喀斯特槽谷区岩石与坡面夹角对坡面集中流水力学特性的影响

喀斯特槽谷区地表出露的岩石与坡面形成不同夹角,塑造了复杂的微地貌,显著改变坡面集中水流路径,使得水流特性发生重大变化。目前,不同岩石与坡面夹角下集中流水力学特性的变化特征还不清楚。通过室内放水冲刷模拟试验,研究了3个坡度(10°、15°和20°)、3个冲刷流量(5、7.5、10 L·min-1)和6个岩石与坡面夹角(30°、60°、90°、120°、150°和180°(0°))组合条件下喀斯特槽谷区地表集中流的水力学特性。结果表明:集中水流雷诺数(Re)随冲刷历时变化趋势较复杂,试验条件下,Re随流量的增大而增大,随坡度变化规律不明显,变化范围为517～3343。Darcy-Weisbach阻力系数(f)随冲刷历时表现出增大的变化趋势,其随坡度增大而增大,随流量增大而减小,变化范围为0.62～5.70。Re和岩石与坡面夹角关系均不显著,f和岩石与坡面夹角间的关系在各流量和坡度组合下表现不同。f与Re之间的耦合关系受岩石与坡面夹角的显著影响,当岩石与坡面夹角小于90°时,f-Re关系用对数方程描述比较好;夹角大于等于90°时,则用幂函数方程描述更好。试验条件下,当Re1 791时,f与Re关系不显著;当Re1 791时,f与Re则呈显著正相关。本研究可为喀斯特槽谷区土壤侵蚀预报模型的建立提供依据。     

Entropion correction in dogs and cats using a combination Hotz-Celsus and lateral eyelid wedge resection: results in 311 eyes

A novel surgical combination technique for the correction of lateral lower lid entropion in dogs and cats is described, involving a combination of Hotz-Celsus and lateral eyelid wedge resection procedures. The technique was used to treat 311 eyes with lower lid entropion: 269 canine (109 bilateral, 51 unilateral) and 42 feline (16 bilateral, 10 unilateral). The most common canine breeds were the Shar Pei, Rottweiler, Bull Mastiff and Labrador Retriever. Domestic cats made up the majority of feline cases. The overall success rate for a single surgical procedure to correct lower lid entropion with this technique was 94.2% per eye.     

稻谷腹部、背部微观结构差异性分析

【目的】从微观角度对糙米腹部、背部的结构差异性进行研究,从宏观角度对糙米的三点弯曲破碎力学性能进行研究,以建立微观结构与宏观力学性能之间的相关关系,为稻谷籽粒裂纹起始于腹部建立理论依据。【方法】对两个品种糙米横截面的腹部、背部在淀粉粒和细胞层次以及糊粉层进行扫描电镜观察,采用三点弯曲法测试糙米的破碎力学性能。【结果】糙米腹部、背部微观结构在淀粉粒、细胞层次以及糊粉层均存在差异,籽粒腹部、背部微观结构的差异对其腹部、背部的结构强度产生影响,使籽粒腹部的结构强度小于背部,与力学测试性能一致,并且腹部、背部微观断裂形式亦存在差异。【结论】稻谷籽粒在解吸和吸湿条件下裂纹起始于腹部与其腹部结构强度小于背部有关。     

A Fracture Mechanics Solution for Control Fissures in Perilous Rock under Seepage Stress

Crack propagation of control fissures in perilous rock under loads is a key process in the failure of perilous rock. Based on the loading mechanism, the control fissures are classified into compression shear and tension shear types. By introducing a model of seepage stress, the calculating principle of the stress intensity factor and the propagation orientation of control fissure under seepage stress are put forward using fracture mechanics methods. Using Shoulishan perilous rock in the Wanzhou district of Chongqing, P. R. China, as an example, the calculated results show that there is an obvious increase of the stress intensity factor. The influence of hydrostatic pressure and hydrodynamic pressure also are analyzed.     

