TSP问题的一种快速近似算法及应用

给出求解度约束最小生成树(DCMST)问题的一种快速近似算法．在此基础上．又给出求解TSP问题的一种快速近似算法,并在微机上实现且其数值试验的效果良好．最后,将求解TSP问题的近似快速算法作一些改进．应用于遗传算法的初始种群生成并进行数值实验．结果表明,用文中算法生成的初始种群．比起一般方法产生的初始种群性能有很大改进．该算法可以加速遗传算法的寻优速度．     

TM polarization characteristics on thermal radiation of a negative refractive index thin film

Thermal radiation TM polarization characteristics of a negative refractive index thin film was studied based on the transmit matrix method and Kirchhoff radiation law. The influence of the thin film parameters on the thermal radiation directional characteristics and spectral property were discussed. And the influence of the evanescent waves was also discussed. The results show that two factors play important roles in the thermal radiation of negative index thin film: one is the interference effect of the thin film structure to the electromagnetic waves; the other is the photon tunneling effect of the negative refractive index material, which was caused by the amplifying evanescent wave. These indicate that spectral and directional characteristics of the thermal emissivity can be modulated by modifying the structure and the physics parameters of the negative refraction index thin film. Supported by the National Natural Science Foundation of China (Grant No. 50606003) and Aeronautic Science Foundation of China (Grant No. 2007ZA51006)     

North China sub-craton lithospheric structure elucidated through coal mine blasting

We present a super-range seismic observation along the >1300-km-long profile passing through the Yinchuan basin and the Ordos block from the blasting point towards the southeast triggered by a large-(dynamite) scale coal blast in the Ningxia Hui Autonomous Region’s Helan Mountain (yielded a profile). The seismic wave information from the uppermost mantle reflecting different depths was obtained by the China continental seismic survey. Pn refracted waves from the uppermost mantle were effectively traced up t...     

流通量间断双曲守恒问题的推广WENO有限体格式

 针对流通量间断双曲守恒方程的数值求解,构造了将δ-映射与经典的WENO(weighted essentially non-oscillatory)五阶有限体方法结合的混合算法, 并用于求解具有混合介质的弹性波方程和流通量间断的多车种交通流模型方程.数值结果表明了算法的有效性.      

高瓦斯煤层深孔预裂爆破增透数值模拟试验

为了解决高瓦斯低透气性煤层的瓦斯抽放难题,利用数值模拟和现场测试相结合的方法,研究了深孔预裂爆破技术对高瓦斯低透气性煤层的卸压增透效果.研究结果再现了爆破过程中,动压冲击震裂、应力波传播与叠加及爆生气体驱动裂纹扩展的整个过程,分析了爆破孔间距对爆生裂纹和增透效果的影响,提出了高瓦斯低透气性煤层深孔预裂爆破的合理间距,表明深孔预裂爆破技术有效地提高了煤层透气性和瓦斯抽采率.该成果为高瓦斯低透气性煤层的瓦斯抽放提出了解决方案.     

优化组合行波故障测距技术及其在超高压电网中的应用

对现代D型双端和A型单端输电线路行波故障测距原理的准确性和可靠性进行了综合评价.在此基础上,提出了基于这两种行波原理的优化组合测距思想,并成功用于实际故障暂态行波分析.与单独的D型或A型行波测距方案相比,该方案能够利用A型行波原理对D型行波原理给出的测距结果进行验证和校正,提高了测距可靠性和准确性.实际应用表明,优化组合行波测距方案是可行的,并且测距性能得到明显提高.     

可编程定时计数器计数波形的实时观测与研究

应用查询或中断控制技术实时观测8253可编程定时计数器的各种计数波形,实验结果表明,8253计数器的计数频率可数倍于2．5MHZ,并且在计数模式3下的奇分频系数必须大于等于5才有效,本实验为提高8253计数器的使用效能提供了可靠的实验依据。     

带β项的非线性涡旋Rossby波的演变过程

利用多重尺度摄动法,推导出当考虑Rossby参数β作用时,非线性涡旋Rossby波的波包振幅的演化方程是非线性的Schrodinger方程．对受Rossby参数β影响的涡旋Rossby波的本征值问题进行分析,指出Rossby参数β对涡旋Rossby波传播的影响．     

Guided elastic waves in infinite free-clamped hollow cylinders

Guided elastic-wave-inspection technique for hollow cylinders has received plenty of attention in recent years because of its hieh effi-ciency ana tow cost.To apply guided elastic waves to detects detection,it is necessary to investigate the propagation of guided waves in the hollow cylinders under all kinds of boundary conditions.In this paper,the dispersion equations of torsional,longitudinal and flexural guided waves in the hollow cylinders with traction-free and clamped lateral boundaries are derived by elastodvnamic theory,based on wnicn the phase and group velocity dispersion curves of the guided waves mentioned above are obtained.And the dispersion properties of these waves are discussed in detail.The transient wave in a tree-clamped hollow cylinder is simulated by the finite element method(FEM).The time-frequency distribution of the transient wave agrees well with the theoretical group velocity dispersion curves.     

地下衬砌洞室群在平面SV波入射下的动应力分析

采用波函数展开法给出了半空间中衬砌洞室群在平面SV波入射下动应力集中问题的一个级数解析解,在满足一定的精度要求下,对无穷级数进行截断数值计算,衬砌分为刚性衬砌、无衬砌、柔性衬砌三种,计算结果表明:洞室问距对动应力集中系数具有重要影响,当洞室之间距离较近时,洞室之间的相互作用对地下洞室群的动应力集中具有显著的放大作用,动应力集中系数可能达到单个洞室的2倍以上;衬砌刚度对动应力集中问题也具有显著的影响,其中,刚性衬砌的动应力集中系数最大,无衬砌次之,柔性衬砌最小;随着入射波频率的增大,动应力集中系数的空间分布逐渐趋于复杂化.