Redistribution Of Flow Research Articles

Réducteur de sinus coronaire : revue de littérature et enjeux autour du registre France Reducer

Coronary sinus Reducer implantation is a percutaneous technique used to treat patients suffering from refractory angina pectoris. The device narrows the coronary sinus, increases the back pressure in the myocardial venous system and forces redistribution of coronary blood flow from less ischemic subepicardium to the more ischemic subendocardium. Multiple clinical studies had proven its efficacy to alleviate myocardial ischemia and related symptoms, and to improve the quality of life of patients with refractory symptomatic chronic coronary artery disease for whom coronary revascularization is deemed unsuitable. This literature review aims to expose the device design, its mechanisms of action, and the clinical data supporting its use.Since November 2021 Reducer's reimbursement has been granted in France by the national health authority. It is the first device to be approved under a newly established reimbursement approval process. A transitional coverage is provided with opportunities for renewal before applying for full-time reimbursement. To fulfill the requirements of the National Commission for Evaluation of Medical Devices and Health Technologies, the French Society of Cardiology has been creating the France Reducer registry. This clinical registry has been collecting data from patients undergoing coronary sinus Reducer implantation regarding their clinical situation, periprocedural information, and one-year follow-up. It is crucial for the future of this emerging therapeutic option in France. To date, 215 patients from 28 centers have been included between June 2022 and September 2023.

Resilience enhancement of water distribution networks under pipe failures: a hydraulically inspired complex network approach

Abstract The resilience of water distribution networks (WDNs) should be proactively evaluated to reduce the potential impacts of disruptive events. This study proposes a novel hydraulically-inspired complex network approach (HCNA) to assess and enhance WDN resilience in the case of single-pipe failure. Unlike conventional hydraulic-based models, HCNA requires no hydraulic simulations for resilience analysis. Instead, it quantifies the failure consequences of edges (pipes) on the WDN graph by incorporating topological attributes with flow redistribution triggered by failures. This HCNA procedure leads to the identification of critical edges (pipes), as well as impacted ones, representing edges more susceptible to the failure of others. The impacted edges are then systematically resized by integrating HCNA with a graph-based design approach, obtaining a wide range of resilience enhancement solutions. A comparative study between HCNA and a hydraulic-based model for three WDNs confirms HCNA's effectiveness in identifying the most critical pipes in various network sizes. Furthermore, HCNA provides comparable resilience enhancement solutions with a hydraulic-based evolutionary optimization but with significantly lower computational effort (1,400 times faster). Thus, it can efficiently be used for resilience enhancement of large-scale WDNs, where the application of conventional optimizations is limited due to the intensive computational workload.

The debt component as a factor in assessing the financial security of the economy: The cross-country aspect

Subject. The article addresses trends in basic financial indicators formed under global political and economic challenges of our time, with an emphasis on debt policy to substantiate the significance of their impact on the financial security of the economy of various States. Objectives. The purpose is to develop economic and mathematical justification for assessing the financial security of the State based on mathematical modeling and rating of macroeconomic indicators, from the perspective of debt approach assessment. Methods. We employ the method of weighted sums as the main approach to solve multi-criteria optimization problems and the method of attributing points. A weighting factor is calculated for each criterion, on the basis of which the individual rating of each factor is calculated. The basis for the application of the weighted sum method is a factor analysis, implemented on the basis of statistical and dynamic approaches. Results. The paper assesses the financial security of the economy of various States on the basis of predominance of the debt policy importance. The rating enables to assess the effectiveness of the State's financial policy, depending on priorities of its implementation for a certain representative period. The selected indicators characterize a multidirectional impact on the financial security of the economy, however, the optimization approach allows for objective assessment and assumes the possibility of their expansion and variation to determine financial security based on assessment of the predominant impact of certain groups of stimulator and destimulator indicators. Conclusions. The study serves as a basis to systematize a set of diverse indicators of financial flows redistribution in the economy to characterize financial security, depending on the parameters characterizing the main directions and instruments of financing priority areas of economic development.

