scholarly journals Statistical model of phonon scattering on rough boundaries of nanostructures

2021 ◽  
Vol 2057 (1) ◽  
pp. 012111
Author(s):  
A A Barinov ◽  
V I Khvesyuk
Keyword(s):  
Heat Transfer ◽  
Statistical Model ◽  
Phonon Scattering ◽  
Rapid Development ◽  
Decisive Role ◽  
Comprehensive Analysis ◽  
Urgent Task ◽  
Semiconductor Electronics ◽  
Ballistic Heat Transfer ◽  
Rough Boundaries

Abstract Because of the rapid development of semiconductor electronics and the tendency to size reduction of the elements of transistors, there is an urgent task of assessing the heat transfer regime, which determines the ability to maintain the required thermal regime. In this work, the heat transfer in micro- and nanostructures in silicon is considered, and a comprehensive analysis of factors determining the heat transfer regime is carried out. In particular, the effect of the interaction of phonons with the sample boundaries in the quasi-ballistic and ballistic heat transfer regimes, where these processes play a decisive role, is evaluated using statistical model of phonon scattering on rough boundaries of samples.

The public and the private: reconfiguring the interrelationship during a civil act

2019 ◽  
pp. 53-69
Author(s):  
Natalia Kostenko
Keyword(s):  
Public Sphere ◽  
Public Space ◽  
Rapid Development ◽  
Online Communication ◽  
Decisive Role ◽  
Physical Interaction ◽  
Bare Life ◽  
Public And Private ◽  
The Public ◽  
The Public Sphere

The subject matter of research interest here is the movement of sociological reflection concerning the interplay of public and private realms in social, political and individual life. The focus is on the boundary constructs embodying publicity, which are, first of all, classical models of the space of appearance for free citizens of the polis (H. Arendt) and the public sphere organised by communicative rationality (Ju. Habermas). Alternative patterns are present in modern ideas pertaining to the significance of biological component in public space in the context of biopolitics (M. Foucault), “inclusive exclusion of bare life” (G. Agamben), as well as performativity of corporeal and linguistic experience related to the right to participate in civil acts such as popular assembly (J. Butler), where the established distinctions between the public and the private are levelled, and the interrelationship of these two realms becomes reconfigured. Once the new media have come into play, both the structure and nature of the public sphere becomes modified. What assumes a decisive role is people’s physical interaction with online communication gadgets, which instantly connect information networks along various trajectories. However, the rapid development of information technology produces particular risks related to the control of communications industry, leaving both public and private realms unprotected and deforming them. This also urges us to rethink the issue of congruence of the two ideas such as transparency of societies and security.

scholarly journals The inverse coefficient problem of heat transfer in layered nanostructures

2017 ◽  
Vol 20 (3) ◽  
pp. 213-219
Author(s):  
K. K. Abgarian ◽  
R. G. Noskov ◽  
D. L. Reviznikov
Keyword(s):  
Heat Transfer ◽  
Inverse Problem ◽  
Thermal Resistance ◽  
Transfer Problem ◽  
Dominant Role ◽  
Rapid Development ◽  
Problem Solution ◽  
Microwave Range ◽  
Contact Thermal Resistance ◽  
Resistance Coefficients

The rapid development of electronics leads to the creation and use of electronic components of small dimensions, including nanoelements of complex, layered structure. The search for effective methods for cooling electronic systems dictates the need for the development of methods for the numerical analysis of heat transfer in nanostructures. A characteristic feature of energy transfer in such systems is the dominant role of contact thermal resistance at interlayer interfaces. Since the contact resistance depends on a number of factors associated with the technology of heterostructures manufacturing, it is of great importance to determine the corresponding coefficients from the results of temperature measurements.The purpose of this paper is to evaluate the possibility of reconstructing the thermal resistance coefficients at the interfaces between layers by solving the inverse problem of heat transfer.The complex of algorithms includes two major blocks — a block for solving the direct heat transfer problem in a layered nanostructure and an optimization block for solving the inverse problem. The direct problem was formulated in an algebraic (finite difference) form under the assumption of a constant temperature within each layer, which is due to the small thickness of the layers. The inverse problem was solved in the extreme formulation, the optimization was carried out using zero-order methods that do not require the calculation of the derivatives of the optimized function. As a basic optimization algorithm, the Nelder—Mead method was used in combination with random restarts to search for a global minimum.The results of the identification of the contact thermal resistance coefficients obtained in the framework of a quasi-real experiment are presented. The accuracy of the identification problem solution is estimated as a function of the number of layers in the heterostructure and the «measurements» error.The obtained results are planned to be used in the new technique of multiscale modeling of thermal regimes of the electronic component base of the microwave range, when identifying the coefficients of thermal conductivity of heterostructure.

