bluuebunny/crossref_metadata_2025 huggingface dataset:
Nursing Cost Analysis for Acute Exacerbation of Chronic Obstructive Pulmonary Disease in the Intensive Care Unit
Authors: Mao Haizhou , Chen Zhi , Li Wei , Pang Xinyue , Cao Xinmei , Shi Jiaqi , Zhuang Danwen , Mao Lijie
Published: December 2024

Objective

To determine nursing costs for intensive care unit (ICU) patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD), assess the correlation with diagnosis‐related group (DRG) payments and identify cost determinants.

Design

Prospective, descriptive and quantitative study.

Methods

From January to December 2022, we selected ICU patients with AECOPD and used time‐driven activity‐based costing method to calculate the overall nursing costs. We examined the cost recovery rate, correlations between nursing costs and DRG Relative Weight, and factors influencing nursing costs using nonparametric tests, Spearman's rank correlation and quantile regression.

Results

The median nursing charge was US$1001.88, the median nursing cost was US$678.51, and the average cost recovery rate was 68.39%. Nursing costs correlated with the DRG Relative Weight but not with payments. Length of stay, oxygen therapy mode and noninvasive ventilator use days impacted costs.

Conclusions

Nursing costs exceeded charges, with a moderate cost recovery rate. DRG payments do not fully reflect nursing cost variations.

Relevance to Clinical Practice

Our findings indicate the need to enhance the reimbursement system for nursing costs and to manage ICU nursing expenses by addressing the determinants of these costs.

Reporting Method

The authors adhered to the EQUATOR network guidelines STROBE to report observational cross‐sectional studies.
Symptom Cluster Trajectories Among Patients With Hepatocellular Carcinoma After Partial Hepatectomy: A Longitudinal Study
Authors: Cai Yanxiu , Li Jing , Bi Liuna , Wang Linlin , Han Jing
Published: December 2024

Aims

To investigate types of symptom clusters in patients with hepatocellular carcinoma after partial hepatectomy and explore symptom cluster trajectories over time.

Design

A longitudinal observational study was conducted.

Methods

Symptoms of patients with hepatocellular carcinoma were assessed on the second day, seventh day, third week, fourth week and twelfth week post‐operation using the MD Anderson Symptom Assessment Inventory and the Symptom Module for Primary Liver Cancer. Symptom clusters were extracted using exploratory factor analysis, and symptom cluster trajectories were analysed using a latent class growth model.

Results

Two hundred and thirty patients with hepatocellular carcinoma completed the five‐point investigation after partial hepatectomy. Three symptom clusters were identified: general somatic, psychological and liver impairment. Each symptom cluster was further categorised into three groups: severe, moderate and low. The severity of the three symptom clusters and subgroups decreased over time.

Conclusion

Three symptom clusters were identified in patients who underwent partial hepatectomy for hepatocellular carcinoma, and symptom cluster trajectories decreased over time during the 12‐week postoperative period. These findings will assist healthcare professionals in providing prompt symptom management and improve patient quality of life.

Implications for the Profession and/or Patient Care

Healthcare professionals should evaluate symptom clusters and their trajectories in patients with hepatocellular carcinoma after partial hepatectomy.

Reporting Method

This report was prepared in accordance with the Guidelines for Reporting Cohort Research.

Patient or Public Contribution

Hepatobiliary surgery nurses worked closely with the research team to ensure the questionnaires were fully assessed before being sent to patients. The active participation of patients provided valuable information for the study.

Trial Registration

Chinese Clinical Trial Registry (ChiCTR2400084232)
Trade Policy in a Third‐Country Model With Kantian Optimization
Authors: Wang Leonard F. S. , Wu Di , Yang Can
Published: December 2024

We address the issue of trade policies in a Kantian equilibrium. We find that “in principle” at Kantian equilibrium between the exporting countries, the trade policy is export tax. A Kantian equilibrium between the exporting countries leads to the lowest importing countries' consumer surplus, exporting firms' profits and global welfare, while the social welfare of the exporting countries is the highest. On the contrary, A Kantian equilibrium between the exporting firms leads to the highest importing countries' consumer surplus, exporting firms' profits and global welfare. The stability analysis demonstrates the robustness of our findings within an oligopoly comprising multiple exporters.
Methodological Quality and Content of Guidelines on Early Childhood Allergy Prevention: A Systematic Assessment and Content Analysis
Authors: Sieferle Katharina , Bitzer Eva M.
Published: December 2024

