scholarly journals Pilot Studies of Vibrations Induced in Perambulators When Moving on Different Surfaces

2021 ◽  
Vol 11 (16) ◽  
pp. 7746
Author(s):  
Gustaw Sierzputowski ◽  
Radosław Wróbel ◽  
Veselin Mihaylov ◽  
Maciej Janeczek ◽  
Marta Majewska-Pulsakowska ◽  
...  
Keyword(s):  
Free Vibration ◽  
Comfort Level ◽  
Frequency Range ◽  
Internal Organs ◽  
Human Comfort ◽  
Pilot Studies ◽  
Iso Standard ◽  
Resonance Frequencies ◽  
Different Types ◽  
Noise Vibration

The ergonomics of transport is a topic widely described in the literature. One of the fields of ergonomics that researchers are engaged in is vibrometry (both laser and accelerometry) of travel and its translation into NVH (Noise, Vibration and Harshness). However, so far, the influence of baby carriage movement on the generated vibrations has not been described in more detail. The topic seems to be particularly important considering occurrence of vibrations with significant amplitudes, whose frequency range can have a direct bearing on the resonance frequencies of the child’s internal organs. The article presents the results of research consisting in the measurement of vibrations to which an infant, lying in two different types of prams, may be exposed when being transported on different surfaces. The author’s measurement system, based on accelerometry, was used for the research. The obtained weighted RMS acceleration values not only exceeded human comfort level in all cases (according to ISO standard) but several times were in the range of the highest discomfort (>2 m/s2). Furthermore, the observed vibration frequency range (≈0–32 Hz) coincided with the frequencies of free vibration of organs and parts of the child’s body.

High-voltage synthetic inductor for vibration damping in resonant piezoelectric shunt

2020 ◽  
pp. 107754632095261
Author(s):  
Kevin Dekemele ◽  
Patrick Van Torre ◽  
Mia Loccufier
Keyword(s):  
Piezoelectric Material ◽  
High Voltage ◽  
State Of The Art ◽  
Vibration Damping ◽  
Operational Amplifiers ◽  
Frequency Range ◽  
Resonant Condition ◽  
Passive Components ◽  
Resonance Frequencies ◽  
Resonant Shunt

Resonant piezoelectric shunts are a well-established way to reduce vibrations of mechanical systems suffering from resonant condition. The vibration energy is transferred to the electrical domain through the bonded piezoelectric material where it is dissipated in the shunt. Typically, electrical and mechanical resonance frequencies are several orders apart. As such, finding a suitable high inductance component for the resonant shunt is not feasible. Therefore, these high inductance values are mimicked through synthetic impedances, consisting of operational amplifiers and passive components. A downside of these synthetic impedances is that standard operational amplifiers can only handle up to 30 V peak to peak and the state-of-the-art amplifiers up to 100 Vpp. However, as mechanical structures tend to become lighter and more flexible, the order induced voltages over the piezoelectric material electrode voltages increase above these limitations. In this research, a high-voltage synthetic inductor is proposed and built by combining the bridge amplifier configuration and the output voltage boost configuration around a single operational amplifier gyrator circuit, effectively quadrupling the range of the synthetic inductor to 400 Vpp. The impedance of the circuit over a frequency range is numerically and experimentally investigated. The synthetic inductor is then connected to a piezoelectric material bonded to a cantilever beam. Numerical and experimental investigation confirms the high-voltage operation of the implemented circuit and its suitability as a vibration damping circuit.

scholarly journals Results of an intercomparison for free space antenna factor measurements within the German Calibration Service (DKD)

2016 ◽  
Vol 14 ◽  
pp. 11-16
Author(s):  
Thomas Kleine-Ostmann ◽  
Frank Huncke ◽  
Dieter Schwarzbeck ◽  
Otto Martetschläger ◽  
Jürgen Gaßner ◽  
...  
Keyword(s):  
Free Space ◽  
Frequency Range ◽  
Space Antenna ◽  
Different Types ◽  
Antenna Factor

