Corner Region Research Articles

Endometriosis cases that occurred at the incision site after cesarean section; Single-center experience

Objective: Endometriosis is the growth of functional endometrial gland and stroma outside the uterine cavity. Scar endometriosis is a very rare disease and is diagnosed by histopathologic examination. Endometriosis may be detected in the scar tissue after a previous gynecological operation. Scar endometriosis is a mass consisting of endometrial glands and stroma that may develop in the incision scar tissue or in the neighborhood after gynecologic procedures performed especially by cesarean section. We aimed to present the patients who had a history of gynecologic surgery, who presented with mass and/or pain complaints especially in the corner regions of the previous incision line, and underwent surgical excision and reported as endometriosis as a result of postoperative pathology.
 Materials and Methods: Patients who presented to the general surgery outpatient clinic between September 2018 and December 2019 with complaints of palpable mass, pain and swelling at the edge of the pfannenstiel incision were evaluated. The records of patients who underwent surgery with a preliminary diagnosis of endometriosis and reported as endometriosis as a result of pathology were reviewed retrospectively.
 Results: Surgical excision was performed in 14 patients with a preliminary diagnosis of endometriosis. The mean age of the patients was 29.5 (min: 18-max: 39 years). All patients had a history of cesarean section as a history of abdominal surgery. When the pathology results were examined, all the reports were endometriosis externa. In the pathology reports, the mean diameter of the lesion was 25x20x17mm (min: 10- max: 40).
 Result: Endometriosis should be considered in patients with a history of palpable mass and pain around the incision site in patients with a history of gynecologic surgery.

Flow and heat transfer in a rotating cavity with de-swirl nozzles: An LES study

Large eddy simulation was applied for studying the flow and heat transfer characteristics in the rotating cavity with de-swirl nozzles. Simulations were performed at the rotational Reynolds number of 1.4 × 105 and nondimensional flow rate of 4040. Compared with vertical nozzle, de-swirl nozzle generates lower swirl ratio, pressure loss and Nusselt number. Distributions of radial velocity show that de-swirl nozzle generates lower velocity in the Ekman boundary layer, but higher velocity in the core region. In the corner region of shroud and jet, the ‘dead zone’ of coherent vortices exists for vertical nozzle. However, for de-swirl nozzle, the ‘dead zone’ disappears due to the impact of inclined injection, and accordingly, the scale of time-averaged counter-rotating vortex pair is reduced effectively. In the middle and lower sections of cavity, plenty of vortex stripes are formed both for vertical and de-swirl nozzles; however, in the Ekman layer, turbulent kinetic energy and Reynolds normal stress for vertical nozzle is much higher than de-swirl nozzle. The distributions of turbulent energy spectrum and energy integral length scale show that, for de-swirl nozzle, large-scale eddies take the dominant role in middle section, while small-scale eddies dominate the flow fields in upper and lower sections of cavity.

C-FCN: Corners-based fully convolutional network for visual object detection

Object detection has achieved significantly progresses in recent years. Proposal-based methods have become the mainstream object detectors, achieving excellent performance on accurate recognition and localization of objects. However, region proposal generation is still a bottleneck. In this paper, to address the limitations of conventional region proposal network (RPN) that defines dense anchor boxes with different scales and aspect ratios, we propose an anchor-free proposal generator named corner region proposal network (CRPN) which is based on a pair of key-points, including top-left corner and bottom-right corner of an object bounding box. First, we respectively predict the top-left corners and bottom-right corners by two sibling convolutional layers, then we obtain a set of object proposals by grouping strategy and non-maximum suppression algorithm. Finally, we further merge CRPN and fully convolutional network (FCN) into a unified network, achieving an end-to-end object detection. Our method has been evaluated on standard PASCAL VOC and MS COCO datasets using a deep residual network. Experiment results present that the proposed method outperforms previous detectors in the term of precision. Additionally, it runs with a speed of 76 ms per image on a single GPU by using ResNet-50 as the backbone, which is faster than other detectors.

