Numerical simulation of heat and mass transfer processes in large-scale fluidized bed complex structure apparatus as an example of the reactor of isoparaffins dehydrogenation

In the chemical industry are widely used fluidized bed apparatus. The advantage of them is the high speed of heat and mass transfer between components of the reaction, which are in different aggregation states. Studies of large-scale apparatus are hindered big sizes and plurality of structural elements. Often such apparatus operate at high temperatures (500-900 C), which further complicates the study. In this paper we consider a fluidized bed reactor block intended for the dehydrogenation of isobutane. In numerical simulation of fluidization was extended Eulerian-Eulerian approach. Differential equations that describe the hydrodynamic and thermal processes in the field of computational model of the reactor were solved in ANSYS Fluent CFD for axisymmetric unsteady flow scheme. At full simulation of the unit of the reactor in differential equations for the mass fraction of components of the gas mixture is necessary to consider changes related with chemical reactions. In the model used for this purpose it is necessary to add terms to the equations of mass transfer and absorption of heat depending primarily on the gas temperature and catalyst concentration. In this paper we'll restrict considering the minimum number of components of the reaction (raw materials - isobutane, product - isobutylene). For a given chemical reaction is written User Defined Functions (UDF). The influence of the ambient gas, the catalyst and the time step on the progress of chemical reaction in the volume element is studied. Numerical calculations were carried out, due to them circulating streams in the apparatus, the temperature field distribution of the catalyst and the conversion of the feeding gas-raw were analyzed

CFD modeling a fluidized bed large scale reactor with various internal elements near the heated particles feeder

© 2018 Institution of Chemical Engineers A numerical study of the fluidized bed industrial reactor in the presence of various internal elements is carried out by CFD methods A simple reactor heating efficiency function of chemical reaction with heat absorption is considered. The main emphasis is placed on the circulation flows of the catalyst particles and heating of the reactor. The analysis of the impact of various design elements on the heating efficiency of the reactor is carried out. Particular attention is paid to the possibility of baffles applying, which allows redirecting the flow. This effect may have an especially important value when the rapid heating of the reactor is required for temperature dependent reactions. The influence of heated catalyst feeder design on the efficiency of whole reactor heating is educed. The influence of the fractional composition of the catalyst, namely the presence of fine particles, on the reactor heating efficiency for different reactor design features is also studied. The results are carried out for a specific reactor example, but contribute to the overall branch of fluidized bed engineering

On Nonperturbative Calculations in Quantum Electrodynamics

A new approach to nonperturbative calculations in quantum electrodynamics is proposed. The approach is based on a regular iteration scheme for solution of Schwinger-Dyson equations for generating functional of Green functions. The approach allows one to take into account the gauge invariance conditions (Ward identities) and to perform the renormalization program. The iteration scheme can be realized in two versions. The first one ("perturbative vacuum") corresponds to chain summation in the diagram language. In this version in four-dimensional theory the non-physical singularity (Landau pole) arises which leads to the triviality of the renormalized theory. The second version ("nonperturbative vacuum") corresponds to ladder summation and permits one to make non-perturbative calculations of physical quantities in spite of the triviality problem. For chiral-symmetrical leading approximation two terms of the expansion of the first-step vertex function over photon momentum are calculated. A formula for anomalous magnetic moment is obtained. A problem of dynamical chiral symmetry breaking (DCSB) is considered, the calculations are performed for renormalized theory in Minkowsky space. In the strong coupling region DCSB-solutions arise. For the renormalized theory a DCSB-solution is also possible in the weak coupling region but with a subsidiary condition on the value of $\alpha$.Comment: 31 pages, Plain LaTex, no figures. Journal version: some discussion and refs. are adde

USp(2k) Matrix Model: Nonperturbative Approach to Orientifolds

We discuss theoretical implications of the large k USp(2k) matrix model in zero dimension. The model appears as the matrix model of type IIB superstrings on a large $T^{6}/Z^{2}$ orientifold via the matrix twist operation. In the small volume limit, the model behaves four dimensional and its T dual is six-dimensional worldvolume theory of type I superstrings in ten spacetime dimensions. Several theoretical considerations including the analysis on planar diagrams, the commutativity of the projectors with supersymmetries and the cancellation of gauge anomalies are given, providing us with the rationales for the choice of the Lie algebra and the field content. A few classical solutions are constructed which correspond to Dirichlet p-branes and some fluctuations are evaluated. The particular scaling limit with matrix T duality transformation is discussed which derives the F theory compactification on an elliptic fibered K3.Comment: LaTeX, 29 pages, 3 figures. PostScript problems are fixe

