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В статье представлено описание гидродинамической теории детонации и известные классические методики расчета скорости детонации на основе законов сохранения условия Чепмена-Жуге и уравнения состояния и термодинамические методы расчета скорости детонации, основанные на теплоте взрыва и составе продуктов детонации. Проведен расчет скорости детонации промышленных эмульсионных ВВ (ЭВВ) порэмит-1А, нитронит Э-70, Э-100 и фортис 70, 85, 100 по различным методам расчета предлагаемых отечественными и зарубежными учеными. Проведен сравнительный анализ расчетных значений с данными из технических условий на производство ВВ и измеренными величинами скорости детонации на карьерах в технологических скважинах, а также на полигонах испытаний взрывчатых материалов (ВМ) в гильзовых зарядах, в условиях предприятий Урала, Мақалада детонацияның гидродинамикалық теориясының сипаттамасы және жарылыс жылуы мен детонация өнімдерінің құрамына негізделген детонация жылдамдығын есептеудің белгілі классикалық әдістері, Чапман-Джугет шарттары мен күй теңдеулері және детонация жылдамдығын есептеудің термодинамикалық әдістері келтірілген. Отандық және шетелдік ғалымдар ұсынатын есептеудің әртүрлі әдістері бойынша порэмит-1А, нитронит Э-70, Э-100 және Фортис 70, 85, 100 өнеркәсіптік эмульсиялық ВВ (ЭВВ) детонация жылдамдығын есептеу жүргізілді. ЖВ өндірісінің техникалық шарттарынан алынған деректермен және технологиялық ұңғымалардағы карьерлерде, сондай-ақ гильзалық зарядтардағы жарылғыш материалдарды (ЖМ) сынау полигондарында, Орал кәсіпорындары жағдайында детонация жылдамдығының өлшенген шамаларымен есептік мәндерге салыстырмалы талдау жүргізілді, The article describes the hydrodynamic theory of detonation and the known classical methods for calculating the detonation velocity based on the Chapman-Jouguet condition and the equation of state, as well as thermodynamic methods for calculating the detonation velocity based on the heat of explosion and the composition of the detonation products. The detonation velocity of industrial emulsion explosives such as Poremite, Nitronit, Fortis was calculated using various calculation methods proposed by domestic and foreign scientists. A comparative analysis of the calculated values with data from the technical specifications for the production of explosives and measured values of the detonation velocity in quarries in technological wells, as well as in test sites for explosive materials in cartridge charges, was carried out under the conditions of enterprises in the Urals, Горный журнал Казахстана, Выпуск 4 (2016) 2023, Pages 28-36

RDX containing a small amount of single-walled carbon nanotubes is obtained by the method of co-precipitation out of a solution. The detonation of this composition is studied by an electromagnetic method of mass velocity measurement and by a high-resolution electroconductivity method. A clearly expressed chemical spike is observed. Preliminary indications of reaction acceleration in the presence of nanotubes are obtained. The electroconductivity measurements are complicated because of the noticeable conductivity of the original material; if this factor is taken into account, the electrical conductivity profiles behind the detonation front are similar to those observed for pure RDX. Possible reasons for the influence of nanotubes on detonation characteristics are discussed.

The mathematical model of vertical penetration of a steel pipe in soil with a shock pulse generator is described. The influence of the external problem parameters on the attenuation of the shock pulse propagating along the pipe is described, and the process generalities are found. The attenuation law of the mass velocity amplitude in the shock pulse along the pipe during vertical penetration in soil is revealed.

The dynamic status near the surface of a catalyst can significantly affect the catalytic process, because the overall reaction rate depends on the mass velocity of product attachment and reactant detachment. As a dominant diffusion mechanism, molecular diffusion is known as a slow process that inhibits the fast contact between the reactants and the heterogeneous catalyst, which depresses catalytic conversion efficiency. Herein, we report a strategy that can break such a stagnant layer to facilitate the mass transport toward the catalyst surface, wherein Pd nanocubes (NCs) encapsulated in soft metal-organic framework (MOF) nanosheets are used as catalysts for the hydrogenation reactions. The soft MOF supports render deformable features to enhance mass transport across the Pd NCs, which is vital to enhance the catalyst performance. In combination with numerical simulations, we identify the deformable MOF driven by the shear force of flowing fluid to increase dye adsorption and catalytic conversion by 5- and 3-fold, respectively, as compared to a counterpart system containing nondeformable MOFs. The catalytic efficiency presents a volcano-type trend with the length-to-spacing ratio of MOF nanosheet being designed and reaches the maximum with a length-to-spacing ratio of 2:1. This technique provides unique opportunities to design a proof-of-concept self-propelled catalysis on the basis of a greater mechanistic understanding of heterogeneous catalytic reactions.

