bluuebunny/crossref_metadata_2025 huggingface dataset:
A Practical Implementation of RESTful API and WebSocket Protocol for Power Efficiency Monitoring: A Case Study at Muhammadiyah Orphanage
Authors: Putra Karisma Trinanda , Ahmadda Danar Arya , Rohmansyah  , Ardi Nugraha Toha , Mujaahid Faaris , Kurniawan Ahdi , Chen Hsing-Chung
Published: September 2024

Power efficiency needs to be monitored to avoid adverse effects on electricity users, particularly those with significant inductive loads. However, current monitoring devices are limited in their ability to continuously record data and represent outputs effectively. This study designs an IoT-based reactive power and power factor monitoring system using a RESTful API for electrical equipment at a Muhammadiyah orphanage. The proposed system utilizes the PZEM-004T as the power sensor, the ESP32 microprocessor as the data processing unit, and a web server as the interface for settings and data visualization. Measurement records for reactive power and power factor can be stored in internal data storage. Additionally, remote monitoring can be conducted via WebSocket protocol and the Telegram application. The system has been tested by comparing reactive power, power factor, kWh, and cost with a standard power meter. The results demonstrate that the sensor exhibits an error of 9.02% in current measurement and 1.106% in active power measurement, with an average delay of 0.137 seconds via WebSocket-based server and 1.359 seconds using Telegram application.
Chemical and Physical Characterization on Metal Alloy Selection for Throwing Knife
Authors: Yudhanto Ferriawan , Wisnujati Andika , Anugrah Rinasa Agistya , Jamir Mohd Ridzuan Mohd , Nabil Muhammad
Published: September 2024

The materials for making throwing knives are selected to determine the characteristics of the two materials. The materials used are Mild Steel (A36) and SUP 9. The prices of these two materials are different, thus affecting the economic value of the final throwing knife product. Chemical composition, hardness and metallography tests are used to determine the properties of the starting material before heat treatment is carried out on the material. The results after testing showed that the carbon, manganese, chromium, and silicon content in SUP 9 steel was very high compared to that of mild steel. The microstructure image results show that SUP 9 steel is dominated by pearlite and very little ferrite, which causes the hardness of SUP 9 steel (231.8 HVN) to be higher than that of mild steel (164.3 HVN). These characteristics show that SUP 9 steel is very suitable for throwing knives that require high strength.
DHT 11 Sensor-Based Automatic Chicken Egg Hatching Incubator
Authors: Jusman Yessi , Irfan Kusumabrata Muhammad , Purwanto Kunnu , Fawwaz Nurkholid Muhammad Ahdan
Published: September 2024

The process of hatching chicken eggs by farmers still uses manual methods, in the market itself there are hatching machine tools but not fully automated. So that the chicken breeding process is less effective and efficient to meet high market needs. In this study, an automatic chicken egg hatching incubator device based on the DHT 11 sensor was designed. The purpose of this design is to help farmers to hatch chicken eggs automatically. The way this tool works is to hatch chicken eggs automatically with a DHT 11 sensor that can read temperature and humidity so that temperature and humidity can be stable according to the needs obtained from the heat of incandescent lamps, fans, and water in the incubator. Then for the process of turning chicken eggs, farmers do not need to do it manually because they already use automatic racks regulated by RTC (Real Time Clock). For the egg turning schedule so that it will move the dynamo motor and the egg rack will shift to turn the eggs. As a result of this study, the well-designed device works and can produce 91% egg hatching with stable temperature and humidity and scheduled egg turning.
Empowering Creative Education: Applying Chat GPT for Enhancing Student Engagement in Senior Teacher-Driven Instructional Design in the Philippines
Authors: Hatmanto Endro Dwi , Pasandalan Sittie Noffaisah B. , Rahmawati Fitria , Sorohiti Maryam
Published: September 2024

Within the dynamic realm of education, the integration of technology has significantly transformed conventional pedagogical approaches, thereby advocating novel tactics to enhance student involvement. The present study delves into the efficacy of ChatGPT technology in amplifying student engagement within the educational landscape of the Philippines, specifically under the supervision of experienced educators. Acknowledging the pivotal significance of student participation in facilitating effective teaching and learning processes, this investigation examines the perspectives and strategies of adept instructors in integrating ChatGPT into their pedagogical frameworks. By conducting semi-structured interviews with ten senior educators hailing from Mindanao City, this study gathered qualitative data on the utilization of ChatGPT to foster interactive and stimulating educational activities, which were subsequently scrutinized using content analysis techniques. The results illuminate a diverse range of attitudes towards ChatGPT, spanning from enthusiasm to skepticism, and unveil specific approaches such as tailored prompts, structured inquiry, and diverse modes of expression. This research addresses a conspicuous void in the existing literature concerning AI-infused education by offering insights into the pragmatic deployment and potential hurdles of utilizing ChatGPT to nurture creativity and student engagement in the Philippine context. It accentuates the imperative need for further exploration of innovative technological instruments to enhance educational methodologies and outcomes.
Eco-Friendly Product: The Role of Pounding Ecoprint Training on Green Economy
Authors: Saptutyningsih Endah , Paripurna Kamiel Berli , Bhakti Hartarto Romi , Putri Johana Engrasia , Anggoro Tri , Hanim Binti Dato Mohamad Zailani Suhaiza
Published: September 2024

