Unusual Flow Research Articles

Flow stress behavior, constitutive modeling, processing map and microstructure evolution in hot deformation of Fe-7.1Al-0.7Mn-0.4C-0.3Nb alloy

The automotive industry has experienced rapid growth, with lightweight materials becoming a significant research focus. Among these materials, low-density Fe–Mn–Al–C alloys show promise for this kind of application. To optimize the hot workability parameters of these alloys for practical applications, it is essential to explore the hot deformation behavior of these alloys. In this study, we investigated the hot deformation behavior of the low-density alloy Fe-0.77Mn-7.10Al-0.45C-0.31Nb using hot plane-strain compression tests for several deformation temperatures (850, 950, 1050, and 1150 °C) and nominal strain rates (0.01, 1, and 10 s−1). Unusual flow stress curves were observed for low (0.01 s−1) and intermediate (1 s−1) strain rates, with discontinuous yielding and multiple stress peaks. This high-temperature behavior is associated with non-homogeneous strain partitioning in duplex microstructure (δ-ferrite + γ). Using the Zenner-Hollomon constitutive modeling approach, we estimated the thermal activation energy for hot deformation as 297 kJ/mol from the experimental peak flow stresses. Additionally, processing maps and microstructure correlation analysis revealed that the alloy exhibits good hot workability in the 975–1075 °C temperature range under low and intermediate strain rates (0.01–0.3 s−1). Under these processing conditions, the δ-ferrite microstructure is submitted to dynamic recovery, while the austenitic phase undergoes dynamic recrystallization.

«Другие мигранты» на Дальнем Востоке России, или Поиск советского народа в период нациестроительства на постсоветском пространстве

The article examines a new, not very important from the statistical viewpoint, but extremely unusual flow of migrants from the former republics of the USSR, primarily Central Asian and, to a lesser extent, Transcaucasian. In the recent past a typical migrant in the Far East, as well as in Russia as a whole, can be described as a resident of a small city or village, who is focused on a short-term or cyclical stay in the region for the purpose of earning money and minimally interacting with the host community. However, the new flow of migrants includes residents of large cities who travel to Russia with an intention to integrate. For these types of migrants the usual economic push/pull factors do not play a significant role. The representatives of this group possess sufficiently high qualifications and did not experience any serious economic problems in the country of origin. The motives for their move are rather political in nature, and this is not persecution for dissent or participation in opposition activities, but rather what the authors refer to as the search for the Soviet people. According to the authors’ conclusion, the emergence of this migration flow is associated with the growing process of ethnicization (as a form of nation-building) in the states of the post-Soviet space, which is increasingly becoming less post-Soviet. After the collapse of the Soviet Union, the authorities of the newly independent states pursued an extremely cautious national policy, which was largely explained by the artificial nature of the contemporary borders of these states and their ethnic foundation. The former imperial cities, the previous centers of power, whose population most closely corresponded to the image of the Soviet people, preserved their high status. However, in the recent years the situation has changed. As ethnicization intensifies, accompanied by the ousting of the Soviet, which was equated with the Russian, the “debris” of the Soviet people lose not only their social status, but also the foundation for self-identification. They move to Russia in search of such foundation, with the hope to find confirmation of their own professional and socio-political identity.

Abstract 13419: Transient Coronary Artery to Left Ventricular Fistula With Diastolic Mitral Regurgitation

Introduction: A fistula from a coronary artery to the cardiac chamber is incidentally found in 0.08% to 0.3% of patients undergoing coronary angiography. Case Presentation: A 73-year-old woman with hypertension, diabetes mellitus, chronic renal failure, and nephrosis visited our department due to dyspnea. The patient’s physical examination revealed a blood pressure of 191/109 mmHg and a pulse rate of 77 beats per min. The blood sampling results revealed a plasma brain natriuretic peptide level of 2,001 pg/mL. A 12-lead electrocardiogram showed poor R wave progression in leads V1 to V4. Chest radiography revealed left pleural effusion. Parasternal transthoracic echocardiography showed left ventricular hypertrophy. Left ventricular (LV) ejection fraction was 41%. A pulsed-wave Doppler echocardiography at the mitral inflow showed diastolic mitral regurgitation and a fusion of E and A waves. An unusual myocardial flow was noted in the apical myocardium. It was directed toward the apical surface during systole (Fig. 1a), and directed toward the LV lumen during diastole (Fig. 1b), suggesting coronary artery to LV fistula through sinusoid. Global strain obtained from apical long axis imaging showed myocardial shortening continued to diastole, suggesting post-systolic shortening (PSS). After treatment for hypertension, both of myocardial flow and diastolic MR disappeared. A longitudinal global strain imaging revealed disappearance of PSS. Conclusion: This is a rare case of diastolic MR due to PSS at the fistula from the coronary artery to the left ventricle.

