大功率拖拉机电液提升器比例提升阀设计

针对大功率拖拉机电液提升器,设计了比例提升阀,对4种不同型式节流口的流量特性进行了对比.基于状态空间法,建立比例提升阀的动态数学模型及仿真模型,在Matlab/Simulink中进行仿真及参数优化设计,并进行了室内试验.结果表明,采用半圆形节流口的阀芯行程短且具有良好的小流量特性;经参数优化之后,比例提升阀控制电流与流量曲线线性度决定系数为0.9986,动态阶跃响应超调量为6.25％,调整时间为0.3s.     

基于数据约束的植物叶柄三维形态交互建模方法

提出了一种基于真实数据并保持原始参数不变的植物叶柄器官建模方法。首先通过叶柄长度、叶柄半径参数建立柄的三维模型,并加入表面绒毛的模拟以增强真实感;为了丰富模型的形态,提出了基于交互的形态调整方法,该方法以关节链及逆向运动学为基础,辅以误差补偿算法,使交互调整过程中模型的原始参数(长度、半径)保持不变。试验结果表明,该方法可以快速、灵活地构建出叶柄器官的三维形态,具有较好的真实感效果,且变形过程中参数的变化很小。     

基于形状特征的大米虫蚀粒检测方法

虫蚀严重影响大米的品质。目前一般使用目测方法检测虫蚀粒,人为因素太多。为此,给出一种基于形状特征的检测方法。首先,对虫蚀米粒图像按Freeman链码方向提取边缘点坐标;然后,求这些相邻点坐标的向量夹角,对得到的夹角数据进行分析,分别求出其均值、方差、三阶矩和熵值等特征;最后,利用这些特征值,运用Fisher分类器识别出虫蚀粒。实验表明,大米虫蚀粒的正确识别率为95.65%。     

关键成员发展循环经济的模糊综合评价研究——基于集成农产品供应链

通过对关键成员发展循环经济评价因素的综合分析,建立了包括农产品质量、附加品增值效益、成本、客户反映、绿色绩效和创新能力等6个一级指标、17个二级指标的评价指标体系。以模糊理论为基础,采用层次分析法确定各指标权重,建立了双层模糊综合评价模型,并利用该方法对某集成农产品供应链关键成员发展循环经济能力进行了综合评价,得到的评价结果可以为政府找到合适的投资主体,并为政府投资或推进循环经济项目提供依据和指导。     

基于权马尔可夫链的宝鸡市年降水量状态预测

为了全面分析宝鸡市自然降水的时间分布规律和变化趋势,为该区域水资源预测、旱涝灾害防治、水量调度和水资源管理提供依据,对宝鸡市年降水量状态进行了权马尔可夫链分析。针对降水过程中的不确定和不精确性,采用均值-标准差分级法,将宝鸡市1956-2009年降水量分为干旱、偏旱、正常、偏涝、雨涝5个状态。以规范化的各阶自相关系数为权重,采用权马尔可夫链模型对宝鸡市未来年份的降水量状态进行预测。平稳分析结果表明,宝鸡市多年降水过程中干旱、偏旱、正常、偏涝、雨涝等5种状态出现的概率分别为0.1305、0.2767、0.2751、0.2075、0.1101。宝鸡市未来多年降水过程中偏旱和正常状态占优势,而雨涝出现概率较低,反映了该区域气候暖干化的长期变化。     

转基因植物重组DNA和表达蛋白的环境分子行为

转基因植物的安全性已经在全球范围内引起了普遍关注。本文从分子水平上就转基因植物的重组DNA在环境中的降解动态、转基因植物重组DNA在生物体内的传递、转基因植物杀虫蛋白在环境中的降解及在食物链间的传递等有关研究进展作一简要介绍。     

Differentiation of two powdery mildews of sunflower (<Emphasis Type="Italic">Helianthus annuus</Emphasis>) by a PCR-mediated method based on ITS sequences

