An Investigation on Design and Performance of Low‐Frequency Panel Absorbers

1983 ◽  
Vol 73 (2) ◽  
pp. 699-699
Author(s):  
M. H. Taghavi‐Nejad
Keyword(s):  
Low Frequency ◽  
And Performance

scholarly journals SIMULATION AND ANALYSIS OF DIFFERENT PIEZOELECTRIC MATERIALS IN MEMS CANTILEVER FOR ENERGY HARVESTING

2021 ◽  
Vol 9 (1) ◽  
pp. 1321-1328
Author(s):  
Abdul Aziz Khan J , Shanmugaraja P , Kannan S
Keyword(s):  
Energy Harvesting ◽  
Lead Zirconate Titanate ◽  
Piezoelectric Materials ◽  
Low Frequency ◽  
Lead Zirconate ◽  
Vital Role ◽  
Von Mises Stress ◽  
And Performance ◽  
Von Mises ◽  
Implantable Sensor

MEMS Energy Harvesting(EH) devices are excepted to grow in the upcoming years, due to the increasing aspects of MEMS EH devices in vast applications. In Recent advancements in energy harvesting (EH) technologies wireless sensor devices play a vital role to extend their lifetime readily available in natural resources. In this paper the design of MEMS Cantilever at low frequency (100Hz) with different piezoelectric materials Gallium Arsenide (GaAs), Lead Zirconate Titanate (PZT-8), Tellurium Dioxide (TeO2), Zinc oxide (ZnO) is simulated and performance with different materials are compared. The results are analyzed with various parameters such as electric potential voltage, von mises stress, displacement. The paper discusses the suitability of the piezoelectric material for MEMS fully cochlear implantable sensor application.

scholarly journals Automated processing of railway track deflection signals obtained from velocity and acceleration measurements

2018 ◽  
Vol 232 (8) ◽  
pp. 2097-2110 ◽  
Author(s):  
David Milne ◽  
Louis L Pen ◽  
David Thompson ◽  
William Powrie
Keyword(s):  
Performance Monitoring ◽  
Low Frequency ◽  
Cumulative Distribution ◽  
Railway Track ◽  
Statistical Process ◽  
Vibration Data ◽  
Rest Position ◽  
Low Frequency Vibration ◽  
Automated Processing ◽  
And Performance

Measurements of low-frequency vibration are increasingly being used to assess the condition and performance of railway tracks. Displacements used to characterise the track movement under train loads are commonly obtained from velocity or acceleration signals. Artefacts from signal processing, which lead to a shift in the datum associated with the at-rest position, as well as variability between successive wheels, mean that interpreting measurements is non-trivial. As a result, deflections are often interpreted by inspection rather than following an algorithmic or statistical process. This can limit the amount of data that can be usefully analysed in practice, militating against widespread or long-term use of track vibration measurements for condition or performance monitoring purposes. This paper shows how the cumulative distribution function of the track deflection can be used to identify the at-rest position and to interpret the typical range of track movement from displacement data. This process can be used to correct the shift in the at-rest position in velocity or acceleration data, to determine the proportion of upward and downward movement and to align data from multiple transducers to a common datum for visualising deflection as a function of distance along the track. The technique provides a means of characterising track displacement automatically, which can be used as a measure of system performance. This enables large volumes of track vibration data to be used for condition monitoring.

Characterisation of PZT in Thin Film Bulk Acoustic Wave Resonators

2008 ◽  
Vol 1075 ◽  
Author(s):  
Janine Conde ◽  
Paul Muralt
Keyword(s):  
Thin Films ◽  
Acoustic Wave ◽  
Bias Voltage ◽  
Sol Gel ◽  
Low Frequency ◽  
Bulk Acoustic Wave ◽  
Coupling Constant ◽  
Pzt Thin Films ◽  
Best Response ◽  
And Performance

ABSTRACTPb(Zr0.53, Ti0.47)O3 (PZT) thin films are potentially interesting as piezoelectric layer in bulk acoustic wave (BAW) resonators. We investigated properties and performance of {111} and {100} textured, dense films deposited by sol-gel techniques in the frequency range of 1 to 2 GHz. The resonators were fabricated on Si wafers using deep silicon etching to create a membrane structure and using platinum as top and bottom electrodes. The best response of the resonators was observed at a bias voltage of −15kV/cm with values of around 10% for the coupling constant and around 50 for the quality factor. This voltage corresponds to the maximal value of the piezoelectric constant d33 and minimal value of the dielectric permittivity measured as a function of the electric field. Resonance and antiresonance frequencies were strongly influenced by a bias voltage, showing a hysteretic behaviour as expected for ferroelectrics. Both of these frequencies shifted in the same direction. As a consequence, the dc voltage can be potentially used to shift the whole band of a filter. In unipolar operation, the coupling constant could be varied from 6 to 10 %. Materials parameters were extracted from the admittance as a function of frequency. Dielectric, piezoelectric and elastic properties of textured PZT films are reported and compared to direct (low frequency) measurements and to literature values. It was found that PZT thin films have lower stiffness than the one of PZT bulk ceramics and it was observed that {111}-textured films are stiffer than {100}-textured films.

