Method of increasing the output signal-to-noise ratio in passive multi-element antenna arrays

A method of processing complex signals in passive multi-element antenna arrays based on an analysis of the natural values of the correlation matrix of the signal is considered. By means of the method it is possible to substantially increase the output signal-to-noise ratio. An iterational process by means of which optimal estimators of both the signal and the amplitude-phase distribution may be obtained, is proposed. Theoretical estimators of the efficiency of the method are given. It is proved that, in terms of the efficiency, the approach considered in the article comes close to the technique of matched filtration. Results of statistical modeling that confirm the statistical results are presented.     

The Danish Twin Apartment Study – Part II: Mathematical modeling of the relative strength of sources of indoor air pollution

Abstract This study deals with the modeling of air pollution in apartments from laboratory measurements of source strengths, using formaldehyde and Total Volatile Organic Compounds (TVOCs) as model pollutants. The sources in two test apartments were grouped into two: building-related sources and occupant-related sources. The measured source strengths and ventilation rates were used for the prediction of concentrations expected in the apartments. These predictions were compared to measurements in the apartment over 12 months. The conclusions were that the model predictions based on emission rates measured in the laboratory can be used to predict the long-term concentration of the two model pollutants in the apartments. Considering the measured differences in ventilation between the apartments, an occupant emission rate of between 0.2 and 0.3 mg/h/kg body weight could be estimated. Based on previous suggested limits of acceptable exposures of humans to VOCs, an acceptable average emission rate of VOCs from building materials in general was estimated to be about 30 (μ/m²/h. The modeling showed that during the first 200 days, building materials dominated the emissions. After this, sources relating to the occupants dominated. On average about half of the VOC pollution originated from the building materials.     

遵义后坝奥陶系红花园组油苗岩石轻烃特征分析

遵义后坝奥陶系红花园组生物碎屑灰岩中发现油苗和沥青,经过气/源岩、沥青/源岩对比,震旦、寒武及奥陶系产层轻烃C₆₊₇结构组成基本一致,奥陶系含油苗灰岩轻烃星图与震旦系泥岩、寒武系沥青砂岩星图较为相似,显示红花园组油苗主要来源于震旦系和下古生界过成熟或高成熟海相烃源岩,油气经历了较长距离的运移,得以在奥陶系中保存下来。这对评价该地区油气前景有重要意义,预示着可能存在一套特殊的含油气组合,存在以O₁h古风化壳储集层为目的层的勘探领域。在兴文—叙永一线以西地区现今下古生界储盖组合保存良好,在适当的构造圈闭中可形成油气藏。志留系和二叠系产层轻烃C₆₊₇与震旦系、寒武系及奥陶系等产层轻烃C₆₊₇明显有别,星图对比性差,表征它们之间成烃母质或沉积环境均有不同。      

Pitting corrosion of Cr–Mn–N steel in sulphuric acid media

The resistance to pitting corrosion of austenitic stainless steel Cr18Mn12N has been studied in model solutions of sulphuric acid (0.5 m) containing chloride ions (0.5 m). The cyclic potentiodynamic method has been employed to investigate the effects of chloride ions and agitation rate on the pitting and repassivation potentials. Electron and optical microscopy, electron diffraction spectroscopy and atomic absorption spectrometry have been used to detect the surface sites for pit formation and the growth of pit nuclei. The results obtained with chromium–manganese–nitrogen steel have been compared with those of austenitic Cr18Ni9 stainless steel. A similarity in pit initiation is established, while steel composition exhibits no significant effect. Cr18Mn12N steel is less prone to repassivation as compared with Cr18Ni9 steel.     

