Mapping user interest into hyper-spherical space: A novel POI recommendation method

Point-of-interest (POI) recommendation helps users quickly filter out irrelevant POI by considering the spatio-temporal factor. In this paper, we address the problem of check-in preference modeling in POI recommendation, and propose a novel POI recommendation method that depicts user preference by constructing unique hypersphere interest model for each user. Different from existing works, we have done three innovative work. (1) We build a check-in graph and adopt DeepWalk algorithm to learn POI embedding, further aggregating them to obtain a hypersphere interest space with an interest center and interest radius. (2) We established a stacked neural network module by a bidirectional LSTM, a self-attention and a memory network, to grasp memory features contained in check-in histories. (3) We proposed a novel candidate POI filter method that updates ranking score by evaluating the Euclidean distance between the vectors of candidate POI and interest center. We evaluate the performance of our method on the four real-world check-in datasets constructed from Foursquare. The comparison between our method and six baselines demonstrates the outstanding performance on various measurements. Compared to the best baseline method, our method achieves about 50% performance improvement on NDCG. In terms of MRR, Precision and Recall, our method achieves about 37%, 21% and 9% performance improvement over the best baseline method. Further ablation experiments verified the importance and effectiveness of the hypersphere interest model, as removing this component caused significant performance degradation.     

空间时代的天文学研究——从空间天文观测到诺贝尔物理学奖

首届诺贝尔物理学奖授予了揭开了现代物理学序幕的X射线的发现,随后的20多年中与X射线密切相关的诺贝尔物理学奖层出不尽。而一个世纪之后空间天文领域的第一个诺贝尔物理学奖于2002年授予了空间X射线天文的突破,由此打开了人类观测宇宙的新窗口。从1962年发现第一个宇宙X射线源至今半个世纪以来,已经有约70个携带天文仪器的空间飞行器(以专用卫星为主)发射运行,极大地促进了人类对于宇宙和基本物理规律的认识。随后2006年的诺贝尔物理学奖授予了"宇宙背景探索者"(COBE)卫星对宇宙微波背景黑体辐射谱的精确测量和观测到空间分布的各向异性。2011年诺贝尔物理学奖授予了宇宙加速膨胀的发现,著名的哈勃空间望远镜对此做出了关键贡献。这样在新世纪空间天文的研究就直接产生了两个诺贝尔物理学奖,并且对第三个起了重要作用,非常类似20世纪初X射线对于诺贝尔物理学奖的作用。文章通过分析这三个以及天文学研究所获得的所有其他诺贝尔物理学奖,发现除了2006年的诺贝尔物理学奖之外,其他所有的获奖成果都和项目最初的科学目标没有关系或者完全相反。与此同时,探讨了重大天文发现的偶然性和必然性,这对于处于快速发展初期的中国空间天文具有很好的借鉴作用。     

Why space matters in technological innovation systems—Mapping global knowledge dynamics of membrane bioreactor technology

Studies on technological innovation systems (TISs) often set spatial boundaries at the national level and treat supranational levels as a geographically undifferentiated and freely accessible global technological opportunity set. This article criticizes this conceptualization and proposes instead to analyze relevant actors, networks and processes in TIS from a relational perspective on space. It develops an analytical framework which allows investigating innovation processes (or ‘functions’) of a TIS at and across different spatial scales. Based on social network analysis of a co-publication dataset from membrane bioreactor technology, we illustrate how the spatial characteristics of collaborations in knowledge creation vary greatly over relatively short periods of time. This finding suggests that TIS studies should be more reflexive on system boundary setting both regarding the identification and analysis of core processes as well as in the formulation of policy advice.     

天体高能辐射的空间观测与研究

1首席科学家 李惕碚中国科学院院士,高能物理研究所研究员,粒子天体物理重点实验室学术委员会主任,清华大学物理系教授,天体物理中心主任,中国空间科学学会常务理事.1939年6月出生,1963年毕业于清华大学工程物理系.     