The problems found in PPR Kerinchi are the natural potential of the area that has not been utilized properly, the lack of skills in managing the potential of this community group, the majority of whom are housewives with minimal income. The International Community Service Program is carried out to provide solutions by utilizing the natural potential of PPR Kerinchi and increasing the ability of BMT recipient members to create an eco-friendly product by utilizing the natural potential in their area. This study aims to determine the differences between before-and-after the community service program by holding training in making ecoprints by utilizing natural materials found in the surrounding environment, thus providing direct benefits to people’s lives in the social and economic fields as well as improving the quality of resources through empowering BMT recipient mothers, in PPR Kerinchi also supports the creation of a green economy. The study revealed that the pounding ecoprint training can support the green economy by providing community members with skills to create eco-friendly products, thus increasing their income. Additionally, incorporating online market training empowers these communities to reach broader markets, further enhancing their income growth. The findings demonstrate the importance of increasing the community capacities in utilizing local natural potential and improving community welfare in supporting the green economy.
Nationwide Survey – What is important for a sustainable radiology?
Authors: Palm Viktoria , Wucherpfennig Lena , Do Thuy Duong , Fink Matthias Alexander , von Stackelberg Oyunbileg , Schwaiger Benedikt Jakob , Kauczor Hans-Ulrich
Published: September 2024

Radiology departments with the large diagnostic devices CT and MRI contribute significantly to the overall energy consumption of health facilities. However, there is a lack of systematic knowledge about the opinions of radiological staff on the most relevant aspects of sustainability. For this reason, we conducted a comprehensive survey for radiology employees on sentiment and experiences regarding sustainability in radiology.

In collaboration with the Sustainability Network of the German Roentgen Society (DRG), we developed a questionnaire on various dimensions of sustainability in radiology. We conducted a nationwide online survey of radiology employees between July 1st, 2023 and November 30th, 2023. The absolute and percentage distributions were then determined.

From 109 participants, mainly doctors (67/109; 62%) from university hospitals (48/109; 44.0%), 81 out of 109 rated sustainability in professional environment (74.3%) as important or very important. However, only 38 out of 109 (38%) of the respondents were able to name specific sustainable procedures in their institute. The most important topics for a sustainable radiology were waste management (26/109, 22.6%), energy reduction (19/109, 16.5%), conscious behaviour (15/109, 13%) and reduction of obsolete examinations (14/109, 12.2%). In addition, a lack of qualifications (16%), finances (21%) and compliance (21%) were named as challenges for the implementation of sustainable actions in radiology. The perceived importance of specific, sustainable measures in radiology is generally higher than the amount of already established actions.

Radiology has significant, yet untapped, potential for sustainable optimization. There is a need for qualified and sensitized health care workers in radiology who are committed to sustainability in everyday clinical practice. Among other things, in this study the respondents demand a more critical indication for diagnostic workup, including avoiding redundant examinations, and a technological progress towards energy-efficient devices, which requires a dynamic exchange between radiology, industry and health care facilities.
Tabuthema Fehlgeburt? – Verankerung durch Mechanismen auf
medizinischer, sozialer und organisationaler Ebene „Es hat mir mein Herz
gebrochen und es ist halt so ...“
Authors: Christl-Sebinger Sarah , Schildberger Barbara
Published: September 2024

Einleitung Eine Fehlgeburt stellt die häufigste
Schwangerschaftskomplikation dar. In dieser Arbeit sollen die mit der Fehlgeburt
assoziierten Erlebnisse und deren Relevanz für die Frauen auf unterschiedlichen
Ebenen aufgearbeitet werden.

Methode Im Mai 2023 werden 14 leitfadengestützte Interviews mit Frauen
geführt. Das damit gewonnene Textmaterial wird mit Hilfe der inhaltsanalytischen
Vorgehensweise nach Mayring einem höheren Abstraktionsniveau zugeführt und im
Anschluss interpretiert.

Ergebnisse Die Untersuchungsergebnisse untermauern die Tragweite einer
Fehlgeburt als einschneidendes Erlebnis und die Annahme einer breiten, als
belastend erlebten, Tabuisierung. Der bewusst gewählte Austausch unter
Gleichgesinnten, die Verheimlichung der Schwangerschaft und in Folge der
Fehlgeburt aus Gründen der Scham, des Selbstschutzes vor beruflichen Nachteilen
und die Vermutung, das Gegenüber zu überfordern, wiegen nicht so schwer wie jene
Mechanismen, die im Gesundheitsbereich verortet sind: auf dieser Ebene tragen
Misstrauen, Bagatellisierung und organisatorische sowie räumliche
Unzulänglichkeiten zur Tabuisierung bei. Abgefedert wird der belastende Umstand
der Fehlgeburt durch Personen, die die Trauer anerkennen und Unterstützung
anbieten.

