温控太赫兹调制器多频带调制特性

基于开口谐振环结构设计了多频带太赫兹波调制器,并在谐振环的开口处及两侧均填充温敏介质锑化铟(InSb),研究了锑化铟的电磁性质随温度的变化、等效电感的组数对共振频带数目的影响以及锑化铟不同的填充方式对太赫兹波调制特性随温度的变化规律。研究结果表明,当环境温度从160 K上升到350 K时,锑化铟的载流子浓度和等离子体频率逐渐增大,然而等效介电常数却不断减小;每增加一组等效电感,太赫兹波调制器都会相应的增加一个共振频带;在调制器开口处和两侧均填充锑化铟时,当环境温度在160～350 K变化时,温度对太赫兹波的共振频率和共振幅度的调制效果比仅在开口处或者两侧填充锑化铟时更明显,且随着温度的升高,每个共振频带所对应的共振频率均明显增大。     

Rotating soliton clusters in nonlocal nonlinear media

From the study of the dynamics for the ring-like soliton clusters, we find that there exists a critical value of the ring radius, dcr, for the stationary rotation of the clusters with respect to the beam centre even in the presence of the relatively strong noise, and that the soliton clusters will not rotate but only undergo periodic collisions in the form of simple harmonic oscillator if the ring radius is large enough. We also show that the direction of the rotation can be opposite to the direction of phase gradient when the relative phase difference is within the domain 0 〈 ｜θ｜ 〈 π, while along the direction of phase gradient when the relative phase difference is within the domain π 〈｜θ｜ 〈 2π     

混合态下运动原子与相干态光场相互作用的量子纠缠

利用负熵方法,研究了混合态运动原子与相干态光场相互作用系统的量子纠缠特性,讨论了原子初态、场模结构参数、相干场平均光子数、失谐量、跃迁光子数等物理参量对系统纠缠度的影响。结果表明：考虑原子运动时,系统纠缠度在整个时域范围内出现了规则的周期振荡。原子初态趋于纯态时系统纠缠度较高。随着相干场平均光子数的增大,系统纠缠度的峰值逐渐变小,规则振荡的周期不变。随着跃迁光子数的增大,系统纠缠度的峰值逐渐变大,振荡变得越来越快。随着失谐量的增大,系统纠缠度的峰值逐渐变小。     

Gibbons-Maeda dilaton 黑洞的纠缠熵

按纠缠熵方法，计算了Gibbons-Maeda(G-M)dilaton黑洞视界外部与黑洞内量子态纠缠的一薄层内量子场的统计熵，得到了G-M dilaton黑洞的Bekenstein-Hawking熵.用广义不确定原理对量子态密度进行修正，克服了brick-wall模型中视界附近态密度的发散困难，该薄层可以紧贴在事件视界上.对brick-wall外部量子场中与黑洞内自由度有关联的自由度统计熵进行了计算，并把结果与brick-wall内量子场的熵进行比较分析，显示两结果具有与视界面积成正比的一致性，但后者能更 关键词： 纠缠熵 黑洞 广义不确定原理 截断     

确定大气边界层顶高度的新方法及数值实验

提出了一种确定大气边界层顶高度的数值微分新方法,该方法使用了正则化技术,把对弯角廓线求导数的数值微分问题转化为求目标泛函极小值的问题,采用双参数模型函数方法来选择正则化参数,最后利用最大梯度法确定边界层顶高度.首先通过两个数值实验验证了新方法的有效性,实验结果显示,随着掩星资料噪音的增多,由差分法和结合L曲线方案的数值微分方法得到的边界层顶高度波动增大,而通过双参数模型函数方法得到的高度很稳定,这说明新方法能够很好地过滤噪音,从而保留廓线的主要信息.随后基于2007-2011年1,4,7,10月的COSMIC弯角数据,利用新方法分析了全球海洋大气边界层顶高度的季节特征,并与用掩星资料自带的大气边界层顶高度数据zbalmax得到的季节分布进行对比.结果表明,两者的季节分布特征十分一致:海温相对周围海域高的区域,边界层顶高度较高,反之,边界层顶高度较低;在暖流经过的海域,边界层顶高度较高,在寒流经过的海域,边界层顶的高度相对较低.     

