bluuebunny/crossref_metadata_2025 huggingface dataset:
Hydraulic traits are not robust predictors of tree species stem growth during a severe drought in a wet tropical forest
Authors: Smith‐Martin Chris M. , Muscarella Robert , Ankori‐Karlinsky Roi , Delzon Sylvain , Farrar Samuel L. , Salva‐Sauri Melissa , Thompson Jill , Zimmerman Jess K. , Uriarte María
Published: November 2022

Severe droughts have led to lower plant growth and high mortality in many ecosystems worldwide, including tropical forests. Drought vulnerability differs among species, but there is limited consensus on the nature and degree of this variation in tropical forest communities. Understanding species‐level vulnerability to drought requires examination of hydraulic traits since these reflect the different strategies species employ for surviving drought.

Here, we examined hydraulic traits and growth reductions during a severe drought for 12 common woody species in a wet tropical forest community in Puerto Rico to ask: Q1. To what extent can hydraulic traits predict growth declines during drought? We expected that species with more hydraulically vulnerable xylem and narrower safety margins (SMP50) would grow less during drought. Q2. How does species successional association relate to the levels of vulnerability to drought and hydraulic strategies? We predicted that early‐ and mid‐successional species would exhibit more acquisitive strategies, making them more susceptible to drought than shade‐tolerant species. Q3. What are the different hydraulic strategies employed by species and are there trade‐offs between drought avoidance and drought tolerance? We anticipated that species with greater water storage capacity would have leaves that lose turgor at higher xylem water potential and be less resistant to embolism forming in their xylem (P50).

We found a large range of variation in hydraulic traits across species; however, they did not closely capture the magnitude of growth declines during drought. Among larger trees (≥10 cm diameter at breast height—DBH), some tree species with high xylem embolism vulnerability (P50) and risk of hydraulic failure (SMP50) experienced substantial growth declines during drought, but this pattern was not consistent across species. We found a trade‐off among species between drought avoidance (capacitance) and drought tolerating (P50) in this tropical forest community. Hydraulic strategies did not align with successional associations. Instead, some of the more drought‐vulnerable species were shade‐tolerant dominants in the community, suggesting that a drying climate could lead to shifts in long‐term forest composition and function in Puerto Rico and the Caribbean.

Read the free Plain Language Summary for this article on the Journal blog.
Below‐ground net primary productivity stability in response to a nitrogen addition gradient in an alpine meadow
Authors: Ma Fangfang , Chen Weinan , Wang Jinsong , Tian Dashuan , Zhou Qingping , Niu Shuli
Published: November 2022

Temporal stability of ecosystem productivity is important for providing reliable ecosystem services under global changes. Great efforts have been made to explore the response of above‐ground net primary productivity (ANPP) stability to nitrogen (N) enrichment, yet how it affects below‐ground net primary productivity (BNPP) stability remains elusive, which hinders a comprehensive understanding of ecosystem stability from the view of a whole system.

Here, using a field manipulative experiment with six N addition rates (0, 2, 4, 8, 16, 32 g N m−2 year−1), we explored the response patterns and drivers of BNPP stability in the topsoil (0–20 cm) and subsoil (20–40 cm) in the alpine meadow.

The results showed that BNPP stability at both soil depths showed a unimodal response to increasing N addition rates. Specifically, for both the topsoil and subsoil, low‐level N addition significantly promoted BNPP stability, while high doses of N addition had no significant impact on BNPP stability, suggesting that current low level of N deposition likely benefits the stable provision of below‐ground functioning. Furthermore, dominant species stability and species richness contributed most to the changes in BNPP stability in the topsoil, whereas only dominant species stability was the dominant driver of BNPP stability in the subsoil.

This study is among the first to illuminate the main mechanisms underlying the responses of BNPP stability to N enrichment at various soil depths, which will advance our current understanding of N addition effects on below‐ground processes and benefit the sustainable provision of ecosystem functioning in the context of atmospheric N deposition.

Read the free Plain Language Summary for this article on the Journal blog.
An effective scheme of joint migration inversion in the pseudo‐time domain
Authors: Qu Shan , Verschuur Dirk Jacob
Published: November 2022

