bluuebunny/crossref_metadata_2025 huggingface dataset:
CRISPR/Cas9‐based editing of NF‐YC4 promoters yields high‐protein rice and soybean
Authors: Wang Lei , O'Conner Seth , Tanvir Rezwan , Zheng Wenguang , Cothron Samuel , Towery Katherine , Bi Honghao , Ellison Evan E. , Yang Bing , Voytas Daniel F. , Li Ling
Published: September 2024

Genome editing is a revolution in biotechnology for crop improvement with the final product lacking transgenes. However, most derived traits have been generated through edits that create gene knockouts.

Our study pioneers a novel approach, utilizing gene editing to enhance gene expression by eliminating transcriptional repressor binding motifs.

Building upon our prior research demonstrating the protein‐boosting effects of the transcription factor NF‐YC4, we identified conserved motifs targeted by RAV and WRKY repressors in the NF‐YC4 promoters from rice (Oryza sativa) and soybean (Glycine max). Leveraging CRISPR/Cas9 technology, we deleted these motifs, resulting in reduced repressor binding and increased NF‐YC4 expression. This strategy led to increased protein content and reduced carbohydrate levels in the edited rice and soybean plants, with rice exhibiting up to a 68% increase in leaf protein and a 17% increase in seed protein, and soybean showing up to a 25% increase in leaf protein and an 11% increase in seed protein.

Our findings provide a blueprint for enhancing gene expression through precise genomic deletions in noncoding sequences, promising improved agricultural productivity and nutritional quality.
Legitimacy, voice and power in ride hailing labour movements in Kenya
Authors: Zollmann Julie
Published: September 2024

One way to improve gig work may be to strengthen worker voice via worker organisations. But organising gig workers under economic strain is difficult. In this article, I apply the power resources approach to two related but divergent cases of digital driver mobilisation—Mombasa and Nairobi—to demonstrate the relationship between the cultivation of internal and external legitimacy and the implications each has for different types of power. In Mombasa, association leaders mobilised a majority of local drivers and built internal legitimacy through geographic zone groups, direct communications and democratic norms. This legitimacy enabled them to use structural power, taking direct action against app companies. Unable to build internal legitimacy, Nairobi association leaders instead cultivated external legitimacy through media and politician appeals, using political power to press for regulation. However, workers contested representation by these leaders, raising questions about whether relying solely on external legitimacy increases effective worker voice.
Cost‐Effectiveness Ratio Analysis of LBBaP Versus BVP in Heart Failure Patients With LBBB
Authors: Wang Shengchan , Xue Siyuan , Jiang Zhixin , Hou Xiaofeng , Zou Fengwei , Yang Wen , Zhou Xiujuan , Zhang Shigeng , Zou Jiangang , Shan Qijun
Published: September 2024

Background

For the initial treatment strategy for patients with cardiac resynchronization therapy (CRT) indications, whether to choose left bundle branch area pacing (LBBaP) or biventricular pacing (BVP) remains controversial. We aimed to investigate the cost‐effectiveness ratio (CER) of LBBaP and BVP in heart failure (HF) patients with left bundle branch block (LBBB).

Methods

This observational study included HF patients with LBBB who underwent successful LBBaP or BVP. The primary outcomes were echocardiographic response (left ventricular ejection fraction [LVEF] increase ≥5%), LVEF improvement, hospitalization costs, and CER (CER = cost/echocardiographic response rate). Secondary outcomes included other echocardiographic parameters, New York Heart Association (NYHA), N‐terminal pro–B‐type natriuretic peptide (NT‐proBNP), pacemaker parameters, complications, ventricular arrhythmia (VA) events, HF hospitalization (HFH), and all‐cause mortality.

Results

A total of 130 patients (85 LBBaP and 45 BVP) were included (65.6 ± 10.0 years, 70.77% men). The median follow‐up period was 16(12,30), months. Compared with BVP, the LBBaP group showed a greater increase in LVEF (20.2% ± 11.8% vs. 10.5% ± 13.9%; p < 0.001), higher echocardiographic response rate (86.1% vs. 57.8%; p < 0.001), and lower hospitalization costs [$9707.7 (7751.2, 18,088.5) vs. $20,046.1 (18,840.1, 22,447.3); p < 0.0001]. The CER was 112.7 and 346.8 in LBBaP and BVP, respectively. The incremental cost‐effectiveness ratio (ICER = △cost/△echocardiographic response rate) was $−365.3/per 1% increase in effectiveness. LBBaP improved cardiac function more significantly than BVP. There were no significant differences in clinical outcomes.

