Vakuum‐Lineardurchführungen mit Magnetflüssigkeitsdichtungen

Vacuum linear feedthroughs with magnetic fluid seal A magnetic fluid sealed feedthrough is a device that transmits linear motion into a vacuum chamber with minimal frictional resistances and minimal contamination level.They are widely employed in high and ultra‐high vacuum equipment among others in semiconductor fabrication industry and robotics applications. The operating conditions of magnetic fluid seals during reciprocating motion are so different from those with rotating motion that the use of their conventional structures for reciprocating motion seals yield no good results. Analysis of sealing mechanism of magnetic fluid seal in reciprocating motion shows that the operation of these seals is affected by the carry‐over and the magnetic fluid deformation in the sealing gap, which depends on the velocity of reciprocating motion. The reduction of magnetic fluid quantity in the sealing gap,caused by the reciprocating motion of the shaft is reason of the seal failure. In the paper a short characteristic of magnetic fluid sealing technology , principle of sealing, behaviour of the ferrofluid and seal failure mechanism in the linear motion of the shaft are given. Moreover some new structure designs of vacuum linear feedthroughs with magnetic fluid seals, which have practical application value are presented.     

Dynamic axial crushing of circular tubes

A series of axial crushing tests on steel circular cylindrical shells loaded either statically or dynamically is reported and compared with various theoretical predictions and empirical relations. A modified version of Alexander's theoretical analysis for axisymmetric, or concertina, deformations gives good agreement with the experimental results when the effective crushing distance is considered and provided that the influence of material strain rate sensitivity is retained in the dynamic crushing case.     

On the formation of double zones of necking during hot tensile tests

The phenomenon of double necking during hot tensile tests is discussed in this work. The investigation was carried out on high-carbon steel using a tensile testing machine equipped with an integral heating system. Tensile tests were performed in a large temperature range to obtain the mechanical characteristic of the material. Microstructure evolution was observed by light microscopy and hardness measurements to determine the position of double zones of necking. A significant increase in flow stress of as-transformed austenite was found to be at the origin of the double necking behaviour.     

Influence of series resistance and cooling conditions on I–V characteristics of SiC merged PiN Schottky diodes

The paper presents the exemplary electro-thermal models of merged PiN Schottky diode – a diode with the parallel PiN junction, protecting the device against the uncontrolled voltage rise, causing so-called thermal runaway. In the presented models, the conductivity modulation effect in the PiN junction is taken into account. The influence of the PiN junction on the non-isothermal I–V characteristics of MPS diodes, for various cooling conditions, is discussed. It is shown, that the thermal runaway is possible, in spite of presence of protecting PiN junction.     

Spontaneous formation of gold microplates during reduction‐coupled removal of noble metals using Dowex M4195 resin

The present work reports the novel phenomenon of spontaneous formation of gold microplates. The effect is observed as a consequence of , , , and sorption on the Dowex M4195 resin. Therefore an attempt to explain the phenomenon mechanism is made. The research is covering sorption, kinetic and thermodynamic studies. The shapes of formed gold single plates are determined. The uptakes of Au(III), Pt(IV), Pd(II), and Re(VII) tests have been conducted using a batch method from single‐component metals solutions in 0.1M HCl. The sorption‐reduction phenomenon has been assessed by executed SEM, FTIR, XRD, and XPS studies. The greatest sorption capacity, combined with reduction‐coupled removal phenomenon, has been achieved for gold (5.5 mmol Au·g^?1 at 9°C). Executed SEM and XRD analyzes prove formation of gold single crystals during present process, furthermore reduction of rhenium is indicated by XPS analysis. Based on the obtained FTIR and Raman's spectra, the reduction phenomenon is probably followed by resins’ functional groups oxidation. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42425.     

The sensor effect tetrahedron: an extended transducer space

A visualisation of a four-dimensional space called an information and energy tetrahedron is introduced in the paper. This model of energy and information could be found useful by designers and developers of new measuring devices as well as in the analysis of measurement and instrumentation systems. The tetrahedron concept is an extension of the idea of a three dimensional transducer space first presented more than 30 years ago. By taking account of the interference sources within the range of possible energy forms it extends the three dimensional predecessor, which did not encompass these effects. To obtain this extended tetrahedron model, the sensor is viewed from its boundary perspective using the principles of systems engineering developed for application in measuring systems. When this approach is applied to sensors it is shown that they may be reduced to systems influenced by three classes of inputs. These inputs, which consist of the information borne by the measurand in its specific energy form, the support energy form and the contaminating information and energy forms, are shown to constitute what is called the input triangle in the paper. The system output, which is an information bearing energy form, provides an axis normal to the plane formed by the input triangle. All of the axes are drawn based upon the COMETMAN acronym to represent the diversity of possible energy domains. A summary of different ways of classifying energy forms or domains, which is given in the paper, allows these different methods of grouping to be compared. The application of the sensor effect tetrahedron is placed within the context of measurement by means of the three interfaces between humans, machines and their working environment. Introducing extrinsic and intrinsic boundaries permits the link between sensors and formal metrological components to be established. In this way the paper can help to provide a deep perception of sensors.     

Paraffin oil solutions of the mixture of sorbitan monolaurate-ethoxylated sorbitan monolaurate as lubricants

Paraffin mixtures of sorbitan monolaurate (SML)-ethoxylated sorbitan monolaurate (ESML) were applied as lubricant additives. The esters tested can be obtained from natural resources. They are environment-friendly. Tests under steady load conditions were performed to assess their tribological properties. The friction coefficient and wear scar diameter were measured. On the basis of the results obtained one can conclude that the mixtures tested significantly reduce motion resistance and wear. As compared to paraffin oil, wear scar diameter was reduced four times, while friction coefficient—even six times. The influence of total concentration and SML:ESML ratio on tribological properties was analyzed. The synergistic effect, attaining its optimum for comparable mole fraction of both esters, was observed. The results can be interpreted in terms of creation of micellar solutions and interaction of these structures with friction surface.     

Physico–chemical and Dyeing Properties of Disperse Dyes containing Phthalimide Residues

The relationship between the constitution and the physico–chemical and dyeing properties of disperse dyes containing phthalimide residues has been studied. The influence of the –NH or –NCH₃ group in the phthalimide residues on the thermal and spectral properties of dyes has been investigated. Their influence on the dyeing process and on the colour and fastness properties of dyed polyester have also been studied.     

Application of the Jones calculus for Gaussian beams in uniaxial crystals

Following our recent approach in which the Jones matrix calculus was applied to a modulated double-refracted and partially interfering light beam propagating in a homogeneous electro-optic crystal [J. Opt. Soc. Am. A21, 132 (2004)], we generalize the method for any distribution of the light intensity. Special attention is paid to Gaussian, flat-topped Gaussian, and quasi-Gaussian beams for which the intensity of the light emerging from the optical system is found analytically. Application of the method to an optical system with an electro-optic crystal is described.