scholarly journals Anisotropy of turbulent flow behind an asymmetric airfoil

2021 ◽  
Vol 3 (12) ◽  
Author(s):  
Vitalii Yanovych ◽  
Daniel Duda ◽  
Vaclav Uruba ◽  
Pavel Antoš
Keyword(s):  
Turbulent Flow ◽  
Experimental Studies ◽  
Structural Function ◽  
Stress Components ◽  
Degree Of Anisotropy ◽  
Turbulence Length ◽  
Low Degrees ◽  
High Degree ◽  
Flow Anisotropy ◽  
Insight Into

AbstractFeature of turbulent flow anisotropy behavior behind an asymmetric NACA 64-618 airfoil investigated in this paper. Experimental studies were performed using a hot-wire anemometery with X-probe at the chord-based Reynolds number $$1.7 \times 10^5$$ 1.7 × 10 5 . The average ensemble velocity and Reynolds stress components are used to determine the wake topology and anisotropy of turbulence. The obtained data allowed to identify the outside wake region, which is characterized by low instability and a high degree of anisotropy of the turbulent flow. This tendency is observed at different angles incident. Further, to gain better insight into the physics of this phenomenon the structure of turbulence have been evaluated. Integral turbulence length and time scales were estimated by the area of the autocorrelation function of velocity fluctuations. Then, using the second-order structural function, we obtained the dissipation characteristics of the flow. In addition, the features of the energy spectrum in the region with high and low degrees of turbulence anisotropy were analyzed.

Beyond committing and presupposing in Yurakaré conversations: Investigating the interactional functions of epistemic markers through their sequential distributions

2020 ◽  
Vol 54 (2) ◽  
pp. 371-404 ◽  
Author(s):  
Sonja Gipper
Keyword(s):  
The Other ◽  
Epistemic State ◽  
Low Degree ◽  
Interactional Functions ◽  
Low Degrees ◽  
High Degree ◽  
Insight Into ◽  
Gaining Insight

AbstractThis paper outlines a method for studying the sequential distributions of epistemic markers with the purpose of gaining insight into their interactional functions. The method is exemplified with a case study of two epistemic markers of Yurakaré (isolate, Bolivia), =la “commitment” and =se “presupposition”. The investigation reveals that the two markers show different distributions across initial and responsive utterances. Moreover, each marker functions differently when used in initial utterances and responses. It is argued that these distributions show that the interactional functions of the two markers go beyond the marking of commitment and presupposition, and that they contrast in terms of two scales, one capturing the poles of “highly initiating” and “highly responsive”, the other concerning high vs. low degrees of “thematic agency”. While the commitment marker =la is associated with the responsivity pole and with a low degree of thematic agency, the presupposition marker =se shows a tendency toward the initiating pole and toward a high degree of thematic agency. These findings then support the view that epistemic markers are employed to co-construct epistemic perspectives in interaction rather than to make explicit some internal epistemic state held by the speaker.

A possibility of using nickel concentrate, obtained as a result of hydrometallurgical enrichment of manganese-containing raw materials, at steel alloying

2020 ◽  
Vol 76 (7) ◽  
pp. 709-715
Author(s):  
O. Yu. Kichigina
Keyword(s):  
Raw Materials ◽  
Experimental Studies ◽  
Selective Extraction ◽  
Technological Parameters ◽  
Nickel Iron ◽  
Nickel Recovery ◽  
Nickel Concentrate ◽  
Steel Alloying ◽  
High Degree ◽  
Comprehensive Processing

At production of stainless steel expensive alloying elements, containing nickel, are used. To decrease the steel cost, substitution of nickel during steel alloying process by its oxides is an actual task. Results of analysis of thermodynamic and experimental studies of nickel reducing from its oxide presented, as well as methods of nickel oxide obtaining at manganese bearing complex raw materials enrichment and practice of its application during steel alloying. Technology of comprehensive processing of complex manganese-containing raw materials considered, including leaching and selective extraction out of the solution valuable components: manganese, nickel, iron, cobalt and copper. Based on theoretical and experiment studies, a possibility of substitution of metal nickel by concentrates, obtained as a result of hydrometallurgical enrichment, was confirmed. Optimal technological parameters, ensuring high degree of nickel recovery out of the initial raw materials were determined. It was established, that for direct steel alloying it is reasonable to add into the charge pellets, consisting of nickel concentrate and coke fines, that enables to reach the through nickel recovery at a level of 90%. The proposed method of alloying steel by nickel gives a possibility to decrease considerably steel cost at the expense of application of nickel concentrate, obtained out of tails of hydrometallurgical enrichment of manganese-bearing raw materials, which is much cheaper comparing with the metal nickel.