PENERAPAN CATATAN AKTIFITAS FISIK, DIET, ISTIRAHAT & KELOLA STRESS PADA IBU RUMAH TANGGA DI RT.2 RW.4 GAYUNGAN, SURABAYA

Introduction & Aim: This PPM activity is motivated by the high incidence of non-communicable diseases such as cardiovascular disease. The epidemiological transition of this disease describes a tendency towards degenerative diseases which is determined by people's behavior. Based on a survey conducted in RT 2 RW 4, Gayungan, Surabaya City, most of the residents suffer from high blood pressure. High blood pressure is a type of cardiovascular disease. The aim of this activity is to provide education on healthy lifestyles to avoid the risk of contracting CHD to residents. Method of Activity: This community service is carried out by providing education about cardiovascular disease and its prevention. At the end of the education, being given a notebook of daily activities can be a motivation to continue to behave in a healthy way to manage stress. Results: This activity was carried out on Jl. Dukuh Menanggal RT 2 RW 4 Gayungan sub-district, Surabaya City. Education is provided through PowerPoint media, leaflets, and daily recording sheets to improve healthy living and manage stress. After being given counseling, the level of knowledge of residents increased. To be able to implement what they have learned, residents are provided with personal notes as a reminder to live healthily. Discussion: survey results show that the majority of residents still lack regular physical activity. Cardiovascular disease is prone to attack people who lack physical activity. Physical exercise and sports activities will increase cardiac output, redistribution of blood flow, and reduce cholesterol and blood fat levels. Eating foods with balanced nutrition, as well as fruit and vegetables can provide additional vitamins, antioxidants, and fiber that the body needs. Conclusion living a healthy lifestyle with regular physical activity and eating more fruit and vegetables can avoid degenerative diseases.

Promoting FADH2 Regeneration of Hydroxylation for High-Level Production of Hydroxytyrosol from Glycerol in Escherichia coli.

Hydroxytyrosol is a natural polyphenolic compound widely used in the food and drug industries. The current commercial production of hydroxytyrosol relies mainly on plant extracts, which involve long extraction cycles and various raw materials. Microbial fermentation has potential value as an environmentally friendly and low-cost method. Here, a de novo biosynthetic pathway of hydroxytyrosol has been designed and constructed in an Escherichia coli strain with released tyrosine feedback inhibition. By introduction of hpaBC from E. coli and ARO10 and ADH6 from Saccharomyces cerevisiae, the de novo biosynthesis of hydroxytyrosol was achieved. An important finding in cofactor engineering is that the introduction of L-amino acid deaminase (LAAD) promotes not only cofactor regeneration but also metabolic flow redistribution. To further enhance the hydroxylation process, different 4-hydroxyphenylacetate 3-monooxygenase (hpaB) mutants and HpaBC proteins from different sources were screened. Finally, after optimization of the carbon source, pH, and seed medium, the optimum engineered strain produced 9.87 g/L hydroxytyrosol in a 5 L bioreactor. This represents the highest titer reported to date for de novo biosynthesis of hydroxytyrosol in microorganisms.

Trends and factors in the development of world tourism in the post-pandemic period

