基于CPLD物理实验电路的研究

复杂可编程逻辑器件CPLD是当今应用最广泛的可编程专用集成电路（ASIC）之一，使用一片CPLD可以代替原来用很多器件才能完成的逻辑功能，我们用CPLD来构建数字电路，和常规逻辑器件相比其突出特点是：元件少，成本低，功耗低。ALTERA公司是全球著名的复杂可编程逻辑器件供应商，结合实际工作的需要，我们选用了ALTERA公司的MAXII EPM1270芯片做了一系列实验电路，先后开展的研究工作包括：1.超低频/超大脉宽信号源；2.门延迟产生电路。 这两方面的工作分别在论文的有关专题介绍。超低频/超大脉宽信号源用作为多定标测量数据获取系统的门控信号，主要功能是产生一系列精确度高、稳定性好的低频、超低频/超大脉宽脉冲信号，且可以根据需要选择手动触发单个大脉冲输出。本电路输出脉冲f/T的精确度≤0.02‰，输出脉冲f/T的稳定性≤±0.01‰。基于CPLD设计的超低频/超大脉宽信号源电路只需一片CPLD就可以取代原来用很多逻辑器件才能完成的功能，此外基于CPLD设计的该信号源的最大周期可超过1000s、步进脉宽调节可达T/1000，远远超过用户提出的指标，从而能满足更多的应用需要。 基于CPLD的门延迟产生电路主要功能是对输入信号进行展宽延迟，我们将它做成NIM单宽插件可提供8道信号延迟展宽，支持NIM负信号输入，用于物理实验中的符合测量、多路时间测量系统及能量测量系统中的ADC或QDC门控信号等，替代目前传统同类型的插件GG8000。 目前两个电路都已调试成功，其中超低频/超大脉宽信号源已交付用户使用，获得满意结果

微弱信号的获取方法及电路研究

论文以长时间超低零漂积分器和基于前端ASIC芯片的微弱信号读出系统两项课题为核心展开，讨论我们在两类典型微弱信号的获取方法和电路研究方面上采用的一些新思路和新方法。论文论述了用于托卡马克装置上电磁测量的长时间超低零漂积分器的原理与设计。积分器的积分零漂被减小到极低的水平，积分1000s绝对积分零漂典型值为16.7mV，同时积分器的非线性误差也得到改善。同时，阐述了一种采用前端ASIC芯片实现微弱信号读出的新型方法。它替代了采用分离元件和电子学插件构建微弱信号读出系统的传统方法，着重解决了近代核与粒子物理实验中越来越突出的多路多道需求和高性能指标要求

多通道电荷时间测量方法与电路研究

随着国家大科学工程兰州重离子加速器冷却储存环(HIRFL-CSR)建成，HIRFL-CSR实验探测系统也正在建设当中。实验探测系统由外靶系统和内靶系统构成。用于探测中子的中子墙探测器是外靶系统中的一个重要组成部分，它有252个探测单元，每一个探测器单元都要求很好的能量分辨和时间分辨，还要求有很高数据获取率。为此，我们设计研发适合于中子墙探测器这样的大型闪烁体探测器的前端电子学读出系统。论文从发展髙性能多路小型化前端电路和研究QAC、TAC的方法和电路两个方面进行研究，讨论了我们采用的新思路和新方法。 我们设计的新型的多道高精度的电荷-电压、时间转换电路.该电路主要用于在相关控制信号的配合下，将光电倍增管输出的快电流脉冲信号转化为电压信号,并在控制信号作用下,将电压信号通过数据采集系统直接送入计算机进行处理。电路采用新型的QAC方法，用于处理快速的电流信号,突出特点是转换速度快,电路结构简单,输入信号范围大,精度高,功耗低, 电路采用改进的TAC方法，用于处理快速的时间信号,利用高速DMOS开关，并优化控制逻辑时序，极大提高了测试精度。 实验室调试结果说明系统已能够适应物理实验的要求，并为最终建立一个完整的满足性能要求的前端电子学系统打下了坚实的基础

弱小信号处理电路的研制

无论是在核物理和粒子物理实验中，我们常常需要对探测到的弱小信号进行线性处理，以满足测量与分析的要求。为此，我们以弱小信号处理为题，开展了一些研究工作，我们先后开展的研究工作包括以下几个方面：1．弱电流测试仪的研制2．电荷前放的研制3．主放的研制这三种仪器我们将在沦文的第二、第三、第四章分别进行阐述。弱电流测试仪是一种便携式仪器（直接由22OV供电），它可以测量0．1 nA至100tlA范围的弱小电流（测量范围分六档可调）。它可以接受正或负极性直流输入电流。输出采用两种方式：表头直读和电压输出。电压输出最大为＋5V。电荷前置放大器具有电路结构简单、体积小（38m×45mm×80mfll）、输出信号上升时间快、噪声低、稳定性好等特点。主放成形时间常数分为四档：0．5 us、1 us、2 us、3 us：放大倍数分为两档：×10、×100；峰保持时间为6us左右（确保后续ADC所需的时间）；具有价格低、性能好、体积小的特点。在论文的第五部分论述的是根据在调试过程中出现的实际问题提出的解决办法，其中最主要的是对各种噪燕的解决办法。上述仪器研制完成后，在实际使用中，获得了满意的结果，受到好评。

