bluuebunny/crossref_metadata_2025 huggingface dataset:
Reduction of Ca2+ Entry by a Specific Block of KCa3.1 Channels Optimizes Cytotoxic Activity of NK Cells against T-ALL Jurkat Cells
Authors: Olivas-Aguirre Miguel , Cruz-Aguilar Laura Hadit , Pottosin Igor , Dobrovinskaya Oxana
Published: August 2023

Degranulation mediated killing mechanism by NK cells is dependent on store-operated Ca2+ entry (SOCE) and has optimum at moderate intracellular Ca2+ elevations so that partial block of SOCE optimizes the killing process. In this study, we tested the effect of the selective blocker of KCa3.1 channel NS6180 on SOCE and the killing efficiency of NK cells from healthy donors and NK-92 cells against T-ALL cell line Jurkat. Patch-clamp analysis showed that only one-quarter of resting NK cells functionally express KCa3.1 current, which increases 3-fold after activation by interleukins 15 and 2. Nevertheless, blockage of KCa3.1 significantly reduced SOCE and intracellular Ca2+ rise induced by IL-15 or target cell recognition. NS6180 (1 μM) decreased NK degranulation at zero time of coculture with Jurkat cells but already after 1 h, the degranulation reached the same level as in the control. Monitoring of target cell death by flow cytometry and confocal microscopy demonstrated that NS6180 significantly improved the killing ability of NK cells after 1 h in coculture with Jurkat cells and increased the Jurkat cell fraction with apoptotic and necrotic markers. Our data evidence a strong dependence of SOCE on KCa3.1 activity in NK cells and that KCa3.1 specific block can improve NK cytotoxicity.
Fe/TaC Coatings Produced on 145Cr6 Steel by Laser Alloying—Manufacturing Parameters and Material Characterization
Authors: Bartkowski Dariusz , Bartkowska Aneta
Published: August 2023

This paper focuses on Fe/TaC composite coatings produced on 145Cr6 steel by laser alloying a TaC precoat in paste form. Fe/TaC coatings were produced in two consecutive steps. The first stage was the application of a precoat in paste form made from tantalum carbide and water glass on a steel substrate. Three TaC precoat thicknesses were produced: 30 µm, 60 µm and 90 µm. In the second step, the TaC precoat was remelted on a steel substrate using a 3 kW rated diode laser beam. A constant laser beam scanning speed of 3 m/min and three laser beam powers were used: 500 W, 800 W and 1100 W. In the study, microstructure, microhardness, chemical and phase composition and wear resistance were tested. The aim of the research was to check the possibility of producing composite coatings in which the reinforcing phase will be TaC, and the role of the matrix will be played by the material from the substrate. It was found that it is possible to produce the continuous composite coatings by remelting the TaC precoat with steel substrate. As microhardness increased, so did wear resistance. The coating microhardness obtained ranged from about 750 to 850 HV0.05 depending on the parameters used.
Preparation of Chitosan-Modified Nano-Silver Solution Microcapsules and Their Effects on Antibacterial Properties of Waterborne Coatings
Authors: Wang Ying , Pan Pan , Yan Xiaoxing
Published: August 2023

In this paper, a chitosan-modified nano-silver solution was used as the core material of an antibacterial agent, and melamine formaldehyde resin was coated onto the core material to obtain the antibacterial microcapsules. The core/wall ratio, the stirring rate, the mass ratio of chitosan to silver ions, and the concentration of the emulsifier were used to carry out four-factor and three-level orthogonal experiments to explore the most significant factors affecting the coverage rate and output of microcapsules and the best preparation technology. The results showed that the concentration of the emulsifier was the most important factor affecting the preparation of microcapsules. The higher the concentration of the emulsifier, the better the dispersed morphology of microcapsules, and the higher the coverage rate, up to 44.0%. The antibacterial coating was prepared by mixing microcapsules with a waterborne primer at a content of 4.0%. Its optical properties, mechanical properties, and antibacterial properties were analyzed. By increasing the concentration of the emulsifier, the gloss of the coating showed a trend of first increasing and then decreasing. When the emulsifier concentration was 2.0%, the gloss of the Andoung wood surface coating reached the maximum value of 21.23%. The influence of emulsifier concentration on the color difference of coating had no obvious law, and it was negatively related to the light transmittance. In terms of mechanical properties, the concentration of the emulsifier is directly proportional to the hardness and impact resistance of the coating, with the maximum reaching 31 kg·cm, and is negatively related to adhesion and roughness. In terms of antibacterial properties, the higher the concentration of the emulsifier, the better the antibacterial properties of the coating. When the concentration of the emulsifier was 4.0%, the antibacterial rates of coating which coated the glass substrate were 71.3% and 80.0% for Escherichia coli and Staphylococcus aureus, respectively. The antibacterial rates of the Andoung wood surface coating reached the maximum, which were 68.4% and 73.2%, respectively, and the antibacterial performance was excellent. In this study, an efficient antibacterial microcapsule for waterborne coatings was prepared, which provided the reference value for the application of antibacterial microcapsules in waterborne coatings.
Variable Velocity Coating Thickness Distribution Model for Super-Large Planar Robot Spraying
Authors: Shi Tongjun , Xu Jiangmin , Cui Jie , Tao Lei , Xu Weijia , Wang Ziqiang , Ji Jianbo
Published: August 2023