The flow of anisotropic nanoparticles in solution and in blood.

The alignment of anisotropic nanoparticles in flow has been used for a range of applications such as the preparation of strong fibres and the assembly of in-plane aligned 1D-nanoobjects that are used for electronic devices, sensors, energy and biological application. Important is also the flow behaviour of nanoparticles that were designed for nanomedical applications such as drug delivery. It is widely observed that non-spherical nanoparticles have longer circulation times and a more favourable biodistribution. To be able to understand this behaviour, researchers have turned to analyzing the flow of non-spherical nanoparticles in the blood stream. In this review, an overview of microfluidic techniques that are used to monitor the alignment of anisotropic nanoparticles in solution will be provided, which includes analysis by small angle X-ray scattering (SAXS) and polarized light microscopy. The flow of these nanoparticles in blood is then discussed as the presence of red blood cells causes margination of some nanoparticles. Using fluorescence microscopy, the extent of margination can be identified, which coincides with the ability of nanoparticles to adhere to the cells grown along the wall. While these studies are mainly carried out in vitro using blood, initial investigations in vivo were able to confirm the unusual flow of anisotropic nanoparticles.

Unusual step-like stress flow behavior and mechanisms of a 1.3 GPa grade medium-Mn steel with 51.2 % ductility

A Fe-8.9Mn-1.59Si-1.0Al-0.25C medium-Mn steel have achieved a superior combination of strength and ductility, i.e., the product of strength and elongation (PSE) of 66.5 GPa%. Meanwhile, an unusual step-like stress–strain curve due to heterogeneous deformation bands including Lüders band and multiple Portevin–Le Chatelier (PLC) bands was investigated systematacially. The repeated heterogeneous deformation is due to a combination of extrinsic and intrinsic factors. The former refers a small stress concentration near the grip ends of the tensile sample, and the latter is associated with low density of initial mobile dislocations, limited capacity of mobile dislocation multiplication and the presence of meta-stable austenite. As for meta-stable austenite, stress-assisted martensite transformation (SAMT) was confirmed experimentally, which will facilitate strain concentration and the starting of heterogeneous deformation. Moreover, before strain-induced martensite transformation (SIMT), it is the plastic deformation of austenite grains through the slip of partial dislocation and stacking faults (SFs) that contributes to a larger Lüders strain. Finally, we propose that whether it is possible to make the heterogeneous deformation to be a positive side for certain working conditions, which may open new doors for the application of medium-Mn steels. We will continue to do some exploratory studies in this direction next.

When good signatures go bad: Applying hydrologic signatures in large sample studies

AbstractHydrologic signatures are quantitative metrics that describe streamflow statistics and dynamics. Signatures have many applications, including assessing habitat suitability and hydrologic alteration, calibrating and evaluating hydrologic models, defining similarity between watersheds and investigating watershed processes. Increasingly, signatures are being used in large sample studies to guide flow management and modelling at continental scales. Using signatures in studies involving 1000s of watersheds brings new challenges as it becomes impractical to examine signature parameters and behaviour in each watershed. For example, we might wish to check that signatures describing flood event characteristics have correctly identified event periods, that signature values have not been biassed by data errors, or that human and natural influences on signature values have been correctly interpreted. In this commentary, we draw from our collective experience to present case studies where naïve application of signatures fails to correctly identify streamflow dynamics. These include unusual precipitation or flow regimes, data quality issues, and signature use in human‐influenced watersheds. We conclude by providing guidance and recommendations on applying signatures in large sample studies.

