Ellipticity Ratio Research Articles

Association of non-invasive assessed anatomical features with functional testing in coronary artery anomalies - NARCO trial

Abstract Introduction Anomalous aortic origin of a coronary artery (AAOCA) is a rare congenital condition believed to carry an increased risk for myocardial ischemia. However, correlation between anatomical characteristics and ischemia remains unclear. Therefore, this study aimed to assess: 1. The difference of invasive fractional flow reserve (FFR) and intravascular ultrasound (IVUS)-based minimal lumen area (MLA) between baseline and stress. 2. The association of coronary computed tomography angiography (CCTA)-based anatomical characteristics to invasively measured hemodynamics and IVUS in AAOCA. Methods Consecutive patients with AAOCA and presence of ≥1 anatomical high-risk features (i.e. intramural course (IM), slit-like ostium, acute take-off angle or proximal narrowing), were systematically evaluated as part of the NARCO trial using CCTA, FFR using adenosine (140 µg/kg/min), dobutamine-volume stress (20-40mcg/kg/min, 0.5-1mg atropine and 3L of saline solution) and IVUS- MLA of IM. Anatomic high-risk features were quantified by CCTA including ostial lumen area and IM-MLA, IM-width, IM-height, IM-elliptic ratio, take-off angle, proximal narrowing and IM length of the anomalous coronary segment. Results A total of 94 patients with AAOCA were screened, whereas 48 showed high-risk anatomic features and underwent the complete stress protocol. Mean age was 54±12 years and 36 (75%) were male and 39 (81%) presented with symptoms. FFRstress was significantly lower than FFRadenosine (0.88 [0.81-0.91] vs. 0.91 [0.87-0.94], p<0.001) (Figure 1). FFRadenosine was ≤0.8 in 5 patients (10%), and FFRdobutamine was ≤0.8 in 12 patients (25%), resulting in 7 (15%) with FFRadenosine >0.8 while FFRdobutamine was ≤0.8. IVUS-MLA was decreased from 6.3 (5.4-8.2) mm2 to 5.4 (4.2-7.1) mm2 during stress (p<0.001) (Figure 2), while elliptic ratio increased from 2.6 (2.1-3.4) to 3.3 (2.5-4.4) (p<0.001). Logistic regression analysis for body surface area adjusted CCTA derived high-risk features showed, that only ostial lumen area, IM-MLA, -elliptic ratio and -width could predict FFRstress ≤0.8. Receiver operating curve analysis showed that ostial width had the greatest AUC with 0.86 (accuracy 83%, sensitivity 83%, and specificity 83%). Eight out of 12 (67%) patients with hemodynamic relevance underwent surgery, 2 (17%) underwent stenting and 2 (17%) were treated with medication. Conclusion In patients with AAOCA and anatomic high-risk features, only one quarter are hemodynamic relevant. FFR during dobutamine-volume stress showed to be the more sensitive stress modality as compared to FFRadenosine. CCTA derived ostial and IM anatomical severity is associated with ischemia under stress. Comprehensive functional and anatomical assessment of AAOCA helps to optimize patient management and avoid unnecessary revascularization.Figure 1:FFRadenosine vs FFRstressFigure 2:IVUS-MLArest vs IVUS-MLAstress

Ellipsometry of surface acoustic waves using 3D vibrometry for viscoelastic material characterization by the estimation of complex Lamé coefficients versus the frequency

Surface acoustic waves (SAW) are adequate regarding material characterization because they have low geometric attenuation compared to bulk waves. SAW can be generated easily by normal excitation using contact transducers or power lasers and have also a unique elliptic polarization, characterized by two parameters: the ellipticity (H/V) ratio between the horizontal and the vertical components of the elliptic motions and the orientation angle (θ) between the horizontal axis of the ellipse and the surface. In the case of a viscoelastic isotropic material, a complete characterization is achieved by the association of the quantitative measurement of the polarization and the propagative characteristics, the complex wavenumber, of the SAW. In practice, this operation is performed using 3D lased vibrometry for propagation monitoring in space and time. The post-processing is carried out by Quaternion Fourier Transform, the Prony algorithm and the complex Lamé coefficients identification for the theoretical model of propagation on the material. Good agreement is observed between the obtained results and the ones of the pulse-echo method.

On the Optimal Combination of Elliptically Distributed Biomarkers to Improve Diagnostic Accuracy.