This study proposed a dynamic optimization method for spray gun flow to address the issue of uneven film thickness in the acceleration and deceleration section of the z-shaped spray trajectory in large plane ship segments. The method takes into account the acceleration and deceleration section of the spray trajectory and improves the film thickness distribution. The study first established a static vertical spray coating growth model of the spray gun without considering the acceleration and deceleration of the spray trajectory. Then, we used an integral method to optimize the coating uniformity and established a film thickness distribution model. The optimization of spray speed and spray spacing is crucial in the use of variable flow spray guns. It is assumed that the acceleration and deceleration sections of the spraying trajectory are linear and symmetrical, which forms the basis for establishing a mathematical model for the variable flow spray gun. To determine the flow of the spray gun at different speeds in the acceleration and deceleration sections, the pattern search method was adopted. A section of a ship was used as an example for this study. In this study, we utilized numerical simulations to compare the uniformity of paint film thickness when using a spray gun with a constant flow versus variable flow. The results indicate that when taking into account the acceleration and deceleration section of the spray trajectory, the film thickness was more uniform with a variable flow. These findings demonstrate the feasibility and effectiveness of the proposed method.
The High-Pressure Phase Transition in Jamesonite: A Single-Crystal Synchrotron X-ray Diffraction Study
Authors: Comodi Paola , Balić-Žunić Tonci , Fastelli Maximiliano , Hanfland Michael , Collings Ines , Zucchini Azzurra
Published: August 2023

The high-pressure behavior of jamesonite (FePb4Sb6S14, a = 4.08(3) Å, b = 19.08(3) Å, c = 15.67(3) Å, β= 91.89°, space group P21/c) has been investigated using in situ HP synchrotron X-ray single-crystal diffraction up to ~17 GPa with a diamond anvil cell under hydrostatic conditions. Results of the volume isothermal equation of state (EoS), determined by fitting the P-V data with a third-order Birch–Murnaghan (BM) EoS, are V0 = 1207.1(4) Å3, K0 = 36(1) GPa and K’ = 5.7(7). At high pressure, jamesonite undergoes a phase transition to an orthorhombic structure with a Pmcb space group (β-jamesonite). The analysis of β-jamesonite’s compressibility up to 16.6 GPa, studied by fitting the data with a second-order BM-EoS, gives V0 = 1027(2) Å3, K0 = 74(2) GPa. The comparison of the structural refinements at different pressures indicates that Fe, Pb and Sb do not change their coordination number over the whole investigated P range, respectively, 6 for Fe, 7 and 8 for Pb and 5 + 2 for Sb. However, a significant change occurs on the orientation of Sb lone electron pairs upon the phase transition in accordance with the change in symmetry. Furthermore, a discontinuity in the Fe chain evolution at the transition pressure is observed.
Annihilation and Generation of Dislocations by Irradiation by Ions and Electrons in Strontium Titanate Single Crystal
Authors: Wojtyniak Marcin , Rodenbücher Christian , Jany Benedykt R. , Cempura Grzegorz , Kruk Adam , Krok Franciszek , Szot Krzysztof
Published: August 2023

The physical and chemical properties of many oxide materials depend strongly on their defect concentration, which gives rise to unique electronic, optical, and dielectric properties. One such promising material for various applications, including energy storage, photocatalysis, and electronics, is SrTiO3 (STO). It exhibits several interesting phenomena, including a metal-to-insulator transition that can be induced by reduction. By extension, 1-D defects, such as dislocations, play a significant role in its electronic properties. Thus, we investigate the process of dislocation movement, its creation, and annihilation under two stimuli: ion thinning and electron irradiation. First, we designed and produced a lamella from a mechanically modified sample with variable thickness in the form of a wedge using a focused ion beam (FIB/Ga+) to investigate thickness-dependent dislocation movement. The lamella was investigated by transmission electron microscopy, allowing for the measurements of dislocation concentration as a function of its thickness. We have noticed a sharp decrease in the defect concentration with respect to the starting sample, showing a process of annihilation of dislocations. Second, we used an electron beam to drive a relatively large current into the STO surface. This experiment produced an electrical breakdown-like pattern. Optical and atomic force microscopy revealed that this pattern evolved due to the removal of material from the surface and local metal-insulator-transition along the dislocations network. Thus, we observe the dislocations generation and movement.
Performance of Point-of-Care Ultrasonography in Confirming Feeding Tube Placement in Mechanically Ventilated Patients
Authors: Ragunathan Thanalachumy , Teo Rufinah , Mohamad Yusof Aliza , Mohamad Mahdi Siti Nidzwani , Izaham Azarinah , Liu Chian Yong , Budiman Maryam , Sayed Masri Syarifah Noor Nazihah , Abdul Rahman Raha
Published: August 2023