Schlussfolgerungen Auf Basis der Untersuchungsergebnisse können vor allem
Verbesserungen im Versorgungsbereich abgeleitet werden: Anerkennung der
Fehlgeburt, bedarfsorientierte Unterstützungsleistungen, Verbesserung
kommunikativer Elemente und organisatorischer sowie räumlicher
Rahmenbedingungen.
Caseload and In-Hospital Outcome of Carotid Surgery Performed during the COVID-19 Pandemic vs. Previous Years: A Single-Centre Analysis
Authors: Westreicher Werner , Goidinger Alina , Gruber Ingrid , Grams Astrid , Knoflach Michael , Wipper Sabine , Kluckner Michaela , Klocker Josef
Published: September 2024

With the beginning of the COVID-19 pandemic in March 2020, restrictions and challenges for elective and emergency vascular surgery as well as worse outcomes were reported. This study aims to compare our single-centre experience with carotid artery surgery during the pandemic and previous years.

Our retrospective analysis included all consecutive patients undergoing carotid surgery for symptomatic and asymptomatic stenosis between January 2017 and December 2021. Caseload, operation specific parameters, and demographic data as well as in-hospital outcome were compared during the COVID-19 pandemic versus previous years.

A total of 623 consecutive patients were included. The caseload comparison showed an average of 112 carotid artery surgeries per adjusted year (March 16th to December 31st) from 2017 to 2019, prior to the pandemic. The caseload reduction in the first year of the pandemic (2020) was 36.6% (n = 71) and 17.9% (n = 92) in the second year (2021). No rebound effect was observed. There was no significant difference (p = 0.42) in the allocation of symptomatic and asymptomatic patients (asymptomatic patients: 37.1% prior vs. 40.8% during the pandemic; symptomatic patients: 62.9 vs. 59.2%). Major adverse event rates in years prior to the pandemic were postoperative bleeding requiring revision: n = 31 (7.1%); stroke in symptomatic patients: n = 9 (3.3%) and stroke in asymptomatic patients: n = 4 (2.5%); symptomatic myocardial infarction (MCI): n = 1 (0.2%); death: n = 2 (0.5%). During the pandemic, major adverse event rates were postoperative bleeding requiring revision: n = 12
(6.5%); stroke in symptomatic patients: n = 1 (0.9%), stroke in asymptomatic patients: n = 1 (1.3%); symptomatic MCI: n = 1 (0.5%); death: n = 1 (0.5%).

Since the beginning of the COVID-19 pandemic in March 2020, there has been a significant reduction in carotid artery surgery performed both in symptomatic as well as in asymptomatic patients. There was no worsening of the outcome of carotid surgery performed during the COVID-19 pandemic, and this remained safe and feasible.
Effect of loading rate on characteristics of cyclic structural adjustment of sandstone granules
Authors: Ma Tengfei , Zou Quanle , Kong Fanjie , Ran Qican , Qin Dengke , Hu Yulin , Lv Feixiang , Zheng Haolong
Published: September 2024

During underground coal seam mining, changes in the working face advancement rate can easily affect the compaction state of granules in the collapse zone. This is an important factor in the induction of gas disasters and surface subsidence in mining areas. In this work, a cyclic loading and unloading mechanical test of granules under different loading rates was carried out. The changes in mechanical parameters of the granules at various stages were investigated. It is shown that the strain of each group of specimens under cyclic loading shows an increasing trend and the final strain increases with the loading rate. The input energy of the granules increases under cyclic loading, and under a low loading rate, the compaction force needs to overcome interparticle friction to destroy the relatively stable structure, which results in a need for more energy to achieve the same level of deformation. The acoustic emission ringing counts of each group of granules specimens show an overall increasing trend, with the highest proportion of ringing counts in the first loading stage. The compaction of pores and filling of particles under cyclic loading is a “uniform compaction, stable change, slow adjustment” dynamic process. When the loading is slow, the relative positions of the granule particles in each stress gradient are more adequately adjusted. The results of this study provide important theoretical support for the scientific formulation of gas control strategies and the prevention of surface subsidence in air-mining zones under different mining speeds.
Impact of Al profile in high-Al content AlGaN/GaN HEMTs on the 2DEG properties
Authors: Papamichail A. , Persson A. R. , Richter S. , Stanishev V. , Armakavicius N. , Kühne P. , Guo S. , Persson P. O. Å. , Paskov P. P. , Rorsman N. , Darakchieva V.
Published: September 2024

