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Wolfgang Priester (1924–2005) was one of Germany’s most versatile and quixotic astrophysicists, reinventing himself successively
as a radio astronomer, space physicist and cosmologist, and making a lasting impact on each field. We focus in this personal
account on his contributions to cosmology, where he will be most remembered for his association with quasars, his promotion
of the idea of a nonsingular “big bounce” at the beginning of the current expansionary phase, and his recognition of the importance
of dark energy (Einstein’s cosmological constant Λ) well before this became the standard paradigm in cosmology.
In memoriam Wolfgang Priester, 22 April 1924 – 9 July 2005 相似文献
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The aim of this work is to investigate the impact of various CO2/N2 ratios on coal pyrolysis and combustion properties and to provide theoretical guidance for better preventing and controlling coal spontaneous combustion in the goaf. The dynamic pyrolysis and combustion characteristics of DX coal were analyzed by using a thermal gravimetric analyzer (TGA) in a constant oxygen atmosphere with different CO2/N2 blend ratios. The Málek method combining Coats-Redfern and Achar methods was used to determine the most probable mechanism functions. CO2 containing atmospheres increased characteristic temperatures, burnout rate, maximum mass loss rate and comprehensive combustion performance index compared to O2/N2 atmospheres. In stages I-III, a lower apparent activation energy was observed in O2/CO2 atmospheres. Apparent activation energy and enthalpy changes showed upward trends in the reaction stage (I→III→IV), whereas Gibbs free energy change and entropy change decreased. The dynamic pyrolysis and combustion of DX coal necessitated increased energy in environment with a CO2/N2 ratio of 4:6, revealing the optimal inhibitory effect on DX coal with this particular ratio. 相似文献
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谢凤岩 《辽宁城乡环境科技》2012,(7):52-53
通过对抚顺某炼油厂在油母页岩干馏过程中产生的高浓度氨氮废水进行负压蒸氨试验,总结出压力、水温、pH、水力停留时间等相关参数对蒸氨效率的影响。 相似文献
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从风机及系统的噪声与振动控制的总体验收标准着手,对风机及系统工艺设计的标准进行描述,提出风机及系统噪声与振动治理的设计方案及工作机理,通过表述风机在系统中的负载特性和不同效率风机在相同管网的不同运行效率及图示,分析说明降噪节能的原理,并以相关改造的两个实例,说明改造的效果,提出风机及系统应用工况优化运行技术,是风机降噪声、节电的必然趋势。 相似文献
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《International Journal of Sustainable Engineering》2013,6(2):93-101
Construction practices tend to have an adverse impact on the environment through their contribution to CO2 emission, increased waste and energy consumption. The United Arab Emirates (UAE) has launched many initiatives to encourage green design over the past years and to work towards a sustainable community. Nonetheless, such initiatives require a considerable amount of time to penetrate the professional psyche and showcase real results that are easily utilised by the construction community. The aim of this research was to study the current degree of use of Green Design Parameters (GDPs) in the UAE construction projects and to identify the main constraints that hinder their application. To achieve the study's objective, a survey was designed and distributed to engineering design professionals in different consulting and contracting companies in the seven emirates of the UAE. Feedback from 112 projects was examined and statistically analysed. The analysis showed a degree of awareness and use of some key GDPs. Moreover, the data showed no correlation between the degree of using GDPs in a project and its cost and schedule. Not surprisingly, the lack of knowledge about green parameters and the lack of trust in recycled materials are the main constraints that featured in the responses. 相似文献