Front Corner Research Articles

Forced Wetting of Shear-Thinning Fluids in Confined Capillaries.

Dynamic wetting in confined spaces is pivotal for the functional efficiency of biological organisms and offers significant potential for optimizing microdevices. The fluids encountered in such scenarios often exhibit shear-thinning behavior, which gives rise to complex interfacial phenomena. Here, we present an intriguing wetting phenomenon for shear-thinning fluids in confined capillary spaces. The employed shear-thinning fluids, carboxymethyl cellulose aqueous solutions with mass fractions of 0.5, 1.0, and 1.5 wt %, exhibit an intermediate state between ideal viscoelastic liquids, viscoelastic solids, and gel-like properties. We elucidate the geometric effect on its capillary wetting behavior, demonstrating that distortion of the moving contact line alters flow dynamics near the front corner, modifying the viscous resistance. This intricate interplay between the modified viscous resistance and the driving force results in a novel dynamic equilibrium distinct from that in Newtonian fluids. We further reveal that the viscous resistance in confined capillaries is controlled by both the morphology of the moving contact line and the shear-thinning exponent, particularly within the range of 0.7 to 1. This novel mechanism provides a pathway for manipulating the wetting dynamics of complex fluids in confined spaces.

Design Exploration of a Novel Fairing to Control Flow Separation at the Front Corner of a Bluff Body

Design Exploration of a Novel Fairing to Control Flow Separation at the Front Corner of a Bluff Body

Joint Vehicle Path Planning for Interruptible 1-D Snake-like Platoons and 2D Flocks in Lane-free Traffic

This article presents a joint trajectory optimization algorithm for connected and automated vehicles forming 1-D snake-like interruptible platoons or 2-D deformable and interruptible flocks in a lane-free traffic environment on highways. A double double-integrator model is employed for the longitudinal and lateral movements of each vehicle. An appropriately defined Euclidian distance to track the front vehicle is utilized to establish and operate a 1-D platoon of vehicles, at selectable distance from each other. The Euclidian distance is used as a soft constraint, which allows for platoons to divide, if required to avoid obstacles, and reunite eventually. Moreover, the distance from a selectable frame (e.g. a triangle) are employed as soft constraints to form and maintain a 2-D deformable and interruptible flock of vehicles. The flock may feature a leader vehicle, e.g. at the front corner of a triangle. A collision avoidance function considering constant time-gaps or space-gaps, is used based on the elliptical distance between each two vehicles or external obstacles. A joint multi-objective function is formulated and minimized using an efficient feasible direction algorithm with respect to constant and state-dependent bounds on control inputs, including road boundary constraints. This leads to creating a flexible platoon or deformable flock accounting for low fuel consumption, passenger convenience, collision avoidance, achievement of desired speed and prevention of infeasible maneuvers. Challenging scenarios are examined on a lane-free straight motorway stretch, producing promising results for further exploration of the proposed concepts within an MPC (model predictive control) framework.

Punching tests on edge slab-column connections with refined measurements

Due to the significant shear forces developing around columns and the potential brittle failure associated, the punching capacity of flat slabs is the main concern at ultimate limit state. An effective way to understand the behaviour of slab-column connections has typically been by testing isolated specimens in the laboratory. While there exist many slab-column connection types in actual slabs, most research efforts have focused on the punching resistance at internal columns. Specifically, edge connections appear largely underrepresented in the literature when the number of existing tests is compared to their importance in typical building floor configurations. Furthermore, the favourable effect of slab continuity is generally neglected in this type of tests. This paper presents the results of an experimental campaign on two edge slab-column connections: one had no shear reinforcement, while the other had a large amount of shear reinforcement to evaluate maximum punching. A novel test setup was conceived to apply representative boundary conditions of actual continuous slabs, introducing moment continuity perpendicularly to the slab free edge. Refined measurement techniques were extensively used, monitoring the visible slab faces using Digital Image Correlation, and instrumenting the flexural and shear reinforcement with distributed fibre-optic sensors. The failure of the slab-column connection without shear reinforcement was triggered in the region of shear stress concentrations and propagated around the column thereafter. Well-anchored vertical legs of flexural reinforcement at the free face induced a smeared-like shear crack pattern. In the shear-reinforced slab-column connection, an initial crushing of the concrete at the column front corners was followed by the formation of a local yield line along the slab axis. In addition to the enhancement of the resistance and rotation capacity, the shear studs also served for increasing the moment redistribution capacity of the system. The experimental results are compared to different codes of practice, showing that improvements are needed to better assess the resistance of edge columns.

