scholarly journals Improvement of Pressing Technology of Products from Polytetrafluoroethylene

2001 ◽  
Vol 14 (5) ◽  
pp. 564-571
Author(s):  
Dmitriy A. Negrov ◽  
Keyword(s):  
Amplitude Modulation ◽  
New Technology ◽  
Low Frequency ◽  
Modern Material ◽  
Simultaneous Application ◽  
New Methods ◽  
Friction Units ◽  
The Coefficient Of Friction ◽  
Modern Material Science ◽  
Pressing Technology

The development of new methods for obtaining materials with predetermined operational properties that ensure the durability and the wear resistance of friction units is an urgent problem in modern material science. The article considers the effect of ultrasonic pressing modes with simultaneously superimposed low-frequency amplitude modulation on the mechanical and tribotechnical properties of polytetrafluoroethylene. The comparison of the obtained research results of the new technology is carried out with the traditional pressing technology. The results of studies indicated that the technology of ultrasonic pressing with the simultaneous application of low-frequency amplitude modulation makes it possible to increase the mechanical properties of PTFE: the tensile strength by 15 %, elongation by 13 %, the elastic modulus by 8 %, the hardness by 12 %, while the intensity of the mass wear rate is reduced by 40 %, and the coefficient of friction by 27 %

Antimicrobial Activities of Metal Containing Compounds and Hybrids

2020 ◽  
Vol 26 (45) ◽  
pp. 5881-5891
Author(s):  
Tahseen Kamal ◽  
Sher Bahadar Khan ◽  
Abdullah M. Asiri
Keyword(s):  
Growth Inhibition ◽  
Mode Of Action ◽  
Material Science ◽  
Antimicrobial Activities ◽  
Excellent Performance ◽  
Modern Material ◽  
Modern Material Science

Normally, antibiotics are used for the growth inhibition of a variety of pathogens. The ever- increasing resistance of the various disease-causing pathogens to the antibiotics has drawn tremendous attention of researchers to find efficient alternatives. The recent era of modern material science and nanotechnology has made it possible to replace the existing antibiotics up to some extent. Currently, a vast library of materials has been prepared, which shows excellent performance against pathogens. Such materials consist of certain metals. Through this review, we present some notable studies concerning the antimicrobial activities of various metal containing compounds and their mode of action.

Multiple-S-Shaped Critical Manifold and Jump Phenomena in Low Frequency Forced Vibration with Amplitude Modulation

2019 ◽  
Vol 29 (05) ◽  
pp. 1930012 ◽  
Author(s):  
Yue Yu ◽  
Qianqian Wang ◽  
Qinsheng Bi ◽  
C. W. Lim
Keyword(s):  
Amplitude Modulation ◽  
Large Amplitude ◽  
Low Frequency ◽  
Slow Variable ◽  
Critical Manifold ◽  
Singular Orbit ◽  
Modulation Control ◽  
Cycle Oscillation ◽  
Tuning Frequency ◽  
Complex Mechanical Systems

Motivated by the forced harmonic vibration of complex mechanical systems, we analyze the dynamics involving different waves in a double-well potential oscillator coupling amplitude modulation control of low frequency. The combination of amplitude modulation factor significantly enriches the dynamical behaviors on the formation of multiple-S-shaped manifold and multiple jumping phenomena that alternate between epochs of slow and fast motion. We can conduct bifurcation analysis to identify two harmonic vibrations. One is that the singular orbit makes multiple jumps to a fast trajectory segment from one attracting equilibrium to another as the expression of slow variable by using the DeMoivre formula. With the increase of tuning frequency, the system exhibits relaxation-type oscillations whose small amplitude oscillations are produced by nonlinear local cycles together with a distinct large amplitude cycle oscillation accounting for the Melnikov threshold values. The tuning frequency may not only affect the asymptotic expressions for the solution curves near fold singularities but also allow for the large amplitude orbit vibrations near fold-cycle singularities. Numerical analysis for computing critical manifolds and their intersections is used to detect the dynamical features in this paper.

