scholarly journals Seismic Qualification of Electrical Cabinet Using High-Fidelity Simulation under High Frequency Earthquakes

2020 ◽  
Vol 12 (19) ◽  
pp. 8048
Author(s):  
Hoyoung Son ◽  
Seonggwan Park ◽  
Bub-Gyu Jeon ◽  
Woo-Young Jung ◽  
Jongwoong Choi ◽  
...  
Keyword(s):  
Seismic Response ◽  
High Frequency ◽  
Power Plants ◽  
Low Frequency ◽  
Experimental Tests ◽  
Design Guidelines ◽  
High Fidelity ◽  
High Fidelity Simulation ◽  
Nonstructural Components ◽  
Fundamental Frequencies

Most nuclear and nonnuclear power plants have been designed in the frequency range of 2 to 10 Hz, but now, the design guidelines for structural and nonstructural components such as electrical cabinets must be improved by including high frequency greater than 10 Hz for sustainable energy. The electrical cabinet is the essential piece of equipment for safety functions and the uncertainty of seismic capability in power plants. Consequently, the attention of this study focused on evaluating the seismic demands of the electrical cabinet under high frequency earthquakes and also, seismic qualification of the electrical cabinet using the identification of experimental tests and numerical models. An experimental test based on ICC-ES AC 156 and IEEE std.344 was conducted for seismic qualification of the cabinet and then, a high-fidelity finite element model to capture the significant deformation was developed in this study. It is observed that the fundamental frequencies were 16 and 24 Hz from the experimental tests, respectively. In order to verify the proposed high-fidelity simulation model, the target fundamental frequencies of the cabinet were evaluated in the ABAQUS platform. It was interesting to note that the reconciliation of experimental and analytical results was extremely identical. Furthermore, in order to evaluate seismic response characteristics of the cabinet subjected to high and low frequency earthquakes, time history analysis was conducted in this study, using the ABAQUS platform. As a result, the observation showed that the seismic response of the cabinet system under a high frequency earthquake was relatively higher than that of low frequency. It can be very important to note that the cabinet system was sensitive to high frequency vibration.

Output Power Correlation Between Nearby Wind Power Plants

2003 ◽  
Author(s):  
Yih-Huei Wan ◽  
Michael Milligan ◽  
Brian Parsons
Keyword(s):  
Power Plant ◽  
Wind Power ◽  
Power Output ◽  
High Frequency ◽  
Power Plants ◽  
Meteorological Data ◽  
Low Frequency ◽  
Spatial Separation ◽  
Wind Power Plant ◽  
Wind Power Plants

The National Renewable Energy Laboratory (NREL) started a project in 2000 to record long-term, high-frequency (1-Hz) wind power output data from large commercial wind power plants. Outputs from about 330 MW of wind generating capacity from wind power plants in Buffalo Ridge, Minnesota, and Storm Lake, Iowa, are being recorded. Analysis of the collected data shows that although very short-term wind power fluctuations are stochastic, the persistent nature of wind and the large number of turbines in a wind power plant tend to limit the magnitudes and rates of changes in the levels of wind power. Analyses of power data confirm that spatial separation greatly reduces variations in the combined wind power output relative to output from a single wind power plant. Data show that high frequency variations of wind power from two wind power plants 200 km apart are independent of each other, but low frequency power changes can be highly correlated. This fact suggests that time-synchronized power data and meteorological data can aid in the development of statistical models for wind power forecasting.

Output Power Correlation Between Adjacent Wind Power Plants*

2003 ◽  
Vol 125 (4) ◽  
pp. 551-555 ◽  
Author(s):  
Yih-huei Wan ◽  
Michael Milligan ◽  
Brian Parsons
Keyword(s):  
Power Plant ◽  
Wind Power ◽  
High Frequency ◽  
Power Plants ◽  
Meteorological Data ◽  
Low Frequency ◽  
Spatial Separation ◽  
Rate Of Change ◽  
Wind Power Plant ◽  
Wind Power Plants