Initial observation of the urodynamic pressure flow study — characteristics of bladder-neck or prostate median lobe dynamics during micturition

Purpose:We present our observations of a urodynamic pressure flow study graph pattern that may be associated with bladder neck hypertrophy or prostate median lobe enlargement. Materials and Methods:We report 23 male patients with signs and symptoms of lower urinary tract dysfunction who underwent urodynamic testing with pressure flow study analysis. We recognized an unusual pressure flow plot curve and found that these patients had cystoscopic evidence for bladder neck hypertrophy or cystoscopic or ultrasound evidence for prostate median lobe enlargement. Results:The patients here demonstrated showed a pattern of increasing detrusor pressure on the pressure flow study — graph phase after maximum of flowrate, where a decreasing pressure pattern is expected. We contemplated that his pattern may show how bladder outflow dynamics is affected by the anatomical features of these patients and how patients may have symptoms of LUT dysfunction or significant residual urine despite a relatively good maximum flow rate. Conclusion:We present a not previously described variation of the pressure flow study graph pattern common in men with prostatic hyperplasia, in a series of patients with median lobe prostatic hyperplasia and or hypertrophy of the bladder neck.

Igneous Rock Associations 29. The Nenana Magnetitite Lava Flow, Alaska Range, Alaska

Magnetitite deposits like El Laco (Chile) are rare and have controversial origins. An unusual magnetitite lava flow overlying a rhyolite unit occurs in the north-central Alaska Range and originally covered ~ 750 km2 of the Miocene Nenana basin. Dating of the rhyolite and relationships between the magnetitite and sedimentary rocks indicate that both are of Late Miocene age. The magnetitite flow is mainly magnetite with some post-eruptive alteration to hematite. Both the rhyolite flow and the magnetitite flow are vesicular, but the magnetitite flow also has small, millimetre-scale columnar jointing. The vesicular zones in the magnetitite flow grade into massive rock on the scale of a thin section, suggesting a degassing lava origin. Samples of the magnetitite flow contain between 12 and 26 wt.% SiO2 and between 45 and 75 wt.% FeO. Rare earth elements (REE) and trace elements from the magnetitite and rhyolite have similar patterns but with lesser abundance in the magnetitite. Both the rhyolite and the magnetitite have light-REE-enriched REE profiles with negative Eu anomalies. Electron microscopic analysis shows that most of the silica and trace element content of the magnetitite flow comes from very finely disseminated silicate minerals and glass in the magnetite. This suggests that the magnetitite was derived from a magma that had undergone unmixing into a silica-rich phase and an iron-rich phase prior to its eruption. Fractures and vesicles within the magnetitite flow contain minor rhyolitic glass and minerals suggesting that the rhyolite magma invaded columnar joints in the solidified magnetitite flow, and is a subvolcanic sill-like body at the studied locality. The magnetitite flow erupted prior to the emplacement of the rhyolite, which may be extrusive on a regional scale. The features of the Nenana magnetitite, and its geological relationships, are consistent with genetic models that invoke unmixing of magma into immiscible Fe-rich and Si-rich liquids during ascent.

Unusual recent prolonged low flow in the Moqu River, northeastern Tibetan Plateau, inferred from tree-ring width variations

The runoff of Moqu river in Zoige, one of most important water conservation ecological function areas in the upper reaches of the Yellow River, located in the north-east of the Tibetan Plateau, is highly sensitive to climate change. However, the current understanding of the long-term changes in the hydrology of this rives is still fragmentary. In this study, we created a regional tree-ring width chronology from two sample sites in Moqu River Basin and analysed the relationships between tree-ring width, climate, and runoff. We found significant positive correlations between tree-ring width and runoff in multiple months, the highest correlation coefficient occurred with annual runoff from previous July to current June (r = 0.617, 1981–2013). Based on this highly significant (p < 0.01) relationship, we reconstructed runoff variations of Moqu River for the period 1672 to 2019. The reconstructed runoff showed unusual prolonged and frequent low flow periods in recent decades. We found that the continuous low precipitation and the high temperature in the context of global warming are the main reasons for the abnormal runoff in recent decades. We assume that a weakening of the Indian summer monsoon (ISM) circulation system may be the key large-scale factor that caused the unusually prolonged low flow. With global warming, the weakening of ISM intensity leads to reduced water vapor transport from the tropical Indian Ocean to High Asia, resulting in less precipitation and low runoff events in Zoige. Our reconstruction improves the understanding of regional runoff variability over multiple timescales, and also provides a scientific basis for the protection, development, and utilization of water resources related to ongoing global warming.

