bluuebunny/crossref_metadata_2025 huggingface dataset:
Establishment of control points using GNSS- RTK technique
Authors: Na’aim Mohd Zahirudin Bin Mohammed , Manaf Marlina Binti Abdul
Published: January 2024

Nowadays, Global Navigation Satellite Systems (GNSS) methods are broadly utilized to determine positions of points. This study was conducted with the aim of determining the positioning of control points at Politeknik Kuching Sarawak Campus using GNSS-RTK Technique. For this purpose, twenty-four control points were established with an average baseline length between Base station and Rover less than 1 km were occupied with Topcon HiPer VR receivers for different time periods. In this study there are situation of positioning under satellite obstruction such as the control points situated in the near buildings. Multipath is a common challenge in GNSS-RTK especially in complex environments. The final result from the Horizontal and Height differences were determined and compared with those measured by both static and RTK surveys. The result of the study shows that GNSS-RTK positioning method ensure high accuracy GNSS position solution within few centimetres.
Assessment of rainwater harvesting potential based on field observations in Jagakarsa District area, South Jakarta
Authors: Suprapti Suprapti , Kusuma Muhammad Syahril Badri , Cahyono Muhammad , Kardhana Hadi
Published: January 2024

Jagakarsa is one of the districts in South Jakarta that has a rainwater catchment area. Problems arise as a result of the high rate of population growth, which has an impact on changes in land use and increased surface runoff, causing flooding. On the other hand, the absence of clean water provision facilities from the government means that people use groundwater-drilled wells to meet their daily clean water needs. Sustainable groundwater consumption has an impact on land subsidence and vulnerability to groundwater availability. Therefore, it is necessary to carry out research. This research seeks to assess the potential for rainwater harvesting based on field observations. The research was carried out by analyzing rainfall data, field surveys, research program socialization, and community socio-economic analysis. Rainfall is high, with an annual average of 2809.7 m. 98% of respondents use drilled groundwater wells with a wells depth in the deep aquifer layer, and public interest in rainwater harvesting (RWH) technology is high. These show the potential for implementing RWH in the study location. This research is an initial study; for the integrated implementation of RWH, further research is needed after this study.
Feasibility and performance analysis of utilizing spent mushroom substrate as biomass fuel
Authors: Liao Chen-hao , Hsieh Jui-Ching
Published: January 2024

A novel biomass system has been developed that utilizes spent mushroom substrates (SMS) and combines a pre-drying and drying system. The novel biomass system consists of a boiler and an Organic Rankine Cycle (ORC), which employs Isohexane as the working fluid to enable operation at high temperatures. The high moisture content of the SMS is dried by pre-drying from condensation waste heat of ORC and drying from the flue gas of the boiler to improve the calorific value of SMS. In the present study, the moisture content of the SMS and evaporation temperature of the ORC ranged from 50% to 65% and from 130℃ to 180℃. The results show although the thermal efficiency of ORC increased with an increase in evaporation temperature, the maximal output power is 412.21 kW at an evaporation temperature of 150 ℃. Additionally, when the moisture content of the SMS is 50 %, the thermal efficiency of the entire system approaches the maximal value (58.6%).
Influence of thermal aging on dielectric characteristics of transformer insulating oils
Authors: Saodah Siti , Eliana Bella , Jakariya
Published: January 2024

Transformer oil is a liquid insulating material used in transformers as insulation and coolant. Particular characteristics insulating oil materials must be able to withstand breakdown voltages, while transformer oil as a coolant must be able to minimize heat generated, so that transformer oil is expected to protect the transformer from disturbances with these two characteristics. In order to reduce the percentage of transformer failures, it is necessary to maintain the purity of the oil. The features of aged transformer oil and pure transformer oil are investigated in this study. Pure transformer oil is heated to a particular temperature and cycled to create samples of aged transformer oil. The electric field intensity of transformer oil is measured to estimate the dielectric strength of aged transformer oil. FEM analysis is used to determine the intensity of an electric field. At aging temperatures of 130°C and 150°C, the dielectric characteristics of transformer oil for both Shell Diala and Triapar types are investigated. As a result, not only the electrical characteristics but also the effects of thermal aging on the physical and chemical properties of transformer oil are reported in this study.
Designing and constructing of a laboratory scale concrete roof tile dryer
Authors: Ramdani Fadli , Haryadi
Published: January 2024

