基于扩频码的单载波迭代频域均衡水声通信

单载波时域均衡在长时延扩展水声信道中计算量大,并对接收机参数的选择较为敏感,可靠性低,而正交频分复用信号峰均功率比高、对频率偏移敏感. 针对这些问题,提出基于扩频码的单载波块传输高速率水声通信方法和基于T/4分数间隔迭代频域均衡的接收机算法. 该接收机利用已知扩频码进行信道估计以及对由多普勒偏移引起的旋转相位进行估计,并通过一种低复杂度迭代频域均衡算法改善系统性能. 开展了湖上实验研究,结果表明在浅水1.8 km距离且复杂多径干扰条件下,利用BPSK/QPSK调制可实现10^-2–10^-4的误码率并达到1500–3000 bit/s的有效数据率. 关键词： 水声通信 单载波 频域均衡 迭代处理     

Effect of gasketing and assembly design: a novel 10/3.5 mm multi-anvil assembly reaching perovskite pressures

A new design of multi-anvil assembly and modified gasket characteristics with octahedron and truncation edge lengths of 10 and 3.5 mm is presented for reaching pressures and temperatures over 24 GPa and 2000 °C, respectively. Partially dehydroxylated pyrophyllite half-gaskets with a tapered design fully nesting the octahedron have been employed to prevent excessive octahedron extrusion between the cubes. The assembly utilizes an axially placed thermocouple through the octahedral center, allowing two samples to be present at identical high P–T conditions on either side of the thermocouple during a run. A third sample can be used as a packing around the thermocouple, so long as that sample is inert with respect to the thermocouple and surrounding material. The temperature gradient within the sample locations has been well characterized using two-pyroxene thermometry in the CaO–MgO–SiO₂ system and numerical modeling calculations. The results indicate a good agreement in gradient shape, although the numerical model appears to under-estimate the magnitude of temperature change. The assembly maintains stable temperatures and provides low failure rates.     

Isotopenverdünnungsanalytische Multielementanalyse mit der Funkenquellen-Massenspektrographie

Es wird ein Verfahren zur Isotopenverdünnungsanalyse mit stabilen Isotopen unter Verwendung einer Funkenionenquelle und einem doppelfokussierenden Massenspektrographen beschrieben, welches die gleichzeitige Analyse mehrerer Elemente in pulverförmigen Feststoffen erlaubt.

Die Leistungsfähigkeit des Analysenverfahrens wild am Beispiel der Spurenanalyse geologischer Standardproben demonstriert.

Das Analysenverfahren erlaubt die Bestimmung von Spurenkonzentrationen bis in den ppb-Bereich mit Standardabweichungen zwischen 2 und 10%.     

Research on the passive nuclear level gauge

ABSTRACT

Using the ‘quadruple combination detection’ automatic calibration method to solve the traditional passive nuclear ash hopper material level meter calibration problem. The method adopts the ‘contour multistage measurement’ mode, fitted the ratio of absorbed dose rate detected by adjacent cascade probe with corresponding actual material level after measurement, then use the fitting parameters to calibrate automatically which do not need ash hopper stop working, And this can effectively save the calibration time and cost. The method can effectively eliminate the material level measuring error brought by the changes of radioactive activity in the coal ash, which improve the measuring precision and material level positioning accuracy. There are many factors affecting the radioactive activity of coal ash which vary in Different feeding period, or after refueling. And this may cause measurement error and misinformation. Using quadruple combination detection and contour multistage measurement mode, when the radioactive activity in the coal ash changes, the passive nuclear meter level gauge can be revised according to the calibration curve or calibrated automatically. Which eliminated the effects brought by the changing of coal ash radioactive activity, saved onerous repeatedly calibration procedure, also improve the accuracy of the calibration, avoid misjudgment, and can improve the accuracy of measurement.     

