Design Limits Research Articles

High-resolution atlas of extreme wave height and relative risk ratio for US coastal regions

Interest in marine energy development has motivated numerous studies on extreme wave conditions to characterize wave loads and project risks. Metrics on extreme wave conditions, including extreme wave height, are limited in nearshore regions by insufficient spatiotemporal coverage and resolution of wave data. This study estimates 1-, 5- and 50-year return period significant wave heights, and relative-risk-ratios computed by non-dimensionalizing these extreme wave heights with their mean values, for US nearshore regions using 32-year regional SWAN wave hindcasts with spatial resolutions of 200-300 m. The model-derived extreme wave height estimates are systematically biased lower than buoy-derived estimates, but are well correlated enabling simple bias correction to buoy-observations. As wave heights at shallow nearshore sites are physically limited by depth-induced wave breaking, model-derived extreme wave height estimates are replaced with estimates using common empirical models based on breaking depth limits. The corrected high-resolution extreme wave height and relative risk ratio atlas generated herein provides important metrics that support resource characterization for the marine energy industry, including resource and site assessment, and the establishment of upper design limits for device type classification and certification to streamline product line development.

Multi-Objective Optimization of Three-Stage Turbomachine Rotor Based on Complex Transfer Matrix Method

This study presents the complex transfer matrix method (CTMM) as an advanced mathematical model, providing significant advantages over the finite element method (FEM) by yielding rapid solutions for complex optimization problems. In order to design a more efficient structure of a three-stage turbomachine rotor, we integrated this method with various optimization algorithms, including genetic algorithm (GA), differential evolution (DE), simulated annealing (SA), gravitational search algorithm (GSA), black hole (BH), particle swarm optimization (PSO), Harris hawk optimization (HHO), artificial bee colony (ABC), and non-metaheuristic pattern search (PS). Thus, the best rotor geometry can be obtained fast with minimum bearing forces and disk deflections within design limits. In the results, the efficiency of the CTMM for achieving optimized designs is demonstrated. The CTMM outperformed the FEM in both speed and applicability for complex rotordynamic problems. The CTMM was found to deliver results of comparable quality much faster than the FEM, especially with higher element quality. The use of the CTMM in the iterative optimization process is shown to be highly advantageous. Furthermore, it is noted that among the different optimization algorithms, ABC provided the best results for this multi-objective optimization problem.

Exploring Unique Patterns of Self-Injury Recovery: A Latent Profile Analysis.

As nonsuicidal self-injury (NSSI) has become an increasing public health concern, the last few years have seen the emergence of efforts to address NSSI recovery. Although many recovery efforts adopt a medical view of self-injury and focus on cessation of the behaviour, recovery can mean many different things to different people. In this study, we provide initial empirical validation of the self-injury recovery framework, by assessing whether different recovery profiles exist. Our sample comprised 733 participants with lived experience of NSSI (M age = 24.54, sd = 6.39). Participants completed self-report measures of constructs related to NSSI recovery and NSSI characteristics. Using latent profile analysis, we identified six unique profiles reflecting differences in thoughts/urges to self-injure, self-efficacy, social support, optimism, coping, underlying adversities, perceptions of scarring, disclosure, resilience and self-compassion. Multivariate analyses of variance confirmed these profiles differed according to NSSI characteristics such as frequency of NSSI, a self-assessment of recovery, the desire to self-injure or avoid self-injury and the number of people disclosed to. A homogenous sample and cross-sectional design limit generalisability of our findings across populations and across time. Our findings reinforce that recovery can take many different forms, with different factors being relevant to different individuals. Adopting a person-centred approach that centres an individual's lived experience and emphasises what is important to them in the recovery process offers opportunities for more empathic responses to self-injury and better outcomes for individuals who self-injure.

