两种沉水植物对风浪及持续高水位胁迫的适应性研究

以两种沉水植物马来眼子菜(Potamogeton malainus)和狐尾藻(Myriophyllum spicatum)为研究对象,通过原位模拟试验,比较在相同水位变化幅度下不同高水位持续胁迫水平(分别以T0、T1、T2、T3表示恒静止、持续4 d、持续8 d和持续12 d)对沉水植物的生物量、植株伸长、具体形态指标和光合荧光特性的影响,并同步分析滆湖大洪港内两处风浪差异区(湖岸区M1和湖心区M2)两种沉水植物相应的适应性和形态变化的特征.结果表明,马来眼子菜和狐尾藻都表现出了较好的环境适应性,T0时任意两处的两种植物生物量和株高均最大;在风浪扰动较小区域(M2),持续高水位减弱了两种植物的伸长和生长(p0.01),并显著限制其在地上生物量的投资和茎干横向的分支(p0.05).在风浪扰动较大区域(M1),持续高水位对两种沉水植物产生了相同的形态变化,并显著降低各梯度下其Fv/Fm和快速光响应曲线(p0.05),但M1处两种沉水植物的光合能力均显著大于M2处.狐尾藻对风浪扰动和长时间水位胁迫能表现出更强抗弱光性和光合作用能力.因此,持续高水位胁迫下(小于8 d)两种沉水植物对一定程度水动力仍有较好的形态和生长适应性,对特定水文波动特征进行合理应对以保持沉水植物活力和维持湖泊生态系统具有指导作用.     

一种HSI空间基于模糊聚类的火灾彩色图像分割算法

针对通用模糊聚类算法进行彩色图像分割存在对初值敏感,迭代过程耗时等问题,在HSI空间结合火焰图像分布特征,采用平均值法进行初值优选,构造抑制算子和抑制因数对火焰无关区域S和I分量进行有效抑制,采用直方图聚类后进行数据融合等方式,最终实现彩色火灾图像分割。实验表明,该算法提高了彩色火灾图像分割的准确性和收敛速度。     

近48a宁夏寒潮的变化特征及可能影响的成因初步分析

利用1961—2008年宁夏日温度及逐月北半球500 hPa环流特征量、北极涛动指数(AOI)和NCAR/NCEP再分析资料,对宁夏寒潮频次变化的气候特征进行了分析,并对影响其变化的可能原因进行了讨论,结果表明:宁夏寒潮活动各地差异较大,主要出现在春季;近48年,春秋季寒潮频次呈弱增加趋势,冬季呈弱减少趋势;寒潮频次与AOI、气温呈负相关,与西伯利亚高压、东亚冬季风强度及入侵中国的冷空气活动频次呈正相关,相关关系在秋冬季明显,春季不明显;在气候变暖的大背景下,从20世纪80年代末开始,随着AOI从负位相转为正位相,冬季西伯利亚高压和东亚冬季风强度的减弱使得宁夏地表温度持续升高,是宁夏冬季寒潮频次减少的可能原因;春季也有类似的变化,不同的是:20世纪80年代中期以前,西伯利亚高压对寒潮活动作用更显著,之后,随气温持续增暖,冷空气活动对寒潮频次的影响更明显;秋季,西伯利亚高压和冷空气活动对寒潮的影响更直接明显。研究还发现,进入21世纪后,随着全球持续增暖,北极涛动对西伯利亚高压和东亚冬季风的影响有所减弱。因此,北极涛动、西伯利亚高压、冷空气活动频次、东亚冬季风、气温这几者之间的相互反馈作用是宁夏寒潮频次变化的可能原因。     

pH和铜离子对微囊藻毒素-LR荧光免疫检测的影响与消除

研究了pH和铜离子对倏逝波全光纤免疫传感器检测微囊藻毒素-LR（MC-LR）的影响及其消除措施.研究表明,过酸或过碱条件对MC-LR免疫检测均有较强烈的影响,当pH<6或pH>8时,系统检测的信号随pH的降低或增大明显下降;而当pH在6～8之间时,检测标准曲线的IC₅₀为1.01～1.04 μg/L,检测区间在0.12～10.5 μg/L之间,较适合MC-LR的检测.低浓度铜离子对MC-LR免疫检测的影响不大,当CuSO₄浓度>5 mg/Ｌ时,系统检测荧光信号明显下降,而当CuSO₄浓度达到10 mg/Ｌ时,系统检测信号下降70％以上.在预反应混合物中添加1%的螯合剂EDTA,能有效抑制铜离子对免疫检测的影响.     

