bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of cardiac rehabilitation in patients with ventricular assist devices: a scoping review
Authors: Portuguez Jaramillo Nelson Esteban , Ceron Angely Paola , Piñeros Álvarez Jose Luis , Giron Ruiz Eleonora , Castro Gómez Carolina
Published: June 2024

Introduction: Ventricular assist devices represent a treatment option for patients with advanced heart failure, offering control over various haemodynamic variables. Similarly, the prescription of exercise within a cardiac rehabilitation programme for heart failure patients is recommended to reduce symptoms, and hospitalisations, improve cardiorespiratory fitness, and increase exercise tolerance. Therefore, exercise prescription can impact those with ventricular assist devices. Given the limited evidence on exercise-based cardiac rehabilitation programmes for this population, this review aims to describe the most commonly used strategies and their health benefits when physical exercise is included in a cardiac rehabilitation programme for patients with ventricular assist devices. Materials and methods: An exploratory review was conducted through searches in the databases: PubMed, SCOPUS, PeDro, and ScienceDirect. The search was limited to studies published between 2013 and 2023. Filters were applied independently by title, abstract, and full text. The included articles were analysed based on the description of the types of cardiac rehabilitation strategies used in patients with ventricular assist devices. Results: Seven articles were included. Each programme employed a cardiopulmonary exercise test before prescribing physical exercise. The most commonly used strategy was aerobic exercise, predominantly high-intensity interval training (HIIT) with intensities close to 90% of peak VO2, followed by continuous moderate-intensity exercise. Limb strength exercises were included in three programmes. Conclusions: The analysed literature suggests that cardiac rehabilitation in patients with ventricular assist devices is safe and can provide benefits in cardiorespiratory fitness and exercise tolerance. High-intensity interval training is identified as an appropriate strategy for achieving results, offering short-term improvements.
Preliminary Design of Electric Part of Thermoelectric Unit in a Power Plant
Authors: Zhang Guohui , Xu Yanhui
Published: June 2024

With the rapid development of society, people’s awareness of environmental protection continues to strengthen, countries also pay more and more attention to environmental protection, whether from the national policy or from the green development of enterprises in the future, the improvement of power plant operation efficiency is imperative. Among them, improving the operation efficiency of thermal power plants is the top priority, and it is also an important link of national economic transformation. The design of electrical part is an important part of improving the operation efficiency of thermal power plants. 2x300MW thermal power plant is designed, including the power plant electrical main wiring design, plant power design, the main circuit of the power plant short-circuit calculation, and it choose the electrical stability and thermal stability of the better electrical equipment. The short circuit calculation of the main circuit of the power plant is carried out and preliminary planning of the secondary circuit scheme is made. A power plant with higher operating efficiency is designed. While improving the operation and economic efficiency of the power plant, it also ensures the reliability, stability and economy of the power plant.
Fault diagnosis of power electronic circuits using optimized BP neural networks
Authors: Jiang Deye , Huang Shuting , Guo Juan
Published: June 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 wordsThree-phase rectifiers have a wide range of applications in industrial production and daily life, and failure to diagnose their faults promptly may affect the reliability of the system operation, resulting in huge safety hazards and economic losses. Therefore, it is of great significance to conduct online fault diagnosis research on the power electronic circuits within three-phase rectifiers. An optimized BP neural network algorithm is proposed for diagnosing open-circuit faults of thyristors in three-phase rectifier circuits. The output voltage waveform characteristics of the circuit, when a fault occurs, are analyzed, and the corresponding output voltage peaks at the same cycle time when different tubes are damaged under the fifth fault type are used as fault feature vectors, and the fault information is input into the BP, optimized BP neural network for training, and the trained neural network is used for fault diagnosis. The fault diagnosis accuracy was obtained by comparing the network output with the desired output. The results of simulation experiments show that the optimized BP neural network can diagnose and analyze the faults of rectifier circuits more efficiently than directly applying the BP network for fault diagnosis.
Study on electromagnetic interference and shielding efficiency of power grid on-line elimination equipment
Authors: Fan Xuejun , Li Yang , Li Yongliang , Li Tong , Yin Lijie , Yan Keke
Published: June 2024

The robot-based automatic power grid defect elimination device represents the future direction of power grid inspection and defect elimination devices. However, the presence of strong electromagnetic interference in the vicinity of power grids poses potential risks to the application of automatic defect elimination devices. This study initially conducts theoretical analysis and calculations to analyse the spatial distribution of electromagnetic fields around 220kV 100MW high-voltage lines in a power grid. The results indicate that electric field intensity can exceed 70kV/m in areas near these high-voltage lines. Subsequently, electromagnetic fields within the operational range of the elimination device are simulated and analysed, leading to selection and optimization of shielding materials and structures. When non-metallic insulating materials are used, equipment is fully exposed to the power grid’s electromagnetic field, making internal devices susceptible to interference; however, employing metal aluminum materials achieves better shielding effects. A continuous metal shielding layer effectively shields against electric fields, while openings or gaps in the shell lead to deteriorated shielding performance. These findings demonstrate that appropriate selection of shielding materials and suitable structural design are crucial factors for achieving excellent shielding effects. To ensure both safety and efficient electromagnetic shielding, a multi-layer composite shielding structure is necessary for power grid elimination devices. Overall, these analysis results provide valuable guidance for designing, operating, and maintaining such devices.
Interoperability Study of Wireless Charging System Based on Generalized DD Coil
Authors: Pan Wenbin , Xie Ronghuan , Li Siqi , Lu Sizhao , Zhang Yiming
Published: June 2024

