bone density

Reasons for performing study: To enhance understanding of the nature and pathogenesis of scapular fractures in racehorses. Hypothesis: Scapular fractures in racehorses have a consistent configuration related to sites of pre‐existing stress modelling and remodelling. Methods: Fractured and intact scapulae collected post mortem were examined visually and with computed tomography (CT). Scapular fracture configuration, bone modelling changes and standardised CT morphometry and density measurements were recorded. Statistical comparisons were made between fractured, nonfractured contralateral and control scapulae. Results: Thirty‐nine scapulae from 10 Thoroughbred (TB) and 10 Quarter Horse (QH) racehorses were obtained. All 14 fractured scapulae (from 12 horses) had a consistent comminuted fracture configuration. A complete fracture coursed transversely through the neck of the scapula at the level of the distal aspect of the spine (8.9 ± 0.9 cm proximal to the lateral articular margin of the glenoid cavity). The distal fragment of 13 fractured scapulae was split into 2 major fragments by a fracture in the frontal plane that entered the glenoid cavity (2.8 ± 0.4 cm caudal to the cranial articular margin). Focal areas of periosteal proliferation and/or radiolucency were present in the distal aspect of the scapular spine of all fractured and intact contralateral scapulae, but less commonly (P<0.01) in intact scapula from horses without a scapular fracture. Fractured scapulae had 7–10% lower mean density and 46–104% greater density heterogeneity in the spine adjacent to the transverse fracture compared to control scapulae (P<0.03). Conclusions and clinical relevance: Thoroughbred and QH racehorses have a characteristic scapular fracture configuration that is associated with pre‐existing pathology of the distal aspect of the spine. This location is consistent with scapular stress fractures diagnosed in lame TB racehorses. Catastrophic fracture is the acute manifestation of a more chronic process. Consequently, there are opportunities for early detection and prevention of fatalities.     

沧临输油管道漏油分析

通过管道许用应力计算和管道当量应力、组合应力和稳定性的验算,对发生在沧临输油管道裂口漏油的实例进行了理论分析,结果表明,输油管道的组合应力(σz)为243.5 MPa,大于管道的许用应力([σ])210.6 MPa,且水平直径方向的变形量已超过3%,管道发生断裂是必然的.并指出了同类管道在运行管理中应注意的问题.     

Shale gas seepage mechanism and fractured wells’ production evaluation

To know the dynamic characteristics of shale gas reservoirs’ production and to improve shale gas wells production, it is very important to research on shale gas seepage mechanism and production evaluation. The main difference between shale gas reservoir and conventional gas reservoir is that shale gas reservoir has the adsorption and desorption characteristics. Combined with shale gas seepage characteristics, using point source function, the mass conservation law and Langmuir isotherm equation to describe the shale gas adsorption and desorption phenomena, it establishes dual media shale fracturing wells’ seepage model. By the numerical inversion and computer programming, it draws production decline curve charts and analysises the Langmuir volume, Langmuir pressure, elastic storativity ratio, cross flow coefficient, borders, fracture length and other factors on the impact of shale gas wells production.     

Common complications of fracture repair

Complications are a reality of fracture repair. Many can be avoided or minimized by being aware of their pathophysiology and predisposing factors. Others are unavoidable but their resolution may be aided by early diagnosis and appropriate treatment. Major complications of fracture repair include osteomyelitis, delayed union, nonunion, malunion, premature physeal closure, and fracture associated sarcoma. Consideration of these complications should factor into presurgical patient evaluation as well as postoperative management. This discussion focuses on how to avoid, recognize, and treat these complications.