107 resultados para Faisceau arqué (FA)


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The wideband high-linearity mixers for a double conversion cable TV tuner is presented. The up-conversion mixer converts the input signal from 100MHz to 1000 MHz to the intermediate frequency (IF) of I GHz above. And the down-conversion mixer converts the frequency back. The degeneration resistors are used to Improve the linearity. The tuner is implemented in a 0.35 mu m SiGe technology. Input power at 1dB compression point can reach +14.23dBm. The lowest noise figure is 17.5dB. The two mixers consume 103mW under a supply voltage of 5 V.

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This paper presents the design of a wide-band low-noise amplifier (LNA) implemented in a 0.35 mu m SiGe BiCMOS technology for cable (DVB-C) and terrestrial (DVB-T) tuner applications. The LNA utilizes current injection to achieve high linearity. Without using inductors, the LNA achieves 0.1-1GHz wide bandwidth and 18.8-dB gain with less than 1.4-dB gain variation. The noise figure(NF) of the wideband LNA is 5dB, its 1-dB compression point is -2dBm and IIP3 is 8dBm. The LNA dissipates 120mW power with a 5-V supply.

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This paper represents a LC VCO with AAC (Auto Amplitude Control), in which PMOS FETs are used as active components, and the varactors are directly connected to ground to widen Kvco linear range. The AAC circuitry adds little noise to the VCO and provides it with robust performance over a wide temperature and carrier frequency range. The VCO is fabricated in 50-GHz 0.35-mu m SiGe BiCMOS process. The measurement results show that it has -127.27-dBc/Hz phase noise at 1-MHz offset and a linear gain of 32.4-MHz/V between 990-MHz and 1.14-GHz. The whole circuit draws 6.6-mA current from 5.0-V supply.

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本论文从2,3'-联吡啶出发,利用两个吡啶环上氮的反应活性差异,选择性合成了单烷基盐1-甲基-2,3,-联吡啶盐、1-甲基-1,一氧-2,3,-联吡啶盐和1'-甲基/节基2,3气联吡啶盐,还原单烷基盐合成了天然生物碱毒黎碱、安那他品和异毒黎碱及其衍生物:对异毒黎碱的合成由还原N,-节基盐后脱节基简化为一步实现还原和脱节基直接得到异毒黎碱。通过用(R)-BINOL和(S)-BINOL对N,-节基异毒黎碱拆分得到了旋光纯的N,-节基异毒黎碱和异毒黎碱,-N,-节基异毒黎碱的旋光度[a]D20:-61.50(c=2.0,乙醇),卜异毒黎碱的旋光度fa]D20:-14.4"(c-1.0,乙醇);将C关异毒黎碱用(RMTPA和(s)MT队衍生为Mosher酞胺,应用Mosllel方法确定了C)异毒黎碱手性中心的绝对构型为R型,即(R)-C)异毒黎碱,同时发现,由(R)一MTPA合成的Mosller酞胺中顺式旋转异构体占优。而通常在环胺的Mosller酞胺中,是反式旋转异构体占优。这一例外被MollteCarlo模型模拟计算结果解释:稀溶液中C卜异毒黎碱的Moshel-酞胺,顺式构型能量上比反式更有利。不对称合成天然生物碱更具有挑战性。对异毒黎碱还原合成中的呱l淀烯类中间体,用BINAP-灿催化体系进行了催化不对称还原的合成研究,氢化N'-节基-1,,4,,5,,6,-四氢一2,3,一联吡陡时得到了最高为21.5%的对映体选择性,而对N'-节基一1,,2',5',6,-四氢-2,3'一联吡陡的氢化则只得到了不超过10.0%的对映体选择性。

