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71.
72.
The use of hypoxic air venting system as fire protection is increasing and is sometimes used to replace traditional extinguishing systems. An oxygen level of 15% is generally used because a lower concentration could pose serious health risks. On the request of the Swedish Radiation Safety Authority, a literature review was conducted to determine advantages and challenges with the system and further research needs. The main advantages with a reduced oxygen environment are the reduced probability of ignition and lowered heat release rate. However, at 15% oxygen level, risk for fire still exists, and the system cannot be seen as an alternative to extinguishing systems. Reduced oxygen environment also results in higher production rates of soot and smoke, and there is limited knowledge regarding the effect of fuel configuration and fire behavior of products. In addition, a first evaluation of the test method specified in the hypoxic air venting standards was carried out through testing. The testing showed that the particleboard passed the test criteria at normal atmosphere even though it is commonly known that a particleboard burns in normal air. It is concluded that the test method has deficiencies, and there is clearly a need for development of the test method to guarantee safety levels. © 2013 The Authors. Fire and Materials published by John Wiley & Sons, Ltd. 相似文献
73.
The thermal performance of a passive solar house in Ireland having high energy conservation standards is compared with that of a similar sized conventional dwelling house. In both cases the performance over a meteorological Test Reference Year is assessed using climatically responsive models developed experimentally which predict their internal temperature without heating. The results indicate that the conventional house required over three times as much auxiliary heating as the passive solar house. Solar gain accounted for over half the gross heat demand in the solar house compared to 13% in the bungalow. An added advantage of the increased utilization of solar gain was the estimated reduction in the heating season from nine to six months. 相似文献
74.
Lars Nilsson 《Drying Technology》2014,32(1):39-46
Dewatering on the paper machine takes place by gravity, suction, pressing, and evaporation. Optimizing the operation of the vacuum system is important, since the electricity consumption of the vacuum pumps might be one-fifth of the total electricity consumption of the paper machine. Vacuum dewatering involves large volumes of air penetrating the web. The present study presents four sets of measured air flow rates useful for designing industrial equipment. The mass flux of air increases with increasing applied vacuum and decreases with increasing basis weight. Paper technological parameters, such as fiber size and fiber flexibility, also influence the mass flux. 相似文献
75.
Fredrik Nilsson 《电子测试》2006,(4):41-45
网络摄像机最初的设计目标就是为了利用数字图像、网络和Internet所具有的优势来拓展基于网络的新应用,因此在最开始视频监控应用被模拟技术所统治的时候,从来没有人想过会把它们应用到专业的视频监视应用当中.这一情况目前显然已经发生了变化:近两年来,网络摄像机的技术水平已经赶上了模拟摄像机,能够完全满足专业视频监控的实际需求和技术规范,在一些与视频监控相关的重要因素方面,网络摄像机的性能甚至已经超过了模拟摄像机.因此,用户有足够的理由在专业视频监控应用中选择网络摄像机. 相似文献
76.
Background
Whole grain (WG) intake is associated with reduced risk of obesity, type 2 diabetes and cardiovascular disease, whereas type 2 diabetes increases the risk of cognitive decline and dementia. The purpose of this study was to investigate the effects of short-term intervention with WG rye on cognitive functions, mood and cardiometabolic risk markers in middle-aged test subjects.Method
Rye-based breads were provided to 38 healthy test subjects (aged 52-70y) during three consecutive days in a crossover study design, using white wheat flour bread (WWB) as a reference. The rye-based bread consisted of a WG rye kernel/flour mixture (1:1 ratio) supplemented with resistant starch type 2 (RS2) (RB?+?RS2). The last bread portion was ingested at 2100 h, and cognitive function, mood and cardiometabolic risk markers were determined the following morning, 11???14 h post intake.Results
In comparison to WWB, the RB?+?RS2 product increased ratings of mood parameters (valance, P?<?0.001; activation P?<?0.05). No differences were seen in the cognitive tests depending on intervention (P?>?0.05). RB?+?RS2 increased insulin sensitivity (P?<?0.05), fasting levels of gut hormones (PYY, P?<?0.05; GLP-2, P?<?0.01) and fasting concentrations of plasma acetate, butyrate and total SCFA (P?<?0.001). In contrast, fasting levels of IL???1β were decreased (P?<?0.05). Insulin sensitivity was positively correlated with working memory test performance (P?<?0.05).Conclusions
This study display novel findings regarding effects of WG rye products on mood, and glucose and appetite regulation in middle-aged subjects, indicating anti-diabetic properties of WG rye. The beneficial effects are suggested to be mediated through gut fermentation of dietary fiber in the RB?+?RS2 product.Trial registration
The study was retrospectively registered at ClinicalTrials.gov, register number NCT03275948. Registered September 8 2017.77.
This article describes how a wheel–rail wear detection parameter based on noise was developed by running a rapid transit train instrumented with microphones in a depot with a small curve radius. This full-scale test made use of previous knowledge gained from lab-scale tests. The lab- and full-scale tests showed that noise could be used as an indicator of wear transition, when normal wear turns into severe or catastrophic wear. This transition was accompanied by a significant increase in sound pressure and a broader sound pressure amplitude spectrum; that is, a narrow initial amplitude distribution in the normal wear regime and a broader distribution in the severe wear regime. The measured noise from the inner/low and outer/high rails was analyzed in conjunction with the wear from the outer wheel and comparisons were made between cleaned (exposed to severe wear) and lubricated (no wear) rail. Based on those analyses, a wear detection parameter criterion was developed for this specific train. This wear parameter has been implemented in a real-time condition monitoring system so that warnings of the risk for severe wear could be sent to the maintenance department. Validation of the wear parameter and challenges linked to open system conditions are discussed in this article. 相似文献
78.
In a neutral acetic buffered solution the influence of F? ions on a high purity A1 electrode has been studied by a potentiostatic step method. The experiments show that both the anodic and cathodic reaction rates are increased by the introduction of the F? ions into the electrolyte. The results are explained by assuming that the F? ions enter the oxide lattice and replace some of the O2? ions. The change in charge distribution caused by the replacement affects the reaction rates in such a way that both the anodic and cathodic reaction rates are increased. 相似文献
79.
P. Dupriez A. Piper A. Malinowski J.K. Sahu M. Ibsen B.C. Thomsen Y. Jeong L.M.B. Hickey M.N. Zervas J. Nilsson D.J. Richardson 《Photonics Technology Letters, IEEE》2006,18(9):1013-1015
We demonstrate a pulsed ytterbium-doped fiber master-oscillator power amplifier source at 1060 nm producing over 300 W of average power in 20-ps pulses at 1-GHz repetition rate. The pulses generated by a gain-switched diode were compressed by a chirped fiber Bragg grating and amplified without any distortion with excellent spectral quality. This fiber master oscillator power amplifier system offers versatility and potential for further power scaling. 相似文献
80.
Although most of the world's river systems are regulated, the effects of river regulation on mammals and birds are little known. In fact, speculations are more common than empirical data. A review of this topic is presented, emphasizing northern rivers where most impacts have been described. Effects are related to the major causes of change. It is concluded that the two most disastrous effects of river regulation on mammals and birds are the permanent inundation of vast areas of land, and the disruption of the seasonal flood regime along the river. The design of future investigations to improve our knowledge is considered. 相似文献