<p>This article is devoted to the study of modern factors and trends in the development of world tourism. Researching the impact of the pandemic on the state of modern tourism is extremely relevant, as COVID-19 has had a significant impact on the tourism industry worldwide. Various factors and trends in the development of this process, which are affected by the pandemic, were considered. That is why the study determined that the COVID-19 pandemic primarily led to the restriction of movements and the closing of borders between countries, which significantly reduced the volume of international travel. The analysis was carried out taking into account such factors as travel restrictions. The introduction of restrictions on international and domestic travel has become one of the main measures to combat the spread of the COVID-19 virus. This led to a sharp reduction in tourist trips and a significant deterioration of the global tourism sector. Also, the loss of revenue when the travel-related tourism sector faced severe financial difficulties due to the pandemic. Cancellations, border closures, and restrictions on international flights were found to have resulted in a significant loss of revenue for companies and hotels and affected employment in the sector. Differences in recovery have been identified when the recovery of international tourism after the pandemic is uneven in different regions of the world. Some countries and regions that quickly implemented effective measures to control the spread of the virus began to recover earlier than others. This led to the emergence of new “tourist hotspots” and the redistribution of tourist flows. New trends in tourism have been identified. The COVID-19 pandemic has caused a change in the preferences and behavior of tourists. Safety, health, and hygiene have become the main priorities when choosing a direction and types of recreation. As a result, the popularity of ecological tourism is growing, and new formats of tourist services are emerging, such as virtual tours and remote travel. In general, the COVID-19 pandemic has a serious and long-term impact on the current development of world tourism, leading to changes in the preferences and behavior of tourists, as well as causing a redistribution of tourist flows and difficulties of a financial nature in this area.</p>

Model cascading overload failure and dynamic vulnerability analysis of facility network of metro station

The existing studies mainly focused on the cascading failure of the whole metro but rarely on stations. In this paper, we map a metro station into a directed and hierarchical network, and propose a cascading overload failure model to study the network dynamic vulnerability. The passenger behavior and node load update are considered based on impedance function and mutual flow redistribution. Without changing the network topology, a flow optimization strategy is proposed to improve the network performance against cascading failure. Yuantong station of Nanjing Metro is studied. The results show the network is vulnerable and global failure occurs easily under small node tolerance. When the node tolerance excesses a critical value, the network can transit abruptly from global failure to balance state. We obtain that the critical node tolerances are 0.17 for the largest degree-based attack(LDA) and 0.19 for the largest load-based attack(LLA). The ranges of the optimal flow redistribution coefficient are identified by the flow optimization strategy, which are [0.15 0.2] for LDA and [0.2 0.25] for LLA. The result indicates that a proper guidance of passenger flow can be beneficial to the network performance while a strong intervention to passenger flow can instead increase the cascading failure risk.

Structural Vulnerability Analysis of Interdependent Electric Power and Natural Gas Systems

The growing use of gas-fired power generators and electricity-driven gas compressors and storage has increased the interdependence between electric power infrastructure and natural gas infrastructure. However, the increasing interdependence may spread the failures from one system to the other, causing subsequent failures in an integrated power and gas system (IPGS). This paper investigates the structural vulnerability of a realistic IPGS based on complex network theory. Different from the existing works with a focus on the static vulnerability analysis for an IPGS, this paper considers both static and dynamic vulnerability analysis. The former focuses on vulnerability analysis under random and selective failures without flow redistribution, while the latter concentrates on vulnerability analysis under cascading failures caused by flow redistribution. Also, different from the existing works with a focus on the IPGS as a whole, we not only analyze the vulnerability of the IPGS but also analyze the vulnerability of the power subsystem (PS) and gas subsystem (GS), in order to understand how the vulnerability of the IPGS is affected by its PS and GS. The analysis results show that (1) if the PS and GS are more susceptible to cascading failures than selective and random failures, the IPGS as a whole is also more vulnerable to cascading failures. (2) There are different dominant factors affecting the IPGS vulnerability under cascading failures and selective failures. Under cascading failures, the GS has a more significant impact on the IPGS vulnerability; under selective failures, the PS has a more important impact on the IPGS vulnerability. (3) The IPGS is more vulnerable to failures on the critical nodes, which are identified from the IPGS as a whole rather than from the individual PS or GS. The results provide insights into the design and planning of IPGSs to improve their overall reliability.

