Bosonic Hofstadter butterflies in the presence of phonon modes

We have investigated the influence of lattice sites vibrations on bosonic Hofstadter’s butterfly (HB) spectrum for the case of conventional square lattice. Only the pair of specific phonon modes with opposite quasimomenta has been taken into account. The study has shown that HB-type spectra can be substantially modified by the presence of phonons, depending on the ratios of such parameters of the system as site-to-site transition amplitudes, particle-phonon interaction constant, and characteristic vibration frequency.

Raman Spectroscopic Characteristics of Zeolite Group Minerals

In this work, Raman spectroscopic experiments are conducted on zeolites, including a total of 33 varieties and seven groups with different secondary structural frameworks, for which characteristic vibration modes are studied. Most of the zeolites show prominent Raman peaks in the spectral range between 200–1200 cm−1. Different groups of zeolites can be recognized by differences in the wavenumbers of the T-O-T (T = Si and Al, O = oxygen) modes in the range 379–538 cm−1, the M-O (M = metal,) modes in the range 250–360 cm−1 and the T-O bending modes in the range 530–575 cm−1. All zeolites show characteristic Raman peaks in the range 379–529 cm−1, except for natrolite group (fibrous) zeolites, which are characterized by T-O-T modes in the 433–447 cm−1 range and T-O bending modes in the 528–538 cm−1 range. The analcime group (with singly connected four-ring chains) zeolites show T-O-T modes in the 379–392 cm−1 and 475–497 cm−1 ranges. The gismondine group (with doubly connected four-ring chains) zeolites have T-O-T modes in the 391–432 cm−1 and 463–497 cm−1 ranges. The chabazite group (with a six-cyclic ring) zeolites are characterized by M-O modes in the 320–340 cm−1 range and T-O-T modes in the 477–509 cm−1 range. The Raman modes of mordenite group zeolites (397–410 cm−1 and 470–529 cm−1) overlap with those of heulandite group zeolites (402–416 cm−1 and 480–500 cm−1). Moreover, the mordenite group has a characteristic peak in the 502–529 cm−1 range, and an additional peak in the 800–965 cm−1 range. Another recognizable peak for the heulandite group is in the 612–620 cm−1 range. The unknown zeolites (cowlesite) have unique characteristic peaks at 534 cm−1, which can aid in the verification of their identity.

Идентификация продуктов реакции комплексов железа по колебательному спектру на примере гидроксокатиона железа [Fe(OH)-=SUB=-2-=/SUB=-(H-=SUB=-2-=/SUB=-O)-=SUB=-2-=/SUB=-]-=SUP=-+-=/SUP=- в водной среде

The change in the vibrational spectrum of iron hydroxocation [Fe(OH)2(H2O)2]+ in the course of its interaction with peroxynitrite [NO–О2]- in an aqueous medium described by the PCM-SMD model was investigated in order to identify the reaction products, primarily nitrogen dioxide. The quantum-chemical calculation of the complex by the CASSCF method is identical to that previously used in the description of reactions in the active center of the tubercular bacillus M. tuberculosis (trHbN). The reaction products in these processes are compared, and the most characteristic vibration frequency is found, which makes it possible to establish the appearance of nitrogen dioxide. The energetic effect in the reverse process, the capture of nitrogen dioxide by the iron complex, has been estimated.

The Dynamic State of a Pseudo-Crystalline Structure of B42 Molecules

In this paper, we have developed a mathematical model of the dynamics of molecular structures arising from an approach using B42 molecules. The model is based on equations that determine the motion of the centers of mass of the molecules in question, and equations for the projections of the moments of quantities of motion of these particles on the axes associated with them. The thermal motions of boron atoms within each individual molecule are calculated using a bond-ordered potential. The intermolecular interactions of atoms have a potential that appears to coincide with that of free atoms. However, the interaction parameters differ. The obtained columns of molecular disks for B42 are stable structures. We determine the characteristic vibration amplitudes and rotation frequency of the molecules in question.

