bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical Optimization of Gravitational Water Vortex Turbine using Computational Flow Analysis
Authors: Edirisinghe D S , Yang H S , Kim B H , Kim C G , Gunawardane S D G S P , Lee Y H 
Published: June 2022

Abstract
Gravitational Water Vortex Power (GWVP) plants are considered one of the most favourable micro-hydro extraction methods suitable for rural communities in mountain areas. Many researchers have focused on enhancing the performance of GWVP plants since it is less efficient than other commercial hydro turbines. This study mainly focuses on optimization of vortex turbine situated in conical vortex basin using the computational fluid dynamic (CFD) analysis. The basic turbine blade design was modified with inclination, height, vertical twist, and horizontal curvature. CFD results were analysed at each step concerning air-water interface, pressure, and velocity while identifying the relationship of flow behaviour with performance. A similar blade inclination with the conical basin enhanced performance, and the increasing of blade height also showed good performance. Vertical twist and horizontal curvature were investigated separately, and the horizontal curvature blade showed slightly better performance than the vertical twisted blade recording the highest efficiency as 40.4%.
Comparative CFD analysis of Kali-Gandaki “A” Francis runner with runner generated from Bovet method
Authors: Karki S , Satyal S , Rijal KP , Koirala P , Adhikari N 
Published: June 2022

Abstract
Kali-Gandaki “A” is a medium head Francis turbine site located in Syangja District of Nepal. The dimensionless specific speed number for this site falls in the range suitable for generating meridional profile from Bovet Method. In this paper, the meridional profile of the actual runner currently deployed is extracted from CAD drawings and another meridional profile is generated using empirical relations of the Bovet Method. Meridional area of profile from Bovet Method is significantly larger in comparison to CAD-based profile. Both of these profiles are imported in commercial software ANSYS BLADEGEN, using linear blade angle distribution with no lean runner’s 3D model is generated for both cases. Both designs are meshed in Turbo-Grid and simulated in ANSYS CFX with k-epsilon turbulence model. Simulation reveals the CAD-based runner has 91.11% efficiency in comparison to Bovet based runner which has only 85.6% efficiency. Also, Simulation results reveal Bovet-based runner is more susceptible towards erosion and cavitation which suggests there is room for improvement and optimization of design obtained from Bovet Method.
Recent developments in the optimization of Francis turbine components for minimizing sediment erosion
Authors: Lama Ram , Gautam Saroj , Neopane Hari Prasad , Thapa Biraj Singh , Chitrakar Sailesh , Dahlhaug Ole Gunnar 
Published: June 2022

Abstract
Sediment erosion in hydraulic turbines are severe in case of hydropower plants operating in Himalayan Rivers of Nepal. Francis turbine components are heavily eroded while hard particles as quartz flow along with water through the water conduit in power plant. In Francis turbines, the runner blades where significant portion of hydraulic energy converts in mechanical energy are heavily eroded. This is due to complexity in fluid flow while operated at different operating conditions with sediment contained water. Conventional design of Francis turbines has overlooked on the effects of sediment erosion while considering optimum efficiency at all operating conditions. This paper examines multi-objective optimization of a reference 92 kW model Francis runner for minimizing sediment erosion effects. The model turbine studied in this paper is a scale down model turbine of Jhimruk Hydropower Plant, Nepal that is severely affected by sediment erosion. It was found that sediment erosion was reduced significantly at part load, full load and best efficiency point with improvement in hydraulic performance for model turbine utilizing multi-objective optimization on runner blade design.
Influence of Rotor Dimple Geometry on Cavitation Characteristics of Rotational Cavitation Generator
Authors: Jia Y F , Xie C , Zhang W , Meng G Q Q G 
Published: June 2022

