bluuebunny/crossref_metadata_2025_split huggingface dataset:
Measurement of functional adequacy in different learning contexts
Authors: Kuiken Folkert , Vedder Ineke 
Published: May 2022

AbstractLinguistic performance elicited by language tasks has generally been operationalized in terms of complexity, accuracy, and fluency (CAF). However, this study argues that assessment of L2 proficiency is impossible without taking into account the adequacy and efficacy of L2 performance. To that end, we developed a rating scale for measuring functional adequacy (FA). In order to investigate the validity, reliability, and applicability of the rating scale, a number of studies are reviewed in which FA was assessed by both expert and non-expert raters, in different learning contexts, for L2 and L1, involving various source and target languages, proficiency levels, task types and modalities. We discuss perspectives and challenges for the use of the FA rating scale, particularly with regard to task-based language assessment (TBLA).
Temperature and environmental degradation: an international evidence
Authors: Vo Duc Hong 
Published: May 2022

ABSTRACT

Introduction
The effects of temperature have largely been under-examined in climate change studies. This study examines both direct and indirect effects of temperature on environmental degradation using the sample of 103 middle-income countries from 1985 to 2019. Unlike previous studies in which a single equation approach is utilized, our study considers the simultaneous equations modelling to examine the energy-growth-environment nexus incorporating temperature and corruption. The difference and system generalized method of moments estimations for panel data are used.

Outcomes
Empirical results from this paper confirm both the direct and indirect effects (via energy consumption) of temperature on environmental degradation. We find corruption harms economic growth in middle-income countries. The continued use of fossil fuel energy in energy consumption deteriorates environmental quality. Our findings confirm the critical role of the services sector in supporting economic growth and reducing emerging consumption, leading to increased environmental quality.

Conclusion
Findings from our study reconfirm the vital role of renewable energy and its extended use in achieving dual objectives of supporting economic growth and improving the environmental quality in middle-income countries.
Trivalent rare-earth-codoped silicate phosphor materials (Ba1.3Ca0.7−x−y
SiO4: xDy3+/yEu3+) for solid-state lighting
Authors: Golja Desta R , Dejene Francis B , Kim Jung Yong 
Published: May 2022

Abstract
Trivalent dysprosium/europium-codoped silicate phosphors (Ba1.3Ca0.7x−y
SiO4: xDy3+/yEu3+) were prepared as a function of Eu3+ concentration (x = 0.03 and y = 0.01–0.05). The phosphors showed the averaged crystallite size of ∼37.2 ± 1.3 nm and displayed nano-/micro-scale grains with some void defects. The energy bandgap is about 4.3 eV for co-doped samples and 3.2 eV for the silicate host. The photoluminescence spectra indicated that the presence of Eu3+ ions enhanced the red light emission, and the emission peaks located at the versatile wavelengths of 482, 577, 592, 614, 652, and 703 nm. Then, the internal quantum efficiencies were estimated by using the Judd–Ofelt model. Resultantly, the best quantum efficiency was ∼74% when the doping concentrations were 3 mol% Dy3+ and 4 mol% Eu3+ ions. Finally, the CIE coordinate data exhibited that the emission color could be tuned from white to reddish-orange by changing the Eu3+ contents, proposing the applicability of Ba1.3Ca0.7−x−y
SiO4:xDy3+/yEu3+ phosphors to the solid-state lighting.
Noise modelling of perfusion CT images for robust hemodynamic parameter estimations
Authors: Li Sui , Zeng Dong , Bian Zhaoying , Ma Jianhua 
Published: May 2022

