A New Model for Studying Nonlinear Vibration Behaviors of Gear-Bearing System

A new model for nonlinear vibration behaviors of gear-bearing system is proposed in this work. For presenting the nonlinear excitation from bearing compliance, the enhanced bearing force excitation model containing two kinds of bearing stiffnesses, which are mean stiffness for the load transfer capacity and alternating stiffness for the disturbance resisting ability, is developed. Considering other dynamic excitations including mesh stiffness, contact pressure angle, center distance, unbalance force caused by static and dynamic eccentricity, an advanced iterative numerical method is introduced, which can timely and accurately update the excitations caused by load-dependent and time-varying nonlinearities inside of the system. The constant bearing stiffness and time-varying bearing alternating stiffness models are introduced and compared with the enhanced bearing excitation force model. The parametric resonant regions and system nonlinear periodic motion states are studied and compared for different bearing supporting models. The effects from internal and external excitations on the system nonlinear vibration behaviors are investigated.

Emergent Magnetic Monopole and Dipole Screening by Proximity Effect With Noble Metal

In this work we present emergent screening of magnetic monopole and dipole by the presence of 20nm aluminum cover layer onsquare artificial spin ice (ASI) systems. Our results were obtained in base of magnetic atomic force measurements, performedafter external magnetic field steps application. We show that the evolution of magnetization and monopole population is affectedby the aluminum presence and attribute that phenomena to the proximity effect, which is responsible for the magnetizationvanish of the first atomic layers at the ferromagnetic interface. Using experimental values to estimate the decrease in thenanomagnetic dipole value used in an emergent excitation model and in the switching field distribution heterogeneity usedin simulations, we observe a very good agreement among experimental and simulation results. The presented emergentscreening could be used in new ASI geometries for thermodynamic activation or proposition of devices with selective magneticmonopole mobility.

The Autoregressive Moving Average with Exogenous Excitation Model for Acoustic Scattering from Underwater Objects

This study aims to identify and predict objects underwater using the autoregressive moving average with exogenous excitation (ARMX) model in such a way that the outcome of the model is similar to actual measurements. It is used for parameter estimation. This model is validated by comparing results in actual model with ARMX model, autoregressive with an exogenous variables, and Box Jenkins (BJ) model. The results are analyzed in frequency and time domain by using mean square error criterion. Initial results show that ARMX predicts the acoustic scattering response with an accuracy of 96%, while ARX provides an accuracy of 78%, and BJ model poorly estimates the signal with an accuracy of 35%. ARMX also provides higher accuracy of detection by 7-8% as compared to the existing techniques.

Temperature diagnostics of Sulfur III plasma using collision-excitation model

For accurate electron temperature diagnostics, the collision-excitation model is used for Sulfur plasma. Using the calculated Maxwellian average collision strengths at 1000 K, we calculate the electron temperature using the 3s23p2[Formula: see text]D1–3s23p2[Formula: see text]P3, 3s23p2[Formula: see text]S1–3s23p2[Formula: see text]D1 and 3s23p2[Formula: see text]S1–3s23p2[Formula: see text]P3 transitions of Sulfur III. Results show that when the line ratio of 3s23p2[Formula: see text]S1–3s23p2[Formula: see text]D1 and 3s23p2[Formula: see text]D1–3s23p2[Formula: see text]P3 transitions varies from 0.43 to 1, the electron temperature will vary from 0 to [Formula: see text] K, and the electron temperature will decrease with increasing line ratio. This discussion will be important for electron temperature diagnostics of plasma.

Establishment of an experimental-computational framework for promoting Project-based learning for vibrations and controls education

A curriculum enhancement project of embedding MATLAB and Simulink to a mechanical engineering (ME) vibrations and controls course is presented in this paper. MATLAB/Simulink is a popular software tool for vibration analysts and control designers, which is consistently regarded as one of the most in-demand technical skills that employers are looking for. In the past, the ME students at Mississippi State University (MSU) did not have the training opportunity to use MATLAB/Simulink for design and analysis of vibration and control systems. With the support of a teaching grants, the author created an experimental lab section to ask students to design and build vibration and control devices, and integrated these device into his vibrations and controls course. In this study, the author develops a computer lab section based on the implementation of MATLAB/Simulink, which complements with the experimental lab section to provide the students with a full lab experience. The experimental-computational lab allows the students to not only observe and characterize the dynamic response of vibration and control systems through experimental operations and measurements, but also validate experimental results and confirm experimental phenomena through computational analysis. As well as exploring dynamic behaviors of the systems in a variety of conditions through numerical simulations with different settings. An example of student project is presented to show an experimental-computational study conducted by a student team using MATLAB/Simulink software tool and self-developed data acquisition systems based on a base excitation model demonstrated in class. A questionnaire was conducted at the end of that class and results confirms that the implementation of MATLAB/Simulink into the course effectively develops the ME students’ programming skills and strengthens their capacity in modeling, simulating, and analyzing vibration, control, and other dynamic systems. The developed computational lab and the current experimental lab complementarily promote student understanding of principles and concepts conveyed in classroom lectures.