Explosive crystallization phenomena in SOI structures

1989 ◽  
Vol 4 (6) ◽  
pp. 1473-1479 ◽  
Author(s):  
H. D. Geiler ◽  
M. Wagner ◽  
E. Glaser ◽  
G. Andrä ◽  
D. Wolff ◽  
...  
Keyword(s):  
Solid Phase ◽  
Amorphous Layer ◽  
Nucleation And Growth ◽  
Time Interval ◽  
Two Phase ◽  
Pulse Technique ◽  
Explosive Crystallization ◽  
Crystalline Nucleus ◽  
Phase Nucleation ◽  
Temperature Time

Using the double pulse technique with two synchronized lasers, we studied the conditions of ignition and evolution of explosive crystallization. The structure of the resulting crystallized layers is analyzed by TEM. Results of calculations are reported describing the development of the two phase fronts: amorphous/molten and molten/crystalline. It is shown that the system takes more than 500 ns to reach the steady state. The experimental results support the model of creating first a melt nucleus in the amorphous layer followed by the formation of the crystalline nucleus in the molten sphere. Competitive solid phase nucleation and growth in the amorphous layer limit the temperature-time interval of melt nucleation. Defined explosively crystallized areas in laterally structured SOI layers are presented.

Occurrence of Dynamic Alpha-Phase Nucleation in Ti-5553 during Hot Deformation

2014 ◽  
Vol 922 ◽  
pp. 149-154 ◽  
Author(s):  
Ameth Maloum Fall ◽  
David Piot ◽  
Frank Montheillet ◽  
Sandra Andrieu
Keyword(s):  
Hot Deformation ◽  
Peak Stress ◽  
Nucleation And Growth ◽  
Alpha Phase ◽  
Flow Softening ◽  
Compression Tests ◽  
Two Phase ◽  
Flow Response ◽  
Phase Nucleation ◽  
Dynamic Nucleation

This paper discusses the microstructural changes during hot deformation, mainly dynamic nucleation and growth of a precipitates, occurring in the b metastable titanium alloy Ti-5553 (Ti–5Al–5Mo–5V–3Cr–0.5Fe). The effect of process variables on flow response and microstructure evolution during hot working of the alloy with initial bimodal microstructure was established using isothermal hot-compression tests. Testing was conducted at 4 strain rates between 0.001 and 1 s−1and 5 temperatures between 720 °C and 850 °C, on material with prior b grain size of 450 μm, a nodular size of 3 µm and a known primary a-phase fraction. All flow curves exhibited a peak stress followed by moderate flow softening in the two-phase domain. Flow softening was interpreted in terms of deformation heating and substructure or texture evolutions. The dependence on strain rate and temperature of the kinetics of dynamic a-phase nucleation during straining is complex and appears to be of second-order importance compared to the effects of strain. This suggests that the nucleation and growth of a phase in the temperature range between 720 °C and 990 °C results from a mixed-mode displacive-diffusional transformation, similar to the austenite / ferrite transformation above the Ae3 temperature reported by some authors.

SYNTHESIS OF HYDROGEN IN ACOUSTOPLASMA DISCHARGE IN A LIQUID-PHASE STREAM

2019 ◽  
pp. 42-48 ◽  
Author(s):  
N. A. Bulychev
Keyword(s):  
Liquid Phase ◽  
Organic Compounds ◽  
Electrode Materials ◽  
Solid Phase ◽  
Plasma Discharge ◽  
Raw Material ◽  
Two Phase ◽  
Reduced Pressure ◽  
External Power Source ◽  
Phase Medium

