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81.
V. N. Paimushin D. V. Tarlakovskii V. A. Firsov R. K. Gazizullin 《ZAMM - Journal of Applied Mathematics and Mechanics / Zeitschrift für Angewandte Mathematik und Mechanik》2020,100(3):e201900102
A refined statement of stationary dynamic acoustoelasticity problems of thin isotropic plates surrounded from both sides by acoustic media assumed to be perfect compressible fluids has been studed. The problem statement takes into account the energy dissipation in the material of the plate and fluid on the basis of the Kelvin-Voigt hysteresis model. The refinement of the fluid behavior is based on the assumption that the pressure increment is proportional not only to volumetric strain, but also to the rate of its volumetric strain. This assumption allows us to obtain the generalized Helmholtz wave equation by introducing Skudrzyk's complex sound velocity into consideration to take account of the energy dissipation. The motion equations of the plate are based on the classical Kirchhoff-Love model and are obtained in two versions. In the first version unsimplified three-dimensional wave equations are used to determine the aerohydrodynamic load acting on a plate. The second version is based on simplifying the equations of fluid motion by the introduction of the well-known hypothesis of plane reflection and emission of sound waves. On the basis of the derived equations, exact analytical solutions of two types of problems are obtained. The first type is related to the problem of free vibrations of a rectangular plate hinged around the contour when complex eigenfrequencies were defined. The second type is related to the problem of forced vibrations of the plate under the action of a flat mono-harmonic incident sound wave when sound transmission loss, the stress-strain state parameters of the plate as well as the laws of change in sound pressure in a fluid were determined. It is shown that correct and more meaningful solutions of acoustoelasticity problems of the considered class are possible only in case of describing the behavior of a fluid with unsimplified three-dimensional wave equations with consideration of the energy dissipation. 相似文献
82.
In the present study, the effect of vertical load, tire inflation pressure and soil moisture content on power loss in tire under controlled soil bin conditions were investigated. Also a finite element model of tire-soil interaction in order to achieve a suitable model for predicting power loss in tire was created. Increasing the vertical load on the tire had a noteworthy impact on increasing the tire contact volume with the soil, reducing the percentage of slip, and increasing the rolling resistance; although, reducing the load on the tire had the opposite effect. At a constant inflation pressure, by increasing the vertical load on the tire, the amount of power loss due to the rolling resistance and the total power loss in the tire increased. Increase in soil moisture content increased the power loss caused by slip. Increasing the inflation pressure at a constant vertical load, also increasing the soil moisture content, led to an increase in the power loss caused by rolling resistance, and increase total power loss. The obtained error for estimating power loss of rolling resistance and total power loss was satisfactory and confirmed the acceptability of the model for power loss estimation. 相似文献
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86.
Jutapol Jumpatam Bundit Putasaeng Narong Chanlek Prasit Thongbai 《Molecules (Basel, Switzerland)》2021,26(7)
The microstructure, dielectric response, and nonlinear current-voltage properties of Sr2+-doped CaCu3Ti4O12/CaTiO3 (CCTO/CTO) ceramic composites, which were prepared by a solid-state reaction method using a single step from the starting nominal composition of CCTO/CTO/xSrO, were investigated. The CCTO and CTO phases were detected in the X-ray diffraction patterns. The lattice parameter increased with increasing Sr2+ doping concentration. The phase compositions of CCTO and CTO were confirmed by energy-dispersive X-ray spectroscopy with elemental mapping in the sintered ceramics. It can be confirmed that most of the Sr2+ ions substituted into the CTO phase, while some minor portion substituted into the CCTO phase. Furthermore, small segregation of Cu-rich was observed along the grain boundaries. The dielectric permittivity of the CCTO/CTO composite slightly decreased by doping with Sr2+, while the loss tangent was greatly reduced. Furthermore, the dielectric properties in a high-temperature range of the Sr2+-doped CCTO/CTO ceramic composites can be improved. Interestingly, the nonlinear electrical properties of the Sr2+-doped CCTO/CTO ceramic composites were significantly enhanced. The improved dielectric and nonlinear electrical properties of the Sr2+-doped CCTO/CTO ceramic composites were explained by the enhancement of the electrical properties of the internal interfaces. 相似文献
87.