An important task in seismic hazard assessment is the estimation of intensity and frequency of rare strong seismic shaking, in particular, the long-term peak ground velocity values (PGVs). A recently proposed method is suitable for simply estimating PGVs based on the examination of the magnitude of displacements of rock blocks. The effectiveness of this method is demonstrated by results of studies on the source zones of two large earthquakes and a vicinity of one strong explosion. In this study, the method is applied to the examination of archeoseismological data from the ancient Rehovot-ba-Negev city and other ancient cities from the Negev desert (in Southern Israel) where numerous evidences of presumable seismic damage were found earlier. The cities and also a sophisticated irrigation system within the region, which existed in the Negev desert, were abandoned however in the middle of the seventh century. The abandonment could be caused by a combined effect, from not only the cessation of the state support from Byzantium as a result of the Arab conquest but also the severe destruction from the strong earthquake that hit the area at that time. The intensities of the seismic events that hit the cities were estimated earlier, which are within the range of 8–9. Our estimates indicate that the PGV values are about 1.5 m/s. Hence, the magnitude of the causative earthquake could be in the range M ≈ 6.5–7.5, and the location of the epicenter might be at a distance of a few dozens of kilometers from the ancient Rehovot-ba-Negev city, while the other variants associated with the earthquake seem to be less probable. Keywords: Ancient earthquakes, Ancient cities in the Negev desert, PGV estimation from macroseismic data, Earthquake hazard assessment for southern Israel

Fundamental features of explosive compacting of powder mixtures containing high-melting metal carbides and metallic binders are under consideration. The effect of acoustic rigidity of metallic binders on the residual porosity of samples after explosive treatment is revealed. It is shown that the degree of compacting of mixtures of carbide powders with metals under explosive compaction is determined by the possibility of arrival of shock waves in the metallic binder particles at their surfaces free of contacts with other particles and with a mass velocity acquired by the metallic binder at these surfaces due to unloading.

This study performs the comparative analysis of R32 and R410A condensation inside a 4.2 mm ID microfin tube: the effects of saturation temperature, vapour quality and mass velocities are evaluated. The heat transfer coefficients show a great sensitivity to vapour quality, a non-negligible sensitivity to saturation temperature/pressure, and a non-monotonic trend versus mass velocity. The microfin tube exhibits a maximum heat transfer enhancement with respect to the smooth tube around 3.5−3.6 at a mass velocity of 200 kg m−2s−1 and a vapour quality of 0.8. The optimum mass velocity for R32 and R410A condensation inside the microfin tube is in the range 150−300 kg m−2s−1. R32 exhibits condensation heat transfer coefficients 20 − 30% higher and frictional pressure drops 10 − 20% higher than those of R410A and it seems a valuable low GWP substitute for R410A.

Background The relationship between the visual sensory and center-of-mass characteristics during the sit-to-stand task is not well documented. Do the center of mass strategies change with restricted vision during the sit-to-stand task? Methods The participants in this study were fifteen girls with congenital blindness (age (94.6 (5.6) months), mass (25.6 (2.0) kg), and height (1.3 (0.0) m)) and 30 healthy girls with no visual impairment who were divided randomly into two groups. The two experimental condition groups consisted of one in which the participants were assigned to keep their eyes open (age (95.8 (5.4) months), by mass (26.1 (5.1) kg), and by height (1.3 (0.0) m)) and the other in which the participants were assigned to keep their eyes closed (age (93.8 (0.0) months), by mass (24.2 (0.0) kg), and by height (1.1 (0.0) m)) for 20 min before the test. The center-of-mass displacement of the foot, leg, and thigh were calculated for dominance and non-dominance during the sit-to-stand performance at initiation, seat-off, and end events. Findings Congenital blindness was associated with the non-dominant center-of-mass displacement of the foot increasing upwards during all events (initiation, p = 0.025; seat-off, p = 0.036; end, p = 0.034), as well the non-dominant center of mass of the foot moving anteriorly during the initiation point (p = 0.016). In addition, the center-of-mass displacements for the dominant and non-dominant feet (initiation, p = 0.006, and p = 0.016; seat-off, p = 0.006, and p = 0.014; end, p = 0.006, and p = 0.013, respectively) and legs (16.98%, p = 0.024, d = 0.95; and 17.88%, p = 0.032, d = 0.99, respectively) in the eyes-closed group shifted to a forward direction, and the center of mass of the non-dominant foot (initiation, p = 0.024; seat-off, p = 0.021; end, p = 0.012) moved significantly upwards. Furthermore, the whole body center of the mass velocity (anterior-posterior axis (initiation, p = 0.042; seat-off, p = 0.006; end, p = 0.005)) in the eyes-closed group was smaller than that in the eyes-open group. Interpretation The findings show that the sit-to-stand center of the mass components in blind children may have clinical importance for the rehabilitation of these subjects.

The oscillations of the mass velocity of melting during cyclic electroslag remelting of ChS-82 steel ingots under laboratory and industrial conditions are studied. The data on the mass velocity, the remelting current, and the furnace voltage that form by an automatic control system during the process in the form of electronic tables are processed. An analysis of these data demonstrates that the oscillations of these parameters that accompany melting substantially affect the ingot quality.

