陆上地震勘探中有关激发能量的几个问题

激发药量和药性一直是陆上地震勘探研究的课题 ,根据弹性介质形变与地震波能量的关系 ,就弹性介质能量饱和问题进行了探讨。结合生产实际 ,提出了采用饱和激发、欠饱和激发、过饱和激发和最佳激发药量等概念 ,来判断或分析炸药震源的激发效果 ,以及饱和激发药量和最佳激发药量的确定方法和准则。

SESAM锁模OP-VECSELs技术

综述了半导体可饱和吸收镜(SESAM)锁模光抽运垂直外腔面发射半导体激光器的理论,分析总结了相关实验技术手段,对SESAM锁模OP-VECSELs的最新研究成果作了介绍。

放射医学

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天体循环

原子中的电子、质子、中子等由单位质能体构成,单位质能体由中微子按能力互补规律,结构区域平衡规律和能量区域平衡规律构成。"宇宙背景辐射"和红移现象不能作为宇宙大爆炸的理论依据。四种力:电磁力、强核力、弱核力、引力都是同一种力在不同质能环境中的不同体现。引力是时空弯曲的因素。黑洞主要存在于暗物质区域里。星球的消亡分为:受其它星球撞击形成消亡,受其它星球爆炸的影响而形成消亡,受宇宙流体撞击而形成消亡,星球吞并形成消亡,向外放射质能体形成消亡。从宇宙整体来看:部分星球消亡,部分星球再生,生生不息,永无止境。星球的再生分为:碰撞形成星球再生,宇宙流体形成星球再生,黑洞经成长阶段形成爆发而形成星球再生。

自锁模超短脉冲激光输出的稳定性

为了研究非线性增益饱和效应对自锁模激光器超短脉冲输出的影响,采用L iapunov线性稳定性分析方法对描述自锁模激光输出的微分方程组进行了分析,得到了锁模定态存在的条件并讨论了各定态的稳定性。结果表明,当增益饱和能量小于一个特定值时,自锁模激光振荡器会同时存在两个锁模定态,其中能量较小的一个是稳定的,而且随着增益饱和能量的增大,此稳定自锁模态的能量增大、脉宽变窄,它应该是自锁模激光振荡器实际工作的状态。

Diode-pumped double passively Q-switched Nd:GdVO_4 laser

Through using both Cr^4＋：YAG and GaAs saturable absorbers, a diode-pttmped double passively Q-switched Nd：GdVO4 laser is realized and compared with a single passively Q-switched laser. This laser can generate symmetric pulse temporal profiles and shorter pulses. A laser pulse width of 17 ns has been achieved with the incident pump power of 8.5 W.

Digital core approach to the effects of clay on the electrical properties of saturated rocks using lattice gas automation

Clay has a significant influence on the relationship between resistivity index I and water saturation Sw （i.e, I-Sw relationship） of reservoir rocks because it complicates the current paths of these rocks. It is difficult to reveal the physical mechanisms of these clay effects on the conductivities of various rocks by physical laboratory measurements because the pore structure, micro distribution and content of clay inside a rock can not be observed and controlled during the experiments. We present a digital rock approach to study these clay effects on the electrical transport properties of reservoir rocks at pore scale using lattice gas automation （LGA） method. The digital rock samples are constructed with the information of grain size distribution from SEM images of reservoir rocks. The LGA is then applied on these digital rocks fully saturated with fluids to simulate the electrical transport properties for revealing the effects of volume and distribution patterns of clay on the non-Archie behaviors of the I-Sw relationship. The very good agreement between the simulated results and the laboratory measurements clearly demonstrates the validity of the LGA in numerical research of rock physics. Based on these studies, a new model has been developed for quantitatively describing the relationship between the saturation exponent and the volume of clay （Vsh）. This development may improve the evaluation for the fluid saturations in reservoir rocks.

Cellular automation model for analyzing capacity of branch road section

In order to reduce the traffic pressure of urban arterial road with the rational utilization of the branch road,the vehicle meeting behavior on the branch road without divided lane was described,and the cellular automation (CA) model was put forward by introducing meeting behavior to reflect the relation between safe meeting speed and road width.The numerical simulation results depict several relation curves between road section capacity,speed and road width under different directional distributions of traffic flow,as well as the curves between the major and minor direction saturation flow,speed and road width.These relation characteristics indicate that except the one-way road section capacity and speed remaining unchanged,other road section capacities and speeds under different directional distributions increase with the increase of road width.On narrow road,the two-way traffic capacity and speed are less than those of one-way traffic;on wide road,the two-way traffic capacity doubles that of one-way traffic,but their speeds are almost the same.As the directional distribution moves to an even distribution of 50/50,the major direction saturation flows and speeds as well as the minor direction speeds tend to decease,while the minor direction saturation flow tends to increase.

Solutions to Consider in Current Transformer Selection for APR1400 Nuclear Power Plant Medium Voltage Switchgears

This paper discusses a preferable solution to mitigate the CT （current transformer） saturation problem, and at same time, reduce the accuracy errors when considering the selection of CTs for installation on the medium voltage switchgear of a nuclear power plant. This consideration is important for both measurement and protection functions of the digital protective relays. This is a study to ascertain the best options for a suitable solution to prevent CT saturation in relations to its protective capabilities during short circuit fault without compromising the CT accuracy class during normal operation of the system, while ensuring its conformity to the design requirement is within limit. The advantages of current transformers have proven not only to be reliable and safe, but also are of easy handling, reduction of the cost and components on the MV （medium voltage） switchgear. The purpose of this research is to identify best approach to resolve the existing problems in the current protection system. With the view of LPCT （low power current transformer） which has been newly constructed by few manufacturers to provide good protection and a wide range of measuring function without errors, some other solutions will be considered in this research.

