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排序方式: 共有4753条查询结果,搜索用时 31 毫秒
1.
为了加快工业生产中对数据信息的采集与处理,该文设计了一个运用欧姆龙CJ1W-SCU22模块与RFID设备通信的数据处理系统,兼顾采集、处理、存储等过程,通过该串行通信模块上的RS-232端口采用无协议通信方式与RFID设备进行数据的交换。主设备为NJ控制器,从设备为RFID读卡设备,主设备向从设备发送命令帧,从设备向主设备返回响应帧,数据转换为用户需要的字符型数据。同时上位机程序CX-Supervisor实时接收处理完的数据,并存储到ACCESS数据库中。  相似文献   
2.
The rising internet-of-things applications in home automation, smart wearables, healthcare monitoring demand small, area efficient, high-performance and low power radio frequency (RF) blocks for effective short-range communication. This growing market demand is addressed in this paper by proposing a fully CMOS radio frequency front-end (RFE) exploiting bulk effect. Apart from the primary function of frequency translation, proper circuit performance concerning the linearity, conversion gain, and noise figure is required for low-cost densely integrated transceivers operating in the 2.4 GHz ISM band. The proposed RFE at 2.4 GHz is designed and implemented in UMC 180 nm CMOS process technology with two modes of operation. In high gain mode (Mode-I), the post-layout simulation with SpectreRF shows a peak gain of 30.06 dB, IIP2 at 64.52 dBm, IIP3 at −2.74 dBm and a DSB-NF of 7.68 dB while consuming only 9.24 mW from the 1.8 V supply. In the high linear mode (Mode-II), the RFE achieves a higher IIP3 of 10.78 dBm, IIP2 of 91.56 dBm, the conversion gain of 23.5 dB, DSB-NF of 9.46 dB while consuming a low power of 3.6 mW. The fully CMOS circuit occupies a core area of only 0.0021 mm2. The proposed front-end exhibits a spurious free dynamic range (SFDR) of 81.18 dB ensuring the high dynamic operation of the wireless system.  相似文献   
3.
Recent advances in hardware technology have led to the development of low cost, power efficient and more feature rich devices that are amongst the most critical parts of communication networks. These devices or sensors can now sense data with more accuracy, process it by themselves and send it to the neighboring node or the sink node. However, robust and reliable security mechanisms are not yet properly implemented on these sensors due to their limited energy and computation power. Sensors also play a very important role in eHealthcare systems where ubiquitous patient monitoring is performed. As data is generated from the sensor nodes, reliable, secure and attack-resistant data acquisition and transmission is important for an efficient eHealthcare systems. This survey focuses on security issues of sensors data acquisition and transmission protocols, describing their main security features and comparing them in the context of a secure eHealthcare system. A taxonomy of open issues and future challenges is also discussed with respect to specific security metrics described in the paper.  相似文献   
4.
孙淑光  周琪 《计算机应用》2020,40(5):1522-1528
针对自动飞行控制系统结构复杂、关联部件众多,发生故障时诊断时间长,从而影响飞机运行效率的问题,提出一种基于飞机通信寻址报告系统(ACARS)的远程实时故障诊断方案。首先,分析自动飞行控制系统的故障特点,设计搭建检测滤波器;然后,利用ACARS数据链实时发送的自动飞行控制系统的关键信息进行相关部件的残差计算,并根据残差决策算法进行故障诊断及定位;最后,针对不同故障部件残差间的差异大、决策门限无法统一的缺点,提出基于二次差值的残差决策改进算法,减缓了检测对象的整体变化趋势,降低了随机噪声和干扰的影响,避免了将瞬态故障诊断为系统故障的情况。实验仿真结果表明,基于二次差值的改进残差决策算法避免了多决策门限的复杂性,在采样时间为0.1 s的情况下,故障检测所需时间大约为2 s,故障检测时间大幅降低,有效故障检测率大于90%。  相似文献   
5.