Comparative analysis of information products of land cover types
 of high spatial resolution in mapping floodplain landscapes

Intrazonal floodplain landscapes in the southern Russia remain relatively unaffected by the direct impact of anthropogenic activity, while zonal steppe landscapes are almost completely plowed, and semi-desert and desert are subject to high pasture loads. At the same time, climatic changes and the regulation of river flow by hydroelectric dams lead to the redistribution of river flow, which leads to the degradation of floodplain ecosystems due to a decrease in the duration and height of the flood. The construction of hydraulic structures, including shafts, dams, and arrays of irrigated lands, contributes to the withdrawal of significant areas from the floodplain regime. Reducing the duration of high water and the areas of flooding during them entails an increase in the mineralization of groundwater and stabilization of their level, which negatively affects natural floodplain ecosystems. Similar trends of hydrological and climatic changes are characteristic of floodplain landscapes of rivers in the zone of insufficient moisture, for example, the Don and its tributaries, the Volga in its lower reaches, the rivers of Central Asia. For these reasons, it is important to monitor the condition of floodplain landscapes, one of the tools of which is mapping based on remote sensing data. The purpose of this work is to map the types of land cover of floodplain landscapes of the Lower Volga on the basis of thematic information products ESA GlobCover, ESRI WorldCover, FROM-GLC10 with a spatial resolution of 10 m and GlobCover30 (GLC30) with a resolution of 30 m. It has been established that the actual area of wetlands regularly flooded during floods is 48% of the area of the entire territory. The most accurate estimates of the areas of wetlands, reservoirs, meadows and forests were obtained from the data of the ESA GlobCover information product, which is associated with the use of not only Sentinel-2 optical satellite images, but also Sentinel-1 radar. ESA data is recommended for analyzing the state of floodplain landscapes in the zone of insufficient moisture.

Cardiovascular decline in offspring during the perinatal period in an ovine model of fetal growth restriction.

Fetal growth restriction (FGR) increases the risk cardiovascular disease (CVD) in adulthood. Placental insufficiency and subsequent chronic fetal hypoxemia are causal factors for FGR, leading to a redistribution of blood flow that prioritizes vital organs. Subclinical signs of cardiovascular dysfunction are evident in growth-restricted neonates; however, the mechanisms programming for CVD in adulthood remain unknown. This study aimed to determine the potential mechanisms underlying structural and functional changes within the heart and essential (carotid) and nonessential (femoral) vascular beds in growth-restricted lambs. Placental insufficiency was surgically induced in ewes at 89 days gestational age (dGA, term = 148dGA). Three age groups were investigated: fetal (126dGA), newborn (24 h after preterm birth), and 4-wk-old lambs. In vivo and histological assessments of cardiovascular indices were undertaken. Resistance femoral artery function was assessed via in vitro wire myography and blockade of key vasoactive pathways including nitric oxide, prostanoids, and endothelium-dependent hyperpolarization. All lambs were normotensive throughout the first 4 wk of life. Overall, the FGR cohort had more globular hearts compared with controls (P = 0.0374). A progressive decline in endothelium-dependent vasodilation was demonstrated in FGR lambs compared with controls. Further investigation revealed that impairment of the prostanoid pathway may drive this reduction in vasodilatory capacity. Clinical indicators of CVD were not observed in our FGR lambs. However, subclinical signs of cardiovascular dysfunction were present in our FGR offspring. This study provides insight into potential mechanisms, such as the prostanoid pathway, that may warrant therapeutic interventions to improve cardiovascular development in growth-restricted newborns.NEW & NOTEWORTHY Our findings provide novel insight into the potential mechanisms that program for cardiovascular dysfunction in growth-restricted neonates as our growth-restricted lambs exhibited a progressive decline in endothelium-dependent vasodilation in the femoral artery between birth and 4 wk of age. Subsequent analyses indicated that this reduction in vasodilatory capacity is likely to be mediated by the prostanoid pathway and prostanoids could be a potential target for therapeutic interventions for fetal growth restriction (FGR).

