scholarly journals Combined method for acoustic cavitation research

Doklady BGUIR ◽  
2020 ◽  
Vol 18 (4) ◽  
pp. 80-88
Author(s):  
A. V. Kotukhov ◽  
V. S. Gavrilyuk ◽  
V. S. Minchuk ◽  
N. V. Dezhkunov
Keyword(s):  
Low Frequency ◽  
Noise Spectrum ◽  
Ultrasonic Field ◽  
Point Of View ◽  
Gas Content ◽  
Variable Pressure ◽  
Preliminary Treatment ◽  
Cavitation Noise ◽  
Key Factor ◽  
Cavitation Region

At present, the field of applications of powerful ultrasound is expanding intensively, and the improvement of equipment and technological processes continues. With that, the key factor in the effect of ultrasonic vibrations on processes in liquids and liquid-like media is cavitation, i.e. the phenomenon of formation, pulsation and collapse of gas microbubbles under the influence of variable pressure. The widespread introduction of promising ultrasound technologies is largely constrained by the fact that the patterns of cavitation generation are not well understood, and the data known in the literature are contradictory and are characterized by low reproducibility. This paper describes an innovative method for studying ultrasonic cavitation. In order to increase the reproducibility of the results and the reliability of the conclusions about the correlation of various cavitation effects, it is proposed to register simultaneously the parameters characterizing these effects. An installation designed to implement this method has been developed and tested. The installation provides the ability to register the full output signal of the hydrophone, the intensity of the glow generated in the cavitation region - sound luminescence, the cavitation noise spectrum and its individual components. Technical characteristics of the installation allow you to adjust the rate of development of the cavitation region by varying the duration and period of the ultrasound pulses. It is possible to conduct experiments both in low-frequency (LF) and high-frequency (HF) fields as well as in interacting HF and LF ultrasonic fields. During the testing of the installation, the results were obtained that are of considerable interest from the point of view of refining the ideas about the mechanism for generating cavitation effects. It was found that preliminary treatment of the liquid in an ultrasonic field with the aim of its degassing for 15–20 min provides a significant increase in the reproducibility of measurements, especially for liquids with a high gas content. Based on a comparison of the time dependences of the signals of the cavitation sensor and the photomultiplier output, the characteristic stages of the development of the cavitation region are distinguished, which differ in the dynamics of the development of the cavitation region and in the composition of the cavitation noise spectra recorded.

Austrian Veto against European Union Membership Negotiations with Turkey

2020 ◽  
Vol 8 (1) ◽  
pp. 103-122
Author(s):  
Ewa Kaczan-Winiarska
Keyword(s):  
European Union ◽  
European Commission ◽  
Security Policy ◽  
Negotiation Process ◽  
Point Of View ◽  
The European Union ◽  
Strategic Partner ◽  
Key Factor ◽  
European Standards ◽  
The Eu

The Austrian government is extremely sceptical about the accession negotiations which are conducted by the European Commission on behalf of the European Union with Turkey and calls for the negotiation process to end. Serious reservations of Vienna have been raised by the current political situation in Turkey under the rule of President Recep Tayyip Erdogan, as well as by the standards of democracy in Turkey, which differ greatly from European standards. Serious deficiencies in rule of law, freedom of speech and independence of the judiciary, confirmed in the latest European Commission report on Turkey, do not justify, from Vienna’s point of view, the continuation of talks with Ankara on EU membership. In fact, Austria’s scepticism about the European perspective for Turkey has a longer tradition. This was marked previously in 2005 when the accession negotiations began. Until now, Austria’s position has not had enough clout within the European arena. Pragmatic cooperation with Turkey as a strategic partner of the EU, both in the context of the migration crisis and security policy, proved to be a key factor. The question is whether Austria, which took over the EU presidency from 1.7.2018, will be able to more strongly accentuate its reservations about Turkey and even build an alliance of Member States strong enough to block Turkey’s accession process.

scholarly journals Determinants of Corporate Anti-Corruption Disclosure: The Case of the Emerging Economics

2021 ◽  
Vol 13 (6) ◽  
pp. 3462
Author(s):  
Maider Aldaz Odriozola ◽  
Igor Álvarez Etxeberria
Keyword(s):  
Empirical Studies ◽  
Geographical Area ◽  
Control Variable ◽  
Emerging Countries ◽  
Point Of View ◽  
Press Freedom ◽  
Negative Effects ◽  
Key Factor ◽  
Using Data ◽  
Positive Effect