Diagnostic biomarkers play a critical role in biomedical research, particularly for the diagnosis and prediction of diseases, etc. To enhance diagnostic accuracy, extensive research about combining multiple biomarkers has been developed based on the multivariate normality, which is often not true in practice, as most biomarkers follow distributions that deviate from normality. While the likelihood ratio combination is recognized to be the optimal approach, it is complicated to calculate. To achieve a more accurate and effective combination of biomarkers, especially when these biomarkers deviate from normality, we propose using a receiver operating characteristic (ROC) curve methodology based on the optimal combination of elliptically distributed biomarkers. In this paper, we derive the ROC curve function for the elliptical likelihood ratio combination. Further, proceeding from the derived best combinations of biomarkers, we propose an efficient technique via nonparametric maximum likelihood estimate (NPMLE) to build empirical estimation. Simulation results show that the proposed elliptical combination method consistently provided better performance, demonstrating its robustness in handling various distribution types of biomarkers. We apply the proposed method to two real datasets: Autism/autism spectrum disorder (ASD) and neural tube defects (NTD). In both applications, the elliptical likelihood ratio combination improves the AUC value compared to the multivariate normal likelihood ratio combination and the best linear combination.

Deep neural network-enabled multifunctional switchable terahertz metamaterial devices

Under the support of deep neural networks (DNN), a multifunctional switchable terahertz metamaterial (THz MMs) device is designed and optimized. This device not only achieves ideal ultra-wideband (UWB) absorption in the THz frequency range but enables dual-functional polarization transformation over UWB. When vanadium dioxide (VO2) is in the metallic state, the device as a UWB absorber with an absorption rate exceeding 90% in the 2.43–10 THz range, with a relative bandwidth (RBW) of 145.2%, and its wideband absorption performance is insensitive to polarization. When VO2 is in the insulating state, the device can switch to a polarization converter, achieving conversions from linear to cross polarization and from linear to circular polarization in the ranges of 4.58–10 THz and 4.16–4.43 THz, respectively. Within the 4.58–10 THz range, the polarization conversion ratio approaches 100% with an RBW of 74.3%, the polarization rotation angle is near 90°. Within the 4.16–4.43 THz range, the RBW is 6.29% and the ellipticity ratio approaches 1, Moreover, the effects of incident angle and polarization angle on the operational characteristics are studied. This THz MMs due to its advantages of wide angle, broad bandwidth, and high efficiency, provides valuable references for the research of new multifunctional THz devices. It has great application potential in short-range wireless THz communication, ultrafast optical switches, high-temperature resistant switches, transient spectroscopy, and optical polarization control devices.

A Light-Powered Self-Circling Slider on an Elliptical Track with a Liquid Crystal Elastomer Fiber.

In this paper, we propose an innovative light-powered LCE-slider system that enables continuous self-circling on an elliptical track and is comprised of a light-powered LCE string, slider, and rigid elliptical track. By formulating and solving dimensionless dynamic equations, we explain static and self-circling states, emphasizing self-circling dynamics and energy balance. Quantitative analysis reveals that the self-circling frequency of LCE-slider systems is independent of the initial tangential velocity but sensitive to light intensity, contraction coefficients, elastic coefficients, the elliptical axis ratio, and damping coefficients. Notably, elliptical motion outperforms circular motion in angular velocity and frequency, indicating greater efficiency. Reliable self-circling under constant light suggests applications in periodic motion fields, especially celestial mechanics. Additionally, the system's remarkable adaptability to a wide range of curved trajectories exemplifies its flexibility and versatility, while its energy absorption and conversion capabilities position it as a highly potential candidate for applications in robotics, construction, and transportation.

Vibration suppression and transient tribo-dynamic stability for adjustable offset-elliptical journal bearings under time-varying load and bi-directional misalignment

This paper concentrates on vibration suppression and transient stability in the key yet understudied field of a newly variable-structure journal bearing that actively adjusts the offset coefficient and elliptical ratio. A novel tribo-dynamic model and modified stability criterion are proposed and validated to investigate the nonlinear characteristics of adjustable offset-elliptical journal bearings (AOEJBs), especially under time-varying loads and bi-directional misalignment. Moreover, bearing behaviors are comparatively analyzed considering multiple coupling factors. The evolution mechanism of load change, varying lubricants, and misalignment variation on the transient stability is studied. The results demonstrate satisfactory vibration suppression and transient performance of AOEJBs, providing a valuable reference for the lubrication design of dynamically loaded bearings.