喀斯特裸坡地地下孔(裂)隙流养分流失特征研究

通过人工模拟试验,研究喀斯特坡耕地地下孔(裂)隙流养分流失特征,结果表明:(1)地下产流、产沙量与雨强、地下孔(裂)隙度呈正相关关系,与坡度呈负相关关系。(2)雨强对地下径流流失浓度影响不显著,不同坡度全钾流失浓度随坡度呈波浪型变化,全磷流失浓度在缓坡(5~10°)地上径流流失浓度最大,是陡坡(15°以上)地上磷素淋失浓度的2~3倍,氮素流失浓度呈现出随着坡度增大而逐渐减小的变化趋势,地下径流全钾流失浓度与地下孔(裂)隙之间没有明显的变化趋势。(3)全钾、全磷和全氮流失量与雨强变化均呈指数函数关系,R~2分别为0.718 7,0.817 1,0.849 2;不同坡度条件下,全钾、全磷和全氮流失量随坡度的变化趋势一致,拟合曲线均为线性关系;全钾和全磷与地下孔(裂)隙度均可用指数函数拟合,全氮流失量与地下孔(裂)隙度可用幂函数拟合,地下径流中养分流失以氮素为主。     

钢筋混凝土渡槽性能及施工研究

为提高钢筋混凝土渡槽的性能,从耐久性能、受力性能、地震时位移控制及裂缝4方面,分析影响渡槽性能的内外因素,并从槽身、钢筋、混凝土施工及减少裂缝方面,探讨提高钢筋混凝土渡槽性能的工艺措施。     

磁环裂纹检测装置的研发与探索

在众多的磁性材料产品中,有一种用来制做电磁线圈的磁性材料产品———磁环,它是由磁性材料经磨具压制而成,经过磁化处理后会产生永久的磁性力;在磁环产品的质量中有一种缺欠是裂纹,用带有裂纹的磁环所生产的线圈在使用过程中会出现磁环爆裂现象,给使用者带来安全问题。为此,磁环裂纹的检测一直是磁环生产厂家不可缺少的检验环节。     

Magnetic resonance imaging features of canine incomplete humeral condyle ossification

Incomplete ossification of the humeral condyle (IOHC) is characterized by an intracondylar fissure located where the intercondylar physis is present in growing dogs. Its radiologic and computed tomographic features have been described but the magnetic resonance (MR) features have not been characterized. Our purpose was to further describe the range of MRappearances of IOHC, to assess the diagnostic capability of MRrelative to radiology, and to determine whether MRis able to identify the disease before a fissure forms. Thirty-eight elbow MRscans and radiographs, when available, were reviewed and divided into three groups. In Group 1 (affected elbows, n = 22), there was an intracondylar defect on MRwith variable appearance; the defect was not visible radiographically in 32% of the elbows. The main difference between Group 2 (nonaffected elbows, n = 6) and Group 3 (contralaterals to IOHC or to condylar fracture, without fissure, n = 10) was the appearance of the humeral condyle in short tau inversion recovery (STIR) sequences: all elbows in Group 2 had a homogeneous humeral condyle, whereas all but one in Group 3 were heterogeneous. One dog in Group 3 developed a complete condylar fissure 7 months after the first examination, when no evidence of an intracondylar defect had been detected. The MRappearance of IOHC is variable and a heterogeneous humeral condyle in STIR images without a clear defect may warn of the possibility for the subsequent development of a condylar fissure.     

不同缓苏条件对稻谷爆腰率影响的研究

研究了干燥时间、缓苏温度及缓苏时间对稻谷爆腰率的影响。结果表明,干燥时间越长,干燥后72h爆腰率越高。缓苏可有效地抑制稻谷爆腰率,干燥50min后,40℃、60℃、80℃三种缓苏温度都可有效抑制爆腰率,使爆腰率降低88．6％。干燥90min后,稻谷水分含量为14．5％,40℃缓苏后爆腰率仍迭到了76％,80℃缓苏后爆腰率仅为8％,可见高温缓苏抑制效果更佳。缓苏温度越高,缓苏效果越好,提高缓苏温度可缩短缓苏时间。稻谷干燥时间延长,应相应地提高缓苏温度,增加缓苏时间。     

预防楼板缝开裂的几项技术措施

本文对如何控制楼板裂缝进行了论述,并提出了几项预防楼板缝开裂的技术措施。