scholarly journals Shedding light on the nature of the catalytically active species in photocatalytic reactions using Bi2O3 semiconductor

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Paola Riente ◽  
Mauro Fianchini ◽  
Patricia Llanes ◽  
Miquel A. Pericàs ◽  
Timothy Noël
Keyword(s):  
Experimental Studies ◽  
Heterogeneous Photocatalysis ◽  
Active Species ◽  
Organic Transformations ◽  
Alkyl Bromides ◽  
Catalytically Active ◽  
Visible Light Driven ◽  
Photocatalytic Reactions ◽  
Insight Into ◽  
Photocatalytic Processes

AbstractThe importance of discovering the true catalytically active species involved in photocatalytic systems allows for a better and more general understanding of photocatalytic processes, which eventually may help to improve their efficiency. Bi2O3 has been used as a heterogeneous photocatalyst and is able to catalyze several synthetically important visible-light-driven organic transformations. However, insight into the operative catalyst involved in the photocatalytic process is hitherto missing. Herein, we show through a combination of theoretical and experimental studies that the perceived heterogeneous photocatalysis with Bi2O3 in the presence of alkyl bromides involves a homogeneous BinBrm species, which is the true photocatalyst operative in the reaction. Hence, Bi2O3 can be regarded as a precatalyst which is slowly converted in an active homogeneous photocatalyst. This work can also be of importance to mechanistic studies involving other semiconductor-based photocatalytic processes.

In-Plane Asymmetries on the Ge(111)-c(2×8) Surface Mapped with the Scanning Tunneling Microscope

1992 ◽  
Vol 295 ◽  
Author(s):  
P. Molinàs-Mata ◽  
J. Zegenhagen ◽  
M. Böhringer ◽  
N. Takeuchi ◽  
A. Selloni
Keyword(s):  
Local Density ◽  
Experimental Studies ◽  
Surface States ◽  
Small Sample ◽  
Constant Current ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Low Energy Electron ◽  
Tunneling Currents ◽  
Insight Into

AbstractWe report on new experimental studies of the Ge(111)-c(2×8) reconstruction performed with low-energy electron diffraction. (LEED) and scanning tunneling microscopy (STM). Weak quarter-order reflections are present in the c(2 × 8) LEED pattern in agreement with previous observations and results of ab initio calculations. In order to gain insight into the predicted splitting of dangling bond states, we compare constant current topographs (CCT's) performed at high-tunneling currents (40.nA) with first-principles calculations of the local density of states (LDOS) 1Å above the surface adatoms and obtain good qualitative agreement. We finally discuss to what extent the STM CCT's at high tunneling currents (small sample-tip distances (STD)) are sensitive to surface states outside the Г point.

Embracing multidimensionality in phonological analysis

2021 ◽  
Vol 38 (1) ◽  
pp. 101-139
Author(s):  
Abigail C. Cohn ◽  
Margaret E. L. Renwick
Keyword(s):  
Native Speaker ◽  
Experimental Studies ◽  
Spoken Language ◽  
Iterative Approach ◽  
Full Spectrum ◽  
Multiple Factors ◽  
Multiple Data ◽  
Language Data ◽  
Corpus Data ◽  
Insight Into

Abstract We pursue the idea, implicit in much current phonological research, that understanding the multiple factors that shape speech production and perception is within the purview of phonology. In particular, increased access to naturalistic data has highlighted the multidimensional reality of variation in spoken language. At the same time, longstanding methods of doing phonology – including impressionistic analysis, and laboratory and experimental studies – remain crucial to understanding native speaker competence and grammar. We advocate for an expanded methodological toolbox in phonological analysis, using an iterative approach that crucially includes naturalistic corpus data. Integrating across multiple data sources offers fuller insight into the nature of the phonological system and native speaker-hearer ability. Several case studies highlight findings gained through linked, iterative studies, showing the importance of naturalistic data for a richer understanding of phonological phenomena, and leading us to reflect on desiderata for corpora to reveal speaker-specific patterns in fine phonetic detail and variability, which we argue are part of a speaker-hearer’s phonological competence. Phonological analysis that embraces the full spectrum of variation in spoken language data (from categorical to gradient, and systematic to sporadic) contributes to a deeper understanding of phonology in this richer sense.