There are some problems with the drying process in the concrete tiles local industry, especially due to uncertain weather, where the drying process relies on sunlight. In addition, roof tile dryers have not yet hit the market. A laboratory-scale dryer is needed to develop a full-scale concrete roof tile dryer. This research aims to design and manufacture a laboratory-scale concrete tile dryer. The dryer will be used to investigate the characteristics of the concrete roof drying. The design was carried out using the Pahl and Beitz method, in three stages, namely planning, conceptual design, and detailed design. In the planning stage, a requirement list was stated, in the conceptual design stage, selected tools are determined for every sub-function, while in the detail design stage, shop drawings were produced. To produce a better distribution of air velocity and temperature, at this detailed design stage, a Solidworks CFD numerical analysis was used. The dimension of the drier is 1600 x 1100 x 1100 mm³, with a capacity of 60 - 180 kg, with air velocity of 3 m/s and variable temperature. The drying chamber consists of 3 layers. The heat source is LPG flame and electric heater. The fresh air is flown to the LPG burner, through a circulating fan into the drying chamber, where the concrete roof tiles are situated. The roof tile dryer was constructed and tested. The test results show that the air velocity at the top layer accorded with the CFD result, while in the second layer and third layer of the drying chamber, the air velocity was relatively small. The temperature in each layer of the drying chamber shows the same value, in this case, the temperature for each layer is 38°C, while the set point at the thermostat was 40°C. The relative humidity of the drying air was 21.7% while the ambient air relative humidity was 52%.
Determinants of MSME financing in Islamic Banks in Indonesia for sustainable development
Authors: Setiawan Iwan , Tripuspitorini Fifi Afiyanti , Ruhana Nafisah
Published: January 2024

You should leave 8 mm of space above the abstract and 10 mm after the abstract. The heading Abstract should be typed in bold 9-point Arial. The body of the abstract should be typed in normal 9-point Times in a single paragraph, immediately following the heading. The text should be set to 1 line spacing. The abstract should be centred across the page, indented 17 mm from the left and right page margins and justified. It should not normally exceed 200 words.
Deep reinforcement learning in agricultural IoT-based: A review
Authors: Isa Indra Griha Tofik , Effendi Adhan , Suhartono
Published: January 2024

The world’s food needs have an impact on innovation in the field of agriculture, and one of them is by implementing deep reinforcement learning (DRL) technology, which is very relevant to the Industrial Revolution 4.0. This research discusses important issues and developments in DRLs that are implemented, especially in the field of IoT-based agriculture. The research method uses a Systematic Literature Review (SLR) approach through searching and analysing raw data sources, sorting and selecting relevant data relevant to the topics discussed, discussing topic areas and how trends are in current conditions, and concluding. The purpose of this study is to see how the current state of DRL implementation in agricultural IoT-based. The limitations of the study are that (1) the data sources come from Scopus-indexed journals; (2) the journal period is 2021–2023; (3) the research approach uses SLR; and (4) the focus of the discussion includes the implementation of DRL in agricultural IoT-based systems, the development of DRL technology, and the use of tools in DRL.
Location prediction using forward geocoding for fire incident
Authors: Irawan Faris Ade , Danoedoro Projo , Farda Nur Mohammad
Published: January 2024

Urban fires, although not a natural disaster, are a severe threat that often occurs in urban areas. Banjarmasin City, the capital of South Kalimantan Province and one of the most populous cities in Kalimantan, recorded 159 fire cases between 2020 and 2022, averaging nearly 53 cases yearly. In today’s digital era, people often share ongoing fire incidents using smartphones and update information on social media and online news. However, the resulting data could be more structured to serve as a dataset. This research addresses these issues by applying geocoding, a digital service that translates street addresses into geographic coordinates. This research uses three geocoders: Google Maps API, Bing Maps API, and Smart Monkey Geocoder. The accuracy of the three geocoders was tested using the Root Mean Square Error (RMSE) statistical method by comparing the geocoding results with valid locations. Prediction analysis was used to identify the next fire event through the density approach of the previous fire event points. This research is expected to provide insights into efficient data collection and structured data conversion, recommendations regarding the best geocoding service, and prediction of fire vulnerability locations based on recurring factors of fire incidents in the area. In conclusion, accurate data is the key to effective fire prediction.
Research of the optimal design of a jet pump for regulating a Pelton hydro turbine
Authors: Liamasov A.K. , Denisov K.E. , Biriulin M.A.
Published: January 2024

Hydroelectric power plants (HPP) contribute a significant share to electricity generation in Russia. Considering the prospects for the development of this sector and using the hydropower potential, it is necessary to explore methods for the modernization of hydroelectric power plants. This article explores a new method of regulating active turbines (Pelton) based on altering the nozzle flow rate by using a jet pump that operates with used fluid from the runner. The relevance of this solution lies in the potential to increase the operational lifespan of high-head pumped storage hydroelectric power plants (PSHPP) and enhance reliability by eliminating or reducing the intensity of the regulatory needle's operation in the guide vane mechanism. Based on the hydraulic scheme incorporating the jet pump into the hydroelectric power plants penstock upstream of the guide apparatus, several geometric configurations of the jet pump were evaluated using CFD modeling to assess the energy losses associated with the proposed regulation method.
Development of mathematical methods for processing tracer studies of wells
Authors: Tiutiaev Andrei , Kashaev Denis , Makarov Yuriy , Makarov Dmitriy , Dolzhikov Andrei
Published: January 2024

