甘蓝型油菜引入我国历史较短,遗传基础狭窄,为了拓宽其遗传基础,前人对其开展了大量的远缘杂交研究.本文总结了甘蓝型油菜与其他芸薹属植物、十字花科植物远缘杂交研究利用进展.甘蓝型油菜种间杂交创制出早熟、黄籽、抗病等新材料,甘蓝型油菜属间杂交已导入抗旱性、抗寒性、乳白花等优良性状.甘蓝型油菜远缘杂交还选育出新的不育系、附加系、代换系.对甘蓝型油菜远缘杂交的发展方向进行了探讨.

本文以线上线下混合式"金课"建设为目标,以《工程流体力学》课程为例,探讨工科专业基础课程的线上线下混合教学模式,对在线课程建设、教学资源及线上线下教学实践进行了探讨,并与现代信息技术有效融合,设计和实施符合混合式教学过程及课程特点的评价考核机制,突出以学生为中心的课程理念,顺应时代发展和人才培养要求.

基于叶素动量理论对水平轴潮流能水轮机叶片外形进行设计,并结合Wilson方法修正计算模型,采用Matlab软件对叶片进行优化计算,得到优化后的弦长和扭角.通过坐标转换得到优化后翼型的三维坐标,将得到的坐标导入SolidWorks软件中建立叶片的三维模型.最后通过Fluent软件对设计的水轮机在不同尖速比下进行三维数值模拟.计算结果表明,设计的水轮机在水流速度为0.8 m/s,叶尖速比为3时,捕能系数能取得较大值,且水轮机无回流现象,具有良好的水动力特性.

[目的]筛选适合杂交油菜黔油早2号一次性施肥及撒播的缓释肥种类及经济用量,为该品种大面积轻简化栽培应用提供技术支撑.[方法]采用随机区组设计,以市售的5种缓释肥料及普通氮磷钾复混肥(CCF)为研究对象,设单施及混施等11个施肥处理,以空白施肥为对照,测定并分析各处理油菜在稻田和旱地环境下叶片叶绿素含量、生物产量及籽粒产量的差异,筛选最适缓释肥.另以油菜专用缓释复合肥为对照,设3个施肥水平进行最适缓释肥经济用量研究.[结果]随着生育进程的推进,稻田环境下,空白对照、宜施壮油菜专用缓释复合肥(YSZ)、沃夫特缓释掺控肥(WFT)和鲁西硫酸钾控失肥(LX)单施处理的叶片SPAD值呈先升后降的变化趋势,CCF单施及洲际核金刚有机无机控释缓释复合肥(HJG)+CCF、WFT+CCF、LX+CCF混施处理的叶片SPAD值逐步升高;旱地环境下,除HJG单施和WFT+CCF混施处理外,其余各处理叶片SPAD值均呈上升趋势;但两种环境下播种后60、90和120 d时,各处理的SPAD值差异均不显著(P>0.05,下同).各处理生物产量,地上部鲜重除旱地播种后60 d外,其他时期处理间差异均达显著水平(P<0.05,下同);地上部干重除稻田播种后90 d差异不显著外,其他时期处理间的差异均达显著水平;播种后90和120 d,不同处理间地下部鲜重差异显著,地下部干重差异均不显著.缓释肥及其施用方式在两种环境下对油菜产量影响显著.其中,稻田LX单施、WFT单施和HJG+CCF混施处理的产量较高,分别达3073.20、2863.05和2791.35 kg/ha;旱地LX+CCF、WFT+CCF和ZS+CCF混施处理的产量较高,分别达3890.25、3713.55和3525.15 kg/ha;综合两种环境,LX单施、WFT+CCF混施和WFT单施处理的产量较高.WFT在高和中等施肥水平下,黔油早2号产量均较同一水平下的其他缓释肥处理高,且环境变异度小.其中,在高施肥水平下,较对照YSZ处理增产150.15 kg/ha,增幅8.57％;较LX处理增产169.35 kg/ha,增幅9.77％.2016—2018年分别实施的2.67和37.33 ha一次性施肥撒播示范结果显示,WFT用量为750 kg/ha时,黔油早2号平均产量分别达2554.20和2350.20 kg/ha.[结论]在贵州省金沙县及具有相似气候及土壤条件的地区,黔油早2号一次性施肥撒播栽培最适合的缓释肥为沃夫特缓释掺控肥(N-P2O5-K2O=22-10-10),施用量约为767.10 kg/ha.

