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221.
X. Zheng Y. Zhang T. Cheng M. Zhao H. Kong Z. Jin 《International Journal of Environmental Science and Technology》2016,13(8):2091-2096
In order to prepare iron phosphate by waste sludge, we report a method for effective utilization of the sludge obtained from the electrocoagulation treatment of source-separated urine. The sludge was dissolved with hydrochloric acid and pretreated with H2O2 and Na3PO4; finally, NaOH was added to precipitate iron phosphate from the solution. Thermal treatment of the precipitate at 750 °C in air yielded crystalline quartz-like anhydrous FePO4. The precipitate was characterized by a number of thermal techniques such as thermogravimetry/differential thermal analysis, scanning electron microscopy, and X-ray powder diffraction. 相似文献
222.
Human-machine interactive visiting and fixed-route visiting are currently the main roaming modes in digital three-dimensional (3D) scenes. However, in general, when a person visits an attraction area, s/he does not follow a fixed path, but instead wander about according to his/her interests. Here, we propose a new roaming mode, called autonomic visiting. That is, in a digital 3D scene, a user selects several interest spots, then a route connecting these spots can be automatically determined and 3D scene can be seen along this route. This study presents a technical approach that enables the realization of autonomic visiting in 3D scenes. Firstly, Delaunay triangular meshes for the terrain in 3D scene are established. Secondly, a plane-growth algorithm and a line-connection algorithm are introduced to automatically mend the broken parts of these triangular meshes. Thirdly, the triangular meshes are then merged and differently weighted according to different layers. Finally, a progress-zone transmission algorithm is presented to optimal the shortest route, which is derived from A-Star (A*) algorithm. Digital 3D campus of Nanjing University, China, is taken as the experimental materials. The experimental results prove the effect of the proposed approach. 相似文献
223.
Hongguang Jiang Xuecheng Bian Chong Cheng Yunmin Chen Renpeng Chen 《Acta Geotechnica》2016,11(2):231-242
Ballastless high-speed railways have dynamic performances that are quite different from those of conventional ballasted railways. The essential dynamic characteristics of high-speed railways due to passing train wheels, such as the cyclic effect, moving effect, and speed effect, were put forward and discussed. A full-scale accelerated railway testing platform for ballastless high-speed railways was proposed in this study. The feasibility of the sequential loading method in simulating train moving loads, and the boundary effect of the proposed physical model of ballastless railways, was investigated using three-dimensional finite element models. A full-scale physical model, 5 m long, 15 m wide, and 6 m high, was then established according to practical engineering design methods. Using a sequential loading system composed of eight high-performance hydraulic actuators, loads of a moving train with highest speed of 360 km/h were simulated. Preliminary experimental results of vibration velocities were presented and compared with field measurements of the Wuguang high-speed railway in China. Results showed that the experimental results coincided with the field measurements, demonstrating that the full-scale accelerated railway testing platform can simulate the process of a moving train and realistically reproduce the dynamic behaviors of ballastless high-speed railways. 相似文献
224.
225.
Cheng Yinhe Zhou Shengqi Wang Dongxiao Lu Yuanzheng Huang Ke Yao Jinglong You Xiaobao 《中国海洋湖沼学报》2016,34(3):619-628
The observed characteristics of lower atmospheric ducts over the South China Sea(SCS) were analyzed based on Global Position Systerm(GPS) radiosonde data collected four times daily during autumn open cruises from 2006 to 2012.Duct occurrence,thickness,and strength over the SCS were about 40%,150-m thick,and 8 M units,respectively,which were larger than during the summer monsoon period.Most ducts occurred at heights 1 500 m and these ducts easily trap electromagnetic wave clusters with wavelengths 2 m.Diurnal variation of the SCS ducts appeared evident.They occurred more often at midnight at higher altitudes(about 1 100 m),with a thickest layer of about 145 m and less frequently during the evening at lower altitudes(about 800 m),with a thinnest layer of about 125 m.Moreover,ducts during the daytime at a mean height of about 900 m,with the greatest strength of about 10 M units.Furthermore,all duct variables observed over the SCS in autumn decreased from north to south.These findings are useful not only in the design of radar and communication systems,but also for evaluating possible effects of anomalous propagation on meteorological radar and military applications. 相似文献
226.
Jian-bing Xu Bin Cheng Qian Deng Yun-gan Liang Oluwabamise Lekan Faboya Ze-wen Liao 《中国地球化学学报》2018,37(6):886-900
There is a dearth of information about the distribution of trace elements in kerogen from shale rocks despite several reports on trace element composition in many shale samples. In this study, trace elements in shale rocks and their residual kerogens were determined by inductively coupled plasma–mass spectrometry. The results from this study show redox-sensitive elements relatively concentrated in the kerogens as compared to the shales. This may be primarily due to the adsorption and complexation ability of kerogen, which enables enrichment in Ni, Co, Cu, and Zn. For the rare earth elements (REEs), distinct distribution characteristics were observed for shales dominated by terrigenous minerals and their kerogen counterparts. However, shales with less input of terrigenous minerals showed similar REE distribution patterns to their residual kerogen. It is speculated that the distribution patterns of the REEs in shales and kerogens may be source-related. 相似文献
227.
