Understanding the YouTube Partners and Their Data： Measurement and Analysis

User generated content,e.g.,from YouTube,the most popular online video sharing site,is one of the major sources of today's big data and it is crucial to understand their inherent characteristics.Recently,YouTube has started working with content providers(known as YouTube partners) to promote the users' watching and sharing activities.The substantial benefit is to further augment its service and monetize more videos,which is crucial to both YouTube and its partners,as well as to other providers of relevant services.In this paper,our main contribution is to analyze the massive amounts of video data from a YouTube partner's view.We make effective use of Insight,a new analytics service of YouTube that offers simple data analysis for partners.To provide the practical guidance from the raw Insight data,we enable more complex investigations for the inherent features that affect the popularity of the videos.Our findings facilitate YouTube partners to re-design current video publishing strategies,having more opportunities to attract more views.

IMPROVING THE FREQUENCY RESOLUTION OF DIGITALLY SYNTHESIZED PERIODIC SIGNALS BY A SEQUENTIAL ADDRESSING SCHEME

In the digital synthesis of wideband periodic signals using an Arbitrary Waveform Gen-erator(AWG),the frequency resolution and spectral complexity of the synthesized signals are com-monly limited by the memory capacity and clock frequency of the AWG.This paper proposes a novel sequential addressing scheme and then presents several sequences to improve the frequency resolution of the synthesized periodic signals without changing their spectral envelopes and basic time-domain characteristics under the condition of a fixed memory capacity and a fixed clock fre-quency.The main idea of the scheme is using the address generator in an AWG to program and produce addresses to read fixed waveform data in variable order,and thus to generate waveforms of various periods and profiles.The scheme is applied in simulating signal scenarios for military com-munication countermeasure experiments,and achieves high performance.

中国英语学习者口语准确性测量和口语成绩的相关性分析

本研究从频数测量和比率测量两方面探讨准确性指标与口语成绩之间的关系。本研究采用诱导任务方法,收集了61篇中国英语专业学生口语语篇。通过对准确性指标数据分析,本研究获得三个主要发现。对口语教学以及引导学生注意形式与意义的连接,提高语言使用的准确性有一定的启示。

Influence of Temperature and Frequency on Microwave Dielectric Properties of Lunar Regolith Simulant

The dielectric constant of the lunar regolith can directly influence the reflection coefficient and the trans-mission coefficient of the Moon′s surface, and plays an important role in the Moon research. In order to study the di-electric properties of the lunar regolith, the lunar regolith simulant was made according to the making procedure of the CAS-1 simulant made by Chinese Academy of Sciences. Then the dielectric constants of the lunar regolith simulant were measured with 85070E Aiglent Microwave Network Analyzer in the frequency ranging from 0.2 GHz to 20.0 GHz and at temperature of 25.1℃, 17.7℃, 13.1℃, 11.5℃, 9.6℃, 8.0℃, 4.1℃, -0.3℃, -4.7℃, -9.5℃, -18.7℃, -27.7℃, and -32.6℃, respectively. The Odelevsky model was employed to remove the influence of water in the air on the final effective dielectric constants. The results indicate that frequency and temperature have apparent influences on the dielectric constants of the lunar regolith simulant. The real parts of the dielectric constants increase fast over the range of 0.2 GHz to 3.0 GHz, but decrease slowly over the range of 4.0 GHz to 20.0 GHz. The opposite phenomenon occurs in the imaginary parts. The influences of the frequency and temperature on the brightness temperature were also estimated based on the radiative transfer equation. The result shows that the variation of the frequency and temperature results in great changes of the microwave brightness temperature emitting from the lunar regolith.

Processing Seismic Ambient Noise Data to Obtain Reliable Surface Wave Dispersion Measurements

Ambient noise tomography is a rapidly emerging field of seismological research. This paper presents the current status of ambient noise data processing and its development history over the past several years, with the intention to explain and justify this development through salient examples. The ambient noise data processing procedure can be divided into four principal phases： ① single station data preparation; ② cross- correlation and temporal stacking; ③ measurements of dispersion curves （ performed with frequency-time analysis for both group and phase speeds） ; ④ quality control, including SNR analysis and selection of the acceptable measurements. In addition, we provide a specific solution for a better use of the seismic station data to ambient noise study.

Estimation of the electromechanical characteristics of power systems based on a revised stochastic subspace method and the stabilization diagram

Estimating low-frequency oscillation modes and the corresponding mode shapes based on ambient data from WAMS measurements has a promising prospect in power system analysis and control.Based on the stochastic subspace method,this paper proposes a revised stochastic subspace method by introducing reference channels,which can estimate the modes and the mode shapes simultaneously with great computational efficiency.Meanwhile,the accuracy of the estimated results is not degraded.To discriminate the real modes from the spurious ones,the stabilization diagram is introduced.A novel algorithm is designed to deal with the stabilization diagram which can detect the real modes automatically.Tests conducted on the IEEE-118 system indicate that the proposed method has good performance in terms of both computational efficiency and accuracy,and has the potential of being used on-line.