Conclusions

LBBaP‐CRT is more cost‐effective than BVP, offering greater LVEF improvement, higher echocardiographic response rates, lower hospitalization costs, and more significantly improved cardiac function. These findings need large randomized clinical trials for further confirmation.
Health Transitions and the Rise of Modern Contraceptive Prevalence: Demand, Access, and Choice
Authors: Corker Jamaica , Biddlecom Ann , Abbasi‐Shavazi Mohammad Jalal , Ezeh Alex , Ponce de León Rodolfo Gómez
Published: September 2024

Improvements in health and mortality, known as the health transition, played important roles in the rise of modern contraceptive prevalence across countries. We describe key mechanisms and selected research evidence that show how health transitions helped shape contraceptive transitions around the world. Mechanisms include how decreases in child mortality rates affect the motivation to use contraception and how the organization and expansion of health care affect key barriers to contraceptive use. Substantial increases in child survival resulting from health transitions increase demand for deliberate fertility regulation and contraceptive use. Improved access to primary health care, particularly maternal and child health services and expansion into rural communities, was associated with increases in modern method use. Country‐specific policies that affected the organization and delivery of health care led to the dominance of particular modern methods in some countries. Empirical evidence is limited on how the quality of health care has affected aggregate level increases in modern method use. Using modern contraceptive prevalence to define the contraceptive transition reflects current data limitations but future research on the relationship of health transitions with macrolevel contraceptive prevalence trends may be able to incorporate more comprehensive aspects of how health transitions impact contraceptive choice and agency.
Main oral characteristics and treatment of ligneous gingivitis and periodontitis in individuals with plasminogen deficiency: A systematic review
Authors: Santos Diego Belmiro do Nascimento , da Silva Larissa Conrado , da Silva Isabelle do Vale Dantas , de Andrade Bruno Augusto Benevenuto , Maia Lucianne Cople , Tenório Jefferson R.
Published: September 2024

Objective

This systematic review evaluated the main clinical, radiographic, histopathological and treatment‐related characteristics of ligneous gingivitis (LG) and periodontitis (LP) in individuals with plasminogen deficiency (PD).

Material and Methods

Studies in humans diagnosed with PD, focusing on the evaluation of oral characteristics and treatment of the LG/LP were considered for inclusion criteria. Electronic searches were performed up to April 2024 in five databases and in the grey literature. Risk of bias was assessed according to the Joanna Briggs Institute Critical Appraisal Checklists for case reports. It was provided a narrative synthesis of the results.

Results

A total of 17 studies were included. All were case reports that analyzed 17 individuals with PD who presented with LG/LP. The relative frequency of PD type I was 56%, while type II constitutes the remaining 44%. In most studies, patients exhibited ulceration clinically, bone loss radiographically, and subepithelial eosinophilic material accumulation on histopathological evaluation. Conventional periodontal scaling was the most used management. All included studies provided well‐described clinical characteristics and confirmed plasminogen deficiency through laboratory testing. Only three studies had a risk of bias values lower than 15%.

Conclusions

Current evidence is limited and varied, complicating the diagnosis and treatment of GL/PL. Future studies should provide a more detailed account of treatments and include extended clinical and radiographic follow‐up.
Increase of Hepatitis B Surface Antibody Levels After Inactivated COVID‐19 Vaccine in Hemodialysis Patients: An Important Single‐Center Observation
Authors: Yaghoubi Fatemeh , Dalil Davood , Iranzadeh Saeid , Ghahramani Ali
Published: September 2024

Background

The effects of COVID‐19 vaccines on immunocompromised people such as hemodialysis (HD) patients are an important topic that should be addressed. This study reports an observation of the effect of the third dose of the Sinopharm vaccine (SphV3) on the level of hepatitis B surface antibody (anti‐HBs) in HD patients, and the differences between anti‐HBs titers before and after SphV3 were analytically evaluated.

Methods

This single‐center observational study involved all HD patients presented to Shariati Hospital, Tehran, Iran, from February 2021 to March 2022. All patients received three doses of the Sinopharm vaccine over 8 months. The anti‐HBs level is measured every 6 months as the routine evaluation against HBV infection for all HD patients. Three months before (anti‐HBs‐B3) and 3 months after (anti‐HBs‐A3) SphV3 were the routine times to measure the anti‐HBs titer during this study.

Results

Twenty‐five HD patients were enrolled. Overall, the anti‐HBs‐A3 was significantly higher than anti‐HBs‐B3 (p = 0.001). The anti‐HBs levels before and after SphV3 were not statistically remarkable in patients with diabetes and ischemic heart disease. The patients with a history of kidney transplant and those with a history of COVID‐19 had significant differences between anti‐HBs‐B3 and anti‐HBs‐A3 (p = 0.002, p = 0.003, respectively).

Conclusion

Our findings revealed that inactivated COVID‐19 vaccine may be involved in the humoral immune response to hepatitis B in HD patients. It may be novel and have significant implications for the vaccination protocol for immunocompromised patients, including those undergoing HD and transplant recipients.
Polarization and Partitioning Representation: How an Overlooked Aspect of Contemporary Democracy Leads to Polarizing Societies
Authors: Scholtz Hanno
Published: September 2024

