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排序方式: 共有408条查询结果,搜索用时 140 毫秒
381.
介绍了火灾报警系统可靠性数字仿真原理和软件设计方法,并举出了运行实例,证明数字仿真技术在火灾报警系统可靠性分析方面具有良好的应用前景。 相似文献
382.
Zichao Lian Donglai Pan Wenchao Wang Dieqing Zhang Guisheng Li Hexing Li 《环境科学学报(英文版)》2017,29(10):108-113
A solar-light double illumination photoelectrocatalytic cell(SLDIPEC) was fabricated for autonomous CO_2 reduction and O_2 evolution with the aid of photosystem II(PS-II, an efficient light-driven water-oxidized enzyme from nature) and utilized in a photoanode solution. The proposed SLPEC system was composed of Cu foam as the photoanode and p-Si nanowires(Si-NW) as the photocathode. Under solar irradiation, it exhibited a super-photoelectrocatalytic performance for CO_2 conversion to methanol, with a high evolution rate(41.94 mmol/hr), owing to fast electron transfer from PS-II to Cu foam.Electrons were subsequently trapped by Si-NW through an external circuit via bias voltage(0.5 V), and a suitable conduction band potential of Si(-0.6 e V) allowed CO_2 to be easily reduced to CH_3 OH at the photocathode. The constructed Z-scheme between Cu foam and Si-NW can allow the SLDIPEC system to reduce CO_2(8.03 mmol/hr) in the absence of bias voltage. This approach makes full use of the energy band mismatch of the photoanode and photocathode to design a highly efficient device for solving environmental issues and producing clean energy. 相似文献
383.
火星滑坡研究对地球上高速远程滑坡形成机制具有借鉴意义,其中火星滑坡体体积的计算是调查难点之一。基于NASA火星侦查轨道器背景摄影技术,借助谷歌地球软件,对火星水手谷中的12处典型滑坡进行了识别与分析。运用Alfred S.McEwen公式和方格网两种方法,计算了火星滑坡体的体积V,得出火星水手谷中12处典型滑坡体的体积平均在1 500km3,最高可达5 452.4km3。采用数理统计理论,发现滑坡体体积V与堆积区域面积D满足V=103.046 D1.036,滑坡体高度H与滑移距离L之比(等效摩擦系数)与滑坡体体积V满足H/L=-0.029lgV+0.459的关系。分析滑坡体滑移距离L的影响因素,得出滑坡体滑移距离L与滑坡体体积V和滑坡体高度H基本呈正相关。将火星滑坡体体积计算结果与地球上217处滑坡统计数据进行对比,发现火星滑坡具有体积大、滑移距离远、低等效摩擦系数等特点。 相似文献
384.
385.
386.
以行政区划为计划单元,结合当地的社会经济发展现状及规划,对象山港海域污染物排放进行总量控制和排放指标额度优化分配,使得象山港海域污染物总量控制研究更具可操作性.研究结果表明,在COD各源强中,水土流失源、畜禽养殖源保持不变,生活源和工业源按一定比例增长,只有奉化、宁海区域海水养殖源需要削减,且削减后的COD源强(容量分配额度)亦能满足该区域今后海水养殖发展的需求,而北仑、鄞州和象山其他3个区域的海水养殖容量分配值则有较大的剩余空间,故在不超过总源强(海水养殖未使用全部源强)的前提下,工业、生活等COD源强可在优化结果的基础上适度增加,从而实现象山港及其周边陆域资源、环境和经济目标的最大化. 相似文献
387.
388.
To explore biodegradation of 2-naphthol and its metabolites accumulated in wastewater treatment, a series of bio-degradation
experiments were conducted. Two main metabolites of 2-naphthol, 1,2-naphthalene-diol and 1,2-naphthoquinone, were identified by
high-performance liquid chromatography with standards. Combining fungus Aspergillus niger with bacterium Bacillus subtilis in the
treatment enhanced 2-naphthol degradation e ciency, lowered the accumulation of the two toxic metabolites. There were two main
phases during the degradation process by the kinetic analysis: 2-naphthol was first partly degraded by the fungus, producing labile
and easily accumulated metabolites, and then the metabolites were mainly degraded by the bacterium, attested by the degradation
processes of 1,2-naphthalene-diol and 1,2-naphthoquinone as sole source of carbon and energy. Sodium succinate, as a co-metabolic
substrate, was the most suitable compound for the continuous degradation. The optimum concentration of 2-naphthol was 50 mg/L.
The overall 2-naphthol degradation rate was 92%, and the CODCr removal rate was 80% on day 10. These results indicated that
high degradation rate of 2-naphthol should not be considered as the sole desirable criterion for the bioremediation of 2-naphtholcontaminated
soils/wastewater. 相似文献
389.
氯代苯化合物的毒性分析 总被引:2,自引:0,他引:2
文章对氯代苯化合物的性质作了系统的论述,并对其毒性进行了研究。通过对氯代苯化合物辛醇——水分配系数的估算分析了氯代苯化合物的毒性与取代基数目的关系,利用二氯代苯对冬小麦、油菜的致死浓度和半致死浓度分析了其毒性与取代基位置的关系。结果表明,氯代苯的毒性随苯环上氢原子被氯原子取代个数的增加而加大。在苯环上氢原子被取代的个数相同时,毒性与氢原子被取代的位置有关,邻位最大,间位次之,对位最小。最后就氯代苯化合物对水生生物、高等动物以及人体的毒性进行了重点分析。 相似文献
390.
The activities of CeO2 nanocubes calcined at di erent temperatures were tested for catalytic oxidation of o-xylene. Using
CeO2 nanocubes as catalysts, complete catalytic oxidation of o-xylene was achieved below 210°C. The CeO2 nanomaterials were
characterized by means of BET, X-ray di raction (XRD), transmission electron microscopy (TEM), and high-resolution transmission
electron microscopy (HRTEM). From the TEM images, all CeO2 nanocubes displayed cubic morphology irrespective of calcination
temperature. The HRTEM images revealed that these nanocubes were enclosed by reactive f001g planes, which may contribute to the
intrinsically catalytic property of o-xylene oxidation. The higher activity of CeO2 nanocubes calcined at 550°C than those calcined
at above 550°C was attributed to their smaller crystallite size and larger surface area. The influences of reaction conditions were also
studied, which found that a higher reaction temperature was necessary for complete catalytic oxidation of o-xylene at higher weight
hourly space velocity (WHSV) and o-xylene concentration. 相似文献