Experimental Investigation of Pressure Drop Through Ceramic Foams: An Empirical Model for Hot and Cold Flow

2011 ◽  
Vol 133 (11) ◽  
Author(s):  
S. Akbar Shakiba ◽  
R. Ebrahimi ◽  
M. Shams

Growing application and use of ceramic foams has intensified the necessity to determine a precise and inexpensive method for prediction of pressure drop through these materials. In this paper, a new experimental model is presented for pressure drop through ceramic foams. In order to measure pressure drop, a set up was made in which air flow rate and temperature varied. Effects of variation in temperature and flow velocity on the pressure drop were investigated through open-cell SiC and Al2O3 foams with different values of porosity and pore density. Results of this study revealed the leading role of parameters such as viscosity, porosity, density, velocity and mean hydraulic diameter of pores of foam. Since there are several parameters affecting the problem, dimensional analysis was adopted as a convenient approach. Euler number, porosity and two Reynolds numbers, one based on the pores’ diameter and the other one based on total bed length, have been shown to be important in the analysis. Finally, an empirical model is developed for the pressure drop which is based on dimensionless numbers.

1991 ◽  
Vol 18 (3) ◽  
pp. 333-362 ◽  
Author(s):  
MADELEINE LY-TIO-FANE

SUMMARY The recent extensive literature on exploration and the resulting scientific advances has failed to highlight the contribution of Austrian enterprise to the study of natural history. The leading role of Joseph II among the neutral powers which assumed the carrying trade of the belligerents during the American War of Independence, furthered the development of collections for the Schönbrunn Park and Gardens which had been set up on scientific principles by his parents. On the conclusion of peace, Joseph entrusted to Professor Maerter a world-encompassing mission in the course of which the Chief Gardener Franz Boos and his assistant Georg Scholl travelled to South Africa to collect plants and animals. Boos pursued the mission to Isle de France and Bourbon (Mauritius and Reunion), conveyed by the then unknown Nicolas Baudin. He worked at the Jardin du Roi, Pamplemousses, with Nicolas Cere, or at Palma with Joseph Francois Charpentier de Cossigny. The linkage of Austrian and French horticultural expertise created a situation fraught with opportunities which were to lead Baudin to the forefront of exploration and scientific research as the century closed in the upheaval of the Revolutionary Wars.


2001 ◽  
Vol 12 (1) ◽  
pp. 45-58 ◽  
Author(s):  
Ross W. Jamieson

As one of the most common artifact categories found on Spanish colonial sites, the wheel-made, tin-glazed pottery known as majolica is an important chronological and social indicator for archaeologists. Initially imported from Europe, several manufacturing centers for majolica were set up in the New World by the late sixteenth century. The study of colonial majolica in the Viceroyalty of Peru, which encompassed much of South America, has received less attention than ceramic production and trade in the colonial Caribbean and Mesoamerica. Prior to 1650 the Viceroyalty of Peru was supplied with majolica largely produced in the city of Panama Vieja, on the Pacific. Panama Vieja majolica has been recovered from throughout the Andes, as far south as Argentina. Majolica made in Panama Vieja provides an important chronological indicator of early colonial archaeological contexts in the region. The reproduction of Iberian-style majolica for use on elite tables was symbolically important to the imposition of Spanish rule, and thus Panamanian majolicas also provide an important indicator of elite status on Andean colonial sites.


2018 ◽  
Vol 5 (3) ◽  
pp. 40-52 ◽  
Author(s):  
S. P. Sviridova ◽  
O. V. Somonova ◽  
Sh. R. Kashiya ◽  
O. A. Obukhova ◽  
A. V. Sotnikov

In recent decades, significant progress has been made in understanding the mechanisms of platelet function and platelet hemostasis correction. Platelets are considered as the most important participants of both normal, and pathological thrombotic process characteristic of the most different diseases and states. In the present review pathophysiological mechanisms of platelet synthesis of various mediators with paracrine effects, which can influence the function of other cells, are consecrated. The physiology of platelets was considered in detail. The leading role of platelets in pathogenesis of the majority of diseases of cardiovascular system as modulators of inflammatory reactions of the immune response which are considered as the leading mechanism of development of atherosclerosis was shown. The ability of platelets to encode inflammatory proteins allowing them to influence adaptive immunity functions was discussed. The role of platelets as a key component of the innate immune system was presented, which is confirmed by the presence of Tolllike receptors (TLR) and glycoproteins, such as integrin αIIbβ3, glycoprotein Ib-IX and FcγRIIa, involved in interaction with bacterial cells. The pathogenesis of the formation of platelet-leukocyte aggregates due to the rapid reversible interaction of P-selectin (CD62P) on the platelet surface with ligand-1 glycoprotein P-selectin (PSGL-1) on the plasma of leukocytes and the mechanism of extracellular neutrophil traps (NETs), as well as the influence of platelets on the function of lymphocytes was presented. The role of platelets in cancer progression, metastasis and thrombosis is considered, and the interrelation of thrombosis and metastasis in malignant diseases was analyzed. The efficiency of the use of antithrombotic drugs in the prevention of thrombosis and, as a consequence, in the prevention of cardiovascular diseases and cancer was discussed.


