Nontrivial dependence of dielectric stiffness and SHG on dc bias in relaxors and dipole glasses

Dielectric permittivity and Second Harmonic Generation (SHG) studies in the field-cooled mode show a linear dependence of dielectric stiffness (inverse dielectric permittivity) on dc bias in PMN-PT crystals and SHG intensity in KTaO$_{3}$:Li at small Li concentrations. We explain this unusual result in the framework of a theory of transverse, hydrodynamic-type, instability of local polarization.Comment: 5 figure

Turbocharger Lubrication - Lubricant Behavior and Factors That Cause Turbocharger Failure

This paper is a review of the turbocharger lubrication system and at the same time an attempt to point out and analyze the factors responsible for turbocharger wear, damage and failures. In particular, the conditions under which the lubricant works are presented, from its entrance up to its exit from the turbocharger bearing housing. Additionally, the consequences of failure to comply with the instructions for appropriate turbocharger operation are provided by the various manufacturers. Water cooled turbochargers (for which engine coolant is used), contribute significantly to the reduction of lubricant temperature, in the critical zones of its operation. This is achieved by reducing, the danger of the oil “coking” effect (charred oil residues) or its decomposition, because of high temperature occurring in these zones. Turbochargers shaft support development using semi-floating bush bearings has a significant impact on turbocharger manufacturing cost, as well as on their operational features. Further benefit may be had, when ball bearings are used (usually angular contact bearings are used) for turbocharger shaft support as they provide: a) a reduction of the kinetic friction coefficient, b) reduction of turbocharger lag during turbocharger shaft acceleration from low to high speeds, and c) reduced sealing problems. Regarding the failures that occur in turbochargers, their majority - up to 50% - is caused by problematic lubrication [1]. The rest of the failures are divided between causes related to human factors (such as misuse and inadequate maintenance of a turbocharged vehicle) and external factors such as foreign objects entering either the compressor or turbine housings

Retirement Incentives in Belgium: Estimations and Simulations Using SHARE Data

peer reviewedThe paper studies retirement behavior of wage‐earners in Belgium – for the first time using a rich survey dataset to analyze retirement incentives as faced by individuals. Specifically, we use SHARE data to estimate a model à la Stock and Wise (1990). Exploring the data on individual life‐histories from SHARELIFE, we construct a measure of financial incentive to retire. Our analysis explicitly takes into account the different take‐up rates of the various early retirement exit paths across time and ages. The results show that financial incentives play a strong role. Health and education also matter, as do regional differences. Against the general background of the 2020 strategy, we perform a set of policy simulations and illustrate the scope but also the limits associated with selective parametric reforms

Electrocaloric effect in Ba(0.2)Ca(0.8)Ti(0.95)Ge(0.05)O(3) determined by a new pyroelectric method

The present letter explores the electrocaloric effect (ECE) in the lead free oxide Ba0.8Ca0.2Ti0.95Ge0.05O3 ceramics (BCTG). The electrocaloric responsivity (dT/dE) was determined by two different methods using the Maxwell relationship (dT/dE)~(dP/dT)_E. In a first well-known indirect method, P-E hysteresis loops were measured in a wide temperature range from which the pyroelectric coefficient p_E=(dP/dT)_E and thus (dT/dE) were determined by derivation of P(T,E) data. In the second novel method the pyroelectric coefficient p_E and consequently the electrocaloric responsivity was determined by direct measurements of the pyroelectric currents under different applied electric fields. Within the experimental error good agreement was obtained between two methods with an electrocaloric responsivity equal to 0.18 +/- 0.05 10-6 K.m.V-1 was obtained at about 410 KComment: 5 pages, 4 figure

Dielectric Properties Of Lead Potassium Lithium Niobate (Pb1,85K1,15Li0,15Nb5O15) With Tetragonal Tungsten Bronze (TTB) Type Structure

A new tungsten bronze ceramic oxide, Pb2-xK1+xLixNb5O15 (PKLN) (x =0.15) was prepared by high temperature solid-state reaction route. Structural and electrical properties are investigated using X-ray diffraction and dielectric measurements. Room temperature XRD pattern confirms the formation of the compound with an orthorhombic crystal system. The dielectric permittivity and the loss tangent of the sample have been measured in a frequency range 1Hz–1MHz and a temperature range 35–550 °C. Studies of dielectric properties show that the compound exhibits an anomaly at 425°C (usually called transition temperature).The electrical parameters of the material were studied using complex impedance spectroscopy showing that the compound exhibits non-Debye of relaxation process. In the paraelectric phase, activation energy was determined and the value is Eτ = 0.68 eV. The present ceramic is promising candidate for high dielectric constant and low loss dielectric ceramic.A new tungsten bronze ceramic oxide, Pb2-xK1+xLixNb5O15 (PKLN) (x =0.15) was prepared by high temperature solid-state reaction route. Structural and electrical properties are investigated using X-ray diffraction and dielectric measurements. Room temperature XRD pattern confirms the formation of the compound with an orthorhombic crystal system. The dielectric permittivity and the loss tangent of the sample have been measured in a frequency range 1Hz–1MHz and a temperature range 35–550 °C. Studies of dielectric properties show that the compound exhibits an anomaly at 425°C (usually called transition temperature).The electrical parameters of the material were studied using complex impedance spectroscopy showing that the compound exhibits non-Debye of relaxation process. In the paraelectric phase, activation energy was determined and the value is Eτ = 0.68 eV. The present ceramic is promising candidate for high dielectric constant and low loss dielectric ceramic