排序方式： 共有124条查询结果，搜索用时 31 毫秒
31.
针对艇尾伴流场中大侧斜桨无空化水动力和水声性能的尺度效应问题,对几何相似但直径分别为250,500和1000mm的七叶大侧斜桨的无空化线谱噪声及其标准化谱曲线经验公式和总声压级进行了分析.噪声预报同时采用频域和时域计算2种方法.作为脉动噪声源的桨叶表面脉动压力和法向速度分布由URANS模拟得到.结果表明,在相同进速系数下3种尺度桨的0.7R截面压力系数分布重合度高;3个桨的推力脉动均能准确地反映出轴频和叶频信息,且中桨相对于小桨在叶频处的推力脉动幅值增量较大桨相对于中桨要大.2种噪声预报方法得到的大桨相对于小桨的总声级增量相差2.49dB;大桨和中桨标准化谱曲线较为一致,但与小桨差异明显.随着直径的增加,线谱谱级和总声级增量增加.建议应尽可能增大模型桨的几何尺度,以减小经验公式的预报误差和尺度效应影响. 相似文献
32.
分析了多次看目标的技术在跳水动作中的重要性及其能使动作稳定的作用,提出多次看目标训练的以下要点：1）看目标的训练一定要抓好;2）运用保护带练习多次看目标训练技术;3）陆水结合;4）保持系统的看目标训练;5）要作好检测工作。提出多次看目标的训练方法以供参考。 相似文献
33.
开放教育是以现代信息技术为传播媒介的数字化教育,是飞速发展的一种新型教育形式,是构建知识经济时代人的终身学习体系的主要手段。在开放教育的教学过程中,教师必须全面进行教学改革,探索以新的教学模式进行教学,教师的导学和学生的自主学习要有机结合。一方面要更新学生的学习观念,另一方面要培养他们在多媒体和网络环境中的高效学习方法和学习能力,使其行之有效地学习,从而提高自主学习能力和创新能力。通过提高对远程开放教育的认识,改变学习方式,体现开放特色,教师变“教”为“导”,为学生自主学习提供服务。 相似文献
34.
《Journal of The Franklin Institute》2019,356(9):4907-4927
In this paper, the distributed bearing-based formation control problem of networked thrust-propelled vehicles (TPVs) is addressed, in which both the constant and time-varying velocity leaders are considered, respectively. By introducing a reference acceleration and adaptive control scheme for the followers, the mass knowledge is not necessary in contrast to the existing works. Based on the designed reference accelerations, distributed adaptive control laws are proposed for the networked TPVs. Then the stabilization conditions are presented and an inner-bearing prescribed formation can be achieved. Under the proposed control laws, the leader-follower formation maneuver problem for networked TPVs with system uncertainties can be solved. Finally, simulation results are provided to demonstrate the effectiveness of the proposed control laws. 相似文献
35.
《Endeavour》1999,23(2):56-59
Herbert Spencer's evolutionary ideas related not just to the biological world but to the universe and everything in it. Human societies were also viewed through his evolutionary lens so that Spencer's evolutionary and political ideas are inextricably entwined. This essay looks at some of Spencer's ideas and attempts to locate them in the social and intellectual context of his youth. It also speculates on the rise and fall of Spencer's reputation. 相似文献
36.
分析了任职教育的生源特点和授课要求,提出了讲座式的授课方法,并进行了讲座的要素和特点分析。以《定量化管理方法》课程为例,介绍了不同授课内容的处理方式,包括绪论内容的讲座式处理、偏重于理论部分教学内容的讲座式处理、偏重于实践部分教学内容的讲座式处理等,最后对采用讲座式授课方式要注意的问题进行了归纳和总结。 相似文献
37.
从建构主义的理论视角出发,提出任务型研究生英语教学模式。在分析该教学模式的特点和实施步骤的基础上,以非英语专业研究生英语阅读课教学为例,探讨了该教学模式的可行性和优越性。 相似文献
38.
A fast integration method for translating-pulsating source Green’s function in Bessho form简 总被引：1，自引：0，他引：1
The singularities and oscillatory performance of translating-pulsating source Green＇s function in Bessho form were analyzed. Relative numerical integration methods such as Gaussian quadrature rule, variable substitution method （VSM）, and steepest descent integration method （SDIM） were used to evaluate this type of Green＇s function. For SDIM, the complex domain was restricted only on the 0-plane. Meanwhile, the integral along the real axis was computed by use of the VSM to avoid the complication of a numerical search of the steepest descent line. Furthermore, the steepest descent line was represented by the B-spline function. Based on this representation, a new self-compatible integration method corresponding to parametric t was established. The numerical method was validated through comparison with other existing results, and was shown to be efficient and reliable in the calculation of the velocity potentials for the 3D seakeeping and hydrodynamic performance of floating struc- tures moving in waves. 相似文献
39.
实验教学在人才培养中起着举足重轻的作用。改变以教员为主体的传统演示实验教学模式,将以学员为主体的新型研讨课模式融入到传统演示实验教学中,创建"教员主导、学员主体、师生互动、问题驱动、能力为主"的新型教学模式,更新教学理念,更好地把学员培养成为应用型、技能型人才,以满足现代化国防的需求。并以流体力学演示实验课为研究对象,对研讨课模式的演示实验教学改革进行了探索。 相似文献
40.
在PAT数组的基础上,引入LCP数组记录文本后缀串的相同前缀长度,通过扫描LCP数组快速抽取文本高频词。该算法不依赖于分词词典,通过探测重复出现串来提取高频词,并能够抽取任意重复字符串,对新词、组合词抽取特别有效。实验结果表明,该算法抽取的高频词可以达到较高的可接受率,在与ICTCLAS系统关键词抽取的比较中也有较高的相同率,且在发现组合词方面更具优势。 相似文献