The use of tracer methods for studying oil wells makes it possible to determine the efficiency of oil field development. However, the reliability of the results of such studies largely depends on both the correctly selected indicators and the methods of interpretation. The currently developed theory of multiphase filtration and numerical analysis methods make it possible to use appropriate models to interpret the results of using various types of indicators. Of particular interest are mathematical models of processes occurring in oil-saturated rocks when using separable tracers.
Mercury behaviour features in soils and bottom sediments of technogenic landscapes water bodies in the Rostov region
Authors: Mikhailenko Anna , Fedorov Yuri , Kostenko Daria
Published: January 2024

Mercury is one of the priority pollutants entering the Rostov region`s water bodies from numerous natural and anthropogenic sources. Analysis of heavy metal extraction in the world indicates a reduction in its use in production. Based on expedition and laboratory studies, the mercury concentrations levels in soils and bottom sediments were determined. The bottom sediments of the region belong to the low and medium range of impact, areas of high pollution are formed within residential areas and in coal-mining areas. Hg concentrations do not exceed MPC in soils.
Environmental protection in the farming system
Authors: Muhamediyeva D.T. , Safarova L.U. , Mavlyanov M.T.
Published: January 2024

The urgency of the problem of environmental protection in the modern agricultural system emphasizes the urgency of not only ensuring food security, but also sustainable impacts on ecosystems. This article examines a set of measures in the field of agriculture aimed at preventing soil degradation and pollution, rational use of natural resources and restoration of natural resources. Particular attention is paid to topics such as protection of the humus status of soils, anti-erosion measures, a scientifically based soil cultivation system, a rational system of fertilizer application, integrated plant protection from pests and diseases, as well as water conservation measures and land reclamation. Crop rotation, as a fundamental element of modern agrolandscape farming systems, deserves special attention in the context of environmental protection. This article provides the scientific rationale for the role of crop rotation in promoting ecosystem resilience and preventing the negative environmental impacts of agricultural activities. The principles and advantages of crop rotations aimed at maintaining biological diversity, preserving the humus status of soils, and preventing erosion are considered. The article also highlights the impact of crop rotation on the energy balance, efficient use of resources, and reproduction of soil fertility. The importance of crop rotation is emphasized as a key factor in balanced and environmentally oriented agriculture, contributing to the creation of sustainable agroecosystems and ensuring long-term environmental sustainability.
Determination of the actual turbocharging characteristics of diesel engines using support vector machines (SVM)
Authors: Fedorenko V.F. , Ivanov A.B. , Eviev V.A. , Sazonov N.
Published: January 2024

The article proposes and justifies a method that allows solving the problem of determining the characteristics of turbocharging of diesel engines of agricultural tractors without the use of test benches. The proposed application of support vector machines (SVM) has a number of advantages over traditional methods for determining the characteristics of turbocharging of diesel engines under operating conditions of agricultural tractors and machines.
Novel Association of KLRC4-KLRK1 Gene Polymorphisms with
Susceptibility and Progression of Antithyroid Drug-Induced
Agranulocytosis
Authors: He Yayi , Ma Pan , Luo Yuanlin , Gong Xiaojuan , Gao Jiayang , Sun Yuxin , Chen Pu , Zhang Suliang , Tian Yuxin , Shi Bingyin , Zhang Bao
Published: January 2024

Objective Antithyroid drug (ATD)-induced agranulocytosis (TIA) is the most
serious adverse effect during ATD treatment of Graves’ disease (GD).
Previously, the MICA gene was reported to be associated with TIA.
MICA protein is an important ligand for the NKG2D protein, which is
encoded by the KLRK1 gene and KLRC4-KLRK1 read-through
transcription. This study further investigated the association between
KLRC4-KLRK1 gene polymorphisms and susceptibility to TIA.

Methods Twenty-eight candidate single nucleotide polymorphisms (SNPs) on
KLRC4-KLRK1 read-through transcription were evaluated by the iPLEX
MassARRAY system in 209 GD control patients and 38 TIA cases.

Results A significant association of rs2734565 polymorphism with TIA was
found (p=0.02, OR=1.80, 95%
CI=1.09–2.96). The haplotype C-A-A-C-G, including rs2734565-C,
was associated with a significantly higher risk of TIA (p=4.79E-09,
OR=8.361, 95% CI=3.737–18.707). In addition, the
interval time from hyperthyroidism to agranulocytosis onset was shorter in
patients carrying the rs2734565-C allele than in non-carrying groups (45.00
(14.00–6570.00) d vs. 1080.00 (30.00–3600.00) d,
p=0.046), and the interval from ATD treatment to
agranulocytosis onset was also shorter in patients carrying rs2734565-C allele
(29.00 (13.00–75.00) d vs. 57.50 (21.00–240.00) d,
p=0.023).

