A multi-beam ion/electron spectra-microscope design

This paper presents the design of a multi-beam charged particle instrument that simultaneously focuses electrons, gallium, oxygen and cesium ions onto the same sample. In addition, the instrument has provision to capture the spectra of both secondary electrons and ions in parallel. The mass spectrometer part of the instrument is expected to detect and identify secondary ion species across the entire range of the periodic table, and also record a portion of their emitted energy spectrum. The electron energy spectrometer part of the instrument is designed to acquire the entire range of scattered electrons, from the low-energy secondary electrons through to the elastic backscattered electrons.     

双腔热解光腔衰荡光谱仪测量大气中NO2和RNO2

A two-channel thermal dissociation cavity ring down spectroscopy (CRDS) instrument has been built for in situ, real-time measurement of NO₂ and total RNO₂ (peroxy nitrates and alkyl nitrates) in ambient air, with a NO₂ detection limit of 0.10 ppbv at 1 s. A 6-day long measurement was conducted at urban site of Hefei by using the CRDS instrument with a time resolution of 3 s. A commercial molybdenum converted chemiluminescence (Mo-CL) instrument was also used for comparison. The average RNO₂ concentration in the 6 days was measured to be 1.94 ppbv. The Mo-CL instrument overestimated the NO₂ concentration by a bias of +1.69 ppbv in average, for the reason that it cannot distinguish RNO₂ from NO₂. The relative bias could be over 100% during the afternoon hours when NO₂ was low but RNO₂ was high.     

A sensitivity study on spectroscopic parameter accuracies for a mm/sub-mm limb sounder instrument

The purpose of this paper is to perform a detailed error analysis for a mm/sub-mm limb sounding instrument with respect to spectroscopic parameters. This is done in order to give some insight into the most crucial spectroscopic parameters and to work out a list of recommendations for measurements that would yield the largest possible benefit for an accurate retrieval. The investigations cover a variety of spectroscopic line parameters, such as line intensity, line position, air and self broadening parameters and their temperature exponents, and pressure shift. The retrieval process is performed with the optimal estimation method (OEM). The OEM allows one to perform an assessment of the total statistical error, as well as of the model parameter error, such as the error coming from spectroscopic parameters. The instrument parameters assumed are those of the MASTER instrument studied by the European Space Agency, one of the candidate instruments for a future atmospheric chemistry mission. However, the same principle and method of analysis can be applied to any other millimeter/sub-millimeter limb sounding instrument, for instance the Japanese instrument JEM/SMILES, the Swedish instrument Odin, and the Earth Observing System Microwave Limb Sounder. We find that an uncertainty in the intensity of the strong lines give an error of similar magnitude on the retrieved species to which the lines belong. Uncertainties in the line position have overall a small impact on the retrieval, indicating that the line positions are known with sufficient accuracy. The air broadening parameters and their temperature exponents of a few strong lines dominate the error budget. On the other hand, the self broadening parameters and the pressure shifts are found to have a rather small impact on the retrieval.     

目标差分吸收光谱技术测量大气NO2平均浓度的方法研究

介绍了一种测量近地面大气NO₂平均浓度的新方法——目标差分吸收光谱方法,即target DOAS(target difference absorption spectrum technology)。该方法基于被动差分吸收光谱技术,测量墙体、山体等目标的太阳反射光谱,通过差分吸收光谱算法反演得到目标与仪器之间NO₂浓度沿路径的积分值SCD(slant column density),同时仪器到目标之间的距离已知,并通过选取特定的参考光谱扣除目标到大气顶层的痕量气体吸收,最终计算出仪器和目标之间的大气NO₂平均浓度。利用建立的目标DOAS系统在合肥开展了观测实验,成功获取了观测地大气NO₂浓度。观测结果与主动长光程差分吸收光谱仪观测数据进行对比,二者呈现较好的一致性,验证了该方法的可行性。     

A Future Millimeter/Sub–Millimeter Radiometer for Satellite Observation of Ice Clouds

The instrument concept of a future spaceborne millimeter/sub-millimeter radiometer is proposed in this paper for the remote sensing of ice clouds from satellite. The proposed radiometer is expected to operate at a series of frequencies within the millimeter and sub-millimeter wave range from 150 to about 900 GHz. Five frequencies are selected in the atmospheric windows, i.e., 150, 220, 463, 683, 874 GHz, and at each frequency there are two orthogonally polarized channels. Three water vapor channels located close to 183.31 GHz are also included in this instrument, since they can provide water vapor information, which is needed for ice cloud parameter retrieval. To simplify system design and test, a modular design philosophy is followed in the receiver frontend design and two antennas are used separately for the millimeter and sub-millimeter channels. Overall, the instrument requirements can be met with today's technology, except for the channels at the highest frequencies, where the radiometric sensitivity can be larger than the required 1.0 K for the 10 km spatial resolution (2.5 ms integration time). However, this situation can be improved by averaging neighboring pixels in data processing if certain compromise in the spatial resolution can be made at these frequencies.     

