bluuebunny/crossref_metadata_2025 huggingface dataset:
A Geometric-Based LSGDM Method for Tourism Project Decision Optimization with Trust–Distrust Relationships
Authors: Zhou Lei , You Xinshang , Zhao Shuo , You Zengtai
Published: April 2022

In this paper, we discuss the decision optimization of tourism projects in Hebei Province, China. To improve the process of analyzing tourism projects, we introduce a model that includes multiple decision makers as subjects based on a standard four-dimensional evaluation system. In order to improve the effectiveness of decision-making results, we will increase the number of decision makers to 40. A novel large-scale group decision-making (LSGDM) algorithm that incorporates the trust–distrust asymmetric relationships between decision makers is proposed. This model contains three main innovations: firstly, in the evaluation of decision makers’ social network relations, the trust–distrust value is introduced as a new carrier, and a weighted directed network and data integration operator are constructed based on the evaluation between decision makers; secondly, an extended Girvan-Newman (GN) algorithm is constructed to cluster the decision makers from this weighted network; thirdly, the interval-valued intuitionistic fuzzy number (IVIFN) is used to evaluate the alternatives, studying the IVIFN’s geometric significance by placing in a rectangular coordinate system. Finally, a new LSGDM model is proposed. Using the development of a cultural tourism project in a township as an example, the effectiveness of the proposed model is illustrated. By comparing the results of our method to those of a LSGDM algorithm that does not incorporate trust relationships, we assess the performance of the new model.
Investigating Multi-Level Semantic Extraction with Squash Capsules for Short Text Classification
Authors: Li Jing , Zhang Dezheng , Wulamu Aziguli
Published: April 2022

At present, short text classification is a hot topic in the area of natural language processing. Due to the sparseness and irregularity of short text, the task of short text classification still faces great challenges. In this paper, we propose a new classification model from the aspects of short text representation, global feature extraction and local feature extraction. We use convolutional networks to extract shallow features from short text vectorization, and introduce a multi-level semantic extraction framework. It uses BiLSTM as the encoding layer while the attention mechanism and normalization are used as the interaction layer. Finally, we concatenate the convolution feature vector and semantic results of the semantic framework. After several rounds of feature integration, the framework improves the quality of the feature representation. Combined with the capsule network, we obtain high-level local information by dynamic routing and then squash them. In addition, we explore the optimal depth of semantic feature extraction for short text based on a multi-level semantic framework. We utilized four benchmark datasets to demonstrate that our model provides comparable results. The experimental results show that the accuracy of SUBJ, TREC, MR and ProcCons are 93.8%, 91.94%, 82.81% and 98.43%, respectively, which verifies that our model has greatly improves classification accuracy and model robustness.
Exploration of Entropy Pair Functional Theory
Authors: Sluss Clifton C. , Pittman Jace , Nicholson Donald M. , Keffer David J.
Published: April 2022

Evaluation of the entropy from molecular dynamics (MD) simulation remains an outstanding challenge. The standard approach requires thermodynamic integration across a series of simulations. Recent work Nicholson et al. demonstrated the ability to construct a functional that returns excess entropy, based on the pair correlation function (PCF); it was capable of providing, with acceptable accuracy, the absolute excess entropy of iron simulated with a pair potential in both fluid and crystalline states. In this work, the general applicability of the Entropy Pair Functional Theory (EPFT) approach is explored by applying it to three many-body interaction potentials. These potentials are state of the art for large scale models for the three materials in this study: Fe modelled with a modified embedded atom method (MEAM) potential, Cu modelled with an MEAM and Si modelled with a Tersoff potential. We demonstrate the robust nature of EPFT in determining excess entropy for diverse systems with many-body interactions. These are steps toward a universal Entropy Pair Functional, EPF, that can be applied with confidence to determine the entropy associated with sophisticated optimized potentials and first principles simulations of liquids, crystals, engineered structures, and defects.
A Robust Electric Power-Steering-Angle Controller for Autonomous Vehicles with Disturbance Rejection
Authors: Khasawneh Lubna , Das Manohar
Published: April 2022