Wavenumber Calibration of CCD Detector Raman Spectrometers Controlled by a Sinus Arm Drive

Abstract

The calibration procedures needed for use of dispersive Raman spectrometers have been reviewed. Like other high‐precision spectrometers incorporating moving gratings, Raman spectrometers are subject to problems with wavenumber scale accuracy. Commercially available Raman spectrometers of types DILOR‐HORIBA LabRam and RENISHAW System 1000 have been examined for wavenumber scale stability, linearity, and reproducibility. For reliable use of the wavenumber data, daily calibration is a necessity. A procedure to examine the linearity of such mechanical drive systems is presented. A new finding was that the examined spectrometers give wavenumber calibration errors that were quite reproducible from day to day at a given temperature in the laboratory but depended markedly on the selected setting of the gratings. Knowledge of this linearity problem is essential for obtaining a reliable calibration. The most correct calibration was obtained by the use of certain “golden” settings of the sinus drive at a constant temperature of the laboratory. In this way, the examined spectrometers could be used with better precision, without daily calibration, provided the temperature of the room was constant or corrected for. A procedure for correction of these errors by the software is suggested.     

含k-次增生算子的非线性方程的迭代程序

建立了一般Banach空间中含k-次增生算子的非线性方程的带混合误差的Ishikawa迭代序列的强收敛性的一般性定理,所得的是任卫云等和LIU Li-shan等于最近得到的主要结果的多方面的拓广和改进,且所用方法不同于他们．     

The High Energy X-ray telescope (HE) onboard the Insight-HXMT astronomy satellite

The Insight-Hard X-ray Modulation Telescope(Insight-HXMT) is a broadband X-ray and γ-ray(1-3000 ke V) astronomy satellite. One of its three main telescopes is the High Energy X-ray telescope(HE). The main detector plane of HE comprises 18 Na I(Tl)/Cs I(Na) phoswich detectors, where Na I(Tl) is used as the primary detector to measure ~ 20-250 ke V photons incident from the field of view(FOV) defined by collimators, and Cs I(Na) is used as the active shielding detector to Na I(Tl) by pulse shape discrimination. Additionally, Cs I(Na) is used as an omnidirectional γ-ray monitor. The HE collimators have a diverse FOV,i.e. 1.1°×5.7°(15 units), 5.7°×5.7°(2 units), and blocked(1 unit). Therefore, the combined FOV of HE is approximately5.7°×5.7°. Each HE detector has a diameter of 190 mm resulting in a total geometrical area of approximately 5100 cm2, and the energy resolution is ~15% at 60 ke V. For each recorded X-ray event by HE, the timing accuracy is less than 10 μs and the deadtime is less than 10 μs. HE is used for observing spectra and temporal variability of X-ray sources in the 20-250 ke V band either by pointing observations for known sources or scanning observations to unveil new sources. Additionally, HE is used for monitoring the γ-ray burst in 0.2-3 Me V band. This paper not only presents the design and performance of HE instruments but also reports results of the on-ground calibration experiments.     

Banach空间中关于(H,η)增生算子的变分包含问题

在Banach空间中引进了一类(H,η)增生算子,利用预解算子技巧,建立了一个Ishikawa迭代,并证明了此迭代算法产生的变分包含的解的存在与唯一性。其结果是近期相关结果的改进与推广。     

透射光栅的实验标定和衍射效率的理论模拟

透射光栅广泛应用于软X射线能谱测量.为了获得用于惯性约束聚变研究的透射光栅的各级衍射效率及其他参数,在北京同步辐射源上200—1600 eV能量范围内对其进行了标定,获得了透射光栅衍射效率的实验结果.扩展了透射光栅衍射效率的计算方法,提出了7边准梯形截面衍射效率计算模型.分析拟合了实验数据,理论结果与实验结果很好符合.得到了7边准梯形的透射光栅栅线截面结构. 关键词： 透射光栅 衍射效率 实验标定 光栅模型     

基于特征圆单目视觉的飞机舵面角位移标定技术

提出了一种基于特征圆单目视觉的非接触式飞机舵面角位移标定技术。用一台数码摄像机对固定在飞机舵面上的特征圆进行拍照,经数字图像处理后确定五个特征点的坐标,利用针孔成像和射影变换原理建立物像空间坐标解算模型,计算出特征圆的法线相对方向和圆心的相对位置,舵面角位移由该圆的法线方向确定。仿真结果表明,该方法具有标定过程简单、实时、快速和准确的特点,标定精度可达到0.1°。该技术也可用于航天器上实时测量交会对接时的相对位姿参数。