Integration in Real PCF

Real PCF is an extension of the programming language PCF with a data type for real numbers. Although a Real PCF definable real number cannot be computed in finitely many steps, it is possible to compute an arbitrarily small rational interval containing the real number in a sufficiently large number of steps. Based on a domain-theoretic approach to integration, we propose two approaches to integration in Real PCF. One consists in adding integration as primitive. The other consists in adding a primitive for function maximization and then recursively defining integration from maximization. In both cases we have a computational adequacy theorem for the corresponding extension of Real PCF. Moreover, based on previous work on Real PCF definability, we show that Real PCF extended with the maximization operator is universal.     

基于数据修正的实时阴影反走样算法

基于百分比渐近滤波（PCF）算法,提出一种改进的实时阴影反走样算法——数据修正PCF算法,其主要思想是在双线性插值滤波前对插值的数据进行必要的修正,从而消除阴影中的一些锯齿形走样现象．该算法利用像素渲染器PS2．0在图形硬件上实现．从实例图片可以看出,文中算法产生的许多阴影边界走样现象得到了明显的改善．     

EEPROMPCF8252在单片机控制系统中的应用

本文讨论电可擦除存储器 PCF8252与单片机 MCS8031的接口技术,给出了具体的接口电路和单片机 MCS8031对 PCF8252的读写子程序清单。     

光子晶体光纤及其在光纤陀螺中的应用

光子晶体光纤是一种包层由空气孔-石英沿轴向方向周期排列所构成的新型光纤。光子晶体光纤特殊的结构分布和特性,使其在降低光学噪声、陀螺尺寸、温度敏感性,提高陀螺精度和抗核辐射等方面,具有传统光纤陀螺不可比拟的优越性。本文综述了光子晶体光纤的概念、在光纤陀螺方面的独特优势,以及其在光纤陀螺应用方面的研究进展和前景。     

PCF的信息系统模型

带类型的λ－演算是一个逻辑系统，它可以作为程序语言的基础．Ｐｌｏｔｋｉｎ所引进的ＰＣＦ就是这样一类程序语言．Ｐｌｏｔｋｉｎ构造了ＰＣＦ的一个模型，然后讨论与这个模型相关的指称语义和操作语义之间的配合问题──简单配合和完全配合．本文利用Ｓｃｏｔｔ引进的信息系统概念构造ＰＣＦ的另一种模型，并证明与这个模型对应的指称语义与操作语义是完全配合的．     

时钟芯片在电压监测仪校验装置中的应用

根据电压监测仪校验装置需要建立一个标准时钟,对电压监测统计仪进行时间精度校正的要求,介绍了I2C总线接口时钟芯片PCF8583的基本原理,提出了利用DS32KHz给PCF8583提供高稳定度频率信号,从而实现了标准时钟的方案,并给出了PCF8583与MCS51单片机接口设计。     

Multiple-stage microfabricated preconcentrator-focuser for micro gas chromatography system

The design, fabrication, and characterization of a multiple-stage Si microfabricated preconcentrator-focuser (/spl mu/PCF) for a micro gas chromatography (/spl mu/GC) system that can provide real-time quantification and identification of complex organic vapor mixtures are presented. The /spl mu/PCF consists of a Si microheater loaded with Carbopack B, Carbopack X, and Carboxen 1000 carbon adsorbent granules, and a Si micromachined cover plate. Deep reactive ion etching is utilized to produce mechanically robust fluidic interconnection adapters hermetically sealed to fused silica capillary tubing for connection to the other components in the /spl mu/GC. This three-stage device is designed to capture compounds spanning up to 4 orders of magnitude in volatility. The dead volume, thermal mass, heating efficiency, and pressure drop of the three-stage /spl mu/PCF are improved significantly over its single-stage /spl mu/PCF predecessor. We demonstrate the successful capture, desorption, and high-resolution chromatographic separation of a mixture of 30 common organic vapors using our three-stage /spl mu/PCF in a conventional GC system. The peak width at half height is <2.05 s for all compounds after elution from the GC column.     