This paper addresses the challenges associated with steering-angle control of electric power steering for autonomous vehicles, including steering model parameter uncertainty, dependency of self-aligning moment disturbance estimation on tire parameters, and compensation for the asymmetrical hysteresis behavior in the steering system caused by backlash in gears and static friction. A variable gain-sliding mode steering-angle controller is developed to deal with these challenges. Replacing the fixed gain with variable gain in the sliding mode controller solves two problems: it eliminates chattering, and it allows for automatic gain adjustment based on the maneuver and the size of the error, which eliminates the need for gain scheduling. Both fixed and variable gain-sliding mode controllers are derived and compared in simulations to prove the superiority of the variable gain controller. A sliding mode observer is developed to estimate the self-aligning moment disturbance without required information about the tire parameters, which makes it vehicle independent. The observer also treats the static friction as disturbance and estimates it along with any other disturbance, such as driver torque disturbance. The stability of both the controller and the observer is proven using Lyapunov stability theory. Simulation and experimental results proved the robustness of the presented methods to the above challenges.
Assessing the Operation System of Fire Alarm Systems for Detection Line and Circuit Devices with Various Damage Intensities
Authors: Paś Jacek , Rosiński Adam , Wiśnios Michał , Stawowy Marek
Published: April 2022

The paper presents a method for assessing operation processes for Fire Alarm Systems (FAS) applied in civil structures, based on use analysis. Individual FAS devices include components with varying ‘lifetimes’ and damage intensities λ. This is because these elements are operated in different internal and external environments. Probability distributions with various damage λ and recovery µ intensity values must, hence, be taken into account for the FAS operation process and to determine the R(t) reliability. The life cycle of elements comprising a FAS can be divided into three distinguishing time periods. The first is the so-called ‘childhood’. The second, the longest, is characterized by damage intensity λ = const, and the third period is where FAS is unfit more frequently. Based on knowledge of actual FAS operation process data, it is possible to determine damage λ and recovery µ intensity parameters. Such data can be employed to determine FAS reliability parameters within the presented service life intervals. The authors of the article first discuss the basic issues associated with FAS, followed by analyzing the current status of the topic. They also present power supply matters and system solution examples, develop an operation process model and determine selected operational indicators for the structures in question. The paper ends with conclusions.
Hydraulic Tests of the PZ0 Gear Micropump and the Importance Rank of Its Design and Operating Parameters
Authors: Osiński Piotr , Deptuła Adam , Partyka Marian A.
Published: April 2022

This article presents the results of hydraulic tests performed for a prototype gear micropump of a new design. The development of modern hydraulic systems is following two directions: the integration of hydraulic and electronic engineering and a reduction in the mass and the dimensions of the system. The scope of this research involved identifying static characteristics of the prototype gear pump, i.e., its efficiency, torque and power. The tests were performed for PZ0 pumps with the following specific deliveries (which are their design parameters), 0.25 cm3/rev, 0.315 cm3/rev, 0.5 cm3/rev, 0.8 cm3/rev, and 1.0 cm3/rev—with two different types of hydraulic oils, Azolla ZS 22 and HL 68. The operating parameters included the rotational speed, the discharge pressure and the flow rate. The obtained research results suggest an application of the decision tree induction-based classification method for identifying the most important design and operating parameters and their values influencing total efficiency. In addition, the article investigates the influence of rotational speed and specific delivery on total efficiency. The total efficiency translates indirectly into the energy consumption of the solution. The criterion of energy consumption is a key parameter for ecological and economical reasons, related mainly to future operating costs.
A Novel Type of Wave Energy Converter with Five Degrees of Freedom and Preliminary Investigations on Power-Generating Capacity
Authors: Zeng Xiaohui , Wang Qi , Kang Yuanshun , Yu Fajun
Published: April 2022