Corruption is a key factor that affects countries’ development, with emerging countries being a geographical area in which it tends to generate greater negative effects. However, few empirical studies analyze corruption from the point of view of disclosure by companies in this relevant geographical area. Based on a regression analysis using data from the 96 large companies from 15 emerging countries included in the 2016 International Transparency Report, this paper seeks to understand what determinants affect such disclosure. In that context, this paper provides empirical evidence to understand the factors that influence reporting on anti-corruption mechanisms in an area of high economic importance that has been little studied to date, pointing to the positive effect of press freedom in a country where the company is located and with the industry being the unique control variable that strengthens this relationship.

scholarly journals Carotid and aortic baroreflexes of the rat: II. Open-loop frequency response and the blood pressure spectrum

2000 ◽  
Vol 279 (5) ◽  
pp. R1922-R1933 ◽  
Author(s):  
Barry R. Dworkin ◽  
Xiaorui Tang ◽  
Alan J. Snyder ◽  
Susan Dworkin
Keyword(s):  
Blood Pressure ◽  
Venous Pressure ◽  
Low Frequency ◽  
Noise Spectrum ◽  
Open Loop ◽  
Step Response ◽  
Algebraic Solution ◽  
Noise Power ◽  
Vascular Conductance ◽  
Aortic Depressor Nerve

To determine the relationship between blood pressure (BP) variability and the open-loop frequency domain transfer function (TF) of the baroreflexes, we measured the pre- and postsinoaortic denervation (SAD) spectra and the effects of periodic and step inputs to the aortic depressor nerve and isolated carotid sinus of central nervous system-intact, neuromuscular-blocked (NMB) rats. Similar to previous results in freely moving rats, SAD greatly increased very low frequency (VLF) (0.01–0.2 Hz) systolic blood pressure (SBP) noise power. Step response-frequency measurements for SBP; interbeat interval (IBI); venous pressure; mesenteric, femoral, and skin blood flow; and direct modulation analyses of SBP showed that only VLF variability could be substantially attenuated by an intact baroreflex. The −3-dB frequency for SBP is 0.035–0.056 Hz; femoral vascular conductance is similar to SBP, but mesenteric vascular conductance has a reliably lower and IBI has a reliably higher −3-dB point. The overall open-loop transportation lag, of which ≤0.1 s is neural, is ≈1.07 s. Constrained algebraic solution, over a range of frequencies, of the pre- and postSAD endogenous noise spectra and the independently determined relative frequency and absolute lag measurements was used to calculate the absolute gain for the open-loop TF. The average gain at 0.02 Hz, the frequency of maximum sensitivity, was 1.47 (95% confidence interval = ±0.48), which agrees well with estimates for the dog reversible sinus. We found that, in the NMB rat, the effects of SAD on the BP noise spectrum were accounted for by the open-loop properties of the baroreflex.

scholarly journals Il castello Colonna di Arnara: dal restauro del monumento alla valorizzazione del borgo antico e del suo territorio

X ◽  
2020 ◽  
Author(s):  
Alessandra Cattaneo ◽  
Laura Baratin
Keyword(s):  
Cultural Heritage ◽  
Social Innovation ◽  
Economic Value ◽  
Research Work ◽  
Exceptional Case ◽  
Point Of View ◽  
Medieval Architecture ◽  
Important Place ◽  
Key Factor ◽  
Private And Public

The castle Colonna of Arnara: from the restoration of the monument to the enhancement of the ancient village and its territoryThe castle of Arnara, is located in Ciociaria in southern Lazio, in what was once the feud of the Conti of Ceccano. For the territory it is the most important monumental complex of medieval architecture. In fact, despite its small size, it is one of the few examples of fortified architecture still original in its essential lines. This castle represents an exceptional case of sedimentation and stratification, which even today, from its reading, allows us to reconstruct both its historical events and those related to the urban development of the adjacent historic village. Moreover it can be considered of priority importance also from the urbanistic point of view because it represents the first historical nucleus of Arnara. Unfortunately, today, the castle is in a bad state of conservation. With the passing of time its conditions have become more and more aggravated also because of the complex events linked to the various passages of property, of private and public nature, which have strongly influenced the management of the monument. The study of the castle of Arnara is part of the national and international debate that considers participation a key factor for the sustainable enhancement of the cultural heritage, because it promotes greater awareness of its social and economic value. The objective of the research work is to develop, taking the castle as a case study, a new approach that sees cultural heritage (tangible and intangible) as an irreplaceable heritage of knowledge and as a precious resource for economic growth, employment and social cohesion; therefore a cultural heritage seen as a driving force. In the specific case of Colonna Castle, attention has been focused on the importance of being able to activate virtuous circles around this very important place of culture, enhancing its role as a centre of knowledge and incubator of creativity and social innovation.

