bluuebunny/crossref_metadata_2025 huggingface dataset:
Traumatised Nurses' Desired Support Needs for Continued Recovery After the COVID‐19 Pandemic: A Qualitative Descriptive Study Utilising Photovoice
Authors: Powell Melissa A. , Oyesanya Tolu O. , Scott Susan D. , Allen Deborah H. , Walton AnnMarie
Published: September 2024

Aims

The aims of this study were to describe the experiences of nurses in the aftermath of the COVID‐19 pandemic and to explore nurses' current desired support needs.

Design

This study used a qualitative descriptive design.

Methods

This study was conducted in the Southeastern United States at an academic health system encompassing acute care hospitals and outpatient speciality clinics. Thirteen nurses were interviewed in August and September of 2023 in five small groups of two or three nurses. Photovoice was used for data collection and each nurse submitted two photographs. Data were analysed utilising conventional content analysis, with transcripts and photograph analysis occurring concurrently.

Results

Three themes were identified: (1) organisational turmoil, (2) personal traumatisation and transitions and (3) striving for revival and renewal. A conceptual model illustrating the three themes and their relationships was developed to depict study findings.

Conclusion

Nurses were impacted by organisational factors, such as staffing issues and lack of support, and personally through psychological trauma that has remained challenging. Nurses found revival and renewal in their personal lives, but still desire continued improvement in organisational factors to enhance their well‐being in ways not currently being addressed to allow for full recovery. Findings from this study are pertinent for healthcare organisations and leaders to develop organisational changes and mental health solutions to support nurse well‐being.

Implications for the Profession

The prioritisation of nurse well‐being is critical for the nursing profession and healthcare organisations. Organisational improvements and the implementation of support resources are urgently needed to aid in nurse recovery, nurse retention and to ensure patients receive quality care.

Impact

This study identified nurses' struggles 3 years after the beginning of the COVID‐19 pandemic, highlighting the ongoing need to provide resources and interventions that support nurse well‐being. Our findings offer nurses' descriptions of their experiences and support needs for organisations and healthcare leaders to consider in the future.

Reporting Method

Standards for Reporting Qualitative Research (SRQR) Checklist.

Patient or Public Contribution

No patient or public contribution.
Diversity‐On: A Diversity‐Sensitive Online Self‐Help Program for Family Caregivers—A Protocol for a Mixed Methods Study
Authors: Annac Kübra , Basyigit Mualla , Öztürk Sümeyra , Örs Ela Rana , Aksakal Tugba , Kuhn Christina , Rutenkröger Anja , Tezcan‐Güntekin Hürrem , Yilmaz‐Aslan Yüce , Brzoska Patrick
Published: September 2024

Background

Scientific research has consistently emphasised the high levels of stress encountered by family caregivers of individuals living with dementia. However, conventional self‐help approaches remain underutilised. The ‘Diversity‐On’ study addresses this issue. The study employs a storytelling approach to develop and evaluate an online self‐help program that is participatory and diversity‐sensitive, thereby ensuring congruence with diverse identities and lifeworlds.

Methods

The study uses a mixed‐methods design, comprising the allocation and implementation of the intervention, the development of stories, a process evaluation (N = 20) and an outcome evaluation (quantitative: N = 130, qualitative: N = 20). The study's primary focus is its comprehensive participatory approach, integrated throughout the research process. The study is dependent on the input of a number of stakeholders, all of whom are committed to advocating for the concerns of patients.

Discussion

Given its participatory methodology and intersectional perspective, the ‘Diversity‐On’ study is anticipated to yield a number of significant outcomes. The study has the potential to empower family caregivers of individuals living with dementia who are under high stress, empowering them to take part in self‐help groups despite multiple barriers, thus alleviating their burden. Additionally, it has the capacity to promote the well‐being of caregiving relatives who are providing care and are experiencing high levels of stress. The study's objective is to maintain home care arrangements for as long as possible, in accordance with the values and preferences of care recipients and their families. The study intends to develop and assess a customised online self‐help resource that is suitable for a diverse range of users and that remains accessible beyond the study period.

Trial Registration

The project is subsequently registered in ClinicalTrials.gov
Information acquisition and tax avoidance: Evidence from a natural experiment
Authors: Fan Lyu , Ouyang Caiyue , Pittman Jeffrey , Xiong Jiacai , Yao Jun
Published: September 2024

Analyzing the launch of high‐speed rail (HSR) services in China as a natural experiment, we identify a positive externality stemming from lower information acquisition costs: the reduction in firms’ overinvestment in tax avoidance. Specifically, we find that outsiders undertake more corporate site visits and firms engage in less tax avoidance after the opening of HSR lines in the cities where these firms are located, leading to enhanced firm value. In another result consistent with expectations, we document that the impact of the introduction of HSR lines on tax avoidance is concentrated in firms in which insiders exhibit a high propensity to extract rents through aggressive tax strategies. Our results imply that more efficient transportation facilitates site visits and the acquisition of firm‐specific information, particularly soft information. This improvement strengthens external monitoring, thereby limiting the ability of insiders to accumulate private benefits under the guise of tax avoidance that benefits all shareholders as the residual claimants.
Characteristics of 24‐h ambulatory blood pressure monitoring in elderly hypertensive males: An observational study of 85 year older patients
Authors: Wang Junwen , Xiao Pijuan , Ye Yuyang , Chen Xuefeng , Hu Xinru , Yang Yuanrui , Peng Yong
Published: September 2024