Automatic regime detection for Rotor Track and Balance using vibration only sensor data

ABSTRACTRotor Track and Balance (RTB) is an important part of regular helicopter maintenance. The ability to perform this service assessment during normal operations, rather than with a series of explicit RTB flights, would greatly reduce the time the vehicle is non-operational and the maintenance costs associated with these flights and adjustments. This paper presents a novel methodology for identifying the RTB-related flight regimes, using a minimal number of vibration signals and comparing these to repeatable and stable characteristic vibration profiles. The technique is stable, with an 81% success in correct identification of the flight regime, when applied to a whole flight with a number of unknown regime events. The method can be run in real time, making it an effective way of identifying periods of flight that are suitable for RTB measurements. A new technique for visually representing any real-time flight signal, such as vibration, is also presented.

An Approximate Estimation Approach of Fault Size for Spalled Ball Bearing in Induction Motor by Tracking Multiple Vibration Frequencies in Current

Fault size estimation is of great importance to bearing performance degradation assessment and life prediction. Until now, fault size estimation has generally been based on acoustic emission signals or vibration signals; an approach based on current signals has not yet been mentioned. In the present research, an approximate estimation approach based on current is introduced. The proposed approach is easy to implement for existing inverter-driven induction motors without complicated calculations and additional sensors, immune to external disturbances, and suitable for harsh conditions. Firstly, a feature transmission route from spall, to Hertzian forces, and then to friction torque is simulated based on a spall model and dynamic model of the bearing. Based on simulated results, the relation between spall size and the multiple characteristic vibration frequencies in friction torque is revealed. Secondly, the multiple characteristic vibration frequencies modulated in the current is investigated. Analysis results show that those frequencies modulated in the current are independent of each other, without spectrum overlap. Thirdly, to address the issue of which fault features modulated in the current are very weak, a fault-feature-highlighting approach based on reduced voltage frequency ratio is proposed. Finally, experimental tests were conducted. The obtained results validate that the proposed approach is feasible and effective for spall size estimation.

Modeling and Calculating Vibration Characteristic of Car Body Assembled and Manufactured in Vietnam

In recently years, Automotive industry in Vietnam is a fast growing sector, mainly reliant on domestic produces, assembly and sales. There are some details of cars that have been modeled, calculated to research and fabricate. Body vibration of the vehicles is one of the criteria to evaluate quality in the process of manufacturing and assembling automobiles. There are so many factors affecting on vibration of vehicles, in that body structure is one of the main causes. Up to now, automobiles manufactured and assembled in Vietnam have not yet had specific evaluations and standards on vibration. Determination of characteristic body vibration is a main part to reduce sound and vibration. In this paper, the modelling and calculating the body’s characteristic vibration of cars manufactured, assembled in Vietnam was researched. The body structure is designed by 3D model using commercial Catia Software. The model was transformed from Catia software to Hypermesh software, using finite element method to simulate. The calculation results of 25 measurement characteristic vibrations whose frequency is in range of 22.77 Hz to 97.21 Hz. The results are shown that, characteristic vibration of state 1 and 2 significantly influence the noise of the body. This is also the basis for optimal analysis of the body structure to control the vibration and noise of automobiles.

Cocrystal Assembled by Pyrene Derivative and 1,4-Diiodotetrafluorobenzene via a C=O···I Halogen Bond

Cocrystal formation is a strategy used to modify the solid-state properties of a given molecule. In this study, a new cocrystal assembled by 1,4-Diiodotetrafluorobenzene (1,4-DITFB) and a pyrene derivative, 1-acetyl-3-phenyl-5-(1-pyrenyl)-pyrazoline (APPP), was synthesized. Due to the twisted structure of APPP, the crystal structure is greatly different with some large π-conjugated compounds, which exhibits edge-to-face π-stacked arrangement between 1,4-DITFB and pyrene rings, rather than the face-to-face π-stacked arrangement. Hirshfeld surface analysis and the shift of characteristic vibration band of the carbonyl group in FT-IR spectroscopy suggest the formation of a C=O···I halogen bond.