1971 ◽  
Vol 46 (2) ◽  
pp. 365-383 ◽  
Author(s):  
T. J. Pedley ◽  
R. C. Schroter ◽  
M. F. Sudlow

The airways of the lung form a rapidly diverging system of branched tubes, and any discussion of their mechanics requires an understanding of the effects of the bifurcations on the flow downstream of them. Experiments have been carried out in models containing up to two generations of symmetrical junctions with fixed branching angle and diameter ratio, typical of the human lung. Flow visualization studies and velocity measurements in the daughter tubes of the first junction verified that secondary motions are set up, with peak axial velocities just outside the boundary layer on the inner wall of the junction, and that they decay slowly downstream. Axial velocity profiles were measured downstream of all junctions at a range of Reynolds numbers for which the flow was laminar.In each case these velocity profiles were used to estimate the viscous dissipation in the daughter tubes, so that the mean pressure drop associated with each junction and its daughter tubes could be inferred. The dependence of the dissipation on the dimensional variables is expected to be the same as in the early part of a simple entrance region, because most of the dissipation will occur in the boundary layers. This is supported by the experimental results, and the ratio Z of the dissipation in a tube downstream of a bifurcation to the dissipation which would exist in the same tube if Poiseuille flow were present is given by \[ Z = (C/4\surd{2})(Re\,d/L)^{\frac{1}{2}}, \] where L and d are the length and diameter of the tube, Re is the Reynolds number in it, and the constant C (equal to one for simple entry flow) is equal to 1·85 (the average value from our experiments). In general, C is expected to depend on the branching angles and diameter ratios of the junctions used. No experiments were performed in which the flow was turbulent, but it is argued that turbulence will not greatly affect the above results at Reynolds numbers less than and of the order of 10000. Many more experiments are required to consolidate this approach, but predictions based upon it agree well with the limited number of physiological experiments available.


1968 ◽  
Vol 90 (2) ◽  
pp. 443-449 ◽  
Author(s):  
R. A. Burton

Pressure and velocity data are reported for measurements in a large-scale experimental apparatus, designed to act as a model of a spiral-groove configuration operating at turbulent Reynolds numbers, and using air as a working fluid. The results predict that inertial effects at the steps in film thickness will exert a dominant influence on flows in machine elements made in geometric similitude to the model. Negative gage pressures were indicated in the thin-film regions, and these would be expected to lead at times to film breakup in elements using a liquid as the working fluid. Furthermore, negative stiffness under displacement of the journal was indicated for some operating conditions. The results, taken together, indicate the role of inertial effects, and dangerous operating conditions as to film breakup and loss of load support.


