A steady-state and transient analysis of the electron transport that occurs within bulk wurtzite zinc-magnesium-oxide alloys subjected to high-fields

MRS Advances ◽  
2018 ◽  
Vol 3 (59) ◽  
pp. 3439-3444 ◽  
Author(s):  
Poppy Siddiqua ◽  
Walid A. Hadi ◽  
Michael S. Shur ◽  
Stephen K. O’Leary
Keyword(s):  
Steady State ◽  
Electron Transport ◽  
Magnesium Oxide ◽  
Transient Analysis ◽  
Alloy System ◽  
Magnesium Content ◽  
High Fields ◽  
Zinc Magnesium Oxide ◽  
The Impact ◽  
Bulk Alloys

ABSTRACTWe present some recently acquired results corresponding to the nature of the electron transport that occurs within bulk alloys of zinc-magnesium-oxide. These results are obtained using three-valley ensemble semi-classical Monte Carlo electron transport simulations. The impact that the magnesium content plays in shaping the form of the electron transport related characteristics associated with this alloy system is explored. Both steady-state and transient electron transport results are examined. The device implications of these results are then commented upon.

How changes in the crystal temperature and the doping concentration impact upon bulk wurtzite zinc oxide’s electron transport response

MRS Advances ◽  
2019 ◽  
Vol 4 (50) ◽  
pp. 2673-2678
Author(s):  
Poppy Siddiqua ◽  
Walid A. Hadi ◽  
Michael S. Shur ◽  
Stephen K. O’Leary
Keyword(s):  
Monte Carlo ◽  
Steady State ◽  
Electron Transport ◽  
Drift Velocity ◽  
Doping Concentration ◽  
Electron Drift ◽  
Crystal Temperature ◽  
Transient Transport ◽  
Transport Response ◽  
The Impact

ABSTRACTThe role that changes in the crystal temperature and the doping concentration play in shaping the character of the steady-state and transient transport response of electrons within bulk wurtzite zinc oxide will be examined. Monte Carlo electron transport simulations are drawn upon for the purposes of this analysis. We find that both the crystal temperature and the doping concentration greatly influence the character of the steady-state and transient electron transport response. In particular, for the case of steady-state electron transport, the peak drift velocity decreases by 30% as the crystal temperature is increased from 100 to 700 K, this decrease in velocity being only 20% as the doping concentration is increased from 1015 to 1019 cm-3. The impact on the transient electron drift velocity is not as acute.

Influence of Flow Geometry on Sandface Temperatures During Single-Phase Oil Production: Dimensionless Analysis

SPE Journal ◽  
2016 ◽  
Vol 21 (03) ◽  
pp. 0928-0937 ◽  
Author(s):  
J. F. App
Keyword(s):  
Steady State ◽  
Flow Regime ◽  
Transient Analysis ◽  
Numerical Solutions ◽  
Temperature Behavior ◽  
Transient Temperature ◽  
Linear Flow ◽  
Dimensionless Analysis ◽  
Flow Geometry ◽  
The Impact

Summary This paper evaluates the impact of flow geometry on sandface temperature behavior under conditions of high drawdown in which Joule-Thomson thermal effects are significant. The temperature behavior of both radial- and linear-flow regimes is evaluated under steady-state and transient conditions. Through a dimensionless analysis of the thermal-energy equation, a systematic evaluation of the contributing terms is presented. The steady-state analysis is based on analytic solutions that demonstrate identical temperature behavior at asymptotic limits but are offset by a geometric factor at intermediary Péclet numbers. The transient analysis is based on a combination of analytical and numerical solutions. The transient analysis demonstrates that temperature changes occur earlier in time for the radial geometry compared with the linear geometry. The impetus behind this study is to address the impact of transient-temperature development in hydraulically fractured vs. nonhydraulically fractured vertical completions. The flow regime in nonhydraulically fractured vertical completions is radial whereas in hydraulically fractured vertical completions a linear-flow regime can dominate a significant portion of the flow history. All analyses assume that skin, wellbore-storage, and thermal-storage effects are negligible.

scholarly journals Advanced Constitutive Modeling of the Thixotropic Elasto-Visco-Plastic Behavior of Blood: Steady-State Blood Flow in Microtubes

