Examination of the statistical method in the conjugated circuit theory

Summary The recently proposed statistical method for the calculation of resonance energies in the conjugated circuit theory is tested on the example of polyacenes. It is found that for the estimation of the resonance energy with a 10% average error, the method requires a sample consisting of about 20 (randomly chosen) Kekulé structures. Further increase of the sample size gives no significant gain in the accuracy of the method.

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Überprüfung der statistischen Methode in der Konjugierten-Ring-Theorie

Zusammenfassung Die unlängst vorgeschlagene statistische Methode in der Konjugierten-Ring-Theorie (conjugated circuit theory) wird am Beispiel der Polyacene getestet. Es wurde festgestellt, daß für die Abschätzung der Resonanzenergien bei einem mittleren Fehler von 10% für diese Methode ungefähr 20 (willkürlich gewählte) Kekulé-Strukturen nötig sind. Weitere Erhöhung dieser Anzahl bringt keine signifikante Verbesserung der Genauigkeit der Methode.

     

Fluorinated compounds for advanced IC interconnect applications: a survey of chemistries and processes

The semiconductor industry is now in the early stages of an unprecedented change in materials set for the integrated circuit (IC) interconnect structure. The traditional layers of aluminum conductors and silicon dioxide dielectrics are being replaced by copper thin films and a variety of low k candidates, respectively. In many cases, fluorine confers desirable properties on either the precursors or the final films. At the same time, fluorine presents some potentially adverse effects, which have led to a so-called “fear-of-fluorine” in interconnect applications. This paper will review the proposed uses of fluorinated compounds in the interconnect structures, covering both precursors and the resulting thin films. Both the status of technical studies, and the prospects for commercial implementation, will be addressed.     

Preparation and evaluation of a large-volume radial flow monolithic column

In this study, a 38 mL monolith with homogeneous porous structure was produced by a single polymerization from glycidyl methacrylate (GMA) and ethylene dimethacrylate (EDMA) in the presence of porogens and an initiator. The uniform temperature distribution within the reaction system was achieved by adding reactant mixture continuously and enhancing the heat transfer ability of the polymerization system. Homogeneous porous structure in the monolith was proved by SEM and the pore size distribution profiles measured by mercury intrusion porosimetry. Experimental results from proteins separation indicated that the dynamic capacity and resolution of radial flow monolithic column were independent of flow rates. Furthermore, the pressure drop on the column was linearly dependent on the flow rate and did not exceed 1.7 MPa even at a flow rate of 50 mL/min, which proved that the prepared monolith could be used in the quick separation and preparation of biopolymers.     

压电石英晶体在电解质水溶液中的振荡性能研究(Ⅱ)——频率、频移特性

根据两面电极浸入液体中的压电晶体等效电路模型和Pierce振荡器振荡方程的解,得到晶体在电解质溶液中的振荡频率(F_1)与溶液电导率(x)的关系式:F_1=(1/2π)(1/C_1+1/C_2)(1/X_e)[(R_e~2+X_e~2)x~2+2R_ex+1]。以自行设计的Pierce晶体振荡器。研究了晶体和主振电路参数、输入电压及检测池外壳屏蔽接地对AT切9MHz石英晶体在KCl、Na_2SO_4水溶液中的频率、相对于纯水频移随溶液电导率变化的影响规律,结果与上式相符。     

数字电路的VHDL语言设计方法

分析了传统硬件电路设计的“自下而上”的方式和步骤，针对设计中存在的调试与试验相对滞后的问题，提出了采用“自上而下”的VHDL电路设计方法，按照硬件设计的三个层面，对行为级描述、寄存器传输级描述和逻辑综合进行了说明并给出了电路设计流程，通过SCI设计实例对该设计方法做了进一步的诠释和具体分析，为数字电路的VHDL语言设计提供了可借鉴的思路和方法．     

TMS320DM642多媒体处理系统中高性能音频功能的实现

介绍了在以新一代高性能处理器TMS320DM642为核心的多媒体处理系统中,采用音频编解码芯片TLV320AIC23实现高性能音频处理功能,详细说明了TMS320DM642多路音频串口McASP和内置集成电路总线的软硬件接口设计,并给出了TLV320AIC23初始化设置参数。     

俄罗斯微型集成电路命名方法(OCT 11 073.915-2000标准)

介绍了俄罗斯OCT 11 073.915-2000标准规定的微型集成电路命名方法,给出器件命名的规则,使用符号及命名中使用的俄罗斯各生产厂家代码.     

电子设备电源系统的谐波特性研究

电子设备的电源系统或电力系统中,存在多种类型的谐波源,分为谐波电流源和谐波电压源,本文针对典型电源系统开关电源系统进行分类和建模,给出各类谐波源的特征,并对容性滤波整流电路的谐波特性进行了分析.     

三值双传输管电路的通用综合方法

提出采用双传管逻辑设计三值电路的方法,对每个MOS管的逻辑功能均采用传输运算予以表示以实现有效综合.建立了三值双传输管电路的反演法则和对偶法则.新提出的三值双传输管逻辑电路具有完全基于标准CMOS工艺,无需对MOS管作任何阈值调整,结构简单、规则,输入信号负载对称性好,逻辑摆幅完整以及无直流功耗等特点.采用TSMC 0.25μm工艺参数和最高电压为3V的HSPICE模拟结果验证了所提出综合方法的正确性.     

钟控神经MOS管的改进及其在多值电路中的应用

首先对钟控神经MOS管进行研究,提出了相应的改进方法.然后采用此改进的钟控神经MOS管设计了一种新型多值触发器.与传统的触发器相比较,此多值触发器具有结构简单、速度快、功耗低等特点;而且无需改变电路结构就可实现不同基的多值触发器.PSPICE模拟证明了所设计的电路具有正确的逻辑功能.