bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transport Phenomena and Evolution Mechanism of the Melt Pool During a Laser-Based Metal Melting Process
Authors: Bian Qingfei , Tian Ke , Ling Kong , Chen Yitung , Zeng Min , Wang Qiuwang 
Published: December 2021

Abstract
This article presents a fully three-dimensional numerical study on the process of melt pool evolution. To overcome the simplifications used in many existing studies, an enthalpy method is developed for the phase change, and an accurate interface capturing method, i.e., the coupled volume-of-fluid and level set (VOSET) method, is employed to track the moving gas–liquid interface. Meanwhile, corresponding experimental studies are carried out for validation. The obtained numerical results show the formed interface morphology during the process of melt pool with its typical sizes and are quantitatively consistent with those data measured in experiments. Based on the numerical results, the thermodynamic phenomena, induced by the interaction between heat and momentum exchange, occurring in the formation of melt pool are presented and discussed. Mechanisms of the melt pool evolution revealed in the present study provide a useful guidance for better controlling the process of additive manufacturing.
Experimental Investigation on Finned Solar Still With Enhanced Thermal Energy Storage
Authors: Sathish Kumar Thangavel Ramalingam , Jegadheeswaran Selvaraj 
Published: December 2021

Abstract
In the present study, a novel solar still incorporated with fins and phase change material (PCM)-based energy storage was designed. To investigate the influence of fins and energy storage unit, four cases of stills were considered. In case I, a conventional type was considered, whereas square hollow fins were fitted over the basin liner of the still in case II. In addition to fins as in case II, case III employs an energy storage unit wherein PCM was packed beneath the basin liner. Case IV was similar to case III except for the extension of fins into the storage unit. The addition of fins above the basin liner improved the absorber surface area and the extension of the same beneath the basin liner enhanced the storage efficiency. Experiments were carried out on all the four modules with a constant basin water depth of 2 cm. The maximum productivity of the conventional solar still was found to be 3.25 L/m2/day. On the other hand, the results reveal improvement in productivity of 17.54%, 48.61%, and 55.69% with cases II, III, and IV, respectively. Although stills with energy storage units exhibited higher exergy efficiency, the presence of fins in the PCM increases the internal irreversibilities. The cost of water yielded by modified solar still (MSS) used in case IV is proved to be less as compared to conventional solar still (CSS). Further, the payback period of MSS is found to be lesser than that of CSS.
A New Loss Generation Body Force Model for Fan/Compressor Blade Rows: Application to Uniform and Non-Uniform Inflow in Rotor 67
Authors: Pazireh Syamak , Defoe Jeffrey 
Published: December 2021

Abstract
Despite advances in computational power, the cost of time-accurate flows in axial compressor and fan stages with spatially non-uniform inflow is still too high for design-stage use in industry. Body force modeling reduces the computation time to practical levels, mainly by reducing the problem to a steady one. These computations are important to determine efficiency penalties associated with non-uniform inflows. Previous studies of body force methods have, in most cases, relied on computations with the presence of the blades to calibrate loss models. In some recent studies, uncalibrated models have been used, but such models can drop off in accuracy at conditions where separation would occur on the blade surfaces. In this paper, a neural-network-based loss model introduced in a recent paper by the authors is implemented for NASA rotor 67 for both uniform and non-uniform inflow conditions. For uniform inflow, the spanwise trend of entropy variation is generally captured with the new body force model. Although there are discrepancies at some span fractions, the present model generally predicts the compressor’s isentropic efficiency to within 3% compared to bladed Reynolds-averaged Navier–Stokes simulations. For non-uniform inflow, we consider a stagnation pressure profile representative of boundary layer ingestion. The results show that the region of maximum entropy generation is captured by the present model and the prediction of isentropic efficiency penalty due to the non-uniform inflow is only 0.2 points less than that determined from bladed computations.
Cooling Performance of Additively Manufactured Pin Fins in Stacked Microchannels for the Inside-Out Ceramic Turbine Shroud-Cooling Ring
Authors: Dubois Patrick K. , Landry-Blais Alexandre , Gazzah Rym , Sivić Sani , Brailovski Vladimir , Picard Mathieu 
Published: December 2021

