在有限执行假设下对最优契约的扩展模型研究

本文运用违约保证金条款改进了代理人事前报酬契约；在契约有限执行的假设下，扩展了代理人的逆向选择模型，并运用扩展逆向选择模型分析了改进后的最优报酬契约。文章指出，改进后的最优报酬契约严格优于委托人为防范代理人违约而被迫采用的非负参与性约束条件下的最优报酬契约。     

Simple and robust digital holography for high-resolution imaging

Based on the point spread function of holographic system,the lateral resolution of digital holographic imaging system without any pre-magnification is studied.The expression of resolution limitation of holographic imaging system is thus presented.We investigate the possibilities to improve the lateral resolution.The simple experimental setup with an off-axis arrangement is built.By using a U.S.Air Force(USAF)test target as microscopic object,the recorded holograms are reconstructed digitally based on the principle of Fresnel diffraction.The lateral resolution of 2.76 μm without any pre-magnification is demonstrated experimentally,which matches the theoretical prediction well.     

Isospin effects of the Skyrme potential and the momentum dependent interaction at intermediate energy heavy ion collisions

We improve the isospin dependent quantum molecular dynamical model by including isospin effects in the Skyrme potential and the momentum dependent interaction to obtain an isospin dependent Skyrme potential and an isospin dependent momentum interaction. We investigate the isospin effects of Skyrme potential and momentum dependent interaction on the isospin fractionation ratio and the dynamical mechanism in intermediate energy heavy ion collisions. It is found that the isospin dependent Skyrme potential and the isospin dependent momentum interaction produce some important isospin effects in the isospin fractionation ratio.     

电子束入射改善托卡马克等离子体约束

 分析了电子束入射托卡马克等离子体表面后所发生的一系列物理过程,特别是电子束注入等离子体后在边界层形成平行电流和径向负电场,使等离子体由低约束模式向高约束模式,即L H模式转换中的作用。论证了当注入电子束的密度超过一定的阀值时,L H 模转换被触发。     

Emerging Theory,Materials, and Screening Methods: New Opportunities for Promoting Thermoelectric Performance

High‐performance thermoelectric materials have attracted immense interest due to the capability of directly converting thermal energy into electrical energy. The correlation and inherent complexity between the thermoelectric parameters pose serious challenges to improving the materials’ thermoelectric performance. Herein, the emerging novel theories in the field of thermoelectrics are summarized, such as the coherent phonon, nanophononic metamaterial, rattling effect, topological phonon, and topological electron. The impacts of these new concepts on thermoelectric performance are then reviewed. Finally, a number of promising thermoelectric materials such as one‐dimensional nanowires, two‐dimensional layered materials, and nanomesh structures are discussed. The advanced understanding of thermal and electrical transport properties in thermoelectric materials is presented herein, providing new opportunities for improving thermoelectric performance.     

A study on the distribution of adsorbed nanoparticles

We use Monte Carlo simulation to calculate the distributions of particles under adsorption force near planar and cylindrical surfaces,respectively.Both hard sphere interaction and repulsive Yukawa (screened coulomb) interaction are employed in our simulations.We study the influence of the inter-particle potentials.The difference between the MC simulation results and the analytical results of ideal gas model shows that the interaction between particles plays an important role in the density distribution under external fields.Moreover,the 2-dimensional constructions of particles close to the surface are studied and show relations of the interaction between particles.These results may indicate us how to improve the methods of building nanoparticle coatings and nano-scale patterns.     

A series of the solutions for the Heisenberg ferromagnetic spin chain equation

The Heisenberg ferromagnetic spin chain equation is investigated. By applying the improved F‐expansion method (Exp‐function method) and the Jacobi elliptic method, respectively, a series of exact solutions is constructed. The parametric conditions of the existence for the solutions are presented. These solutions comprise periodic wave solutions, doubly periodic wave solutions, and dark and bright soliton solutions, which are expressed in several different function forms, namely, Jacobi elliptic function, trigonometric function, hyperbolic function, and exponential function. The results illustrate that the Exp‐function method is a powerful symbolic algorithm to look for new solutions for the nonlinear evolution systems.     

PHOTOCONDUCTIVITY STUDY OF NEW POLYACETYLENE DERIVATIVES WITH DIFFERENT SUBSTITUENTS

The photoconductivities of a series of novel polyacetylene derivatives （PAs） serving as charge generation materials in the single-layered photoreceptors were investigated using photoinduced xerographic discharge technique. It was found that the substitution can improve the photosensitivity of PAs by increasing the conjugation of π electrons. When the substituent is itself photoconductive, the photoconductivity becomes even higher. It can be concluded from cyclic voltammetry that when the HOMO level of the polymer is closer to that of the charge transport material, the photoconduction performance will be better.     

Application of multi-phase particle swarm optimization technique to retrieve the particle size distribution

The multi-phase particle swarm optimization (MPPSO) technique is applied to retrieve the particle size distribution (PSD) under dependent model.Based on the Mie theory and the Lambert-Beer theory, three PSDs, i.e., the Rosin-Rammer (R-R) distribution, the normal distribution, and the logarithmic normal distribution, are estimated by MPPSO algorithm.The results confirm the potential of the proposed approach and show its effectiveness.It may provide a new technique to improve the accuracy and reliability of the PSD inverse calculation.     

低渗透油藏聚合物强化泡沫调剖剂

为改善某低渗透油田的水驱开发效果,开展了聚合物强化氮气泡沫调剖提高采收率研究.根据该油田的地质油藏条件,建立典型地质概念模型,地质模型能够比较完整地反映地层静态状况和井网条件.对聚合物强化泡沫调剖注采参数进行了优化设计.研究结果表明,聚合物强化氮气泡沫调剖最佳注采参数为:聚合物分子量为800万,聚合物浓度为1000mg/L,最佳泡沫剂浓度为0.25%(质量分数),气液比为1:1.