When toxicity is not just from gluten: a systematic review on financial toxicity and celiac disease

Abstract Background With an incidence of up to ∼2% globally, Celiac Disease (CD) is probably one of the most life-long common chronic conditions. Although ‘Financial toxicity’ (FT) has been mainly linked to oncology, significant financial burdens have been described across all healthcare domains, even in CD and to the unexpected economic effort resulting from illness and the need for treatments. This study aimed to investigate the potential relationship between CD and FT. Methods A systematic literature review was performed according to the PRISMA Statement 2020 guidelines. The search query queried the following databases: PubMed, Scopus, CINAHL and APA PsycInfo. No time and study design limits were included. Results 105 articles were found, and 25 were included in the review. The main results revealed that CD impacts physical health and imposes a significant financial burden on patients and their families. FT in CD is primarily due to the high costs of diagnosis, lifestyle changes, and expenses for gluten-free foods. Several studies highlighted the scarce adherence to the therapeutic diet due to the cost of food and poor acceptance of CD. Furthermore, since 2007, there has been increased attention to the difficulty of finding gluten-free products and their expensive fees. All these aspects, even for low-income countries, were faced differently globally, as documented by the heterogeneity of government subsidy policies highlighting the health inequity. Conclusions Considering the prevalence, a comprehensive health assessment with a global health approach should consider clinical, social, and economic aspects. This regard could improve the quality of life for CD patients and ensure fair and personalised access to care, regardless of their geographical location or financial situation. This review has highlighted the fragmentation of resources available internationally, underlining the relevance from a public health point of view. Key messages • Celiac Disease is one of the most common life-long disorders, and financial toxicity is an aspect that should be taken into account also from a public health point of view to ensure health equity. • The gluten-free diet represents an important therapeutic choice in CD; the related expensive fees could increase scarce adherence and worse health outcomes.

Evaluation of Reusable Thermal Protection System Materials Using a High-Velocity Oxygen Fuel Torch.

We studied a candidate TPS (thermal protection system) material for reusable re-entry space vehicle applications. The material was based on a high-temperature-resistant material called Cerakwool. A total of six specimens were fabricated with substrate densities of 0.45 g/cm3, 0.40 g/cm3, and 0.35 g/cm3, with two specimens for each density. All specimens were coated with high-emissivity TUFI (toughened unpiece fibrous insulation), with coating thicknesses ranging from 445 to 1606 µm. The specimens were tested using an HVOF (high-velocity oxygen fuel) material ablation test facility. For each density specimen pair, one specimen was tested at 1 MW/m2 and the remaining one was tested at 0.65 MW/m2. The average stagnation point temperature for specimens tested at 1 MW/m2 was ~893 °C, approximately 200 °C higher than those tested at 0.65 MW/m2. This suggests a ~200 °C increase in stagnation point temperature for a 0.35 MW/m2 rise in incident heat flux. During the tests, internal temperatures were measured at three locations. For all tested specimens, regardless of heat flux test conditions and density, the temperature at ~40 mm from each specimen's stagnation point remained around or below 50 °C, well within the 180 °C design limit set for the TPS back face temperature. Post-test visual inspections revealed no signs of ablation or internal damage, confirming the material's reusability.

Kidney complications in children with bronchopulmonary dysplasia.

To describe kidney outcomes in a cohort of children with bronchopulmonary dysplasia (BPD). We assessed short-term (acute kidney injury defined using neonatal KDIGO criteria) and long-term kidney outcomes, including chronic kidney disease (defined as a GFR < 90 ml/min/1.73 m2), albuminuria, and hypertension in a single-center retrospective cohort of children with BPD born between 2010 and 2020. 309 (38.8%) of 797 children included in the cohort had acute kidney injury (AKI) during their NICU admission. Kidney specific follow-up evaluation was infrequent in this cohort; 52.4% of patients had serum creatinine testing and 31.5% had a urinalysis performed after discharge. 163 (32.0%) of 510 patients with long-term data had CKD, which occurred at a median age of 2.2 years. An abnormal eGFR occurred in 31.7%, proteinuria in 12.5% and hypertension in 15.2%. Children with BPD had high frequencies of AKI and CKD. While the retrospective nature and single-center convenience cohort design limit generalizability, our findings suggest that children with BPD should be carefully monitored for short- and long-term kidney outcomes, including CKD. Children with bronchopulmonary dysplasia (BPD) may have a higher likelihood of both acute and chronic kidney complications than currently recognized. Kidney outcomes in children with BPD is an area that remains underexplored. To our knowledge, this is the first study exploring the prevalence of CKD in a cohort of children with BPD. Our findings suggest children with BPD have high rates of kidney complications in early childhood. Increased attention should be placed on monitoring children with BPD for both short- and long-term kidney outcomes.

