车削用量的优化选择

本文对车削加工建立了切削用量优化选择的数学模型,并运用分层复合形法编制了优化程序,为利用计算机快速、可靠地选择使生产率最高或加工成本最低的最优车削用量提供了一个有效的方法。     

Active optical clock

This article presents the principles and techniques of active optical clock, a special laser combining the laser physics of one-atom laser, bad-cavity gas laser, super-cavity stabilized laser and optical atomic clock together. As a simple example, an active optical clock based on thermal strontium atomic beam shows a quantum-limited linewidth of 0.51 Hz, which is insensitive to laser cavity-length noise, and may surpass the recorded narrowest 6.7 Hz of Hg ion optical clock and 1.5 Hz of very recent optical lattice clock. The estimated 0.1 Hz one-second instability and 0.27 Hz uncertainty are limited only by the relativistic Doppler effect, and can be improved by cold atoms. Supported by the National Basic Research Program of China (Grant No. 2005CB724500) and National Natural Science Foundation of China (Grant No. 10874009     

自行车转弯问题的研究

自行车转弯问题是一个典型的原始物理问题.文章分析关于该过程的一个较精细模型,并计算转弯倾角,所得结果在考虑实物尺寸量级之后与传统的直杆模型结果相差很小.此类原始物理问题可以更好地训练学生思维能力,对大学物理教学具有重要的启示作用.     

车削零件的工艺分析

阐述阵削零件工艺分析的作用和内容，分析了影响加工零件工艺过程的各种因素，提出了在加工工艺规程的制订中，应充分发挥机床的使用率，达到节约材料，进一步提高经济性及技术性的效果。     

高阶转向点问题

证明了小参数问题εy″+f(x,ε)y′+g(x,ε)y=0,y(-a)=a(ε),y(b)=β(ε)解的存在唯一性和一致有效渐近展开,其中ε>0,f(0,0)=,f′(0,0)=…=f~(m-1)(0,0)=0,f~(m)(0,0)≠0,m是一大于2的奇数。     

大型飞机在较低等级机场滑行转弯性能研究

针对大型飞机在较低等级机场滑行道转弯运行受限的问题,基于飞机转弯性能,提出了一种转弯滑行道内侧边线半径和特定机型转弯半径关系的模型.该模型可以根据特定机型的转弯性能,在较低等级机场转弯滑行道内侧边线半径为确定值的情况下,计算出该机型转弯半径的取值范围.如果大型飞机转弯半径在该取值范围内,就可以在该机场滑行转弯.用A380飞机在某4E机场模拟转弯过程,验证了大型飞机在较低等级机场滑行转弯的可行性.     

An optical lattice clock

The precision measurement of time and frequency is a prerequisite not only for fundamental science but also for technologies that support broadband communication networks and navigation with global positioning systems (GPS). The SI second is currently realized by the microwave transition of Cs atoms with a fractional uncertainty of 10(-15) (ref. 1). Thanks to the optical frequency comb technique, which established a coherent link between optical and radio frequencies, optical clocks have attracted increasing interest as regards future atomic clocks with superior precision. To date, single trapped ions and ultracold neutral atoms in free fall have shown record high performance that is approaching that of the best Cs fountain clocks. Here we report a different approach, in which atoms trapped in an optical lattice serve as quantum references. The 'optical lattice clock' demonstrates a linewidth one order of magnitude narrower than that observed for neutral-atom optical clocks, and its stability is better than that of single-ion clocks. The transition frequency for the Sr lattice clock is 429,228,004,229,952(15) Hz, as determined by an optical frequency comb referenced to the SI second.     

椭圆车削装置及误差分析

本文设计了一种车削椭圆的新装置，并对其工作原理和加工误差进行了分析，给出了在不同长短半轴比下，椭圆轮廓最大相对误差值（maxΔr／b）．     

科学:在世纪的转折点上

２０世纪的科学技术发轫于１９世纪和２０世纪之交的物理学革命。百年前的世纪转折点 ,恰恰也是经典科学向现代科学的大转折时期。这是一个激动人心的年代 ,是物理学乃至整个科学发展的黄金时代。在新的世纪之交回顾一下上一个世纪之交的科学发展 ,无疑是适逢其时、别有教益的。１．２０世纪伊始 ,当百年庆典钟声的余音还在袅袅回响之时 ,英国皇家学会主席、科学界的泰斗开耳芬勋爵１９００年４月２７日在皇家学会发表了一篇著名的讲演 :“悬浮在热和光动力理论上的１９世纪的乌云”。他开门见山地说 :“动力学理论断言热和光都是运动的方式…