Recommendations on Early Childhood Allergy Prevention (ECAP) are found in Clinical Practice Guidelines (CPG) and Food‐Based Dietary Guidelines (FBDG). This synthesis of guidelines aims to compare the methodological quality and content of recommendations in CPGs and FBDGs for ECAP. We searched MEDLINE, the FAO directory of FBDGs and other guideline databases, including the Association of the Scientific Medical Societies in Germany (AWMF), the WHO and the Guideline International Networks database on clinical guidelines (GIN) for CPGs and FBDGs about ECAP and child nutrition. Guidelines had to be published from 2010 onwards, target infants or pregnant/breastfeeding women and contain recommendations on primary preventative interventions to decrease the onset of IgE‐mediated allergies, including atopic eczema or asthma. We retrieved a sample of 36 guidelines (23 CPGs, 13 FBDGs) and assessed their methodological quality with the Appraisal of Guidelines for Research and Evaluation tool (AGREE) II. On a subset of recommendations, we performed an in‐depth analysis by the type of intervention for direction and strength of recommendation and level of evidence. Descriptive analysis was conducted with SPSS 27. CPGs score higher than FBDGs in most AGREE domains (3, 4, 5 and 6). The 36 guidelines contain 287 recommendations on ECAP, with 70 addressing the introduction of complementary foods and common allergens. We found only slight differences between those recommendations in CPGs and FBDGs. FBDGs on ECAP are of lower quality than CPGs. This does not affect their recommendations on the introduction of complementary foods and common allergens but may compromise their trustworthiness.
Diets, Fruit and Vegetable Intake and Nutritional Status Among Children, Adolescents and Adults in the Philippines: A Scoping Review
Authors: Smith Taryn J. , Hess Sonja Y. , Angeles‐Agdeppa Imelda , Goyena Eva , Gelli Aulo , Olney Deanna K.
Published: December 2024

Suboptimal diets contribute to the risk of malnutrition and non‐communicable diseases across the life course. Globally, intakes of fruit and vegetables (F&V) fall below recommendations, including in the Philippines. To promote F&V intakes, understanding the extent of inadequate intakes across population groups and key drivers of dietary patterns is needed. This narrative scoping review was conducted to map the diet, F&V intakes and nutritional status in the Philippines. PubMed was searched using keywords specific to diet, F&V intake, and nutritional status, with 50, 24 and 22 articles meeting the inclusion criteria for diet, F&V intake, and nutritional status, respectively. Available evidence indicates that across all population and sociodemographic groups, diets lacked diversity, with high intakes of energy‐dense, nutrient‐poor foods, such as refined rice and sugar‐based foods and beverages, contributing to inadequate micronutrient intakes. Intakes of F&V were especially low across all population groups. Stunting/short height, wasting and underweight were prevalent among children and adolescents, and micronutrient deficiencies (iron, zinc, vitamin A) were common among children < 5 years of age. More than one‐quarter of adults were overweight or obese and demonstrated poor cardiometabolic health. A lack of published evidence identified through this search reported on pregnant and lactating women and women of reproductive age. Published evaluations assessing the impact of interventions or programmes to improve diets or F&V intake were limited. Additional research to fill these gaps will help design interventions and target entry points to improve diet diversity and F&V intakes across all population groups.
Parallel Signatures of Diet Adaptation in the Invasive Common Myna Genome
Authors: Atsawawaranunt Kamolphat , Stuart Katarina C. , Whibley Annabel , Ewart Kyle M. , Major Richard E. , Johnson Rebecca N. , Santure Anna W.
Published: December 2024

Invasive species offer uniquely replicated model systems to study rapid adaptation. The common myna (Acridotheres tristis) has been introduced to over a dozen countries and is classified as one of the most invasive birds in the world. Their multiple invasions provide an opportunity to identify repeated adaptation, as invasive populations originated from multiple source populations. We compared whole‐genome resequencing data from 80 individuals from four native and seven invasive populations, representing two independent introduction pathways. Results from two different selection scan methods were combined and identified a strongly selected region on chromosome 8 that spans two copies of AMY2A, part of the alpha‐amylase gene family, a putative ncRNA and an insertion–deletion structural variant (SV) that contains an ERVK transposable element (TE). Outlier SNPs and the SV are polymorphic in native populations, but fixed or close‐to‐fixed in the two invasive pathways, with the fixation of the same alleles in two independent lineages providing evidence for parallel selection on standing variation. Intriguingly, the second copy of AMY2A has a non‐conservative missense mutation at a phylogenetically conserved site. This mutation, alongside variation in the SV, TE and ncRNA, provide possible routes for changes to protein function or expression. AMY2A has been associated with human commensalism in house sparrows, and genes in this family have been linked to adaptation to high‐starch diets in humans and dogs. This study illustrates the value of replicated analyses within and across species to understand rapid adaptation at the molecular level.
Leveraging Transcriptional Signatures of Diverse Stressors for Bumble Bee Conservation
Authors: Quinlan Gabriela M. , Hines Heather M. , Grozinger Christina M.
Published: December 2024

Organisms in nature are subjected to a variety of stressors, often simultaneously. Foremost among stressors of key pollinators are pathogens, poor nutrition and climate change. Landscape transcriptomics can be used to decipher the relative role of stressors, provided there are unique signatures of stress that can be reliably detected in field specimens. In this study, we identify biomarkers of bumble bee (Bombus impatiens) responses to key stressors by first subjecting bees to various short‐term stressors (cold, heat, nutrition and pathogen challenge) in a laboratory setting and assessing their transcriptome responses. Using random forest classification on this whole transcriptome data, we were able to discriminate each stressor. Our best model (tissue‐specific model trained on a subset of important genes) correctly predicted known stressors with 92% accuracy. We then applied this random forest model to wild‐caught bumble bees sampled across a heatwave event at two sites in central Pennsylvania, US, expected to differ in baseline temperature and floral resource availability. Transcriptomes of bees sampled during the heat wave's peak showed signatures of heat stress, while bees collected in the relatively cooler morning periods showed signatures of starvation and cold stress. We failed to pick up on signals of heat stress shortly after the heatwave, suggesting this set of biomarkers is more useful for identifying acute stressors than long‐term monitoring of chronic, landscape‐level stressors. We highlight future directions to fine‐tune landscape transcriptomics towards the development of better stress biomarkers that can be used both for conservation and improving understanding of stressor impacts on bees.
Bank Credit, Portfolio Selection, and Macrodynamics in a Small Open Economy
Authors: Watanabe Toshio
Published: December 2024

