Immediate results of surgical treatment of high and intermediate risk pulmonary embolism in elderly and senile patients

The aim of the study: is to analyze the immediate results of surgical treatment of high-and intermediate-risk PE in a group of elderly and senile patients. Material and methods. The study included 43 patients operated on for high-and intermediate-risk pulmonary embolism between 2008 and 2019. In the general group of patients, the number of women prevailed and amounted to 67.4%. The average age was 65.4 ± 4.23 years old. The Miller index in the general group was 29.1 ± 1.42. The Geneva Index was 8.4 ± 1.12. The average pressure in the pulmonary artery at the time of operation was 54 ± 1.4 mm Hg, and the peak pressure was 68 ± 3.43 mm Hg. Results. 5 patients died at the hospital stage. Thus, the hospital survival rate of patients was 88.4%. Among nonlethal complications, cardiovascular and respiratory failure prevailed. According to the statement, the calculated pressure gradient in the pulmonary artery was 29.0 ± 3.1 mm Hg. Conclusion. Surgical treatment is a highly eff ective and reliable method of treatment in the group of older patients.

THE COMPARISON OF THE DYNAMIC TESTS RESULTS FROM SENSORY PLATFORMS

The article deals with dynamic plantography, which is a popular diagnostic method focused on assessment of the foot condition during walking and to expose foot disorders. The aim of the paper is to discover whether it’s possible to do dynamic analyses on short platforms by using comparison of short and long sensory platform output. To get dynamic output were used ImportaMedica platforms, specific long platform Elegance and short platform Speed. Three subjects were involved in dynamic test on both platforms. The evaluated parameters were surface of the foot, maximum and average pressure, speed and gait line. By comparing these parameters the biggest difference was discovered in adapting walking because of the correct tread on short platform. When comparing the outputs from the long and short platforms, a longer duration of the right and left footsteps was recorded for all three subjects on the short platform.

Coaction of Wind and Rain Effects on Large-Span Hyperbolic Roofs

Rainfall is often accompanied by strong winds. The large-span roof structure has a low height, its surrounding turbulence is high, and the wind speed changes greatly. The effects of coaction of wind and rain on the roofs cannot be ignored. Wind-driven rain (WDR) is an oblique movement phenomenon of raindrops generated by wind flow. Four types of hyperbolic roofs, that is, square, rectangular, circular, and elliptical, are selected as the objective to study the wind-driven rain by CFD simulation. Effects of wind direction, wind speed, and rainfall intensity on the WDR are analyzed. Pressure distribution of four types of hyperbolic roofs under coaction of wind and rain is obtained. The results are compared with those from the wind action only. The roofs are partitioned to obtain the coaction of wind and rain pressure of the four large-span hyperbolic roofs with different shapes under the most unfavorable working conditions. The results show that the average pressure coefficient of the roof surface increases with the increase of wind speed and rainfall intensity. The reference value of the average pressure coefficient of wind-driven rain on the surface of the roof is given, which provides a reference basis for the design of wind-driven rain on similar hyperbolic roofs.

The limiting state of bodies during separation in the case of the general plane problem

Работа посвящена решению общей плоской задачи, связанной с определением предельного состояния тел при отрыве. Уравнения, определяющие условия предельного состояния принимаются функциями, зависящими от среднего давления и направлений отрыва. В результате вычислений были получены характеристические уравнения для двух случаев: при достижении предельных значений отрыва двумя главными напряжениями и при достижении предельного значения отрыва одним главным напряжением. Для двух рассмотренных случаев были получены уравнения характеристик и соотношения вдоль них. The work is devoted to the solution of the general plane problem related to the determination of the limiting state of bodies during separation. The equations defining the conditions for the limiting state are taken as functions that depend on the average pressure and directions of separation. As a result of calculations, the characteristic equations were determined for two cases: when the limiting values of separation by two main stresses are reached and when the limiting value of separation by one main stress is reached. For the two considered cases, equations of characteristics and relations along them were obtained.

Hydrodynamic Lubrication of Partially Textured Gas Parallel Slider Bearings with Orientation Ellipse Dimples

The hydrodynamic lubrication performance of partially textured gas parallel slider bearings with orientation ellipse dimples is investigated in this paper. By using the multigrid finite element method, the pressure distribution between a partially textured slider and a smooth slider is obtained. The geometric parameters of the ellipse dimples are optimized to maximize the average pressure under a given sliding speed. The numerical results show that geometric parameters such as orientation angle, depth, slender ratio, and area density have an important impact on hydrodynamic pressure. Besides, the effect of textured fraction on hydrodynamic pressure is investigated under a given sliding speed. It is observed that the optimum textured fraction for maximizing the average pressure is dependent on the sliding speed.