Effects of behavioral characteristics of taxi drivers on safety and capacity of signalized intersections

Comparative analyses were conducted to compare the effects of the behavioral characteristics of the drivers of taxis and private cars on the capacity and safety of signalized intersections. Data were collected at sixteen signalized intersections in the Nanjing area in China. The risk-taking behaviors of the drivers of taxis and private cars were compared. The results suggest that 19.9% of taxi drivers have committed at least one of the identified risky behaviors, which is 2.37 times as high as that of the drivers of private cars(8.4%). The traffic conflicts technique was used to estimate the safety effects of taxis and private cars. The overall conflict rate for taxis is 21.4% higher than that for private cars, implying that taxis are more likely to be involved in conflicts. Almost all of the identified traffic conflicts can be attributed to certain levels of risk-taking behaviors committed by either taxi drivers or the drivers of private cars, and taxi drivers are more likely to be at fault in a conflict. Failure to yield to right-of-way and improper lane change is the leading causes of the conflicts in which taxis are at-fault. The research team further studied the effects of taxis on the queue discharge characteristics at signalized intersections. The results show that the presence of taxis significantly reduces both start-up lost time and saturation headways. The effects of taxis on saturation flow rates are dependent on the proportion of taxis in the discharge flow, and the saturation flow rates increase with the increase in the proportion of taxis. The adjustment factors for various proportions of taxis for different turning movements are then calculated to quantitatively evaluate the effects of taxis on the capacity of signalized intersections.

被动锁模掺镱光纤激光器中耗散孤子特性

对被动锁模光纤激光器系统谐振腔中每个器件进行建模;通过数值仿真实验研究了具有严格线性啁啾的耗散孤子在谐振腔内的演化过程;分析了腔内色散与掺镱光纤的饱和能量对耗散孤子脉宽与峰值功率特性参数的影响.仿真实验结果表明,耗散孤子的脉宽随着色散的增加而变宽,峰值功率随着色散的增加而减小.增益饱和能量对耗散孤子脉宽的影响是非单调的,在仿真实验条件下,当掺镱光纤的增益饱和能量的值为70 p J时,脉宽达到最小值,而耗散孤子的峰值功率随着增益饱和能量的增加而增加,且变化趋势几乎是线性的.

全正色散光纤激光器输出抛物线脉冲特性研究

在全正色散光纤激光器的基础上,数值研究了不同泵浦方式对抛物线脉冲产生的影响。建立了全正色散光纤激光器的模型,具体研究了不同泵浦方式下不同的增益可饱和能量以及增益带宽对激光器输出抛物线脉冲的拟合因子、脉宽、频谱宽度和脉冲能量的影响。结果表明,后向泵浦方式下激光器能输出更大能量的抛物线脉冲,而且能在更低的增益可饱和能量下产生抛物线脉冲。后向泵浦方式的全正色散光纤激光器可以在更大的增益可饱和能量范围内保持抛物线形脉冲的输出。全正色散腔中增益光纤的增益带宽对抛物线脉冲输出特性的影响较小。

Energy flux characteristics of seismic waves at the interface between soil layers with different saturations

Based on the multiphase poroelasticity theory describing the propagation of waves in the unsaturated fluid-saturated porous medium,the reflection and transmission coefficients of the seismic waves at the interface between soil layers with different saturations are obtained.Our unsaturated model consists of a deformable skeleton in which two compressible and viscous fluids(i.e.,water and gas)flow in the interstices.Three compressional waves(i.e.,P1,P2,and P3 waves)and one shear(i.e.,S wave)wave exist in the unsaturated soils.The expressions for the energy ratios of the various reflected and transmitted waves at the interface during the transmission and reflection processes are presented in explicit forms accordingly.At last,numerical computations are performed and the results obtained are respectively depicted graphically.The variation of the energy ratios with the incident angle,wave frequency and saturation degrees of the upper and lower soil layers is illustrated in detail.The calculation results show that the allocation of incident seismic waves at the interface is influenced not only by the angle and frequency of the incident seismic waves,but also by the saturations of the upper and lower soil layers.It is also verified that,at the interface,the sum of energy ratios of the reflected and transmitted waves is approximately equal to unity as was expected.This study is of importance to several fields such as geotechnical engineering,seismology,and geophysics.

Theoretical analysis on expansion mechanism in carbon dioxide expander

The expansion mechanism inside carbon dioxide expander is analyzed theoretically in this paper.The mechanism analysis of metastable equilibrium indicates that there is a potential barrier during phase change process.That is to say energy is required to overcome the potential barrier when the new interface is formed from primary phase.The superheat of liquid is the impetus of phase change and has an exponential decrease with the increase of the saturated temperature of fluid.The analysis also indicates that there is a critical radius during the phase change process.The bubble will grow up when its radius is larger than the critical value,otherwise,will disappear.When considering the metastable phase change,calculation of P and V during expansion process indicates that the phase-change will be delayed with the decline of pressure,which is called lag phenomenon.The phase-change delay time decreases with the increase of initial temperature.When the initial temperature is close to the critical temperature,the delay time is close to zero.The phase-change delay brings energy losses,which decrease with the increase of initial temperature and its decrease ratio also has a decrease trend.When the initial pressure is 10 MPa,the energy loss will be 1.06 W with an initial temperature of 10℃ while 0.34 W with that of 20℃.