北非库弗腊盆地油气成藏条件及地质风险初探

库弗腊盆地是在稳定结晶基底上形成的大型古生代克拉通内坳陷盆地。油气地质评价认为，该盆地发育始寒武系一自垩系的浅海相与河流相交互沉积，依据钻井、露头、孢粉组合可将其沉积序列划分为8套地层单元。推测盆地存在3套烃源岩：始寒武系泥岩、奥陶系泥岩、志留系Tanezzuft组泥岩，其中Tanezzuft组泥岩是盆地最有可能的烃源岩。库弗腊盆地可能存在奥陶系一志留系和始寒武系两套成藏组合，盆地模拟结果表明盆地的两个沉积中心（uri槽和Kalanshiyu槽）的烃源岩已达到生油窗范围，是否存在有效烃源岩是决定该盆地油气潜力的主要因素和油气勘探的最大地质风险所在。图4参18     

小型腔式微波离子源的研制

研制了１种用在离子束细胞刻蚀装置中的小型腔式微波离子源，它由石英放电管、同轴谐振腔和封装在管一端的二电极引出系统组成。该源由同轴腔激发起的表面波在石英管内产生等离子体柱。为了提高柱末端等离子体离子引出流密度，选用了在内径７．０ｍｍ直管的一端加上一内径５．０ｍｍ衬管的放电管。在微波频率为２．４５ＧＨｚ，输入功率为９３Ｗ下，氮的引出流密度分别为４８．４ｍＡ／ｃｍ２和９１．７ｍＡ／ｃｍ２。这种表面波放电等离子体源体积小、结构简单，可在较宽的压强范围内产生重复性好、工作稳定的等离子体柱。     

青城子矿田小佟家堡子金银矿床地质特征及成矿物质来源探讨

小佟家堡子金银矿床赋存在辽河群大石桥组PtLd^5 3和PtLd^4 3的互层带之中。矿体受层间滑脱构造控制。容矿岩石以自云石大理岩和硅质岩为主，矿体呈层就、似层就。矿石中的金以不可见金为主，金古量与毒砂关系最密切。成矿物质来源于地层——即海底火山喷气和喷流作用形成含矿热卤水，经运移在海盆边缘沉积形成矿源层或维集区，经区域变质作用和岩浆作用的改造，在印支期就位。矿床成因类型为同生沉积-变质一岩浆热液叠加再造型金银矿床。     

点阵汉字库到PROTEL元件符号图形库的转换

本文介绍了PROTEL元件符号图形库和点阵汉字库的结构,以及怎样将点阵汉字库转换到PROTEL元件符号图形库的方法。从而提出一种在利用PROTEL设计电路原理图时,加入汉字标注的途经。     

控制过程中的抗干扰研究

以提高控制系统精度为目标，详细分析了现场中各种可能的干扰源及其解决方法     

High concentration erbium doping of silicon-rich SiO2 thin films on silicon

In this work, high concentration erbium doping in silicon-rich SiO₂ thin films is demonstrated. Si plus Er dual-implanted thermal SiO₂ thin films on Si substrates have been fabricated by using a new method, the metal vapor vacuum arc ion source implantation with relatively low ion energy, strong flux and very high dose. X-Ray photoelectron spectroscopy measurement shows that very high Er concentrations on the surfaces of the samples, corresponding to 10 at.% or the doping level of 10²¹ atoms cm⁻³, are achieved. This value is much higher than that obtained by using other fabrication methods such as the high-energy ion implantation and molecular beam epitaxy. Reflective high-energy electron diffraction, atomic force microscopy and cross-section high-resolution transmission electron microscopy observations show that the excess Si atoms in SiO₂ matrix accumulate to form Si clusters and then crystallize gradually into Si nanoparticles embedded in SiO₂ films during dual-ion implantation followed by rapid thermal annealing. Er segregation and precipitates are not formed. Photoluminescence at the wavelength of 1.54 μm exhibits very weak temperature dependence due to the introduction of Si nanocrystals into the SiO₂ matrix. The 1.54-μm light emission signals from annealed samples decrease by less than a factor of 2 when the measuring temperature increases from 77 K to room temperature.