Numerical Study on Effects of Geometric Parameters on the Release Characteristics of Straight Sudden Expansion Gas Extinguishing Nozzles

In order to guide the optimization design of the nozzle of the aircraft-fixed gas fire extinguishing system, we studied the influence of nozzle geometric parameters including outlet–inlet area ratio, length–diameter aspect ratio, and wall roughness on the distribution of pressure and velocity in the nozzle on the basis of CFD simulations. Although the structure of the nozzle is axisymmetric, the spatial distribution of the pressure and velocity during the flow and release of gas extinguishing agent is not completely symmetric. It was found that both of the outlet–inlet area ratio (δ) and the length–diameter aspect ratio (ξ) had a significant impact on the distribution characteristics of the pressure and axial velocity in the nozzle. With the increase of δ, the average pressure at the outlet cross-section of the nozzle decreased monotonically, while the average axial velocity at the outlet increased approximately linearly. When ξ≥2, the uniformity of the pressure and velocity distribution at the nozzle outlet was significantly improved. Moreover, with the increase of ξ, the average pressure and the average axial velocity of the outlet both showed a non-monotonic change trend, and the optimal value of ξ should be about 3.0. Compared with δ and ξ, the influence of the nozzle wall roughness (εN) on the flow and release characteristics of the extinguishing agent was weak. With the increase of εN, the average pressure of the nozzle outlet increased slightly, while the average axial velocity at the nozzle outlet decreased slightly.

Enhancing the differentiation of walking and standing via the ratio of plantar pressures

Differentiation of standing and walking based on plantar pressures is helpful in developing strategies to reduce health risks in the workplace. In order to improve the differentiation ability, the paper proposes a new metric for posture differentiation, that is, the pressure ratio on the two anatomical plantar regions. The plantar pressures were collected from 30 persons during walking and standing. After verifying the normal distribution of the pressure ratio by the Monte Carlo method, two-way repeated-measures ANOVA was conducted for the pressure ratios. The advantage of the pressure ratio over two conventional pressure metrics (the average pressure and the peak pressure) is demonstrated by its much larger size effect. Furthermore, the pressure ratio permits to establish value ranges corresponding to walking and standing, which are less influenced by specific person factors, thus facilitating the design of a standardized posture recognition system. The underlying mechanism underlying the pressure ratio is discussed from the aspect of biomechanics of movement.

Thermal Performance Characteristics of a Microchannel Gas Heater for Solar Heating Applications

In the present article, the heat transfer and fluid flow of the air in a compact microchannel gas heater (MCGH) was experimentally quantified. To understand the effect of heat flux value (HFV), and inlet velocity on the heat transfer coefficient (HTC), wall temperature, friction factor, Nusselt number, average pressure-drop value (PDV) and performance index (PI), a microchannel gas heater was constructed and tested with pressurized air. The results showed that the HTC was 20 W/(sqmK) to 70 W/(sqmK), corresponding to inlet velocities 6.7 m/s and 16.7 m/s, respectively within HFV < 1 kW/m2. Also, the highest PI was 1.19 meaning that the HT rate can be increased by 19% at u = 15 m/s in comparison with the reference case (at u = 13.3 m/s). Likewise, the HTC was intensified once the inlet velocity is increased. It was also identified that increasing the HFV has a strong effect on wall temperature, however, slightly changes the HTC. By increasing the heat flux value from 200 W/sqm to 1000 W/sqm, the HTC increased only by 4.7% which was associated with the poor thermophysical properties of air flowing inside MCGH. Two main mechanisms of wall slip and viscous heating were identified as main contributors to the heat transfer enhancement in MCGH.

Study on turbulent flow in wave wall tube heat exchanger

The traditional straight wall tube heat exchanger has low heat exchange efficiency, in order to solve this problem, the turbulent flow in wave wall tube heat exchanger was studied by numerical simulation. It is found that the unique corrugated structure of the heat exchange tube in the wave wall tube heat exchanger can improve the flow state of the fluid in the heat exchanger. The average pressure drop of heat exchanger gradually increases with the increase of Reynolds number Re. Under the same conditions, the average pressure drop of wave wall tube heat exchanger is lower than that of straight wall tube heat exchanger. The improvement of heat exchange performance of heat exchanger can not be realized only by increasing the inlet flow of heat exchanger. The wave wall tube heat exchanger can strengthen the heat exchange of the fluid in the heat exchanger.

Determination of the limiting state of bodies during separation in the case of the general plane problem

The paper considers the general plane problem of determining the limiting state of bodies during separation. The conditions for reaching the limiting state are considered to depend on the average pressure and the direction of separation. The paper defines the characteristic equations for two cases of separation: equality of two principal stresses to the limiting value of separation and equality of one principal stress to the limiting value of separation. Equations of characteristics’ lines and relations along them are determined.