Exploration of morphological coherence in open clusters with a “core-shell” structure

Context. The morphology of open clusters plays a major role in the study of their dynamic evolution. The study of their morphological coherence, namely, the three-dimensional (3D) difference between the inner and outer morphologies of open clusters, allows us to obtain a better understanding of the morphological evolution of open clusters. Aims. We aim to investigate the morphological coherence of 132 open clusters with up to 1 kpc from the Sun in the three-dimensional (3D) space within the heliocentric cartesian coordinate frame. The 132 open clusters have a 3D core-shell structure and conform to the ellipsoidal model, with all of them coming from a catalog of publicly available clusters in the literature. Methods. We employed the ellipsoid fitting method to delineate the 3D spatial structure of the sample clusters, while using the morphological dislocation (MD) defined in our previous work and the ellipticity ratio (ER) of the clusters’ inner and outer structures to characterize the morphological coherence of the sample clusters. Results. The results show an inverse correlation between the ER of the sample clusters and the number of their members, indicating that sample clusters with a much more elliptical external morphology than internal shape generally tend to host a large number of members. Meanwhile, a slight shrinking of the MD of the sample clusters with their members’ number may shed light on the significant role of the gravitational binding of the sample clusters in maintaining their morphological stability. Moreover, there are no correlations between the MD and ER of the sample clusters and their age. They are also not significantly correlated with the X-axis, the Y-axis, their orbital eccentricities, and the radial and vertical forces on them. However, the ER of the sample clusters displays some fluctuations in the distributions between it and the above covariates, implying that the morphologies of the sample clusters are sensitive to the external environment if sample effects are not taken into account. Finally, the analysis of the 3D spatial shapes of sample clusters with a small ER or a large ER demonstrates that the number of members lays an important foundation for forming a dense internal system for sample clusters. At the same time, the MD of the sample clusters can serve well as an indicator of their morphological stability, which is built upon a certain amount of member stars. Conclusions. We present a new insight into the morphological coherence of open clusters, attributed to the combination of their gravitational binding capacity and external environmental perturbations.

Numerical investigation of elliptical trailing edge on cascade loss of transonic turbine airfoils

Abstract The shape and thickness of the trailing edge are important factors in the supersonic loss in transonic cascades. To investigate the influence of trailing edge shape, a prismatic turbine cascade and a three-dimensional cascade with an elliptic trailing edge were analyzed with numerical simulation by changing different elliptic axis ratios ER. It was indicated that the shock wave and its mixing with the wake were the important sources of loss in the transonic prismatic cascade. With the increase of exit Mach number, shock waves are generated rapidly and migrate downstream, and the shock loss and the total loss of the prismatic cascade are both accrescent. Increasing the elliptical axis ratio could weaken shock waves and delay shock waves. In the loss state region 3, the cascade loss of the ER3 blade is reduced by 8% compared with the round trailing edge cascade. As the elliptical axis ratio of the three-dimensional cascade is increasing, the profile loss and secondary loss are reduced. However, an excessive elliptical axis ratio could lead to an increase in tip leakage loss. Within the range of ER values from 0 to 3, the total loss of the transonic three-dimensional cascade reached minimization when ER was 3.0.

Otolith Shape Analysis of Five Sillaginidae Species from the Persian Gulf and the Oman Sea

The discrimination power of sagittal otolith shape analysis is evaluated for five closely related sillaginid species from the Persian Gulf and the Oman Sea; (Sillago arabica, Sillago attenuata, Sillago indica, Sillago sihama and Sillaginopodys chondropus) besides the description of morphological characters using scanning electron microscopy (SEM). The identification of sillaginids is difficult due to the limited reliable diagnostic morphological characters. The otolith shape was described by six shape indices (Roundness, Rectangularity, Circularity, Ellipticity, Form factor and Aspect ratio) and Elliptic Fourier Descriptors (EFD). For all shape indices, there was at least an overlap between the two species and no one was significantly different among the five species. Based on EFD analysis all five species were discriminated (91.7%) evidencing the high taxonomic value of sagittal otolith for the studied taxa. SEM images revealed sulcus acusticus as homosulcoid with an inframedian position in all five species. S. arabica and S. sihama are characterized by having a pseudo-ostiocaudal, while S. indica, S. attenuate and Sillaginopodys chondropus have ostial mode of opening. The ostium was tubular and slightly curved in all studied species, which was more strongly curved in S. arabica. These findings suggest that the sagittal otolith shape is a reliable tool to recognize inter-specific diagnosis for sillginid species in the Persian Gulf and Oman Sea.