We propose an open macroeconomic model based on Bernanke and Blinder's credit perspective. We assume a small open economy with imperfect capital movement and substitutes for financial assets under a floating exchange rate system. We represent credit creation mechanisms and investigate the impact of financial factors on the home economy. We find that the difference in relative responses of banks and firms to the profit rate is associated with short‐term economic fluctuations and long‐term economic stability. Finally, we examine the effects of an inflation targeting policy, signifying that the central bank must gain credibility for its monetary policy to achieve stability.
The nature of a specialty
Authors: Myers Jeff
Published: December 2024

Myers unpacks the defining features of a specialty and their implications for Clinical Competency Committees.
Loneliness and social media
Authors: Hall Jeffrey A.
Published: December 2024

After defining five possible pathways to increase belonging through social media use, this narrative review summarizes the research on social media and loneliness. The association between social media use and loneliness is examined at the trait level and change in loneliness over time. Next, the use of social media during the COVID pandemic and its use to increase belonging at the momentary or daily level are summarized. Following, the use of social media to cope with loneliness or ostracism as well as the social compensation and enhancement hypotheses are examined. The evidence suggests social media use is weakly related to trait loneliness, explains little variance in loneliness relative to other predictors, and fails to explain a change in loneliness over time. There is no evidence it causes loneliness. On any given day, however, social media use may be used to promote belongingness but may not be a good means of coping with loneliness in the long term. This narrative review concludes that future research should firmly situate the study of loneliness and social media in the context of social interactions and relationships by carefully examining when and for whom it is beneficial or harmful.
Anterior Controllable Antedisplacement and Fusion (ACAF) for Cervical Stenosis Patients With Hyperextension Injury: A Retrospective Study
Authors: Sun Shuangxi , Miao Yingying , Xu Tao , Sun Kaiqiang , Lu Yijuan , Sun Jingchuan , Sun Jiuyi , Shi Jiangang
Published: December 2024

Objective

Central cord syndrome (CCS) is an incomplete spinal cord injury (SCI) causing severe motor weakness, and timely decompression via surgical intervention facilitates better recovery. Anterior controllable antedisplacement and fusion (ACAF) is a novel decompression technique and achieved satisfactory outcomes in treating cervical degenerated diseases. However, the clinical effects of ACAF on CCS remains unknown. This present study aimed to investigate the clinical outcomes of ACAF for cervical stenosis patients with CCS due to hyperextension injury.

Methods

This is a retrospective study, and patients who underwent ACAF due to CCS in our institution from July 2021 to December 2022 were enrolled based on the inclusion and exclusion criteria. All patients underwent x‐ray, computed tomography (CT), and magnetic resonance imaging (MRI) before and after surgery. The duration of follow‐up was at least 12 months. The radiological parameters included associated pathologies, prevertebral hyperintensity (HI), intramedullary signal intensity (ISI), and Torg–Pavlov ratio (TPR). The cervical stability was also evaluated. Neurological function was assessed using the American Spinal Injury Association (ASIA) grading system and Japanese Orthopaedic Association (JOA) score. The Mann–Whitney U test was used to compare the clinical outcomes preoperatively and postoperatively.

Results

Finally, 13 patients (7 male and 6 female) with the minimum of 12‐month follow‐up were finally enrolled in this study, with the mean age of 56.6 ± 12.5 years (range, 39–74 years). There were eight patients suffered CCS due to fall, three due to vehicle accident, and two due to diving injuries. The average delay from injury to surgery was 2.23 days (range, 1–4 days), and the mean duration of follow‐up was 16.1 ± 3.5 months. In terms of prevertebral HI and ISI, C4–C6 were the most affected region. In addition, 76.9% (10 of 13) patients were observed to have cervical stenosis indicated by TPR. Associated pathologies were herniated nucleus pulposus (HNP) in five patients, OPLL in three cases, and HNP‐osteophyte complexes (HNP‐OC) in six patients. At the final follow‐up, 13 patients were improved to E. The mean JOA score improved to 15.4 ± 1.0, with the recovery rate of 77.0% ± 12.0%. Two patients experienced postoperative dysphagia, two patients had hoarseness, and one patient suffered postoperative hematoma.

