1,354,237 research outputs found
KHAIT: K-9 Handler Artificial Intelligence Teaming for Collaborative Sensemaking
No full textIn urban search and rescue (USAR) operations, communication between handlers and specially trained canines is crucial but often complicated by challenging environments and the specific behaviors canines are trained to exhibit when detecting a person. Since a USAR canine often works out of sight of the handler, the handler lacks awareness of the canine’s location and situation, known as the “sensemaking gap.” In this paper, we propose KHAIT, a novel approach to close the sensemaking gap and enhance USAR effectiveness by integrating object detection-based Artificial Intelligence (AI) and Augmented Reality (AR). Equipped with AI-powered cameras, edge computing, and AR headsets, KHAIT enables precise and rapid object detection from a canine’s perspective, improving survivor localization. We evaluate this approach in a real-world USAR environment, demonstrating an average survival allocation time decrease of 22%, enhancing the speed and accuracy of operations.Published versio
Novel transonic nozzle for Ranque-Hilsch vortex tube
No full textThe process of the vortex flow formation in the Ranque-Hilsch vortex tube is studied. Starting from deficiencies of the existing vortex tubes, a novel type for the transonic nozzle is suggested and designed. The proposed nozzle is different from the existing classical ones by the presence of additional supersonic section placed after the blades. This section creates controlled conditions for acceleration of the vortex flow to supersonic speed. Analysis of the gas flow in the transonic nozzle using 3D RANS simulations showed that slightly improper selection of nozzle dimensions may lead to destabilization of the vortex flow and deterioration of the vortex tube performance. Simplified semi-one-dimensional model of swirling gas flow was derived and utilized for correction of the nozzle dimensions in order to stabilize the flow. Detailed validation of this model against full 3D RANS simulations demonstrated its applicability for preliminary engineering computations. It was demonstrated that application of the novel transonic nozzle extends the region in the energy separation chamber occupied by the supersonic vortex. This results in increase of both temperature separation effect and vortex tube energy efficiency. Main advantages and disadvantages of the novel transonic nozzle are summarized in the concluding section
Deceleration of the Cold Flow in the Vortex Tube
No full textEnhancement of the cold flow deceleration unit is considered in the paper to improve the energetic efficiency of the vortex tube. It was shown that the gradual expansion of the cross-section in the cold flow diffuser is inefficient for reducing the gas flow velocity in presence of its significant rotation. Installation of a blade grid at the entrance to the cold flow diffuser was suggested for interruption of the flow swirling. A notable reduction of the energy losses has been demonstrated improving the efficiency of the vortex tube. © Published under licence by IOP Publishing Ltd
Analysis of the local entropy generation in a double-circuit vortex tube
No full textThe method of entropy generation analysis has been implemented with the aim to investigate a double-circuit vortex tube thermodynamics. The value of the enthalpy growth rate was utilized as an indicator of the useful work done by the system. Post-processing of the numerical simulation results was carried out in order to determine the irreversible energy transformations within the computational domain. Particular attention was paid to comparative analysis of the standard k-ε and SAS-SST turbulence models from thermodynamic point of view. The near main nozzle area was mentioned as a source of irreversible energy losses because of active production of turbulence dissipation due to high local values of mean rate of strain tensor modulus. Existence of the negative work area, designated as a parasitic zone, was found in the center of the vortex tube in the close proximity to the additional flow inlet. Its formation can be explained by insufficient turbulent interactions between central and peripheral flows. It was shown that this area contributes significantly to the irreversibility and should be eliminated. The integral characteristics were developed on the ground of the three dimensional distribution of both entropy generation and enthalpy growth rate. The given characteristics are suggested to be used as objectives for the optimization studies. The vortex tube diameter, main nozzle geometry and the turbulization of the additional flow were suggested to be optimized
A comparison of the application of RSM and LES turbulence models in the numerical simulation of thermal and flow patterns in a double-circuit Ranque-Hilsch vortex tube
No full textThe present paper reports an investigation of a double-circuit Ranque-Hilsch vortex tube using a fully
three-dimensional numerical model of the turbulent compressible air flow. The main purpose of the
paper is to perform a detailed analysis of the thermal and flow patterns obtained with RSM-LRR and
LES turbulence models in order to understand which one is able to represent the Ranque-Hilsch energy
separation effect observed in a double-circuit vortex tube in the most effective way.