Although hypertension is highly prevalent among the elderly and significantly contributes to cardiovascular disease risk, studies focusing on male elderly individuals over 85 years old are relatively scarce. This study aimed to investigate ambulatory blood pressure monitoring (ABPM) characteristics in male hypertensive patients aged over 85 years. These included demographic characteristics, antihypertensive drug use, 24‐h ABPM values, diabetes, coronary heart disease, sleep disorders, smoking history, and drinking history, and the differences in ABPM between the age groups over and under 85 years old were analyzed. A total of 585 elderly hypertensive patients were included. The mean systolic blood pressure in individuals aged over 85 years was significantly greater throughout the day (131.57 ± 12.52 mmHg vs. 123.75 ± 2.74 mmHg, p < .001). In the 85 years older age group, the nighttime variability coefficient of SBP was lower at 7.84 ± 2.9 than the under 85 years age group 8.92 ± 3.13 (p < .001). The 85 years older age group age group presented a significantly greater whole‐day systolic blood pressure standard deviation of ABPM (13.2 ± 3.19 vs. 12.47 ± 3.05, p = .005) compared with those under the age of 85 years. In the 85 years older age group, the proportion of individuals with the reverse dipper pattern was higher (48.15% vs. 38.31%, p = .017) than under 85 years age group. This study revealed that elderly male hypertensive patients aged over 85 years presented elevated average blood pressure levels. The research investigated ABPM characteristics. Older hypertensive individuals are more likely to have a reverse‐dipper blood pressure pattern.
Tools for assessing the quality of life of hysterectomized women: A systematic review
Authors: Taheri Mahdiye , Simbar Masoumeh , Ebadi Abbas , Dolatian Mahrokh
Published: September 2024

Aims and Objectives

Since hysterectomy surgery is a major and invasive procedure, it can affect the quality of life of women in many ways. This study aimed to review and critique the psychometric properties of tools used to measure the quality of life of hysterectomized women.

Method

An advanced search was conducted in international (PubMed, Web of Science, Scopus, PsycINFO, Embase) as well as national databases (SID and Magiran) to retrieve articles published from 2000 to 2024, using keywords related to hysterectomy and quality of life. Then, the psychometric properties of the tools found in these articles were evaluated by COSMIN checklist.

Results

The psychometric properties of tools were analyzed using the COSMIN checklist. Among the 20 general and specific tools examined, content validity had not been evaluated in 15 tools, construct validity had not been evaluated in four tools, criterion validity had not been evaluated in eight tools, internal consistency had not been evaluated in five tools, responsiveness had not been evaluated in 16 tools, and interpretability had not been assessed in 18 tools, and measurement error had not been evaluated in any of the tools.

Conclusion

The results showed that none of the evaluated tools have all the criteria of Cosmin's checklist. Of course, construct validity and reliability had been assessed in most of the tools. Meanwhile, there was no tool to measure the quality of life of hysterectomized women specifically. Therefore, it seems that developing a tool with acceptable psychometric properties is necessary to measure the quality of life of hysterectomized women specifically.
Assessment of magnetic resonance imaging findings in ovarian granulosa cell tumors along with clinical prognostic factors
Authors: Aydin Elçin , Akdemir Celal , Erdoğan Özgür , Şahin Hilal , Karadeniz Özden , Yürük Yeşim Yekta , Şahin Şükrü , Sanci Muzaffer
Published: September 2024

Aim

To determine the role of preoperative MRI in the diagnosis and treatment of patients with granulosa cell tumors (GCTs) of the ovary.

Materials and Methods

Twenty‐four patients who were operated on between 2018 and 2022 and who were pathologically diagnosed with GHT and met the inclusion criteria were retrospectively examined. The findings were compared with the patients' demographic data, symptoms, surgical findings (laterality, stage, lymph node involvement, endometrial pathology, tumor size), and CA‐125 levels.

Results

The final cohort included 24 patients with a mean age of 54.71 ± 16.52. All the patients had the pathological diagnosis of adult type GCT. In the morphological evaluation, the most common finding was a solid‐cystic mixed type (14 patients, 58.3%), while intratumoral hemorrhage signal was observed in 10 patients (41.7%). In the majority of cases (91.7%), the mass showed regular contours. The honeycomb/Swiss cheese sign was detected in 54.2% of the cases. When the T1 and T2 signal of the solid component of the mass were examined relative to the myometrium, the majority of GCTs appeared isointense on both sequences (83.3% and 62.5%, respectively). The mean ADC value of the solid component obtained from diffusion‐weighted imaging was 0.78 ± 0.15 × 10−3. Pelvic fluid was observed in 41.7% of the cases. The average endometrial thickness was 9.74 ± 6.43 mm. Thickened endometrium more than 9 mm was observed in 9 out of the remaining 21 patients (42.9%).