Conclusions

ACAF can be a good option for treating CCS patients due to hyperextension injury with underlying cervical spondylosis and stenosis.
Decreased Sleep Duration and Increased Use of Medication to Aid Sleep Among Parents of Children With Atopic Dermatitis: A Cross‐Sectional Study of the National Health Interview Survey, 2013–2018
Authors: Youn Christopher G. , Kim Joo Yeon , Chen Jennifer K. , Siegel Dawn H.
Published: December 2024

While atopic dermatitis (AD) is one of the most common childhood inflammatory conditions and has been associated with decreased parental sleep quality, most of the reports on this topic are single‐institutional in nature with relatively small sample sizes. Thus, to assess the association of childhood AD with parental sleep on a national scale, we utilized the 2013–2018 National Health Interview Survey (NHIS) and conducted multivariable logistic regression analyses. 6,130,919 (mean age: 7.9 years, standard error [SE]: 0.08) weighted participants had parent‐reported AD (12.9%) and having a child with AD decreased the odds of acquiring 7 hours of sleep (aOR, 0.78; [95% CI 0.72–0.85]) and increased the odds of taking medications to aid sleep (aOR, 1.26; [95% CI 1.12–1.43]). Our findings suggest that having a child with pediatric AD increases the odds of parents not meeting the 7 hours of sleep recommended by the American Academy of Sleep Medicine, underscoring the indirect burden of this condition.
Legitimacy in Constitutional Moments
Authors: Ballingrud Gordon
Published: December 2024

This paper is about the concept of legitimacy in Ackerman's theory of constitutional moments. Ackerman's theory of the constitutional moment explains how constitutional change takes place outside of, and even in tension with, established channels of constitutional amendment. The main tool of legitimacy which Ackerman uses is popular sovereignty, to which he gives special features. Ackerman's particular conception of popular sovereignty I name hyperconsensus, and then I explore whether that is sufficient to justify deviations from Article V, as Ackerman claims. I conclude, with many others, that the constitutional moment needs more justificatory work. I offer reciprocity as a corrective procedural requirement as found in Rawls's liberal principle of legitimacy. Doing so enhances the normative attractiveness of dualist democracy.
Demand Uncertainty and the Optimal Number of Export Destinations
Authors: Danziger Eliav , Danziger Leif
Published: December 2024

We study how demand uncertainty affects risk‐neutral firms' number of export destinations when uncertainty is resolved after firms choose their export destinations and output. We show that firms' ability to allocate their output across destinations in response to destination‐specific shock realizations provides even risk‐neutral firms an incentive to export. Without appealing to firm‐country heterogeneity or increasing marginal cost, our framework can explain why firms export to some but not all ex‐ante indistinguishable destinations. We also show how, for a given firm productivity, the optimal number of export destinations depends on the correlation of shocks across the home and foreign countries.
A prospective, multi‐centric study on the prevalence of dengue, zika and chikungunya in asymptomatic blood donors from different geographical regions of Brazil
Authors: Langhi Dante M. , Levi José E. , Sanches Sidneia , Cerqueira Renato S. , Felix Alvina Clara , Ribeiro Glaciano , Bordin José O.
Published: December 2024

Background and Objectives

Arboviruses outbreaks are increasing in their frequency, geographical area and extension. Brazil is one of the most affected countries in the world, due to its tropical weather and favourable mosquito proliferation conditions. During outbreaks, the safety of the blood supply is a concern, in spite of the low number of transfusion‐transmitted cases with clinical impact. The aim of this study was to evaluate the use of NAT for Dengue, Zika and Chikungunya RNA in actual screening.

Materials and Methods

Blood donors from services located in 4 Brazilian regions were invited to participate in the study and provide an extra blood sample during the collection period between February 7, 2020, and April 4, 2020. Plasma from 21 341 donations was tested in mini pools of 6 by a duplex NAT for Dengue and Chikungunya, in addition to a Zika single assay. Confirmed viremic samples were submitted to an alternative NAT and serological assays.

Results

There were 33 (0.15%) Dengue RNA+ and 5 (0.02%) Chikungunya RNA+ donations. The South region showed the highest prevalence of Dengue‐infected donors (0.29%). These results are in line with the incidence of these arboviruses on the respective geographical regions. Viremic units were discarded and blood services notified.

Conclusion

Screening blood donors for arboviruses during the outbreak season in Brazil reveals a significant number of viremic individuals. Arbovirus NAT testing is feasible and may be incorporated to the current screening policy.
Predictive Zero-Dimensional Combustion Modeling in Internal Combustion Engines With Residual Fraction and Exhaust Gas Recirculation
Authors: Feyijimi Clement , Depcik Christopher
Published: December 2024