Background: A feeding tube (FT) is routinely placed in critically ill patients, and its correct placement is confirmed with a chest X-ray (CXR), which is considered the gold standard. This study evaluated the diagnostic accuracy of ultrasonography (USG) in verifying FT placement compared to a CXR in an intensive care unit (ICU). Method: This was a prospective single-blind study conducted on patients admitted to the ICU of a tertiary hospital in Malaysia. The FT placements were verified through a fogging test and USG at the neck and subxiphoid points. The results of confirmation of FT placement through USG were compared with those obtained using CXRs. Results: A total of 80 patients were included in this study. The FT positions were accurately confirmed by overall USG assessments in 71 patients. The percentage of FT placements correctly identified by neck USG was 97.5%, while the percentage of those identified by epigastric USG was 75%. The corresponding patients’ CXRs confirmed correct FT placement in 76 patients. The overall USG assessment had a sensitivity of 92.11% and specificity of 75%, a positive predictive value of 98.59%, and a negative predictive value of 33.33%. The USG findings also showed a significant association between FT size and BMI. FTs with a size of 14Fr were better visualized (p = 0.008), and negative USG findings had a significantly higher BMI (p < 0.001). Conclusion: USG is a simple, safe, and reliable bedside assessment that offers relatively high sensitivity in confirming correct FT placement in critically ill patients.
Analysis of Bilaterality and Symmetry of Posterior Staphyloma in High Myopia
Authors: Ruiz-Moreno José M. , Puertas Mariluz , Flores-Moreno Ignacio , Almazán-Alonso Elena , García-Zamora María , Ruiz-Medrano Jorge
Published: August 2023

The purpose of this study was to examine bilaterality and symmetry of posterior staphyloma (PS) in high myopic eyes. Methods: This cross-sectional and non-interventional study assessed 473 high myopic eyes [axial length (AL) ≥ 26 mm] of 259 patients. Patients underwent an ophthalmological examination including multimodal-imaging and myopic maculopathy grading according to Atrophic/Tractional/Neovascular (ATN) system, presence and subtype of PS, and severe pathologic myopia (PM). Bilaterality of PS and subtype’s symmetry between eyes of the same patient was assessed. Four groups were analyzed: (1) bilateral vs. unilateral PS’s eyes. Within bilateral group, symmetric vs. asymmetric subtypes according to (2) Curtin’s classification, (3) Ohno-Matsui’s classification, and (4) primary/compound subtypes. Results: Out of the total, 334 myopic eyes of 167 patients were included. The 92.8% (n = 310/334) of the eyes presented PS and was bilateral in 85.6% (n = 143/167) of the patients. Bilateral eyes showed significantly (p < 0.01) greater AL, severe PM, A and N components vs. unilateral PS. AL-difference between both eyes was greater in unilateral PS (p < 0.01). Among bilateral PS, the subtype was symmetric in 79 (55.2%), 84 (58.7%), and 115 (80.4%) patients according to Curtin’s classification, Ohno-Matsui’s classification, and primary/compound; respectively. The asymmetric group presented worse best-corrected visual acuity (p < 0.01), higher AL (p < 0.01), incidence of PM, and severe PM (p < 0.05). Conclusions: PS was bilateral in most of the patients without clinical differences between both eyes, being symmetrical in more than half of bilateral cases. Patients with bilateral PS showed higher myopic maculopathy, AL, and incidence of severe PM than unilateral PS.
Particular Aspects Related to CD4+ Level in a Group of HIV-Infected Patients and Associated Acute Coronary Syndrome
Authors: Bajdechi Mircea , Gurghean Adriana , Bataila Vlad , Scafa-Udriște Alexandru , Bajdechi Georgiana-Elena , Radoi Roxana , Oprea Anca Cristiana , Chioncel Valentin , Mateescu Iuliana , Zekra Lucia , Cernat Roxana , Dumitru Irina Magdalena , Rugina Sorin
Published: August 2023

People living with HIV infection are at high risk for cardiovascular events due to inflammation and atherosclerosis. Also, some antiretroviral therapies may contribute to the risk of cardiovascular complications. Immune status is highly dependent on the level of lymphocyte T helper CD4+. There are data suggesting that immune status and CD4+ cell count may be involved in the development of cardiovascular complications in these patients. Our study is longitudinal and retrospective and included a total number of 50 patients with HIV infection associated with acute coronary syndrome, divided into two subgroups based on the nadir of CD4+ cells. This study analyzes the relationship between the immune status of HIV patients, assessed by the nadir of the CD4+ T-cell count, and the outcome of these patients. Also, secondary endpoints were the assessment of the magnitude of coronary lesions and of thrombotic and bleeding risk assessed by specific scores. Clinical and biological parameters and also the extension and complexity of coronary lesions were assessed. Although patients with poor immune status had more complex coronary lesions and increased operative risk and bleeding risk at one year, this was not associated with significant differences in major adverse cardiac and cerebrovascular events at the 30-day and 1-year outcomes.
Validation of the Accuracy of Automatic Measurement of Blood Volume in Culture Bottles for Blood Culture
Authors: Kim Kyoungbo , Park Sunggyun
Published: August 2023

