Acetabular dysplasia may persist in developmental dysplasia of the hip (DDH), leading to an increased risk of early hip degeneration. This study aimed to identify predictive factors for residual acetabular dysplasia (RAD) in children aged 2 to 5 years using magnetic resonance imaging (MRI). A retrospective study was conducted on 67 hips from 34 patients. The diameters of the femoral head and acetabular cartilages were measured on T2-weighted coronal images, and the difference and ratio of the cartilage diameters were calculated. The outcome measure was the Severin classification at the final follow-up. Patients were divided into 3 groups based on their age at the time of MRI, for additional evaluations. The mean age at the final follow-up was 13.4 (6.2 to 23.5) years, and the mean age at the MRI was 3.8 (2.4 to 5.9) years. The good and poor outcome groups comprised 48 (72%) and 19 (28%), respectively. The good outcome group had a smaller cartilage diameter difference (4.6±0.9 vs. 6.4±1.4mm; P <0.05), and larger cartilage diameter ratio (86±3 vs. 82±3%; P <0.05). A cartilage diameter difference of ≥5.5mm and a cartilage diameter ratio of ≤85% were associated with poor acetabular growth. The difference and ratio of the cartilage diameters was significantly different at all ages at which the MRI was performed. Combining cartilage diameter measurements with radiographic parameters improved predictive accuracy. Cases in which the acetabular cartilage diameter was larger than the femoral head cartilage diameter (difference ≥5.5mm, ratio ≤85%) showed poor subsequent acetabular development. Cartilage evaluation using MRI during childhood, particularly between 3 and 5 years of age, is useful for predicting acetabular development. Level III-retrospective comparative study.

Periprocedural thromboembolic events are common complications of neuroendovascular treatment. We aimed to determine the incidence and potential risk factors of DWI-positive lesions detected on postoperative MRI after Woven EndoBridge (MicroVention/Terumo, Aliso Viejo, CA, USA) treatment for intracranial aneurysms. Between February 2021 and April 2025, 55 patients underwent Woven EndoBridge treatment for 59 intracranial aneurysms at two neurovascular institutions in Japan. Of these, 37 patients with 40 unruptured intracranial aneurysms treated with the Woven EndoBridge device alone were retrospectively enrolled. The distal access catheter/parent artery ratio was defined as the outer diameter of the distal tip of the distal access catheter divided by the diameter of the parent artery. MRI was performed within 48 hours after the procedure to evaluate appearance and number of DWI-positive lesions. DWI-positive lesions after Woven EndoBridge treatment were confirmed in 28 (70.0%) unruptured intracranial aneurysms. Univariate analysis revealed a trend toward a higher proportion of age ≥70 years (DWI-positive lesion [-] group: 33.3% vs [+] group: 64.3%, P=.09). The proportion of distal access catheter/parent artery ratio ≥0.70 differed significantly between the two groups (DWI-positive lesion [-] group: 8.3% vs [+] group: 53.6%, P=.01). In the multiple logistic regression model using age and distal access catheter/parent artery ratio, a distal access catheter/parent artery ratio (OR, 111.00; 95% CI, 0.76-16000.00; P=.06) was identified as a marginally significant risk factor for postprocedural DWI-positive lesions. Furthermore, the eligible cases were divided into two groups: DWI-positive lesion ≥10 (-) group (n=31, 77.5%) and ≥10 (+) group (n=9, 22.5%). Univariate analysis revealed significant differences in the proportion of age ≥70 years (45.2% vs 88.9%, P=.03) and those with a distal access catheter/parent artery ratio ≥0.80 (9.7% vs 66.7%, P=.001). In the multiple logistic regression model using age and distal access catheter/parent artery ratio, a significant relationship was found between distal access catheter/parent artery ratio (OR, 1400.00; 95% CI, 3.70-533000.00; P=.02) and postprocedural DWI-positive lesion ≥10 following Woven EndoBridge treatment. Distal access catheter/parent artery ratio in Woven EndoBridge treatment may affect DWI-positive lesions incidence and postprocedural count.

