认知型宽带恒模阵列水声通信多用户信号分离与干扰抑制算法

提出了一种适用于水声通信系统节点多用户信号获取与干扰抑制的宽带空时恒模阵列算法,实现多用户信号提取和宽带干扰的抑制。该算法与常规恒模阵列相比,具有更强的多径与干扰抑制能力。作为认知水声通信技术的重要组成部分,采用时频分析与瞬时自相关等调制特征提取算法,对宽带恒模阵列获取的多用户及干扰有效分类,从而为不同调制用户解调及干扰抑制提供解决方案。计算机仿真验证了该认知处理算法结构的良好性能。     

Extending interactive data language with higher-order functions

The interactive data language (IDL) is a dynamically typed array processing language widely used for the analysis of images and other scientific data. It operates in two basic modes. The first is a command line mode for interactive analysis and visualization of scientific data. The second is as a development platform for end-user applications which process scientific data. This paper details the introduction of higher-order functions to the core IDL. The purpose of these constructs is to increase the productivity of the interactive IDL user. Historically, interactive users of IDL have been scientists and engineers engaged in the exploration of new data. The addition of functional constructs aids these users by allowing them to accomplish, in a few lines of code, what might otherwise require writing a custom function which is then compiled and used. The constructs described were implemented as C language extensions to core IDL. The IDL extensions themselves are available for download at .     

An investigation of the impact of cognitive absorption on continued usage of social media in Taiwan: the perspectives of fit

Information processing view explains the fit between information processing need and information processing capability to achieve optimal performance. This research observes that the model of users’ needs-functional capabilities fits by two perspectives of holistic and reductionistic in the context of social media usage. Through an online survey of 310 Facebook users in Taiwan, the findings provide the holistic and reductionistic perspectives of the fit between users’ needs and functional capabilities as having a significant impact on users’ cognitive absorption. Thus, social media providers must emphasise managing the fit between users’ needs and functional capabilities for their products and services development.     

水下成像的稀疏阵列乘性处理

针对阵列传感器布阵设计中的冗余问题,提供了一种水下声学成像稀疏阵列的处理方法。采用稀疏阵列乘性处理方法可合成一个收发一体的虚拟阵列且虚拟阵元数目等于实际阵列发射阵元与接收阵元的乘积。依据相位中心近似的原理,对虚拟阵元的布阵位置进行了数学的解析表示,使用几种不同结构的稀疏阵列进行比较。实验结果得出,使用上述方法建立的稀疏阵列性能指标在三维声场、波束、导向矢量、主瓣宽度和峰值旁瓣级等方面与同等数量的收发一体Mills cross稀疏阵列一致。表明了乘性处理方法能有效解决阵元冗余问题,利用上述方法可得到一种优于Mills cross的新型稀疏阵列。     

A survey of blind users on the usability of email applications

Blind users face many challenges and obstacles when using computers at home and in the workplace, including difficulties in accessing web sites and using corporate software. A detailed understanding of usability problems in common email applications can inform designs that will provide improved usability. To help understand the challenges faced, a web-based survey on email usage by blind screen reader users was conducted. This paper presents the results of the survey of 129 blind users, which reveal several important facets of email applications that can be improved for blind users. The paper also discusses the specific challenges that are faced by blind users when using desktop and web-based email software.     

维、哈、柯全文搜索引擎检索器的关键技术

研究维、哈、柯全文搜索引擎检索器的关键问题,提出有效的解决方法,包括在用户计算机没有安装本地输入法和字库的情况下输入维、哈、柯文检索词并正常显示搜索结果,针对具有高拼写错误率的维、哈、柯文检索词进行检错、纠错处理,返回给用户正确而全面的搜索结果等。实验结果表明,该方法为用户提供方便的同时明显提高了维、哈、柯文搜索引擎的查全率和查准率。     

A privacy-preserving aggregation scheme based on immunological negative surveys for smart meters

The smart meter is a basic device of the smart grid, which improves the efficiency of the power grid and brings a lot of convenience for the industry and people’s daily life. However, real-time power consumption data contain some sensitive information, and could disclose the privacy of users. As an immunological technique, the negative survey is proposed to preserve the privacy of static data. In this paper, firstly, we demonstrate that traditional negative survey might disclose the privacy of users when it is used to collect time-series data. Secondly, we propose an improved negative survey method for collecting the time-series data. Thirdly, for the first time, we apply the negative survey to preserving the privacy of the power consumption data aggregated from smart meters. Theoretical analysis and experimental results demonstrate that the method proposed in this paper could aggregate the power consumption data while preserving the privacy of users. Compared with existing techniques, our method is simple and efficient, and does not need a trusted third party. Moreover, it could tolerate the failure of some users and resist differential attack.     