In order to further improve the power-generating capacity of the wave energy converter (WEC) of oscillating buoy type, this paper puts forward a novel type where the WEC can move and extract power in five degrees of freedom. We make a detailed hydrodynamic analysis of such WECs. Each buoy is modeled as a floating truncated cylinder with five degrees of freedom: surge, sway, heave, roll, and pitch, and there are relative motions among buoys in the array. Linear power take-off (PTO) characteristics are considered for simplicity. Under the linear wave theory, a semi-analytical method based on the eigenfunction expansion and Graf’s addition theorem for Bessel functions is proposed to analyze the hydrodynamic interactions among the WEC array under the action of incident waves, and the amplitude response and power extraction of the WEC array are then solved. After verifying the accuracy of hydrodynamic analysis and calculation, we make preliminary case studies, successively investigating the power-generating capacity of a single WEC, an array of two WECs, and an array of five WEC; then, we compare their results with the conventional heaving WECs. The results show that the WEC with five degrees of freedom can significantly improve the power extraction performance.
Application of Slow Pyrolysis to Convert Waste Plastics from a Compost-Reject Stream into Py-Char
Authors: Iwanek (nee Wilczkowska) Ewa M. , Kirk Donald W.
Published: April 2022

There is growing recognition that the degradation of plastics in the environment is a serious problem. This study investigated and reported on the feasibility of removing end-of-life plastics from circulating in the environment. The specific example focuses on non-recyclable plastics found in a waste diversion program for compostable materials, known as the Green Bin Program. The purpose of this study was to identify and quantify the types of polymers in this stream, as well as to determine if it could be successfully turned into char without separation of its components. The measurements show that polyethylene (72 wt.%), polypropylene (14 wt.%) and polyethylene terephthalate (12 wt.%) are the main constituents of this stream, with minor contributions from polybutylene adipate terephthalate (PBAT), polyvinyl alcohol (PVA), poly methyl methacrylate (PMMA), polystyrene (PS), Nitrile rubber and Nylon. Samples of the as-received waste containing plastics and fibrous material were subjected to a slow pyrolysis process. The yield of the char product depended on the conditions of the pyrolysis and a strong synergistic effect was noted when both the plastic and fibrous materials were co-pyrolyzed. The study of variable pyrolysis conditions, along with DTA-TGA-MS studies on the mechanism of the char formation, indicate that the positive effect results from enhanced interaction of plastics with air, in the presence of fibrous material, during the initial/pre-treatment step.
Dandelion-Root Extract as Green Corrosion Inhibitor for Carbon Steel in CO2-Saturated Brine Solution
Authors: Žbulj Katarina , Hrnčević Lidia , Bilić Gordana , Simon Katarina
Published: April 2022

Recently, due to the corrosion problem in the petroleum industry and the usage of commercial corrosion inhibitors, which, when released untreated into the environment, are considered to be environmentally unfriendly, green corrosion inhibitors are being researched. In this paper, the results of dandelion-root-extract testing as a green corrosion inhibitor for carbon steel in simulated brine solution saturated with carbon dioxide (CO2) are shown. The extract’s inhibition efficiency in static and flow conditions was determined by using potentiodynamic polarization with Tafel extrapolation and electrochemical-impedance-spectroscopy methods. In static conditions, the extract was tested at different concentrations. A maximum inhibition efficiency of 98.37% in static conditions at an extract concentration of 12 mL/L and 82.80% in flow conditions at a concentration of 14 mL/L was achieved. Additionally, for the most efficient dandelion-root-extract concentration (12 mL/L), the biodegradability and toxicity were determined. A biodegradability of 0.96 and a toxicity of 2.38% was achieved. Based on the obtained results of the conducted laboratory measurements, it can be concluded that dandelion-root extract has significant potential in terms of its use as a green corrosion inhibitor for carbon steel in a CO2-saturated brine solution.
Denoising Transient Power Quality Disturbances Using an Improved Adaptive Wavelet Threshold Method Based on Energy Optimization
Authors: Goh Hui Hwang , Liao Ling , Zhang Dongdong , Dai Wei , Lim Chee Shen , Kurniawan Tonni Agustiono , Goh Kai Chen , Cham Chin Leei
Published: April 2022