5～9月西藏降水异常空间模的时空分布特征

本文采用方差极大正交旋转EOF方法，对西藏26个测站多年5-9月逐月降水场的时空特征进行了分析。结果表明，经过旋转后的空间模及其对应的时间系数能较好地反映西藏5-9月降水的空间分布和时间变化。对前四个异常空间模对应的时间系数进行了持续性及周期变化分析，发现大部分时间系数没有明显的持续性，前四个空间模对应的时间系数分别存在着准3年、4年、8年和16年的显著周期。     

专利视角下云计算领域的知识图谱研究"

专利是科学技术的重要知识载体,在技术创新升级和产业跨越式发展中,发挥着不可或缺的作用。利用可视化工具,对专利数据库中云计算技术专利进行分析,研究合作网络及其聚类的知识扩散机制,在云计算专利权人特征描述的基础上,绘制云计算专利共被引、专利发明人以及专利发明机构的知识图谱,形象地反映出云计算领域技术发展态势及其研发主体间的合作关系。结合研究结论,提出了引导我国深入布局云计算产业发展蓝图的对策建议。     

从改革、适应、创新中寻找发展空间

云南省地球物理学会是一个跨系统的横向的理科学会。从成立之日起就面临着由传统的计划经济向社会主义市场经济转轨的严峻形势 ,加之挂靠单位云南大学地球物理系既不是一经济实体 ,又不是一级真正独立的行政组织 ,根本无经济实力“养活”学会。因而学会一成立 ,学会的领导核心———学会理事会就认识到 ,我们办会的指导思想只能是解放思想 ,转变观念 ,主动自觉地去“改、适、创”。从“改革、适应、创新”中寻找学会的主存发展空间 ,增强学会的凝聚力和向心力。通过 10多年来的改革与工作实践 ,我们深切地认识到 :学会改革必须坚持以邓小平…     

构造新结晶体群的平面对称动力系统

将标准平面结晶体P1迭代公式中的自变量x,y用x3+c1,y3+c2替换,构造可视化平面动力系统.将原有的自变量的线性关系替换为自变量的非线性关系,提出了一种新的自变量的映射方法.并且运用蒙特卡罗搜索法寻找参数,运用李雅普诺夫指数来确定该动力系统的特性,绘制出该动力学系统的混沌吸引子和充满Julia集的图案。     

从企业并购观航天寡头市场竞争态势

冷战后,世界航天市场竞争格局发生了巨大的变化,国外航天公司兼并重组活动风起云涌。本文首先概述航天企业的兼并活动,进而对航天市场的市场结构进行了评价——认为该市场结构属于典型的寡头垄断型结构。在此基础上,论述了企业兼并对航天市场竞争态势所产生的巨大影响。     

Mapping technological trajectories of the Green Revolution and the Gene Revolution from modernization to globalization

The dynamics of technology development along the technological trajectories of the Green Revolution and the Gene Revolution could be explicated by the social morphologies of modernization and globalization. The Green Revolution was shaped by the exigencies of modernization, while the Gene Revolution is being shaped by the imperatives of neo-liberal economic globalization. Innovation, development, and diffusion of technologies followed different trajectories in these two realms because of being part of different innovation systems. Considerations of private gain and profit in the form of high returns to shareholders of agro-biotech corporations of global reach, largely, determine the dynamics of technological innovation in the Gene Revolution. Technology transfer and local adaptive work in the Green Revolution was carried out in the international public domain with the objective of developing research capacity in post-colonial Third World agriculture to increase food production to avert hunger-led political insurrection during the Cold War. Differentiating these two trajectories is important not only due to the normative implications inherent in comparing the impacts of these two “revolutions”, but also due to the important lessons we learn about how different contexts of innovation in the same technology cluster could evolve into contrasting research policy regimes.     