Personalised Information Retrieval: survey and classification

Information Retrieval (IR) systems assist users in finding information from the myriad of information resources available on the Web. A traditional characteristic of IR systems is that if different users submit the same query, the system would yield the same list of results, regardless of the user. Personalised Information Retrieval (PIR) systems take a step further to better satisfy the user’s specific information needs by providing search results that are not only of relevance to the query but are also of particular relevance to the user who submitted the query. PIR has thereby attracted increasing research and commercial attention as information portals aim at achieving user loyalty by improving their performance in terms of effectiveness and user satisfaction. In order to provide a personalised service, a PIR system maintains information about the users and the history of their interactions with the system. This information is then used to adapt the users’ queries or the results so that information that is more relevant to the users is retrieved and presented. This survey paper features a critical review of PIR systems, with a focus on personalised search. The survey provides an insight into the stages involved in building and evaluating PIR systems, namely: information gathering, information representation, personalisation execution, and system evaluation. Moreover, the survey provides an analysis of PIR systems with respect to the scope of personalisation addressed. The survey proposes a classification of PIR systems into three scopes: individualised systems, community-based systems, and aggregate-level systems. Based on the conducted survey, the paper concludes by highlighting challenges and future research directions in the field of PIR.     

区块链的数据管理技术综述

最近几年,随着加密货币和去中心化应用的流行,区块链技术受到了各行业极大的关注.从数据管理的角度,区块链可以视作是在一个分布式环境下众多不可信节点共同维护且不可篡改的账本.由于节点间相互不可信,区块链通过共识协议,确保数据存储的一致性,实现去中心化的数据管理.针对区块链的安全性以及共识协议,已有诸多工作进行全面的分析.将从数据管理的角度,分析区块链技术与传统数据库下数据管理技术的异同.分布式数据管理的研究已经持续数十年,涵盖了数据存储模式、事务处理机制、查询执行与验证、系统可扩展性等诸多方面,并已有诸多技术广泛应用于实际的分布式数据库中.该类工作往往假定存在中心可信节点或者节点只可能发生崩溃而不存在恶意攻击.然而在区块链环境中,系统设计需考虑不可信节点可能的攻击行为以及拜占庭容错.这给数据管理带来了新的问题与挑战.因此,将梳理并分析国内外有关区块链数据管理的文献,并展望未来的研究方向.     

Ergonomics of electronic mail address systems: related literature review and survey of users

The paper reviews the cognitive ergonomics literature related to electronic mail (e-mail) address design. Based on this information, a survey of 160 users of current e-mail address system was conducted. The aim was to obtain information on likes, dislikes and difficulties associated with e-mail address and to obtain users' suggestions and input for improving the current e-mail address system. The survey results indicated that users want an improved e-mail address system with regard to shorter length, useful information and appropriate presentation of information.     

Challenges of computing in mobile cellular environment—a survey

Advances in cellular mobile technology have engendered a new paradigm of computing, called mobile computing. The frequency spectrum allocated to this service is not sufficient with respect to enormous growth of mobile communication users. Tracking down a mobile user in a cellular network which is a collection of geometric areas called cells each serviced by a base station is the other concern to the designer. This service also needs another problem to be solved, that is the access of common information by mobile users. Other than the issues in existing technology, many other issues on developing technology need to be addressed.

The survey is done in two phases. In the first phase a survey of three fundamental problems in mobile computing on existing technology is done. The issues discussed arise from three essential requirements: the efficient management and sharing of the spectrum among the users; to locate a mobile user in the cellular mobile environments; and processing of queries on location dependent data. The second phase highlights on research on different issues such as security, routing etc. in third generation wireless network in developing technology.     

六角形阵快速傅立叶变换波束形成算法

在六角形阵阵元数较多时,传统的频域相移求和波束形成方法要求的运算量很大.为此提出一种采用六角形快速傅立叶变换HFFT(Hexagonal Fast Fourier Transform)的波束形成算法.使用六角形傅立叶变换HDFT(Hexagonal Discrete Fourier Transform)完成六角形阵的波束形成,由于HDFT存在快速算法HFFT,因此能够显著降低波束形成的运算量.首先在各个通道上做FFT,将信号变换到频域,然后转角重排,再对各个阵元上相同的频点做HFFT,得到频域常规波束形成输出.理论分析表明,对于窄带信号的六角形阵波束形成,所提出的算法所需的计算量比传统的相移求和方法降低了95%以上.仿真和试验结果表明,提出的算法在不影响阵列处理性能的同时,显著降低了波束形成所需的计算量,易于工程实现.     