Conclusion

Understanding the key imaging features for GCTs plays an essential role in the diagnosis and guiding the treatment effectively.
Bouillon fortification as a strategy to address inequities in micronutrient adequacy of diets in Nigeria
Authors: Adams Katherine P. , Vosti Stephen A. , Becher Emily , Ishaya Faith , Engle‐Stone Reina
Published: September 2024

Bouillon is a widely consumed condiment in many West African countries, including Nigeria. Although Nigeria has mandatory fortification standards for multiple food vehicles, bouillon fortification could help address remaining gaps in micronutrient intake. Using household food consumption data, we used the nutrient density method to model the additional contribution of bouillon fortified with vitamin A (40–250 µg/g bouillon), folic acid (20–120 µg/g), vitamin B12 (0.2–2 µg/g), iron (0.6–5 mg/g), and zinc (0.6–5 mg/g) for meeting micronutrient requirements of women of reproductive age (WRA) and children aged 6–59 months. Accounting for existing fortification programs, our results showed that, except for iron, the prevalence of inadequacy was substantially higher among WRA and children living in poorer and rural households. Given the ubiquity of bouillon consumption, bouillon fortification has the potential to virtually eliminate vitamin A, folate, and vitamin B12 inadequacy, reduce the prevalence of zinc inadequacy by over 20 percentage points, and improve equity in the micronutrient adequacy of diets across socioeconomic strata and urban and rural residence. Our results also suggested that designing a bouillon fortification program would require careful planning to balance reductions in inadequacy with the risk of high intakes. This evidence provides important input into decisions around bouillon fortification in Nigeria.
The importance of World Health Organization international reference standards in the product life cycle of biosimilars
Authors: Kang Hye‐Na , Wadhwa Meenu , Knezevic Ivana , Burns Chris , Griffiths Elwyn
Published: September 2024

Technological advances in analytics, as well as scientific and regulatory knowledge and experience gained from biosimilar development/approvals over the last decade, enabled the World Health Organization (WHO) in 2022 to revise its guidelines on the evaluation of biosimilars. Among the revisions, there is more reliance on analytical and functional aspects to prove similarity (and likely fewer clinical requirements). WHO international reference standards for biosimilars provide additional confidence to regulators looking for evidence‐ and data‐based regulatory convergence in scientific and technical measures of quality attributes. These standards serve as a benchmark for harmonizing the bioactivity or potency of biosimilars, ensuring their future sustainability. This article discusses the availability and role of WHO international reference standards throughout the product life cycle of biosimilars.
Asymmetric Warming of Day and Night Benefits the Early Growth of Acer mono Seedlings More Than Symmetric Warming
Authors: Yuan Junfeng , Yu Xinlei , Wu Ting , Gao Shitong , Zhang Ting , Yan Qiaoling , Li Rongping , Zhu Jiaojun
Published: September 2024

Asymmetric warming refers to the difference between the increase in daytime maximum temperature and the increase in nighttime minimum temperature and has been documented in temperate regions. However, its impacts on seedling growth have been largely ignored. In this study, seedlings of a widely distributed tree species, Acer mono Maxim., were exposed to both symmetric warming (SW) and asymmetric warming scenarios (day warming [DW], night warming [NW] and diurnal asymmetric warming [DAW]). Compared to control, all warming scenarios were found to enhance belowground biomass. DW promoted the seedling growth, while NW reduced the stem biomass. DAW did not impact the total biomass relative to the control. Compared to SW, DAW advanced phenology, increased indole‐3‐acetic acid content and chlorophyll content, which enhanced total biomass and stored more NSC in the root. Future DAW would be not beneficial to the growth of A. mono seedlings by comparing with the control. This research encourages further exploration of tree growth experiments under asymmetric warming conditions, as most studies tend to underestimate the warming effects on plant growth by focusing on SW. Incorporating the responses of seedling physiology and growth to non‐uniform diurnal warming into earth system models is crucial for more accurately predicting carbon and energy balances in a warmer world.
2024 RSS Presidential Address: Reconceptualizing Rurality and Nurturing Rural Sociological Souls☆
Authors: Sherman Jennifer
Published: September 2024

This address focuses on the importance of inclusivity and diversity to the future of the Rural Sociological Society. It begins by sharing the author's experiences within the society as a rural‐focused scholar trained in a Sociology department without strong ties to the RSS, and the challenges she faced in earning recognition in the RSS. It goes on to explore the development of the RSS and the ways in which this history continues to shape who is and isn’t perceived as a rural sociologist. It then argues that the society should strive to be more inclusive in the ways it conceptualizes both rurality and rural sociology. This inclusivity should be extended to those who care about rural places and populations and treat them with respect, regardless of whether they were trained in historic departments of Rural Sociology. The Society should view multidisciplinarity as a benefit, not a detriment to its long‐term health and flourishing. The address ends by calling upon members to engage in the work of nurturing rural sociological souls wherever they are trained and working. It emphasizes the importance of a renewed commitment to diversity and inclusivity in multiple forms.
General boundary conditions for a Boussinesq model with varying bathymetry
Authors: Lannes David , Rigal Mathieu
Published: September 2024

