大宗数据实时处理优化方法的研究及应用

主要讨论在需要进行大宗数据实时处理的企业级计算环境中影响系统处理性能的主要因素。以及如何通过优化处理方式规避这些因素、降低I／O并发冲突和提高系统实时处理性能的方法。对上述方法的风险进行了描述,并给出优化处理崩溃／恢复和保持数据一致性的策略。     

化学气相渗透法制备三维针刺C/SiC复合材料的烧蚀性能

用化学气相渗透法制备了三维针刺碳纤维增强碳化硅陶瓷基复合材料,复合材料的平均密度为2.15 g/cm3,气孔率为16.0%.用氧乙炔焰研究了复合材料的烧蚀性能,用扫描电镜分析了烧蚀表面的形貌,用表面能谱分析了烧蚀产物的成分.复合材料的线烧蚀率和质量烧蚀率分别为0.03mm/s和0.004 7 g/s.在烧蚀中心区,烧蚀最严重,表层只有C纤维骨架,且C纤维呈针状,复合材料的烧蚀以升华和冲刷为主.在烧蚀过渡区,垂直于烧蚀面的C纤维表现出端部锐化、根部细化的特性,平行于烧蚀面的C纤维呈针状,复合材料的烧蚀以氧化和机械剥蚀为主.烧蚀边缘烧蚀不明显,烧蚀产物和SiC基体熔融后覆盖在烧蚀表面,阻碍了复合材料的进一步烧蚀,复合材料的烧蚀以氧化为主.     

复杂性测度在肌电信号模式识别中的应用

针对表面肌电信号(SEMG)的非平稳特性,提出了一种以复杂性测度和支持向量机(SVM)相结合的肌电信号模式识别新方法。肌电信号的复杂度作为一种新的肌电信号特征,算法简单。支持向量机是一种新的机器学习机制。通过对采集的四通道表面肌电信号进行分析,提取其复杂性测度信息构建特征矢量,利用“一对一”分类策略和二叉树构建的多类支持向量机分类器,很好地实现了对前臂的八种动作表面肌电信号的模式分类。实验表明,由支持向量机对肌电信号的复杂度特征进行分类,具有很好的稳定性和准确率,为肌电信号及其它非平稳生理电信号的模式分类提供了一种新思路。     

Moisture transfer and stress development during high-temperature drying of Chinese fir

Abstract

The knowledge of moisture content (MC) and drying stress are crucial parameters to control the drying process and maintain the quality of dried wood. Herein, we investigated the pattern of moisture transfer and stress development in Chinese fir during the high-temperature drying process. The MC in each layer of lumber was separated into bound water and free water via nuclear magnetic resonance (NMR), and the drying and residual stress were measured using prong test method. There was different MC in each layer along the thickness, resulting in an MC gradient that initially increased and then decreased, which is consistent with the trend of drying stress. The T₂₁ peak indicating bound water shifted to the left especially when MC was below the fiber saturation point, signifying that the discharge of moisture became difficult with prolonged drying time. The ratio of bound water to free water was different in each layer, indicating that the moisture transfer was different along the thickness. Furthermore, the residual stress was greater than the corresponding drying stress though the disparity reduced gradually, which suggests that the MC gradient was the largest affecting factor for drying stress at high MC stages but decreased to some extent as the drying process continued.     

