Energy Absorption of Vibration in the Hand for Higher Frequencies

1996 ◽  
Vol 15 (2) ◽  
pp. 71-79 ◽  
Author(s):  
Anna SöRensson ◽  
Lage Burström
Keyword(s):  
Energy Absorption ◽  
High Frequency ◽  
Measurement Method ◽  
Vibration Energy ◽  
Frequency Range ◽  
Measurement And Analysis ◽  
Method Of Measurement ◽  
High Frequency Vibrations ◽  
Noise Vibration ◽  
Male Subjects

The aim of this study has been to develop a measurement method to study the absorption of vibration energy on exposure to high frequency vibrations. The developed measurement method consists of specially constructed equipment for measurement and analysis of the subject's absorption of vibration energy. In this study the energy absorption from the exposure to white noise vibration within the frequency-range 20 to 5000 Hz has been studied. Five female and five male subjects were involved in this study. The results show that the developed method of measurement works satisfactorily and gives reliable results for the energy absorption within the frequency-range 20 to 4000 Hz. Furthermore, the results show that the subjects absorb vibration energy even for frequencies above 1000 Hz. The results also show that the energy absorption is dependent upon factors such as gender, the level of the vibration and the frequency.

scholarly journals High Frequency Modal Testing of the Multiblade Packets Using a Noncontact Measurement and Excitation System

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
C. H. Liu ◽  
C. Zang ◽  
F. Li ◽  
E. P. Petrov
Keyword(s):  
High Frequency ◽  
Measurement Method ◽  
Natural Frequencies ◽  
Spectral Lines ◽  
Modal Testing ◽  
Frequency Resolution ◽  
Mode Shapes ◽  
Finite Model ◽  
Frequency Range ◽  
Noncontact Measurement

High cycle failure of blades and vanes caused by the vibration is one of the major causes reducing the lifetime of turbomachines. For multiblade packets, the failure may occur at vibrations with high frequencies that can reach up to tens of kHz. The experimental modal testing of blades is crucial for the validation of numerical models and for the optimization of turbomachine design. In this paper, the test rig and procedure for measurements of dynamic characteristics of lightweight multiblade packets in wide and high frequency ranges are developed. The measurements are based on a noncontact excitation and noncontact measurement method, which allows the determination of the modal characteristics of the packets with high accuracy in wide frequency ranges. The responses of the multiblade packets are measured using a Scanning Laser Doppler Vibrometry (SLDV), while vibrations are excited by the acoustic excitation technique. Modal tests of the blade packet comprising 18 vane blades connected by shrouds are performed. The measurements are performed within the high frequency range of 0–30 kHz, and the natural frequencies and mode shapes are obtained for first 97 modes. To capture the complex high frequency blade mode shapes, each blade in the packet is scanned over 25 reference points uniformly distributed over the blade concave surface. In order to obtain the high frequency resolution, the frequency range used for the measurements is split into several frequency intervals accordingly to the number of spectral lines available in the used data acquisition system, and for each such interval, the test is performed separately. The finite model of the packet is created, and the numerical modal analysis is performed to compare the calculated natural frequencies and mode shapes with the experimental measurements. The comparison shows the satisfactory with those from finite element analysis. It illustrates the measurement method described in this work is effective and reliable.

On the Effect of Cardboard Liners on Impact-Induced High Frequency Vehicular Driveline Vibrations

2007 ◽  
Author(s):  
Stephanos Theodossiades ◽  
Homer Rahnejat ◽  
Patrick Kelly
Keyword(s):  
Short Duration ◽  
High Frequency ◽  
Modern Trend ◽  
Component Level ◽  
Contact Behaviour ◽  
Foam Filled ◽  
High Frequency Vibrations ◽  
Metallic Wires ◽  
Noise Vibration ◽  
Fea Analysis

A typical driveline Noise, Vibration and Harshness (NVH) spectrum contains the contribution of a significant number of vibration components, ranging from a few Hz to several kHz. This is due to different NVH phenomena that have their causes in the contact behaviour of discrete driveline components. A short duration, audible, high frequency, elastoacoustic phenomenon, which occurs as a load reversal in the presence of lashes in the driveline, is onomatopoeically known in industry as clonk (300–5,000 Hz). Its short duration acts as an impulse that excites a large number of structural modes of the lightly damped driveline system. The above phenomenon has become a major concern to automobile manufacturers in recent years with the modern trend of reducing inertial effects in powertrain systems by use of materials of lower elastic moduli and thinner sections. The most common approach in industry to reduce the radiated clonk noise is by using palliatives, such as metallic wires, foam-filled driveshafts, the Dual Mass Flywheel (DMF) and cardboard liners. However, the mechanisms of vibration and noise reduction that the above palliatives introduce have not been fully understood yet, as these are rather used in an empirical manner. This paper investigates the effect of cardboard liners on the high frequency driveline response, by a combined study of FEA analysis at component level and experimental measurements in a drivetrain rig. The results reveal that cardboard liners reduce the severity of the driveline high frequency vibrations, as well as the number of the driveshafts’ structural modes that are excited by remote impacting of the drivetrain components through their lash zones. The predicted and observed effect of the cardboard liners shows good conformance with the existing literature.

