Corrosion behavior of tempered dual-phase steel embedded in concrete

Dual-phase (DP) steels with different martensite contents were obtained by appropriate heat treatment of an SAE1010 structural carbon steel, which was cheap and widely used in the construction industry. The corrosion behavior of DP steels in concrete was investigated under various tempering conditions. Intercritical annealing heat treatment was applied to the reinforcing steel to obtain DP steels with different contents of martensite. These DP steels were tempered at 200, 300, and 400℃ for 45 min and then cooled to room temperature. Corrosion experiments were conducted in two stages. In the first stage, the corrosion potential of DP steels embedded in concrete was measured every day for a period of 30 d based on the ASTM C 876 standard. In the second stage, the anodic and cathodic polarization values of these steels were obtained and subsequently the corrosion currents were determined with the aid of cathodic polarization curves. It was observed that the amount of second phase had a definite effect on the corrosion behavior of the DP steel embedded in concrete. As a result of this study, it is found that the corrosion rate of the DP steel increases with an increase in the amount of martensite.     

一类最速降线与最短路径问题

本文结合梯度讨论了椭球面上一类最速降线问题 ,应用变分法及 Mathematica软件讨论了椭球面上最短路径问题 ;分析了二者的关系 ,旨在加强应用数学知识的能力 .     

一类最速降线与最短路径问题

本结合梯度讨论了椭球面上一类最速降线问题,应用变分法及Ｍａｔｈｅｍａｔｉｃａ软件讨论了椭球面上最短路径问题;分析了二的关系,旨在加强应用数学知识的能力。     

非离子表面活性剂和β-环状糊精包结作用的微量热法研究

用Model-4200型恒温滴定量热系统,研究了非离子表面活性剂(TritonX-114,TritonX-100,TritonX-102,TritonX-405)和β-环状糊精的包结的热力学性质,结果表明:对所有体系,均形成1:1的包结物,ΔHⅲ和ΔSⅲ值均为负值,形成包结物的过程是焓有利而熵不利的过程,而且-ΔHⅲ和ΔSⅲ值随非离子表面活性剂环氧乙烷(EO)链长的增加而减少。另外,非离子表面活性剂环氧乙烷(EO)链越长,包结物稳定常数越小。     

数据库远程过程调用语言编译器的设计与实现

DBRPC（数据库远程过程调用）是开放式分布数据库客户／服务器体系结构中的一种通信服务中件（Middleware）,是解决远程、异构、分性数据库系统互联的关键技术和构造分布信息集成系统的基础机制,本文在DBRPC原体系结构实现的基础上,结合具体要求定义了DBRPL（数据库远程过程语言）,设计并实现了DBRPL编译器。     

用边界元方法分析射孔完井非稳定渗流问题

本文综合考虑了射孔孔眼状态、各向异性储层伤害、以及不同边界条件等因素,建立了射孔井的油藏模型和非稳定渗流数学模型。应用边界元数模直接解法和区域分割技术,得到了随射孔孔眼和储层伤害变化时,孔眼附近储层不稳定渗流规律、生产动态和不稳定压力变化特征。对于更好地解决开发井网布置、射孔参数优化、增产措施设计和不稳定试井方法改进等生产问题有实际指导作用。边界元方法在油藏数值模拟领域有广阔的应用前景。     

微波消解/等离子体发射光谱法测定蒙药哈日阿-布日-16中的多种元素

采用高压密封微波消解,以V(HNO3) V(HClO4)=5 1为溶样试剂,电感耦合等离子体原子发射光谱法(ICP-AES)测定了蒙古药—哈日阿-布日-16中的镁、钙、铬、锰、铁、钴、镍、铜、锌、锶、银、镉、铅等金属元素的含量。结果表明,回收率为99.5%~104.7%,RSD为0.4%~2.3%。哈日阿-布日-16中的多种金属元素,尤其镁、钙、锌、锶的含量较高,未测到有铅、银等元素。     

甘氨酸钙络合物的熔融法合成及表征

以甘氨酸和氢氧化钙为原料,采用熔融法合成了甘氨酸钙络合物,最佳合成条件为:原料摩尔比n甘氨酸:nCa(OH)2=2:1,在熔融状态下,反应温度150℃左右,反应时间40min,并通过元素分析、红外光谱、X-射线粉末衍射、差热-热重等实验手段对该络合物进行了表征,确定其化学式为Ca(NH2CH2COO)2,所得产品的产率达94.1%.     

Atlas of dynamic spectra of fast radio burst FRB 20201124A Atlas of dynamic spectra of fast radio burst FRB 20201124A

Fast radio bursts(FRBs) are highly dispersed millisecond-duration radio bursts,^[1,2] of which the physical origin is still not fully understood. FRB 20201124A is one of the most actively repeating FRBs. In this paper, we present the collection of 1863 burst dynamic spectra of FRB 20201124A measured with the Five-hundred-meter Aperture Spherical radio Telescope(FAST). The current collection, taken from the observation during the FRB active phase from April to June 2021, is the largest ...     

钢-混凝土组合简支桥面连续结构横向应力分析

针对钢-混组合简支梁桥的桥面连续结构开裂等病害,围绕桥面连接板的横桥向应力问题,采用线弹性理论和板的偏微分方程进行分析,得出了桥面连接板挠度和应力的分布函数,建立非线性有限元模型,并进行实桥荷载试验.通过比较理论解、有限元解和实测试验结果,证实了理论解和有限元的有效性.根据得到的分布函数,发现横桥向和纵桥向上的最大拉应力出现在钢梁端部位置的连接板的上缘.此外,还分析了连接板区域尺寸变化对横桥向应力峰值的影响,包括纵梁端部距支座的长度、纵梁的间距以及连接板区域整体尺寸变化.结果表明：较小的纵梁间距和较长的纵梁端部与支撑之间的距离会导致连接板中的横向拉应力峰值增加,并提高横向拉应力在总应力中的占比,从而导致桥面连接板早于设计荷载开裂.因此对于纵梁间距较小、梁端长度较长的钢-混组合简支梁桥桥面连续结构,仅计算其纵桥向受力性能会导致计算结果偏危险,建议按照本文方法考虑横桥向应力对桥面连接板的影响.