应用单相流量计测量油水两相流

为探讨单相流量计用于液液两相流参数测量的可行性和有效性,本文对文丘里管、涡轮流量计和椭圆齿轮流量计用于油水两相流测量的响应特性进行了实验研究.文丘里管和涡轮流量计的实验管径为15 mm,25 mm,40 mm,椭圆齿轮流量计的实验管径为25 mm和40 mm.油水两相流总体积流量范围为1～5 m3/h,油含率范围为15%～85%.实验结果表明,文丘里管在高油含率时测得的油水两相流流量比实际流量偏大4%～5%.涡轮流量计的测量误差随油含率升高呈现增大的趋势,最大测量洪差小于5%.椭圆齿轮流量计用于油水两相流测量时相对测量误差小于1.0%且基本不受油含率影响.     

取样管型流分相式气液两相流体流量计

提出了用取样管来组成一种分流分相式气液两相流体流量计,通过取样管从被测两相流中成比例地分流出一部分气液混合物,然后应用-小型分离器将其分离成单相气体和液体,并用单相流量计分别测量它们的流量,最后根据测量值计算被测两相流体的各相总流量.文中给出了这种两相流体流量计的组成原理,分流系数特性及实验结果.研究结果表明,取样管的端口形状对分流系数的特性影响较大,其中S型端口的效果较理想,能够在较宽的测量范围内保持分流系数的稳定.     

一种新的气液两相流体流量计-三通管型分流分相式两相流体流量计

利用三通管的相分离特性,从被测气液两相流体中分流分离出一部分单相气体,通过测量这部分单相气体的流量计算被测气液两相流体的流量或干度.文中给出了这种分流分相式气液两相流体流量计的组成原理,分流系数特性及实验结果.     

应用多传感器时间融合的塞状流测量研究

气液两相流由于其自身的复杂性,流型、流量等流动参数的测量一直是研究的重点和难点.应用多传感器数据融合技术测量气液两相流可以从多角度揭示流体信息,提高流动参数的测量精度.多传感器系统主要由截面信息测量系统和V型内锥式流量计构成,在利用相关技术对截面测量信息与V型内锥式流量计的测量数据进行时间融合的基础上,对水平管气液塞状流经行了分段式的流量测量.测量中将气塞和液塞分开计算,并引入了等效干度的计算,通过对实验结果进行的误差比较,验证了该方法是可行的,而且能一定程度上提高测量精度.     

高含气率油气水多相流流量计算模型研究

针对目前截面含气率超过80%的油田多相流流量计量中普遍存在的总质量流量和分相流量计量精度低等问题,利用经典文丘里流量计和相参数传感器在多相流实验装置上对油气水三相流流量计算模型进行了研究,改进了传统的文丘里多相流计算模型,建立了基于干度和滑速比的高含气率多相流流量计算模型。实验结果表明,本文提出的高含气率下多相流流量计算模型具有较高的精度,从而为现场高含气率多相流计量提供了一种新的方法。     

基于滑速比的气水两相流气相流量计算方法研究

目前对气水两相流的分相流量的研究中,多是针对两相流总流量和液相分相流量进行,对气相分相流量的研究很少.本文利用文丘里管和含气率传感器对空气水两相流气相流量计算方法进行了研究,在均相流模型基础上考虑了滑速比因素造成的影响,探讨了两相流气相流量计算方法.结果表明,该方法相对于传统的均相流模型在计算精度上得到了显著提高.     

Coriolis流量计在油水两相流中的误差特性研究

在油水两相流实验回路上,用Coriolis质量流量计对油水两相流中的流量和含水率的误差特性进行了实验研究。实测了含水率的相对误差随含水率的变化特性。实验结果也证明质量流量和体积流量的相对误差在含水率0-100％范围内都较小,且在同一含水率下,流量越大,精度越高。实验所用的Coriolis质量流量计通径为25 mm,实验范围为:体积流量1.2 m3/h～2.4 m3/h,含水率0-100％。     

气液两相流相含率测量新方法研究

本文基于电容耦合式非接触电导检测(Capacitively Coupled Contactless Conductivity Detection,C~4D)技术,提出了一种气液两相流相含率测量新方法。该方法基于新型六电极阵列式C~4D传感器,首先获取气液两相流电导信号,然后利用所获电导信号,结合LS-SVM回归方法分别建立三种典型流型(泡状流、环状流和层状流)的相含率测量模型。实际测量时根据流型选择相应的相含率测量模型,计算获得相含率。在内径为47.5 mm管径下进行相含率测量静态实验,研究结果表明,所提出的气液两相流相含率测量新方法是可行、有效的。在三种典型流型下的相含率测量最大绝对误差均小于9%。     

含分液小孔气液分离器冷态实验研究

本文以水和空气的混合物为工质模拟两相流,对含分液小孔气液分离器进行变空气流量、入口干度的冷态实验.通过分析各参数对气液分离器漏液速率和气液分离效率的影响来获得一定分液小孔的气液分离器的较佳运行工况.结果表明空气流量大于0.32 m~3/h、入口干度小于0.25的工况下,漏液速率大于0.18 g/s,分离效率在90%以上。     

方管内气液两相流界面波统计特性分析

以空气、水为工质，利用电导探针测量技术结合统计分析理论研究了水平矩形管内气液两相流界面波特性．首先对管内气液两相流的界面波进行了分类和定义；其次研究了气液两相流界面波在幅域、时域和频域的统计特性，同时考察了界面波特性参数（波速、频率和波高）等随气液两相流量的变化规律．     

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.