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通过对光纤光栅火灾报警器原理的介绍,详述了这一新技术在工程应用中的优点、技术特点和系统组成(由宽带光源、光纤光栅传感器、光纤光栅解调仪和信号处理器组成),并通过在储油罐和公路隧道中的应用实例分析,阐述了该报警器的实际应用。 相似文献
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本文介绍了调压器压力报警器的特点及应用现状,结合万州天气管网系统的特点,分析了该报警器在万州应用的可行性及经济性。 相似文献
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通过对家用燃气报警器的应用现状分析,根据影响产品质量的主要因素,提出产品比选的技术方案,利用产品比选模型对市场上3种家用燃气报警器进行了综合比选。 相似文献
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Klaxon Signals将LED技术添加到Nexus系列声光报警产品中。这种技术应用在小电流消耗及同时闪光的可靠度是非常重要的,新型声光报警器通过一个10~60V(直流)供电,使得它非常适合火灾安全应用。该报警器具有高亮度输出量和较强的耐环境能力,使其在任何环境下都可以安装。 相似文献
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黄慷 《地下空间与工程学报》2021,17(5):1337-1350
在我国当前大规模城市基础设施建设进程中,为提高城市生命线工程的防护性能,降低战时破坏带来的不利影响,对于综合管廊兼顾人防设计的需求逐渐提上议事日程。本文首先系统回顾了我国在该领域内的理论研究历程及工程实践现状,对综合管廊工程兼顾人防设计的理论要点做了全面分析总结,归纳了全套设计方法;其次以杭州亚运村片区综合管廊防护设计为例,侧重于片区管廊防护单元的总体布局特点,介绍了按浙江省人防标准进行防护设计的方法和思路,详细分析各专业防护设计方法及技术措施;最后基于前述内容,提炼了该领域内关键技术问题,并对技术标准及相关技术措施提出了建议。本文提出的设计思路方法以及工程实例,可供目前国内类似工程规划设计借鉴参考。 相似文献
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清末广州中西交汇,景园营造新旧共存互动,推
动岭南园林的近代转型。其中,在繁荣的中西贸易和文化交
流,以及书院文化、士绅文化等的影响下,清末岭南形成了
以广州为中心、十三行行商为代表、官商士绅竞相造园的特
殊历史时期,其造园数量、规模、意匠等均在该时期达到岭
南古典园林发展的巅峰。这一时期也是岭南园林近代转型的
关键时期。在西方文化和清末洋务运动思想的影响下,广州
开始出现洋务花园、公园、市政绿化,以及校园绿地等新型
园林形式。这些具有公共性质的城市景致与新建私园一道广
泛分布在城墙以外,成为清末广州城市空间拓展与风景体系
形成的重要参与者。由于清末广州城外造景的繁荣,从时间
上开启了岭南园林的近代转型,在空间上使岭南园林的地域
性特征得以形成和辨识,其空间性与时间性界定了清末岭南
园林近代转型的物质及文化维度。梳理了清末广州具有代表
性的景园营造活动,在分析其动力机制的同时,探讨城外造
景之于岭南园林近代转型的意义。 相似文献
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Stephan Bose-O'Reilly Gustav Drasch Saulo Rodrigues-Filho Beate Lettmeier Alexandra Maydl Uwe Siebert 《The Science of the total environment》2010,408(4):713-1000
Small scale miners use mercury to extract gold from ore in many countries. An environmental and health assessment was performed in Indonesia in two regions, Galangan in Central Kalimantan and Talawaan in Northern Sulawesi. The environmental assessment showed severe mercury contamination of the sediments, and increased mercury levels in local fish. For the health investigation 281 volunteers were recruited and examined by a standardized questionnaire, a neurological examination and neuro-psychological tests. A medical score was used consisting of significant factors of mercury intoxication. Mercury exposed workers showed typical symptoms of mercury intoxication, such as movement disorders (ataxia, tremor, dysdiadochokinesia, etc.). Blood, urine and hair samples were taken from any participant and analyzed for mercury. The mercury concentration in the biomonitors was high, partly extreme high in the working population, increased in the population living in the same habitat and low in the control group. By a standard protocol which includes a combination of threshold values of mercury in the biomonitors and a medical sum score the diagnosis of chronic mercury intoxication was made for highly burdened workers (amalgam smelters) in 55% in Sulawesi and in 62% in Kalimantan. Less exposed mineral processors and the general population in the mining areas were also intoxicated to a high percentage. 相似文献
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探究“虚实”空间关系,创造个性化的城市空间场所 总被引:1,自引:1,他引:1
作者利用空间的“虚、实”概念,结合格斯塔心理学的“图底”关系,类比分析中国水墨画的留白艺术手法及生态系统中的细胞繁衍规律,通过张家界城市绿化广场周边地段的概念设计的创作实践,提出创造个性化的城市空间场所工作中虚实空间的理念与原则目标。 相似文献
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Trace metal behaviour in estuarine and riverine floodplain soils and sediments: a review 总被引:14,自引:0,他引:14
Du Laing G Rinklebe J Vandecasteele B Meers E Tack FM 《The Science of the total environment》2009,407(13):3972-3985
This paper reviews the factors affecting trace metal behaviour in estuarine and riverine floodplain soils and sediments. Spatial occurrence of processes affecting metal mobility and availability in floodplains are largely determined by the topography. At the oxic-anoxic interface and in the anoxic layers of floodplain soils, especially redox-sensitive processes occur, which mainly result in the inclusion of metals in precipitates or the dissolution of metal-containing precipitates. Kinetics of these processes are of great importance for these soils as the location of the oxic-anoxic interface is subject to change due to fluctuating water table levels. Other important processes and factors affecting metal