Paper 14: Acoustic Detection of Cavitation

1966 ◽  
Vol 181 (1) ◽  
pp. 1-8 ◽  
Author(s):  
I. S. Pearsall
Keyword(s):  
High Frequency ◽  
Critical Frequency ◽  
Low Frequency ◽  
Francis Turbine ◽  
Frequency Noise ◽  
Performance Tests ◽  
Acoustic Detection ◽  
Cavitation Noise ◽  
Further Development ◽  
Onset Of Cavitation

The onset of cavitation in a hydraulic machine can be determined visually and its effect on performance by performance tests. It would be convenient to have an alternative method that required neither transparent sections nor expensive tests. Initial tests have been made measuring noise over a frequency range of 20 c/s-20 kc/s in one-third octave bands, on a number of pumps and turbines. An accelerometer attached to the casing was used. The tests indicated that, generally, the onset of cavitation was accompanied by a rise in the high-frequency noise, whilst the low-frequency noise increased as the cavitation developed. A maximum of cavitation noise was reached before the efficiency and load fell off. In some cases difficulty was experienced because blade cavitation was drowned by noise caused by other cavitation, such as the vortex in a Francis turbine. It also appears that the noise following the onset of cavitation is at the frequency which is used as a critical frequency in accelerated erosion tests. Further development of techniques is required, but the initial tests are encouraging.

Modelling mutual interactions between soil structure and soil biological communities.

2021 ◽  
Author(s):  
Tancredi Caruso
Keyword(s):  
Habitat Structure ◽  
Soil Structure ◽  
Pore Space ◽  
Point Of View ◽  
Species Number ◽  
Ecological Communities ◽  
Soil Organisms ◽  
Biological Communities ◽  
Key Factor ◽  
Complex Habitat

<p>Habitat structure is a key factor controlling the structure of ecological communities. For example, complex habitat structure may increase species number, minimise competition and facilitate the retention of nutrients. Alteration and disturbance of habitat structure may thus negatively affect biodiversity. Soil is an extremely complex and highly structured environmental matrix. Soil structure, defined as a distribution of aggregate/pore space of different sizes, can thus be a major control of soil biological communities, which are for example highly structured in their size distribution. Soil organisms, however, also affect and modify soil structure, and for many organisms the soil habitat structure is thus not just a condition to which they have to adapt but, rather, an environmental feature they also affect. In this talk, I discuss all these aspects from a community ecology point of view and with an emphasis on statistical and dynamical models that soil ecologists are trying to develop to describe and predict the mutual interactions between soil structure and biological communities. I will focus on the different rates at which soil structure affects soil organisms and vice versa, to emphasise that the temporal scales at which we have to measure the two parts of this mutual feedback (i.e. soil structure -> biota vs. biota -> soil structure) are very different, and also variable in space and time. </p>

Embassy of the Russian Empire in Berlin on the Socialist Movement in Germany in 1890–1898

2021 ◽  
pp. 179
Author(s):  
Anna Matveeva
Keyword(s):  
Domestic Politics ◽  
Russian Empire ◽  
Point Of View ◽  
Democratic Movement ◽  
Social Democratic ◽  
The Social ◽  
Key Factor ◽  
The Government ◽  
Socialist Movement ◽  
The Russian Empire

