计及横向耦合的振幅变换器的计算

本文从弹性理论的普遍方程出发,用伴随法求解了轴对称变幅杆的振动模式。因为没有忽略横向耦合的影响,故用本法的计算结果不受横向尺寸的限制。作为用例,我们用本法计算了三种尺寸的指数式变幅杆的谐振频率,所得结果似比一维理论的计算结果更接近于实测。本法的另一优点是可以用来计算其他非指数型的变幅杆,例如高斯型杆、抛物线型杆等。关于本法的适用范围问题,还有待于进一步的研究。     

稀土分量的XRF法分析—熔珠粉末压薄片法

本法用50mg稀土氧化物样品,经四硼酸锂熔融后,粉碎压成薄片,以透空照射法,直接测定15项稀土分量和铀、钍。本法消除基体效应好,制样精度高,测定含量范围宽。     

能量色散X射线荧光光谱测定延迟焦化石油焦中的硫

本法采用能量色散Ｘ射线荧光光谱法成功地测定了延迟焦化石油焦的硫,结果表明,该方法简便、快速,准确,重复性较好。本法适用范围为０．３－６．５（ｍ／ｍ）％。     

火焰原子吸收光谱法测定血浆代用品中钾和钠

本文报道了火争原子吸收光谱法测定血浆代用品中钾，钠，使用镧和氯化铯，消除了电离干扰和共存元素干扰，本法简便，快速，本法的准确度和精密度均令人满意。     

快速测定工业废水化学需氧量

通过实验得出消解最佳实验条件为:催化剂NiSO4-CuSO4配比为80∶20,消解温度185℃、消解时间15min.本法测定的CODCr值与标准回流法所得结果一致,但本法比标准回流法省时.     

快速测定锌精矿中二氧化硅

用氢氧化钠熔融 试样,以水浸出熔融合物,分取部分试液于硫酸介质中,用硅钼蓝光度法测定锌精矿中二氧化硅的含量。加标回收率在９８％－１０２％之间。用本法测定锌精矿中的二氧化硅与国标法结果吻合。可见本法准确,可靠,并且简便,快速。     

测定树木中总氮和总磷的新方法

本文采用过硫酸盐氧化树样中的总氮为硝态氮、总磷为磷酸盐,用分光光度法测定总氮量和总磷量,测得结果表明,本法所得精密度和准确度是比较好的,本方法能批量处理样品;省时、省电、省试剂、环境污染少。本法适用于树木中总氮总磷的测量。     

在线正相微孔柱高效液相色谱与傅氏变换红外光谱的联用方法

发展了一种在线正相微孔柱高效液相色谱/傅氏变换红外光谱联用法。它有匹配的接口,适当的联机参数,合理的数据处理方法。用本法成功地实现了对一些模型混合物和实际样品的分析鉴定。实验表明本法可作为复杂有机混合物分析鉴定的有效手段之一。     

火焰原子发射光谱法直接测定矿泉水中锶

本文介绍了用原子吸收光谱仪的发射方式火焰原子发射光谱法直接测定矿泉水中锶。使用钾、钠混合消电离剂和镧释放剂，消除电离干扰和共存元素干扰，本法灵敏度高，可直接测定矿泉水中微量锶。本法准确、可靠，结果令人满意。     

薄层树脂相吸光光度法测定痕量钴的研究

本文提出用薄层树脂相通过光度法测定前量钴的新方法。本法具有灵敏度高,选择性好、速度快等特点。钴离子（Ⅱ）与「４－（５－氯－二吡啶）偶氮」－１,３－二氨基苯生成稳定的有色配合物将其富集在Ｈ型（７３２）阳离子交换树脂上,制作成薄层直接测定,λｍａｘ＝５７１ｎｍ。本法既克服了需特制１ｍｍ比色皿的困难,又提高了测定精密度,使推广精树脂相光度法成为可能。用本法实测了天然水中痕量钴,检出限２．８μｇ·Ｌ＾－１     

Theoretical analysis and simulation of conjugate heights for dual-conjugate AO system in lidar

A multi-conjugate adaptive optics （MCAO） can offer a possibility of widening field of view （FOV） characterized by the isoplanatic angle, and the choose of conjugate height becomes a basic problem for MCAO, which influences the size of iosplanatic angle. Considering the application of lidar, the isoplanatic angle＇s expressions of two deformable mirrors （DMs） MCAO for uplink and downlink are deduced. The effects of conjugate heights for dual-conjugate AO are thoughtfully discussed, and the isoplanatic angles are further analyzed. The results show that the isopanatic angle varies with the conjugate height and reaches the maximum as the conjugate height is at the optimal altitude. Moreover, the optimal conjugate height changes with the propagation distance.     

Quick single-photon detector with many avalanche photo diodes working on the time division

Due to the limit of response speed of the present single-photon detector, the code rate is still too low to come into practical use for the present quantum key distribution (QKD) system.A new idea is put up to design a quick single-photon detector.This quick single-photon detector is composed of a multi-port optic-fiber splitter and many avalanche photo diodes (APDs).Au of the ports with APDs work on the time division and cooperate with a logic discriminating and deciding unit driven by the clock signal.The operation frequency lies on the number N of ports, and can reach N times of the conventional single-photon detector.The single-photon prompt detection can come true for high repetition-rate pulses.The applying of this detector will largely raise the code rate of the QKD, and boost the commercial use.     