The Other Mrs. Clemm

The Other Mrs. Clemm

경복궁 전각의 온돌방 평면과 구조특성

Purpose: This study is a study of Gyeongbokgung Ondol, Korea"s representative Jeonggung Palace. Therefore, the purpose of this study is to study the basic architectural characteristics of the Ondol of Gyeongbokgung Palace, which is the largest and most advanced of Korean palaces. Method: This study classified the existing pavilions in Gyeongbokgung Palace into each area according to their functions or uses, studied the current status and architectural characteristics of ondol facilities for the pavilions in which ondol is installed, and studied structures such as ondol and Agungi and chimneys. Result: As a result of the research, we compared the size of the ondol for each corner of Gyeongbokgung Palace, and the largest of the ondols was Gangnyeongjeon, which is 209.93㎡, and the smallest, is Yangildang, which is 21.11㎡. The total area of the ondol installed in the front corner is 3,323.63㎡, and if you look at the average, it can be seen that 39.3% of the total area of the front corner is made of ondol.

Enhancing the Fatigue of Mechanical Systems Such as Dispensers Entrenched on Generalized Life-Stress Models and Sample Sizes

To lengthen the life of a mechanical system, parametric accelerated life testing (ALT) is recommended as an established way to help identify structural imperfections and reduce fatigue-related failures. It involves (1) a parametric ALT scheme, (2) fatigue design, (3) ALTs with alterations, and (4) an estimate of whether design(s) achieve the BX lifetime. The application of a quantum-transported time to failure prototype and a sample size expression is also suggested. The improvements in the reliability of a water dispenser made of stainless steel or polypropylene (PP) in a bottom-mount domestic refrigerator was used as a case study. In the first ALT, the hinge and front corner of the dispensing system was cracked. The water dispenser lever was altered by increasing the thickness of its ribs and fillets. In the second ALT, the altered dispensing lever system cracked because there was an insufficient thickness in its front corner for impact loading. The critical design factors for improving reliability were corner fillet rounding and rib thickening in a dispenser lever. As there were no difficulties in the third ALT, the dispenser life was verified to have a B1 life of 10 years.

Numerical Modeling of Solitary Wave-Induced Flow and Scour around a Square Onshore Structure

Waves or tsunamis in the onshore area could induce severe scour at the structure foundations, threatening the stability of the structure. This paper presents a numerical study of the solitary wave-induced flow and scour around a square onshore structure. A CFD model coupled with hydrodynamic and sediment transport models is first validated through a large-scale laboratory experiment, which shows that the model can well reproduce the flow and scour characteristics. Subsequently, based on the reliable numerical results, the flow field and scour development during wave inundation of the structure are explored. It is found that the development of the simulated scour depth is faster at the early stage compared to that in the experimental result. The results also show that the scour starts at the front corner of the structure, which is also the position of the maximum scour depth. The scour develops rapidly at the early stage and is almost completed in the first half of the wave period. In addition, the results demonstrate that bed scouring increases the wave force on the structure due to the increase in the flow velocity near the bed, which needs to be considered, especially in the shallow-water scour scenario. Finally, a simplified prediction equation is proposed for the temporal development of the scour depth.

Physical mechanisms behind the extreme wind pressures on two tandem square cylinders

The extreme wind pressure might lead to local or overall structural failures. The physical mechanisms behind extreme pressures on two tandem square cylinders are investigated using large-eddy simulation at a Reynolds number of 8 × 104. The spacing ratio P/B ranges from 1.1 to 5 (P: cylinders’ center distance; B: side length). The aerodynamic coefficients, flow patterns, mean and fluctuating pressure coefficients, pressure skewness and kurtosis, and instantaneous flow structures are analyzed. The extreme negative pressures are induced by the intermittent appearance of strong vortices attached to the cylinder surfaces. “Gap vortex” and “wall vortex” are responsible for the extreme pressure at the gap-sides of two cylinders in the single mode (1 < P/B < 2). “Corner vortex” would cause extreme negative pressure near the front corners of the upstream cylinder and the rear corners of both cylinders at most spacings. At the reattached (2 ≤ P/B < 4) and binary (4 ≤ P/B ≤ 5) modes, the Karman vortex released from the rear corner of the downstream cylinders leads to extreme pressure on the rear surface. As the spacing increases, the extreme pressure on non-Gaussian-pressure regions is generally strengthened but the three-dimensionality in vortex structures and instantaneous pressure distributions roughly declines.