Generating optimal reloading patterns for CNPGS Unit-3 core using multi-objective elitist teaching-learning-based optimizer

Pressurized Water Reactors (PWRs) management presents the core reloading pattern optimization as a significant problem that contributes to the improvement of reactor productivity and optimal fuel utilization with considering safety conditions. In present study, Multi-Objective Elitist Teaching-Learning-Based Optimization (MO-ETLBO) technique is suggested to cope up the multi-objective reloading optimization problem of the Chashma Nuclear Power Generating Station (CNPGS) unit-3 core. A multivariable objective function is designed to evaluate the quality of each loading pattern while maximizing critical boron concentration (CBC), minimizing the power peaking factor (PPF), and optimally enhancing the cycle length while ensuring adequate safety margins and design limits. It has been found that the equilibrium cycle can be extended to 16.07 extended full power days (EFPDs) while maintaining the PPF and CBC within design limits. To validate the effectiveness of TLBO, the optimized loading pattern of the equilibrium core was evaluated using the deterministic computer code DONJON5, for neutronic parameter analysis. The results show that the algorithm proposed in this study is a promising approach for reloading pattern optimization in CNPGS unit-3, offering potential improvements in reactor cycle length while ensuring safety and enhancing overall performance.

Unique Gut Microbiome and Metabolic Profiles in Chinese Workers Exposed to Dust: Insights from a Case-Control Study.

This study aimed to identify distinct gut microbiome and serum metabolic features in workers exposed to dust compared to healthy controls. A case-control study was conducted with dust-exposed workers without silicosis and age-matched healthy controls. Gut microbiome composition was analyzed using 16S rRNA sequencing, and serum and fecal metabolomic profiles were assessed by LC-MS. Dust-exposed workers showed higher levels of Blautia and Trichoderma and lower levels of Anaplasma, Aspergillus, Plasmodiophoromycetes, and Escherichia coli-Shigella. Metabolites such as indole-3-acetate and gentamicin C1a were downregulated, while adenine, 2-phenylacetamide, and 4-pyridoxic acid were upregulated. Blautia spp. were linked to altered metabolites in dust-exposed workers, suggesting microbiome-metabolite interactions that may affect silicosis progression. However, the small sample size and cross-sectional design limit generalizability, and further longitudinal studies are needed.

Pushing boundaries in slurry microtunneling: Innovations in microtunnel boring machine design for hard rock conditions

AbstractFor microtunneling in hard rock, as it is encountered very often in alpine tunneling, the continuous further development of technologies plays a key role to overcome the limitations in drive length and to improve performance. During the last decades, the application range of slurry microtunneling has been considerably extended and more demanding projects have been designed for underground utilities installations worldwide, including many sewage tunnels and hydropower plants. The prevailing ground conditions still play a key role and determine the limits for alignment design and the possible use of trenchless construction methods. In hard rock conditions with high rock strength and/or abrasivity, the applicability of slurry microtunneling has been especially limited in the non‐accessible diameter range in the past. With the new AVN 800 HR for hard rock microtunneling, Herrenknecht has developed a machine concept, enabling drives of up to 200 m, with precise steering of the MTBM. Longer drives, even through hard rock, make microtunneling a more economic, flexible, and more environmentally friendly construction method. New opportunities for clients and consultants in the planning of tunnel routes in alpine environments for different infrastructure installations can be considered, making trenchless installations even more cost‐effective, while improving public acceptance.

