scholarly journals Numerical Modal Analysis of Vibrations in a Three-Phase Linear Switched Reluctance Actuator

2017 ◽  
Vol 2017 ◽  
pp. 1-18
Author(s):  
José Salvado ◽  
Maria do Rosário Calado ◽  
António Espírito Santo ◽  
Anna Guerman
Keyword(s):  
Control Strategies ◽  
Mode Shapes ◽  
Audio Signals ◽  
Structural Vibrations ◽  
Significant Information ◽  
Switched Reluctance ◽  
Three Phase ◽  
Linear Configuration ◽  
Analytical Approaches

This paper addresses the problem of vibrations produced by switched reluctance actuators, focusing on the linear configuration of this type of machines, aiming at its characterization regarding the structural vibrations. The complexity of the mechanical system and the number of parts used put serious restrictions on the effectiveness of analytical approaches. We build the 3D model of the actuator and use finite element method (FEM) to find its natural frequencies. The focus is on frequencies within the range up to nearly 1.2 kHz which is considered relevant, based on preliminary simulations and experiments. Spectral analysis results of audio signals from experimental modal excitation are also shown and discussed. The obtained data support the characterization of the linear actuator regarding the excited modes, its vibration frequencies, and mode shapes, with high potential of excitation due to the regular operation regimes of the machine. The results reveal abundant modes and harmonics and the symmetry characteristics of the actuator, showing that the vibration modes can be excited for different configurations of the actuator. The identification of the most critical modes is of great significance for the actuator’s control strategies. This analysis also provides significant information to adopt solutions to reduce the vibrations at the design.

Monitoring of Petroleum-Related Environmental Contamination Using Fluorescence Fingerprinting

2006 ◽  
Vol 1 (2) ◽  
Author(s):  
P. Literathy ◽  
M. Quinn
Keyword(s):  
Environmental Contamination ◽  
Statistical Evaluation ◽  
Oil Pollution ◽  
Emission Spectra ◽  
Cost Effective ◽  
Petroleum Products ◽  
Danube River ◽  
Aromatic Components ◽  
Analytical Approaches

Petroleum and its refined products are considered the most complex contaminants frequently impacting the environment in significant quantities. They have heterogeneous chemical composition and alterations occur during environmental weathering. No single analytical method exists to characterize the petroleum-related environmental contamination. For monitoring, the analytical approaches include gravimetric, spectrometric and chromatographic methods having significant differences in their selectivity, sensitivity and cost-effectiveness. Recording fluorescence fingerprints of the cyclohexane extracts of the water, suspended solids, sediment or soil samples and applying appropriate statistical evaluation (e.g. by correlating the concatenated emission spectra of the fingerprints of the samples with arbitrary standards (e.g. petroleum products)), provides a powerful, cost-effective analytical tool for characterization of the type of oil pollution and detecting the most harmful aromatic components of the petroleum contaminated matrix. For monitoring purposes, the level of the contamination can be expressed as the equivalent concentration of an appropriate characteristic standard, based on the fluorescence intensities at the relevant characteristic wavelengths. These procedures are demonstrated in the monitoring of petroleum-related pollution in the water and suspended sediment in the Danube river basin

scholarly journals Impedance Matching-Based Power Flow Analysis for UPQC in Three-Phase Four-Wire Systems

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2702
Author(s):  
Xiaojun Zhao ◽  
Xiuhui Chai ◽  
Xiaoqiang Guo ◽  
Ahmad Waseem ◽  
Xiaohuan Wang ◽  
...  
Keyword(s):  
Power Flow ◽  
Control Strategies ◽  
Impedance Matching ◽  
Flow Analysis ◽  
Point Of View ◽  
Impedance Model ◽  
Power Flow Analysis ◽  
Three Phase ◽  
System Node ◽  
Power Quality Conditioner

Different from the extant power flow analysis methods, this paper discusses the power flows for the unified power quality conditioner (UPQC) in three-phase four-wire systems from the point of view of impedance matching. To this end, combined with the designed control strategies, the establishing method of the UPQC impedance model is presented, and on this basis, the UPQC system can be equivalent to an adjustable impedance model. After that, a concept of impedance matching is introduced into this impedance model to study the operation principle for the UPQC system, i.e., how the system changes its operation states and power flow under the grid voltage variations through discussing the matching relationships among node impedances. In this way, the nodes of the series and parallel converter are matched into two sets of impedances in opposite directions, which mean that one converter operates in rectifier state to draw the energy and the other one operates in inverter state to transmit the energy. Consequently, no matter what grid voltages change, the system node impedances are dynamically matched to ensure that output equivalent impedances are always equal to load impedances, so as to realize impedance and power balances of the UPQC system. Finally, the correctness of the impedance matching-based power flow analysis is validated by the experimental results.

scholarly journals Effect of Thrust on the Structural Vibrations of a Nonuniform Slender Rocket

2020 ◽  
Vol 25 (2) ◽  
pp. 29
Author(s):  
Desmond Adair ◽  
Aigul Nagimova ◽  
Martin Jaeger
Keyword(s):  
Natural Frequencies ◽  
Equations Of Motion ◽  
Approximate Solutions ◽  
Mode Shapes ◽  
Algebraic Equations ◽  
Structural Vibrations ◽  
Unknown Parameters ◽  
One Dimensional ◽  
Vibration Problems ◽  
Nonuniform Beam

The vibration characteristics of a nonuniform, flexible and free-flying slender rocket experiencing constant thrust is investigated. The rocket is idealized as a classic nonuniform beam with a constant one-dimensional follower force and with free-free boundary conditions. The equations of motion are derived by applying the extended Hamilton’s principle for non-conservative systems. Natural frequencies and associated mode shapes of the rocket are determined using the relatively efficient and accurate Adomian modified decomposition method (AMDM) with the solutions obtained by solving a set of algebraic equations with only three unknown parameters. The method can easily be extended to obtain approximate solutions to vibration problems for any type of nonuniform beam.

Optimized screen-printing and SEM-FIB characterization of YSZ thin films for Solid Oxide Fuel Cells and gas sensors devices

2004 ◽  
Vol 822 ◽  
Author(s):  
A. Morata ◽  
A. Tarancón ◽  
G. Dezanneau ◽  
F. Peiró ◽  
J. R. Morante
Keyword(s):  
Experimental Design ◽  
Screen Printing ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Deposition Process ◽  
Technological Parameters ◽  
Significant Information ◽  
Screen Printing Technique ◽  
Final Porosity

AbstractIn the present work, the screen printing technique has been used to deposit thick films of Zr0.84Y016O1.92 (8YSZ). In order to control the final porosity in view of a specific application (SOFCs or gas sensor), an experimental design based on analysis of variances (ANOVA) has been carried out. From this, we were able to determine the influence of several technological parameters on films porosity and grain size. The films obtained have been analysed with both Scanning Electron Microscopy (SEM) and Focused Ion Beam (FIB) combined with SEM. We show that only the combination of experimental design and advanced observation technique such as Focused Ion Beam allowed us to extract significant information for the improvement of the deposition process.

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