Microstructural and mechanical properties of marine clay cemented with industrial waste residue-based binder (IWRB)

Improving the engineering properties of low-strength soft clay in an environmentally friendly way becomes a challenge in coastal areas. Conventional ground treatment techniques for marine clay using cement can cause significant environmental pollution. In this study, the potential use of industrial waste residue-based binder (IWRB), a silicate-based chemical modified by a powdery polymer, as a substitute for Portland cement (PC) is investigated. Collected marine clay was treated with various IWRB-to-PC ratios (0:8, 4:4, 2:6 and 8:0 wt. %) to measure the mechanical properties, through unconfined compression (UC) test and one-dimensional consolidation (ODC) test, and the microstructural and mineralogical characters, through scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetry analysis (TGA) and Fourier transform infrared spectroscopy (FT-IR). The strength and the deformation of specimens treated with mixed IWRB and PC in a ratio of 1:1 were similar to those improved with PC alone, but the toughness was significantly improved. The microstructural results demonstrated that the cementitious compounds (C–S–H and C–A–S–H) increased significantly in the early curing stage of marine clay treated with IWRB, contributing to the improvement of mechanical properties. It is suggested that IWRB can be an effective substitute for PC to reduce the cost and environmental pollution.

     

西藏阿里地区盐湖浮游生物生态调查

2006年8~10月对西藏阿里地区21个湖泊的浮游生物作了初步调查,采得44个浮游生物样品和22个水化学样品。经鉴定分析得浮游植物105种(变种),分属5门49属,其中硅藻门19属63种(变种),占总种数的60%;浮游动物14种,分属3门11属,其中亚洲后镖水蚤(Metadiaptomus asiaticus Uljanirs)为西藏首次记录。有螺旋藻、盐藻、西藏拟溞、卤虫等经济种分布的湖泊数分别为8、3、5、12个。浮游生物物种多度随盐度升高而降低,统计分析表明,在0.31~300.71g/L盐度范围内,浮游生物物种多度与盐度存在不显著负相关关系(r2=-0.05,p>0.05)。文章讨论了西藏拟溞与桡足类之间存在的季节性种群更替现象,以及硅藻在这一现象中可能存在的重要作用。最后对盐湖生物资源特别是西藏拟溞的开发利用提出了设想。     

聊天机器人技术浅析

对话系统已经成为人工智能时代重要的人机交互接口.聊天机器人技术在对话系统技术发展中扮演着至关重要的角色,代表了对话系统技术的前沿发展.从聊天机器人技术的兴起入手,深入分析聊天机器人技术的发展趋势,介绍国内外学术界和产业界的聊天机器人技术研究进展,重点介绍聊天机器人的3项关键技术,即基于检索的多轮对话技术、基于生成的对话...     

Microbial Mats in Tibetan Hot Springs and their Contributions to the Cesium‐bearing Geyserite Ore Formation

Microbial mats, mainly dominated by filamentous algae Calothrix and Oscillatoria, are well developed in Tibetan hot springs. A great number of fossil microorganisms, which existed as algae lamination in thermal depositional cesium-bearing geyserite in this area, are identified as Calothrix and Oscillatoria through microexamination and culture experiments. These microbial mats show the ability to accumulate cesium from spring water to the extent of cesium concentration of 0.46–1.03% cell dry weight, 900 times higher than that in water, and capture large numbers of cesium-bearing opal grain. Silicon dioxide colloid in spring water replaces and fills with the organism and deposits on it to form algae laminated geyserite after dehydration and congelation. Cesium in the microbial mats and opal grain is then reserved in the geyserite. Eventually, cesium-bearing algae laminated geyserite is formed. Study on cesium distribution in geyserite also shows that cesium content in algae lamination, especially in heavily compacted algae lamination, is higher than in the opal layer. For geyserite with no algae lamination or other organism structure, which is generally formed in spring water with low silicon content, cesium accumulation and cesium-bearing opal grain assembled by the microbial mats are also indispensable. After the microbial mats accumulating cesium from spring water, silicon dioxide colloid poorly replaces and fills with the organism to form opal grain-bearing tremellose microbial mats. The shape and structure of the organisms are then destroyed, resulting in cesium-bearing geyserite with no algae lamination structure after dehydration and congelation. It is then concluded that microbial mats in the spring area contribute to the enrichment of cesium in the formation of cesium-bearing geyserite, and a biological genesis of the geyserite, besides of the physical and chemical genesis, is likely.     