Traditional full‐waveform inversion is a non‐linear and ill‐posed inversion problem. To reduce the non‐linearity of it, joint migration inversion (joint migration inversion) was proposed as an alternative. Joint migration inversion tries to minimize the mismatch between measured and modelled reflection data. One key feature of joint migration inversion is its parameterization: two separate parameters, reflectivity (for the amplitudes of reflected events) and propagation velocity (for the phase effects). This separation helps to reduce the non‐linearity of the inversion. During joint migration inversion, with the velocity being updated, the reflectors in the updated image are also shifting in depth accordingly, this phenomenon is called depth–velocity ambiguity. This interaction between the two parameters during inversion is desired to keep the image time consistent with the measured data but may lead to non‐robustness of joint migration inversion due to the presence of local minima. Therefore, we propose a more robust joint migration inversion scheme, which parameterizes the models with vertical time, termed pseudo‐time joint migration inversion. In pseudo‐time, the updates of velocity will not result in the associated vertical location changes of reflectors in the estimated image. Instead, the reflectors are mainly getting more focused. One limitation is that the depth‐pseudo‐time conversion process assumes a simple linear relationship between depth and pseudo‐time, which might cause some artefacts in the converted models when there exist strong lateral velocity variations. One subsequent round of depth joint migration inversion is recommended to resolve this issue. We demonstrate the effectiveness of our proposed method with a two‐dimensional synthetic example in an extreme scenario, where the initial velocity model is homogeneous, a realistic offshore two‐dimensional synthetic example, a two‐dimensional field example from the Vøring basin in Norway and a simple three‐dimensional synthetic example. In all examples, pseudo‐time joint migration inversion manages to recover more reasonable updates in the inverted velocity and invert more focused reflectors in the inverted image, compared to depth joint migration inversion.
Rigour vs. Reality: Contextualizing Qualitative Research in the Low‐Income Settings in Emerging Markets
Authors: Halme Minna , Piekkari Rebecca , Matos Stelvia , Wierenga Marleen , Hall Jeremy
Published: November 2022

Management scholars increasingly conduct qualitative research in low‐income settings in emerging markets. These large communities, which often operate in the informal economy and cut across national boundaries, face enormous challenges in meeting basic needs. Nevertheless, low‐income settings have not received separate methodological attention and are often subsumed instead under the more general and homogenous category of emerging markets. We argue that application of Western methodological conventions to low‐income settings may result in decontextualized and distorted knowledge that does not advance societal betterment. We characterize research that strictly follows methodological rules and steps, with limited contextualization for low‐income settings as ‘rigour‐by‐convention’. In turn, we introduce the alternative concept of ‘rigour‐within‐context’, which reconciles the seemingly opposing goals of rigorous and contextualized research. In this approach, researchers contextualize their research, even if this means deviating from established conventions. Hence, rigour should be judged by its internal logic rather than by external rules or templates not designed to capture key insights from low‐income settings. We conclude by recommending the means through which contextualized research on low‐income settings can be conducted.
Floral composition and diversity of the lagos coastal environment, South‐Western, Nigeria
Authors: Ajikah Linus B. , Adekanmbi Olusola H. , Oyebanji Oyetola O. , Agboola Oludare O. , Akomaye Ferdinand A. , Adeonipekun Peter A. , Onuminya Temitope O. , Bamford Marion , Ogundipe Oluwatoyin T.
Published: November 2022

The present study investigates the floral diversity of the Lagos coastal environments by sampling 21 points using the quadrat method. The study revealed two major aquatic ecosystem types (mangrove and freshwater swamp) and recorded 125 species belonging to 108 genera and 49 families. While Alchornea cordifolia and Raphia hookeri were found as the most frequent, Acalypha crenata and Acrostichum aureum were the least abundant species. The highest and lowest species‐rich locations were Unilag (n = 125 species) and Abule Osun (n = 2 species), respectively. The vegetation structure of the LCE is dominated by herbaceous species. Our findings provide insights on the flora diversity of the LCE, and a guideline for the effective conservation of near‐threatened species such as Nauclea diderrichii and Mitragyna stipulosa in this coastal ecosystem is presented.
Addressing workplace gender inequality: Using the evidence to avoid common pitfalls
Authors: Ryan Michelle K.
Published: November 2022

In this Landmark article I outline four common missteps that are made when designing and implementing workplace gender equality initiatives: (1) when we don't go beyond describing the numbers; (2) when we try to ‘fix’ women rather than fix systems; (3) when we are overly optimistic about the progress we have made; and (4) when we fail to recognise the intersectionality of the experiences that women face. I will briefly consider each of these missteps in term, presenting research that suggests alternative ways of approaching gender equality initiatives.
Successful combined auxiliary partial liver and intestinal transplantation in two highly sensitized, cross‐match positive patients
Authors: Wu Guosheng , Liu Chaoxu , Ma Nan , Zhou Xile , Zhao Long , Zhang Yuntao , Zhang Wentong , Liang Tingbo
Published: November 2022

Introduction

Sensitization to human leukocyte antigen (HLA) creates an immunological barrier to intestinal transplantation (ITx). Current desensitization therapies are limited and ineffective in the most highly sensitized patients. A co‐transplanted whole liver transplant can protect a kidney, heart, or intestinal allograft from antibody‐mediated injury. Whether an auxiliary partial liver allograft provides effective protection for highly sensitized intestinal transplant recipients is unknown.

Methods

Two patients with strong HLA donor‐specific antibody at high titer against their deceased donors underwent combined auxiliary partial liver and ITx across a positive cross‐match. The left lateral lobes from the combined‐graft recipients and the right liver lobes from the deceased donors were transplanted as a domino procedure to other four patients.