水泥基渗透结晶型防水材料和纳米二氧化硅改性混凝土自修复性能的研究

为研究水泥基渗透结晶型防水材料(CCCW)与纳米二氧化硅(NS)对混凝土自修复性能的影响,制备了基准混凝土、单掺3％ CCCW、复掺3％ CCCW和1％、2％及3％ NS的5种混凝土试件,通过抗压强度试验、超声波探伤试验和SEM试验研究了混凝土的力学性能与不同养护龄期下(7d、14 d、28 d、56 d)混凝土的自修复性能.结果 表明,随着龄期的延长和NS掺量的增加,混凝土的抗压强度均呈现上升趋势.单掺CCCW和复掺CCCW与NS混凝土的抗压强度优于基准混凝土,且复掺情况下混凝土的抗压强度高于单掺CCCW混凝土;单掺CCCW和复掺CCCW与NS混凝土具有良好的自修复性能.随着养护龄期的延长,复掺情况下混凝土修复后抗压强度的增长趋势和波速明显优于其他混凝土;预压80％极限抗压强度的混凝土自修复效果优于预压60％的情况.其中,复掺3％ CCCW与1％ NS混凝土修复后的抗压强度、波速与强度恢复率均高于其他混凝土;CCCW与NS的掺入促进了裂缝处未水化水泥颗粒的水化反应,生成结晶体,从而形成致密的结晶体网络,提高了混凝土自修复性能.     

铝合金小尺寸空心薄壁圆铸锭热顶铸造

介绍外径为（１２０－２００）ｍｍ壁厚为２０ｍｍ的铝全金空心薄壁圆铸锭（长为７ｍ）热顶铸造原理及特点;对工艺参数对铸锭质量的影响进行了简要的分析,对铸锭表面组织,低倍、高倍组织以及机械性能与普通铸锭进行对比,得出热顶铸锭质量明显优于普通铸坯的;指出存在问题和解决问题的措施 。     

Thermophysical and Mechanical Properties of a Three-Dimensional Hi–Nicalon/SiC Composite

Key thermophysical and mechanical properties of a three-dimensional Hi-Nicalon™/silicon carbide (SiC) composite were tested. The relationship between the thermal expansion coefficient and temperature of the composite from room temperature (RT) to 1400°C was similar to that of chemical vapor deposition SiC. The thermal diffusivity of the composite could be well fitted by a logarithmic function. The composite exhibited excellent mechanical properties at RT and high temperature in vacuum. At RT, the flexural strength and flexural modulus were 1193 MPa and 255.6 GPa, respectively. Above 1200°C, the value of the flexural strength and flexural modulus at high temperature in vacuum decreased as the temperature increased, while the fracture toughness increased as the temperature increased.     

测试技术在风电叶片静力试验的应用

介绍了长距离应变和加载载荷测试技术在风电叶片静力试验中的应用,总结了影响测试精度的因素,并提出了解决措施。     

风电叶片疲劳试验载荷确定方法研究

文章以1.0MW风电叶片(DF64A)为例,研究了在单点单轴恒幅值加载方式下,疲劳试验的疲劳载荷计算方法。根据Bladed软件仿真得出的叶片在风场的疲劳载荷谱(Markov矩阵),利用疲劳损伤理论分析方法及有限元软件研究分析了叶片疲劳试验载荷设计点的位置;最终确定了疲劳载荷设计点在单轴疲劳载荷My作用下的疲劳损伤值;并给出了单点恒幅值加载方式下,该位置的静态载荷参数和动态加载载荷。最终确定出试验方案。     

Sporosarcina pasteurii诱导碳酸盐-铀共沉淀修复低浓度铀废水的试验研究

对有钙源条件下Sporosarcina pasteurii诱导碳酸盐-铀共沉淀修复低浓度铀废水的性能开展了试验研究。试验结果表明,该细菌能分泌脲酶水解尿素诱导产生方解石并促使其与铀发生共沉淀,使废水中铀的去除率达到95.38%;该细菌能够耐受的铀浓度高达500 mg/L;铀的去除率随Ca²⁺浓度的升高而增加;温度在30℃左右和碱性环境有利于方解石与铀的共沉淀。对沉淀产物进行XRD、SEM-EDS表征分析表明,其主要成分为方解石,且包含铀元素;消解分析表明,在方解石形成过程中铀以共沉淀的方式被固定到了沉淀产物中。本研究表明,Sporosarcina pasteurii诱导碳酸盐-铀共沉淀对修复低浓度铀废水有潜在应用前景。