Validation of the fast reactor plant dynamics analysis code Super-COPD using FFTF loss of flow without scram test #13

The Japan Atomic Energy Agency (JAEA) has been developing a plant dynamics analysis code named Super-COPD for design studies and safety analyses of sodium-cooled fast reactors. Since there are a few validation studies of a thermal–hydraulic model in a plant, including a point kinetics model considering reactivity feedback for anticipated transient without scram (ATWS) events classified into the beyond design basis events (BDBEs), further validation studies under BDBE conditions are needed to improve the prediction accuracy of the model. Therefore, JAEA has participated in the international benchmark analysis of loss of flow without scram (LOFWOS) test #13 performed at the Fast Flux Test Facility (FFTF) as one of passive safety demonstration tests hosted by the International Atomic Energy Agency. In the first step, the transient calculation with major reactivity feedback mechanisms and imposing measured power history was conducted with Super-COPD. The results were compared with the measured data. Several challenges were identified about the thermal–hydraulic model in the core and heat transport systems and the reactivity model in the point kinetics model. Consequently, the transient calculation was performed with modified models considering the radial heat transfer, flow redistribution, and interwrapper flow in the core. The time-dependent change and the second peak of the outlet temperature in the specified assembly were predicted accurately because the core thermal–hydraulics was reproduced well. Furthermore, the assembly bowing reactivity model was developed to improve the net reactivity, thereby resulting in a good agreement with the measured data on the reactor power, temperature, and flow rate in the primary loop. Thus, this paper proves the validation of Super-COPD for the LOFWOS event in the BDBE.

Stability studies of dispersed systems for physicochemical methods to enhance oil recovery in the presence of a hydrophobic filler

As the formation of highly permeable zones in the reservoir results in progressive watering of the produced products, restricting the movement of the oil displacement agent is one of the main conditions for further improving the effectiveness of methods for influencing oil-saturated formations. This can be achieved by targeted tamponing with physicochemical compositions of highly conductive channels and artificial fractures. In most cases, there is a redistribution of flow and, as a result, previously undrained reservoir intervals are brought into production.The effect of tamponing is best achieved by the use of dispersed systems containing various fillers. The use of such technologies is regulated in many documents used in the work of oil and gas producing enterprises. The formation of a high-quality water barrier in such technologies depends on the stability of the working composition.The article is devoted to the study of the influence of filler hydrophobicity on the sedimentation and aggregation stability of dispersed systems. The conditions under which the systems show the least tendency to sedimentation and are aggregatively unstable are considered. It has been shown experimentally that the stability of the systems is influenced by the hydrophobic properties of the filler, which do not allow the particles to enter the aqueous phase, swell and precipitate, thereby reducing the sedimentation stability. It has been shown experimentally that the systems composed of NaQMC or PetroPam P-104 have similar indicators for the time of onset of mass deposition of particles, their average calculated deposition rates as well as viscosity characteristics.

Glomerular microcirculation: Implications for diabetes, preeclampsia, and kidney injury.

This review outlines the features of tandem regulation of glomerular microcirculation by autoregulatory mechanisms and intraglomerular redistribution of blood flow. Multiple points of cooperation exist between autoregulatory and distributional mechanisms. Mutual interactions between myogenic and tubuloglomerular feedback (TGF) mechanisms regulating the inflow are briefly discussed. In addition to this, TGF operation involving purinergic, autocoid, and NO signaling affects, however, not only afferent arteriolar tone, but mesangial cell tone as well. The latter reversibly reconfigures the distribution of blood flow between the shorter and longer pathways in the glomerular tuft. I advance a hypothesis that blood flow in these pathways spontaneously alternates, and mesangial cell tonicity serves as a rheostatic shift between them. Furthermore, humoral messengers from macula densa cells, themselves dependent on myogenic mechanisms, fine-tune the secretion of renin and, subsequently, the local, intrarenal generation of angiotensin II, which, in turn, provides additional vasomotor signaling to glomerular capillaries through changing the tone of mesangial cells. This complex regulatory network may partially explain the phenomenon of renal functional reserve, as well as suggest implications for changes in renal function during pregnancy, early diabetes mellitus, and acute kidney injury.

Novel concepts in the management of angina in coronary artery disease.