Abstract The pseudo homogeneous fixed bed heat transfer model employs two lumped parameters to describe radial heat transfer, the effective radial thermal conductivity and the apparent wall heat transfer coefficient . These parameters are difficult to correlate empirically, especially from data for tube‐to‐particle diameter ratio , as each combines several heat transfer phenomena. An alternative approach, termed model matching, is to relate and to the heat transfer parameters for fluid and solid individual phases in a heterogeneous fixed bed heat transfer model, which are easier to investigate experimentally or by simulation. A model matching method is evaluated that provides relations between the lumped and single‐phase heat transfer parameters and gives excellent predictions of the effective parameters but involves complex equations requiring iterative solution. A new approximate version of the method is offered, giving accurate predictions using much simpler explicit equations.

Unveiling the multi-droplet dynamics in dust suppression: a combined numerical and molecular dynamics study on the wetting, coating, and agglomeration using biomass-betaine surfactants.

Covered stent implantation is an effective treatment for coarctation of the aorta (CoA) and can reduce aortic wall injury; however, stent-related complications, including recoil, restenosis, infolding, and access site injury, are of concern. Report our institutional experience using the BeGraft Aortic covered stent for native and recurrent CoA. Retrospective review of consecutive patients treated for CoA from January 2017 to April 2025 [IRB RMC 389-22]. Eighty-five patients [61 male], median age 14.1 years, median weight 50 kg, underwent implantation of 92 BeGraft Aortic stents, 71 (84%) through a 9 Fr sheath. CoA diameter increased by 170% (IQR 150%-270%) and pressure gradient decreased by 16 mmHg (IQR 10-23 mmHg) to a median of 4 mmHg (IQR 0-6 mmHg). Final stent-to-balloon diameter ratio was 0.94 ± 0.05 (5.6% recoil, IQR 2.8%-9.4%). During median follow-up of 2.7 years (IQR 1.0-4.3 years, max 7.3 years), 38 patients underwent re-imaging (CT, angiography), which demonstrated two new aneurysms. Eight aneurysms present prior to BeGraft aortic implantation completely resolved, and one patient had an asymptomatic femoral artery occlusion. Of the 24 patients who underwent additional catheterizations, 19 had re-interventions, 13 balloon dilations, and 6 stent implantations: 10 restenosis, 7 somatic growth, and 2 aneurysms. In this single-center experience, BeGraft Aortic covered stents were associated with favorable technical results, including minimal stent recoil and low rates of reintervention for restenosis or aneurysm formation. The low-profile delivery system affords treatment of CoA for smaller children with low risk for vascular damage.

In this paper, aiming at the aging problem of rubber sealing strips in key parts of hydropower units under long-term load, this study proposes a quantitative aging-feature-extraction technique centered on the ratio of the short-axis length to the original diameter (b/D) of serviced rubber strips. Through a systematic approach combining theoretical analysis, numerical simulation, and measured data calculations, the research first derives from energy principles that the elastic modulus (E) and yield stress (σs) are key physical parameters characterizing rubber aging, reflecting the material's energy storage capacity and irreversible deformation threshold, respectively. Based on this, a radial compression simulation model of rubber strips is established, focusing on the cross-sectional deformation laws under 25% and 30% compression ratios in serviced conditions. It is found that the short-axis diameter ratio b/D exhibits a significant linear relationship with the dimensionless yield stress (σs/E), and a quadratic relationship with the dimensionless unit-length reaction force (F/ED). Using measured data, fluororubber (FKM) and nitrile rubber (NBR) specimens after 17 years of service are selected for radial compression experiments to extract the elastic modulus. The calculated results are compared with elasticity modulus estimates based on hardness empirical formulas (Gent's and Qi's formulas), showing consistency, particularly with Qi's formula for NBR. This method enables rapid and accurate assessment of rubber aging, demonstrating the effectiveness and practicality of using b/D as a feature parameter. The study provides a quantitative and convenient tool for condition monitoring and life prediction of industrial equipment seals, especially suitable for the operation and maintenance of rubber components in complex environments such as hydropower units.