Abstract. In this paper we discuss the results of an intercomparison for free space antenna factor measurements performed within the German Calibration Service (DKD). Three different types of antennas covering the frequency range from 30 MHz to 26.5 GHz have been calibrated in five different laboratories using different methods and calibration sites to obtain the free space antenna factor. The results agree well within the uncertainties specified by the laboratories suggesting that different approaches and different measurement sites to obtain the free space antenna factor are well compatible.

scholarly journals Low Frequency Noise Remove from EEG Signal

2020 ◽  
Vol 9 (1) ◽  
pp. 1510-1513
Keyword(s):  
Human Brain ◽  
Random Noise ◽  
Low Frequency ◽  
Frequency Noise ◽  
Eeg Signal ◽  
Low Frequency Noise ◽  
Frequency Range ◽  
Average Value ◽  
Different Types ◽  
The Brain

The electrical activity of the brain recorded by EEG which used to detect different types of diseases and disorders of the human brain. There is contained a large amount of random noise present during EEG recording, such as artifacts and baseline changes. These noises affect the low -frequency range of the EEG signal. These artifacts hiding some valuable information during analyzing of the EEG signal. In this paper we used the FIR filter for removing low -frequency noise(<1Hz) from the EEG signal. The performance is measured by calculating the SNR and the RMSE. We obtained RMSE average value from the test is 0.08 and the SNR value at frequency(<1Hz) is 0.0190.

scholarly journals Renal Tubular Dysgenesis in a Case of Fetus Acardius Amorphus

2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
C. Thoeni ◽  
K. Holzer ◽  
J. Leichsenring ◽  
C. Porcel ◽  
B. K. Straub ◽  
...  
Keyword(s):  
Blood Flow ◽  
Smooth Muscle Actin ◽  
Extramedullary Hematopoiesis ◽  
Renal Tubular Dysgenesis ◽  
Internal Organs ◽  
Multiple Gestations ◽  
Different Types ◽  
Inner Organs ◽  
Renal Tubular ◽  
Umbilical Arteries

Fetus acardius amorphus is a rare congenital malformation characterized by the lack of a functional heart, the presence of a bivascular umbilical cord, as well as a developed and organized skeletal system and partially organized inner organs. Fetus acardii mostly occur in multiple gestations. The pathogenesis of this entity is not clarified yet. It has been hypothesized that, although formation of anastomosing vessels between the co-twin and the anomalous embryo as well as reverse directed blood flow within the umbilical arteries of the weaker twin may allow sufficient blood flow to form rudimentary internal organs, it is insufficient to develop a fully functional heart. We had a case of fetus acardius amorphus, where we performed autopsy as well as routine histology assessment to identify different types of tissues. We showed that our fetus acardius amorphus demonstrated histomorphological features of renal tubular dysgenesis, confirmed by lack of proximal tubules, extramedullary hematopoiesis and increased number of smooth muscle actin positive vessels. This is a novel finding and has not been reported previously.

scholarly journals System-Level Model and Simulation of a Frequency-Tunable Vibration Energy Harvester

Micromachines ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 91 ◽  
Author(s):  
Sofiane Bouhedma ◽  
Yongchen Rao ◽  
Arwed Schütz ◽  
Chengdong Yuan ◽  
Siyang Hu ◽  
...  
Keyword(s):  
Energy Harvester ◽  
Element Model ◽  
Industrial Applications ◽  
System Level ◽  
Dual Frequency ◽  
Frequency Range ◽  
Vibration Energy Harvester ◽  
Resonance Frequencies ◽  
Level Model ◽  
System Level Model

In this paper, we present a macroscale multiresonant vibration-based energy harvester. The device features frequency tunability through magnetostatic actuation on the resonator. The magnetic tuning scheme uses external magnets on linear stages. The system-level model demonstrates autonomous adaptation of resonance frequency to the dominant ambient frequencies. The harvester is designed such that its two fundamental modes appear in the range of (50,100) Hz which is a typical frequency range for vibrations found in industrial applications. The dual-frequency characteristics of the proposed design together with the frequency agility result in an increased operative harvesting frequency range. In order to allow a time-efficient simulation of the model, a reduced order model has been derived from a finite element model. A tuning control algorithm based on maximum-voltage tracking has been implemented in the model. The device was characterized experimentally to deliver a power output of 500 µW at an excitation level of 0.5 g at the respected frequencies of 63.3 and 76.4 Hz. In a design optimization effort, an improved geometry has been derived. It yields more close resonance frequencies and optimized performance.