In this paper, the plasma discharge in a high-pressure fluid stream in order to produce gaseous hydrogen was studied. Methods and equipment have been developed for the excitation of a plasma discharge in a stream of liquid medium. The fluid flow under excessive pressure is directed to a hydrodynamic emitter located at the reactor inlet where a supersonic two-phase vapor-liquid flow under reduced pressure is formed in the liquid due to the pressure drop and decrease in the flow enthalpy. Electrodes are located in the reactor where an electric field is created using an external power source (the strength of the field exceeds the breakdown threshold of this two-phase medium) leading to theinitiation of a low-temperature glow quasi-stationary plasma discharge.A theoretical estimation of the parameters of this type of discharge has been carried out. It is shown that the lowtemperature plasma initiated under the flow conditions of a liquid-phase medium in the discharge gap between the electrodes can effectively decompose the hydrogen-containing molecules of organic compounds in a liquid with the formation of gaseous products where the content of hydrogen is more than 90%. In the process simulation, theoretical calculations of the voltage and discharge current were also made which are in good agreement with the experimental data. The reaction unit used in the experiments was of a volume of 50 ml and reaction capacity appeared to be about 1.5 liters of hydrogen per minute when using a mixture of oxygen-containing organic compounds as a raw material. During their decomposition in plasma, solid-phase products are also formed in insignificant amounts: carbon nanoparticles and oxide nanoparticles of discharge electrode materials.

The influence of the Stokes and Archimedes forces on the stability of a two-phase flow

2003 ◽  
Vol 3 ◽  
pp. 266-270
Author(s):  
B.H. Khudjuyerov ◽  
I.A. Chuliev
Keyword(s):  
Spectral Method ◽  
Stability Region ◽  
Gas Flow ◽  
Two Phase Flow ◽  
Solid Phase ◽  
Stability Characteristic ◽  
Phase Flow ◽  
Two Phase ◽  
The Stability

The problem of the stability of a two-phase flow is considered. The solution of the stability equations is performed by the spectral method using polynomials of Chebyshev. A decrease in the stability region gas flow with the addition of particles of the solid phase. The analysis influence on the stability characteristic of Stokes and Archimedes forces.

scholarly journals Implementation of an FPGA-Based Current Control and SVPWM ASIC with Asymmetric Five-Segment Switching Scheme for AC Motor Drives

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1462
Author(s):  
Ming-Fa Tsai ◽  
Chung-Shi Tseng ◽  
Po-Jen Cheng
Keyword(s):  
Discrete Time ◽  
Control Function ◽  
Current Control ◽  
Motor Drives ◽  
Modulation Scheme ◽  
Time Interval ◽  
Switching Scheme ◽  
Two Phase ◽  
Ac Motor ◽  
Ac Motor Drives

This paper presents the design and implementation of an application-specific integrated circuit (ASIC) for a discrete-time current control and space-vector pulse-width modulation (SVPWM) with asymmetric five-segment switching scheme for AC motor drives. As compared to a conventional three-phase symmetric seven-segment switching SVPWM scheme, the proposed method involves five-segment two-phase switching in each switching period, so the inverter switching times and power loss can be reduced by 33%. In addition, the produced PWM signal is asymmetric with respect to the center-symmetric triangular carrier wave, and the voltage command signal from the discrete-time current control output can be given in each half period of the PWM switching time interval, hence increasing the system bandwidth and allowing the motor drive system with better dynamic response. For the verification of the proposed SVPWM modulation scheme, the current control function in the stationary reference frame is also included in the design of the ASIC. The design is firstly verified by using PSIM simulation tool. Then, a DE0-nano field programmable gate array (FPGA) control board is employed to drive a 300W permanent-magnet synchronous motor (PMSM) for the experimental verification of the ASIC.

scholarly journals CFD Simulation of Solid Suspension for a Liquid–Solid Industrial Stirred Reactor

2021 ◽  
Vol 11 (12) ◽  
pp. 5705
Author(s):  
Adrian Stuparu ◽  
Romeo Susan-Resiga ◽  
Alin Bosioc
Keyword(s):  
Chemical Reaction ◽  
Cfd Simulation ◽  
Simulation Analysis ◽  
Solid Phase ◽  
Initial Conditions ◽  
Chemical Reactor ◽  
Liquid Mixtures ◽  
Multiphase Model ◽  
Chemical Product ◽  
Two Phase