Ultra-thin high-Al content barrier layers can enable improved gate control and high-frequency operation of AlGaN/GaN high electron mobility transistors (HEMTs) but the precise composition control is very challenging. In this work, we investigate the compositional profiles of AlxGa1−xN/GaN HEMT structures with targeted Al content in the barrier layer, x = 0.50, 0.70, and 1, and thickness in the sub-10 nm range in correlation with the two-dimensional electron gas (2DEG) properties. The HEMT structures are grown by metal-organic chemical vapor deposition on SiC. The maximum Al content in the barrier layer, experimentally determined by scanning transmission electron microscopy combined with energy-dispersive x-ray spectroscopy, is found to be lower than that intended and the deviations from the designed structures increase progressively with increasing x. Compositionally sharp interface between GaN and Al0.46Ga0.54N and box-like Al profile is achieved for intended x∼0.50 while pronounced Al grading is found in the samples with intended x of 0.70 and 1, with a maximum Al content of 0.78 reached for the HEMT structure with intended AlN barrier layer. The impact of the experimentally determined Al profiles on the 2DEG properties, obtained by contactless and electrical Hall effect measurements and coupled with self-consistent solution of the Poisson–Schrödinger equation, is evaluated and discussed. It is shown that the observed deviations from the intended Al profiles have a negative effect on the 2DEG confinement and result in reduced mobility parameters, which have significant implications for the implementation of high-Al content AlGaN/GaN structures in high-frequency devices.
Optimization of damping function parameters for -D3 and -D4 dispersion models for Hartree–Fock based symmetry-adapted perturbation theory
Authors: Wallace Austin M. , Sherrill C. David
Published: September 2024

Symmetry-adapted perturbation theory (SAPT) directly computes intermolecular interaction energy in terms of electrostatics, exchange-repulsion, induction/polarization, and London dispersion components. In SAPT based on Hartree–Fock (“SAPT0”) or based on density functional theory, the most time-consuming step is the computation of the dispersion terms. Previous work has explored the replacement of these expensive dispersion terms with simple damped asymptotic models. We recently examined [Schriber et al. J. Chem. Phys. 154, 234107 (2021)] the accuracy of SAPT0 when replacing its dispersion term with Grimme’s popular -D3 correction, reducing the computational cost scaling from O(N5) to O(N3). That work optimized damping function parameters for SAPT0-D3/jun-cc-pVDZ using estimates of the coupled-cluster complete basis set limit [CCSD(T)/CBS] on a 8299 dimer dataset. Here, we explore the accuracy of SAPT0-D3 with additional basis sets, along with an analogous model using -D4. Damping parameters are rather insensitive to basis sets, and the resulting SAPT0-D models are more accurate on average for total interaction energies than SAPT0. Our results are surprising in several respects: (1) improvement of -D4 over -D3 is negligible for these systems, even charged systems where -D4 should, in principle, be more accurate; (2) addition of Axilrod–Teller–Muto terms for three-body dispersion does not improve error statistics for this test set; and (3) SAPT0-D is even more accurate on average for total interaction energies than the much more computationally costly density functional theory based SAPT [SAPT(DFT)] in an aug-cc-pVDZ basis. However, SAPT0 and SAPT0-D3/D4 interaction energies benefit from significant error cancellation between exchange and dispersion terms.
High switching ratio of antiferromagnetic order in thick sputtered Mn3+xSn1−x films by spin–orbit torque
Authors: Song Houning , Wang Dong , Xing Yuzhi , Zhao Wenxiao , Qi Chen , Wei Lin , Yan Shishen , Tian Yufeng , Bai Lihui , Chen Yanxue
Published: September 2024

Electrical manipulation of the antiferromagnetic states of Weyl semimetal Mn3Sn by current-induced spin–orbit torque (SOT) has attracted intensive attention recently, largely due to its potential advantage for high-density integration and ultrafast operation. In this study, the relation between the antiferromagnetic SOT switching ratio and the composition of Mn3+xSn1−x films was explored systematically. While SOT manipulation of ferromagnetic order has traditionally been confined to films just a few nanometers in thickness, our results indicate that current-induced SOT can effectively switch the antiferromagnetic order of sputtered Mn3+xSn1−x films with a thickness of up to 100 nm. Notably, a high electrical switching ratio of 83% was obtained in the optimized film with a composition of Mn3.1Sn0.9. The switching of the octupole polarization in thick Mn3Sn films may be accounted for by a seeded SOT mechanism. Joule heating of the Mn3Sn film close to the Néel temperature plays a key role in this switching process. Additionally, the factors influencing the switching ratio were further investigated. This work will deepen our understanding of the electrical switching mechanism of non-collinear antiferromagnetic order in Mn3Sn film and promote the development of antiferromagnetic spintronic devices.
New insights on cavitating flows over a microscale backward-facing step
Authors: Maleki Mohammadamin , Rokhsar Talabazar Farzad , Toyran Erçil , Priyadarshi Abhinav , Sheibani Aghdam Araz , Villanueva Luis Guillermo , Grishenkov Dmitry , Tzanakis Iakovos , Koşar Ali , Ghorbani Morteza
Published: September 2024