Otolith Shape Indices of Japanese Threadfin Bream (Nemipterus japonicus, Bloch 1791) from the Makassar Strait, Indonesia

Japanese threadfin bream (Nemipterus japonicus) is a demersal fish that plays a very important role in maintaining ecosystem stability related to webs and food chains. This fish often becomes prey for predatory fish. In efforts to reveal the relationship between predators and prey in food webs and food chains, there is still limited information due to the difficulty of identifying digested food. In connection with this, this study aims to identify the morphology shape index value otolith of Japanese threadfin bream. Sampling was carried out at the Labuang Maros Fish Landing Site with 150 samples and morphometric data were collected from 150 pairs of otoliths in April and May 2023. The calculation of the shape index uses six descriptors, which include form factor (FF), roundness (RO), circularity or compactness (C), rectangularity (Rt), ellipticity (E), and aspect ratio (AR). The results showed that there was no significant difference in the otolith morphometry of the right and left otoliths (P>0.05). Based on the shape index value obtained, it explains that the morphometric shape of the otolith of Japanese threadfin bream tends to be oval, elongated, and has an irregular surface.

Tunable deformation design of porous Al2O3 based on the Direct FE2 method

Abstract The tunable deformation design of porous ceramics has raised many interests in many engineering and manufacturing fields, where its corresponding design methodologies still suffer from the lower efficiency and higher computational cost. To handle this problem, a novel optimization and design methodology based on the Direct FE2 method has been proposed in this study, and several numerical examples of the porous Al2O3 tunable deformation design has been performed by this novel methodology. Compared with the traditional methodologies, the proposed method is more convenient to conduct the tunable deformation design and improves the optimization efficiency. Based on this method, the distribution and assembly of the microscale RVE could be tailored along the space dimension to handle the sinusoidal deformation and variable Poisson’s ratio ceramic design at the macroscale. By comparing the simulation results with the Direct Numerical Simulation (DNS) model, the effectiveness and accuracy of this methodology is well validated. Meanwhile, the simulation results based on the proposed methodology found that the predictability of porous Al2O3 deformation could be enhanced by changing the micro structure parameters such as the elliptical hole angle and aspect ratio. This methodology holds great potential for applications in the design and optimization of porous ceramics with tailored deformation characteristics.

Manipulation of geometric parametric sidebands via elliptical Gaussian beam in graded-index multimode fibers

Geometric parametric instability is a class of processes where the revival of optical beam in a nonlinear multimode graded-index fiber induces a spatial index modification and in turn generates frequency sidebands due to space-time coupling. While current studies have been focusing on breathing Gaussian beams in such settings, the evenly spaced eigenvalue in parabolic fiber indicates that any input condition will experience self-imaging effects under linear conditions. Here we investigate the nonlinear propagation and the corresponding geometric parametric instability sidebands generation associated with elliptical Gaussian beams where the long- and short- axis of the beam oscillates with different phases. We show that, depending on the initial conditions, there are four possible propagation regimes: over-trapping, self-trapping, under-trapping and self-focusing. As a result, the spacing and strength of generated sidebands can be judiciously tuned by the elliptical ratio of elliptical Gaussian beams. At certain conditions, missing-order effect occurs where a set of sidebands completely disappear. We experimentally observed the multiple and a few sidebands of the Gaussian beam and elliptical Gaussian beam in a standard graded-index multimode fiber. In addition, experiments show that GPI sidebands have well-defined and stable bell-shaped near-field profiles. These results pave the way for developing tunable light sources and ultra-broadband supercontinuum generation.

Can the Mismatch of Measured Pelvic Morphology vs. Lumbar Lordosis Predict Chronic Low Back Pain Patients?