Unusual Water Flow in Ultra-Tight Porous Media: Integration of Profession and Innovation

Hydraulic fracturing is an effective method for stimulating reservoirs, making the economic development of ultra-tight shale gas and coalbed methane reservoirs possible. These formations are rich in nanopores, in which the fracturing fluid, such as fresh water, the flow, and the behavior of this flow differ significantly from those described in the classic Navier-Stokes formula. In bulk space, the interaction force exerted by the solid phase can be ignored, but the solid–fluid interaction plays a dominant role in nanoconfinement spaces in which the pore size is comparable to the molecular diameter. Nanoconfined water molecules tend to approach the water-wet pore surface, enhancing the water viscosity, which is a key parameter affecting the water flow capacity. Conversely, water molecules tend to stay in the middle of nanopores when subjected to a hydrophobic surface, leading to a decrease in viscosity. Thus, nanoconfined water viscosity is a function of the strength of the surface–fluid interaction, rather than a constant parameter, in classic theory. However, the influence of varying the viscosity on the nanoscale water flow behavior is still not fully understood. In this research, we incorporate wettability-dependent viscosity into a pore network modeling framework for stable flow for the first time. Our results show that: (a) the increase in viscosity under hydrophilic nanoconfinement could reduce the water flow capacity by as much as 11.3%; (b) the boundary slip is the primary mechanism for boosting the water flow in hydrophobic nanopores, as opposed to the slight enhancement contributed by a viscosity decline; and (c) water flow characterization in nanoscale porous media must consider both the pore size and surface wettability. Revealing the varying viscosity of water flow confined in nanopores can advance our microscopic understanding of water behavior and lay a solid theoretical foundation for fracturing-water invasion or flowback simulation.

Situation Awareness-Oriented Dashboard in ICUs in Support of Resource Management in Time of Pandemics.

In a pediatric intensive care unit (PICU) of 32 beds, clinicians manage resources 24 hours a day, 7 days a week, from a large-screen dashboard implemented in 2017. This resource management dashboard efficiently replaces the handwriting information displayed on a whiteboard, offering a synthetic view of the bed's layout and specific information on staff and equipment at bedside. However, in 2020 when COVID-19 hit, the resource management dashboard showed several limitations. Mainly, its visualization offered to the clinicians limited situation awareness (SA) to perceive, understand and predict the impacts on resource management and decision-making of an unusual flow of patients affected by the most severe form of coronavirus. To identify the SA requirements during a pandemic, we conducted goal-oriented interviews with 11 clinicians working in ICUs. The result is the design of an SA-oriented dashboard with 22 key indicators (KIs): 1 on the admission capacity, 15 at bedside and 6 displayed as statistics in the central area. We conducted a usability evaluation of the SA-oriented dashboard compared to the resource management dashboard with 6 clinicians. The results showed five usability improvements of the SA-oriented dashboard and five limitations. Our work contributes to new knowledge on the clinicians' SA requirements to support resource management and decision-making in ICUs in times of pandemics.

Abstract 15341: Persistent Fifth Arch as an Aortopulmonary Connection in a Case of Tetralogy of Fallot

Persistent fifth aortic arch is a heterogeneous vascular anomaly with variable anatomical presentations and physiological consequences. This unusual embryological remnant represents a management challenge, particularly in critical right sided obstructive heart lesions where accurate delineation of sources of pulmonary blood flow is essential. This is a newborn 2 kg premature male born at 34 weeks of gestation with prenatally diagnosed tetralogy of Fallot. Post-natal echocardiogram confirmed diagnosis with evidence of moderate-to-severe pulmonary stenosis, restrictive ventricular septal defect, and a right aortic arch. CT angiogram ordered to delineate the head and neck vessel anatomy showed an exceedingly rare finding of an isolated connection of the left subclavian artery (LSCA) to the main pulmonary artery (MPA) via a left sided ductus arteriosus. Blood flowed from the common carotid arteries, through the circle of Willis, and, in a retrograde direction, into the LSCA. Prostaglandin E was initiated due to concern for ductal dependent pulmonary blood flow, but after clinical observation it was discontinued without subsequent onset of cyanosis. Repeat echocardiograms were reassuring in showing persistence of the left ductus arteriosus. The patient was discharged home at 5 weeks-old and at 4 months-old he underwent complete repair after developing progressive desaturations and worsening sub-valvar and valvar pulmonary stenosis. The surgical repair included ventricular septal defect closure, transannular patch, extensive right ventricular myomectomy and reimplantation of LSCA onto the left common carotid artery. The post-operative course was uncomplicated. This rare case of persistent fifth aortic arch with retrograde flow to the LSCA demonstrates the complementary roles of noninvasive imaging modalities in guiding medical therapy and surgical management. This unusual blood flow pattern and initial concern for duct dependent pulmonary blood flow complicated early management, but a conservative approach with repeat imaging allowed for eventual complete repair.

