A wave energy resource assessment in the China's seas based on multi-satellite merged radar altimeter data

Wave energy resources are abundant in both offshore and nearshore areas of the China＇s seas. A reliable assessment of the wave energy resources must be performed before they can be exploited. First, for a water depth in offshore waters of China, a parameterized wave power density model that considers the effects of the water depth is introduced to improve the calculating accuracy of the wave power density. Second, wave heights and wind speeds on the surface of the China＇s seas are retrieved from an AVISO multi-satellite altim-eter data set for the period from 2009 to 2013. Three mean wave period inversion models are developed and used to calculate the wave energy period. Third, a practical application value for developing the wave energy is analyzed based on buoy data. Finally, the wave power density is then calculated using the wave field data. Using the distribution of wave power density, the energy level frequency, the time variability indexes, the to-tal wave energy and the distribution of total wave energy density according to a wave state, the offshore wave energy in the China＇s seas is assessed. The results show that the areas of abundant and stable wave energy are primarily located in the north-central part of the South China Sea, the Luzon Strait, southeast of Taiwan in the China＇s seas; the wave power density values in these areas are approximately 14.0–18.5 kW/m. The wave energy in the China’s seas presents obvious seasonal variations and optimal seasons for a wave energy utilization are in winter and autumn. Except for very coastal waters, in other sea areas in the China＇s seas, the energy is primarily from the wave state with 0.5 m≤Hs≤4 m, 4 s≤Te≤10 s whereHs is a significant wave height andTe is an energy period; within this wave state, the wave energy accounts for 80% above of the total wave energy. This characteristic is advantageous to designing wave energy convertors （WECs）. The practical application value of the wave energy is higher which can be as an effective supplement for an energy con-sumption in some areas. The above results are consistent with the wave model which indicates fully that this new microwave remote sensing method altimeter is effective and feasible for the wave energy assessment.

Validation and application of multi-source altimeter wave data in China＇s offshore areas

Studies of offshore wave climate based on satellite altimeter significant wave height（SWH） have widespread application value. This study used a calibrated multi-altimeter SWH dataset to investigate the wave climate characteristics in the offshore areas of China. First, the SWH measurements from 28 buoys located in China＇s coastal seas were compared with an Ifremer calibrated altimeter SWH dataset. Although the altimeter dataset tended to slightly overestimate SWH, it was in good agreement with the in situ data in general. The correlation coefficient was 0.97 and the root-mean-square（RMS） of differences was 0.30 m. The validation results showed a slight difference in different areas. The correlation coefficient was the maximum（0.97） and the RMS difference was the minimum（0.28 m） in the area from the East China Sea to the north of the South China Sea.The correlation coefficient of approximately 0.95 was relatively low in the seas off the Changjiang（Yangtze River） Estuary. The RMS difference was the maximum（0.32 m） in the seas off the Changjiang Estuary and was0.30 m in the Bohai Sea and the Yellow Sea. Based on the above evidence, it is confirmed that the multialtimeter wave data are reliable in China＇s offshore areas. Then, the characteristics of the wave field, including the frequency of huge waves and the multi-year return SWH in China＇s offshore seas were analyzed using the23-year altimeter wave dataset. The 23-year mean SWH generally ranged from 0.6-2.2 m. The greatest SWH appeared in the southeast of the China East Sea, the Taiwan Strait and the northeast of the South China Sea.Obvious seasonal variation of SWH was found in most areas; SWH was greater in winter and autumn than in summer and spring. Extreme waves greater than 4 m in height mainly occurred in the following areas： the southeast of the East China Sea, the south of the Ryukyu Islands, the east of Taiwan-Luzon Island, and the Dongsha Islands extending to the Zhongsha Islands, and the frequency of extreme waves was 3%-6%. Extreme waves occurred most frequently in autumn and rarely in spring. The 100-year return wave height was greatest from the northwest Pacific seas extending to southeast of the Ryukyu Islands（9-12 m）, and the northeast of the South China Sea and the East China Sea had the second largest wave heights（7-11 m）. For inshore areas, the100-year return wave height was the greatest in the waters off the east coast of Guangdong Province and the south coast of Zhejiang Province（7-8 m）, whereas it was at a minimum in the area from the Changjiang Estuary to the Bohai Sea（4-6 m）. An investigation of sampling effects indicates that when using the 1°×1°grid dataset, although the combination of nine altimeters obviously enhanced the time and space coverage of sampling, the accuracy of statistical results, particularly extreme values obtained from the dataset, still suffered from undersampling problems because the time sampling percent in each 1°×1°grid cell was always less than33%.

