Y型网式过滤器堵塞过程对有机肥浓度的响应研究

为研究水肥一体化设备中用于过滤有机肥的Y型网式过滤器的堵塞规律,对Y型网式过滤器在初始流量500 L/h、水源压力117.6 k Pa下,设置25、30、40、50 g/L共4种黄腐酸钾有机肥肥液质量浓度,进行了过滤器堵塞试验,分析了Y型网式过滤器的局部水头损失与单个滤孔滤网清洁度(单个滤孔有效过水断面面积与孔隙总面积比值) S/S0的关系,并利用XRD分析了过滤器内堵塞物质的成分。结果表明:肥液质量浓度对过滤器滤网清洁度影响显著,建议肥液质量浓度不超过40 g/L;过滤器局部水头损失在S/S0减小到10%后才逐渐开始增大,过滤器局部水头损失与滤网清洁度、肥液质量浓度有关,利用多项式拟合给出了过滤器滤网清洁度与肥液质量浓度、施肥持续时间的关系式及局部水头损失与肥液质量浓度、滤网清洁度的关系式;滤网堵塞物质主要成分为硫酸钙、草酸钙。本研究结果可为水肥一体化设备中过滤器的选择提供理论参考。     

饱和度及干密度对弱膨胀土土水特征曲线影响

采用滤纸法测量不同干密度下试样的总吸力与基质吸力,并绘制相应的土水特征曲线,分析饱和度与干密度对土水特征曲线的影响.实验结果表明:在饱和度一定时,总吸力与基质吸力均随干密度的增大而增大;随饱和度增大,不同干密度的总吸力差值和基质吸力差值逐渐减小;另外,试样的排水速率随饱和度的增大而减小,且干密度越大,排水速率越慢.在较低含水率时,试样的总吸力和基质吸力随干密度的增大而增大,随含水率的增大,干密度对总吸力和基质吸力的影响逐渐弱化.     

生物—电氧化法去除海水养殖循环水污染物

为提高海水养殖循环水处理效率,降低处理成本,本研究采用曝气生物滤器与电化学阳极氧化组合工艺,考察了不同阳极电势、进水氨氮和亚硝酸盐浓度下系统对氨氮及亚硝酸盐等污染物的去除效果,研究了微生物与工作电极之间的相互作用,并分析了电化学反应能耗。在水力停留时间为45 min、1.4 V阳极电压、进水氨氮和亚硝酸盐浓度分别为4.5和1.3 mg/L条件下,生物—电氧化法对氨氮去除率达88.8%,高出对照组7.6%,出水氨氮和亚硝酸盐浓度分别为0.5和0.9 mg/L,COD去除率为88.2%,高出对照组19.4%,平均能耗0.040 kWh/m~3,电极表面微生物生长对阳极电氧化过程有促进作用,微生物功能预测显示实验组硝化功能占比为0.03%,对照组为0.07%。研究表明,生物—电氧化法对海水养殖循环水的污染物有良好的去除效果,具有一定的发展应用潜力。     

森林保险制度体系重塑与运行机制优化

森林保险市场存在有效需求不足、创新供给乏力、地方政府参与积极性低的供需双冷局面,财政补贴政策低效运行。其根本原因是缺乏独立的适应其特殊性的森林保险制度体系作为保障,致使现有运行机制不协同,产品体系不科学,补贴机制不合理,导致市场发展缓慢。为此,通过林业风险与林业生产的属性特征分析,确定我国森林保险属性定位应是有政府支持的商业性森林保险,在此基础上围绕运行模式、产品体系、财政补贴体系建立相应的运行机制,从而构建一套独立综合的森林保险制度体系与运行机制,以改善供需双冷市场僵局,保障财政补贴政策有效发挥,推动森林保险健康持续发展。     

