模拟酸雨对三叶草种子萌发及幼苗生理指标的影响

[目的]为酸雨区三叶草作为地被植物管理提供科学依据。[方法]研究pH为2．5、3．0、3．5、4．0、4．5、6．5（清水）不同梯度酸雨胁迫对地被植物三叶草发芽势、发芽率及幼苗蛋白质含量、丙二醛（MDA）含量、脯氨酸含量和过氧化物酶（POD）活性等生理抗性指标的影响。蛋白质含量采用考马斯亮蓝G－250染色法测定,丙二醛含量采用硫代巴比妥酸（TBA）法测定,脯氨酸含量用酸性茚三酮显色法测定,POD活性采用比色法测定。[结果]在不同pH酸雨影响下,三叶草种子的发芽势、发芽率和幼苗的蛋白质含量随着pH的下降呈下降趋势;丙二醛（MDA）、脯氨酸含量和过氧化物酶（POD）活性随着pH的下降呈上升趋势。[结论]pH〈3．5的酸雨胁迫对三叶草种子萌发及幼苗生理指标影响明显。     

基于LSSVM和SA-BBO算法的循环水系统优化

火力发电厂循环水系统的优化对确定凝汽器最佳真空,以及提高火电厂整体效率、节能降耗,意义重大.以某电厂2台600 MW机组循环水系统为研究对象,建立了基于最小二乘支持向量机（LSSVM）的汽轮机功率预测模型.该模型解决了神经网络中的局部极小值问题,取得了很好的预测效果,泛化能力强.在此基础上,建立了以利润最大化为目标函数,综合考虑循环水泵功耗、汽轮机组功率微增以及煤、电能量价值市场差异的凝汽器真空优化模型.实际应用中,该模型计算时,首先以一定周期从实时数据库中读取电厂运行的最新工况信息,并进行数据预处理和稳态判别;再采用模拟退火生物地理学优化混合算法（SA-BBO）对凝汽器真空优化模型进行寻优,得出了不同工况下的凝汽器最佳真空、循环水泵的最优组合运行方式及优化收益.将寻优结果制成循环水系统的优化组合图,可以指导现场运行调节.     

硝酸盐污染地下水原位碳源注入生物修复优化方案研究

以北京某场地生活垃圾填埋场硝酸盐污染地下水为研究对象,针对原位生物修复技术,建立生物耦合Monod(RT3D)溶质运移模型。利用遗传算法(GA)和模拟退火法(SA)对地下水硝酸盐污染羽治理区开展了碳源(乙醇)注入备选井方案和原位生物修复系统进行模拟优化研究。优化结果表明,在满足硝酸盐氮浓度降低到10mg·L-1的目标下,GA和SA两种优化方案均优化确定相同的3口碳源注入井,比原设计节省15口井。100d后硝酸盐氮生物降解总量去除率分别为90.78%和84.51%。碳源注入井的布置方式呈三角点布置,且上游点的碳源注入量大于其他两点注入量。原位生物修复两种优化算法对比表明SA优化系统治理成本比GA节省1.46%,且收敛性强,波动性小,但计算时间较长。     

模拟降雨条件下坡度对石灰岩坡面土壤侵蚀的影响

[目的]揭示坡度对石灰岩坡面径流的影响。[方法]通过室内模拟降雨试验,研究了坡度对石灰岩坡面产流过程和侵蚀过程的影响。[结果]在5°～25°范围内,石灰岩坡面径流总量和动态径流量随坡度的增大而增大,临界坡度接近或大于25°。径流泥沙含量也随坡度的增大而增大,同一坡度下泥沙含量在产流初期迅速达到峰值,随后的20 min内持续下降直至稳定。径流系数、径流深随着坡度的增大而增大,呈现良好的线性关系。[结论]该研究为建立石灰岩土壤侵蚀预报模型和实现石灰岩区的综合治理提供理论依据。     

基于模拟退火和遗传算法的神经网络在精确施肥的研究

为了更加精确地描述农作物产量与土壤和施肥量中的N、P、K浓度之间的复杂的非线性关系,对原始的BP神经网络进行了改进。首先采用模拟退火算法对神经网络的初始权值和阈值进行优化,提高了网络的整体逼近性能,再用遗传算法对神经网络的权值和阈值进行改善,并对这两种方法的优化效果进行了比较,结果表明模拟退火和遗传算法的神经网络能产生很好的效果。     

