Stressed and unstressed Ge:Ga detector arrays for airborne astronomy

We have constructed and used two dimensional arrays of both unstressed and stressed Ge:Ga photoconductive detectors for far-infrared astronomy from the Kuiper Airborne Observatory (KAO). The 25 element (5×5) arrays are designed for a new cryogenically cooled spectrometer, the MPE/UCB Far-Infrared Imaging Fabry-Perot Interferometer (FIFI). All of the pixels for the stressed array performed well on the first flights with FIFI; 25% of the detectors in the array are more sensitive than our best single element detector, with background limited noise equivalent powers (NEPs)3.0×10^–15 W Hz^–1/2 at 158 m and 40 km s^–1 spectral resolution. The average array element performs within±15% of this value. With a bias field of 0.1 V/cm, the average detector response is 20±6 Amp/Watt at 158 m. The cutoff wavelength and response also compare well with our single element detectors. The unstressed array delivers significantly better performance than our single element detector due to the lower thermal background in the new spectrometer. The average background limited NEp at 88 m and 35 km s^–1 spectral resolution is 7×10^–15 W Hz^–1/2. The least sensitive pixel is only 40% less sensitive. The unstressed array response at 88 m with a bias field of 1 V/cm is 5±1 Amp/Watt. Twenty four of the 25 elements worked on the first flights-on subsequent flights all channels have worked. Some of the exciting new science possible with far-infrared detector arrays is also discussed.     

CKM-XXXX型同轴磁控管工作中突然停振的解决

通过选用一种工作温度较低的阴极,并优化阴极制造和排气处理工艺,基本解决了CKM-XXXX型同轴磁控管工作中突然停振的难题。     

中国原子光谱技术及应用发展近况

原子光谱（atomic spectrometry,AS）技术作为分析领域一个重要的组成部分,是尖端科学快速发展的助推器。随着国家对高新技术的愈加重视,国内的分析检测技术也在飞速发展,原子光谱技术作的发展则成为了极其重要的推动力。对中国原子光谱近4年（2015年-2018年）的研究成果与应用进展做了一个综述,内容主要分为六大部分：原子发射光谱（atomic emission spectrometry, AES）包括电感耦合等离子体发射光谱（inductively coupled plasma optical emission spectrometry, ICP-OES）,辉光放电发射光谱（glow discharge optical emission spectrometry, GD-OES）,介质阻挡放电发射光谱（dielectric barrier discharge optical emission spectrometry, DBD-OES）和激光诱导击穿光谱（laser induced breakdown spectrometry, LIBS）;原子吸收光谱（atomic absorption spectrometry, AAS）包括火焰原子化吸收光谱（flame atomic absorption spectrometry, FAAS）,石墨炉原子化吸收光谱（graphite furnace atomic absorption spectrometry, GFAAS）和氢化物发生原子吸收光谱（hydride generation atomic absorption spectrometry, HGAAS）;原子荧光光谱（atomic fluorescence spectrometry, AFS）;X射线荧光光谱（X-ray fluorescence spectrometry, XRF）;元素质谱（elemental mass spectrometry, EMS）包括电感耦合等离子体质谱（inductively coupled plasma mass spectrometry, ICP-MS）,辉光放电质谱（glow discharge mass spectrometry, GDMS）,激光电离源质谱（laser ionization mass spectrometry, LIMS）和原子探针层析成像（atom probe tomography, APT）;原子光谱分析的联用技术。主要关注了各个技术及各种联用技术在仪器设备、检测方法、检测性能上的突破和创新,并简要介绍它们在电子、冶金、地质、环境、制药、食品、生命科学等多种领域中的应用。     

具有时滞的Volterra反应扩散差分方程的稳定性

本文考虑一类时滞Volterra反应扩散差分方程的初边值问题的正稳态解的稳定性。利用上下解方法和单调迭代方法得到了每一个解趋于方程的正稳态解的充分条件。     

Recent advances in analytical chemistry--a material approach

Advancements of materials research have profound direct impacts on developments in analytical chemistry and may hold the key to improvement of existing or new techniques at present times and near future. Applications of materials in analytical chemistry are reviewed, with focus on sensors, separations and extraction techniques. This review aims to survey examples of interesting works carried out in the last five years over a broad spectrum of materials classified as hybrids, nanomaterials and biomolecular materials.     

