钻芯法检测混凝土强度对比试验的数理统计分析

运用配对设计的差值均数与总体均数0作比较的t检验法,对两站钻芯法检测混凝土强度值进行数理统计分析,结果表明芯样的切割、打磨和试压过程容易出现问题,其端面修补厚度和平整度、试压初始速度等对混凝土强度检测值影响较大。     

Effects of gamma irradiation and moisture absorption on mechanical properties of PA6/PTFE blends

PA6/PTFE blends with varying polytetrafluoroethylene content from 3% to 15%(mass fraction) were irradiated by 60Co gamma-ray with various doses(20,50 and 100 kGy) under ambient conditions.Moisture absorption test,U-notched Charpy impact test and quasi-static tension and bending were conducted to investigate the effect of irradiation on moisture absorption and mechanical properties of the blends.It is shown that the exposure of the blend to 60Co irradiation improves the tensile modulus,tensile strength and f...     

智能变电站二次设备检验光纤防误拔插装置设计与应用

通过比较光开关、通信领域法兰卡条设计方案,提出一种使用快拆式光纤转接口的专用光纤防误拔插装置,并对装置的固定、尺寸、重量、防尘等予以分析。该防误拔插装置可有效防止光纤误拔插操作,减少光纤拔插次数,避免光纤接口损坏,提高检验效率,能满足二次检修实际使用需求。     

Water-absorptivity and mechanical behaviors of PTFE/PA6 and PTFE/PA66 blends

The effects of polytetrafluoroethylene （PTFE） content on water-absorptivity, tensile strength, flexural strength, and notched impact strength of polytetrafluoroethylene/polyamide 6 （PTFE/PA6） and polytetrafluoroethylene/polyamide 66 （PTFE/PA66） blends were investigated by water immersion test, uniaxial tensile test, three-point test, and Charpy impact fracture test. The water-absorptivity in the blend decreases with increasing PTFE content, which indicates that the PTFE phase restrains the polyamide phase from water absorption. For water-free blends, the addition of PTFE causes a reduction in tensile strength, while for water-absorbed PTFE/PA6 blends, the tensile strength increases with increasing PTFE. Simultaneously, the absorbed water improves the elongation, but results in a notable reduction in flexural strength of the blends. Although the addition of PTFE causes a reduction in notched impact strength of the blends, as compared to pure polyamide, the absorbed water has little effects on the notched impact strength of the blends. Finally, the effects of temperature and loading frequency on complex viscosity parameters of PTFE/PA6 and PTFE/PA66 melts were tested. It is found that the complex viscosity of PTFE/PA6 melt is reversed with increasing temperature and shear velocity, but that of PTFE/PA66 melt increases approximately in exponential form with increasing temperature. To fill polyamide with suitable mass percentage of PTFE can effectively reduce the viscosity of blend, and as a result, the molding and processing properties are improved.     

γ射线辐照对PA6/PTFE合金吸水与力学性能的影响

为了探讨辐照对尼龙6(PA6)基共混材料吸水性能和力学性能的影响,制备了PA6和聚四氟乙烯(PTFE)共混合金并在室温下进行不同剂量的60Coγ射线辐照.通过吸水率测试、准静态拉伸和弯曲实验以及缺口冲击测试,研究了辐照对PA6/PTFE共混体系吸水性能以及吸收水和辐照剂量对共混合金动静态力学性能的影响.结果表明,辐照过程引发交联反应,共混合金的拉伸强度、拉伸模量和弯曲模量均随辐照剂量的增大而增大,而缺口冲击强度和吸水率则随之减小.吸收水对共混合金缺口冲击强度的影响与合金组分有关.PTFE含量较低时,吸收水抑制PTFE对合金冲击强度的减弱作用;当PTFE的质量分数大于7%时,吸收水反而加剧PTFE对材料冲击强度的减弱效应.此外,PA6/PTFE合金的吸水率随PTFE含量的增加而降低,而弯曲模量则先增后减.     

混杂尺寸纲纤维混凝土试验研究

对4种不同的钢纤维混凝土和2种相应的素混凝土进行了抗压、劈裂和4点弯曲实验.结果表明,钢纤维混凝土的上述强度明显优于素混凝土的相应强度;而钢纤维再生混凝土的上述强度明显优于钢纤维卵石混凝土的相应强度;混杂尺寸钢纤维混凝土的上述强度不如单一尺寸钢纤维混凝土的相应强度.     

混杂尺寸钢纤维混凝土试验研究

对4种不同的钢纤维混凝土和2种相应的素混凝土进行了抗压、劈裂和4点弯曲实验。结果表明,钢纤维混凝土的上述强度明显优于素混凝土的相应强度;而钢纤维再生混凝土的上述强度明显优于钢纤维卵石混凝土的相应强度;混杂尺寸钢纤维混凝土的上述强度不如单一尺寸钢纤维混凝土的相应强度。     

矿用带式输送机新技术应用前景分析

探讨了带式输送机智能自动化集中控制和无人值守技术、输送带防纵撕技术、节能降耗新技术、快速安装与回撤技术等新技术的引入和应用前景。从视觉功能、听觉功能和触觉功能3个方面阐述如何真正实现无人值守;介绍了一种新型矿用输送带纵向撕裂识别装置,该装置利用摄像机视频识别技术对输送带表面损伤进行实时识别和判断;分析得出以芳纶作为骨架材料的新型橡胶输送带、视频识别智能调速技术、低阻力不锈钢托辊的应用能够有效实现节能降耗;介绍了一种带式输送机无基础固定方式,实现了带式输送机的快速安装与回撤。矿用带式输送机新技术的应用将逐步实现高智能化集中自动控制、快速高效安装和回撤等功能,为煤矿实现安全高产高效打下坚实基础。     

混凝土强度检测技术的对比试验分析

为了提高检测机构对混凝土强度的检测水平,在同等条件下选择了2个检测站进行对比试验和分析,探讨了影响混凝土强度检测结果的因素;得到标准试件、钻芯法、回弹法、后装拔出法等测得混凝土强度之间的关系和差异,同时分析了我市三家商品混凝土公司的质量状况。