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本工作对糠醇(FA)和FA与三-(2-羟乙基)异氰尿酸酯(THEIC)的缩聚和磺化反应以及产物的结构和抗氧,抗氯稳定性进行了系统的研究。对FA与THEIC表面聚合制备反渗透复合膜具有十分重要的指导意义。由热分析方法研究发现,FAFA与THEIC共缩聚反应过程在DSC谱图上有四个放热反应峰。I、II峰(50~80 ℃)为FA头-尾及头-头醚化脱水线性缩聚反应。III峰(110~130 ℃)为FA缩聚物的端羟甲基与亚甲基脱水反应。IN峰(150~190 ℃)为高温下呋喃甲醚链脱出甲醛,甲醛与亚甲基发生交联反应。催化剂用量的增加有利于羟甲基间脱水醚化反应。FA与THEIC共缩聚反应在150 ℃左右有突变,THEIC参加反应的活性增加。体系中大量硫酸存在对THEIC参加反应不利,同时引起FA缩聚物裂解反应。THEIC的加入可改善FA缩聚物的耐热氧化裂解性能。空气下使起始热失重温度提高了60 ℃;氮气下,起始热失重温度提高80 ℃。FA缩聚物的磺化反应在低温下就开始进行,140 ℃时磺化程度最高。磺化度为0.067个SO_3H/重复单元,离子交换容量(电荷密度)为0.84 meg/g酸型。FA和甲基呋喃齐聚物和其磺化后的~(13)C-NMR分析表明,磺化反应容易发生在端呋喃环与H相连的α位,β位,中间呋喃环β位也可发生磺化反应。磺化反应速度较慢,磺化程度不高。H_2SO_4与FA重量之比大于四分之一时,磺化程度基本不变,H_2SO_4量过高时对产物有裂解作用,因此选择此比例比较适宜。由液体和固体~(13)C-NMR观察到FA缩聚反应过程中,羟甲基于100 ℃基本消失,而呋喃甲醚链生成。产生交联的主要原因是甲醛与亚甲基反应进行的。甲醛也可同呋喃环端αH位和β位发生反应生成羟甲基,羟甲基可继续参加反应使缩聚物产生交联。缩聚物中有明显的端甲基酮、醛和羧酸基的生成。产生的原因如下:FA缩聚物中呋喃环间在较高温度下可发生Diels-Alder反应,裂解色谱-质谱分析检出裂解产物中有CH_3和CH_3等芳香族化合物,证实发生了Diels-Alder反应。FA和甲基呋喃齐聚物在大量硫酸作用下,室温磺化交联产物的固体~(13)C-NMR表明有呋喃环上双键打开的反应。可能为Diels-Alder反应,也可能是环双键打开交联的反应。但形成的温度和反应速度还不十分清楚。FAFA与THEIC缩聚物经过氧化氢氧化裂解产物裂解失重较大,主链发生了断裂反应红外光谱和固体~(13)C-NMR分析表明产生了大量的酮,醛和羧酸。反应过程可能如下:FA缩聚物经游离氯作用后,有少量缩聚物被裂解掉,共缩聚物中脂肪醚被裂解,生成醇,THEIC部分被裂解掉。于是可初步确定FA缩聚物和FA与TEHIC共缩聚物链中的亚甲基和脂肪醚键是易受氧化攻击的弱点。利用表面内反射红外光谱,电子能谱和电子显微镜等对PEC-1000复合膜和试剂复合膜进行了结构与组成剖析,发现PEC-1000膜分离功能层中含有较多伯醇化合物。膜表面含有较多的O, S, N等原子,因此制复合膜的溶液中,THEIC的含量较高,膜的流动电位随压力变化的速率为-4.67mV/atm,膜功能层中含有较多的极性SO_3~-基团。

