水下超声速气体射流气液两相复杂流动研究

本文实验研究了水下超声速气体射流气液两相复杂流动。利用高速摄影仪和电子相机分别实时记录了过膨胀超声速工况水下气体射流的喷射状态和整体形貌,显示了不同工况水下高速气体垂直射流的演化过程和动态不稳定性形貌。研究结果表明:在射流的初始段存在与射流内部复杂波系相关的激波反馈特性,激波反馈特性发生之前存在能量积聚的高频低幅的胀鼓过程,二者均随机发生;在射流的主体段,在气水掺混和卷吸大规模能量交换作用下,射流呈现随机的偏摆效应,并且偏摆受环境流场影响明显。     

气-液组合横向射流中气体种类的影响

吸气式旋转爆震发动机中燃料的良好雾化对爆震燃烧的组织极其重要,气-液组合横向射流是其中一种重要的燃料喷注技术。为获取气体种类在超声速来流中对其的影响,通过数值方法对液体射流穿透深度和辅助射流气体分布进行研究。采用Euler-Lagrange方法研究不同气体射流对液体射流的作用规律,结果表明：气体射流通过激波结构降低局部来流动量通量提升液体射流穿透深度,相同的来流条件下气体射流动量通量越大,液体射流穿透深度越高,且主要影响扩张段之前的流场区域,气体种类的变化对于后场液体射流穿透深度和雾化特性几乎无影响。     

Performance Optimization of Phase-Shifting Interferometry Using Data Average on Wide Range Roughness Measurement

Performance optimization of phase-shifting interferometry was investigated using data average on wide range roughness measurement. The interferometry performance was strongly affected by data average and an optimal data averaging condition of minimal measurement error was found. The high limit roughness level which makes the data average available for the interferometry performance optimization providing a reproducible and smallest roughness was determined to be about 5 _A rms roughness. Therefore, the optimal interferometry performance absolutely required data average for finer surfaces than about 5 _A rms roughness. On the other hand, the optimal interferometry performance for surfaces rougher than about 10 _A rms required little data average. The reliability of the optimal performance of phaseshifting interferometry was checked.     

利用单光子的量子对话

提出了一个利用一束单光子对话的方案.在方案中,利用两个不同的幺正操作对光子态进行编码,并且从一束光子中选择较大的子集进行窃听检查,该方案能够有效地抵御截取再发送袭击.此外,由于利用单光子没有利用EPR对,因此该方案是很实际的.该方案是绝对安全的.     

Characteristics of High Harmonics Generated in a Gas Filled Microcapillary

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Characteristics of High Harmonics Generated in a Gas Filled Microcapillary

The phase-match and amplitude characteristics of high harmonics generation in gas filled micro-capillary have been analyzed. The results show that the order of harmonic can be selected by adjusting the gas pressure, the laser intensity and the inner diameter of capillary. The adjustment is depended on the dispersion properties of gas media . The amplitude of harmonics generated in gas filled capillary is two orders higher than that of gas jet, and the spectrum is become more monochromatic when the radius of the capillary is smaller. A high brightness tunable coherent soft X-ray source can be produced through interaction of fs intense laser with gas filled microcapillary.     

The Further Study of Corrugated Circular Groove Waveguides by Using Method of Space Harmonics

By using method of space harmonics in the interior and higher order modes in the slot region of the corrugated circular groove waveguide, The dispersive equation of this waveguide is derived.     

单帧单曝光图像法测量气固两相流速度场

本文提出一种基于单帧单曝光图像的气固两相流固相颗粒的速度场测量方法。通过控制相机的单次曝光时间获得流场中颗粒的单帧运动模糊图像,运用分水岭算法分割图像,提取颗粒,由自相关函数获得各颗粒的速度大小和方向,重建二维速度场。利用该方法对玻璃珠在空气中重力沉降的速度测量结果与理论值基本一致,矢量场与颗粒运动轨迹相符,说明该方法可以用于气固两相流速度场的测量。研究发现使用片光源比背光源能够获得更加准确的速度值。     

用单光纤光栅实现扭转与温度的双参量传感测量

采用一种新颖的扭梁设计结构 ,利用单光纤光栅成功地实现了扭转 (扭转角或扭矩 )与温度的双参量同时测量。该方法能够有效地解决扭转角与温度的交叉敏感问题 ,且光纤光栅波长的变化对扭转角、扭矩及扭应力 (力臂一定时 )均呈线性关系。在 - 40°～ +32°范围内 ,扭转角、扭矩和温度的传感灵敏度分别达到 0 .19nm (°)、3.2 9nm Nm和 0 .0 3nm ℃ ,波长线性调谐范围可达 14.2 0nm。     

Assessment of Fiber Chromatic Dispersion Based on Elimination of Second-Order Harmonics in Optical OFDM Single Sideband Modulation Using Mach Zehnder Modulator

