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Publicatii proprii

The energy transfer between the ports of an implemented gyrator using LM13700 operational transconductance amplifier

In this paper a gyrator implementation using a LM13700 operational transconductance amplifier is analyzed. It was first verified under PSpice simulation and experimentally the antireciprocity of this gyrator, i.e., its properties. This type of gyrator can be used for controlling the energy transfer from one port to the other by modifying the bias currents of the operational transconductance amplifier.

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RESPONSE TO APPLIED MECHANICAL LOAD OF A MULTIVARIANT MARTENSITIC Cu-Zn-Al-Fe SHAPE MEMORY ALLOY

A multivariant martensitic Cu-Zn-Al-Fe Shape Memory Alloy has been analysed by means of tensile loading-unloading tests, X-ray diffraction and scanning electron microscopy. The tensile superelastic curve was correlated with the crystallographic reorientation of the martensite plate variants. The stress plateaus correspond to the reversible formation of (016) variant, up to 20 MPa, accompanied by the increase of the second and third order microstrains

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A new possibility of experimental characterization of a time of flight telemetric system
A statistical evaluation of thermomechanical loading effects on martensite plate morphology in CuZnAl SMAs

The paper reports the effects of 100 to 500 training cycles applied to lamellar specimens of a Cu-Zn-Al Shape Memory Alloy (SMA). The training procedure consisted in the bending, during the cooling to room temperature (RT) of martensitic specimens, by the load fastened at their free end and in load lifting by Shape Memory Effect (SME) during heating up to austenitic domain. During cooling, the concave surface of bent specimens was compressed and

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Influence of mechanical alloying on the behavior of Fe-Mn-Si-Cr-Ni shape memory alloys made by powder metallurgy

Fe-14 Mn-6 Si-9 Cr-5 Ni (mass. %) shape memory alloys (SMAs) were produced from raw powders employed both in initial commercial state and in a mixture state of equal fractions of commercial and mechanically alloyed (MA’d) particles. After blending, pressing and sintering, powder compacts were hot rolled (HR’d) and solution treated (ST’d) before being machined into plane-parallel lamellas. Specimens with special geometry were pre-strained on

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Prãbuşirea imperiului sovietic. „Lecţii” în retrospectivã
The 1989 Revolutions in Retrospect

Reminding us of the failure of academia to predict the East European revolutions, and the challenges presented by the latter to the theories of revolution, the essay claims that in order to understand why the exit from communism comprised so many varied modes, one should take a 'path-dependence' diachronic and synchronic comparative perspective. Based on this dual approach and a set of variables, the essay advances a typology of East European revolutions

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Use of land snails (pulmonata) for monitoring copper pollution in terrestrial ecosystems

The term bioindicator defines organisms that respond to a pollutant load with changes in vital functions or accumulate pollutants (Arndt et al. 1987). The use of bioindicator organisms may allow researchers to evaluate the effects of mixtures of pollutants on ecosystems in time and space, depending on the selected species and approach (Hellawell 1986). In contrast, simple instrumental analyses of pollutants can provide extremely precise data about

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The 1/2 Correction Forms in Geometric Quantization of the Symmetric Free Rigid Body

Some aspects of Kostant's geometric quantization for the symmetric free rigid body are given. The basic idea is to show that the spectrum of a symmetrical free rigid body can always determine via Kostant's geometric quantization in the correction 1/2 forms as well as geometric pre-quantization approach.

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Researches on the failure modes under tensile forces of the Resistance Spot Welding (RSW) joints

Resistance spot welding (RSW) is one of the most used methods of joining sheet metals. The RSW process is based on Joule Lenz effect, of the electric current passing trough the (similar or dissimilar ) joining metal sheets positioned between the two contact electrodes. At welding process , some important changes occurs in metallurgical and mechanical properties of the welded areas and heat affected zones (HAZ) . The purpose of this work is to highlight

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