Abstract 11183: Unusual Color Flow Leads to Diagnosis of Unroofed Coronary Atrial Septal Defect

Introduction: Unroofed coronary sinus-atrial septal defect (CS-ASD) is a very rare anomaly that may be easily missed by transthoracic echocardiography. Case: A 59 year old woman presented with chronic and progressively worsening dyspnea. TTE demonstrated preserved ejection fraction, right ventricular and atrial dilation, and elevated pulmonary artery pressures. Color doppler demonstrated a persistent diastolic flow at the interatrial septum immediately above the plane of the tricuspid valve, suspicious for atrial septal defect (Fig. 1). Such aberrant flow was not observed on multiple prior TTEs. Decision-Making: Given the uncertain nature of the abnormal color flow seen, further imaging was pursued with a gated Cardiac CT with contrast. CT imaging demonstrated a dilated coronary sinus with a communication between the roof of the terminal coronary sinus and the left atrium, consistent with an unroofed coronary sinus-atrial septal defect (CS-ASD) (Fig. 2). There was no evidence of a persistent left superior vena cava. Cardiac MRI demonstrated a significant right to left shunt with a Qp/Qs of 1.53 using phase contrast imaging. Discussion: CS-ASD is a very rare cardiac anomaly and is the most uncommon type of ASD (&lt;1%), often associated with a persistent left superior vena cava. Given the posterior nature of the defect, it is often missed on TTE. In our case, suspicion was raised by a small abnormal color jet of flow coming from the interatrial septum. Cardiac CT is an excellent diagnostic modality for CS-ASD given its excellent visuospatial capabilities and ability to evaluate pulmonary veins. Cardiac MRI may serve as a helpful adjunct in quantification of shunt flow.

MATHEMATICAL MODELING OF THERMO-SOLUTAL TRANSPORT IN PULSATING FLOW IN THE HYDROCEPHALUS

Cerebrospinal fluid (CSF) is a symmetric flow transport that surrounds brain and central nervous system (CNS). Hydrocephalus is an asymmetric and unusual cerebrospinal fluid flow in the lateral ventricular portions. This dumping impact enhances the elasticity over the ventricle wall. Henceforth, compression change influences the force of brain tissues. Mathematical models of transport in the hydrocephalus, which constitutes an excess of fluid in the cavities deep within the brain, enable a better perspective of how this condition contributes to disturbances of the CSF flow in the hollow places of the brain. Recent approaches to brain phase spaces reinforce the foremost role of symmetries and energy requirements in the assessment of nervous activity. Thermophysical and mass transfer effects are therefore addressed in this paper to quantify the transport phenomena in pulsatile hydrocephalus CSF transport with oscillating pressure variations that characterize general neurological activity and transitions from one functional state to another. A new mathematical model is developed which includes porous media drag for brain tissue and solutal diffusion (concentration) effects. A classical Laplace transform method is deployed to solve the dimensionless model derived with appropriate boundary conditions. The analysis reveals that with increasing permeability of the subarachnoid space, the CSF velocity is increased, and a significant fluid flux enhancement arises through the brain parenchyma as the pressure of the fluid escalates drastically due to hydrocephalus disorder. Stronger thermal buoyancy (Grashof number) also results in deceleration in the flow. CSF temperature is reduced with progression in time. Particle (e.g. ion) concentration is suppressed with increasing Schmidt number. As heat conduction parameter increases, there is a substantial depletion in CSF velocity with respect to time. Increasing Womersley parameter displaces the CSF velocity peaks and troughs. The present effects are beneficial in determining the thermo-fluidic transport mechanism of the pathological disorder hydrocephalus. Also, the present results are compared with those clinical studies for some cases. We have confirmed that our validity provides a decent justification with the neurological studies.

