基于神经网络的认知无线电合作频谱感知     

薛建伟  唐亮  卜智勇 《中国科学院大学学报》2020,37(3):379-386

认知无线电是一种可用于有效缓解当前频谱资源紧张的技术，而频谱感知是认知无线电的前提。针对低信噪比情况下频谱感知性能差的问题，提出一种将信号高阶统计量、协方差矩阵特征值与神经网络相结合的合作频谱感知算法。该算法考虑到认知用户与授权用户的信道衰落情况，利用神经网络较强的多分类能力，将最大-最小特征值之比、平均-最小特征值之比以及高阶统计量作为特征参数，通过神经网络实现合作频谱感知。仿真结果表明，该算法不仅在低信噪比情况下较其他算法具有更高的频谱检测率，而且对频谱中信号的调制类型也有较高的识别率。  相似文献   

Experimental and Numerical Analysis of a Novel Display Case Design: Case Study of the Renovated Anne Frank House     

Karin Kompatscher  Bart Ankersmit  Edgar Neuhaus  Marcel A.P. van Aarle  Jos W.M. van Schijndel  Henk L. Schellen 《文物保护研究》2020,65(5):262-284

ABSTRACT

Many museums are housed in historic buildings, sometimes the building itself is part of the museum collection. Creating a stable environment by providing a nearly constant temperature and relative humidity at correct levels decreases the risk of object degradation. Maintaining this steady indoor environment, however, increases energy consumption and risks to the historic building. Museum display cases offer a solution to the mitigation of risks to which valuable objects may be subjected by providing an extra layer of protection to indoor climate fluctuations. The Anne Frank House is a historic house museum located in Amsterdam. The museum has undergone several renovations in the last years to deal with an increase in the number of visitors to over 1.2 million a year. The original diaries and other documents of Anne Frank are permanently on display in the Anne Frank House. With the recent refurbishment the possibility arose to design a new state-of-the-art display case. This study presents the results of the experimental research related to the design, performed in-situ. The temperature and relative humidity in the new exhibition space and inside the new display cases were monitored to gain insight into the hygrothermal behavior of these controlled environments. A complementary numerical study was performed to investigate effects of dynamic climate control of the exhibition gallery and climate conditions in the display case under various circumstances. Four main conclusions are presented in this paper. The investigated display case design is able to provide a stable relative humidity environment by means of silica gel, while using an active box-in-box climate control system to create stable temperature conditions. The inner case temperature depends on the temperature supplied by the display case air handling unit. Protocols must be in place in case of malfunction or failure of the climate control system of the display case. The air handling unit of the case needs to be shut off to create a passive environment for the objects on display until necessary actions are taken. Exhibition gallery set points can be less stringent when susceptible museum objects are on display in the display case. The environments are separated and provide an opportunity for energy saving set point strategies. The last conclusion drawn is that the numerical study provides valuable insight into imposing dynamic control of set points for temperature and relative humidity in the exhibition gallery and the effect on the display case environment.  相似文献   

From shanzhai chic to Gangnam style: seven practices of cultural-economic mediation in China and Korea     

Tommy Tse  Victor Shin  Ling Tung Tsang 《Journal of Cultural Economy》2020,13(5):511-530

ABSTRACT

This paper examines the social construction of ‘fashionability’ – namely, what is ‘desirable’ and ‘fashionable’ – with reference to the concept ‘cultural mediators’ that foregrounds agency, negotiation and the contested practices of market actors in cultural production. It zeroes in on the cultural mediators’ attitudes and positions in the two markets by drawing on 25 in-depth interviews with industry veterans. It shows that the mediators in South Korea and China increasingly occupy hybrid occupational roles and social positions across industries and sectors yet achieve limited success in countering the status quo of Western fashion through mediation. The analysis contributes to the literature with a categorisation of seven mediation practices that shape the valuation of fashion products (i.e. ‘fashionability’) in two ways. Empirically, this categorisation illuminates how cultural mediators make reference habitually to the broader social and cultural contexts to co-construct cultural-aesthetic objects. Theoretically, it advances a cultural-economic approach to the understanding of cultural mediation and challenges the reductionist viewpoint of actor–network theory through the notion of a matrix of cultural-economic agency.  相似文献   

Dialogic processes that enable student teachers' learning about pupil learning in mentoring conversations in a Lesson Study field practice     

《Teaching and Teacher Education》2018

This study investigates dialogic processes in student teachers' mentoring conversations in field practice, where Lesson Study (LS) was used as a context for establishing a dialogic learning community in one student group in science. We apply an analytical framework associated with Sociocultural Discourse Analysis to identify utterances that have the potential to create a dialogic space and contribute to ‘interthinking’ among the participants. The findings show the important role of the mentor teacher as a facilitator and a ‘knowledgeable other’, challenging the student teachers to reflect on chosen activities using predictions and detailed observations related to pupils' learning.  相似文献   