The combustion process in spark ignition (SI) and compression ignition (CI) engines plays a significant role in ascertaining engine performance, efficiency, and emissions. As the automotive industry faces challenges related to energy conservation and environmental impacts, understanding and optimizing SI and CI engine combustion become paramount. This study uses a zero-dimensional (0D) internal combustion engine (ICE) model utilizing the Wiebe function to predict mass fraction burned profiles in port fuel injection (PFI) engines. The model incorporates chemical reactions of air–fuel mixtures under lean and rich combustion conditions, accounting for residual and exhaust gas recirculation (EGR). Pressure-based equilibrium constants are applied for rich combustion reactions. Further implementation of the combustion reaction model requires an accurate estimate of the combustion duration. As a result, an exploration of analogous efforts in the literature was accomplished, subsequently drawing insights. This resulted in the development of an empirical model that predicts combustion duration for various fuels such as gasoline, natural gas, propane, methanol, ethanol, hydrogen, and methane–hydrogen blends under different conditions. This includes a unique feature of spark timing variation with run-time conditions. Flame speed data, notably a maximum adiabatic flame speed at an equivalence ratio of 1.1, serve as normalization parameters. The model shows a relative fit to experimental data (R2-values: 0.729–0.972) and is explored through parametric studies, thus demonstrating its utility in simulating fuels under various engine runtime operating conditions.
Dynamical Features and Complete Synchronization of Unified Chaotic Systems With Caputo-Hadamard Fractional Derivative
Authors: Yin Chuntao , Zhao Yufei , Chen Yangquan , Shen Yongjun
Published: December 2024

This paper investigates the dynamical characteristics and synchronization of a unified chaotic system described by Caputo–Hadamard fractional derivative. The equilibrium solutions of the considered system are first analyzed and confirmed to be unstable. Then, by observing the phase diagram and calculating the largest Lyapunov exponent, we discuss the dynamical behavior of the fractional unified chaotic system in relation to variations in both inherent parameters and fractional order. The result indicates that the dynamic states of the system are influenced by these two parameters. The chaos synchronization of fractional unified chaotic systems is explored using a drive-response synchronization method, wherein two controllers are designed to achieve complete synchronization between the driving and responding systems. Furthermore, this proposed chaos synchronization approach for the fractional unified chaotic system is successfully applied to secure communication. Finally, numerical simulations illustrate how both inherent parameters of the system and fractional order affect synchronization performance.
Heat Release Characteristics of a Volatile, Oxygenated, and Reactive Fuel in a Direct Injection Engine
Authors: LeBlanc Simon , Cong Binghao , Sandhu Navjot , Yu Xiao , Reader Graham , Zheng Ming
Published: December 2024

Compression ignition (CI) diesel engines offer power-dense solutions for heavy-duty vehicles. The purpose of combustion management for diesel engines primarily concerns the balance of high efficiency and low emissions. Conventional single-shot diesel combustion involves extended overlap of fuel injection and combustion, promoting diffusion combustion, which is efficient yet prone to form excessive amounts of nitrogen oxides and soot emissions. The application of exhaust gas dilution to reduce NOx below regulation limits leads to an increase in smoke emissions, further magnifying the emission control dilemma. Dimethyl ether (DME) contains suitable reactivity for compression ignition engines while also possessing distinct characteristics to diesel, notably physical properties such as volatility and high oxygen content, that eliminates engine-out soot concerns. In turn, DME enables direct NOx control via oxygen dilution. Nonetheless, the influence of charge dilution toward the combustion heat release behavior of DME persists. This study investigated heat release patterns of high-pressure DME combustion using a single-shot fuel scheduling, with injection timing fixed at top dead center (TDC). Throughout the study, the injection pressure, engine load, and oxygen dilution were adjusted separately to characterize their influence on the subsequent combustion process. Diesel combustion operated at matching conditions was used to provide relevance to the results. Most notably, the period of diffusion burning was extended in DME following a longer period of injection–combustion overlap. To add, the heat release of DME combustion was repeatedly shorter than diesel owing to the lack of end-burning combustion phase inherent to diesel combustion.
Surrogate Modeling-Based Analysis of Concentration Decay in Diffusion-Reaction Mass Transfer Problems
Authors: Abbas Muhammad Mehdi , Jain Ankur
Published: December 2024

Diffusion-reaction phenomena occur commonly in heat and mass transfer problems. Determining the decay characteristics of such problems by solving the underlying energy/mass conservation equation is often mathematically cumbersome. In contrast, there is continued interest in simplified decay models that may offer reasonable accuracy at significantly reduced mathematical complexity. While simplified decay modeling has been presented before for pure diffusion problems, there remains a lack of similar work on diffusion-reaction problems. This work presents analysis of decay characteristics of diffusion-reaction problems using surrogate modeling, wherein the decay constant is determined using the moment matching method. Results are derived for homogeneous and two-layer Cartesian, cylindrical and spherical geometries. Under special conditions, results from this work are shown to correctly reduce to previously presented pure diffusion analysis. Good agreement with past work on a diffusion-reaction drug delivery problem is also demonstrated. Surrogate modeling using a single exponential function is shown to agree well with exact solutions. A two-term exponential model is also proposed to further reduce the error under certain conditions. This work extends surrogate decay modeling to the technologically important class of diffusion-reaction problems. Results presented here may help analyze and optimize several heat/mass transfer problems, such as drug delivery and reactor safety.
Solidification of a Liquid Column Between Two Rods of Unequal Sizes and Different Temperatures
Authors: Ho Nang X. , Nguyen Vinh T. , Vu Truong V.
Published: December 2024

