二维周期系数线性微分方程的特征指数

给出利用系数直接判定二维周期系数线性微分方程特征指数符号的若干结论．     

双驱动电动换能器电磁场和声-结构耦合场分析

电动换能器的设计涉及电磁场和声-结构耦合问题,本文利用COMSOL多物理场分析软件提供的该两种分析模块进行组合,以电磁理论为基础推导出了适合COMSOL数值计算的公式,把两种耦合场的分析结合起来,利用电磁场分析过程计算所需要变量,代入声-结构耦合场进行分析,得到声场分布情况。文章也大致介绍了COMSOL的有限元建模和该两种模块的使用方法。本文对电动换能器结构如何优化不做讨论。     

用近红外无损肌氧及运动心率检测技术评定100 m极量强度运动对心脏冲击影响

利用连续双波长近红外光技术测量肌肉中血红蛋白含氧量的变化情况,同时应用运动心率无线实时采集设备,设计了检测实时肌肉组织血氧含量和瞬时心率实验方案,对6名健康男性进行了100 m跑同步实测实验。实验表明,肌肉组织氧合血红蛋白浓度在100 m跑结束后继续降低,达到最低值的时刻滞后于运动结束时刻的时间为(6.65±1.10)s;心率则在运动结束后继续上升,达到最高值的时刻滞后于运动结束时刻的时间为(8.00±1.57)s。这些结果显示了双波长近红外光组织氧测试技术和运动心率无线实时采集系统能够正确检测极量强度运动时的血氧参数和心率,揭示了极量强度运动过程中肌肉中氧运输与消耗的过程及其与心率之间的动力学特征。     

Crossing disciplines ‐ A view on two‐dimensional optical spectroscopy

Recent interest in the role of quantum mechanics in the primary events of photosynthetic energy transfer has led to a convergence of nonlinear optical spectroscopy, condensed matter and quantum physics on the topic of energy‐transfer dynamics in pigment‐protein complexes. The convergence of these communities has unveiled a mismatch between the background and terminology of the respective fields. To make connections, a pedagogical guide to understanding the basics of two‐dimensional spectra is provided aimed at researchers with a background in quantum mechanics and condensed matter.     

Formation of intermediate coupling optical polarons and bipolarons in two-dimensional systems

The formation of the optical polaron and bipolaron in two-dimensional (2D) systems is studied in the intermediate electron–phonon coupling regime. The total energies of the 2D polaron and bipolaron are calculated by using the Buimistrov–Pekar method of canonical transformations. The obtained results are compared with other existing results obtained by using the Feynman path integral method and the modified Lee–Low–Pines unitary transformation method. It is shown that the electron–phonon correlation significantly reduces the total energy of the 2D polaron in comparison with the energy of the strong coupling (adiabatic) polaron. It is found that the polaron formation in 2D systems is possible when the electron–phonon coupling constant α is greater than the critical value ${\alpha }_c?2.94$, which is much lower than a critical value of the electron–phonon coupling constant α in three-dimensional (3D) systems. The critical values of the Fröhlich coupling constant α and the ratio $\eta ={\epsilon }_{\infty }/{\epsilon }_0$ (where ${\epsilon }_{\infty }$ and ${\epsilon }_0$ are the high frequency and static dielectric constants, respectively), which determine the bipolaron stability region in 2D systems, are calculated numerically. It is interesting for application to the layered cuprate superconductors that the (bi)polarons are formed more easily in quasi-2D regions than in the bulk. It is argued that the high-$T_c$ cuprate superconductivity can exist above the bulk superconducting transition temperature $T_c$ as the persisting superfluidity of polaronic (bosonic) Cooper pairs and large bipolarons at quasi-2D grain boundaries or in the CuO₂ layers above $T_c$.     

满足互补原理的半单复合模型

本文系统分析了SU(N)×SO(M)半单超色群的手征三前子模型.我们发现:SU(3)×SO(5)模型满足互补原理要求;由′tHooft方程及Bars条件可以给出三代夸克、轻子谱;超色群G_(MC)和规范色味子群G_(CF)都是渐近自由的,因此可以构造出具有低的超色禁闭标度A_(MC)的现实模型.我们还发现,本模型中存在二个超色标度.在这两个标度之间,模型类似于费米——玻色模型,这可以简化前子的动力学.     

二阶线性中立型微分差分方程非振动解的类型与判别

本文讨论了二阶线性中立型微分差分方程d~2/dt~2[x(t)-cx(t-τ)]+px(t-σ)=0的非振动解的所有类型及其判别。     

二级属性文法的设计

本文给出一个将文法 G 划分为二级文法的算法,并讨论二种构造二级属性文法的方法,这是二级属性计算器乃至整个编译程序自动生成的基础.     

柴油机供油系统中的油—汽两相流及对不规则喷射产生的影响

本文阐明了柴油机供油系统中油—汽两相流与不规则喷射的内在联系．分析了不规则喷射产生的机理，并指出在高速小负荷工况下，供油系统中的汽泡是产生不规则喷射的主要原因．