This paper is devoted to the theoretical and numerical investigation of the initial boundary value problem for a system of equations used for the description of waves in coastal areas, namely, the Boussinesq–Abbott system in the presence of topography. We propose a procedure that allows one to handle very general linear or nonlinear boundary conditions. It consists in reducing the problem to a system of conservation laws with nonlocal fluxes and coupled to an ordinary differential equation. This reformulation is used to propose two hybrid finite volumes/finite differences schemes of first and second order, respectively. The possibility to use many kinds of boundary conditions is used to investigate numerically the asymptotic stability of the boundary conditions, which is an issue of practical relevance in coastal oceanography since asymptotically stable boundary conditions would allow one to reconstruct a wave field from the knowledge of the boundary data only, even if the initial data are not known.
Effect of angiotensin II type 1 receptor antibodies on graft function and survival in paediatric kidney transplant recipients
Authors: Kermond R. F. , Kim S. , Mackie F. , Hahn D. , Carroll R. P. , Sharma A. , Durkan A. M.
Published: September 2024

HLA donor specific antibodies (DSA) are implicated in antibody‐mediated rejection (AMR), graft dysfunction and failure in kidney transplant (KT) recipients. Non‐HLA antibodies including angiotensin II type 1 receptor (AT1R) may also play a role in AMR, impact graft function and survival. Data is limited in paediatric KT cohorts. We aimed to assess the prevalence and effect of pre‐transplant AT1R antibodies on rejection, graft function and survival in paediatric KT recipients. This was a retrospective cohort study conducted across two paediatric centres including KT recipients with a pre‐transplant AT1R antibody level. Outcomes included rejection, de novo DSA formation, graft function, failure, proteinuria and hypertension. Of 71 individuals, 72% recorded a positive pre‐transplant AT1R Ab level (≥17 U/mL). Over a median follow‐up of 4.7 years, AT1R Ab positivity demonstrated a trend towards increased risk of rejection however was not statistically significant (HR 3.45, 95% CI 0.97–12.35, p‐value 0.06). Sensitivity analysis with AT1R Ab levels of ≥25 U/mL (HR 2.05 95% CI 0.78–5.39, p‐value 0.14) and ≥40 U/mL (HR 1.32, CI 95% 0.55–3.17, p‐value 0.53) validated this. De novo DSA formation occurred more frequently with AT1R Ab positivity (41% vs. 20%, p‐value 0.9). AT1R Ab was not associated with hypertension, proteinuria, graft failure or dysfunction. In conclusion, this cohort study demonstrated a high prevalence of pre‐transplant AT1R Ab positivity (72%). AT1R Ab positivity demonstrated a trend towards increased risk of rejection and de novo DSA formation however did not meet statistical significance. There was no association between AT1R Ab and hypertension, proteinuria, graft failure or dysfunction.
The effects of foreign direct investment on human capital accumulation—Evidence from China
Authors: Liu Yan
Published: September 2024

This paper examines the effect of foreign direct investment (FDI) on human capital accumulation in China. The identification strategy exploits variations in FDI inflows across manufacturing sub‐sectors caused by China's FDI liberalisation and initial sectoral composition patterns across cities. Using a panel of city‐level data from 1990 to 2005, the paper shows that FDI liberalisation accelerated human capital accumulation. Cities with higher exposure to FDI liberalisation experienced higher growth in high school and college enrollment. FDI incentivizes individuals' investment in their human capital by paying a higher wage premium for skilled workers, pushing up the skill premium in the local labor market, and raising household income. Compared to export‐oriented FDI and FDI in less‐skilled industries, market‐seeking FDI and skill‐intensive FDI have a much larger effect on college enrollment.
Chromatic symmetric functions and polynomial invariants of trees
Authors: Aliste‐Prieto José , Martin Jeremy L. , Wagner Jennifer D. , Zamora José
Published: September 2024

Stanley asked whether a tree is determined up to isomorphism by its chromatic symmetric function. We approach Stanley's problem by studying the relationship between the chromatic symmetric function and other invariants. First, we prove Crew's conjecture that the chromatic symmetric function of a tree determines its generalized degree sequence, which enumerates vertex subsets by cardinality and the numbers of internal and external edges. Second, we prove that the restriction of the generalized degree sequence to subtrees contains exactly the same information as the subtree polynomial, which enumerates subtrees by cardinality and number of leaves. Third, we construct arbitrarily large families of trees sharing the same subtree polynomial, proving and generalizing a conjecture of Eisenstat and Gordon.
Burner and Flame Transfer Matrices of Jet-Stabilized Flames: Influence of Jet Velocity and Fuel Properties
Authors: Nedden Philipp zur , Eck Mattias E. G. , Lückoff Finn , Paschereit Christian Oliver , Orchini Alessandro
Published: September 2024