Physics-based modeling techniques of a twelve-string Portuguese guitar: A non-linear time-domain computational approach for the multiple-strings/bridge/soundboard coupled dynamics

The Portuguese guitar is a pear-shaped instrument with twelve metal strings which is widely used in Portuguese traditional music. Unlike most common guitars, it has a curved top-plate and a specific violin-like bridge which is not rigidly fixed to the soundboard of the instrument. From the dynamical point of view, if the bridge transmits the strings vibrations to the instrument body in order to maximize the radiated energy, it also couples all the component parts of the instrument which therefore interact by structural coupling. This can originate various audible effects such as beating behavior and the excitation of numerous sympathetic resonances enhanced by the large number of strings of the instrument, and this is certainly why the Portuguese guitar has such distinct sound compared to other guitars. In this paper, a fully coupled time-domain model of the Portuguese guitar is developed and a series of simulations are presented to emphasize the various coupling phenomena involved in sound production. To reproduce the main musical features, the model includes the coupled dynamics of the twelve strings supported by a bridge which interact with the body of the instrument, described through Finite-Element modeling of the soundboard of a typical Portuguese guitar. Further simple models have been devised for the string/fret interaction and the pluck excitation. Since nonlinear effects are quite apparent in the behavior of string musical instruments, the string dynamics is modeled by the Kirchhoff–Carrier equations which describe large-amplitude string vibrations, and includes the coupling between both polarizations of string motion. The coupling between the strings and the soundboard at the bridge is provided by a model of the bridge kinematics, built on the basis of simple geometrical rationale, so that the two perpendicular string motions can exchange energy back and forth. By a close examination of the energy transfers between the various subsystems of the model, we first assess the correct behavior of the physical model and then examine the respective influence of the string nonlinearity and the bridge on the nonplanar motion of the string. The fully coupled model which pertains to the restricted group of studies which deals with the complete physical-based modeling of a multi-stringed instrument, captures many important phenomena observed in practice, among which the pitch glide effect and the mutual excitation of sympathetic vibrations.     

Development of a compact CO2 sensor based on near-infrared laser technology for enological applications

This paper reports the development of an infrared laser spectrometer using commercial diode laser emitting at 2.68 μm. The instrument is designed to measure CO₂ concentrations above a glass poured with a sparkling liquid, such as beer or champagne in the present case. This spectrometer was developed in order to realize the cartography of CO₂ outgassing in the headspace above various glasses. We provide details of the instrument design and data processing. Absorption lines were carefully selected to minimize interferences from neighboring water vapor transitions. The instrument performance allows to measure ambient CO₂ concentrations so that one can be very confident in the CO₂ concentrations measurements above the glass. Some preliminary results on sparkling liquids such as beer and champagne are presented and compared to a model describing the flux of CO₂ discharging from glasses due to the contribution of bubbles.     

Reproducibility of optically stimulated luminescence measurements from single grains of Al2O3:C and annealed quartz

We have measured some aspects concerning the performance of a new instrument for the measurement of optically stimulated luminescence (OSL) from single sand-sized grains. The instrument uses a solid-state laser to stimulate OSL from each grain individually. These grains are placed in a regular grid of nine-by-nine holes, which are drilled in the sample disc. We report on tests carried out to determine the precision with which the laser beam can be directed at individual grains in these holes. Single grains of aluminium oxide (Al₂O₃:C) (90–180 μm) and annealed quartz (90–120 μm) were used to test the reproducibility with which the OSL signal can be measured. These experiments suggest that the laser beam can be positioned to within 30 μm and that the reproducibility of OSL measurement is 3.5% on an average.     

N2O and O3 arctic column amounts from PARIS-IR observations: Retrievals, characterization and error analysis

Ground-based solar absorption infrared spectra were recorded in the Canadian Arctic during the early spring of 2004 using a moderate-resolution Fourier transform spectrometer, the Portable Atmospheric Research Interferometric Spectrometer for the Infrared (PARIS-IR). As part of the Canadian Arctic Atmospheric Chemistry Experiment (ACE) validation campaign, the PARIS-IR instrument recorded solar absorption spectra of the atmosphere from February to March 2004 as the Sun returned to the Arctic Stratospheric Ozone Observatory (AStrO) near Eureka, Nunavut, Canada (80.05°N, 86.42°W). In this paper, we briefly outline the PARIS-IR instrument configuration and data acquisition in the high Arctic. We discuss the retrieval methodology, characterization and error analysis associated with total and partial column retrievals. We compare the PARIS-IR measurements of N₂O and O₃ column amounts with those from the Fourier transform spectrometer (ACE-FTS) onboard the Canadian SCISAT-1 satellite and the ozonesonde data obtained at Eureka during the validation campaign.     

