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1.
Effects of injection parameters on propagation patterns of hydrogen-fueled rotating detonation waves
《International Journal of Hydrogen Energy》2022,47(91):38811-38822
Two-dimensional rotating detonation waves (RDWs) with separate injections of hydrogen and air are simulated using the Navier–Stokes equations together with a detailed chemical mechanism. The effects of injection stagnation temperature and slot width on the detonation propagation patterns are investigated. Results find that extremely high temperatures can lead to a chaotic mode in which detonation waves are generated and extinguished randomly. Increasing the slot width can reduce the number of detonation waves and finally trigger detonation quenching at a low injection stagnation temperature. But increasing the slot width can change the RDW propagation pattern from a chaotic to a stable mode under high injection temperature. Furthermore, the kinetic parameter τ (representing the chemical reactivity of the mixture) and the kinematic parameter α (representing the mixing efficiency of hydrogen and oxygen) are introduced to distinguish the RDW propagation patterns. 相似文献
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《Journal of dairy science》2022,105(10):8130-8142
Residual feed intake (RFI) is a measurement of the difference between actual and predicted feed intake when adjusted for energy sinks; more efficient cows eat less than predicted (low RFI) and inefficient cows eat more than predicted (high RFI). Data evaluating the relationship between RFI and feeding behaviors (FB) are limited in dairy cattle; therefore, the objective of this study was to determine daily and temporal FB in mid-lactation Holstein cows across a range of RFI values. Mid-lactation Holstein cows (n = 592 multiparous; 304 primiparous) were enrolled in 17 cohorts at 97 ± 26 d in milk (± standard deviation), and all cows within a cohort were fed a common diet using automated feeding bins. Cow RFI was calculated as the difference between predicted and observed dry matter intake (DMI) after accounting for parity, days in milk, milk energy, metabolic body weight and change, and experiment. The associations between RFI and FB at the level of meals and daily totals were evaluated using mixed models with the fixed effect of RFI and the random effects of cow and cohort. Daily temporal FB analyses were conducted using 2-h blocks and analyzed using mixed models with the fixed effects of RFI, time, RFI × time, and cohort, and the random effect of cow (cohort). There was a positive linear association between RFI and DMI in multiparous cows and a positive quadratic relationship in primiparous cows, where the rate of increase in DMI was less at higher RFI. Eating rate, DMI per meal, and size of the largest daily meal were positively associated with RFI. Daily temporal analysis of FB revealed an interaction between RFI and time for eating rate in multiparous and primiparous cows. The eating rate increased with greater RFI at 11 of 12 time points throughout the day, and eating rate differed across RFI between multiple time points. There tended to be an interaction between RFI and time for eating time and bin visits in multiparous cows but not primiparous cows. Overall, there was a time effect for all FB variables, where DMI, eating time and rate, and bin visits were greatest after the initial daily feeding at 1200 h, increased slightly after each milking, and reached a nadir at 0600 h (6 h before feeding). Considering the relationship between RFI and eating rate, additional efforts to determine cost-effective methods of quantifying eating rate in group-housed dairy cows is warranted. Further investigation is also warranted to determine if management strategies to alter FB, especially eating rate, can be effective in increasing feed efficiency in lactating dairy cattle. 相似文献
3.
Alison Jee Samantha Christine Sernoskie Jack Uetrecht 《International journal of molecular sciences》2021,22(6)
Idiosyncratic drug-induced liver injury (IDILI) remains a significant problem for patients and drug development. The idiosyncratic nature of IDILI makes mechanistic studies difficult, and little is known of its pathogenesis for certain. Circumstantial evidence suggests that most, but not all, IDILI is caused by reactive metabolites of drugs that are bioactivated by cytochromes P450 and other enzymes in the liver. Additionally, there is overwhelming evidence that most IDILI is mediated by the adaptive immune system; one example being the association of IDILI caused by specific drugs with specific human leukocyte antigen (HLA) haplotypes, and this may in part explain the idiosyncratic nature of these reactions. The T cell receptor repertoire likely also contributes to the idiosyncratic nature. Although most of the liver injury is likely mediated by the adaptive immune system, specifically cytotoxic CD8+ T cells, adaptive immune activation first requires an innate immune response to activate antigen presenting cells and produce cytokines required for T cell proliferation. This innate response is likely caused by either a reactive metabolite or some form of cell stress that is clinically silent but not idiosyncratic. If this is true it would make it possible to study the early steps in the immune response that in some patients can lead to IDILI. Other hypotheses have been proposed, such as mitochondrial injury, inhibition of the bile salt export pump, unfolded protein response, and oxidative stress although, in most cases, it is likely that they are also involved in the initiation of an immune response rather than representing a completely separate mechanism. Using the clinical manifestations of liver injury from a number of examples of IDILI-associated drugs, this review aims to summarize and illustrate these mechanistic hypotheses. 相似文献
4.