Coronary artery disease remains a condition with high prevalence and detrimental effects on the quality of life of affected individuals. Its most frequent manifestation, stable angina pectoris, may be challenging to manage despite the available antianginal pharmacotherapy and adequate risk factor control, especially in subjects not amenable to revascularization. In the direction of refractory angina pectoris, several approaches have been developed over the years with varying degrees of success. Among the most recognized techniques in managing angina is enhanced external counterpulsation, which utilizes mechanical compression of the lower extremities to increase blood flow to the heart. Moving to coronary sinus reduction, it leads to an increase in coronary sinus backward pressure, ultimately augmenting myocardial blood flow redistribution to ischemic regions and ameliorating chronic angina. Clinical trial results of the above-mentioned techniques have been encouraging but are based on small sample sizes to justify their widespread application. Other interventional approaches, such as transmyocardial laser revascularization, extracorporeal shockwave myocardial revascularization, and spinal cord stimulation, have been met with either controversial or negative results, and their use is not recommended. Lastly, angiogenic therapy with targeted intramyocardial vascular endothelial growth factor injection or CD34+ cell therapy may be beneficial and warrants further investigation. In this review, we summarize the current knowledge in the field of angina management, highlighting the potential and the gaps in the existing evidence that ought to be addressed in future larger-scale, randomized studies before these techniques can be safely adapted in the clinical practice of patients with refractory angina pectoris.

Динамика объемных показателей работы больниц скорой медицинской помощи во время пандемии новой коронавирусной инфекции Covid-19

Summary. The aim of the study is to investigate the dynamics of volumetric indicators of emergency medical care inpatient work during the Covid-19 pandemic and the factors determining it. Materials and research methods. The material of the study was the data on the work of two multidisciplinary hospitals working in the mode of emergency (24/7/365) and having fundamental structural and functional features associated with the presence of beds for patients with a new coronavirus infection. The methods of the study are regulatory, statistical and analytical. Results of the study and their analysis. The results of the study showed that during COVID-19 pandemic there was a decrease in the volume performance of emergency hospitals. The factors causing differences in the organization of work of hospitals were identified. Among them: re-profiling of hospitals to receive infectious patients — deployment of beds for patients with COVID-19; redistribution of patient flows and changes in routing schemes for medical evacuation of patients; assignment of additional volumes of specialized medical care for non-infectious patients to unreprofiled multidisciplinary hospitals. It is concluded that emergency medical aid beds of the emergency hospitals in 2020-2021 performed the functions of a mobile general-purpose bed fund, allowing to sort and separate the flows of incoming patients and to ensure sanitary and epidemiological safety and quarantine measures.

Semianalytical Modeling for Multiphase Flow in a Fractured Low-Permeability Gas Condensate Reservoir.

During the production of fractured low-permeability gas condensate reservoir (FLPGCR), a phase transition takes place in both the formation and wellbore, resulting in multiphase flow when the pressure drops below the dew point pressure. Additionally, the presence of fractures causes the formation of stress-sensitive characteristics. Nevertheless, traditional analytical models, such as the two-region model or three-region model, overlook the coupling impact of the above factors, which could lead to incorrect pressure transient response and erroneous estimation of well and formation parameters. Therefore, this work presents a semianalytical model for an FLPGCR considering the effects of multiphase flow, stress-sensitive, and wellbore phase redistribution. The gas condensate reservoir is divided into N banks, and the radial fluid saturation variation is modeled by multiple annular reservoirs with a constant saturation in each annular reservoir. The behavior of a fractured reservoir is modeled by using the dual-porosity model. The Pedrosa transform was utilized to address the nonlinear differential equation arising from stress-sensitive behavior. To verify the semianalytical solution, it was compared with numerical simulation results from CMG. The results showed that there are 10 flow regimes for the proposed model. The shape of the type curve has the potential to identify the degree of blockage within the FLPGCR. The wellbore phase redistribution only affects the first transitional-flow regime, which slows the rate of pressure drop. The stress sensitivity will lead to the upward characteristic of the curve in a later stage. More attention should be paid to the upward pressure derivative curve at late times, which is conventionally regarded as the effect of a closed boundary when it may not be the case. In addition, the shape factor and composite radius may obscure the radial flow regime. Finally, the proposed model was applied to interpret the pressure measurements recorded from the Bohai field in China, which exhibits a better fitting quality than the traditional models.