Conclusions The findings suggest that the KLRC4-KLRK1 gene
polymorphism is associated with susceptibility and progression of ATD-induced
agranulocytosis. Patients carrying the rs2734565-C allele had a higher
susceptibility and faster onset time of TIA.
Meanings and implications of love: review of the scholarship of love with a sub-Saharan focus
Authors: Steen Karin , Antoniou Alice , Lindemann Lehnke , Jerneck Anne
Published: January 2024

Love, as an emotion, binds people together in social practices that are contingent on culture, historical processes, and social trends. As such, love is a perfect site to study how people interact and to understand how power, equality, and sustainability play out in human relations. Despite its importance and much attention, love as a concept and form of interaction is not fully understood, especially not across cultures. In our research, mainly in sub-Saharan Africa, we show that alongside other emotions, love matters not only for passion in life or for wellbeing but also for improved resource use, increased gender equality, and, subsequently, higher food security and sovereignty – all signs of sustainability. While love is understood as a universal human phenomenon, definitions and expressions of love vary across time and cultures. Since love drives human interaction in many intertwined ways there is no single best way to define it. Yet, scholars have advanced the theory of love by identifying at least 40 major distinct but interdependent ‘love constructs’ fitting into the four main dimensions of affection, closeness, compassion, and commitment (Karandashev et al. 2022). In parallel to this and based on our review of the scholarship of love in a subset of 45 relevant academic articles from an 80-article systematic literature search of ‘love’ we find four core (and partly overlapping) types of how to speak about love as an expression and experience. These include: 1/ contextual love influenced by culture, space, and time; 2/ romantic and compassionate love; 3/ transactional love; 4/ post-humanist perspectives and ‘harmony love’. Finally, we examine love in relation to power; love-related emotions; and how understandings of love and culture impact gender relations.
How did African stock markets react to the Russia-Ukraine crisis “black-swan” event? Empirical insights from event study
Authors: Oyadeyi Olajide O. , Arogundade Sodiq , Biyase Mduduzi
Published: January 2024

This study builds on the recent literature by investigating how various types of African stock markets responded to the Russia-Ukraine crisis (commonly referred to as the black-swan event). The empirical analysis used in this paper centred on event study analysis, a statistical technique used to measure the impact of a specific event. The findings show that the black-swan event had a significant negative impact on African stock markets (14/20), with stocks having a negative abnormal return on the event day, and out of this, nine stocks’ abnormal returns are statistically significant. These include Safaricom Kenya, Commercial International Bank, Attijariwafa Bank, Morocco Casablanca Index, Egyptian Exchange 30, Nairobi All Share Index, AVI Equity, MCB Group Ltd, FTSE/JSE All Share, Delta Corp. Ltd, Stock Exchange of Mauritius, Tunisia Stock Exchange, Tanzania All Share Index, and Banque de Tunisie. Furthermore, the study discovers that African stock markets reacted heterogeneously to the impact of the crises, while some stocks were severely affected, some were minimally affected. The study concludes that African stock markets should build a resilient market capable of withstanding external shock and reducing the risk of contagion.
Dynamics of returns to vocational education in China: 2010–2017
Authors: Chen Jie , Pastore Francesco
Published: January 2024

In this paper, we use the Chinese General Social Survey data (2010–2017) to analyze the dynamics of returns to different education qualifications. We find increasing returns for all types of education, with returns to vocational and academic education increasing roughly at the same speed. We additionally compare the returns to vocational education with returns to academic education. Compared to those who only complete compulsory education, upper secondary graduates earn about 20% more, vocational college graduates earn 50%, and academic university graduates earn 75% more. At tertiary level, academic education pays better than vocational education, although the difference shrinks over the years. At upper secondary level, the evidence is indeterminate, depending on different econometric techniques (i.e., OLS, IV, Lewbel method, or PSM). These findings add to the limited quantitative evidence on returns to vocational education. The dynamics emerged from the findings echo the discussion on labor market mismatch and overeducation in China, which has important policy implications.
Looking towards an automated future: U.S. attitudes towards future artificial intelligence instantiations and their effect
Authors: Novozhilova Ekaterina , Mays Kate , Katz James E.
Published: January 2024

The present study explores people’s attitudes towards an assortment of occupations on high and low-likelihood of automation probability. An omnibus survey (N = 1150) was conducted to measure attitudes about various emerging technologies, as well as demographic and individual traits. The results showed that respondents were not very comfortable with AI’s management across domains. To some degree, levels of comfort corresponded with the likelihood of automation probability, though some domains diverged from this pattern. Demographic traits explained the most variance in comfort with AI revealing that men and those with higher perceived technology competence were more comfortable with AI management in every domain. With the exception of personal assistance, those with lower internal locus of control were more comfortable with AI managing in almost every domain. Age, education, and employment showed little influence on comfort levels. The present study demonstrates a more holistic approach of assessing attitudes toward AI management at work. By incorporating demographic and self-efficacy variables, our research revealed that AI systems are perceived differently compared to other recent technological innovations.
The impact of artificial intelligence on employment: the role of virtual agglomeration
Authors: Shen Yang , Zhang Xiuwu
Published: January 2024