In recent years, with the popularization of intelligent auxiliary driving technology, wireless charging technology has garnered widespread attention due to its advantages in automation. However, there are still many issues to be resolved before the widespread adoption of wireless charging technology, with a key issue being the interoperability of coupling structures. To achieve adaptive interoperability, this paper proposes a wireless charging system based on dual generalized double-D (DD) coils. The system introduces a receiving structure composed of two generalized DD coils, which can naturally decouple the two coils. At the same time, the system topology employs a series connection of half-bridge rectifiers to enhance the system’s equivalent mutual inductance. Mathematical models and simulation verifications are provided. The proposed approach has been validated through simulations, showing that the system can automatically achieve interoperability with unipolar coils, DD coils, and quadrupolar coils.
Evidenz der modernen Diagnostik, der konservativen und chirurgischen
Therapie des sekundären Lymphödems
Authors: Will Patrick , Dragu Adrian , Zuther Joachim , Heil Jörg , Chang De-Hua , Traber Jürg , Hirche Christoph
Published: June 2024

Hintergrund Das sekundäre Lymphödem (SL) stellt eine der häufigsten und
zugleich bedeutsamsten Folgen und Komplikation der modernen onkologischen
Therapie dar. Obwohl eine gründliche Anamnese und körperlicher Untersuchung für
den Verdacht ausreichen, ist eine funktionelle Bildgebung des Lymphsystems für
die gezielte Diagnose und Ermittlung des Schweregrads essenziell. Hierfür wurden
in den letzten Jahren Techniken wie die MR-und die ICG-Lymphographie sowie die
ultrahochfrequenten Ultraschalluntersuchungen entwickelt und validiert. Die
selektive Anwendung dieser Techniken hat die individualisierte
Indikationsstellung und erfolgreiche stadienabhängige Behandlung mit den
(super-) mikrochirurgischen Techniken zur Wiederherstellung des regionalen
Lymphabflusses im Kontext einer intensivierten konservativen Therapie erst
möglich gemacht.

Methode Systematischer Review der Literatur zur Diagnose und Therapie des
SL mit anschließender Analyse und Klassifikation der Ergebnisse in Evidenzlevel
gemäß Oxford Centre for Evidence-Based Medicine sowie gemäß der GRADE Skala.

Ergebnisse Zur etablierten und validierten Diagnostik des SL gehören
Bildgebungen (ICG Fluoreszenzlymphographie, MR-Lymphographie und Tc-99
Funktionslymphszintigraphie) bei klinischem Verdacht und Hochrisikopatienten.
Komplexe physikalische Entstauungstherapie (KPE) ist der Physiotherapie oder
Kompression allein überlegen. Die (Super-)Mikrochirurgie des SL ermöglicht eine
postoperative Reduktion der Frequenz der KPE, Reduktion von Erysipelraten,
Volumenreduktion der lymphomatösen Extremität und bei prophylaktischer
Durchführung eine geringere Inzidenz des SL. Saugungsverfahren können
langfristig stabile Umfangsreduktionen und eine Verbesserung der Lebensqualität
erzeugen.

Schlussfolgerung Patienten mit SL profitieren von einer konservativen
Therapie mit regelmäßiger Reevaluation. Hochrisikopatienten für ein SL oder
Patienten mit einer klinischen Verschlechterung oder gleichbleibendem
Leidensdruck unter leitliniengerechter konservativer Therapie können von
(super-)mikrochirurgischen Therapien nach individualisierter Funktionsdiagnostik
des Lymphsystems profitieren. Exzisionale Dermolipektomien oder
Lympholiposuktionen sind für fortgeschrittene und therapierefraktäre Stadien
verfügbar und wirksam.
Heterozygous Prothrombin Mutation-Associated Thrombophilia
Authors: Wu Xi , Li Lei , Lu Zhengjing , Hu Xiaobo , Lu Yeling , Liu Yu , Xu Guanqun , Ding Qiulan , Wang Xuefeng , Wu Wenman , Jin Peipei , Dai Jing
Published: June 2024

Background Venous thromboembolism (VTE) is predisposed by thrombotic mutations in patients with hereditary thrombophilia. Although prothrombin deficiencies caused by homozygous or compound heterozygous mutations are associated with bleeding diathesis, rare cases have shown a correlation between heterozygous prothrombin mutations and thrombosis.

Materials and Methods We surveyed genetic variants involved in thrombosis and hemostasis in 347 patients with unprovoked VTE or having a positive family history of thrombosis. For patients identified with heterozygous prothrombin mutations, we conducted family investigations and performed a thrombin generation test (TGT) to elucidate the thrombotic risk. Novel mutants were expressed and subjected to functional assays to clarify the underlying thrombotic mechanisms.

