棉秆切碎器的浮动夹持喂入机构设计

针对棉秆切碎收获机械介绍了一种新型带自调节、夹紧和主动输入功能的喂入机构。同时,对其结构组成、工作原理和关键部件参数设计分别进行了详述,并验算了最大通过量,分析了几种改变切碎长度的方法。实践表明,该机构还可适用于其它硬质冠状秸秆切碎前的强制喂入,具有结构简单、稳定性好、使用维修方便以及使用寿命长等特点。     

自吸式复合滚筒稻麦割前脱粒装置的设计

传统联合收获机的收获工艺大多是全喂入方式,采用先切割后脱粒,易造成堵塞、脱粒不净及谷粒难以分离等现象,使收获的工作效率受到一定限制,且存在机器体积大、制造成本高、功率消耗大等缺点。自吸式复合滚筒稻麦割前脱粒装置采用先脱粒后切割方式,在喂入口产生大气负压力,将稻麦穗头吸入脱粒装置内对吸入的穗头进行梳刷摘穗,摘下的穗头经过弓齿、钩齿与栅格式凹板筛进行2次梳刷与揉搓脱粒,同时穗头在随脱粒滚筒旋转时与脱粒滚筒筛表面纹理发生摩擦,进行辅助脱粒。     

便携式割灌机U型手柄的人机工程学优化研究

该文通过模拟实验,研究了便携式割灌机Ｕ型手柄人机几何界面参数对操作者主观施力的影响。人机几何界面参数包括:U型手柄宽度,操作者至左右握持点连线的垂直距离,握持点距操作者站台的高度3个参数。结果表明,手柄宽度、握持点距身体的前后距离以及握持点距站台的高度对水平横向操作力的影响都很显著。手柄宽度与身高具有很好的线性关系,相关系数为0.975。研究结果为U型手柄割灌机以及相关类型的机械设计提供了人机工程学设计依据。      

双向犁平地合墒器随动翻转机构的研究

为了在双向犁上配置合墒器解决耕耙复式作业,对双向犁及平地合墒器进行了分析,提出双向犁平地合墒器随动翻转机构,对随动翻转机构的主要设计参数进行了理论分析,论述了各参数之间的关系及选择原则。试验表明,该机构工作稳定可靠,具有良好的使用价值。     

新型无轴承无刷直流电动机结构与模型研究

目前研究的无轴承电机均是将电机和转子悬浮磁路合为一体,两个磁场的叠加一方面容易造成磁饱和,使电机的承载能力下降,影响电机的稳定悬浮;另一方面电磁转矩与径向悬浮力之间具有很强的非线性耦合,而实现解耦控制是非常复杂的。将无刷直流电机的优点与磁悬浮轴承的优点结合,提出一种六自由度可控的无轴承无刷直流电动机结构,通过研究其悬浮原理和运行原理,建立了转子偏心时的精确数学模型和PWM（脉宽调制）调速的精确数学模型,经仿真测试,表明了这种电机结构的合理性。主要特点是承载能力高且电磁转矩控制与径向悬浮力的控制相互独立,无需复杂的非线性解耦控制。     

Characterization of a carlavirus in elderberry (Sambucus spp.)

A carlavirus was isolated fromSambucus racemosa andS. nigra in the Netherlands. The virus was sap-transmissible and capable of infecting 14 out of 58 plant species and cultivars tested, causing symptoms in five of them. It was also transmitted byMyzus persicae at a low rate. Dilution end-point was 10^–3–10^–4, thermal inactivation at 70–75°C and ageing in vitro 2–4 days. The virus had a sedimentation coefficient of 155 S and molecular weight of capsid protein subunits of 31 000 dalton. The average buoyant density of the four isolates used was 1.315 g/cm³. The virus particles had an average normal length of 678 nm and a width of approximately 12 nm. In ultrathin sections of leaf tissue ofS. racemosa Plumosa Aurea bundles of virus particles were observed in the cytoplasm. Close serological relationship was found to a virus isolated from elderberry in Britain and a distant relationship to carnation latent virus. In its reaction on host plants and its persistence in crude sap it also resembled the former virus, originally code-named elderberry virus A. We propose the name elderberry carlavirus for it.Samenvatting Een carlavirus werd geïsoleerd uitSambucus racemosa enS. nigra in Nederland. Het virus kon met sap worden overgebracht en was in staat 14 van de 58 getoetste plantesoorten en-cultivars te infecteren waarbij op vijf van deze symptomen verschenen. Ook metMyzus persicae vond overdracht plaats, zij het in beperkte mate. De verdunningsgrens was 10^–3–10^–4, de inactiveringstemperatuur 70–75°C en de houdbaarheid in vitro 2–4 dagen. Het virus had een sedimentatiecoëfficiënt van 155 S en het molecuulgewicht van de structuurelementen van het capside-eiwit bedroeg 31 000 dalton. De deeltjes van de vier gebruikte isolaten hadden een gemiddelde zweefdichtheid van 1,315 g/cm³. De gemiddelde normale lengte van de virusdeeltjes bedroeg 678 nm bij een breedte van ongeveer 12 nm. In ultradunne coupes van bladweefsel vanS. racemosa Plumosa Aurea werden bundels draadvormige virusdeeltjes waargenomen in het cytoplasma. Het virus vertoonde een zeer sterke serologische verwantschap met een virus uit vlier geïsoleerd in Groot-Brittannië en een geringe verwantschap met het anjer-latenvirus. In zijn reactie op waardplanten en zijn eigenschappen in ruw sap vertoonde het ook veel gelijkenis met eerstgenoemd virus, in de literatuur vermeld onder de code-naam elderberry virus A. We stellen voor de naam carlavirus van vlier aan dit virus te geven.     