Results

Two combined‐graft recipients have had an uneventful postoperative course without major complications at a 12‐ and 24‐month follow‐up, respectively. Intestinal graft function has been excellent with no evidence of humoral or cellular rejection. While a positive cross‐match turned negative, titers of donor‐specific HLA antibodies gradually declined over time after transplant. The left liver lobes procured from the combined‐graft recipients were successfully transplanted into two pediatric patients (age 1.9, 2.4 years) and the right lobes from two deceased donors were successfully transplanted into two adult patients. All transplant procedures went well, without post‐operative complications related to the splitting technique.

Conclusion

Our results indicate that an auxiliary liver transplant can effectively protect a co‐transplanted intestinal allograft against rejection and suggest that this combined procedure may serve as a useful therapeutic adjunct for a highly sensitized intestinal transplant candidate.
Infants show enhanced neural responses to musical meter frequencies beyond low‐level features
Authors: Lenc Tomas , Peter Varghese , Hooper Caitlin , Keller Peter E. , Burnham Denis , Nozaradan Sylvie
Published: November 2022

Music listening often entails spontaneous perception and body movement to a periodic pulse‐like meter. There is increasing evidence that this cross‐cultural ability relates to neural processes that selectively enhance metric periodicities, even when these periodicities are not prominent in the acoustic stimulus. However, whether these neural processes emerge early in development remains largely unknown. Here, we recorded the electroencephalogram (EEG) of 20 healthy 5‐ to 6‐month‐old infants, while they were exposed to two rhythms known to induce the perception of meter consistently across Western adults. One rhythm contained prominent acoustic periodicities corresponding to the meter, whereas the other rhythm did not. Infants showed significantly enhanced representations of meter periodicities in their EEG responses to both rhythms. This effect is unlikely to reflect the tracking of salient acoustic features in the stimulus, as it was observed irrespective of the prominence of meter periodicities in the audio signals. Moreover, as previously observed in adults, the neural enhancement of meter was greater when the rhythm was delivered by low‐pitched sounds. Together, these findings indicate that the endogenous enhancement of metric periodicities beyond low‐level acoustic features is a neural property that is already present soon after birth. These high‐level neural processes could set the stage for internal representations of musical meter that are critical for human movement coordination during rhythmic musical behavior.

Research Highlights

5‐ to 6‐month‐old infants were presented with auditory rhythms that induce the perception of a periodic pulse‐like meter in adults.

Infants showed selective enhancement of EEG activity at meter‐related frequencies irrespective of the prominence of these frequencies in the stimulus.

Responses at meter‐related frequencies were boosted when the rhythm was conveyed by bass sounds.

High‐level neural processes that transform rhythmic auditory stimuli into internal meter templates emerge early after birth.
Ahead of the pain: Where we stand after a decade of growth in United Council for Neurologic Subspecialties‐certified headache subspecialists
Authors: Kanegi Skyler L. , Rosen Noah L.
Published: November 2022

Objective

To characterize the geographic distribution of United States (US) headache subspecialists in 2021 compared to 2012 and analyze trends in distribution of and growth by geography.

Introduction

Headache disorders are the second‐highest cause of disease burden worldwide. Historically, headache disorders have been treated by primary care and emergency physicians, often suboptimally. Our 2012 study identified further disparities in geographic distribution of United Council for Neurologic Subspecialties (UCNS)‐certified headache subspecialists.

Methods

This correlational population study explores the current geographic distribution of and changes in subspecialists by aggregating data from the UCNS, National Health Interview Survey, US Census, Bureau of Economic Analysis, and American Community Survey.

Results

In 2021, there were 692 UCNS‐certified headache subspecialists. There continued to be higher subspecialist density in the Northeast (1:34,678) and Midwest (1:55,005), with the highest density in Vermont (1:12,510) and Connecticut (1:20,419). The highest absolute subspecialist increases were in the South (99), California (35), and Texas (25). The highest relative subspecialist increases were in the West (105%), Vermont (500%), and Mississippi (500%). The univariable regressions showed significant associations between number of subspecialists and adult headache population (R2 = 0.797, p < 0.001), between subspecialist density and personal income (R2 = 0.935, p = 0.033), and between growth in subspecialists and poverty rate (R2 = 0.553, p = 0.022). However, the multivariable regressions showed that only the adult population was significantly associated with number of subspecialists (adjusted R2 = 0.806, p < 0.001).

Conclusion

Overall, there has been substantial growth in the number of UCNS‐certified headache subspecialists in the US, especially relative to growth in adult headache population. Subspecialist density continues to be highest in the Northeast and is associated with higher per capita personal income. However, there has been encouraging growth in geographies that previously had little to no access. These findings represent positive progress, but there is more to be done to both increase access to optimal headache care by subspecialists nationally and decrease geographic disparities in access to care.
General practitioners' wellbeing during the COVID‐19 pandemic: Novel methods with social media data
Authors: Golder Su , Jefferson Laura , McHugh Elizabeth , Essex Holly , Heathcote Claire , Castro Avila Ana , Dale Veronica , Van Der Feltz‐Cornelis Christina , Bloor Karen
Published: November 2022

Background

It is difficult to engage busy healthcare professionals in research. Yet during the COVID‐19 pandemic, gaining their perspectives has never been more important.

