跌坎对消力池水力特性影响的试验研究

为研究跌坎在底流消能中的作用,依托某工程水力学模型,研究了跌坎对消力池内水流流态、临底流速及脉动压强的影响。结果表明:在来流量一定的情况下,随着跌坎高度的增加,消力池内流态会由底流依次演变为淹没混合流及淹没面流流态。加设跌坎可显著降低消力池前半段的临底流速,且跌坎越高,最大临底流速降幅越大,跌坎对消力池后半段的临底流速基本无影响;跌坎对脉动压强影响较大,随跌坎高度的增加,最大脉动压强先增大后减小;加设跌坎后,脉动压强和临底流速沿程先增大后减小,且脉动压力和临底流速的最大值位置基本在同一区域。     

反渗透海水淡化压力能回收装置进展

反渗透海水淡化在各类淡化技术中迅速崛起得益于压力能回收装置的发展.从该类装置的结构、原理、能量回收效率、设备维护和使用寿命等方面分析比较了国内外各类装置的性能,对该类装置的研究进展进行了综述分析.结果表明:正位移式装置各方面性能优于离心式,但现有的正位移式装置存在各自的缺陷,相关核心技术为国外掌握,今后的研发重点是设计具有自主产权且性能优越的压力能回收装置.     

钻井液密度窗口下限的三维数值计算格式

为了得到准确的安全泥浆窗口,结合有限单元法提出了用于计算钻井液密度窗口下限三维数值解的数值计算格式.计算包含了井孔轨迹全长的油田区块整体模型的应力场,利用有限元子模型技术逐点计算井孔轨迹上关键点的泥浆窗口下限值.在数值求解过程中,施加足够泥浆压力保持井孔围岩处于弹性状态,并施加反向载荷形成实际卸载,逐步试算求出泥浆窗口的下限值.利用一个包含直井段和90°转角圆弧段井孔轨迹的简单井孔模型,计算了沿井轴全长各处不同井孔倾角对应的泥浆窗口下限值数值解,并把该数值解和利用经典解析解取得的结果作了比较,证明了算法的有效性.     

Dynamic buffering performance of the honeycomb paperboard filled with polyurethane

A new kind of composite buffering material was made by filling the voids of honeycomb paperboard with polyurethane. Drop tests were performed to evaluate the dynamic energy absorption capacity of the material. Based on the tests results, we analyzed the mechanical behaviors of the material under different conditions and obtained the inherent influencing laws of some factors on the material＇s dynamic buffering performance. It was shown that the dynamic buffering performance varied directly with impact velocity, and inversely with the void diameter, thickness and buffeting area of the composite material.     

不同温度下AZ31镁合金绝热剪切变形局域化

为了了解镁合金在不同温度高应变率载荷作用下发生变形局域化的特点,进而揭示镁合金在高速冲击载荷作用下发生绝热剪切的特殊规律,采用分离式Hopkinson压杆对挤压态AZ31镁合金进行了常温及高温的高速冲击压缩试验,而后对不同温度冲击后的试样通过光学显微镜、扫描电镜和透射电镜进行变形机制的分析.结果表明:常温下试样在受到剪切力后,在剪切区的裂纹周围产生了大量的孪晶;高温下试样的剪切区内产生了明显的绝热剪切带,并且在剪切带周围发现了大量平行的孪晶.在TEM下观察到剪切带内为等轴晶晶粒,在剪切区内发生了动态再结晶过程.     

Preparation and properties of PMMA modified silica aerogels from diatomite

Diatomite was used as raw material to prepare sodium silicate with a modulus of 3.1 by alkalidissolution method and the resulted sodium silicate solution was employed as a precursor. Methyl methacrylate monomers were introduced in wet gels through solution-immersion, and upon heating at 70 ℃, the mesoporous surfaces throughout the skeletal framework were coated with the polymer layer. PMMA modified silica aerogels were successfully synthesized via ambient pressure drying. The properties were investigated by FTIR, NMR, TGA, nitrogen adsorption-desorption, FESEM and nano-indentation, etc. Results indicate that with the increasing of PMMA incorporated into silica aerogels, the bulk density and the BET surface area increase, the porosity decreases. Through the observation of FESEM, it is found that the interconnecting pores and the big pores add, the pore size distribution expands from 5-17 to 28-150 nm. By comparison, the PMMA modified silica aerogels achieve a 52-fold increase in hardness and a 10-fold increase in modulus.     

Leaching Stability of Simulated Waste Forms for Immobilizing An3＋ by Gd2Zr2O7 with Nd3＋

In order to investigate the anti-leaching capability of pyrochlore Gd2Zr2O7 immobilized An3+, trivalent neodymium was used as the simulacrums for radioactive wastes with trivalence, Gd2-xNdxZr2O7(0.0x 2.0) series samples were successfully synthesized by high temperature solid reaction and using Gd2O3, Zr O2 powders as starting materials. The experiments of long-term chemical stability were conducted in synthetic seawater at 40 and 70 ℃. The XRD diffractive data and extraction ratio of as-received samples were collected with the help of X-ray diffraction(XRD) instrument and inductively coupled plasma mass spectrometry(ICPMass). The results indicate that the phases of as-received compounds keep the single phase of pyrochlore. The extraction ratio of Gd3+, Zr4+ and Nd3+ in waste forms is increasing with the increase of immersion time in synthetic seawater. The extraction ratio of waste forms at 70 ℃ is higher than at 40 ℃. The highest extraction ratio of Gd3+, Zr4+ and Nd3+ after 42 days is near 0.025 8, 0.003 8 and 0.045 2 μg·m L-1, respectively.     

一种应用于噪声点分布密集环境下的噪声点识别算法

为了提高DBSCAN及其改进算法在噪声点分布密集环境下的噪声点识别率,通过结合PageRank算法思想及噪声数据分布密集的特点,构造簇间投票映射函数,提出了簇间投票噪声点识别算法-NoiseRank 。实验结果表明,在噪声点分布密集环境下,NoiseRank算法比DBSCAN算法具有更高的噪声点识别率。     

大型高压铸铁烘缸有限元分析和结构优化设计

针对大型高压烘缸应力集中和局部位移偏大等问题,运用有限元分析方法,设计了调整侧缸盖和轴毂连接处的过渡圆角、适当增加两边端盖厚度等结构优化方案。优化结果可使烘缸满足工业生产的需求并符合企业标准的规定。     

涡轮增压器叶轮低压铸造工艺设计及优化

采用UG NX8.0对某涡轮增压器叶轮的三维立体图进行有限元网格划分,应用ProCAST对铝合金叶轮的低压铸造充型过程和凝固过程进行数值模拟,利用VisualCAST对产生的缺陷进行可视化的对比,分析浇注温度、模具温度及压力-时间参数对铝液充型状态和凝固顺序的影响,并获得合适的低压铸造工艺参数。对试铸样品进行检测,结果表明:利用ProCAST可对叶轮的低压铸造工艺进行定量优化。