Noise significantly reduces the detection accuracy of transient power quality disturbances. It is critical to denoise the disturbance. The purpose of this research is to present an improved wavelet threshold denoising method and an adaptive parameter selection strategy based on energy optimization to address the issue of unclear parameter values in existing improved wavelet threshold methods. To begin, we introduce the peak-to-sum ratio and combine it with an adaptive correction factor to modify the general threshold. After calculating the energy of each layer of wavelet coefficient, the scale with the lowest energy is chosen as the optimal critical scale, and the correction factor is adaptively adjusted according to the critical scale. Following that, an improved threshold function with a variable factor is proposed, with the variable factor being controlled by the critical scale in order to adapt to different disturbance types’ denoising. The simulation results show that the proposed method outperforms existing methods for denoising various types of power quality disturbance signals, significantly improving SNR and minimizing MSE, while retaining critical information during disturbance mutation. Meanwhile, the effective location of the denoised signal based on the proposed method is realized by singular value decomposition. The minimum location error is 0%, and the maximum is three disturbance points.
Thermal Characterization and Thermal Effect Assessment of Biofouling around a Dynamic Submarine Electrical Cable
Authors: Maksassi Ziad , Garnier Bertrand , Moctar Ahmed Ould El , Schoefs Franck , Schaeffer Emmanuel
Published: April 2022

Wind energy is expected to play a significant role in meeting emission targets over the next 20 years. Offshore wind turbines in deep water (>150 m) must be developed due to resource quality, environmental, and activity constraints. Floating offshore wind turbines (FOWT) will be the best technology for reaching these targets. The dynamic submarine electrical cable (DSEC) is a key component of FOWT. Its electric insulation system is intended to withstand a maximum conductor temperature of 90 °C. However, biofouling growth, particularly mussels, can modify the heat transfer around the cable and thus its maximum conductor temperature, as well as temperature fluctuation, affecting the fatigue lifetime. In our work we estimate the effective thermal conductivity of mussels of various ages, as well as the heat transfer coefficient of the water around them. The results revealed that the effective thermal conductivity of juvenile mussels is lower than that of mix (both juvenile and adult) and only adult mussels. This variation in effective thermal conductivity with mussel age is related to the water porosity of the mussel’s layer. Then, the thermal effect of the resulting global thermal resistance can lead the DSEC conductor wire to either overheat (colonized by juvenile and mixed mussels) or cool down (colonized by adult mussels). Numerical simulations are used to quantify this effect.
The Influence of Hydrothermal Activity on the Long-Distance Migration and Accumulation of Hydrocarbons: A Case Study from the Y8 Area in the Songnan-Baodao Sag of Qiongdongnan Basin
Authors: Gan Jun , Xiong Shuling , Liang Gang , Gao Zhiye , Li Xing , Yang Wei , Jiang Zhenxue , Wang Yaohua
Published: April 2022

The Qiongdongnan (QDN) basin in the northwestern South China Sea has been shown to be rich in petroleum resources and has significant exploration potential for deepwater oil and gas resources. Therefore, it is of great significance to clarify the gas accumulation process in the deepwater area of the QDN basin, specifically the Y8 area. In this study, fluid inclusion analysis, including the identification and localization of fluid inclusions under a microscope, laser Raman spectrum analysis and homogenization temperature (Th) measurement, reconstruction of the thermal evolution burial history, geochemical analysis, and typical seismic section analysis were comprehensively used to interpret the gas accumulation process of the Y8 area. The laser Raman spectrum analysis results of fluid inclusions verified the existence of methane and confirmed the hydrocarbon charging event in this area. However, the Th of fluid inclusions in the reservoir, the mixed compositions of hydrothermal compositions (H2S + SO2) and hydrocarbons (methane) in the fluid inclusions, and the low Tmax values of some wells in the Y8 area comprehensively confirmed that the coincidence of hydrothermal activity with the accumulation process affected the long-distance gas accumulation of the Y8 area. The hydrothermal activity was also confirmed by the presence of fluid diapirs in seismic profiles of the Y8 area. Furthermore, the hydrocarbon accumulation process was reconstructed using the modified thermal evolution history considering the effect of hydrothermal activity. Overall, this study attributed the high Th of fluid inclusions in the reservoirs of the Y8 area to hydrothermal activity and proposed a long-distance migration model of hydrocarbon accumulation coinciding with hydrothermal activity, both of which are beneficial to understanding the accumulation process of the Y8 area.
Optimization of Heat Exchanger Network via Pinch Analysis in Heat Pump-Assisted Textile Industry Wastewater Heat Recovery System
Authors: Kim Yurim , Lim Jonghun , Shim Jae Yun , Hong Seokil , Lee Heedong , Cho Hyungtae
Published: April 2022

