基于 h 型自适应有限元法在薄板冲压 成型中的应用

在对薄板冲压成型这一过程进行有限元仿真分析时,难以精确分析场变量发生剧烈变化的应力 集中及应变梯度大的区域,如何平衡精度和效率间的关系是冲压成型仿真的关键。因此,基于非线性有限元大 变形的相关理论,针对动态仿真的网格自适应关键技术,建立了自适应分析模式下的薄板冲压成型算法。为了 提高计算精度,提出基于单元应变能增量的能量误差准则以及基于板料成型几何特征的几何误差准则,并结合 2 类误差准则,建立了基于自适应分析算法的误差判断准则;为了提高计算效率,引入阻尼因子提出了阻尼子 循环算法,将自适应加密后的板料单元按时间步长划分为若干个区域,并按照不同时间步长分别求解。结果表 明,该算法有效提高了薄板冲压成型有限元仿真的精度与效率。     

不同干密度压实黄土的非饱和渗透性曲线特征及其与孔隙分布的关系

压实黄土在水分入渗条件下容易产生湿陷、不均匀沉降等工程地质问题,因此有必要对其渗透特性进行研究。本文采用基于滤纸法的竖直土柱试验测试了3种不同干密度压实黄土全吸力范围的渗透性曲线。试验结果表明,压实黄土的渗透性曲线随着基质吸力减小分为缓升段、陡升段和饱和段三个阶段,且干密度越小的土三段特征越明显。压实黄土干密度的差异主要影响低吸力段渗透系数,干密度越大,渗透系数越小;基本不影响高吸力段渗透系数。由于渗透系数与孔隙分布密切相关,孔隙越多渗透性越强。因此本文用压汞试验测得了3种土样的孔隙分布曲线。试验表明不同干密度的压实黄土,微孔数量基本相同,对应吸力范围的渗透系数也相同;孔径为1.3μm d 8μm的小孔数量随干密度增大而减小,对应吸力范围的渗透系数也相应地减小;中孔、大孔数量很少,其对土样的渗透性的影响甚微。这反映了渗透性受孔隙分布控制的内在机理。     

Preparation of cerium doped Cu/MIL-53(Al) catalyst and its catalytic activity in CO oxidation reaction

Metal-organic framework (MOF) material MIL-53(Al) with high thermal stability was prepared by a solvothermal method, serving as a support material of cerium doped copper catalyst (Ce-Cu)/MIL-53(Al) material for CO oxidation with high catalytic activity. The catalytic performance between the (Cu-Ce)/MIL-53(Al) and the Cu/MIL-53(Al) catalytic material was compared to understand the catalytic behavior of the catalysts. The catalysts were characterized by thermogravimetric-differential scanning calorimetry (TG-DSC), N₂ adsorption- desorption, X-ray diffraction (XRD), and transmission electron microscopy (TEM). The characterization results showed that MIL-53(Al) had good stability and high surface areas, the (Ce-Cu) nanoparticles on the MIL-53(Al) support was uniform. Therefore, the heterogeneous catalytic composite materials (Ce-Cu)/MIL-53(Al) catalyst exhibited much higher activity than that of the Cu/MIL- 53(Al) catalyst in CO oxidation test, with 100% conversion at 80 °C. The results reveal that (Cu-Ce)/MIL- 53(Al) is the suitable candidate for achieving low temperature and higher activity CO oxidation catalyst of MOFs.     

Effect of deposition time on microstructures and growth behavior of ZrC coatings prepared by low pressure chemical vapor deposition with the Br<Subscript>2</Subscript>-Zr-C<Subscript>3</Subscript>H<Subscript>6</Subscript>-H<Subscript>2</Subscript>-Ar System

ZrC coatings were deposited on graphite substrates by low pressure chemical vapor deposition (LPCVD) with the Br₂-Zr-C₃H₆-H₂-Ar system. The effects of deposition time on the microstructures and growth behavior of ZrC coatings were investigated. ZrC coating grew in an island-layer mode. The formation of coating was dominated by the nucleation of ZrC in the initial 20 minutes, and the rapid nucleation generated a fine-grained structure of ZrC coating. When the deposition time was over 30 min, the growth of coating was dominated by that of crystals, giving a column-arranged structure. Energy dispersive X-ray spectroscopy showed that the molar ratio of carbon to zirconium was near 1:1 in ZrC coating, and X-ray photoelectron spectroscopy showed that ZrC was the main phase in coatings, accompanied by about 2.5mol% ZrO₂ minor phase.     