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 367
Author(s):  
Konstantinos Giannokostas ◽  
Yannis Dimakopoulos ◽  
Andreas Anayiotos ◽  
John Tsamopoulos
Keyword(s):  
Blood Flow ◽  
Steady State ◽  
Constitutive Model ◽  
Blood Plasma ◽  
Constitutive Modeling ◽  
Flow Direction ◽  
Momentum Balance ◽  
Plastic Behavior ◽  
Flow Investigation ◽  
The Impact

The present work focuses on the in-silico investigation of the steady-state blood flow in straight microtubes, incorporating advanced constitutive modeling for human blood and blood plasma. The blood constitutive model accounts for the interplay between thixotropy and elasto-visco-plasticity via a scalar variable that describes the level of the local blood structure at any instance. The constitutive model is enhanced by the non-Newtonian modeling of the plasma phase, which features bulk viscoelasticity. Incorporating microcirculation phenomena such as the cell-free layer (CFL) formation or the Fåhraeus and the Fåhraeus-Lindqvist effects is an indispensable part of the blood flow investigation. The coupling between them and the momentum balance is achieved through correlations based on experimental observations. Notably, we propose a new simplified form for the dependence of the apparent viscosity on the hematocrit that predicts the CFL thickness correctly. Our investigation focuses on the impact of the microtube diameter and the pressure-gradient on velocity profiles, normal and shear viscoelastic stresses, and thixotropic properties. We demonstrate the microstructural configuration of blood in steady-state conditions, revealing that blood is highly aggregated in narrow tubes, promoting a flat velocity profile. Additionally, the proper accounting of the CFL thickness shows that for narrow microtubes, the reduction of discharged hematocrit is significant, which in some cases is up to 70%. At high pressure-gradients, the plasmatic proteins in both regions are extended in the flow direction, developing large axial normal stresses, which are more significant in the core region. We also provide normal stress predictions at both the blood/plasma interface (INS) and the tube wall (WNS), which are difficult to measure experimentally. Both decrease with the tube radius; however, they exhibit significant differences in magnitude and type of variation. INS varies linearly from 4.5 to 2 Pa, while WNS exhibits an exponential decrease taking values from 50 mPa to zero.

The electron transport that occurs within wurtzite zinc oxide and the application of stress

MRS Advances ◽  
2017 ◽  
Vol 2 (48) ◽  
pp. 2627-2632 ◽  
Author(s):  
Poppy Siddiqua ◽  
Michael S. Shur ◽  
Stephen K. O’Leary
Keyword(s):  
Monte Carlo ◽  
Zinc Oxide ◽  
Electron Transport ◽  
Velocity Field ◽  
Monte Carlo Simulations ◽  
Significant Role ◽  
Energy Gap ◽  
Device Application ◽  
The Impact

ABSTRACTWe examine how stress has the potential to shape the character of the electron transport that occurs within ZnO. In order to narrow the scope of this analysis, we focus on a determination of the velocity-field characteristics associated with bulk wurtzite ZnO. Monte Carlo simulations of the electron transport are pursued for the purposes of this analysis. Rather than focusing on the impact of stress in of itself, instead we focus on the changes that occur to the energy gap through the application of stress, i.e., energy gap variations provide a proxy for the amount of stress. Our results demonstrate that stress plays a significant role in shaping the form of the velocity-field characteristics associated with ZnO. This dependence could potentially be exploited for device application purposes.

A Monte Carlo study of electron‐hole scattering and steady‐state minority‐electron transport in GaAs

1988 ◽  
Vol 53 (22) ◽  
pp. 2205-2207 ◽  
Author(s):  
K. Sadra ◽  
C. M. Maziar ◽  
B. G. Streetman ◽  
D. S. Tang
Keyword(s):  
Monte Carlo ◽  
Steady State ◽  
Electron Transport ◽  
Monte Carlo Study ◽  
Electron Hole

Evaluation of Single-Hole Hydraulic Tests in Fractured Crystalline Rock by Steady-State and Transient Methods: A Comparison

1985 ◽  
Vol 50 ◽  
Author(s):  
J-E. Andersson ◽  
O. Persson
Keyword(s):  
Steady State ◽  
Hydraulic Conductivity ◽  
Flow Pattern ◽  
Transient Analysis ◽  
Crystalline Rock ◽  
Steady State Analysis ◽  
Single Hole ◽  
The Mean ◽  
Transient Methods ◽  
State Analysis