Objective

To explore social media data for insights into the wellbeing of UK General Practitioners (GPs) during the Covid‐19 pandemic.

Methods

We used a combination of search approaches to identify 381 practising UK NHS GPs on Twitter. Using a two stage social media analysis, we firstly searched for key themes from 91,034 retrieved tweets (before and during the pandemic). Following this we used qualitative content analysis to provide in‐depth insights from 7145 tweets related to wellbeing.

Results

Social media proved a useful tool to identify a cohort of UK GPs; following their tweets longitudinally to explore key themes and trends in issues related to GP wellbeing during the pandemic. These predominately related to support, resources and public perceptions and fluctuations were identified at key timepoints during the pandemic, all achieved without burdening busy GPs.

Conclusion

Social media data can be searched to identify a cohort of GPs to explore their wellbeing and changes over time.
Social representation of nonacademic work from the perspective of company gatekeepers in the Mexican tourism sector
Authors: Hunink Claudia , Raesfeld Lydia
Published: November 2022

Cooperations or transfers of the German technical and vocational education and training (TVET) system have taken place in different cultural contexts in recent decades. In Mexico, the so‐called Modelo Méxicano de Formación Dual has been adapted to Mexico's cultural conditions. Yet, it still seems to be largely unknown in society, the education system and the labour market. Attitudes, perceptions or so‐called ‘social representations’ are culturally anchored in a society and can be identified in artefacts and individual narratives. Especially social representations of company gatekeepers, such as human resources employees are focused because they regulate access in companies and to higher positions. Although this happens on the basis of organizational transition policies, decision‐making processes are shaped by culturally anchored individual perceptions. The target group of company gatekeepers from the tourism sector was interviewed within the framework of a qualitative study during eight semistructured ‘face‐to‐screen’ interviews, analysed according to grounded theory methodology. Based on social representation analysis, the Mexican labour market seems to be dichotomized. Academic titles have a high symbolic value, promising prestige. TVET options are given little focus, lack a high social esteem and are still largely unknown. Those produce técnicos, while holders of oficos often do on‐the‐job training within their families. Both depend upon their employers and have to accept unfavourable working conditions. This implies physically demanding, often gender‐specific work. Promotions are possible, even without academic degrees. Because of a lack of institutionalization, these are subjective, depending on the goodwill of company gatekeepers. Promotions are possible to a certain extent, so nonacademic workers are facing a glass ceiling.
Hydrodynamic cavitation processing of ascorbic acid treated precooled sugarcane juice for physiochemical, bioactive, enzyme stability, and microbial safety
Authors: Bhukya Jithender , Mohapatra Debabandya , Naik Ravindra
Published: November 2022

A hydrodynamic cavitation (HC) system (0.35 MPa) with a cooling arrangement was developed for the treatment of ascorbic acid (AA)‐treated sugarcane juice (AASCJ). The AASCJ was precooled to different temperatures (4, 17, and 30°C) and underwent HC processing for different durations (10, 20, 30, and 40 min). The quality parameters such as pH, total soluble solids, titratable acidity, polyphenol oxidase (PPO), peroxidase (POD) activity, viscosity, total color difference, microbial load, total phenolic, flavonoids, AA, and antioxidant activity were investigated. The processed AASCJ precooled to 4°C resulted in more than 90% retention in color, total phenolic content, flavonoid content, and antioxidant activity. The PPO and POD activities significantly reduced after HC treatment. A 3 log reduction in the microbial population was achieved during HC processing. The optimized condition for HC treatment of AASCJ was a precooling temperature of 4°C and a treatment time of 30 min.

Practical applications

Sugarcane juice has a short shelf life due to the high rate of microbiological contamination and enzymatic reactions that occur shortly after extraction. Low‐temperature HC is a nonthermal approach for processing low viscous liquid foods. The HC processed AASCJ is microbiologically safe, with reduced PPO and POD activity, and better retention of bioactive compounds. The low‐temperature HC processing can be used instead of thermal processing to reduce both enzymatic and nonenzymatic browning reactions and eradicate pathogenic microorganisms while maintaining the sugarcane juice quality. This approach is simple to handle, requires little investment, and does not use environmentally hazardous chemicals.
Subjective and objective evaluation of masticatory function in patients with bimaxillary implant‐supported prostheses
Authors: Homsi George , Karlsson Anna , Almotairy Nabeel , Trulsson Mats , Kumar Abhishek , Grigoriadis Anastasios
Published: November 2022

Background

People perform poorly in masticatory function tests despite well‐functioning prostheses. However, it is unclear whether there is an agreement between subjective and objective measures of mastication.

