Theoretical Background and State-of-the-Art

2020 ◽  
pp. 13-43
Author(s):  
Themistoklis Diamantopoulos ◽  
Andreas L. Symeonidis
Keyword(s):  
State Of The Art ◽  
Theoretical Background

scholarly journals Efficient Rank-Based Diffusion Process with Assured Convergence

2021 ◽  
Vol 7 (3) ◽  
pp. 49
Author(s):  
Daniel Carlos Guimarães Pedronette ◽  
Lucas Pascotti Valem ◽  
Longin Jan Latecki
Keyword(s):  
Diffusion Process ◽  
Learning Strategies ◽  
State Of The Art ◽  
Representation Learning ◽  
Theoretical Background ◽  
High Dimensional ◽  
Visual Features ◽  
Learning Approaches ◽  
Previous Decade ◽  
Asymptotic Complexity

Visual features and representation learning strategies experienced huge advances in the previous decade, mainly supported by deep learning approaches. However, retrieval tasks are still performed mainly based on traditional pairwise dissimilarity measures, while the learned representations lie on high dimensional manifolds. With the aim of going beyond pairwise analysis, post-processing methods have been proposed to replace pairwise measures by globally defined measures, capable of analyzing collections in terms of the underlying data manifold. The most representative approaches are diffusion and ranked-based methods. While the diffusion approaches can be computationally expensive, the rank-based methods lack theoretical background. In this paper, we propose an efficient Rank-based Diffusion Process which combines both approaches and avoids the drawbacks of each one. The obtained method is capable of efficiently approximating a diffusion process by exploiting rank-based information, while assuring its convergence. The algorithm exhibits very low asymptotic complexity and can be computed regionally, being suitable to outside of dataset queries. An experimental evaluation conducted for image retrieval and person re-ID tasks on diverse datasets demonstrates the effectiveness of the proposed approach with results comparable to the state-of-the-art.

X-ray absorption spectroscopy: state-of-the-art analysis

2002 ◽  
Vol 10 (1) ◽  
pp. 26-42 ◽  
Author(s):  
C. R. Natoli ◽  
M. Benfatto ◽  
S. Della Longa ◽  
K. Hatada
Keyword(s):  
Structural Analysis ◽  
State Of The Art ◽  
Theoretical Background ◽  
Point Of View ◽  
Biological Applications ◽  
Present Material ◽  
X Ray ◽  
Spectral Fitting ◽  
Art Analysis ◽  
X Ray Absorption

State-of-the-art techniques for analysing X-ray absorption spectra are reviewed, with an eye to biological applications. Recent attempts to perform full spectral fitting of the XANES energy region and beyond for the purpose of structural analysis have met with encouraging success. The present paper analyses the theoretical motivations behind this success and indicates routes for future improvements. The theoretical background is not entirely new, although the point of view is, and some sections and appendices present material that the authors believe has never been published before. The aim of this paper is to provide a theoretical analysis that is as self-contained as possible.

On the Possibility to Compute Slowly-Varying Drift in a CFD Solver

2018 ◽  
Author(s):  
Charles Monroy ◽  
Charaf Ouled Housseine ◽  
Sime Malenica
Keyword(s):  
State Of The Art ◽  
Low Frequency ◽  
Theoretical Background ◽  
Linear Potential ◽  
Forward Speed ◽  
The Past ◽  
Strong Current ◽  
Added Resistance In Waves ◽  
Wave Trains ◽  
Offshore Industry

Slowly-varying drift is a phenomenon very familiar to offshore industry, but usually not so much relevant or discussed in naval industry. The classical theoretical background consists in considering a bichromatic wave composed of two regular wave trains of pulsations ω1 and ω2 evolving in the same direction and without any forward speed. The force which varies at low frequency (ω2 – ω1) is known as the slowly-varying drift force and is important in case of moored vessels because it may excite them at their natural periods. The equivalent application in the naval industry is related to maneuvering and added resistance in waves. However, as already indicated, up to the authors’ knowledge, there has not been much work on these issues in the past. State-of-the-art potential flow tools predict well this slowly-varying drift at zero forward speed. However, with an additional forward speed or a strong current, traditional linear potential codes are outside the scope of their underlying hypothesis and cannot predict accurately the low frequency force. With the constant rise of CPU power and accuracy of CFD solvers, this problem may now be addressed in CFD. The results of foamStar, in-house OpenFOAM solver, will be shown with and without additional forward speed.