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本论文通过对计算方法的筛选,把目前被认为是最有前途的多元统计学方法--主组份回归法(PCR)和偏最小二乘法(PLS)以及人们使用较多的CPA矩阵法固较为成熟的,且普遍使用的光度分析有机地结合在一起,对多组份混合体系进行了同时测定的应用研究。并详细阐述了多元线性回归方法(MLR)、PLS、PCR方法的基本数学原理,继而又以运行速度较快的FORTRAN语言分别编制了CPA矩阵法,PCR法,PLS法的计算机程序,实现了对光谱数据矩阵和校准浓度矩阵的计算机全处理过程,获得了预期的效果。经过它们处理计算的几个多组份混合体系的同时测定,也都取得了满意的结果。本文还通过对CPA矩阵法,PCR法和PLS法的计算测定的比较,归纳总结了它们各自的优缺点,并在校准样品的系列统计设计。以交叉证实法(Cross-Validation)确定最佳校准模型的因子数,不相容因子(DF)判定检查结果的可靠性等方面都作了较系统的有益探索,并提出了些新颖的观点和看法,证明了其具有广阔的应用前景。即使对有交互作用较强的药物样品的定量分析,仍取得了较满意的结果。本论文共作了如下四方面的探讨。1.CPA矩阵法在光度分析中进行多组份体系同时测定的研究。2.偏最小二乘法(PLS)在分光光度定量分析中的应用。它是以因子分析为基础的多元统计学方法。3.主组份回归法(PCR)同时计算测定钨、钼、钒。它是因子分析(FA)和MLR相结合的产物。故兼容了FA和多元线性回归法中的经典最小二乘法(CLS)和逆最小二法(ILS)的优点。4.多元统计学方法在光度分析中应用的研究。本文将较为优异的计算方法,PCR和PLS分别进行了多方面的分析测定研究。总之,PCR和PLS法都是因子分析(FA)和多元线性回归法(MLR)相结合的产物。在目前的计算方法中,被认为是最有前途的多元统计学方法。

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本文综述了无机闪烁材料研究的进展,着重了氟化物体系中几种新型无机闪烁材料的制备、性能及辐照损伤等特性。运用B-S法生长了BaF_2及BaF_2:Ce晶体,研究了其室温以上的TSL特性,发现BaF_2的TSL曲线是由381K和402K的双峰结构组成Ce的掺入使TSL强度降低,同时提高了其抗辐照性能。运用高温固相反应法合成了KMgF_3、KCaF_3、BaLiF_3微晶,用TSL和ESR研究了其辐照损伤及其恢复情况。纠正了文献中对KMgF_3热释峰归属的错误,发现在KMgF_3、KCaF_3中杂质Al~(3+)一方面引入新的缺陷而导致新的热释峰,另一方面抑制了F心的形成。在BaLiF_3中La~3、Yb~(3+)的掺入会抑制F心,同时使H心增强,观察到了大剂量(10~8Rad)辐照时BaLiF_3中FA心形成及其在加热和紫外光照射时向F心的转化。发现它们的X射线辐照损伤极易恢复,而γ射线辐照损伤则较难恢复。通过对ESR峰高与Eu掺杂浓度的研究,运用数学拟合法求得了Eu~(3+)掺入KMgF_3制备KMgF_3:Eu~(2+)的饱和掺杂浓度为0.29mol%。首次发现BaLiF_3:Eu~(2+)的PSL现象,并证明它是一种很有发展前途的新型X射线存贮材料。运用B-S法探索了KMgF_3、BaLiF_3、单晶生长工艺,用X射线四园衍射法发现La~(3+)、Tm~(3+)掺入KMgF_3时分另占据K~+、Mg~(2+)的格位,用SEM观察了浓H_2SO_4cf KMgF_3单晶的侵蚀形貌和BaLiF_3单晶生长中经常出现的包裹体。研究了LaF_3:Ce~(3+)的发光特性及其它三价稀土离子的共掺杂对Ce~(3+)发光特性的影响,发现其它三价稀土离子的共掺杂都会使Ce~(3+)的发光猝灭,并分别归结为能量传递和电荷转移。用B-S法生长了CeF_3单晶,但因原料纯度低,衰减常数和光子产额都比文献值要低,说明在闪烁晶体制备时,提高原料纯度是十分必要的。

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Current based microscopic defect analysis methods such as current deep level transient spectroscopy (I-DLTS) and thermally stimulated current (TSC) have been further developed in accordance with the need for the defect analysis of highly irradiated (Phi(n) > 10(13) n/cm(2)) high resistivity silicon detectors. The new I-DLTS/TSC system has a temperature range of 8 K less than or equal to T less than or equal to 450 K and a high sensitivity that can detect a defect concentration of less than 10(10)/cm(3) (background noise as low as 10 fA). A new filling method using different wavelength laser illumination has been applied, which is more efficient and suitable than the traditional voltage pulse filling. It has been found that the filling of a defect level depends on such factors as the total concentration of free carriers generated or injected, the penetration length of the laser (laser wavelength), the temperature at which the filling is taking place, as well as the decay time after the filling (but before the measurement). The mechanism of the defect filling can be explained by the competition between trapping and detrapping of defect levels, possible capture cross section temperature dependence, and interaction among various defect levels in terms of charge transferring. Optimum defect filling conditions have been suggested for highly irradiated high resistivity silicon detectors.