Objectives

To investigate the association between subjective and objective measures of masticatory function in patients with bimaxillary implant‐supported prostheses.

Materials and Methods

An experimental group (n = 25, age = 70.6 ± 7.5 years, eight women) with bimaxillary implant‐supported fixed prostheses and a control group (n = 25, age = 69.0 ± 5.3, 13 women) with natural dentition were recruited. The participants in the experimental group were included if they had been using the prosthesis for at least a year and had no obvious complaints with their prostheses. The control group was people with natural dentition and without any prostheses or complaints related to the masticatory system. The masticatory function was evaluated objectively with food comminution and mixing ability tests, and subjectively with jaw function limitation scale (JLFS) and oral health impact profile (OHIP).

Results

The experimental group performed poorly in both objective tests (p < .001). However, there was no significant differences between the two groups in total JFLS (p = .114) and OHIP (p = .312) scores. Though, there were certain positive correlations between the food comminution test and JFLS subdomains in the control group, and a positive correlation between food comminution test and specific subdomains of OHIP in the experimental group indicating poor correlation between the subjective and objective measures.

Conclusion

Although patients with implant prostheses show poor masticatory performance, there is no agreement in the objective and subjective measures of mastication.
Chopsticks and clothes: Chinese heritage parents' perspectives on young children's technology use as a tool for language and cultural learning
Authors: Hao Ling
Published: November 2022

This paper presents Chinese heritage parents' perspectives on young children's use of technology as a tool for language and cultural learning. Growing up with Confucian heritage culture, some Chinese parents have particular cultural beliefs about learning that value effortful learning practices and the social context of learning. However, some Chinese parents believe technology is just a tool for entertainment and keeps children away from social interaction, which leads to their preference of print‐based literacy practices at home. Four parents from different families whose children were between the ages of four to five participated in this study. These parents were interviewed about their experience and history of using technology and their thoughts about technology as a tool for language and cultural learning. Four narratives were constructed to describe parents' experiences, histories, opinions, cultural values and beliefs. Parents' perspectives were influenced by a variety of intertwined factors, including their own childhood language learning experiences, their histories of using technology, their cultural values and beliefs about learning, the purpose of technological experiences, and the quality of available technological resources. Pedagogical implications for using technology with children and communicating with parents are discussed.
Factors associated with nursing students' self‐regulated learning in clinical practicum: A descriptive cross‐sectional study
Authors: Subaş Furkan , Karaçay Pelin
Published: November 2022

Self‐regulated learning is essential to nursing students' professional development, especially in the management of their learning and adaptation to complex clinical learning environments. This study aimed to explore the self‐regulated learning status and associated factors of nursing students in clinical practicum. The study was conducted with 764 second‐, third‐, and fourth‐year nursing students from 135 nursing undergraduate programs in Turkey. Data were collected using a questionnaire that consisted of sociodemographic characteristics, factors affecting learning, and the “Self‐Regulated Learning Scale in Clinical Nursing Practice.” Descriptive methods, univariate linear regression, and multiple linear regression were used for data analysis. The results of the multiple regression analysis revealed that being female, having a higher academic grade point average, having willingly chosen the nursing profession, feeling comfortable in clinical practicum, having the ability to transfer theoretical knowledge into practice, and making sufficient effort to learn in clinical practicum were factors associated with nursing students' self‐regulated learning; these factors explained 45.1% of the variance. The study suggests that positive learning clinical environments can support students in the use of self‐regulated learning approaches.
Clinical characteristics and outcome in 15 dogs treated with transsphenoidal hypophysectomy for nonfunctional sellar masses
Authors: Hyde Brittany R. , Martin Linda G. , Chen Annie V. , Guess Sarah C. , Carrera‐Justiz Sheila , Bruyette David , Owen Tina J.
Published: November 2022

Objective

To characterize the clinical features, neurological examination findings, diagnostic imaging results, histopathological findings, and outcome following transsphenoidal hypophysectomy (TSH) in dogs with nonfunctional sellar masses (NFSM).

Study design

Multi‐institutional retrospective study.

Methods

Medical records of dogs that underwent TSH for a NFSM were reviewed for clinical signs, physical and neurological examination findings, diagnostic imaging results, endocrine testing, surgery reports, and outcome. Magnetic resonance (MR) imaging was rereviewed, and tumors were classified using the previously described system according to pituitary tumor extension and vascular involvement. Owners of dogs that survived to discharge were contacted.

Results

The majority of dogs presented for mentation change (12/15). The mean pituitary to brain ratio (P/B ratio) was 1.05 (0.6–1.4). Eight dogs had a tumor imaging classification of 5B. Eleven dogs were diagnosed with a nonfunctional pituitary adenoma (NFPA). Perioperative mortality was 33% (5/15). The median survival for all dogs was 232 days (0–1658). When dogs that did not survive to discharge were excluded, the median survival time was 708 days. Seven of 10 dogs that survived the perioperative period received adjunctive therapy. Owner assessment of outcome was excellent (6/7) to good (1/7).