Seismic performance of simple steel frames with buckling-restrained knee braces & SMA to reduce residual displacement

Knee braces located in the corner regions of beams and columns have high potential to be widely used in different structures under wind and earthquake loading. Since it is possible that even such braces experience buckling, some attention has been paid to carry out research on using buckling-restrained knee braces (BRKBs). In this study, BRKBs are used in two structures with different number of stories. Due to high cost of Shape Memory Alloy, SMA, it is only utilized in the core of BRKBs rather than steel material. Nonlinear time-history analysis is conducted to evaluate the behavior of the structures under some well-known earthquake records. The results indicated that adding SMA to the BRKBs can reduce the residual deformations of the frames more than 50%.

WIND LOADS ON ROOFING SYSTEM AND PHOTOVOLTAIC SYSTEM INSTALLED PARALLEL TO FLAT ROOF

Mechanically-attached waterproofing system has become popular in Japan. Being vulnerable to wind actions, especially to suctions, this roofing system is often damaged by strong winds. Similarly, photovoltaic (PV) systems installed on flat roofs are often damaged by strong winds, because the PV panels are subjected to large wind forces in an adverse wind. In order to reduce such damage to both systems, the authors propose to install the PV panels parallel to the flat roof with gaps between them, which may reduce the net wind forces on the PV panels due to the effect of pressure equalization. In addition, the wind pressures acting on the waterproofing system will decrease significantly. The present paper investigates the validity of the above-mentioned idea. The wind pressures underneath the PV panels, called ‘layer pressures’, are evaluated by a numerical simulation using the unsteady Bernoulli equation together with the time history of external pressures measured at many locations on the rooftop of a flat-roofed building model in a turbulent boundary layer. The results clearly indicate a significant reduction of wind forces acting on the PV panels as well as on the waterproofing system. The use of PV panels for reducing the wind pressures on waterproofing system is quite effective to the corner region of the roof, where very large suctions are induced in a diagonal wind.

Supersonic flow in the rectangular duct of an air inlet with the separation-induced interaction of the boundary layer with shock waves

Results of a numerical study of the flow structure in the rectangular duct of a model air inlet with the interaction of the shock wave generated by the inlet cowl with the turbulent boundary layer on the inner duct surfaces are reported. A configuration involving a convergent entrance section and a constant-cross-section throat was analyzed. The numerical simulation of the three-dimensional flow with free-stream Mach number M = 4 was performed on the basis of the Reynolds-averaged Navier-Stokes equations and the k-ω SST model of turbulence. As a result of the calculations, the limit streamlines and the distributions of static pressure on the duct surfaces, as well as the distributions of total pressure and the fields of Mach number in duct cross sections were obtained. The structure of the flow is analyzed and the possibility of occurrence of longitudinal vortex structures in the corner region of the intake-duct throat is shown.

Forming of serpentine micro-channels on SS304 and AA1050 ultra-thin metallic sheets using stamping technology

The present work explored the application of conventional stamping technology to manufacture micro-channels in SS304 and AA1050 ultra-thin sheets of 200 μm thickness. In order to obtain defect free stamped components, the forming limit diagrams (FLDs) of both the ultra-thin sheets were determined experimentally by sub-sized stretch forming setup, and these were further used as diagnostic tool for formability predictions. The finite element (FE) simulation of the stamping process was performed to predict different channel parameters such as channel width, depth and thinning development. Based on these predicted results, an in-house stamping test setup was designed and developed to fabricate novel multi-pass and parallel-serpentine micro-channels, and the stamping operation was demonstrated successfully using a 20 ton hydraulic press. The micro-channels with an average width of 1.5 mm and depth of 0.463 mm were fabricated without any wrinkling and fracture, and moreover, the quality of the channels was investigated in terms of channel depth uniformity, thinning development and surface roughness. It was observed that uniform channel with a negligible variation of approximately 1.5% in depth was observed at the central channel compared to that of the lateral channel irrespective of the material. The thickness distribution showed a maximum thinning of approximately 23% and 11% near the bottom corner region of the channels in case of AA1050 and SS304 ultra-thin sheets respectively. Also, surface roughness was found to be higher in the micro-channels fabricated using AA1050 material compared to that of SS304 material due to larger initial grain size and higher amount of effective plastic strain in AA1050 material during stamping.