Simulation Training with Structured Debriefing Improves Residents’ Pediatric Disaster Triage Performance

2012 ◽  
Vol 27 (3) ◽  
pp. 239-244 ◽  
Author(s):  
Mark X. Cicero ◽  
Marc A. Auerbach ◽  
Jason Zigmont ◽  
Antonio Riera ◽  
Kevin Ching ◽  
...  
Keyword(s):  
Educational Intervention ◽  
Simulation Training ◽  
Low Frequency ◽  
Disaster Medicine ◽  
Care Needs ◽  
High Stakes ◽  
Head Injured ◽  
Post Test ◽  
And Performance ◽  
Disaster Scenario

AbstractIntroductionPediatric disaster medicine (PDM) triage is a vital skill set for pediatricians, and is a required component of residency training by the Accreditation Council for Graduate Medical Education (ACGME). Simulation training is an effective tool for preparing providers for high-stakes, low-frequency events. Debriefing is a learner-centered approach that affords reflection on one's performance, and increases the efficacy of simulation training. The purpose of this study was to measure the efficacy of a multiple-victim simulation in facilitating learners’ acquisition of pediatric disaster medicine (PDM) skills, including the JumpSTART triage algorithm. It was hypothesized that multiple patient simulations and a structured debriefing would improve triage performance.MethodsA 10-victim school-shooting scenario was created. Victims were portrayed by adult volunteers, and by high- and low-fidelity simulation manikins that responded physiologically to airway maneuvers. Learners were pediatrics residents. Expected triage levels were not revealed. After a didactic session, learners completed the first simulation. Learners assigned triage levels to all victims, and recorded responses on a standardized form. A group structured debriefing followed the first simulation. The debriefing allowed learners to review the victims and discuss triage rationale. A new 10-victim trauma disaster scenario was presented one week later, and a third scenario was presented five months later. During the second and third scenarios, learners again assigned triage levels to multiple victims. Wilcoxon sign rank tests were used to compare pre- and post-test scores and performance on pre- and post-debriefing simulations.ResultsA total of 53 learners completed the educational intervention. Initial mean triage performance was 6.9/10 patients accurately triaged (range = 5-10, SD = 1.3); one week after the structured debriefing, the mean triage performance improved to 8.0/10 patients (range = 5-10, SD = 1.37, P < .0001); five months later, there was maintenance of triage improvement, with a mean triage score of 7.8/10 patients (SD = 1.33, P < .0001).Over-triage of an uninjured child with special health care needs (CSHCN) (67.8% of learners prior to debriefing, 49.0% one week post-debriefing, 26.2% five months post-debriefing) and under-triage of head-injured, unresponsive patients (41.2% of learners pre-debriefing, 37.5% post-debriefing, 11.0% five months post-debriefing) were the most common errors.ConclusionsStructured debriefings are a key component of PDM simulation education, and resulted in improved triage accuracy; the improvement was maintained five months after the educational intervention. Future curricula should emphasize assessment of CSHCN and head-injured patients.Cicero MX, Auerbach MA, Zigmont J, Riera A, Ching K, Baum CR. Simulation training with structured debriefing improves residents’ pediatric disaster triage performance. Prehosp Disaster Med. 2012;27(3):1-6.

scholarly journals Study on Low-Frequency TEM Effect of Coal during Dynamic Rupture

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Cheng-wu Li ◽  
Chuan Wang ◽  
Bei-jing Xie ◽  
Xiao-yuan Sun ◽  
Xiao-meng Xu
Keyword(s):  
High Strain ◽  
Low Frequency ◽  
Test System ◽  
Test Results ◽  
Dynamic Rupture ◽  
Monitoring Technique ◽  
Shpb Test ◽  
Coal Rock ◽  
And Performance ◽  
Electromagnetic Monitoring

Dynamic loads provided by the SHPB test system were applied to coal specimens, and the TEM signals that emerged during coal rupture were recorded by the TMVT system. Experiments on coal-mass blasting rupture in excavating workface were also carried out, and the emerged TEM signal was analyzed. The results indicate that the low-frequency TEM signals were detected close to the coal specimens under high strain dynamic load applied by the SHPB, initially rising sharply and dropping rapidly, followed by a small tailing turbulence. And the field test results obtained during coal blasting process coincided with the results from the SHPB tests. Furthermore, its initial part shaped like a pulse cluster had a more pronounced tail and lasted even longer. And the generation mechanism of the low-frequency TEM effect was analyzed. It suggests that the low-frequency TEM effect of coal during dynamic rupture is contributed by the fractoemission mechanism and the resonance or waveguide effects. Because its wavelength is longer than the higher ones, the low-frequency TEM has a good anti-interference performance. That can expand the scope and performance of the coal-rock dynamic disaster electromagnetic monitoring technique.

