建筑外延

文章将建筑师从事建筑学领域以外的活动分类梳理为四个方向——生活体验、艺术创作、空间运营、媒体传播,发现外延活动的共性所在,并期待其对建筑学本身的影响可以成为值得研究的课题。     

直接序列扩频系统的多次驻留顺序捕获

本文利用矩阵变换方法对多次驻留顺序捕获的平均捕获时间表示式进行了推导,其过程较信号流图法简单。同时还给出了一次、二次及三次驻留顺序捕获系统的平均捕获时间的计算实例。     

突发式连续波发射机工作方式的设计

本文较详细地讨论了突发式连续波发射机工作的设计思想,设计方法,采用的技术措施。     

Resource allocation in MIMO‐OFDM‐based cooperative cognitive radio networks: optimal and suboptimal low complexity approaches

The problem of resources allocation in multiple‐input multiple‐output‐orthogonal frequency division multiplexing based cooperative cognitive radio networks is considered, in this paper. The cooperation strategy between the secondary users is decode‐and‐forward (DF) strategy. In order to obtain an optimal subcarrier pairing, relay selection and power allocation in the system, the dual decomposition technique is recruited. The optimal resource allocation is realized under the individual power constraints in source and relays so that the sum rate is maximized while the interference induced to the primary system is kept below a pre‐specified interference temperature limit. Moreover, because of the high computational complexity of the optimal approach, a suboptimal algorithm is further proposed. The jointly allocation of the resources in suboptimal algorithm is carried out taking into account the channel qualities, the DF cooperation strategy, the interference induced to the primary system and the individual power budgets. The performance of the different approaches and the impact of the constraint values and deploying multiple antennas at users are discussed through the numerical simulation results. Copyright © 2014 John Wiley & Sons, Ltd.     

5G网络中通信运营商的安全布局分析

针对5G网络的逐步商业化推进环境下通信运营商面对的需求、业务和挑战到通信运营商的网络安全责任。基于对网络安全构架和业务特征化的安全布局进行分析,重点对5G网络业务切片下的网络安全管理进行了安全策略差异化分析,着重提出了网络安全布局和策略建议。     

Bare necessities: the argument for a ‘revenge porn’ exception in Section 230 immunity

‘Revenge porn’ is the online posting of nude or sexually explicit photographs or videos of a former lover without his or her consent. Despite the malicious intent behind revenge porn, victims are provided with little to no relief due to Section 230 of the Federal Communications Decency Act, also known as the ‘Good Samaritan’ provisions. Section 230 unambiguously provides blanket immunity for website operators and Internet service providers that feature user-generated content, including revenge porn.

In Section 1, I discuss the purpose of Section 230 of the Communication Decency Act. In Section 2, I analyze the legal impact of the blanket immunity established in Section 230. In Section 3, I examine the potential remedies already in existence for revenge porn victims and highlight their inadequacies. In Section 4, I argue Congress should create a narrow exception to Section 230 immunity specifically geared toward revenge porn. The exception would establish a definition of revenge porn, which would prevent over-deterrence. Additionally, the exception would institute a takedown procedure similar to the process found in the Digital Millennium Copyright Act. In creating a narrow exception, the spirit of Section 230 will remain while also providing adequate legal relief for victims of revenge porn.     

西门子PLC总线技术在特种氧化铝微粉系统中的应用

通过Profibus-DP总线技术实现西门子S7-300系列PLC系统与现场智能设备之间的通信。该PLC控制系统总线连接设备有ABB ACS800变频器,施耐德ATV71变频器,智能MMC保护装置。通过数据采集处理完成对电气设备的实时数据监控和控制。     

浅析计算机网络通讯存在的问题及其改进策略

随着计算机技术取得的长足发展以及计算机的日益普及,计算机网络通讯已成为人们生活及工作中的不可或缺的组成部分。虽然计算机网络通讯极大的方便了人与人之间的沟通,但是仍然存在诸多问题,主要表现在网络通讯技术故障和网络通讯安全方面。网络故障问题主要是硬件连接和软件设置问题,网络通讯安全问题主要体现在非法窃听、恶意篡改、假冒以及对个人信息的非法操作等方面。本文简要剖析了计算机网络通讯当前存在的问题以及针对问题提出了相应解决方案。     

Improving bit error rate under burst noise in OFDM power line communications

Noise in Power Line Communications is typically impulsive, with impulses being a fraction of the OFDM symbol length. Because of their large duration the impulse can also be called bursts. The short duration of the burst compared with the OFDM symbol length implies that there is a strong correlation between the noise at different carriers, given a determined burst position. The position can be determined using an estimate of the noise after a first demodulation. The high correlation is used to develop demodulators with a reduced bit error rate in comparison with conventional demodulators, so increasing the capacity. The demodulators use a smoothed estimate of the noise signal or a new metric for the distance based on the new correlation matrix. About half of the bit errors can be corrected in this way, corresponding to a 1 dB improvement in Signal Noise Ratio (SNR). How to split the OFDM symbol without increasing the overhead due to the circular prefix is also shown. Noise measurements in power lines are presented. These measurements are used in the simulations.     

PLC在机房环境监控系统中的应用

基于PLC设计了一套机房环境监控系统,系统可监测机房环境、UPS运行状态、智能空调运行状态。系统可通过GSM短信息的方式将异常情况及时通知工作人员,实现机房的无人职守。