Abstract

Objective. The radiation dose of cerebral perfusion computed tomography (CPCT) imaging can be reduced by lowering the milliampere-second or kilovoltage peak. However, dose reduction can decrease image quality due to excessive x-ray quanta fluctuation and reduced detector signal relative to system electronic noise, thereby influencing the accuracy of hemodynamic parameters for patients with acute stroke. Existing low-dose CPCT denoising methods, which mainly focus on specific temporal and spatial prior knowledge in low-dose CPCT images, not take the noise distribution characteristics of low-dose CPCT images into consideration. In practice, the noise of low-dose CPCT images can be much more complicated. This study first investigates the noise properties in low-dose CPCT images and proposes a perfusion deconvolution model based on the noise properties. Approach. To characterize the noise distribution in CPCT images properly, we analyze noise properties in low-dose CPCT images and find that the intra-frame noise distribution may vary in the different areas and the inter-frame noise also may vary in low-dose CPCT images. Thus, we attempt the first-ever effort to model CPCT noise with a non-independent and identical distribution (i.i.d.) mixture-of-Gaussians (MoG) model for noise assumption. Furthermore, we integrate the noise modeling strategy into a perfusion deconvolution model and present a novel perfusion deconvolution method by using self-relative structural similarity information and MoG model (named as SR-MoG) to estimate the hemodynamic parameters accurately. In the presented SR-MoG method, the self-relative structural similarity information is obtained from preprocessed low-dose CPCT images. Main results. The results show that the presented SR-MoG method can achieve promising gains over the existing deconvolution approaches. In particular, the average root-mean-square error (RMSE) of cerebral blood flow (CBF), cerebral blood volume, and mean transit time was improved by 40.3%, 69.1%, and 40.8% in the digital phantom study, and the average RMSE of CBF can be improved by 81.0% in the clinical data study, compared with tensor total variation regularization deconvolution method. Significance. The presented SR-MoG method can estimate high-accuracy hemodynamic parameters andachieve promising gains over the existing deconvolution approaches.
Beyond automatic medical image segmentation—the spectrum between fully manual and fully automatic delineation
Authors: Trimpl Michael J , Primakov Sergey , Lambin Philippe , Stride Eleanor P J , Vallis Katherine A , Gooding Mark J 
Published: May 2022

AbstractSemi-automatic and fully automatic contouring tools have emerged as an alternative to fully manual segmentation to reduce time spent contouring and to increase contour quality and consistency. Particularly, fully automatic segmentation has seen exceptional improvements through the use of deep learning in recent years. These fully automatic methods may not require user interactions, but the resulting contours are often not suitable to be used in clinical practice without a review by the clinician. Furthermore, they need large amounts of labelled data to be available for training. This review presents alternatives to manual or fully automatic segmentation methods along the spectrum of variable user interactivity and data availability. The challenge lies to determine how much user interaction is necessary and how this user interaction can be used most effectively. While deep learning is already widely used for fully automatic tools, interactive methods are just at the starting point to be transformed by it. Interaction between clinician and machine, via artificial intelligence, can go both ways and this review will present the avenues that are being pursued to improve medical image segmentation.
Laser ablation as a method for microsampling of paint layers
Authors: Balakhnina I A , Brandt N N , Dedova A E , Zagladin A A , Chikishev A Yu 
Published: May 2022

Abstract
It is proposed to use nanosecond laser pulses to obtain microsamples of paint layers with subsequent identification of the substance using Raman microspectroscopy. It is shown that the ablation of the paint layer on the primed canvas is a two-threshold process. The proposed technique can be used to study paintings.
Development of the microbubble pump having ‘S-shape’ impeller using experimental and numerical analysis
Authors: Lee S-M , Jang C-M 
Published: May 2022

Abstract
Microbubble pumps for water treatment can be used in a variety of fields, including wastewater treatment of semiconductor factories, sewage treatment, and aquaculture. In this study, a microbubble pump, with the ‘S-shape’ impeller, for sewage treatment has been developed in two steps. In the first step, a numerical design optimization was performed to develop a small-scaled microbubble pump. In the second step, a microbubble pump with a capacity that can be used in an actual water treatment facility has been developed through the scale-up process of a small-scaled optimum design of microbubble pump. The experimental test rig of the microbubble pump has been developed to investigate the performances of the microbubble pump, such as air and water flow rate, pressure differences and torque. To analyse three-dimensional flow field in the micro-bubble pump, general analysis code, CFX, has been employed. SST turbulence model has been employed to estimate the eddy viscosity and compared the pump performance to k-ε model. Unstructured grids have been used to represent a hybrid grid system including blade, casing and inlet casing. The results in the first step, a small-scaled optimum design shows the efficiency about 30.4%, which corresponds to a 0.4 percentage points increase compared to the conventional one. The results in the second step, the final design of microbubble pump shows an efficiency of 32.5% at the flow rate of 200 lpm.
LES investigation of different shedding cloud behaviors around the typical NACA66 hydrofoil
Authors: Wang Ziyang , Cheng Huaiyu , Ji Bin 
Published: May 2022