内蒙古锡林郭勒盟盐湖浮游生物的群落特征

通过2003年9月-2004年1月的渔获物调查,并结合1984-2002年的鱼类产量统计资料,分析了近二十年来太湖鱼类产量和组成的变化规律以及环境间的相互作用关系.结果表明,太湖鱼类的种类在不断减少,如本次调查和2002年3月-2003年12月的调查只采集到48种鱼类,和历史资源料比较有55种鱼类难以采到;鱼类产量组成表现为仅鲚鱼的产量和组成比例总体呈较快的上升趋势,从1984年的5153.7t、占总产量的36.2%上升到2002年的19571t、64.1%,鲤、鲫鱼基本维持不变,但近四年略有上升,其余鱼类均呈下降趋势.用Wilhm改进式计算的鱼类产量组成的均匀度指数H总体呈逐年下降趋势,近二十年来平均以每年-0.0465的速率下降;分析认为,人类活动以及由此引起的太湖生态环境变化,包括江湖阻隔、过渡捕捞、富营养化及太湖特有的鱼类生态学特点决定了鱼类组成的这一变化趋势:江湖阻隔、过度捕捞是引起太湖鱼类种类减少和鱼类组成发生巨大变化的主要原因;太湖近二十年来富营养化程度不断加重,由此使初级生产力水平持续增长,浮游生物饵料丰富,使鲚鱼等浮游生物食性鱼类产量逐年提高;舶鱼数量的减少又使鲚鱼失去抑制.随着鲚鱼等浮游动物食性鱼类产量的升高,太湖浮游动物的生物量呈下降趋势,这可能是太湖浮游植物数量倍增的生物学因素之一.目前太湖鱼类产量组成的变化正向着抑制浮游动物和有利浮游植物生长的方向发展.     

Simplified methods to analyze geosynthetic mattress resting on deformable foundation soil

A special case of geosynthetic tubes is the geosynthetic mattress characterized by its larger width-to-height ratio and higher lateral-force-resisting capacity. When the geosynthetic mattresses are adopted for dike or breakwater construction in coastal engineering projects, they are often laid on deformable foundation soil. The induced ground settlement will influence the cross-sections and tensile forces of the geosynthetic mattresses. Two analytical methods, called the Winkler foundation method and the e–log p method, are proposed in this paper to analyze the geosynthetic mattresses resting on deformable foundation soil. For the Winkler foundation method, the subgrade soil is assumed as a Winkler elastic foundation represented by the modulus of subgrade reaction, K_f. For the e–log p method, the 1D consolidation relationship (e–log p curve) is adopted to describe the behavior of the subgrade soil within which the distribution of vertical surcharge is calculated using Boussinesq equation. The numerical analyses using FLAC are also conducted to evaluate the accuracy of the proposed methods. The differences between the analytical and numerical solutions are also discussed. It is found from this paper that the proposed e–log p method is more suitable than the Winkler foundation method for the calculation of the geosynthetic mattress resting on deformable foundation soil.     

Progress and Prospects of Salt Lake Research in China

China has unique salt lake resources, and they are distributed in the east of Eurasian salt lake subzone of the Northern Hemisphere Salt Lake Zone, mainly concentrated in the regions with modern mean annual precipitation lower than 500 mm. This paper preliminarily reviews the progress made in salt lake research in China for the past 60 years. In the research of Paleoclimate and paleoenvironment from salt lake sediments, a series of salts have been proposed to be indicators of paleoclimate, and have been well accepted by scholars. The chloride-sulfate depositional regions of the west Qaidam and the east Tarim have been revealed to be the drought center of China since the Quaternary, and more than 6 spreading stages of arid climate(salt forming) have been identified. Five pan-lake periods with highstands have been proved to exist during the late Quaternary on the Tibetan Plateau. In mineral resource prospecting and theories of the forming of salt deposits: the atlas(1:2500000) of hydrochemical zoning of salt lakes on the Tibetan Plateau has been compiled for the first time, revealing the zonal distribution and transition from carbonate type to chloride type from south to north and presenting corresponding mineral assemblages for different type of salt lakes; several large continental salt deposits have been discovered and the theory of continental potash deposition has been developed, including the salt deposition in deep basins surrounded by high mountains, the mineral deposition from multistage evolution through chains of moderate or shallow lakes with multilevels, the origin of potassium rich brines in gravel layers, and the forming of potassium deposits through the inheriting from ancient salt deposits, thus establishing the framework of "Continental Potash Deposition Theory"; several new types of Mg-borate deposits have been discovered, including the ulexite and pinnoite bed in Da Qaidam Lake, Qinghai, the pinnoite and kurnakovite bed in Chagcam Caka, Tibet, the kurnakovite bed in Lake Nyer, and the corresponding model of borate deposition from the cooling and dissolution of boron rich brines was proposed based on principles of geology, physics and chemistry. The anti-floatation-cold crystallization method developed independently has improved the capacity of KCl production to 3 million tons per year for the Qarham, serving the famous brand of potash fertilizer products. One 1.2 million ton K-sulfate production line, the biggest in the world, has been built in Lop Nor, and K-sulfate of about 1.6 million tons was produced in 2015. Supported by the new technology, i.e. brine preparation in winter-cooling-solarization-isolation-lithium deposition from salt gradient solar pond" the highest lithium production base at Zabuye Lake(4421 m), Tibet, has been established, which is the first lithium production base in China that reaches the year production of 5000 tons of lithium carbonate. The concept of Salt lake agriculture(Salt land agriculture) has been established based on the mass growth of Dunaliella and other bacillus-algae and the occurrence of various halophytes in saltmarsh and salt saline-alkali lands, finding a new way to increase arable lands and develop related green industry in salt rich environments. Finally this paper presents some new thoughts for the further research and development on salt science, and the further progress in salt science and technology will facilitate the maturing of the interdisciplinary science "Salinology".     

