基于改进型FCM算法的牛肉大理石花纹提取方法

提出了一种基于改进型模糊C均值聚类算法的牛肉大理石花纹提取方法。该方法结合了快速模糊C均值（FCM）聚类算法,对传统FCM算法中的隶属函数、聚类数C和初始聚类中心点选取方法进行了优化。试验表明,该方法使牛肉大理石花纹提取的准确度由     

Nitrous oxide emissions from animal urine as affected by season and a nitrification inhibitor dicyandiamide

Purpose  

Nitrous oxide emissions from pasture soils account for one third of total agricultural greenhouse gas emissions in New Zealand. The aim of this study was to determine nitrous oxide (N₂O) emissions from animal urine patches under summer (with irrigation) and winter conditions as affected by dicyandiamide (DCD) in grazed grassland in New Zealand.     

Post Plasma-Catalysis of Low Concentration VOC Over Alumina-Supported Silver Catalysts in a Surface/Packed-Bed Hybrid Discharge Reactor

In this study, the degradation of benzene by the means of an optimized surface/packed-bed hybrid discharge (SPBHD) plasma combined with γ-Al₂O₃-supported MO _x (M?=?Ag, Mn, Cu, or Fe) catalysts in post plasma-catalysis (PPC) system. The effects of Ag loading amount and gas hourly space velocity (GHSV) for plasma-catalysis degradation of benzene have been systematically investigated. The experimental result showed that the benzene degradation was improved and the mineralization process was greatly enhanced towards total oxidation after the combination of plasma with all MO _x /γ-Al₂O₃ catalysts. The AgO _x /γ-Al₂O₃ catalyst exhibited the best catalytic activity in benzene degradation than the other catalysts in PPC system. The highest benzene degradation efficiency of 96% and CO _x selectivity of 99% can be obtained for AgO _x /γ-Al₂O₃ catalyst with optimum Ag loading amount and GHSV of 15% and 22,856 h^?1, respectively. Time course of benzene degradation during PPC process indicated that the plasma-induced catalytic activity of AgO _x /γ-Al₂O₃ catalyst was temporary rather than lasting over a period after the plasma off. FT-IR analysis results revealed that the intermediate products (such as CO, HCOOH) and unwanted by-products (O₃ and NO _x ) generated in plasma process could be significantly inhibited by PPC process with AgO _x /γ-Al₂O₃ catalyst.     

Analysis of average standardized SSR allele size supports domestication of soybean along the Yellow River

Soybean (Glycine max) was domesticated in China from its wild progenitor G. soja. The geographic region of domestication is, however, not exactly known. Here we employed the directional evolution of SSR (microsatellite) repeats (which mutate preferentially into longer alleles) to analyze the domestication process and to infer the most ancestral soybean landraces. In this study, the average standardized SSR allele sizes across 42 SSR loci in 62 accessions of G. soja were determined, and compared with those in 1504 landraces of G. max, collected from all over China and representing the diversity in the gene bank. The standardized SSR allele size in the landraces (0.009) was significantly (P = 8.63 × 10^?58) larger than those in G. soja (?0.406). Pairwise comparisons between inferred clusters and sub-clusters of Chinese landraces indicated that the average standardized SSR allele size also increased with the further differentiation of landraces populations. Spring-sowed types had the shortest size, followed by summer-sown types, while the sub-cluster of autumn-sown type had the largest length. The spring-sowed landraces located near the middle region along the Yellow River had the smallest allele sizes, indicating that this is the most ancestral population of cultivated soybean. We concluded that soybean was most likely domesticated in the middle region of the Yellow River in central China, initially as a spring-sown type.     

小麦穗和芒表面积的估测

<正> 一、穗表面积的估测目前估测麦穗(不连芒)表面积方法中,一是公式(穗长×穗宽×3.8),二是 C.S.Saha 等的公式〔(穗基部第2结实小穗的长×宽)×2(小穗总量)〕。采用方格座标纸折算法测定麦穗的表面积,即分别在座标纸上逐一测定整穗全部小穗(包括退化小穗)的表面积,最后累计成整穗表面积。座标纸折算法虽费时,但较准     

沼肥中重金属对土壤和植物影响及控制技术研究

沼肥中的重金属主要来自于动物饲养中微量元素添加剂和农业种植中农药、化肥的过度使用.短期施用沼肥对土壤中的重金属含量没有显著影响,这里由于沼肥中有机物官能团和微生物对重金属的吸附净化作用降低了土壤中重金属的活性,减少了植物对重金属离子的吸收.为此,结合重金属的来源分析,从产前、产中、产后3方面阐述了减轻沼肥中重金属危害的措施及建议,并结合现代生物技术的新成果,对利用沼肥中微生物和有机官能团对重金属进行吸附净化做出展望.     

