共查询到19条相似文献,搜索用时 156 毫秒
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一、前言根据一些无机离子交换剂的离子交换性质,利用它们直接从大体积海水中有选择地吸附某种或某几种放射性核素,然后进行非破坏性的r能谱分析被认为是一种有效的快速分析方法.我们曾用K_4[Fe(CN)_6]与Cu(No_3)_2合成了亚铁氰化铜(CuFC),并初步研究了CuFC定量吸附铯的最佳分析条件,证实合成的CuFC在海水中有极好的机械稳定性及在酸性、碱性和中性条件下对Cs均有很高的选择交换吸附能力.在此基础上本文就CuFC对Cs的最大吸附容量,和铯载体量,吸附时的温度,不同流速等对铯吸附效率的影响及对几种核素的分配系数等作了进一步探讨. 相似文献
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在理论和实验上研究了光学参量振荡中产生的弱压缩真空场的光子统计行为. 弱压缩真空具有强烈的光子聚束效应,这种比热光场更强的聚束效应在量子光学和量子测量中具有重要的应用. 利用远离阈值的光学参量振荡(optical parametric oscillator, OPO )过程,在实验上产生了该弱压缩真空输出,运转波长在铯原子线附近. 通过Hanbury-Brown-Twiss(HBT)测量了OPO输出光场的二阶关联函数,实验结果与理论分析基本一致. 相似文献
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《中国海洋大学学报(自然科学版)》2017,(Z1)
利用第一性原理计算了羟基修饰的石墨烯纳米带(OH-AGNRs)吸附钠原子和氯原子的吸附能、几何结构、电荷密度以及体系的态密度,并与边缘氢修饰石墨烯纳米带(H-AGNRs)的吸附特性进行了比较。计算结果表明:羟基修饰石墨烯纳米带的边缘出现明显的起伏,边缘的起伏角度超过22°;羟基修饰石墨烯纳米带可以稳定吸附钠原子和氯原子,但是吸附能稍小于氢修饰石墨烯纳米带;无论边缘是羟基修饰还是氢修饰,石墨烯纳米带的边缘与中间区域的吸附特性相似,反映了石墨烯表面大π键的独特特性。 相似文献
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利用Monte Carlo (MC)模拟技术研究了非均一的吸附原子与基底相互作用能在一定的生长条件下对超薄膜生长过程的影响.非均一相互作用能是由基底表面原子在垂直和水平方向上实际位置与理想晶格原子位置的偏差所造成.本文用高斯分布来表示这种非均一相互作用能.模拟结果表明:非均一相互作用能对超薄膜的生长过程及薄膜的形貌有显著的影响.这种影响同时受到生长条件的限制,在中等温度时相互作用能的非均一性对岛的个数、平均大小的影响最显著;温度的增加在一定程度上可抵御相互作用能的非均一性对薄膜生长的影响. 相似文献
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基于器件模拟仿真,设计了一种1.5 μm波长InGaAsP-InP晶体管激光器材料外延结构. 其多量子阱有源区置于基区非对称波导中. 仿真结果显示该外延结构能够获得较好的光场限制和侧向电流限制. 对该材料MOCVD生长研究表明,基极重掺杂接触层中Zn2+扩散将导致量子阱严重退化. 通过对其扩散过程的模拟仿真,采用平均掺杂浓度为1×1018 cm-3的梯度掺杂,有效地抑制了Zn2+向量子阱区的扩散. 所获得的外延材料在 相似文献
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黄河水下三角洲沉积物在循环荷载作用下土体中孔压变化实验研究 总被引:4,自引:0,他引:4
利用室内周期循环加载试验 ,对黄河水下三角洲土体中孔隙水压力的变化加以测定 ,通过对波浪水槽试验和动三轴试验 2种方案所获数据分析认为黄河水下三角洲土体 (粉土、粘质粉土、粉质粘土 )存在一破坏的循环极限荷载。在小于此极限循环荷载作用情况下 ,土体中孔隙水压力总体呈现下降趋势 ,没有积累升高的过程 ,不同于砂土在循环荷载作用下孔隙水压力升高导致液化的情况。这一现象对判别黄河水下三角洲土体破坏机制的研究有重要意义。 相似文献
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YAN Shuwang FANG Shouzhong Professor Dept. of Hydraulic Engineering Tianjin University Tianjin P. R. China. Graduate Student Dept. of Hydraulic Engineering Tianjin University Tianjin P. R. China. 《中国海洋工程》1998,(2)
Vacuum loading has been examined as a way of preparing uniformly consolidated soft claysamples.The facility and loading procedure are described in this paper.An analytical solution to the threedimensional consolidation equation is derived for estimating the degree of consolidation of the soil samplewith vacuum loading.The given example shows that the predicted degree of consolidation of a soft claybulk with vacuum loading is close to that measured in the consolidation process. 相似文献
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Qiu Changlin Yan Shuwang
Ph. D. Student Dept. of Hydraulic Engrg. Tianjin University Tianjin Professor Dept. of Hydraulic Engrg. Tianjin University Tianjin 《中国海洋工程》1997,(1)
Strengthening soft foundation by vacuum loading from lower position is a new method of ac-celerating the consolidation of dredger fill.This paper presents the mechanism of soft foundation strength-ening by vacuum loading from lower position and evaluates the effectiveness of this method under variousboundary conditions by means of finite element method(FEM)on the basis of Biot's consolidationtheory. 相似文献
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Yuke Wang Heyang Jia Hongjian Cai Xiangyuan Zhang 《Marine Georesources & Geotechnology》2013,31(3):402-407
ABSTRACTOne-way cyclic loading is more typical for traffic loading and cyclic triaxial test has been recognized as a useful method for solving many engineering problems. Under traffic loading, the influence of variable confining pressure on cyclic behavior of natural organic clay subjected to cyclic traffic loading is rarely reported in the literature. In this study, a laboratory investigation on undrained cyclic behavior of natural organic clay is presented and conducted by cyclic triaxial apparatus. Tests are conducted by both constant confining pressure and variable confining pressure, to simulate the loading conditions induced by passing vehicles in actual engineering. Different stress levels are also considered in this study. By comparing between the results of constant confining pressure tests and variable confining pressure tests, it shows that the one-way cyclic behavior of organic clay is influenced significantly by variation of confining pressure, in terms of pore water pressure, permanent axial strain and stress–strain hysteretic loops. 相似文献
