FET开关特性在手机电路中的应用

无论对现在以TDMA为主流的手机,还是下一代以CDMA为主导技术的3G手机,其内部电路大都是以时隙为时间单元断续地工作,为延长手机待机时问,电路设计是以时隙为时间单元作断续供电.FET是利用电场来控制其导通与截止的器件,具有良好的开关特性,它在手机的收发电路供电控制、电池充电电路控制、发射功率大小控制等部分起着关键性的作用.文中结合FET在手机中的典型应用,对其结构、原理及工作过程作了详细的探讨.     

Critical time of the lognormal distribution

The critical time is the time point as the failure rate starts to decrease and also as the mean residual lifetime starts to increase. The estimated critical time is useful for determining the duration of a burn-in process. The method for estimating the critical time of the failure rate for lognormal lifetime distribution is discussed. A single time censored data is used as a example for illustration.     

Astronomical time

Astronomical time serves as the basis for civil time and is required to describe the orientation of the Earth with respect to an inertial reference frame. The definitions of astronomical time scales are reviewed as well as observational methods. The causes of the variations in the Earth's rotation are explained and a brief overview of international efforts to maintain astronomical time scales is presented     

Characterization of operational time variability using effective process times

Operational time variability is one of the key parameters determining the average cycle time of lots. Many different sources of variability can be identified such as machine breakdowns, setup, and operator availability. However, an appropriate measure to quantify variability is missing. Measures such as overall equipment effectiveness (OEE) used in the semiconductor industry are entirely based on mean value analysis and do not include variances. The main contribution of this paper is the development of a new algorithm that enables estimation of the mean effective process time t/sub e/ and the coefficient of variation c/sub e//sup 2/ of a multiple machine workstation from real fab data. The algorithm formalizes the effective process time definitions as known in the literature. The algorithm quantifies the claims of machine capacity by lots, which include time losses due to down time, setup time, and other irregularities. The estimated t/sub e/ and c/sub e//sup 2/ values can be interpreted in accordance with the well-known G/G/m queueing relations. Some test examples as well as an elaborate case from the semiconductor industry show the potential of the new effective process time algorithm for cycle time reduction programs.     

一种基于频繁模式的时间序列分类框架

如何提取和选择时间序列的特征是时间序列分类领域两个重要的问题。该文提出MNOE(Mining Non- Overlap Episode)算法计算时间序列中的非重叠频繁模式,并将其作为时间序列特征。基于这些非重叠频繁模式,该文提出EGMAMC(Episode Generated Mixed memory Aggregation Markov Chain)模型描述时间序列。根据似然比检验原理,从理论上推导出频繁模式在时间序列中出现的次数和EGMAMC模型是否能显著描述时间序列之间的关系;根据信息增益定义,选择能显著描述时间序列的频繁模式作为时间序列特征输入分类模型。在UCI (University of California Irvine)公共数据集和实际智能楼宇数据集上的实验表明,选择频繁模式作为特征进行分类的准确率、召回率和F-Measure均优于不选择频繁模式作为特征的分类结果。高效的计算和有效的选择非重叠频繁模式作为时间序列特征有助于提高时间序列分类模型的各项评价指标。     

Preserving the Moment, Commodifying Time, and Improving Upon the Past: Insights Into the Depiction of Time in American Advertising

Despite its pervasiveness in ads, the depiction of time in American advertising remains one of the least understood cultural values, perhaps because of its complexity and its taken-for-grantedness. Using a sample of magazine ads, this study adds to the existing knowledge and provides new insights into 5 time categories: limited time, marking time, more time, planning time, and oriented time. Examples and frequencies of time categories are provided with an analysis of use across product categories. The study also provides insights into how advertising as a cultural product sends "unintended" messages about cultural values. Despite the availability of alternative time concepts, the time categories observed in this study exclusively support the monochronic culture (Hall, 1983), making it appear as the only time system available.     

