APPLICATION OF SIMILARITY PRINCIPLE TO STRATIFICATION THEORY STUDY IN GRAVITY CONCENTRATION

The stratification processes have been studied by the application of the similarity principle, and the similarity criteria has also been derived.Two possible π-equations were deduced from the experimental results.The approach of the π-equation to predict separating results and to control the separating processes is presented with examples.

First-principles investigation of the concentration effect on equilibrium fractionation of Ca isotopes in forsterite

Previous theoretical studies have found that the concentration variations within a certain range have a prominent effect on inter-mineral equilibrium isotope fractionation(10^3 lna).Based on the density functional theory,we investigated how the average Ca–O bond length and the reduced partition function ratios(10^3 lnb)and103lna of 44 Ca/40 Ca in forsterite(Fo)are affected by its Ca concentration.Our results show that Ca–O bond length in forsterite ranges from 2.327 to 2.267 A with the Ca/(Ca+Mg)varying between a narrow range limited by an upper limit of 1/8 and a lower limit of 1/64.However,outside this narrow range,i.e.,Ca/(Ca+Mg)is lower than1/64 or higher than 1/8,Ca–O bond length becomes insensitive to Ca concentration and maintains to be a constant.Because the 10^3 lnb is negatively correlated with Ca–O bond length,the 10^3lnb significantly increases with decreasing Ca/(Ca+Mg)when 1/64<Ca/(Ca+Mg)<2/16.As a consequence,the 10^3lna between forsterite and other minerals also strongly depend on the Ca content in forsterite.Combining previous studies with our results,the heavier Ca isotopes enrichment sequence in minerals is:forsterite[orthopyroxene[clinopyroxene[calcite & diopside[dolomite[aragonite.Olivineand pyroxenes are enriched in heavier Ca isotope compared to carbonates.The 10^3lna between forsterite with a Ca/(Ca+Mg)of 1/64 and clinopyroxene(Ca/Mg=1/1,i.e.,diopside)is up to^0.64%at 1200 K.The large 103lnaFodiopsiderelative to the current analytical precision for Ca isotope measurements suggests that the dependence of10^3 lnaFo-diopsideon temperature can be used as a thermometer,similar to the one based on the 103lna of 44 Ca/40 Ca between orthopyroxene and diopside.These two Ca isotope thermometers both have a precision approximate to that of elemental thermometers and provide independent constraints on temperature.

紧凑型混合励磁三相饱和铁芯型故障限流器

加装饱和铁芯型故障限流器是限制高压系统短路电流的有效方法,但其需要与外加的限流空心电抗器配合,导致整个限流系统占地面积和体积很大。因此,基于非正交解耦原理提出了一种紧凑型混合励磁三相饱和铁芯型故障限流器(compact hybrid-biased three-phase saturated core fault current limiter,CTFCL),其具有占地面积和体积小的优点。首先,提出了含非正交解耦绕组的CTFCL拓扑。其次,建立了CTFCL的等效电磁路模型,分析了其工作原理。然后,给出CTFCL的参数设计准则,搭建了220 kV的有限元模型,仿真验证了CTFCL的限流效果和电磁特性。最后,设计并研制出小容量样机,开展了实验研究。仿真和实验结果均证明了该文所提CTFCL的有效性,CTFCL对各种短路均有良好的限制效果,且对比得到CTFCL限流系统占地面积和体积较传统三相SCFCL限流系统分别减少了44%和26%,适合实际高压系统的安装与应用。

基于磁各向异性的管壁应力集中区域检测方法

针对应力集中导致管壁发生屈服失效的问题,提出了利用磁各向异性检测管壁应力集中区域的方法。从能量角度出发,研究了应力导致管壁产生磁各向异性的机理,建立了管壁当量应力与磁各向异性探头输出电压信号的数学模型,通过计算管壁的当量应力判断其是否发生屈服失效,搭建了应力检测实验平台。实验结果表明,应力会导致管壁产生磁各向异性,磁各向异性检测方法能够检测出管壁当量应力的变化趋势和主应力方向所在延长线的角度,进而判断管壁是否产生应力集中区域。