Abstract
The current investigation is aimed to simulate the internal flows in a rotational cavitation generator with a rotor and a stator by using the RNG k-ε turbulence model and Zwart-Gerber-Belamri cavitation model. The design of the cavitation generator is that the rotor is provided with surface dimples. A detailed analysis of the pressure distribution, vapor volume fraction distribution and velocity distribution in cavitation generator with five different structures (5 different depth of rotor dimples h=25mm, 35mm, 45mm, 55mm, 65mm) under the same operation condition, is presented. The simulation results demonstrate that the characteristics of velocity and pressure area and cavitaion area are quite different based on the magnitude of the dimple depth of the rotor. It is showed that with the rotor dimple depth increase, cavitation area appears in the low pressures area at the bottom of the dimple and expands rapidly inside dimple; near the top of the dimple, the pressure gradient becomes larger and larger and velocity gradient changes dramatically; which induces strong flow disturbance at the top of the dimple and on the surface of the rotor, the water vapor exchange effect is enhancing, and the cavitation effect is getting stronger and stronger. The cavitation effect of the rotational hydrodynamic cavitation generator can be enhanced by increasing the depth of the rotor dimple.
Sediment erosion in the labyrinths of Francis turbine: A numerical study
Authors: Gautam Saroj , Acharya Nirmal , Chitrakar Sailesh , Neopane Hari Prasad , Iliev Igor , Dahlhaug Ole Gunnar 
Published: June 2022

Abstract
Development of new hydropower projects in Himalayan regions aims for the efficient performance of the turbine with lesser operation and maintenance cost. Over the past two decades, significant efforts have been made to improve the sediment handling capabilities by the turbine components. In the case of Francis turbines, the design of guide vanes and runner blades were focused on the past to improve the sediment resistivity. However, other components of these machines were not studied from the perspective of sediment erosion. The present work aims to study the sediment erosion in the labyrinth sealings of a prototype Francis turbine, having serious erosion problems. Upper labyrinth sealing and bottom labyrinth sealing were modelled by developing a reference case and the erosion wear in these regions were examined numerically. The flow leaving the gap between stationary guide vanes and the runner enters the top and bottom labyrinth seals. While sediment flows along with the clean water these seals get heavily eroded. The results from the numerical investigation show a distinct pattern of erosion locations in the labyrinth sealings that is similar to the field observation.
Wear in centrifugal pumps with causes, effects and remedies: A Review
Authors: Pokharel Nischal , Ghimire Amul , Thapa Bhola , Thapa Biraj Singh 
Published: June 2022

Abstract
Pumps are widely used machinery in various applications. Mostly now, a day in importance is seen from household applications to different industrial level. Various types of pumps are available in the market according to their applications and centrifugal pumps are one of most common types among them. In the course of time, pumps faces various problems and repairing is required. Among them wear is one of the most common problem for reduction in pump performance. Cavitation, corrosion, erosion, fatigue are the common wear mechanisms faced by the centrifugal pumps. In order to minimize such problems frequent maintenance strategies are required. Various researchers have purposed different methodologies. Material properties, coatings in design and optimizing hydraulic and mechanical design for such challenges has been now a major topic of research. In this study, the different wear mechanisms and their causes with reference to various research paper is presented. Different effects for such problems is highlighted. Finally, new emerging technology developed by various researchers for minimizing such wear challenges are discussed.
Research and Analysis on Model measurement and Prototype Operation of large-scale Kaplan turbine
Authors: ZHOU Jingming , ZHOU Xuezhi , XIA Ming , LUO Hongyun , WU Yibin , WANG Zhengwei 
Published: June 2022

Abstract
Prototype research of hydraulic turbine, as most important one of the three major methods in the research region, is different from theoretical analysis and model measurement. Since the operation conditions of the prototype turbine test are numerous and corresponding to reality, considering the complexity of the medium characteristics, operation parameters are difficult to predict accurately. Taking a giant Kaplan turbine as the research object., this paper is based on the results of numerical simulation and model measurement under rated conditions, combining with difference analysis between field data and others, as well as further study inside flow pattern of prototype and model Kaplan turbine. Reasonable judgment is made on various performance indicators, which provides reliable basis for the implement of hydraulic turbine by different methods and otherwise effectively guide the production practice.
Hydrogen as a fuel for electrifying transportation sector in Nepal: Opportunities and Challenges
Authors: Shakya N , Shrestha R , Saiju R , Thapa B S 
Published: June 2022