This study introduces the first experimental analysis of shear cavitation in a microscale backward-facing step (BFS) configuration. It explores shear layer cavitation under various flow conditions in a microfluidic device with a depth of 60 μm and a step height of 400 μm. The BFS configuration, with its unique characteristics of upstream turbulence and post-reattachment pressure recovery, provides a controlled environment for studying shear-induced cavitation without the complexities of other microfluidic geometries. Experiments were conducted across four flow patterns: inception, developing, shedding, and intense shedding, by varying upstream pressure and the Reynolds number. The study highlights key differences between microscale and macroscale shear cavitation, such as the dominant role of surface forces on nuclei distribution, vapor formation, and distinct timescales for phenomena like shedding and shockwave propagation. It is hypothesized that vortex strength in the shear layer plays a significant role in cavity shedding during upstream shockwave propagation. Results indicate that increased pressure notably elevates the mean thickness, length, and intensity within the shear layer. Instantaneous data analysis identified two vortex modes (shedding and wake modes) at the reattachment zone, which significantly affect cavitation shedding frequency and downstream penetration. The wake mode, characterized by stronger and lower-frequency vortices, transports cavities deeper into the channel compared to the shedding mode. Additionally, vortex strength, proportional to the Reynolds number, affects condensation caused by shockwaves. The study confirms that nuclei concentration peaks in the latter half of the shear layer during cavitation inception, aligning with the peak void fraction region.
The calculation method of blood flow pressure based on four-dimensional flow magnetic resonance imaging and deep learning
Authors: Tao Chunhao , Han Yanjing , Du Tianming , Zhang Yanping , Jin Long , Zhang Hanbing , Chen Shiliang , Wang Qian , Wu Wei , Qiao Aike
Published: September 2024

Utilizing artificial intelligence methods for blood flow pressure estimation can significantly enhance the computational speed of blood flow pressure. However, current related research can only calculate the blood flow pressure parameters of vessels with different geometric shapes under fixed boundary conditions, thus fail to achieve transient flow field calculation and consider the hemodynamic differences formed by patients' varying physiological and pathological conditions. In view of this, this study proposes a method for relative pressure estimation based on four-dimensional flow magnetic resonance imaging (4D flow MRI) of patient blood flow and deep learning. 4D flow MRI was used to obtain the patient's blood flow velocity gradient data, and feature engineering processing is performed on the sampled data. Then, a novel neural network was proposed to acquire the characteristic relationship between velocity gradient and pressure gradient in the vicinity of the point to be measured and within adjacent sampling time periods, thereby achieving the calculation of the relative pressure in the vicinity of the point to be measured. Statistical analysis was performed to evaluate the efficacy of the method, comparing it with computational fluid dynamics methods and catheter pressure measurement techniques. The accuracy of the proposed method exceeded 96%, while computational efficiency was improved by several tens of times, and no manual setting of physiological parameters was required. Furthermore, the results were compared with clinical catheter-measured pressure results, r2 = 0.9053, indicating a significant consistency between the two methods. Compared to previous research, the method proposed in this study can take the blood flow velocity conditions of different patients at different times as input features via 4D flow MRI, thus enabling the calculation of pressure in transient flow fields, which significantly improved computational efficiency and reduced costs while maintaining a high level of calculation accuracy. This provides new direction for future research on machine learning prediction of blood flow pressure.
The “simple” photochemistry of thiophene
Authors: Parkes Michael A. , Worth Graham A.
Published: September 2024

The static gas-phase (“simple”) ultraviolet absorption spectrum of thiophene is investigated using a combination of a vibronic coupling model Hamiltonian with multi-configuration time-dependent Hartree quantum dynamics simulations. The model includes five states and all 21 vibrations, with potential surfaces calculated at the complete active space with second-order perturbation level of theory. The model includes terms up to eighth-order to describe the diabatic potentials. The resulting spectrum is in excellent agreement with the experimentally measured spectrum of Holland et al. [Phys. Chem. Chem. Phys. 16, 21629 (2014)]. The, until now not understood, spectral features are assigned, with a combination of strongly coupled vibrations and vibronic coupling between the states giving rise to a progression of triplets on the rising edge of the broad spectrum. The analysis of the underlying dynamics indicates that population transfer between all states takes place on a sub-100 fs timescale, with ring-opening occurring at longer times. The model thus provides a starting point for further investigations into the complicated photo-excited dynamics of this key hetero-aromatic molecule.
Controlling size and distribution of Au nano-particles on C3N4 for high-efficiency photocatalytic hydrogen production
Authors: Ran Xunan , Chen Zhihua , Ji Hongzhou , Ma Zhaoyu , Xie Yuxi , Li Wenping , Zhang Junying
Published: September 2024

With advantages such as low cost, high stability, and ease of production, visible light photocatalytic C3N4 with a unique microscopic layered structure holds significant potential for development. However, its hydrogen production efficiency remains low due to the pronounced recombination of photo-generated charge carriers and limited surface reaction sites. Normally, the photocatalytic performance of C3N4 can be enhanced by loading noble metals with surface plasmon resonance. It is worth noting that the size of noble metal nanoparticles has a great influence on photocatalytic performance. In this study, accurate controlling of the size and distribution of Au nanoparticles was achieved on the surface of C3N4 by introducing amino groups to improve photocatalytic performance. Results show that uniformly distributed Au nanoparticles in the range of 2–6 nm can be obtained on C3N4 with a remarkable enhancement of hydrogen production efficiency, which is about 114 times the property of pure C3N4. The small-sized and uniformly distributed Au nanoparticles can provide more reaction sites and increase the separation of photo-generated charge carriers, in turn improving Au/NH3–C3N4 photocatalytic hydrogen release rate to 6.85 mmol g−1 h−1. This work offers a facile way to enhance photocatalytic performance by controlling the size of metal nanoparticles on C3N4 precisely.
Unveiling the underlying physics of two-phase boiling heat transfer enhancement through shearing of coalescing bubbles
Authors: Laskar Niloy , Das Mihir K.
Published: September 2024

