共查询到20条相似文献,搜索用时 78 毫秒
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着重分析探讨当前嵌入式应用程序开发教学的教学内容及组织形式,针对学生学习嵌入式应用程序开发的学习现状,提出面向技术发展的嵌入式应用程序开发教学内容,包括嵌入式应用程序开发的程序开发模式的更新、开发语言的更新及驱动型项目的教学内容改革措施。 相似文献
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本文主要应用虚拟技术对电视机进行开发,在设计和开发过程中,主要对电视机的基本结构如电视机外壳、电子元器件、连接导线和PCB等结构要素进行交互操作、场景开发和动画控制,给出了详细的开发过程和开发效果图,对于电视机的开发具有一定的借鉴作用。 相似文献
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敏捷开发是目前较流行的一种软件开发方法,它汲取了多种传统软件开发方法的优点,但也区别于传统的软件开发方法。本文就敏捷开发和最常用的迭代式开发、瀑布式开发、螺旋开发作了一定的比较,重点阐述了敏捷开发的优点和特点。 相似文献
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适用于嵌入式开发团队的嵌入式开发成熟度模型和用于工程实施的持续改进措施,能保证嵌入式系统开发工程的质量。逐级递进设计过程不规范、缺乏设计流程持续性改进、开发模式混乱、需求分析随动性差等是嵌入式系统开发过程中必须解决的问题。为了增强工程实践应用,基于嵌入式系统开发过程的ESD-CMMI五级模型,总结了嵌入式系统本身开发特征,探讨了ESD-CMMI模型所对应的持续性改进方向,给出了嵌入式系统开发持续改进的行动步骤。 相似文献
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Two variations of a novel feeding technique for a wideband circularly polarized aperture-coupled microstrip antenna are described. Prototype designs for wideband linearly polarized elements are first presented, and then used for circularly polarized designs. Techniques used for design of the feed network are detailed, for both series feed and parallel feed versions. Experimental results are shown for each antenna, and results for the two designs are compared. The impedance and axial ratio bandwidths for these antennas are among the best yet achieved for microstrip antenna elements. Several design variations are also discussed 相似文献
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Russ Bleemer 《Alternatives to the High Cost of Litigation》2007,25(9):146-160
It's last call for three CPR doings: for the Fall Meeting in Boston later this month, for three trainings, and for nominations for the 2007 CPR Awards. Also, CPR member options for signing up for free electronic copies of Alternatives 相似文献
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Rain attenuation measurements over New Delhi carried out with a microwave radiometer installed at the National Physical Laboratory (NPL), New Delhi and operating on 11 GHz for a period of more than three years are presented. For 0.01 percent of time for the period June 1977-April 1978, the attenuation exceeded for the monsoon period is 14.0 dB whereas for the whole year, it exceeds 10.4 dB. During the winter for the same percentage of time, the attenuation exceeded 1.5 dB, whereas for March-April it exceeds 0.5 dB. For the period May 1978-June 1980, it is observed that for 0.01 percent of time the attenuation for the whole year exceeds 9.0 dB. During the winter for the same percentage of time, the attenuation exceeds 1.4 dB whereas for March-April it exceeds 0.4 dB. A comparison of attenuation over New Delhi and those reported elsewhere are discussed. Yearly and worst month time ratio over New Delhi are given also as the values reported for the European region. Comparison of the attenuation distribution and the rate of surface rainfall measured with a rapid-response rain gauge are also given. The comparison shows that for the monsoon period and for 0.01 percent of time, the attenuation value exceeded for 14 dB corresponds to the surface rainfall rate of 140 mm/h. For the monsoon of 1978, 1979, comparison shows that for 0.1 percent of time, the attenuation value exceeded for 9.0 dB corresponds to the surface rainfall rate of 90 mm/h. Variation of attenuation and effective path length for various rainfall rates and elevation angles are also given. 相似文献
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Characterization and performance evaluation of differentialshielded cables for multi-Gb/s data-rates
Deutsch A. Kopcsay G.V. Surovic C.W. Coteus P.W. Lanzetta A.P. Takken T. Bond P.W. 《Advanced Packaging, IEEE Transactions on》2002,25(1):102-117
This paper compares several differential cable characteristics that were evaluated for multi-Gb/s data-rates for both data and clock paths for 1-10 m lengths. Time-domain measurements are shown for the unassembled and connectorized cables and for representative card-plus-cable signal paths and the performance limiting factors are highlighted. Techniques are shown for developing coupled-line models for odd and even excitations for all the components in a full chip-to-chip path in order to make realistic data-rate predictions 相似文献
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Information Model for Resource of ASON Control Plane 总被引:2,自引:0,他引:2
XU Yun-bin SONG Hong-sheng GUI Xuan ZHANG Jie GU Wan-yi School of Telecommunications Engineering Beijing University of Posts Telecommunications Beijing P. R. China 《中国邮电高校学报(英文版)》2004,11(3)
1 Introduction Opticalnetworkshavebecomemorecomplicatedthanbefore ,andneednetworkmanagement.InASON ,theControlPlane (CP)isanewnetworkcomponent[1~ 3] ,inordertomanagethenewemergedresources ,anin formationmodelforCPisrequired . TheReferenceModelofOpenDistributedProcessing(RM ODP) providesanobjectorientedframeworkfordistributedmanagementsystemsthatallowsuser sdif ferentrequirementsformanagementapplications[4 ] .RM ODPhasprovideduswithanetworkmanagementviewpoint,anditprovidesfiveview… 相似文献