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Chemically vapour deposited silicon on sapphire (SOS) films 0.25 mu m thick were implanted with Si-28(+) and recrystallized in solid phase by furnace annealing (FA) and IR rapid thermal annealing (RTA) in our laboratory. An improvement in crystalline quality can be obtained using both annealing procedures. After FA, it is hard to retain the intrinsic high resistivity value(10(4)-10(5) Ohm cm) observed in as-grown SOS films, so the improvement process cannot be put to practical use effectively. However, it is demonstrated that by properly adjusting the implantation and RTA conditions, significant improvements in both film quality and film autodoping can be accomplished. This work describes a modified double solid phase epitaxy process in which the intrinsic high resistivities of the as grown SOS films are retained. The mechanism of suppression of Al autodoping is discussed.

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An analog baseband circuit made in a 0.35-μm SiGe BiCMOS process is presented for China Multimedia Mobile Broadcasting (CMMB) direct conversion receivers. A high linearity 8th-order Chebyshev low pass filter (LPF) with accurate calibration system is used. Measurement results show that the filter provides 0.5-dB pass-band ripple, 4% bandwidth accuracy, and -35-dB attenuation at 6 MHz with a cutoff frequency of 4 MHz. The current steering type variable gain amplifier (VGA) achieves more than 40-dB gain range with excellent temperature compensation.This tuner baseband achieves an OIP3 of 25.5 dBm, dissipates 16.4 mA under a 2.8-V supply and occupies 1.1 mm~2 of die size.

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A 5.2 GHz variable-gain amplifier (VGA) and a power amplifier (PA) driver are designed for WLAN IEEE 802.11a monolithic RFIC. The VGA and the PA driver are implemented in a 50 GHz 0.35 μm SiGe BiCMOS technology and occupy 1.12×1.25 mm~2 die area. The VGA with effective temperature compensation is controlled by 5 bits and has a gain range of 34 dB. The PA driver with tuned loads utilizes a differential input, single-ended output topology, and the tuned loads resonate at 5.2 GHz. The maximum overall gain of the VGA and the PA driver is 29 dB with the output third-order intercept point (OIP3) of 11 dBm. The gain drift over the temperature varying from -30 to 85℃ converges within±3 dB. The total current consumption is 45 mA under a 2.85 V power supply.

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介绍了一种新型单侧耦合16通道、100GHz通道间隔的硅基二氧化硅阵列波导光栅(AWG).通过增加一个Y分支波导结构,将AWG的输入、输出波导等间距整齐排列,仅用一个光纤阵列(FA)就可以对AWG器件进行耦合封装.这种AWG的结构设计可有效地减小器件尺寸和增加波导结构的弯曲半径,可减少器件的抛光和耦合时间,可降低器件的成本.