This work addresses the analytical and numerical investigations of the transmission performance of an optical Single Sideband (SSB) modulation technique generated by a Mach Zehnder Modulator (MZM) with a 90° and 120° hybrid coupler. It takes into account the problem of chromatic dispersion in single mode fibers in Passive Optical Networks (PON), which severely degrades the performance of the system. Considering the transmission length of the fiber, the SSB modulation generated by maintaining a phase shift of π/2 between the two electrodes of the MZM provides better receiver sensitivity. However, the power of higher-order harmonics generated due to the nonlinearity of the MZM is directly proportional to the modulation index, making the SSB look like a quasi-double sideband (DSB) and causing power fading due to chromatic dispersion. To eliminate one of the second-order harmonics, the SSB signal based on an MZM with a 120° hybrid coupler is simulated. An analytical model of conventional SSB using 90° and 120° hybrid couplers is established. The latter suppresses unwanted (upper/lower) first-order and second-order (lower/upper) sidebands. For the analysis, a varying quadrature amplitude modulation (QAM) Orthogonal Frequency Division Multiplexing (OFDM) signal with a data rate of 5 Gb/s is upconverted using both of the SSB techniques and is transmitted over a distance of 75 km in Single Mode Fiber (SMF). The simulation results show that the SSB with 120° hybrid coupler proves to be more immune to chromatic dispersion as compared to the conventional SSB technique. This is in tandem with the theoretical analysis presented in the article.     

利用等离子体非定常射流实现单转子轴流压气机扩稳

实验研究了非定常等离子体射流对低速单转子轴流压气机稳定工作范围的影响。实验在低速单转子轴流压气机实验台上开展,在压气机转子前缘处布置一组等离子体激励器,通过施加非定常等离子体激励,在压气机转速为1500～2400r/min下实现了压气机扩稳。实验测量表明需要协调好激励器布置位置和激励强度之间的矛盾,将激励器靠近转子前缘对叶尖泄漏流的作用更强,不过距离转子过近会造成激励器与叶片之间易于爬电,这样无法提高激励强度,反而不利于扩稳,通过反复实验,发现在转子前缘19 mm布置激励器时不会发生爬电且扩稳效果比较理想。为了对等离子体诱导射流发生的反作用力有定量认识,利用电子天平测量了不同激励电压下反作用力的大小。     

MSM光探测器瞬态特性的二维分析及优化设计

应用有限差分方法对金属-半导体-金属光探测器进行二维分析,全部数值模拟工作都是基于半导体物理的基本微分方程完成的.结合模拟结果对金属-半导体-金属光探测器的瞬态响应进行了分析,以特性分析结果为基础针对探测器的响应速度和响应率等性能指标进行了二维结构上的优化设计.     

自由光谱范围加倍的单微环谐振滤波器

基于两点耦合和光波干涉控制相移思想提出U型波导耦合单微环的谐振滤波器结构。利用传输矩阵法推导了此结构的数学模型,采用Matlab模拟了输出端口谱线形状。当微环与U型波导的两个耦合点之间的距离为微环周长的整数倍时,此新型微环谐振滤波器比传统的双直波导耦合单微环滤波器的自由光谱范围增加1倍。针对该结构参数,同时讨论了耦合系数对输出谱线的影响,得出当耦合系数为0.018时,输出谱线具有最佳的消光比,同时保持窄的带宽和高的品质因子。     

A Single Model of Interacting Dark Energy: Generalized Phantom Energy or Generalized Chaplygin Gas

I present a model in which dark energy interacts with matter. The former is represented by a variable equation of state. It is shown that the phantom crossing takes place at zero redshift, moreover, stable scaling solution of the Friedmann equations is obtained. I show that dark energy is most probably be either generalized phantom energy or the generalized Chaplygin gas, while phantom energy is ruled out as a dark energy candidate.     

Simultaneous Teleportation of Arbitrary Two-qubit and Two Arbitrary Single-qubit States Using A Single Quantum Resource

In this paper we present a teleportation protocol by which the multitask of transfer of a two-qubit and two single-qubit quantum states is performed simultaneously with the help of a single entangled channel. The protocol is under the supervision of a controller. There are three pairs of senders and receivers who are connected among themselves along with the controller by a single entangled state. The teleportation protocol is perfect.     

采用移动极差统计合并技术来监控ICP-AES测量系统的不确定度

采用ICP AES(电感耦合等离子体 原子发射光谱法 )测定金属硅中铁杂质含量进行不确定度评估时 ,提出了平均移动极差 (MR)合并统计动态监控技术。研究认为 ,采用该技术来进行ICP AES测量系统的不确定度评估 ,其贡献量分别是由控制样品 (QC)和线性拟合两部分合成。这一结论的得出能最大限度合成各种变异因素的影响 ,避免了相关性的复杂计算 ,有利于ICP AES测量系统的不确定度评估     

利用气体火焰研究驻波

驻波是一个比较抽象的概念,较难理解,用气体火焰模拟驻波可以让我们更直观的研究声场产生的驻波。实验中发现火焰按波形变化的规律分布,用驻波波函数和伯努利方程对实验现象进行了理论分析,引入压节(波腹)、压腹(波节)解释在两端出现的高火焰现象。实验结果与理论分析接近一致。     

二能级系统的高次谐波产生过程的动力学分析

通过非扰动方法导出了与线偏振激光脉冲相互作用的二能级原子的诱导极化所满足的运动方程，并通过在一些不同激光强度下的该运动方程所具有的不同形式，对二能级系统的市郊人谐波的产生过程进行了动力学分析。     

两种荧光染料对葡萄糖氧化酶的标记

本工作用异硫氢酸荧光素和异硫氢酸四甲基罗丹明分别对葡萄糖氧化酶进行标记，研究了标记蛋白的吸收光谱，荧光光谱，讨论了两种染料标记的位点的差异，同时还研究了脲对标记后染料荧光的影响。