Abstract
The unsteady cavity dynamics induced by the reverse flow and shock wave is a crucial issue in studies of cloud cavitation. In the current meeting paper, numerical simulation of cavitating flow around the NACA66 hydrofoil is performed based on the self-developed program. LES method is introduced to adequately account for the transient turbulence effects in compressible cavitating flow. The simulation agrees favorably with the previous experiment for the cavity shedding behaviors. The results showed that the unsteady cavity dynamics is induced by both the reverse flow and shock wave mechanism. Besides, the different cavity shedding behaviors of the reverse flow and shock wave are compared in details.
Effects of dissolved gas on surface pressure of a hydrofoil under cavitation condition
Authors: Matsuura Y , Tsuji D , Watanabe S , Tsuda S 
Published: May 2022

Abstract
Dissolved gas in water is known as one of the factors which affect cavitation. The present study focuses on the effect of dissolved gas on cavitation around a hydrofoil, more specifically on the hysteresis of cavitation and surface pressure of the hydrofoil. The pressure measurement on a hydrofoil of Clark Y-11.7% was carried out under various dissolved gas conditions. Pressure in the test section was reduced stepwise from an atmospheric pressure to that in a super-cavitation condition, then was increased stepwise to the atmospheric pressure condition. Amount of dissolved oxygen (DO) was used as a parameter representing the degree of air content, and three DO conditions were set at low DO: under 30%, middle DO: around 50%, and high DO: over 70% of saturation under atmospheric pressure. Also, two angles of attack, 8 and 20 degrees were selected. Although there is no significant difference of the surface pressure and its hysteresis at the angle of attack of 8 degrees, dissolved gas seems to affect the behavior of cavitation. At the angle of attack of 20 degrees, it was found that the appearance of cavity was changed by DO conditions, and it would affect surface pressure of the foil. Under high DO condition, when the cavity oscillated with large amplitude, dissolved gas seemed to enhance the growth of the cavity, and the cavity tended to grow as covering the suction surface of the foil; it would make the time-averaged surface pressure of high DO condition lower than that of the other DO condition.
Reduction of flow-induce noise of a high-speed centrifugal pump by applying blade leaning on guide vane
Authors: Wei Z C , Li N , Xiao R F , Tao R , Yang W , Hu H L 
Published: May 2022

Abstract
The generation of noise is harmful to worker’s health and the stable operation of the system. Due to the high speed and high head of the high-speed centrifugal pump, the noise performance needs improvement. Therefore, a high-speed centrifugal pump was studied both in experiment and numerical way. The noise performance of the high-speed pump is improved by optimizing the design of the impeller and the guide vane. The blade leaning is also applied as an improvement with forming the X-shape stagger between rotor and stator. Base on the numerical simulation, the characteristic curves and unsteady characteristics of different optimized cases are predicted. The optimal case is selected as the final experimental object to verify the effectiveness. Numerical result indicated that the pressure fluctuation at blade pass frequency (BPF) and the fluctuated radial force is the main component of the original pump. The noise spectrum distribution of the original pump is concentrated near the BPF in the experiment, which means that the rotation effect of the impeller is the main reason for the noise of the pump. By improving the hydraulic design, the pressure fluctuation and the radial force in the pump can be effectively suppressed. But many factors affect the pump noise, the improvement of hydraulic design is limited.
Computational fluid dynamic simulation of hull reservoir wave energy device
Authors: De Alwis V A U , De Silva A P K , Gunawardane S D G S P , Lee Young-Ho 
Published: May 2022