Synthesis of HTPB based PU-PS IPN membrane for pervaporation recovery of butanol

Hydroxyl terminated polybutadiene(HTPB) based polyurethane(PU)-polystyrene(PS) interpenetrating polymer network(IPN) was prepared and characterized by FTIR, TGA, WCA, swelling experiments, and SEM. The IPN was used for pervaporation(PV) recovery of butanol. Both the permeation flux and separation factor increased with feed temperature, and both water and butanol fluxes increased with feed concentration while no obvious effect of concentration on separation factor was found. Through the formation of IPN structure, the total flux of HTPB based PU increased greatly with the decrease of separation factor. At the feed temperature of 60 °C, the IPN membrane obtained a total flux of 613.3 g/m~2 h with a separation factor of 6.15.     

隐私保护算法在智能电网中的应用

数据聚合是智能电网中的重要环节,在数据聚合的过程中应达到准确、安全、高效节能等指标.通过对DGK密码体制与盲签名加密钥分配技术两种方法的对比分析,得出盲签名加密钥分配技术更加安全可靠,同时计算开销较小的结论.     

高强钢绞线网加固混凝土粘结性能试验研究

通过高强钢绞线网聚合物砂浆加固层与混凝土结构的剥离破坏试验,对加固层与混凝土界面的剥离破坏特征进行了研究。探讨了单侧加固、植筋加固及U型加固等不同的加固方式对加固层抗剪承载力及抗剪强度的影响。试验结果表明,采用U型加固等增加粘结面积的方式能有效提高加固层粘结面抗剪承载力,但同时会削弱加固层的抗剪强度,而在界面上植入抗剪钢筋后,能同时提高聚合物砂浆加固层的抗剪承载力及抗剪强度。根据试验结果,提出了最小植筋率的建议值。     

自然伽马能谱测井在杭锦旗地区的应用

杭锦旗地区二叠系下石盒子组具有岩性复杂、储层物性差及气水识别难的问题,为了解决这些难题,将现有9口井的自然伽马能谱测井曲线应用于储层划分和物性判断、岩性识别以及储层含气性判别中得到了很好的效果,并归纳总结出了自然伽马能谱测井识别气水层的判别标准。自然伽马能谱测井在该地区的成功应用为正确评价杭锦旗地区致密砂岩储层提供了可靠的信息。     

地震波层析成像探测技术与水平定向钻拉管技术在地下障碍物探测中的应用

顶管施工属于非开挖施工方法,是一种不开挖或者少开挖的管道埋设施工技术,该项技术彻底解决了管道埋设施工中对城市建筑物的破坏和道路交通的堵塞等难题,在稳定土层和环境保护方面凸显其优势。但是,在顶管施工过程中一旦遇到地下障碍物,将导致顶管顶力突然增大,顶管顶进方向偏离设计轴线,严重影响顶管施工的顺利进行。福州市某污水顶管施工需要穿越河道,通过前期资料收集发现,河道两侧可能存在护岸抛石等地下障碍物。为了查明护岸抛石的分布情况,综合应用了地震波层析成像探测技术与水平定向钻拉管技术进行探测,既为后期顶管施工的顺利进行提供了参考依据,又降低了探测成本,提高了探测效率。     

地面高精度磁测在龙首山新水井-火石岭地区铀矿勘查中的应用

龙首山地区是以碱交代型为主的铀成矿带,新水井-火石岭地区处于龙首山成矿带中段。通过地面高精度磁测工作,并结合地质情况,对该地段马路沟断裂及岩体分布特征进行了研究。共推断断裂构造5条,圈定侵入岩体8片,其中东南部2片闪长岩主要发育于浅部,而其他地段岩体深部延伸较深,并大致查明了区内构造格架、岩体的发育特征,为本区铀矿勘查提供了找矿信息。