scholarly journals Effect of surface charge self-organization on gate-induced 2D electron and hole systems

2020 ◽  
Vol 6 (3) ◽  
pp. 101-106
Author(s):  
Vitaly A. Tkachenko ◽  
Olga A. Tkachenko ◽  
Dmitry G. Baksheev ◽  
Oleg P. Sushkov
Keyword(s):  
Structural Factor ◽  
Freezing Temperature ◽  
Metropolis Algorithm ◽  
Self Organization ◽  
Surface Charges ◽  
Carrier Scattering ◽  
Wave Numbers ◽  
Small Wave ◽  
The One ◽  
Effect Of Surface

A simple model has been suggested for describing self-organization of localized charges and quantum scattering in undoped GaAs/AlGaAs structures with 2D electron or hole gas created by applying respective gate bias. It has been assumed that these metal / dielectric / undoped semiconductor structures exhibit predominant carrier scattering at localized surface charges which can be located at any point of the plane imitating the GaAs / dielectric interface. The suggested model considers all these surface charges and respective image charges in metallic gate as a closed thermostated system. Electrostatic self-organization in this system has been studied numerically for thermodynamic equilibrium states using the Metropolis algorithm over a wide temperature range. We show that at T > 100 K a simple formula derived from the theory of single-component 2D plasma yields virtually the same behavior of structural factor at small wave numbers as the one given by the Metropolis algorithm. The scattering times of gate-induced carriers are described with formulas in which the structural factor characterizes frozen disorder in the system. The main contribution in these formulas is due to behavior of the structural factor at small wave numbers. Calculation using these formulas for the case of disorder corresponding to infinite T has yielded 2–3 times lower scattering times than experimentally obtained ones. We have found that the theory agrees with experiment at disorder freezing temperatures T ≈ 1000 K for 2D electron gas specimen and T ≈ 700 K for 2D hole gas specimen. These figures are the upper estimates of freezing temperature for test structures since the model ignores all the disorder factors except temperature.

scholarly journals Analytical solution of one-dimensional Pennes’ bioheat equation

Open Physics ◽  
2020 ◽  
Vol 18 (1) ◽  
pp. 1084-1092
Author(s):  
Hongyun Wang ◽  
Wesley A. Burgei ◽  
Hong Zhou
Keyword(s):  
Analytical Solution ◽  
Radiofrequency Energy ◽  
Bioheat Equation ◽  
Surface Cooling ◽  
One Dimensional ◽  
The Fourier Transform ◽  
The One ◽  
Parameter Values ◽  
Mathematical Derivation ◽  
Effect Of Surface

Abstract Pennes’ bioheat equation is the most widely used thermal model for studying heat transfer in biological systems exposed to radiofrequency energy. In their article, “Effect of Surface Cooling and Blood Flow on the Microwave Heating of Tissue,” Foster et al. published an analytical solution to the one-dimensional (1-D) problem, obtained using the Fourier transform. However, their article did not offer any details of the derivation. In this work, we revisit the 1-D problem and provide a comprehensive mathematical derivation of an analytical solution. Our result corrects an error in Foster’s solution which might be a typo in their article. Unlike Foster et al., we integrate the partial differential equation directly. The expression of solution has several apparent singularities for certain parameter values where the physical problem is not expected to be singular. We show that all these singularities are removable, and we derive alternative non-singular formulas. Finally, we extend our analysis to write out an analytical solution of the 1-D bioheat equation for the case of multiple electromagnetic heating pulses.

scholarly journals The Good, the Bad and the Ugly? The Dynamic Interplay Between Educational Practice, Policy and Research

2014 ◽  
Vol 11 (2) ◽  
Author(s):  
Paul Van Geert ◽  
Henderien Steenbeek
Keyword(s):  
Complex System ◽  
Educational Practice ◽  
The Other ◽  
Self Organization ◽  
Other Hand ◽  
The Creation ◽  
Characteristic Features ◽  
The One ◽  
Dynamic Interplay ◽  
Interacting Components

The notion of complexity — as in “education is a complex system” — has two different meanings. On the one hand, there is the epistemic connotation, with “Complex” meaning “difficult to understand, hard to control”. On the other hand, complex has a technical meaning, referring to systems composed of many interacting components, the interactions of which lead to self organization and emergence. For agents, participating in a complex system such as education, it is important that they can reduce the epistemic complexity of the system, in order to allow them to understand the system, to accomplish their goals and to evaluate the results of their activities. We argue that understanding, accomplishing and evaluation requires the creation of simplex systems, which are praxis-based forms of representing complexity. Agents participating in the complex system may have different kinds of simplex systems governing their understanding and praxis. In this article, we focus on three communities of agents in education — educators, researchers and policymakers — and discuss characteristic features of their simplex systems. In particular, we focus on the simplex system of educational researchers, and we discuss interactions — including conflicts or incompatibilities — between their simplex systems and those of educators and policymakers. By making some of the underlying features of the educational researchers’ simplex systems more explicit – including the underlying notion of causality and the use of variability as a source of knowledge — we hope to contribute to clarifying some of the hidden conflicts between simplex systems of the communities participating in the complex system of education.