scholarly journals Accelerometer profile of motion of the pelvic girdle in breaststroke swimming

2016 ◽  
Vol 52 (1) ◽  
pp. 147-156 ◽  
Author(s):  
Zbigniew Staniak ◽  
Krzysztof Buśko ◽  
Michał Górski ◽  
Anna Pastuszak
Keyword(s):  
Measurement Method ◽  
Elite Athletes ◽  
Technical Skills ◽  
Pelvic Girdle ◽  
Recording Device ◽  
Good Tool ◽  
Swimming Motion ◽  
Measurement And Analysis ◽  
Biomechanical Evaluation ◽  
Method Of Measurement

Abstract The aim of the study was to develop a method for measurement and analysis of kinematics of the pelvic girdle movement in breaststroke swimming to support training of technical skills. The measurements were performed in five elite breaststroke swimmers. A recording device for triaxial accelerations and triaxial rotational angular velocity was mounted on the dorsal part of the pelvic girdle of the athlete. The task of the athlete was to swim one length of the 50 m swimming pool with the intensity similar to competition. From the consecutive cycles of swimming motion, we developed individual mean graphical and numerical profiles of the kinematics of the pelvic girdle movement within the average cycle. Mean basic values of the characteristics were compared with the values documented in the literature obtained by means of the video analysis or using the method of measurement of the velocity of the unwound rope. The comparison revealed that the results in the group studied were very similar to the results obtained using other methods and were typical of elite athletes. Analysis of the motion profiles for the pelvic girdle in breaststroke swimmers indicated that the results obtained reflected individual technique of performing individual phases of swimming cycles. The proposed measurement method, presentation and analysis of the profile of the pelvic girdle motion in breaststroke swimming represents a good tool for fast and effective biomechanical evaluation of motion technique components.

scholarly journals A review of accurate phase measurement methods and instruments for sinewave signals

ACTA IMEKO ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 52
Author(s):  
Eulalia Balestrieri ◽  
Luca De Vito ◽  
Francesco Picariello ◽  
Sergio Rapuano ◽  
Ioan Tudosa
Keyword(s):  
Measurement Uncertainty ◽  
High Frequency ◽  
Measurement Method ◽  
Essential Role ◽  
Scientific Literature ◽  
Phase Measurement ◽  
Measurement Methods ◽  
Frequency Range ◽  
Electronic Instrumentation ◽  
Response Testing

<p class="Abstract">The phase measurement of sinewave signals is important in  several applications, such as electric and electronic instrumentation; telecommunications; and optical interferometry. The uncertainty of the phase measurement has an essential role in ensuring the suitable performance of the devices and systems used by the relevant application. Some highly accurate phase measurement methods have been developed and implemented in different instrument types that are currently available on the market or have been proposed in the scientific literature, each capable of covering very different frequency ranges. This article presents an overview of these methods and instruments in order to highlight the characteristics in terms of the measurement uncertainty of the main methods and instruments that are used, by taking into account a varying operative frequency range. The standard deviations considered in the surveyed literature are used to identify a phase measurement method that is capable of covering a large high-frequency range, simultaneously maintaining a low value of measurement uncertainty, as requested by some applications (like waveform recorder frequency response testing).</p>

Evaluation of Special Hearing Aids for Deaf Children

1971 ◽  
Vol 36 (4) ◽  
pp. 527-537 ◽  
Author(s):  
Norman P. Erber
Keyword(s):  
Hearing Aids ◽  
High Frequency ◽  
Hearing Aid ◽  
Low Frequency ◽  
Acoustic Stimulation ◽  
Deaf Children ◽  
Frequency Range ◽  
Frequency Limit ◽  
Unpublished Studies ◽  
Published Research

Two types of special hearing aid have been developed recently to improve the reception of speech by profoundly deaf children. In a different way, each special system provides greater low-frequency acoustic stimulation to deaf ears than does a conventional hearing aid. One of the devices extends the low-frequency limit of amplification; the other shifts high-frequency energy to a lower frequency range. In general, previous evaluations of these special hearing aids have obtained inconsistent or inconclusive results. This paper reviews most of the published research on the use of special hearing aids by deaf children, summarizes several unpublished studies, and suggests a set of guidelines for future evaluations of special and conventional amplification systems.

