Search results for "ding"
showing 10 items of 16709 documents
Stabilization of primary mobile radiation defects in MgF2 crystals
2016
Abstract Non-radiative decay of the electronic excitations (excitons) into point defects ( F – H pairs of Frenkel defects) is main radiation damage mechanism in many ionic (halide) solids. Typical time scale of the relaxation of the electronic excitation into a primary, short-lived defect pair is about 1–50 ps with the quantum yield up to 0.2–0.8. However, only a small fraction of these primary defects are spatially separated and survive after transformation into stable, long-lived defects. The survival probability (or stable defect accumulation efficiency) can differ by orders of magnitude, dependent on the material type; e.g. ∼10% in alkali halides with f.c.c. or b.c.c. structure, 0.1% in…
Magnetic properties of exciton trapped by an off-center ionized donor in single quantum dot
2021
Abstract It is known that the lines of exciton (X) and exciton trapped by an ionized donor ( D + , X ) are often very close which makes very difficult their experimental identification. In order to facilitate their distinction in spherical quantum dots, we investigate the effect of an applied magnetic field studying the binding energy of the complex ( D + , X ) as function of dot size and the ionized donor position. Our calculation is using a variational approach taking into account the interactions between all charge carriers. Our results show that the complex is more sensitive to the magnetic field than the exciton and that the energy of the exciton is not sufficiently affected when the i…
Analytical solution for the diffusion of a capacitor discharge generated magnetic field pulse in a conductor
2016
Powerful forces arise when a pulse of a magnetic field in the order of a few tesla diffuses into a conductor. Such pulses are used in electromagnetic forming, impact welding of dissimilar materials and grain refinement of solidifying alloys. Strong magnetic field pulses are generated by the discharge current of a capacitor bank. We consider analytically the penetration of such pulse into a conducting half-space. Besides the exact solution we obtain two simple self-similar approximate solutions for two sequential stages of the initial transient. Furthermore, a general solution is provided for the external field given as a power series of time. Each term of this solution represents a self-sim…
Interface evolution during magnetic pulse welding under extremely high strain rate collision: mechanisms, thermomechanical kinetics and consequences
2020
Abstract Magnetic pulse welding enables to produce perplexing interfacial morphologies due to the complex material response during the high strain rate collision. Thus, a thermomechanical model is used in this study to investigate the formation mechanism of the wake, vortex, swirling and mesoscale cavities with the increase of the impact intensity at the interface. The formation of these interfacial features are difficult to characterize by insitu methods, thus the origin of phenomena still remain a subject of open discussion. Our studies identify the governing mechanisms and the associated thermomechanical kinetics, which are responsible for the formation mechanism of interfacial features.…
Metrological Properties of the Test Setup for Determination Shielding Effectiveness of the Industrial Cable Connectors
2017
Abstract The paper presents results related to assessment of the repeatability and reproducibility of the measurement test setup for determination the relative value of the shielding effectiveness coefficient of the industrial connectors. The construction of the proposed test setup, the measurement method and the procedure for the analysis of measurement results were described. To determine the value of the repeatability and reproducibility coefficient, the two–way analysis of variance was used, which additionally allows for an assessment of the influence of individual sources of variance. The measurements and their analysis were conducted for several frequencies in the range up to 1 GHz. A…
Synergistic effect of fiber content and length on mechanical and water absorption behaviors of Phoenix sp. fiber-reinforced epoxy composites
2016
Phoenix sp. fiber-reinforced epoxy composites have been manufactured using compression molding technique. The effect of reinforcement volume content (0%, 10%, 20%, 30%, 40%, and 50%) and size (300 µm particles, 10 mm, 20 mm, and 30 mm fibers) on quasi-static and dynamic mechanical properties was investigated. Moreover, the water absorption properties of composites were analyzed at different environmental conditions (10℃, 30℃, and 60℃). For each reinforcement size, composites loaded with 40% in volume show highest tensile and flexural properties. Furthermore, composites with 300 µm particles present the best impact properties and the lowest water absorption, regardless of the environmental …
Composition dependence ofSi1−xGexsputter yield
2005
Sputtering yields have been measured for unstrained ${\mathrm{Si}}_{1\ensuremath{-}x}{\mathrm{Ge}}_{x}$ $(x=0--1)$ alloys when bombarded with ${\mathrm{Ar}}^{+}$ ions within the linear cascade regime. Nonlinear S-shape dependence of the sputter yield as a function of the alloy composition has been revealed. The dependence is analyzed within the frameworks of the cascade theory conventionally accepted to be the most systematic to date theoretical approach in sputtering. In view of a linear composition dependence predicted for the sputter yield by the cascade theory adapted for polyatomic substrates, the nonlinearity observed in our experiments is shown to be related to the alloying effect on…
Experimental investigation of the effect of moisture on the acoustic properties of lightweight substrates used in green envelopes
2021
International audience; Substrates are used in green walls and roofs to supply air and water to the roots of the growing plants. These substrates are porous with micropores which store water and macropores which facilitate drainage and air entry. Effect of moisture on acoustic absorption is studied for two lightweight substrates: coir dust and perlite. Measurement of dry and moistened substrates are conducted to evaluate their effective speed of sound, attenuation, characteristic impedance, compressibility and density between 100 Hz and 1000 Hz using an impedance tube and the three microphone-two load method. Effect of moisture on these quantities is found to depend strongly upon the intera…
Computer-aided analysis and design procedure for rotating induction machine magnetic circuits and windings
2018
The aim of this study is to present a new, accurate, and user-friendly software procedure for the analysis and rapid design of rotating induction machine windings, considering both the electric and the magnetic specifications of the machine itself. This procedure is a valid aid for quick first stage design without the necessity of using finite element method (FEM)-based design procedures. FEM can be used in a second design phase in order to refine the first stage results. The design procedure is hereafter outlined and some examples show its capability.
Multiphysical Modeling of Transport Phenomena During Laser Welding of Dissimilar Steels
2016
Abstract The success of new high-strength steels allows attaining equivalent performances with lower thicknesses and significant weight reduction. The welding of new couples of steel grades requires development and control of joining processes. Thanks to high precision and good flexibility, laser welding became one of the most used processes for joining of dissimilar welded blanks. The prediction of the local chemical composition in the weld formed between dissimilar steels in function of the welding parameters is essential because the dilution rate and the distribution of alloying elements in the melted zone determines the final tensile strength of the weld. The goal of the present study i…