Sustainable Development Goal 8 proposes the promotion of full and productive employment for all. Intelligent production factors, such as robots, the Internet of Things, and extensive data analysis, are reshaping the dynamics of labour supply and demand. In China, which is a developing country with a large population and labour force, analysing the impact of artificial intelligence technology on the labour market is of particular importance. Based on panel data from 30 provinces in China from 2006 to 2020, a two-way fixed-effect model and the two-stage least squares method are used to analyse the impact of AI on employment and to assess its heterogeneity. The introduction and installation of artificial intelligence technology as represented by industrial robots in Chinese enterprises has increased the number of jobs. The results of some mechanism studies show that the increase of labour productivity, the deepening of capital and the refinement of the division of labour that has been introduced into industrial enterprises through the introduction of robotics have successfully mitigated the damaging impact of the adoption of robot technology on employment. Rather than the traditional perceptions of robotics crowding out labour jobs, the overall impact on the labour market has exerted a promotional effect. The positive effect of artificial intelligence on employment exhibits an inevitable heterogeneity, and it serves to relatively improves the job share of women and workers in labour-intensive industries. Mechanism research has shown that virtual agglomeration, which evolved from traditional industrial agglomeration in the era of the digital economy, is an important channel for increasing employment. The findings of this study contribute to the understanding of the impact of modern digital technologies on the well-being of people in developing countries. To give full play to the positive role of artificial intelligence technology in employment, we should improve the social security system, accelerate the process of developing high-end domestic robots and deepen the reform of the education and training system.
A new methodology for measuring the enthalpies of mixing and heat capacities of molten chloride salts using high temperature drop calorimetry
Authors: Strzelecki Andrew C. , Cockreham Cody B. , Parker S. Scott , Mann Shane C. , Lhermitte Charles , Wu Di , Guo Xiaofeng , Monreal Marisa , Jackson J. Matt , Mitchell Jeremy , Boukhalfa Hakim , Xu Hongwu
Published: January 2024

Molten salt reactors (MSRs) are a promising alternative to conventional nuclear reactors as they may offer more efficient fuel utilization, lower waste generation, and improved safety. The state of knowledge of the properties of liquid salts is far from complete. In order to develop the MSR concept, it is essential to develop a fundamental understanding of the thermodynamic properties, including the heat capacities (Cp) and enthalpies of mixing (ΔHmix), of molten salts at MSR operating conditions. Historically, the Cp values of molten salts were determined by drop-calorimetry or differential scanning calorimetry, whereas their ΔHmix values were typically measured using specialized high temperature calorimeters. In this work, a new methodology for measuring both the Cp and the ΔHmix of molten chloride salts was developed. This novel method involves sealing a chloride salt sample in a nickel capsule and performing conventional transposed temperature drop calorimetry using a commercially available Setaram AlexSYS-800 Tian–Calvet twin microcalorimeter. This methodology may be applied to calorimetric measurements of more complex salt mixtures, especially mixtures containing actinides and fission products.
Generalized prediction for self-starting performance of two-dimensional hypersonic inlets
Authors: Yang Shu-zi , Xie Wen-zhong , Xu Cheng-long , Ma Guang-fu
Published: January 2024

The acceleration self-starting performance of a hypersonic inlet is pivotal for ensuring the stable operation of a scramjet. While the geometric configuration of the internal contraction section (ICS) considerably influences the inlet's self-starting performance, the current prediction model solely considers the internal contraction ratio. To encompass the entire geometric configuration's influence on ICS, a generalized prediction model for the acceleration self-starting Mach number of critical hard unstart two-dimensional hypersonic inlets is proposed. This model calculates the theoretical reattachment pressure rise of the main separation bubble within the actual unstarted flow structure of the hypersonic inlet. Additionally, it computes the theoretical pressure rise assuming the main separation bubble is in a critical state. By comparing these pressures, the model evaluates whether the main separation bubble can be sustained under given incoming flow conditions, predicting the self-starting Mach number. This modeling approach offers broad adaptability to various ICS configurations and incoming flow Reynolds numbers. Each step of the prediction model and the final computational results underwent rigorous evaluation through unsteady numerical simulations. Remarkably, the prediction results demonstrated exceptional alignment with simulation outcomes, surpassing the accuracy of previous prediction methods.
Suppression of flow separation around a finite wall-mounted square cylinder by suction at the side leading edge
Authors: Jin Xiaowei , Dai Mingwei , Zou Xuchao , Laima Shujin
Published: January 2024

We investigate the control of three-dimensional flow separation around a finite wall-mounted square cylinder by applying suction at the side leading edge. Direct numerical simulations are conducted at a Reynolds number of 250, with suction ratios Γ of 0–2 (where Γ is the absolute value of the suction velocity divided by the free stream velocity). The effect of Γ on the aerodynamic forces acting on the cylinder is studied. The results show that suction reduces the aerodynamic forces, with the best control effect for the fluctuating lift coefficient (corresponding to a reduction of over 70%) achieved at Γ = 0.375. As the suction ratio increases, the pressure drag experienced by the square cylinder decreases. Simultaneously, the mean frictional drag force exerted on the square cylinder increases. The optimal mean drag coefficient (corresponding to a reduction of nearly 20%) is achieved at Γ = 1. The effect of the suction ratio on the flow topology in the wake is also investigated. Suction significantly suppresses the flow separation. As the suction ratio increases, the spanwise counter-rotating vortices in the streamwise and transverse directions decreases in size, and the downwash vortex shrinks, and shifts toward the free end of the square cylinder. The far-wake streamwise base vortex disappears when active suction is applied to the side leading edge. However, a new pair of base vortices splits from the original base vortex and persists into the far wake flow field, forming a quadrupole vortex structure with the tip vortex.
Collisions among elongated settling particles: The twofold role of turbulence
Authors: Grujić Anđela , Bhatnagar Akshay , Sardina Gaetano , Brandt Luca
Published: January 2024