Abstract
The inside-out ceramic turbine (ICT), a novel microturbine rotor architecture, has an air-cooled ring, which keeps its composite rotating structural shroud within operating temperature. The cooling ring must achieve a significant radial temperature gradient with a minimal amount of cooling. The cooling ring is made through additive manufacturing, which opens the design space to tailored cooling geometries. Additively manufactured pin fin heat transfer enhancers are explored in this study to assess whether they hold any significant performance benefit over current rectangular cross section open channels. Experimental friction factors and Nusselt numbers were determined for small, densely-packed pin fins over an asymmetrical thermal load. Results indicate that pressure loss is similar to what can be expected for additively manufactured pin fins, whereas heat transfer is lower due to the extremely tight streamwise pin spacing, in both in-line and staggered pin configurations. A design study presented in this article suggests that pin fins are beneficial to an ICT for reducing cooling mass flowrate up to 40%, against an increase in cooling ring mass of roughly 50%.
The Influence of Purge Flow Parameters on Heat Transfer and Film Cooling in Turbine Center Frames
Authors: Jagerhofer Patrick R. , Patinios Marios , Glasenapp Tobias , Göttlich Emil , Farisco Federica 
Published: December 2021

Abstract
The imperative improvement in the efficiency of turbofan engines is commonly facilitated by increasing the turbine inlet temperature (TIT). This development has reached a point where also components downstream of the high-pressure turbine (HPT) have to be adequately cooled. Such a component is the turbine center frame (TCF), known for a complex aerodynamic flow highly influenced by purge-mainstream interactions. The purge air, being injected through the wheelspace cavities of the upstream high-pressure turbine, bears a significant cooling potential for the TCF. Despite this, fundamental knowledge of the influencing parameters on heat transfer and film cooling in the TCF is still missing. This paper examines the influence of purge-to-mainstream blowing ratio, density ratio (DR), and purge swirl angle on heat transfer and film cooling in the TCF. The experiments are conducted in a sector-cascade test rig specifically designed for such heat transfer studies using infrared thermography and tailor-made flexible heating foils with constant heat flux. Three purge-to-mainstream blowing ratios and an additional no purge case are investigated. The purge flow is injected without swirl and also with engine-similar swirl angles. The purge swirl and blowing ratio significantly impact the magnitude and the spread of film cooling in the TCF. Increasing blowing ratios lead to an intensification of heat transfer. By cooling the purge flow, a moderate variation in purge-to-mainstream density ratio is investigated, and the influence is found to be negligible.
Film Cooling Effectiveness Measurement of Fan-Shaped Holes Manufactured Using Electrical Discharge Machining Technique
Authors: Rouina S. , Abdeh H. , Barigozzi G. , Odemondo V. , Abba L. , Iannone M. 
Published: December 2021

Abstract
In this study, the influence of geometric factors such as hole diameter (D), length-to-diameter ratio (L/D), injection angle (α), and lateral expansion angle (β) on film cooling effectiveness of holes made using electrical discharge machining (EDM) is experimentally investigated. Nine different cooling configurations were tested on a flat plate wind tunnel at various coolant Reynolds number (Rec) and coolant-to-mainstream blowing ratio (M). The considered flat plate model incorporates engine-sized V-shaped holes. EDM reliability is assessed through a hole qualification process, while effectiveness was measured by the pressure-sensitive paint (PSP) technique. Results confirm the suitability of EDM for V-shaped hole manufacturing as long as a correct tolerance on β is prescribed. An accurate qualification of hole morphology is also recommended.
Facile Synthesis and Characterization of the Mn-MOF Electrode Material for Flexible Supercapacitors
Authors: Liu Yanhong , Liu Jiahong , Cao Yijun , Shang Wei , Peng Ning , Long Xianhao , Zhou Shengjun , Wen Yuqing 
Published: December 2021