Powdery mildew can be found in most sunflower fields during the winter season in Taiwan and causes severe yellowing on the blade, petiole, stem, and calyx, as well as serious defoliation. Two types of powdery mildew fungi isolated from sunflower leaves showed variable status for fibrosin bodies. But only the cleistothecium of Podosphaera xanthii, one of the pathogens causing this disease, was observed on samples from Chungpu County at the beginning of 2005. With a species-specific primer pair, PN23/PN34, no specific PCR product was amplified from the pathogen’s genomic DNA. Based upon the ITS sequence of rDNA, three PCR primer sets (S1/S2, G1/G2, and L1/L2) specific to P. xanthii, Golovinomyces cichoracearum and Leveillula taurica, respectively, were designed to detect and differentiate pathogens causing powdery mildews on sunflower. Only the primer pairs S1/S2 and G1/G2 could amplify PCR products, with product sizes of 454 and 391 bp, respectively. Four samples of fungal DNA were subjected to a multiplex PCR amplification with primer pairs S1/S2 and G1/G2; P. xanthii and G. cichoracearum were successfully detected. These results suggest that the multiplex PCR method is a rapid, simple, and effective technique to detect and differentiate powdery mildews, for example P. xanthii and G. cichoracearum, found on sunflower. With morphologic characteristics, ITS sequence analysis and pathogenicity testing, P. xanthii and G. cichoracearum, the first case, are two powdery mildews on sunflower in Taiwan.     

Internal fruit rot of netted melon caused by <Emphasis Type="Italic">Pantoea ananatis</Emphasis> (=<Emphasis Type="Italic">Erwinia ananas</Emphasis>) in Japan

An internal fruit rot with a malodor was found in netted melons (Cucumis melo L.) in commercial greenhouses in Kochi Prefecture, Japan, in 1998, despite their healthy appearance and lack of water-soaking or brown spots on the surface. A yellow bacterium was consistently isolated from the affected fruits. To confirm the pathogenicity of eight representative isolates of the yellow bacterium, we stub-inoculated ovaries (immature-fruits) 5–7 days after artificial pollination, with a pin smeared with bacteria. After the melon fruits had grown for 60 more days, an internal fruit rot resembling the natural infection appeared, and the inoculated bacterium was reisolated. The melon isolates had properties identical with Pantoea ananatis, such as gram-negative staining, facultative anaerobic growth, indole production, phenylalanine deaminase absence, and acid production from melibiose, sorbitol, glycerol, and inositol. Phylogenetic analysis based on 16S rDNA sequences showed that the melon bacterium positioned closely with known P. ananatis strains. The melon bacterium had indole acetic acid (IAA) biosynthesis genes (iaaM and iaaH) and a cytokinin biosynthesis gene (etz). The bacterium could be distinguished from the other ‘Pantoea’ group strains by rep-PCR genomic fingerprinting. From these results, the causal agent of internal fruit rot was identified as a strain of P.ananatis [Serrano in (Philipp J Sci 36:271–305, 1928); Mergaert et al. in (Int J Syst Bacteriol 43:162–173, 1993)]. The nucleotide sequence data reported are available in the DDBJ database under accessions AB297969, AB373739, AB373740, AB373741, AB373742, AB373743 and AB373744.     

Detection of Koi herpesvirus: impact of extraction method,primer set and DNA polymerase on the sensitivity of polymerase chain reaction examinations

Since virus isolation is seldom successful, KHV infection is commonly detected by PCR examination. A number of different PCR assays have been described in recent years. However, at present no commonly accepted PCR method is used amongst different laboratories. The aim of this study was to check if the examination of infected fish by different PCR methods yielded comparable results. We used tissue samples of three KHV‐infected koi, one KHV‐infected common carp, one KHV‐infected goldfish and one non‐infected common carp. DNA was extracted with DNAzol Reagent, High Pure PCR Template DNA Preparation Kit and QIAamp DNA Mini Kit. The DNA was tested by PCR with different combinations of published primer sets –KHV‐F and ‐R, KHV‐Gray‐2F and ‐2R and KHV‐TKf and ‐TKr – plus different DNA polymerases – a standard Taq DNA polymerase, a Platinum (hotstart) Taq DNA polymerase and a Platinum (hotstart) Pfx DNA polymerase with proofreading activity. The different extraction methods produced DNA solutions with different yields of DNA and different degrees of homogeneity. Also, the sensitivity of the PCR depended on the choice of the primer set and polymerase. Not all infected fish could be identified with all methods; there were large differences in the sensitivity between methods.     

蜂产品行业供应链管理优化初探

蜂产品行业在供应链管理中存在原料供应不稳定和食品安全等问题,这势必影响到行业的持续健康发展。在分析中国蜂产品行业供应链现状、特点的基础上,提出强化企业对原料生产的参与,强调供应链管理中食品安全的核心地位,提高供应链管理的信息化水平等方式优化供应链管理。优化现有供应链模式对促进我国蜂产业长期、稳定、高速发展,具有重要意义。