Several manufacturers have developed systems that automatically measure the amount of blood in culture bottles. We compared the volumes measured automatically by the Virtuo instrument (bioMérieux, France) (height-based volumes) and those calculated by weighing the bottles. In all, 150 pairs of aerobic and anaerobic blood culture bottles (BacT/ALERT FA/FN Plus, bioMérieux) were randomly selected over two periods to compare the height- and weight-based volumes and analyze the effect of foam. We also estimated the limit of detection (LOD) and the cut-off value for 5 mL equine blood. The mean height-based volume was approximately 0.67 mL greater than the weight-based volume, particularly in anaerobic culture bottles. Foam did not have a significant effect. The LOD for the automatic height-based volume of equine blood was 0.2–0.4 mL. The 5 mL cut-off was 4–4.2 mL. Therefore, when reporting or monitoring blood volume within culture bottles in the laboratory, these performance characteristics should be adequately considered.
Detection of Alzheimer’s Disease Based on Cloud-Based Deep Learning Paradigm
Authors: Pruthviraja Dayananda , Nagaraju Sowmyarani C. , Mudligiriyappa Niranjanamurthy , Raisinghani Mahesh S. , Khan Surbhi Bhatia , Alkhaldi Nora A. , Malibari Areej A.
Published: August 2023

Deep learning is playing a major role in identifying complicated structure, and it outperforms in term of training and classification tasks in comparison to traditional algorithms. In this work, a local cloud-based solution is developed for classification of Alzheimer’s disease (AD) as MRI scans as input modality. The multi-classification is used for AD variety and is classified into four stages. In order to leverage the capabilities of the pre-trained GoogLeNet model, transfer learning is employed. The GoogLeNet model, which is pre-trained for image classification tasks, is fine-tuned for the specific purpose of multi-class AD classification. Through this process, a better accuracy of 98% is achieved. As a result, a local cloud web application for Alzheimer’s prediction is developed using the proposed architectures of GoogLeNet. This application enables doctors to remotely check for the presence of AD in patients.
Gaussian of Differences: A Simple and Efficient General Image Fusion Method
Authors: Kurban Rifat
Published: August 2023

The separate analysis of images obtained from a single source using different camera settings or spectral bands, whether from one or more than one sensor, is quite difficult. To solve this problem, a single image containing all of the distinctive pieces of information in each source image is generally created by combining the images, a process called image fusion. In this paper, a simple and efficient, pixel-based image fusion method is proposed that relies on weighting the edge information associated with each pixel of all of the source images proportional to the distance from their neighbors by employing a Gaussian filter. The proposed method, Gaussian of differences (GD), was evaluated using multi-modal medical images, multi-sensor visible and infrared images, multi-focus images, and multi-exposure images, and was compared to existing state-of-the-art fusion methods by utilizing objective fusion quality metrics. The parameters of the GD method are further enhanced by employing the pattern search (PS) algorithm, resulting in an adaptive optimization strategy. Extensive experiments illustrated that the proposed GD fusion method ranked better on average than others in terms of objective quality metrics and CPU time consumption.
Poultry Value Chain Performance Measurement Using Stochastic Frontier Analysis in Mozambique, Maputo Region
Authors: Chunga João , Silva Luis Mira , Soares Fernando Brito
Published: August 2023

Poultry production in Mozambique occupies a prominent place in the agricultural sector, especially because it is attractive for the promotion of entrepreneurship and self-employment. These facts are due to the short cycle and a large increase in the consumption of poultry products. However, despite the opportunities it presents, challenges do exist, namely, the strategic organization of producers and the access to the market, which give producers a weak capacity to compete, and thus favoring imports to the country. To analyze competitiveness, stochastic models were used to determine the efficiency of producers and to define good practices. The results clearly show that producers with a more organized and well-planned structure, producing more than 2000 chickens per cycle of production, tend to be more efficient when compared to those with less organized structures and without commercial agreements that facilitate market access.
ESD-YOLOv5: A Full-Surface Defect Detection Network for Bearing Collars
Authors: Li Jiale , Pan Haipeng , Li Junfeng
Published: August 2023

To address the different forms and sizes of bearing collar surface defects, uneven distribution of defect positions, and complex backgrounds, we propose ESD-YOLOv5, an improved algorithm for bearing collar full-surface defect detection. First, a hybrid attention module, ECCA, was constructed by combining an efficient channel attention (ECA) mechanism and a coordinate attention (CA) mechanism, which was introduced into the YOLOv5 backbone network to enhance the localization ability of object features by the network. Second, the original neck was replaced by the constructed Slim-neck, which reduces the model’s parameters and computational complexity without sacrificing accuracy for object detection. Furthermore, the original head was replaced by the decoupled head from YOLOX, which separates the classification and regression tasks for object detection. Last, we constructed a dataset of defective bearing collars using images collected from industrial sites and conducted extensive experiments. The results demonstrate that our proposed ESD-YOLOv5 detection model achieved an mAP of 98.6% on our self-built dataset, which is a 2.3% improvement over the YOLOv5 base model. Moreover, it outperformed mainstream one-stage object detection algorithms. Additionally, the bearing collar surface defect detection system developed based on our proposed method has been successfully applied in the industrial domain for bearing collar inspection.
Computation and Communication Efficient Adaptive Federated Optimization of Federated Learning for Internet of Things
Authors: Chen Zunming , Cui Hongyan , Wu Ensen , Yu Xi
Published: August 2023

