某些噻唑偶氮苯酚类试剂结构与性能关系的理论研究

噻唑偶氮试剂广泛应用于分析化学,近十来年发展较快,迄今已有170余种,但其结构和性能关系的理论研究报导较少。本文选取2-(2-噻唑偶氮)苯酚(简称TAP)及其九种甲基取代衍生物(见表1),用CNDO/2方法研究其结构与碱性关系,讨论这些试剂与金属离子螯合的可能位置,其结果和实验基本一致。计算分子构型所用TAP骨架取由文献,甲基用标准构型。原子编号见图1,计算在IBM PC/AT微机上完成。     

两层阵列二的补码复数并行算法及其光学实现

提出了直接的二的补码阵列算法，基于混合二的补码表达方式，加法，减法和阵列乘法都能全并行地实现。直接算法克服了传统算法中存在的困难，即原理上对操作数的编码位数无限制，更有效地利用了空间带宽积，卷积后的序更直接加权求和即为两数的乘积，复数运算由包含四个区域的两层阵列完成，并进行了光学实验。     

快速无参数背景建模的红外目标检测方法研究

针对复杂背景红外图像序列目标检测的难题,给出了一种用于红外监控系统中入侵目标检测的背景建模方法。应用特征样本集为每一个像素建立统计无参数样本集模型,根据核函数估计计算每一个像素值对模型的符合概率。使用双阈值进行目标检测和模型更新,将图像分为三类:可靠背景、感兴趣区域和不可靠背景。通过不可靠背景类提供的信息进一步将感兴趣区域细分为入侵目标和错误检测。对几种红外图像序列仿真实验表明,该算法不仅可以比较精确的检测显著入侵目标,对于容易淹没在噪声中的弱小入侵目标也可以实现准确地检测。     

Direct observation of the intramolecular triplet-triplet energy transfer in poly(aryl ether) dendrimers

A series of benzophenone (BP) and naphthalene (NA) labeled poly(aryl ether) dendrimers (BP-Gn-NA), generations 1-4, were synthesized, and their photophysical properties were examined. Flash photolysis demonstrates that the triplet energy in BP-Gn-NA can be transferred from the peripheral BP chromophores to the core NA group with the efficiencies of ca. 0.97, 0.96, 0.88, and 0.54 and with the rate constants of 1.4x10(8), 1.2x10(8), 9.5x10(7), and 1.3x10(7) s-1 at room temperature for generations 1-4, respectively. The transient absorption spectra of BP-Gn-NA show clearly the formation of the triplet NA absorption along with the decay of the triplet BP one with an isosbestic point at 475 nm, which gives direct evidence of the triplet energy transfer from the periphery BP chromphores to the core NA group. The phosphorescence of the NA group attached to the focal point was observed when the periphery BP chromophores were selectively irradiated in BP-G1-NA at 77 K. The triplet energy transfer occurs at 77 K with the efficiencies of 1.0, 0.16, 0.17, and 0.21 for generations 1-4, respectively. The intramolecular triplet energy transfer is proposed to proceed mainly via a through space mechanism.     

Comparing a mononuclear Zn(II) complex with hydrogen bond donors with a dinuclear Zn(II) complex for catalysing phosphate ester cleavage

Introducing ligand based hydrogen bond donors to increase the activity of a mononuclear Zn(II) complex for catalysing phosphate ester cleavage can be a more effective strategy than making the dinuclear analogue.     

A miniaturized HTS microwave receiver front-end subsystem for radar and communication applications

This paper presents a miniaturized high performance high temperature superconducting (HTS) microwave receiver front-end subsystem, which uses a mini stirling cryocooler to cool a high selective HTS filter and a low noise amplifier (LNA). The HTS filter was miniaturized by using specially designed compact resonators and fabricating with double-sided YBCO films on LAO substrate which has a relatively high permittivity. The LNA was specially designed to work at cryogenic temperature with noise figure of 0.27 dB at 71 K. The mini cryocooler, which is widely used in infrared detectors, has a smaller size (60 mm × 80 mm × 100 mm) and a lighter weight (340 g) than the stirling cryocoolers commonly used in other HTS filter subsystem. The whole front-end subsystem, including a HTS filter, a LNA, a cryocooler and the vacuum chamber, has a size of only φ120 mm × 175 mm and a weight of only 3.3 kg. The microwave devices inside the subsystem are working at 71.8 K with a consumed cooling power of 0.325 W. The center frequency of this subsystem is 925.2 MHz and the bandwidth is 2.7 MHz (which is a fractional bandwidth of 0.2%), with the gain of 19.75 dB at center frequency and the return loss better than ?18.11 dB in the pass band. The stop band rejection is more than 60 dB and the skirt slope is exceeding 120 dB MHz^?1. The noise figure of this subsystem is less than 0.8 dB. This front-end subsystem can be used in radars and communication systems conveniently due to it’s compact size and light weight.     

Relative Transpose and its Dual with Respect to a Bimodule

For a class of modules \(\mathcal {X}\), we introduce the \(\mathcal {X}\)-transpose of a module with respect to a bimodule, which unifies some well-known transposes. Let \(\mathcal {V}\) be a subclass of \(\mathcal {X}\). The relations between \(\mathcal {X}\)-transposes and \(\mathcal {V}\)-transposes are investigated under the condition that \(\mathcal {V}\) is a generator or cogenerator of \(\mathcal {X}\). The dual aspects of \(\mathcal {X}\)-transposes are also discussed. Then we give some applications of these results. In particular, the dual counterparts of Gorenstein transposes are established.     

求一阶数值微分的L-广义解方法cTSVD

<正>1引言数值微分也就是给定一个函数在一个区间或某些离散点上的扰动数据来求函数的导数,它产生于很多实际问题当中,比如,图象处理中的边界识别问题;Abel积分方程的求解问题;化学中波谱的波峰识别问题.以及一些数学物理反问题当中.数值微     

Effect of Fe on the glass-forming ability,structure and devitrification behavior of Zr–Cu–Al bulk glass-forming alloys

We report on the glass-forming ability and devitrification behavior of Zr₆₀Cu₃₀Al₁₀, Zr₆₀Cu₂₅Al₁₀Fe₅ and Zr_62.5Cu_22.5Al₁₀Fe₅ bulk glass-forming alloys on heating. The effect of Fe addition on the structure of Zr–Al–Cu alloys is also discussed. Crystallization kinetics and structural changes in the glassy alloys were studied using X-ray diffraction, transmission electron microscopy, differential scanning and isothermal calorimetry methods. The results indicate that good glass-formers, such as Zr_62.5Cu_22.5Al₁₀Fe₅, are located somewhat beyond the equilibrium eutectic point. Possible phase separation in the supercooled liquid on heating and electron beam-induced in situ crystallization are observed and discussed.     

Skin Thickness and β-Crystals Development in Injection-Molded iPP Along the Flow Direction

In this study, iPP was injection molded at 180°C, 200°C, and 220°C. According to polarization optical microscopy (POM) results, for a given part, the skin thickness steadily decreases along the flow direction. However, at the same distance from the gate, the skin thickness of the parts molded at lower melt temperature is larger than that molded at higher melt temperature. It is found that flow time (here, the time taken for melt to pass the specific position along the flow direction) and melt temperature are two significant factors leading to this phenomenon, while the gate size is another one.

The DSC and WAXD results show that the relative fraction of β-form crystals, for a specific part, decreases along the flow direction, which is mainly determined by flow time. However, for the parts molded at different molding temperatures, the fraction of the β-form crystals is mainly determined by the molding temperature, though this influence is very complex.