Continuous aerobic granular sludge activated by a contracted final settler and associated hydraulic measures.

Evaluating the vertical bearing capacity of offshore wind turbine pile-ring composite foundations under complex marine environmental loads is critical for ensuring engineering safety. This study employs the rigorously validated T-EMSD upper-bound method to conduct a three-dimensional numerical analysis of the vertical bearing capacity of pile-ring composite foundations in saturated clay. It systematically investigates the influence of soil homogeneity (η, diameter ratio (D/B), embedment ratio (L/B), and external shaft friction coefficient (α) on the bearing capacity factor Nc, and reveals the associated failure mechanism through velocity field analysis. The results indicate that the bearing capacity factor Nc increases significantly with the diameter ratio D/B. The system exhibits optimal bearing performance when the pile shaft friction is fully mobilized (α = 1) in homogeneous soil (η=1). Moreover, as the embedment ratio L/B increases, the plastic zone extends downward along the pile shaft, enhancing the deep foundation effect. Based on parametric analysis, a predictive formula for the net bearing capacity factor of the pile-ring composite foundation under homogeneous conditions is established. Verified against existing numerical methods and experimental data, the formula demonstrates an error margin within ±5%, indicating its good suitability for engineering applications. Furthermore, by establishing a ratio relationship, the net bearing capacity factor under heterogeneous conditions is correlated with that under homogeneous conditions. This enables a more in-depth analysis of the influences of soil strength heterogeneity and external shaft friction coefficient on the vertical bearing capacity of the pile-ring composite foundation. The work presented in this paper provides a theoretical basis for the design and bearing capacity assessment of this type of composite foundation.

The Aluminum 1100 series is widely used because of its high corrosion resistance and ductility. Joining aluminum by conventional welding is challenging due to its poor weldability. Friction Stir Welding (FSW) is a solid-state joining process in which heat is generated by the tool's rotation pin and shoulder rubbing against the material to be welded, stirring it. The FSW process can reduce welding issues when joining aluminum materials. The quality of the joint formed by friction stir welding depends on the welding parameters, as evidenced by numerous prior investigations. However, previous research has been limited to mechanical strength of welded joints, using destructive testing methods. This allows researchers to examine the quality of welded joints using nondestructive testing. Researchers focus on investigating the quality of friction stir welding joints on an AA 1100 thin plate. The tool used has three flat sides, with a tool pin and shoulder diameter ratio of 1:3. The parameters used were variations in the tool's lateral tilt angle, with values of 0º, 0.5º, and 1º. The travel speed was 45 mm/minute with a tool rotation of 1860 rpm. The clamp/fixture was made of S45C, a heat-treated material; the backing plate was mild steel. The AA 1100 material, thicker than 2 mm, undergoes welding. The quality of FSW joints was inspected using nondestructive testing methods, including visual, radiographic, and eddy-current testing. In contrast, mechanical strength was assessed by tensile testing to validate the nondestructive test. The results indicated that tilt angle 0º had no defects, tilt angle 0.5º had tunneling or voids, and tilt angle 1º had defects in the form of a lack of material. When the tilt angle was changed to 0º, the tensile strength was 85.53 MPa, and the joint efficiency was 78%. When the tilt angle was set to 0.5º and 1º, the tensile strength dropped to 61.84 MPa and 71.91 MPa, respectively.