基于自适应滤波算法的树木年轮测量方法

为提高树木年轮测量仪的测量精度,提出了一种自适应低通滤波算法对年轮测量仪的直流电机电流信号进行滤波处理。普通低通滤波算法滤波系数固定,当树木年轮宽度发生变化时,既可能保留了部分噪声信号,又可能滤去部分有效的树木年轮信号,因此降低了年轮测量仪的测量精度。自适应低通滤波算法的滤波系数可随滤波器输入值和输出值的变化自动进行调整,提高了噪声滤除效果,减少了有效信号损失。使用自主研发的年轮测量仪测量了大、中、小3种径阶的60个落叶松圆盘,记录直流电机原始电流信号,分别采用自适应低通滤波算法和普通低通滤波算法对原始电流进行滤波处理,根据滤波后的电流波形图,预估圆盘年龄,并计算2种滤波算法的年轮识别正确率。结果表明,自适应低通滤波器年轮识别正确率的平均值为89. 66%,普通低通滤波器年轮识别正确率的平均值为75. 84%;当平均年轮宽度变窄时,自适应低通滤波器的年轮识别正确率从95. 61%下降到82. 02%,下降了13. 59个百分点,而普通低通滤波器的年轮识别正确率从86. 37%下降到62. 30%,下降了24. 07个百分点。表明自适应低通滤波器年轮识别正确率高,自适应能力强,年轮识别精度稳定。     

森林经理学的定位与发展

经理的释义不一定视为经营与管理的缩写,而应该是度量与筹划,森林经理学是森林度量与筹划的技术学科,应定位发展。     

Effects of polyline simplification of dynamic GPS data under forest canopy on area and perimeter estimations

The objectives of this study were to determine Global Positioning System (GPS) positional errors while moving under the forest canopy and to clarify the effects of polyline simplification on area and perimeter estimations. We used the Pathfinder Pro XR and GPSMAP 76S, which are categorized as “high-end mapping” and “general navigation” GPS receivers, respectively. The field tests were conducted in both natural and plantation forests. The results showed that the Pathfinder Pro XR, which has better multipath rejection technology, worked well, especially in the plantation forest under unfavorable conditions of higher stand density. We used analysis of variance to clarify the effects of the receiver type, positioning mode, stand type, and polyline simplification method on area and perimeter estimations. The receiver type and positioning mode were found to be significant factors that affected area estimation. The Pathfinder Pro XR estimated the area more accurately than the GPSMAP 76S, and differential GPS estimated the area more accurately than autonomous GPS. With respect to the perimeter, the receiver type, positioning mode, and polyline simplification method were found to be significant factors. The results showed that perimeter estimation was improved by using the velocity filter, and further improved by using the velocity filter and Douglas-Peucker algorithm, especially when the Pathfinder Pro XR was used. The GPSMAP 76S estimated the perimeter accurately without any filtering because its default speed filter worked well, even though the GPSMAP 76S is a general navigation GPS receiver.     

森林游憩开发中的盈利模式研究

森林游憩的深度开发 ,呼唤盈利模式的研究与运用。尝试提出森林游憩开发的技术路线 ,并对其开发的盈利模式进行探讨。     

Assessment of wood surface roughness: comparison of tactile roughness and three-dimensional parameters derived using a robust Gaussian regression filter

Japanese oak and Japanese beech were sanded by hand with abrasive papers of varying grit number. Two three-dimensional parameters selected to characterize their surface roughness – one parameter for the distribution of roughness-profile peaks and the other for the relative area of the roughness-profile peaks above the threshold height – were compared against tactile roughness. The parameters were obtained from roughness profiles as determined by a robust Gaussian regression filter (RGRF) using seven cutoffs. The RGRF filtering process was adjusted specifically for the evaluation of wood surface roughness. Except for a cutoff wavelength of 0.25mm, the RGRF lent itself well to the determination of roughness profiles. No distortion of roughness profiles occurred around deep valleys, and there was a good correlation between the parameters and tactile roughness.Part of this study was presented at the 2002 Kansai Branch Office lecture meeting of the Japan Society for Precision Engineering, Kyotanabe, August 2002