A study of water curtain parameters of underground oil storage caverns using time series monitoring and numerical simulation

Water curtain systems(WCSs) are key components for the operation of underground oil storage caverns(UOSCs) and their optimization and design are important areas of research.Based on the time series monitoring of the first large-scale underground water-sealed storage cavern project in China,and on finite element analysis,this study explores the optimum design criteria for WCSs in water-sealed oil caverns.It shows that the optimal hole spacing of the WCS for this underground storage cavern is 10 m in order to ensure seal effectiveness.When the WCS is designed with a 10-m horizontal hole spacing and a water curtain pressure(WCP) of 80 kPa,a water curtain hole(WCH) has an influence radius of approximately 25 m.The smaller the vertical distance is between a WCH and the main cavern,the greater the water inflow into the main cavern.The vertical hydraulic gradient criterion can be satisfied when this distance is 25 m.It shows that the optimal WCP is 70 kPa,which meets sealing requirements.     

基于改进BESO算法的集材绞盘机卷筒优化设计

通过修正材料插值模型和引入应力均方差作为性能收敛指标,改进了基于von Mises应力的双向渐进结构拓扑优化(Bi-directional Evolutionary Structural Optimization, BESO)方法,并结合Abaqus有限元软件及MATLAB语言编程实现了该算法;在此基础上,优化设计了集材绞盘机摩擦卷筒,得到不同材料体积分数、不同旋转周期数时,摩擦卷筒的最优拓扑结构,在减轻质量的同时,降低了应力集中水平。优化结果对实现集材绞盘机摩擦卷筒轻量化设计具有工程指导意义。     

混凝土三轴等幅拉-压疲劳性能试验研究

Fatigue tests were conducted on tapered plain concrete prism specimens under triaxial constant-amplitude tension-compression cyclic loading. The low stress of the cyclic loading was taken as 0.2fc and the upper stress ranged from 0.20ft to 0.65ft. Three constant lateral pressures were 0.1fc, 0.2fc and 0.3fc respectively. Based on the results, the three-stage evolution nile of the fatigue stiffness, maximttm(minimum) longitudinal strain and damage were analyzed, and a unified S-N curve to calculate fatigue strength factors was worked out. The results show that the fatigue strength and fatigue life under triaxial constant-amplitude tension-compression cyclic loading are smaller than those under uniaxial fatigue condition. Moreover, the secondary strain creep rate is related to the fatigue life, a formula for describing their relation was derived. The investigation of this paper can provide information for the fatigue design of concrete structures.     

“一站式”物业管理平台的设计与实践

随着城市化进程不断推进,物业管理信息化程度和技术也飞速发展,但是,物业管理平台在建设过程中也逐渐暴露了一些问题:例如以"应用"为驱动,各部门缺乏统一的标准和规范、缺乏统一的平台进行管理等。"一站式"物业管理平台能够解决这些问题。通过"一站式"物业管理平台的构建,实现新型的"统一平台、分权流转"的管理模式,形成以数字平台为中枢,各系统相互融合、协调运行的一体化物业管理格局,促进规范化、集约化、自动化的物业管理信息化建设进程。     

正交异性钢桥面铺装有限元模拟和优化分析

为了确定正交异性钢桥面铺装受力状态并为设计提供参考,运用子模型有限元法分析了桥梁整体变形及局部轮载作用下铺装内部受力状态及应变分布特点.为优化设计铺装层结构,分析了铺装层模量对其应变状态影响.分析结果表明:大跨径钢桥整桥变形对铺装层受力状态影响很小,钢桥面铺装设计的控制受力因素是轮载局部作用下铺装层的横向应变,铺装层模量对铺装层的受力状态有显著影响,通过提高铺装层刚度过渡层的结构优化设计措施可以显著改善铺装层的受力状态,降低铺装层的应变水平.分别对环氧沥青混凝土、SBS改性沥青SMA和Rosphalt改性沥青混凝土的模量及疲劳性能进行了试验评价,可以为桥面铺装结构组合设计提供参考数据.     

