scholarly journals The Behaviour of Mistuned Piezoelectric Shunt Systems and Its Estimation

2016 ◽  
Vol 2016 ◽  
pp. 1-18 ◽  
Author(s):  
M. Berardengo ◽  
S. Manzoni ◽  
M. Vanali
Keyword(s):  
Experimental Tests ◽  
Vibration Damping ◽  
Piezoelectric Transducers ◽  
Electric Impedance ◽  
Rapid Prediction ◽  
Vibration Attenuation ◽  
In Series ◽  
Dynamical Features ◽  
Impedance Parameters ◽  
Piezoelectric Shunt

This paper addresses monoharmonic vibration attenuation using piezoelectric transducers shunted with electric impedances consisting of a resistance and an inductance in series. This type of vibration attenuation has several advantages but suffers from problems related to possible mistuning. In fact, when either the mechanical system to be controlled or the shunt electric impedance undergoes a change in their dynamical features, the attenuation performance decreases significantly. This paper describes the influence of biases in the electric impedance parameters on the attenuation provided by the shunt and proposes an approximated model for a rapid prediction of the vibration damping performance in mistuned situations. The analytical and numerical results achieved within the paper are validated using experimental tests on two different test structures.

scholarly journals A Simple Mismatch Mitigating Partial Power Processing Converter for Solar PV Modules

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2308
Author(s):  
Kamran Ali Khan Niazi ◽  
Yongheng Yang ◽  
Tamas Kerekes ◽  
Dezso Sera
Keyword(s):  
Experimental Tests ◽  
Energy Yield ◽  
Power Electronic ◽  
Solar Pv ◽  
Partial Shading ◽  
Loss Analysis ◽  
Pv Systems ◽  
Pv Module ◽  
Pv Modules ◽  
In Series

Partial shading affects the energy harvested from photovoltaic (PV) modules, leading to a mismatch in PV systems and causing energy losses. For this purpose, differential power processing (DPP) converters are the emerging power electronic-based topologies used to address the mismatch issues. Normally, PV modules are connected in series and DPP converters are used to extract the power from these PV modules by only processing the fraction of power called mismatched power. In this work, a switched-capacitor-inductor (SCL)-based DPP converter is presented, which mitigates the non-ideal conditions in solar PV systems. A proposed SCL-based DPP technique utilizes a simple control strategy to extract the maximum power from the partially shaded PV modules by only processing a fraction of the power. Furthermore, an operational principle and loss analysis for the proposed converter is presented. The proposed topology is examined and compared with the traditional bypass diode technique through simulations and experimental tests. The efficiency of the proposed DPP is validated by the experiment and simulation. The results demonstrate the performance in terms of higher energy yield without bypassing the low-producing PV module by using a simple control. The results indicate that achieved efficiency is higher than 98% under severe mismatch (higher than 50%).

scholarly journals Feasibility of Using Electrical Impedance Spectroscopy for Assessing Biological Cell Damage during Freezing and Thawing

Sensors ◽  
2021 ◽  
Vol 21 (12) ◽  
pp. 4129
Author(s):  
Sisay Mebre Abie ◽  
Ørjan Grøttem Martinsen ◽  
Bjørg Egelandsdal ◽  
Jie Hou ◽  
Frøydis Bjerke ◽  
...  
Keyword(s):  
Phase Angle ◽  
Short Term Memory ◽  
Cell Damage ◽  
Electrical Impedance Spectroscopy ◽  
Electric Impedance ◽  
Freezing And Thawing ◽  
Short Term ◽  
Long Short Term Memory ◽  
Impedance Parameters ◽  
Deep Learning Model

This study was performed to test bioimpedance as a tool to detect the effect of different thawing methods on meat quality to aid in the eventual creation of an electric impedance-based food quality monitoring system. The electric impedance was measured for fresh pork, thawed pork, and during quick and slow thawing. A clear difference was observed between fresh and thawed samples for both impedance parameters. Impedance was different between the fresh and the frozen-thawed samples, but there were no impedance differences between frozen-thawed samples and the ones that were frozen-thawed and then stored at +3 °C for an additional 16 h after thawing. The phase angle was also different between fresh and the frozen-thawed samples. At high frequency, there were small, but clear phase angle differences between frozen-thawed samples and the samples that were frozen-thawed and subsequently stored for more than 16 h at +3 °C. Furthermore, the deep learning model LSTM-RNN (long short-term memory recurrent neural network) was found to be a promising way to classify the different methods of thawing.