scholarly journals Evaluation of the security of the scope of culture expert method

2019 ◽  
pp. 115-125
Author(s):  
Sergiy Kuchyn
Keyword(s):  
National Security ◽  
Security Policy ◽  
Rapid Development ◽  
Developed Countries ◽  
Practical Implementation ◽  
Security Culture ◽  
Urgent Task ◽  
Main Components ◽  
Weight Coefficients ◽  
Research Analysis

Introduction. Ensuring national security is an urgent task for modern Ukraine. The national culture and its infrastructure components are given special attention in developed countries. Achieving the pace of rapid development of the national economy is now an important scientific and practical task. Ensuring the security of the sphere of culture is one of the priority directions of state security policy. Methods. The following methods of scientific knowledge are used in the course of the research: analysis, synthesis, grouping, analytical method, forecast method, study of scientific and statistical sources, tabular method, expert method. Results. The article proposes an approach to assessing the level of security of the sphere of culture by the indices of macroeconomic and social and demographic security. The article has received a practical implementation of the approach to assessing the level of security of the sphere of culture by an expert method. The conducted research has allowed to reveal a state of safety of a sphere of culture. The weight coefficients of economic and social and demographic security indices are obtained. Discussion. The prospect of further exploration in this direction is to develop a method of the main components and comparative analysis to assess the level of national security and security of the sphere of culture. Keywords: macroeconomic, social and demographic, security, culture, expert method, algorithm, questionnaire.

Design for Robot Control Board Based on AVR Single Chip Microcomputer

2014 ◽  
Vol 484-485 ◽  
pp. 570-573 ◽  
Author(s):  
Hong Li ◽  
Si Qing Zhang
Keyword(s):  
Robot Control ◽  
Electronic Device ◽  
Rapid Development ◽  
Decisive Role ◽  
Control Board ◽  
Single Chip ◽  
Single Chip Microcomputer ◽  
Electronic Products ◽  
Intelligent Electronic Device ◽  
Avr Mcu

Application of single chip microcomputer in the ubiquitous in modern life, as electronic products, intelligent upgrade, MCU control board play a decisive role, the design of main control board system for intelligent electronic device provides a more rapid development. This paper firstly introduces the properties of AVR single chip, the performance of AVR MCU design the control board of the corresponding circuit, and to study its programming method, is convenient for the users to operate, it is applied to the hardware.

Specific features of heat transfer in the orientationally ordered phases of molecular crystals in the region with predominant phonon-phonon scattering

2015 ◽  
Vol 41 (7) ◽  
pp. 551-556 ◽  
Author(s):  
A. I. Krivchikov ◽  
O. O. Romantsova ◽  
O. A. Korolyuk ◽  
G. A. Vdovichenko ◽  
Yu. V. Horbatenko
Keyword(s):  
Heat Transfer ◽  
Phonon Scattering ◽  
Molecular Crystals ◽  
Ordered Phases

PERFORMANCE ANALYSIS OF NANOREFRIGERANTS IN HEATED AND ROTATING CONCENTRIC AND ECCENTRIC ANNULUS CYLINDERS

2015 ◽  
Vol 77 (8) ◽  
Author(s):  
Omer A. Alawi ◽  
Nor Azwadi Che Sidik ◽  
Rizalman Mamat
Keyword(s):  
Heat Transfer ◽  
Control Volume ◽  
Rapid Development ◽  
Convection Heat Transfer ◽  
Eccentric Annulus ◽  
The Past ◽  
Nanoparticles Concentration ◽  
Horizontal Annuli ◽  
20 Nm ◽  
Rayleigh Numbers

The past decade has seen rapid development of nanofluids science in many aspects. In recent years, refrigerant-based nanofluids have been introduced as nanorefrigerants due to their significant effects over heat transfer performance. In this investigation, the Control Volume based Finite Element Method (CVFEM) is used to simulate the natural convection heat transfer of nanorefrigerant in cylindrical horizontal annuli with imposed temperatures in both surfaces. The Maxwell–Garnetts (MG) and Brinkman models are also employed to estimate the effect of thermal conductivity and viscosity of nanorefrigerant. The governing parameters are nanoparticles types, nanoparticles concentration and size, effect of Rayleigh numbers (Ra), eccentricity and rotation of inner cylinder. Results are presented in the form of isotherms and streamlines of nanorefrigerant temperature and velocity. The results indicate that Al2O3/R141b with concentration (2%) and nanoparticles size (20 nm) has the best heat transfer performances. Moreover, the heat transfer and fluid flow enhance by increasing the Rayleigh numbers (Ra). Eccentricity and rotation of inner cylinder also have effects on heat transfer characteristics. 