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设计了一种基于CCD的非接触尺寸测量系统.运用亚像素边缘检测法对圆环进行边缘检测,完成对圆环的非接触尺寸测量.利用数据库实现对测量数据的存储管理及网络传输.通过实验证明:对圆环测量精度外径误差0.005 mm,内径误差0.001 mm,壁厚误差0.015 mm,整体绝对误差小于0.02 mm,相对误差小于0.07%,满足了工程高精度测量要求.本系统适合有危害性的工业现场环境,数据的存储管理功能也给实际应用带来很大便利. 相似文献
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Methods are presented for the generation of the transfer polynomials, and then the direct synthesis of the corresponding canonical network coupling matrices for Chebyshev (i.e., prescribed-equiripple) filtering functions of the most general kind. A simple recursion technique is described for the generation of the polynomials for even- or odd-degree Chebyshev filtering functions with symmetrically or asymmetrically prescribed transmission zeros and/or group delay equalization zero pairs. The method for the synthesis of the coupling matrix for the corresponding single- or double-terminated network is then given. Finally, a novel direct technique, not involving optimization, for reconfiguring the matrix into a practical form suitable for realization with microwave resonator technology is introduced. These universal methods will be useful for the design of efficient high-performance microwave filters in a wide variety of technologies for application in space and terrestrial communication systems 相似文献
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Fernando Ramírez-Mireles 《Wireless Personal Communications》2014,78(2):915-925
In this work we study the channel capacity from the point of view of a secondary user that shares the bandwidth of the channel with a primary user using dynamic spectrum access in cognitive radio.The secondary user sees bandwidth fluctuations (i.e, at any given time the bandwidth can be available or not) that impact its channel capacity. We study the outage capacity for the secondary user considering two scenarios in which the secondary user uses either a single carrier modulation for the case in which bandwidth fluctuates over the complete transmission band, and a multicarrier modulation for the case in which bandwidth fluctuations are over various transmission subbands. We derive expressions for the outage capacity of the secondary user for both single carrier and multicarrier. Results show that: (1) The outage capacity for single carrier can be higher than for multicarrier, but with a higher outage probability for single carrier than for multicarrier. In fact, a low value of outage probability for single carrier requires a duty cycle for the secondary user close to one, but this has the problem that it leaves a very short duty cycle for the primary user. (2) Although for the secondary user the outage capacity for multicarrier is smaller than for single carrier, for multicarrier lower values of the outage probability can be achieved even for short values of the duty cycle of the secondary user, allowing larger duty cycle values of the primary user. (3) For multicarrier, the outage capacity is more sensitive to changes in the duty cycle than to changes in the outage probability. To obtain a larger outage capacity with low values of both the outage probability and the duty cycle, it requires the use of a large number of subbands. 相似文献
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A technique for the analysis and design of noniterative algorithms for discrete-time, band-limited signal extrapolation is described. The approach involves modeling the extrapolation process as a linear, time-varying (LTV) system, or filter. Together with a previously developed Fourier theory for LTV systems, this model provides a frequency-domain transfer function representation for the extrapolation system. This representation serves as a powerful tool for characterizing and comparing the reconstruction properties of several well-known least squares optimal algorithms for band-limited extrapolation. Moreover, the frequency-domain setting provides a conceptually attractive means for understanding the process of extrapolation itself. Additionally, a least squares approximation methodology for designing LTV filters for band-limited extrapolation is developed. The design technique is shown to unify a broad class of algorithms for extrapolating discrete-time data and, further, to provide a means for designing new and improved extrapolation algorithms 相似文献
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We consider optimum uniform data quantization for noisy channels. We present a general formulation for natural encoding that results in simple expressions for the mean-square error. Specifically, we show that the optimum location of the center of the quantizer is at the mean of the distribution for all error rates. The optimum levels for quantization and the corresponding mean-square error are presented for Gaussian and uniform data. For the latter the width of the optimum quantizer for noisy channels is shown to be smaller than the entire range of probability distribution. 相似文献