光腔衰荡光谱法测量大气中的NO3和N2O5

本文应用基于二极管激光器的双路光腔衰荡光谱技术,分别对大气中NO₃和N₂O₅浓度进行监测. 通过使用实验室标准样校正有效吸收腔长比R_L和系统的总损耗系数?,并获得了NO₃有效吸收截面. 该装置在时间分辨率为1 s时,对NO₃的测量灵敏度达到1.1 pptv,N₂O₅被在线转换成NO₃,从而被另一路光腔衰荡光谱装置探测. 利用该装置,对合肥市区冬季夜间大气中的NO₃,N₂O₅浓度进行了实时监测. 通过对比一次大气快速清洁过程中氮氧化物、臭氧、PM_2.5等组分的浓度变化,讨论了大气环境下可能影响NO₃及N₂O₅浓度的因素.     

基于虚拟仪器及PXI技术的传感器标定

为了借助虚拟仪器技术实现对叶轮机械各种测试技术的集成,本文将虚拟仪器及PXI技术运用于传感器的标定中。文中阐述了基于虚拟仪器及PXI技术的传感器静态特性标定系统的结构、标定方法、数据处理以及被标定传感器的静态特性指标,并与传统仪器组成的标定系统进行了比较。结果表明,基于虚拟仪器及PXI技术的传感器静态特性标定系统,比用其它手段更精确、快捷和方便,为虚拟仪器在叶轮机械试验测试中的进一步应用打下了基础。     

Cu2O/C60梯度薄膜的制备

 功能梯度材料应用前景广阔,特别在ICF研究中,梯度靶是一种重要的基础-基准靶。以Cu₂O和C₆₀为原料,用真空蒸镀法在石英基底上制备了Cu₂O/C₆₀梯度薄膜,并用XPS, AFM, 紫外光谱仪对其成份分布、表面形貌、紫外吸收谱进行了测试。测量结果表明,薄膜的组成沿厚度方向呈连续梯度变化,符合梯度功能材料的变化规律。     

Optical constants of DUV/UV fluoride thin films

High-refractive-index materials LaF3, NdF3, and GdF3 and low-refractive-index materials MgF2, A1F3, and Na3A1F6 single thin films are deposited by a resistive-heating boat at different depositing rates and specific substrate temperatures on single crystal MgF2 substrates. Transmittances of all fluoride thin films are measured using commercial spectrometer in the ambient atmosphere and under vacuum using synchrotron radiation instrument in the wavelength region from 190 to 500 am. The optical constants of these materials are determined by envelope method and iterative algorithm on the basis of transmittance measurements.     

A correlated-k model of radiative transfer in the near-infrared windows of Venus

We present a correlated-k-based model for generating synthetic spectra in the near-infrared window regions, from 1.0 to 2.5 μm, emitted from the deep atmosphere of Venus on the nightside. This approach is applicable for use with any near-infrared instrument, ground-based and space-borne, for analysis of the thermal emissions in this spectral range. We also approach this work with the view of using the model, in conjunction with a retrieval algorithm, to retrieve minor species from the Venus Express/VIRTIS instrument. An existing radiative-transfer model was adapted for Venusian conditions to deal with the prevailing high pressures and temperatures and other conditions. A comprehensive four-modal cloud structure model based on Pollack et al. [Near-infrared light from venus’ nightside: a spectroscopic analysis. Icarus 1993;103:1-42], using refractive indices for a 75% H₂SO₄25% H₂O mixture from Palmer and Williams [Optical constants of sulfuric acid; application to the clouds of Venus? Appl Opt 1975;14(1):208-19], was also implemented. We then utilized a Mie scattering algorithm to account for the multiple scattering effect between cloud and haze layers that occur in the Venusian atmosphere. The correlated-k model is shown to produce good agreement with ground-based spectra of Venus in the near infrared, and to match the output from a line-by-line radiative-transfer model to better than 10%.     

神舟3号飞船中分辨率成像光谱仪场地替代定标新方法研究

神舟3号飞船(SZ-3)搭载的中分辨率成像光谱仪(CMODIS)是我国下一代对地环境卫星遥感器的试验仪器,能获取地气系统30个可见光-近红外通道观测数据,这些高光谱数据应用,特别是定量遥感产品反演受到辐射定标的严重制约。文章在传统的在轨遥感器场地辐射校正基础上,提出了星地准同步观测场地辐射校正新方法,在缺少足够地面同步观测数据情况下,实现了CMODIS场地辐射校正,并达到了预期辐射校正精度要求。同时基于敦煌场地反射率光谱光滑的特点,利用EOS/MODIS大气订正后的通道反射比进行光谱内插,开展一种新的交叉定标方法试验。文章针对SZ-3/CMODIS数据,用此两种方法独立进行场地替代定标,试验结果能够相互验证,表明这两种定标方法切实可行,定标精度可靠,为我国下一代环境气象卫星传感器在轨辐射定标提供了新的定标方法和技术。     