Results Heterozygous prothrombin mutations were identified in 3.5% of patients (12/347), including three novel mutations Phe382Ser, Phe382Leu, and Asp597Tyr found in one patient each, as well as previously reported Arg541Trp mutation in four patients and Arg596Gln mutation in five patients. A total of 42 mutation carriers were identified within the 12 pedigrees, among whom 64.3% (27/42) had experienced thrombotic events. TGT results demonstrated hypercoagulability for carriers of the five mutations, with Arg596Gln showing the highest thrombin generation potential followed by Arg541Trp. The Phe382-associated mutations severely impaired thrombomodulin-binding ability of thrombin, resulting in obviously reduced protein C (PC) activation. The Asp597Tyr mutation exhibited a mild reduction in both inactivation by antithrombin and PC activation reactions.

Conclusion The presence of heterozygous prothrombin mutations represents a potential genetic predisposition for VTE. All thrombosis-associated mutations potentiate coagulation activity by either conferring antithrombin resistance and/or impairing PC pathway activity.
Gram-Scale Synthesis of (±)-Tylophorine
Authors: Reddy D. Srinivasa , Masal Dattatraya P.
Published: June 2024

We report a practical scalable synthesis of the natural product (±)-tylophorine by using an operationally simple protecting-group-free route from readily accessible starting materials. Synthesis of a cyclic N-acetyl diester compound through cyclization, followed by two key steps (decarboxylation and a Clemmensen reduction), provides access to the target molecule.
Positional Relationship between Two Microcatheters according to the Navigation Sequence within the Curved Vessel in Neuroendovascular Procedures
Authors: Ohshima Tomotaka , Koiwai Megumi , Matsuo Naoki , Miyachi Shigeru
Published: June 2024

Objective In neuroendovascular treatment, there are many opportunities to guide multiple catheters into the intracranial blood vessels. We report the relationship between two microcatheters according to the guiding order with experimental in vitro studies.

Materials and Methods We hypothesize that in a bent blood vessel such as a paraclinoid region of the internal carotid artery, the catheter that was first guided tended to pass through the inside, and the catheter that was guided later tended to pass through the outside. The in vitro verification was performed using a microcatheter and a balloon catheter in a silicone vascular aneurysmal model.

Results As a result, it was found that the two catheters were arranged according to our hypothesis. This finding was also observed during the actual operation of balloon-assisted coil embolization.

Conclusion The positional relationship between the two catheters according to the navigation order is very important, in particular during balloon-assisted coiling and stent-assisted coiling via a jailed microcatheter.
Stress-Induced Hypercoagulability: Insights from Epidemiological and Mechanistic Studies, and Clinical Integration
Authors: von Känel Roland
Published: June 2024

By integrating findings from comprehensive reviews, meta-analyses, and cutting-edge genetic studies, this article illuminates the significance of stress-induced hypercoagulability in clinical medicine. In particular, the findings from numerous prospective cohort studies indicate that stress and hemostatic factors of a hypercoagulable state are associated with increased incident risk and poor prognosis for atherosclerotic cardiovascular disease and venous thromboembolism. Mendelian randomization studies suggest that these associations are partially causal. The review synthesizes extensive research on the link between acute and chronic stress and hypercoagulability, outlining a potential pathway from stress to thrombosis risk. Consistent with the allostatic load concept, acute stress-induced hypercoagulability, initially adaptive, can turn maladaptive under chronic stress or excessive acute stress, leading to arterial or venous thrombotic events. Individuals with predisposing factors, including atherosclerosis, thrombophilia, or immobilization, may exhibit an increased risk of thrombotic disease during stress. Contextual sociodemographic characteristics, the stress experience, and coping resources additionally modulate the extent of stress-induced hypercoagulability. Research into the neuroendocrine, cellular, and molecular bases reveals how stress influences platelet activation coagulation and fibrinolysis. The activation of the sympathetic nervous system and the hypothalamic–pituitary–adrenal axis, along with vagal withdrawal, and the effects of catecholamines, cortisol, and vasopressin, are the central mechanisms involved. Hemoconcentration, inflammation, endothelial dysfunction, and thrombopoiesis additionally contribute to stress-induced hypercoagulability. Further research is needed to prove a causal link between chronic stress and hypercoagulability. This includes exploring its implications for the prevention and management of thrombotic diseases in stressed individuals, with a focus on developing effective psychosocial and pharmacological interventions.
Emerging Trends in Neuropalliative Care: A Palliative Approach to Epilepsy and Seizure Management in Adults
Authors: Willert Anna-Christin , Kowski Alexander Bernhard
Published: June 2024

Management of severe (drug-resistant) epilepsy and epilepsy in other serious illnesses is multidimensional and requires consideration of both physical symptoms and psychosocial distress that require individualized treatment. Palliative care offers a holistic approach to disease that focuses on all dimensions of suffering to maintain quality of life. Integration of a palliative care mind- and skillset in the management of severe epilepsy and epilepsy in other serious illnesses can provide person-centered care and support for families and caregivers.
Colorectal Cancer and Inflammatory Bowel Disease
Authors: Gamaleldin Maysoon , Qazi Taha , Hull Tracy
Published: June 2024