We study the collision rates of settling spheres and elongated spheroids in homogeneous, isotropic turbulence by means of direct numerical simulations aiming to understand microscale-particle encounters in oceans and lakes. We explore a range of aspect ratios and sizes relevant to the dynamics of plankton and microplastics in water environments. The results presented here confirm that collision rates between elongated particles in a quiescent fluid are more frequent than those among spherical particles in turbulence due to oblique settling. We also demonstrate that turbulence generally enhances collisions among elongated particles as compared to those expected for a random distribution of the same particles settling in a quiescent fluid, although we also find a decrease in collision rates in turbulence for particles of the highest density and moderate aspect ratios (A=5). The increase in the collision rate due to turbulence is found to quickly decrease with aspect ratio, reach a minimum for aspect ratios approximately equal to 5, and then slowly increase again, with an increase up to 50% for the largest aspect ratios investigated. This non-monotonic trend is explained as the result of two competing effects: the increase in the surface area with aspect ratio (beneficial to increase encounter rates) and the alignment of nearby prolate particles in turbulence (reducing the probability of collision). Turbulence mixing is, therefore, partially balanced by rod alignment at high particle aspect ratios.
Machine learning based longitudinal virtual diagnostics at SwissFEL
Authors: Bettoni S. , Orlandi G. L. , Salomone F. , Boiger R. , Ischebeck R. , Xue R. , Mostacci A.
Published: January 2024

The bunch length in a linac driven Free Electron Laser (FEL) is a major parameter to be characterized to optimize the final accelerator performance. In linear machines, this observable is typically determined from the beam imaged on a screen located downstream of a Transverse Deflecting Structure (TDS) used to impinge a time dependent kick along the longitudinal coordinate of the beam. This measurement is typically performed during the machine setup and only sporadically to check the beam duration, but it cannot be continuously repeated because it is time consuming and invasive. A non-invasive method to determine the electron bunch length has already been presented in the past. This method is based on the analysis of the synchrotron radiation light spot emitted by the bunch passing through a magnetic chicane, provided that the energy chirp impinged on the bunch by the upstream radio frequency structures is known. In order to overcome a systematic discrepancy affecting the synchrotron radiation monitor based results compared to the absolute TDS based ones, we implemented and optimized a machine learning approach to predict the bunch length downstream of the two SwissFEL compression stages—from about 10 fs up to about 2 ps—as well as the beam longitudinal profile at the first one.
Design and analysis of impedance matching for a radial standing wave piezoelectric ultrasonic motor
Authors: Jiang Chunrong , Cheng Sunan , Shen Zhan , Jin Long
Published: January 2024

Impedance matching circuits are capable of tuning and wave filtering, which is beneficial to performance improvement of piezoelectric ultrasonic motors. At present, impedance matching for piezoelectric ultrasonic motors is usually realized through a series inductance, which has the problem of poor wave filtering effect. Different from the previous series inductance matching method for ultrasonic motors, a series inductance and capacitance matching method is proposed for a radial standing wave piezoelectric ultrasonic motor. The series capacitance is added to adjust the quality factor of the resonance tank so that a desired wave filtering effect can be obtained. The values of the series inductance and capacitance are derived based on the Butterworth–Van Dyke model of the piezoelectric ultrasonic motor. Simulations are conducted to verify the feasibility of the proposed matching method. Finally, the waveforms of voltages and currents as well as torque–speed curves of the motor are measured. The results validate the proposed matching method. In addition, the previous series inductance matching method is compared. The results show that the proposed series inductance and capacitance matching method not only achieves tuning function but also obtains a significantly improved wave filtering effect. Moreover, the torque–speed characteristics of the motor are also improved with the proposed matching method.
Visualization of sidewall vortices in rectangular nozzle supersonic blowdown wind tunnel
Authors: Andrews Philip S. , Lax Philip A. , Thomas Flint O , Leonov Sergey B.
Published: January 2024

This study focuses on the details of the geometry and dynamics of sidewall vortices observed in supersonic wind tunnels with a rectangular cross section of the nozzle and the test section. The formation of sidewall vortices limits the accuracy of the data measured during wind tunnels' testing due to a reduced area of uniform core flow results. Most of the test data presented in this work are generated using Mie scattering visualization for M = 4 flow, with CO2 seeded up to 7% mole fraction. The Mie scattering results are complemented by data from fast pressure sensor and schlieren visualization. It is shown that the formation of vortices is caused by a transverse pressure gradient realized in the supersonic nozzle due to the gas under-expansion. The vortex external mixing layer is strongly perturbed in time but remains globally geometrically similar with streamwise distance. The vortex-generated dominant flow disturbances are in the frequency range of f = 10–50 kHz, doubling the magnitude of baseline power spectral density. The authors' viewpoint is that sidewall vortex generation is a more generic phenomenon than was thought previously.
Advancing fluid dynamics simulations: A comprehensive approach to optimizing physics-informed neural networks
Authors: Zhou Wen , Miwa Shuichiro , Okamoto Koji
Published: January 2024