DC向CNMARC元数据格式的逆映射研究

元数据是控制网络信息资源的重要技术手段,随着不同应用领域元数据格式的多样化,人们越来越关注元数据的互操作问题。元数据映射是元数据互操作的一种基本形式。研究了DC向CNMARC元数据格式的逆映射,探讨了这种逆映射的意义,对这一逆映射作了一定分析,最后提出解决方案,即建立一种基于DC的细分的元数据元素集。     

Mapping Markush

Markush structures are molecular skeletons containing not only specific atoms but also placeholders to represent broad sets of chemical (sub)structures. As genus claims, they allow a vast number of compounds to be claimed in a patent application without having to specify every single chemical entity. While Markush structures raise important questions regarding the functioning of the patent system, innovation researchers have been surprisingly silent on the topic. This paper summarizes the ongoing policy debate about Markush structures and provides first empirical insights into how Markush structures are used in patent documents in the pharmaceutical industry and how they affect important outcomes in the patent prosecution process. While not causing frictions in the patent prosecution process, patent documents containing Markush structures have an increased likelihood to restrict the patentability of follow-on inventions and to facilitate the construction of broad patent fences.     

Mapping world-class universities on the web

A visual display of the most important universities in the world is the aim of this paper. It shows the topological characteristics and describes the web relationships among universities of different countries and continents. The first 1000 higher education institutions from the Ranking Web of World Universities were selected and their link relationships were obtained from Yahoo! Search. Network graphs and geographical maps were built from the search engine data. Social network analysis techniques were used to analyse and describe the structural properties of the whole of the network and its nodes. The results show that the world-class university network is constituted from national sub-networks that merge in a central core where the principal universities of each country pull their networks toward international link relationships. The United States dominates the world network, and within Europe the British and the German sub-networks stand out.     

本体映射规则研究

介绍了本体和本体映射的概念,以及本体映射的过程和方法.打破传统的本体映射思路,灵活定义了本体之间的映射关系,将本体映射从宏观和微观两个方面进行分类,总结归纳出了一套本体映射规则,形成一个相对完整的本体映射规则体系,并对每条规则的来源和推理过程都进行了相应说明.     

关于压缩映射原理的某些应用

探讨了压缩映射原理在求数列极限、判断矩阵可逆、求近似值、微分方程存在唯一解问题以及非线性方程求解方面的某些应用,阐明了压缩映射原理在数学各分支应用的灵活性和广泛性.     

The northern light: from mystery to modern space science

As the name implies, the northern light is visible only at high latitudes, and it is therefore not surprising that Scandinavian scientists have been prominent in research on its origin and nature. This article reviews the history of its observation and the development of an understanding of its true origin.     

文档模式(DTD或Schema)到UML模型的映射规则研究

本文对比了信息模型和编程模型的四层体系，提出了从文档模式(DTD或Schema)到UML模型的映射规则．并在基于NewsML的新闻发布软件开发中得到了应用．     

基于知识图谱的2005-2015年我国情报分析研究现状

以中国知网(CNKI)核心期刊数据库为数据来源,检索2005-2015年关于情报分析研究的文献。清洗数据,采用关键词与时间序列的方法,对这一时期的情报分析相关文献分类。同时,采用多种分析工具组合使用对高频关键词做共现分析、聚类分析,构建情报分析研究的知识图谱。分析发现,我国情报分析呈现出研究多领域合作、系统性分析、处理数据化、网络化监测、情报人员培训五大特点。     

子像元定位方法在湖泊水质制图中的应用研究

子像元定位技术是一种提高图像详度和分辨率的简单、高效的方法,近年来已成为遥感领域研究的一个热点.该方法已经在许多方面得到了应用,但目前将子像元定位技术应用于湖泊水质制图在国内外鲜有报道.本文基于Landsat-7 ETM+数据对太湖的叶绿素a(Chl-a)浓度进行试验,结果表明在水质监测中应用子像元定位技术可以获得超过遥感影像自身分辨率的叶绿素a浓度分布图,更好地反映了其空间分布的细节,说明子像元定位技术在提高湖泊水质监测的精度方面具有一定的潜力.     

对象关系映射中类的继承映射分析与实现

针对软件开发人员经常面对如何实现类的继承映射,研究了实现类的继承映射的几种实现方法,重点分析每种方法的优缺点,并给出如何使用的几点建议。解决软件开发过程中存在继承关系的对象持久化问题。