scholarly journals Isotopic Techniques to Measure N2O, N2 and Their Sources

2021 ◽  
pp. 213-301
Author(s):  
M. Zaman ◽  
K. Kleineidam ◽  
L. Bakken ◽  
J. Berendt ◽  
C. Bracken ◽  
...  
Keyword(s):  
Stable Isotope ◽  
State Of The Art ◽  
Theoretical Background ◽  
Natural Abundance ◽  
Basic Principles ◽  
Link Type ◽  
Current State ◽  
Numerical Tools ◽  
Enrichment Techniques ◽  
Tracing Techniques

AbstractGHGemissions are usually the result of several simultaneous processes. Furthermore, some gases such as N2 are very difficult to quantify and require special techniques. Therefore, in this chapter, the focus is on stable isotopemethods. Both natural abundance techniques and enrichment techniques are used. Especially in the last decade, a number of methodological advances have been made. Thus, this chapter provides an overview and description of a number of current state-of-the-art techniques, especially techniques using the stable isotope15N. Basic principles and recent advances of the 15N gasflux method are presented to quantify N2 fluxes, but also the latest isotopologue and isotopomermethods to identify pathways for N2O production. The second part of the chapter is devoted to 15N tracing techniques, the theoretical background and recent methodological advances. A range of different methods is presented from analytical to numerical tools to identify and quantify pathway-specific N2O emissions. While this chapter is chiefly concerned with gaseous N emissions, a lot of the techniques can also be applied to other gases such as methane (CH4), as outlined in Sect. 10.1007/978-3-030-55396-8_5#Sec12.

scholarly journals Electrochemical Impedance Spectroscopy (EIS): Principles, Construction, and Biosensing Applications

Sensors ◽  
2021 ◽  
Vol 21 (19) ◽  
pp. 6578
Author(s):  
Hend S. Magar ◽  
Rabeay Y. A. Hassan ◽  
Ashok Mulchandani
Keyword(s):  
Electrochemical Impedance Spectroscopy ◽  
Impedance Spectroscopy ◽  
Electrochemical Impedance ◽  
State Of The Art ◽  
Theoretical Background ◽  
Review Article ◽  
Antigen Recognition ◽  
Biomedical Diagnosis ◽  
Basic Concepts ◽  
The Impact

Electrochemical impedance spectroscopy (EIS) is a powerful technique used for the analysis of interfacial properties related to bio-recognition events occurring at the electrode surface, such as antibody–antigen recognition, substrate–enzyme interaction, or whole cell capturing. Thus, EIS could be exploited in several important biomedical diagnosis and environmental applications. However, the EIS is one of the most complex electrochemical methods, therefore, this review introduced the basic concepts and the theoretical background of the impedimetric technique along with the state of the art of the impedimetric biosensors and the impact of nanomaterials on the EIS performance. The use of nanomaterials such as nanoparticles, nanotubes, nanowires, and nanocomposites provided catalytic activity, enhanced sensing elements immobilization, promoted faster electron transfer, and increased reliability and accuracy of the reported EIS sensors. Thus, the EIS was used for the effective quantitative and qualitative detections of pathogens, DNA, cancer-associated biomarkers, etc. Through this review article, intensive literature review is provided to highlight the impact of nanomaterials on enhancing the analytical features of impedimetric biosensors.

scholarly journals Wearable-Based Affect Recognition—A Review

Sensors ◽  
2019 ◽  
Vol 19 (19) ◽  
pp. 4079 ◽  
Author(s):  
Philip Schmidt ◽  
Attila Reiss ◽  
Robert Dürichen ◽  
Kristof Van Laerhoven
Keyword(s):  
State Of The Art ◽  
Affective State ◽  
Theoretical Background ◽  
Research Field ◽  
Mental Wellbeing ◽  
Affect Recognition ◽  
Affective States ◽  
Stress Monitoring ◽  
Comprehensive Overview ◽  
Wearable Systems