Colorectal cancer (CRC) in patients with ulcerative colitis (UC) and Crohn's disease accounts for ∼5% of all cases of CRC. Although it only accounts for a fraction of CRC cases, inflammatory bowel disease (IBD)-related CRC is a serious consequence of chronic inflammation that needs attention. There is a better understanding today about the pathogenesis contributing to IBD-CRC and the role of genetics and gut microbiota. Guidelines recommend timely screening and surveillance of UC and Crohn's patients, and it is usually timed from the initial diagnosis. This helps with early detection of dysplasia and CRC in this subset of patients, thus allowing for earlier intervention. However, dysplasia is not always easy to discern and management of CRC in each patient may differ. A multidisciplinary approach should be adopted in managing CRC in IBD. Although the oncologic principles of managing sporadic CRC and IBD-CRC are the same, surgical resection should be tailored to each patient.
Design of tunable pneumatic metamaterials for low-frequency vibration control
Authors: Zhang Yingjie , Xu Wei , Chen Zhimin , Fu Junqiang , Yin Lihang
Published: June 2024

For addressing the limitations of traditional elastic metamaterials in opening wide bandgaps below 100 Hz, a tunable pneumatic metamaterial plate with airbag local resonators is proposed. Utilizing the characteristics of airbags, such as small volume, large load-bearing capacity, easy stiffness adjustment, and the ability to provide multi-directional restoring forces, a structured low-stiffness local resonator with a certain load-bearing capacity is designed. By varying the gauge pressure of the airbag, the bandgap can be moved toward lower frequencies, thereby achieving a broad low-frequency vibration suppression capability for various wave propagations. The low-frequency vibration bandgap characteristics of the tunable pneumatic metamaterial are analyzed and verified by applying the finite element method. The results illustrate that this tunable pneumatic metamaterial can attenuate bending waves in the range of 22–121 Hz by adjusting the air pressure. Moreover, increasing the gauge pressure will not only shift the complete bandgap toward lower frequencies but also significantly expand the bandwidth of the complete bandgap. For instance, increasing the gauge pressure from 0 to 50 kPa reduces the opening frequency of the complete bandgap from 36 to 22 Hz while enhancing the relative bandwidth from 0.52 to 0.85. Extending from this, a parametric study was conducted to examine the impact of the structural parameters of airbag-type resonant units on bandgap evolution, summarizing the general principles for achieving wide low-frequency bandgaps. Finally, the bandgap characteristics of the tunable pneumatic metamaterial are confirmed through the frequency response function of a finite periodic structure.
Exploring equity of care for Aboriginal and Torres Strait Islander peoples within the state-wide Musculoskeletal Physiotherapy Screening Clinic and Multi-disciplinary Service in Queensland Health
Authors: McDougall Alistair , Raymer Maree , Window Peter , Cottrell Michelle , Nelson Curtley , Francia Carl , Watson Eliza , O’Leary Shaun
Published: June 2024

Objective This study aimed to explore equity of care for Aboriginal and Torres Strait Islander peoples compared to non-Indigenous Australians within a Queensland-wide musculoskeletal service. Method The service database was analysed between July 2018 and April 2022 across 18 Queensland Health facilities. Representation of Aboriginal and Torres Strait Islander peoples within the service’s patient population was first explored. Second, service and patient-related characteristics and outcomes between Aboriginal and Torres Strait Islander patients and non-Indigenous patients undergoing an episode of care in the service were compared using analysis of variance and chi-squared tests. Results A greater proportion of Aboriginal and Torres Strait Islander peoples (4.34%) were represented within the service’s patient population than in the general population (3.61%) state-wide. Aboriginal and Torres Strait Islander patients presented with a generally higher severity of clinical presentation across measures at initial consult. Very similar proportions of Aboriginal and Torres Strait Islander (63.2%) and non-Indigenous (64.3%) patients reported clinically meaningful treatment benefits. While a higher proportion of Aboriginal and Torres Strait Islander patients (69.7%) were discharged from the service without requiring specialist review compared to non-Indigenous patients (65.6%), Aboriginal and Torres Strait Islander patients had higher rates of discharge due to non-attendance (20.8%) when compared to non-Indigenous (10.6%) patients (P < 0.01). Conclusions Disparity in care retention for Aboriginal and Torres Strait Islander patients compared to non-Indigenous patients was observed within the musculoskeletal service. Consultation with Aboriginal and Torres Strait Islander communities is needed to address access barriers once in the service to guide service improvement.
Citizen science delivers high-value biosecurity surveillance and reporting capability
Authors: Roger Erin , Turley Andrew , Waite Callum , Balasubramaniam Shandiya , Slatyer Cameron , Andrew Pearce J.
Published: June 2024