为了提高横轴水轮机发电装置能量利用率,采用CFD方法研究了水轮机外围导流罩的增速性能,比较了有、无导流罩情况下水轮机的流场特性.选取导流罩入口角度、出口角度、导流罩间距3个因素,每个因素选取4个水平,对16种方案下的横轴水轮机力矩系数及能量利用率进行对比分析.结果 表明,导流罩在一定程度上增大了来流的速度,水平段中心处速度可增大至原来的2倍左右;导流罩结构参数对横轴水轮机能量利用率影响的大小依次为:出口角度、间距、入口角度;其中导流罩出口角度和间距对能量利用率影响较为明显,而入口角度对其影响较小;当导流罩间距为1.4倍水轮机旋转直径时,其能量利用率达到最大.

以鲨鱼尾鳍、胸鳍与背鳍为对象,基于水动力数值仿真方法,研究3种不同流速条件下标本结构的压力场、速度场以及流场状态,给出力学性能分析与比较.结果表明为提高反卡门涡效应,尾翼的设置宽度可以参考设置为0.5～4.8 m;当仿生机器设备主要工作方向与水流方向是同一方向,在保证0.5～4.8 m的基础上,应将尾鳍宽度设计的相对窄;对于主要工作方向不在同一平面内的,则尾鳍宽度设计的相对宽;相同速度流场中的胸鳍所受力约等于背鳍的两倍,结构流线型弧度越好受到阻力越小.

The blade airfoil of water turbine is an important factor to affect hydrodynamic performance of blade.The types of blade airfoil and structure of existing power generation device has been summarized.The hydrodynamic performance of ten different types of blade airfoils was analyzed based on numerical simulation method,which includes the mechanical properties of resistance and lift force,surface pressure and velocity distribution.The lift force coefficient and resistance coefficient and their ratio of different blade airfoil were compared.A method was presented to optimize blade airfoils.Thus,it provides reference for improving the efficiency of power generation device and blade hydrodynamic analysis and optimization.

A circular particle settling in a confined vertical channel with static fluid is investigated by lattice Boltzmann method, the effect of density ratio on the particle motion and flow pattern is discussed. It shows that the particle starting from an initial position off-center displays various moving modes accompanied by different flow patterns for 1.003 ≤ γ ≤ 5.0: when γ < 1.1, the particle is finally in a stable equilibrium near the centerline and settles uniformly with a symmetrical flow, but there are different modes before reaching the centerline at different density ratios, a monotonic approach appears at γ ≤ 1.005 and an transient overshoot appears at 1.005 < γ < 1.1; When γ = 1.1, a weak oscillation appears in the particle moving but the flow is almost symmetrical, it is in a critical state of the particle moving from stable equilibrium with a transient overshoot to oscillation; When 1.1 < γ ≤ 3.0, the particle oscillates regularly around the centerline with the uniform amplitude and frequency, and it turns into irregularity for γ > 3.0. Meanwhile the rotation of the particle depends on the distance from a wall; it rolls up the closer wall and stops at centerline.

Based on the engineering practice of the experimental tea-ching courses in fluid mechanics as the object, in order to promote the teaching quality, the method of combining CFD simulation and test methods, process steps is presented with examples, in order to enhance students understanding of the course and application, and promote the cultivation of students' innovative ability.

Fluid mechanics series courses is the key characteristic foundation course of the ocean ,ocean engineering .In order to adapt to the professional requirements of multiple disciplines ,the construction of curriculum group is studied from perfect series curriculum group model ,enrich the content of the teaching materials ,optimizing teaching methods as well as build practice from several aspects ,such as the experimental platform .The series of curriculum construction and teaching innovation is carried out in order to promote students'knowledge , innovation ability and comprehensive quality coordinated .The effect is good for several years through the application practice .