Highstands in the interior of the Qinghai–Tibetan Plateau since the last interglacial: evidence from grain‐size analysis of lacustrine core sediments in Zabuye Salt Lake

Highstands in the Marine Isotope Stage (MIS) 3 based on ¹⁴C dating in the Qinghai–Tibetan Plateau (QTP) are widely documented. Recent records from shoreline sediments dated using U‐series and/or optically stimulated luminescence (OSL), however, reveal that the highstands originally dated in MIS 3 should now be considered to fall in MIS 5. This paper provides new evidence from the interior of the QTP, based on the grain‐size from a continuous lake core in the Zabuye Salt Lake, to verify the MIS 5 highstand in the QTP. Grain‐size analysis of the core sediments also distinguishes two other highstands in MIS 3 and MIS 2, respectively. The MIS 5 highstand is considered as the maximum lake level since the Last Interglacial, as cored sediments contain very low values of Median Diameter (Md) during MIS 5. Compared with the discontinuous records from lake shorelines sediments, the grain‐size records from the continuous lake centre core sediments provide a more complete dataset to infer lake level variations, and make it possible to make wider palaeoclimatic and palaeoenvironmental interpretation. In the interior of the QTP, highstands might have continued into cold climate periods due to the reduced evaporation rates in the latter. The influence of the moisture‐bearing southerly‐shifted Westerly wind pathway may also have contributed to the highstands in the glacial period. Copyright © 2015 John Wiley & Sons, Ltd.     

基于多智能体的洪涝风险动态评估理论模型

随着全球气候变化的加剧和城市化进程的快速发展,洪涝灾害的影响和复杂性日益加剧。洪涝灾害风险评估是一项复杂的系统工程,在防洪减灾工程理论与实践中具有重要意义;作为洪涝灾害风险管理和应急处置的基础和核心,风险评估模型直接影响洪涝灾害风险评估结果的可靠性。洪涝灾害风险是洪涝灾害复杂系统组成部分相互作用的结果,综合考虑洪涝灾害系统的特点以及智能体建模的优势,提出了一种基于多智能体的洪涝风险动态评估理论模型。首先从复杂系统建模的角度出发,对洪涝灾害复杂系统进行分析建模,构建基于多智能体的洪涝灾害风险动态评估框架模型;其次,对所构建的框架模型中单个智能体模型进行研究,分别建立基于反应型的孕灾环境智能体模型和基于慎思型的致灾因子、承灾体和风险分析智能体模型,并对以上单个智能体的流程进行研究;然后以风险分析智能体联盟为例对模型框架中所涉及到4类智能体联盟的内部结构和流程进行分析,对构建的框架模型中涉及到的智能体通信协调和作用规则进行探讨;最后,在Netlogo平台上,基于30 m DEM数据和构建的模型,对淮河流域的暴雨型洪涝孕育发生发展全过程的人口风险进行动态评估。结果表明,构建的模型能有效评估洪涝灾害全过程中人口风险的动态。研究结果对洪涝灾害人口灾情评估、应急救助和应急管理都具有较强的指导意义。     

利用三次卷积方法实现新一代天气雷达产品电视播出

针对地市级电视天气预报节目中雷达网制作环节存在的问题,使用VB编程丁具,读取单站新一代天气雷达产品的第19类数据(反射率因子),利用三次卷积插值算法进行放缩,生成可适用绝大多数非编软件播出的带有Alpha通道的TGA文件序列,并且可以通过Alpha通道叠加背景图片或动态视频,实现雷达产品在电视天气预报节目中播出.实践证明,三次卷积插值方法不仅内插精度较高、图像的颜色连续,所得图像质量较其它插值方法明显提高,符合播出标准,而且还能较好地保留图像的高频成分.