Flow modeling based on physics-informed neural networks (PINNs) is emerging as a potential artificial intelligence (AI) technique for solving fluid dynamics problems. However, conventional PINNs encounter inherent limitations when simulating incompressible fluids, such as difficulties in selecting the sampling points, balancing the loss items, and optimizing the hyperparameters. These limitations often lead to non-convergence of PINNs. To overcome these issues, an improved and generic PINN for fluid dynamic analysis is proposed. This approach incorporates three key improvements: residual-based adaptive sampling, which automatically samples points in areas with larger residuals; adaptive loss weights, which balance the loss terms effectively; and utilization of the differential evolution optimization algorithm. Then, three case studies at low Reynolds number, Kovasznay flow, vortex shedding past a cylinder, and Beltrami flow are employed to validate the improved PINNs. The contribution of each improvement to the final simulation results is investigated and quantified. The simulation results demonstrate good agreement with both analytical solutions and benchmarked computational fluid dynamics (CFD) calculation results, showcasing the efficiency and validity of the improved PINNs. These PINNs have the potential to reduce the reliance on CFD simulations for solving fluid dynamics problems.
Enhanced dropwise condensation on downward-facing cross-shaped pillar-structured surfaces with mixed wettability
Authors: Tang Shi , Li Qing , Li Wanxin , Chen Shoutian
Published: January 2024

In this paper, a novel downward-facing cross-shaped pillar-structured surface with mixed wettability is conceived for enhancing dropwise condensation. A three-dimensional thermal lattice Boltzmann model is employed to investigate the condensation performance on the downward-facing cross-shaped pillar-structured surface with mixed wettability and the associated enhancement mechanism of dropwise condensation. The numerical investigation shows that the cross-shaped pillar-structured surface with mixed wettability exhibits much better condensation performance than the square pillar-structured surface with mixed wettability and the flat surface with mixed wettability due to the synergistic effects of structural effects and mixed wettability, which can promote the droplet nucleation and accelerate the condensate removal. Moreover, for different contact angles of the pillar top (θtop), there exists a competition between the droplet nucleation and the condensate removal on the downward-facing cross-shaped pillar-structured surface. It is found that, when θtop=60°, an optimal droplet dripping rate can be achieved due to a suitable balance between a relatively large mass of detached droplets and a short condensation cycle time. Furthermore, the aspect ratio (γ) has an important influence on the droplet dripping rate, i.e., as γ increases, the droplet dripping rate first exhibits small fluctuations, then increases rapidly before γ=1.0, and after that experiences a slight variation. The large droplet dripping rate achieved at γ=1.0 is mainly attributed to the fact that an optimum structure of the concave corner can promote the droplet nucleation, increase the length of the triple-phase contact line, advance the appearance of droplet coalescence, and finally accelerate the condensate removal.
Theoretical analysis of bulk acoustic wave resonators with emerging
ε
-Ga2O3 piezoelectric film
Authors: Zhang Zhang , Yang Lili , Liu Zeng , Wang Xi'an , Luo Haosu , Wang Yaojin
Published: January 2024

In this paper, the theoretical analysis of 2.3 GHz bulk acoustic wave (BAW) resonators with emerging ε-Ga2O3 piezoelectric films was investigated. By using the finite element method to calculate the dispersion curve of the BAW resonator based on ε-Ga2O3, we designed and optimized the Bragg reflector structure as well as the metal frame to suppress transverse energy leakage. When the width of the raised metal frame is an odd multiple of the quarter wavelength of the S1 Lamb mode, the vibration displacement at the boundary of the resonators is significantly suppressed, and the acoustic energy is concentrated as much as possible in the effective area of the resonators, resulting in improvement of the Qp and Qmax. Therefore, the ε-Ga2O3 based BAW resonators with Bode Qmax (∼1488), electromechanical coupling coefficient k2eff (∼15%), and the figure of merit (FoM) coefficient (∼223) are simulated and designed. Detailed theoretical analysis provides the key theoretical guidance and design scheme for the realization of ε-Ga2O3 BAW filters. The above-mentioned results imply that the emerging ε-Ga2O3 piezoelectric semiconductors have application prospects in BAW resonators and radio frequency front-end fields.
Interactional aerodynamics and acoustics of a rotor with an airframe in hover
Authors: Kim Si Jin , Hwang Yu-Hyeon , Myong Rho Shin , Lee Hakjin
Published: January 2024