Abstract
Metal-organic frameworks (MOFs) due to their porosity and well-defined structures are considered to be very promising electrode materials for the construction of high-performance supercapacitor (SC). In this paper, manganese-based metal-organic framework (Mn-MOF) were prepared on the surface of carbon cloth (CC) by a facile hydrothermal method. The morphology and structure of the electrode material were characterized by scanning electron microscopy (SEM), X-ray diffractometer (XRD), Fourier-transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). Its electrochemical studies show that the Mn-MOF electrode materials exhibit lower charge transfer resistance, the excellent specific capacitance of 433.5 mF/cm2 in 1.0 M Na2SO4 aqueous solution at the current density of 0.8 mA/cm2. It is noteworthy that the flexible electrode have excellent cycle stability and 105% capacitance retention even after 5000 cycles at a current density of 5 mA/cm2. The excellent electrochemical performance of Mn-MOF/CC flexible electrode materials can be attributed to its three-dimensional porous structure.
Power Enhancement of Wave Energy Converter Array via Wave Runup in Channel
Authors: Tay Zhi Yung 
Published: December 2021

Abstract
When waves pass through a channel, wave elevation is observed to increase, a phenomenon known as wave runup. Attempts are made to utilize the wave runup along a channel supported on a floating platform to enhance the energy generation from the array of point absorber wave energy converters (PA-WECs). Such floating platforms could be integrated into the floating breakwater, floating pier, or other floating platforms utilized as floating cities for efficient ocean space utilization. The channel is created by modeling two vertical walls supported on a floating platform with wave energy converters deployed in the channel. The performance of the wave farm in terms of energy generation (i.e., power) and interaction factor (i.e., q-factor) are assessed. The paper investigates the effect of channel widths and depths on the power absorption of the arrays. A three-stepped floating platform with varying depths along the channel is then studied to obtain optimal depths along the channel where the highest energy is harvested. Thereafter, three arrays of WECs deployed in a larger three-stepped channel (TSC) floating platform are considered and the effectiveness of such configuration in harvesting energy is assessed. The wave elevation surrounding the wave farm is presented to show the effect the wave runup has on energy generation. The results show that the energy generation of wave energy converters when the arrays are placed in three-stepped channel floating platform could be increased significantly. A q-factor above 1.0 could be achieved for wave period greater than 6 s and the array can generate greater energy for omnidirectional waves.
Assessment of Influence of Urban Aerosol Vertical Profile on Clear-Sky Diffuse Radiance Pattern
Authors: Petržala Jaromír 
Published: December 2021

Abstract
Aerosol particles spread in the atmosphere play an important role in solar light scattering and thus co-determine the sky radiance/luminance pattern as well as diffuse irradiances/illuminances at the ground. The particular influence is given by their optical properties and by their distribution in the atmosphere. The dependence of the aerosol extinction coefficient on altitude is usually described by the exponential law, which results from the averaging of a large number of aerosol realizations. This is also frequently the case of simulating of the solar diffuse radiance/luminance distribution over the sky, when it is based on solving the radiative transfer problem. However, the aerosol vertical profile can sometimes be significantly different from the exponential one. Mainly in the urban environment, the aerosol is often well-mixed within the atmospheric boundary layer, so its volume extinction coefficient is almost constant there. Under specific conditions also the so-called elevated aerosol layer may occur. This work investigates how such different profiles affect the clear sky radiance pattern and consequently also the ground-based horizontal diffuse irradiance. The numerical simulations revealed that the discrepancies are negligible in practice. So, it appears that the aerosol vertical distribution does not play any important role in sky radiance calculations, and the standard exponential law is general enough to cover also various specific aerosol conditions.
Association of Logic’s hip hop song “1-800-273-8255” with Lifeline calls and suicides in the United States: interrupted time series analysis
Authors: Niederkrotenthaler Thomas , Tran Ulrich S , Gould Madelyn , Sinyor Mark , Sumner Steven , Strauss Markus J , Voracek Martin , Till Benedikt , Murphy Sean , Gonzalez Frances , Spittal Matthew J , Draper John 
Published: December 2021