螺旋溜槽分选技术发展现状和展望

螺旋溜槽分选是利用流膜重力和斜面流分选的重选方法,具有处理量大、能耗低、无污染、分选效率高、分选范围广等优点,在矿物加工领域应用广泛。本文深入阐述了螺旋溜槽在其发展历程中所解决的关键技术问题、不同型号螺旋溜槽的特点及其存在的主要问题。同时,还系统梳理了关于螺旋溜槽流膜运动状态、颗粒运动轨迹及槽面优化设计的最新研究动态。最后,对当前螺旋溜槽分选技术的应用状况进行了全面总结,并对该技术的发展趋势进行了展望。本文内容可为螺旋溜槽分选技术的发展提供参考。

细胞外囊泡表征检测方法的对比

细胞外囊泡(extracellular vesicles,EVs)是细胞主动分泌的具有磷脂双分子层结构的囊泡,天然携带母细胞来源的各种内容物,保留母细胞的生物学特征,可以反映其分泌时的母细胞状态。为了解EVs的生物发生及其在机体内的生物学功能,科学家们做了许多尝试,但直接检测EVs有一定的困难,目前的检测技术通常以EVs内容物作为检测对象,实现间接表征的目的。通过分析体液中的EVs,可以实现疾病诊断的目的,对EVs进行详细表征可以推动精准医学的发展。EVs属于内源性物质,可作为递送药物的载体,具有增加药效、降低药物毒理作用和辅助药物通过生物屏障的优势。目前,作为药物或者递送药物的载体应用尚存在的问题,包括(1)EVs内容物的表征,以便使用更明确定义的EVs;(2)开发适合的检测方法来监测体内的EVs,以确定和优化EVs的剂量、给药途径及潜在毒性;(3)确定EVs膜组成的种类及数量。EVs直径为纳米级别,内容物含量少,但临床应用价值大。应用中选择合适的分析技术将能够对EVs类型进行全面表征,并进一步推进对EVs生物学的理解,开发基于EVs的新型诊断和治疗方法,促进其临床转化。本综述介绍了EVs研究中分析技术的原理、应用及优缺点,重点是EVs和EVs中蛋白质的表征检测技术。

云南省地级城市近20年空间格局演变

以云南省16个地级城市为研究区域,基于2000-2017年6个时间段的遥感影像、GDP、人口等数据,通过城市面积、扩展面积、扩展速度、扩展强度、用地增长弹性系数、空间扩展类型、紧凑度等7个评价指标来揭示云南省近20年城市扩展空间演变规律。结果表明,(1)空间格局上,在这17年间城区规模呈直线攀升,且城市扩展呈现出明显阶段性和地域差异性。(2)用地效益上,城市用地增长弹性系数均大于最优值,城市土地的扩展远大于城市人口的增长,二者出现不协调。(3)扩展类型上,在2000-2010年基本为外延型扩展,2011-2017年内部填充型扩展城市增多。(4)空间形态上,城市紧凑度呈现出“西高东低”的特征,而时间进程上表现为西南部地区先降后升,东部地区逐渐提升。

免蒸养抗开裂超高性能混凝土的制备及性能研究

为进一步提高超高性能混凝土(UHPC)抗开裂性能,降低生产制备中热养护所产生的能耗,通过复合掺入硫铝酸盐水泥(CSA)熟料制备了一种免蒸养抗开裂UHPC。基于最紧密堆积原理对UHPC原材料配合比进行设计,评价了UHPC的工作性能、力学性能、抗开裂性能。结果显示:制备的UHPC工作性能优异,随CSA熟料掺量的增加,UHPC的流动度减小,凝结时间缩短;CSA掺量为10%时,UHPC的流动度为240 mm,抗拉强度为7.848 MPa,28 d抗压强度为146.3 MPa,7 d总收缩值约为3000με,抗裂指数为11.23%。