Liquefaction and reliquefaction mitigation of sand specimen treated with prefabricated vertical drains: An experimental investigation

This study examines the performance of prefabricated vertical drains (PVD) against liquefaction and reliquefaction. A series of 102 shakings were performed using 1g shaking table apparatus on untreated and treated sand specimens prepared with 25% relative density. Sinusoidal waveform experimented with three different repeated shaking patterns and independent events for two different frequencies (2 Hz and 3.5 Hz) with 1-min duration. Two different installation methods; drainage alone method (PVD-D) and drainage along with densification (PVD-DD) were experimented. Durability of PVD were examined from geotextile tensile testing apparatus and digital image correlation. These experiments demonstrated excellent durability characteristics of PVD filter even after exposed to repeated shakings. Treated specimens improved the resistance to reliquefaction due to radial drainage offered by PVD which has retarded the excess pore pressure (EPP) generation. In addition, densification induced during the installation of PVD also contributed for restricting EPP, however, the induced sand densification achieved during repeated shaking events were not responsible for increased resistance against liquefaction/reliquefaction. Results indicate that the maximum pore pressure ratio in treated specimens were restricted within threshold design limit (≤0.60) for most of the events, even when the untreated specimens completely liquefied or generated a maximum value near unity.

Development of a thermal diagnostic system for the SPARC tokamak.

The SPARC tokamak will have scrape-off layer parallel heat fluxes on the order of GW/m2. Managing power exhaust of this magnitude will be mandatory for a reactor-scale device. To enable this mission, a thermal diagnostic suite will be deployed to measure the in-vessel structural temperatures to ensure they do not exceed their design limits and to determine the spatial distribution and magnitude of energy deposited onto the first wall. Thermocouples and fiber Bragg gratings have been selected for their environmental compatibility and proven useful on other fusion devices. High-density thermocouple arrays in the divertor will have two spring-loaded thermocouples per divertor target tile, which are being used as calorimeters, and will look to resolve the temperature distribution within the tile due to a swept or static strike point. All systems will need to survive the vacuum vessel bake, set at a minimum plasma facing surface temperature of 350 °C, which presents a particularly challenging environment for the fiber-based subsystem. Along with this temperature design requirement, all the materials in the primary vacuum need to be ultra-high vacuum compatible, able to handle the expected neutron and gamma radiation, as well as tritium exposure, all of which restrict material options. Finally, due to the expected activated environment in SPARC, there will be little chance to replace defective sensors, so system resilience is ensured through toroidal redundancy, probe material selection, and mitigating the impact of common-mode failures. Initial testing of sensors show that intershot structural measurements are sufficiently captured with the raw output, but intrashot measurements of the plasma facing material requires model-based interpretive tools.

Spectral and spatial resolution of an extreme ultraviolet broadband imaging spectrometer based on dispersion-matched zone plates

We present a combined 1D imaging and broadband spectroscopy tool for analyzing laser-produced plasma sources of extreme ultraviolet light using a tapered zone plate that is dispersion-matched to a transmission grating. Specifically, we follow up on prior work [Mostafa et al. Opt. Lett. 48, 4316 (2023)] to obtain the actual spectral and spatial resolution of the imaging spectrometer and compare it to the design values. The imaging spectrometer is shown to have a spectral resolution of 1.2 nm at 13.5 nm, close to its design value, by assessing spectra obtained from carbon laser-produced plasma in a 5–180 nm wavelength band. The spatial resolution was obtained by placing slits near the object plane and back-illuminating the slit with a tin laser-produced plasma and found to be 17(5) µm, somewhat larger than the design specifications but still well within design limits for use for diagnosing plasma.