The LES turbulence model is found to represent the qualitative turbulence of the flow better than the
RSM-LRR model. The detailed analysis of turbulence characteristics estimated by LES model indicates that
turbulence has a significant impact on the energy separation phenomenon.
Both LES and RSM-LRR turbulence models are shown to have a weak accuracy in the prediction of the
integral characteristics of a double-circuit vortex tube.
An attempt was made to improve the results achieved with LES turbulence model by means of a grid
refinement and an increase of Smagorinsky constant value, but they were found to have a limited impact.
This leads to the conclusion that more advanced kinds of LES turbulence model should be investigated in
order to increase the accuracy of the simulation of a double-circuit vortex tube
Numerical investigation of a double-circuit Ranque-Hilsch vortex tube
No full textThe present paper reports a numerical investigation of a double-circuit RanqueeHilsch vortex tube.
Different turbulence models, namely keε, keε RNG, SAS-SST, RSM-LRR and LES, have been tested, in
order to understand which is the most suitable for the considered problem. The analysis is conducted on
a full three-dimensional model and the results show that LES turbulence model provides the best accuracy
of temperature separation prediction, standard keε and keε RNG have the worst accuracy,
whereas RSM-LRR and SAS-SST turbulence models take an intermediate position. On the contrary, LES
model is the most expensive in terms of computational time and resources. The results obtained with LES
highlight very high radial velocity values, which result in the enhancement of the turbulent heat and
mass transfer, which implies a more accurate prediction of the temperature separation effect. The present
study concludes that LES model provides the best accuracy for the simulation of a double-circuit
RanqueeHilsch vortex tube, but at the same time RSM-LRR and SAS-SST models are a good compromise
between computational efficiency and accuracy
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Sixty Yeats of Sovetskaia muzyka: A History of a Soviet Music Periodical
No full textThe journal Sovetskaia muzyka, established in 1933 as the press organ of the newly founded Composers’ Union, became the main musical periodical and official source of information on Soviet musical affairs for decades to come. It was expected not only to portray Soviet musical life, but to take an active part in creating a well-rounded cultured Soviet person. As the leading, and for some time the only music journal, Sovetskaia muzyka shaped Soviet musical life in ways both explicit and implicit. Evaluating scores and concerts as well as commenting on current ideological and aesthetic issues, the journal provided the recipe for successful musical composition, defined the rules of engagement and established the range of permissible actions on the musical front. The journal also took an active part in rewriting musical history along ideological lines, re-constructing composers’ images in order to market them for popular consumption. At the same time, Sovetskaia muzyka cannot be described as either an academic or professional periodical. From the beginning the orientation of the journal was multifaceted, combining ideological indoctrination, professional discussion, exchanges of information, and entertainment. Its audience was much broader than the academic community, consisting of both professional musicians and amateurs, and only a part of its output was scholarly. Despite its importance for contemporaries and present-day scholars alike, the journal has never been the subject of individual investigation. This dissertation seeks to fill this gap by examining its sixty-years history through study of archival documents, memoirs, and a complete collection of the journal. I examine Sovetskaia muzyka’s relationships with the Communist Party and governmental organs, creative unions, the professional community, readers, and other periodicals in order to assess its place in Soviet musical culture.
Ultimately, this dissertation contributes to our understanding of how media functions in an environment of strict ideological control. I demonstrate how, as a result of the gradual decreasing of governmental control and the development of musicology as a discipline, Sovetskaia muzyka distanced itself from participating in political discourse and instead concentrated on strictly professional, musicological projects. Over time, from a democratic, broadly oriented journal tightly connected to present-day politics, the journal changed into a highly specialized, academic periodical for the professional community. Even though such specialization limited its audience, Muzykal’naia akademiia (as Sovetskaia muzyka came to be known after 1992) is able to better cater to the needs of its readers
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