泡沫酸化工艺对川中低压裂缝性油藏适应性的认识

针对川中油田经过多年的消耗式开采,各主产油田压力很低,增产改造的难度增大的发展现状,提出应用泡沫酸化工艺技术在川中低压油层增产改造的技术方案,其中分析了泡沫酸的物理特性、其在地层优良的渗流特性(滤失小、酸岩反应速度慢、返排迅速等优点),并进行了泡沫酸液体系的室内配方研究,提出了工艺设施的矿场配套研究内容.得出了泡沫酸化工艺对川中低压裂缝性油藏改造具有很强的适应性,具有推广应用的价值.     

苏州市景观水体表观污染类型识别及特征指标筛选

为解决表观污染成因的问题,以苏州市区河网为主要研究对象,采集796个数据样本,对景观水体的表观污染类型进行划分界定,并通过对数据样本的统计分析,探究水体表观污染类型和水质指标之间的关系。结果表明:氧化还原电位、溶解氧、叶绿素a、高锰酸盐指数和浊度对不同污染类型的水体具有很好的区分度,可作为主要特征指标;景观水体可分为有机主导型、无机主导型、营养主导型和混合型4种表观污染类型;不同表观污染水体判别的优先次序为有机主导型、无机主导型、营养主导型、混合型。     

Cryptanalysis of two password authenticated key exchange protocols based on RSA

In 2002, Zhu et al. proposed a password-based authenticated key exchange protocol based on RSA. Many researchers pointed out that Zhu et al.'s protocol is vulnerable to off-line dictionary attack. In 2003, Yeh et al. proposed an improved protocol. Recently, Lo and Yang-Wang pointed out that Yeh et al.'s improved protocol is also vulnerable to offline dictionary attack. To avoid this weakness existed in Yeh et al.'s protocol, Lo and Yang-Wang proposed two improved protocols. However, in this letter, we show that the Lo protocol is vulnerable to an active off-line dictionary attack and the Yang-Wang protocol is vulnerable to a passive off-line dictionary attack.     

信任管理在电子商务中的实现

在电子商务中，信任已经成为谈判策略中的一个重要因素，信任管理也成为安全服务的重要组成部分。本文给出了信任管理在电子商务中的实现。     

桥梁空心墩身施工组织管理

随着时代的发展与改革开放的深化，各城市都在全国性经济建设目标下努力地进行着建设与改革。而在城市建设中，桥梁的建设最为重要。本文对桥梁空心墩身施工组织管理进行了简要地分析与说明，以供大家参考借鉴。     

后张法预应力砼桥梁施工技术应用

现代桥梁工程的重要施工手段是后张法预应力施工。本文根据施工复杂的实际情况，对砼桥梁施工技术进行了分析，并阐述了后张法预应力砼的内容及作用，以供相关人员参考。     

增进城市地区生物多样性——以新加坡模式为例

自 1963 年以来,新加坡开展实施了绿化计划,并经历了从“花园城市”到“花园中的亲生态城市”的演变。为了在新加坡实现生物多样性保护,国家公园局制定了自然保护蓝图,重点介绍该规划实施的关键是利用技术创新。新加坡城市生物多样性指数是一种评价生物多样性成效的自我评估工具,已在全球范围内的多个城市得到应用。     

企业介入的传统村落保护实施探讨——以天津蓟县西井峪村为例

正传统村落承载着中华传统文化的精华,是农耕文明的重要展示窗口和维系华夏子孙文化认同的纽带,其保护与利用既关乎我国传统文化多样性的存续,也关乎乡村地区重构与建设的成败,进而关系到我国现代化进程中的城乡均衡与可持续发展。但传统村落保护同城镇化、农业现代化、新农村建设和农户福利提升之间存在矛盾,相当数量的传统村落或遭受"开发性、建设性"破坏,或因保护约束而日渐衰败,文化断裂、价值观失落等棘手问题接踵而至[1]。     

WWW的信息监控研究

WWW是Internet上进行信息交换的系统。面对WWW日益严重的信息污染问题．信息监控势在必行。本文给出了WWW的信息监控模型，分析了信息监控的各种技术，讨论了当前信息监控面临的问题。     

Sentinel-1 based Soil Moisture Estimation in Middle Reaches of Heihe River Basin

In this study, a change detection model, constructed using the Sentinel-1 Synthetic Aperture Radar (SAR) data and the simultaneous Normalized Difference Vegetation Index (NDVI) products from the Moderate Resolution Imaging Spectroradiometer (MODIS) and Landsat 8 sensors, is applied to estimate soil moisture in middle reaches of the Heihe River Basin, and the effects of two key parameters on retrieval accuracy are comprehensively investigated. The results show that: (1) when constructing the empirical relationship between backscattering coefficient difference ( \mathrm{\Delta } \sigma ) and Vegetation Index (VI) required by change detection model, the optimal sampling ratios in the ( \mathrm{\Delta } \sigma - V I ) space are approximately 2% and 4% for MODIS NDVI and Landsat 8 NDVI, respectively; (2) the Landsat 8 NDVI-based change detection model slightly outperforms the MODIS NDVI-based model in soil moisture retrieval accuracy, with Root Mean Square Error(RMSE) of 0.040 m³/m³ and 0.044 m³/m³respectively; (3) for the key parameters of the change detection method, replacing the ground-based initial soil moisture and scaling factor (maximum soil moisture difference between two adjacent dates \mathrm{\Delta } M s_{max} ) by the low-resolution SMAP/Sentinel-1 L2_SM_SP data will increase the RMSE by 0.01 m³/m³ and 0.04 m³/m³ respectively. Comparing to the parameter of initial soil moisture, the error in soil moisture scaling factor will lead to more significant degradation in the performance of the change detection method, thus it is recommended to use the high precision scaling factor for soil moisture estimation. This study confirms the promising potential of Sentinel-1 data for retrieving high-resolution soil moisture via change detection method and provides practical insight into its application.