Theoretical and Experimental Studies of Sulfur and Boron Distribution between the Slag of the CaO-SiO2-B2O3-MgO-Al2O3 System and the Metal

2021 ◽  
Vol 410 ◽  
pp. 287-292
Author(s):  
Anatolij A. Babenko ◽  
Leonid A. Smirnov ◽  
Alena G. Upolovnikova
Keyword(s):  
Distribution Coefficient ◽  
Thermodynamic Modeling ◽  
Experimental Studies ◽  
Oxide System ◽  
Slag Basicity ◽  
Interphase Distribution ◽  
Desulfurization Process ◽  
Simplex Lattice ◽  
High Degree ◽  
Effect Of The Composition

The equilibrium interfacial distribution of sulfur and boron was estimated using the HSC 6.1 Chemistry software package (Outokumpu) and the simplex-lattice planning method. Adequate mathematical models have been constructed in the form of III degree polynomial, which describe the effect of the composition of the studied oxide system on the equilibrium distribution of sulfur and boron between the slag and the metal. Generalization of the results of experimental studies and thermodynamic modeling made it possible to obtain new data on the influence of the basicity and content of B2O3 in the slag of the CaO-SiO2-B2O3-MgO-Al2O3 system on the interphase distribution of sulfur and boron. It was found that in the range of boron oxide concentration of 1.0-10%, an increase in slag basicity from 2 to 5 at 1600°C leads to an increase in the sulfur distribution coefficient from 1 to 20 and, as a consequence, a decrease in the sulfur content in the metal from 0.02 to 0.0014 %, i.e. an increase in slag basicity favorably affects the development of the metal desulfurization process. An increase in the B2O3 content from 2.0 to 10.0% in slags formed in the region of moderate basicity, not exceeding 2-3, is accompanied at 1600°C by a decrease in the boron interphase distribution coefficient from 450 to 150 and an increase in the boron concentration in the metal from 0.006 to 0.021 %, which indicates the progress of boron reduction from slag to metal. The shift of the formed slags to the area of ​​increased basicity up to 5.0 shows a high degree of boron reduction from slag to metal. The results of the laboratory experiment confirmed the results of thermodynamic modeling.

Main approaches to treatment of hypoxia in acute respiratory distress syndrome, bacterial and viral pneumonia (part III)

2021 ◽  
pp. 38-55
Author(s):  
A. V. Vlasenko ◽  
E. A. Evdokimov ◽  
E. P. Rodionov
Keyword(s):  
Respiratory Failure ◽  
Distress Syndrome ◽  
Experimental Studies ◽  
Viral Pneumonia ◽  
Medical Technologies ◽  
Clinical Observations ◽  
Wide Range ◽  
Prevention And Treatment ◽  
High Degree

The paper summarizes data on modern approaches to the diagnosis, prevention and treatment of severe acute parenchymal respiratory failure of various origins, including ARDS due to bacterial viral pneumonia. The work is based on the data of modern well-organized studies, analysis of international clinical guidelines with a high degree of evidence, as well as the results of our own long-term experimental studies and clinical observations of the treatment of patients with ARDS of various origins, including viral pneumonia of 2009, 2016, 2020. Scientifically grounded algorithms for prevention, differential diagnosis and personalized therapy of severe acute respiratory failure using innovative medical technologies and a wide range of respiratory and adjuvant treatment methods have been formulated. The authors tried to adapt as much as possible the existing current recommendations for the daily clinical practice of anesthesiologists and resuscitators.

Modeling Cyclic Variability in Spark-Assisted HCCI

2008 ◽  
Vol 130 (5) ◽  
Author(s):  
C. Stuart Daw ◽  
K. Dean Edwards ◽  
Robert M. Wagner ◽  
Johney B. Green
Keyword(s):  
Control Strategies ◽  
Experimental Studies ◽  
Mode Switching ◽  
Load Range ◽  
Gasoline Engines ◽  
Cyclic Variability ◽  
Hcci Combustion ◽  
Quantitative Understanding ◽  
Low Dimensional ◽  
High Degree

Spark assist appears to offer considerable potential for increasing the speed and load range over which homogeneous charge compression ignition (HCCI) is possible in gasoline engines. Numerous experimental studies of the transition between conventional spark-ignited (SI) propagating-flame combustion and HCCI combustion in gasoline engines with spark assist have demonstrated a high degree of deterministic coupling between successive combustion events. Analysis of this coupling suggests that the transition between SI and HCCI can be described as a sequence of bifurcations in a low-dimensional dynamic map. In this paper, we describe methods for utilizing the deterministic relationship between cycles to extract global kinetic rate parameters that can be used to discriminate multiple distinct combustion states and develop a more quantitative understanding of the SI-HCCI transition. We demonstrate the application of these methods for indolene-containing fuels and point out an apparent HCCI mode switching not previously reported. Our results have specific implications for developing dynamic combustion models and feedback control strategies that utilize spark assist to expand the operating range of HCCI combustion.

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