信号采集与数据处理电路的研究

随着原子核科学技术的发展，无论是对原子核内部特征和规律的研究，或者是对原子核科学技术的应用，都需要对核辐射和原子核所携带的信息进行测量和分析研究。在核电子学测量系统中，核辐射探测器输出信号在经过各种信号处理电路后，通常都要变换成数字信号，再经过数据收集和处理，给出实验的最终结果，因此实验工作的任何进展都要求有相应的数据获取和处理系统的支持。根据实验的实际需求，我们以采集、处理探测器输出的信号为题，开展了一些研究工作，我们先后开展的研究工作包括以下儿个方面：1．激光功率计的变换与显示电路的研制2．基于PCI总线、嵌入8051单片机的计数卡的研制3．数据处理分析软件的设计这三部分的设计工作我们将在论文的第二、第三、第四章分别进行阐述。激光功率计的变换与显示电路把由激光功率计输出的模拟电压量变为数字脉冲输出，并且把该输出脉冲的频率实时定性显示出来。本电路测量精度高，线性好，工作稳定。我们研制开发的计数卡是一种很实用的计数卡，它是一种基于PCI总线，嵌入单片机的高速计数器，最大计数范围为109-1，最高的计数频率为20MHz。该计数卡计数范围宽，计数频率高，具有定时计数、重复计数等功能，可以取代常规的定标器，具有广泛的应用前景。数据处理分析软件包括下位机软件、上位机软件及通讯协议三部分，实现数据的采集与记录，并将读取的数据以Excel电子表格的形式存储，以备查询。下位机的软件采用KeilC编写，上位机软件采用Delphi编写。目前激光功率计的变换与显示电路和计数卡及相应的数据处理软件都设计、调试完成，已经投入使用，获得满意结果，受到好评。

Spatial-temporal characteristics of siping urban expansion based on remote sensing and GIS

Based on the RS and GIS methods, Siping city is selected as a study case with four remote sensing images in 25 years. Indices of urban morphology such as fractal dimension and compactness are employed to research the characteristics of urban expansion. Through digital processing and interpreting of the images, the process and characteristics of urban expansion are analysed using urban area change, fractal dimension and compactness. The results showed that there are three terms in this period. It expended fastest in the period of 1979~1991, and in the period of 1992~2001, the emphases on urban redevelopment made it expended slower. And this is in agreement with the Siping Statistical Yearbook. This indicates that the united of metrics of urban morphology and statistical data can be used to satisfactorily describe the process and characteristics of urban expansion. © 2008 IEEE.

Phthalocyanato tin(IV) dichloride: An air-stable, high-performance, n-type organic semiconductor with a high field-effect electron mobility

Phthalocyanato tin(IV) dichloride, an axially dichloriniated MPc, is an air-stable high performance n-type organic semiconductor with a field-effect electron mobility of up to 0.30 cm(2) V-1 s(-1). This high mobility together with good device stability and commercial availability makes it a most suitable n-type material for future organic thin-film transistor applications.

Potassium-Lead-Switched G-Quadruplexes: A New Class of DNA Logic Gates

A cation-driven allosteric G-quadruplex DNAzyme (PW17) was utilized to devise a conceptually new class of DNA logic gate based on cation-tuned ligand binding and release. K+ favors the binding of hemin to parallel-stranded PW17, thereby promoting the DNAzyme activity, whereas Pb2+ induces PW17 to undergo a parallel-to-antiparallel conformation transition and thus drives hemin to release from the G-quadruplex, deactivating the DNAzyme. Such a K+-Pb2+ switched G-quadruplex, in fact, functions as a two-input INHIBIT logic gate. With the introduction of another input EDTA, this G-quadruplex can be further utilized to construct a reversibly operated IMPLICATION gate.

Realization of negative differential resistance and switching devices based on copper phthalocyanine by the control of evaporation rate

We have observed, respectively, a negative differential resistance (NDR) and switching conduction in current-voltage (I-V) characteristics of organic diodes based on copper phthalocyanine (CuPc) film sandwiched between indium-tin-oxide (ITO) and aluminum (Al) by controlling the evaporation rate. The NDR effect is repeatable which can be well, controlled by sweep rate and start voltage, and the switching exhibits write-once-read-many-times (WORM) memory characteristics. The traps in the organic layer and interfacial dipole have been used to explain the NDR effect and switching conduction. This opens up potential applications for CuPc organic semiconductor in low power memory and logic circuits.