Reading Fluency Estimates of Current Intellectual Function: Demographic Factors and Effects of Type of Stimuli

2013 ◽  
Vol 19 (3) ◽  
pp. 355-361 ◽  
Author(s):  
Panagiotis G. Simos ◽  
Georgios D. Sideridis ◽  
Dimitrios Kasselimis ◽  
Angeliki Mouzaki
Keyword(s):  
Reading Fluency ◽  
Formal Education ◽  
Clinical Sample ◽  
Block Design ◽  
Low Frequency ◽  
Demographic Variables ◽  
Clinical Value ◽  
Intellectual Capacity ◽  
Reading Measures ◽  
And Performance

AbstractThe study explores the potential clinical value of reading fluency measures in complementing demographic variables as indices of current intellectual capacity. IQ estimates (based on the PPVT-R, WASI Vocabulary and Block Design subtests) were obtained from a representative, non-clinical sample of 386 Greek adults aged 48–87 years along with two measures of reading efficiency (one involving relatively high-frequency words—WRE—and the second comprised of phonotactically matched pseudowords—PsWRE). Both reading measures (number of items read correctly in 45 s) accounted for significant portions of variability in demographically adjusted verbal and performance IQ indices. Reading measures provided IQ estimates which were significantly closer to those predicted by demographic variables alone in up to 22% of individuals with fewer than 7 (across all ages) or 13 years of formal education (in the 70–87 year age range). PsWRE scores slightly outperformed WRE scores in predicting a person's estimated verbal or performance IQ. Results are discussed in the context of previous findings using reading accuracy measures for low-frequency words with exceptional spellings in less transparent orthographic systems such as English. (JINS, 2013, 19, 1–7)

scholarly journals Practical Design Considerations for Performance and Robustness in the Face of Uncertain Flexible Dynamics in Space Manipulators

2021 ◽  
Vol 8 ◽  
Author(s):  
Connor Holmes
Keyword(s):  
Control Strategies ◽  
Low Frequency ◽  
Open Loop ◽  
Unmodeled Dynamics ◽  
Loop Control ◽  
Stability Margins ◽  
Flexible Mode ◽  
Space Manipulators ◽  
The Face ◽  
And Performance

Low frequency dynamics introduced by structural flexibility can result in considerable performance degradation and even instability in on-orbit, robotic manipulators. Although there is a wealth of literature that addresses this problem, the author has found that many advanced solutions are often precluded by practical considerations. On the other hand, classical, robust control methods are tractable for these systems if the design problem is properly constrained. This paper investigates a pragmatic engineering approach that evaluates the system’s stability margins in the face of uncertain, flexible perturbation dynamics with frequencies that lie close to or within the bandwidth of the nominal closed-loop system. The robustness of classical control strategies is studied in the context of both collocated (joint rate) and non-collocated (force/torque and vision-based) feedback. It is shown that robust stability and performance depend on the open-loop control bandwidth of the nominal control law (as designed for a simplified, rigid plant). Namely, the designed bandwidth must be constrained to be lower than the minimum flexible mode frequency of the unmodeled dynamics by a given factor. This strategy gives credence to popular heuristic methods commonly used to reduce the effect of unmodeled dynamics in complex manipulator systems.

scholarly journals Design and Analysis of Asynchronous Sampling Duty Cycle Corrector

Electronics ◽  
2021 ◽  
Vol 10 (21) ◽  
pp. 2594
Author(s):  
Gijin Park ◽  
Jaeduk Han ◽  
Woorham Bae
Keyword(s):  
Duty Cycle ◽  
Low Frequency ◽  
Operating Conditions ◽  
Cmos Process ◽  
Asynchronous Sampling ◽  
Operation Conditions ◽  
Correction Scheme ◽  
Control Scheme ◽  
And Performance ◽  
Settling Behavior

This paper presents a duty cycle correction scheme based on asynchronous sampling and associated settling analysis. The proposed duty cycle corrector circuit consumes less power and area compared to other corrector circuits due to the low-frequency operation of asynchronous sampling. However, the settling behavior of an asynchronous sampling duty cycle corrector is limited in some operation conditions, which degrades its robustness and performance. This paper, therefore, performs analysis on the settling behavior of the asynchronous sampling in various operating conditions and proposes a control scheme to avoid the lagged settling. To verify the proposed duty cycle corrector and its analysis, a prototype design is implemented in a 40-nm CMOS process and its performance is verified by post-layout simulations. The proposed duty cycle corrector achieved very small duty cycle errors (less than 0.8%) and consumed 540 uW per one DCC unit.

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