Affect recognition is an interdisciplinary research field bringing together researchers from natural and social sciences. Affect recognition research aims to detect the affective state of a person based on observables, with the goal to, for example, provide reasoning for the person’s decision making or to support mental wellbeing (e.g., stress monitoring). Recently, beside of approaches based on audio, visual or text information, solutions relying on wearable sensors as observables, recording mainly physiological and inertial parameters, have received increasing attention. Wearable systems enable an ideal platform for long-term affect recognition applications due to their rich functionality and form factor, while providing valuable insights during everyday life through integrated sensors. However, existing literature surveys lack a comprehensive overview of state-of-the-art research in wearable-based affect recognition. Therefore, the aim of this paper is to provide a broad overview and in-depth understanding of the theoretical background, methods and best practices of wearable affect and stress recognition. Following a summary of different psychological models, we detail the influence of affective states on the human physiology and the sensors commonly employed to measure physiological changes. Then, we outline lab protocols eliciting affective states and provide guidelines for ground truth generation in field studies. We also describe the standard data processing chain and review common approaches related to the preprocessing, feature extraction and classification steps. By providing a comprehensive summary of the state-of-the-art and guidelines to various aspects, we would like to enable other researchers in the field to conduct and evaluate user studies and develop wearable systems.

scholarly journals Internet of Things Infrastructure for Security and Safety in Public Places

Information ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 333
Author(s):  
Angelos Chatzimichail ◽  
Christos Chatzigeorgiou ◽  
Athina Tsanousa ◽  
Dimos Ntioudis ◽  
Georgios Meditskos ◽  
...  
Keyword(s):  
Data Aggregation ◽  
Situational Awareness ◽  
State Of The Art ◽  
Theoretical Background ◽  
Public Places ◽  
Security Environment ◽  
Missing Children ◽  
First Results ◽  
Health Related ◽  
Device Operation

We present the technologies and the theoretical background of an intelligent interconnected infrastructure for public security and safety. The innovation of the framework lies in the intelligent combination of devices and human information towards human and situational awareness, so as to provide a protection and security environment for citizens. The framework is currently being used to support visitors in public spaces and events, by creating the appropriate infrastructure to address a set of urgent situations, such as health-related problems and missing children in overcrowded environments, supporting smart links between humans and entities on the basis of goals, and adapting device operation to comply with human objectives, profiles, and privacy. State-of-the-art technologies in the domain of IoT data collection and analytics are combined with localization techniques, ontologies, reasoning mechanisms, and data aggregation in order to acquire a better understanding of the ongoing situation and inform the necessary people and devices to act accordingly. Finally, we present the first results of people localization and the platforms’ ontology and representation framework.

scholarly journals On the development of high-frequency torsional impact drilling techniques for hard formation drilling

2018 ◽  
Vol 10 (6) ◽  
pp. 168781401878160 ◽  
Author(s):  
Liping Tang ◽  
Xiaohua Zhu
Keyword(s):  
High Frequency ◽  
Laboratory Experiments ◽  
Control Method ◽  
State Of The Art ◽  
Theoretical Background ◽  
Stick Slip ◽  
Real Time Measurement ◽  
Deep Wells ◽  
Hard Formation ◽  
Active Control Method

Stick-slip vibration is a big problem that the drilling of deep wells has to face, especially for drilling of tough formations. This type of vibration leads to failure problems, reduces the rate of penetration, and lowers the borehole quality. Suppression techniques for stick-slip vibration, for example, active control method based on real-time measurement, play important roles in improving the drilling efficiency. The high-frequency torsional impact drilling, however, provides a cheaper and more stable way to mitigate stick-slip in many conditions. This work is aimed to study the high-frequency torsional impact generator, which is used to achieve the function, for this new technique. First, state-of-the-art of high-frequency torsional impact generator is studied by schematically illustrating the existing four structures and their operating principles, followed by comments for these structures. Second, theoretical background of the high-frequency torsional impact drilling is presented, showing how the high-frequency torsional impact generator works to mitigate stick-slip and improve drilling efficiency. Finally, an optimally designed high-frequency torsional impact generator is schematically described. It is an improved version of the assembly of United Diamond and the improvements are based on results of a series of laboratory experiments.