The proliferation of the Internet of Things (IoT) and widespread use of devices with sensing, computing, and communication capabilities have motivated intelligent applications empowered by artificial intelligence. Classical artificial intelligence algorithms require centralized data collection and processing, which are challenging in realistic intelligent IoT applications due to growing data privacy concerns and distributed datasets. Federated Learning (FL) has emerged as a privacy-preserving distributed learning framework, which enables IoT devices to train global models through sharing model parameters. However, inefficiency due to frequent parameter transmissions significantly reduces FL performance. Existing acceleration algorithms consist of two main types including local update and parameter compression, which considers the trade-offs between communication and computation/precision, respectively. Jointly considering these two trade-offs and adaptively balancing their impacts on convergence have remained unresolved. To solve the problem, this paper proposes a novel efficient adaptive federated optimization (FedEAFO) algorithm to improve the efficiency of FL, which minimizes the learning error via jointly considering two variables including local update and parameter compression. The FedEAFO enables FL to adaptively adjust two variables and balance trade-offs among computation, communication, and precision. The experiment results illustrate that compared with state-of-the-art algorithms, the FedEAFO can achieve higher accuracies faster.
The Frequency Control Strategy of a Wind–Storage Combined System Considering Battery SOC
Authors: Wang Xi , Ye Xi , Wei Wei , Wang Yanfeng , Zhu Tong , Liu Chang , Chen Yufan
Published: August 2023

The wind power capacity has increased a lot recently and the number of close energy storage systems has also rapidly increased. To enhance the frequency stability support ability of such wind–storage combined systems, this paper proposes a virtual synchronous control strategy for a wind–storage combined system considering the battery state of charge (SOC). The virtual synchronous control is used to make the wind turbine generate more active power when the system is in disturbance. Most importantly, to ensure that the stored energy is used efficiently, the wide-area SOC concept of the energy storage system is considered, which is realized by designing the batteries with additional control that is related to the other batteries’ SOCs. This means that the low-SOC energy storage system’s power shortage can be compensated for by the high-SOC batteries. The above unified control enhances the wind–storage combined system’s frequency supporting ability. According to the simulations, the frequency drop can be suppressed through the help of the virtual synchronous control and the stored energy. Additionally, the instability can also be eliminated when wide-area SOC is considered, such that the proposed efficiency and correctness are finally verified through the simulations.
Three-Phase Inverter Fault Diagnosis Based on an Improved Deep Residual Network
Authors: Fu Yanfang , Ji Yu , Meng Gong , Chen Wei , Bai Xiaojun
Published: August 2023

This study addresses the challenges of limited fault samples, noise interference, and low accuracy in existing fault diagnosis methods for three-phase inverters under real acquisition conditions. To increase the number of samples, Wavelet Packet Decomposition (WPD) denoising and a Conditional Variational Auto-Encoder (CVAE) are used for sample enhancement based on the existing faulty samples. The resulting dataset is then normalized, pre-processed, and used to train an improved deep residual network (SE-ResNet18) fault diagnosis model with a channel attention mechanism. Results show that the augmented fault samples improve the diagnosis accuracy compared with the original samples. Furthermore, the SE-ResNet18 model achieves higher fault diagnosis accuracy with fewer iterations and faster convergence, indicating its effectiveness in accurately diagnosing inverter open-circuit faults across various sample situations.
Day-Ahead Dynamic Assessment of Consumption Service Reserve Based on Morphological Filter
Authors: Cai Xinlei , Wang Naixiao , Cai Qinqin , Wang Hengzhen , Cheng Zhangying , Wang Zhijun , Zhang Tingxiang , Xu Ying
Published: August 2023

With the development goal of a low-cost and low-carbon reserve market, this paper proposes a dynamic assessment method for day-ahead consumption service reserve demand considering the forecast error of uncertainty power. The iterative self-organizing data analysis techniques algorithm is adopted to cluster the historical actual power into typical scenarios. In addition, the online matching between the typical scenario and the day-ahead forecast power is conducted. In order to realize the hierarchical quantification of reserve demand, the reserve resources in the whole power system are classified according to their response time. Furthermore, the mathematical morphology filter based on the structural elements that are consistent with the response time of the hierarchical reserve resources is initially applied to decompose the historical forecast error of the matched scenarios. The simulation results verify that the proposed dynamic assessment effectively reduces the reserve cost on the basis of being able to cope with multi-time-scale power fluctuations.
Silica Nanoparticle Formation from Supercritical Geothermal Sources
Authors: Bordvik Silje , Næss Erling
Published: August 2023

