相思人工林土壤呼吸及残差呼吸的季节格局

采用红外气体分析(IRGA)法对平和天马国有林场3种相思人工林的土壤呼吸进行1 a的野外定位观测.结果表明,在3种相思人工林中,土壤呼吸的季节格局与土壤温度基本一致,呈明显的单峰曲线.卷荚相思林、黑木相思林和马占相思林土壤呼吸速率年平均值分别为3.51、2.73和3.36 μmol·m-2·s-1;土壤呼吸的Q,o值的...     

基于赤池信息准则和人工神经网络的亚热带森林郁闭度遥感估算

以江西省泰和县为研究区,探讨利用Landsat TM影像进行亚热带森林郁闭度森林遥感估算的可行性。首先,利用赤池信息准则(AIC)筛选了用于建模的遥感变量因子,通过模拟试验确定了估算森林郁闭度的前馈神经网络(BP)模型参数,利用检验样本数据验证了模型结果的可靠性。结果表明,遥感变量因子之间存在着强的相关关系,为了保证所建模型的效果需要剔除部分因子,利用BP神经网络建立的森林郁闭度模型的模拟和拟合精度都优于逐步回归模型,研究区内森林郁闭度较高,有47.8%的森林郁闭度大于0.7,但空间差异明显,西部和东部山区森林郁闭度高于中部丘陵森林的郁闭度。     

黄土丘陵区营造果园后土壤质量效应分析

 【目的】研究黄土丘陵区坡耕地营造果园后土壤质量变化过程。【方法】采用时空互代法,以黄土丘陵区不同年限的塌地果园为研究对象,选取坡耕地为对照,通过室内测试分析,并运用统计和相关分析等方法,研究土壤质量的变化过程。【结果】坡耕地改造为果园后,在改造初期土壤物理性质和抗蚀性变化不大或略有降低,随后显著改善并趋于稳定。土壤有机碳和全氮含量在改造前10年波动较大,增幅较慢,随后增长加速,15—30年基本趋于稳定;碱解氮含量在改造2年后增幅即达到显著水平,随后逐步升高。全磷和速效钾含量在初期显著降低,随后逐渐上升。速效磷在改造前10年变化不大,随后逐渐升高。pH随改造年限先升高后降低,CaCO3先降低后升高。微生物量碳、氮在改造前5年增幅显著,随后趋于稳定。微生物量磷在改造10年增加达到显著水平,随后逐渐增加。土壤基础呼吸强度在改造10年后显著增加,随后逐渐增加。诱导呼吸强度在改造5年后增幅达到显著水平,随后趋于稳定。代谢商在改造初期显著低于坡耕地,随后逐渐升高,15年后趋于稳定,和坡耕地没有显著差异。土壤脲酶、碱性磷酸酶、蔗糖酶和纤维素酶活性缓慢增加,在20—30年时趋于稳定。过氧化氢酶在改造第2年增幅即达到显著水平,随后随改造年限呈波动式缓慢上升。淀粉酶和多酚氧化酶活性整体随改造时间呈缓慢降低趋势,分别在10年和2年时达到显著水平,10—30年时趋于稳定。土壤质量指数（SOI）作为土壤理化和生物学性质的综合反映,在前20年土壤质量改善作用明显,20—30年趋于稳定,回归分析表明SQI随年限的增加呈显著的线性关系（r=0.946）。【结论】黄土丘陵区坡耕地由于严重的水土流失和不合理耕作方式,土壤物理、化学和生物学性质较差。改造为塌地果园初期,物理、化学和生物学性质显著改善,SQI增加,改造中后期,系统处于相对的稳定期,土壤物理、化学和生物学特性改善作用有所减缓,SQI趋于稳定。但此阶段却是以高投入高产出的状态在运转,系统仍旧受到较强的胁迫。     

伏马菌素B1单克隆抗体的制备及鉴定

 【目的】真菌毒素可导致严重的食品安全问题。本试验旨在制备可用于检测伏马菌素B1的特异性单克隆抗体。【方法】制备伏马菌素B1人工抗原,杂交瘤细胞法筛选杂交瘤细胞株制备腹水型单克隆抗体,并对其特性进行鉴定。【结果】筛选得到杂交瘤细胞株F3,分泌的单克隆抗体亚类为IgG1,轻链类型为κ链;10%变性聚丙烯酰胺凝胶电泳显示单抗蛋白重链分子质量约为50 kD,轻链分子质量约为25 kD;间接酶联免疫吸附法测定杂交瘤细胞F3细胞培养上清和腹水效价分别为1:3 200和1:51 200;亲和力常数为1.60×10-8 mol•L-1;IC50值可达3.589 ng•mL-1;对其它真菌毒素不存在交叉反应;免疫转印法鉴定抗体具有高特异性。【结论】本试验制备FB1单克隆抗体具有较好亲和力和高特异性,具有良好的应用价值。     

