高速剪切轴向间隙的研究     

李耀辉  许春龙 《苏州市职业大学学报》2003,14(1):47-49

本针对剪切下料问题中存在的不足，从裂纹扩展的角度出发，结合断裂力学及塑性力学关于裂纹技术的相关理论，对剪切过程中影响断面质量的一个重要参数一轴向间隙进行分析，得出了高速剪切下合理轴向间隙的表这式。  相似文献   

后牙折裂原因与分类初探     

张李明  卢东民 《湖州师范学院学报》2004,26(2):95-97

收集典型病例，观察年龄、牙位、牙髓状况、充填洞型、咬合等与牙折裂的关系，按斜折、纵折、横折、粉碎折四型对牙折进行分类，研究发现：后牙折裂年龄集中在30～60岁，上下颌第一磨牙折裂率最高．折裂与牙髓状况、充填、咬合有关，各型牙折以Ⅰ类B型和Ⅱ类B型牙折率较高．死髓牙、严重磨耗牙、Ⅱ类洞充填的牙要特别注意防止其发生牙折，不同类型的牙折治疗原则应有针对性。  相似文献   

First-rib stress fracture in two adolescent swimmers: a case report     

Sara Low  Michael Kern 《Journal of sports sciences》2016,34(13):1266-1270

First-rib stress fractures have been described in adolescent athletes in various sports, with only one prior case report of first-rib stress fractures in an adolescent female swimmer. There is a need for research on the cause, management, and prevention of these injuries as they lead to significant morbidity and critical time away from sport for these aspiring athletes. We aimed to describe first-rib stress fractures as a potential cause for non-specific atraumatic chronic shoulder pain in adolescent swimmers and to discuss the different presentations, unique risk factors, treatment, and potential injury prevention strategies of such fractures. We discussed two such cases which were successfully treated with activity modification with restriction of all overhead activity, gradually progressive physical therapy and a return to swimming protocol. First-rib stress fractures can vary in presentation and should be in the differential diagnosis in adolescent swimmers with chronic shoulder pain. These injuries can be successfully managed with rest from overhead activities and physical therapy. Gradual return to competitive swimming can be achieved even with non-union of a first-rib stress fracture. Emphasis on balanced strength training in different muscle groups and proper swimming technique is essential to prevent these injuries.  相似文献   

弹塑性断裂的内参量热力学分析——Ⅰ.线弹性裂纹体的裂纹扩展     

朱锡雄 《宁波大学学报(教育科学版)》1989,(1)

本文在内参量热力学的理论框架内详细讨论了线弹性裂纹体的裂纹扩展问题。对线弹性断裂力学中所涉及到的各种能量关系作了统一的整理,其中包括Irwin的弹性能释放率——裂纹扩展力,Griffith的脆性断裂准则,以及Irwin-Kies的柔度公式和Paris的位移公式。本文以中心裂纹体为例,详细计算了裂纹扩展的稳定性,并区分恒载荷和恒位移两种情况,对材料断裂韧性测试中所遇到的失稳扩展,稳定扩展以及进发现象提供了理论说明。  相似文献   

Mental toughness and transitions to high school and to undergraduate study     

Helen St Clair-Thompson  Rebecca Giles  Sarah P. McGeown  David Putwain  Peter Clough  John Perry 《教育心理学》2017,37(7):792-809

Mental toughness can be conceptualised as a set of attributes that allow people to deal effectively with challenges, stressors and pressure. Recent work has suggested that it may be a valuable construct to consider within educational settings. The current studies explored the associations between mental toughness and educational transitions. Study 1 examined the relationships between mental toughness and concerns about moving to a new school in 105 children aged 12–13 years of age. The results revealed significant relationships between several aspects of mental toughness, but particularly confidence in abilities, and children’s concerns. Study 2 examined the relationships between mental toughness and adjustment to university in 200 undergraduate students at various stages of their course. The results revealed a role for several aspects of mental toughness; commitment, control of life, control of emotion, confidence in abilities and interpersonal confidence. The results are discussed in terms of implications for educational practice. It is suggested that measures of mental toughness could be used to identify individuals who may benefit from additional support during transition to a new school or to university, and that future research should explore the potential benefits of mental toughness training.  相似文献   

Learning Acetabular Fracture Classification using a Three-Dimensional Interactive Software: A Randomized Controlled Trial     

Huixiang Wang  Fei Lyu  Kapil Sugand  Sheungting Wong  Yanping Lin  Qiugen Wang 《Anatomical sciences education》2019,12(6):655-663