Using direct numerical simulations, this paper presents the first comprehensive investigation of the three-dimensional flow characteristics for a large array of cylinders in steady current, by systematically varying the array arrangement through the number of cylinders in the range N = 1–109, gap ratio G/d (1.2–14.7, G is the center-to-center distance between two adjacent cylinders, d is the cylinder diameter), array-to-element diameter ratio D/d (7.3–48.6, D is the array diameter), incident flow angle θ (0°, 90°), and the uniformity of the array. The three-dimensional flow field both within and behind the array is shown varying widely with gap ratio, array-to-element diameter ratio, incident flow angle, and the uniformity of the array, which demonstrates the influence of array arrangement. Physical mechanisms for the effects of G/d, D/d, θ and non-uniformity are interpreted. The arrangement effects become most critical in the intermediate range of flow blockage parameter ΓD= 0.8–3 (ΓD=aD/1−ϕ, where a is the frontal area per unit volume, and ϕ is the solid volume fraction). The flow three-dimensionality arises from the wakes of individual cylinders (element wake) and the array wake behind the array at low and high values of ΓD, respectively, and from both wakes at the intermediate range of ΓD. A transition from element-wake into array-wake three-dimensionality occurs as array shear layers are susceptible to shear layer instability while quasi-two-dimensional spanwise vortices form within the array. Across arrangements modeled, it is confirmed that the extent of flow three-dimensionality is, to first order, controlled by flow blockage parameter as this parameter controls the bleeding velocity that largely determines the extent of three-dimensionality.

Residual stress networks offer a powerful means to enhance mechanical properties, but controlling them at the nanoscale remains challenging. Here, we introduce a method to create prestressed tensegrity-inspired nanoarchitectures, i.e., nano-tensegrities, by exploiting a previously uncharacterized size-affected shrinkage phenomenon. We discover that the shrinkage of acrylate-based polymers during pyrolysis has a power-law dependence on size. This size-effect arises due to increased residual oxygen-containing groups in larger-dimension specimens. Leveraging this effect, we use two-photon lithography to fabricate polymer structures with thicker "bar" and thinner "tendon" members and pyrolyze them to create prestressed glassy carbon nano-tensegrities. Using combined experiments and numerical modeling, we demonstrate pyrolyzed structures retain their designed state of prestress, which can then be precisely controlled by tuning the bar-to-tendon diameter ratio. Prestress is shown to considerably enhance stiffness - up to a two-and-a-half-fold increase in the structures studied here - but can lead to buckling in excessively stressed slender members. We evaluate the effect of architecture and slenderness on the limits of prestressability and analyze corresponding changes in mechanical performance. This work establishes a method to precisely program 3D residual stress into metamaterials at the nanoscale, enabling a new class of mechanically tunablenanoarchitectures.

Background: Targeted muscle reinnervation (TMR) is an emerging surgical technique that reroutes severed peripheral nerves to nearby motor targets to prevent symptomatic neuroma formation and reduce amputation-related pain. This case series evaluates the effectiveness of TMR in managing symptomatic neuromas following digit and hand amputations and reports postoperative outcomes and complications. Methods: Seventeen patients with traumatic or surgical digit/hand amputations distal to the wrist crease presenting with symptomatic neuromas were prospectively enrolled between August 2021 and August 2023. Patients underwent either primary TMR at the time of amputation or secondary TMR following neuroma formation. Surgical technique involved microsurgical coaptation of transected sensory nerves to adjacent motor entry points under loupe or microscopic magnification. Outcomes assessed included operative time, pain recurrence, phantom limb pain (PLP), narcotic usage and upper limb function measured by the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire. Results: Primary TMR was performed in 13 patients and secondary TMR in 4 patients. The mean operative time was approximately 90 minutes. All nerve transfers maintained a sensory-to-motor diameter ratio of less than 2:1. Postoperative neuroma-related pain occurred in only one patient due to a slipped suture, which was successfully revised. PLP was reported in three patients, resolving within 2 months in all cases. Narcotic and neuromodulator medication use was required transiently in three patients, with complete cessation achieved by 2 months postoperatively. The mean DASH score was 21 ± 8, indicating mild overall disability and good overall hand function. Conclusions: TMR demonstrates significant promise as an effective intervention to reduce symptomatic neuroma formation and associated pain following digit and hand amputation. Successful implementation requires detailed knowledge of hand microsurgical anatomy and expertise in nerve coaptation techniques. Further studies with larger cohorts and longer follow-up are warranted to validate these findings and optimise patient selection. Level of Evidence: Level IV (Therapeutic).

