基于改进BP神经网络的排种器充种性能预测

充种性能直接影响排种器排种质量,应用Matlab神经网络工具箱建立了排种器充种单粒率η1和空穴率η2的改进BP神经网络预测模型。选取转速n、种子当量直径d、充种角β和型孔直径D作为试验因素进行充种性能试验,获得64组单粒率和空穴率的试验结果。选取55组结果作为训练样本,采用Levenberg-Marquardt训练方法对建立的网络进行训练,并选取剩余的9组结果对训练好的网络进行仿真预测。其中,n、d、β和D为网络的输入层,η1和η2为网络的输出层,网络结构为含有单隐层的4-15-2型3层网络。预测结果表明：预测值与试验值有较好的一致性,利用改进BP神经网络对排种器充种性能进行预测是可行的,可为排种器的优化设计及工作参数的选择提供依据,从而减少试验时间和成本。     

Frequency shift domain iterative analysis for frequency estimation of equilong signals

From the view of trick recognition, features of signal decomposition structure in existing frequency estimation methods were analyzed, based on which, a frequency shift domain decomposition structure was proposed. A compound signal was constructed by combining several simple signals corresponding to different times. The given information in the time domain can be adopted to form an information accumulation effect, such that the interference frequency and noise can be suppressed effectively by decreasing the calculation. To match the use of a frequency shift domain decomposition structure, a frequency shift equilong iterative algorithm suitable for equilong signals was proposed. Simulated experiments were carried out in numerous application environments. The results show better noise immunity and real time performance as well as higher frequency estimation precision.     

Engine crankshaft static strength analysis based on the finite element method

Focusing on the fracture issue of single cylinder engine crankshafts, a three dimensional solid model was built in CATIA. Pre treatments, such as plotting grids, were carried out through Hypermesh, and finite element analysis was done using MSC. Patran/Nastran. The results show that the fatigue safety coefficient cannot meet demand when nodular iron is the crankshaft material. This finding verifies the theoretical possibility of crankshaft fracture. A crankshaft using 40Cr theoretically would not fracture because the fatigue safety coefficient could meet the demand. Simulation correctness was verified by a 400 hour engine reliability test.     

Wind tunnel tests and numerical simulation on arches’static wind loads of half through arch bridge

Long span half through arch bridges have the flexible space structure. Wind loads on the arches are usually the key factor to the whole bridge. Taking an example of the Chongqing Caiyuanba Yangzi River Bridge in P. R. China, wind tunnel tests of single arch and double arches section models were conducted. The results of a single arch in the smooth flow show that arch drag variability is small, and the lift and moment variability are significantly large. The results of double arches testing show that the static forces of the windward arch are similar to the single arch. The three force coefficients of leeward arches vary with the space width ratio and the angle between the two arches. Static forces testing was simulated by the CFD software FLUENT. The static forces from the testing and the simulation were compared. The results show that the values match quite well with testing, and the drag forces mainly varied with the space width ratio.     

Integrated control technology for methane in mining faces

Methane drainage is an effective technological approach to manage methane in an integrated fashion. Based the actual conditions of the 11031 mining face of the Zhongling coal mine in P. R. China, we divided the origin of methane into three categories: methane of the coal mining layer, methane of the adjacent coal layer, and methane in the goaf. Combining current techniques for managing methane in the mining face, we analyzed the effects of seven methods for draining the methane: through the coal layer borehole, the sector borehole, the cross borehole, the high level borehole, the large diameter borehole, the pipe buried in the goaf, and a special return airway. We suggest improvements for implementing integrated control in the three dimensional space by the control principle of dividing the sources. We provide references for other projects.     

Numerical simulation of outburst prevention air door destruction by coal and gas outbursts

We explore the destruction of outburst prevention air doors by coal and gas outbursts using numerical simulation. The reflective overpressure when an outburst acts on doors is elucidated, and its formula is obtained. The destruction of outburst prevention wind doors by coal and gas outburst are simulated using ANSYS software based on data of wind door pressure obtained by similarity simulation experiment. The simulation results show that the weakest place of gate posts is where the wind tube is. Simulation results also show the first shock wave pressure that acts on an outburst prevention wind door is not the maximum one. Due to the effect of reflected overpressure, the outburst prevention wind door pressure will reach the maximum in several milliseconds. This finding is similar to the experiment result.     

生态牧草筛选及其在生态果园应用的研究

总结了10年来福建省农业科学院与国外合作的红壤丘陵区适生草种研究和推广的主要成果，提出生态牧草的概念。阐述了筛选出的10余种优良牧草品种的特性、种植技术与模式以及推广应用的生态、经济和社会效益，生态果园模式与牧草套种技术及其应用效果，并分析了生态牧草在推广应用中存在的问题。     

水稻化感作用的生理生化特性研究

用化感水稻叶片浸提液处理不同萌发阶段的稗草幼苗，8d后测定受体稗草体内各种酶的活性结果表明，对地上部超氧化物岐化酶（SOD）的活性的最大抑制效应达27.7%，对地下部的最大抑制效应达38.4%；对地上部过氧化氢酶活性（CAT）的最大抑制效应达56.4%，对地下部的最大抑效应达62.4%。经分析，水稻的化感作用具有破坏受体植物膜的功能、影响其生长调节系统和破坏其光合作用等生理生化特性。     

福建牛姆林自然保护区天然林植物区系组成分析

对福建省牛姆林6个天然林样地的植物区系组成统计分析结果表明，牛姆林天然林的植物种类组成丰富，在2900m^2范围有248种高等植物分属82科153属，其中蕨类植物11科14属16种，裸子植物3科3属3种，被子植物71科136属229种，种子植物属的系数为61．69；区系地理成分较为复杂，属的地理成分以热带分布型为主，63．36％的热带地理成分及32．82％的温带地理成分显示出牛姆林地处南亚热带北缘的地理特点。     

江苏沿海地区土地整治项目成效综合评估

为了对江苏省沿海地区大量土地进行整治,针对沿海地区盐碱土改良增产效果进行量化以获取整治效果.以江苏省沿海地区的4个土地整治项目为例,从资金投入、过程管理、工程实施、综合效益4个方面选取了27个评价指标组成效益评价指标体系,用统计类比、专家咨询等方法构建了土地整治综合评估模型,得到综合效益评价值,提出了相应的建议和措施,为沿海地区土地整治成效的定量化评价提供了科学依据.结果表明:该研究区的4个土地整治项目实施的总体成效较为显著,大部分指标达到计划要求,具有显著的经济、社会和生态效益,但是各项目单项指标成效评估差距较大,土地整治项目综合评价还有较大的提升空间.评价结果为沿海地区在土地整治实践中有针对性地改进提供了依据和借鉴.