The demand for the development of urban air mobility (UAM) powered by electric systems has been steadily rising across private and public sectors. Most UAM flights incorporate a distributed electric propulsion system to enhance aircraft safety and reliability, which entails an increase in the number of rotors or propellers. Consequently, aerodynamics and aeroacoustics are significantly influenced by strong interactions between the rotor and the airframe. In this study, we conducted a computational investigation to examine the impact of rotor–airframe interaction on aerodynamic and aeroacoustic characteristics. This examination considered variations in airframe shape and the distance between the rotor and airframe. The aerodynamic analysis was executed using the lattice-Boltzmann method simulation, in which acoustic predictions were made using the Ffowcs Williams–Hawkings(FW–H) acoustic analogy with a permeable surface. The airframe consists of two geometries: a cylinder and a cone. Tip vortex breakdown and the transition into the turbulent wake state were captured in both airframes, and a fountain flow was affected by the downwash circulation generated under certain proximity of airframe cases. The acoustic prediction results showed that high-intensity noise radiated over the broad surface of the airframe in the conical airframe case. Significant thrust force fluctuations and an increase in noise level were observed at the smallest rotor tip clearance, S/R=−0.1, compared to the isolated rotor. Furthermore, the noise contribution of the rotor and airframe was compared, revealing that the airframe noise level was even higher than the rotor noise at S/R=−0.1.
Direct numerical simulation of the drag, lift, and torque coefficients of high aspect ratio biomass cylindrical particles
Authors: Wang Jingliang , Ma Lun , Jiang Maoqiang , Fang Qingyan , Yin Chungen , Tan Peng , Zhang Cheng , Chen Gang
Published: January 2024

Biomass straw fuel has the advantage of low-carbon sustainability, and therefore, it has been widely used in recent years in coupled blending combustion with coal-fired utility boilers for power generation. At present, the drag force FD, the lift force FL, and the torque T evaluation model are very limited. In this study, within a wide range of Reynolds numbers (10 ≤ Re ≤ 2000) and incident angles (0° ≤ θ ≤ 90°), the computational fluid dynamics open source code OpenFOAM-body-fitted mesh method is used to carry out the direct numerical simulation of the flow characteristics of large cylindrical biomass particles with a high aspect ratio of L/D = 9:1. The results show that (1) the projected area of the cylinder begins to decrease after reaching the maximum at θ = 15°, while the change in the incident angle causes the formation of a smaller recirculation zone on the leeward side of the structure, and the effect of the pressure difference on the drag coefficient (CD) is reduced. (2) The lift coefficient (CL) displays a parabolic symmetric distribution when θ = 45°, and then the distribution becomes asymmetrical when Re > 100. The torque coefficient (CT) exhibits a similar trend. (3) Based on the simulation data and the literature data, new models for CD, CL, and CT for cylinders with L/D = 9:1, 10 ≤ Re ≤ 2000 and 0° ≤ θ ≤ 90° are obtained, and the mean square errors are 2.4 × 10−2, 1.4 × 10−2, and 6.4 × 10−2, respectively. This new model can improve the accuracy and adaptability of the universal model of gas–solid dynamics for biomass particles.
Unsupervised machine learning of virus dispersion indoors
Authors: Christakis Nicholas , Drikakis Dimitris , Ritos Konstantinos , Kokkinakis Ioannis W.
Published: January 2024

This paper concerns analyses of virus droplet dynamics resulting from coughing events within a confined environment using, as an example, a typical cruiser's cabin. It is of paramount importance to be able to comprehend and predict droplet dispersion patterns within enclosed spaces under varying conditions. Numerical simulations are expensive and difficult to perform in real-time situations. Unsupervised machine learning methods are proposed to study droplet dispersion patterns. Data from multi-phase computational fluid dynamics simulations of coughing events at different flow rates are utilized with an unsupervised learning algorithm to identify prevailing trends based on the distance traveled by the droplets and their sizes. The algorithm determines optimal clustering by introducing novel metrics such as the Clustering Dominance Index and Uncertainty. Our analysis revealed the existence of three distinct stages for droplet dispersion during a coughing event, irrespective of the underlying flow rates. An initial stage where all droplets disperse homogeneously, an intermediate stage where larger droplets overtake the smaller ones, and a final stage where the smaller droplets overtake the larger ones. This is the first time computational fluid dynamics is coupled with unsupervised learning to study particles' dispersion and understand their dynamic behavior.
A study on motor characteristics based on pole-slot combinations
Authors: Kim Su Yong
Published: January 2024

Electric devices called motors, which have a history of 100 years, are the devices that use the most electricity in the world. Therefore, the development of high-efficiency motors leads to efficient power use and carbon neutrality. In motor design, the combination of poles and slots is very important. It affects many characteristics including back electromotive force waveform and magnitude, torque and torque ripple, cogging torque, noise and vibration, and efficiency. The most widely used combination of poles and slots is 8 poles and 12 slots. And recently, 8-pole 9-slots are also attracting attention for their various advantages. This paper compares the characteristics of 8-pole 12 slots and 8-pole 9 slots through computer simulation. And to overcome the weaknesses of 8 poles and 9 slots, a multiple of the pole-slot combination is applied. Finally, the comparative values are verified through an experiment.