Silica precipitation from high-enthalpy, depressurized supercritical fluids is investigated to determine the best method for accessing the scaling potential as a function of time, position and fluid composition. The most relevant knowledge application is for geothermal sources where the wells are drilled closed to magma and the temperature gradients in the rock are very high. The power potential per well for such a system is large compared to conventional geothermal power production, but several knowledge gaps, among them mineral precipitation from produced fluids, limit commercial use. For the high-enthalpy supercritical well fluid used as a base case in this review, conventional methods for reducing the silica content before it enters a turbine limit the power output. Knowledge of the particle-number density, size and time scales of growth in different depressurization scenarios, along with the silica solubility, kinetics and morphology, is essential to handle deposits and avoid scaling in inconvenient parts of the power plant. Experimental data on the precipitation of silica from highly supersaturated superheated steam are scarce, and it is known that the kinetics of precipitation in steam differ from those of liquid water. We argue that to quantify the number of solids in the depressurized supercritical fluid and superheated steam, dividing the process into three separate but dependable mathematical steps is a reliable approach: (1) the nucleation of nanocolloids, (2) growth by agglomeration, and (3) deposition onto a surface.
Research and Development of the Oxy-Fuel Combustion Power Cycle for the Combined Production of Electricity and Hydrogen
Authors: Kindra Vladimir , Rogalev Andrey , Oparin Maksim , Kovalev Dmitriy , Ostrovsky Mikhail
Published: August 2023

Modern trends in improving environmental safety have determined the urgency in creating innovative technologies that allow the production of electricity and hydrogen without the emission of harmful substances. However, at the moment, there are not so many technical solutions offering the combined production of these useful products with a high degree of efficiency and environmental friendliness. The transition to oxy-fuel combustion power cycles for the co-production of electricity and hydrogen is a prospective way to decrease carbon dioxide emissions into the atmosphere from the energy sector. To achieve zero emissions, the semi-closed oxy-fuel combustion cycle is combined with a steam methane reformer, which has a high energy efficiency through reducing losses in the steam turbine condenser. The modeling methodology has been described in detail, including the approaches to defining the working fluid properties and mathematical models of the different steam methane reforming plants and the oxy-fuel combustion power plant. According to the results of the thermodynamic analysis of the steam methane reforming plant, it was found that an increase in the temperature from 850 to 1000 °C leads to a decrease in the mass flow fuel by 16.3% due to the shift towards a direct reaction. Moreover, the optimal temperature in the reformer lies in the range of 900–950 °C. A comparison of the energetic and ecological characteristics of various steam methane reformer units showed that the scheme with oxy-fuel combustion is better compared to the scheme with CO2 capture by absorption in monoethanolamine; the efficiency is 6.9% higher and emissions of carbon dioxide are 22 times lower. According to the results of the thermodynamic analysis of a novel oxy-fuel combustion power cycle, it was found that its performance varied regarding the range of electricity production (123.6–370 MW) and hydrogen production (0–10.8 kg/s). The efficiency of the oxy-fuel combustion power cycle varies in the range of 47.2–70.1%. Based on the results of the operation regimes analysis, the energy complex performance map has been developed, allowing identification of the efficiency and working fluid massflow by net power and produced hydrogen massflow.
An Optimized Switching Strategy Based on Gate Drivers with Variable Voltage to Improve the Switching Performance of SiC MOSFET Modules
Authors: Tan Jixiang , Zhou Zhongfu
Published: August 2023

This paper proposes an optimized switching strategy (OSS) based on a silicon carbide (SiC) MOSFET gate driver with variable voltage, which allows simultaneous variations in several different parameters to optimize the switching performance of semiconductor devices. As a relatively new device, the SiC MOSFET shines in the field of high power density and high-frequency switching; it has become a popular solution for electric vehicles and renewable energy conversion systems. However, the increase in voltage and current slope caused by high switching speeds inevitably increases the overshoot and oscillation in a circuit and can even generate additional losses. The principle of this new control strategy is to change the voltage and current in the turn-on and turn-off stages by changing the gate driver’s voltage. That is, we reduced the drive’s voltage after a certain time delay and maintained it for a period of time, thus directly controlling the slopes of di/dt and dv/dt. This study focused on the optimization of the SiC MOSFET by changing the time delay preceding the decrease in the voltage of the gate driver, analyzing and calculating the optimal time delay before the decrease in the voltage of the gate driver, and verifying the findings using LTspice simulation software. The simulated results were compared and analyzed with hard-switching strategies. The results showed that the proposed OSS can improve the switching performance of SiC MOSFETs.
Large Eddy Simulation of Externally Induced Ingress about an Axial Seal by Stator Vanes
Authors: Nketia Sabina , Bryden Kenneth Mark , Dalton Richard , Shih Tom I-P.
Published: August 2023

Turbine inlet temperatures in advanced gas turbines could be as high as 2000 °C. To prevent ingress of this hot gas into the wheelspace between the stator and rotor disks, whose metals can only handle temperatures up to 850 °C, rim seals and sealing flows are used. This study examines the abilities of large eddy simulation (LES) based on the WALE subgrid model and Reynolds-averaged Navier–Stokes (RANS) based on the SST model in predicting ingress in a rotor–stator configuration with vanes but no blades, a configuration with experimental data for validation. Results were obtained for an operating condition, where the ratio of the external Reynolds number to the rotational Reynolds number is 0.538. At this operating condition, both LES and RANS were found to correctly predict the coefficient of pressure, Cp, located downstream of the vanes and upstream of the seal, but only LES was able to correctly predict the sealing effectiveness. This shows Cp by itself is inadequate in quantifying externally induced ingress. RANS was unable to predict the sealing effectiveness because it significantly under predicted the pressure drop in the hot gas path along the axial direction, especially about the seal region. This affected the pressure difference across the seal in the radial direction, which ultimately drives ingress.
Experimental Study of a Fixed OWC-Type Wave Energy Converter with a Heave Plate and V-Shaped Channels for Intermediate-Water-Depth Applications
Authors: Ulm Nicholas , Huang Zhenhua , Cross Patrick
Published: August 2023

