水稻白叶枯病黄单胞菌中与甘蓝黑腐病黄单胞菌致病因子调控基因(rpf 基因)同源基因的分子克隆

DNA-DNA 杂交结果表明,水稻白叶枯病黄单胞菌总 DNA 中存在着与甘蓝黑腐病黄单胞菌致病因子调控基因(rpf 基因)具有同源性的 DNA 外段.应用广谱性寄主载体pLAFRI,在大肠杆菌中建立了水稻白叶枯病黄单胞菌野生型菌株 T3000的基因文库.从文库中筛选到与 rpf 基因具有同源性的克隆 pGXN3000,将重组质粒 pGXN3000通过三亲本接合转入甘蓝黑腐病黄单胞菌 rpf 基因突变体,发现 pGXN3000能互补甘蓝黑腐病黄单胞菌 rpf突变体,恢复其致病性胞外酶和胞外多糖的产生及致病性.转座子 Tn5诱变,缺失分析及DNA-DNA 杂交实验结果表明,重组质粒 pGXN3000中确实含有与甘蓝黑腐病黄单胞菌编码。双组份调控系统”蛋白的 rpfC 基因功能相同的基因,此基因被定位于 pGXN3000中的3kb BamHl 片段中。     

黄土坡面细沟侵蚀能力的水动力学试验研究

建立以水动力学为基础的侵蚀预报模型,必须解决影响土壤侵蚀发生过程及其强度的各水力要素的合理计算问题。本文通过室内径流冲刷试验,研究了黄土坡国沟侵蚀发生的水动力学机理及其输沙特征,探讨了细沟侵蚀预报模型中,细沟侵蚀民涉衣的土壤及有关径流的水力参数;土壤侵蚀性系数,细沟侵蚀发生的临界切应力,细沟径流的平均流速,Ｍａｎｎｎｉｎｇ糙率系数,以及反映细沟断面形态特征的系数的估算问题。     

二相流喷雾技术的研究

为了探索设施农业病虫害防治新的施药方法，该文对气液二相流喷雾作了雾化性能与药液物理特性相关性试验，得到了空气压强与气流量、喷雾量、雾滴直径、有效功率、吸液高度、喷口空气过流面积等诸参数之间相互关系，明确了药液粘性和表面张力对雾滴直径、喷雾量的影响程度，其结果为设计二相流喷头提供了依据。     

Factors contributing to guidance performance when using a camera-based guidance aid

A guidance aid is a device that provides guidance information to the driver rather than replacing the driver. With a camera-based guidance aid, the view seen by a forward-looking video camera is displayed on a monitor situated within the operator station of the vehicle. As the vehicle moves forward, images of the ground scroll vertically across the monitor. The rate at which the image scrolls, the image velocity, is related to the forward velocity of the vehicle, the placement of the camera (height and tilt angle), and the optical characteristics of the guidance camera. When tested with a tractor at forward velocities between 1.6 and 12.8 km/h, lateral error increased linearly as image velocity increased. Driver self-confidence decreased linearly as image velocity increased. Based on subjective feedback, drivers preferred a camera tilt angle of 20 degrees (over either 30 degrees or 40 degrees) because it yielded the greatest look-ahead distance. Statistically, a tilt angle of 30 degrees was best for a camera with a narrow field of view (narrow FOV, 20 degrees in the lateral direction). For a camera with a wide field of view (wide FOV, 39 degrees in the lateral direction), there was no statistical difference. For the narrow FOV camera, a camera height of 1.1 m yielded statistically smaller lateral errors than a camera height of 1.5 m. There was no statistical difference for the wide FOV camera. Overall, the lateral error was statistically smaller for the narrow FOV camera than for the wide FOV camera due to the difference in the lateral ratio for each camera, where the lateral ratio is the ratio of the lateral field of view of the camera to the fixed monitor width.     