可回收外周血管支架设计与生物力学研究

为解决传统支架长期滞留体内诱发支架内再狭窄的问题,设计一种新型可回收外周血管支架,并对其安全性与有效性进行力学分析。首先建立支架和外周斑块血管有限元模型,对支架进行压握、自由扩张过程的有限元分析,比对分析结果与径向支撑力测试结果,发现误差小于10%,验证了支架有限元模型有效性;在此基础上,再对支架植入及回收过程进行仿真模拟,分析与血管耦合条件下支架与血管生物力学性能。压握过程中支架最大应变为5.919%,回收过程中支架所受等效应力最大值为691MPa,均小于支架材料镍钛合金最大弹性应变及屈服应力。自膨胀扩张过程中血管所受最大等效应力值为0.592 6MPa,支架回收过程中血管所受等效应力最大值为0.536 6MPa,均小于血管损伤应力。试验结果表明,新型可回收外周血管支架理论上是可回收的,并且在植入以及回收过程中,其力学性能安全可靠。     

复合悬臂曲梁力学性能的研究

用有限元方法对复合悬臂曲梁进行了数值分析,求得了复合悬臂曲梁的正应力和切应力。设计并制作了复合悬臂曲梁的实验模型并进行了应力测试,将两者结果与解析解进行比较,进一步验证了复合曲梁的理论公式的正确性,此举也为高校有关复合曲梁的开放性实验提供了一些参考。     

A load-holding time prediction method based on creep strain relaxation for the cold-stretching process of S30408 cryogenic pressure vessels

Austenitic stainless steel (ASS) has been widely used for cryogenic pressure vessels. Its high strain hardening characteristic allows cold-stretching. In the cold-stretching process, the load-holding time is a critical operating parameter which affects the final deformation of the material. In this paper, a load-holding time prediction method for the cold-stretching process of S30408 cryogenic pressure vessels is proposed, based on room-temperature creep strain relaxation. The proposed correlation has only one variable, the maximum circumferential stress applied to the cylindrical shell, which can be easily obtained by finite element analysis. Consequently, the strain rate measurement during the cold-stretching process is significantly simplified. The prediction method and the strain rate measurement were verified by experimental measurements conducted on two vessels manufactured via the cold-stretching process. The measured strain relaxation times accurately matched the calculated values and the load-holding time for the process was well predicted.     

基于有限元强度折减法的双孔并行隧道间距设计优化研究

研究双孔并行隧道双洞间距对隧道围岩稳定性的影响,根据有限元强度折减法数值模拟计算得到的不同线间距条件下的隧道安全系数和围岩及支护结构内力、位移、塑性区的结果分析,对嵩山隧道的线间距进行了优化设计,确定了最佳、最小线间距.     

Supporting collaborative dissection through the development of an online wiki positively impacts the learning of veterinary anatomy

An innovative series of dissections of the canine abdomen was created to facilitate social distancing in the dissection room following COVID-19 restrictions imposed in the UK. In groups of six, first-year veterinary students took turns dissecting selected parts of the canine abdomen while maintaining social distancing and documenting their work with video and photographs. Here, students learned about the canine abdominal anatomy by dissecting, recording the dissections of others in their group, and compiling the recorded material into a collaborative electronic media portfolio (Wiki). An online formative multiple-choice test was created to test students' knowledge of the canine abdominal anatomy. The result analysis showed that although students achieved the learning outcomes only by studying the Wiki, they had better performance in the anatomical areas where they learned through the dissection (p < 0.05). Student performance was very similar in the areas in which they were present in the dissection room and participated in recording the dissection compared with the areas that they effectively dissected (p > 0.05). A qualitative thematic analysis was developed to understand students' opinions via their feedback on this dissection approach. Our results showed that student collaboration and the development of practical skills were the most valued aspects of this dissection teaching initiative. Moreover, these results show that developing a group Wiki has a positive impact on student achievement of learning objectives, with a practical hands-on dissection being fundamental for the optimal learning of the canine abdominal anatomy.     

Pressure from the lips and the tongue in children with class Ⅲ malocclusion

Objective： To discuss possible relationships between class In malocclusion and perioral forces by measuring the pressure from the lips and the tongue of children with class nI malocclusion. Methods： Thirty-one children with class In malocclusion were investigated and their perioral forces were measured at rest and during swallowing under natural head position by a custom-made miniperioral force computer measuring system. Results： The resting pressures exerted on the labial side and palatine side of the upper lett incisor, as well as the labial side and lingual side of the lower lett incisor, were 0 g/cm^2, 0 g/cm^2, 0.57 g/cm^2 and 0.23 g/cm^2, respectively. Correspondingly, the swallowing forces were 2.87 g/cm^2, 5.97 g/cm^2, 4.09 g/cm^2 and 7.89 g/cm^2, respectively. No statistical difference between muscular pressure and gender existed. During swallowing, the lingual forces were significantly higher than the labial forces （P〈0.01）, however, at rest there was no significantly different force between these two sides. Compared to the normal occlusion patients, children with class Ⅲ malocclusion had lower pedoral forces. The upper labial resting forces （P〈0.01）, the lower labial resting forces （P〈0.05） and all the swallowing pressures from the lips and the tongue （P〈0.01） showed statistical differences between the two different occlusion conditions. Meanwhile, no significant difference was found for the resting pressure from the tongue between class Ⅲ malocclusion and normal occlusion. Conclusion： Patients with class Ⅲ malocclusion have lower perioral forces and this muscle hypofunction may be secondary to the spatial relations of the jaws. The findings support the spatial matrix hypothesis.     