Offshore pipelines are crucial for transporting fluids from offshore platforms to onshore processing facilities. However, these pipelines are susceptible to damage from third-party activities, such as collisions with ship anchors. An inspection revealed a dent in the pipeline with a depth of 111 mm, resulting in a dent depth to outside diameter ratio of 31.21%. According to various regulatory codes, this ratio indicates failure. Despite this, no leaks or ruptures were observed during the inspection. To assess the pipeline's integrity, finite element analysis (FEA) using Abaqus was conducted to determine the maximum stress in the dented area. The analysis produced a graph illustrating the relationship between stress and the allowable operating pressure of the pipeline.

The inertial migration of a neutrally buoyant sphere in pipe Poiseuille flow is examined using numerical simulations. Three migration regimes are observed with increasing Reynolds number ( ${\textit{Re}}$ ): monotonic convergence to the equilibrium position, overshooting convergence and damped oscillations. The critical Reynolds numbers separating these regimes decrease with the sphere-to-pipe diameter ratio, $d/D$ . The axial entry length, $L_{p}$ , required for the sphere to reach equilibrium decreases with both ${\textit{Re}}$ and $d/D$ in the monotonic regime, but increases in the oscillatory regime. These results elucidate the dynamics of inertial migration and inform strategies for manipulating particles in confined, particle-laden flows.

This study evaluated the safety and efficacy of individualised interventional strategies in paediatric pulmonary arterial hypertension, focusing on the outcomes of atrial septostomy, reverse Potts shunt, and partial ASD closure in patients unresponsive to medical therapy or with rapid right ventricular deterioration. A retrospective analysis included 12 paediatric patients who underwent 18 interventional procedures between 2019 and 2024. Pulmonary arterial hypertension was confirmed by right heart catheterisation, and pre- and post-procedural clinical, echocardiographic, and haemodynamic data were compared. Interventions included graded balloon atrial septostomy (n = 10), partial ASD closure (n = 2), and reverse Potts shunt via ductal stenting (n = 1). All surviving patients showed clinical improvement with significant reductions in heart rate (p < 0.01), NT-proBNP (p = 0.008), mean right atrial pressure (p < 0.001), and RV/LV end-diastolic diameter ratio (p = 0.014), along with improvements in six-minute walk distance (p = 0.002), WHO functional class (p < 0.001), and TAPSE (p = 0.028). One patient (8.3%) died within days following atrial septostomy due to nonadherence to medical therapy. Three patients required repeat atrial septostomy because of shunt restriction or spontaneous narrowing. Individualised interventional strategies guided by comprehensive haemodynamic assessment can slow disease progression and improve quality of life in paediatric pulmonary arterial hypertension. Partial ASD closure, as a novel approach in this cohort, reduces excessive left-to-right volume load while preserving a controlled right-to-left shunt, thereby enhancing haemodynamic stability and optimising outcomes. Timely implementation of interventional strategies before disease progression may help reduce mortality.