The upcoming energy scarcity problem has driven research toward developing energy-efficient two-phase heat exchangers essential for various cooling applications. This research is rooted in the principles of pool boiling, essential for effective heat transfer in various heat exchangers. A well-known reported problem in heat exchangers is the dry-out phenomena of heated surfaces due to bubble coalescence. To tackle this undesirable problem, an innovative technique has been introduced in this study, which involves the shearing of bubbles through liquid jet impingement over the heated surface. The study has been carried out in a two-dimensional domain numerically, in the wall superheat range of 9–16 K. To study the underlying physics involved in this pool boiling phenomenon, the bubble dynamics parameters such as departure frequency, bubble diameter, cold spot (bubble base) temperature, and vapor volume fraction have been analyzed. The results show that with the jet shearing effect, a maximum enhancement of 25% in heat transfer rate is observed at higher wall superheat. The investigation also highlights that the liquid jet enhances vapor volume fraction, indicating enhanced steam generation, particularly an enhancement of 27% observed at elevated wall superheat. An early onset necking effect is also observed with the shearing effect, which leads to the formation of smaller bubbles with higher departure frequencies. This study is a benchmark to the fundamental physics of enhancing two-phase heat transfer through bubble shearing, offering promising insights for energy conservation in two-phase heat exchanger design, particularly within the context of pool boiling.
Optical actinometry for number density measurements in low-pressure plasmas: Advantages, error sources, and method validation
Authors: Britun Nikolay , Mo Michael K. T. , Hsiao Shih-Nan , Arellano Fatima J. T. , Sekine Makoto , Hori Masaru
Published: September 2024

Number density of plasma-generated atoms or molecules is an important parameter for both fundamental research and applications. It can be measured in a straightforward manner, using vacuum-ultraviolet absorption spectroscopy, which is mainly possible in laboratory conditions as it may require bulky equipment, such as lasers. By contrast, optical actinometry is an alternative approach that only uses spontaneous emission from the plasma. This technique relies on the so-called corona excitation and uses emission line ratios between the gases with unknown and known concentrations (called actinometer in the last case). As a result of using line ratios, the additional density calibration is not required if the excitation cross sections are known. This study discusses Ar-based actinometry in low-pressure (roughly <1 kPa) plasma discharges with an emphasis on multiple line ratios. The work is particularly focused on the method’s applicability, the choice of Ar cross sections, and potential error sources. The influence of the additional excitation mechanisms is analyzed based on both experiments and modeling. The optical transitions for F, O, H, N, and P atoms along with expressions for their number density are presented, not requiring high optical resolution for measurements. For the sake of method validation, it is shown that in low-pressure radiofrequency discharges, a nearly excellent agreement between the actinometry data and the calibrated measurements can be achieved by careful selection of optical transitions.
Non-modal analysis of transient growth in a liquid annular jet surrounded by gas flow
Authors: Huang Dong-qi , Fang Zi-xuan , Hu Tao , Fu Qingfei , Yang Lijun
Published: September 2024

Transient energy growth is a common mathematical concept in many fluid flow systems, and it has been widely investigated in recent years using non-modal analysis. Non-modal analysis can characterize the short-term energy amplification of perturbations, which is influenced by the Reynolds number, the Weber number, and the initial conditions such as the wavenumber. In gas–liquid coaxial nozzles, annular jets are often produced, and their breakup process is influenced by transient energy growth. However, research in this area has been limited so far. This paper for the first time investigates the transient energy growth of an annular liquid jet in static gas and validates it using a modified annular jet model. In the derivation process, the gas–liquid interfaces inside and outside the annular liquid film are taken into account. It has been found that there exists an optimal initial condition for a certain Reynolds number and a Weber number. The increase in the Reynolds number and ratio of inner and outer radius of the annular jet can maximize the transient growth under a specific initial wavenumber, while the increase in gas/liquid density ratio and the Weber number will minimize the transient growth. It is also found that transient energy growth is caused by the displacement of the free boundary.
The novel impedance matching device realized by the structure of air-gap ring based on the doping method at microwave frequency
Authors: Zhao Lin , Li Jiaxin , Pan Li
Published: September 2024

The doping method enabled the epsilon-near-zero (ENZ) medium to adjust its permeability effectively. In this study, we theoretically analyze that the gap ring structure formed by the ENZ medium doped with perfect electrical conductor (PEC) can be equivalent to the controllable series reactance. Based on this concept, a universal matching network that can match any complex impedance load by adjusting the gap ring spacing is constructed. We used the above universal matching network to carry out theoretical and simulation calculations on the matching effect of a random-sized stepped waveguide and horn antenna, and the results show that the impedance-matching technology has a good matching effect for different loads. Finally, experimental verification is carried out. Compared with traditional impedance-matching networks, the proposed structure has the characteristics of simplicity, reliability, low loss, high carrying power, low preparation requirements, and good application prospects. This work is a good example of the practicality of ENZ media and also provides a very meaningful idea for the development of new electromagnetic matching devices.
Sliding-reversible bandgap modulation in irreversible asymmetric multilayers
Authors: Ke Changming , Yang Yudi , Qian Zhuang , Liu Shi
Published: September 2024