scholarly journals Development of methodology for evaluation of innovative IT-projects

2019 ◽  
Vol 110 ◽  
pp. 02092
Author(s):  
Lisienkova Tatiana ◽  
Liubov Lisienkova ◽  
Ekaterina Baranova ◽  
Lyudmila Nosova ◽  
Inna Tursukova
Keyword(s):  
Comprehensive Analysis ◽  
Business Development ◽  
Digital Transformation ◽  
Innovation Strategy ◽  
Financial Indicators ◽  
It Projects ◽  
Urgent Task ◽  
Methodological Approaches ◽  
The Impact ◽  
Selection And Ranking

Innovative business development based on a digital transformation is the urgent task for companies. It is able to ensure the implementation of innovation strategy and digital transformation of business. Due to the high development speed and the IT-market updating, the problem is lack of methods of rational choice of the IT-project. In practice, companies often implement IT-projects without reasonable selection and ranking, which leads to a high proportion of failed innovative IT-projects. As a result, the company does not receive a commercially successful product or service that stands out to the consumer among competitors. The evaluation of innovative IT-projects is based on the financial indicators analysis of the expected results from the implementation. The evaluation of the strategic coherence of the project is ignored. The research approaches the methodical of ranking innovative IT-projects in companies. The method consists in a comprehensive analysis of the impact of the proposed project results in various aspects of the company (strategic, environmental, organizational and technological). The study highlights the features of innovative projects in the field of information technology, a comparative analysis of methodological approaches to the evaluation of innovative projects, modified the model of acceptance of IT-innovations.

Computational Heat Transfer in Heat Exchanger Analysis and Design (Invited)

2005 ◽  
Author(s):  
Bengt Sunden
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
Rapid Development ◽  
Flow Fields ◽  
Analysis And Design ◽  
Recirculating Flow ◽  
Numerical Solution Methods ◽  
Solution Methods ◽  
Laminar And Turbulent Flow ◽  
Grid Points

Rapid development of computer capacity and advances in numerical solution methods for the governing equations of fluid flow and heat transfer have enabled CFD (computational fluid dynamics) methods to gradually become useful tools in research and development, engineering design and analysis of heat transfer equipment. However, turbulence modelling still presents a problem as accurate and reliable predictions of flow separation, reattachment, impingement and recirculating flow fields are requested. For heat exchangers both laminar and turbulent flow fields are of significance and in addition the geometries are complex, of small dimensions sometimes and turbulators or enhanced surfaces are applied. Still the demands on computers are strong as analysis of full scale equipment requires a huge amount of grid points and the computation times are long. The present paper concerns current CFD methods for thermal problems in analysis and design of heat exchangers. Application examples are presented and associated problems and limitations are discussed.

A Statistical Model of Bubble Coalescence and Its Application to Boiling Heat Flux Prediction—Part II: Experimental Validation

2009 ◽  
Vol 131 (12) ◽  
Author(s):  
Wen Wu ◽  
Barclay G. Jones ◽  
Ty A. Newell
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Statistical Model ◽  
Mechanistic Model ◽  
Model Development ◽  
Critical Diameter ◽  
Bubble Coalescence ◽  
Average Error ◽  
Static Contact ◽  
Lift Off

A mechanistic model for the boiling heat flux prediction proposed in Part I of this two-part paper (2009, “A Statistical Model of Bubble Coalescence and Its Application to Boiling Heat Flux Prediction—Part I: Model Development,” ASME J. Heat Transfer, 131, p. 121013) is verified in this part. In the first step, the model is examined by experiments conducted using R134a covering a range of pressures, inlet subcoolings, and flow velocities. The density of the active nucleation sites is measured and correlated with critical diameter Dc and static contact angle θ. Underlying submodels on bubble growth and bubble departure/lift-off radii are validated. Predictions of heat flux are compared with the experimental data with an overall good agreement observed. This model achieves an average error of ±25% for the prediction of R134a boiling curves, with the predicted maximum surface heat flux staying within ±20% of the experimentally measured critical heat flux. In the second step, the model is applied to water data measured by McAdams et al. (1949, “Heat Transfer at High Rates to Water With Surface Boiling,” Ind. Eng. Chem., 41(9), pp. 1945–1953) in vertical circular tubes. The consistency suggests that the application of this mechanistic model can be extended to other flow conditions if the underlying submodels are appropriately chosen and the assumptions made during model development remain valid.

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