排序方式: 共有6条查询结果,搜索用时 4 毫秒
1
1.
Idowu David Ibrahim Tamba Jamiru Emmanuel R. Sadiku Williams Kehinde Kupolati Stephen C. Agwuncha Gbenga Ekundayo 《Composite Interfaces》2016,23(1):15-36
There has been a growing interest in the utilization of sisal fibres as reinforcement in the production of polymeric composite materials. Natural fibres have gained recognition as reinforcements in fibre polymer–matrix composites because of their mechanical properties and environmental friendliness. The mechanical properties of sisal fibre-reinforced polymer composites have been studied by many researchers and a few of them are discussed in this article. Various fibre treatments, which are carried out in order to improve adhesion, leading to improved mechanical properties, are also discussed in this review paper. This review also focuses on the influence of fibre content and fabrication methods, which can significantly affect the mechanical properties of sisal fibre-reinforced polymer composites. 相似文献
2.
Abdullahi Shittu Ismail Aznan Fazli Yasir Muhamad Samudi 《Journal of Radioanalytical and Nuclear Chemistry》2020,324(1):301-315
In this study, 52 samples of ceramic materials were studied for 226Ra, 222Rn, 232Th and 40K natural radionuclides using high-purity germanium detector and relevant radiological hazards parameters were also appraised. Furthermore, the long-term variations of the total effective dose equivalent (TEDE) and effects of wall thickness on TEDE were established and analyzed using RESRAD-BUILD computer code. The observed percentage variations of TEDE are 2% and 8% for 226Ra and 232Th, respectively, while no variation observed for external dose due to 40K. The estimated indoor doses from the studied ceramic materials are all below the recommended maximum limit.
相似文献3.
Complex computational engineering uncertainty analyses have become more prevalent. When input parameters of such engineering models are uncertain, the output metric's uncertainty distribution is of an unknown parametric form. Since Wilks' method, named after the seminal paper by SS Wilks in 1941 entitled “Determination of sample sizes for setting tolerance limits”, is a nonparametric statistical procedure, it has received renewed interest, in particular in nuclear and chemical safety engineering. Unfortunately, the prevailing Wilks' method applied relies on arbitrary specification of order statistics' ranks with undue influence on the sample size recommendations that follow. Herein, a novel modification of Wilks' method involving two quantiles is proposed resolving that arbitrary rank selection. Together with a confidence level to be exceeded, these quantiles uniquely determine the parameters of an order statistics' beta distribution which drive the selection of symmetric tolerance limits. The modified procedure is demonstrated in two illustrative engineering uncertainty analysis examples drawn from the nuclear and chemical engineering domains. 相似文献
4.
Reem Shomal Babatunde Ogubadejo Toyin Shittu Eyas Mahmoud Wei Du Sulaiman Al-Zuhair 《Molecules (Basel, Switzerland)》2021,26(12)
Biodiesel is a promising candidate for sustainable and renewable energy and extensive research is being conducted worldwide to optimize its production process. The employed catalyst is an important parameter in biodiesel production. Metal–organic frameworks (MOFs), which are a set of highly porous materials comprising coordinated bonds between metals and organic ligands, have recently been proposed as catalysts. MOFs exhibit high tunability, possess high crystallinity and surface area, and their order can vary from the atomic to the microscale level. However, their catalytic sites are confined inside their porous structure, limiting their accessibility for biodiesel production. Modification of MOF structure by immobilizing enzymes or ionic liquids (ILs) could be a solution to this challenge and can lead to better performance and provide catalytic systems with higher activities. This review compiles the recent advances in catalytic transesterification for biodiesel production using enzymes or ILs. The available literature clearly indicates that MOFs are the most suitable immobilization supports, leading to higher biodiesel production without affecting the catalytic activity while increasing the catalyst stability and reusability in several cycles. 相似文献
5.
Beierle JM Osimboni EB Metallinos C Zhao Y Kelly TR 《The Journal of organic chemistry》2003,68(12):4970-4972
The synthesis of louisianin C (3), a member of a small family of 3,4,5-trisubstituted pyridyl natural products, is achieved in six steps and 11% overall yield starting from commercially available 3,5-dibromopyridine. The key step is a fluoride-induced desilylation-cyclization to afford carbinol 12. 相似文献
6.
A synthesis of N-aryl and N-heteroaryl amino acid derivatives using palladium catalysis is described. Several carbamate-protected glycine derivatives react with aryl and heteroaryl halides using a palladium/Xantphos catalyst system to access the desired synthons. 相似文献
1