Effect of surface charges on the polarization of BaTiO 3 thin films investigated by UHV ‐ SPM

2018 ◽  
Vol 101 (10) ◽  
pp. 4677-4688 ◽  
Author(s):  
Keigo Suzuki ◽  
Tadasu Hosokura ◽  
Takafumi Okamoto ◽  
James Steffes ◽  
Koji Murayama ◽  
...  
Keyword(s):  
Thin Films ◽  
Surface Charges ◽  
Effect Of Surface

Worker Involvement, the New Technologies and New Forms of Company Organization

1999 ◽  
Vol 4 (1) ◽  
pp. 69-82
Author(s):  
Gerhard Leminsky
Keyword(s):  
Personal Development ◽  
Management Strategy ◽  
New Technologies ◽  
Self Organization ◽  
Practical Implementation ◽  
Democratic Participation ◽  
Grass Roots ◽  
The Past ◽  
The One ◽  
Real Responsibility

The concept of democratic participation has been receiving wide attention over the past few years — both in Germany and at the European level. Unfortunately, the same cannot be said for social and corporate praxis where practical implementation of the idea encounters ingrained resistance and reservations from different groups. On the one hand, the trades unions are afraid that forms of direct democratic involvement will act in competition to the institutionalized forms of in-company codetermination; on the other, many managers — having discovered that worker involvement is a good way to improve both productivity and quality — are simultaneously opposed to the transfer to the grass roots of any real responsibility or decision making rights. Nevertheless, the narrow use of employee participation as a mere management strategy should not obscure our view of the opportunities for self-organization, democratization and personal development that are inherent to democratic participation.

The Effect of Surface Charges in Vacuum Discharge Tubes

1925 ◽  
Vol 25 (1) ◽  
pp. 58-65 ◽  
Author(s):  
A. R. Olson ◽  
T. F. Young
Keyword(s):  
Surface Charges ◽  
Vacuum Discharge ◽  
Discharge Tubes ◽  
Effect Of Surface

Synthese und Aggregatbildung eines 5-Hydroxy-2,5-dihydropyrrols. Enantiomerenreine, eindimensionale Stränge durch Wasserstoffbrückenbindungen und chiroselektive Selbstorganisation/Synthesis and Aggregation of a 5-H ydroxy-2,5-dihydropyrrole. Enantiomerically Pure, One-dimensional Strands via Hydrogen Bonds and Chiroselective Self Organization

1999 ◽  
Vol 54 (2) ◽  
pp. 179-186 ◽  
Author(s):  
Rolf W. Saalfrank ◽  
Jochen Nachtrab ◽  
Stephan Reck
Keyword(s):  
Hydrogen Bonds ◽  
Ring Opening ◽  
Self Organization ◽  
Nucleophilic Attack ◽  
X Ray Diffraction ◽  
Enantiomerically Pure ◽  
One Dimensional ◽  
X Ray ◽  
Self Selection ◽  
The One

Reaction of dimethyl 1,3-acetonedicarboxylate 8 with oxalylchloride 2 and magnesium chloride as catalyst yielded 2,3-dioxo-2,3-dihydrofuran 9, which is in equilibrium with tautomer 10 (9:10 = 1:2). Addition of thionyl chloride to a mixture of 9/10 afforded 3-chloro-2(5H)-furanone 11. The structure of 11 was unequivocally established by X-ray diffraction, which indirectly proved the structure of 10 as well. Ring opening of 11 by nucleophilic attack with benzylamine 14 in C2-position and subsequent recyclization led to racemic 3-chloro-5-hydroxy-2-oxo-2,5-dihydropyrrole 15. According to a single crystal X-ray analysis, 15 aggregates via stereospecific self selection through hydrogen bonds to give chiroselectively the one-dimensional strands ∞1[(S)-15] and ∞1[( R)-15]

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