China's Data Telecom Networks

China has built 22 optical cable trunks, 20 digital microwave trunks and 20 medium-to-large satellite earth stations during the eighth Five-year Plan, thus creating a favorable condition for the development of China’s data telecommunications and value-added business. China’s public data telecommunications, networks have become the main stream for the country’s information transmission through several years of rapid development. China’s public packet switching data network (China Pac), its network capacity increasing to over 60,000 terminals, now covers more than 600 cities, and is interconnected with 44 packet networks of 23 countries and regions. China’s

Data Watch on China's Foreign Trade and Investment in the First Ten Months of 2011

China’s foreign trade in the first ten months of 2011 According to statistics of the Customs, China’s exports and imports in the first ten months of the year reached $2.97538 trillion, up 24.3% over the same period last year, 12 percentage

基于S-XGBoost融合模型的中国进境快件风险水平评价研究

党的二十大报告指出要增强维护国家安全能力,推进国家安全体系和能力现代化,坚决维护国家安全和社会稳定。随着互联网产业的发展壮大,以进境快件为代表的跨境个人消费进入发展的快车道,随之而来的安全准入风险也越来越高。为深入推进智慧海关建设,进一步提升进境快件风险防控能力,文章分析了现行监管模式下进境快件存在的问题,运用XGBoost算法和SMOTE技术构建了S-XGBoost进境快件风险评估模型,并对历史通关数据进行了仿真布控和评估。研究结果表明本文提出的S-XGBoost算法模型具有较好的预测效果,风险预测准确率达到了99.06%,能够为海关工作人员提升进境快件布控有效率提出切实参考建议。

Major Data of China's 1% National Population Sampling Survey,1995

ＭａｊｏｒＤａｔａｏｆＣｈｉｎａ′ｓ１％ＮａｔｉｏｎａｌＰｏｐｕｌａｔｉｏｎＳａｍｐｌｉｎｇＳｕｒｖｅｙ，１９９５Major Data of China's 1% National Population Sampling Survey,199...

DO YOU NEED ANY DATA ON CHINA'S POPULATION?PLEASE CONTACT:DUS

Data User Service(DUS)offers you any data on China's population and rclated socioec onomic data--total population,age-sex composition,population density,labour force and more--to help you do demographic research,make investments in China and so on.

China's Trade Data Shows Positive Signs

China’s foreign trade operation situation According to the statistics collected by Customs,in January-October 2017,China’s total import and export value reached RMB 22.52 trillion,with an increase of 15.9%year on year.In this,exports reached RMB 12.41 trillion,with an increase of 11.7%,and imports reached RMB 10.11 trillion,with an increase of 21.5%.The surplus was RMB 2.29 trillion,down by 17.8%.In terms of commodity structure,

基于MSB二维标记的加密图像可逆数据隐藏

针对基于标记编码的加密图像可逆数据隐藏存在图像冗余未充分利用和信息泄露问题,提出一种基于MSB(Most Significant Bit)二维标记的加密图像可逆数据隐藏(Reversible Data Hiding in Encrypted Image,RDH-EI)算法.为提高算法的嵌入容量,在二维标记图生成阶段,根据原始与预测像素值构造出差异序列,生成MSB二维标记(l1,l2).第一维l1和第二维l2分别记录原始与预测像素值初始连续相同MSBs位数和后继连续相反MSBs(Subsequent Consecutive Opposite MSBs,SCO-MSBs)位数.SCO-MSBs的使用提高像素冗余的利用率,结合范式哈夫曼编码实现嵌入容量的提升.为提高算法的安全性,在伪标记图与加密图像构造阶段,将二维标记图生成的编码流与保存所有辅助信息的额外数据流进行有效信息合并生成原始流后加密,同时在构造加密图像过程中生成用于标识可嵌入位置的伪标记图.原始流加密能有效防止图像信息泄露,伪标记图则用于确定嵌入的预留空间位置.实验结果表明,与现有同类算法相比,本文算法能防止标记图泄露并抵抗唯密文攻击,嵌入容量提高0.208 bpp以上,且算法实现完全可逆的同时,运行时间将近现有算法的1/4.