The roughness effects of the gas flows of nitrogen and helium in microchannels with various relative roughnesses and different geometries are studied and analyzed by a lattice Boltzmann model. The shape of surface roughness is simulated to be square, sinusoidal, triangular, and fractal. Numerical computations compared with theoretical and experimental studies show that the roughness geometry is an important factor besides the relative roughness in the study of the effects of surface roughness. The fractal boundary presents a higher influence on the velocity field and the resistance coefficient than other regular boundaries at the same Knudsen number and relative roughness. In addition, the effects of rarefaction, compressibility, and roughness are strongly coupled, and the roughness effect should not be ignored in studying rarefaction and compressibility of the microchannel as the relative roughness increases.

The flow around two square cylinders arranged side by side has been investigated through lattice Boltzmann method under different Reynolds numbers and various space ratios (s = d/D, d is the separation distance between two cylinders, D is the characteristic length) from 1.0, 1.1 to 2.7, including 18 space ratios. It is found that the flip-flop regime occurs at small space ratios and the synchronized regime occurs at large space ratios. Wide and narrow wakes at small spacing are formed and intermittently change behind the cylinders, and the biased flow in the gap is bistable. The frequency of vortex shedding is different in two wakes. The upper frequency is smaller than the lower frequency for small space ratios (s < 1.4), and the time-averaged drag and lift coefficients of cylinders are also different. When the space ratios increase, two distinct vortex streets occur behind the cylinders, and the frequency of vortex shedding is almost equal in two wakes. Also the difference of time-averaged drag and lift coefficients of the cylinders decreases with the increase in space ratios; in this case the flow shows synchronized regime. The transition between flip-flop and synchronized regimes occurs at s = 1.5. When s < 1.5, the flow shows flip-flop regime; otherwise, it shows synchronized regime. When s = 2.0 and 2.5, the curves for the time-averaged drag and lift coefficient with different Reynolds numbers are smooth. When s = 1.5 and 1.8, the curves are also smooth under Re ≤ 140, but that will be fluctuant under Re > 140 because of the nonlinear interaction between the wakes, and the instability of flow becomes stronger with the increase in Reynolds numbers. On the other hand, the vortex shedding type from the cylinder occurs in-phase when s < 2.5 and s = 2.5 for Re < 190, whereas that occurs anti-phase when s = 2.5 for Re ≥190. In addition, the pressure varies a little on the left surfaces and greatly on the right surfaces of both cylinders with the increase in Reynolds number at s = 2.5.

The flow around two parallelized square cylinders is simulated by Lattice Boltzmann method with different spacing ratio S/D, 0.2、0.3、0.4、0.5、1.0、1.4、1.5、1.6、1.8、2.0、2.5, respectively. The streamline, the lift coefficient and the drag coefficient of square cylinders are presented, the pressures of midpoints at every square cylinder side are also provided. The results show that the gap flow between two cylinders is biased when s/D≤1.5, and there are periodic eddies behind two square cylinders; while s/D=1.5, the gap flow between two cylinders is symmetrical, and there are symmetrical eddies behind two square cylinders, respectively. Therefore, the spacing ratio s/D=1.5 gets the critical value determining biased flow or symmetrical flow.

The multi-bifurcation effect of blood flow is investigated by lattice Boltzmann method at Re = 200 with six different bifurcation angles α, which are 22.5°, 25°, 28°, 30°, 33°, 35°, respectively. The velocities and ratios of average velocity at various bifurcations are discussed. It is indicated that the maximum velocity at the section near the first divider increases and shifts towards the walls of branch with the increase of α. At the first bifurcation, the average horizontal velocities increase with the increase of α. The average horizontal velocities of outer branches at the secondary bifurcation decrease at 22.5° ⩽ α ⩽ 30° and increase at 30° ⩽ α ⩽ 35°, whereas those of inner branches at the secondary bifurcation have the opposite variation, as the same as the above variations of the ratios of average horizontal velocities at various bifurcations. The ratios of average vertical velocities of branch at first bifurcation to that of outer branches at the secondary bifurcation increase at 22.5° ⩽ α ⩽ 30° and decrease at 30° ⩽ α ⩽ 35°, whereas the ratios of average vertical velocities of branch at first bifurcation to that of inner branches at the secondary bifurcation always decrease.