期刊文献+
共找到5篇文章
< 1 >
每页显示 20 50 100
技术预见德尔菲调查中共性技术课题识别研究 被引量:33
1
作者 袁思达 《科学学与科学技术管理》 CSSCI 北大核心 2009年第10期21-26,共6页
共性技术对一国产业技术能力提升有巨大推动作用,其特性决定了政府应成为其供给与扩散的主要推动者。但是,当前世界各国对于产业共性技术的识别尚缺乏有效方法。在各国技术预见实践中,尚未有人根据德尔菲调查结果对共性技术课题识别进... 共性技术对一国产业技术能力提升有巨大推动作用,其特性决定了政府应成为其供给与扩散的主要推动者。但是,当前世界各国对于产业共性技术的识别尚缺乏有效方法。在各国技术预见实践中,尚未有人根据德尔菲调查结果对共性技术课题识别进行研究。以"中国未来20年技术预见研究"能源技术领域为例,通过分析备选技术课题之间的相关度,得到若干项共性技术课题,以期为国家关键技术选择、优先发展技术领域的确定提供一些参考。 展开更多
关键词 未来学 技术课题相关度 技术预见 共性技术课题
下载PDF
基于模拟退火算法的可逆数据库水印 被引量:1
2
作者 姜传贤 李志平 张廷茂 《电脑知识与技术》 2017年第6期141-143,共3页
针对当前数据库存储信息的安全问题,提出一种基于模拟退火算法可逆数据库水印并对其进行实现,相关度技术的使用确定待嵌属性列,进一步利用模拟退火算法优化技术确定待嵌属性列数据的修改量,提高水印的不可见性;通过1位水印嵌入到数据块... 针对当前数据库存储信息的安全问题,提出一种基于模拟退火算法可逆数据库水印并对其进行实现,相关度技术的使用确定待嵌属性列,进一步利用模拟退火算法优化技术确定待嵌属性列数据的修改量,提高水印的不可见性;通过1位水印嵌入到数据块中,达到提高水印鲁棒性目的。测试结果表明,该系统能较好地实现数据库数据的版权和完整性保护。 展开更多
关键词 可逆数据库水印 模拟退火算法 相关度技术
下载PDF
战略性新兴产业共性技术测度指标研究 被引量:29
3
作者 栾春娟 《科学学与科学技术管理》 CSSCI 北大核心 2012年第2期11-16,共6页
探索战略性新兴产业共性技术测度指标,可以厘清战略性新兴产业发展过程中的共性技术选择和管理的作用。依据对产业共性技术的界定,初步确认技术共现率指标、技术相关度指标、多重测量中心度指标及度中心度和中介中心度指标等,可以作为... 探索战略性新兴产业共性技术测度指标,可以厘清战略性新兴产业发展过程中的共性技术选择和管理的作用。依据对产业共性技术的界定,初步确认技术共现率指标、技术相关度指标、多重测量中心度指标及度中心度和中介中心度指标等,可以作为战略性新兴产业共性技术的测度指标。 展开更多
关键词 共性技术测度指标 战略性新兴产业 技术共现率 技术相关度 多重测量中心度 度中心度 中介中心度
原文传递
Satellite-based Estimation of Gross Primary Production in an Alpine Swamp Meadow on the Tibetan Plateau:A Multi-model Comparison 被引量:4
4
作者 NIU Ben ZHANG Xianzhou +7 位作者 HE Yongtao SHI Peili FU Gang DU Mingyuan ZHANG Yangjian ZONG Ning ZHANG Jing WU Jianshuang 《Journal of Resources and Ecology》 CSCD 2017年第1期57-66,共10页
Alpine swamp meadows on the Tibetan Plateau,with the highest soil organic carbon content across the globe,are extremely vulnerable to climate change.To accurately and continually quantify the gross primary production... Alpine swamp meadows on the Tibetan Plateau,with the highest soil organic carbon content across the globe,are extremely vulnerable to climate change.To accurately and continually quantify the gross primary production(GPP) is critical for understanding the dynamics of carbon cycles from site-scale to global scale.Eddy covariance technique(EC) provides the best approach to measure the site-specific carbon flux,while satellite-based models can estimate GPP from local,small scale sites to regional and global scales.However,the suitability of most satellite-based models for alpine swamp meadow is unknown.Here we tested the performance of four widely-used models,the MOD17 algorithm(MOD),the vegetation photosynthesis model(VPM),the photosynthetic capacity model(PCM),and the alpine vegetation model(AVM),in providing GPP estimations for a typical alpine swamp meadow as compared to the GPP estimations provided by EC-derived GPP.Our results indicated that all these models provided good descriptions of the intra-annual GPP patterns(R〉20.89,P〈0.0001),but hardly agreed with the inter-annual GPP trends.VPM strongly underestimated the GPP of alpine swamp meadow,only accounting for 54.0% of GPP_EC.However,the other three satellite-based GPP models could serve as alternative tools for tower-based GPP observation.GPP estimated from AVM captured 94.5% of daily GPP_EC with the lowest average RMSE of 1.47 g C m^(-2).PCM slightly overestimated GPP by 12.0% while MODR slightly underestimated by 8.1% GPP compared to the daily GPP_EC.Our results suggested that GPP estimations for this alpine swamp meadow using AVM were superior to GPP estimations using the other relatively complex models. 展开更多
关键词 satellite remote sensing eddy covariance technique(EC) gross primary production(GPP) model performance alpine swamp meadow Tibetan Plateau
原文传递
HF SAR image cross-correlation technique for high accuracy orbit positioning
5
作者 KOBAYASHI Takao LEE SeungRyeol +1 位作者 KIM JungHo ONO Takayuki 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2011年第5期978-985,共8页
A novel technique to determine the position of spacecraft orbits is proposed. The technique is based on the cross-correlation function of HF SAR images and is able to determine the relative position of orbits with an ... A novel technique to determine the position of spacecraft orbits is proposed. The technique is based on the cross-correlation function of HF SAR images and is able to determine the relative position of orbits with an accuracy of - λ/4 or better, where 2 is the wavelength of the HF radar pulse at its center frequency. The performance of the proposed technique was confirmed by simulation which was carried out under the condition of design facts of the SELENE LRS mission. The highly accurate orbit positioning enables precise superposition of HF SAR images so that the inherent mirror image ambiguity problem of HF SAR imaging is resolved to obtain a quality SAR image of the HF band. In addition ambitious 2D-SAR processing would be possible when the above accuracy is available. 展开更多
关键词 high accuracy orbit determination SAR LRS SELENE
原文传递
上一页 1 下一页 到第
使用帮助 返回顶部