Context Early surveillance and the detection of incursions of species of biosecurity concern are a crucial component of an effective biosecurity system. Citizen science represents an opportunity to engage communities in biosecurity, and to provide mechanisms for citizen scientists to contribute to both monitoring the spread of species already present in country, and reporting new incursions. Aims To present an example of how citizen science is being used for environmental biosecurity surveillance in Australia and showcase the value of large data services such as the Atlas of Living Australia (ALA), as a connector between citizen science and management. Methods We detail how the alert email system was set up, using a bespoke solution implemented in the R programming language. The system works by querying the ALA database for species that match lists provided by management authorities. Alerts can be sent out at national, state/territory and local government scales, as well as defined spatial areas such as national park estates. Key results Twelve months in, the top source for alerts comes from iNaturalist (a popular global biodiversity citizen-science platform), with other contributions from a set of biodiversity-reporting applications. Over a 12-month period, the alerts service has provided notifications for over 150 species, including the first public record of an invasive species in Australia. Conclusions Systems such as the Biosecurity Alerts Service, provide impact through the connection between communities and decision-making. Implications Our findings showed how the advancement of citizen science is interconnected with the advancement of research infrastructure and will ultimately lead to greater scientific and management value of citizen-science data.
Machine learning in biological physics: From biomolecular prediction to design
Authors: Martin Jonathan , Lequerica Mateos Marcos , Onuchic José N. , Coluzza Ivan , Morcos Faruck
Published: June 2024

Machine learning has been proposed as an alternative to theoretical modeling when dealing with complex problems in biological physics. However, in this perspective, we argue that a more successful approach is a proper combination of these two methodologies. We discuss how ideas coming from physical modeling neuronal processing led to early formulations of computational neural networks, e.g., Hopfield networks. We then show how modern learning approaches like Potts models, Boltzmann machines, and the transformer architecture are related to each other, specifically, through a shared energy representation. We summarize recent efforts to establish these connections and provide examples on how each of these formulations integrating physical modeling and machine learning have been successful in tackling recent problems in biomolecular structure, dynamics, function, evolution, and design. Instances include protein structure prediction; improvement in computational complexity and accuracy of molecular dynamics simulations; better inference of the effects of mutations in proteins leading to improved evolutionary modeling and finally how machine learning is revolutionizing protein engineering and design. Going beyond naturally existing protein sequences, a connection to protein design is discussed where synthetic sequences are able to fold to naturally occurring motifs driven by a model rooted in physical principles. We show that this model is “learnable” and propose its future use in the generation of unique sequences that can fold into a target structure.
Explaining neural scaling laws
Authors: Bahri Yasaman , Dyer Ethan , Kaplan Jared , Lee Jaehoon , Sharma Utkarsh
Published: June 2024

The population loss of trained deep neural networks often follows precise power-law scaling relations with either the size of the training dataset or the number of parameters in the network. We propose a theory that explains the origins of and connects these scaling laws. We identify variance-limited and resolution-limited scaling behavior for both dataset and model size, for a total of four scaling regimes. The variance-limited scaling follows simply from the existence of a well-behaved infinite data or infinite width limit, while the resolution-limited regime can be explained by positing that models are effectively resolving a smooth data manifold. In the large width limit, this can be equivalently obtained from the spectrum of certain kernels, and we present evidence that large width and large dataset resolution-limited scaling exponents are related by a duality. We exhibit all four scaling regimes in the controlled setting of large random feature and pretrained models and test the predictions empirically on a range of standard architectures and datasets. We also observe several empirical relationships between datasets and scaling exponents under modifications of task and architecture aspect ratio. Our work provides a taxonomy for classifying different scaling regimes, underscores that there can be different mechanisms driving improvements in loss, and lends insight into the microscopic origin and relationships between scaling exponents.
APACE: AlphaFold2 and advanced computing as a service for accelerated discovery in biophysics
Authors: Park Hyun , Patel Parth , Haas Roland , Huerta E. A.
Published: June 2024

The prediction of protein 3D structure from amino acid sequence is a computational grand challenge in biophysics and plays a key role in robust protein structure prediction algorithms, from drug discovery to genome interpretation. The advent of AI models, such as AlphaFold, is revolutionizing applications that depend on robust protein structure prediction algorithms. To maximize the impact, and ease the usability, of these AI tools we introduce APACE, AlphaFold2 and advanced computing as a service, a computational framework that effectively handles this AI model and its TB-size database to conduct accelerated protein structure prediction analyses in modern supercomputing environments. We deployed APACE in the Delta and Polaris supercomputers and quantified its performance for accurate protein structure predictions using four exemplar proteins: 6AWO, 6OAN, 7MEZ, and 6D6U. Using up to 300 ensembles, distributed across 200 NVIDIA A100 GPUs, we found that APACE is up to two orders of magnitude faster than off-the-self AlphaFold2 implementations, reducing time-to-solution from weeks to minutes. This computational approach may be readily linked with robotics laboratories to automate and accelerate scientific discovery.
Quantifying NOxpoint sources with Landsat and Sentinel-2 satellite observations of NO2plumes
Authors: Varon Daniel J. , Jervis Dylan , Pandey Sudhanshu , Gallardo Sebastian L. , Balasus Nicholas , Yang Laura Hyesung , Jacob Daniel J.
Published: June 2024