The study of oscillating water column (OWC)-type wave energy converters (WEC) has primarily focused on applications in the nearshore environment with an end use in residential power grids. This study examines the power performance of a new OWC geometry relative to blue economy energy objectives that focus on providing power in the intermediate-water-depth environment. The method examines power performance through the performance indicators of extraction efficiency, coefficient of amplification, and coefficient of pressure. The study discusses the implications of these coefficients relative to a new end use and examines if an analytical relationship between each indicator exists. The power performance is evaluated through experimental testing on a fixed-geometry OWC that consists of a cylindrical OWC chamber affixed above a heave plate with V-shaped channels. In evaluating power performance, the impact of different representative power take-off (PTO) damping values and directional dependence is investigated. It was found that incident wave angle has a minimal impact on extraction efficiency for this geometry and that a relationship exists between extraction efficiency, wave frequency, and PTO damping. It can be concluded that extraction efficiency can be expressed as a function of each coefficient, that an emphasis on extraction efficiency may be misguided for at-sea power applications, and that performance indicators have functionality in OWC design outside of power performance.
Heating Performance and Economic Analysis of Solar-Assisted Cold-Water Phase-Change-Energy Heat Pump System in Series and Parallel Connections
Authors: Yang Yujuan , Wu Ronghua , Yue Yuanbo , Zhang Yao , Sun Yuanyuan , Liu Shunjie
Published: August 2023

To study the heating performance of a solar-assisted cold-water phase-change-energy heat pump system, its heating performance under series and parallel connections is simulated for a community in Harbin, the influence of ice thickness on the different operation modes is analyzed, and the economy of the system is calculated for series and parallel connections in this paper. The results show that the water supply temperature is higher and more uniform in the parallel operation, and more terminal heat is supplied; the ice thickness has more of an influence on the series connection compared to the parallel connection; and the dynamic payback period is 6.72 years for the series connection and 7.28 years for the parallel connection. This case study can serve as a guide for practical engineering application projects and act as a reference for heating and economic data for the promotion of this heat pump system.
Validation and Verification of containmentFOAM CFD Simulations in Hydrogen Safety
Authors: Yassin Khaled , Kelm Stephan , Kampili Manohar , Reinecke Ernst-Arndt
Published: August 2023

As the applications of hydrogen as a replacement for fossil fuels and energy storage increase, more concerns have been raised regarding its safe usage. Hydrogen’s extreme physical properties—its lower flammability limit (LFL), for instance—represent a challenge to simulating hydrogen leakage and, hence, mitigating accidents that occur due to such leakage. In this work, the OpenFOAM-based CFD simulation package containmentFOAM was validated by different experimental results. As in its original use, to simulate nuclear safety issues, the containmentFOAM package is capable of capturing different phenomena, like buoyant gas clouds and diffusion between gases and air. Despite being widely validated in nuclear safety, this CFD package was assessed with benchmark experiments used to validate hydrogen leakage scenarios. The validation cases were selected to cover different phenomena that occur during the hydrogen leakage—high-speed jet leakage, for example. These validation cases were the hallway with vent, FLAME, and GAMELAN experiments. From the comparison of the experimental and simulation results, we concluded that the containmentFOAM package showed good consistency with the experimental results and, hence, that it can be used to simulate actual leakage cases.
The Identification of the Abundance of European Larch Trees in Polish Forests
Authors: Jankowska Agnieszka , Sagan Jacek , Potocki Michał
Published: August 2023

The purpose of the study was to identify the abundance of European larch trees in Polish forests, taking into account the size of areas and their location. A dendrometric analysis (volume, age of trees) was performed as a source of knowledge on the availability of the raw material base as a response to the production needs of wood products in Poland. The detailed data were made available in 2023 by the Directorate General of State Forests on the basis of a license specifying the conditions of use of the vector record of the forest numerical map and appraisal description data. European larch trees are in areas all around Poland. They grow throughout the country, with most stands located in the southern and northern parts of Poland. Stands with a dominant share of larch in the species composition (i.e., those that are part of trees stands with a minimum area of 0.1 ha) occupy 44,813 ha and occur in 17,553 stand divisions. The analysis of productivity showed that the average height of larch stands in Poland ranges from 5 m to 45 m. Tree stands are predominately 26–30 m in height. Most stands with trees over 30 m high are located in the RDFS Krosno (over 15% of the entire forest area with larch as the dominant species). European larch stands in Poland are characterized by significant differences in the average DBH. They are correlated with the age of the stands.
Annual Tree-Ring Curve-Fitting for Graphing the Growth Curve and Determining the Increment and Cutting Cycle Period of Sungkai (Peronema canescens)
Authors: Bahtiar Effendi Tri , Iswanto Apri Heri
Published: August 2023

