投资内生化的房地产投入占用产出局部闭模型及其应用

房地产在国民经济中占据特殊地位,为全面反映房地产与国民经济间的相互联系和促进关系,设计和构造了房地产投入占用产出表.分析表中数据可知,房地产发展对国民经济的主要影响与其他生产部门不同,主要通过增加企业毛盈余和政府收入进而拉动投资增长,最终实现经济增长.鉴于传统投入产出模型不能对此进行有效刻画,提出新的将投资内生化的投入产出局部闭模型.应用模型测算房地产对经济的拉动效应,得出的测算结果与传统模型相比明显偏大.     

CUPT2019循环摆研究

2019年CUPT第14题"循环摆"描述了一个在生活中常见却物理原理深刻的现象.所谓循环,指的能够旋转一周以上,约定轻物体绕杆旋转一圈以上,就形成了循环摆.实验中观察循环摆的轨迹,发现其必然会过渡到渐开线.利用拉格朗日方程可得描述轻物运动的非线性常微分方程组,据此方程组分析过渡到渐开线时刻的各物理量的变化规律、确定形成...     

X射线TICT在复合材料工件检测中的射束硬化拟合校正研究

X射线TICT中,X射线透射物质时,发生了能谱硬化现象。使图像重建时出现伪影。因此必须进行修正。文中对X射线硬化现象进行了分析,探讨了X射线TICT在检测复合材料工件中, X射线射束和与透射厚度的关系, 并根据Beer定律和X射线与物质作用的特点, 通过获取X射线射束和数据,首先拟合出射束和与透射厚度的关系式, 然后推导出X射线射束和校正为单色射线射束和的等效厚度与透射厚度的关系及其等效方法, 最终得出X射线TICT在检测复合材料工件中X射线等效单色射线的衰减系数的射束硬化拟合值, 再对此衰减系数拟合值进行卷积反投影重构, 即可有效消除X射线TICT在检测复合材料工件中射束硬化造成的影响。     

简单浸渍法制备纳米CuO/TiO2及其光催化剂活性

以Cu(NO₃)₂·3H₂O和P25为前躯体,通过简单浸渍法制备了CuO/TiO₂光催化剂,利用N₂物理吸附、XRD、TEM、UV-vis漫反射光谱分析了催化剂的结构特性。研究了Cu组分的负载量、催化剂在反应液中的分散量、催化剂焙烧温度、反应液中甲醇浓度对CuO/TiO₂光催化反应产氢活性的影响,并考察了催化剂的稳定性,提出了该体系光催化反应的机理。结果表明,Cu的适宜负载量为2.0%~7.5%(质量分数),在Cu质量分数2.0%、催化剂焙烧温度350℃、甲醇的体积浓度为10%、催化剂分散量为1.0 g/L时,产氢活性可达到1 022 μmol/(h·g),并且该催化剂具有较好的稳定性。     

CdTe量子点-罗丹明6G荧光共振能量转移体系的构建及其应用研究

采用巯基化合物修饰的CdTe量子点构建了量子点(供体)-罗丹明6G(受体)荧光共振能量转移体系, 研究了CdTe量子点与牛血清白蛋白(BSA)的相互作用. 结果表明, CdTe量子点与BSA相互作用后提高了CdTe量子点-罗丹明6G 体系的荧光共振能量转移(FRET)效率, 减小了CdTe量子点和罗丹明6G分子间的距离(r), 证实BSA是通过其色氨酸(Trp)残基与CdTe量子点表面金属发生配位作用而直接结合到量子点表面的.     

A new traffic model with the consideration of coupling effect with two lanes

This paper introduces a new two-lane high-order continuum model by embedding the two delay time scales continuum traffic model presented by Xue (2003 Phys. Rev. E 68 066123) into the multi-lane model proposed by Daganzo (1997 Transpn. Res. B 31 83) with the consideration of the coupling effect between the vehicles of two lanes in instantaneous traffic situation and lane-change effect. In the novel model, the coupling effect of two lanes and phenomena of lane change, which were not discussed in Daganzo's model and Xue's model, are taken into account. Numerical simulation shows that it is in accordance with real traffic flow. This obviously indicates that the new phenomenon and behaviour are analogous results as single lane presented by Xue, and the proposed model is more reasonable on two lanes. Furthermore, the generation rate between two lanes is also investigated. The results show that the formation and diffusion of traffic shock wave can be better simulated on two lanes.     

Multiple car-following model of traffic flow and numerical simulation

On the basis of the full velocity difference (FVD) model, an improved multiple car-following (MCF) model is proposed by taking into account multiple information inputs from preceding vehicles. The linear stability condition of the model is obtained by using the linear stability theory. Through nonlinear analysis, a modified Korteweg-de Vries equation is constructed and solved. The traffic jam can thus be described by the kink--antikink soliton solution for the mKdV equation. The improvement of this new model over the previous ones lies in the fact that it not only theoretically retains many strong points of the previous ones, but also performs more realistically than others in the dynamical evolution of congestion. Furthermore, numerical simulation of traffic dynamics shows that the proposed model can avoid the disadvantage of negative velocity that occurs at small sensitivity coefficients λ in the FVD model by adjusting the information on the multiple leading vehicles. No collision occurs and no unrealistic deceleration appears in the improved model.     

A viscous continuum traffic flow model with consideration of the coupling effect for two-lane freeways

In this paper, the viscous continuum traffic flow model for a single lane is extended to the traffic flow for two-lane freeways. The proposed model is a higher-order continuum model considering the coupling and lane changing effects of the vehicles on two adjacent lanes. It results from integrating the Taylor series expansion of the viscous continuum traffic flow model proposed by Ge (2006 Physica A 371 667) into the multi-lane model presented by Daganzo (1997 Transpn. Res. B 31 83). Our proposed model may be used to describe non-anisotropic behaviour because of lane changing in multi-lane traffic. A linear stability analysis is given and the neutral stability condition is obtained. Also, issues related to lane changing, shock waves and rarefaction waves, local clustering and phase transition are investigated through a simulation experiment. The simulation results show that the proposed model is capable of explaining some particular traffic phenomena commonly observable in real world traffic flow.     

龙舟挂饰

<正>拼贴剪,折卷插,小手指上开出花。巧巧手,大家有,我有创意我最牛!准备材料和工具：珠光纸、彩色卡纸、牙膏盒、扭扭棒、毛球、牙签、丝带、双面胶、刀、圆规、彩笔制作步骤第一步在珠光纸背面画若干个直径为3 cm的圆,并把它们剪下来。     

缤纷花束

<正>拼贴剪,折卷插,小手指上开出花。巧巧手,大家有,我有创意我最牛！准备材料和工具：彩纸、包装纸、细铁丝、胶带、双面胶、胶水、圆规、直尺、剪刀制作步骤第一步取一张直径为2.2 cm的黄色圆形彩纸,作为花蕊;将六张直径为2.5 cm的浅黄色圆形彩纸紧凑地粘在一起,作内层花瓣;再将六张直径为3 cm的橘色圆形彩纸粘成圆环状,作外层花瓣。