Relationship of pedestrian crash types and passenger vehicle types

Introduction: This is the first known study that examines the association between common pedestrian crash types and passenger vehicle types. Method: The analysis included single-vehicle, single-pedestrian crashes from two data sets: North Carolina state crash data and the Fatality Analysis Reporting System (FARS). We performed separate multinomial logistic regression analyses of major pedestrian crash types occurring at or near intersections and at nonintersections. Results: At or near intersections, minivans, large vans, pickups, and SUVs (collectively known as light truck vehicles, or LTVs) were more likely than cars to be involved in crossing-roadway–vehicle-turning-left crashes versus crossing-roadway–vehicle-not-turning crashes. LTVs were also more likely involved in fatal crossing-roadway–vehicle-turning-right crashes at or near intersections versus crossing-roadway–vehicle-not-turning crashes when compared with cars. At nonintersections, LTVs were associated with increased odds of walking-along-roadway crashes relative to crossing-roadway–vehicle-not-turning crashes when compared with cars. Conclusions: LTVs were more likely to be involved in certain pedestrian crash types, implying a potentially problematic visibility of pedestrians near the front corners of these vehicles. Practical applications: More research is needed to examine A-pillar blind zones by vehicle type. If it is found that LTVs have larger blind zones, automakers should consider ways to design the A-pillars of these vehicles to minimize blind zones while maintaining pillar strength. Doing this could improve pedestrian safety around these increasingly popular larger vehicles.

Analysis and control of the front corner flow of commercial vehicles

Analysis and control of the front corner flow of commercial vehicles

Flow and Heat Transfer Performance of Channels with ‎‎45 Degree Ribs in Staggered Array‎

The cooling efficiency of blade is growing demand with increasing turbine inlet temperature in gas ‎turbine development. Ribs used in cooling channels is a common cooling structure, therefore, many ‎configurations were studied by previous literatures, including angle, spacing, shape etc. However, there ‎are less research about the dislocation ribs structure. In this paper, the 45-deg parallel ribs, crossed ribs ‎and dislocation ribs were investigated by numerical simulation, in order to reveal the heat transfer ‎performance and flow mechanism. Refer to the experiment, SST k-ω model was applied in steady ‎simulation, at Re from 20000 to 50000. Due to the angled ribs can induce the secondary flow and ‎generate small helical vortices at front corner, heat transfer performance was elevated. The large rotating ‎vortices influenced by the ribs arrangement occupy the center channel, thence the dislocation caused ‎different flow and heat transfer results. The results shown that parallel rib has higher heat transfer ‎enhancement than crossed ribs, but pressure loss possess considerable level. At Re=21587, the averaged ‎turbulent kinetic energy of Case2.2 with dislocation ribs is 22.4% lower than parallel ribs. The all 45-deg ‎crossed ribs present higher level of overall thermal performance, and Case2.2 is optimal for the range of ‎Re investigated‎.

Flow around square-like cylinders with corner and side modifications

Shape modification effectively reduces the wind loading and wind-induced vibrations of slender structures. Large-eddy simulation is used to investigate the flow around multiple square-like cylinders at a Reynolds number of 22,000. Based on a standard square cylinder, six square-like cylinders are simulated with sharp/rounded corners and straight/concave/convex sides. The combination of rounded corners and convex sides enables the best aerodynamic performance. Furthermore, a parametric study on the round-convex cylinder is conducted considering a fixed corner radius and various side curvatures B/K (B: nominal side length; K: side radius). The results show that both the aerodynamic characteristics of and the flow features around the cylinder change considerably with varying B/K and that three distinct flow regimes are observed. In Stage I (0 ≤ B/K ≤ 0.71), the flow separates at the front corners, and the aerodynamic forces decrease gradually. In Stage II (0.71 < B/K < 1.00), the shear layer separating at the front corner-side region reattaches to the lateral sides. The fluctuating coefficients rise at B/K = 0.74; thereafter, the aerodynamic forces drop and are minimized at B/K = 1.00. In Stage III (1.00 ≤ B/K ≤ 1.77), flow separates at the lateral sides, and the aerodynamic forces recover gradually.

LES study of windward-face-mounted-ribs’ effects on flow fields and aerodynamic forces on a square cylinder

Building-façade-mounted appurtenances are found to be effective for reducing wind loads on high-rise buildings. In this study, large eddy simulations (LES) are performed to investigate the effects of windward-face-mounted ribs on aerodynamic forces acting on a square cylinder of width D under smooth flow. The flow fields, wind pressure distributions and aerodynamic forces on different models are examined to clarify the underlying mechanism of the mitigation of wind load caused by vertical ribs. It is found that local recirculation forms in the front corner region, which greatly influences the flow separation and modifies the behavior of shear-layer flow. Three typical flow patterns around cylinders with different rib depths d are identified: full separation flow (0<d/D ≤ 0.105), periodic attachment flow (0.105<d/D ≤ 0.12), and steady attachment flow (d/D > 0.12). The wake vortex structures, vortex shedding frequency and wind pressure distribution are significantly different under these three flow patterns. The flow field changes result in remarkable mitigation of mean drag C‾d and fluctuating lift C'l. Optimal combinations of location b and depth d of ribs are also investigated. In these optimal cases, the shear layer first separates from the rib's leading edge and then passes by the cylinder's leading edge. The maximum reduction ratios of C‾d and C'l reach 50% and 86%, respectively, when d/D = 0.12 and b/D = 0.10. An empirical configuration equation of the vertical ribs is finally proposed by fitting results of optimal combinations.