Comparison of aerodynamic coefficients of various types of Y-plan-shaped tall buildings

Aerodynamic performance of a tall structure can be significantly improved by providing different shape modifications (major and minor). This study presents a comparison of wind load and pressure distribution on different types of shape-modified Y-plan-shaped buildings. The numerical study was done by ANSYS CFX for two turbulence models: k– $$ \epsilon $$ and shear stress transport. For validation purposes, the results of the regular Y-shaped building model are compared with previous experimental results in a similar flow condition. The flow patterns, wind-induced force and distribution of pressure over the surfaces of different types of Y-shaped buildings are represented graphically to interpret the limit of alteration due to the modifications of shape. Different types of helical, tapered, setback and corner-modified models were analysed, and their pros and cons were discussed. Setback building model with rounded corner shape is proved out to be most efficient among the studied models, but there is a problem of a huge increase in the suction on the corner regions.

Computational Predictions for Boger Fluids and Circular Contraction Flow under Various Aspect Ratios

This work puts forward a modeling study contrasted against experimental, with focus on abrupt circular contraction flow of two highly-elastic constant shear-viscosity Boger fluids, i.e., a polyacrylamide dissolved in corn-syrup PAA/CS (Fluid-1) and a polyisobutylene dissolved in polybutene PIB/PB (Fluid-2), in various contraction-ratio geometries. Moreover, this work goes hand-in-hand with the counterpart matching of experimental pressure-drops observed in such 4:1 and 8:1 aspect-ratio contraction flows, as described experimentally in the literature. In this study, the experimental findings, for Boger fluids with severe strain-hardening features, reveal significant vortex-evolution characteristics, correlated with enhanced pressure-drop phasing and normal-stress response in the corner region. It is shown how such behavior may be replicated through simulation and the rheological dependencies that are necessary to bring this about. Predictive solutions with an advanced hybrid finite-element/volume (fe/fv) algorithm are able to elucidate the rheological properties (extensional viscosity and normal-stress response) that rule such vortex-enhancement evolution. This is accomplished by employing the novel swanINNFM(q) family of fluids, through the swIM model-variant, with its strong and efficient control on elongational properties.

World War II Japanese American Internment in the American Southwest

Sites of WWII Japanese Internment create a complex landscape of confinement that spreads across the United States with 13 sites concentrated in the states of Arizona, New Mexico, Utah, and Colorado. This paper provides a brief overview of the history of incarceration focusing on the sites found in the four corners region. While sites may share some artifacts and feature types each tells a unique portion of the larger narrative of unjust confinement and details the lived experience of detainees.

Wide-Band Electromagnetic Wave Propagation and Resonance in Long Cobalt Nanoprisms

Electromagnetic wave interaction with confined metallic magnetic structures is complex due to the excitation of nonuniform electromagnetic fields and magnetic precession and spin-wave modes over length scales that are dependent on the geometric, electromagnetic, and micromagnetic properties of the magnetic structures. Here, we solve the coupled system of Maxwell's equations and the Landau-Lifshitz-Gilbert equation using a stable algorithm based on the finite-difference time-domain method to study the transient wide-band electromagnetic propagation and resonance in infinitely long cobalt nanoprisms with a square cross section of side lengths 50--1000 nm. In particular, we identify the resonance mechanisms through studying the local transient and spectral distributions of magnetization in the prisms. The nanoprisms are excited by an axially polarized plane wave at normal incidence with a 70 GHz Gaussian pulse profile. For this incident wave condition, the simulations confirm that resonance in the cobalt prisms is excited mainly by the current-induced magnetic fields and indicate a magnetization curling resonance mode for prism side lengths less than 100 nm. The eigenfrequencies for the curling mode are confirmed theoretically using a model for an equivalent long circular cylinder with radial spin-wave modes. For prism side lengths longer than 100 nm (but less than the nonmagnetic skin depth), the magnetic response is confined to thin regions along the prism edges due to resonance-induced skin effects. The simulations indicate predominately uniform magnetization precession in the confined edge regions with increased pinning in the corners. The uniform resonance mode in the central part of the edge regions increases in intensity with prism size, with frequency described using Kittel's ferromagnetic resonance frequency of a thin planar structure. A higher-frequency size-independent uniform resonance mode is observed in the corner regions with frequency determined by the local demagnetizing factors. Local and integrated power absorption spectra are calculated using the simulated transient magnetization and fields, and confirm the resonance modes and frequencies in the cobalt prisms and their size dependence. The profile of the local power absorption spectra is also used to estimate the thickness of the confined edge regions or magnetic skin depth in the cobalt prisms at the fundamental resonance mode and is found to be approximately 50 nm. The outcomes of this work would benefit the design and engineering of lightweight and compact materials and devices incorporating metallic magnetic nanostructures. This work also provides a foundation for further modeling and understanding of electromagnetic transmission and propagation in more complex metallic ferromagnetic structures and composites excited by different electromagnetic wave conditions.