磁绝缘线振荡器脉宽及效率与三角波电压关系

采用数值模拟与实验相结合的方法,在没有功率容量不足问题的情况下,研究了磁绝缘线振荡器(MILO)的输出微波脉宽和功率效率与类似三角形二极管电压的关系,研究结果表明:在相同宽度的电压条件下,随着电压幅度的增大,输出微波的底宽和半高宽相应增大,功率效率先增大,当达到饱和后功率效率逐渐降低;在相同电压幅度条件下,随着二极管电压上升沿(斜率不变)的增大,输出微波的半高宽略有增大,但功率效率略有降低。因此,在有限脉宽的类似三角形二极管电压条件下,通过增大二极管电压上升沿的方法,可以有效地增大输出微波脉宽;而在有限电压幅度条件下,通过减小电压上升沿的方法,可以有效地增大输出微波的功率。选择适当的二极管电压参数,可以解决MILO器件在类似三角形二极管电压条件下的输出微波功率和脉宽两个指标相匹配的问题。     

Electrokinetic transport of nanoparticles to opening of nanopores on cell membrane during electroporation

Nanoparticle transport to the opening of the single nanopore created on the cell membrane during the electroporation is studied. First, the permeabilization of a single cell located in a microchannel is investigated. When the nanopores are created, the transport of the nanoparticles from the surrounding liquid to the opening of one of the created nanopores is examined. It was found that the negatively charged nanoparticles preferably move into the nanopores from the side of the cell membrane that faces the negative electrode. Opposite to the electro-osmotic flow effect, the electrophoretic force tends to draw the negatively charged nanoparticles into the opening of the nanopores. The effect of the Brownian force is negligible in comparison with the electro-osmosis and the electrophoresis. Smaller nanoparticles with stronger surface charge transport more easily to the opening of the nanopores. Positively charged nanoparticles preferably enter the nanopores from the side of the cell membrane that faces the positive electrode. On this side, both the electrophoretic and the electro-osmotic forces are in the same directions and contribute to bring the positively charged particles into the nanopores.     

三腔整管RKA相位的理论与模拟的比较分析

首先采用运动学理论和空间电荷波理论推出了计算中间腔间隙入口处调制电流相位的经验公式。采用调制电子束激励中间腔的非线性理论估算中间腔和输出腔间隙电压的幅度和相位,并提出了估算输出腔间隙入口处调制电流相位的经验公式。采用这些理论和二维粒子模拟比较了中间腔和输出腔间隙入口处调制电流相位、中间腔和输出腔间隙电压相位。中间腔和输出间隙入口处调制电流相位误差为2.627°(模型1)和3.857°(模型2)。中间腔间隙电压幅度的相对误差是1.47%,输出腔幅度的相对误差是5.42%,中间腔相位的误差是4.017°(模型2)和5.427°(模型3),输出腔的相位的误差是12.32°。最后根据二维粒子模拟得出了三种模型调制电流的相位与距离的关系。相关理论计算结果与2D的PIC模拟结果进行了比对,验证了理论估算结果的可信度。     

Collapsing dynamics of a laser-induced cavitation bubble near the edge of a rigid wall