Growth and increment are extremely important in sustainable forest management, and in forest inventory they are periodically measured in a permanent sampling unit. The age of a tree is often unknown, especially in natural, community, and urban forests; therefore, determining growth and increment can be problematic. The aim of this study was to propose a solution for this problem by conducting annual tree-ring curve-fitting to determine a tree’s age-related dimension so that growth and increment can then be calculated smoothly. Sungkai (Peronema canescens), a luxurious commercial timber chosen as a case study, resulted in a satisfying growth curve following continuous models (Gompertz, Chapman–Richards, and von Bertalanffy) and discrete models (Bahtiar and Darwis exponential modification). The Chapman–Richards model gave the best-fit sigmoid growth curve. The first derivation (dN/dt) of the growth formula produces the current annual increment (CAI). CAI intersection with mean annual increment (MAI) at the peak of MAI resulted in the optimum biological rotation age and a cutting cycle period of 30 years for the Sungkai plantation commonly planted in urban forests.
Soil Respiration and Related Abiotic and Remotely Sensed Variables in Different Overstories and Understories in a High-Elevation Southern Appalachian Forest
Authors: Hammer Rachel , Seiler John , Peterson John , Thomas Valerie
Published: August 2023

Accurately predicting soil respiration (Rs) has received considerable attention recently due to its importance as a significant carbon flux back to the atmosphere. Even small changes in Rs can have a significant impact on the net ecosystem productivity of forests. Variations in Rs have been related to both spatial and temporal variation due to changes in both abiotic and biotic factors. This study focused on soil temperature and moisture and changes in the species composition of the overstory and understory and how these variables impact Rs. Sample plots consisted of four vegetation types: eastern hemlock (Tsuga canadensis L. Carriere)-dominated overstory, mountain laurel (Kalmia latifolia L.)-dominated understory, hardwood-dominated overstory, and cinnamon fern (Osmundastrum cinnamomeum (L.) C. Presl)-dominated understory, with four replications of each. Remotely sensed data collected for each plot, light detection and ranging, and hyperspectral data, were compiled from the National Ecological Observatory Network (NEON) to determine if they could improve predictions of Rs. Soil temperature and soil moisture explained 82% of the variation in Rs. There were no statistically significant differences between the average annual Rs rates among the vegetation types. However, when looking at monthly Rs, cinnamon fern plots had statistically higher rates in the summer when it was abundant and hemlock had significantly higher rates in the dormant months. At the same soil temperature, the vegetation types’ Rs rates were not statistically different. However, the cinnamon fern plots showed the most sensitivity to soil moisture changes and were the wettest sites. Normalized Difference Lignin Index (NDLI) was the only vegetation index (VI) to vary between the vegetation types. It also correlated with Rs for the months of August and September. Photochemical reflectance index (PRI), normalized difference vegetation index (NDVI), and normalized difference nitrogen index (NDNI) also correlated with September’s Rs. In the future, further research into the accuracy and the spatial scale of VIs could provide us with more information on the capability of VIs to estimate Rs at these fine scales. The differences we found in monthly Rs rates among the vegetation types might have been driven by varying litter quality and quantity, litter decomposition rates, and root respiration rates. Future efforts to understand carbon dynamics on a broader scale should consider the temporal and finer-scale differences we observed.
Fostering Innovation, Transition, and the Reconstruction of Forestry: Critical Thinking and Transdisciplinarity in Forest Education with Strategy Games
Authors: Waeber Patrick O. , Melnykovych Mariana , Riegel Emilio , Chongong Leonel V. , Lloren Regie , Raher Johannes , Reibert Tom , Zaheen Muhammad , Soshenskyi Oleksandr , Garcia Claude A.
Published: August 2023

Forest education plays a crucial role in achieving the Sustainable Development Goals and promoting sustainable forest management amidst global challenges. However, existing programs struggle to keep pace with rapidly evolving crises and uncertainties that contribute to deforestation and forest degradation. To tackle these challenges, integrating innovative approaches into forest education is essential. This paper showcases the transformative use of a strategy game, MineSet, as an innovative teaching method for integrated forest management. The game facilitates deeply engaging experiences that provide unique insights into complex issues like deforestation. By assuming various stakeholder roles, graduate students actively engage with and confront the intricate tradeoffs inherent in forest management. This interactive and immersive role-play game not only fosters critical thinking skills but also promotes collaborative problem-solving, making MineSet a highly innovative and attractive tool in forest education. The importance of extended debriefings, facilitation throughout the game, and ongoing discussions should not be underestimated, as they establish meaningful and necessary connections between in-game events, validated educational material, and published research outcomes. Moreover, the game equips students with practical experience and a comprehensive understanding of landscape approaches, using the Congo Basin as a case study. We emphasize the potential of innovative forest education to foster sustainability, stimulate critical thinking, resolve conflicts, and prevent costly forest losses.