Ergonomics of electronic mail address systems: related literature review and survey of users

The paper reviews the cognitive ergonomics literature related to electronic mail (e-mail) address design. Based on this information, a survey of 160 users of current e-mail address system was conducted. The aim was to obtain information on likes, dislikes and difficulties associated with e-mail address and to obtain users' suggestions and input for improving the current e-mail address system. The survey results indicated that users want an improved e-mail address system with regard to shorter length, useful information and appropriate presentation of information.     

正交阵并行图象处理的研究和实现

文中提出了具有良好性能的正交阵并行图象处理机系统的硬件构造，并详细分析了快速Ｆｏｕｒｉｅｒ变换，图象矩运算，直方图统计等图像处理中常用算法在并行机上的执行情况，时间复杂度和相对单机而言的加速比。     

Exploring contributions of public resources in social bookmarking systems

Our study examines whether users’ contributions of public resources to social bookmarking sites are circumstantial (a side effect of bookmarking for oneself), or motivational (intentional bookmarking for others). We develop a research model based on these two explanations and test it using survey data from users of two bookmarking sites. Our results suggest that public contributions are mainly driven by intentional bookmarking of resources for other users. In addition, we found that users deliberately bookmark resources for others when they believe that their bookmarks are valuable to other users and when they perceive that other users are contributing as well.     

Impact of CAD tools on creative problem solving in engineering design

This paper presents the results of a survey of CAD users that examined the ways in which their computational environment may influence their ability to design creatively. This extensive online survey builds upon the findings of an earlier observational case study of the use of computer tools by a small engineering team. The case study was conducted during the conceptual and detailed stages of the design of a first-to-world product. Four mechanisms by which CAD tools may influence the creative problem solving process were investigated: enhanced visualisation and communication, circumscribed thinking, premature design fixation and bounded ideation. The prevalence of these mechanisms was examined via a series of questions that probed the user’s mode of working, attitudes, and responses to hypothetical situations. The survey showed good support for the first three mechanisms and moderate support for the fourth. The results have important implications for both the users and designers of CAD tools.     

空间非平稳噪声环境下非均匀线阵的DOA估计

针对在空间非平稳噪声环境下传统的MUSIC算法会失效的问题，提出了一种新的波达方向（DOA）估计方法。该方法利用转换矩阵法，通过对阵列数据相关矩阵进行预处理，从而克服噪声对方位估计的影响，并且该算法适用于非均匀线阵，而非均匀线阵在阵元数目一定的情况下，通过合理设置阵元间距。其方位分辨率较之均匀线阵有较大的提高。计算机仿真结果表明，在非平稳噪声环境下利用该算法非均匀线阵的分辨能力要明显高于均匀线阵。     

Evaluation of detection and discrimination ability of peripheral vision on notification information based on large displays

Large displays enable users to perform several tasks simultaneously. Under such circumstances, notification information provided through the concept of ambient displays plays a vital role in assisting users to switch among tasks. This paper presents the experimental results of a notification system design in the peripheral region of large displays. The aim is to provide guidance for notification information design by investigating detection and discrimination performance of human observers when visual notification information is presented away from the foveal region and viewed using peripheral vision. The proposed notification system was designed using an array of glyphs. Each glyph is a small gray square with a fixed size of 60 × 60 pixels. By changing the gray levels of adjacent glyphs dynamically, a glyph array presents a particular dynamic pattern. The experiments involved testing factors that comprised the visual angle, size and shape of glyph arrays, frequency of temporal modulation, phase shift of each pattern, and number of stimuli. The results show that glyph arrays are detected accurately if they are larger, even at wide viewing angles, and that the number of glyphs in a glyph array affects the performance more than the shapes of glyph arrays do. Furthermore, the discrimination performance is higher when both the frequency and phase are manipulated simultaneously (multidimensional design), compared with the case when each of these dimensions is varied separately (single-dimensional design). When the number of stimuli is set at 8, for example, users can maintain an accuracy rate of 70% for the multidimensional design, whereas the accuracy rate is only approximately 60% for the single-dimensional design.     

A novel initial ranging algorithm for OFDMA systems using smart antenna

To improve the capacity of initial ranging （IR） users simultaneously accessing into network and enhance the performance of the IR, a novel IR algorithm is presented for the orthogonal frequency division multiple access systems with the smart antenna. The beamforming weight vectors provided by the antenna array are introduced for the IR users, and the procedures of the multiuser parameter estimation and the interference cancellation are designed. The proposed method can improve the accuracy of the channel estimation of active paths and efficiently reduce the residual multiple access interference. Simulation results show that the proposed method has a much better performance than the available successive multiuser detection and interference cancellation algorithm and accommodates more active ranging users simultaneously accessing into a cell.