A Geometric Parametric Analysis of a Magnetorheological Engine Mount

2010 ◽  
Author(s):  
Walter Anderson ◽  
Constantine Ciocanel ◽  
Mohammad Elahinia
Keyword(s):  
High Frequency ◽  
New Technology ◽  
Low Frequency ◽  
Variable Stiffness ◽  
Small Displacement ◽  
Element Analysis ◽  
Mr Fluid ◽  
Wide Range ◽  
Engine Mount ◽  
Vehicle Technology

Engine vibration has caused a great deal of research for isolation to be performed. Traditionally, isolation was achieved through the use of pure elastomeric (rubber) mounts. However, with advances in vehicle technology, these types of mounts have become inadequate. The inadequacy stems from the vibration profile associated with the engine, i.e. high displacement at low frequency and small displacement at high frequency. Ideal isolation would be achieved through a stiff mount for low frequency and a soft mount for high frequency. This is contradictory to the performance of the elastomeric mounts. Hydraulic mounts were then developed to address this problem. A hydraulic mount has variable stiffness and damping due to the use of a decoupler and an inertia track. However, further advances in vehicle technology have rendered these mounts inadequate as well. Examples of these advances are hybridization (electric and hydraulic) and cylinder on demand (VCM, MDS & ACC). With these technologies, the vibration excitation has a significantly different profile, occurs over a wide range of frequencies, and calls for a new technology that can address this need. Magnetorheological (MR) fluid is a smart material that is able to change viscosity in the presence of a magnetic field. With the use of MR fluid, variable damping and stiffness can be achieved. An MR mount has been developed and tested. The performance of the mount depends on the geometry of the rubber part as well as the behavior of the MR fluid. The rubber top of the mount is the topic of this study due to its major impact on the isolation characteristics of the MR mount. To develop a design methodology to address the isolation needs of different hybrid vehicles, a geometric parametric finite element analysis has been completed and presented in this paper.

scholarly journals Notched-noise precursors improve detection of low-frequency amplitude modulation

2017 ◽  
Vol 141 (1) ◽  
pp. 324-333 ◽  
Author(s):  
Ali Almishaal ◽  
Gavin M. Bidelman ◽  
Skyler G. Jennings
Keyword(s):  
Amplitude Modulation ◽  
Low Frequency

scholarly journals Monitoring the Impact of Electromagnetic Waves on Yield and Quality in Maize

2011 ◽  
Vol 68 (1) ◽  
Author(s):  
Florin IMBREA ◽  
Branko MARINCOVIC ◽  
Valeriu TABĂRĂ ◽  
PAUL PÎRŞAN ◽  
Gheorghe DAVID ◽  
...  
Keyword(s):  
Protein Content ◽  
Quality Indicators ◽  
Electromagnetic Waves ◽  
Starch Content ◽  
New Technology ◽  
Low Frequency ◽  
Cultivation Method ◽  
Yield And Quality ◽  
The Impact ◽  
Starch Yield

Experimenting new technology of cultivating maize is an important step forward in order to optimise the yielding capacity if a crop that ranks second among crops cultivated worldwide and first among crops cultivated in Romania. Using low frequency radiations to stimulate yield and quality in maize allows increases in yield between 10 and 15% compared to the classical cultivation method and an improvement of the quality indicators (protein content increased with 6-11% determining an increase of the protein yield per ha; starch content increased with 7-14%, which also determined an increase of the starch yield per ha; while fat content, another indicator we monitored, increased with 2-6%).

scholarly journals SeMSA: a compact super absorber optimised for broadband, low-frequency noise attenuation

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Andrew McKay ◽  
Ian Davis ◽  
Jack Killeen ◽  
Gareth J. Bennett
Keyword(s):  
New Technology ◽  
Perforated Plate ◽  
Low Frequency ◽  
Broadband Noise ◽  
Frequency Noise ◽  
Noise Attenuation ◽  
Loss Mechanism ◽  
Small Form Factor ◽  
Broadband Sound ◽  
Sub Wavelength

Abstract The attenuation of low-frequency broadband noise in a light, small form-factor is an intractable challenge. In this paper, a new technology is presented which employs the highly efficient visco-thermal loss mechanism of a micro-perforated plate (MPP) and successfully lowers its frequency response by combining it with decorated membrane resonators (DMR). Absorption comes from the membranes but primarily from the MPP, as the motion of the two membranes causes a pressure differential across the MPP creating airflow through the perforations. This combination of DMR and MPP has led to the Segmented Membrane Sound Absorber (SeMSA) design, which is extremely effective at low-frequency broadband sound absorption and which can achieve this at deep sub-wavelength thicknesses. The technology is compared to other absorbers to be found in the literature and the SeMSA outperforms them all in either the 20–1000 Hz or 20–1200 Hz range for depths of up to 120 mm. This was verified through analytical, finite element and experimental analyses.