Application of Low Modulus CFRP Fabric for Steel Beams Strengthening: Experimental and Design Validation

This paper presents experimental results of steel beams strengthened with low-density and low-modulus CFRP fabrics, with the objective of, (i) checking the capability of the fabric type CFRP in strengthening; (ii) assessing and understanding the failure modes for design improvement; and (iii) validating the design methods for the practical application. A total of eighteen full-scale 2.5-meter-long beams strengthened with CFRP were tested. The governing failure modes of the CFRP-strengthened steel beams were debonding, rupture, and wrinkling. The experimental moment capacities were compared with the design predictions using the limit state suggested in the ACI guideline and two new design limit states. The comparison of design predictions indicated that the use of the limit state suggested in the ACI guideline unconservatively predicted the design moment capacity while the two new design limit states were conservative. Further, it is evidently assessed that the low modulus CFRP fabric can be used for the strength upgrade of the steel beams. A detailed design example is presented for the CFRP-strengthened steel beam using different limit states for a better understanding of the readers.

Comment on, "Longterm outcome and quality of life after CNS cavernoma resection: eloquent vs. noneloquent areas".

The study titled "Long-term outcome and quality of life after CNS cavernoma resection: eloquent vs. non-eloquent areas," by Shoubash et al. (2022) provides crucial insights into the long-term neurological outcomes and quality of life (QoL) in patients following CNS cavernoma resection. Differentiating between eloquent and non-eloquent areas, the study shows that patients generally experience non-inferior QoL, with some differences in physical role functioning. Utilizing the Short Form-12 (SF12) questionnaire at a mean follow-up of 6.5 years, the study's findings are significant for clinical decision-making and patient counseling. However, the study's small sample size and retrospective design limit its generalizability and introduce potential biases. The lack of preoperative QoL assessments further constrains its conclusions. Future research should focus on larger, prospective studies with comprehensive QoL metrics and longitudinal follow-up to better understand the impact of surgery on patient outcomes and improve clinical strategies.

Early clinical drug product shelf-life setting using accelerated predictive stability and metabolite data for impurity qualification: A case study

This case study demonstrates how knowledge of degradation products together with predictions can establish a lean stability strategy using the accelerated predictive stability (APS) principles. Applying all available data for AZD4831, (R)-1-(2-(1-aminoethyl)-4-chlorobenzyl)-2-thioxo-2,3-dihydro-1H-pyrrolo[3,2-d]pyrimidin-4(5H)-one, a reliable predictive model was developed despite minor differences in technical batch tablet compositions. Early forced degradation studies were performed to map potential degradation pathways. The insights from these studies guided the design of an APS study, which in turn inform on a suitable clinical stability program, initial specification and shelf-life. The use of APS predictions of degradants as well as total impurities highlighted at an early stage, when designing the clinical stability program, the opportunity to identify which degradation product that would be shelf-life limiting. Hence, it was possible to guide the development stability activities and set an initial shelf-life of a tablet formulation. The presented study displays the importance of combining several sources of information in drug development, e.g., potential degradation pathways, accelerated stability, stability program design, metabolite data, and specification limits.

Study on Structural Analysis for Design Limit Setting of Carbon Fiber Reinforced Plastic Spacer

Study on Structural Analysis for Design Limit Setting of Carbon Fiber Reinforced Plastic Spacer

Assessment of nominal and off-nominal parameters of a soluble boron free small modular reactor design

Boric acid is traditionally used for reactivity control in pressurised water reactors. However, it increases the rate at which reactor components corrode. This leads to increased operational radioactive waste produced through neutron-activation of corrosion fragments. During reactor operation, radioactive corrosion product deposits, or so-called crud, accumulate on fuel cladding in regions of high burnup. Boron compounds have been detected in such deposits, and they cause axial-offset anomaly, i.e. deviation in axial power prediction. Accumulation of boron-laden deposits can reduce plant efficiency to about 70 % over time. This work presents the design process and analysis of nominal and off-nominal parameters of a soluble boron-free small modular reactor core. The design, and analyses were carried out using CASMO4e, CMSLINK, and SIMULATE3 codes. In addition, a borated variant of the target boron-free core was designed and used as reference. Equilibrium cycles were achieved for both the reference and the boron-free core. The limiting FΔH during the transition to equilibrium was found to be 1.754 and 1.651 for the reference and boron-free cores. The equilibrium FΔH were found to be 1.624 and 1.57 compared to the design limit of 1.7. The hot zero power MTC for the boron-free core at beginning of cycle was found to be –22.67 pcm/K compared to −3.64 pcm/K for the reference. The removal of boric acid made the MTC coefficients more negative and the FΔH lower compared to the reference. The boron-free core had enough rod-worth for power and isothermal defect counteraction and reactor shut down.

