4 . with the consideration of practical soil - pile interaction , the soil around pile is modeled as a three - dimensional viscous - elastic continuous medium and the time effect of the settlement of single pile is studied . the semi - analytical solutions for vertical displacement of soil and for the relationship between settlement of pile head and time were obtained by laplace transform method and fourier inverse method , and the law of the settlement of pile head varying with time was then analyzed and discussed 考虑桩土藕合作用的单桩沉降时间效应研究从研究空间轴对称问题的角度出发,将桩周土体建模为三维粘弹性连续介质,更为合理地考虑了静荷载下桩土系统中单桩与桩周土的藕合作用,分别建立了桩周土体和桩体的静力平衡方程,并通过拉普拉斯变换、傅立叶逆变换等数学手段,获得了单桩桩周土体的垂直变形和桩顶沉降在拉普拉斯变换域内的解析解和在时间域内的半解析解,进而分析讨论了单桩沉降随时间变化的规律。
And the rock mass as the main object of most engineering practice is developed by all kinds of geotechnical action and force in the long geology history to the complex characteristic of continuous medium , crannied medium and granular medium , to the anisotropic and heterogeneous entity with elasticity , plasticity , viscidity , creepocity and rheology 作为主要工程对象的岩体是在漫长的地质历史发展过程中经受各种地质营力作用而形成的成因和构造复杂,岩性多样且包含了连续介质,裂隙介质和散体介质特征的,兼有弹性、塑性、粘性、流变性的各向异性的非均质地质体。
While wells are producing , heat transfer in welibore is considered as heat conduction and convection in continuous media in vertical tube , heat transfer in production zones is considered as heat conduction and convection in porous media , heat transfer in adjacent rocks is considered as heat conduction in porous media . while wells stop producing , because of stopping flowing in welibore and production zones , heat transfer in welibore is considered as heat conduction in continuous media in vertical tube , and heat transfer in formation is considered as heat conduction in porous media 当油井生产时,将井筒内传热看成竖直圆管中连续介质的传导和对流换热,将地层中产层部分的传热看成多孔介质中的传导和对流换热,将地层中围岩部分的传热看成多孔介质中的热传导;当油井停产时,由于井筒和产层都没有了流体的流动,所以将井筒内的传热看成竖直圆管中连续介质的传导,将地层中的传热看成多孔介质中的传导。
Firstly , in this dissertation , two types of symbol start time estimation schemes for orthogonal frequency division multiplexing ( ofdm ) systems are evaluated and analyzed . simulation results suggest that : pilot symbol based synchronization has better performance over cyclic prefix based schemes , and it performances improved when the length of pilot symbol increases ; cyclic prefix based synchronization method has a high spectrum efficiency in spite of its relative low acquisition of synchronization rate ; and the former is more suitable to bursting symbol based information systems , such as ieee802 . 11a , while the later can be used in broadcasting systems for continuous media streams , such as digital video broadcasting systems , digital audio broadcasting systems 首先,论文从同步获取的角度对ofdm系统中的两类时域符号同步方案进行了性能分析,并通过大量的仿真说明:基于训练序列的同步方法具有较好的同步获取成功率,其性能随训练序列的长度增加而改善;基于循环前缀的同步方法,其同步获取成功率较低,但是具有较高的频谱利用率;前者适用于突发数据帧传输系统,如ieee802 . 11a等,后者适合广播式连续媒体流传输系统,如数字音频、数字视频系统。
Recently , discrete particle model in which particles are directly tracked was paid widely attention due to the great development of computer hardware . in this model , gas phase is treated as continuous medium , and particle phase is treated as the discrete system . because particle movement is investigated in the particle - level , the multi - scales structure of fluidized bed can be simulated in both particle - scale and macro - scale 近年来,由于计算机硬件的飞速发展,直接对颗粒进行跟踪的离散颗粒模型得到了广泛的关注,此类模型将流体相处理为连续介质,颗粒相处理为独立的离散体系,由于它对颗粒相运动进行的是颗粒层次的分析,因而可以从颗粒尺度与宏观尺度模拟流化床气固两相流的多尺度结构。