Delu Li Rongxi Li Zengwu Zhu Xiaoli Wu Futian Liu Bangsheng Zhao Jinghua Cheng Baoping Wang 《中国地球化学学报》2018,37(1):134-150
Using trace elements to reconstruct paleoenvironment is a current hot topic in geochemistry. Through analytical tests of oil yield, ash yield, calorific value, total sulfur, major elements, trace elements, and X-ray diffraction, the quality, mineral content, occurrence mode of elements, and paleoenvironment of the Zhangjiatan oil shale of the Triassic Yanchang Formation in the southern Ordos Basin were studied. The analyses revealed relatively high oil yield (average 6.63%) and medium quality. The mineral content in the oil shale was mainly clay minerals, quartz, feldspar, and pyrite; an illite–smectite mixed layer comprised the major proportion of clay minerals. Compared with marine oil shale in China, the Zhangjiatan oil shale had higher contents of quartz, feldspar, and clay minerals, and lower calcite content. Silica was mainly in quartz and Fe was associated with organic matter, which is different from marine oil shale. The form of calcium varied. Cluster analyses indicated that Fe, Cu, U, V, Zn, As, Cs, Cd, Mo, Ga, Pb, Co, Ni, Cr, Sc, P, and Mn are associated with organic matter while Ca, Na, Sr, Ba, Si, Zr, K, Al, B, Mg, and Ti are mostly terrigenous. Sr/Cu, Ba/Al, V/(V + Ni), U/Th, AU, and δU of oil shale samples suggest the paleoclimate was warm and humid, paleoproductivity of the lake was relatively high during deposition of the shale—which mainly occurred in fresh water—and the paleo-redox condition was dominated by reducing conditions. Fe/Ti ratios of the oil shale samples suggest clear hydrothermal influence in the eastern portion of the study area and less conspicuous hydrothermal influence in the western portion. 相似文献
228.
选取广西容县花岗岩残积土为研究对象,取击实曲线上3个不同含水率对应的压实样(最佳含水率及干侧、湿侧,后两者对应的干密度相同)分别进行了直剪试验、扫描电镜观测(SEM)和压汞试验(MIP),并从微观特征解释其力学性能的差异。结果表明:(1)花岗岩残积土在3种压实状态下具有相同应力-应变曲线形状,无明显峰值,抗剪强度在最佳状态时的最高,湿侧状态抗剪强度与干侧状态相近,3种状态下内摩擦角值差别较小,但黏聚力在最佳状态时最大,干侧和湿侧状态较最佳状态分别下降66.4%和43.1%;(2)花岗岩残积土在湿侧状态下普遍形成团聚体,团聚体之间呈架空结构,累积孔隙体积最大,为明显的双峰分布孔隙特征;在最佳状态下组构最密,高岭石片定向性排列;在干侧状态下高岭石片呈片架结构,累积孔隙体积最小;随着含水率的降低,土样双峰孔隙特征逐渐变得不明显;(3)花岗岩残积土在不同状态时的微观特性较好地解释其力学性质的差异。 相似文献
229.
都匀市是贵州省城镇滑坡地质灾害多发频发区。文章以都匀市沙包堡镇为研究区,采用栅格单元提取高程、坡度、岩性、水系等9项致灾因子,分别使用都基于数学统计模型的定量分析方法(二元逻辑回归模型、信息量模型)和定性分析方法(层次分析模型)对都匀市研究区滑坡地质灾害易发性进行评价。结果表明:二元逻辑回归模型预测精度与预测效果均为最优,其ROC曲线下面积AUC值为0.873,易发性分区中高易发区和中易发区内预测发生滑坡面积比占95.41%,且最符合野外实地调查验证情况。评价方法与结果可为贵州城镇地区滑坡地质灾害评价和防治提供借鉴。 相似文献
230.
重度石漠化区不同土地利用方式下土壤养分特征 总被引:1,自引:1,他引:0
本文以云南省蒙自市西北勒乡碧色寨村石漠化土地为研究对象,基于主成分分析法(PCA)研究岩溶石漠化区不同土地利用方式下的土壤养分特征。结果表明:(1)研究区土壤各养分指标变异系数介于0.14~1.76,不同土地利用方式下,土壤养分状况有较大差异;(2)研究区土壤12项养分指标可归结为3个主成分,所提供的信息占全部信息的90.69%,其中PC1主要包含了全磷、有效磷、速效钾和有效锰,PC2主要综合了有机碳、全氮、全钙和有效锌,有效铁对PC3具有较大的贡献。(3)对不同用地类型土壤养分的主成分得分进行排序,由大到小依次为火龙果地>林地>封育草地>玉米地,表明植树造林及火龙果种植等方式能有效改善石漠化区的土壤养分状况。建议对样区的石漠化治理应以封山育土为前提,以生态恢复为目的,通过种植火龙果与修复林地改善样区土壤状况,逐步形成生态环境与社会经济协调发展的石漠化综合治理体系。 相似文献