Impact of external excitations on the dynamic properties of negative-stiffness vibration Isolation table

This paper presents a study of the efficiency of a negative-stiffness vibration isolation table Minus K 500BM-1 in the frequency range of 2–110 Hz. An overview of other possible methods of vibration isolation is provided. Experimental testing of vibration transmissibility was conducted. Special vibration excitation equipment was tested, which enables the planned studies of the object in question to be carried out

Research of dynamics of the vibration isolation platform

Performance of negative-stiffness vibroisolating table „Minus K500BM-1“ was analyzed in a frequency range of 2-110 Hz. The paper also reviewed other possible ways of vibroisolation. Performed experimental vibrations transmissibility tests were reported as well. A special vibration excitation equipment was tested in research facilities. Subsequently, experimental test methods were described together with presentation of results and conclusions of experimental analysi

Comparable analysis of vibrodiagnostic results of rotary components with different type bearings

"Comparable vibrodiagnostic results of rotor components of technological machines with bearings of tilting-pad journal bearing, sleeve liquid-friction and of roll are given in this work. Sliding of roll of researching technological machines are described; the main characteristics of work and photo are given. Experimental comparable vibrodiagnostics measurements are done. Primary signals of measurement are gotten doing vibrodiagnostic measurements, using different programmable pockets they are transformed to other formats of data. Getting results of measurement are systematized and its analysis is done. Comparison of getting results is done and dependence of work characteristics between rotary systems with bearings of sledding friction and of roll is ascertained. Generalization of results of vibrodiagnostic researches is done and conclusions are formulated in the end of this work

Impact of external excitations on the dynamic properties of negative-stiffness vibration Isolation table

This paper presents a study of the efficiency of a negative-stiffness vibration isolation table Minus K 500BM-1 in the frequency range of 2–110 Hz. An overview of other possible methods of vibration isolation is provided. Experimental testing of vibration transmissibility was conducted. Special vibration excitation equipment was tested, which enables the planned studies of the object in question to be carried out

Research of positioning accuracy of robot MOTOMAN SSF2000

Research of the dynamic properties, positioning precision and repeatability of MOTOMAN SSF2000 movement is presented in this article. Dynamic properties were analyzed using a mobile equipment of measuring „Machine Diagnostic Toolbox Type 9727“ with a DELL notebook. The manipulator vibrations were measured in two robot’s positions: vertical and horizontal, and at three different speeds. The research was made under three different conditions, changing the tool mass and spee

Persistent cAMP-Signals Triggered by Internalized G-Protein–Coupled Receptors

Real-time monitoring of G-protein-coupled receptor (GPCR) signaling in native cells suggests that the receptor for thyroid stimulating hormone remains active after internalization, challenging the current model for GPCR signaling

Conserved expression and functions of PDE4 in rodent and human heart

PDE4 isoenzymes are critical in the control of cAMP signaling in rodent cardiac myocytes. Ablation of PDE4 affects multiple key players in excitation–contraction coupling and predisposes mice to the development of heart failure. As little is known about PDE4 in human heart, we explored to what extent cardiac expression and functions of PDE4 are conserved between rodents and humans. We find considerable similarities including comparable amounts of PDE4 activity expressed, expression of the same PDE4 subtypes and splicing variants, anchoring of PDE4 to the same subcellular compartments and macromolecular signaling complexes, and downregulation of PDE4 activity and protein in heart failure. The major difference between the species is a fivefold higher amount of non-PDE4 activity in human hearts compared to rodents. As a consequence, the effect of PDE4 inactivation is different in rodents and humans. PDE4 inhibition leads to increased phosphorylation of virtually all PKA substrates in mouse cardiomyocytes, but increased phosphorylation of only a restricted number of proteins in human cardiomyocytes. Our findings suggest that PDE4s have a similar role in the local regulation of cAMP signaling in rodent and human heart. However, inhibition of PDE4 has ‘global’ effects on cAMP signaling only in rodent hearts, as PDE4 comprises a large fraction of the total cardiac PDE activity in rodents but not in humans. These differences may explain the distinct pharmacological effects of PDE4 inhibition in rodent and human hearts

Cyclic Nucleotide Phosphodiesterases and Compartmentation in Normal and Diseased Heart

International audienceCyclic nucleotide phosphodiesterases (PDEs) degrade the second messengers cAMP and cGMP, thereby regulating multiple aspects of cardiac function. This highly diverse class of enzymes encoded by 21 genes encompasses 11 families which are not only responsible for the termination of cyclic nucleotide signalling, but are also involved in the generation of dynamic microdomains of cAMP and cGMP controlling specific cell functions in response to various neurohormonal stimuli. In myocardium, the PDE3 and PDE4 families are predominant to degrade cAMP and thereby regulate cardiac excitation-contraction coupling. PDE3 inhibitors are positive inotropes and vasodilators in human, but their use is limited to acute heart failure and intermittent claudication. PDE5 is particularly important to degrade cGMP in vascular smooth muscle, and PDE5 inhibitors are used to treat erectile dysfunction and pulmonary hypertension. However, these drugs do not seem efficient in heart failure with preserved ejection fraction. There is experimental evidence that these PDEs as well as other PDE families including PDE1, PDE2 and PDE9 may play important roles in cardiac diseases such as hypertrophy and heart failure. After a brief presentation of the cyclic nucleotide pathways in cardiac cells and the major characteristics of the PDE superfamily, this chapter will present their role in cyclic nucleotide compartmentation and the current use of PDE inhibitors in cardiac diseases together with the recent research progresses that could lead to a better exploitation of the therapeutic potential of these enzymes in the future

Wpływ wzbudzania zewnętrznego na właściwości dynamic zne stołu wibroizolacyjnego

Scientific publications available on sandwich panels in evaluating fundamental frequency with a non-dimensional parameter have been discussed in this article. Effectiveness of optical table with pneumatic vibration insulation supports have been analysed in low (1-50) Hz and higher (500-1200) Hz frequency range. Experiments of vibration transmissibility performed using vibration excitation apparatus and other special test equipment. The dynamics characteristics and application ranges of a table as low frequency vibration damper have been defined. Theoretical and experimental modal analysis of the main part of the system – top surface of table – has been performed. This analysis enabled to determine four resonant eigen-frequencies at higher frequency range. Research results show the reliability of vibration table usage and the dangerous zones of its exploitation.W artykule omówiono dostępne publikacje naukowe dotyczące oceny częstotliwości podstawowej paneli przekładkowych z wykorzystaniem parametru bezwymiarowego. Analizowano wydajność stołu optycznego wyposażonego w podpory wibroizolacyjne w niskim (1-50 Hz) i wyższym (500-1200 Hz) zakresie częstotliwości. Doświadczenia dotyczące charaketrystyk przenoszenia drgań prowadzono z zastosowaniem aparatury do wzbudzania drgań i innych specjalnych urządzeń badawczych. Określono właściwości dynamiczne i zakres wykorzystania stołu jako tłumika drgań o niskiej częstotliwości. Dokonano teoretycznej i eksperymentalnej analizy modalnej głównej części systemu – górnej powierzchni stołu. Analiza ta pozwoliła wyodrębnić cztery częstości drgań własnych z wyższego zakresu częstotliwości. Wyniki badań potwierdzają niezawodność stołu wibracyjnego oraz określają strefy jego eksploatacji wykazujące niekorzystne właściwości