Electrical properties in vanadyl-phthalocyanine-based metal-insulator-semiconductor devices

We investigated electrical properties of vanadyl phthalocyanine (VOPc) metal-insulator-semiconductor (MIS) devices by the measurement of capacitance and conductance, which were fabricated on ordered para-sexiphenyl (p-6P) layer by weak epitaxy growth method. The VOPc/p-6P MIS diodes showed a negligible hysteresis effect at a gate voltage of +/- 20 V and small hysteresis effect at a gate voltage of +/- 40 V due to the low interface trap state density of about 1x10(10) eV(-1) cm(-2). Furthermore, a high transition frequency of about 10 kHz was also observed under their accumulation mode. The results indicated that VOPc was a promising material and was suitable to be applied in active matrix liquid crystal displays and organic logic circuits.

High-mobility pentacene thin-film transistors with copolymer-gate dielectric

Pentacene thin-film transistors have been obtained using polymethyl-methacrylate-co-glyciclyl-methacrylate (PNIMA-GMA) as the gate dielectric. The optimum active layer thickness in thin-film transistors (OTFTs) was investigated. The present devices show a wide operation voltage range. The on/off current ratio is as high as 10(5). In linear region (V-DS = -2V), the field-effect mobility of device increases with the increase in gate field at low-voltage region (V-G < - 20 V), and a mobility of 0.33 cm(2)/Vs can be obtained when V-G > 20 V. In saturation region, the mobility increases linearly with the gate field, and a high mobility of 1.14 cm(2)/Vs can be obtained at V-G = -95V. The influence of voltage on mobility of device was investigated.

Poly(vinylidene fluoride-hexafluoropropylene)/organo-montmorillonite clays nanocomposite lithium polymer electrolytes

Polymer-clay nanocomposite (PCN) materials were prepared by intercalation of an alkyl-ammonium ion spacing/coupling agent and a polymer between the planar layers of a swellable-layered material, such as montmorillonite (MMT). The nanocomposite lithium polymer electrolytes comprising such PCN materials and/or a dielectric solution (propylene carbonate) were prepared and discussed. The chemical composition of the nanocomposite materials was determined with X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy, which revealed that the alkyl-ammonium ion successfully intercalated the layer of MMT clay, and thus copolymer poly(vinylidene fluoride-hexafluoropropylene) entered the galleries of montmorillonite clay. Cyclic voltammetry and electrochemical impedance spectroscopy (EIS) were used to investigate the electrochemical properties of the lithium polymer electrolyte. Equivalent circuits were proposed to fit the EIS data successfully, and the significant contribution from MMT was thus identified. The resulting polymer electrolytes show high ionic conductivity up to 10(-3) S cm(-1) after felling with propylene carbonate.

Organic thin-film transistors having inorganic/organic double gate insulators

Bottom-contact organic thin-film transistors (BC OTFTs) based on inorganic/organic double gate insulators were demonstrated. The double gate insulators consisted of tantalum pentoxide (Ta2O5) with high dielectric constant (kappa) as the first gate insulator and octadecyltrichlorosilane (OTS) with low kappa as the second gate insulator. The devices have carrier mobilities larger than 10(-2) cm(2)/V s, on/off current ratio greater than 10(5), and the threshold voltage of -14 V, which is threefold larger field-effect mobility and an order of magnitude larger on/off current ratio than the OTFTs with a Ta2O5 gate insulator. The leakage current was decreased from 2.4x10(-6) to 7.4x10(-8) A due to the introduction of the OTS second dielectric layer. The results demonstrated that using inorganic/organic double insulator as the gate dielectric layer is an effective method to fabricate OTFTs with improved electric characteristics.

Improved n-type organic transistors by introducing organic heterojunction buffer layer under source/drain electrodes

N-type organic thin-film transistors (OTFTs) employing hexadecafluorophthalocyaninatocopper (F16CuPc) as active layer and p-type copper phthalocyanine (CuPc) as buffer layer are demonstrated. The highest field-effect mobility is 7.6x10(-2) cm(2)/V s. The improved performance was attributed to the decrease of contact resistance due to the introduction of highly conductive F16CuPc/CuPc organic heterojunction. Therefore, current method provides an effective path to improve the performance of OTFTs.

Negative differential resistance effect in organic devices based on an anthracene derivative

The authors observed a negative differential resistance (NDR) in organic devices consisting of 9,10-bis-(9,9-diphenyl-9H-fluoren-2-yl)-anthracene (DPFA) sandwiched between Ag and indium tin oxide electrodes. The large NDR shown in current-voltage characteristics is reproducible, resulting in that the organic devices can be electrically switched between a high conductance state (on state) and a low conductance state (off state). It can be found that the currents at both on to off states are space-charge limited and attributed to the electron traps at the Ag/DPFA interface. The large and reproducible NDR makes the devices of tremendous potential in low power memory and logic circuits.