The present study examines the possibility of using an industrial stirred chemical reactor, originally employed for liquid–liquid mixtures, for operating with two-phase liquid–solid suspensions. It is critical when obtaining a high-quality chemical product that the solid phase remains suspended in the liquid phase long enough that the chemical reaction takes place. The impeller was designed for the preparation of a chemical product with a prescribed composition. The present study aims at finding, using a numerical simulation analysis, if the performance of the original impeller is suitable for obtaining a new chemical product with a different composition. The Eulerian multiphase model was employed along with the renormalization (RNG) k-ε turbulence model to simulate liquid–solid flow with a free surface in a stirred tank. A sliding-mesh approach was used to model the impeller rotation with the commercial CFD code, FLUENT. The results obtained underline that 25% to 40% of the solid phase is sedimented on the lower part of the reactor, depending on the initial conditions. It results that the impeller does not perform as needed; hence, the suspension time of the solid phase is not long enough for the chemical reaction to be properly completed.

scholarly journals The Chemical Composition of Cometary Nuclei

1972 ◽  
Vol 45 ◽  
pp. 265-270
Author(s):  
L. M. Shul'man
Keyword(s):  
Chemical Composition ◽  
Cosmic Rays ◽  
Organic Molecules ◽  
Solid Phase ◽  
Critical Concentration ◽  
Energy Output ◽  
Time Interval ◽  
Nuclear Surface ◽  
Solar Cosmic Rays ◽  
Cometary Nuclei

The probable parent-molecules of radicals such as C3 and N2+ are discussed, and it is concluded that cometary nuclei may contain complicated organic molecules, such as C3H4, CH2N2, and C4H2. It is suggested that these molecules are formed by radiation synthesis in solid phase. In a time interval of order 107 to 109 yr bombardment from cosmic rays would be expected to transform the chemical composition to a depth of 1 m. Solar cosmic rays do not penetrate as far, and as a result the surface layer of the nucleus can be enriched with unsaturated hydrocarbons. After a critical concentration of this explosive material is reached a further burst of solar cosmic rays can initiate an explosion and thus an outburst in the comet's brightness. This mechanism is the only one advanced to date that can explain the synchronism of the energy output over the whole nuclear surface.

Kinematic and Dynamic Parameters of a Liquid-Solid Pipe Flow Using DPIV∕Accelerometry

2007 ◽  
Vol 129 (11) ◽  
pp. 1415-1421 ◽  
Author(s):  
Joseph Borowsky ◽  
Timothy Wei
Keyword(s):  
Pipe Flow ◽  
Solid Phase ◽  
Fluid Phase ◽  
Central Moment ◽  
Steady Flows ◽  
Dynamic Parameters ◽  
Two Phase ◽  
Turbulence Structures ◽  
Two Phases ◽  
Flat Profile

An experimental investigation of a two-phase pipe flow was undertaken to study kinematic and dynamic parameters of the fluid and solid phases. To accomplish this, a two-color digital particle image velocimetry and accelerometry (DPIV∕DPIA) methodology was used to measure velocity and acceleration fields of the fluid phase and solid phase simultaneously. The simultaneous, two-color DPIV∕DPIA measurements provided information on the changing characteristics of two-phase flow kinematic and dynamic quantities. Analysis of kinematic terms indicated that turbulence was suppressed due to the presence of the solid phase. Dynamic considerations focused on the second and third central moments of temporal acceleration for both phases. For the condition studied, the distribution across the tube of the second central moment of acceleration indicated a higher value for the solid phase than the fluid phase; both phases had increased values near the wall. The third central moment statistic of acceleration showed a variation between the two phases with the fluid phase having an oscillatory-type profile across the tube and the solid phase having a fairly flat profile. The differences in second and third central moment profiles between the two phases are attributed to the inertia of each particle type and its response to turbulence structures. Analysis of acceleration statistics provides another approach to characterize flow fields and gives some insight into the flow structures, even for steady flows.