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Gang Zheng Jingjin Liu M. S. Rahman Zaikun Tan 《Marine Georesources & Geotechnology》2017,35(5):631-642
This paper describes a full-scale test on a very soft clay ground around 70,000?m2, which is conducted in Huizhou of Guangdong Province, China, to present a new method of vacuum preloading method. A novel moisture separator was developed, which can automatically regulate the vacuum pressure variation by changing the volume of the gas inside it. A large quantity of water drained by the proposed moisture separators can be directly used as a surcharge loading, which would shorten the ground improvement time and save costs as well. Three levels of silt-prevention prefabricated vertical drains were used in the treating process to accelerate the consolidation. In addition, the vacuum preloading method also included an effective radial drainage device which would strengthen the dredged soft clay fill in a deep layer. In the in situ test, tens of piezometers and settlement plates were installed to measure the variations of excess pore water pressures and settlement of two stages of observation points at different positions in the ground. The results show that the largest average consolidation settlement was 314.1?cm and made a saving of more than 66% in power consumption compared with traditional method. It demonstrates that this adopted method is an efficient, cost-effective, and environmentally friendly method for improving sites with low bearing capacity and high compressibility soils. 相似文献
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Consolidation occurs in estuarine marine clays for coastal reclamation by dissipation of the excess pore pressure, which is induced by increasing the total overburden stress during conventional mechanical surcharging. The excess pore pressure can be decreased usually by the use of several construction methods such as sand drain and paper drain. Besides the drain methods, vacuum can also be used in the soil mass to consolidate the estuarine marine clays by decreasing the pore pressure as well as increasing the effective stress.The study on vacuum consolidation is devoted so far mainly for laboratory model tests or numerical analysis in Korea. Recently, an instrumentation system was applied to manage the vacuum-applied consolidation on a field, in which a sewage disposal plant was constructed. While vacuum was applied, the behaviors of estuarine marine clays such as the settlement, lateral deformation and pore water pressure have been investigated precisely. The behavior of estuarine marine clays during vacuum-applied consolidation shows some difference from the behavior of estuarine marine clays in the case of conventional preloading. A principal difference is that the lateral deformation corresponding to settlement is smaller than before vacuum application even though the surcharge height has been increased. 相似文献
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The influence of cyclic loading on the strength and deformation behavior of cemented marine clay has been studied. This marine clay is of recent Pleistocene origin and deposited in a shallow water marine environment. Open pits were dug in sheeted enclosures and from these pits, undisturbed samples were taken for strength testing. A series of standard triaxial shear tests and stress controlled one-way cyclic load tests were conducted at consolidation stress ranges below and above the preconsolidation pressure. For the stress levels below the preconsolidation pressure, the cyclic loading has brought about the collapse of the cementation bond through an increase in strains, and at higher pressure ranges, the soil behaves like typical soft clay. This experiment studied the rate of development of strain and pore water pressure and shows that rate is a function of number of cycles, applied stress, and stress history. In addition, soil degradation during cyclic loading is studied in terms of Degradation Index. Attempt has been made to predict stain, pore water pressure, and degradation index through an empirical model. 相似文献
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通过一系列室内试验,研究了黄河口粉质类沉积物在循环动荷载作用后侵蚀性的变化.在试验中,采用真空预压固结装置制备重塑土样,采用液压伺服土动三轴试验机实现了不同幅值及不同振次的动荷载作用条件,并通过动三轴静态试验及贯入强度测试,测定了动荷载作用后土样强度的变化.通过水槽冲刷试验测试了不同条件的动荷载作用后,土样抗冲刷能力的变化,并进行了临界剪切应力的计算.试验结果表明:对于黄河口粉质类沉积物,动荷载作用后其强度及抗侵蚀性均降低;沉积物强度指标(不排水剪切强度、残余强度、贯入阻力)、侵蚀性指标(起动流速、临界剪切应力、冲刷率)与动荷载幅值、动荷载振次均呈现出较好的线性相关性. 相似文献