The National Renewable Energy Laboratory (NREL) started a project in 2000 to record long-term, high-frequency (1-Hz) wind power data from large commercial wind power plants in the Midwestern United States. Outputs from about 330 MW of installed wind generating capacity from wind power plants in Lake Benton, MN, and Storm Lake, Iowa, are being recorded. Analysis of the collected data shows that although very short-term wind power fluctuations are stochastic, the persistent nature of wind and the large number of turbines in a wind power plant tend to limit the magnitude of fluctuations and rate of change in wind power production. Analyses of power data confirms that spatial separation of turbines greatly reduces variations in their combined wind power output when compared to the output of a single wind power plant. Data show that high-frequency variations of wind power from two wind power plants 200 km apart are independent of each other, but low-frequency power changes can be highly correlated. This fact suggests that time-synchronized power data and meteorological data can aid in the development of statistical models for wind power forecasting.

Analytical Modeling and Experimental Verification of the Vibrations of the Zigzag Microstructure for Energy Harvesting

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
M. Amin Karami ◽  
Daniel J. Inman
Keyword(s):  
Energy Harvesting ◽  
Resonance Condition ◽  
Low Frequency ◽  
Dominant Frequency ◽  
Design Guidelines ◽  
Ambient Vibration ◽  
Micro Electro Mechanical Systems ◽  
Fundamental Frequencies ◽  
Near Resonance ◽  
Tip Mass

This paper addresses an issue in energy harvesting that has plagued the potential use of harvesting through the piezoelectric effect at the micro-electro-mechanical systems (MEMS) scale. Effective energy harvesting devices typically consist of a cantilever beam substrate coated with a thin layer of piezoceramic material and fixed with a tip mass tuned to resonant at the dominant frequency of the ambient vibration. The fundamental natural frequency of a beam increases as its length decreases, so that at the MEMS scale the resonance condition occurs orders of magnitude higher than ambient vibration frequencies, rendering the harvester ineffective. Here, we propose a new geometry for MEMS scale cantilever harvesters with low fundamental frequencies. A “zigzag” geometry is proposed, modeled, and solved to show that such a structure would be able to vibrate near resonance at the MEMS scale. An analytical solution is presented and verified against Rayleigh’s method and is validated against a macroscale experiment. The analysis is used to provide design guidelines and parametric studies for constructing an effective MEMS scale energy harvesting device in the frequency range common to low frequency ambient vibrations, removing a current barrier.

The Impact of Hazard Statement Design Elements in Procedures: Counterintuitive Findings and Implications for Standards

2021 ◽  
pp. 001872082110501
Author(s):  
Joseph W. Hendricks ◽  
S. Camille Peres ◽  
Stefan V. Dumlao ◽  
Cara A. Armstrong ◽  
Timothy J. Neville
Keyword(s):  
Experimental Studies ◽  
Design Guidelines ◽  
Consumer Products ◽  
High Fidelity ◽  
High Fidelity Simulation ◽  
Consistent Finding ◽  
Design Elements ◽  
Standard Operating ◽  
The Impact ◽  
Positive Effect

Objective The objective of these studies was to identify hazard statement (HS) design elements in procedures that affected whether both workers and lab participants performed the associated hazard mitigation. Background Many of the incidents in high-risk industries are the result of issues with procedures (e.g., standard operating procedures; SOPs) workers use to support their performance. HSs in these procedures are meant to communicate potential work hazards and methods of mitigating those hazards. However, there is little empirical research regarding whether current hazard design guidelines for consumer products translate to procedures. Method Two experimental studies—(1) a laboratory study and (2) a high-fidelity simulation—manipulated the HS design elements present in procedures participants used while performing tasks. Participants’ adherence to the mitigation of the hazard was compared for the HS designs. Results The guidelines for HSs from consumer products did not translate to procedures. Specifically, the presence of an alert icon, a box around the statement, and highlighting the statement did not improve adherence to HSs. Indeed, the only consistent finding was for the Icon, with its presence reliably predicting nonadherence in both studies. Additionally, the total number of design elements did not have a positive effect on adherence. Conclusion These findings indicate that more fundamental procedure HSs research is needed to identify effective designs as well as to understand the potential attentional mechanisms associated with these findings. Application The findings from these studies indicate that current regulations and guidelines should be revisited regarding hazard presentation in procedures.