中国城镇化过程中村庄土地整理潜力估算

该文在理论分析的基础上，创建了一个定量的数学模型来估算村庄土地整理净增加的潜力。估算结果表明，全国平均整理系数2010年为1.42～2.42、2030年为2.27～3.27，分别可净增加耕地面积173.81～296.58万hm²、279.10～401.86万hm²。通过对不同时间和不同生态区的整理系数比较，村庄土地整理潜力具有明显的时空分布规律。在时序上，随着社会经济的发展和城镇化水平的提高，我国农村人口会逐渐减少，整理潜力逐渐增大；在空间上，东部和中部村庄土地     

多项式插值法绘制发动机万有特性曲线

发动机万有特性可直观的反映发动机在其运行范围内的各项性能参数的变化情况。该文利用多项式插值法绘制发动机万有特性曲线。推导了三次多项式插值公式和三次多项式插值余项，绘制了发动机万有特性曲线。结果表明三次多项式插值法能精确地反映发动机特性，并可用该方法绘制发动机等油耗、等排放等特性曲线。为绘制发动机特性曲线、研究发动机性能提供较好的方法。     

Study on the supramolecular interaction of curcumin and beta-cyclodextrin by spectrophotometry and its analytical application

The supramolecular interaction of curcumin and beta-cyclodextrin (beta-CD) has been studied by spectrophotometry. The mechanism of the inclusion was studied and discussed based on the variations of pK(a), absorption intensity, and infrared spectrograms. The results show that beta-CD reacts with curcumin to form a 2:1 host-guest complex with an apparent formation constant of 5.53 x 10(5) mol(-2) x L2. Based on the enhancement of the absorbance of curcumin produced through complex formation, a spectrophotometric method for the determination of curcumin in bulk aqueous solution in the presence of beta-CD was developed. The linear relationship between the absorbance and curcumin concentration was obtained in the range of 0-15 microg/mL, with a correlation coefficient (r) of 0.9991. The detection limit was 0.076 microg/mL. The proposed method was used to determine the curcumin in curry and mustard with satisfactory results.     

基于遗传算法和神经网络的车辆主动悬架控制技

采用遗传算法与神经网络相结合的控制策略,以四自由度车辆主动悬架半车模型为仿真对象,与传统的被动悬架进行控制性能比较.通过改变神经网络训练参数、遗传算法输入函数以及车速,对系统的响应特性进行了分析.结果表明车辆主动悬架控制策略可以减小车辆的振动,改善车辆行驶平顺性.     

移动式绿篱修剪机设计

针对绿篱修剪机的发展现状,设计开发了一种小型自走式绿篱修剪机,包括动力系统设计和行走装置设计、修剪装置设计,并且利用三维建模软件建立了移动式绿篱修剪机的三维模型。所设计的移动式绿篱修剪机在所查阅的文献中尚未发现有相同机型的报道,属原创型产品。相比现在小型绿篱修剪机以手持式为主的状况,该绿篱修剪机能够有效降低绿篱修剪的劳动强度,提高修剪质量,有比较广阔的市场前景。     

柔性滚筒结构参数对水稻脱粒效果的影响试验

刚性脱粒冲击力较大,造成水稻籽粒破碎或破损.为了降低脱粒过程籽粒破碎或破损,设计了柔性脱粒滚筒,并对其开闭型式、脱粒齿直径、长度和迹距等结构参数进行了试验.单因素试验结果表明:脱粒齿直径、齿长对脱粒性能影响极显著,齿迹距对脱粒性能影响不显著,滚筒型式对脱粒性能影响有差异.正交试验结果表明:脱粒齿直径和齿长的交互作用对破碎率和未脱净率影响大,未脱净率低的较优组合是柔性齿直径为8mm,齿长为75mm,齿迹距为55mm的等齿迹距滚筒;破碎率小的较优组合是柔性齿直径为45mm,齿长为75mm,齿迹距为45mm的等齿迹距滚筒.