The electronic bandgap of a material is often fixed after fabrication. The capability to realize on-demand and nonvolatile control over the bandgap will unlock exciting opportunities for adaptive devices with enhanced functionalities and efficiency. We introduce a general design principle for on-demand and nonvolatile control of bandgap values, which utilizes reversible sliding-induced polarization driven by an external electric field to modulate the irreversible background polarization in asymmetric two-dimensional (2D) multilayers. The structural asymmetry can be conveniently achieved in homobilayers of Janus monolayers and heterobilayers of nonpolar monolayers, making the design principle applicable to a broad range of 2D materials. We demonstrate the versatility of this design principle using experimentally synthesized Janus metal dichalcogenide multilayers as examples. Our first-principles calculations show that the bandgap modulation can reach up to 0.3 eV and even support a semimetal-to-semiconductor transition. By integrating a ferroelectric monolayer represented by 1T″′-MoS2 into a bilayer, we show that the combination of intrinsic ferroelectricity and sliding ferroelectricity leads to multi-bandgap systems coupled to multi-step polarization switching. The sliding-reversible bandgap modulation offers an avenue to dynamically adjust the optical, thermal, and electronic properties of 2D materials through mechanical and electrical stimuli.
Functional variations in efficiency of PSII during leaf ontogeny in the tropical plant Saraca asoca
Authors: Shasmita   , Swain Barsha Bhushan , Mishra Smrutirekha , Mohapatra Debasish , Naik Soumendra Kumar , Mohapatra Pradipta Kumar
Published: September 2024

Leaf ontogeny of tropical evergreen tree species lasts several months with changes in size, shape, colouration and internal tissue distribution of leaves. Leaf initiation in Saraca asoca generally occurs once in a year during February–April, followed by very limited leafing thereafter. We measured the rate of photosynthesis, chlorophyll a fluorescence, energy quenching and PSII functions during the leaf ontogeny process. Observations were taken up to 35 days after opening of lamina (DAOL). Significant increase in the synthesis and accumulation of photosynthetic pigments but negative net photosynthesis was noticed during initial days of the ontogeny. The leaf moved from heterotrophy to autotrophy with gradual improvement of PSII functions. The ratio of intercellular CO2 (Ci) and ambient CO2 (Ca) showed significant change at ≥11 DAOL. Increase in the age of the leaf (between 5 and 28 DAOL) caused decrease in O-J rise and corresponding increase in J-I and I-P rise as well as of fluorescence maximum (FM) of the OJIP curve. The improvement of the electron transport components of the donor side of PSII was seen with increase in the functional oxygen evolving complex. The functional improvements of the donor and acceptor side of PSII during leaf ontogeny are discussed.
An energy perspective on Galileo’s kinematic paradox
Authors: Hailu Dawit Hiluf
Published: September 2024

The connection between kinematics and work–energy principles is often not emphasized enough for students to appreciate fully. Highlighting the relationship between the kinematic equations and the conservation of total mechanical energy is crucial. We revisit the solution to Galileo’s kinematic paradox from an energy perspective. Galileo stated that the time it takes for an object to travel from the top to the bottom point of a vertical circle is the same regardless of its path. While mathematical proofs of this statement using kinematic approaches are well-documented, this paper explores the problem from an energy standpoint, using experimental evidence to elucidate the relationship between kinematics and energy.
Elastic splitting of x-ray photon by an atomic ion
Authors: Hopersky A N , Nadolinsky A M , Novikov S A
Published: September 2024

The analytical structure, absolute values, and angular anisotropy of the fourfold differential cross section of the elastic splitting of an x-ray photon by a neon-like atomic ion are theoretically predicted.
Advances in timing and control of ultrafast molecular dynamics: from XUV to infrared
Authors: Jiang Wenyu , Pan Shengzhe , Huang Hao , Tong Jihong , Zhang Wenbin , Ni Hongcheng , Wu Jian
Published: September 2024

With the availability of modern laser and detection technologies, the investigation of ultrafast molecular dynamics induced by intense laser pulses has become a routine practice. In this Topical Review, we present a survey of recent progress in the timing and control of ultrafast molecular dynamics, encompassing processes initiated by both extreme ultraviolet and near infrared pulses. Prospects and perspectives of this field are given. This Review underscores the remarkable potential for further advances in understanding and harnessing ultrafast molecular processes.
Electron-impact excitation data for W2+ in support of tungsten spectroscopy and re-deposition measurements for magnetically-confined plasmas
Authors: McCann M , Ballance C P , Loch S D , Ennis D A
Published: September 2024