scholarly journals Effect of Frequency Content of Earthquake on the Seismic Response of Interconnected Electrical Equipment

CivilEng ◽  
2020 ◽  
Vol 1 (3) ◽  
pp. 198-215
Author(s):  
Kashif Salman ◽  
Sung Gook Cho
Keyword(s):  
Seismic Response ◽  
Natural Frequency ◽  
Ground Motion ◽  
High Frequency ◽  
Seismic Analysis ◽  
Response Spectrum ◽  
Low Frequency ◽  
Stable Operation ◽  
Design Spectrum ◽  
Standard Design

To ensure the stable operation of safety-related nuclear power plant (NPP) equipment, they are tested by following the seismic qualification procedures. The in-cabinet response spectrum (ICRS) is used to test the mounted components. However, the ICRS varies significantly with the number of uncertainties that include (1) loaded and unloaded condition of the cabinets, (2) the number of connected cabinets (grouping effects), and (3) higher frequency contents in the seismic inputs. This study focuses on the ICRS generation and alteration induced due to the listed uncertainties. A prototype of an electrical cabinet was experimentally examined. Followed by the numerical modeling of the cabinet, the seismic analysis for the group of cabinets was performed using artificial ground motion compatible with the standard design spectrum and the real accelerograms of high and low frequency contents. The seismic response using finite element (FE) analysis manifests (1) natural frequency of loaded cabinets reduced due to the in-cabinet components while for the unloaded cabinets it increased significantly, (2) a consistent reduction in ICRS due to the grouping effect was recorded when excited by the lower-frequency motion, while it was amplified dramatically due to high-frequency pulses. Interconnected cabinets under the low-frequency input motions have a significant reduction of 50% in the ICRS that corresponds to the higher stiffness of the cabinets, while a 100% increase under the high frequency of ground motion was obtained. High frequency of ground motion, usually above 10 Hz, can cause the interconnected cabinets to resonate as the natural frequency of these equipment lies in this range.

scholarly journals High Frequency Performance of Piezoelectric Diaphragms for Impedance-Based SHM Applications

2020 ◽  
Vol 2 (1) ◽  
pp. 16
Author(s):  
Guilherme Rezende ◽  
Fabricio Baptista
Keyword(s):  
High Frequency ◽  
Structural Damage ◽  
Low Cost ◽  
Low Frequency ◽  
Experimental Tests ◽  
Piezoelectric Transducers ◽  
Low Frequencies ◽  
High Frequencies ◽  
Electromechanical Impedance ◽  
Damage Indices

Piezoelectric transducers are used in a wide variety of applications, including damage detection in structural health monitoring (SHM) applications. Among the various methods for detecting structural damage, the electromechanical impedance (EMI) method is one of the most investigated in recent years. In this method, the transducer is typically excited with low frequency signals up to 500 kHz. However, recent studies have indicated the use of higher frequencies, usually above 1 MHz, for the detection of some types of damage and the monitoring of some structures’ characteristics that are not possible at low frequencies. Therefore, this study investigates the performance of low-cost piezoelectric diaphragms excited with high frequency signals for SHM applications based on the EMI method. Piezoelectric diaphragms have recently been reported in the literature as alternative transducers for the EMI method and, therefore, investigating the performance of these transducers at high frequencies is a relevant subject. Experimental tests were carried out with piezoelectric diaphragms attached to two aluminum bars, obtaining the impedance signatures from diaphragms excited with low and high frequency signals. The analysis was performed using the real part of the impedance signatures and two basic damage indices, one based on the Euclidean norm and the other on the correlation coefficient. The experimental results indicate that piezoelectric diaphragms are usable for the detection of structural damage at high frequencies, although the sensitivity decreases.