Abstract
This paper presents a Computational Fluid Dynamics (CFD) analysis of a wave energy device called the Hull Reservoir Wave Energy Converter (HRWEC). The device consists of a floating hull and a flap connected to the shaft of power take-off system (PTO), which is integral to the hull structure. It is unique due to its ability to convert wave energy by utilizing the pitch motion of the hull and rotating flap due to the internal water movement in the hull. Due to the complexity of the internal fluid dynamics, a CFD-based analysis was considered most appropriate. The CFD investigation of the dynamics of the device was done under regular wave conditions by using the ANSYS-AQWA and ANSYS FLUENT. Relative pitch angle variation, the hydrodynamic coefficients, which determine the degree of power extraction, were obtained from simulated results. A simulation was designed exhibiting complete system dynamics for different configurations varying on internal water height. Excellent convergence was observed, and an optimum configuration was identified. It is expected to validate the simulation results through experiments in the foreseeable future.
Influence of distance from water surface of a horizontally installed Savonius turbine in a rectangular open channel on turbine performance
Authors: Katayama Y , Watanabe S , Tsuda S 
Published: May 2022

Abstract
The aim of this investigation is to develop a nano-hydro turbine that can effectively utilize the wasted hydraulic energy in infrastructure such as agricultural and industrial canals and irrigation waterways. Up to this time, the utilization of such a small hydropower has not progressed owing to economic reasons. Therefore, we focus on the Savonius type, which has the advantages of low manufacturing cost and excellent maintainability because of its simple structure. Conventionally, the Savonius type has been developed and researched as a vertical axis wind turbine. In order to effectively utilize the water surface flow, which is particular to open channels, we place the turbine runner perpendicular to the water flow and horizontally on the channel bottom. In the present study, we experimentally investigated the effect of the parameters for the turbine installation and its operation, namely distance between a runner and the water surface and the rotation direction of the runner, on the performance at each water level. As a result, it was found that the suitable installation depth differs depending on the rotation direction of the turbine.
Optimization design and unsteady flow analysis of stall characteristics in a vertical centrifugal pump
Authors: Yang Gang , Zhao Xutao , Zhang Desheng , Yang Xueqi , Geng Linlin , Gao Xiongfa 
Published: May 2022

Abstract
In this paper, an optimization design of the vertical centrifugal pump with vaned diffuser was accomplished, and analyzed the internal flow pattern of the model before and after optimization under stall conditions to explore the relationship between design parameters and the stall characteristics. The reasons for the improvement of efficiency and hump characteristics curve after optimization were revealed combined with streamline distributions, entropy production theory and pressure fluctuation. The results show that the error between the external characteristic result calculated by Computational Fluid Dynamics (CFD) and the experimental value is less than 5%, which proves the reliability of the numerical simulation method adopted in this paper. The hydraulic efficiency under multiple operating conditions and stall characteristics of the optimized model have been significantly improved. After optimization, the entropy production rate in the vaned diffuser is greatly reduced, and the improvement of the internal flow pattern in the vaned diffuser is the main reason for slowing down the hump characteristic curve. The hydraulic performance and the stall characteristics of the vertical centrifugal pump can be significantly improved by properly increasing the radial distance of the vaneless region. The matching relationship between the vaned diffuser and the impeller is one of the important factors that affect the stall characteristics. The large-scale vortices in the vaned diffuser is the main reason for the low-frequency pressure fluctuation signal when operating in the hump region. The low-frequency signal in the vaned diffuser of the optimized model is obviously weakened.
Numerical simulation of unsteady flow characteristics in a centrifugal pump during runaway process caused by power failure
Authors: Zhang Chenying , Wang Wen Jie , Pei Ji , Yuan Shouqi 
Published: May 2022