Conclusion

The common presenting complaint for dogs with large NFSM causing mass effect was mentation changes. Dogs with NFPA that survived to discharge and received adjunctive therapy had good to excellent outcomes.

Clinical significance

Transsphenoidal debulking with adjunctive therapy can be considered for the treatment of NFSM causing clinical signs of mass effect in dogs. Successful long‐term outcomes are possible.
Development of a Lead-Free Bronze Bearing Alloy With Improved Conformability and Seizure Performance
Authors: Harvey Jennifer , Stearns John , Merchant Jack
Published: November 2022

Material selection for off-highway heavy duty engine bearing applications is becoming more complex as there is a growing requirement to replace the traditionally utilized copper-lead based lining alloys due to adverse health and environmental concerns surrounding heavy metals. Although upcoming legislation is increasing the drive to find alternative lead-free solutions these have not been well adopted for all applications as there are limited products available that are matched to the excellent performance of leaded materials in tolerance to debris, ability to conform and prevention of seizure events.

This paper details the development of a new lead-free bronze alloy with a focus on improvements in conformability and seizure resistance compared to current lead-free materials. A new alloy composition is introduced which contains bismuth soft phase with optimized tin content which when combined with a lead-free electroplated overlay presents a robust material for applications where seizure performance might be a concern.

The present development provides a suitable product that will enable the future-proofing of off-highway heavy duty applications and offers a solution to inevitable future restrictions surrounding leaded materials. Results from bespoke rig testing and engine testing are detailed that support the material development.
Investigation of Flow and Flame Propagation in a Spark Ignition Direct Injection Engine Using Particle Image Velocimetry
Authors: Shen Li , Willman Christopher , Stone Richard
Published: November 2022

Variations in the in-cylinder flow before and during combustion influence the propagation of the flame in spark ignition direct injection (SIDI) engines, which leads to variations in combustion between engine cycles. Accommodating such cycle-to-cycle variation in production engines requires design compromises that may reduce efficiency. The in-cylinder flow and flame evolve rapidly during combustion, and due to the existence of cyclic variation, the flame propagation in individual cycles cannot be replicated by taking measurements at different timings over different cycles, hence crank-angle-resolved measurements in the same cycle are needed. However, such high-speed flow and flame measurements usually require combining multiple laser-based diagnostic techniques, which can be costly due to the need for multiple lasers with high repetition rates at different wavelengths. In this work, the crank-angle-resolved flow velocity and the flame propagation on a swirl plane in an optically accessible SIDI engine were simultaneously measured by a single laser-based diagnostic technique — high-speed planar particle image velocimetry (PIV). In-plane flame boundaries were inferred from the absence of PIV seeding oil droplets in the burned gas regions. Line-of-sight flame images from two orthogonal views were recorded synchronously with the PIV data in order to validate the in-plane flame boundaries derived from the PIV data. The impact of the neighbouring flow on the evolution of the flame boundaries over crank angles is examined.
Injection Strategies for POMDME- and Diesel-Natural Gas Dual Fuel Engines
Authors: Hariharan Deivanayagam , Krishnan Sundar Rajan , Srinivasan Kalyan Kumar
Published: November 2022

Conventional dual-fuel combustion (DFC) has been studied for decades due to its ability to produce high fuel conversion efficiency and its potential to defeat the well-known diesel NOx-PM trade-off. In DFC, a low-reactivity fuel (LRF) such as natural gas is premixed with air and ignited with the help of a high-reactivity fuel (HRF) such as diesel. In DFC, along with its low PM emissions, NOx emissions are reduced significantly by advancing the start of injection (SOI) to earlier than 320 CAD (40 degrees before TDC). However, earlier SOIs result in combustion instability, due to overleaning of HRF. It is more evident for a case with a high percentage energy substitution (PES) of LRF, due to the limited injected quantity of HRF. Research has shown that combustion instabilities can be improved by split injection (more than one injection), especially when they are close-coupled. In this study, the typical diesel PM-NOx tradeoff was nullified with an oxygenated, high cetane fuel, polyoxymethylene dimethyl ether (POMDME) as HRF. POMDME-natural gas DFC produced zero measurable soot emissions at all investigated conditions. However, since the lower heating value of POMDME is nearly half that of diesel, it needs longer injection durations (greater mass injected) for the same energy input. Therefore, it is important to understand the effect of end of injection (EOI) of POMDME compared to diesel for the same SOI on performance and emissions In addition, the impact of split injection strategies on performance and emissions are explored, especially at the heat release rate shape transformation region (i.e.) between SOI 320 and 330 CAD.
Phenomenological Model Development of Flash Boiling Spray for Multi-Hole Gasoline Direct Injection (GDI) Systems
Authors: Ailaboina Akhil , Saha Kaushik
Published: November 2022