Polarization within Western societies escalates, as citizens increasingly distrust their governments and disagree with one another in an increasingly emotional way. Departing from a literature devoid of ideas to break this destructive trend, this paper presents a novel approach: While societies have evolved—becoming more diverse, individualized, and interconnected—democratic systems have remained unchanged, hence rooted in outdated structures. This misalignment drives the rise of political polarization. Through a comprehensive review of literature and data across OECD countries, this paper states the generality of the polarization problem, with the U.S. only as severest example. It introduces the concept of ‘partitioning representation’ of representing individuals as parts of non‐overlapping subsets of society, a form that fitted a bygone era of geographically and socially partitioned communities. The paper identifies three mechanisms through which the disjunction between this traditional form of representation and contemporary individualization leads to polarization: disconnection of voters from the political process, intra‐party dynamics that favor radicalization, and perverse incentives for political and media actors. Ultimately, breaking this destructive cycle requires rethinking how representation can work in a world that no longer conforms to the partitioned societies of the Western past. This calls for new forms of doing politics, empowering citizens to engage meaningfully with the political process and restoring the capacity for collective problem‐solving that is essential for democratic resilience in a new approach usefully called a ‘civil democracy’.
Pregnancy Among Reported Lyme Disease Cases—United States, 1992–2019
Authors: Bostic Taylor D. , Kugeler Kiersten J. , Hinckley Alison F.
Published: September 2024

Background

Lyme disease (LD), the most common vector‐borne disease in the United States, typically presents with a localised erythema migrans rash (EM). Left untreated, infection can disseminate to cause severe heart, joint or nervous system manifestations. Summaries of LD surveillance data have been published previously but did not include the frequency, demographic or clinical characteristics of LD cases during pregnancy.

Methods

We summarised confirmed and probable LD cases by pregnancy status as reported to the U.S. Centers for Disease Control and Prevention during 1992–2019. We defined an LD case during pregnancy as one with (1) female sex, (2) age 14–49 years and (3) positive pregnancy indication. We evaluated the frequency, seasonality, age distribution, race and ethnicity, geographic distribution and clinical manifestations of LD cases during pregnancy and cases among non‐pregnant females. We compared proportions using chi‐squared tests.

Results

Among 698,876 reported LD cases, 112,002 (16%) were confirmed or probable cases among females aged 14–49 years; 32,301 (29%) were specifically reported as non‐pregnant and 643 (0.6%) (568 confirmed and 75 probable cases) reported as pregnant. Illness onset peaked in June among LD cases during pregnancy, but in July for cases among non‐pregnant females. A higher proportion of confirmed LD cases during pregnancy had only EM rash than did cases among non‐pregnant females (66% vs. 60%, p = 0.019).

Conclusions

LD cases during pregnancy are rare. Compared to non‐pregnant females, cases among pregnant females more commonly involve early clinical manifestations. These patterns could suggest earlier detection or more complete reporting of LD cases during pregnancy than their non‐pregnant counterparts. Earlier detection could be due to frequent contact with healthcare or increased self‐advocacy during pregnancy. Prompt antimicrobial treatment is critical for preventing severe disease and reducing risk of adverse pregnancy or birth outcomes.
Approximate identities for ideals in L(Lp)$L(L^p)$
Authors: Johnson W. B. , Schechtman G.
Published: September 2024

The main result is that the only non‐trivial closed ideal in the Banach algebra of bounded linear operators on , , that has a left approximate identity is the ideal of compact operators. The algebra has at least one non‐trivial closed ideal that has a contractive right approximate identity as well as many, including the unique maximal ideal, that do not have a right approximate identity.
High-Speed Three-Dimensional-Digital Image Correlation and Schlieren Imaging Integrated With Shock Tube Loading for Investigating Dynamic Response of Human Tympanic Membrane Exposed to Blasts
Authors: Alipanahi Anahita , Luiz Jonathan Oliveira , Rosowski John J. , Furlong Cosme , Cheng Jeffrey Tao
Published: September 2024

Investigating the dynamic response of human tympanic membranes (TMs) exposed to blasts requires full-field-of-view and three-dimensional (3D) methodologies. Our paper introduces a system that combines high-speed 3D digital image correlation (HS 3D-DIC) and Schlieren imaging (HS-SI) with a custom-designed shock tube for generating blast waves. This integrated system allows us to measure TM surface motions under intense transient loading, capturing full-field-of-view shape deformations exceeding 100 μm with a temporal resolution of 10 μs. System characterization encompasses (i) measuring the shock tube's output levels and repeatability, (ii) assessment of the spatial and temporal resolutions of the imaging techniques, and (iii) identification of overall system limitations. Optimizing these factors is crucial for improving the reliability of our system to ensure the accurate measurement of deformations. To assess our shock tube's reliability in generating repeated blast waves, we instrumented it with high-pressure (HP) and high-frequency (HF) pressure sensors along the blast wave pathway to record overpressure waveforms and compared them with Schlieren imaging visualized blast waves. We validate our HS 3D-DIC measured deformations by comparing them with deformations measured using single-point laser Doppler vibrometry (LDV), establishing a comprehensive assessment of the TM's dynamic response and potential fracture mechanics under blast. Finally, we test our approach with 3D-printed TM-like samples and a real cadaveric human TM. This methodology lays the groundwork for further investigations of blast-related auditory damage and the invention of more effective protective and medical solutions.
Quantifying the Fascicular Changes in Recovered Achilles Tendon Patients Using Diffusion Magnetic Resonance Imaging and Tractography
Authors: Rahimnezhad Shabnam , Arefin Tanzil M. , Bai Xiaoxiao , Neuberger Thomas , Cortes Daniel
Published: September 2024