Vocal Fold Polyp in a Professional Brass/Wind Instrumentalist and Singer

Wind instrumentalists, especially brass players, and singers share common factors, including vocal tract shape, function and pressure, vocal fold opening and closure, breath vector of force and air flow rates. To understand the mechanism and function of the vocal folds with a pathological lesion, it is necessary to visualize the differing interactions of the vocal tract during wind and brass instrument playing and in singing. A school band director, singer, wind and brass instrumentalist, was referred by musician colleagues with intermittent dysphonia, aphonia, and inability to sing high notes. Simultaneous videolaryngoscopy, with and without stroboscopy, and external video examination were documented. An hourglass glottis with a sessile, cystic polyp of the left vocal fold were recorded and studied during phonation and the playing of 3 instruments. The techniques of glottic opening, closure, configuration and function varied with the type of instrument and phonatory function. Singing was adversely affected by the vocal fold polyp but no harmful interaction occurred during wind/brass instrument playing. Down-stream loading in singers is at the laryngeal level and in wind/brass instrumentalists is at the embouchure. Preoperative voice therapy, phonomicrosurgery, and postoperative voice rest followed by voice therapy, succeeded in restoring her combined wind/brass instrumental and singing career.     

基于多轴差分光学吸收光谱测量北京地区对流层NO2的研究

由于二氧化氮（NO₂）在大气的物理和化学机制进程中有着十分重要的作用,并且对环境、气候以及人体健康产生影响,合理、有效地监测和控制大气中NO₂浓度已成为十分重要的课题。地基多轴差分吸收光谱（MAX-DOAS）仪是利用太阳散射光的被动DOAS仪器,相较于小范围测量的点式仪器、利用光源和反射装置的主动DOAS仪器,具有时间分辨率高、高灵敏度、测量范围广和不受搭建平台制约等优势特点。2018年在北京中国气象科学研究院（116.32°E,39.95°N）开展了基于地基MAX-DOAS的对流层NO₂全年连续观测,采集得到原始吸收光谱并运用光谱处理软件QDOAS进行反演得到NO₂斜柱浓度（SCD）,选择较为简单的几何近似方法计算求出大气质量因子（AMF）,从而将NO₂SCD转换为垂直柱浓度（VCD）,据此研究分析了北京地区NO₂VCD月均值和季节均值变化、季节的日平均变化以及一周内日平均变化的特征。结果表明,北京地区对流层NO₂VCD随季节变化较为明显,呈现冬季最高而夏季最低的趋势,其中冬季季节均值达到2.94×1016 molec·cm-2,为夏季的1.6倍,不同季节的日均变化一般在下午表现出明显的差异,最大相差为2.17×1016 molec·cm-2。一周内每日的浓度变化有一定规律性,周日平均浓度较其他时间降低17%左右,出现了一定程度的周末效应。通过将地基MAX-DOAS观测结果和地面国控站点官园监测站（116.339°E,39.929°N）2018全年数据结果进行对比,显示出两者变化趋势具有好的一致性,相关系数r可达0.81。研究表明,地基MAX-DOAS不仅可以对区域污染气体如NO₂的实时快速监测及变化规律的研究分析提供一种有效手段,也可以对其他数据来源进行校验。     

基于GPS/BD的高精度授时关键技术研究*

Aim at the problem that the precision of the past satellite communication terminal system isn't high, designed a system that can provide accurate and standard PPS and timing information for the testing instrument of precision time, used the idea of high-stability GPS system and high-reliability BD system to design a dual-model redundance system, FPGA and DSP are used as a central control core, combined the key technology of undamaged dual-model timing, the placeholder optimization of BNC and optimizing of PPS model, provided a unified time standard for all kinds of ground testing control equipments to ensure the high-precision synchronization on time among testing control equipments. Testing results show that this system can provide 20ns PPS of the average accuracy for time interval measuring instrument, and the reliability is high.     

KLYPVE/TUS space experiments for study of ultrahigh-energy cosmic rays

The KLYPVE space experiment has been proposed to study the energy spectrum, composition, and arrival direction of ultrahigh-energy cosmic rays (UHECR) by detecting from satellites the atmosphere fluorescence and scattered Cherenkov light produced by EAS, initiated by UHECR particles. The TUS setup is a prototype KLYPVE instrument. The aim of the TUS experiment is to detect dozens of UHECR events in the energy region of the GZK cutoff, to measure the light background, to test the atmosphere control methods, and to study stability of the optical materials, PMTs, and other instrumental parts in space environment.