在滑动轴承转子系统中挤压油膜阻尼器的减振特性分析

研究了挤压油膜阻尼器在具有滑动轴承支承的非线性转子动力系统中的减振特性．首先分析了滑动轴承－转子非线性动力系统的稳定性及分岔行为．研究表明：在较大不平衡量作用下，系统易发生倍周期分岔、准周期分岔，失稳转速较低．然后分析了加入挤压油膜阻尼器后的滑动轴承－转子非线性动力系统的稳定性及分岔行为．分析表明：挤压油膜阻尼器的加入，有效地改变了系统的分岔行为，提高了失稳转速，特别是在较大不平衡量作用下，其效果更加明显     

Azimuthal Dipolar Rotor Arrays on Surfaces

A set of dipolar molecular rotor compounds was designed, synthesized and adsorbed as self-assembled 2D arrays on Ag(111) surfaces. The title molecules are constructed from three building blocks: (a) 4,8,12-trioxatriangulene (TOTA) platforms that are known to physisorb on metal surfaces such as Au(111) and Ag(111), (b) phenyl groups attached to the central carbon atom that function as pivot joints to reduce the barrier to rotation, (c) pyridine and pyridazine units as small dipolar units on top. Theoretical calculations and scanning tunneling microscopy (STM) investigations hint at the fact that the dipoles of neighboring rotors interact through space through pairs of energetically favorable head-to-tail arrangements.     

Give or Take: Effects of Electron-Accepting/-Withdrawing Groups in Red-Fluorescent BODIPY Molecular Rotors

Mapping microviscosity, temperature, and polarity in biosystems is an important capability that can aid in disease detection. This can be achieved using fluorescent sensors based on a green-emitting BODIPY group. However, red fluorescent sensors are desired for convenient imaging of biological samples. It is known that phenyl substituents in the β position of the BODIPY core can shift the fluorescence spectra to longer wavelengths. In this research, we report how electron-withdrawing (EWG) and -donating (EDG) groups can change the spectral and sensory properties of β-phenyl-substituted BODIPYs. We present a trifluoromethyl-substituted (EWG) conjugate with moderate temperature sensing properties and a methoxy-substituted (EDG) molecule that could be used as a lifetime-based polarity probe. In this study, we utilise experimental results of steady-state and time-resolved fluorescence, as well as quantum chemical calculations using density functional theory (DFT). We also explain how the energy barrier height (Ea) for non-radiative relaxation affects the probe’s sensitivity to temperature and viscosity and provide appropriate Ea ranges for the best possible sensitivity to viscosity and temperature.     

Chaotic motions of a rigid rotor in short journal bearings

In the present paper the conditions that give rise to chaotic motions in a rigid rotor on short journal bearings are investigated and determined. A suitable symmetry was given to the rotor, to the supporting system, to the acting system of forces and to the system of initial conditions, in order to restrict the motions of the rotor to translatory whirl. For an assigned distance between the supports, the ratio between the transverse and the polar mass moments of the rotor was selected conveniently small, with the aim of avoiding conical instability. Since the theoretical analysis of a system's chaotic motions can only be carried out by means of numerical investigation, the procedure here adopted by the authors consists of numerical integration of the rotor's equations of motion, with trial and error regarding the three parameters that characterise the theoretical model of the system: m, the half non-dimensional mass of the rotor, , the modified Sommerfeld number relating to the lubricated bearings, and , the dimensionless value of rotor unbalance. In the rotor's equations of motion, the forces due to the lubricating film are written under the assumption of isothermal and laminar flow in short bearings. The number of numerical trials needed to find the system's chaotic responses has been greatly reduced by recognition of the fact that chaotic motions become possible when the value of the dimensionless static eccentricity % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbnL2yY9% 2CVzgDGmvyUnhitvMCPzgarmWu51MyVXgaruWqVvNCPvMCG4uz3bqe% fqvATv2CG4uz3bIuV1wyUbqee0evGueE0jxyaibaieYlf9irVeeu0d% Xdh9vqqj-hEeeu0xXdbba9frFf0-OqFfea0dXdd9vqaq-JfrVkFHe9% pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr0-vqpWqaaeaabiGaciaaca% qabeaadaabauaaaOqaaiabew7aLnaaBaaaleaacaWGZbaabeaaaaa!4046!\[\varepsilon _s \] is greater than 0.4. In these conditions, non-periodic motions can be obtained even when rotor unbalance values are not particularly high (=0.05), whereas higher values (>0.4) make the rotor motion periodic and synchronous with the driving rotation. The present investigation has also identified the route that leads an assigned rotor to chaos when its angular speed is varied with prefixed values of the dimensionless unbalance . The theoretical results obtained have then been compared with experimental data. Both the theoretical and the experimental data have pointed out that in the circumstances investigated chaotic motions deserve more attention, from a technical point of view, than is normally ascribed to behaviours of this sort. This is mainly because such behaviours are usually considered of scarce practical significance owing to the typically bounded nature of chaotic evolution. The present analysis has shown that when the rotor exhibits chaotic motions, the centres of the journals describe orbits that alternate between small and large in an unpredictable and disordered manner. In these conditions the thickness of the lubricating film can assume values that are extremely low and such as to compromise the efficiency of the bearings, whereas the rotor is affected by inertia forces that are so high as to determine severe vibrations of the supports.Nomenclature C radial clearance of bearing (m) - D diameter of bearing (m) - e dimensional eccentricity of journal (m) - e _s value of e corresponding to the static position of the journal - E dimensional static unbalance of rotor (m) - f _x, f _y =F _x/(P), F _y/(P): non-dimensional components of fluid film force - F _x, F _y dimensional components of fluid film force (N) - g acceleration of gravity (m/s²) - L axial length of bearing (m) - m % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbnL2yY9% 2CVzgDGmvyUnhitvMCPzgarmWu51MyVXgaruWqVvNCPvMCG4uz3bqe% fqvATv2CG4uz3bIuV1wyUbqee0evGueE0jxyaibaieYlf9irVeeu0d% Xdh9vqqj-hEeeu0xXdbba9frFf0-OqFfea0dXdd9vqaq-JfrVkFHe9% pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr0-vqpWqaaeaabiGaciaaca% qabeaadaabauaaaOqaaiabg2da9maalaaabaGaeqyYdC3aaWbaaSqa% beaacaaIYaaaaaGcbaGaeqyYdC3aa0baaSqaaGabciaa-bdaaeaaca% WFYaaaaaaakiabg2da9maalaaabaGaeqyYdC3aaWbaaSqabeaacaaI% YaaaaOGaam4qaaqaaiabeo8aZjaadEgaaaaaaa!4C14!\[ = \frac{{\omega ^2 }}{{\omega _0^2 }} = \frac{{\omega ^2 C}}{{\sigma g}}\]: half non-dimensional mass of rotor - M half mass of rotor (kg) - n angular speed of rotor (in r.p.m.=60/2) - t time     