Regardless of the way of treatment, persistent deficits in calf muscles in recovered patients from Achilles tendon rupture (ATR) exist long-term postinjury. Studies on calf muscle changes mostly highlight morphological changes in the calf muscles and Achilles tendon. However, limited attention has been given to fascicular changes. Diffusion tensor imaging (DTI) can provide a better understanding of the characteristics and properties of tissues with organized microstructure. In the current study, we used DTI-derived indices (mean diffusivity (MD), fractional anisotropy (FA), and eigenvalues—λ1, λ2, and λ3) and fiber tractography to better understand the soleus muscle after recovery from ATR by comparing the results of injured legs with healthy ones. Our findings suggest that the standard deviations of measured parameters (FA, MD, and eigenvalues) within the soleus muscle are better predictors of the changes associated with the ATR as compared to the control counterpart for the volumetric region of interest (ROI). Additionally, in four out of five participants, smaller tracts were observed in the injured leg compared to the healthy one, as evidenced by the fiber length distribution of the tracts. Altogether, this study demonstrates the feasibility of the DTI and fiber tractography approaches to quantify the fascicular changes in the individuals recovered from ATR.
Effects of Acid Etching on the Microstructure and Stiffness of Human Teeth
Authors: Zhai Yingnan , Shi Zhenshan , Premaraj Thyagaseely , Premaraj Sundaralingam , Karpova Tatiana , Dong Pengfei , Gu Linxia
Published: September 2024

The mechanical properties of acid-etched enamel and dentin are important for understanding tooth erosion and developing innovative dental restorative materials. In this study, the microstructure and mechanical properties of both enamel and dentin were characterized using scanning electron microscopy (SEM) and atomic force microscopy (AFM) to quantify the impact of acid etching. SEM images demonstrated that enamel rods have a diameter of approximately 5 μm, while dentinal tubules have a diameter of around 2 μm. After acid etching, the intertubular and peritubular regions were exposed, with the peritubular regions showing a thickness of approximately 1 μm. AFM measurements showed that the stiffness of enamel at the bottom, middle, and top layers is 26.28±4.24 GPa, 32.03±8.68 GPa, and 23.94±3.53 GPa, respectively. For dentin, the stiffness is 16.28±2.76 GPa at the bottom layer and 17.59±5.33 GPa at the middle layer. AFM morphology and stiffness maps illustrated the microstructures of enamel rod and sheaths, as well as dentin tubules in both unetched and acid-etched tooth sections. The stiffness of the acid-etched enamel rod and peritubular dentin decreased by 7-fold and 3.6-fold, respectively, compared to the unetched enamel rod and peritubular dentin.
Computational Modeling of Cough Droplet Behavior in the Human Upper Respiratory Airway
Authors: Khan Rafid Jahangir , Ilegbusi Olusegun
Published: September 2024

This study investigated the interaction of cough droplets with airflow in a realistic human airway. The ultimate aim was to understand the behavior of cough droplets inside the airway and to assess the potential of droplets to be retained in the airway or transmitted to the lungs. A computational fluid dynamics (CFD) model, based on the Euler–Lagrangian framework, was employed to predict the two-phase, droplet-laden transient cough flow in a realistic three-dimensional (3D) human airway. The airway geometry was reconstructed from patient computed tomography (CT) scan dataset. The discrete phase model was used to track the motion of the droplets in the air flow. Two distinct cough profiles—a strong cough and a weak cough—acquired experimentally from human subjects, were used as input to simulate normal and disordered cough functions. The effects of cough strength and droplet size on droplet retention and aspiration in the airway were investigated. It was found that droplet retention was significantly higher for a weak cough compared to a strong cough. For a weak cough, the highest droplet retention percentage exceeded 60%, while for a strong cough, it was less than 20%. Larger sized droplets were more likely to be aspirated into the lungs, especially under weak cough conditions. In the case of weak cough, more than 5% of the 200 μm sized droplets were aspirated into the lungs, whereas for strong cough, aspiration was less than 2%.
Active Data-Enabled Robot Learning of Elastic Workpiece Interactions
Authors: McCann Lance , Yan Leon (Liangwu) , Hassan Sarmad , Garbini Joseph , Devasia Santosh
Published: September 2024

During manufacturing processes, such as clamping and drilling of elastic structures, it is essential to maintain tool–workpiece normality to minimize shear forces and torques, thereby preventing damage to the tool or the workpiece. The challenge arises in making precise model-based predictions of the relatively large deformations that occur as the applied normal force (e.g., clamping force) is increased. However, precision deformation predictions are essential for selecting the optimal robot pose that maintains force normality. Therefore, recent works have employed force–displacement measurements at each work location to determine the robot pose for maintaining tool normality. Nevertheless, this approach, which relies on local measurements at each work location and at each gradual increment of the applied normal force, can be slow and consequently time prohibitive. The main contributions of this work are: (i) to use Gaussian process (GP) methods to learn the robot-pose map for force normality at unmeasured workpiece locations; and (ii) to use active learning to optimally select and minimize the number of measurement locations needed for accurate learning of the robot-pose map. Experimental results show that the number of data points needed with active learning is 77.8% less than the case with a benchmark linear positioning learning for the same level of model precision. Additionally, the learned robot-pose map enables a rapid increase of the normal force at unmeasured locations on the workpiece, reaching force-increment rates up to eight times faster than the original force-increment rate when the robot is learning the correct pose.
A Distributed Layered Planning and Control Algorithm for Teams of Quadrupedal Robots: An Obstacle-Aware Nonlinear Model Predictive Control Approach
Authors: Imran Basit Muhammad , Fawcett Randall T. , Kim Jeeseop , Leonessa Alexander , Hamed Kaveh Akbari
Published: September 2024