In the present paper, the collapsing dynamics of a laser-induced cavitation bubble near the edge of a rigid wall is experimentally investigated with a high-speed photography system. For a symmetrical setup, the two primary control parameters of the bubble collapsing behavior include the equivalent maximum bubble radius and the distance between the bubble and the edge of the rigid wall. Based on the bubble interface deformation during the collapsing process, three typical cases are identified for the categorization of the phenomenon with the influences of the parameters revealed. Through a quantitative analysis of the obtained high-speed photos, the motions of the bubble interface in different directions are given together with the calculations of the bubble centroid. The primary findings of the present paper could be summarized in terms of the bubble-edge distance as follows. When the bubble is close to the edge, the movement of the bubble interface near the edge will be restricted with a clear neck formation in the middle part of the bubble. For this case, the edge could delay the bubble collapsing time up to 22% of the Rayleigh collapsing time. When the bubble is of the medium distance to the edge, the differences of the expansion or shrinkage of the bubble interface among different directions will be reduced with an olive-shaped bubble formed during the collapsing process. For this range of parameters, the bubble moves rapidly toward the edge especially during the final collapsing stage. When the bubble is far away from the edge, the bubble will be a nearly spherical one.     

Near-field acoustic characteristics of screech jet exhausted from a nozzle with a hard reflecting plate

The standing wave in the near field of the screech jet exhausted from a nozzle with a hard plate works on the jet flow as the forcing wave by the location of a reflecting plate, and then jet flow is considered to be changed. Moreover, the reflector location from the nozzle changes the sound pressure contours of the near field. Intensity maps of the screech tone which indicate the propagation to the jet axial direction or the radial direction of the jet by the presence of the reflector plate have not been explored. In the present paper, acoustic characteristics in the near field of the screech tone with the reflecting plate are studied using an optical wave microphone, which can measure the sound propagating for both vertical and horizontal directions to the jet axis. As a result, the standing wave in the near field of the screech jet with the reflector has two types: One is the standing wave between the hydrodynamic pressure fluctuation propagating jet downstream and the sound pressure propagating upstream, and the other is the standing wave by the difference between the wavelength of the sound wave and the wavelength at the place close to the jet.     

二维阵列狭缝阿达玛光谱仪波长准确度研究

二维阵列狭缝模板是阿达玛编码模板的一种新的设计思想,分析了模板上同列狭缝的加工误差对仪器波长准确度的不利影响,在此基础上,给出了减少同列狭缝高度、垂直光谱维方向上位置不一致性误差对仪器波长准确度影响的方法,以及同列狭缝在光谱维方向上位置不一致导致解码所得谱线产生的光谱偏移量的粗略估计方法,并建立模型进行仿真,计算了当模板上某列狭缝存在宽度、光谱维方向上位置不一致性误差时,解码所得其他各列狭缝谱线分布上测量误差的大小,根据仿真结果可以初步确定模板的加工精度。通过该研究有助于合理设计MEMS(微机电系统)二维阵列狭缝模板,获得对系统误差的有效补偿,提高仪器的波长准确度。     

串列扑翼间前缘涡在不同间距下对平均推力的影响

利用压力传感器测量扑翼的瞬时力,利用数字粒子测速仪（digital particle image velocimetry,DPIV）系统测量扑翼的前缘涡以及周围的流场,来揭示前缘涡在不同间距下对扑翼平均推力的影响.实验在一个低Reynolds数循环水洞中进行,两串列扑翼均做二维正弦平动.在固定的相位差下,当间距增加时,后翅前缘涡对前翅的影响具有相似性,均提高或者均降低前翅的平均推力.前翅平均推力的提高是由于后翅的前缘涡提高了前翅尾部的射流速度以及有效攻角.随着间距的增加,后翅前缘涡对前翅的影响急剧下降,使得前翅的平均推力快速接近于单翼值.在固定的相位差下,当间距增加时,前翅的脱落涡对后翅的影响变化非常大,后翅的平均推力可能先升高后降低,这是因为间距改变了前翅脱落涡作用于后翅的时间点.当前翅脱落涡遇到后翅,并且和后翅的前缘涡有相同的旋转方向时,前翅的脱落涡会抑制后翅前缘涡的形成,并且后翅的有效攻角减小,其平均推力降低.如果这两个涡的旋转方向相反,那么后翅有效攻角就会增大,平均推力值就会提高.      