A liquid column hanging between two surfaces (e.g., rod ends) appears in many engineering applications. This study focuses on its solidification with volume expansion through the use of an axisymmetric front-tracking method. The phase boundaries are handled by connecting points while the momentum and energy equations are solved on a fixed, rectangular grid. The rods holding the column in the vertical direction have different radii and temperatures and initiate solidification from their ends due to their temperatures smaller than the liquid melting point. As the upper rod is hotter than the lower rod, the lower phase-change interface moves faster than the upper one, resulting in an increase in the difference between the lengths of the upper and lower solid phases. The liquid phase changing into the lighter solid phase results in a ring formed near the midplane of the column at the end of solidification. The ring is located above the midplane and shifts more away from it as the upper rod has a higher temperature and a smaller radius than the lower rod. Increasing the upper rod radius or the column length or decreasing the Stefan number causes the solidification of the column to progress longer.
An Undulating Kirigami Pattern With Enhanced Tear Strength
Authors: Corrigan Tom , Xie Di , Srivastava Abhishek
Published: December 2024

Kirigami, the cutting and folding of sheets, can create useful three-dimensional shapes from flat sheets of material. Some kirigami patterns self-deploy from their flat state when tension is applied; we call these tension-activated kirigami (TAK) patterns. A new TAK pattern has been proposed that produces ribbons of material that undulate out of the plane of the kirigami sheet when deployed with tension. In the planar state, this pattern comprises staggered rows of multiple slits, so we call it the multi-slit pattern. The multiple slits can include two, three, or more slits in place of the widely studied single-slit kirigami pattern, with an increased number of undulations produced with additional slits. An enhancement is also proposed that increases the tear strength of this pattern by adding multiple beams to carry the tension forces that deploy and hold the structure. This multi-beam enhancement to the multi-slit pattern has been investigated with experiments and duplicated with finite element analysis simulations. A good correlation was found, and a broader design space was also investigated with additional simulations. It is proposed that the multi-slit undulating kirigami pattern, with or without the multi-beam enhancement, produces a compelling new deployed structure with increased interlocking and the potential for many applications.
Load-Side Dynamics Introduces Complex Effects on Orthotic Actuator Performance in Benchmarking
Authors: Sun Mingrui , Oetomo Denny , Tan Ying , Kulić Dana , Baček Tomislav
Published: December 2024

Series elastic actuators are increasingly adopted in wearable robots, due to superior sensing and actuating capabilities provided by the added internal compliance. However, when evaluating their performance in benchtop setups, the dynamics of the physical human–robot interface (i.e., external compliance) are usually overlooked despite it causing energy dissipation and delays in power transmission. This work closes the gap by emulating in a test bench the physical human–robot interaction dynamics and validating actuator performance against commonly used performance indices, including torque bandwidth, torque tracking, and transparency. The results show a significant impact of the interaction dynamics on the actuator performance. When interface dynamics is present, decreasing the actuator (internal) compliance has little to no effect on its bandwidth. When delivering a walking torque, decreasing internal (actuator) and external (interface) compliance has the same decreasing effect on the motor’s peak electrical power in the hip joint. Conversely, the motor peak electrical power decreases with an increase in internal (actuator) compliance but increases with an increase in external (interface) compliance in the knee joint. As such, this work demonstrates the importance of including interaction dynamics as a norm in designing and evaluating actuation units in wearable robots.
Flow and Heat Transfer in a Rotating Disc Cavity With Axial Throughflow at High-Speed Conditions
Authors: Wang Ruonan , Chew John W. , Gao Feng , Marxen Olaf
Published: December 2024

Flow and heat transfer in a compressor rotating disc cavity with axial throughflow is investigated using wall-modeled large-eddy simulations (WMLES). These are compared to measurements from recently published experiments and used to investigate high Reynolds number effects. The simulations use an open-source computational fluid dynamics solver with high parallel efficiency and employ the Boussinesq approximation for centrifugal buoyancy. Kinetic energy effects (characterized by Eckert number) are accounted for by scaling the thermal boundary conditions from static temperature to rotary stagnation temperature. The WMLES shows very encouraging agreement with experiments up to the highest Reynolds number tested, Reϕ=3.0×106. A further simulation at Reϕ=107 extends the investigation to an operating condition more representative of aero engine high-pressure compressors. The results support the scaling of shroud heat transfer found at lower Reϕ, but disc heat transfer is higher than expected from a simple extrapolation of lower Reϕ results. This is associated with transition to turbulence in the disc Ekman layers and is consistent with the boundary layer Reynolds numbers at this condition. The introduction of swirl in the axial throughflow, as may occur at engine conditions, could reduce the boundary layer Reynolds numbers and delay the transition.
High-Fidelity Investigation of Vortex Shedding From a Highly Loaded Turbine Blade
Authors: Gloerfelt Xavier , Cinnella Paola
Published: December 2024