This paper aims to develop a distributed layered control framework for the navigation, planning, and control of multi-agent quadrupedal robots subject to environments with uncertain obstacles and various disturbances. At the highest layer of the proposed layered control, a reference path for all agents is calculated, considering artificial potential fields (APF) under a priori known obstacles. Second, in the middle layer, we employ a distributed nonlinear model predictive control (NMPC) scheme with a one-step delay communication protocol (OSDCP) subject to reduced-order and linear inverted pendulum (LIP) models of agents to ensure the feasibility of the gaits and collision avoidance, addressing the degree of uncertainty in real-time. Finally, low-level nonlinear whole-body controllers (WBCs) impose the full-order locomotion models of agents to track the optimal and reduced-order trajectories. The proposed controller is validated for effectiveness and robustness on up to four A1 quadrupedal robots in simulations and two robots in the experiments.1 Simulations and experimental validations demonstrate that the proposed approach can effectively address the real-time planning and control problem. In particular, multiple A1 robots are shown to navigate various environments, maintaining collision-free distances while being subject to unknown external disturbances such as pushes and rough terrain.
Stall Inception Analysis on Axial Compressors With Different Rotor Loading Distributions Under Radial Inlet Distortions
Authors: Sun Dakun , Zhu Hengyi , Xu Dengke , Hu Jiahao , Sun Xiaofeng
Published: September 2024

Stability studies were conducted on a single-stage, low-speed compressor with different rotor loading-distribution designs under a uniform inlet, 10% intensity, and 20% intensity total tip pressure distortion inlet conditions via numerical calculations, theoretical model predictions, and experimental methods. The steady numerical performance was in basic agreement with experimentally measured performance. The theoretical prediction model showed an error within 1.5%, which is less than that of the steady numerical calculation. The total tip pressure distortion reduced flow stability. Conversely, the design of moving the rotor loading axially rearward significantly improved the flow stability. The blade loading analysis showed that the radial distortion caused a radial redistribution of rotor loading. The increase in the rotor-tip loading due to tip distortion was the main reason for the reduced flow stability. In contrast, the design of moving the rotor loading axially rearward reduced the rotor-tip leading-edge loading, enhancing the flow stability. Moreover, an analysis of the unsteady flow validated the findings of the blade loading analyses. It was found that the periodic evolution of the tip leakage vortex (TLV) had an adverse effect on flow stability. In addition, the modified rotors could prevent the tip leakage flow (TLF) from spilling from the leading edge and prevent the interaction of different diffusing regions, decreasing the probability of flow separation.
Computational Analysis of Flow Around Two Wall-Mounted Trapezoidal Bluff Bodies Arranged in Tandem Position
Authors: Sarkar Sourav , Gupta Nishant , Debnath Koustuv , Lawrence Raj Prince Raj
Published: September 2024

Flow around two identical wall-mounted trapezoidal bluff bodies, arranged in tandem, is numerically investigated at a Reynolds number of 750,000. The investigation employs Reynolds-averaged Navier–Stokes (RANS) equations and the k–ω SST turbulence model. The effect due to the change of the angular orientation of the inclined faces (α) of this bluff body and the pitch distance (L/D) on hydrodynamic quantities and turbulence quantities is investigated. Furthermore, the drag coefficient and Strouhal number have also been evaluated to understand the vortex shedding and flow pattern-related phenomena. For d and intermediate types of bluff bodies, the streamwise mean velocity, cross-stream mean velocity, turbulence kinetic energy, and recirculation length decrease with the increase of α or L/D. Significant changes are also observed in the case of Strouhal number. Reduction in drag coefficient and recirculation length is observed with increased L/D at a constant α for d-type bluff bodies. The change of α and L/D also creates the formation of a periodic von Kármán vortex street at downstream of the second bluff body in the case of L/D = 7, making the flows more complex and unstable. The maximum size of the recirculation bubble occurs in the case of L/D = 10 at α = 30 deg. The investigation provides valuable insight into the complex dynamics of tandem configurations of wall-mounted bluff bodies.
Data-Guided Low-Reynolds-Number Corrections for Two-Equation Models
Authors: Hu Xiaohan , Huang George , Kunz Robert , Yang Xiang
Published: September 2024

