Interaction effects of multiple pool fires

What are the effects of flame behavior of a number of fires burning in close proximity to one another? The results of measurements of burning rates, heat feedback, flame height, and flame trailing are reported for fires involving liquid pools.     

地下空间──未来城市发展的趋势

可持续发展是未来城市建设的主题，伴随全球资源短缺，环境恶化，地下空间的开发利用已被提到越来越重要的地位，并以此作为城市可持续发展的保证之一。本文以大连城市为例，阐述了地下空间开发利用的意义、作用、原则及总体框架。     

Studies on oxidation of benzo [a] pyrene by sunlight and ozone

The destruction of the carcinogen benzo[a]pyrene (BaP) by light is well known; laboratory workers are routinely advised to cover fluorescent lamps with yellow filters while treating samples containing BaP. However until recently the mechanism of oxidation by sunlight and ozone had not been studied in detail. Concentrations of benzo[a]pyrene in urban air are in the range of 5–10 μg/1000 m³. Oxidant concentrations (predominantly in the form of ozone) are reported to be in the range of 0.01 ppm (22 μg per m³). Thus a sampling system with a filter paper would filter about 22,000 μg of ozone passing through and collect about 5 μg of BaP for analysis. The effect of interactions of such large ozone concentrations with BaP deposited on the filter paper is reported; data for the oxidation rates for benzo[a]pyrene coated on quartz surface and exposed to ozone or sunlight are presented. The oxidation products were analysed by thin-layer chromatography and highpressure liquid chromatography. From about eight products detected in these experiments, three have been identified as quinones based on UV-absorption spectrometry and mass spectrometry. Oxidation rates as high as 100% per hour of exposure are observed when less than 0.1 μg of BaP is coated inside the quartz tubes and exposed to ozone or sunlight. Oxidation rates for benzo[a]pyrene (using tritiated BaP) were determined for two types of experimental conditions. In the first set, tritiated BaP was spotted onto a glass fibre paper and sampling continued for 24 h; the loss of BaP was found to be 88%. In the second set tritiated BaP was spotted at intervals of one hour, for eight hours, while sampling is being carried out and the loss of BaP during the period was estimated to be 50%.     

大快活餐厅

牛仔服饰是这一代全球通行的时尚标志。透过利用这种熟悉的符号，加上点变化，营造出独特、开朗但生活化的气氛。典型牛仔服饰的袋口剪裁、车线、拉链、纽扣、皮带扣等，以橙色人造皮塑料制造，将牛仔时装的设计带进餐厅内。出收银处、柜台到座椅，都依照这些细节设计，让人感觉坐下时就像穿上最时尚的橙色牛仔裤般。     

A digital wind gust recorder

The instrument was a byproduct of an undergraduate final year project on wind power which was carried out by the Department of Mechanical Engineering of the University of Liverpool.The windmill test site was on an exposed, rocky island where there was no history of weather recording but a long tradition of violent winds.Field experience during the winter months suggested that corrosion fatigue arising from wind buffeting and salt spray would rank equally with maximum wind pressure as criteria of failure and if modern materials, so convenient for forming aerodynamic surfaces, were to be used then limited life concepts would need to be considered. This called for more knowledge of wind variations at the test site. A complete wind spectrum taken on chart recording instruments would have been ideal but since such such refined devices were not available the instrument to be described was designed.The only wind measuring instrument which was available was a rotating cup anemometer. This supplied an alternating voltage proportional to its rotational speed. It also operated a gear driven microswitch which could give an integrated “miles of wind” reading on an electromagnetic counter.Briefly the e.m.f. generated by the anemometer (Fig. 1) was matched against a pre-set voltage corresponding to the required gust velocity. When this was exceeded an appropriate counter was operated. Only the rising e.m.f. was significant. The subsequent fall was ignored. Initially three stages were incorporated which reported the gusts rising through forty, fifty and sixty knots, respectively. These recorded on separate counters. All basic settings were based on pitot-static speed determinations in a wind tunnel.     

Combined biological and ozone treatment of log yard run-off

Batch biological treatment of log yard run-off reduced biochemical oxygen demand (BOD), chemical oxygen demand (COD) and tannin and lignin (TL) concentration by 99%, 80%, and 90%, respectively. Acute (Microtox) toxicity was decreased over treatment, from an initial EC50 of 1.83% to a value of 50.4% after 48 h of treatment. Kinetics of biodegradation were determined using respirometry and fitted using the Monod and Tessier model. For the Monod model the maximum substrate uptake rate, and Ks values determined were 0.0038 mg BOD/mgVSS min, and 1.4 mg/L, respectively. The efficacy of ozone as a pre- and post- biological treatment stage was also assessed. During ozone pretreatment, TL concentration and acute toxicity were rapidly reduced by 70% and 71%, respectively. Pre-ozonation reduced BOD and COD concentration by < 10%, however a larger fraction of residual COD was non biodegradable after ozonation. Biologically treated effluent was subjected to ozonation to determine whether further improvements in effluent quality could be achieved. A reduction in COD and TL concentration was observed during ozonation, however no further improvement in toxicity was observed. Ozonation increased BOD by 38%, due to conversion of COD to BOD.     

Buckling of compound hyperbolic paraboloidal shells

This paper presents the first elastic buckling analysis of a compound hyperbolic paraboloidal (hypar) shell under a uniformly distributed load. The compound shell is composed of four hypar panels of rectangular ground plan. A special feature of this analysis is the use of the pulse function to deal with the curvature discontinuities at the ridges. The stability-governing equations are derived from the general equations of Reissner for the linear elastic buckling of hypobolic paraboloidal shells, taking into account the curvature discontinuities at the ridges. These equations are then solved in an approximate manner by assuming trigonometric variations of the buckling deformations. Numerical results are presented, which show that the buckling modes of the shell are either symmetrical or antisymmetrical about both axes of symmetry. For antisymmetric buckling, the critical load of the compound shell is the same as that for a single hypar panel.     

我国最大的悬臂结构机库设计与竖向地震力的试验研究

阐明如何在学习国外先进经验基础上,结合我国国情,设计出这个中国最大也是亚洲最大的悬臂结构机库。在许多关键性技术上,做出了较好的尝试。实践证明,完全可靠,为今后设计同类结构提供了宝贵经验,尤其是对长悬臂结构竖向地震力,做了较系统的试验研究,提出了一批有价值的科学数据。这对今后悬臂结构竖向地震力的计算和规范修订都有参考依据。     

小城镇成长机制及其规划启示

一、目前小城镇成长中存在的主要问题目前国内对小城镇界定认识不一。笔者认为小城镇应为建制镇和县城。未来条件好的县城应逐步设为小城市,小城镇主要为县城以外的建制镇,且小城镇人口应达到一定规模,以3万人以上为宜。我国目前小城镇一是规模小、数量多,缺乏重点,不是有序建设,而是一哄而起,盲目追求数量;多数镇是行政建镇和乡改镇的产物,缺乏经济基础和非农产业支撑,缺乏吸引力和辐射功能,大多处于传统的农业经济阶段。二是缺乏科学的区域城镇体系规划和总体规划,小城镇定位缺乏依据,产业结构雷同,缺乏个性;企业规模小、布局分散,难以形…     

Seismic methods for study of soil building properties

Bulletin of Engineering Geology and the Environment - Information about distribution of elastic wave propagation velocities Vp, Vs in the subsurface zone of a soil mass can be obtained rapidly and...