基于择优掺杂取向研究Y掺杂量对ZnTe电子结构和吸收光谱的影响

Zn Te由于其特有的禁带宽度,光学性质以及可重掺杂等特性,使得众多学者对其进行了系列的相关研究,但关于Y掺杂浓度和掺杂方式对Zn Te性质的影响却鲜有报道.作者采用密度泛函理论框架下的广义梯度近似方法,分别计算了Y在掺杂浓度为1.56at%、3.12at%、4.69at%下Zn Te的几何结构、能带结构、态密度分布、吸收光谱等性质,以及不同掺杂方式对体系的影响.结果表明:在掺杂浓度为3.12at%,掺杂方式不相同时,掺杂原子沿[111]晶向排布的形成能最低,即[111]晶向为择优晶向.当掺杂浓度为4.69at%时,择优晶面为(111)面.若要实现更高浓度的Y掺杂,沿(111)晶面掺杂更容易实现.对于实验而言,更高浓度的Y掺杂,掺杂原子在Zn Te体系中更容易沿(111)晶面进行集中排列. Y掺杂Zn Te后,体系的禁带宽度变大,吸收光谱发生蓝移,对可见光的吸收强度减小.在浓度为3.12at%时禁带宽度最大,蓝移现象最明显,吸收强度最小. Y掺杂后体系变为n型半导体,可以使用这种掺杂方式制作P-N结二极管.

装配式桥墩节点连接密实性监测技术研究

在装配式混凝土结构中,预制构件间的节点密实度是影响节点受力性能的关键因素,其直接影响结构的承载力和抗震能力。为此,提出了一种基于振动阻尼原理的密实性监测系统,详细介绍了该监测系统的工作原理,并提出了基于振动阻尼传感器的装配式桥墩节点连接密实性监测实施工艺。同时,以实际工程为依托,选取混凝土盖梁、桥墩为研究对象,对节点密实性进行分析。结果表明,压浆初期传感器振幅衰减缓慢,中后期衰减加快,且不同出浆孔中传感器振幅存在一定的离散性。

ON THE CONCENTRATION PROPERTIES FOR THE NONLINEAR SCHRDINGER EQUATION WITH A STARK POTENTIAL

In this paper, we study blow-up solutions of the Cauchy problem to the L2 critical nonlinear Schrdinger equation with a Stark potential. Using the variational characterization of the ground state for nonlinear Schrdinger equation without any potential, we obtain some concentration properties of blow-up solutions, including that the origin is the blow-up point of the radial blow-up solutions, the phenomenon of L2-concentration and rate of L2-concentration of blow-up solutions.

VECTORIAL EKELAND VARIATIONAL PRINCIPLE AND CYCLICALLY ANTIMONOTONE EQUILIBRIUM PROBLEMS

In this article, we extend the cyclic antimonotonicity from scalar bifunctions to vector bifunctions. We find out a cyclically antimonotone vector bifunction can be regarded as a family of cyclically antimonotone scalar bifunctions. Using a pre-order principle(see Qiu, 2014), we prove a new version of Ekeland variational principle(briefly, denoted by EVP), which is quite different from the previous ones, for the objective function consists of a family of scalar functions. From the new version, we deduce several vectorial EVPs for cyclically antimonotone equilibrium problems, which extend and improve the previous results. By developing the original method proposed by Castellani and Giuli, we deduce a number of existence results(no matter scalar-valued case,or vector-valued case), when the feasible set is a sequentially compact topological space or a countably compact topological space. Finally, we propose a general coercivity condition. Combining the general coercivity condition and the obtained existence results with compactness conditions, we obtain several existence results for equilibrium problems in noncompact settings.

High-order maximum-principle-preserving and positivity-preserving weighted compact nonlinear schemes for hyperbolic conservation laws

In this paper,the maximum-principle-preserving(MPP)and positivitypreserving(PP)flux limiting technique will be generalized to a class of high-order weighted compact nonlinear schemes(WCNSs)for scalar conservation laws and the compressible Euler systems in both one and two dimensions.The main idea of the present method is to rewrite the scheme in a conservative form,and then define the local limiting parameters via case-by-case discussion.Smooth test problems are presented to demonstrate that the proposed MPP/PP WCNSs incorporating a third-order Runge-Kutta method can attain the desired order of accuracy.Other test problems with strong shocks and high pressure and density ratios are also conducted to testify the performance of the schemes.