On the roots of the Poincare structure of asymptotically flat spacetimes

The analysis of vacuum general relativity by R. Beig and N. O Murchadha (Ann. Phys. vol 174, 463 (1987)) is extended in numerous ways. The weakest possible power-type fall-off conditions for the energy-momentum tensor, the metric, the extrinsic curvature, the lapse and the shift are determined, which, together with the parity conditions, are preserved by the energy-momentum conservation and the evolution equations. The algebra of the asymptotic Killing vectors, defined with respect to a foliation of the spacetime, is shown to be the Lorentz Lie algebra for slow fall-off of the metric, but it is the Poincare algebra for 1/r or faster fall-off. It is shown that the applicability of the symplectic formalism already requires the 1/r (or faster) fall-off of the metric. The connection between the Poisson algebra of the Beig-O Murchadha Hamiltonians and the asymptotic Killing vectors is clarified. The value H[K^a] of their Hamiltonian is shown to be conserved in time if K^a is an asymptotic Killing vector defined with respect to the constant time slices. The angular momentum and centre-of-mass, defined by the value of H[K^a] for asymptotic rotation-boost Killing vectors K^a, are shown to be finite only for 1/r or faster fall-off of the metric. Our center-of-mass expression is the difference of that of Beig and O Murchadha and the spatial momentum times the coordinate time. The spatial angular momentum and this centre-of-mass form a Lorentz tensor, which transforms in the correct way under Poincare transformations.Comment: 34 pages, plain TEX, misleading notations changed, discussion improved and corrected, appearing in Class. Quantum Gra

Probability of relativistic electron trapping by parallel and oblique whistler-mode waves in Earth's radiation belts

International audienceWe investigate electron trapping by high-amplitude whistler-mode waves propagating at small as well as large angles relative to geomagnetic field lines. The inhomogeneity of the background magnetic field can result in an effective acceleration of trapped particles. Here, we derive useful analytical expressions for the probability of electron trapping by both parallel and oblique waves, paving the way for a full analytical description of trapping effects on the particle distribution. Numerical integrations of particle trajectories allow to demonstrate the accuracy of the derived analytical estimates. For realistic wave amplitudes, the levels of probabilities of trapping are generally comparable for oblique and parallel waves, but they turn out to be most efficient over complementary energy ranges. Trapping acceleration of 100 keV electrons. (C) 2015 AIP Publishing LLC

Дослідження синдрому емоційного і професійного вигорання у фармацетичних працівників

The burnout as a result of professional stress occurs when the adaptive capacity (resources) of the pharmaceutical worker in overcoming stressful situation becomes difficult, the "emotional burnout syndrome" - is the appropriate response to prolonged working stresses of employee during his professional activity. Our conducted researches in the regions of the country show that only 3-5% of pharmaceutical professionals familiar with the term "emotional burnout syndrome". So inKievto 10 per cent of people are familiar with this concept, at the same time, 54 per cent of workers aged 45-60 years old and 32 per cent aged 25-30 years old every day get into stressful situations and have different diseases, indicating the presence of the syndrome "professional burnout".Выгорание как следствие профессиональных стрессов возникает тогда, когда адаптационные возможности (ресурсы) фармацевтического работника в преодолении стрессовой ситуации становятся затруднительными, т.е. "синдром эмоционального выгорания" – это соответствующая реакция на продолжительные рабочие стрессы работника, в процессе его профессиональной деятельности. Проведенные собственные исследования в областях страны свидетельствуют, что только 3-5%  фармацевтических работников знакомы с понятием "синдром эмоционального выгорания". Так в  г. Киеве до 10% человек ознакомленным с этим понятием, в то же время 54% работников в возрасте 45-60 лет и 32% в возрасте 25-30 лет ежедневно попадают в стрессовые ситуации и имеют различные заболевания, свидетельствующие о наличии синдрома "профессионального выгорания".Вигорання як наслідок професійних стресів виникає тоді, коли адаптаційні можливості (ресурси) фармацевтичного працівника у подоланні стресової ситуації стають скрутними, тобто "синдром емоційного вигорання" - це відповідна реакція на тривалі робочі стреси працівника, в процесі його професійної діяльності. Проведені власні дослідження в регіонах країни свідчать, що тільки 3-5% фармацевтичних працівників знайомі з поняттям "синдром емоційного вигорання". Так у м. Києві до 10% осіб  ознайомлені з цим поняттям, в той же час 54% працівників у віці 45-60 років і 32% у віці 25-30 років щодня потрапляють в стресові ситуації і мають різні захворювання, що свідчать про наявність синдрому "професійного вигорання"