To achieve the decarbonization of electrical power generation, gas turbines need to be upgraded to combust high-hydrogen content fuels reliably. One of the main challenges in this upgrade is the burner design. A promising burner concept for a high-hydrogen fuel mixture are jet burners, which are highly flashback resistant thanks to their high bulk velocity. Due to its nonacoustically compact extension and the presence of hydrogen in the fuel mixture, new challenges arise in assessing the (thermo)acoustic response of this burner design. A burner transfer matrix (BTM) and the flame transfer function (FTF) or transfer matrix (FTM) are typically measured with the multimicrophone method (MMM) to assess the performance of new burner types in relation to thermoacoustic stability. With the switch toward hydrogen, the fuel/air mixture is significantly altered in its properties regarding the speed of sound and density, which are of fundamental importance for acoustic waves propagation and their reconstruction via the MMM, as highlighted in recent work. In this work, we extend this discussion by studying the influence of the gas composition within the burner when measuring BTMs, and its indirect effect on the assessment of FTFs. Experimentally, we achieve this by adapting the preheating temperature during the measurement of the BTM with a nonreactive mixture in order to match the speed of sound of the hydrogen–air mixture required to flow in the burner under reactive conditions. Additionally, we present an analytical model for the jet burner transfer matrix, which is validated against the experimental data. Since the BTM is fundamental for the assessment of the FTM and FTF, the propagation of the error of changing fuel mixtures in the burner is evaluated. The influence of the variation in reactant composition of the BTM on the FTM assessment is noticeable, particularly in the gain of the FTFs. Furthermore, the influence of the total mass flow and, thus, the bulk flow velocity on the FTF is analyzed.
Infants Sucking Pattern Identification Using Machine-Learned Computational Modeling
Authors: Olapojoye Abdullahi , Singh Abhishek , Nishi Eri , Fei Baowei , Nostratinia Aria , Hassanipour Fatemeh
Published: September 2024

Breastfeeding involves a complex coordination of swallowing, breathing, and sucking, with the infant's sucking proficiency being crucial for adequate nutrient intake. However, real-time assessment of milk intake is difficult, and issues with sucking often become apparent after the infant shows signs of nutrient deficiency. Traditional assessments by clinicians rely on the expertise and subjective judgment of healthcare professionals, enabling personalized evaluations. In this research, we introduce a novel approach to identifying sucking patterns by leveraging data collected from infants during breastfeeding sessions. This method utilizes artificial nipple-based sensors to capture the tongue forces exerted by infants, generating valuable clinical data. In the analysis of the collected time-series data, we applied machine-learned computational modeling (MLCM) algorithms to extract pertinent features and identify distinctive sucking patterns. The best-performing model demonstrated an accuracy of 90%, an 80% recall score, a perfect 100% precision score, a 0.90 f1-score, and an area under the curve (AUC) of 0.80. The proposed classification system has the potential to serve as a reliable decision-support tool for clinicians, offering valuable insights into infants' sucking behaviors. By integrating machine learning (ML)-based computational modeling into clinical practice, we aim to enhance the early identification of unhealthy sucking patterns, allowing for timely interventions and pro-active healthcare management.
Optimization of Power Control for Autonomous Hybrid Electric Vehicles With Flexible Power Demand
Authors: Kargar Mohammadali , Song Xingyong
Published: September 2024

Technology advancement for on-road vehicles has gained significant momentum in the past decades, particularly in the field of vehicle automation and powertrain electrification. The optimization of powertrain controls for autonomous vehicles typically involves a separated consideration of the vehicle’s external dynamics and powertrain dynamics, with one key aspect often overlooked. This aspect, known as flexible power demand, recognizes that the powertrain control system does not necessarily have to precisely match the power requested by the vehicle motion controller at all times. Leveraging this feature can lead to control designs achieving improved fuel economy by adding an extra degrees-of-freedom to the powertrain control while maintaining safety and drive comfort. The present research investigates the use of an approximate dynamic programming (ADP) approach to develop a powertrain controller, which takes into account the flexibility in power demand within the ADP framework. The concept of reachable sets is incorporated into the ADP framework to ensure safety, improve ride comfort, and enhance the accuracy of the optimization solution. The formulation is based on an autonomous hybrid electric vehicle, while the methodology can also be applied to other types of vehicles. It is also found that necessary customization of the ADP algorithm is needed for this particular control problem to prevent convergence issues. Finally, a case study is presented to evaluate the effectiveness of flexible power demand, as addressed by the ADP method. The experiment demonstrates a 14.1% improvement in fuel economy compared to a scenario without flexible power demand.
A Fault Diagnosis Method for Electric Vehicle Lithium Power Batteries Based on Dual-Feature Extraction From the Time and Frequency Domains
Authors: Chang Chun , Dai Jiuhe , Pan Yaliang , Lv Lu , Gao Yang , Jiang Jiuchun
Published: September 2024