2019 ◽  
pp. 22-29
Author(s):  
Н. В. Фрадкіна

The purpose and tasks of the work are to analyze the contemporary Ukrainian mass culture in terms of its value and humanistic components, as well as the importance of cultural studies and Ukrainian studies in educational disciplines for the formation of a holistic worldview of modern youth.Analysis of research and publications. Scientists repeatedly turned to the problems of the role of spirituality in the formation of society and its culture. This problem is highlighted in the publications by O. Losev, V. Lytvyn, D. Likhachev, S. Avierintsev, M. Zakovych, I. Stepanenko and E. Kostyshyn.Experts see the main negative impact of mass culture on the quality approach, which determines mass culture through the market, because mass culture, from our point of view, is everything that is sold and used in mass demand.One of the most interesting studies on this issue was the work by the representatives of Frankfurt School M. Horkheimer and T. Adorno «Dialectics of Enlightenment» (1947), devoted to a detailed analysis of mass culture. Propaganda at all socio-cultural levels in the form is similar in both totalitarian and democratic countries. It is connected, according to the authors, with the direction of European enlightenment. The tendency to unify people is a manifestation of the influence of mass culture, from cinema to pop. Mass culture is a phenomenon whose existence is associated with commerce (accumulation in any form – this is the main feature of education), in general, the fact that it exists in this form is related to the direction of the history of civilization.Modern mass culture, with its externally attractive and easily assimilated ideas and symbols, appealing to the trends of modern fashion, becomes a standard of prestigious consumption, does not require intense reflection, allows you to relax, distract, not teach, but entertains, preaches hedonism as the main spiritual value. And as a consequence, there are socio-cultural risks: an active rejection of other people, which leads to the formation of indifference; cruelty as a character trait; increase of violent and mercenary crime; increase in the number of alcohol and drug addicts; anti-patriotism; indifference to the values of the family and as a result of social orphanhood and prostitution.Conclusions, perspectives of research. Thus, we can conclude that modern Ukrainian education is predominantly formed by the values of mass culture. Namely, according to the «Dialectic» by Horkheimer and Adorno, «semi-enlightenment becomes an objective spirit» of our modern society.It is concluded that only high-quality education can create the opposite of the onset of mass culture and the destruction of spirituality in our society. It is proved that only by realizing the importance of cultivating disciplines in the educational process and the spiritual upbringing of the nation, through educational reforms, humanitarian knowledge will gradually return to student audiences.Formation of youth occurs under the influence of social environment, culture, education and self-education. The optimal combination of these factors determines both the process of socialization itself and how successful it will be. In this context, one can see the leading role of education and upbringing. It turns out that the main task of modern education is to spread its influence on the development of spiritual culture of the individual, which eventually becomes a solid foundation for the formation of the individual. Such a subject requires both philosophical and humanitarian approaches in further integrated interdisciplinary research, since the availability of such research will provide the theoretical foundation for truly modern educational and personal development.


2020 ◽  
pp. 81-92
Author(s):  
Andrey Ivanovich Shutenko ◽  
◽  
Elena Nikolaevn Shutenko ◽  
Julia Petrovna Derevyanko ◽  
◽  
...  

The article is devoted to the problem of educational communications development as a sphere of implementation of modern information-communication technologies in the higher education system. The purpose of the article is to present the structure and functions of educational communications aimed at the development of personal potential and self-realization of students. Methodology. The study is based on the methodology of personal and communicative-informational approaches in education, psychological-pedagogical provisions on the structure of communication, the leading role of learning activity, didactic principles of building an educational-informational environment. In theoretical terms, the study is based on the idea of the indirect implementation of ICT in education through the development of educational communications. The developing structure of educational communications, including didactic, informational-gnostic, interactive, psychological, attractive-motivational, value-semantic components, is presented. The possibilities of developing personal potential in educational communications are considered. The author’s developmental model of ICT functions is presented, which includes clusters of actual and latent functions aimed at the formation of information-educational space for the development of students’ personal potential. In conclusion, a inference was made about the prospects of the indirect introduction of modern ICT as tools for the development and functioning of various educational communications. At the same time, it is essential that these communications perform psychological and pedagogical tasks and functions.


Author(s):  
Petar Halachev ◽  
Victoria Radeva ◽  
Albena Nikiforova ◽  
Miglena Veneva

This report is dedicated to the role of the web site as an important tool for presenting business on the Internet. Classification of site types has been made in terms of their application in the business and the types of structures in their construction. The Models of the Life Cycle for designing business websites are analyzed and are outlined their strengths and weaknesses. The stages in the design, construction, commissioning, and maintenance of a business website are distinguished and the activities and requirements of each stage are specified.


Author(s):  
Stephen Yablo

Aboutness has been studied from any number of angles. Brentano made it the defining feature of the mental. Phenomenologists try to pin down the aboutness features of particular mental states. Materialists sometimes claim to have grounded aboutness in natural regularities. Attempts have even been made, in library science and information theory, to operationalize the notion. However, it has played no real role in philosophical semantics, which is surprising. This is the first book to examine through a philosophical lens the role of subject matter in meaning. A long-standing tradition sees meaning as truth conditions, to be specified by listing the scenarios in which a sentence is true. Nothing is said about the principle of selection—about what in a scenario gets it onto the list. Subject matter is the missing link here. A sentence is true because of how matters stand where its subject matter is concerned. This book maintains that this is not just a feature of subject matter, but its essence. One indicates what a sentence is about by mapping out logical space according to its changing ways of being true or false. The notion of content that results—directed content—is brought to bear on a range of philosophical topics, including ontology, verisimilitude, knowledge, loose talk, assertive content, and philosophical methodology. The book represents a major advance in semantics and the philosophy of language.


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