We show that the Landsat and Sentinel-2 satellites can detect NO2plumes from large point sources at 10 to 60 m pixel resolution in their blue and ultrablue bands. We use the resulting NO2plume imagery to quantify nitrogen oxides (NOx) emission rates for several power plants in Saudi Arabia and the United States, including a 13-y analysis of 132 Landsat plumes from Riyadh power plant 9 from 2009 through 2021. NO2in the plumes initially increases with distance from the source, likely reflecting recovery from ozone titration. The fine pixel resolutions of Landsat and Sentinel-2 enable separation of individual point sources and stacks, including in urban background, and the long records enable examination of multidecadal emission trends. Our inferred NOxemission rates are consistent with previous estimates to within a precision of about 30%. Sources down to ~500 kg h−1can be detected over bright, quasi-homogeneous surfaces. The 2009 to 2021 data for Riyadh power plant 9 show a strong summer peak in emissions, consistent with increased power demand for air conditioning, and a marginal slow decrease following the introduction of Saudi Arabia’s Ambient Air Standard 2012.
Carbonate uranium isotopes record global expansion of marine anoxia during the Toarcian Oceanic Anoxic Event
Authors: Remírez Mariano N. , Gilleaudeau Geoffrey J. , Gan Tian , Kipp Michael A. , Tissot François L. H. , Kaufman Alan J. , Parente Mariano
Published: June 2024

The Toarcian Oceanic Anoxic Event (T-OAE; ~183 Mya) was a globally significant carbon-cycle perturbation linked to widespread deposition of organic-rich sediments, massive volcanic CO
2
release, marine faunal extinction, sea-level rise, a crisis in carbonate production related to ocean acidification, and elevated seawater temperatures. Despite recognition of the T-OAE as a potential analog for future ocean deoxygenation, current knowledge on the severity of global ocean anoxia is limited largely to studies of the trace element and isotopic composition of black shales, which are commonly affected by local processes. Here, we present the first carbonate-based uranium isotope (δ
238
U) record of the T-OAE from open marine platform limestones of the southeastern Tethys Ocean as a proxy for global seawater redox conditions. A significant negative δ
238
U excursion (~0.4‰) is recorded just prior to the onset of the negative carbon isotope excursion comprised within the T-OAE, followed by a long-lived recovery of δ
238
U values, thus confirming that the T-OAE represents a global expansion of marine anoxia. Using a Bayesian inverse isotopic mass balance model, we estimate that anoxic waters covered ~6 to 8% of the global seafloor during the peak of the T-OAE, which represents 28 to 38 times the extent of anoxia in the modern ocean. These data, combined with δ
238
U-based estimates of seafloor anoxic area for other CO
2
-driven Phanerozoic OAEs, suggest a common response of ocean anoxia to carbon release, thus improving prediction of future anthropogenically induced ocean deoxygenation.
Summary of the 4th IAHR Asian working group symposium on hydraulic machinery and systems
Authors: Zhengwei Wang
Published: June 2024

1. Background

The international Association for Hydro-Environment Engineering and Research (IAHR), founded in 1935, one of the IAHR Committee is the Hydraulic Machinery and Systems, which deals with the advancement of technology associated with the understanding of steady and unsteady flow characteristics in hydraulic machinery and conduit systems connected to, and the main emphasis is to promote interaction between the machine designers, machine users, the academic communities, and the communities at large.

To meet its objectives, the Committee focuses on the best possible exchange of technical knowledge by arranging a Committee Symposium every second year. The symposiums are designed to attract scientists and engineers from industries, universities, consultants and users of hydraulic machinery. In addition, the Committee established “Asian Working Group” specially to promote the exchange and cooperation of hydraulic machinery industry in Asian countries.

In recent years, water conservancy and hydropower in Asia have been developing dramatically. Hydraulic machinery like pump, pump turbines etc., are widely used in project construction. There are plentiful scientific and technical payoffs achieved within the related researches. The "Asian Working Group" has held three symposiums on hydraulic machinery and systems, which are: IAHR 2017 Asia Beijing, IAHR 2019 Asia Busan, IAHR 2021 Asia Nepal. And all conference proceedings have been published in IOP. After the 4th IAHR Asian Working Group Symposium on Hydraulic Machinery and Systems (hereinafter referred to as IAHR 2023 Asia Kashgar) following its convention, the conference proceedings will be published in IOP.

List of Scope, Record, Appendices A: Organization, Appendices B: Committee members, Appendices C: Excellent papers are available in this pdf.
Consideration on setting conditions of the upstream surge chamber in the water transmission system of pumped storage power station
Authors: Zhao Long , Wang Jue , Cheng Yanan
Published: June 2024

Through the investigation of more than ten domestic pumped storage power stations that have been built or are under construction, the actual setting of the upstream surge chamber is obtained. The traditional upstream surge chamber setting conditions are derived from conventional hydropower station construction experience and subsequent derivations. Combined with the load shedding test and unit design parameters, the practical application of the upstream surge chamber setting conditions is evaluated, and the relevant construction experience of the pumped storage power station is summarized. The analysis and research results of the installation conditions of the upstream surge chamber are presented.
Vortices Evolution Characteristics and Pressure Pulsations of Variable-speed Francis Turbine
Authors: Zhang Changbing , Wang Chongxun , Zhang Yongqi , Wang Wenquan , Liu Demin , Shen Chunhe
Published: June 2024

