纯电动汽车超低温热泵型空调系统特性模拟研究

针对低温工况下电动汽车普通热泵空调系统压缩机排气温度高,系统制热性能衰减严重,甚至无法正常工作等问题,设计了一种混气型纯电动汽车热泵空调系统。基于热力学第一定律和各部件之间的耦合特性建立该系统的数学模型,用该模型对系统的主要性能参数进行模拟计算,与实验结果相比具有较好的吻合性。并对模拟结果进行研究分析,从分析结果可以看出:该系统能够有效的解决非混气型电动汽车热泵系统低温工况下排气温度过高和制热性能衰减等问题。     

BP神经网络模拟冰盘管蓄冷过程特性的可行性研究

文中基于BP神经网络方法对冰盘管蓄冷系统的整个蓄冷过程中的蓄冷动态特性参数进行模拟研究,根据实验研究数据对所建的BP神经网络进行网络训练,进而通过预测试验对预测网络进行检验。结果表明:利用BP神经网络方法对整个蓄冷过程中的蓄冷动态特性参数进行模拟的精确度明显高于传统模拟方法,可使研究者更全面、更精确地了解和掌握了蓄冷过程中蓄冷动态特性参数的变化情况,为设计和优化直接蒸发式冰盘管蓄冰系统提供了理论依据。     

MOVING NONLINEAR LOCALIZED MODES FOR ONE-DIMENSIONAL KLEIN－GORDON DIATOMIC LATTICE

We study analytically the moving nonlinear localized vibrational modes (discrete breathers) for a one-dimensional Klein－Gordon diatomic lattice in the whole ω(q) plane of the system by means of a semi- discrete approximation, in which the carrier wave of the modes is treated explicitly while the envelope is described in the continuum approximation. We find that both pulse and kink envelope moving modes for this lattice system can occur with certain carrier wave vectors and vibrational frequencies in separate regions of the ω(q) plane. However, the kink envelope moving modes have not been reported previously for this lattice system.     

Photon-assisted electronic structure and transport for a quantum dot

This paper investigates theoretically the electronic structure and transport of a two-level quantum dot irradiated under a strong laser field at low temperatures. Using the method of Keldysh equation of motion for nonequilibrium Green functions, it examines the time-averaged density of states and conductance for the system with photon polarization parallel with and perpendicular to the tunnelling current direction respectively. It is demonstrated that, by analysing some numerical examples, more photon sidebands resonance states and multi- and single-photon transitions are found when diagonal matrix elements dominate the interaction, while the electronic transitions due to multiphoton absorption are more or less suppressed when off-diagonal interaction dominates.     

THz-field-induced electronic transmission step-structure for a quantum wire

We study theoretically the low-temperature electronic transport property of a straight quantum wire under the irradiation of a finite-range transversely polarized external terahertz (THz) electromagnetic (EM) field. Using the freeelectron model and the scattering matrix approach, we show an unusual behaviour of the electronic transmission of this system. A sharp step-structure appears in the electronic transmission probability as the EM field strength increases to a threshold value when a coherent EM field is applied. We demonstrate that this effect physically comes from the inelastic scattering of electrons with lateral photons through intersubband transitions.     

电动汽车空调涡旋压缩机低压补气特性模拟研究

为解决超低温工况下纯电动汽车普通热泵空调系统运行时,压缩机排气温度过高和制热性能衰减严重,甚至无法正常运行等问题,设计了一种低压混气型电动汽车热泵空调用涡旋式压缩机,在课题组前期研究的基础上建立低压混气型涡旋压缩机的数学模型,并用实验结果对模拟计算值进行验证。结果表明,模拟值与实验值最大误差小于5%,该模型能够较好地预测系统性能。     

制冷剂HCFC-124热力性质计算研究

采用已发表的热力性质数据,利用软件origin 8.0对R124部分热力性质基本公式进行拟合,拟合误差小于4.3%。利用拟合公式计算出的数据与已发表文献的实验数据作对比,结果表明,在额定工况下,高温热泵系统能满足工程的应用要求。     

气液双热源耦合换热器性能研究

设计了一种由管翅式换热器和套管式换热器耦合而成的气液双源耦合式换热器,该换热器可以实现一种介质同时与气态热源和液态热源进行同步耦合换热.对该换热器进行了详细的介绍,并对其耦合换热特性及该换热器在耦合热源热泵空调中应用时的制热工况进行了的性能测试.研究结果证明,使用该气液双热源耦合式换热器的耦合热源热泵空调系统,气液双热...     

关于切锥与切导数的等价命题

给出集值映射导数的若干等价命题,这有助于加深对集值映射的导数概念的理解,并给使用带来方便.     

Velocity modulation of electron transport through a ferromagnetic silicene junction

We address velocity-modulation control of electron wave propagation in a normal/ferromagnetic/normal silicene junc tion with local variation of Fermi velocity, where the properties of charge, valley, and spin transport through the junction ar investigated. By matching the wavefunctions at the normal-ferromagnetic interfaces, it is demonstrated that the variation of Fermi velocity in a small range can largely enhance the total conductance while keeping the current nearly fully valley and spin-polarized. Further, the variation of Fermi velocity in ferromagnetic silicene has significant influence on the valley and spin polarization, especially in the low-energy regime. It may drastically reduce the high polarizations, which can b realized by adjusting the local application of a gate voltage and exchange field on the junction.