Multiple signal classification (MUSIC) has been widely applied in multiple-input multiple-output (MIMO) receivers for direction-of-arrival (DOA) estimation. To reduce the cost of radio frequency (RF) chains operating at millimeterwave bands, hybrid analog-digital structure has been adopted in massive MIMO transceivers. In this situation, the received signals at the antennas are unavailable to the digital receiver, and as a consequence, the spatial covariance matrix (SCM), which is essential in MUSIC algorithm, cannot be obtained using traditional sample average approach. Based on our previous work, we propose a novel algorithm for SCM reconstruction in hybrid massive MIMO systems with multiple RF chains. By switching the analog beamformers to a group of predetermined DOAs, SCM can be reconstructed through the solutions of a set of linear equations. In addition, based on insightful analysis on that linear equations, a low-complexity algorithm, as well as a careful selection of the predetermined DOAs, will be also presented in this paper. Simulation results show that the proposed algorithms can reconstruct the SCM accurately so that MUSIC algorithm can be well used for DOA estimation in hybrid massive MIMO systems with multiple RF chains.

Purpose – This paper aims to find the current situation of research data services by academic libraries and summarize some strategies for university libraries to reference. Recent years have seen an increasing number of university libraries extended their traditional roles and provided research data services. Design/methodology/approach – This paper selected 87 libraries of the top 100 universities listed in the World’s Best Universities released by the USA News in October 2012 as samples and conducted a Web site investigation to check if there were any research data services provided. In addition, it made an interview with the Wuhan University Library’s Research Data Service Workgroup to understand the procedure, difficulties and experiences of their research data service. Based on the survey and interview, it analyzed the current status and difficulties of research data services in university libraries and proposed some strategies for others to reference. Findings – Of the 87 university libraries investigated, 50 libraries have offered research data services. Most of the services can be divided into six aspects: research data introduction, data management guideline, data curation and storage service, data management training, data management reference and resource recommendation. Among these services, research data introduction is the most frequently provided (47.13 per cent), followed by data curation and storage services (43.68 per cent), data management guideline (42.53 per cent), data management reference (41.38 per cent), resource recommendation (41.38 per cent) and data management training (24.14 per cent). The difficulties met by research data service of Chinese academic libraries are also concluded. Originality/value – Through Web site investigation and interview with the Wuhan University Library’s Research Data Service, this paper presented an overall picture of research data services in university libraries and identified the difficulties and experiences of research data services of the Wuhan University Library. Based on some successful examples, it put forward some strategies for university libraries to reference. This study is very useful for academic libraries to promote their research data services.

Purpose This paper aims at understanding the current situation of research support services offered by academic libraries in world-leading universities and providing useful implications and insights for other academic libraries. Design/methodology/approach Of the top 100 universities listed in the QS World University Rankings in 2017, 76 libraries were selected as samples and a website investigation was conducted to explore the research support services. The statistical method and visualization software was used to generalize the key services, and the text analysis and case analysis were applied to reveal the corresponding implementation. Findings Research support service has become one of the significant services of academic libraries in the context of e-research and data-intensive research. The research support services can be generally divided into seven aspects, as follows: research data management (62, 81.58 per cent), open access (64, 84.21 per cent), scholarly publishing (59, 77.63 per cent), research impact measurement (32, 42.11 per cent), research guides (47, 61.84 per cent), research consultation (59, 77.63 per cent) and research tools recommendation (38, 50.00 per cent). Originality/value This paper makes a comprehensive investigation of research support services in academic libraries of top-ranking universities worldwide. The findings will help academic libraries improve research support services; thus, advancing the work of researchers and promoting scientific discovery.

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PurposeThis paper aims to provide an overall picture of the application of Web 2.0 technologies in Chinese university libraries. The focus of the research is what types of Web 2.0 technologies were applied in such libraries as well as their function and user interface.Design/methodology/approachThe top 30 Chinese university libraries were selected to investigate the application of Web 2.0 technologies. Content analysis was used in terms of quantitative approach. Data were collected by accessing these 30 university libraries web sites within five weeks.FindingsTwo‐thirds of Chinese university libraries deployed one or more Web 2.0 technologies. Only one‐tenth of libraries adopted more than four Web 2.0 technologies. RSS was the most widely applied, while Wiki was the least. The application of Web 2.0 technologies among Chinese university libraries was not extensive and profound enough.Research implicationsThe findings can be utilized to evaluate the status of Web 2.0 technology applications. The statistical data are very useful and authentic sources for improving the level of Web 2.0 technology application. It may enable future research to analyze other aspects (e.g. the application of RSS or Blogs for services).Originality/valueThis unique study explores the application of Web 2.0 mainly in Chinese university libraries that deployed any types of Web 2.0 technologies. This study is very useful for Chinese university libraries in evaluating/deploying Web 2.0. Library managers, librarians, and other libraries may also find this helpful, once they decide to implement such technologies in their libraries.

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Lagrangian of the Einstein's special relativity with universal parameter c (SR c ) is invariant under Poincaré transformation which preserves Lorentz metric η µν . The SR c has been extended to be one which is invariant under de Sitter transformation that preserves so called Beltrami metric B µν . There are two universal parameters c and R in this Special Relativity (denote it as SR cR ).The Lagrangian-Hamiltonian formulism of SR cR is formulated in this paper. The canonic energy, canonic momenta, and 10 Noether charges corresponding to the space-time's de Sitter symmetry are derived. The canonical quantization of the mechanics for SR cR -free particle is performed. The physics related to it is discussed.