An improved prediction model for corner stall in axial compressors with dihedral effect

Corner stall predictions are important and difficult in axial compressors. However, all of the prediction models have proved to be ineffective for advanced compressor blades, which tend to use the combined sweep and dihedral. As for the prediction parameter DL, although it effectively modeled the effects of the adverse pressure gradient and secondary flow, it failed to predict the corner stall of curved blades because the model failed to consider the intersection of the boundary layer at the corner region. In this paper, the shape factor gradient Ψ of the boundary layer at the corner region was investigated by numerically studying specially shaped expansion pipes under different adverse pressure gradients. The improved prediction parameter DJ was presented based on the model of Ψ and the circumferential pressure gradient ξ. A comparison of the critical range of the prediction parameters DL and DJ was investigated using the NACA65 cascade database, which was established by a numerical method. Then, the stall criterion was validated according to the experimental results of various test facilities with different blade geometries and experimental conditions. The results show that the improved prediction parameter is able to predict the corner separation/stall flows and is in good agreement with the experimental results for axial compressors with three-dimensional designed blades.

Plague, pumas and potential zoonotic exposure in the Greater Yellowstone Ecosystem

SummaryWe tested for plague (Yersinia pestis) in a puma population in the Greater Yellowstone Ecosystem (GYE) over 9 years, overlapping a case when a boy in the area became infected with plague. Antibodies to Y. pestis were detected in 8 of 17 (47%) pumas tested by complement-enzyme-linked immunosorbent assay, and the organism itself was detected in 4 of 11 (36%) pumas tested after necropsy. Neither puma sex nor age was significantly associated with Y. pestis exposure or mortality, although our sample size was small. The overall prevalence of exposure we recorded was similar to that found along the western slope of Colorado, which is adjacent to the Four Corners region, a known plague hotspot in the USA. This suggests that: (1) Y. pestis may be present at higher levels in the GYE than previously assumed; (2) plague is a significant source of mortality for local pumas (6.6% of sub-adult and adult mortality); and (3) pumas may be a useful sentinel for potential risk of plague exposure to humans throughout the West. We would also emphasize that hunters and others handling pumas in this region should be made aware of the possibility of exposure.

A thermal EHL investigation on plate-pin hinge pairs in silent chains using a narrow finite line contact

Purpose The purpose of this paper is to numerically study the variations of oil film pressure, thickness and temperature rise in the contact zone of plate-pin pair in silent chains. Design/methodology/approach A steady-state thermal elastohydrodynamic lubrication (EHL) model is built using a Ree–Eyring fluid. The contact between the plate and the pin is simplified as a narrow finite line contact, and the lubrication state is examined by varying the geometry and the plate speed. Findings With increase in the equivalent radius of curvature, the pressure peak and the central film thickness increase. Because the plate is very thin, the temperature rise can be neglected. Even when the influence of the rounded corner region is less, a proper design can beneficially increase the minimum film thickness at both edges of the plate. Under a low entraining speed, strong stress concentration results in close-zero film thickness at both edges of the plate. Originality/value This study reveals the EHL feature of the narrow finite line contact in plate-pin pairs for silent chains and will support the future works considering transient effect, surface features and wear.