The baseline Launder–Spalding k−ε model cannot be integrated to the wall. This paper seeks to incorporate the entire law of the wall into the model while preserving the original k−ε framework structure. Our approach involves modifying the unclosed dissipation terms in the k and ε equations specifically within the wall layer according to direct numerical simulation (DNS) data. The resulting model effectively captures the mean flow characteristics in both the buffer layer and the logarithmic layer, resulting in robust predictions of skin friction for zero-pressure-gradient (ZPG) flat-plate boundary layers and plane channels. To further validate our formulation, we apply our model to boundary layers under varying pressure gradients, channels experiencing sudden deceleration, and flow over periodic hills, with highly favorable results. Although not the focus of this study, the methodology here applies equally to the k–ω formulation and yields improved predictions of the mean flow in the viscous sublayer and buffer layer.
Improved Numerical Model to Investigate Self-Aeration Along Stepped Spillway
Authors: Masouminia Mohammadhosein , Türker Umut
Published: September 2024

The concept of understanding and predicting the behavior of flow characteristics such as velocity, pressure, and energy in the presence of bubbles and droplets of various morphologies has always fascinated researchers. Flow aeration has been a challenging topic contributing to drag force, flow morphology, and cavitation, which was successfully investigated through numerical studies. Subsequently, it has resulted in the development of numerical models that can predict and simulate the self-aerated flow more accurately with less cost and in a shorter time frame. This study presents a numerical model that utilizes drag coefficient, disperse phase diameter, and interfacial area concentration to provide a novel idea of drag force in the presence of bubbles and droplets in flow. As part of enhancing the numerical model's precision, a dynamic calibration parameter for drag coefficient is incorporated which captures the macro-and microflow characteristics as over- and subgrid effects. Additionally, bubbles and/or droplets lead to a variable eddy viscosity that implemented in the numerical model as modified mixture viscosity. Furthermore, this numerical model is implemented on a stepped spillway, a well-known structure that causes aeration, to validate its accuracy and present a better understanding of the flow velocity changes, pressure differences, aeration, and energy. Finally, this numerical model predicts the self-aeration with consistent precision to experimental data that can be used alternatively to create, investigate, and optimize the design of complex geometries like stepped spillways.
A Comparative Study on the Prediction of Hydrogen, Nitrogen, and Water Vapor of Regenerative Hydrogen Pump With Different Turbulence Models
Authors: Yang Tao , Wang Shengke , Sun Jinju
Published: September 2024

The flow in a regenerative hydrogen pump used in a proton exchange membrane (PEM) fuel cell system is complex, including velocity mixing, streamline distortion, swirling flow, corner flow, and possible boundary separation. Experimental measurement and computational fluid dynamics (CFD) prediction are the main methods used to evaluate such performance. In this work, regenerative hydrogen designed for fuel cell electric vehicles with an impeller diameter of 91 mm and a shaft speed of 22,000 rpm is tested with a mixture of nitrogen, hydrogen, and water vapor. During the test, the flowrate and shaft speed ranges are 151–881 L/min and 8000–22,000 rpm, respectively. The inlet pressure and temperature are 171 kPa and 66 °C, respectively. Then, the flow is predicted by the k − ε model, the renormalization group (RNG) k − ε model, the explicit algebraic Reynolds stress models (EARSM) and the shear-stress transport (SST) detached eddy simulation (DES) model. The differences between the tested and predicted performances are compared. With these results, the velocity distribution in the side channel, the radial force of the impeller and casting, and the changes in the downstream pressure and velocity are analyzed in consideration of the ability of the turbulence models to simulate each characteristic flow. On this basis, the differences and abilities of the turbulence models for predicting the flow in regenerative hydrogen pumps are summarized.
Walking Slope and Heavy Backpacks Affect Peak and Impulsive Lumbar Joint Contact Forces
Authors: Sturdy Jordan T. , Sessoms Pinata H. , Rizeq Hedaya N. , Silder Amy , Whittier Tyler T. , Silverman Anne K.
Published: September 2024

Heavy load carriage is associated with musculoskeletal overuse injury, particularly in the lumbar spine. In addition, steep walking slopes and heavy backpacks separately require adaptation of torso kinematics, but the combined effect of sloped walking and heavy backpack loads on lumbar joint contact forces is unclear. Backpacks with hip belt attachments can reduce pressure under the shoulder straps; however, it is unknown if wearing a hip belt reduces lumbar spine forces. We used a musculoskeletal modeling and simulation approach to quantify peak and impulsive L1L2 and L4L5 lumbar joint contact forces in the anterior/posterior shear and compressive directions during walking on 0 deg and ±10 deg slopes, with no backpack and with 40% body weight backpack load using two different backpack configurations (hip belt assisted and shoulder-borne). Both walking slope and backpack load significantly affected shear and compressive peak and impulsive forces. The largest peak shear and compressive forces of 1.57 and 5.23 body weights, respectively, exceed recommended limits and were observed during uphill walking with shoulder-borne loads. However, only impulsive force results revealed differences due to the backpack configuration, and this effect depended on walking slope. During downhill walking only, the hip belt-assisted configuration resulted compressive impulses lower than during shoulder borne by 0.25 body weight seconds for both L1L2 and L4L5. These results indicate that walking uphill with heavy loads causes high shear and compressive lumbar forces that may increase overuse injury risk. In addition, our results suggest it is especially important to wear a hip belt when walking downhill.
Theoretical Model and Experimental Application for Solute Diffusion in Leaching Test With Time-Dependent Boundary Conditions
Authors: Tong Shan , Sample-Lord Kristin M. , Li Yu-Chao , Lang Ji
Published: September 2024

