Search results for "hardening"

Impact of Gamma Radiation on Dynamic RDSON Characteristics in AlGaN/GaN Power HEMTs

2019

GaN high-electron-mobility transistors (HEMTs) are promising next-generation devices in the power electronics field which can coexist with silicon semiconductors, mainly in some radiation-intensive environments, such as power space converters, where high frequencies and voltages are also needed. Its wide band gap (WBG), large breakdown electric field, and thermal stability improve actual silicon performances. However, at the moment, GaN HEMT technology suffers from some reliability issues, one of the more relevant of which is the dynamic on-state resistance (R) regarding power switching converter applications. In this study, we focused on the drain-to-source on-resistance (R) characteristic…

Optimum design for work-hardening adaptation

1977

Abstract The finite element-linear programming approach and the work-hardening adaptation criterion are used to formulate a general theory of optimum design of rigid-work-hardening structures subjected to loads which vary statically within given limits. Self-weight, as well as some technological constraints, can be introduced into the framework of the optimization problem. The optimality conditions are discussed with the aid of geometrical descriptions as well, and a comparison is made with the standard limit design. Numerical applications are given for a plane truss and a plane frame with axial force-bending moment interaction.

Radiation hard monolithic CMOS sensors with small electrodes for High Luminosity LHC

2019

Abstract The upgrade of the tracking detectors for the High Luminosity-LHC (HL-LHC) requires the development of novel radiation hard silicon sensors. The development of Depleted Monolithic Active Pixel Sensors targets the replacement of hybrid pixel detectors with radiation hard monolithic CMOS sensors. We designed, manufactured and tested radiation hard monolithic CMOS sensors in the TowerJazz 180 nm CMOS imaging technology with small electrodes pixel designs. These designs can achieve pixel pitches well below current hybrid pixel sensors (typically 50 ×  50 μ m ) for improved spatial resolution. Monolithic sensors in our design allow to reduce multiple scattering by thinning to a total si…

Photoinduced Modifications of the Structure and Microhardness of Fullerite C60

2004

The wavelength dependence, temperature limits, time and depth evolution of the photoinduced hardening of C60 crystals in air have been investigated by microindentation and dislocation mobility methods. Two photopolymerized phases, which differ in the hardness and thermal stability, are found to appear. We suggest that formation of fullerene dimers (ie. C120) in pristine fullerite and growth of C120O phase in oxygenated fullerite via [2+2] photoaddition reaction is responsible for it. It has been found from depth distribution data of the hardness that the C120O phase is located in oxygen-contaminated subsurface layer of 0.8–1 μm and appears under illumination at 290–330 K.

Numerical and experimental analysis of load capacity of pressure vessels for large deformations

1991

Abstract A method of theoretical and experimental investigations of large deformations and load capacity of pressure vessels has been proposed. Algorithms and programs for numerical analysis (with the finite element method) of spatial stress and strain state and load capacity have been worked out according to the Prandtl-Reuss theory of plastic flow. Loading in the vessel was realized in an incremental way. The loading process was continued up to the moment when the maximum loading was obtained (i.e. the moment when state of equilibrium of the vessel was not possible). It has been found that in thin-walled circular vessels with rigid bottoms, when a ratio of length to their diameter is less…

NMR relaxation study of hardening acid-base dental cements

2001

Influence of material characteristics on plastomechanics of the fsw process for T-joints

2009

Abstract The potential of friction stir welding (FSW) has thoroughly been investigated by several authors, however their focus has primarily been on butt joints. T-joints are of paramount interest for transportation industries especially due to their capacity to straighten panels. Welding of T-joints is very challenging due to thin walls, poor location of the rib–web interface and the requirements for corner-fillets. This paper investigates FSW of T-joints of two popular aluminum alloys, i.e. 2024-T4 and 6082-T6, and the role played by the material characteristics on joining. First, an experimental study is carried out with specially designed fixture to determine the effect of process condi…

Effect of ageing on the morphology and creep and recovery of polymer-modified bitumens

2018

Polymer additives are used to improve the properties of road bitumens including their oxidative resistance. However, their usage as anti-oxidative materials remains relatively unclear. This study aims to investigate the changes in the morphology and the rheological response of polymer modified bitumens used in road pavement construction caused by ageing. An elastomer (radial styrene butadiene styrene, SBS) and a plastomer (ethyl vinyl acetate, EVA) polymer were mixed with one base bitumen at three polymer concentrations. The bitumens were RTFO and PAV aged. The morphology of the bitumens was captured by fluorescence microscopy while the rheological properties were measured by means of the m…

Effects of photoperiodically induced reproductive diapause and cold hardening on the cold tolerance of Drosophila montana

2010

Coping with seasonal and daily variation in environmental conditions requires that organisms are able to adjust their reproduction and stress tolerance according to environmental conditions. Females of Drosophila montana populations have adapted to survive over the dark and cold winters at high latitudes and altitudes by spending this season in photoperiodically controlled reproductive diapause and reproducing only in spring/summer. The present study showed that flies of a northern population of this species are quite tolerant of low temperatures and show high seasonal and short-term plasticity in this trait. Culturing the flies in short day length (nearly all females in reproductive diapau…

Influence of the Mean Load Value in Fatigue Block Loading on Strains

2014

This paper presents the results of the fatigue tests of the specimens made from S3555 steel and aluminum alloy AlCu4MgSi subjected to bending block loading with mean load value. The influence of the changes of the mean load conditions was investigated. During the tests strains were registered and relation between the load and the strains was analyzed. In the case of S355 steel it was observed, that additional hardening occurs when higher value of the mean load is applied at the beginning of the block loading. Other case, when the mean load was increased from zero to maximum, a creep effect of the material was registered. For the specimens made from aluminum alloy similar processes were not …