Tuning the Spin Transition and Carrier Type in Rare-Earth Cobaltates via Compositional Complexity.

There is growing interest in material candidates with properties that can be engineered beyond traditional design limits. Compositionally complex oxides (CCO), often called high entropy oxides, are excellent candidates, wherein a lattice site shares more than four cations, forming single-phase solid solutions with unique properties. However, the nature of compositional complexity in dictating properties remains unclear, with characteristics that are difficult to calculate from first principles. Here, compositional complexity is demonstrated as a tunable parameter in a spin-transition oxide semiconductor La1- x(Nd, Sm, Gd, Y)x/4CoO3, by varying the population x of rare earth cations over 0.00≤ x≤ 0.80. Across the series, increasing complexity is revealed to systematically improve crystallinity, increase the amount of electron versus hole carriers, and tune the spin transition temperature and on-off ratio. At high a population (x = 0.8), Seebeck measurements indicate a crossover from hole-majority to electron-majority conduction without the introduction of conventional electron donors, and tunable complexity is proposed as new method to dope semiconductors. First principles calculations combined with angle resolved photoemission reveal an unconventional doping mechanism of lattice distortions leading to asymmetric hole localization over electrons. Thus, tunable complexity is demonstrated as a facile knob to improve crystallinity, tune electronic transitions, and to dope semiconductors beyond traditional means.

Ductility‐oriented design of UHPC T‐beams: Mechanical model and design recommendations

AbstractUltrahigh performance concrete (UHPC) has recently become a major focus garnering substantial attention due to its remarkable mechanical properties. UHPC has been increasingly employed across diverse projects in the construction industry. However, the structural ductility of UHPC members has yet to be fully established and is often compromised by the manifestation of the crack localization phenomenon. This paper presents the flexural test results of five T‐beams and introduces a model for predicting the flexural capacity and failure modes of UHPC T‐beams. The model employs the curvature ductility index as a measurement for evaluating and ensuring the member's ductility. The results show that the flexural behavior of UHPC T‐beams can be characterized by four key points representing cracking, reinforcement yielding, crack localization, and post‐localization capacity. The validity of the model is substantiated by experimental data from this study and complemented by test data collected from the literature. The proposed model is then employed to derive ductility‐oriented design limits, including minimum and maximum reinforcement ratios and minimum localization strain capacity. Finally, the paper summarizes the design recommendations and provides a classification of section conditions, reinforcement limits, localization strain limits, adequate ductility range, and the feasible ductile design range.

Rubber compounds made of modified ethylene propylene diene monomer (EPDM) for laminated bearings with excellent anti-peel strength

In order to enhance the design life of laminated rubber bearings in the field of highway bridges in the plateau region, a novel laminated bearing was made by the modified ethylene propylene diene monomer (EPDM) rubber that combines both low-temperature and ageing resistance properties in this work. The modified EPDM also exhibit a high anti-peel strength with reinforced steel plate layer. Experimental and numerical investigations were carried out to evaluate the mechanical properties and failure conditions for the EPDM laminated bearing. The results indicate that the bearing with different shape factors exhibit good mechanical properties, and its key performance parameters such as compressive modulus and shear stiffness meet the requirements of the current specification for highway bridges. Meanwhile, we have established a quantitative relationship between the proportion of void area and the total local shear strain for EPDM laminated bearing, and found that when the proportion of void area reaches more than 32 %, some of the performance indexes of the bearing will exceeds the design limit. The above research results can be used as an important criterion for evaluating the performance of modified EPDM bearings.