Schrödinger方程的连续时空有限元方法

本文讨论Schr?dinger方程的连续时空有限元方法,通过引入相应的时空投影算子,利用实部虚部分离技巧,得到了变量u在时间节点处的L²范数,以及u和u_t的全局L²(H¹)和L²(L²)范数意义下的最优误差估计结果.该文的结论对进一步探索和设计Schr?dinger方程的数值算法是有益的.     

A-P-S组合策略的多重绩效及其“褪色”效应分析

为了降低城市交通拥堵及空气污染程度,本文在现有研究的基础上引入罚款政策,利用系统动力学方法原理构建了机动车污染物减排管控模型。通过仿真和比较分析来探索空气污染收费(Air pollution charging fee,简称APCF)、罚款(penalty)和补贴(subsidy)政策(简称A-P-S策略)的作用效果。研究结果表明:一方面,组合策略具有多重绩效,不但能够降低污染损失(经济-环境效益)、死亡人口的生命价值(社会-经济效益)、交通拥堵程度(社会效益)和机动车污染物总量(环境效益),而且能大大改善环境生态承载力(环境效益)和机动车非法出行增长量(社会安全绩效);另一方面,政策在实施过程中也会遇到一定的局限性,如初期的滞后性,后期的“褪色”效应和“反弹”效应,因此,从长期来看,需要及时调整组合方案。最后,根据仿真结果提出了相应的政策建议,进而为城市交通和环保等相关部门提供决策参考。     

基于累积前景理论和VIKOR的毕达哥拉斯犹豫模糊风险型多属性决策方法

针对属性权重未知,且属性值为毕达哥拉斯犹豫模糊数(PHFN)的风险型多属性决策问题,考虑到决策者的有限理性行为,提出基于累积前景理论(CPT)和多准则妥协优化解(VIKOR)的决策方法。首先,定义PHFN的分散率,并构建优化模型确定属性权重。其次,将CPT融入PHFN环境,定义PHFN的价值函数,并结合决策权重函数计算方案在各属性下的综合前景值。进一步,构建综合前景值矩阵,在此基础上运用VIKOR法确定方案排序。最后,通过风险投资项目选择的应用案例说明所提方法是可行、有效的。     

中国数字经济发展水平:时空特征、动态演化及影响因素

基于构建的数字经济发展水平评价指标体系与2010~2018年全国30个省市(除西藏、港澳台)的面板数据,对中国数字经济发展水平的时空特征、动态演化与区域差异原因进行探究。研究发现:全国及三大区域的数字经济发展水平均呈现稳步上升态势,并伴有明显的空间相关性、空间集聚性和区域差异性,且东部相较于中西部区域内差异更大。数字经济发展速度动态演化显示,整体上中国各省市数字化发展水平变化速度状态表现为上升趋势,相较于中西部,东部拥有更大的速度变化状态。地区前期数字化基础、经济发展的一阶滞后、政府科技投入均会促进区域数字经济的发展,对外开放水平会抑制数字经济发展,地区规模对数字经济的影响表现为非线性。此外,不同线性影响因素在不同区域内对数字经济发展水平具有不同的影响力。     

基于前景理论的药品质量安全监管演化博弈分析

现有药品质量安全监管的相关研究多从理性假设出发探讨政府与企业的互动机理,鲜有考虑企业质量安全意识的有限理性,导致模型对现实的解释能力不足。运用前景理论,通过价值函数和权重函数构建演化博弈的收益前景矩阵,研究了政府和药品生产企业的博弈过程,得到了影响企业质量安全意识的约束条件及因素。同时,研究了上市许可持有人质量激励、惩罚机制对药品生产企业质量安全意识的影响。研究结果表明:过度自信、风险偏好等是影响企业质量安全意识的重要因素;上市许可持有人的质量激励与惩罚能否发挥作用取决于企业的风险态度;在质量激励、惩罚条件下,上市许可持有人需加大监督或惩罚力度来改善企业的质量安全意识。     

Analogues of hadwiger's theorem in space ℝ n —Sufficient conditions for a convex domain to enclose another

We estimate the kinematic measure of one convex domain moving to another under the groupG of rigid motions in ⁿ . We first estimate the kinematic formula for the total scalar curvature D ₀gD ₁ Rdv of then–2 dimensional intersection submanifold D ₀gD ₁. Then we use Chern and Yen's kinematic fundamental formula and our integral inequality to obtain a sufficient condition for one convex domain to contain another in ⁿ (4). Forn=4, we directly obtain another sufficient condition in ⁴.     

A global pinching theorem for compact surfaces inS 3 with constant mean curvature

LetM be a compact minimal surface inS ³. Y. J. Hsu^[5] proved that if S₂22, thenM is either the equatorial sphere or the Clifford torus, whereS is the square of the length of the second fundamental form ofM, ·₂ denotes theL ²-norm onM. In this paper, we generalize Hsu's result to any compact surfaces inS ³ with constant mean curvature.Supported by NSFH.     

Structural characterization of a novel self-assembly heterohexanuclear complex: [Ni2Ag4(μ-dppm)4(pymt)6](SbF6)2 · 2DMF · H2O

A novel heterohexanuclear complex [Ni₂Ag₄(μ-dppm)₄(pymt)₆](SbF ₆)₂ · 2DMF · H₂O (1), was synthesized by self-assembly with [Ag₂(μ-dppm)₂(MeCN)₂](SbF₆) ₂ and [Et₄N][Ni(pymt)₃] (dppm = bis(diphenylphosphino)methane, pymt = pyrimidine-2-thiolate) as components and characterized by IR spectra, elemental analysis, ¹H-NMR spectrum, ³¹P-NMR spectrum and Visible-Ultraviolet spectrum. Structure of the complex was determined by X-ray analysis.     

Kilogram-scale synthesis of carbon quantum dots for hydrogen evolution,sensing and bioimaging

A facile, low-cost, green, kilogram-scale synthesis of high quality CQDs were synthesized. The throughput of CQDs is 1.4975 kg in one pot and the as-prepared CQDs have a highly crystalline hexagonal structure with remarkable solubility, stability, and biocompatibility. It showed outstanding electrocatalytic activity, Fe³⁺ sensitivity and good biocompatibility.     

Molar volumes and viscosities of LiClO4 and LiBr in propylene carbonate + 1,2-dimethoxyethane mixed solvents at 298.15 K

The standard partial molar volumes, viscosity B-coefficients and activation free energies of lithium salts (LiClO₄ and LiBr) in propylene carbonate (PC) with 1,2-dimethoxyethane (DME) mixed solvents have been determined as a function of the mole fraction of DME at 298.15 K from precise density and viscosity measurements. The values studied are all positive and decrease monotonously with addition of DME in the PC, which indicates that nature of the solvents plays an important role. The effects are discussed in terms of preferential solvation and packing effect in the solvation shell and electrostriction. The differences between ClO₄⁻ and Br⁻ have also been discussed.