Prevalence of professional burnout among practicing cardiologists in the constituent entities of the Russian Federation

The burnout syndrome among healthcare professionals is a headline problem in the world, as it leads to poor health of medical workers, affects patient satisfaction with health care and the healthcare system as a whole. At the same time, existing preventive measures can improve the well-being of staff.Aim. To study the prevalence of professional burnout syndrome among practicing cardiologists in the Russian Federation (RF).Material and methods. This cross-sectional study was carried out using the method of online anonymous surveying. The inclusion criterion was the current practical activity in the RF. The study involved 452 cardiologists from 8 federal districts (women; n=377, 83,4%), 48,2% of which worked in a hospital. Occupational burnout was assessed using the Maslach Burnout Inventory (MBI) questionnaire in the Russian language adaptation for healthcare workers by N. E. Vodopyanova and E. S. Starchenkova. The score was calculated on three subscales (emotional exhaustion, depersonalization, personal accomplishment), the maximum score for the subscales was 54, 30 and 48, respectively. The personal accomplishment subscale is the opposite as follows: the higher the score, the less the symptom severity. Additionally, demographic parameters, working conditions, the desire to change job and field of activity were taken into account. Regression analysis was used to establish associations of burnout with factors.Results. The median score of the emotional exhaustion subscale was 29,5 (23,0; 35,0) points, depersonalization — 12,0 (8,0; 16,0) and personal accomplishment — 32,0 (28,0; 37,0). Men had higher depersonalization score than women as follows: 15,0 (10,0; 18,0) vs 11,0 (8,0; 15,0), p=0,001. High degrees of emotional exhaustion and depersonalization (burnout) were found in 235 (52%) cardiologists, while all three symptoms simultaneously — in 132 (29,2%) doctors. There were no symptoms of burnout in 84 (18,6%) cardiologists. A high degree of burnout was associated with a desire to change job (p<0,001).Conclusion. A high prevalence of professional burnout among practicing cardiologists in the RF was revealed, which, in turn, is associated with the desire to change job or occupation

Stimulation of Liver Regeneration Using a Titanium Nickelide Implant (Experimental Study)

Currently, morbidity and mortality from chronic diffuse diseases of the liver and cirrhosis continue to increase worldwide. The difficulty of stabilizing the process with pharmacological agents, lots of restrictions for liver transplantation, the palliative character of the surgical correction of complications determine the urgency of finding various ways to stimulate liver regeneration, including surgical ones. Most of the known methods of surgical stimulation of regeneration are quite traumatic, and their stimulating effect is short-lived. The methods associated with cellular technologies are mostly expensive, ineffective, or poorly understood. In the experimental study, the effect on the parenchyma of a healthy and cirrhotic liver clips for clamping parenchymal organs exerting different unit pressure on the tissue was studied. The object of the study was laboratory rats with a healthy liver and animals with simulated cirrhosis. The animals were operated on with the imposition of titanium nickelide clips on the liver. Changes in the liver were studied 3, 7, 14, and 28 days after the surgery by histological examination of various parts of the liver. It was established that the clip with a lower specific pressure did not cause tissue necrosis, led to atrophy of the marginal part of the liver, also increased hepatocytes and binuclear hepatocytes were observed in the bulk of the liver. A decrease in the proportion of connective tissue was also observed in groups with liver cirrhosis. Thus, we consider it possible to use clips with a certain specific pressure on the tissue as a method of stimulating the reparative properties of the liver in chronic diffuse diseases and cirrhosis of the live