Acetabular fractures are a real challenge for junior doctors as well as experienced orthopedic surgeons. Correct fracture classification is crucial for appreciating the fracture type, surgical planning, and predicting prognosis. Although three-dimensional (3D) tutorial is believed to improve the understanding of the complex anatomy structure, there have been few applications and randomized controlled trials to confirm it in orthopedics. This study aims to develop a 3D interactive software system for teaching acetabular fracture classification and evaluate its efficacy. Participants were randomly but evenly allocated into either the experimental group (who learned the acetabular fracture classification using a 3D software) or the control group (who used a traditional two-dimensional [2D] tutorial). Both groups were then tasked to classify 10 acetabular fractures and complete a five-point Likert scale on their satisfaction of each learning modality. To calculate significance (P < 0.05), independent t-test was used for normally distributed data whereas Mann-Whitney U test for non-normally distributed data. The experimental group significantly outperformed the control group (t (28) = 2.526, P = 0.017) with identifying correct acetabular fracture classification. Moreover, Likert scale score in the experimental group was also significantly higher than in the control group (Z = 2.477, P = 0.013). This 3D classification software has objectively and subjectively showed an advantage over the traditional 2D tutorial, resulting in an improved classification accuracy and higher Likert scale score. The 3D software has the potential to improve both clinical knowledge as well as identifying correct patient management in orthopedics.  相似文献   

塔里木盆地塔中地区奥陶系裂缝储层发育特征及预测     

孙培元 《茂名学院学报》2011,21(4):63-66

裂缝是塔里木盆地奥陶系碳酸盐岩沉积的重要渗流通道和储集空间,因此裂缝研究对油气藏开发具有重要意义。利用岩心、测井等资料对裂缝识别,选择裂缝相关参数（如线密度及充填性等）予以统计,研究塔中地区裂缝发育垂向及平面分布规律。结合裂缝发育规律,研究裂缝发育受岩性、层厚、断层及岩溶的影响关系。主要基于地质统计方法,预测塔中地区奥陶系裂缝发育的有利区带集中在主要断裂带附近及断裂带交汇处。预测的有利区带与其他方法如三维有限元数值模拟方法预测的区带一致。  相似文献   

法律断裂与湖北地方政府、汉冶萍公司间的官款偿还案     

左世元 《黄石理工学院学报(人文社科版)》2011,(2):1-5

官款偿还案是湖北地方政府与汉冶萍公司利益之争的重要表现。在官款偿还案的较量过程中,由于近代中国急速的政权更迭,矿业条例、公司法等相关法律的制定无法适应形势的发展,因而出现法律滞后甚至断裂的严重现象。正因如此,争论双方在该案中各自所持的依据不同,得出的结论也迥然相异,以致引发严重的分歧和冲突。从这个意义上说,法律断裂是导致官款偿还案无法解决的最主要的原因。  相似文献   

国产气垫夹板治疗踝关节损伤的临床观察     

李国平  李旭坤  贾林 《体育科学》1998,18(6):64-68

运用国产气垫夹板对37例急性踝关节损伤进行了治疗效果的观察和分析。结果证实:国产气垫夹板对踝关节扭伤后所致的韧带损伤和稳定性骨折均有明显的治疗作用;踝关节气垫夹板固定时间相对较短,韧带拉伤平均18天,稳定性骨折平均31天;国产气垫夹板限制踝关节内翻和外翻,但不影响踝关节的背伸和跖屈运动,患者可进行早期关节活动。  相似文献   

新场须四下亚段沉积相精细描述     

李佳阳  黎华继  李建良  周维娜  李忠平 《大众科技》2015,(5)

根据高分辨层序地层学和沉积特征,新场须四下亚段可划分为TX48、TX49、TX410三套砂组。主要为辫状河三角洲相的粗碎屑沉积,其中砾岩、砂砾岩属超致密储层,砂岩主要为致密储层,天然气产出须裂缝沟通,砂岩为储集空间的主要提供者但不发育裂缝,而砾岩发育。因此,用分流河道和水下分流河道微相难以描述有利储集体,需细化微相。根据沉积构造、岩性组合、电性等识别标志,将其分为砾质、砂砾质以及砂质(水下)分流河道微相、河口坝、远砂坝沉积微相。通过地球物理技术的精细刻画,揭示研究区北部、中部储层沉积微相以三角洲平原砾质、砂砾质以及砂质分流河道为主,而往南以三角洲前缘亚相的河口坝、远砂坝沉积微相为主,细化了储层的空间展布规律,可为后续的储层储集性能的研究及储层评价提供有力支撑。  相似文献