This study investigates acoustic impedance matching between a thermoacoustic Stirling heat engine and a branch liquid column, using multiple regenerators. We characterize acoustic impedances at both ...the engine and liquid column load ends using thermoacoustic theory, expressed as functions of frequency and temperature differences across regenerators. The intersection points of these functions indicate matched impedances, critical for evaluating the engine’s operating points. Notably, this study emphasizes the impact of a vibrating membrane on the system’s acoustic impedance, highlighting its significant role in modulating acoustic states and facilitating self-sustained oscillations. To verify our theoretical models, we conducted experiments with the proposed fluidyne engine under various liquid column volumes. The verifications confirmed our simple calibrations for characterizing a vibrating membrane clamped in the engine and the oscillating liquid columns. Significantly, the acoustic compliance and inertance effects respectively introduced by the membrane and liquid columns enable us to modulate the engine’s acoustic states. The proposed configuration is named a thermoacoustic Stirling fluidyne. This fluidyne, a heat engine that outputs work power using a liquid piston, achieves a markedly higher acoustic impedance than the pure gas case while maintaining traveling wave phasing for the regenerators.
•Introducing a flexible design in the fluidyne-style thermoacoustic Stirling engine.•Utilization of a vibrating membrane coupled with oscillating liquid columns for improved acoustic modulation.•Attainment of remarkably high acoustic impedance, while efficiently preserving the traveling wave phasing within regenerators.
In this paper we show the existence of non-negative solutions for a Kirchhoff type problem driven by a nonlocal integrodifferential operator, that is −M(‖u‖Z2)LKu=λf(x,u)+|u|2∗−2uin Ω,u=0in Rn∖Ω ...where LK is an integrodifferential operator with kernel K, Ω is a bounded subset of Rn, M and f are continuous functions, ‖⋅‖Z is a functional norm and 2∗ is a fractional Sobolev exponent.
The paper presents the results of research on the vibrating motion of a laboratory screen with a rectilinear (segmental) trajectory of vibrations during its start-up and braking. The investigations ...were carried out on a modernized stand equipped with a system of two vibrating motors applied in newer solutions of industrial screens, which are mounted directly on the riddle. The tests were carried out for three different frequencies using three-axis acceleration sensors. The analysed parameter was the increase in the amplitude of vibrations in transient states compared to the amplitude during the stable operation of the device. The maximum multiplication of the vibration amplitude of the classic drive system during start-up was 9.7 (mm/mm) in the vertical direction and 5.7 (mm/mm) for the new system. During braking, the maximum multiplication of the vibration amplitude of the classic drive system was 6.9 (mm/mm) vertically, while for the drive system with vibration motors, it was 11.4 (mm/mm). The absence of flexible couplings in the drive system reduces the damping of vibrations and increases the value of amplitude during the start-up and free braking of the machine. This does not have a major influence on the correct operation of the machine in a steady state. However, the use of the new drive system resulted in a significant reduction in power demand and shortened the start-up time, which has a positive effect on the operating costs of the machine.
Liquid-vapor coexistence is calculated via molecular dynamics for a variety of polygonal shaped molecules and for the platonic polyhedra. Tangential hard spheres interacting with an attractive ...square-well potential form the molecules. Spheres within the molecules are bonded together with in a small size infinitely high square-wells to keep them vibrating at the appropriate intra molecular distance. The total density of the system is near to its critical value. Liquid-vapor coexistence is obtained with the process of spinodal decomposition. orthobaric densities, surface tensions, vapor pressures and interfacial widths are calculated along with critical temperatures and densities. These polygonal and polyhedral shapes can be used in the development of a theoretical equation of state.
Mining machinery industry transformation is oriented towards highly sophisticated technologies aimed at enhancing the nature of operations carried out. Vibrating screen machine is a major player in ...the mining processing plants and has continuously been improved over the past years. This paper presents a literature study of vibrating screen development trends and the nature of the evolution through the years. From this comprehensive survey, a model was developed to show the distinct novelties and technical features that have evolved in vibrating screen production trends in the mining machinery industries. In view of this, aforementioned features novel techniques have also been identified, brainstormed and developed in order take mineral beneficiation technology and its associated industries to its peak.
The present investigation includes experimental and ANN-based intelligent modeling to explore the dynamic interference effect of closely positioned vibrating foundations placed on unreinforced and ...geogrid-reinforced soil beds. Large-scale field block vibration tests are conducted on isolated and interacting block footings placed on prepared foundation beds at IIT Kanpur, India. The dynamic interaction of various combinations of two-footing assemblies is examined where one footing (active footing) is excited with dynamic loadings, and the other (passive footing) carries static loadings. The tests involve three eccentric force settings for four distinct footing combinations at different clear spacings and reinforcement conditions. The responses of both footings are recorded at different loading frequencies. The interaction effect is presented in terms of the transmission ratio plotted against the frequency ratio. Additionally, an Artificial Neural Network (ANN) model is developed using the recorded field datasets to anticipate the dynamic interference effect. The predicted outcomes of the ANN model demonstrate promising agreement with the experimental findings reported in the literature, indicating the reliability and robustness of the intelligent model.
•Dynamic interaction between closely spaced footings is explored for unreinforced and geogrid-reinforced soil beds.•Effect of footing size, dynamic force level and spacing between footings is examined.•Efficacy of geogrid layers in reducing interaction between footings is observed.•An Artificial Neural Network (ANN) model is developed to predict the dynamic interaction effect.
Micro-electromechanical systems (MEMS) vibrating gyroscopes have gained a lot of attention over the last two decades because of their low power consumption, easy integration, and low fabrication ...cost. The usage of the gyroscope equipped with an inertial measurement unit has increased tremendously, with applications ranging from household devices to smart electronics to military equipment. However, reliability issues are still a concern when operating this inertial sensor in harsh environments, such as to control the movement and alignment of mini-satellites in space, tracking firefighters at an elevated temperature, and assisting aircraft navigation in gusty turbulent air. This review paper focuses on the key fundamentals of the MEMS vibrating gyroscopes, first discussing popular designs including the tuning fork, gimbal, vibrating ring, and multi-axis gyroscopes. It further investigates how bias stability, angle random walk, scale factor, and other performance parameters are affected in harsh environments and then discusses the reliability issues of the gyroscopes.
•A far-resonant vibrating system with three rollers driven by two vibrators.•Synchronization and stability among two vibrators and three rollers.•Vibrating crushing/grinding equipment with multiple ...working chambers.
As a continuing and intensive work of the previous literature, the synchronization and stability of a far-resonant vibrating system with three rollers and two vibrators, will be given in this paper. The criterion of implementing synchronization for two vibrators and three rollers, is obtained in theory firstly, by constructing mathematical models of the system and using the average method. The stability criterion of the synchronous states is proved to comply with the Routh–-Hurwitz principle. In numerical qualitative analyses, the coupling dynamic characteristics of the system are revealed in detail, by considering the effects of key parameters of the system, including structural parameters, friction coefficients, mass ratio and distance ratio coefficients. An experiment is carried out to further verify the validity of the theoretical and numerical results, as well as the feasibility of the theory method used. It is shown that the ideal stability effect can be reached, under the preconditions of matching reasonably a certain kind of parameters of the system. These facts can provide the theory guidance for designing some new types of vibrating crushing/grinding equipment with multiple working chambers, etc.
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