Flash boiling occurs when a superheated liquid fuel is injected into a sub-atmospheric pressure environment. This phenomenon is often seen in a gasoline direct injection (GDI) engine under part-load conditions. The injector tip is exposed to the combustion environment, increasing the fuel temperature inside the injector up to 80–90° C. Under these flash boiling conditions, the injected liquid fuel will undergo rapid vaporization, affecting the spray structure. The flash boiling spray helps achieve better atomization of the fuel spray. However, in some conditions, due to flashing, a dense vapor cloud will form in the in-cylinder and disturb the air-fuel mixture, and lead to unwanted pollutants. Several numerical models have been developed for the flash boiling sprays. However, most of these models are hard to implement in a multi-cycle GDI engine combustion simulation. The existing flashing-based evaporation models in the CONVERGE code are not dimensionally consistent. In that regard, a phenomenological model of flash boiling spray is developed using the relevant non-dimensional numbers to help GDI engine combustion modeling under such conditions and address the issue of dimensional inconsistency in the source term formulations.

A multi-hole GDI injector from the engine combustion network (ECN) called Spray G is considered for this work. The model is developed using the CONVERGE v2.4 user-defined functions (UDFs). The blob injection method is considered for this work, and the simulations are carried out using the Eulerian-Lagrangian framework. An Unsteady Reynolds Averaged Navier-Stokes (URANS) RNG k-ε turbulence model is considered in this study. The KH-RT breakup length model is adopted for modeling spray breakup. The developed model has achieved a reasonable agreement with the experimental spray images. Comparisons of the predictions are made with the data available through ECN, such as spray penetrations and spray patternations.
Reinforcement Learning Based Control of an Organic Rankine Cycle Waste Heat Recovery System Over a Drive Cycle for Heavy-Duty Diesel Engines
Authors: Egan Daniel , Xu Bin , Zhu Qilun , Prucka Robert
Published: November 2022

Organic Rankine cycle (ORC) waste heat recovery (WHR) systems are of interest in the automotive sector because of their ability to convert exhaust heat into usable energy, increasing system-level brake thermal efficiency. Interest is particularly strong in the heavy-duty market as these vehicles have large footprints and heat outputs that can accommodate ORC-WHR systems. ORC-WHR systems are in the early stages of development and as a result the effectiveness of ORC-based systems throughout transient drive cycles can be difficult to quantify. One of the primary barriers preventing insight into transient performance is the lack of control maturity that exists prior to hardware implementation. Early development of control strategies allows for insights to be integrated into design earlier in the process, potentially streamlining the development cycle. ORC control development is hindered by the physical complexity of the boiler and the modeling of associated dynamics. Creating a model that captures the warm-up, power-generation, and cool-down operating regimes requires the use of a finite volume-based model (FVM) which is computationally infeasible to use with optimal control techniques such as model predictive control or dynamic programming. If the model is switched to a control oriented moving boundary model (MBM) the ability to govern the warmup and cool-down operating regimes is eliminated. This research proposes the use of a model-free reinforcement learning (RL) algorithm to create a control strategy using a FVM system model. The model-free nature of RL allows it to be trained/calibrated on models of unlimited complexity with the resulting controller capable of real-time operation. This eliminates the need for model reduction during control strategy generation and allows for the controller to handle all operating regimes the system will encounter. This study utilizes a deep deterministic policy gradient (DDPG) RL agent trained on a FVM of an ORC-WHR system. The RL agent is trained over a heavy-duty drive cycle and is capable of extracting net positive work over a transient drive cycle.
Effect of the Virtual Mass Force Term on the Critical Flow
Authors: Xu Hong , Chen Jiayue , Ming Pingjian , Cheng Xu
Published: November 2022

Critical (choked) flow is a highly concerning phenomenon in safety analysis for nuclear energy. During an accident, the radioactive aerosol in nuclear power plant (NPP), which is hazardous for the environment, may be released accompanying the fluid discharge. Consequently, the discharge mass flow rate prediction is crucial for engineering design and emergency response in case of nuclear accidents. Unfortunately, the critical flow is difficult to predict especially when two-phase flow exists. Developing a more accurate model for critical flow is an essential requirement to the system thermal-hydraulic (STH) codes (e.g., RELAP5, TRACE, and ATHLET, etc.) for nuclear safety analysis. The accuracy is based on a deeper understanding of the complex phenomenon of critical flow. One of the difficulties concerned with the mathematical modeling of the two-phase critical flow is the complexity of the transfer phenomena at the interface. Normally, an interfacial drag law and a virtual mass force were used to quantify the momentum transfer between the phases in the STH codes. The present study is concerned with the effect of virtual mass force on phase separation during the acceleration of a two-phase mixture. Virtual mass represents real physical effects and it can be regarded as induced inertia on the dispersed phase which is accelerating relative to the continuous phase. It has been verified that the virtual mass acceleration is objective, and the consideration of it in the two-phase flow simulation can improve the numerical stability and efficiency. Therefore, a variety of objective forms of virtual mass acceleration were derived in the last fifty years. But the influence of virtual mass force on the two-phase critical flow was seldom concentrated on owing to the lack of suitable critical flow models for studies in detail. This study is based on a developed two-phase critical flow model based on the separate conservation equations of mass, momentum, and energy for each phase. Several typical models of virtual mass force are selected and their influences on the accuracy of critical flow predictions will be studied in some detail. Furthermore, the critical flow that happened in the NPP accident scenarios may go through several flow regimes such as subcooled flow, bubbly flow, slug flow, and annular flow, etc. The impact of virtual mass force on these different stages of critical flow is another topic of this study. The results of this study can benefit a further understanding of virtual mass force, especially its influence on critical flow, and will contribute to the development of a more accurate two-phase critical flow model.
Improvement of Large Container Inspection System in Photon- Counting Mode Proved With Steel Penetration Ability
Authors: Zhang Huaxia , Wu Zhifang , Dong Tao , Jiang Shibo
Published: November 2022