Pedestrian Impact Analysis of Side-Swipe and Minor Overlap Conditions

&lt;div class="section abstract"&gt;&lt;div class="htmlview paragraph"&gt;This paper presents analyses of 21real-world pedestrian versus vehicle collisions that were video recorded from vehicle dash mounted cameras or surveillance cameras. These pedestrian collisions have in common an impact configuration where the pedestrian was at the side of the vehicle, or with a minimal overlap at the front corner of the vehicle (less than one foot overlap). These impacts would not be considered frontal impacts [&lt;span class="xref"&gt;1&lt;/span&gt;], and as a result determining the speed of the vehicle by existing methods that incorporate the pedestrian travel distance post impact, or by assessing vehicle damage, would not be applicable. This research examined the specific interaction of non-frontal, side-impact, and minimal overlap pedestrian impact configurations to assess the relationship between the speed of the vehicle at impact, the motion of the pedestrian before and after impact, and the associated post impact travel distances. The21analyzed events are categorized according to the type of impact configuration (side-impact or minimal corner overlap). The vehicle speed was also determined from the video, and the relationship between the vehicle speed and pedestrian distance traveled post impact are summarized.&lt;/div&gt;&lt;/div&gt;

Effect of aerodynamic modifications on the surface pressure patterns of buildings using proper orthogonal decomposition

This study analyzed the pressure patterns and local pressure of tall buildings with corner modifications (recessed and chamfered corner) using wind tunnel tests and proper orthogonal decomposition (POD). POD can distinguish pressure patterns by POD mode and more dominant pressure patterns can be found according to the order of POD modes. Results show that both recessed and chamfered corners effectively reduced wind-induced responses. Additionally, unique effects were observed depending on the ratio of corner modification. Tall building models with recessed corners showed fluctuations in the approaching wind flow in the first POD mode and vortex shedding effects in the second POD mode. With large corner modification, energy distribution became small in the first POD mode, which shows that the effect of the first POD mode reduced. Among building models with chamfered corners, vortex shedding effects appeared in the first POD mode, except for the model with the highest ratio of corner modifications. The POD confirmed that both recessed and chamfered corners play a role in reducing vortex shedding effects, and the normalized power spectral density peak value of modes showing vortex shedding was smaller than that of the building model with a square section. Vortex shedding effects were observed on the front corner surfaces resulting from corner modification, as with the side surface. For buildings with recessed corners, the local pressure on corner surfaces was larger than that of side surfaces. Moreover, the average wind pressure was effectively reduced to 88.42% and 92.40% in RE1 on the windward surface and CH1 on the side surface, respectively.

Effects of Air Outlet Position and Air Speed on Airflow and Dust Field Distributions

To meet the actual demands on ventilation and dust removal in mine heading faces and to reduce the potential safety threats and pollution risks of dust, this study investigates the migration and distribution trends of airflow and dust fields at different air outlet positions and air speeds under scenarios using forced ventilation and long-forced-short-exhaust ventilation techniques at the heading face under continuous mining operation, which is accomplished in the engineering context of Xiaobaodang Coal Mine by a combination of two-phase flow analysis and finite element simulation. As the results reveal, the return air speeds exhibit a “rising-falling-stable” trend at different air outlet positions and inlet air speeds. Appropriate increase of inlet air speed is effective in covering the front corner area and in improving the dust distribution in the roadway. Dust concentration on the return air side is markedly higher than on the air duct side, with distribution primarily in the front section. In the case of forced ventilation for the roadway having a large cross-sectional area of 22 m2, reasonable dust distribution on the return air side can be ensured when the air duct outlet is 10 m away from the front and the inlet air speed is 11 m/s. In the case of long-forced-short-exhaust ventilation, reasonable settings are a 15 m distance of air duct outlet from the front and a 9 m/s speed of inlet air.