Reactive dyeing is primarily used in the textile industry to achieve a high level of productivity for high-quality products. This method requires heating a large amount of freshwater for dyeing and cooling for the biological treatment of discharged wastewater. If the heat of the wastewater discharged from the textile industry is recovered, energy used for heating freshwater and cooling wastewater can be significantly reduced. However, the energy efficiency of this industry remains low, owing to the limited use of waste heat. Hence, this study suggested a cost-optimal heat exchanger network (HEN) in a heat pump-assisted textile industry wastewater heat recovery system with maximizing energy efficiency simultaneously. A novel two-step approach was suggested to develop the optimal HEN in heat pump-assisted textile industry wastewater heat recovery system. In the first step, the system was designed to integrate the heat exchanger and heat pump to recover waste heat effectively. In the second step, the HEN in the newly developed system was retrofitted using super-targeted pinch analysis to minimize cost and maximize energy efficiency simultaneously. As a result, the proposed wastewater heat recovery system reduced the total annualized cost by up to 43.07% as compared to the conventional textile industry lacking a wastewater heat recovery system. These findings may facilitate economic and environmental improvements in the textile industry.
Next-Generation Wireless Charging Systems for Mobile Devices
Authors: Park Young-Jin
Published: April 2022

Wireless power transfer (WPT) is currently sparking more attention towards the application of wireless charging for mobile devices and electric vehicles [...]
Use of Recurrent Neural Network with Long Short-Term Memory for Seepage Prediction at Tarbela Dam, KP, Pakistan
Authors: Ishfaque Muhammad , Dai Qianwei , Haq Nuhman ul , Jadoon Khanzaib , Shahzad Syed Muzyan , Janjuhah Hammad Tariq
Published: April 2022

Estimating the quantity of seepage through the foundation and body of a dam using proper health and safety monitoring is critical to the effective management of disaster risk in a reservoir downstream of the dam. In this study, a deep learning model was constructed to predict the extent of seepage through Pakistan’s Tarbela dam, the world’s second largest clay and rock dam. The dataset included hydro-climatological, geophysical, and engineering characteristics for peak-to-peak water inflows into the dam from 2014 to 2020. In addition, the data are time series, recurring neural networks (RNN), and long short-term memory (LSTM) as time series algorithms. The RNN–LSTM model has an average mean square error of 0.12, and a model performance of 0.9451, with minimal losses and high accuracy, resulting in the best-predicted dam seepage result. Damage was projected using a deep learning system that addressed the limitations of the model, the difficulties of calculating human activity schedules, and the need for a different set of input data to make good predictions.
Energy Balance Control for Improving Transient Performance of DC Bus Voltage in Power Electronic Transformer for the Voltage-Sensitive Loads
Authors: Feng Gaohui , Bu Pengsheng , Yuan Liqiang
Published: April 2022

The power electronic transformer (PET), as a main topology for the energy router in the energy internet, consists of the rectifiers, the dual active bridge (DAB), and the inverter, and these three parts are connected by two dc buses. So, the performance of the dc bus voltages is very important because it can totally affect the output waveforms of the dc and ac voltage, especially for the voltage-sensitive loads. Compared with the proportion integration (PI) control scheme, the energy control method utilizes the energy as the control variable, and the control strategy derived from the energy relationship, including the passive elements and all the interfaces, is more direct and explicit. In this paper, considering the energy between the dc bus capacitors and the input inductor and the load and the source in the PET topology, the energy balance control (EBC) strategy is proposed. For the two dc bus voltages, the energy balance relationship of the different time scales is used to decouple the interaction in the control scheme. The EBC strategy can obviously reduce the fluctuation and the transient time of the two dc bus voltages when the load power or voltage reference is changed. Thus, under the limited voltage fluctuation, the EBC strategy can reduce the dc bus capacitance in order to reduce the volume and weight of the converter and enhance the reliability. The simulation and experimental results verify the effectiveness of the proposed control strategy.
Relationship between Ultraviolet-B Radiation and Broadband Solar Radiation under All Sky Conditions in Kuwait Hot Climate
Authors: Kadad Ibrahim M. , Ramadan Ashraf A. , Kandil Kandil M. , Ghoneim Adel A.
Published: April 2022