We present the structure and characteristics of a photon-counting system for increased Steel Penetration (SP) ability in large container inspection area. Ideally, radiation images should count only unreacted photons. Conventional detectors utilize analog current integration and thus suffer from scattered signals and electronic noise which can deteriorate image quality. However, with the increasing demand for container inspection, higher requirements have been placed on image quality, scan speed as well as radiation dose. Therefore, we propose a new photon-counting mode large container inspection system that counts individual signals, in which scattered signals and electronic noise can be eliminated by setting an energy threshold.

In this paper, we give a system overview and describe the key technologies in system design. Then the improvement of the presented system is analyzed theoretically from the aspect of physical interactions that take place in the system. Simulation of the Steel Penetration model is conducted in Geant4 software. Results show that the improvement of SP ability compared with the conventional current-integration system is about 3 to 4cm Fe even if we increase the scan speed or reduce the radiation intensity, and can be 1 to 2cm more by setting an appropriate energy threshold. Along with this property, the possibility of reducing radiation dose and increasing scan speed makes this system unique for future growth of container inspection missions.
Local Damage to Reinforced Concrete Panels Subjected to Oblique Impact by Projectiles: Numerical Analysis on Test Results
Authors: Kang Zuoyi , Okuda Yukihiko , Nishida Akemi , Tsubota Haruji , Li Yinsheng
Published: November 2022

This study aims at proposing a numerical analysis method to evaluate local damage to reinforced concrete (RC) panel caused by projectile impact. To validate the proposed numerical analysis method, we recently conducted a series of impact tests with normal and oblique impacts due to rigid and soft projectiles. We intend to compare the numerical results with experimental results including reaction forces, damage modes of RC panel and soft projectile in oblique impact. In the numerical analysis for evaluation of local damage to RC panel, there are several key parameters, such as material properties, contact conditions between concrete and projectile. In addition to these parameters, we also focused on the reaction forces of RC panel, which is important when investigating the impact effects on structure under projectile impact. Since the stiffness of support structure is represented as a spring element in finite element (FE) model, we examined the relationship between the spring stiffness and numerically computed reaction forces in oblique impact. The numerical analysis method for oblique impact is validated, and the local damage in the RC panel is evaluated, by comparing experimental and numerical results.
Investigation of Transport Models of Radionuclides in Various Water Environments
Authors: Qu Zhengzhe , Xie Feng , Nie Baojie , Wang Liang
Published: November 2022

Concerning the Fukushima nuclear accident, many radionuclides were released into the marine environment, which caused contamination of many parts of the world through ocean circulation. Regarding inland nuclear power plants, freshwater habitats such as reservoirs and rivers could also be polluted by the radioactive effluents. Several models were developed to track radionuclide transport in the water environment. However, the applicability and characteristics of these models were not fully identified and compared, particularly for the different water environments. In this study, the research progress and application examples of radionuclide transport models in rivers and oceans in recent years are systematically summarized, and the methods for simulating radionuclide transport behavior in various water environments are compared. An adequate model is expected to be instrumental in assessing radioactive pollution in various water environments.
Dynamic Modeling of Nuclear Hydrogen Generation Plant Based on Multi-Modular High-Temperature Gas-Cooled Reactor
Authors: Li Junyi , Dong Zhe , Li Bowen , Huang Xiaojin
Published: November 2022

There has been growing interest in nuclear hydrogen cogeneration recently since hydrogen has been considered one of the prospective substitutes to fossil fuels in the future, and nuclear energy can supply the energy required for hydrogen production efficiently and cleanly. The multi-modular high-temperature gas-cooled reactor (MHTGR) is a small modular reactor with the advantage of inherent safety, and its nuclear steam supply system (NSSS) can provide steam at around 570°C. Methane Steam Reforming (MSR) is currently the most widely used hydrogen production method, and if it is combined with a carbon capture and storage system, the greenhouse gas emissions can be minimized. This paper presents the design for a nuclear hydrogen cogeneration plant that has six-module MHTGRs coupled with MSR.