Background: Measures of lumbar lordosis (LL) and elliptical modeling variables have been shown to discriminate between normal and chronic low back pain (CLBP) patients. Pelvic morphology influences an individual's sagittal lumbar alignment. Our purpose is to investigate the sensitivity and specificity of lumbar sagittal radiographic alignment and modeling variables to identify if these can discriminate between normal controls and CLBP patients. Methods: We conducted a computer analysis of digitized vertebral body corners on lateral lumbar radiographs of normal controls and CLBP patients. Fifty normal controls were attained from a required pre-employment physical examination (29 men; 21 women; mean age of 27.7 ± 8.5 years), with no history of low back pain, a normal spinal examination, no pathologies, anomalies, or instability. Additionally, 50 CLBP patients (29 men; 29.5 ± 8 years of age) were randomly chosen and matched to the characteristics of the controls. The inclusion criteria required no abnormalities on lumbar spine radiographs. The parameters included the following: ARA L1-L5 lordosis, ARA T12-S1 lordosis, Cobb T12-S1, b/a elliptical modelling ratio, sacral base angle (SBA), and S1 posterior tangent to vertical (PTS1). Two measures of pelvic morphology were determined for each person-the angle of pelvic incidence (API) and posterior tangent pelvic incidence angle (PTPIA)-and the relationships between API - ARA T12-S1, API - Cobb T12-S1, and API - ARA L1-5 was determined. Descriptive statistics and correlations among the primary variables were determined. The receiver operating characteristic curves (ROC curves) for primary variables were analyzed. Results: The mean values of LL were statistically different between the normal and CLBP groups (p < 0.001), indicating a hypo-lordotic lumbar spine for the CLBP group. The mean b/a ratio was lower in the chronic pain group (p = 0.0066). The pelvic morphology variables were similar between the groups (p > 0.05). API had a stronger correlation to the SBA and Cobb T12-S1 than PTPIA did, while PTPIA had a stronger correlation to the S1 tangent and ARA T12-S1 than API did. While CLBP patients had a stronger correlation of ARA T12-S1 and Cobb T12-S1 relative to the pelvic morphology, they also had a reduced correlation of ARA L1-L5 lordosis relative to their SBA and pelvic morphology measures. API - T12-S1, API - L1-L5, and API - Cobb T12-S1 were statistically different between the groups, p < 0.001. Using ROC curve analyses, it was identified that ARA L1-L5 lordosis of 36° and ARA T12-S1 of 68° have a good sensitivity and specificity to discriminate between normal and CLBP patients. ROC curve analyses identified that lordosis ARAT12-S1 < 68° (AUC = 0.83), lordosis ARAL1-L5 < 36° (AUC = 0.78), API - ARA T12-S1 < -18° (AUC = 0.75), API - ARAL1-L5 > 35° (AUC = 0.71), and API - Cobb T12-S1 < -5° (AUC = 0.69) had moderate to good discrimination between groups (AUC = 0.83, 0.78, 0.75, and 0.72). Conclusions: Pelvic morphology is similar between normal and CLBP patients. CLBP patients have an abnormal 'fit' of their API - ARAT12-S1 and L1-L5 lumbar lordosis relative to their pelvic morphology and sacral tilt shown as a hypolordosis.

An investigation on shell-side thermal–hydraulic performance of helically coiled tube heat exchanger for deep underground space

Helically coiled tube heat exchanger (HCHE) was extensively used to enhance the thermal environment of deep underground space. The inefficiency of heat transfer in the mine cooling system results in increased operational energy consumption. To enhance heat utilization, this study examines the impact of air temperature, air velocity, coil diameter, pitch, and elliptical tube aspect ratio on the shell-side thermal performance of HCHE through experimental and numerical analysis. The performance evaluation criterion (PEC) and field synergy are introduced to provide a comprehensive assessment of performance. Results suggest that the air velocity can more significantly affect the thermal performance of HCHE than air temperature. Augmenting the coil diameter from 30 − 40 mm and coil pitch from 7.5 − 9.0 mm led to an increase in the Nu number by 16.5 % and 6.7 %, as well as an increase in friction factor f by 575.2 % and 147.1 %, while a reduction in PEC by 38.4 % and 21.1 % when the air velocity is 5 m/s, respectively. For the helically coiled elliptical-tube heat exchanger (HCHE-E), the thermal performance is significantly dependent on the long axis's direction and its aspect ratio. When the air velocity is 3 m/s, the increase in aspect ratio from 1.0 to 1.8 resulted in a decrease and increase in Nu by 14.7 % and 14.6 %, an increase and decrease in PEC by 24.5 % and 28.4 %, as well as a reduction and increase in f by 31.5 % and 48.1 % for the long axle in the horizontal and vertical directions, respectively. The PEC for HCHE is not significantly dependent on the air velocity. The increase in air velocity can result in the augment in PEC of HCHE-E regardless of long axis's direction. The variation of synergy angle is consistent with the change of Nu. These findings offer valuable insights for optimizing the design parameters of HCHE in deep underground spaces.