Archeointensity of the Four Corners Region of the American Southwest

AbstractNew paleointensity experiments were conducted using the IZZI protocol (a variation on the Thellier‐Thellier method) on 289 specimens from 54 baked pottery fragments collected from four archeological sites in the American Southwest. Anisotropy experiments were conducted to correct for anisotropy of remanence, a common problem in archeological material. Additionally, the effect of cooling rate was evaluated and the calculated paleointensity values were adjusted accordingly. Using the Thellier graphical user interface program, the specimen results were analyzed, averaged by sample (i.e., pottery fragment), filtered for the highest quality, and converted to Virtual Axial Dipole Moments (VADMs). Stylistic evidence, historical documentation, and dendrochronology analyses provide age constraints with up to decade resolution for the VADM results. We compared these new results with the highest quality previously published paleointensity values from the Four Corners region of the American Southwest—defined here as the four states of New Mexico, Arizona, Utah, and Colorado. None of the previously published data were corrected for cooling rate and only some were corrected for anisotropy, resulting in a systematic bias between data sets. To accommodate this difference, an estimated cooling rate correction was applied to all the previously published data. No correction can be made for anisotropy as this is specimen specific. Our estimated cooling rate correction and the empirical correction applied to the new data both require an estimation of the historical cooling rate of the pottery. Experimental pottery firings using one ancient technique and outfitted with thermocouples were conducted to determine the historical cooling rate.

Crashworthiness of tailored-property multi-cell tubular structures under axial crushing and lateral bending

Abstract Thin-walled structures have been widely used as energy-absorbing components, which can be probably subjected to multiple loading conditions in real life, such as axial crushing and lateral bending. Most of the existing literature solely focuses on the pure axial crushing or lateral bending. In this paper, a novel tailored-property multi-cell tubular structure is proposed, where the material's ultimate strength at the corner region is increased to accommodate both the axial crushing and lateral bending conditions. Finite element (FE) models were developed and validated through experimental results. The FE models were used to investigate the crashworthiness performances of the tailored-property multi-cell tubes under axial crushing and lateral bending. Under both axial crushing and lateral bending, it was found that the tailored-property multi-cell tubes exhibited noticeable advantages over the corresponding traditional tubes. The tailoring ratio and thickness had a significant influence on the crashworthiness performance of the tailored-property multi-cell tubes. Moreover, the well-designed tailored-property multi-cell tubes could exhibit the progressive deformation mode under axial crushing. Furthermore, a theoretical model for the tailored-property multi-cell tubes under axial crushing was developed based on the Superfolding Element (SFE) Method. The results showed that the theoretical solutions were in good agreement with the finite element analysis results. The findings of this paper have the potential for energy absorption applications under different loading conditions.

Determination of thermal resistance at mould-strand interface due to shrinkage in billet continuous casting – Development and application of a novel integrated numerical model

An industrial continuous casting process of steel billet is analysed using a novel, integrated numerical model for the heat transfer and solidification of the molten metal as it passes through the mould. One of the major difficulties related to determination of thermal resistance at the mould-strand interface is addressed in the present study. Contrary to empirical or semi-empirical methods commonly used in the industry for determination of the heat transfer at the interface, the present work deals with the determination of the interfacial thermal resistance by adopting a novel mathematical approach. A two-dimensional, transient, finite difference method based code is developed for a plane slice of molten steel moving with a given casting speed down the mould. The resultant solidification and thermal shrinkage are calculated from the temperature distribution and knowledge of the temperature dependent density of steel. The heat transfer from the cast strand to the cooling water is modelled by a network of thermal resistance. The model is validated against experimental data obtained from literature. The numerical results reveal a dominant role of advection of the gaseous mixture of air and other components from pyrolysis of casting oil, in the interfacial gap formed due to the shrinkage of steel, which has not been considered previously in the formulation of thermal resistance. The numerical model is also used to analyse the heat transfer in the mould and the growth of the solidified shell as the strand moves down the mould. In particular, the corner regions of the strand are found to be hotter than the off-corner regions, due to non-uniform heat transfer across the periphery. Also, the effect of casting speed in the mould is found to be dominant in comparison to other casting parameters, such as mould thickness and cooling water velocity.