基于NS-2的自适应差额IEEE 802.11 PCF轮询机制

在研究无线局域网IEEE 802.11标准点协调功能PCF(Point Coordination Function)机制不足的情况下,针对其中Round Robin轮询机制存在的QoS(Quality of Service)不能得到有效保障的问题,提出了一套自适应差额轮询调度算法解决方案,阐述了算法的核心思想,介绍了调度机制的执行过程,并且通过修改PCF源代码,在网络模拟器NS-2平台上对算法进行了脚本模拟.实验结果表明,自适应差额IEEE 802.11 PCF轮询算法比传统的Round Robin算法在端到端延迟、系统吞吐量和包延迟等QoS服务性能方面都有显著的提高.     

Numerical analysis of fiber optical parameter amplifier based on triangular photonic crystal fiber

Due to triangular photonic crystal fiber (PCF) high nonlinearity and low dispersion slope, using the condition that the different linear phase shift combination must satisfy the phase match, the expressions of gain and bandwidth for one-pump fiber-optic parametric amplifiers (1P-FOPA) based on PCF in the normal and abnormal dispersion regimes are derived respectively. Then, 1P-FOPAs performance comparison among PCF, dispersion-shifted fiber (DSF) and highly nonlinear fibers (HNLF) are carried out by numerical simulations. It is shown that the 1P-FOPA based on triangular PCF can provide higher peak gain over wider bandwidth. When the pump wavelength is at the zero-dispersion wavelength (ZDWL), about 108.7 nm single-pass gain bandwidth and 91.4 dB peak gain can be obtained; when in the normal dispersion regime and near zero-dispersion wavelength, not less than 46 nm single-pass gain bandwidth 77.1 nm away from pump can be achieved. Finally the influence of dispersion fluctuation is analyzed, and the result shows that the tolerance of the 1P-FOPA based on photonic crystal fiber is better.     

实时时钟在智能仪表系统中的应用设计

本文介绍了实时时钟芯片PCF8583在基于单片微处理器的智能仪表系统中的数据实时记录、保存的应用设计技术,给出了与单片微处理器的硬件连接及系统软件流程图,其使用非常方便简洁,应用广泛。     

Orthogonal signaling-based queue status investigation method in IEEE 802.11

IEEE 802.11 specifies four different medium access control (MAC) protocols to coordinate multiple access in a wireless local area network (WLAN). Since several tens of stations can operate in a WLAN, the performance of MAC protocols is important for overall network efficiency. It has been observed that the IEEE 802.11 MAC protocols can be improved by knowing which station has a non-empty queue, i.e., queue status. The point coordination function (PCF) can use this information to avoid polling a station that has no pending data. The HCF controlled channel access can adapt polling parameters based on queue status information, especially when scheduling a bursty and variable bit-rate traffic. Previously suggested methods are rather limited in terms of accuracy and efficiency.In this paper, we propose a novel method to investigate the queue status of multiple stations by exploiting orthogonal signaling. With synchronous transmission of orthogonal codes and symbol level signal processing, the method allows all of the associated stations to report their queue status at the same time. Challenges that can arise in the implementation of the proposed method are identified, and their solutions are suggested. The feasibility of detecting orthogonal signals is thoroughly tested on a realistic channel model. To demonstrate the performance improvement of a MAC protocol, we applied the proposed method to PCF. Both analysis and simulation show that the modified PCF significantly outperforms not only the original PCF but also other previously suggested PCF enhancements.     

Probabilistic coherence spaces as a model of higher-order probabilistic computation

We study a probabilistic version of coherence spaces and show that these objects provide a model of linear logic. We build a model of the pure lambda-calculus in this setting and show how to interpret a probabilistic version of the functional language PCF. We give a probabilistic interpretation of the semantics of probabilistic PCF closed terms of ground type. Last we suggest a generalization of this approach, using Banach spaces.     