mobility in floodplain soils are adsorption/desorption processes, salinity, the presence of organic matter, sulphur and carbonates, pH and plant growth. Many authors report highly significant correlations between cation exchange capacity, clay or organic matter contents and metal contents in floodplain soils. Iron and manganese (hydr)oxides were found to be the main carriers for Cd, Zn and Ni under oxic conditions, whereas the organic fraction was most important for Cu. The mobility and availability of metals in a floodplain soil can be significantly reduced by the formation of metal sulphide precipitates under anoxic conditions. Ascending salinity in the flood water promotes metal desorption from the floodplain soil in the absence of sulphides, hence increases total metal concentrations in the water column. The net effect of the presence of organic matter can either be a decrease or an increase in metal mobility, whereas the presence of carbonates in calcareous floodplain soils or sediments constitutes an effective buffer against a pH decrease. Moreover, carbonates may also directly precipitate metals. Plants can affect the metal mobility in floodplain soils by oxidising their rhizosphere, taking up metals, excreting exudates and stimulating the activity of microbial symbionts in the rhizosphere. 相似文献
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Martin Mihaljevi? Vojtěch Ettler Petr Drahota Ladislav Strnad Josef Zeman 《The Science of the total environment》2010,408(6):1286-1294
The weathering of arsenopyrite (FeAsS) has been monitored in soils using an in situ experimental approach. Arsenopyrite in nylon experimental bags was placed in individual horizons in soils in spruce (litter, horizons A, B, and C), beech (litter, horizons A, B, and C) and unforested (horizons A, B, and C) areas and left in contact with the soil for a period of 1 year. The individual areas on the ridge of the Krušné hory Mts., Czech Republic, had the same lithology, climatic and environmental conditions. Scorodite (FeAsO4·2H2O) was identified as a principal secondary mineral of arsenic (As) formed directly on the surface of the arsenopyrite. Scorodite was formed in all the areas in all soil horizons. The amount of scorodite formed decreased in the series beech, spruce and unforested areas. In forested areas, there was a larger amount of scorodite on arsenopyrites exposed in organic horizons (litter, A horizon). The greater rate of arsenopyrite alteration in organic horizons in the beech stand compared to spruce stand is probably a result of faster mineralization of organic material with resulting production of nitrate and better seepage conditions of soil in this area. Speciation of As determined using the sequential extraction technique demonstrated that As was bonded in the soils primarily in the residual fractions prior to the experiment. The As content in the mobile fractions increased in the organic horizon in the forested areas after the experiments. 相似文献
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山东地区地质构造环境十分复杂,历史上曾多次发生中强地震及强震。为深入了解该地区现今构造应力场特征及区域地壳应力积累水平,基于优化处理后的181组地应力实测数据,采用回归分析法全面分析了该地区地应力量值随深度的分布特征,并依据地壳应力积累理论,探讨了区域应力积累水平和地壳稳定性。结果表明,该地区地应力状态主要以?H>?h>?v型和?H>?v>?h型为主,应力状态类型与深度有一定关系;3个主应力?H,?h和?v均随深度呈近似线性增加的关系,应力变化梯度值分别为0.024 2,0.018 0,0.025 8;3个侧压系数KH,Kh和Kav随深度呈近似双曲线分布,随着深度的增加分别向1.46,0.89,1.17趋近;水平差应力相对大小μd更接近于线性分布,随着深度的增加趋向于0.24;最大水平主应力优势方向整体表现为NWW-SEE向,但NEE-SWW向也占有较大比例,优势方位统计结果与世界应力图2016及板块间作用相吻合;沂沭断裂带西侧区域最大水平主应力优势方向整体呈NEE-SWW向,而其东侧区域整体呈NWW-SEE向。?m能较好地反映地壳应力积累能力,?m值主要集中在0.3~0.5,0.2~0.3范围内,该地区的应力积累水平整体上处于中低程度,地壳浅层处于相对稳定状态。逆断型应力状态的?m值主要集中在0.2~0.3范围内,应力积累水平以较低程度为主;走滑型应力状态的?m值主要集中在0.3~0.5范围内,应力积累水平以中等程度为主。 相似文献
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近年来我国城市规划教育的发展和不足 总被引:8,自引:1,他引:7
针对近年来我国城市规划教育在发展中的不足.借鉴英、美两国的经验, 认为我国城市规划教育在规划教育认证、规划院校准入、师资、职业认证、教研视野国际化、学生的社会服务和公共参与技能和学生的个性化培养等有改进的空间.对此,提出了5项建议,包括:①加强对城市规划教育的监管, 建立适当的规划院校准入标准:②建立全国性的城市规划教育基金:③改革现有规划教育体制, 满足不同雇主需求和增强个性化的教育体验:④建立跨校的教研同盟:⑤实现城市规划学术交流中的双向和多边交流.以强化我国的城市规划教育. 相似文献
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通过计量分析方法对近30年来住区环境设计预防犯罪领域的文献进行关键词共现分析、关键词时区分析以及关键词聚类分析等,总结了该领域在国内的研究进程及学科发展趋势。以CPTED理论为分析框架,简要梳理了该领域当前的研究方法、数据来源类型和研究发现,并结合现有城市居住区规划设计规范内容探讨其在犯罪环境预防方面的启示;在此基础上从数据来源、研究的地域性和案件类型的差异性以及研究成果的实践应用等方面对当前的研究进展进行剖析与反思。针对当前该领域实践与理论研究中存在的不足与瓶颈,对未来这一研究领域的发展和实践提出具体建议。 相似文献