High-fidelity numerical simulations based on wall-resolved large-eddy simulations (LESs) are used to investigate the vortex shedding dynamics in a linear turbine cascade. The profile geometry is the well-documented LS59 highly loaded rotor blade. The simulation campaign covered several outlet Mach numbers (subsonic and transonic) and several experimental configurations to shed light on the relations between vortex shedding frequency, the laminar or turbulent states of boundary layers, and the resulting cascade losses. A first major result concerned experiments for transonic outlet Mach number. LES without inlet turbulence and LES without tripping the suction-side boundary layer are unable to match the experimental flow field. In the untripped case, the recirculation bubble is shorter leading to a vortex shedding Strouhal number of 0.17, whereas in simulations with trip wire or inlet turbulence, the bubble was longer, with a Strouhal of 0.24. A second finding is that the inlet turbulence intensity is able to drive the switching between two regimes for subsonic outlet Mach numbers: the so-called detached vortex shedding (long bubble, St∼0.24) or a “transonic vortex shedding” (short bubble, St∼0.19). The appearance of shock waves and very coherent rolls in the wake for the “transonic” regime can lead to a doubling of the cascade losses due to the drastic pressure drop near the trailing edge. Such a change in the flow regime, due solely to an increase in freestream turbulence, has not been reported earlier.
An Active Turbulence Grid for Turbomachinery Flow Experiments
Authors: Bertelli Federico , Okada Mizuki , Lavagnoli Sergio , Hillewaert Koen
Published: December 2024

Quantifying and predicting the effects of freestream turbulence on the aerodynamic performance of turbomachinery flows continues to be of primary interest to advance the physical understanding and modeling of loss mechanisms. This work is motivated by the need to expose turbine flows to a wide class of inlet turbulence fields, characterized by the peculiarity of setting the turbulence intensity levels and yet tuning the turbulence scales independently. This article describes the development and experimental characterization of an active turbulence generator concept that provides the authority to enable future experimental measurements in turbine cascade rigs. The study has been conducted in an auxiliary low-speed test bench with a small cross-sectional area, testing at low Mach numbers (∼0.05) and ambient conditions. Pressure, hot-wire anemometry, and particle image velocimetry (PIV) measurements are presented. The results indicate that the active turbulence generator is capable of generating a wide range of homogeneous and isotropic freestream turbulence. Turbulence levels in the range of 1.5–13% with minimum pressure losses and a low degree of nonuniformity (<5%) have been obtained with the ability to independently control the integral length scale within the range of 6–25 mm.
Autonomous Satellite Servicing Infrastructure for In-Space Assembly and Manufacturing
Authors: Down Ian M. , van Wijk David E. J. , Parikh Deep , Majji Manoranjan
Published: December 2024

This work examines the closed-loop deployment of spacecraft servicing modules onto an uncontrolled bundle of assembly components as a method of gaining custody during the in-space assembly process. Minimum energy, low-thrust relative trajectories are generated using indirect optimal control on linear dynamics over a finite time search horizon. A line search solves for the minimum energy solution in the closed subset that satisfies a keep out zone constraint. A trajectory tracking linear quadratic regulator is used in conjunction with an extended Kalman filter to closed-loop maneuver the spacecraft under nonlinear relative orbital motion dynamics. Bearing angles, range, and range rate measurements are assumed available. Launch ΔV’s from the servicer spacecraft’s deployment of a module and the ΔV’s seen in the relative frame upon impact on the client are included, and their effect on covariance due to impact site uncertainty is investigated. Discussions regarding these GN&C elements’ importance within the context of the manufacturing/assembly process are included.
Application of PyAnsys for Level 3 Assessment Tool Development
Authors: Bao Ji , Zhang Shenwei , Zhang Billy
Published: December 2024

Finite Element Analysis (FEA) is a prevalent tool for the integrity assessment of pipelines in the industry and is widely acknowledged by industrial standards such as CSA Z662 and CFR 192.712. Previous research has established the capability of FEA to accurately simulate the response of pipelines under various loading scenarios, demonstrating high fidelity in processes like dent simulation and predicting the failure of corroded pipelines.

The Finite Element method is a complex numerical technique that involves discretizing a continuous pipeline into small finite elements. While the accessibility of commercial FEA software tools has facilitated the application of this method, challenges and potential issues persist. Firstly, FEA simulations generate substantial amounts of data, including nodal solutions and stiffness matrices. Secondly, debugging can be intricate, necessitating a combination of experience and specialized knowledge. Thirdly, postprocessing can be time-consuming; for instance, calculating the Ductile Failure Damage Indicator (DFDI) involves integrating stress components across all time steps. Lastly, commercial FEA software typically operates as closed source, limiting customization options to the features provided by the software.

This paper introduces the use of a Python-based FEA library, PyAnsys, offering a more accessible and streamlined approach to managing the extensive data generated by FEA simulations. The integration of PyAnsys with Python enhances the debugging process by providing an intuitive and user-friendly scripting interface. Python’s readability and extensive debugging tools contribute to a smoother debugging experience, reducing the dependency on specialized knowledge. Additionally, PyAnsys facilitates efficient pre-processing and post-processing by leveraging the power of Python. The open-source nature of PyAnsys enhances customization options, allowing integration with other Python libraries, such as the visualization package PyVista, making PyAnsys a versatile and powerful tool for FEA applications.