AbstractObjectiveTo assess changes in daily call volumes to the US National Suicide Prevention Lifeline and in suicides during periods of wide scale public attention to the song “1-800-273-8255” by American hip hop artist Logic.DesignTime series analysis.SettingUnited States, 1 January 2010 to 31 December 2018.ParticipantsTotal US population. Lifeline calls and suicide data were obtained from Lifeline and the Centers for Disease Control and Prevention.Main outcome measuresDaily Lifeline calls and suicide data before and after the release of the song. Twitter posts were used to estimate the amount and duration of attention the song received. Seasonal autoregressive integrated moving average time series models were fitted to the pre-release period to estimate Lifeline calls and suicides. Models were fitted to the full time series with dummy variables for periods of strong attention to the song.ResultsIn the 34 day period after the three events with the strongest public attention (the song’s release, the MTV Video Music Awards 2017, and Grammy Awards 2018), Lifeline received an excess of 9915 calls (95% confidence interval 6594 to 13 236), an increase of 6.9% (95% confidence interval 4.6% to 9.2%, P<0.001) over the expected number. A corresponding model for suicides indicated a reduction over the same period of 245 suicides (95% confidence interval 36 to 453) or 5.5% (95% confidence interval 0.8% to 10.1%, P=0.02) below the expected number of suicides.ConclusionsLogic’s song “1-800-273-8255” was associated with a large increase in calls to Lifeline. A reduction in suicides was observed in the periods with the most social media discourse about the song.
Prevalence of Long COVID symptoms in Bangladesh: a prospective Inception Cohort Study of COVID-19 survivors
Authors: Hossain Mohammad Anwar , Hossain K M Amran , Saunders Karen , Uddin Zakir , Walton Lori Maria , Raigangar Veena , Sakel Mohamed , Shafin Rubayet , Hossain Mohammad Sohrab , Kabir Md Feroz , Faruqui Rafey , Rana Md Shohag , Ahmed Md Shahoriar , Chakrovorty Sonjit Kumar , Hossain Md Anwar , Jahid Iqbal Kabir 
Published: December 2021

BackgroundThe objective of this study was to identify the prevalence of long COVID symptoms in a large cohort of people living with and affected by long COVID and identify any potential associated risk factors.MethodsA prospective survey was undertaken of an inception cohort of confirmed people living with and affected by long COVID (aged 18–87 years). 14392 participants were recruited from 24 testing facilities across Bangladesh between June and November 2020. All participants had a previously confirmed positive COVID-19 diagnosis, and reported persistent symptoms and difficulties in performing daily activities. Participants who consented were contacted by face-to-face interview, and were interviewed regarding long COVID, and restriction of activities of daily living using post COVID-19 functional status scale. Cardiorespiratory parameters measured at rest (heart rate, systolic blood pressure, diastolic blood pressure, oxygen saturation levels, maximal oxygen consumption, inspiratory and expiratory lung volume) were also measured.ResultsAmong 2198 participants, the prevalence of long COVID symptoms at 12 weeks was 16.1%. Overall, eight long COVID symptoms were identified and in descending order of prominence are: fatigue, pain, dyspnoea, cough, anosmia, appetite loss, headache and chest pain. People living with and affected by long COVID experienced between 1 and 8 long COVID symptoms with an overall duration period of 21.8±5.2 weeks. Structural equation modelling predicted the length of long COVID to be related to younger age, female gender, rural residence, prior functional limitation and smoking.ConclusionIn this cohort, at 31 weeks post diagnosis, the prevalence of long COVID symptoms was 16.1%. The risk factors identified for presence and longer length of long COVID symptoms warrant further research and consideration to support public health initiatives.
Effect of RUSI-based core stability exercise on chronic non-specific low back pain patients: study protocol for a randomised controlled trial
Authors: Lin Shanshan , Zhu Bo , Zheng Yiyi , Liu Shufeng , Wang Chuhuai 
Published: December 2021