ИСТОРИЯ СОЗДАНИЯ И ФУНКЦИОНИРОВАНИЯ ИСТОРИКО-КРАЕВЕДЧЕСКОЙ ЭКСПОЗИЦИИ «ПО РЕКЕ ВРЕМЕНИ» В МУЗЕЕ Г. СЕВЕРСКА

The Exhibition Hall Museum of Seversk was opened on December 24, 1987 as an exhibition hall. In the first years of its existence, it hosted temporary exhibitions from abroad, central museums of the Soviet Union, as well as exhibitions of local artists and the Children’s Art School. In the early 1990s, the government ceased to financially support traveling exhibitions. The museum faced the problem of how to fill its space. The archaeological excavations conducted by the Tomsk State University and the Seversk Archaeological Inspectorate, which were well known to the Seversk Administration, suggested the idea of creating a Department of Archeology and Ethnography at the museum. This Department was created in 1993. PhD of History P.E. Bardina, E.A. Vasilyev and L.M. Pletneva, came to the Department from the Tomsk State University. From the very beginning, they made it their goal to open a local history exhibition in a few years. In order to create its own collection, the museum needed to undertake archaeological and ethnographic expeditions. It developed a clear plan to excavate already known monuments and, with significant financial support from the Seversk Administration (then known as the City Council of People’s Deputies), brought this plan to life. The museum actively collected ethnographic materials in the surrounding villages. After each year of work, it presented exhibitions. At the same time, the museum developed a Scientific Concept and a Thematic Exposition Plan. In 1997, both documents were approved by the Scientific and Methodological Council of the museum. The Thematic Exposition Plan consisted of three sections: archeology, history of the first Russian settlement on the site of the future city, and ethnography. The exposition as a whole covers the ancient history, the Middle Ages, modern and contemporary times. The archaeological section presents exhibits dating back to the Stone, Bronze, Early Iron, and Middle Ages. The historical section demonstrates documents from archives on the history of the Virgin MaryAlekseevsky Monastery, religious items, photographs of churches from the surrounding villages and priests, a copy of a fragment of the S.U. Remezov’s map. A model of a Russian log cabin with three walls, a front corner and a Russian stove is the central part of the ethnographic exposition. Agricultural and haymaking tools, tools for handicrafts, such as cooperage and blacksmithing, as well as for women's handicrafts, are presented on the outer wall of the log cabin. At a certain distance from the log cabin, there is a hunting hut with tools for hunting, fishing and pine nut harvesting. The exposition is continually updated and supplemented. A particularly large update took place in 2009. In subsequent years, considerable attention was paid to the introduction of innovative technological developments into the exposition. Using the exposition, the museum provides guided tours, classes for schoolchildren and senior kindergarten groups on the basis of museum research and educational programs.

Effect of Microgroove Structures on the Fluid Dynamics and Film Conformality in Spatial Atomic Layer Deposition of Al2O3

A two-dimensional (2D) model coupling computational fluid dynamics (CFD) with chemical kinetics is built to investigate the hydrodynamics and film growth characteristics for Al2O3 deposited from trimethylaluminum (TMA) and water in a spatial ALD system with flat and microgroove substrates. Results show that a vortex flow appears at both sides of the microstructure corners. The vortices hinder the gas flow in the micro-gap, leading to weaker convective mass transfer of precursors to the microstructure corners. Compared to the front corner of the step towards the precursor injector, less precursor concentration is detected at the back corner of the step. The deposition rate at the back corner is always the lowest due to the lowest precursor concentration. A relative lower speed of the substrate can ensure the saturated adsorption of precursors on the substrates, thus improving the conformality of the film deposited on the microstructures.

Don’t Lose Your Heart to a Car. Extracorporeal Ejection of the Heart by Forceful Upward Thoraco-abdominal Blunt Trauma in Human and Animal.

The traumatic extracorporeal ejection of a beating heart has not been witnessed and reported in the literature previously, to our knowledge. Here we present two cases of vehicle accidents leading to this fatal injury, both in a rabbit and a human.&#x0D; Case 1. One late evening in June, in the land of the midnight sun, a young man was driving to his favourite fishing river for a spot of trout fishing in a remote part of Eastern Finland. While driving his aged Nissan Almera at 60 km/h down a dusty gravel road on this dusky night, suddenly a young male rabbit jumped onto the road and appeared in the beam of his headlights. Despite the man’s evasive manoeuvres, the rabbit was struck by the left front corner of the car. After hitting the brakes and the car eventually coming to a standstill, the young man went to inspect the animal he had hit….&#x0D; In conclusion, we present that in a very rare constellation of forceful blunt trauma to the chest, the heart can be completely avulsed and ejected from the body in human as in animals. Larger prospective and randomised studies are probably not needed to confirm these findings. Just be careful – it is possible to lose your heart to a car.