轴流泵叶片的水动力性能研究

根据叶片绕流理论,用保角变换和级数展开的方法推导出由变换系数表示的叶片表面的速度分布,给出了轴流泵可调叶片的水动力矩数学模型及可靠性分析。最后,对某泵可调叶片的水动力矩进行了计算。研究表明,方法是可靠的,结果令人满意。     

Distribution Regularity of Muzzle Shock-Wave Inside Protective Cover

The injury of gunners caused by muzzle shock-wave has always been a great problem when firing inside the protective cover. The distribution regularity and personnel injury from the muzzle blast-wave were investigated by both test and numerical simulation. Through the inside firing test, the changes of overpressure and noise have been measured at different measuring points in the thin-wall cover structure with different open widths and shallow covering thickness. The distribution regularity of muzzle shock-wave with different firing port widths is calculated by ANSYS/LSDYNA software. The overpressure distribution curves of muzzle shock-wave inside the structure can be obtained by comparing the test results with the numerical results. Then, the influence of open width and shallow covering thickness is proposed to give a reference to the protective design under the condition of the inside firing with the same cannon caliber.     

滚翻垫球后“再后倒”现象的讨论

对滚翻垫球后“再后倒”现象进行理论分析 ,可找出出现问题的根源 ,以便在教学中解决这一问题     

论刚体对坐标轴转动惯量的平移和旋转变换

本文导出了刚体对坐标轴的转动惯量的平移和旋转变换一般式。     

Dependence of nucleotide physical properties on their placement in codons and determinative degree

INTRODUCTION It is well-known from the genetic code structure that there exists a connection between codons and physical and chemical amino acid properties (Lewin, 1983). Codon properties in turn are defined by physical properties of the nucleotides from which they are compounded (Ratner, 1985; 2000). The most important properties of nucleotides as complex three-dimensional molecules are their dipole moment, heat of formation and energy of the most stable con- formation (Schneider and Be…     

Estimates of Central Moments for One Kind of Exponential-Type Operators

In this paper,the explicit estimates of central moments for one kind of exponential-type operators are derived.The estimates play an essential role in studying the explicit approximation properties of this family of operators.Using the proposed method,the results of Ditzian and Totik in 1987,Guo and Qi in 2007,and Mahmudov in 2010 can be improved respectively.     

运用内力图规律快速绘制剪力图和弯矩图

根据荷载集度与剪力、弯矩之间的导数关系,找出了绘制内力图的规律,应用此规律画剪力图和弯矩图不必列内力方程,只需依据梁在不同荷载作用下剪力图及弯矩图的图形特征计算出控制截面的内力值,即能简便、快捷地画出内力图。     

二项分布中p~2的矩估计与极大似然估计

基于二项分布B(n,p)总体,给出了未知参数p2的矩估计和极大似然估计,并讨论了估计量的无偏性。     

比较“精神顿悟”和“重要瞬间”的写作技巧

以乔伊斯的《一片浮云》和伍尔夫的《墙上的斑点》为例,分析了“精神顿悟”和“重要瞬间”写作技巧上的相似处和不同点。指出两者皆由外界事物引发,反映人物的心理瞬间,促成人物的顿悟和意识的流动。其不同点在于“精神顿悟”是故事循序渐进过程的必然产物,重在揭示社会背景,而“重要瞬间”与故事情节和人物刻画无关,重在抒发个人的人生瞬间感悟。     

优秀双向飞碟运动员3号 靶位击发节奏与脱靶关系研究

双向飞碟射击项目中3号靶位是8个靶位中射击命中难度最大的靶位,是制约运动员整体命中率的关键所在。将双向飞碟双靶分为1靶击发、随靶、2靶击发3个阶段,对3名国内优秀运动员击发节奏特征进行分析。发现：①1靶击发阶段的节奏直接影响2靶中靶情况,1靶击发用时越长,2靶质量越差,想要提高2靶的命中率必须要提高1靶的动作质量。②随靶阶段的人枪结合能力会影响2靶命中率。③优秀运动员2靶击发阶段的时间节奏一致性较强,动作自动化程度较高。④整体击发节奏慢更易造成2靶脱靶。提出,运动员要提高打好1靶的能力,在保证1靶质量的前提下加强快打技术训练,同时提高随靶阶段人枪结合能力,加强对技术的监控和分析,辅助运动训练,科学提高成绩。