AbstractThe results from a large number of single-hole packer tests in crystalline rock from three test sites in Sweden have been analysed statistically. Average hydraulic conductivity values for 25 m long test intervals along boreholes with a maximal length of about 700 m are used in this study. A comparison between steady state and transient analysis of the same test data has been performed.The mean vaule of the hydraulic conductivity determined from steady state analysis was found to be about two to three times higher compared to transient analysis. However, in some cases the steady state analysis resulted in 10 to 20 times higher values compared to the transient analysis. Such divergence between the two analysis methods may be caused by deviations from the assumed flow pattern, borehole skin effects and influence of hydraulic boundaries.

scholarly journals Research on Cooperative Innovation Behavior of Industrial Cluster Based on Subject Adaptability

2016 ◽  
Vol 2016 ◽  
pp. 1-19 ◽  
Author(s):  
Xiaohui Jia ◽  
Minghui Jiang ◽  
Lei Shi
Keyword(s):  
Steady State ◽  
Evolutionary Game ◽  
Industrial Cluster ◽  
Industrial Clusters ◽  
Government Support ◽  
Correlated Equilibrium ◽  
Game Model ◽  
Cooperative Innovation ◽  
The Cost ◽  
The Impact

From the perspective of the interactive cooperation among subjects, this paper portrays the process of cooperative innovation in industrial cluster, in order to capture the correlated equilibrium relationship among them. Through the utilization of two key tools, evolutionary stable strategy and replicator dynamics equations, this paper considers the cost and gains of cooperative innovation and the amount of government support as well as other factors to build and analyze a classic evolutionary game model. On this basis, the subject’s own adaptability is introduced, which is regarded as the system noise in the stochastic evolutionary game model so as to analyze the impact of adaptability on the game strategy selection. The results show that, in the first place, without considering subjects’ adaptability, their cooperation in industrial clusters depends on the cost and gains of innovative cooperation, the amount of government support, and some conditions that can promote cooperation, namely, game steady state. In the second place after the introduction of subjects’ adaptability, it will affect both game theory selection process and time, which means that the process becomes more complex, presents the nonlinear characteristics, and helps them to make faster decisions in their favor, but the final steady state remains unchanged.

Life Prediction of Power Turbine Components for High Exhaust Back Pressure Applications: Part I — Disks

2015 ◽  
Author(s):  
Dipankar Dua ◽  
Brahmaji Vasantharao
Keyword(s):  
Steady State ◽  
Secondary Flow ◽  
Gas Turbines ◽  
Life Prediction ◽  
Creep Damage ◽  
Back Pressure ◽  
System Level ◽  
Cyclic Life ◽  
Power Turbine ◽  
The Impact

Industrial and aeroderivative gas turbines when used in CHP and CCPP applications typically experience an increased exhaust back pressure due to pressure losses from the downstream balance-of-plant systems. This increased back pressure on the power turbine results not only in decreased thermodynamic performance but also changes power turbine secondary flow characteristics thus impacting lives of rotating and stationary components of the power turbine. This Paper discusses the Impact to Fatigue and Creep life of free power turbine disks subjected to high back pressure applications using Siemens Energy approach. Steady State and Transient stress fields have been calculated using finite element method. New Lifing Correlation [1] Criteria has been used to estimate Predicted Safe Cyclic Life (PSCL) of the disks. Walker Strain Initiation model [1] is utilized to predict cycles to crack initiation and a fracture mechanics based approach is used to estimate propagation life. Hyperbolic Tangent Model [2] has been used to estimate creep damage of the disks. Steady state and transient temperature fields in the disks are highly dependent on the secondary air flows and cavity dynamics thus directly impacting the Predicted Safe Cyclic Life and Overall Creep Damage. A System-level power turbine secondary flow analyses was carried out with and without high back pressure. In addition, numerical simulations were performed to understand the cavity flow dynamics. These results have been used to perform a sensitivity study on disk temperature distribution and understand the impact of various back pressure levels on turbine disk lives. The Steady Sate and Transient Thermal predictions were validated using full-scale engine test and have been found to correlate well with the test results. The Life Prediction Study shows that the impact on PSCL and Overall Creep damage for high back pressure applications meets the product design standards.

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