Yi-Chun Lin Yuan-Yung Lin Hsin-Chien Chen Chao-Yin Kuo Ai-Ho Liao Ying-Liang Chou Chia-Lien Hung Cheng-Ping Shih Chih-Hung Wang 《Molecules (Basel, Switzerland)》2021,26(12)
The application of insulin-like growth factor 1 (IGF-1) to the round window membrane (RWM) is an emerging treatment for inner ear diseases. RWM permeability is the key factor for efficient IGF-1 delivery. Ultrasound microbubbles (USMBs) can increase drug permeation through the RWM. In the present study, the enhancing effect of USMBs on the efficacy of IGF-1 application and the treatment effect of USMB-mediated IGF-1 delivery for noise-induced hearing loss (NIHL) were investigated. Forty-seven guinea pigs were assigned to three groups: the USM group, which received local application of recombinant human IGF-1 (rhIGF-1, 10 µg/µL) following application of USMBs to the RWM; the RWS group, which received IGF-1 application alone; and the saline-treated group. The perilymphatic concentration of rhIGF-1 in the USM group was 1.95- and 1.67- fold of that in the RWS group, 2 and 24 h after treatment, respectively. After 5 h of 118 dB SPL noise exposure, the USM group had the lowest threshold shift in auditory brainstem response, least loss of cochlear outer hair cells, and least reduction in the number of synaptic ribbons on postexposure day 28 among the three groups. The combination of USMB and IGF-1 led to a better therapeutic response to NIHL. Two hours after treatment, the USM group had significantly higher levels of Akt1 and Mapk3 gene expression than the other two groups. The most intense immunostaining for phosphor-AKT and phospho-ERK1/2 was detected in the cochlea in the USM group. These results suggested that USMB can be applied to enhance the efficacy of IGF-1 therapy in the treatment of inner ear diseases. 相似文献
88.
Ebselen is the leader of selenorganic compounds, and starting from its identification as mimetic of the key antioxidant enzyme glutathione peroxidase, several papers have appeared in literature claiming its biological activities. It was the subject of several clinical trials and it is currently in clinical evaluation for the treatment of COVID-19 patients. Given our interest in the synthesis and pharmacological evaluation of selenorganic derivatives with this review, we aimed to collect all the papers focused on the biological evaluation of ebselen and its close analogues, covering the timeline between 2016 and most of 2021. Our analysis evidences that, even if it lacks specificity when tested in vitro, being able to bind to every reactive cysteine, it proved to be always well tolerated in vivo, exerting no sign of toxicity whatever the administered doses. Besides, looking at the literature, we realized that no review article dealing with the synthetic approaches for the construction of the benzo[d][1,2]-selenazol-3(2H)-one scaffold is available; thus, a section of the present review article is completely devoted to this specific topic. 相似文献
89.
Tomasz Miroslaw 《ZAMM - Journal of Applied Mathematics and Mechanics / Zeitschrift für Angewandte Mathematik und Mechanik》2021,101(1)
Wheel construction and adhesion to the road decide on transport economy and safety. People are still developing wheel rims and tries to increase vehicle stability, reduce energy consumption and noise emissions. For many years designers have developed many models to describe the tire‐road phenomena. The models are created in a couple of ways, some tried to find the mathematical equation which follows the experiment resets, others tried to explain the phenomena itself. Some examples are presented in this paper. The brush Pacejca and LuGre models were developed to a new model to explain the process of vehicle force generation with longitudinal and lateral slips. When the wheel is propelled or braked, the force is transferred between rim and tire to the road by elastic blocks. Because of that, the difference of speed between the external part of the tire and the rim appears what results in tire longitudinal and lateral deformations. Based on Columbus friction model with Stribeck effect the model of force flow with tire deformation was presented for three models of friction. The two directional (lateral and longitudinal) slip and energy loses were worked out. The concept of the force flow model for dynamic processes modeling is presented. It refers to the force carried by the rotating part of the tire which loses the contact with a road. The friction force decreases and wheel has to accelerate until the new deformation compensates the “lost force.” Some examples of simulation results based on presented methods are shown and they seem to be consistent with other results from other accepted models. 相似文献
90.
Oleg?V.?MishechkinEmail author Richard?L.?Davis Li?Fan Dong?Lu Mahmoud?Fallahi 《Journal of Sol-Gel Science and Technology》2005,34(1):47-51
A passivation method for improving long-term stability of organic-inorganic sol–gel material is reported. The effect is observed in experiments with two different passivation materials: Teflon AF and SiO2. A regime of material curing prior to the passivation is found to strongly affect the optical loss. The degradation of waveguide loss with time due to moisture adsorption from the atmosphere is drastically suppressed by coating the material with a thin silica film. The results indicate a long-term optical loss below 0.3 dB/cm in coated waveguides, significantly smaller than that in uncoated waveguides. The mechanism of the loss reduction is described and experimentally confirmed. 相似文献