Evaluation of wind resistance performance for hidden frame glass curtain walls based on digital image correlation technique

In order to characterize the asymmetric deflection deformation of panels in hidden frame glass curtain wall under complex boundary conditions and wind loads, the digital image correlation technique was employed on the curtain wall sample and realized the non-contact full-field flexural deformation measurement. A set of comprehensive evaluation methods for wind resistance performance of glass curtain wall based on the normal distance on the flexural surface of the glass panel, the Gaussian curvature, the surface principal strain and the strain energy density distribution was accordingly proposed by reconstructing the flexural morphology of the panel. The calculation results show that under the situation of initial deflection morphology and structural coupling effect, the maximum surface normal distance of panel after deflection is 6.02 mm, which is less than the current standard experimental calculations. Therefore, the curtain wall is actually more resistant to the wind load; The corner regions of the panel are deformed as a hyperbolic paraboloid, which also have potential safety hazards, with the maximum in-plane principal strain occurred in the upper left corner in 257 μe. Therefore, this method not only avoids the shortcomings of the traditional instrument limited by the measured results of specified point, but also demonstrates the full-field spatiotemporal dynamic behavior of the glass panel deformation, which provides a convenient and effective method for characterizing the wind resistance performance of the hidden frame glass curtain wall.

Subgrid-scale model for large-eddy simulation of transition and turbulence in compressible flows

This article focuses on a subgrid-scale (SGS) eddy viscosity model based on helicity which is derived from our previous research [Yu et al., “Subgrid-scale eddy viscosity model for helical turbulence,” Phys. Fluids 25, 095101 (2013)] for large-eddy simulation of transition and turbulence in compressible flows. Based on the character of the compressible boundary layer over a flat plate, we obtain from theoretical analysis that this model can automatically distinguish laminar flow and turbulence and can also simulate turbulence well. Meanwhile, an a priori test using direct numerical simulation (DNS) data of a spatially developing flat-plate boundary layer at Ma = 2.25 shows that the helicity model can clearly differentiate laminar, transitional, and turbulent regions. Comparing the numerical simulation results with DNS and other SGS models in the spatially developing boundary-layer over a flat plate, we find that the suggested model could precisely predict the onset of transition, transition peak, skin-friction coefficient, mean velocity profile, mean temperature profile, and turbulence intensities. In the case of a compression ramp, the model can well simulate the bypass-type transition, the separated and reattached points, and the size of the separation bubble in the corner region. Furthermore, the prominent advantage of the proposed model can predict transitional flow exactly with no explicit filtering or dynamic procedure.

Effects of annular channel angular extrusion process and heat treatment on microstructure and mechanical properties of 2A12 aluminum alloy cabin

In this paper, a recently developed backward extrusion process enforcing severe plastic deformation, annular channel angular extrusion (ACAE), was successfully applied to produce the 2A12 aluminum (Al) alloy cabin. The effects of the extrusion and heat treatment on microstructure evolution and mechanical properties of 2A12 aluminum alloy were experimentally studied. Microstructure analysis and fracture surface characterization were performed to discern the reason of mechanical properties improvement via the extrusion and heat treatment, and also to explain the mechanisms underlying the grain refinement. The results showed that the grain refinement mechanisms of 2A12 Al alloy were strain-induced boundary migration (SIBM) and continuous dynamic recrystallization (CDRX) caused by severe plastic deformation. Specifically, the billet was subjected to severe shear deformation in the corner region of the ACAE, producing a large number of dislocations and promoting the recrystallization process. After the solution treatment, the alloy endured static recovery and recrystallization, and the microstructure was further refined. However, abnormal grain growth was identified after solution treatment at 495 °C for 2 h, which affected the mechanical behavior negatively. A lot of S phases precipitated from the alloy after solution and aging treatment, and the mechanical properties of the alloy were obviously improved. The specimens cut from the extruded cabin after solution (495 °C + 1 h) and aging (195 °C + 6 h) heat treatment achieved the highest ultimate tensile strength of ~476.1 MPa with an appropriate elongation to failure of ~12.9%.