On the Natural Lubrication of Synovial Joints: Normal and Degenerate

1977 ◽  
Vol 99 (2) ◽  
pp. 163-172 ◽  
Author(s):  
Joseph M. Mansour ◽  
Van C. Mow
Keyword(s):  
Articular Cartilage ◽  
Solid Phase ◽  
Articular Surface ◽  
Moving Load ◽  
Frictional Resistance ◽  
Elastic Solid ◽  
Surface Load ◽  
Two Phase ◽  
Tissue Properties ◽  
Synovial Joints

Fluid flow and mass transport mechanisms associated with articular cartilage function are important biomechanical processes of normal and pathological synovial joints. A three-layer permeable, two-phase medium of an incompressible fluid and a linear elastic solid are used to model the flow and deformational behavior of articular cartilage. The frictional resistance of the relative motion of the fluid phase with respect to the solid phase is given by a linear diffusive dissipation term. The subchondral bony substrate is represented by an elastic solid. The three-layer model of articular cartilage is chosen because of the known histological, ultrastructural, and biomechanical variations of the tissue properties. The calculated flow field shows that for material properties of normal healthy articular cartilage the tissue creates a naturally lubricated surface. The movement of the interstitial fluid at the surface is circulatory in manner, being exuded in front and near the leading half of the moving surface load and imbibed behind and near the trailing half of the moving load. The flow fields of healthy tissues are capable of sustaining a film of fluid at the articular surface whereas pathological tissues cannot.

Calculating Method for the Solid Phase Effect Coefficient of the Solid-Fluid Two Phase Flow Centrifugal Pump

2010 ◽  
Vol 29-32 ◽  
pp. 658-663
Author(s):  
Chuan Jun Li ◽  
Gang Yu ◽  
Xin Wang
Keyword(s):  
Differential Equation ◽  
Centrifugal Pump ◽  
Two Phase Flow ◽  
Solid Phase ◽  
High Accuracy ◽  
Phase Flow ◽  
Phase Effect ◽  
Two Phase ◽  
Error Band ◽  
Calculating Method

In order to acquire the solid-fluid two phase flow centrifugal pump’s slurry head according with the fact, the solid phase effect coefficient must be calculated precisely. By analysising the acting forces on the solid particle, its moving differential equation was established. And the calculating formula of the solid phase effect coefficient was deduced based on the equation. For the sake of verifying its validity, a test of contrast and comparison on the calculating slurry heads by some ways was carried out. The results shows that the relative error values of the slurry head calculated are less than 2.00% with a small and stably error band. The method has the advantage of simple calculating process, high accuracy, low randomness and good practicability.

High-Performance Liquid Chromatographic Determination of Memantine in Human Urine Following Solid-Phase Extraction and Precolumn Derivatization

2013 ◽  
Vol 96 (6) ◽  
pp. 1302-1307 ◽  
Author(s):  
Karim Michail ◽  
Hoda Daabees ◽  
Youssef Beltagy ◽  
Magdy Abd Elkhalek ◽  
Mona Khamis
Keyword(s):  
Human Urine ◽  
High Performance ◽  
Solid Phase ◽  
Internal Standard ◽  
Chromatographic Determination ◽  
Therapeutic Drug ◽  
Time Interval ◽  
Precolumn Derivatization ◽  
Uv Detector

Abstract A validated HPLC-UV method is presented for the quantification of urinary memantine hydrochloride, a novel medication approved to treat moderate and advanced cases of Alzheimer's disease. The drug and amantadine hydrochloride, the internal standard, were extracted from human urine using SPE. The extract was then buffered and derivatized at room temperature using o-phthalaldehyde in the presence of N-acetyl-L-cyteine. Chromatographic separation of the formed derivatives was achieved on a C18 column using methanol–water mobile phase adjusted to pH 7 and pumped isocratically at 1 mL/min. The UV detector was set at 340 nm. The chromatographic run time did not exceed 10 min. The LOD and LOQ were 8 and 20 ng/mL, respectively. The RSDs for intraday and interday precisions did not exceed 5.5%. The method was used to monitor memantine hydrochloride in human urine in order to determine an appropriate sampling interval for future noninvasive therapeutic drug monitoring. The assay could also be applied to the determination of amantadine. The described assay showed that a postdosing time interval of 25–75 h seems adequate for sampling and monitoring memantine in urine.

Sign in / Sign up

Export Citation Format

Share Document