UWB系统多址接入方法的比较研究

研究UWB系统多址接入技术的主要目的是在尽量减少多址之间的干扰,降低接收机的复杂度,实现低功耗、低成本。从误码率理论分析、性能仿真和接收机结构等几个方面对混沌序列扩频与伪随机序列扩频、伪混沌跳时与传统跳时多址接入方式进行比较研究。结果表明,在系统误码率方面,伪随机序列扩频优于混沌序列扩频,传统跳时优于伪混沌跳时;在接收机复杂度方面,混沌序列扩频和传统跳时较好。     

对通信工程项目施工的时间管理

在通信工程项目施工中,时间管理是非常重要的一环,可以说时间管理的好坏会决定整个项目的成败,因此要正确认识到通信工程项目中时间管理的重要性。本文通过对通信工程项目时间管理的重点和难点的分析,以及一个实例来对通信工程项目施工的时间管理进行详细的探讨。     

C/S方式软件时统的研究与开发

就实时测控软件的开发与运行环境问题,简单介绍了硬件时统设备在实时测控中的作用和重要地位以及实时操作系统的时间管理方式。针对软件时统设计中的两个关键技术展开分析与讨论,对软件时统的主要功能设计进行了重点描述,并给出便于程序开发的控制流图。     

变电站用同步时间服务器的实现

在此设计一款具有多个输入钟源和多个输出接口的同步时间服务器,它采用FPGA实现时间接口,用MCU作为控制器,输入GPS引擎M12T,IRIG—B,IEEE1588等作为标准时钟源,利用多路选择器得到系统标准时间,通过低频数字锁相环提供同步输出。该系统还可实现IRIG—B直流码和交流码,利用硬件实现NTP和PTP时间戳及相关的网络时间协议。其中,多路时间选择和基准时间产生及同步用低频数字锁相环和同步时间编码输出是创新之举。系统采用VHDL进行逻辑综合,软件采用C语言进行编程,通过软件仿真和示波器观测以及现场运行表明,系统同步和定时精确可靠,完全达到预期目标。     

Power-induced time division on asynchronous channels

Time division multiple access offers certain well-known advantages over methods such as spread spectrum code division. Foremost is the interference immunity provided by dedicated time slots. Partly offsetting this is TDMA's need for network-wide synchronization. Viewing arbitrary time intervals as potential TDMA time slots, we ask whether it is possible to obtain some of the benefit of time division without incurring the synchronization cost. In particular, we address the question of whether a TDMA-like state can be induced on asynchronous channels in such a way as to reduce interference and energy consumption. Through analysis and simulation we find conditions under which it is beneficial to use time division, and then show how autonomous power management may be used as a mechanism to induce a form of time division. In this context a backlog-sensitive power management system is presented.     

Generalized feature extraction for time-varying autoregressivemodels

In this paper, a feature extraction scheme for a general type of nonstationary time series is described. A non-stationary time series is one in which the statistics of the process are a function of time; this time dependency makes it impossible to utilize standard globally derived statistical attributes such as autocorrelations, partial correlations, and higher order moments as features. In order to overcome this difficulty, the time series vectors are considered within a finite-time interval and are modeled as time-varying autoregressive (AR) processes. The AR coefficients that characterize the process are functions of time that may be represented by a family of basis vectors. A novel Bayesian formulation is developed that allows the model order of a time-varying AR process as well as the form of the family of basis vectors used in the representation of each of the AR coefficients to be determined. The corresponding basis coefficients are then invariant over the time window and, since they directly relate to the time-varying AR coefficients, are suitable features for discrimination. Results illustrate the effectiveness of the method     

影响卫星导航定位系统精度的关键技术

对影响导航定位系统定位精度的各种因素进行了分析。研究了影响导航定位精度的关键技术问题,如时间基准、时间同步和卫星定轨等。叙述了GPS系统的时间基准精度的国内外技术水平,以及时间同步的各种常用方法,如单向时间传递、共视时间传递和双向时间传递等。描述了影响卫星定轨的各种因素,特别是地球重力、月球引力、宇宙引力、大气阻力和阳光光压等对卫星轨道的作用。指明了卫星导航系统的主要误差源或影响定位精度的主要因素。     

Modelling the repairability function by the first passage time distribution of Brownian motion

This paper puts forward the first passage time distribution of Brownian motion as a repairability model. The paper fits the model to observed active repair data of radar systems, obtaining as a result estimates of the mean first passage time, drift and diffusion parameters of the associated Brownian motion. Hypothesizing the first passage time distribution of Brownian motion for active repair time data of radar systems, the Kolmogorov-Smirnov test shows that the model is accepted and can be chosen as the parent population.     