Abstract
At present more than 2 million kl fossil fuels are imported by Nepal per year, which is increasing at the rate of 7% annually on an average since 2012. The transportation sector alone accounts for more than 63% of the total fossil consumption. The major demand of fuels for transportation sector is diesel used by heavy-duty vehicles with high payload. The diesel demand for the year 2050 is projected to rise by 18%. There is a need for alternative fuel to diesel, which is also called hard-to-decarbonize fuel. Green hydrogen produced by electrolysis can be possibly used to power heavy locomotives due to its impressive properties as a heavy-duty transportation fuel. Several countries have already identified hydrogen as the future fuel for decarbonizing the transportation sector. Hydropower resource can be converted to green hydrogen as an energy storage medium and electrifying transportation sector. This paper identifies the need for an alternative to diesel fuel in the transportation sector and attempts to introduce hydrogen as a decarbonizing fuel to electrify the heavy-duty transportation sector of Nepal. Attempts are made to investigate the economic and environmental benefits of hydrogen in Nepal for heavy duty transportation sector in comparison to conventional fuels.
Hydrologic risk from consecutive dry and wet extremes at the global scale
Authors: Rashid M M , Wahl T 
Published: June 2022

Abstract
Dry and wet extremes (i.e., droughts and floods) are the costliest hydrologic hazards for infrastructure and socio-environmental systems. Being closely interconnected and interdependent extremes of the same hydrological cycle, they often occur in close succession with the potential to exacerbate hydrologic risks. However, traditionally this is ignored and both hazards are considered separately in hydrologic risk assessments; this can lead to an underestimation of critical infrastructure risks (e.g., dams, levees, dikes, and reservoirs). Here, we identify and characterize consecutive dry and wet extreme (CDW) events using the Standardized Precipitation Evapotranspiration Index, assess their multi-hazard hydrologic risks employing copula models, and investigate teleconnections with large-scale climate variability. We identify hotspots of CDW events in North America, Europe, and Australia where the total numbers of CDW events range from 20 to 30 from 1901 to 2015. Decreasing trends in recovery time (i.e., time between termination of dry extreme and onset of wet extreme) and increasing trends in dry and wet extreme severities reveal the intensification of CDW events over time. We quantify that the joint exceedance probabilities of dry and wet extreme severities equivalent to 50-year and 100-year univariate return periods increase by several folds (up to 20 and 54 for 50-year and 100-year return periods, respectively) when CDW events and their associated dependence are considered compared to their independent and isolated counterparts. We find teleconnections between CDW and Niño3.4; at least 80% of the CDW events are causally linked to Niño3.4 at 50% of the grid locations across the hotspot regions. This study advances the understanding of multi-hazard hydrologic risks from CDW events and the presented results can aid more robust planning and decision-making.
Effect of carbon nanotubes on the biotribological behavior of hot-pressed PEEK-based composites for biomedical applications
Authors: Pigosso T , Richhariya V , Binder C , Silva F S , Carvalho O , Gomes J R 
Published: June 2022

Abstract
This study aims to evaluate the influence of carbon nanotubes (CNTs) content (0.1, 0.5, 1, and, 5 wt%) on the poly-ether-ether-ketone (PEEK) composites based on a veneering concept and produced by the hot-pressing technique. Biotribological tests were performed in a ball-on-plate geometry using an alumina ball as the counter body under a phosphate-buffered saline solution at 37 °C, assessing the coefficient of friction and specific wear rate. Hardness measurement, white-light interferometry, and scanning electron microscopy were employed to support the study. The results revealed that the carbon nanotubes exhibited a positive influence on the biotribological behavior resulting in 1 wt% CNT proved to be the optimized value. Such findings could engineer high-performance surfaces as load-bearing materials in biomedical applications.
Convolutional neural networks with radio-frequency spintronic nano-devices
Authors: Leroux Nathan , De Riz Arnaud , Sanz-Hernández Dédalo , Marković Danijela , Mizrahi Alice , Grollier Julie 
Published: June 2022