Multifractal analysis of Hg pore size distributions in soils with contrasting structural stability

Parameters are needed to recognize and monitor changes in pore size distributions (PSD) caused by factors such as differences in soil management systems or by disturbance of the soil structure. The objectives of this work were to evaluate the potential of multifractal parameters obtained from mercury injection porosimetry (MIP) curves to distinguish between two soils with contrasting structure stability indices and between distinct stages of the surface of these soils. Samples were collected from the uppermost surface layer of two agricultural soils, before and after simulated rainfall. The first soil was loamy textured, with 4.61% organic matter content and a mean weight diameter (MWD) of 2.136 mm. The second soil was a silty loam with 2.17% organic matter content and a MWD of 0.262 mm, highly susceptible to crusting. Crusted soil surfaces were produced by cumulative 260 mm and 140 mm simulated rainfall on the loamy and the silty loam soil, respectively. Ten replicated samples from the initial freshly-tilled and the crusted soil surfaces were analyzed. In the diameter range of 100-0.005 μm, the freshly-tilled surface of the loamy soil had a significantly (p < 0.05) higher pore volume than its rain-disturbed counterpart, whereas the respective pore volume of the silty loam soil slightly increased following simulated rain. The scaling properties of PSDs measured by MIP could be fitted reasonably well with multifractal models. Generalized dimension spectrum, D_q, led to a better definition of multifractal scaling than singularity spectrum, f(α). Multifractal parameters such as Hölder exponent of order zero, α₀, aperture of the left part of the singularity spectrum (α₀ − α_q+), entropy dimension, D₁, correlation dimension, D₂, as well as indexes (D₀-D₁) and (D₀-D₂) were significantly different between the structurally stable loamy soil and the silty loam soil prone to crusting and between initial and rain-disturbed surface stages (p < 0.05). Moreover, D₁ and (D₀-D₁) were also significantly affected by the interaction between soil type and surface stage. Parameter α₀ ranked as: loam initial < loam rain-disturbed < silty loam initial < silty loam rain-disturbed, whereas the opposite rank was true for entropy dimension, D₁. Consequently, low structural stability or stability decay due to disaggregation by rainfall lead to clustering of PSDs measured by Hg intrusion porosimetry. These results show that multifractal analysis of PSDs may be an appropriate tool for characterizing soil structure stability and also a suitable indicator for assessing soil surface evolution stages.     

集配货一体化VRP问题的具记忆功能的模拟退火算法研究

针对集配货一体化车辆路径问题的特性,建立了考虑配送车辆出行固定成本、车辆出发满载系数等因素的更加符合实际的数学模型;并设计了一种带记忆功能的模拟退火算法求解模型,确保输出结果是每次寻优的最优解;最后通过算例计算,结果表明,算法求解更优,稳定性更好,计算效率也较高。     

土壤中酸可提取态重金属释放特征研究

采用模拟酸雨土柱淋洗实验,研究了不同土壤中酸可提取态重金属释放特征。结果表明,随着模拟酸雨pH值下降,土壤中酸可提取态重金属释放强度明显增大,各元素的释放量与酸雨pH值呈显著负相关。Zn释放主要集中在pH4.5～3.5之间;Cu释放主要集中在pH6.5～3.5之间;Cd的释放没有较集中的范围;而Cr和Pb,不同土壤集中释放的pH值范围不同。不同处理水平对酸可提取态种金属的释放有显著影响。     

模拟移动床技术在生化领域的应用研究进展

模拟移动床技术作为一种新型色谱分离技术,应用日益广泛。文章介绍了模拟移动床技术的发展情况及其工作原理,并详细介绍了模拟移动床技术在生化产品分离中的研究进展和应用情况。     

低温等离子体净化汽车尾气中NO的实验研究

研制了一套高压脉冲电源和介质阻挡放电反应器，通过在常压下放电产生低温等离子体。结合模拟汽车排气试验，对NO的去除率随放电管的放电电压、NO的初始浓度以及气体流量的改变而变化的规律进行研究。研究表明，利用介质阻挡放电产生低温等离子体净化尾气，是一种具有发展前景的排气后处理技术，对汽车尾气的净化具有明显的净化效果。