Pediatric adenotonsillectomy frequently requires Boyle-Davis mouth gag placement, which may transiently increase intracranial pressure (ICP). Ultrasonographic optic nerve sheath diameter (ONSD) is a validated noninvasive marker of ICP. This study aims to investigate the impact of endotracheal intubation and Boyle-Davis mouth gag placement on ONSD, eyeball transverse diameter (ETD), and ratio of optic nerve sheath diameter to eyeball transverse diameter (ONSD/ETD) ratio in children. In this prospective observational study of 120 children (American Society of Anesthesiologists I-II, 2-18 years), bilateral ONSD and ETD were measured at post‑induction (T0), post‑intubation (T1), post‑gag placement (T2), and post‑gag removal (T3). Unadjusted profiles used repeated-measures ANOVA. Adjusted analyses used linear mixed-effects models with time and random intercept for subject; end-tidal carbon dioxide (EtCO2) and mean arterial pressure (MAP) were entered as time-varying covariates. Means (±standard deviation) for ONSD were 5.74 ± 0.46 (T0), 5.79 ± 0.46 (T1), 5.86 ± 0.44 (T2), 5.77 ± 0.48 (T3); for ONSD/ETD: 0.251 ± 0.021, 0.252 ± 0.020, 0.255 ± 0.020, 0.249 ± 0.021. The overall time effect was significant for both outcomes (P < .01). In adjusted models, T2 versus T0 remained higher for ONSD (+0.108 mm; 95% confidence interval (CI): 0.046-0.170; P < .001) and ONSD/ETD (+0.0033; 95% CI: 0.0003-0.0063; P = .03), whereas MAP was not significant and EtCO2 showed a modest positive association with both outcomes (ONSD: +0.007 mm/mm Hg; 95% CI: 0.002-0.012; P < .01). Heart rate and MAP varied over time (both P < .001), EtCO2 rose early and declined by T3 (P < .001). No neurologic events occurred. Mouth-gag suspension produces a small, transient rise in ONSD and ONSD/ETD that peaks at T2 and recedes after removal. Effects persisted after adjustment for EtCO2 and MAP, primarily suggesting contributions from positioning and suspension rather than hypercapnia. Findings support prudent positioning and monitoring in at‑risk children.

The permeability of tree-like branching networks has long been a focus of academic research in fractal theory. Based on fractal theory, this study develops a permeability model for a damaged tree-like branching network that accounts for the influence of surface roughness. By incorporating key parameters such as relative roughness, damage degree, and number of branching levels, the model systematically characterizes the impact of the microstructure on fluid seepage. Meanwhile, based on fractal theory, this study derives a fractal model for the dimensionless permeability of a porous medium composed of spherical particles and randomly distributed, rough tree-like branching networks embedded within it. Furthermore, the model incorporates an equivalent structure featuring conical corrugated pipes with expansion and contraction characteristics, systematically revealing the intrinsic relationships between the dimensionless permeability and key microstructural parameters such as porosity, fractal dimension, length ratio, diameter ratio, bifurcation angle of the branching network, and relative roughness. It is important to note that for porous media composed of conical pipes, as the inner diameter ratio increases, the dimensionless permeability decreases accordingly. This rule conforms to the physical laws in the field of fractal theory. Research suggests that randomly distributed, rough, and damaged tree-like branching networks can enrich and advance the physical studies of fluid flow in porous media.