Abstract
Centrifugal pump is widely used in agricultural irrigation, petrochemical, mining, metallurgy and other industries. A special centrifugal pump with elbow pipe is researched in this paper. The flow rate and rotating speed change rapidly, especially in elbow pipe, causing serious pressure fluctuation and complex vorticity in the centrifugal pump. A user-defined function to solve the angular momentum equation was calculated the pump rotational speed. Unsteady numerical simulation with SST turbulence model is carried out and Short time Fourier transform (STFT) and vorticity strength are used to analyse the pressure fluctuation and vortexes respectively. The results indicate that the rotational speed first decreases to zero and then reversely increases to runaway speed. Large area vorticity appeared at the elbow pipe when the high amplitude frequency of pressure fluctuation increased. The change law of main frequency of pressure fluctuation at the elbow pipe is consistent with the rotational speed change ruler, which is equal to blade passing frequency (BPF). The main source of pressure fluctuation was rotor stator interaction. This study’s results provide a meaningful reference about pump runaway process caused by power failure, leading to the prevention of dangerous situations, for safe operations of the pumping unit.
Effect of the number of blades on diffuser unsteady loss of centrifugal pump
Authors: Ueda Akihito , Takeda Tomoki , Sugiyama Daisuke , Miyagawa Kazuyoshi 
Published: May 2022

Abstract
In recent years, an unshrouded impeller is being developed for rocket turbopumps to reduce production costs and disk friction losses. However, the internal flow structure in a diffuser influenced by an impeller has not been clarified yet. In this study, we focused on the investigation of unsteady flow in turbopumps with unshrouded impellers and vaned diffusers by experiments and CFD. Furthermore, we investigated the effect of changing the number of blades of the impeller and diffuser on the unsteady losses in the diffuser. First, we measured the static pressure at the shroud side in the impeller and the velocity at the diffuser inlet and outlet. Second, we confirmed the accuracy of the CFD by comparing CFD results with experimental results. Third, we investigated unsteady losses in diffusers by CFD. We could confirm increased entropy at the suction surface and shroud side because of the tip leakage and the vortex. Finally, we changed the number of impeller blades or diffuser blades. In conclusion, the loss region at the suction surface and the high-pressure region at pressure surface in the unshrouded impeller were mixed and caused unsteady losses through the diffuser. And diffuser efficiency decreased because channel width in diffuser became narrower by the number of diffuser blades increasing.
Performance characteristics of propeller turbine using an outer ring runner
Authors: Morii R , Iio S 
Published: May 2022

Abstract
The authors focus on a small propeller turbine utilizing the extremely low head and relatively much flow rate sites. The proposed propeller turbine by the authors previously had fixed pitch vanes, and the vane was made of a constant thickness metal plate to reduce manufacturing cost and required technology. The turbine was in a step in the casing and had an outer ring on the runner vane periphery. The structure effectively suppressed the tip leakage flow but had no significant effect on turbine efficiency improvement. This is the limit of the constant thickness blade rotor. So, this study focuses on making the runner by additive manufacturing by the 3D printer because it is faster and cheaper than conventional production methods and is expected to improve turbine efficiency and physical strength. This study aims to compare the performance of the new ring runner model designed to further improve the efficiency of the turbine by CFD analysis and experiment. As a result, the turbine efficiency improved, tip leakage flow was suppressed by attached to the outer ring compared with the previous model
Flow characteristics around a guide vane in cross-flow turbine
Authors: Tanaka T , Otsuka K , Goto M , Iio S 
Published: May 2022

Abstract
A swing-type guide vane is the most popular in a cross-flow turbine, which controls the water flow rate into the turbine. The flow under the guide vane may turn away from the optimum direction in partial load operation by the flow separation from the guide vane leading edge. Maintaining the ideal velocity triangle at the runner inlet is essential to improve the turbine efficiency and to avoid noise and vibration for partial load operation. It is essential to reveal how the angle and shape of those guide vanes affect the flow behavior at the runner inlet and turbine performance. Therefore, this study focuses on the flow characteristics around the guide vane and at the cross-flow runner inlet. The authors verify the evaluation by CFD simulation and compare turbine performance and internal flow between different operating conditions with two guide vanes, the swing-type, and circular segment type. As a result, it is revealed that the swing-type guide vane affects the flow direction, and especially the flow angle is far from the optimum at partial operation. The circular segment type shows superior performance at partial load than the swing-type guide vane.