Application of annexation principle to the study of thermodynamic properties of Ag-Bi-In metallic melts

Based on the measured activities, the phase diagrams and the annexation principle, the calculating models of mass action concentrations for Ag-Bi and Ag-Bi-In melts have been formulated. The calculated results agree with practice and obey the mass action law, showing that the models formulated can reflect the structural characteristics of both melts. Meanwhile, it confirms that annexation principle is applicable to the Ag-Bi-In metallic melts. The melts involving eulectic which give rise to phase separation, and in which activities exhibit positive deviation from Raoult's law is the basic cause of melts transforming from homogeneous to heterogeneous ones.

Application of annexation principle of thermodynamic property of In-Pb-Sb and In-Bi-Pb melts

Based on the principle of annexation and phase diagrams, the structural units of In Pb Sb and In Bi Pb melts were determined, and their calculating models of mass action concentrations were formulated. Calculated results agree well with practical values, which in turn show that the models deduced can reflect the structural realities of corresponding melts and the principle of annexation is applicable not only to some binary metallic melts, but also to ternary metallic melts.

Application of annexation principle to the study of thermodynamic properties of Ag-Bi-In metallic melts

Based on the measured activities,the phase diagrams and the annexation principle,the calculating models of mass action concentrations for Ag-Bi and Ag-Bi-In melts have been formulated.The calculated results agree with practice and obey the mass action law,showing that the models formulated can reflect the structural characteristics of both melts.Meanwhile,it confirms that annexation principle is applicable to the Ag-Bi-In metallic melts.The melts involving eutectic which give rise to phase separation,and in which activcities exhibit positive deviation from Raoult's law is the basic cause of melts transforming from homogeneous to heterogeneous ones.

基于STM32的便携式有毒气体检测仪设计

基于STM32设计一种便携式有毒有害气体检测仪,选用电化学原理气体传感器、低功耗高性能微控制器STM32及功能模块实现对有毒有害气体的浓度检测。文中详细介绍便携式有毒气体检测仪的工作原理,并对电化学气体传感器信号调理电路、控制电路、存储电路和功能软件进行设计。实验结果表明,所设计的气体检测仪具有体积小、功耗低、使用便捷、响应快速、检测精度高等优点,可广泛应用于有毒有害化学品的生产、贮运等各类场景。

一类与Klein-Gordon-Maxwell问题有关的方程组的基态解的存在性

该文利用临界点理论、变分法以及集中紧性原理等理论方法,研究如下一类非线性方程组的基态解的存在性.{−Δu+(m+2ωϕ)u=A(x)|u|^(p−2)u,−Δϕ+λϕ=ωu^(2),lim|_(x|→∞)u(x)=0,lim_(|x|→∞)ϕ(x)=0.其中u∈H^(1)(R^(3)),ϕ∈H^(1)(R^(3)),λ>0,m与ω均为正常数.如果A(x)是正常数,当$4时,上述问题存在基态解(u,ϕ);如果A(x)是非常值函数,当$4时,在适当的情况下上述问题存在基态解(u,ϕ).

POSITIVE SOLUTIONS WITH HIGH ENERGY FOR FRACTIONAL SCHRODINGER EQUATIONS

In this paper, we study the Schrodinger equations (-△)^(s)u + V(x)u = a(x)|u|^(p-2)u + b(x)|u|^(q-2)u, x∈R^(N),where 0 < s < 1, 2 < q < p < 2_(s)^(*), 2_(s)^(*) is the fractional Sobolev critical exponent. Under suitable assumptions on V, a and b for which there may be no ground state solution, the existence of positive solutions are obtained via variational methods.

黄河含沙量变化过程预报方法研究

含沙量预报能够为黄河流域生态保护和高质量发展提供技术支持与决策信息。本研究对现有的含沙量预报方法进行总结分析后发现,系统响应函数模型的预报精度较高且易于运行,水沙动力学模型的水沙运动机理性较强。通过结合水文和水力学方法,在不同水沙运动机理条件下构建了基于不平衡输沙原理、马斯京根演算、多来多排理论的3种系统响应函数模型。在黄河潼关站的应用结果表明,系统响应函数模型的物理运动机制越高,预报精度也越高,不平衡输沙原理系统响应函数模型可以较好地描绘汇流区的水沙输移特征,预报效果最优。