This study focuses on the safety and reliability issues of lithium-ion batteries, proposing a fault diagnosis strategy that leverages dual-feature extraction from both the time and frequency domains. Additionally, by modifying the traditional autoencoder, the study proposes a feature-guided autoencoder as an unsupervised model for extracting features in the time domain. Initially, wavelet packet decomposition and its energy-denoising treatment are employed to refine fault information within battery voltage signals. Subsequently, the reconstruction error outputted by the Feature-Guided Autoencoder is utilized as the time-domain fault feature, while the cosine similarity of the energy of signals in various frequency bands obtained after wavelet packet decomposition serves as the frequency-domain fault feature. Ultimately, this article selects the Isolation Forest algorithm for two-dimensional outlier detection of time and frequency features. Experimental results demonstrate that the feature-guided autoencoder proposed in this study not only enhances the sensitivity of time-domain fault features compared to traditional autoencoders and their variants but also optimizes issues related to training time and computational load. The effectiveness of the proposed dual-feature fault diagnosis method in both the time and frequency domains is validated through data from two actual vehicles, showing superior early fault detection capability relative to single-feature fault diagnosis methods.
Analysis of ansys fluent for Wall-Modeled Large-Eddy Simulation of Turbulent Channel Flow
Authors: Li Weiyi , Giometto Marco G.
Published: September 2024

This study assesses the accuracy of ansysfluent 19.2, a commonly employed general-purpose finite volume solver, in the context of wall-modeled large-eddy simulation for turbulent channel flow at a moderate Reynolds number, Reτ=2000. The sensitivity of the solution to variations in grid resolution, aspect ratio, grid arrangement (collocated versus staggered), and subgrid-scale (SGS) model is analyzed and contrasted to results from a corresponding direct numerical simulation (DNS) and a mixed pseudospectral and finite differences solver. Results indicate good convergence of first- and second-order statistics from the staggered grid setups as the grid is refined, whereas no clear trend is observed in cases with collocated grid setups. Velocity spectra show a lack of an apparent inertial range trend and rapid decay of energy density at high wavenumbers, with a spurious energy pile-up near the cutoff wavenumber indicating the presence of unphysical oscillations in the velocity fields. Grid refinement strengthens such oscillations in collocated grid setups and reduces them in staggered grid setups. Two-point streamwise velocity autocorrelation maps reveal an underprediction of turbulent structure size. In contrast, cross-stream autocorrelations agree with corresponding curves from direct numerical simulation, showing signatures of alternating high- and low-momentum streaks in the logarithmic layer.
Assessment of Aging Degradation in Rubber Using Quasi-Static Components of Ultrasonic Longitudinal Waves
Authors: Lai Quanqing , Xu Caibin , Wang Gonglin , Deng Mingxi
Published: September 2024

Aging degradation is the main form of failure of rubber in service, leading to a decline in its physical and mechanical properties. This paper presents an efficient method for assessing the aging degradation of rubber using the quasi-static component (QSC) of ultrasonic longitudinal waves induced by acoustic radiation. The experiments quantitatively observe the response of the QSC pulse to different levels of aging degradation. A pulse-echo ultrasonic transducer is employed to simultaneously capture the primary longitudinal wave (PLW) and QSC echoes, enabling the determination of the acoustic nonlinearity parameter of QSC with a single transducer excitation. The results suggest that, in comparison to traditional linear ultrasonic techniques based on attenuation coefficient and wave velocity measurements, the relative acoustic nonlinear parameter of QSC proves to be more sensitive to aging degradation in rubber. Particularly, the amplitude of the QSC pulse undergoes a significant change with increasing aging degradation, even when the PLW tone burst is completely attenuated. These findings confirm the effectiveness of QSC as a method for evaluating aging degradation in highly attenuative materials.
Case Studies and Parametric Analysis of Heliostat Performance With a Tradeoff-Informed Technoeconomic Analysis Metric
Authors: Zolan Alexander , Augustine Chad , Armijo Kenneth
Published: September 2024

The Heliostat Consortium (HelioCon) was launched in 2021 to advance heliostat technology. This work presents a collection of baseline case studies for the technoeconomic analysis (TEA) of candidate heliostat improvements for concentrating solar power (CSP) and concentrated solar thermal (CST) systems that employ central receivers. The case studies we develop include a large-scale CSP plant, a smaller, modular CSP plant, and a small CST plant used for industrial process heat. In this work, we also propose a novel metric for TEA of a plant component technology that recasts relative changes in levelized system costs into component-specific capital cost budgets. This measure, which we refer to as the equivalent breakeven installed cost, is the maximum budget for the technology component that leads to improved levelized costs. Finally, we perform a parametric analysis to show the impact of candidate technologies on the levelized cost of heat and, by extension, equivalent breakeven installed cost.
The Building Decarbonization in High-Density Cities: Challenges and Solutions
Authors: Lv Guoquan , Zhao Zilong , Zhao Kang , Ge Jian
Published: September 2024

Decarbonization of buildings is an imperative and challenging task. Beyond the common challenges associated with building decarbonization, those in high-density urban areas also face technical challenges due to geographical conditions and resource endowments. As decarbonization practices deepen, it has been found that reliance on conventional methods is fraught with difficulties, primarily due to the high proportion of incremental costs involved. This review study explores methods not widely incorporated into existing building energy efficiency standards but which hold the potential for aiding decarbonization. It advocates for a synergistic strategy involving surrounding infrastructure such as power and other building energy systems, innovative low-carbon building materials, and greenery to facilitate this transition.
Optimization of the Distributor Setup in an Axial Turbine at Speed-No-Load Using Machine Learning
Authors: Kranenbarg Jelle , Jonsson Pontus P. , Mulu Berhanu G. , Sundström Joel , Cervantes Michel J.
Published: September 2024