基于酶传感的农药浓度快速检测装置研究

基于酶传感对农药浓度进行检测,设计了以丝网印刷酶电极作为敏感元件、由SOC单片机和微电流测量电路组成的检测装置。通过与CHI660B型电化学工作站测量对比实验可知:该装置对微电流测量的精度达0.01uA,最大误差小于0.19uA,检出时间小于3min;装置尺寸小,适合于现场农药浓度的快速检测。     

基于DPSA传统分解聚合模型的并联泵站优化

针对多决策变量复杂非线性系统优化问题,引入基于DPSA的传统分解聚合模型进行并联泵站叶片全调节优化运行研究.首先将大系统分解为若干个子系统,采用DPSA法对各子系统进行优化;再以各子系统分配水量作为关联变量将各子系统回归方程进行聚合,并由聚合模型确定整个系统的最优解;最后通过关联变量将系统最优解反馈到各子系统,从而得到各子系统相应优化调度过程.通过在江都并联泵站叶片全调节优化中的应用,实现了系统总费用最小时的优化调度过程,确定了各站各时段开机台数及叶片角度的最优组合方案,表明了方法的可行性.同时以单位提水费用为指标,按考虑峰谷电价与不考虑两种情况,分析了江都站不同日均扬程、不同运行负荷下,叶片全调节相对定角恒速的优化运行效果,其中考虑峰谷电价节省费用较多,在满负荷、80%负荷6、0%负荷运行情况下,不同日均扬程单位费用节省率均值分别为7.52%2,2.19%,25.89%.     

不同鳃片间距下的分离鳃内部流场三维数值模拟

为研究鳃片间距对分离鳃的速度场及泥沙分布特性的影响,采用Fluent软件中的层流模型和欧拉模型,运用Phase Coupled SIMPLE(PC-SIMPLE)算法,对不同鳃片间距下分离鳃的水沙两相流流场进行了静水沉降的三维数值模拟。根据数值计算结果,对速度场和含沙量分布特性进行了对比与分析。结果表明:不同鳃片间距下,分离鳃内部的速度场分布规律有所不同,鳃片间距越大,速度流场受到来自泥沙通道中的泥沙流与清水通道中的清水流影响就越大;鳃片间距越小,分离鳃的沉淀效果越好。以泥沙平均速度和清水平均速度作为考核指标,同时考虑分离鳃内部的流场特性、水沙分离效果与制作分离鳃的成本,则最佳鳃片间距为5 cm。     

倾斜梯形孔式穴施肥排肥器设计与试验

为降低肥料施用量、提高肥料利用效率、实现植株根区施肥,设计了一种倾斜梯形孔式定量穴排肥器。阐述了穴排肥器的成穴与工作原理,分析了影响其成穴性能的主要因素,构建了充肥和排肥过程中肥料颗粒群的力学模型;应用离散元软件EDEM和流体分析软件Fluent对穴排肥器的成穴性能进行了仿真分析,研究了作业速度、充肥孔长度和气流速度对穴长、穴排肥量误差的影响,通过全因子试验得到作业速度为3~7km/h时的较优参数组合为充肥孔长度27.0mm、气流速度15.0m/s,对应的穴长和穴排肥量误差分别为62.7~87.5mm和7.4%~8.9%。台架试验表明,在作业速度为3~7km/h、充肥孔长度为27.0mm和气流速度为15.0m/s条件下,穴长、穴长稳定性变异系数、穴排肥量误差和穴距误差分别为98.5~175.5mm、7.42%~14.18%、7.60%~15.17%、2.3%~4.7%;田间试验表明,作业速度为3~7km/h时,穴长、穴长稳定性变异系数、穴排肥量误差和穴距误差分别为104.2~178.4mm、7.55%~14.56%、7.69%~13.80%、2.1%~4.3%,成穴性能较好。