Effect of partial replacement of geopolymer binder materials on the fresh and mechanical properties: A review

The growth of demand for concrete raises concerns about the consumption of natural resources and ordinary Portland cement. Geopolymer composites show promise as a sustainable alternative for conventional cement concrete. Considering the wide range of potential geopolymer composites applications (including suitability for transportation infrastructure, underwater applications, repair and rehabilitation of structures as well as recent developments in 3D printing), the desired fresh and mechanical properties of the geopolymer composite may vary between applications: for example, rapid setting can be a merit for certain applications and a demerit for others. Therefore, the desired fresh and mechanical properties (e.g., workability, setting time, compressive strength, etc.) can be controlled for a given geopolymer source material through its partial substitution by natural or by-product materials. Recognizing the critical role of various replacement materials in enhancing the potential applications of geopolymer composites, the present review was undertaken to quantify and understand the effect of partial replacement by fly ash, metakaolin, kaolin, red mud, slag, ordinary Portland cement, and silica fume on the setting time, workability, compressive strength and flexural strength of various source materials addressed in the literature. The review also provides insights into research gaps in the field to promote future research.     

An analytical model to determine the ultimate load on masonry arch bridges.

This paper proposes an analytical elasto–plastic model to describe the behavior of arches. The modeling is carried out using the equations of (i) horizontal equilibrium, (ii) vertical equilibrium and (iii) equilibrium of moments. The latter equations of equilibrium are ordinary differential equations which can easily be solved by adding boundary conditions, imposing restrictions on the horizontal and vertical movement and on the rotation in the abutments of the arch. For masonry arches, including material properties allowing the occurrence of cracks and the subsequent formation of hinges is required. The latter theory has been implemented in a computer program (Matlab), offering numerical simulations. The software was used to illustrate two case-studies, i.e., the assessment of an arch loaded with a vertical point load and one with a horizontal point load.     

普通中央空调防范疾病传播的措施

指出普通中央空调在防范空气类传播疾病时 ,存有缺陷 ,必须采取有效措施 ,对其进行适当改进 ,以提高中央空调在使用中防范疾病传播的能力     

改善普通水泥耐久性的研究

研究了活性组分及少量的引气剂对水泥性能的影响。实验表明：活性组分或与少量的引气剂复合使用，降低了水泥砂浆的大孔体积和干缩率，提高了其抗渗性、抗化学侵蚀性、抗钢筋锈蚀性，并改善了水泥砂浆的某些力学性能。     

浅谈解的存在唯一性定理在《偏微分方程数值解》中的应用

从一个新的角度讨论常微分方程中解的存在唯一性定理在偏微分方程数值解法中的重要应用。给出一类伪双曲型偏微分方程的新的分裂混合有限元数值格式,将该格式转化成常微分方程系统,利用解的存在唯一性定理证明该系统是存在唯一解的。通过简短的讨论、概述明确解的存在唯一定理在偏微分方程数值解中的应用方法．并希望能够在教学科研未来的发展中有新的观念。     

基于单片机控制的燃气灶自动开关设计

本文以AT89C51单片机为核心,与传统电子燃气灶结合,设计出可以自动点火的燃气灶。该燃气灶通过感受压力来控制燃气的通断和点火,并通过温度传感器检测燃气灶是否已经点燃了。     

Solving differential matrix Riccati equations by a piecewise-linearized method based on diagonal Padé approximants

Differential Matrix Riccati Equations (DMREs) appear in several branches of science such as applied physics and engineering. For example, these equations play a fundamental role in control theory, optimal control, filtering and estimation, decoupling and order reduction, etc. In this paper a new method based on a theorem proved in this paper is described for solving DMREs by a piecewise-linearized approach. This method is applied for developing two block-oriented algorithms based on diagonal Padé approximants. MATLAB versions of the above algorithms are developed, comparing, under equal conditions, accuracy and computational costs with other piecewise-linearized algorithms implemented by the authors. Experimental results show the advantages of solving stiff or non-stiff DMREs by the implemented algorithms.