Axial hydraulic turbines are operated more frequently at standby mode operation, also known as Speed-No-Load (SNL), to connect rapidly to the grid when required. This operation is harmful to the turbine and is sometimes characterized by large rotating vortical flow structures extending from the vaneless space to the draft tube, introducing detrimental pressure pulsations. A previous study showed that the flow structures can be mitigated with individual control of the guide vanes. The present study is a continuation that aims to find the best distributor layout for mitigation of the flow structures by introducing machine learning. A reduced CFD model, without runner blades and spiral casing, is developed to generate steady-state input data for a Gaussian process regression model. The surrogate model predicts that the best distributor layout is to open seven guide vanes out of 20 in a row while keeping the remaining ones closed. A cross-validation with a transient simulation on the reduced CFD model shows that the flow structures are mitigated, resulting in a stable and predictable flow field. The pressure pulsations in the vaneless space have been reduced by up to 94%. In addition, there is no risk for cavitation in the distributor domain by not opening all guide vanes, and the forces on the runner hub are less compared to regular SNL operation. The proposed distributor setup can potentially increase the turbine’s life span and make it better suited for grid regulation purposes.
Heat Transfer in Drop-Laden Turbulent Flows
Authors: Mangani Francesca , Zonta Francesco , Roccon Alessio , Soldati Alfredo
Published: September 2024

We study the heat transfer process in a multiphase turbulent system composed by a swarm of large and deformable drops and a continuous carrier phase. For a shear Reynolds number of Re = 300 and a constant drops volume fraction of Θ = 5.4%, we perform a campaign of direct numerical simulations (DNS) of turbulence coupled with a phase-field method and the energy equation; the Navier-Stokes equations are used to describe the flow field, while the phase-field method and the energy equation are used to describe the dispersed phase topology and the temperature field, respectively. Considering four Prandtl numbers, Pr = 1, 2, 4 and 8 and two Weber numbers, We = 1.5 and 3.0, we investigate the heat transfer process from warm drops to a colder turbulent flow. Using detailed statistics, we first characterize the time evolution of the temperature field in both the dispersed and carrier phase. Then, we develop an analytic model able to accurately reproduce the behaviour of the dispersed and continuous phase temperature. We find that an increase of the Prandtl number, obtained via a decrease of the thermal diffusivity, leads to a slower heat transfer between the dispersed and carrier phase. Finally, we correlate the drop diameters and their average temperatures.
A Computational Analysis of Fluid-Structure Interaction in Metachronal Propulsion
Authors: Lou Zhipeng , Lei Menglong , Byron Margaret L. , Li Chengyu
Published: September 2024

Ctenophores employ flexible rows of appendages called ctenes that form the metachronal beating pattern. A complete cycle of such paddling consists of a power stroke that strokes backward to produce propulsion and a recovery stroke that allows the appendage to recover its initial position. Effective locomotion in these creatures relies on maximizing propulsion during the power stroke while minimizing drag in the recovery stroke. Unlike rigid oars, the ctenes are flexible during both the power stroke and the recovery stroke, and notably, their strokes are asymmetric, with faster movement during the power stroke. As previous research assumed uniform material properties. This assumption will eventually make the ctene deform more intensively in the power stroke than the recovery stroke due to the asymmetrical hydrodynamic forces. However, observations contradict these assumptions. One explanation posits that ctenes stiffen during the power stroke, enhancing their propulsive force, and become more flexible in the recovery stroke, reducing drag by minimizing the water-countering area. This study focusses on the influence of asymmetric stiffness on their propulsion mechanism. Inspired by nature, we conducted three-dimensional fluid-structure interaction (FSI) using an in-house immersed-boundary-method-based flow solver integrated with a nonlinear finite-element solid-mechanics solver. This integrated solver uses a two-way coupling that ensures a higher accuracy regarding the complexity due to the involvement of the multiple ctenes in a ctene row. The preliminary results show that the anisotropic stiffness of the ctene have better accuracy of deformation as compared to the deformation recorded by the high-speed camera. The asymmetric properties of the ctene material allow both the spatial and temporal asymmetry of the ctene beating pattern. Our investigation suggests that while symmetrical beating can only generate negative net thrust, a slightly asymmetrical beating can make the thrust positive. We find that power stroke period that cost 30% whole period can generates the highest thrust. As multiple ctenes involves, the interaction among ctenes can amplified the effects of the asymmetrical beating, so that the thrust generation is enhanced by 9 to 13 times because of it.
Investigation on Design Parameters of a Francis Turbine Runner for Optimization Based on 3-D Inverse Design Method
Authors: Nagata Shunsuke , Tamada Yoichiro , Irie Tatsuya , Miyagawa Kazuyoshi
Published: September 2024