充模过程中熔接痕的改进光滑粒子动力学方法模拟与预测

提出了一种黏弹性流体的改进光滑粒子动力学(SPH)方法以试探性地模拟和预测黏弹性FENE-P熔体充模过程中熔接痕的形态演化. 首先基于SPH方法建立了聚合物流动的宏微观耦合模型, 同时提出了黏弹性流体的改进SPH离散格式. 随后, 通过模拟一些基准算例验证了改进的SPH方法模拟聚合物宏微观耦合问题的有效性及收敛性, 以及所提出的黏弹性温度模型的有效性. 最后, 模拟了环型腔内的充模过程, 试探性地展示了充模过程中微观分子的变形过程. 同时采用顺序热流道技术模拟了多浇口C形腔内的充模过程, 并与其他数值结果做比较. 数值结果表明: 对于大制件多浇口充模过程, 顺序热流道技术能够改善甚至消除充模过程中的熔接痕.     

单极随钻声波测井换能器感知信号类型的研究

在假定钻铤是光滑的提前下，前人理论模拟了随钻测井的声压波形，但未发表关于理论波形与实验波形的比较的文章。为了认识测量信号所对应的力学类型及相应类型的钻铤波在钻铤内的分布，本文将理论模拟的随钻声波测井波形与实验波形进行对比。与前人单独考虑压电效应或井孔传播效应不同，本文模拟单极随钻声波测井响应时，将发射器、接收器、光滑钻铤和井孔结构作为一个整体，采用有限元法计算模拟了电压源激励下接收器纪录的声压信号和位移信号。将模拟的声压波形与电压信号进行比较，发现二者的钻铤波与斯通利波相对幅值相差较大，而模拟的径向位移波形更接近电压信号。进一步比较理论波形与小模型井内实验测量到的电压信号，证实电压信号更接近位移信号而与声压信号差异明显。这表明当钻铤光滑时，单极随钻声波测井换能器感知的主要是径向位移信号。研究还表明声压信号中的钻铤波能量主要集中在钻铤内壁，径向位移信号中的钻铤波能量主要集中在钻铤外壁。     

滚筒内非等粒径二元颗粒体系增混机理研究

提出了在圆形滚筒内设置十字形内构件的增混方式,并采用离散单元方法对设置不同大小内构件的滚筒内非等粒径二元颗粒体系的混合进行了数值模拟试验.通过模拟结果重点分析了内构件对混合的影响,讨论了内构件的尺寸对混合效果的作用,分析和探讨了滚筒内构件对二元颗粒体系的增混机理.研究发现,当滚筒内无内构件时,对流、扩散和离析三种作用机制对颗粒体系的混合和分离都起到了重要作用;当滚筒内含内构件时,颗粒的混合则只受到颗粒对流和扩散机制的作用,而颗粒的离析效应得到了很大程度的抑制.十字形内构件很大程度上会破坏滚筒内的自由表面流,从而使发生在自由表面流中的颗粒分离不能发生,最终可有效地增加颗粒之间的混合.对于采用在滚筒内设置十字形内构件的方式来增加颗粒间的混合,存在一个最优的内构件尺寸,内构件过小或过大都不利于颗粒间的混合. 关键词： 分离 混合 离散单元法     

Traffic flow velocity disturbance characteristics and control strategy at the bottleneck of expressway

In the three-phase traffic flow studies, the traffic flow characteristic at the bottleneck section is a hot spot in the academic field. The controversy about the characteristics of the synchronized flow at bottleneck is also the main contradiction between the three-phase traffic flow theory and the traditional traffic flow theory. Under the framework of three-phase traffic flow theory, this paper takes the on-ramp as an example to discuss the traffic flow characteristics at the bottleneck section.In particular, this paper mainly conducts the micro-analysis to the effect of lane change under the two lane conditions, as well as the effect of the on-ramp on the main line traffic flow. It is found that when the main road flow is low, the greater the on-ramp inflow rate, the higher the average speed of the whole road section. As the probability of vehicles entering from the on-ramp increases, the flow and the average speed of the main road are gradually stabilized, and then the on-ramp inflow vehicles no longer have a significant impact on the traffic flow. In addition, this paper focuses on the velocity disturbance generated at the on-ramp, and proposes the corresponding on-ramp control strategy based on it, and the simulation verified that the control strategy can reasonably control the traffic flow by the on-ramp, which can meet the control strategy requirements to some extent.     