噪声引导混沌同步的同步时间分析

以Logistic映射为物理模型,计算了噪声混沌系统的Lyapunov指数谱,并利用其分析了噪卢分布区间与同步时间的关系．发现同步时间与噪声分布区间内的平均Lyapunov指数直接相关．若陔区间的平均Lyapunov指数越小,则同步时间越短。最后,提出了一种基于统计分析的时间阈值估算方法．并用该方法估算了Logistic系统在不同同步精度下的时间阈值。     

复合量子点MOSFET结构存储器的电路模拟

本文采用准经典近似的Monte Carlo方法对复合量子点MOSFET结构存储器的等效单电子电路进行了模拟.研究结果表明,由于台阶状的复合隧穿势垒的作用,存储器的存储时间特性可得到极大提高.我们进一步研究了N沟道锗/硅复合量子点MOSFET结构存储器的时间特性,得到其存储时间可长达数年,同时写擦时间可分别为μs和ns量级,从而这种新型的器件结构可以有效解决快速编程和长久存储间的矛盾.     

Potential for citizen time savings with 911 access

Much time and discussion is focused on the response time of public safety agencies during an emergency. Little or no time has been spent discussing the time it takes the citizen to access a public safety agency during an emergency. However, preliminary research indicates that after the citizen decides to call for help, substantial time may be spent by the citizen in trying to access the appropriate agency. Many agencies feel that three minutes is the maximum response time allowable in an emergency and consider citizen access time to be negligible. However, SRI International found that the average time spent by citizins for agency access is also three minutes. Many citizens spend substantially more time than the average, particularly when they have difficulty identifying the appropriate agency. The problems encountered by citizens while trying to locate and contact the appropriate agency are described. Areas where a single number, such as 911, is most useful, as well as those areas where it is less useful to the citizen, are discussed.     

灰色预估神经网络在时滞系统控制中的应用

针对过程控制中由于系统时滞引起的建模和控制方面的困难,提出了利用RBF神经网络对系统时滞进行辨识,采用灰色预估器对系统输出进行预测,并以此替代系统未来的实际输出反馈给输入端,最后利用RBF神经网络控制器对系统进行控制,有效地提高了控制器对时滞变化的自适应性。通过在一个具有时滞的加热炉系统中的应用,说明此方法能够克服不定时滞的影响,使控制目标具有良好的动态和静态性能。     

Activation of nitrogen implants in 6H-SiC

We have studied the effect of anneal time and temperature on activation of high-dose nitrogen implants into 6H-SiC. At a fixed anneal temperature, a strong dependence on anneal time is seen. For short anneals, the resistivity initially decreases with anneal time. After a minimum resistivity is reached, resistivity increases with further anneal. The optimum anneal time for minimum resistiv-ity increases as anneal temperature is reduced. Successful activation has been achieved at temperatures as low as 900°C.     

Enhanced Resource Blocks Management in D2D based Communication for 5G Networks

D2D based communication holds a promising future for 5G networks as they are efficient and can yield high data rates, good signal to noise interference ratio, improved resource-block uploading time, minimized delay from one end to the other and conserved power for transmission. The traditional system of cellular type contains cell edge clients who need a larger resource blocks count as well as time to upload data. Hence the quality of service will be reduced. The relay scheme in the proposal for cooperative type D2D networks is pivoted on the value of channel gain as well as transmission link distance. For bringing down the resource blocks’ count as well as uploading time, the paper is proposing a capable scheme of selection of relays that employs communication of D2D in the situations of uplinking. To begin with, in a cell modeling is done. It contains D2D pairs of multiple types as well as cellular clients. Next, the analysis related to issues of allocating resources as well as control of power is done. In order to lessen the resource blocks as well as their uploading time, the paper in proposal suggests a better blocks management mechanism that uses D2D based communication. Simulated output infers that the method in the proposal is superior to the present methods as far as time to upload contents; resource blocks, SINR, throughput as well as rates of data and Energy Consumption are concerned. Added to that, the stated method conserves 43% of the Energy Consumption of the network clients and while doing that the time to upload the contents is not affected.