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垃圾卫生填埋是国内外城市垃圾的主要处置方法。垃圾渗滤液是渗入填埋场垃圾的降水混合垃圾降解过程中产生的物质而形成的混合物,是垃圾填埋场向环境排放的主要污染物。渗滤液由于其所含高浓度有机和无机污染物,且其中很多物质有生物毒性或难生物降解,难于治理。特别是到填埋晚期,渗滤液中高浓度的氨氮更是增加了治理的难度。渗滤液场外硝化-原位反硝化是填埋场氮管理的新途径。本文利用从环境中筛选出优势硝化功能菌对渗滤液中的高浓度氨氮进行生物硝化,经硝化后的渗滤液回灌至以垃圾柱模拟的生物反应器填埋场,在填埋场内实现原位反硝化。 上述目标通过以下两部分来实现: 第一部分:渗滤液场外硝化。首先从污水厂的硝化污泥中富集并筛选出硝化功能菌,在模拟氨氮废水中优化。将驯化的硝化功能菌接种于连续式完全混合反应器(CSTR)进行高氨氮渗滤液硝化研究。在200余天的连续运行中,反应器硝化和有机物去除效果良好。在最大氨氮负荷和有机物负荷分别为0.65 g N l-1 d-1 和3.84 g COD l-1 d-1时,氨氮和COD去除率分别高于99%和57%。实验过程中发现,游离氨(FA)和溶解氧(DO)浓度对反应器中亚硝酸盐的积累影响很大。 第二部分:渗滤液原位反硝化。本文利用一个垃圾填充柱模拟生物反应器填埋场,研究了硝化渗滤液回灌对垃圾降解的影响,和回灌的硝化渗滤液中TON(总氧化态氮)对填埋场生物反应器产甲烷作用的影响。最后利用变性梯度凝胶电泳(DGGE)分析了硝化渗滤液回灌对垃圾填埋场菌群结构的影响。结果表明:回灌的TON被完全还原,反硝化为主要反应,最大TON负荷为28.6 mg N kg-1 TS d-1。当垃圾柱TON负荷大于11.4 mg N kg-1 TS d-1时,出现了产甲烷抑制,抑制作用随TON负荷的增加而加强。在此过程中,反硝化逐渐代替产甲烷作用成为填埋场内垃圾降解的主要反应,且更多产生的是清洁的氮气,而非温室气体甲烷。直到实验结束时,回灌硝化渗滤液的垃圾柱的甲烷产量仅相当于对照的2.5%,并且回灌的硝化渗滤液还加速了填埋场垃圾的降解与稳定。通过DGGE进行菌群结构分析发现,由于TON对填埋场的长期作用,反硝化菌增多而产甲烷菌减少。 Landfill still remains the chief method for MSW management around the world. Leachate is a mixture of rainfall permeating through landfill and organic and inorganic matters generated during decomposition of the wastes in the landfills, characterized as highly complicated and refractory wastewater. Ex-situ nitrification and sequential in-situ denitrification represents a novel approach to nitrogen management at landfills. In the present paper, nitrification was carried out in a continuous stirred tank reactor (CSTR) inoculated with nitrifying bacteria which were isolated from municipal WWTP of Chengdu city. The nitrified leachate from CSTR was recirculated to a lab-scale municipal solid waste (MSW) column where in-situ denitrification took place. The above object was achived through two parts as following: First, ex-situ nitification of leachate. After acclimated in simulated wastewater for 3 month, nitrifying bacteria isolated from WWTP nitrifying sludge were added to the CSTR for nitrification. The results over 200 days showed that the maximum nitrogen loading rate (NLR) and the maximum organic loading rate (OLR) was 0.65 g N l-1 d-1 and 3.84 g COD l-1 d-1, respectively. The ammonia and COD removal was over 99% and 57%, respectively. Moreover, the effects of free ammonia (FA) and dissolved oxygen (DO) on nitrification were investigated. Second, in-situ denitrification was studied in a municipal solid waste (MSW) column. Variation of nitrified leachate and its effects on the decomposition of municipal solid waste (MSW) were studied in a lab-scale MSW column to which nitrified leachate was recirculated. Additionally, DGGE was employed to investigate the microbial community of both MSW columns. The results suggested: complete reduction of total oxidized nitrogen (TON) was obtained with maximum TON load of 28.6 mg N kg-1 TS d-1 and denitrification was the main reaction responsible. Methanogenesis inhibition was observed while TON load was over 11.4 mg N kg-1 TS d-1 and the inhibition was enhanced with the increase of TON load. Denitrification gradually took over methanogenesis to become the main reaction responsible for decomposition of MSW while nitrogen gas, a clean byproduct, was generated instead. Till the end of the experiment, the average weekly methane production in the denitrification column was as low as 2.5% of that of the control, and the rate of decompition and stability of MSW was accelerated by the recirculation of the nitrified leachate.Owing to long term exposure of nitrified leachate to landfill, denitrifying bacteria increased and methanogen decreased.