Mapping Visual Studies in Communication

This essay documents the main currents of visual studies in communication. After a brief history of the emergence of the field, we review the record of published research in books and journals during the past 5 years, identifying major strains of theory, key issues, and topical categories. We then apply the strains of thought to classify papers presented at the ICA conferences, noting patterns and shifts across and within ICA divisions and interest groups. Based on these patterns, as well as on informal input from colleagues, we map the discipline formation of visual studies and identify trends in institutional development. We conclude by exploring future directions for the field now that the visual interest group has grown to become the Visual Studies Division of ICA.     

Organizational Communication: Challenges for the New Century

Organizational communication covers an eclectic mix of approaches, theories, and methodologies, developed within organizational settings or applied from other areas. The authors start their assessment of recent literature with 6 challenges for the field that have been delineated in previous reviews: (a) to innovate in theory and methodology, (b) to acknowledge the role of ethics, (c) to move from micro- to macrolevel issues, (d) to examine new organizational structures and technologies, (e) to understand the communication of organizational change, and (f) to explore diversity and intergroup aspects of communication. All 6 challenges implicate the importance of considering the intergroup level of analysis as well as the interpersonal and organizational levels, to undertake multilevel research in context, and to consider the role and place of voice in organizations. Finally, researchers must make their research ethical and consequential.     

Public Relations: State of the Field

Public relations is both a professional practice and a subfield of communication with its own research and theory base. Public relations is relatively young as an academic field, however, having developed identifiable theory in only about the last 50 years. The field of public relations is developing into a theoretically based area of applied communication that has the potential to inform several areas of communication/mass communication and to offer theoretic and conceptual tools useful in health, risk, and political communication, among others. Because many readers are unfamiliar with public relations theory and research, this article first reviews and summarizes theory-related scholarship in public relations, then categorizes and explains the theoretic trends in the field. The article concludes by demonstrating how one of public relations' theoretic/conceptual tools, issues management, can apply across all areas of applied communication.     

Role of Trichocytic Keratins in Anti-Neuroinflammatory Effects After Spinal Cord Injury

Shifting microglia/macrophages to M2 anti-inflammatory phenotype is considered a pivotal therapeutic target for spinal cord injury (SCI). Keratin extracted from human hair exhibits anti-inflammatory properties. However, the differences among the 17 types of human hair keratins and their mechanisms of anti-inflammation remain poorly understood. In this study, the anti-inflammatory activity of 17 human hair keratins using a recombinant synthesis approach is explored. Distinct activities of microglia/macrophage phenotype modulation of 17 keratins are found through qRT-PCR analysis, and recombinant keratin 33A (RK33A) and RK35 display superior anti-inflammatory efficiency compared to other keratins. Immunofluorescence and flow cytometry reveals a significant effect of RK33A on the regulation of microglia/macrophages into an anti-inflammatory M2 phenotype. Subsequently, recombinant keratin 33A nanofiber (RKNF33A) is fabricated to evaluate its in vivo anti-inflammatory and nerve regeneration properties using the rat T9 spinal cord lateral hemisection model. The optimized keratin-based nanofiber shows outstanding performance in enhancing M2 polarization, reducing glial scarring, promoting nerve regeneration, and improving locomotor function recovery in SCI rats. Moreover, it is preliminarily found that RK33A regulates M2 microglia/macrophage polarization by upregulating the PI3K/AKT/mTOR signaling pathway. Together, this study reveals that trichocytic keratins exhibit distinct anti-inflammatory properties, providing a prospective treatment for SCI by modulating microglia/macrophage polarization.     

ICO G1卫星移动通信系统

本文首先从空间段、地面段和用户段三个方面对美国ICO G1卫星移动通信系统的组成进行了分析和介绍;其次对ICO G1采用的主要关键技术进行了剖析;最后介绍了ICOG1系统的主要功能及发展现状。     

电力线通信系统中的子载波组分配

研究电力线通信系统在各种约束下的速率自适应子载波分配模型,提出一种基于层次分析法的动态子载波组分配算法。为了对比还提出以一种不含决策者偏好信息和比特功率比最大化的逐子载波分配算法。在典型电力线信道环境下还仿真以一个子载波为一组的子载波组分配算法,结果表明一子载波一组的子载波组分配算法性能最优,但其复杂度最大,而动态子载波组分配算法的性能与逐子载波分配对比算法的性能相当,且接近于一子载波一组的分配算法,复杂度大大减少。     