无芯模旋压旋轮轨迹曲线对其成形精度影响的仿真研究

研究目的：验证无芯模旋压工艺可行性,同时深入探究此新型工艺机理,研究并获取旋轮轨迹曲线参数化控制及其对于零件成形精度的影响趋势。创新要点：基于贝塞尔曲线实现对于无芯模旋压旋轮轨迹曲线的参数化控制;通过构建包括成形与回弹工艺过程的无芯模旋压仿真模型,研究参数化轨迹曲线对成形件壁厚及形状精度的影响趋势及关系,同时对成形过程变形区应力应变进行了深入探究分析。研究方法：1．基于三次贝塞尔曲线实现对于旋轮轨迹曲线的拟合以及参数化控制（图3）;2．利用LSDYNA软件实现对无芯模旋压成形及回弹工艺综合仿真及其过程、结果数据的提取;3．研究不同参数化轨迹曲线下成形件壁厚及形状精度变化趋钟（图12和13）,获取量化轨迹曲线对于零件成形精度影响关系（表3）,并通过增加实验组验证所获关系模型;4．提取成形过程中及成形后板料变形区应力及应变数据（图14-19）,深入探究上述变形机理。重要结论：凹轨迹曲线下,坯料中部出现最大减薄及变形程度,且降低曲线曲率,形状精度提高;凸轨迹曲线下,最大减薄及变形区域出现在坯料后部,且降低曲线曲率,壁厚及形状精度均提高。     

Study on the Stress of DLC/MCT Interface by Finite Element Method

l IntroductionDLC film is one of coating materials that has highhardness and good wear-resisbot PrOPerlies. When thefilm is deposited on low haulness substrates with thedifferent YOung's model and expansion coefficient, ahigh stress occurs in the film, which resulted in thedecrement of the adherence of the film and the filmspliting or carking['~4]. In order to improve theadherence of DLC film on the soft subside, the mostcommon method is tO colltrol the iIYIPurities, such as H,St, N and…     

A coupled thermal–hydraulic–mechanical–chemical (THMC) model for methane hydrate bearing sediments using COMSOL Multiphysics

Methane gas extraction by a deep well installed in methane hydrate bearing sediments (MHBS) found in deep subsea and permafrost regions is a coupled thermal–hydraulic–mechanical–chemical (THMC) process. The key processes include heat convection between layers, local deformation due to compaction, and stress relaxation caused by damage of the bonded structure. As improper production may induce formation compaction, sand production, and wellbore failures, a numerical code is needed to simulate the THMC processes during methane gas production so that geomechanics and production risks can be quantified. In this study, a nonlinear THMC model was implemented in the partial differential equations (PDE) and structural mechanics module of the COMSOL Multiphysics^® finite element code. This paper describes the non-linear coupled governing equations of the mechanical behavior during hydrate dissociation. In particular, it introduces a new thermodynamics-based constitutive model to simulate the mechanical behavior of hydrate bearing sediments. The performance of the newly developed code was examined by comparing the computed results with test data and other simulation results. The differences between fully coupled and semi-coupled models were analyzed. For example, heterogeneous turbidite layers observed in the Nankai Trough were modeled, and behaviors such as heat convection between different layers, shear stress and strain concentration were examined.     

Pressure from the lips and the tongue in children with class III malocclusion

Objective:To discuss possible relationships between class III malocclusion and perioral forces by measuring the pressure from the lips and the tongue of children with class III malocclusion. Methods:Thirty-one children with class III malocclusion were investigated and their perioral forces were measured at rest and during swallowing under natural head position by a custom-made miniperioral force computer measuring system. Results:The resting pressures exerted on the labial side and palatine side of the upper left incisor, as well as the labial side and lingual side of the lower left incisor, were 0 g/cm2, 0 g/cm2, 0.57 g/cm2 and 0.23 g/cm2, respectively. Correspondingly, the swallowing forces were 2.87 g/cm2, 5.97 g/cm2, 4.09 g/cm2 and 7.89 g/cm2, respectively. No statistical difference between muscular pressure and gender existed. During swallowing, the lingual forces were significantly higher than the labial forces (P<0.01), however, at rest there was no significantly different force between these two sides. Compared to the normal occlusion patients, children with class III malocclusion had lower perioral forces. The upper labial resting forces (P<0.01), the lower labial resting forces (P<0.05) and all the swallowing pressures from the lips and the tongue (P<0.01) showed statistical differences between the two different occlusion conditions. Meanwhile, no significant difference was found for the resting pressure from the tongue between class III malocclusion and normal occlusion. Conclusion:Patients with class III malocclusion have lower perioral forces and this muscle hypofunction may be secondary to the spatial relations of the jaws. The findings support the spatial matrix hypothesis.     