Abstract
Convolutional neural networks (LeCun and Bengio 1998 The Handbook of Brain Theory and Neural Networks 255–58; LeCun, Bengio and Hinton 2015 Nature
521 436–44) are state-of-the-art and ubiquitous in modern signal processing and machine vision. Nowadays, hardware solutions based on emerging nanodevices are designed to reduce the power consumption of these networks. This is done either by using devices that implement convolutional filters and sequentially multiply consecutive subsets of the input, or by using different sets of devices to perform the different multiplications in parallel to avoid storing intermediate computational steps in memory. Spintronics devices are promising for information processing because of the various neural and synaptic functionalities they offer. However, due to their low OFF/ON ratio, performing all the multiplications required for convolutions in a single step with a crossbar array of spintronic memories would cause sneak-path currents. Here we present an architecture where synaptic communications are based on a resonance effect. These synaptic communications thus have a frequency selectivity that prevents crosstalk caused by sneak-path currents. We first demonstrate how a chain of spintronic resonators can function as synapses and make convolutions by sequentially rectifying radio-frequency signals encoding consecutive sets of inputs. We show that a parallel implementation is possible with multiple chains of spintronic resonators. We propose two different spatial arrangements for these chains. For each of them, we explain how to tune many artificial synapses simultaneously, exploiting the synaptic weight sharing specific to convolutions. We show how information can be transmitted between convolutional layers by using spintronic oscillators as artificial microwave neurons. Finally, we simulate a network of these radio-frequency resonators and spintronic oscillators to solve the MNIST handwritten digits dataset, and obtain results comparable to software convolutional neural networks. Since it can run convolutional neural networks fully in parallel in a single step with nano devices, the architecture proposed in this paper is promising for embedded applications requiring machine vision, such as autonomous driving.
Intracellular flow cytometry staining of antibody-secreting cells using phycoerythrin-conjugated antibodies: pitfalls and solutions
Authors: Renner Patrick , Crone Michael , Kornas Matthew , Pioli KimAnh T , Pioli Peter D 
Published: June 2022

Abstract

Background
Antibody-secreting cells are terminally differentiated B cells that play a critical role in humoral immunity through immunoglobulin secretion along with possessing the potential to be long-lived. It is now appreciated that ASCs regulate multiple aspects of biology through the secretion of various cytokines. In this regard, ICFC is a key tool used to assess the presence of intracellular proteins such as cytokines and transcription factors.

Methods
Paraformaldehyde plus saponin or the eBioscience Foxp3/Transcription Factor Staining Buffer Set were used to evaluate the non-specific intracellular retention of phycoerythrin-containing antibody conjugates by ASCs.

Results
We showed that the use of phycoerythrin-containing antibody conjugates led to a false interpretation of ASC intracellular protein expression compared with other cell types. This was mainly due to the inappropriate retention of these antibodies specifically within ASCs. Furthermore, we demonstrated how to reduce this retention which allowed for a more accurate comparison of intracellular protein expression between ASCs and other cell types such as B lymphocytes. Using this methodology, our data revealed that spleen ASCs expressed toll-like receptor 7 as well as the pro-form of the inflammatory cytokine interleukin-1β.

Conclusion
Increasing the number of centrifugation steps performed on ASCs post-fixation leads to inappropriate retention of phycoerythrin-containing antibody conjugates during ICFC.
Root grafts matter for inter-tree water exchange – a quantification of water translocation between root grafted mangrove trees using field data and model-based indications
Authors: Wimmler Marie-Christin , Vovides Alejandra G , Peters Ronny , Walther Marc , Nadezhdina Nadezhda , Berger Uta 
Published: June 2022

Abstract

Background and Aims
Trees interconnected through functional root grafts can exchange resources, but the effect of exchange on trees remains under debate. A mechanistic understanding of resource exchange via functional root grafts will help understand their ecological implications for tree water exchange for individual trees, groups of trees and forest stands.

Methods
To identify the main patterns qualitatively describing the movement of sap between grafted trees, we reviewed the available literature on root grafting in woody plants that focus on tree allometry and resource translocation via root grafts. We then extended the BETTINA model, which simulates mangrove (Avicennia germinans) tree growth on the individual tree scale, to synthesize the available empirical information. Using allometric data from a field study in mangrove stands, we simulated potential water exchange and analysed movement patterns between grafted trees.

Key Results
In the simulations, relative water exchange ranged between −9.17 and 20.3 %, and was driven by gradients of water potential, i.e. differences in tree size and water availability. Moreover, the exchange of water through root grafts alters the water balance of trees and their feedback with the soil: grafted trees that receive water from their neighbours reduce their water uptake.