转杯速度与成纱质量关系的研究

本文探讨了国产转杯纺纱器的转杯速度与成纱质量的关系,采用经过优化的转杯、隔离盘和假捻盘进行纺纱。试验结果表明,随着转杯速度的提高,成纱质量基本上呈下降趋势。但在杯速为50000 r/min 左右时,成纱质量的几项主要指标最佳。这对于合理设计转杯速度具有一定的参考价值。     

一种新型结构的内外双转子感应电机

为了提高感应电机的运行性能,研究了一种具有内外双转子的新型结构的感应电机。电机采用励磁电抗较大的特殊铁芯和定子绕组形式。通过分析电机内部的电磁关系,计算了其特殊的磁场分布,推导出电机的数学模型,并对其进行了动态仿真。结果表明,电机具有良好的动态特性,特别是当电机极数较少（例如2极）时,绕组电阻和端部漏抗值都很小,而力能指标却较高。因此,推导出的电磁关系和数学模型适用于新型内外双转子感应节能电机的设计分析。     

Dipolar Rotors Orderly Aligned in Mesoporous Fluorinated Organosilica Architectures

New mesoporous covalent frameworks, based on hybrid fluorinated organosilicas, were prepared to realize a periodic architecture of fast molecular rotors containing dynamic dipoles in their structure. The mobile elements, designed on the basis of fluorinated p‐divinylbenzene moieties, were integrated into the robust covalent structure through siloxane bonds, and showed not only the rapid dynamics of the aromatic rings (ca. 10⁸ Hz at 325 K), as detected by solid‐state NMR spectroscopy, but also a dielectric response typical of a fast dipole reorientation under the stimuli of an applied electric field. Furthermore, the mesochannels are open and accessible to diffusing in gas molecules, and rotor mobility could be individually regulated by I₂ vapors. The iodine enters the channels of the periodic structure and reacts with the pivotal double bonds of the divinyl‐fluoro‐phenylene rotors, affecting their motion and the dielectric properties.     

传递矩阵－多项式法的改进及其应用

本文提出一种计算转子－滑动轴承－挤压油膜阻尼器转子系统的阻尼固有频率及稳定性的方法，即将传递矩奉多项式法改进后，应用于这类具有分叉结点的系统，直接得到系统的特征多项式，然后用Ｂａｉｒｓｔｏｗ－Ｎｅｗｔｏｎ僻因子法求出全部特征根。本方法具有占内存少、计算速度快、数值稳定等特点，文中对一转子模型进行了计算，其结果与实测基本相符。     

Dynamics of coupled systems

A survey in the form of a review of the author’s research results in the area of dynamics of coupled rotations and coupled systems is presented. The theorem on the existence of a trigger of the coupled singularities and the separatrix in the form of the number eight is presented with a few examples of coupled rotations of the simple systems with debalances. Also, a survey of models and dynamics of coupled systems composed of a number of deformable bodies (plates, beams or belts) with different properties of materials and discrete layer properties is presented and mathematically described. The constitutive stress–strain relations for materials of the coupled sandwich structure elements are presented for different properties: elastic, viscoelastic and creeping. The characteristic modes of the coupled system vibrations are obtained and analyzed for different kinds of materials and structure composition. The visualization of the characteristic numbers and modes and eigenamplitude forms are presented. Structural analysis of sandwich structure vibrations is done.     

下支承摩擦副相对滑动的垂直转子的动力行为

实际运行中垂直转子系统的下支承摩擦副之间存在相对滑动。为了了解这种相对滑动对转子系统动力行为的影响,建立了垂直转子动力学模型,并通过数值计算模拟了转子在稳态和非稳态时的振动特征。测量实际运行时垂直转子的振动特征,测量结果与理论分析结果吻合较好。这表明建立的动力学模型和采用的数值方法是有效的。分析结果表明:当摩擦力或油膜刚度增加时,系统的抗干扰能力随之提高;转速的升高使系统抗干扰能力减弱;摩擦力增加使系统低频进动频率升高;油膜刚度增加使系统低频进动频率降低。