An experimental research has been carried out for vertically upward two-phase flow of air-water across inverted half U-tube bundle with or without anti-vibration bars. Pressure drop characteristics in inverted half U-tube bundle and anti-vibration bars were obtained and analyzed. New correlations for total pressure drop of two-phase flow in inverted half U-tube bundle and local pressure drop of two-phase flow in anti-vibration bars were developed. The measured two-phase pressure drops in inverted half U-tube bundle of three walls in the test sections were unequal. The pressure drop in the side wall dominated the total pressure drop of two-phase flow in inverted half U-tube bundle for 57 ≤ G −2 ·s −1 , while the pressure drop in the front wall dominated for 114 G ≤ 143 kg·m −2 ·s −1 . An obvious mass velocity effect was observed for the total pressure drop of two-phase flow in inverted half U-tube bundle. For a given Martinelli parameter, the total pressure drop of two-phase flow in inverted half U-tube bundle decreased with an increasing mass velocity. The two-phase local pressure drop data of anti-vibration bars could be fitted well in terms of the Martinelli parameter and mass velocity.

Presented are results of experimental investigation of heat transfer at downflow condensation of refrigerant R-21 in a vertical assemblage of minichannels in a plate-fin heat exchanger with plane fins. Selection of refrigerant was caused by the fact that its physical properties at room temperature are similar to those of cryogenic liquids at low temperatures. A pattern of vapor-liquid downflow in the heat exchanger channels was plotted using the working section with a transparent wall. For the mass velocity in the range of 30 to 50 kg/m2s and the wall subcooling below −2◦C, the dependence of the heat transfer coefficient on the mass vapor content is determined and a method is proposed to calculate the heat transfer coefficient that is in good agreement with the experimental data.

Even with the recent advances in the area of dynamic walking on humanoid robots there is still a significant amount of manual calibration required in practice due to the variances in the hardware. That is in order to achieve the performance needed in environments such as RoboCup. We present a LIPM-based closed-loop walk, that adapts to differences in the physical behavior of the robot by optimizing parameters of the model directly on the NAO while walking and executing other tasks. A significant amount of errors in the model predictions can be reduced without using a more complex model simply by adjusting the LIPM to fit the observed behavior. Our experiments show that the optimized model yields a more controlled, faster and even more energy-efficient walk on different NAO robots and on various surfaces without additional manual parameter tuning.

We have regarded a mixture as a superposition of coexisting, interacting, and possibly reacting species. We have discussed the motion of monochromatic species parcels and analyzed the mixture kinematics with reference to the species diffusion velocities defined as the differences between the individual species velocities and the mixture mass velocity. In this chapter, we turn our attention to the balance of forces and introduce species and mixture stresses that develop spontaneously in hydrostatics or as a result of the motion.

In this study, a new numerical model based on the method of particles in cells, which differs in principle from the schematic of particles in Harlow cells by the fact that the particles have their own velocity and, therefore, boundaries with a vacuum are not spread, is proposed for the first time. The model makes it possible to pass the stage of the “continuous” transition to rupture development and description of the dynamics of the further state of its “banks.” Based on the Iordansky–Kogarko–van Wijngaarden mathematical model (IKW model), the formation of rupture and its further dynamics in the bubble fluid layer in the jump region of the mass velocity is numerically investigated using the proposed method. The dynamics of the state of the medium on both rupture “banks” is calculated including the structure of the rarefaction waves, fields of mass velocity and density, and cavitation development in the time range up to 2 μs when the subsequent dynamics of the layer succumbs to the prognosis.

An approximate kinetic analysis of the process of intense evaporation has been carried out. The analytical solutions obtained for temperatures, pressures, and mass velocities of vapor agree well with the available numerical and analytical solutions. The evaporation limiting mass velocity has been calculated.

We discuss the nonrelativistic limit of the relativistic Navier-Fourier-Stokes (NFS) theory. The next-to-leading order relativistic corrections to the NFS theory for the Landau-Lifshitz fluid are obtained. While the lowest order truncation of the velocity expansion leads to the usual NFS equations of nonrelativistic fluids, we show that when the next-to-leading order relativistic corrections are included, the equations can be expressed concurrently with two different fluid velocities. One of the fluid velocities is parallel to the conserved charge current (which follows the Eckart definition) and the other one is parallel to the energy current (which follows the Landau-Lifshitz definition). We compare this next-to-leading order relativistic hydrodynamics with bivelocity hydrodynamics, which is one of the generalizations of the NFS theory and is formulated in such a way to include the usual mass velocity and also a new velocity, called the volume velocity. We find that the volume velocity can be identified with the velocity obtained in the Landau-Lifshitz definition. Then, the structure of bivelocity hydrodynamics, which is derived using various nontrivial assumptions, is reproduced in the NFS theory including the next-to-leading order relativistic corrections., 10 pages, replaced with published version in the Brazilian Journal of Physics