Impact of stent strut link location in proximal balloon edge dilation technique for bifurcation percutaneous coronary intervention.

The single-stent strategy has generally been accepted as the default approach to bifurcation percutaneous coronary intervention. We have proposed the proximal balloon edge dilation (PBED) technique to prevent stent deformation during side branch (SB) dilation. This bench study aimed to evaluate the impact of stent link location and stent design on stent deformation, obstruction by stent struts at a jailed SB ostium, and incomplete stent apposition in the proximal optimization technique (POT)-PBED procedure. A coronary bifurcation model was used. We intentionally set the absence or presence of stent link on the carina (link-free or link-connect) under videoscope observation and compared stent parameters between 3- and 2-link stents (n = 5 each, n = 20 total). In the link-free group, the SB jailing rate of 3-link stents was significantly higher than that of 2-link stents (15.5 ± 5.1% vs. 6.6 ± 1.2%, p = 0.009). In the link-connect group, the SB jailing rate of 3-link stents was significantly lower than that of 2-link stents (30.0 ± 4.5% vs. 39.0 ± 2.6%, p = 0.009). In the bifurcation segment, the rate of incomplete stent apposition was significantly lower for 3-link stents of the link-connect group than for 2-link stents of the link-connect group (3.3 ± 4.2% vs. 19.0 ± 7.8%, p = 0.009). For both stent designs, ellipticity ratio was higher for link-connect group than link-free group. Link location as well as stent cell design greatly impacted stent deformation during the POT-PBED procedure.

Elliptical concrete-filled FRP tubes with an embedded H-shaped steel under axial compression and cyclic lateral loading: Experimental study and modelling

Concrete-filled FRP tubes (CFFTs) have found increasing applications due to their superior ductility and remarkable corrosion resistance. In published literature, circular CFFTs and rectangular CFFTs have been investigated extensively, while there are relatively few studies on elliptical CFFTs. There is no research about elliptical CFFTs with an embedded H-shaped steel (i.e., HS-ECFFTs) under axial compression and cyclic lateral loading. Against this background, this paper investigated the seismic behaviour of HS-ECFFTs experimentally and numerically. Test results indicated that: (1) all HS-ECFFTs performed well with remarkable energy dissipation ability; (2) due to the effective FRP confinement, the local buckling of the H-shaped steel was prohibited; (3) the elliptical aspect ratio had limited influences on the ductility, the stiffness degradation and the energy dissipation; (4) the FRP thickness, after a certain threshold, showed beneficial but limited influences on the peak load, the stiffness degradation and the energy dissipation; (5) the HS-ECFFT specimen performed much better in terms of the peak load, the ductility, the stiffness degradation and the energy dissipation when it was bending around the strong axis. The proposed numerical model established on the OpenSees platform could generate reasonably accurate numerical results for all HS-ECFFTs.

Three-dimensional observation of porous materials prepared from iron tailings and their pore wall site adsorption function

Porous materials are widely used to treat phosphorus-containing wastewater due to their structural characteristics and loading site functionality. The use of iron tailings as a raw material during the preparation of these materials can effectively reduce production costs. In this study, a porous material was prepared according to a one-step method using solid waste iron tailings. High-temperature phase transition technology was used to construct crystallographic sites on the pore walls of the material to improve the phosphorus removal efficiency. The pore structure, pore wall characteristics, and internal crystal growth in the three-dimensional space of the material were characterized using X-ray microscopy (micro-CT) scanning, and the voxel data for the internal structural were analyzed. The results showed that the material had a clear internal skeletal structure, a uniform distribution of internal pores, and crystal phases in three-dimensional space. The pore ratio in the three-axis direction was greater than 50%, with connected pores accounting for more than 95% of the pores. The wall thickness distribution was uniform, but the pore size distribution and ellipticity ratio varied significantly due to the different pore structures and quantities. A connected structure was formed when the thin walls of adjacent pores ruptured, and there were magnesioferrite and hematite crystal sites with fractal growth in the pore wall framework. The adsorption capacity of the porous material for phosphorus pollutants was investigated using photometry, and the highest removal rate was found to be 68.13%. This analysis suggests that the presence of rough pore walls, a high specific surface area, and crystal sites within the pore walls enhance the adsorption performance of the material. Further research along this line could explore the potential of developing new low-cost materials for pollution treatment.