基于Linux的CDMA2000中报文控制功能的模拟

移动通信向第三代发展已成为必然趋势，基于CDMA2000中报文控制功能（PCF）和报文数据服务节点（PDSN）在网络中的作用，讨论了用计算机模拟PCF的两种可选方案，最后给出一种基于Linux平台的模拟PCF的具体实现，并论述了其中涉及的关键技术。     

802.11e无线局域网QoS技术研究

本文分析了IEEE802.11中DCF、PCF和IEEE802.11e中的EDCF、HCF四种接入机制。研究了这四种机制对实时业务的QoS支持能力。通过NS-2软件仿真得出,相比于802.11中的DCF、PCF,802.11e中的EDCF、HCF机制提高了实时业务的QoS。对当前WLAN网络中实时业务的传输有着重要的指导意义。     

基于光子晶体光纤F-P腔的高压电器温度传感器系统

基于光子晶体光纤F-P的窄带滤波特性和液晶折射率对温度变化敏感特性,提出了一种用于高压电器温度测量的温度传感器系统.该系统主要由液晶填充的光子晶体光纤F-P腔传感器、光纤F-P滤波器、放大电路和显示模块组成.将向列型液晶填充在光子晶体光纤F-P腔内,温度变化引起最大反射光强点波长的变化,采用光纤F-P腔滤波器解调出光波...     

改进的百分比靠近软阴影技术的研究与实现

百分比靠近软阴影算法可以生成视觉上逼真的软阴影,它是基于PCF内核的,随着PCF内核的增大,生成的软阴影逼真度越高,该算法的关键是通过变化滤波内核的大小来获得高质量的软阴影。在算法的遮挡物查找和滤波阶段,使用泊松圆盘采样来处理由于不适当地增加采样数目而产生的带状走样。同时在PCF内核中使用深度梯度来得到可变的深度偏移值,进而处理自阴影问题,改进了百分比靠近软阴影算法,从而生成更准确,更逼真的软阴影。     

Nanocrystalline graphite-like pyrolytic carbon film electrode for electrochemical sensing of hydrazine

Pyrolytic carbon film (PCF) electrode fabricated by a non-catalytic chemical vapor deposition (CVD) process was used as an electrochemical sensor for the detection of hydrazine. The electrode response was found to be electrocatalytic producing a reduction in the overpotential compared to other unmodified carbon-based electrodes such as glassy carbon (GC), basal-plane pyrolytic graphite (BPPG), and edge-plane pyrolytic graphite (EPPG) electrodes. The overall number of electrons involved in the electro-oxidation of hydrazine, the number of electrons involved in the rate-determining step, and diffusion coefficient of hydrazine at PCF electrode were estimated using cyclic voltammetry and chronoamperometry. The performance of PCF electrode was comparable to and in some cases even better than many chemically modified electrodes in terms of detection limit, linear dynamic range, and sensitivity. Moreover, the sensor exhibited fast response time (within 2 s), high response stability, and reproducibility. All the results indicated this sensor is suitable for hydrazine analysis.     

一种能量有效的无线传感器网络轮询接入控制协议

周期性休眠的PCF机制虽然较好地解决了无线传感器网络的能耗问题,但没有考虑节点的负载状态,降低了系统性能,也增加了系统的查询能耗.以限定(K=1)服务为基础,提出了一种改进的PCF轮询控制协议,即具有混合服务策略的无线传感器网络轮询接入控制协议PCF-SS.该协议在保障公平性的前提下,能够根据节点状态动态调整优先级并改变服务K值,中心服务器AP则根据各节点的服务K值在每轮服务时对节点的下一轮服务时间进行预估计,并采用统一的服务时间表唤醒节点,达到节能的效果.仿真实验表明系统的平均等待时间、平均排队队长等性能指标比周期性休眠的PCF机制要好,能量的有效利用率更高,具有更长的生命周期,适合作为无线传感器网络的MAC控制协议.     

一种提高PCF中非实时数据传输性能的方案

论文提出一种PCF的改进方案VPCF,提升竞争阶段非实时数据的传输性能。站点在无竞争阶段被轮询时向点协调者捎带将在竞争阶段传输的帧的退避计时器值;点协调者通过比较退避计时器值预见站点间的冲突并告知站点,采用一种称为虚冲突的机制避免站点冲突的发生。仿真表明,VPCF在不影响无竞争阶段实时数据发送的前提下减少了竞争阶段的冲突次数,提高了非实时数据的吞吐量。