Biological treatment of airstreams contaminated with VOCs: an overview

1996 ◽  
Vol 34 (3-4) ◽  
pp. 565-571 ◽  
Author(s):  
Findlay G. Edwards ◽  
N. Nirmalakhandan
Keyword(s):  
The Netherlands ◽  
Biological Treatment ◽  
Buffer Capacity ◽  
Pilot Studies ◽  
Volatile Chemicals ◽  
Biotrickling Filters ◽  
Different Types

Biological treatment of contaminated airstreams is a technology which has been used successfully in Germany and The Netherlands for twenty years. The technology can be utilized in a wide array of industries to treat numerous volatile chemicals. There are three categories of air phase bioreactors: biofilters, biotrickling filters, and bioscrubbers. Addition of nutrients and buffer capacity may be required. Many different types of support media can be used. Currently, design of airphase bioreactors is based upon guidelines, pilot studies, and experience gained from similar applications.

Bandgap Properties of Two-Layered Locally Resonant Phononic Crystals

2020 ◽  
Vol 12 (07) ◽  
pp. 2050075
Author(s):  
Hongyun Wang ◽  
Heow Pueh Lee ◽  
Wei Xu
Keyword(s):  
Coating Thickness ◽  
Low Frequency ◽  
Phononic Crystals ◽  
Formation Mechanisms ◽  
Frequency Range ◽  
The Third ◽  
Resonance Frequencies ◽  
Rubber Coating ◽  
Lower Frequency Range ◽  
Mass Spring

Multi-layered locally resonant phononic crystals (LRPCs) with wider and multiple bandgaps (BGs) in low frequency range and small size of the unit cell have promising applications in noise and vibration controls. In this paper, a 2D two-layered ternary LRPC consisting of a periodical array of cylindrical inclusions embedded in an epoxy matrix is investigated by the finite element method (FEM), where the inclusion is comprised of two coaxial cylindrical steel cores with rubber coating. It is found that the size of the inclusion of the 2D two-layered ternary LRPC has significant effects on the BG properties. With the increase of the core radius and coating thickness, the first BG would shift to lower frequency range with its width decreasing, and the second BG width would become wider until the third BG appears. Especially, with the increase of the coating thickness, more bands and BGs would appear in the lower frequency range. Based on the formation mechanisms of the BGs, several mass-spring models to predict the frequencies of the first two BG edges are developed. The results calculated by these mass-spring models are in good agreement with those by the FEM except for the upper edge frequency of the second BG when the rubber coating thickness exceeds a certain value and the third BG is opened up. These proposed mass-spring models would allow for quick pre-estimation of the resonance frequencies, and facilitate the selection of possible parameters for the wider and lower frequency BGs to obtain the desired attenuation bands. The studies would also benefit the design of multiple BGs for some device applications.

scholarly journals Companion Animals as Models for Inhibition of STAT3 and STAT5

Cancers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2035 ◽  
Author(s):  
Matthias Kieslinger ◽  
Alexander Swoboda ◽  
Nina Kramer ◽  
Barbara Pratscher ◽  
Birgitt Wolfesberger ◽  
...  
Keyword(s):  
Companion Animals ◽  
Clinical Signs ◽  
Human Diseases ◽  
Pilot Studies ◽  
Human Counterpart ◽  
Different Types ◽  
Safety Studies ◽  
Human Use ◽  
Trial Phase ◽  
Stat Pathway