Conclusions
Our individual-tree modelling study is a first theoretical attempt to quantify root graft-mediated water exchange between trees. Our findings indicate that functional root grafts represent a vector of hydraulic redistribution, helping to maintain the water balance of grafted trees. This non-invasive approach can serve as a basis for designing empirical studies to better understand the role of grafted root interaction networks on a broader scale.
Comparison of Waning Neutralizing Antibody Responses Against the Omicron Variant 6 Months After Natural Severe Acute Respiratory Syndrome Coronavirus 2 Infection (With or Without Subsequent Coronavirus Disease 2019 [COVID-19] Vaccination) Versus 2-Dose COVID-19 Vaccination
Authors: Lim So Yun , Park Soonju , Kim Ji Yeun , Kim Seungtaek , Jee Youngmee , Kim Sung-Han 
Published: June 2022

Abstract
Following severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, subsequent ChAdOx1 nCoV-19 vaccination induced similar neutralizing antibody levels against the original strain but significantly higher levels against the Omicron variant compared to those who were not vaccinated. Prior SARS-CoV-2 infection exhibited higher neutralization antibody titers than vaccination alone for both original strains and the Omicron variant.
Testing Frequency Matters: An Evaluation of the Diagnostic Performance of a Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Rapid Antigen Test in US Correctional Facilities
Authors: Lind Margaret L , Schultes Olivia L , Robertson Alexander J , Houde Amy J , Cummings Derek A T , Ko Albert I , Kennedy Byron S , Richeson Robert P 
Published: June 2022

Abstract

Background
The Centers for Disease Control and Prevention recommends serial rapid antigen assay collection within congregate facilities. Although modeling and observational studies from communities and long-term care facilities have shown serial collection provides adequate sensitivity and specificity, the accuracy within correctional facilities remains unknown.

Methods
Using Connecticut Department of Correction data from 21 November 2020 to 15 June 2021, we estimated the accuracy of a rapid assay, BinaxNOW (Abbott), under 3 collection strategies: single test collection and serial collection of 2 and 3 tests separated by 1–4 days. The sensitivity and specificity of the first (including single), second, and third serially collected BinaxNOW tests were estimated relative to RT-PCRs collected ≤1 day of the BinaxNOW test. The accuracy metrics of the testing strategies were then estimated as the sum (sensitivity) and product (specificity) of tests in each strategy.

Results
Of the 13 112 residents who contributed ≥1 BinaxNOW test during the study period, 3825 contributed ≥1 RT-PCR paired BinaxNOW test. In relation to RT-PCR, the 3-rapid-antigen-test strategy had a sensitivity of 95.9% (95% CI: 93.6–97.5%) and specificity of 98.3% (95% CI: 96.7–99.1%). The sensitivities of the 2- and 1-rapid-antigen-test strategies were 88.8% and 66.8%, and the specificities were 98.5% and 99.4%, respectively. The sensitivity was higher among symptomatic residents and when RT-PCRs were collected before BinaxNOW tests.

Conclusions
We found serial antigen test collection resulted in high diagnostic accuracy. These findings support serial collection for outbreak investigation, screening, and when rapid detection is required (such as intakes or transfers).
Early Detection of Severe Acute Respiratory Syndrome Coronavirus 2 Variants Using Traveler-based Genomic Surveillance at 4 US Airports, September 2021–January 2022
Authors: Wegrzyn Renee D , Appiah Grace D , Morfino Robert , Milford Scott R , Walker Allison Taylor , Ernst Ezra T , Darrow William W , Li Siyao Lisa , Robison Keith , MacCannell Duncan , Dai Dongjuan , Girinathan Brintha P , Hicks Allison L , Cosca Bryan , Woronoff Gabrielle , Plocik Alex M , Simen Birgitte B , Moriarty Leah , Guagliardo Sarah Anne J , Cetron Martin S , Friedman Cindy R 
Published: June 2022

Abstract
We enrolled arriving international air travelers in a severe acute respiratory syndrome coronavirus 2 genomic surveillance program. We used molecular testing of pooled nasal swabs and sequenced positive samples for sublineage. Traveler-based surveillance provided early-warning variant detection, reporting the first US Omicron BA.2 and BA.3 in North America.