温度、pH及碳氮源对产色素青霉菌株（Penicilliumsp．）生长的影响

PSO312是从土壤分离的1个青霉菌株,生长中能产生不同酸碱性条件下显黄色与紫红色等天然色素物质．通过菌株固体平板上恒温培养,168h测定菌落直径的方法研究了温度、pH及碳、氮源对菌株（Penicilliumsp．）生长的影响．研究表明31℃为菌株生长的最适温度．31℃培养以pH2—3的最快,pH8—9生长次之,24℃培养以pH8—9生长最快,pH3—4其次．菌株以蛋白胨4g／L、牛肉膏4g／L、酵母膏2g／L及尿素2g／L为氮源培养的菌落直径分别为55．75mm、51．5mm、55．5mm及25．3mm．在（NH4）2SO4 2g／L、NH4NO3 3g／L、NaNO3 4g／L、KN034g／L用量之上培养生长最快,菌落直径分别为35mm、34mm、35mm、及32mm．葡萄糖、蔗糖用量30g／L、果糖20g／L及乳糖25g／L的生长速率最快,菌落直径分别为45mm、38mm、38mm及39mm．丙三醇与淀粉25g／L培养的菌落直径均为39mm．     

高产柠檬酸突变菌株以玉米粉为原料的生物反应器扩大生产研究

研究目的：研究高产黑曲霉突变菌株以玉米粉为原料的生物反应器扩大发酵,以期获得适合于工业化生产柠檬酸的发酵工艺。 创新要点：以玉米粉为原料,系统地研究了筛选得到的高产菌株在50L生物反应器中不同糖浓度发酵生产柠檬酸的特性,最终优化出适合于工业化生产柠檬酸的发酵工艺。 研究方法：（1）利用淀粉酶对粉碎后的玉米进行液化,然后过滤,最终得上清液;（2）以50L生物反应器作为发酵设备,对筛选得到的高产柠檬酸菌株进行扩大培养;（3）通过测定不同培养时期中积累的柠檬酸含量和剩余的残总糖,最终优化出高效率生产柠檬酸的发酵工艺。 重要结论：以不同糖浓度的液化玉米粉上清液作为碳源,突变菌株H4002能积累177．7--196．0g,L的柠檬酸,效率能达到2．96～3．27g/（L·h）,尤其当糖浓度为210g／L,H4002菌株表现出最佳的柠檬酸生产水平,如柠檬酸积累187．5g/L,生产效率达3．13g／（L·h）。上述结果说明了突变菌株H4002拥有快速生产柠檬酸的能力。     

类金刚石薄膜/HgCdTe晶体界面应力的有限元分析

Micro-indention and finite element method (FEM) are used to study the stress at the interface between diamond-like carbon (DLC) film and mercury cadmium telluride (MCT) substrate, with different coating thickness, deposition temperature and indention load. The FEM simulation results show that when Young＇s modulus ratio of the coating to the substrate Ec/Es相似文献   

晶粒尺寸对16 Mn 钢 MnS 夹杂物的应力应变分布影响

基于ABAQUS有限元分析方法,对两种热处理工艺下的16 Mn钢中MnS夹杂物在同一拉伸载荷作用下的应力和应变分布进行了研究。结果表明,两种晶粒尺寸的材料在长条形MnS夹杂物附近存在着垂直于加载方向的X形状的Mi-ses应力和PEEQ集中区。但细晶的16Mn钢中MnS引起的应力和应变集中程度要明显大于粗晶的16Mn钢中MnS引起的应力和应变集中,其原因与细晶强化有关。     

基于ANSYS的某轻型车车架纵梁优化设计

针对某型车架满载时车身产生严重弯曲变形的问题,在有限元法的基础上,利用ANSYS软件建立车架三维有限元分析模型,并进行变形和应力计算机仿真分析,结合变形实验,得到车架变形及应力变化规律,找出了车架产生严重弯曲变形的原因,并对大梁截面尺寸进行优化,提出优化改进方案。