河南温县地下水高氟区内土壤中氟的现状评价

[目的]研究河南温县地下水高氟与土壤中氟的关系。[方法]选取土壤水溶性氟作为评价因子,运用单因子评价方法,对温县地下水高氟区内土壤中氟进行现状评价。[结果]土壤水溶性氟处于较高水平,属于轻度或中度污染,土壤水溶性氟与总氟的比值也极显著高于全国平均水平。[结论]土壤水溶性氟偏高是该县地下水高氟的重要原因。     

额济纳绿洲植被生态需水量空间分布

生态环境需水量是当前水资源管理等学科研究的重点和难点。以额济纳绿洲为例,采用GIS技术进行生态分区的基础上采用阿维里扬诺夫方法估算绿洲植被生态需水。结果表明:现状2009年绿洲植被最低生态需水总量为4.72262×108m3。从地区分布看,东河上段、东河中段、东河下段、西河、两湖区和中戈壁的植被生态需水分别占绿洲植被总需水量的8.8%、2.8%、34.3%、46.3%、6.8%、1.0%。要将植被恢复到20世纪80年代的规模,绿洲植被最低生态需水总量为7.12841×108m3。从地区分布看,东河上段、东河中段、东河下段、西河、两湖区和中戈壁的植被需水占绿洲植被总需水量的12.7%、4.5%、30.6%、39.6%、10.6%、2.0%。在现状流域水量分配方案下,平水年和枯水年都存在不同程度的缺水量。以上研究成果可为目前实施的生态水量调度提供技术支撑和参考。     

Impacts of soil erosion on organic carbon and nutrient dynamics in an alpine grassland soil

The impact of soil erosion on the nutrient dynamics in alpine grassland soils is still an essential problem. Selecting a grass-covered hillslope in eastern Tibet Plateau, the cesium-137 (¹³⁷Cs) technique was used to determine the impacts of soil erosion on soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), and total potassium (TK). The ¹³⁷Cs data revealed that there were distinct soil redistribution patterns in different hillslope positions because of the influences of slope runoff, plant coverage and grazing activity. For the upper slope, soil erosion first decreased downward, followed by soil deposition in its lower part. In contrast, for middle and toe slopes, there was an increasing soil erosion along a downslope transect. Across the lower slope, soil erosion showed an irregular variation. Influenced by the selective transport of water erosion, SOC, TN and TP storage decreased with increasing soil erosion in upper, middle and toe slopes. In contrast, SOC, TN and TP storage varied little with soil erosion in the lower slope. On the whole hillslope, TK storage also varied little with soil erosion due to the large amount of potassium elements derived from soil parent materials. Particularly noteworthy was the greatest storage of SOC, TN and TP in the lower slope where most obvious net soil erosion occurred, which is closely related to the humus accumulation combined with gravel separation as well as weathering and pedogenesis of parent rocks induced by soil freeze-thaw.     

窟野河流域径流变化及人类活动对其的影响率

利用王道恒塔、温家川2个水文站的实测降水、径流资料,应用M—K秩相关系数、R/S分析、降水—径流双累积曲线法等多种数值模型方法,分析了窟野河径流年际变化特征、径流变化趋势、降水变化以及人类活动对径流变化的影响。结果表明:(1)窟野河流域多年径流变化呈下降趋势,20世纪末以来尤为明显。(2)王道恒塔和温家川2个水文站的Hurst指数分别为0.853和0.803,表明未来一段时间内窟野河年径流变化趋势将与过去保持同一势态,有持续递减的特征。(3)不同历史阶段,人类活动的剧烈程度不同,对径流量减少的影响亦不同。影响最剧烈的阶段为1997—2010年,该阶段人类活动对径流减少的影响所占比例在2个水文站分别高达80.48%和93.62%。人类活动的加剧是导致窟野河径流量锐减的主要原因。     

基于改进方向纹理谱特征的图像检索

在定义图像局部邻域纹理方向特性的基础上,提出了一种新的方向纹理谱描述符。该描述符针对局部邻域内中心像素与其相对的邻域像素,既充分考虑了它们间的灰度变化关系,又考虑了它们间灰度差异的变化关系,从而更有效地描述了局部纹理特征。为证明新描述符的分辨能力,采用4种不同图像库进行图像检索对比实验,结果表明,本文的新纹理谱描述符取得了最好的检索效果。     

基于行驶状态反馈的电动助力转向(EPS)系统控制策略研究

利用卡尔曼滤波估计二自由度整车的行驶状态,仿真结果表明估计值和真实值吻合良好;在电动助力转向系统(EPS)基本助力电流基础上引入横摆角速度和质心侧偏角电流补偿,并且进行仿真分析,结果表明补偿后驾驶员路感得到改善,侧滑趋势得到抑制,汽车行驶稳定性得到提高。     

基于PRO/E的沙滩伞罩注塑模设计

分析了沙滩伞罩的结构特点,介绍了以Pro/E软件作为开发平台设计沙滩伞罩的过程,对模具进行了结构自动化设计,设计了分型面和成型零件等。     

基于嵌入式原理的轮胎气压监视系统设计

轮胎气压监视系统(TPMS)可以对轮胎胎内气压、温度提供预警,以保障行车安全。本文遵循轮胎气压监视系统(TPMS)对功耗以及可靠性的严格要求,基于嵌入式系统设计的基本原理,介绍了轮胎气压监视系统(TPMS)的设计与开发,主要包括监视模块、接收模块的软硬件设计。     

浅谈屋顶绿化技术推行的现状、问题及对策

指出了随着城市人口的密集度的增加以及人民生活水平的不断提高，人们对建设生态城市、绿色城市的要求也日益强烈，但由于技术、造价等多方原因，建筑屋顶绿化在我国推行的状况并不乐观。探讨了我国屋顶绿化主要面临的问题，包括技术不成熟、政策法规不健全、资金短缺、人们认可度较低等，从加强屋顶绿化技术的研究、完善国家政策和相关法规、加大资金投入力度、提高人们的认识水平等方面提出了相应的对策与建议。     

Effect of turgor on micromechanical and structural properties of apple tissue: A quantitative analysis

The effect of turgor on the micromechanical properties of apples (Malus domestica Borkh. cv Jonagored) and its relation to structural parameters of the cells was investigated. Mechanical measurements were carried out using a miniature tensile stage mounted under a microscope. Turgor was manipulated by soaking tissue samples in iso-, hypo- or hypertonic mannitol solutions. Samples were then subjected to tensile and compression tests, during which the deformation of the individual cells was recorded. In both tests, sigmoidal stress–strain curves were found, where stiffness increases with strain. With increasing turgor, strain at maximum stress became significantly (p < 0.05) lower while stiffness increased, but no clear effect on failure stress was found. As expected, fresh apples proved to be firmer and stiffer than stored apples, while the influence of turgor was the same. Measurement of initial cell parameters (area, length, width, aspect, roundness) showed that the apples in the experiment were homogeneous, having comparable cell sizes. Manipulation of turgor did not affect initial cell parameters, but the magnitude of cell deformations was clearly influenced. Larger deformations were found in flaccid cells. Changes in length and width were closely related to strain measurements. In conformity with micromechanical parameters, deformations were smaller in stored than in fresh apples.