Broom snakeweed (Gutierrezia sarothrae) Population Change in Central New Mexico: Implications for Management and Control

This paper examines changes in broom snakeweed populations (Gutierrezia sarothrae [Pursh] Britt. & Rusby) from 1979 to 2014 at three prairie grassland sites in New Mexico. Data gathered each fall were used to study broom snakeweed population dynamics and to estimate the probability that the relatively short-lived subshrub will die off or invade blue grama (Bouteloua gracilis [H.B.K. Lag]) rangelands. Annual broom snakeweed standing crop data were used to categorize populations as None (< 100 kg ha^? 1), Light (< 300), Moderate (< 750), or Heavy (≥ 750). Ordered logit regression was then used to estimate the frequency of transition between these categories over time depending on environmental and site factors. Significant variables found to influence annual variation in broom snakeweed included the broom snakeweed standing crop and density observed the previous period (+ effect for continued broom snakeweed); grass standing crop the previous period (?); rainfall received from April to June (+); and average temperatures during April (+) and June (?). The probability of broom snakeweed invading an area that is currently without the plant ranges from about 1% to > 40% depending on environmental conditions and the amount of grass standing crop present. Transition probability estimates were also used in a Monte Carlo simulation model to evaluate the economics of broom snakeweed control. The economics of chemical broom snakeweed control were most strongly related to the rate of snakeweed reinvasion on treated areas and to the probability of natural die-off if infested areas were not sprayed.     

探析高职院校学籍管理系统开发与设计

高职院校是我国独立设置的高等职业技术学校,随着高职院校的发展,在校生占到全国普通高校在校生的一半多,实现学生的学籍信息的数字化、网络化管理已经迫在眉睫。     

条状刷式砂光机法向压力的测量与分析

为了研究条状刷式砂光机用于木制品异形部件砂光时,法向压力的变化规律,在不同理论接触长度、砂光条长度、砂光条偏转角度等条件下,对水曲柳试件进行砂光处理并测量法向压力.结果表明,砂光条施加到试件上的法向压力,随着理论接触长度、偏转角度的增大而增大,随着砂光条长度的增大而减小.用于异形面砂光时,适当增加砂光条的长度,可减小凹凸平面间法向压力的差值,增强条状刷式砂光机的形状适应性.     

利用“微创刷”法获得抗草甘膦转基因大豆

以发芽3 d的大豆成熟种子胚尖生长点为作用点,利用"微创刷"法将抗草甘膦基因(EPSPS)转入绥农22中,对转化植株T1代进行草甘膦筛选,对筛选后的抗性植株进行PCR检测,得到抗草甘膦转基因大豆。同时研究了不同浓度草甘膦对野生型绥农22与抗草甘膦转基因绥农22大豆植株的影响。结果表明:绥农22 T0代成株率为97.38%,对T1代具有草甘膦抗性的植株进行PCR检测,初步证明EPSPS基因成功转入大豆中,T1代转化效率为6.20%;对野生型绥农22与"微创刷"法获得的转基因绥农22大豆在不同浓度草甘膦进行相关生理指标测定,抗草甘膦转基因绥农22大豆在不同浓度草甘膦作用下叶片叶绿素含量指数、光合速率高于野生型绥农22大豆,莽草酸含量低于野生型绥农22大豆,进一步证明了大豆抗性植株对草甘膦的抗性。