Optimizing the spectral efficiency of photonic quantum well structures

One can construct photonic single quantum well structures by sandwiching a homogeneous medium slab as a defect between two symmetrical photonic crystals (PCs). It is shown that the number of observed resonant peaks increases with increasing slab thickness. It is found that while the slab is composed of alternatively stacked step-index films, the frequencies of these resonant peaks can be adjusted finely by changing the film thickness properly. In this case, the frequency and frequency interval of confined states can be tuned accurately, and the spectral efficiency can be greatly enhanced without increasing the volume of optical devices. Numerical simulation is based on the finite-difference time-domain (FDTD) method.     

新课程下化学教学的反思

新课程下如何实施化学的高效课堂教学?从转变教学思想,科科学把握教学深广度,精心策划教学设计,灵活用用教学策略,作业布置,学习效果的评价方式等方面做了反思与总结.     

High-performance 850 nm vertical-cavity surface-emitting laser in Gigabit Ethernet network

High-performance oxide vertical-cavity surface-emitting (VCSEL) laser is fabricated, and its usefulness is demonstrated as a suitable transmitting light source at 850 nm operating wavelength for Gigabit Ethernet application. Utilization of barrier reduction layers reveals low-threshold current requirement for operation at high modulation bandwidth. The electrical and optical characteristics, measured from the fabricated VCSEL, are simulated for Gigabit Ethernet transmission. Data rates of 1.25 Gbps with a bit error rate of 10⁻¹¹ are achieved by the use of a specific multimode network simulator.     

深基坑回弹观测及应注意的问题

对平煤集团经调中心进行了基坑回弹观测 ,着重介绍回弹观测的观测方法、观测过程、误差来源、精度分析及观测中应注意的问题     

浅谈卧泥井的设置

结合工程实践，介绍了卧泥井的构造、特点及作用，探讨了设置卧泥井存在的问题及对策，提出了卧泥井设置的注意事项．     

井壁超热中子测井MC模拟

在 MCNP的基础上 ,开发了井壁超热中子时间谱测井蒙特卡罗 (Monte Carlo)模拟软件包 .裸眼井、井眼里无下井仪器、淡水饱和砂岩地层、井眼注淡水 ;油饱和砂岩地层、井眼注油 ;油饱和砂岩地层、井眼注淡水 ;淡水饱和灰岩地层、井眼注淡水与淡水饱和白云岩地层、井眼注淡水 ,及裸眼井、井眼里有下井仪器、淡水饱和砂岩地层、井眼注淡水等条件下 ,计算井壁超热中子时间谱随孔隙度的变化 ,同时可得到井壁超热中子总通量随孔隙度的变化 ,结果证明井壁超热中子时间谱测井或井壁超热中子测井是确定地层孔隙度最有效的方法 .在此基础上 ,再研究井壁超热中子时间谱测井仪或井壁超热中子测井仪的工程参数 .     

油井超声互相关流量测量方法

提出了一种用超声互相关测量油井流量的方法 ,设计了专用超声传感器和互相关器。试验结果证明 ,用该方法测量油井流量是可行的 ,但在获得工业应用之前要解决一些实际问题。     

Entropy and equilibrium property of QCD-instanton induced final state in deep-inelastic scattering

The scaling and additivity properties of Rényi entropy in rapidity space of the instanton final state (IFS) and current jet identified by the r-sorting method from the QCDINS Monte Carlo event sample are to saturation with decreasing phase space scale. Furthermore, it is found that the additivity of H2 holds well for the IFS in narrow rapidity windows at different positions. These results indicate that the IFS produced in the instanton-induced process of deep inelastic scattering has reached local equilibrium.     

定向井环空内岩屑运移机理的研究

运用实验观察方法,对定向井环空内岩屑的运移情况进行了研究和分析。从宏观上看,斜井环空内岩屑的运移状况有四种不同的流动物理模型,即:均称悬浮流动、非均称悬浮流动、移动床流动和固定床流动。在不同斜度的井眼中分别存在一个对应的临界流速.从微观上分析,岩屑床床面的岩屑颗粒承受液流的拖曳力和上举力、粒间离散力、重力和浮力的作用。对于极细的岩屑颗粒,还承受粒间粘结力。研究结果表明,环空倾角对岩屑运移有一定的影响。倾角越大,越不利于岩屑的运移。液流流速越大,岩屑的运移越快。     

大斜度井中岩屑床厚度模式的研究

岩屑床是大斜度钻井中的重要影响因素,为了控制岩屑床的形成厚度,保证安全钻进,建立了岩屑床厚度的理论计算模式和半经验模式,分析了影响岩屑床形成的各种因素。运用所建立的计算模式对油田丛式井斜度较大的6口井进行了计算。计算结果表明,半经验模式计算结果与理论模式计算结果基本相符。由计算结果推出了安全钻进时岩屑床的厚度极值为1.9cm.