The stability of Francis turbine under low load conditions has become the focus in the power grid dominated by variable renewable energy. In this paper, the variable-speed approach is used to explore the operating characteristics of the Francis turbine, the RANS/LES hybrid turbulent model is adopted to investigate the fluid structure evolution process, and using the Q-criterion depicts the vortex cores. The results show that the numerical simulation agrees well with the experimental data acquired from the model test. It is found that the variable-speed operation can effectively eliminate the vortex ropes in the draft tube. Unexpectedly, the vortices in the runner will evolve from the separated vortices at the runner outlet for the fixed-speed Francis turbine to the inter-blade vortices at the runner inlet for the variable-speed Francis turbine in the case of small guide vane opening. It is concluded that the optimum operating range of a variable-speed Francis turbine (VSFT) should be within ±30% rated speed and 60% to 100% opening, and the pressure pulsation coefficient in the draft tube can be reduced from 7% to 1% at minimum water head, the output and efficiency of the turbine are increased by about 30% and 10% respectively.
Study on erosion characteristics of turbine in sediment-laden river
Authors: Wei Xin-Yu , Yang Jia-Fu , Pei Jun-Xian , Xie Guo , Wang Wen-Quan
Published: June 2024

Sediment erosion of hydro turbines is prevalent and serious in the mountain river region. The effect of operating head and particle diameter on sediment erosion was investigated in this paper. A Eulerian-Lagrangian approach was applied to numerically simulate the solid-liquid flow in a Francis turbine under the minimum, design and maximum heads. Five typical diameters (0.1, 0.3, 0.5, 0.7, 0.9 mm) were firstly determined based on field measurements at a hydropower station. After tracking the trajectories of sediment particles, McLaury model was selected to predict the erosion rate. The results show that sediment erosion regions of runner blades are similar under different operating heads, while the sediment erosion rates amplify significantly with the increase of operating heads. The erosion rate of blade suction side is significantly higher than that of pressure side because of the effect of inter-blade vortices between runner blades. Sediment diameters also play an important role in accelerating erosion rate, which indicate that setting up sedimentation tanks to settle large-size sediment particles is a powerful method to alleviate sediment erosion. This study can provide a reference for erosion estimation and operational maintenance of hydro turbines in mountain river region.
Optimization design and test verification of guide vanes for a fish-friendly Francis turbine
Authors: Yi Y L , Wang W P , Li T Y , Gao Z X , Lu L , He L
Published: June 2024

Fish will die from the strike of the narrow flow passages when passage through traditional Francis turbines, in order to obtain excellent hydraulic performance as well as improve survival rate of fish, the guide vanes of fish-friendly Francis turbine model is taken as the research object. CFD method is adopted to predict the flow field characteristics of the turbine, meanwhile, the model test is carried out to validate the reliability of the numerical simulation. The results showed that, for plan A with 20 guide vanes, the internal flow of the turbine is more uniform and the pressure between the guide vanes is more symmetric in the circumferential direction, the turbine has better performance in the efficiency and operational stability.
A Comparative Analysis on the Efficient and Stability Cam Curve of a 200 MW Kaplan Turbine Unit
Authors: Zhao W , Xia M
Published: June 2024

In this paper, the cam curve selection methodology of the largest Kaplan turbine unit is discussed. The cam curves generated by both index test and stability test are presented and analysed. To compare with the current cam curve running the power plant, the efficiency cam curve increases the unit efficiency by around 1%; while the stability cam curve has decreased the vibration with a small cost of output (less than 2%). The research gives the operators of hydraulic turbine unit a guidance of selecting the optimal operation strategy.
Evaluation of Forces on the Needle for Regulation of Pelton Turbine Injector
Authors: Khan F , Kumar A , Staubli T
Published: June 2024

In hydropower plants, the Pelton turbine is a commonly used hydraulic turbine where flow is regulated with a dual mechanism of needle and deflector. The needle is controlled by a servomotor and governor system, where the flow rate varies by adjusting the needle strokes. The needle is operated under the hydraulic force caused by the high-water pressure inside the injector acting on the needle surface. The objective of computing the force balance in a Pelton injector is to determine the force to be supplied by the servomotor. The closing trend is crucial to design the injector for safe operation during an emergency. In this study, the function of the needle and nozzle curve generalizes the variable needle surface area, allowing the geometric properties of the nozzle and needle to be suitable for the needle force evaluation. The single-axis force transducer, which is mounted on the needle rod, has been used in the experimental method for determining the needle forces. The experimental findings are compared to analytical calculations and serve as validation for the accuracy and reliability of the computed results obtained through the analytical approach.
Investigation on hydraulic loss characteristic of Kaplan turbines based on entropy generation theory
Authors: Liu Boxing , Feng Jianjun , Wang Zhaoning , Guan Ziwu , Zhu Guojun
Published: June 2024