Answer: An unusual flow from the coronary sinus

Answer: An unusual flow from the coronary sinus

Question: An unusual flow from the coronary sinus

Question: An unusual flow from the coronary sinus

Multiple hysteresis effects and their destabilization mechanism in the enclosed mixed convection enclosure with three representative aspect ratios

Mixed convection in the lid-driven cavity model widely represented real engineering applications, especially electronic cooling and wind across buildings. In past decades, avalanche experiments and numerical calculations have been done on the lid-driven cavity model. Unfortunately, one unusual flow behavior in the cavity mixed convections—multiple steady solutions, i.e., identical boundary conditions and governing parameters whereas different initial conditions or loading perturbations may lead to two or more flow states, and it was hardly investigated. Multiple steady enclosure flow behaviors essentially complicate the convective transport of heat and air, which has been vividly analyzed by streamlines, heatlines and isotherms. In the present work, the flow mechanisms and evolution driven by mixed convections in lid-driven cavities for multiple aspect ratios will be investigated through the numerical methodology of computational fluid dynamics. The effects of dimensionless parameter (Grashof number, Reynolds number, and Richardson number) on multiple flow motions have been disclosed, regarding of hysteresis effect and their destabilization mechanism. Investigations on these complicated flow motions essentially facilitate the optimization of engineering flows similar to lid driven enclosures, whatever mechanical cooling of electronics, or wind across street canyons.

Partial regularity of the heat flow of half-harmonic maps and applications to harmonic maps with free boundary

We introduce a heat flow associated to half-harmonic maps, which have been introduced by Da Lio and Rivière. Those maps exhibit integrability by compensation in one space dimension and are related to harmonic maps with free boundary. We consider a new flow associated to these harmonic maps with free boundary which is actually motivated by a rather unusual heat flow for half-harmonic maps. We construct then weak solutions and prove their partial regularity in space and time via a Ginzburg-Landau approximation. The present paper complements the study initiated by Struwe and Chen-Lin.

Flood monitoring and community based flash flood warning system for Nasiri River, West Seram, Maluku

ABSTRACT On 1st of August 2012, two successive flash floods hit Nasiri hamlet in Maluku archipelago, Indonesia. The floods destroyed 61 houses and swept some of them down into the sea. A monitoring and community-based early warning system (MCBEWS) was developed 2 years later. This paper presents the approach, development, and implementation of the system. There are two components, namely community capacity-building and the establishment of telemetric monitoring. The flood warning system considers two causes: extreme rainfall and landslide dam breaks. Raising awareness, workshops, training, and disaster organisation establishment appeared to effectively increase flood disaster preparedness capacity and community commitment. The adoption of a rainfall depth vs. intensity chart method for issuing flood warnings seems to be promising. The presence of an unusual flow reduction in the record during extreme rainfall indicates damming at the upstream of the record station due to landslides. Possible landslide dams near the downstream to the middle reaches might provide dangerous high peak discharge flash floods with short warning times.

A decade of cold Eurasian winters reconstructed for the early 19th century

Annual-to-decadal variability in northern midlatitude temperature is dominated by the cold season. However, climate field reconstructions are often based on tree rings that represent the growing season. Here we present cold-season (October-to-May average) temperature field reconstructions for the northern midlatitudes, 1701-1905, based on extensive phenological data (freezing and thawing dates of rivers, plant observations). Northern midlatitude land temperatures exceeded the variability range of the 18th and 19th centuries by the 1940s, to which recent warming has added another 1.5 °C. A sequences of cold winters 1808/9-1815/6 can be explained by two volcanic eruptions and unusual atmospheric flow. Weak southwesterlies over Western Europe in early winter caused low Eurasian temperatures, which persisted into spring even though the flow pattern did not. Twentieth century data and model simulations confirm this persistence and point to increased snow cover as a cause, consistent with sparse information on Eurasian snow in the early 19th century.