The temporal pocket: 1990s Beijing artist colonies     

Christen Cornell 《Inter-Asia Cultural Studies》2018,19(1):58-71

In recent years, a small but growing body of scholarship has emerged on the category of the Chinese art district, particularly its institutionalisation amidst twenty-first century creative industries polices. Such research presents important stories of Chinese artists’ negotiations with urban and political authority, thus nuancing paradigms for the comprehension of political work within contemporary China. This current article contributes to this growing research area by considering the spatial conditions for these socio-spatial categories’ emergence, namely, the urban structures in which they first took shape in 1990s Beijing. First occupying traditional villages (cunzi) and later ex-socialist work units (danwei), these arts colonies appropriated existing communal architecture, and turned their designs and physical buildings to their own communal ends. Importantly, these sites were made available by the dramatic reconstruction of the city, and in this sense these occupations were limited to the temporal realm. To describe the nature of occupations, and their eventual impact upon the shape of the city, this paper proposes the category of “the temporal pocket”: a cellular and temporary inhabitance, defined by the shared investments of its participants, and one that is both discrete (in the sense of its spaces) and discreet (in the sense that this can be understood as a non-oppositional politics). The article is informed by spatial and cultural theory, literature on Chinese urban planning and art history, as well as primary documents (such as documentaries, art works and archival material) and interviews conducted by the researcher in Beijing.  相似文献   

Motivation profiles of urban preservice teachers: Relations to socialization,initial career perceptions,and demographics     

《Contemporary educational psychology》2021

Given the perennial challenge of attracting and retaining high-quality teachers, especially in large cities, there is a need to understand why preservice teachers in urban districts choose a teaching career, their perceptions of the profession, and how these relate to their initial career commitments and aspirations. Using latent profile analysis, we examined patterns of motivational perceptions with variables from the Factors Influencing Teacher Choice model alongside perceived task effort cost, opportunity cost, and emotional cost of teaching within a diverse sample of 630 preservice teachers. We identified four distinct profiles that differentially related to theorized antecedents (prior teaching and learning experiences, social encouragement, fallback career) and outcomes (satisfaction, planned persistence, planned professional development, leadership aspirations). Race, gender and certification-level were distributed in unique patterns across profiles. Results provide a holistic perspective of preservice teacher motivations and indicate that perceived costs in relation to FIT Choice variables were a defining characteristic of motivational patterns.  相似文献   

高校潜水专业可持续发展影响因素研究——以岭南师范学院为例     

黎明 《体育科技文献通报》2020,(1):158-160

在SWOT总体框架下运用德尔菲法和层次分析法等一些研究方法,去构建研究高校潜水可持续发展的体系,并确立其因素的权重。结果表明从SWOT分析方面去构建一级四个指标优势S、劣势W、机会O、威胁T,二级指标18个因素的体系是能够分析出哪个因素的权重更大,能给予一定的定量分析支持。其中一级指标的优势S是四个指标中最重要的一个因素,能给予决断层学术上的帮助。  相似文献   

Abandoning Either/Ors in Analyzing Shifts in Humanitarian Reporting     

David Nolan  Stephanie Brookes  Michelle Imison 《Journalism Practice》2020,14(1):17-33

ABSTRACT

The shifting constitution of journalists as humanitarian actors has profound implications for changing forms of journalism practice, as well as for the normative models through which journalists understand and reflect on that practice. In an effort to develop a more empirically-grounded engagement with change, this article explores the interview testimonies of Australian journalists who cover international and humanitarian issues. It argues that frameworks reliant on stark oppositions (between past and present, optimism and pessimism, or moral agency and material structure) are both empirically and practically problematic, and seeks to move beyond these. Engagement with data from semi-structured interviews offers insight into how journalists’ perceptions of and responses to change are shaped by the historical and shifting institutional relations in which they are implicated.  相似文献   

面向区域创新与产业发展的信息服务实践研究——以中国科学院文献情报中心区域信息服务为例     

贾苹  闫亚飞  郭文姣  刘细文  张超  彭皓  杨雨寒  赵婉雨 《图书情报工作》2021,64(24):24-31

[目的/意义] 随着自主创新战略的提出，科技信息和科技情报在国家科技发展中的基础性作用日益受到重视，开展区域创新和经济发展的信息服务研究与实践，构建面向区域创新和经济发展的信息服务方法体系、实施方案，是十分必要的。[方法/过程] 通过对国内外文献情报机构服务区域创新和经济发展的实践调研，以及中国科学院文献情报中心在"十二五"和"十三五"期间面向省级科学院、中国科学院转化中心、地方政府、园区企业开展区域信息服务的整体设计和服务实践与案例分析，总结归纳中国科学院文献情报中心开展区域创新和经济发展知识服务的特色和成效。[结果/结论] 在实践的基础上提出图书馆面向区域创新和产业发展提供信息服务，进一步拓展了图书馆的服务领域，是图书馆发展的一个生长点，并将在服务内容与服务方式上不断发展完善。  相似文献   

从传递信息到营造体验:体育传播产品转型初探——基于传播游戏理论的考察     

付晓静  潘陈青  罗幽诗 《武汉体育学院学报》2020,54(2):11-17

传播游戏理论强调传播作为一种主观性游戏的存在，体育传播与此具有天然的契合点。该文在界定体育传播产品内涵、分析传播游戏理论观点的基础上，提出体育传播产品要从传递信息走向营造体验，要开发体育视频资源，利用VR技术增强赛事体验，借助机器人提升体育信息传播速度，采用数据可视化增强体育传播的趣味性与观赏性。  相似文献