IntroductionLow back pain (LBP) is one of the most highly prevalent pain both in developed countries and low-income and middle-income countries. Despite increasing healthcare resources and numerous treatment methods for LBP, the efficacy of these therapeutic strategies is still uncertain. Recently, core stability exercise (CSE) is popularly applied as a preventive or rehabilitative method in the treatment of LBP. However, the adequate activation of the local muscle systems of CSE needs further optimisation and quantification. This trial aims to investigate the feasibility and efficacy of CSE monitored by real-time ultrasound image (RUSI) on LBP individuals.Methods and analysisForty subjects with chronic non-specific LBP (CNLBP), aged from 20 to 50 years, will be randomly allocated into two groups using sealed, consecutively numbered opaque envelopes: (1) study group (SG): CSE monitored by RUSI and (2) control group (CG): identical CSE without monitoring. Interventions will last 30 mins, two times a week for 8 weeks. The primary outcomes include pain intensity, disability and quality of life, and the secondary outcomes will be the postural control static stability, onset timing of trunk muscles activation, ultrasound images of muscle thickness and surface electromyography (sEMG) signal of muscle activities. Outcome measures will be collected at baseline, 4 and 8 weeks during training, and at 6 months follow-up. Data will be collected and analysed by an assessor blinded to group allocation. Effect sizes and mixed-model repeated measures analysis of variance (2 groups×4 time points) will be calculated.Ethics and disseminationThis protocol and informed consent has been approved by the Institutional Research Ethics Committee of the First Affiliated Hospital, Sun Yat-sen University (Approval number: [2020] 254-1). The findings of this study will be disseminated to participants through social networks and will be submitted to peer-reviewed journals and scientific conferences.Trial registration numberChinese Clinical Trial Registry (ChiCTR2000034498).
Optimising prescribing practices in older adults with multimorbidity: a scoping review of guidelines
Authors: Lun Penny , Law Felicia , Ho Esther , Tan Keng Teng , Ang Wendy , Munro Yasmin , Ding Yew Yoong 
Published: December 2021

ObjectiveInappropriate polypharmacy occurs when multiple medications are prescribed without clear indications or where harms outweigh their benefits. The aims of this scoping review are to (1) identify prescribing guidelines that are available for older adults with multimorbidity and (2) to identify cross-cutting themes used in these guidelines.DesignScoping review.Data sourcesPubMed, Embase, Web of Science, the Cochrane Library databases, Cumulative Index to Nursing and Allied Health Literature, grey literature sources, six key geriatrics journals, and reference lists of identified review papers. The search was conducted in November 2018 and updated in September 2019.Study selectionGeneral prescribing guidelines tailored to or for adults including older adults with multimorbidity.Data extractionData for publication description, guideline characteristics, information for users and criteria were extracted. The synthesis contains summarised qualitative descriptions of the studies and guideline characteristics as well as identified cross-cutting themes.ResultsOur search strategy yielded 10 427 unique citations, of which 70 fulfilled the inclusion criteria for synthesis. Among these, there were 61 unique guidelines and tools which used implicit, explicit, mixed or other approaches in the prescriber decision-making process. There are 11 cross-cutting themes identified in the guidelines. Prescriber-related themes are: conduct a comprehensive assessment before prescribing, identify patients’ needs, goals and priorities, adopt shared decision-making, consider evidence-based recommendations, use clinical prescribing tools, incorporate multidisciplinary inputs and embrace technology-enabled prescribing. Wider organisation-related and system-related themes related to education, training and the work environment are also identified.ConclusionsFrom guidelines and tools identified, eleven cross-cutting themes provide a usable knowledge base when seeking to optimise prescribing among older adults with multimorbidity. Incorporating these themes in an approach that uses mixed criteria and implementation information could facilitate greater uptake of published prescribing recommendations.