无线传感器网络改进质心算法的节点自定位

节点自定位是无线传感器网络的关键技术之一。在对距离无关的定位机制质心算法研究的基础上,采用极大似然估计法,估算信标节点与未知节点间的距离,以距离作约束降低误差值,从而提高定位的精度。通过MATLAB仿真。结果表明算法能够有效提高定位精度。     

粒子滤波在电子航标节点跟踪中的应用

提出一种高斯粒子滤波求解基于RSSI测距定位的无线传感器网络电子航标节点定位的非线性方程组算法.该算法在每次递推产生新的粒子时充分考虑了当前时刻的量测,使得该算法能很好地利用最新的量测信息.仿真结果表明该算法的节点估计均方误差在3 m以内.可见,它在解决非线性机动目标跟踪问题时有比较好的跟踪性能和滤波结果.     

黄河源区黑土滩垂穗披碱草人工草地土壤水分动态研究

对黄河源区不同龄垂穗披碱草人工草地及黑土滩退化草地土壤水分动态进行了研究。结果表明：各样地0～20cm土层土壤含水量具有明显的季节变化规律,变化趋势总体上为先增高,后降低。人工草地7月下旬土壤含水量达到最高,黑土滩退化草地8月下旬土壤含水量达到最高。各个时期0～20cm土层土壤含水量总体上为黑土滩退化草地〉2龄人工草地〉6龄人工草地。各时期0～20cm土层土壤水分垂直变化为人工草地随土层深度的增加而减小,黑土滩退化草地总体上随土层深度的增加而增大。     

Optimization of an artificial neural network topology using coupled response surface methodology and genetic algorithm for fluidized bed drying

In this study, an integrated response surface methodology (RSM) and genetic algorithm (GA) are recommended for developing artificial neural networks (ANNs) with great chances to be an optimal one. A multi-layer feed forward (MLFF) ANN was applied to correlate the outputs (energy and exergy) to the four exogenous inputs (drying time, drying air temperature, carrot cubes size, and bed depth). The RSM was used to build the relationship between the input parameters and output responses, and used as the fitness function to measure the fitness value of the GA approach. In the relationship building, five variables were used (number of neurons, momentum coefficient and step size in the hidden layer, number of epochs and number of training times). A polynomial model was developed from training results to mean square error (MSE) of 50 developed ANNs to generate 3D response surfaces and contour plots. Finally, GA was applied to find the optimal topology of ANN. The ANN topology had minimum MSE when the number of neurons in the hidden layer, momentum coefficient, step size, number of training epochs and training times were 28, 0.66, 0.35, 2877 and 3, respectively. The energy and exergy of carrot cubes during fluidized bed drying were predicted with R² values of greater than 0.97 using optimal ANN topology.     

The prediction of seedy grape drying rate using a neural network method

This paper presents an application which uses Feedforward Neural Networks (FNNs) to model the nonlinear behaviour of the drying of seedy grapes. First, a novel type of dryer for experimentally and mathematically evaluating the thin-layer drying kinetics of seedy grapes is developed. In the developed drying system, an expanded-surface solar air collector, a solar air collector with Phase-Change Material (PCM) and drying room with swirl element have been particularly included. Secondly, the drying rate is estimated as an exponential-type equation using non-linear regression analysis. Thirdly, the drying rate of seedy grapes is estimated using an FNN. Finally, the performance of the FNN model is compared with those of nonlinear and linear regression models by means of the root mean square errors, the mean absolute errors, and the correlation coefficient statistics. The results indicate that the FNN is more accurate and performed more consistently than alternative approaches employed in estimating drying rate.     

A novel methodology for the monitoring of the agricultural production process based on wireless sensor networks

Precision agriculture is a field which provides one of the most suitable scenarios for the deployment of wireless sensor networks (WSNs). The particular characteristics of agricultural environments - which may vary significantly with location - make WSNs a key technology able to provide accurate knowledge to farmers. This knowledge represents a valuable resource because it enables real-time decision making with regard to issues such as establishing water saving policies while providing adequate irrigation and choosing the right time to harvest the fruit based on its maturity.This article proposes a methodology consisting of a set of well-defined phases that cover the complete life cycle of WSN applications for agricultural monitoring. We have studied different existing real-world scenarios where WSNs are being applied. Based on this study we have discovered that there exist significant commonalities but no methodology that specifies the best practices that should be used in the general, crop-independent case. The lack of a general methodology negatively impacts the amount of effort, development time, and cost of developing applications.