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。     

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。     

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.     

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     

Microtopographic structures facilitate plant recruitment across a saltmarsh tidal gradient

1. It is well known that establishment limitation is stronger than seed limitation in aquatic ecosystems. Therefore, it seems crucial during the recruitment recovery process to overcome this establishment limitation on bare or degraded patches.
2. Microtopographic structures have been shown to act as trap agents in saltmarshes. They can facilitate establishment, but this effect has not been quantitatively examined and assessed. This study examined the facilitative effect of microtopographic structures on plant recruitment in a dynamic saltmarsh system by conducting a series of field experiments along a saltmarsh tidal gradient.
3. A simple plant life‐cycle model was used to evaluate the dynamics of the plant recruitment process facilitated by microtopographic structure and the importance of each life stage. The influence of abiotic factors on each life stage was also assessed, to identify the determinants during the life history.
4. It was revealed that seed retention was the limiting factor in a bare saltmarsh area, rather than seed dispersal. Microtopographic structures can provide trap agents to facilitate seed anchorage. During seed retention, the stability of the microtopographic structure, especially its relative surface elevation difference, can be influenced by tidal events and the associated sediment process, which then affects seed retention efficiency.
5. Microtopographic structure has a strong environmental filtering effect that can revise the potential dispersed seed and emergence patterns, and the determinant of the final establishment pattern along a tidal gradient is the retention pattern resulting from the interactions between microtopographic structures and tidal events.
6. Furthermore, it can be designed into the early stage of recovery or restoration process so that it facilitates pioneer plant establishment. These early recruitment patches will speed up the recovery or succession process by (1) providing local seed sources, (2) retaining more seeds via the established vegetative structures, and (3) modifying microhabitat factors.

     

基于SPC563的DPF控制器底层软件开发

为了满足非道路柴油机国Ⅴ排放法规的要求,以意法半导体公司的SPC563芯片为控制器主芯片,开发用于柴油颗粒过滤器(diesel particulate filter,DPF)控制器的底层软件驱动程序,且AD转换功能、通信功能和掉电固化功能都采用模块化的底层软件开发模式。首先将脉冲宽度调制(pulse wide modulation,PWM)波生成函数封装为接口函数,然后将开发的控制器在发动机台架和整车进行试验。试验结果表明,本系统所开发的DPF控制器底层软件驱动程序能够精准控制DPF喷射阀的喷油量,满足国Ⅴ排放法规的要求。     

我国马铃薯价格波动规律研究--基于X-12和H-P滤波法的实证分析

马铃薯作为重要的农产品之一,其价格波动受多种因素影响。本文采用X-12模型和H-P滤波法,选取2005年1月至2015年12月全国农产品批发市场价格的月度数据,将其波动分解为季节性、周期性、趋势性和不规则性波动4种类型。结果显示,马铃薯生产的季节性是价格季节性波动的主要原因;成本上升及消费量增加推动价格趋势性上涨但总体趋于平缓;马铃薯价格呈明显的周期性波动,平均周期约为47个月;天气变化、市场突发事件等是价格不规则性波动的主要影响因素。对此,需扎实推进马铃薯生产稳定发展、健全全产业链信息分析预警机制、完善马铃薯价格保险制度,并推进马铃薯一二三产业融合发展,确保薯农收益稳定增长和市场供需基本平衡,促进市场平稳运行。