The Design and Control of a Rigid-flexible Coupling Positioning Stage for Enhanced Settling Performance

2021 ◽  
Author(s):  
Hao Peng ◽  
Zhijun Yang ◽  
Wenchao Xue ◽  
Ruirui Huang ◽  
Yi Huang
Keyword(s):  
High Frequency ◽  
High Speed ◽  
Mechanical Design ◽  
Dead Zone ◽  
Low Frequency ◽  
Poor Performance ◽  
Experimental Tests ◽  
Control Performance ◽  
Flexible Coupling ◽  
Positioning Stage

Abstract Traditional high-speed precision motion stage (HSPMS) design pursues high-stiffness structure to achieve fast response. However, such structure leads to high-frequency disturbance near dead zone of friction, which causes poor performance in controlling HSPMS. To this end, this paper proposes the active disturbance rejection control (ADRC) based mechanical design to reduce the bandwidth of friction disturbance and improve the control performance of HSPMS. It is proved that the low-frequency disturbance can be more effectively tackled by the extended state observer (ESO) in the frame of ADRC. In particular, rigid-flexible coupling (RFC) positioning stage is presented for converting the high-frequency friction disturbance into the low-frequency elastic deformation disturbance by flexure hinges. The experimental tests are carried out for both traditional stage and RFC stage. It is clearly shown that compared with traditional design, the control performance of RFC stage is remarkably promoted.

Simulations of high-resolution images of amorphous silicon films

1986 ◽  
Vol 44 ◽  
pp. 544-545
Author(s):  
G. Y. Fan ◽  
J. M. Cowley
Keyword(s):  
Electron Microscope ◽  
High Frequency ◽  
Fourier Transformation ◽  
Amorphous Materials ◽  
Low Frequency ◽  
Chromatic Aberration ◽  
Structure Information ◽  
Frequency Components ◽  
High Resolution Images ◽  
Spatial Frequency Spectrum

It is well known that the structure information on the specimen is not always faithfully transferred through the electron microscope. Firstly, the spatial frequency spectrum is modulated by the transfer function (TF) at the focal plane. Secondly, the spectrum suffers high frequency cut-off by the aperture (or effectively damping terms such as chromatic aberration). While these do not have essential effect on imaging crystal periodicity as long as the low order Bragg spots are inside the aperture, although the contrast may be reversed, they may change the appearance of images of amorphous materials completely. Because the spectrum of amorphous materials is continuous, modulation of it emphasizes some components while weakening others. Especially the cut-off of high frequency components, which contribute to amorphous image just as strongly as low frequency components can have a fundamental effect. This can be illustrated through computer simulation. Imaging of a whitenoise object with an electron microscope without TF limitation gives Fig. 1a, which is obtained by Fourier transformation of a constant amplitude combined with random phases generated by computer.

SEM image sharpness analysis

1996 ◽  
Vol 54 ◽  
pp. 142-143
Author(s):  
M. T. Postek ◽  
A. E. Vladar
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Quantitative Information ◽  
Primary Electron ◽  
Image Sharpness ◽  
Critical Dimensions ◽  
Sem Image ◽  
Frequency Changes ◽  
Electron Microscopes ◽  
Scanning Electron

Fully automated or semi-automated scanning electron microscopes (SEM) are now commonly used in semiconductor production and other forms of manufacturing. The industry requires that an automated instrument must be routinely capable of 5 nm resolution (or better) at 1.0 kV accelerating voltage for the measurement of nominal 0.25-0.35 micrometer semiconductor critical dimensions. Testing and proving that the instrument is performing at this level on a day-by-day basis is an industry need and concern which has been the object of a study at NIST and the fundamentals and results are discussed in this paper.In scanning electron microscopy, two of the most important instrument parameters are the size and shape of the primary electron beam and any image taken in a scanning electron microscope is the result of the sample and electron probe interaction. The low frequency changes in the video signal, collected from the sample, contains information about the larger features and the high frequency changes carry information of finer details. The sharper the image, the larger the number of high frequency components making up that image. Fast Fourier Transform (FFT) analysis of an SEM image can be employed to provide qualitiative and ultimately quantitative information regarding the SEM image quality.

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