Complete1H- and13C-NMR spectroscopic assignment of two pentadecapeptides by reverse C,H correlation techniques

Summary Two oligopeptides representing a wild type and a modified version of the polyprotein cleavage region for proteinase2 A of the human rhinovirus type 2 (HRV 22 A) have been investigated using homo- and heterocorrelated 2 D NMR spectroscopy. Proton-detected C,H correlation techniques turned out to be extremely useful for sequential resonance assignment. In one case, the complete amino acid backbone could be analyzed without using NOESY spectra, thus avoiding ambiguities inherent to this method. No defined tertiary structure of the cleavage region could be detected in either molecule. However, one of the oligopeptides is present to a very low extent in a conformation different from therandom-coil arrangement.

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Vollständige¹H- und¹³C-NMR-spektroskopische Zuordnung von zwei Pentadecapeptiden mittels invers detektierter C,H-Korrelationstechniken

Zusammenfassung Zwei Oligopeptide, die die native Spaltregion für die Proteinase2 A des humanen Rhinovirus von Serotyp 2 (HRV 22 A) beziehungsweise eine modifizierte Version repräsentieren, wurden mit Hilfe von homo- und heterokorrelierter 2 D-NMR-Spektroskopie untersucht. Protondetektierte C,H-Korrelationstechniken erwiesen sich als außerordentlich hilfreich bei der sequenziellen Zuordnung. In einem Fall konnte das gesamte Aminosäureskelett ohne Zuhilfenahme von NOESY-Spektren analysiert und damit die dieser Methode inhärenten Unsicherheiten bei der Zuordnung vermieden werden. In keinem der beiden Moleküle konnte eine definierte Tertiärstruktur der Spaltregion ermittelt werden. Eines der beiden Oligopeptide liegt jedoch zu einem sehr geringen Prozentsatz in einer von derrandom-coil Anordnung abweichenden Konformation vor.

     

小样本下的金融风险测度的技术研究

在金融风险管理技术的研究中,如何通过总体的小样本信息对总体风险特性给出定性、定量分析,具有十分重要的理论意义和实践意义。本文通过对W eibull分布的小样本拟合技术的研究,给出了一种可应用于金融市场风险管理技术的风险测度技术方法,同时利用实证数据分析例示其应用价值。     

应用于探地雷达成像ImgSoftGPR

介绍了用于探地雷达成像的Ｗｉｎｄｏｗｓ应用软件ＩｍｇＳｏｆｔＧＰＲ中的时域聚集方法，给出成像前应进行的各项预处理措施，如直达波消除，反卷积，距离补偿，角度补偿，波达时刻估计等，并研究了电磁波在地下的传播速度的估计，最后利用模拟结果和实测结果验证了软件中时域聚集方法的有效性。     

On some accurate finite-difference methods for laminar flame calculations

The ozone-decomposition flame has been studied by means of fourth- and second-order accurate schemes. The fourth-order methods include a method of lines, a time-linearization algorithm, and a majorant operatorsplitting technique. The second-order schemes include two time-linearization methods which use different temporal approximations. It is shown that the fourth-order techniques yield comparable results to those obtained with very accurate finite element and adaptive grid finite-difference algorithms. The results of the second-order methods are in good agreement with second-order explicit predictor-corrector methods but predict a lower flame speed than that obtained by means of fourth-order techniques. It is also shown that the temporal approximations are not as important as the spatial approximations in flame propagation problems characterized by the presence of several small time scales.     

Hybrid Wavelength and Code Division Multiple Access in Optical Networks

A review of schemes for multiple access in fiber optic networks shows that a hybrid of wavelength and code division multiple access (WCDMA) combines the best features of both. In particular, the hybrid scheme retains the large information carrying capacity of wavelength division multiple access (WDMA) and flexibility of code division multiple access (CDMA). In this paper WDMA, optical CDMA (OCDMA), and WCDMA networks are discussed. In OCDMA networks, concept of incoherent and coherent coding including inverse decoding and matched filter is introduced. The delay performance of both WDMA and WCDMA networks, under the simple suboptimum access protocols based on cyclic search, is computed. It has been shown quantitatively that tuning delay significantly affects the delay performance of both WDMA and WCDMA networks. Futhermore, delay performance of WCDMA networks is always better than the WDMA networks for the same tuning delay, load, and number of users.