Study of gas-liquid two-phase flow redistribution characteristics in the rod bundle channel using wire-mesh sensor

In subchannel analysis, the gas and liquid flow distribution phenomenon plays an important role in understanding rod bundle channels’ two-phase turbulent mixing mechanism. This paper obtained gas-liquid flow distribution data inside a vertical coupled subchannel rod bundle channel by utilizing a double-set wire-mesh sensor (WMS). To achieve evolutions of two-phase flow distributions, one subchannel was injected with gas and water called the donor channel, and the other injected with water is called the receptor channel. Four axial locations (Z/Dh = 28.95, 57.90, 86.86, and 115.81) were measured for each flow condition to obtain the evolution of the flow distribution. 36 flow conditions were acquired with 〈jg〉 from 0.073 to 1.02 m·s−1 and 〈jl〉 from 0.93 to 1.86 m·s−1 at Z/Dh = 115.81, including bubbly, cap-bubbly, and slug flow. The gas flow distributions were obtained by the cross-correlation calculation of the phase distribution data measured by a double-set WMS. The gas-phase flow rate relative errors acquired by WMS and rotameters are within ± 10%. To obtain the liquid flow distribution, the inter-subchannel equal-slip ratio assumption was introduced, which is according to the truth that two-phase flow characteristics between the adjacent subchannel are similar for most cases in this study. Further, obtained two-phase flow distribution data were verified and evaluated by Han et al.’s drift-flux model, and the relative errors for most cases are less than ± 20%. Results show that, under bubbly flow, the two-phase flow redistribution is weak. 90% of the gas was restricted in the donor channel, and the liquid flow was approximately distributed in both channels. With the increment of void fraction, two-phase flow redistributions are more severe. The liquid-phase recirculation flow was found in the receptor channel, under cap-bubbly and slug flow, which results in a higher gas-liquid flow in the donor channel than in the receptor channel. The rules of two-phase flow distributions indicate that the liquid-phase flow redistribution is more moderate than the gas phase. The drastic change in the gas-phase flow redistribution starts with the cap-bubbly flow. In addition, the current two-phase flow data indicates that the two-phase flow redistribution between the donor and the receptor channels does not follow the equal-volume principle postulated in the existing two-phase turbulent mixing model. Furthermore, current data also imply the relationship between void and mass flux distribution is not linear as assumed in the existing two-phase turbulent mixing model.

INCREASING THE EFFICIENCY OF CARGO AND PASSENGER TRANSPORTATION ON LINES WITH PARALLEL RUNS

Purpose. The purpose of the work is to determine measures to improve logistics operations with the specialization of directions for cargo and passenger transportation by transferring part of the transit cargo flow to parallel routes. Solving the problem of choosing a rational distribution of freight and passenger transportation depending on the specialization of directions will allow to optimize the use of throughput and transportation capacity and investments in infrastructure development. Method. Optimization of the transport process during mixed transportation involves the possibility of separating cargo traffic from passenger traffic. The proposed method involves solving the problem of choosing a rational distribution of cargo and passenger transportation depending on the specialization of directions. The idea of such demarcation is based on the fact that on the railway network it is possible to distinguish stations between which there are several parallel train routes. The research was carried out on the railway network connecting Lviv and Kyiv. When solving the problem, various indicators were considered: the length of the route, the time of movement, the mechanical operation of the locomotive, the load on the track, and others. In addition, the boundary conditions were taken into account: the volume of passenger traffic, cargo traffic, the carrying capacity of sections and the permissible speed of train movement. Results. A mathematical model of the redistribution of train flows on the railway network has been developed, which ensures the rational operation of the railway track with minimal costs for the reconstruction of the railway. Scientific novelty. It has been established that in the case of traffic separation, the timing of repairs may be different due to lower traffic intensity, which allows you to focus on specific types of repair work, and not on all types of work at the same time. Although the general principles of the periodicity of repairs may remain the same in both cases, periodicity schemes may differ depending on many factors, in particular, the intensity of operation, the technical condition of the vehicle, the timing of repairs and the availability of specialized personnel. Practical significance. With the application of the new approaches proposed by the authors to solving the tasks, schemes for the rational distribution of cargo and passenger transportation at the closed landfills of the regional branches of the South-Western and Lviv Railways were established, which will allow determining measures to improve logistics operations and reduce operating costs for the transportation of cargo and passengers.