scholarly journals The Phenomena of High Energy Astrophysics

2003 ◽  
Vol 214 ◽  
pp. 3-20 ◽  
Author(s):  
R. D. Blandford
Keyword(s):  
Supernova Remnants ◽  
New Technology ◽  
Low Frequency ◽  
Cosmic Ray ◽  
High Energy ◽  
Galactic Cosmic Rays ◽  
High Energy Astrophysics ◽  
Physical Conditions ◽  
Hot Gas ◽  
Neutrino Astronomy

A brief summary of some highlights in the study of high energy astrophysical sources over the past decade is presented. It is argued that the great progress that has been made derives largely from the application of new technology to observation throughout all of the electromagnetic and other spectra and that, on this basis, the next decade should be even more exciting. However, it is imperative to observe cosmic sources throughout these spectra in order to obtain a full understanding of their properties. In addition, it is necessary to learn the universal laws that govern the macroscopic and the microscopic behavior of cosmic plasma over a great range of physical conditions by combining observations of different classes of source. These two injunctions are illustrated by discussions of cosmology, hot gas, supernova remnants and explosions, neutron stars, black holes and ultrarelativistic outflows. New interpreations of the acceleration of Galactic cosmic rays, the cooling of hot gas in rich clusters and the nature of ultrarelativistic outflows are outlined. The new frontiers of VHE γ-ray astronomy, low frequency radio astronomy, neutrino astronomy, UHE cosmic ray physics and gravitational wave astronomy are especially promising.

Dialogue and Collaboration with ECVAM: The View of the EFPIA

2002 ◽  
Vol 30 (2_suppl) ◽  
pp. 195-198
Author(s):  
Bernward Garthoff
Keyword(s):  
European Union ◽  
Technology Development ◽  
New Technology ◽  
Past Experience ◽  
European Federation ◽  
New Methods ◽  
Research Areas ◽  
Umbrella Organisation ◽  
The Future ◽  
Pharmaceutical Industries

An evaluation is presented of past experience of dialogue and collaboration between ECVAM and the European Federation of Pharmaceutical Industries and Associations (EFPIA) over the last nine years. Lessons learnt from the viewpoint of EFPIA company representatives are given. Also, proposals for the future ECVAM approach are made, such as support for other research areas for new methods to be validated, giving realistic statements to ECVAM's European Union and external customers, and being open to any new technology development that might help in opening and establishing new alternative avenues. Finally, the need for proper publications on the implementation of alternatives is recommended, for example, through the existing national platforms and their umbrella organisation, ecopa.

The Preparation and Low-Frequency Vibrational Spectra of Some Copper(I) and Silver(I) Alkane- and Arene-monothiolate Complexes

1979 ◽  
Vol 32 (7) ◽  
pp. 1443 ◽  
Author(s):  
GA Bowmaker ◽  
L Tan
Keyword(s):  
Raman Spectra ◽  
Infrared Spectra ◽  
Vibrational Spectra ◽  
Low Frequency ◽  
Far Infrared ◽  
New Methods ◽  
Thiolate Complexes ◽  
New Compounds ◽  
First Time ◽  
Far Infrared Spectra

A number of different methods for preparing anionic Group 1B metal thiolate complexes have been investigated. The compounds [Me4N] [CU2(SMe)3] and [Et4N] [Ag5(SBut)6] are reported for the first time, and new methods for preparing the previously known compounds [Et4N] [Cu5(SBut)6], [Me4N]2 [CU5(SPh)7] and [Et4N]2 [Cu5(SPh)7] are described. The far-infrared spectra of the above compounds, and of CuSMe, CuSBut, AgSBut, [Me4N]2 [CU4(SPh)6] and [Me4N]2 [Ag5(SPh)7] have been obtained, and metal-sulfur stretching bands are assigned in the 150-350 cm-1 region. The low-frequency Raman spectra have also been obtained for some of these compounds. Possible structures for the new compounds are considered in the light of the low-frequency vibrational spectra.

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