In this paper, an effect of a blade loading and a lean angle at a runner inlet are investigated to understand the internal flow and the loss in the turbine runner. Furthermore, a new Francis turbine runner is designed to improve the turbine performance by the optimization method using the 3D Inverse Design Method and Computational Fluid Dynamics (CFD). According to the investigation of the blade loading and the internal flow, the pressure gradient and the centrifugal forces cause the spanwise secondary flow on the meridional plane of the runner. Also, it is confirmed that designing a runner with the after-loading at every span on the blade is effective in reducing the pressure gradient near the runner inlet, minimizing the spanwise secondary flow, and improving the performance. For the lean angle at the runner inlet, the positive blade lean angle, i.e., the band side forward inclination in the direction of runner rotation, is effective in reducing the pressure gradient on the meridional plane and controlling the secondary flow. The performance of the new runner optimized based on the discussion above has demonstrated the effectiveness of this investigation. These findings and the optimization method will be of great use for designers to develop or improve the turbine performance.
An Experimental Study on the Emission Dynamics in Fused Deposition Modelling (FDM) 3D Printing Process
Authors: Misztal Tad Jerzy , Addasi Omar , Albano Jooi , Liu Yang
Published: September 2024

Fused Deposition Modeling (FDM) 3D printing is a manufacturing process that involves the melting and layering of thermoplastic to create 3D objects. Concerns have arisen from the volatile organic compounds (VOCs) emitted when 3D printing filaments are heated to their melting points, posing environmental and health risks. In the present study, a series of experiments were conducted to characterize the thermal flow phenomena during FDM 3D printing, specifically focused on investigating the VOCs emission dynamics along with the thermal flow during heating and melting in the printing processes. A high-speed Schlieren imaging system and an infrared thermal imaging system were temporally synchronized to both qualitatively and quantitatively characterize the thermal effects and the thermal-induced multiphase flows during the 3D printing process within an FDM 3D printer. In addition, the VOC emissions during the printing process were quantified by using a spatially-distributed-and-temporally-synchronized metal-oxide sensor array system, which can achieve fast spatial tracking of the VOC emissions. By correlating the data from the multiple measurement systems, the VOC emission transport behaviors in the convective gas current were characterized in detail. The findings in this paper offer insights into off-gassing profiles of different filaments, aiding in the development of customized ventilation approaches.
Accessing the Melting Dynamics of Phase Change Material Under Reduced Gravity Conditions
Authors: Singh Shobhana , Kansara Keyur , Dwivedi Navin K. , Khodachenko Maxim L.
Published: September 2024

Phase Change Materials (PCMs) are widely used materials in thermal management applications. The passive working, good thermal stability and inherent thermophysical properties make PCM a natural fit for thermal control devices. However, their performance in real working conditions is often different from the behavior measured at lab scale owing to the effects occurring from varied heat sources, length scale, gravity forces, enthalpy and supercooling effects, etc. In this study, a two-dimensional computational fluid dynamic (CFD) model of a PCM-filled square enclosure with constant temperature bottom heating is developed to investigate the impact of reduced gravity on the melting process of PCMs and assess the dynamic characteristics that evolve with time. The control volume-based enthalpy porosity approach is utilized to simulate the melting process of paraffin-based PCM. Numerical simulations are carried out with reduced gravity environments by varying g to 0.2g. The evolution of flow regimes from conductive to convective through the destabilization of conductive state to the onset of Rayleigh-Benard convection, and chaotic flow is presented in terms of temperature and flow fields. It is found that when the gravity is reduced to 0.2g, the onset of convection delays by ∼ 3 times compared to the time taken by PCM under the standard gravity. In conclusion, the present study has provided valuable insights into the underlying physical phenomena of PCM melting in reduced gravity important in developing design strategies for PCM-based thermal energy storage systems that can operate effectively in reduced gravity environments.
Migration of a Leaky-Dielectric Droplet in the Fringe Electric Fields of Parallel Plate Capacitors
Authors: Melbye Julie , Wang Danling , Wang Yechun
Published: September 2024

This work numerically studies the dynamics of a droplet, uncharged and freely suspended in an immiscible fluid, driven to move by the fringe electric field generated by parallel plate capacitors. Both the droplet and the suspending fluid are considered as leaky dielectrics. The deformation and migration of the droplet through the fringe electric field into or away from the parallel plate capacitors is our focus. A three-dimensional spectral boundary element method for interfacial dynamics in electrical fields is modified and adopted for the current study. The influences of the material properties of the pair of immiscible fluids including the viscosity ratio, surface tension, conductivity, and permittivity on the direction and velocity of the droplet migration will be investigated. The effects of operational and design parameters on droplet motion, including the electrical field strength and the parallel plates’ gap width will be explored as well. In this preliminary study the numerical method will then be applied to investigate the entrapment processes of fine CO2 bubbles in two-dimensional MXene-membranes, a novel membrane technology newly developed for CO2 sensing, capture and reduction. This technology is being developed for an over-arching goal of understanding changes in ocean carbon cycle and controlling CO2 level globally. The efficiency of such a device will be discussed from the view point of fluid dynamics.