Supersonic Flow over Elliptic Cone with Different Ellipticity Ratio

This study investigates supersonic flow characteristics over circular and elliptic cones at various angles of attack. Simulations were conducted on the cones with the same base area and length-to-diameter ratio. The elliptic cones considered had axis ratios of 1.5 and 3. The angle of attack varied from 0o to 50o, with two different Mach numbers (1.97 and 2.94) employed for the analysis. The numerical results were compared with the experimental and theoretical findings from existing literature. The results revealed that increasing the ellipticity ratio of the cones resulted in higher lift generation. The pressure distributions on the windward and leeward sides of the cones were also examined. The results demonstrated that elliptic cones outperformed circular cones in terms of lift production, and this advantage increased with higher ellipticity ratios. Specifically, when the ellipticity ratio was increased from 1 to 3, the maximum increase in lift coefficient was 96% and 100% at Mach numbers 2.94 and 1.97, respectively. Additionally, by changing the ellipticity ratio from 1 to 1.5, the maximum gain in the lift-drag ratio was 16% and 22% at Mach numbers 1.97 and 2.94, respectively. Notably, an elliptic cone with an ellipticity ratio of 3 achieved a remarkable 46% gain in lift-to-drag ratio compared to a circular cone. However, as the angle of attack increased, a primary bow shock formed on the windward side of the cone, with an embedded shock appearing on the leeward side.

Ground stability of ellipsoidal cavity due to pipeline defects

The problem of road-related sinkhole stability has long been one of the main safety concerns to pavement engineers. Collapse and blowout failures are two typical types of pipeline-related sinkhole failures. Although much research on sinkhole stability analyses can be found in the literature, most of them assume a simple circular or rectangular shape of a cavity. In this study, the problem of sinkhole stability in an ellipsoidal cavity is investigated under both blowout and collapse conditions using advanced finite element limit analysis with adaptive meshing in an axisymmetric condition. A dimensionless pressure ratio is defined to represent sinkhole stability that is a function of many design parameters such as depth ratio, elliptical shape ratio, and soil strength ratio. Selected results are compared with published solutions, and comprehensive solutions of the parametric study are presented in the form of charts for use by design engineers. The present study contributes to the understanding of sinkhole stability under an ellipsoidal cavity, and it should be of interest to the road engineering community.

The effect of structural damping on flow-induced vibration of a thin elliptical cylinder

This study experimentally investigates the influence of structural damping on the transverse flow-induced vibration (FIV) of an elastically mounted thin elliptical cylinder. The cylinder tested has an elliptical ratio of $\varepsilon = b/a = 5$ , where $a$ and $b$ are the streamwise and cross-flow dimensions, respectively, and a mass ratio (i.e. the total oscillating mass/the displaced fluid mass) of $17.4$ . The FIV response was characterised over a reduced velocity range of $2.30 \leq U^* = U/(\,{{f_{{nw}}}} b) \leq 10.00$ (corresponding to a Reynolds number range of $300 \leq \textit {Re} =(U b)/\nu \leq 1300$ ) and a structural damping ratio range of $3.62\times 10^{-3}\leq \zeta \leq 1.87\times 10^{-1}$ . Here, $U$ is the free stream velocity, ${{f_{{nw}}}}$ is the natural frequency of the system in quiescent fluid (water) and $\nu$ is the kinematic viscosity of the fluid. The FIV response was characterised by four wake–body synchronisation regimes (defined as the matching of the dominant fluid forcing and oscillation frequencies, and labelled regime I, regime II, regime III and the hyper branch) and a desynchronisation region, with the hyper branch representing a high amplitude regime not observed for a circular cylinder. Interestingly, the major vortex shedding mode was predominately two single opposite-signed vortices shed per body vibration cycle. Moreover, hydrogen-bubble-based flow visualisations revealed a secondary vortex street forming in the elongated shear layers associated with largest-scale vibration amplitudes ( $A^* = A/b$ up to $7.7$ ) in the hyper branch and regime II. As the structural damping ratio was increased beyond $1.92 \times 10^{-2}$ , the hyper branch was found to be suppressed. The results have potential ramifications for the efficient extraction of energy from free-flowing water sources, which has become increasingly topical over the last decade.