Numerical Modeling to Investigate the Aerodynamics of a Boundary-Layer Ingested Transonic Fan

Boundary-layer ingested engines have the potential to offer significantly reduced fuel burn, but the fan stage must be designed to run efficiently with a distorted inflow. It must also be able to withstand unsteady aerodynamic loads resulting from a complex nonuniform flowfield. This paper applies different numerical methods for an improved understanding of the aerodynamic interaction between a transonic fan and inlet distortion. A single-stage transonic tail cone thruster fan was designed using both in-house and commercial tools operating in an inlet distortion flowfield. This paper demonstrates that the relevant metrics required to compute the aerodynamic performance of a fan stage in distorted conditions can be reasonably modeled with a few harmonics using the nonlinear harmonic method in a fraction of time in comparison to a full annulus time marching solution. The nonlinear harmonic method also reduces the computational domain, and hence reduces the solution runtime by an order of magnitude. However, it fails to accurately resolve the wake and potential field transfer across the blade rows due to a limited number of harmonics being applied. A detailed aerodynamic description of the unsteady inflow distortion, the interacting blade-row mechanisms, the flow redistribution upstream of the rotor, the distortion transfer across the different blade rows, and the corresponding aerodynamic losses can be analyzed accurately using only a full annulus time-marching method.

Correspondence distribution over a network in designing public urban passenger transportation tasks

Introduction. The process of planning public transport is divided into a few number of tasks in strategic, tactical and operational levels, which include the development route system, the establishment of traffic intensity along routes, the design of the structure of road transport vehicles, the distribution of the current road transport vehicles along the routes, determining the required amount of the subsidies, etc. Materials and methods. The article presents a multi-criteria mathematical model of transportation design, according to which the tasks have been solved by distributing (limited or unlimited) transport resources between the permissible routes of the transport network in accordance with a variety of efficiency criteria, which can be the subject to appropriate restrictions. The formation acceptable routes on the transport network can be carried out by means of the algorithms developed, for example, in the framework of solving TNDP and TNDFSP tasks. The routes can also be adjusted by experts. Transport demand is set by a matrix of passenger correspondence generated for the entire period of traffic on a weekday, to ensure that all passenger flows along the route network are taken into account, and not only the periods of the greatest traffic intensity. The calculation of the parameters of the transport offer in the process of solving the problems of transportation design is carried out based on the results of the passenger correspondence distribution on the route network (PAP), which is a complex problem unsolved today. The article describes the developed PAP methodology based on a flexible passenger strategy that takes into account the waiting time for transport, the proximity of the route through an empirical model of dividing demand by the length of trips, the preferences of transport modes, the possible redistribution of passenger flows between the stopping points of the network located within a walking distance. Results. The tasks of designing public transport transportation have been formulated, a multi-criteria mathematical model of their solution has been developed. The method of distribution of passenger flows on the route network based on a flexible passenger strategy has been described. The effectiveness of the developed PAP methodology is shown on test calculations, which were carried out using passenger correspondence, an average weekday in October 2019, obtained by processing validations of e-tickets of urban passenger transport in Krasnoyarsk. Discussion and conclusion. The practical implementation of the described methodology for the distribution of passenger flows on the route network using relational database management systems (DBMS) MS SQL Server has been carried out.