Two case studies are presented in the paper to demonstrate the effectiveness of PyAnsys. The first case study utilizes PyAnsys to analyze a dented pipe in structural analysis, while the second case study involves study simulating a corroded pipeline to evaluate the load carrying capacity of a pipeline containing metal loss corrosions.
Effective Anomaly Management Approach for Class Location Change With Engineering Assessment
Authors: Al-Amin Mohammad , Zhang Shenwei , Kariyawasam Shahani
Published: December 2024

Canadian Standard Association (CSA) Z662 allows pipeline operators to perform engineering assessment (EA) to determine the suitability for continued operation of the existing pipeline at the new class location designation instead of pipe replacement or pressure reduction. Canadian Energy Regulator (CER) filing manual guide E provides the filing requirements for class location change EAs. However, there is no clear guideline in CSA Z662 or CER filing manual guide E on how to assess and manage pipeline anomalies (e.g., corrosion and cracking) on a pipeline operating with a class change managed under an EA.

CSA Z662-23 Clause 10.7.2 requires evaluation and repair of imperfections per Clause 10.10 and Clause 10.11 for class location change pipeline segments. However, no explicit guidelines are provided regarding which location factor is to be used when the class location changes from a lower class to higher class with an EA. The most common perception is that the location factor based on the new higher class should be used in a class location change scenario. This leads to the question whether a pipeline segment which is designed for a lower class location can have an appropriate response criterion (i.e., acceptable FPR level) based on a higher class location. The authors performed an in-depth analysis to address this question. These results are explained in this paper. The anomaly assessment and response process presented in this paper combines a deterministic FPR based assessment and a probabilistic assessment to effectively manage anomalies on class location change pipeline segments. The proposed process will ensure safe and consistent response requirement for anomalies identified in pipeline segments with class location changes.
Key Elements to Consider When Managing Circumferential SCC In Pipelines
Authors: Guillen Pedro , Merotto Fernando , Monteiro Larissa , Gamboa Erwin
Published: December 2024

In recent years, stress corrosion cracking (SCC) has become a more prevalent threat to pipeline integrity worldwide; SCC only occurs in a specific combination of a susceptible material, environment, and tensile stress at a particular location. In pipeline systems, the main SCC driving stress — from internal pressure — favors axial rather than circumferential SCC (CSCC). However, under certain conditions, such as excessive soil loads, high residual axial stresses from construction, etc., axial loading can reach the threshold for CSCC to initiate and propagate. Although in a smaller proportion when compared to axial SCC, CSCC incidence has also increased in the pipeline industry. Similar to any other integrity threat, a holistic approach is required to manage it; once a pipeline has been identified to be susceptible to CSCC, the next stage is to assess its extent in the system, understand the pipeline locations with active CSCC, and implement adequate repair and mitigation actions.

Using only crack ILI to assess the extent of CSCC in a pipeline can be challenging due to limitations in currently available ILI technologies, especially for gas pipelines. Thus, direct assessment becomes a key supporting task at this initial stage of the management process; combining relevant data sets will help to define areas more susceptible to CSCC. Combining this information with ILI outcomes, when available, will help to develop and implement a more effective management plan. Although SCC direct assessment industry guidance is available, a CSCC-focused susceptibility model should be developed for each pipeline.

This paper describes a proposed approach to managing CSCC in pipelines, which combines applicable data based on CSCC specific drivers, such as geohazards and construction features along the pipeline, pipe material data and cathodic protection (CP) performance. Hence, different layers of information are considered, including the pipeline data book and available ILI datasets (e.g., MFL, geometric inspection, historic CP surveys, visual inspections, and field verification data). In fact, this document includes a review of the main factors affecting CSCC in a gas pipeline with the aim of identifying those that should be considered in the susceptibility model; it also includes an example of elements considered for a specific pipeline whit CSCC present. Furthermore, it reviews the relevance of ILI when dealing with this threat, available ILI technologies and their possible limitations, and uncertainties and how to manage them. Finally, relevant mitigation and other actions aimed to manage this threat are also discussed.
Development of a SCC Crack Growth Rate Calculator
Authors: Gamboa Erwin , Wynne Andrew
Published: December 2024

Estimation of representative Crack Growth Rates (CGR) for pipelines with confirmed Stress Corrosion Cracking (SCC) is an Integrity management challenge.

Published rates used within the industry can be unreliable, as most estimates assume a particular range of time periods for when cracks initiated, without providing reliable evidence for when crack initiation occurred. Also, little detail is provided to help assess whether the published rate could be applied to similar asset of interest. Laboratory testing (often used to determine industry published CGRs) tends to be under Stage II growth conditions where the CGRs are known to be much higher than compared to Stage III conditions. As a result, reported maximum CGRs can vary greatly from approximately 5 mm/yr (from laboratory testing) to approximately 0.8 mm/yr (from infield estimates, where operational conditions are not generally provided). These values are known to be very conservative, so a “rule of thumb” rate of 0.3 mm/yr is commonly used throughout the pipeline industry as an SCC growth rate. This estimate of 0.3 mm/yr is still considered to be conservatively aggressive when compared with reliably obtained rates of 0.15 mm/yr or lower.

To support operators, an SCC Crack Growth Rate Calculator has been developed to bring together the different parameters known to affect SCC crack growth rates in order to provide an initial, conservative crack growth rate for individual anomalies (reported or hypothetical) located along a specific pipeline.