To better understand plasma wall interactions involving tungsten, accurate atomic structure and electron-impact driven collisional processes for near-neutral ion stages of tungsten are required. Complementing existing work on neutral and singly ionised tungsten, atomic structure and collisional calculations for W2+ electron-impact excitation have been completed. These excitation calculations are an important component of S/XB coefficients for near-neutral charge states, which may be used to spectroscopically infer re-deposition of tungsten at the plasma-solid boundary of fusion relevant devices. With W2+ in particular having emission lines that can be observed at ultraviolet (UV) wavelengths, while higher charge states of tungsten are unlikely to have lines possible to observe outside of the vacuum UV range. The atomic structure was generated using the General-purpose Relativistic Atomic Structure Package (GRASP0), implementing the Multi-configuration Dirac Fock approach. This structure was the basis for a subsequent Dirac R-matrix electron-impact excitation calculation to provide Maxwellian averaged rate coefficients. A synthetic spectrum was generated from this data using a collisional-radiative model to predict the strongest W III spectral lines and these lines were compared to emission from the Compact Toroidal Hybrid (CTH) plasma device. Several of the strongest W III lines are observed in CTH and agree well with the modelled line wavelengths and intensities, a table of these lines is provided that could be observed in other devices.
Effects of anode evaporation process on the anode sheath characteristics in vacuum arc plasma
Authors: Liu Zhaohui , Song Mengmeng , Wang Ziming , Yang Wei , Dong Ye , Sun Qiang , Zhou Qianhong
Published: September 2024

The anode sheath of vacuum arc plasma plays a key role in the generation of anode plasma, but the effects of anode evaporation on the anode sheath remains unclear. In this paper, a theoretical model of a collisional sheath for multi-component plasma coupled with anode evaporation is developed, and the spatial evolution of the anode sheath at different anode surface temperatures is investigated. The results indicate that the distribution of charged particles density and potential in the anode sheath monotonically decreases in the absence or reduction of anode evaporation. When the anode surface temperature exceeds 1900 K, a potential hump appears within the sheath. This is due to enhanced anode evaporation increasing the metal vapor density, which intensifies electron impact ionization and charge exchange collisions, resulting in a higher net space charge density. Finally, the effects of various collision reactions and electron temperatures on the potential hump are analyzed. These findings are meaningful for understanding the anode plasma generation mechanism and regulating the anode plasma parameters.
Development characteristics of rod-plate Gap streamer-leader system at high altitude areas
Authors: Wang Ping , Ma Wenchuang , Zhang Hang , Geng Jianghai , Liu Yunpeng , Luo Bing , Liu Lei , Xiao Wei , Zhong Zheng
Published: September 2024

Air density is an important factors affecting the morphology characteristics of long air gap discharge channels. Analyzing characteristic parameters, such as the propagation velocity and angle of the streamer-leader system at high altitude areas is indispensable in studying the discharge mechanism of long gaps. In this paper, optical images and optical power of the discharge channel were captured. The propagation velocity of the streamer-leader system and angle distribution characteristics of the streamer region were obtained. In accordance with the findings, the downward velocity of the streamer-leader system at low pressure ranges from 1 × 104 to 5 × 104 m s−1. Simultaneously, the velocity decreases slightly under the voltage with a low rise rate, and it is often accompanied by the phenomenon of leader re-luminescence. In addition, the optical images were processed by the pseudo-color algorithm, and the angle of the streamer region of the downward leader head was obtained between 50.3° and 71.6°. The angle of the streamer region is inversely correlated with the voltage rise rate but positively correlated with the gap distance. The results obtained in this paper have academic significance for improving the theoretical system of long gap discharge in high-altitude extreme environments.
Dulac maps of real saddle-nodes
Authors: Ilyashenko Yu
Published: September 2024

Consider a germ of a holomorphic vector field at the origin on the coordinate complex plane. This germ is called a saddle-node if the origin is its singular point, one of its eigenvalues at zero is zero, and the other is not. A saddle-node germ is real if its restriction to the real plane is real. The monodromy transformation for this germ has a multiplier at zero equal to 1. The germ of this map is parabolic and admits a ‘normalizing cochain’. In this note we express the Dulac map of any real saddle-node up to a left composition with a real germ

(

C

,
0
)
→
(

C

,
0
)

through one component of the cochain normalizing the monodromy transformation.
A facile method of deriving solar selective nickel-cobalt oxide thin films via spraying process
Authors: Farhan Ghofran K , Taha Hatem
Published: September 2024

The present study focuses on synthesizing solar selective absorber thin films, combining nanostructured, binary transition metal spinel features and a composite oxide of Co and Ni. Single-layered designs of crystalline spinel-type oxides using a facile, easy and relatively cost-effective wet chemical spray pyrolysis method were prepared with a crystalline structure of MxCo3−xO4. The role of the annealing temperature on the solar selective performance of nickel-cobalt oxide thin films (∼725 ± 20 nm thick) was investigated. XRD analysis confirmed the formation of high crystalline quality thin films with a crystallite size in the range of 27–52 nm. The highest solar absorptance (∼85.2%) and the lowest thermal emittance (∼4.45%) along with the highest values of both hardness and the Young’s modulus (19.1 GPa and 104 GPa, respectively) were obtained for the film annealed at 600 °C. In addition, the synthesized nickel-cobalt oxide thin films show band gap energies in the range of 1.15–1.38 eV and excellent thermal stability at higher temperatures, which makes them interesting candidates for solar absorbing applications.