The study focuses on assessing the representativeness and relevance of diplomatic documents for the study of key aspects of German domestic politics. Three issues are central to the analysis of the documents from the Archive of the Foreign Policy of the Russian Empire: the completeness of the indicated sources for understanding the factors of the German Empire’s inner policy; the assessment of the subjectivity of the author of diplomatic dispatches, i.e. how much the ambassador's personality determined the content of the dispatches that he sent to the ministry; the relevance of highlighting key issues of internal life in Germany from the point of view of Russian diplomats. Among constantly present in the messages, the most important was the problem of the socialist movement and the Social-Democratic Party’s activities. The socialists were mentioned for significant reasons: the repeal of the Law against the Socialists, the Berlin Conference on the Labor Protection (1890); elections to the Reichstag (1893, 1898); the Reichstag votes on issues important for Russia. The measures of counteraction to the socialists, discussed by the emperor and the government, also aroused interest. The study of archival documents (1890–1898) allows the author to draw the following conclusions. The dispatches adequately reflect the main trends in the socialist movement and the tactics of the SPD, therefore they can be used to study many internal problems faced by Germany in the course of its political evolution. The development of the social-democratic movement was rightly interpreted by Russian diplomats as one of the fundamental reasons for the internal instability of the German state during the reign of Wilhelm II. At the same time, the conclusion drawn by the diplomats can be primarily explained by the Russian imperial regime and its substantial characteristics, rather than the political realities within Germany itself. They considered parliamentarism, limiting the monarch actions (the state interests), to be the main reason for the high popularity and the broadest electoral support of the SPD. The key factor preventing the monarch from defeating the “coup parties” was defined as the activities of liberal political parties, which demanded the unconditional observance of the freedoms prescribed in the Сonstitution of 1871, as well as the prevention of the introduction of Exceptional Laws and other measures of an extraordinary nature.

LOFAR4SW – Space Weather Science and Operations with LOFAR

2021 ◽  
Author(s):  
Hanna Rothkaehl ◽  
Barbara Matyjasiak ◽  
Carla Baldovin ◽  
Mario Bisi ◽  
David Barnes ◽  
...  
Keyword(s):  
The Netherlands ◽  
Radio Telescope ◽  
Space Weather ◽  
Low Frequency ◽  
Point Of View ◽  
Current Status ◽  
Civic Society ◽  
Horizon 2020 ◽  
Final Design ◽  
Areas Of Interest

<p>Space Weather (SW) research is a very important topic from the scientific, operational and civic society point of view. Knowledge of interactions in the Sun-Earth system, the physics behind observed SW phenomena, and its direct impact on modern technologies were and will be key areas of interest.  The LOFAR for Space Weather (LOFAR4SW) project aim is to prepare a novel tool which can bring new capabilities into this domain. The project is realised in the frame of a Horizon 2020 INFRADEV call.  The base for the project is the Low Frequency Array (LOFAR) - the worlds largest low frequency radio telescope, with a dense core near Exloo in The Netherlands and many stations distributed both in the Netherlands and Europe wide with baselines up to 2000 km.  The final design of LOFAR4SW will provide a full conceptual and technical description of the LOFAR upgrade, to enable simultaneous operation as a radio telescope for astronomical research as well as an infrastructure working for Space Weather studies.  In this work we present the current status of the project, including examples of the capabilities of LOFAR4SW and the project timeline as we plan for the Critical Design Review later in 2021.</p>

Covert Underwater Acoustic Communication System Using Parametric Array

2019 ◽  
Vol 53 (1) ◽  
pp. 20-26 ◽  
Author(s):  
Anbang Zhao ◽  
Yue Cheng ◽  
Tiansi An ◽  
Juan Hui
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Low Frequency ◽  
Nonlinear Behavior ◽  
Beam Width ◽  
Point Of View ◽  
Underwater Acoustic Communication ◽  
Water Tank ◽  
Narrow Beam ◽  
Underwater Acoustic ◽  
Parametric Array

AbstractA novel and efficient covert underwater acoustic (UWA) communication scheme using an acoustic parametric array and orthogonal frequency division multiplexing (OFDM) system is presented. The proposed system is robust and can easily be implemented in the ocean environment. The system is also very useful in military applications where the secrecy of transmission signal and location of the transmitter are extremely important. The paper exploits the difference frequency generated by the acoustic parametric array due to the nonlinear behavior of an underwater medium. Besides the lightness and compactness, the parametric array also possesses the advantage of being low-frequency, broadband, highly directive, and narrow beam with no side lobes. The narrow beam width also helps to secure the data from a spatial point of view. Experiments have been performed in a water tank, and the results are presented to show the effectiveness of the proposed scheme.

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