scholarly journals Extended horn gears in 3D maypole braiding

2018 ◽  
Vol 1 ◽  
pp. 251522111878674 ◽  
Author(s):  
Yordan Kyosev ◽  
Peter Gleßner
Keyword(s):  
Numerical Simulation ◽  
Theoretical Analysis ◽  
Theoretical Result ◽  
State Of The Art ◽  
Theoretical Background ◽  
The State ◽  
Specific Configuration ◽  
Practical Validation

This article presents the theoretical background for the arrangement of horn gears in maypole braiding machines in order to act as equivalent larger gears. The theoretical analysis is verified with numerical simulation and experiments. After review about the state of the art, an analysis of the process for one specific configuration of horn gears is given. This analysis demonstrates how a set of horn gears can be arranged to work as an equivalent to a larger one horn gear. The braiding equation is checked as remaining valid for such extended configurations, too. The theoretical result is verified using numerical simulation for all cases and practical validation for several variants. The theoretical rules give a clear extension of the current braiding knowledge and make the design of complex configurations of braiding machines more systematic and clear.

scholarly journals Inmigración, deporte y escuela. Revisión del estado de la cuestión (Immigration, sport and school. A review of the state of the art)

Retos ◽  
2016 ◽  
pp. 19-24
Author(s):  
Bastian Carter-Thuillier ◽  
Víctor Manuel López Pastor ◽  
Francisco Gallardo Fuentes
Keyword(s):  
Social Integration ◽  
Educational Development ◽  
State Of The Art ◽  
Theoretical Background ◽  
Educational Setting ◽  
Future Studies ◽  
Advantages And Disadvantages ◽  
Theoretical Approaches ◽  
The Relationship ◽  
Practical Implications

El presente artículo tiene por objeto analizar y exponer la relación entre inmigración, deporte y escuela, examinando las posibilidades pedagógicas que ofrece la convergencia de estos tres elementos desde el escenario educativo formal. Para ello se desarrolla una discusión basada en diferentes antecedentes teóricos. La revisión ha sido llevada a cabo en diferentes bases de datos y fuentes de indización internacional: WOK, SCOPUS, ERIC, SCIELO, DIALNET, REDALYC, SPORTDISCUS y GOOGLE ACADÉMICO, además de libros especializados en campos próximos a la temática. La revisión indica que existen diferentes enfoques teóricos respecto a inmigración, deporte e interacción social, especialmente en lo relacionado con la inmigración y la integración social en la escuela. Se describen las ventajas y desventajas encontradas en la literatura sobre las prácticas deportivas como herramientas para la integración e inclusión social, así como para el desarrollo educativo. Precisamente en la relación entre deporte educativo e inmigración es donde encontramos la mayor cantidad de antecedentes teóricos y experiencias positivas al respecto. En las conclusiones se aportan algunas consideraciones finales sobre el tópico investigado, así como posibles implicaciones prácticas asociadas a procesos de intervención y prospectiva.Abstract. This paper aims to analyze and explain the relationship between immigration, sport, and school, by examining the educational possibilities offered by the convergence of these three elements within the formal educational setting. A discussion based on different theoretical background is carried out. The review has been performed through different databases and international indexing sources: WOK, SCOPUS, ERIC, SCIELO, DIALNET, REDALYC, ACADEMIC GOOGLE, SPORTDISCUS, and also in specialized books in the field. The review indicates the existence of different theoretical approaches related to immigration, sport, and social interaction, especially in relation with immigration and social integration in school. Furthermore, this research describes the advantages and disadvantages of sports practices as a tool for social integration and inclusion, as well as for educational development, as they were highlighted in the existent literature. The greatest amount of theoretical background and useful lessons were found precisely on the relationship between educational sport and immigration. In the conclusion some final remarks on the topic investigated are given, as well as practical implications associated with intervention processes and possible future studies.

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