关于用能量同化波浪作用下溢油乳化的研究思想和思考

介绍加拿大学者用能量概念解决化学实验室锥形瓶或烧杯,水动力学物理模拟实验室水槽以及自然界海岸线波浪破碎等不同尺度下波浪同溢油乳化行为之间关系的同化方法和针对某些特殊问题所采取的措施以及新的尝试.从物理模拟实验室尺度和自然界海岸线尺度提出一些思考问题,并从发展的角度和中国同加拿大研究设备、能力和观点上的差异,提出中国曾经开展的类似研究是否有再度崛起的可能性,使得研究成果成为溢油乳化和溢油清理科学技术的基础,并带动解决冻结水域溢油乳化现象的理论解释.     

绿化林带对交通噪声的衰减效果

为了研究公路绿化林带的降噪效果,对路侧林带降低实时交通噪声的效果进行定位测量,并将交通噪声人工编辑为不同频率的噪声,在远离交通噪音的林带中进行模拟试验,测定林带对不同频率噪声的衰减效果.结果表明：林带对交通噪声衰减有一定作用,其作用随能见度增大而降低;林带降噪效果随林带宽度增大而增大,可决系数为0.990,但在30m宽度内随林带宽度的增加,噪声的降低速率有所下降;不同林带类型的降噪效果有所不同,所选30m宽林带类型中,国槐纯林的降噪效果最佳可达15.38dB,而杨树、柳树纯林降噪效果较弱,分别为7.25、11.02dB;林带对中低频率噪声的平均衰减作用高于高频率噪声.     

Coupling effects of the explosion shock wave and heat radiation on the dynamic response of a fixed-roof tank

The occurrence of leakage in large tank farms or oil deposits can lead to fire or explosion accidents. Coupling effects of fire and explosion loadings can cause considerably more damage to adjacent tanks or buildings than either loading individually does. In this study, the combined loadings of the explosion shock wave and heat radiation from a pool fire on a neighboring empty fixed-roof tank were numerically investigated. The effects of the explosion shock wave intensity and relative height of the explosion center [the ratio of the height of the explosion center to the height of the tank (h_r)] were analyzed. The results indicate that tanks damaged by explosion shock waves have decreased fire resistance and critical buckling temperature. Moreover, the thermal buckling deformation of the predamaged tank largely depends on the explosion shock wave. With an increase in the explosion shock wave intensity or a decrease in h_r, the explosion shock wave has greater influence on the fire resistance of the tank, and the critical buckling temperature decreases. This paper can provide an understanding of the dynamics of a tank under explosion shock wave loading, and of the critical failure criterion and failure modes of a target tank under the coupled loading of the explosion shock wave and an adjacent pool fire.     

激波与森林作用的实验研究

利用激波与森林的作用,有可能成为森林灭火中的一项新技术,本文报告了激波与林带作用的实验模拟方法,实验技术与装备,测试和显示手段等基本技术环节。激波在林地,林带中的传播和衰减,以及其它物理现象由纹影方法作了显示。激波诱导的压力场也作了测量。研究表明,以激波管为基础的模拟技术是成功的,实验结果对于进一步认识激波与林冠火阵面的相互作用有很好的先导意义。     

Experimental study on pollutant movement in surf zone

The experiments on pollutant movement in surf zone were conducted on the two gentle beaches(with slope of 1:100 and 1:40, respectively), for diverse wave cases. The movement contours and direction of pollutants, under the action of regular and random waves with diverse wave amplitudes, were provided and studied in this paper. It was shown that, due to complicated hydrodynamics in surf zone, the pollutant movement state is quite complicated and different from that in pure current zone.     

Resistance of Villages to Elevated-Road Traffic Noise

The purpose of this study is to evaluate the methods of reducing elevated-road traffic-noise levels in rural residential areas by controlling the relative locations and morphological parameters and to investigate the effect of noise barriers on noise attenuation along elevated roads and building facades in villages. This study selected six morphological parameters and used noise-mapping techniques to estimate the noise attenuation in 60 village sites. The results indicate that ‘quiet areas’ increase by approximately 10% for each additional 100 m increase in the distance between the elevated road and the village. The best strategy for noise reduction is keeping the elevated road 1,000 m away from the village and raising the road height to 20 m. The building façade conditions only affect the traffic noise level attenuation when the buildings are within 100 m of the elevated road. It was found that the cost-effective length of the road noise barrier is 600 m on both sides of the village parallel to the road. The results highlight the importance of using morphology to improve the traffic noise resistance of villages. The landscape shape indices of buildings and roads are the most important parameters that affect the traffic noise attenuation of elevated roads.