Characterization of PolyA and PolyC mismatches by Raman spectroscopy

A.C mismatches are studied by Raman spectral characterization of PolyA, PolyC, and their equimolar complex in solution of 0.14 mol/L Na ,pH7.0.Experimental results show that A·C mismatches occur to be A/B (mainly A) conformers, and unlike Watson-Crick base pairing, this kind of mismatches is stabilized by only one hydrogen bond involving cytosine N4H2 and adenine N7.The formation of A·C complex makes the base stacking interactions much stronger, and conformation of the backbone more ordered, which leads to obvious Raman hypochromic effect with some shifts in corresponding bands.     

Improvement of four-wave mixing-based wavelength conversion efficiency in dispersion shifted fiber by 40-GHz clock pumping

40-GHz clock modulated signal as a pump to improve the efficiency of four-wave mixing (FWM)-based wavelength conversion in a 26.5-km dispersion shifted fiber (DSF) is investigated. The experimental results demonstrate that the conjugated FWM component has higher intensity with the clock pumping than that with the continuous-wave (CW) light pumping. The improvement of FWM-based wavelength conversion efficiency is negligible when the pump power is less than Brillouin threshold. But when the pump power is greater than Brillouin threshold, the improvement becomes significant and increases with the increment of pump power. The improvement can increase up to 9 dB if pump power reaches 17 dBm.     

Multi-pulse operation of a Kerr-lens mode-locked femtosecond laser

Our experimental results show that the presence of a proper amount of negative group velocity dispersion is essential to multi-pulse operation of a Kerr-lens mode-locked femtosecond laser. We demonstrate that the pulse separations and the number of pulses contained within a cavity round trip are strongly dependent on the initial perturbations. The results allow us to get a better understanding on the influences of the convoluted self-phase modulation and intra-cavity dispersions on the stable multi-pulse oscillation in a Kerr-lens mode-locked femtosecond laser.     

Propagation of Helmholtz-Gauss beams in weak turbulent atmosphere

Based on the Rytov approximation of light propagation in weak turbulent atmosphere,the closed-form expressions of field and average irradiance of each one of the four fundamental families of Helmholtz-Gauss (HzG)beams:cosine-Gauss beams,stationary Mathieu-Gauss beams,stationary parabolic-Gauss beams,and Bessel-Gauss beams,which are propagating in weak turbulent atmosphere,are obtained.The results show that the field and average irradiance can be written as the product of four factors:complex amplitude depending on the z-coordinate only,a Ganssian beam.a factor of complex phase perturbation induced by atmospheric turbulence,and a complex scaled version of the transverse shape of the non-diffracting beam.The effect of weak atmospheric turbulence on irradiance distribution of the HzG beam can be ignored.     

An effective method for reducing speckle noise in digital holography

An effective method for reducing the speckle noise in digital holography is proposed in this paper.Different from the methods based on classical filtering technique,it utilizes the multiple holograms which are generated by rotating the illuminating light continuously.The intensity images reconstructed by a series of holograms generated by rotating the illuminating light possess different speckle patterns.Hence by properly averaging the reconstructed intensity fields,the speckle noises can be reduced greatly.Experimental results show that the proposed method is simple and effective to reduce speckle noise in digital holography.     

Influence of purity of HfO2 on reflectance of ultraviolet multilayer

The impurities in two kinds of HfO2 materials and in their corresponding single layer thin films were determined through glow discharge mass spectrum technology and secondary ion mass spectrometry(SIMS) equipment respectively.It was found that ZrO2 was the main impurity in the two kinds of HfO2 either in the original HfO2 materials or in the electron beam deposited films.In addition,the difference of Zr content in the two kinds of HfO2 single laver films was much laxger than that of the other impurities such as Ti and Fe.which showed that it was just ZrO2 that made the difference between the optical performance of the film products including the two kinds of HfO2.With these two kinds of HfO2 and the same kind of SiO2.we deposited HfO2/SiO2 multilayer reflective coatings at the wavelength of 266 nm.Experimental results showed that the reflectances of these two mirrors were about 99.85% and 99.15% respectively,which agreed well with the designed results what were based on the optical constants obtained from the corresponding single layer thin films.     

Speech enhancement by array crosstalk resistant ANC and spectrum subtraction

Microphone array-based speech enhancement has great importance for speech communications and speech recognition. To reduce the aperture of the microphone array and to increase the effect of the speech enhancement will greatly broaden the application areas of the microphone array. An array crosstalk resistant adaptive noise cancellation method is therefore presented. And then an improved spectral subtraction algorithm is further cascaded to obtain better enhancement results. Theoretic analysis and experiments indicate that the proposed scheme needs only a very small microphone array while it simultaneously achieves a higher SNR improvement. Besides, the proposed scheme can be used in many noisy environments and is easy for real-time implementation.