Simulation of vibration piercing of pipe blank at press

2020 ◽  
Vol 76 (11) ◽  
pp. 1128-1138
Author(s):  
S. R. Rakhmanov
Keyword(s):  
High Frequency ◽  
Deformation Zone ◽  
Pipe Blank ◽  
Equipment Operation ◽  
Metal Deformation ◽  
Technological Tool ◽  
High Frequency Vibrations ◽  
Pipe Blanks ◽  
Wave Phenomena

In some cases, the processes of piercing or expanding pipe blanks involve the use of high-frequency active vibrations. However, due to insufficient knowledge, these processes are not widely used in the practice of seamless pipes production. In particular, the problems of increasing the efficiency of the processes of piercing or expanding a pipe blank at a piercing press using high-frequency vibrations are being solved without proper research and, as a rule, by experiments. The elaboration of modern technological processes for the production of seamless pipes using high-frequency vibrations is directly related to the choice of rational modes of metal deformation and the prediction resistance indicators of technological tools and the reliability of equipment operation. The creation of a mathematical model of the process of vibrating piercing (expansion) of an axisymmetric pipe blank at a piercing press of a pipe press facility is an actual task. A calculation scheme for the process of piercing a pipe plank has been elaborated. A dependence was obtained characterizing the speed of front of plastic deformation propagation on the speed of penetration of a vibrated axisymmetric mandrel into the pipe workpiece being pierced. The dynamic characteristics of the occurrence of wave phenomena in the metal being pierced under the influence of a vibrated tool have been determined, which significantly complements the previously known ideas about the stress-strain state of the metal in the deformation zone. The deformation fields in the zones of the disturbed region of the deformation zone were established, taking into account the high-frequency vibrations of the technological tool. It has been established that the choice of rational parameters (amplitude-frequency characteristics) of the vibration piercing process of a pipe blank results in significant increase in the efficiency of the process, the durability of the technological tool and the quality of the pierced blanks.

HIGH FREQUENCY OHMIC LOSSES IN TERAHERTZ FREQUENCY RANGE CW KLYNOTRONS

2017 ◽  
Vol 76 (10) ◽  
pp. 929-940 ◽  
Author(s):  
Yu. S. Kovshov ◽  
S. S. Ponomarenko ◽  
S. A. Kishko ◽  
A. A. Likhachev ◽  
S. A. Vlasenko ◽  
...  
Keyword(s):  
High Frequency ◽  
Terahertz Frequency ◽  
Frequency Range ◽  
Terahertz Frequency Range ◽  
Ohmic Losses

scholarly journals An Improved Time Integration Method Based on Galerkin Weak Form with Controllable Numerical Dissipation

2021 ◽  
Vol 11 (4) ◽  
pp. 1932
Author(s):  
Weixuan Wang ◽  
Qinyan Xing ◽  
Qinghao Yang
Keyword(s):  
High Frequency ◽  
Integration Method ◽  
Time Integration ◽  
Low Frequency ◽  
Weak Form ◽  
High Accuracy ◽  
Numerical Dissipation ◽  
Frequency Range ◽  
Time Integration Method ◽  
Numerical Damping

Based on the newly proposed generalized Galerkin weak form (GGW) method, a two-step time integration method with controllable numerical dissipation is presented. In the first sub-step, the GGW method is used, and in the second sub-step, a new parameter is introduced by using the idea of a trapezoidal integral. According to the numerical analysis, it can be concluded that this method is unconditionally stable and its numerical damping is controllable with the change in introduced parameters. Compared with the GGW method, this two-step scheme avoids the fast numerical dissipation in a low-frequency range. To highlight the performance of the proposed method, some numerical problems are presented and illustrated which show that this method possesses superior accuracy, stability and efficiency compared with conventional trapezoidal rule, the Wilson method, and the Bathe method. High accuracy in a low-frequency range and controllable numerical dissipation in a high-frequency range are both the merits of the method.

scholarly journals Band notched self complementaryultra wideband antenna for wireless applications

2018 ◽  
Vol 7 (2.8) ◽  
pp. 529 ◽  
Author(s):  
Ch Ramakrishna ◽  
G A.E.Satish Kumar ◽  
P Chandra Sekhar Reddy
Keyword(s):  
High Frequency ◽  
Return Loss ◽  
Wide Band ◽  
Ultra Wideband ◽  
Impedance Bandwidth ◽  
Relative Dielectric Permittivity ◽  
Frequency Range ◽  
Ground Structure ◽  
Wireless Applications ◽  
Patch Edge

This paper presents a band notched WLAN self complementaryultra wide band antenna for wireless applications. The proposed antenna encounters a return loss (RL) less than -10dB for entire ultra wideband frequency range except band notched frequency. This paper proposes a hexagon shape patch, edge feeding, self complementary technique and defective ground structure. The antenna has an overall dimensionof 28.3mm × 40mm × 2mm, builton  substrate FR4 with a relative dielectric permittivity 4.4. And framework is simulated finite element method with help of high frequency structured simulator HFSSv17.2.the proposed antenna achieves a impedance bandwidth of 8.6GHz,  band rejected WLAN frequency range 5.6-6.5 GHz with  vswr is less than 2.

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