Gas sensing study of hydrothermal reflux synthesized NiO/graphene foam electrode for CO sensing

Nickel oxide nanosheets have been successfully synthesized on the graphene foam (GF) using hydrothermal reflux process for their application as carbon monoxide (CO) gas sensor. X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, energy dispersive spectroscopy, and gas sorption analysis were used to characterize the structure and morphology of the samples. The morphology (SEM), crystal structure (XRD and Raman), and elemental composition (EDS) analysis of NiO/GF composite confirmed the cubic crystal structure of NiO and elemental composition (i.e., Ni, O, and C) of NiO/GF composite. The results reveal that the incorporation of graphene into NiO nanosheets not only improved the surface area of NiO/GF composite, but also enhanced the performance of the composite on CO sensing by improving its conductivity. These results indicate that NiO/GF has potential as electrode material for CO gas sensor.     

Heat transfer in a conical cylinder with porous medium

In this paper, numerical study of heat transfer in a conical annular cylinder fixed with saturated porous medium is presented. The heat transfer is assumed to take place by natural convection and radiation. The inner surface of conical cylinder is maintained at uniform wall temperature. The governing partial differential equations are non-dimensionalised using suitable non-dimensional parameters and then solved by using finite element method. The porous medium is divided using triangular elements with uneven element size. A computer software is used to solve the coupled momentum and energy equations in an iterative manner. The results are discussed for various values of geometric and physical parameters of porous medium with emphasis on cone angle of the cylinder. It is seen that the cone angle plays a vital role in heat transfer from the hot surface to porous medium.     

水域城市的主题

水文地理景观需要一种独特的设计思考及实践方式，甚至一种当代设计语境下新的水理念。鉴于水域都市主义急需认知的转变，文章引用达卡城作为此理念的起点。将达卡与经历了类似爆炸式增长的其它城市区别开来的是达卡城与由壮丽河流、凶猛洪水、大量的河道淤积与陆地偏移所构成的景观之间错综复杂的关系。在三角洲变幻莫测的水文世界里，动态的河流、运河、湿地、冲积平原、农田、冲积阶地，及人类栖息地构成了城市及聚落。对这类城市的水利愿景应从其边缘的珍贵湿地和农田景观开始，引导一种整合都市生活、农业和洪泛区的理念。