Measuring the diffusion coefficient of clay-based liner materials is important in estimating and predicting long-term barrier performance in waste containment facilities. Various theoretical models, including the finite cylindrical model, have been commonly used to determine the diffusion properties of clay-based liner materials in leaching tests. However, the assumption of zero-concentration boundary conditions of the traditional finite cylindrical model contradicts the measured variation of concentration in real leaching tests, likely resulting in (1) underestimated and unconservative diffusion coefficient, or (2) requirement of a relatively large liquid-to-soil ratio and frequent leachate replacement in the experiment to maintain the zero-concentration boundary condition. In this study, a theoretical model was developed to evaluate the solute diffusion process within a soil specimen under arbitrary, time-dependent concentration boundary conditions. The proposed model, incorporating the time-dependent boundary conditions, provides efficient calculations of the concentration distribution and the cumulative fraction leached of solute across the soil specimen. The example application of the proposed model to experimental data demonstrates the capability of the proposed model to determine apparent diffusion coefficients of clay-based liner materials without introducing errors associated with the assumption of a zero concentration boundary condition. The proposed model provides a comprehensive method to investigate the dynamic transport behaviors of solutes through clay-based liner materials in future studies.
Thermal Performance Investigation of Vapor Chamber Under Partial Heating and Different Heat Flux Conditions: Effects of Inclination Angle
Authors: Varol Yasin , Oztop Hakan F. , Tamdoğan Enes , Parlak Murat , Şenocak Şafak Melih , Coşanay Hakan
Published: September 2024

The need for cooling technologies increases tremendously with raising demand on the powerful and compact electronics. There, it pushes the research and technology to the new investigations on varying heat transfer mechanisms and devices. While one of these devices is vapor chamber (VC), an experimental study has been carried out to investigate the heat transfer performance of a VC under partial heating, varying heat fluxes, and different inclination angles for different temperatures, in the current study. For this purpose, a VC with a dimension of 90 mm × 90 mm × 3 mm is evaluated via its resulting thermal resistance, performance, and the temperature distribution over the VC surface. There, the limited effect of inclination angle is observed on the performance, while the highest change is obtained with decreasing local heating surface area, thus increasing heat fluxes. Moreover, this trend is seen almost similar with a reasonable shift up or down according to the different temperature differences.
Measurement of Steam-Generator-Tube Vibration Damping Caused by Anti-Vibration-Bar Supports
Authors: Smith Bruce A. W. , Feenstra Paul , Liu Michael
Published: September 2024

In 2013, Atomic Energy of Canada Limited (now Canadian Nuclear Laboratories) experimentally measured the damping of a straight tube with a variety of tube supports to examine low-frequency damping. These tests were motivated by the discovery of severe tube damage caused by in-plane fluidelastic instability (FEI) in the U-bend regions of new replacement recirculating steam generators (SG). The measurements were intended to assess the applicability of existing design guidelines for estimating the support-related damping of a tube. In the tests, the damping ratios of a single steam generator tube were measured using both log-decrement and power-based methods. Noncontacting excitation and position-sensing techniques were employed to improve accuracy. Initial baseline tests explored configurations with no support and drilled-hole supports of different hole sizes, and these results were compared with previously published work. Subsequent tests were performed to measure damping of tube vibration parallel to flat-bar supports. Most of the tests were performed with the tube fully submerged in still water. The tests examined the effects of fluid (water or air), natural frequency, gap width, preload, and vibration normal to the bars. This paper describes the test apparatus, methods, and analysis techniques. A summary of the results is presented. The initial baseline results showed that the damping ratios measured without any supports and with a drilled-hole support were consistent with previously published data. However, the subsequent measurements showed that, contrary to a published design guideline, the anti-vibration bars resulted in no significant additional viscous or squeeze-film damping when the vibration was parallel to the bars. On the other hand, the results did show that anti-vibration bars could introduce significant in-plane Coulomb-type damping if there was sufficient tube-to-support preload or impacting.
Machine Learning Modeling for Predicting Tensile Strain Capacity of Pipelines and Identifying Key Factors
Authors: Park Dong-Yeob
Published: September 2024

Machine learning (ML) techniques have recently gained great attention across a multitude of engineering domains, including pipeline materials. However, their application to tensile strain capacity (TSC) modeling remains unexplored. To bridge this gap, this study developed and evaluated an ML model to predict the tensile strain capacity of girth-welded pipelines. The model was trained on over 20,000 data points derived from a TSC equation available in the literature. The ML model demonstrated robust performance in predicting tensile strain capacities. Evidence of this lies in the near-zero means, minimal standard deviations, and normal distribution of residuals for both the training and test datasets. These collectively suggest that the model provides a good fit for the data. Furthermore, the model's loss behavior indicates successful convergence and generalization, without signs of overfitting or underfitting. An analysis using the random forest method revealed that the geometry of the flaw, specifically the flaw depth, is the most influential variable in predicting the TSC. This could be attributed to its significant impact on the fracture toughness of materials. In contrast, material properties and fracture toughness exert less influence relatively, despite their contributions to the model. This finding underscores the importance of flaw geometry in TSC prediction models. Overall, the development of a data-driven TSC model has shown efficient TSC modeling. This model leverages ML techniques, allowing for continuous updates with new data via deep learning.
Defect Detection of Polyethylene Gas Pipeline Based on Convolutional Neural Networks and Image Processing
Authors: Wang Jun-qiang , Zha Sixi , Sun Jia-chen , Wang Yang , Lan Hui-qing
Published: September 2024