Preliminary Investigations of Machine Frame Vibration Damping Using Eddy Current Principle

2016 ◽  
Vol 821 ◽  
pp. 288-294 ◽  
Author(s):  
George Juraj Stein ◽  
Peter Tobolka ◽  
Rudolf Chmúrny
Keyword(s):  
Mathematical Model ◽  
Natural Frequency ◽  
Eddy Current ◽  
Asynchronous Motor ◽  
Oscillatory System ◽  
Vibration Damping ◽  
Combined Effects ◽  
Magnetic Forces ◽  
Novel Approach ◽  
Vibration Attenuation

A novel approach to vibration attenuation, based on the eddy current principle, is described. The combined effects of all magnetic forces acting in the oscillatory system attenuate frame vibrations and, concurrently, decrease the damped natural frequency. A mathematical model of the forces balance in the oscillatory system was derived before. Some experimental results from a mock-up machine frame excited by an asynchronous motor are presented.

Various Attractors, Coexisting Attractors and Antimonotonicity in a Simple Fourth-Order Memristive Twin-T Oscillator

2018 ◽  
Vol 28 (04) ◽  
pp. 1850050 ◽  
Author(s):  
Ling Zhou ◽  
Chunhua Wang ◽  
Xin Zhang ◽  
Wei Yao
Keyword(s):  
Fourth Order ◽  
Chaotic Systems ◽  
Basin Of Attraction ◽  
Phase Portraits ◽  
Chaotic Attractors ◽  
Coexisting Attractors ◽  
Dynamical Behaviors ◽  
Random Bit Generator ◽  
In Series ◽  
Dynamical Features

By replacing the resistor in a Twin-T network with a generalized flux-controlled memristor, this paper proposes a simple fourth-order memristive Twin-T oscillator. Rich dynamical behaviors can be observed in the dynamical system. The most striking feature is that this system has various periodic orbits and various chaotic attractors generated by adjusting parameter [Formula: see text]. At the same time, coexisting attractors and antimonotonicity are also detected (especially, two full Feigenbaum remerging trees in series are observed in such autonomous chaotic systems). Their dynamical features are analyzed by phase portraits, Lyapunov exponents, bifurcation diagrams and basin of attraction. Moreover, hardware experiments on a breadboard are carried out. Experimental measurements are in accordance with the simulation results. Finally, a multi-channel random bit generator is designed for encryption applications. Numerical results illustrate the usefulness of the random bit generator.

Sheet Hemming with Rolling Tools: Analysis and Optimization of the Part Quality

2007 ◽  
Vol 344 ◽  
pp. 357-364 ◽  
Author(s):  
Elisabetta Ceretti ◽  
Aldo Attanasio ◽  
Antonio Fiorentino ◽  
Claudio Giardini
Keyword(s):  
Tool Path ◽  
Outer Part ◽  
Experimental Tests ◽  
Process Time ◽  
Cnc Machine ◽  
Whole Process ◽  
Cad Cam ◽  
In Series ◽  
Aluminium Sheets ◽  
Set Up

The present paper is the continuation of a research conducted on hemming operations by using rolling tools. Sheet hemming is a joining operation widely used in automotive industry when it is necessary to join two sheet parts (such as the engine hood or the door panels with their internal frame) by plastic deformation of the edge of the outer part. The whole process is characterised by a 90° sheet flanging, a pre-hemming (up to approximately 135°) and the final hemming where the outer sheet edge is bended up to 180° clamping the inner sheet. Hemming processes are normally performed using rigid dies in series production and manually in pre-series and small batch production, due to the high cost of the dies. Nowadays, rollers moved by robots are becoming an interesting alternative to the manual operations especially when flexible productions are required. Even if the process time is higher, this solution can help in minimizing set-up times and costs. The required equipments are a support and a blocking system for the sheets together with the rollers mounted on a CNC machine or on a robot. The production flexibility is guaranteed by changing the 3D tool path using a CAD/CAM system. Authors are dealing with this technique having conducted many experiments studying the influence of the hemming process parameters such as flange geometry (edge height, fillet radius), distance of the inner panel from the flange, tool path sequence, along straight paths on steel sheets. The goal of the present research is to study the material behaviour and the produced parts quality when working on aluminium sheets. In particular, both experimental tests and simulations will be carried out in order to optimize the process.

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