Fuzzy c-means text clustering based on topic concept sub-space

To improve the accuracy of text clustering, fuzzy c-means clustering based on topic concept sub-space （TCS2FCM） is introduced for classifying texts. Five evaluation functions are combined to extract key phrases. Concept phrases, as well as the descriptions of final clusters, are presented using WordNet origin from key phrases. Initial centers and membership matrix are the most important factors affecting clustering performance. Orthogonal concept topic sub-spaces are built with the topic concept phrases representing topics of the texts and the initialization of centers and the membership matrix depend on the concept vectors in sub-spaces. The results show that, different from random initialization of traditional fuzzy c-means clustering, the initialization related to text content contributions can improve clustering precision.

Optimization of MQAM Modulation Schemes in Mobile Communications(Ⅰ)——Analysis of MQAM BER Performance in AGWN Channel Based on Signal Space

Based on signal space concepts, a transmission error code performance for MPSK, square MQAM and star MQAM modulation schemes on the AGWN channel is analyzed. The corresponding BER formulas and computer aided numeric results are also given. Therefore it provides a theoretical basis for choosing MQAM modulation schemes in mobile communications.

Resource discovery in distributed digital libraries through visual knowledge navigation

In order to support users to search and browse for various resources, digital libraries are composed of discovery systems which provide user interface and information retrieve system. Recent researches in Information Retrieval have investi- gated different techniques through improving precision and recall to enhance the effectiveness of discovery system in digital libraries. In this paper, we present our work to enhance discovery system effectiveness with a different approach, through resource discovery based on visual knowledge navigation. In our Strand Map Services project under National Science Digital Library, we introduce the visual resource discovery system called conceptual browsing interfaces, to help educators and learners to locate, comprehend and use educational resources in digital libraries. The paper begins with a short introduction of the Strand Map Services. Then we illustrate the service architecture, the design and implementation of its major components. We will focus our discussion of how the visualization system of the Strand Map Services supports the visual knowledge navigation for distributed digital libraries. This includes the knowledge acquisition of the conceptual browsing interfaces, different knowledge representa- tions in the system perspective and user interface perspective, visualization system modules, algorithm and Web services inte- gration to use visual knowledge navigation to enhance resource discovery in digital libraries.

Concept of the solar ring mission:An overview

The concept of the Solar Ring mission was gradually formed from L5/L4 mission concept, and the proposal of its pre-phase study was funded by the National Natural Science Foundation of China in November 2018 and then by the Strategic Priority Program of Chinese Academy of Sciences in space sciences in May 2019. Solar Ring mission will be the first attempt to routinely monitor and study the Sun and inner heliosphere from a full 360-degree perspective in the ecliptic plane. The current preliminary design of the Solar Ring mission is to deploy six spacecraft, grouped in three pairs, on a sub-AU orbit around the Sun. The two spacecraft in each group are separated by about 30?and every two groups by about 120?. This configuration with necessary science payloads will allow us to establish three unprecedented capabilities:(1) determine the photospheric vector magnetic field with unambiguity,(2) provide 360-degree maps of the Sun and the inner heliosphere routinely, and(3) resolve the solar wind structures at multiple scales and multiple longitudes. With these capabilities, the Solar Ring mission aims to address the origin of solar cycle, the origin of solar eruptions, the origin of solar wind structures and the origin of severe space weather events. The successful accomplishment of the mission will advance our understanding of the star and the space environment that hold our life and enhance our capability of expanding the next new territory of human.