Under the circumstance of perceptual consumption, it is still challenging to grasp consumer's emotions and demands due to the large search space, diversified preferences, and easy fatigue of consumers. To reduce user fatigue and enlarge search space, a novel method was presented to design and optimize the pattern of yarn-dyed plaid fabric using the isolation niche genetic algorithm and rough set theory. Each pattern was encoded as a chromosome based on the real number code. The population was initialized and evolved using INGA to maintain the diversity. The rough set theory was adopted as the fitness function of isolation niche genetic algorithm to extract the consumer's demands. After multiple evolutions, a large set of practical patterns of the yarn-dyed plaid fabric are obtained. Experiments were carried out by 24 testers of different ages and genders. The results prove that the proposed method based on the isolation niche genetic algorithm and rough set theory is feasible and effective, supplying references to the designer. 相似文献
5.
In this article, an analytical technique is introduced to obtain the excitation coefficients of uniformly spaced linear antenna arrays in order to achieve a desired array factor. By integration of the prescribed array factor, the array factor dependency to the progressive phase shift is eliminated. A new system of linear equations is consequently obtained whose solution represents the excitation coefficients of the array. Some examples are presented to verify the accuracy of the introduced method. The performance of this strategy is compared with those obtained by the other well‐known techniques such as Woodward‐Lawson and Fourier transform. It is shown that the presented method estimates the desired array pattern with a very good precision. 相似文献
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张庄铁矿设计采矿方法为大直径深孔阶段空场嗣后充填法。为了最大化发挥采矿设备性能,降低采切工程量,提高回采效率,通过实施一系列技术攻关,实现了将采矿阶段高度由原来的60 m提高到90 m。而作为最初爆破回采的自由面及爆破补偿空间,切割天井施工工艺为影响高阶段矿房爆破回采效果的关键因素,施工质量的优劣,直接影响矿房爆破回采生产作业能否顺利进行,而二次处理在增加施工成本的同时将带来安全隐患。张庄铁矿在面临可参考的成熟经验较少的情况下,结合现场可用的作业条件采取了对比试验的方法,在安全、技术及经济多方面综合分析比较下,确定了最终方案,为张庄铁矿安全稳定生产奠定了基础,同时研究成果可为大型地下矿山生产实践提供一定的参考。 相似文献
9.
水平井压裂技术在低渗透及非常规储层中得到了广泛应用,压裂后水平井的产能预测关系到油田开发方案的制定,因此,国内外学者对压后渗流模型的建立和求解方法做出了不懈的努力。本文详细回顾了国内外学者所建压裂水平井产能预测模型及求解方法,指出了不同模型和求解方法的优缺点,并展望了压裂水平井产能模型的发展方向。 相似文献
10.
文章从风景园林学科的角度出发,对传统老广州曾经存在的地域人文景观里的典型——滨水动态人文景观进行了初步的全面整理,以日常型滨水动态人文景观和节庆型滨水动态人文景观为两种基本类型,总结梳理出超过25种滨水动态人文景观的主要类型,充分说明了广州市传统滨水动态人文景观的多样性和独特性。并以景观格局的理论视角分析了传统滨水动态人文景观在广州旧城的空间格局,分析得出其两个核心聚集区:以祭祀水神的仁威神庙为精神核心节点的呈圆形扩散的西关功能核心区和以长堤滨江段为中线的呈椭圆形扩散的珠江两岸功能核心区,并总结了促使这种人文景观发展与繁盛的历史经验,为广州地域文化景观的发扬及旧城更新工作提供借鉴。 相似文献