粒子在二维开放型四分之一圆形微腔中的逃逸研究

利用半经典理论对粒子在开放型四分之一圆形微腔中的逃逸过程进行了研究,推导出了逃逸几率密度的计算公式.我们研究了一簇从四分之一圆形微腔的左下方的入口出射、并从该微腔右边界逃逸的粒子轨迹.对于粒子的每一条逃逸轨迹,记录下它的传播时间和逃逸的位置.结果发现逃逸时间图随着逃逸点的位置的变化曲线呈现出振荡结构.随着碰撞次数的增加,逃逸点的位置越靠近该腔的右顶端.对一系列的探测点,找到从源点出发到达探测点的轨迹,然后应用半经典理论来构造波函数,进而给出逃逸几率密度的计算公式.研究结果标明,逃逸几率密度与探测平面上逃逸点的位置、粒子的动量、初始出射角及与微腔的碰撞次数有关.为了更清楚的看出量子力学和经典力学之间的联系,我们对体系的半经典波函数进行傅里叶变换,给出了粒子的路径长度谱.路径长度谱的每个峰值对应于一条粒子逃逸轨迹的长度.本文的研究对理解量子力学和经典力学之间的联系以及研究粒子在微腔中的的逃逸和输运过程有一定的参考价值.     

利用气象要素估算海洋大气近地层光学湍流

基于近地层相似理论以及极端层结下对该理论的修正,建立了海洋大气近地层光学湍流估算模型,并进行了数值分析。结果表明:当气温与海温相差较大时,温度起伏对光学湍流贡献最大;当气温与海温相差较小时,海面湿度越小,光学湍流越强;在较低湿度条件下,尤其在红外窗区,湿度扰动对光学湍流贡献起支配作用。当气温小于海温时,光学湍流先随海面风速增大而增强,后随风速增大而减弱;当气温大于海温时,光学湍流总体上是伴随海面风速增大而减弱。当气温小于海温或与海温接近时,与可见光和近红外波段相比,红外窗区光学湍流显著偏强;当气温远大于海温时,两波段光学湍流接近。在中性和近中性层结下,大气折射率结构参量C2n依赖于垂直高度的负幂指数接近-2/3,伴随海面大气层结稳定度或不稳定度增强,C2n依赖于垂直高度的负幂指数的绝对值分别逐渐减小或增大,并分别趋近于稳定极限下的0或不稳定极限下的-4/3。     

原子吸收限附近完整晶体内的能流方向

研究了原子吸收限附近对称劳厄和布拉格情况下完整晶体内的能流方向．发现在对称劳厄情况下，只有当原子散射因子的虚部对衍射的贡献可以与实部的贡献相比较时，晶体内与色散面上某一结点相对应的能流会偏离色散面的实部的法向；而在对称布拉格情况下，即使在原子散射因子的虚部对衍射的贡献可以忽略时，在所谓的“全反射”区内也会偏离．当衍射仅由原子的虚部引起时，这种偏离在对称劳厄情况下最大，而在对称布拉格情况下最小． 关键词：     

Comptonɢ��Լ�����������йⳡ�͵����ܶȷֲ���Ӱ��

应用电子和多光子集团非弹性碰撞模型和冷等离子体模型，研究了飞秒强激光与线性等离子体发生多光子非线性Compton散射时，散射激光与入射激光形成的飞秒耦合激光场对线性等离子体层中光场和电子密度分布的影响。研究发现，在耦合激光的有质动力作用下，电子密度分布和离子密度分布比Compton散射前的偏离更加严重，电子密度的变化比离子密度的变化更快，产生的静电场更强。即使耦合激光场非常弱，电子的运动仍表现出相对论效应，仍有静电场存在。