To analyze the demographic and clinical features of sialolithiasis based on a large sample size. Clinical and imaging data of patients with sialolithiasis treated at the Sialendoscopy Center of Peking University School and Hospital of Stomatology from January 2020 to December 2024 were retrospectively collected. Patient demographics, disease duration, and affected glands were recorded. Moreover, the number, size, location, and long-to-short diameter ratio of the stones were mea-sured. A total of 1 812 patients with salivary gland stones were collected, including 855 males and 957 females. The age range was 4 to 97 years [mean: (39.0±15.0) years] with a median disease duration of 6.0 months (interquartile range: 1.0-24.0). Most stones involved unilateral glands (98.4%), and 64.2% of the affected glands had a single stone. The stone size averaged at a diameter of (6.5±4.6) mm. The cases included 1 541 cases with submandibular gland (SMG) stones (85.0%), 267 cases with parotid gland (PG) stones (14.7%), and 4 cases affecting both SMG and PG. The SMG stones were mostly located in the extra-glandular main duct (50.2%), followed by the hilum (41.5%), and only 8.2% of them were in the intra-glandular area. The majority of PG stones (75.2%) were in the extra-glandular main duct. The average diameter of SMG stones was significantly larger than that of PG stones [(6.9±4.8) mm vs. (4.5±2.5) mm]. The average age of SMG patients was younger than that of PG patients [(38.0±15.0) years vs. (48.0±16.0) years]. There was no significant difference in recurrence rate between PG and SMG stones (3.4% vs. 2.1%). The recurrence intervals ranged from 2 months to 10 years, with an average of (33.8±31.4) months. In 21 patients (1.2%), the stones originated from foreign body calcification, which accounted for 0.6% (9/1 541) of SMG cases and 4.5% (12/267) of PG cases. Among the cases analyzed, sialolithiasis was the most common in middle-aged individuals, with no significant gender difference. Unilateral gland involvement was the most frequent, and 2/3 of the cases had a single stone. Significant differences were observed in the location, size, and patient age between SMG and PG stones. The recurrence rate of sialolithiasis was relatively low. Stones originated from foreign body calcification was occasionally seen. Understanding of these demographic and clinical characteristics provided a basis for clarifying the pathogenesis of sialolithiasis and optimizing the diagnostic and therapeutic strategies.

Abstract This study examines the elastic–plastic contact behavior between two hemispheres under varying diameter ratios, with a focus on the influence of base flexibility. The finite element method is used to analyze both rigid and deformable base conditions. Brass, which possesses elastic-perfectly plastic properties, is the material used in this study. The upper hemisphere has a constant diameter, whereas the lower hemisphere has a variable diameter. The results show that deformable bases exhibit greater lateral displacement and can distribute stress uniformly, thereby reducing peak stress zones. The deviation in maximum contact pressure between the deformable and rigid bases remains below 1% at low loads (≤ 1 kN), when the load increases to approximately 19% (DR1, 30 kN), 48% (DR2, 30 kN), 12% (DR4, 10 kN), and 16% (DR7, 6 kN) at higher loads. The maximum von Mises stress for DR7 also increases by approximately 37%, confirming that the stress is sensitive to base compliance. In contrast, rigid bases focus stresses within a narrower region, which may increase the risk of local failure. A convergence study ensures mesh reliability, and the results are validated against established models. Based on the findings from this study, it can be concluded that base flexibility plays a crucial role in stress redistribution, particularly at high diameter ratios. This study provides practical insights into the structural and mechanical systems subjected to localized contact, including forming dies and medical implants. The outcomes of this study contribute to improving durability and reliability in contact-based devices. However, the present analysis is limited to static loading and elastic–perfectly plastic material behaviour, without considering time-dependent or thermal effects, which will be addressed in future studies.

As the demand for cleaner-greener energy surges owing to more nations adopting Net Zero Emission by 2050, wind turbine (WT) technology is increasingly poised as one of the technologies to match the demand. Capacity building in the development of cost-effective WT tower with improved reliability and safety has become critical to delivering Net Zero mandate. This research demonstrates implementation of Taguchi Design of Experiment (DoE) in conjunction with Signal-to-noise ratio (S/N) to optimise both structural design parameters and material cost of a 90 m tower of a standard 5 MW WT tower subjected to adverse wind conditions. Nine Computer Aided Design tower models are generated from Taguchi design at constant shell volume. Deflection, stress and buckling responses of the models to applied environmental loads are simulated using ANSYS mechanical package. Results are validated with analytical method. Responses of the models are compared with the standard model. Model 1, made of steel grade S275, 95 mm wall thickness and 0.45 top-to-bottom diameter ratio, is found optimal. It deflects 9.3% less, accumulates 7.62% less stress, shows higher resistance to buckling and costs 8.2% less. The methodology adopted in this work is well suited to preliminary design stages, where design flexibility is high and cost decisions are most influential, and it contributes to capacity building in wind turbine tower technology to support technological advancement towards Net Zero.