Ion flux dropout observed near dipolarization front

An ion flux dropout near the dipolarization front （DF） at around XGSM =- 11 RE in the Earth＇ s plasma sheet was observed by Time History of Events and Macroscale Interaction during substorms （THEMIS） on March 31, 2009. The ion differential energy fluxes at energies from 450 eV to 150 keV measured by the ESA and SST instruments from THC began to decrease about 2 s before the detection of the DF and reached a local minimum 6 s later. Then, the ion fluxes gradually increased to form a dropout around the DF. The spatial extent of the dropout was about 4,000 km. For energies above 20 keV, the ion fluxes after the dropout are greater than those before it, contrary to the fluxes at energies below 20 keV. The associated ion density variation indicates that the ion flux dropout coincides with the ion density dropout. Taking advantage of multipoint observations, THD, THC, and THE detected the same DF consecutively. Only THC detected an obvious ion flux dropout; THD observed an indistinct one about 2 s before THC; no high-energy （E 〉 30 keV） ion flux dropout was observed by THE. Our study suggests that the ion flux dropout may evolve with the earthward-propagating DF, and its properties can depend on locations relative to the DF.     

Some open problems related to creative telescoping

Creative telescoping is the method of choice for obtaining information about definite sums or integrals. It has been intensively studied since the early 1990s, and can now be considered as a classical technique in computer algebra. At the same time, it is still a subject of ongoing research. This paper presents a selection of open problems in this context. The authors would be curious to hear about any substantial progress on any of these problems.     

The distributed representation for societal risk classification toward BBS posts

The risk classification of BBS posts is important to the evaluation of societal risk level within a period. Using the posts collected from Tianya forum as the data source, the authors adopted the societal risk indicators from socio psychology, and conduct document-level multiple societal risk classification of BBS posts. To effectively capture the semantics and word order of documents, a shallow neural network as Paragraph Vector is applied to realize the distributed vector representations of the posts in the vector space. Based on the document vectors, the authors apply one classification method KNN to identify the societal risk category of the posts. The experimental results reveal that paragraph vector in document-level societal risk classification achieves much faster training speed and at least 10% improvements of F-measures than Bag-of-Words. Furthermore, the performance of paragraph vector is also superior to edit distance and Lucene-based search method. The present work is the first attempt of combining document embedding method with socio psychology research results to public opinions area.     

TRIZ理论在风电产品设计中的应用

介绍了TRIZ理论的产生及其理论体系,重点介绍了其在产品设计创新中应用最为广泛的TRIZ矛盾理论,包括矛盾的定义、分类及相关的解决原理,并结合实例说明了TRIZ理论的矛盾理论在风电产品设计中的应用及在企业中推广TRIZ理论的重要意义。     

太原市民营经济开发区地电场观测系统运行评测

详细介绍了太原市民营经济开发区地电场观测系统的运行情况,从数据的完整率和图形曲线变化等方面对仪器观测系统进行了全方位的综合评价,结果表明:该区地电场观测仪器系统运行平稳可靠,能够有效记录民营区范围内地电场的相关变化,为该区地震预测预报提供一定的依据。     

基于Hive的性能优化研究

主要从Map Reduce作业调度和Hive性能调优两个方面对Hive的性能优化进行研究.对于Map Reduce主要从编程模型切入,分析其执行过程,并从map端、reduce端进行参数调优.接着从Hive框架角度入手,分别从分区表和外部表以及常用数据文件的压缩、行式存储与列式存储等方面进行深入研究.实验结果表明,snappy压缩、orcfile/parquet存储格式对于列式查询,提高查询效率,对于大数据分析平台有较好的兼容性.     

New rapid transfer alignment method for SINS of airborne weapon systems

Transfer alignment is an effective alignment method for the strapdown inertial navigation system （SINS） of airborne weapon systems. The traditional transfer alignment methods for large misalignment angles alignment use nonlinear transfer align- ment models and incorporate nonlinear filtering. A rapid transfer alignment method with linear models and linear filtering for ar- bitrary misalignment angles is presented. Through the attitude quaternion decomposition, the purpose of transfer alignment is converted to estimate a constant quaternion. Employing special manipulations on measurement equation, velocity and attitude linear measurement equations are derived. Then the linear trans- fer alignment model for arbitrary misalignment angles is built. An adaptive Kalman filter is developed to handle modeling errors of the measurement noise statistics. Simulation results show feasibili- ty and effectiveness of the proposed method, which provides an alternative rapid transfer alignment method for airborne weapons.