A New 3D Wireless Directional Sensing Model and Coverage Enhancement Algorithm

Coverage control for each sensor is based on a 2D directional sensing model in directional sensor networks conventionally. But the 2D model cannot accurately characterize the real environment. In order to solve this problem,a new 3D directional sensor model and coverage enhancement algorithm is proposed. We can adjust the pitch angle and deviation angle to enhance the coverage rate. And the coverage enhancement algorithm is based on an improved gravitational search algorithm. In this paper the two improved strategies of GSA are directional mutation strategy and individual evolution strategy. A set of simulations show that our coverage enhancement algorithm has a good performance to improve the coverage rate of the wireless directional sensor network on different number of nodes,different virtual angles and different sensing radius.

Cross-Language Transfer Learning-based Lhasa-Tibetan Speech Recognition

As one of Chinese minority languages,Tibetan speech recognition technology was not researched upon as extensively as Chinese and English were until recently.This,along with the relatively small Tibetan corpus,has resulted in an unsatisfying performance of Tibetan speech recognition based on an end-to-end model.This paper aims to achieve an accurate Tibetan speech recognition using a small amount of Tibetan training data.We demonstrate effective methods of Tibetan end-to-end speech recognition via cross-language transfer learning from three aspects:modeling unit selection,transfer learning method,and source language selection.Experimental results show that the Chinese-Tibetan multi-language learning method using multilanguage character set as the modeling unit yields the best performance on Tibetan Character Error Rate(CER)at 27.3%,which is reduced by 26.1%compared to the language-specific model.And our method also achieves the 2.2%higher accuracy using less amount of data compared with the method using Tibetan multi-dialect transfer learning under the same model structure and data set.

什么是暗物质?

虽然暗物质的存在已经得到了大量的天文观测的支持,但暗物质的属性是什么仍然是个未解之谜.近期暗物质探测的实验和理论研究均取得了长足的进展.本文从暗物质问题的提出讲起,介绍了暗物质的基本特点和可能的粒子物理候选者,之后详细介绍了暗物质研究的最新进展.(1)暗物质研究的早期历史.从星系旋转曲线、引力透镜、微波背景辐射等方面介绍了暗物质的观测证据,特别是暗物质丰度起源的标准热退耦理论机制和典型的暗物质粒子候选者,如弱相互作用有质量粒子等.(2)暗物质粒子的实验探测的基本原理和手段,如地下直接探测和空间间接探测等.重点综述了近期实验研究的进展.在地下直接探测方面综述了10 Ge V以下轻质量暗物质的探测实验:Super CDMS(super cryogenic dark matter search),CDEX(China dark matter experiment)等,以及大质量暗物质探测中的液氩探测器Dark Side等.(3)暗物质未来的碰撞方向性探测实验,如DRIFT(directional recoil identification from tracks),MIMAC(MIcro-tpc MAtrix of Chambers)等.在空间间接探测方面介绍暗物质湮灭到宇宙线粒子中涉及到的宇宙线粒子产生和传播的基本理论.(4)已有的实验,如Fermi-LAT(Fermi large area telescope)和AMS(Alpha magnetic spectrometer)-02在高能宇宙线电子和核子方面已经取得的成果,特别是近期DAMPE(dark matter particle explorer)卫星实验的首个结果中看到的正负电子总流强中的新现象和疑似反常现象以及AMS-02的反质子结果对暗物质搜寻的影响.展望了未来在反核子,如反氘和反氦方面可能取得的结果及其对暗物质研究的重要性.

Classification-based self-adaptive differential evolution and its application in multi-lateral multi-issue negotiation

Multi-lateral multi-issue negotiations are the most complex realistic negotiation problems. Automated ap- proaches have proven particularly promising for complex ne- gotiations and previous research indicates evolutionary com- putation could be useful for such complex systems. To im- prove the efficiency of realistic multi-lateral multi-issue ne- gotiations and avoid the requirement of complete informa- tion about negotiators, a novel negotiation model based on art improved evolutionary algorithm p-ADE is proposed. The new model includes a new multi-agent negotiation protocol and strategy which utilize p-ADE to improve the negotia- tion efficiency by generating more acceptable solutions with stronger suitability for all the participants. Where p-ADE is improved based on the well-known differential evolution （DE）, in which a new classification-based mutation strategy DE/rand-to-best/pbest as well as a dynamic self-adaptive pa- rameter setting strategy are proposed. Experimental results confirm the superiority of p-ADE over several state-of-the-art evolutionary optimizers. In addition, the p-ADE based multi- agent negotiation model shows good performance in solving realistic multi-lateral multi-issue negotiations.

Explanations of the DAMPE high energy electron/positron spectrum in the dark matter annihilation and pulsar scenarios

Many studies have shown that either the nearby astrophysical source or dark matter(DM)annihilation/decay can be used to explain the excess of high energy cosmic ray(CR)e~±,which is detected by many experiments,such as PAMELA and AMS-02.Recently,the dark matter particle explorer(DAMPE)collaboration has reported its first result of the total CR e~±spectrum from 25 Ge V to 4.6 Te V with high precision.In this work,we study the DM annihilation and pulsar interpretations of this result.We show that the leptonic DM annihilation channels toτ^+τ^-,4μ,4τ,and mixed charged lepton final states can well explain the DAMPE e~±spectrum.We also find that the mixed charged leptons channel would lead to a sharp drop structure at～Te V.However,the ordinary DM explanations have been almost excluded by the constraints from the observations of gamma-ray and CMB,unless some exotic DM models are introduced.In the pulsar scenario,we analyze 21 nearby known pulsars and assume that one of them dominantly contributes to the high energy CR e~±spectrum.Involving the constraint from the Fermi-LAT observation of the e~±anisotropy,we find that two pulsars could explain the DAMPE e~±spectrum.Our results show that it is difficult to discriminate between the DM annihilation and single pulsar explanations of high energy e~±with the current DAMPE result.