Synthetic tidal parameters for gravity over China and its neighbor area

The synthetic tidal parameters with high spatial resolution for gravity over China and its neighbor area are constructed with Earth＇s tidal model and ocean tide loading calculated using TPXO7 global ocean tide model as well as tidal data over China seas. The comparison between synthetic parameters and ones observed by spring gravimeters at some seismic network stations and Hong Kong station and one observed by super-conducting gravimeter at Wuhan station shows that the average differences in amplitude factors and phases are smaller than 0.005 and 0.5° respectively; and that the discrepancies between observational and synthetic parameters are dependent on gravimetric technique in that the synthetic parameters are in well agreement with the superconducting gravimetric observations. This also indicates that the synthetic result is a good estimation for tidal gravity, and the numerical results in the present paper not only can provide ground and space gravimetry such as absolute gravimetry with correction model of tidal gravity, but also provide effective tidal parameters over areas where no observation is carried out.

Vigorously Developed China's Satellite Meteorological Cause

This article describes the development of the meteorological satellite,its data applications in China and the problems in the further development of China’s satellite meteorological cause.

China's C802 Shore-to-Ship Mobile Missile System

This article describes China’s C802 shore-to-ship mobile missile system,especially its components,tactical and technical specifications,as well as the configuration and features of C802 missile.Besides,it also briefs the weapon system’s launching and technical site facilities and their functions.

基于TOPSIS理论的因子分析模型在服务业发展中的应用研究

针对已有文献面板数据因子分析模型在实际应用中存在的不足,将每一年综合得分最高和最低的截面数据因子分别作为最优和最劣向量,通过TOPSIS理论求出每个研究对象的最优因子方案接近度.以中国的服务业发展为例,用模型的最优因子方案接近度来描述各个地区服务业发展状况,研究发现多数省份服务业发展与最优因子方案接近度相差较大.

Big Data Analytics in E-commerce for the U.S.and China Through Literature Reviewing

Big data analytics(BDA)in e-commerce,which is an emerging field that started in 2006,deeply affects the development of global e-commerce,especially its layout and performance in the U.S.and China.This paper seeks to examine the relative influence of theoretical research of BDA in e-commerce to explain the differences between the U.S.and China by adopting a statistical analysis method on the basis of samples collected from two main literature databases,Web of Science and CNKI,aimed at the U.S.and China.The results of this study help clarify doubts regarding the development of China's e-commerce,which exceeds that of the U.S.today,in view of the theoretical comparison of BDA in e-commerce between them.

THE DESIGN AND DATA PROCESSING OF THE SAMPLING SURVEY OF CHILDREN'S SITUATION IN CHINA, 1987

In July of 1987, the Sampling Survey of Children's Situation was conducted in 9 provincesautonomous regions of China. A stratified two--stage cluster sampling plan was designed for thesurvey. The paper presents the methods of stratification, selecting n=2 PSU's (cities/counties) withunequal probabilities without replacement in each stratum and selecting residents/village committeein each sampled city/county. All formulae of estimating population characteristics (especiallypopulation totals and the ratios of two totals), and estimating variances of those estimators aregiven. Finally, we analyse the precision of the survey preliminarily from the result of dataprocessing.

How did women’s education and differential family planning policies shape transition to second and third births in historical China? New evidence from micro data

The influence of China’s family planning policies on fertility transition is widely acknowledged in research studies.However,little is known about how improve-ments in women’s education have shaped reproductive decisions of Chinese women across different family planning regimes,particularly at micro level.This study uses retrospective pooled birth history data from five consecutive population and fam-ily planning surveys collected over the period 1982-2006 to systematically examine the interrelationship between family planning policies and women’s education,and their interactive effect on the second and third birth transitions.We hypothesize that family planning policies had a differential influence on educational groups in reduc-ing the transition to second and third births.The results from discrete time com-plementary log-log survival models provide strong evidence of differential repro-ductive behavior of education groups across time in China,and the simultaneous influence of women’s education and family planning policies in lowering risks to higher parities.The rates of progression to second and third births tend to be lower after the introduction of rigid family planning policies,and more importantly,the policy impact persisted even after adjusting for demographic and socioeconomic factors.The increase in women’s education overall had a depressing effect on transi-tion to higher parities,and family planning policies implemented overtime have had differential effects on women from different educational groups.The findings show that both family planning policies and women’s education have been instrumental in shaping fertility behavior in China.