In this paper, a method based on image recognition was proposed to detect the defects of polyethylene (PE) gas pipeline, especially the deformation due to the indentation. First, the pipeline -detection VGG (PD-VGG) model was established based on the convolutional neural network (CNN), and appropriate model parameters were optimized through model training. The defect recognition rate of the improved model can reach 94.76%. Following, the weighted average graying algorithm was used to separate the defects characterized by deformation. Then, an improved gamma correction algorithm was applied to achieve image enhancement, and the interference of impurities adhered on intersurface of pipeline was also removed by using multilayer filters. The edge detection of the defect image was completed by using the Canny operator, and following the screening between the target contour and the interference contour by using top-contour. Finally, the algorithm for minimum outer rectangle algorithm was used to fit the defect contour, and the eigenvalues of deformation defects were extracted. The results indicate that the above defect detection method can better extract the deformation contour of the dented pipeline. The high agreement with the experimental results provides a basis for the research of effectively recognizing whether the pipeline has undergone ductile failure only through profile detection of defects.
Thermal Striping Limits Analysis on the Cylinder With a Defect of Liquid-Cooled Nuclear Fast Reactors
Authors: Yu Mingda , Du Juan , Shao Xuejiao , Pu Zhuo
Published: September 2024

The structural safety of the cylinder in liquid-cooled fast reactors is significantly affected by high-temperature thermal striping on the cylinder wall due to the free level fluctuation. Based on the elevated-temperature creep-fatigue evaluation theory of the RCC-MRx rules, combined with the finite element and numerical heat transfer analysis methods, a thermal analysis method appropriate for the fast reactor cylinder containing hypothetical cracks after being subjected to normal transient loads was established. The proposed model is validated compared with the test reactors, FAENA and SUPERSOMITE, and the calculated thermal striping limits agree with the experimental data. Furthermore, the involved model was implemented to predict the thermal striping limits for several ideal normal transients. Simultaneously, the effects of some key parameters, including the frequency, the heat transfer coefficient, wall thickness, and the mean temperature of the fluid on the thermal striping limit of the SS316 stainless steel cylinder were studied.
Design and Implementation of a Computer-Controlled Hybrid Oscillatory Ventilator
Authors: Cruz Andrea F. , Herrmann Jacob , Hajdarevic Bakir , Hawley Monica L. , Fox Donald , Bates Jason H. T. , Kaczka David W.
Published: September 2024

During mechanical ventilation, lung function and gas exchange in structurally heterogeneous lungs may be improved when volume oscillations at the airway opening are applied at multiple frequencies simultaneously, a technique referred to as multifrequency oscillatory ventilation (MFOV). This is in contrast to conventional high-frequency oscillatory ventilation (HFOV), for which oscillatory volumes are applied at a single frequency. In the present study, as a means of fully realizing the potential of MFOV, we designed and tested a computer-controlled hybrid oscillatory ventilator capable of generating the flows, tidal volumes, and airway pressures required for MFOV, HFOV, conventional mechanical ventilation (CMV), as well as oscillometric measurements of respiratory impedance. The device employs an iterative spectral feedback controller to generate a wide range of oscillatory waveforms. The performance of the device meets that of commercial mechanical ventilators in volume-controlled mode. Oscillatory modes of ventilation also meet design specifications in a mechanical test lung, over frequencies from 4 to 20 Hz and mean airway pressure from 5 to 30 cmH2O. In proof-of-concept experiments, the oscillatory ventilator maintained adequate gas exchange in a porcine model of acute lung injury, using combinations of conventional and oscillatory ventilation modalities. In summary, our novel device is capable of generating a wide range of conventional and oscillatory ventilation waveforms with potential to enhance gas exchange, while simultaneously providing less injurious ventilation.
Equivalent Circuits for Exergy Flow in Thermodynamic Systems
Authors: Kocher Jordan D. , Yee Shannon K.
Published: September 2024

The second law of thermodynamics explains the nature of all spontaneous processes, and it imposes a limit on the performance of all technologies, from heat engines to refrigerators. These limits are well described as early as Sadi Carnot's 1824 publication that established the field of thermodynamics; researchers later developed the concept of exergy, or the available work, that a thermodynamic system can produce when interacting with a specified environment. In this work, we describe a resistance analogy for thermodynamic systems, in which the need to remove entropy forces some amount of energy to leave the system as heat rejection. Specifically, it is the inverse temperature of the heat sink that resists energy flowing out of the system as heat rejection. An equivalent circuit can be drawn for any thermodynamic system, with energy flowing through different branches of the circuit. The different paths correspond to different energy and exergy flows, including the energy that must flow out of the system as heat rejection and, therefore, cannot contribute to the exergy content of the system. After establishing this equivalent circuit, it is applied to a natural gas combined cycle example problem, a desalination example problem, and a transient heating problem.