The use of transgenic mouse models has revolutionized the study of many human diseases. However, murine models are limited in their representation of spontaneously arising tumors and often lack key clinical signs and pathological changes. Thus, a closer representation of complex human diseases is of high therapeutic relevance. Given the high failure rate of drugs at the clinical trial phase (i.e., around 90%), there is a critical need for additional clinically relevant animal models. Companion animals like cats and dogs display chronic inflammatory or neoplastic diseases that closely resemble the human counterpart. Cat and dog patients can also be treated with clinically approved inhibitors or, if ethics and drug safety studies allow, pilot studies can be conducted using, e.g., inhibitors of the evolutionary conserved JAK-STAT pathway. The incidence by which different types of cancers occur in companion animals as well as mechanisms of disease are unique between humans and companion animals, where one can learn from each other. Taking advantage of this situation, existing inhibitors of known oncogenic STAT3/5 or JAK kinase signaling pathways can be studied in the context of rare human diseases, benefitting both, the development of drugs for human use and their application in veterinary medicine.

Effects of tip relief on vibration responses of a geared rotor system

2013 ◽  
Vol 228 (7) ◽  
pp. 1132-1154 ◽  
Author(s):  
Hui Ma ◽  
Jian Yang ◽  
Rongze Song ◽  
Suyan Zhang ◽  
Bangchun Wen
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Spur Gear ◽  
Rotor System ◽  
Time Varying ◽  
Frequency Range ◽  
Mesh Stiffness ◽  
Resonance Frequencies ◽  
Vibration Responses

Considering tip relief, a finite element model of a spur gear pair in mesh is established by ANSYS software. Time-varying mesh stiffness under different amounts of tip relief is calculated based on the finite element model. Then, a finite element model of a geared rotor system is developed by MATLAB software considering the effects of time-varying mesh stiffness and constant load torque. Emphasis is given to the effects of tip relief on the lateral–torsional coupling vibration responses of the system. The results show that as the amount of tip relief increases, the saltation of time-varying mesh stiffness reduces at the position of approach action and transition mesh region from the single tooth to double tooth. A number of primary resonances and some super-harmonic of gears 1 and 2 are excited by time-varying mesh stiffness in amplitude frequency responses. As the amount of tip relief increases, some super-harmonic responses change due to the variation in the higher frequency components of time-varying mesh stiffness. After tip relief, the vibration and meshing force decrease obviously at lower mesh frequency range except at some resonance frequencies; however, tip relief is not effective in reducing the vibration at higher mesh frequency range. The amplitude fluctuation of the vibration acceleration reduces evidently after considering tip relief, which is not remarkable with the increase of meshing frequency.

Influence of various multilayer LTCC systems on dielectric properties’ stability in GHz frequency range

2016 ◽  
Vol 33 (3) ◽  
pp. 136-140 ◽  
Author(s):  
Tibor Rovensky ◽  
Alena Pietrikova ◽  
Igor Vehec ◽  
Martin Kmec
Keyword(s):  
Dielectric Properties ◽  
Design Methodology ◽  
Middle Layer ◽  
Ring Resonators ◽  
Frequency Range ◽  
Content Type ◽  
Different Types ◽  
Good Repeatability ◽  
Microstrip Ring ◽  
Multilayer Substrate

Purpose The purpose of this paper is to create multilayer substrate (composite) from various low temperature co-fired ceramic (LTCC) substrates by their mutual combinations and to analyse influence of these multilayer substrates on dielectric properties in GHz frequency range. Design/methodology/approach GreenTape 951, GreenTape 9K7 and Murata LFC were used to create compound multilayer substrates that include three layers: middle layer is from Murata LFC, and both upper and bottom layers are either from GreenTape 951 or GreenTape 9K7. Shrinkage in all x-, y- and z-axes of all substrates including multilayer substrates were analysed, and influence of different shrinkage on dielectric properties was examined by microstrip ring resonators applied on all mentioned of substrates. Findings The middle layer of Murata LFC has significant influence on shrinkage value of composites which has a good repeatability and minimalizes problems with design of multilayer LTCC devices. Impact of middle layer from Murata LFC on dielectric constant is not significant, but on the other hand Q factor (loss tangent) of these composites is increased according to inhomogeneity between single LTCC layers, especially at frequency around 6 GHz. Originality/value The novelty of this work lies in creating multilayers systems from different types of LTCC substrates to find combination with the most suitable physical and dielectric properties for various purposes in GHz range applications.

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