In this paper, the hydraulic losses of a Kaplan turbine under optimal and rated operating conditions are investigated through the theory of entropy generation. The results show that hydraulic loss values calculated using pressure drop and entropy generation theory are similar. The hydraulic losses are mainly concentrated in runner and draft tube. However, when the operation condition of Kaplan turbines deviates from the optimal condition, the proportion of hydraulic loss in draft tube increases. The hydraulic loss in draft tube is mainly composed of entropy generation caused by turbulence fluctuation, which is the result of unstable flow induced by vortex rope. The hydraulic losses of other parts are mainly composed of entropy production caused by wall shear. The high entropy production of the runner concentrated on the shroud, hub, blade surface, and blade trailing edge, while entropy production caused by wall shear is concentrated on blade pressure surface and shroud near blades when the turbine strays from optimal operating condition.
Numerical study on the influence of the bucket offset angle on the flow field of Pelton turbines with six-nozzles
Authors: Wang Xiao-Dong , Wang Wen-Quan , Yang Jia-Fu , Zhang Chang-Bing , Cao Wen-Zhe
Published: June 2024

Pelton turbines are emerging as a primary means for exploiting ultra-high water head resources. The hydraulic performance of a Pelton turbine is determined by the design of its runner/bucket. Among the critical parameters that affect the hydraulic performance of multi-nozzle Pelton turbines is the bucket offset angle (α). To investigate the influence of bucket offset angle on the flow field of Pelton turbines with six nozzles, this study conducted unsteady numerical simulations of gas-liquid two-phase flow for various bucket offset angles, employing the VOF multiphase model combined with the SST k-ω turbulence model. The results reveal that as the bucket offset angle increases, the axial width of the water sheet formed by the current jet progressively widens, with a tendency to catch up with the water film formed by the previous jet during the torque rising stage. Moreover, the increased bucket offset angle causes the water sheet to distribute more closely to the bucket cutout, raising the risk of leakage from the cutout. Notably, at α= 10°, some of the water sheet has already flowed out of the cutout and collided with the subsequent jet.
Understanding the modal response of a full-scale 200 MW Francis turbine runner
Authors: Roig R , Sánchez-Botello X , Wiborg E , Escaler X
Published: June 2024

Under off-design operating conditions, the flow through hydraulic turbines presents fluidodynamic disturbances that can excite a natural frequency and provoke a resonance. Determining with precision the modal properties of the runner is thus of paramount importance. The current article presents an experimental modal analysis of a 200 MW Francis runner located in the Oksla hydropower plant in Norway. During the test, the runner was bolted to the still shaft supported by the bearings and an instrumented hammer was used to excite it. Then, several accelerometers were fixed to the band and blades to measure its modal response. Subsequently, frequency response functions between the hammer impulsive force and the vibration acceleration signals were computed to determine the natural frequencies and mode shapes of the Oksla runner. Even though the main modes corresponded to nodal diameters, other more complex modes were also identified on the blades. Nevertheless, a significant disagreement was found when comparing the experimental results with the numerical predictions from a similar but not exactly equal Francis geometry, which confirms the need to scan the actual shapes and dimensions of the runner in order to obtain reliable simulated results.
Research on the Analysis Method of Measured Pressure Data during the Transient Process of Load Rejection in Hydropower Stations
Authors: Fan Jiayi , Ma Yanmei , Zhang Jian , Du Xuan , Lin Fangzhou
Published: June 2024

This paper proposes a method to analyze the measured pressure data in the transition process of hydropower station. The method first separates the measured pressure data to the mean pressure and pressure fluctuation data, then divides the pressure fluctuation data into different time domain grids, and performs the confidence probability processing on the pressure fluctuation data in each time grid, and finally obtains the credible measured pressure data of transient process. In this paper, the specific implementation steps of the method are introduced by taking the results of a load rejection test of a pumped storage power station as an example.
Study on On-Line Monitoring Technique and Case Study of Pump-Storage Turbine Headcover Bolt Axial Load
Authors: Zhang Meng , Wang Qifei , Xia Yushu , Tang Lei
Published: June 2024

This work is based on the principle of acoustoelasticity of metallic materials, systematically studied the headcover bolt axial load on-line monitoring, the method of calibration technique based on ultrasound transit time difference and temperature, and case study. By analytical calculation, test, and finite element analysis (FEA), derived the coefficients of acoustoelasticity and temperature, and investigated the bolt thermal stress and the temperature correction method. A scheme for the on-line monitoring of pump-storage turbine headcover bolt axial load is given, providing a reference for important bolt axial load monitoring of hydropower units.
Study on sensitivity evaluation of conveyance system to unit hydraulic transient characteristics in pumped storage plant
Authors: Zhou Shun , Fan Jiayi , Zhang Jian , Ma Yanmei , Chen Taiping
Published: June 2024

The minimum pressure of draft tube inlet under the condition of successive load rejection is the key factor restricting the unit hydraulic transient characteristics in pumped storage plant, and the layout of conveyance system is an important factor affecting the unit hydraulic transient characteristics. To explore the influence of the conveyance system layout on the unit hydraulic transient characteristics, the author proposed a new method to evaluate the sensitivity of conveyance system layout to the unit hydraulic transient characteristics. Furthermore, the simulation analysis of two case power stations is used to verify the new method.