一流本科专业建设是新时代高等教育体制创新的重要举措,是高校贯彻科教兴国战略的落脚点。通过对“金课”建设的现状进行调查,以国际交流英语课程为切入点,分析了过于强调语言技能训练、“两性一度”尚有距离、不符合创新人才培养举措的问题,提出了“金课”建设的措施,即厘清课程实践目标、优化课程建设结构、丰富课程建设形态、提升教师实践能力,为高素质人才培养提供了新思路,实现高等教育的高质量发展。  相似文献   
6.
In this paper, the impact of communication time delays (CTDs) on combined load frequency control (LFC) and automatic voltage regulation (AVR) of a multi-area system with hybrid generation units is addressed. Investigation reveals that CTDs have significant effect on system performance. A classical PID controller is employed as a secondary regulator and its parametric gains are optimized with a differential evolution - artificial electric field algorithm (DE-AEFA). The superior performance of the presented algorithm is established by comparing with various optimization algorithms reported in the literature. The investigation is further extended to integration of redox flow batteries (RFBs) and interline power flow controller (IPFC) with tie-lines. Analysis reveals that IPFC and RFBs coordinated control enhances system dynamic performance. Finally, the robustness of the proposed control methodology is validated by sensitivity analysis during wide variations of system parameters and load.  相似文献   
7.
In this article we explore the role of innovation champions and the ways innovation is championed and promoted in five selected UK megaprojects. To date, this research area is surprisingly under-explored in the megaproject management literature. The study is based on thirty interviews with innovation champions to capture their own perceptions and narratives on the ways innovation is stimulated and promoted in megaprojects, combined with relevant textual materials. Innovation was commonly defined as a step change or best practice that creates value that could be financial, environmental, societal etc. The data demonstrate the role of CEOs and their collaboration with innovation champions and academic partners in introducing innovation into the vocabulary of megaprojects, developing and formalising innovation strategy, and transferring experiences across megaprojects. The data show the ways different communication channels are used to promote innovations by champions such as forums, portals, platforms, campaigns, events etc.  相似文献   
8.
The implementation of higher shares of renewables in a global energy mix has to be accompanied by simultaneous deployment of enabling smart grid technologies (SGTs). This combination will inevitably lead to a revolutionary change in a conventional energy system, particularly, the shifting role of consumers to prosumers. But resistance may arise from such a dramatic shift, since it is associated with high uncertainty in conjunction with increasing responsibilities of all stakeholders, the urgent need of effective control, and the development of a process. To ensure the positive influence, coherent actions of all players, and appropriate treatment of the spots of resistance, the analysis of the interplay between key stakeholders has been done. The paper introduces the framework for stakeholders' analysis, applies it on the European Union (EU) example, and provides recommendations to reduce the resistance of SGTs deployment.  相似文献   
9.
徐潜  谭成翔 《计算机科学》2015,42(11):191-196, 221
针对Android存在的特权提升攻击问题,提出了基于动态权限集的Android强制访问控制模型DP_ManDroid。该模型首先分析强连通分支的权限分布特性,构建动态的权限集划分;然后在信息流与权限集耦合的基础上,抽象权限提升路径;最后提出线性时间的访问控制算法,并通过动态追踪权限集,实现了细粒度的决策控制。与现有 安全模型的对比,以及在原型系统上的仿真结果表明,所提出的安全模型很好地抵御了特权提升攻击,同时降低了时间复杂度。  相似文献   
10.
针对变换域通信系统传统硬门限判决算法漏检和误检的问题,为提高系统的抗干扰性能,提出一种自适应N-sigma幅度谱成型算法。该算法通过频谱感知获得环境功率谱的幅值信息,计算环境功率谱的均值和标准差;根据正态分布相关理论,自适应设置门限。若电磁环境发生变化,均值和标准差会重新调整更新门限。仿真结果表明,相比传统的硬门限判决算法,自适应N-sigma幅度谱成型算法的门限设置更加灵活精确,降低了干扰的漏检概率和误检概率,提高了系统的抗干扰性能。  相似文献   
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