移动通信机房电源系统节能潜力分析

结合移动通信机房中电源产品性能及配电系统结构存在的问题,文章从电源产品的本体效率,配电系统功率因数及谐波改善,配电系统的结构性调整等各方面有针对性对电源系统节能潜力进行分析,并给出各节能手段的可执行方式和具体措施。     

提高通信对抗装备的可靠性

分析了通信对抗装备的可靠性现状，对影响可靠性的因素进行了初步的探讨，并针对如何提高装备的可靠性提出了几点建议。     

一种适用于卫星通信的低噪声放大器设计

采用高频电路仿真软件ADS,结合高频电磁仿真软件HFSS,进行联合仿真,设计了一种低噪声放大器,适用于Ku频段卫星通信接收通道。在频率11.45 GHz-12.75 GHz范围内,噪声系数小于0.80 dB,端口输入驻波小于-17.0 dB,有一定的实用价值。     

卫星集群组呼业务通知过程

集群通信在指挥调度及抢险救灾中发挥中重要作用,目前地面集群通信网络的覆盖范围有限,在处理有些紧急事件时可能会超出网络覆盖。依托通信对距离不敏感的卫星移动通信,在GMR-1标准基础上实现组呼呼叫业务功能,可以扩大集群通信的覆盖面积。对空闲模式下组呼通知过程进行了研究,对处于空闲模式下的移动台使用简化的NCH监听机制做了概述,最后提出了组呼通知信道的配置方法,计算得到NCH信道可以支持的话务量,与现有的GSM网络通信的相比具有更高的寻呼效率、可以承栽更大的用户数量。     

Circuit Topology Analysis of CMOS LNA in Mobile Communication Systems

1　Introduction　Now ,mostoftheLNAinRFreceiversarede signedwithGaAsorbipolartechnologies,whichhavealargepowerdissipationandunfavorableper formanceofintegration .CMOStechnologiestakeincreasinglyadvantagesoftechnologyadvances,whichhaveverylow powerconsumptionandmakepossibletheintegrationofcompletecommunicationsystems[1 ] .Forexample ,mobilecommunicationsystemreceiversemployextensivedigitalsignalpro cessingtoperformacquisition ,tracking ,anddecod ingfunctions.TheuseofCMOStechnologiesforimpl…     

基于LTE的移动物联网通信新技术发展综述

据统计,到2025年,全球物联网的终端连接将达到50亿以上,这显然是一个颠覆性的机会。在此背景下,满足物联网广覆盖、大容量、低功耗和低成本等特定需求的新型LPWA低功耗广域覆盖通信技术应运而生,包括两种基于LTE的移动通信新技术:Cat-NB1和Cat-M1。对上述两种技术的演进和关键技术进行了分析和比较,并深入研究了两者用到的核心低功耗技术和应用,最后分析了基于LTE的移动物联网通信新技术的实现策略,并对其应用和发展进行了展望。     

800Hz通信电缆屏蔽系数的计算

文章分析了通信电缆800Hz磁屏蔽系数的计算方法,并根据现行行业规范及国际导则中给定的部分参数建议值,对不同情况下的屏蔽系数进行了计算。计算结果表明,现有文献中给出的屏蔽系数参考值有些偏小,进而会影响通信双线回路中杂音电动势计算的准确性。     

单极变换技术在通信电源中的应用

介绍一种新的实现三相有源功率因数校正电路一单极变换电路，本介绍的单级变换电路具有功率因数校正与DC／DC变换两个电路的功能，该主电路的特点是结构简单，工作可靠。     

保密通信中的分形调制技术

分形调制在保密通信中具有广阔的应用前景。介绍了分形调制的原理,讨论了其在多速率分集、抗1/f噪声、抗频率选择性衰落、适用于信道条件复杂的MIMO通信系统等方面的特点。由于作为密钥的小波基任意多,且可根据信道情况在不同的小波基之间跳变,故分形调制具有极强的保密性和抗破译能力。