In the present study, continuous measurements of solar global (G) and ultraviolet-B (UVB) radiation are taken in Kuwait for 2014–2019 for all weather conditions. Hourly curves show a sinusoidal behavior for both G and UVB radiation. Statistical analysis indicates that there is a good agreement between hourly G and hourly UVB as the coefficients of determination (R2) for all years are larger than 0.91 and the root-mean-square error (RMSE) and mean bias error (MBE) are very small. The hourly percentage ratio (UVB/G) is found to decrease with G due to cloudy sky conditions. In addition, the ratio (UVB/G) tends to decrease with global clearness index (KT), indicating that a higher ratio of (UVB/G) can be obtained for a cloudier atmosphere. Another interesting finding is that KT and the UVB index (KTUVB) are directly proportional, and a third-order polynomial fit gives an acceptable formula (R2 = 0.859). Daily G and UVB values are very well correlated as R2 is very close to unity for all years. The values of RMSE and MBE obtained from daily analysis are greatly enhanced as the values of RMSE and MBE are almost zero. The maximum G and UVB radiation obtained is 27.94 MJ/m2 and 0.0044 MJ/m2, respectively, with both occurring in June 2015. Finally, there is an excellent linear fit between the monthly G and monthly UVB radiation as R2 is almost equal to unity and RMSE and MBE are negligible. Thus, the predicted daily or monthly empirical formula can be utilized with a very high accuracy to predict both daily and monthly UVB values at locations in Kuwait where G is measured.
One-Shot Fault Diagnosis of Wind Turbines Based on Meta-Analogical Momentum Contrast Learning
Authors: Liu Xiaobo , Guo Hantao , Liu Yibing
Published: April 2022

The rapid development of artificial intelligence offers more opportunities for intelligent mechanical diagnosis. Fault diagnosis of wind turbines is beneficial to improve the reliability of wind turbines. Due to various reasons, such as difficulty in obtaining fault data, random changes in operating conditions, or compound faults, many deep learning algorithms show poor performance. When fault samples are small, ordinary deep learning will fall into overfitting. Few-shot learning can effectively solve the problem of overfitting caused by fewer fault samples. A novel method based on meta-analogical momentum contrast learning (MA-MOCO) is proposed in this paper to solve the problem of the very few samples of wind turbine failures, especially one-shot. By improving the momentum contrast learning (MOCO) and using the training idea of meta-learning, the one-shot fault diagnosis of wind turbine drivetrain is analyzed. The proposed model shows a higher accuracy than other common models (e.g., model-agnostic meta-learning and Siamese net) in one-shot learning. The feature embedding is visualized by t-distributed stochastic neighbor embedding (t-SNE) in order to test the effectiveness of the proposed model.
Evaluation of the Implementation Effect of China’s Industrial Sector Supply-Side Reform: From the Perspective of Energy and Environmental Efficiency
Authors: Dong Si-Si , Qi Liang-Qun , Li Jia-Quan
Published: April 2022

The analysis of the implementation effect of the supply-side reform (SSR) in the industrial sector of China’s provinces and the reasons behind them are of great significance for China to formulate relevant policies in the future. However, this work has not yet been carried out. Industrial development performance is closely related to energy and environmental efficiency (EEE), and the effect of the SSR implementation is directly reflected in EEE. This study fills this gap by analyzing the EEE of 30 provinces in China from 2012 to 2017 using data envelopment analysis and Malmquist index methods. The results show that the positive effect of China’s implementation of SSR has emerged. This positive effect is mainly reflected in the implementation of measures such as reducing overcapacity, which has promoted the technological innovation of enterprises. However, the low management level and resource-allocation efficiency hinder the further improvement of the implementation effect of the SSR, which should be paid special attention to in China’s future supply-side reform. In addition, we believe that in the context of China’s high-quality development and carbon neutrality goals, the SSR should be given more connotations, which are to increase the requirements for strengthening green and low-carbon development.
On Solar Radiation Prediction for the East–Central European Region
Authors: Mierzwiak Michał , Kroszczyński Krzysztof , Araszkiewicz Andrzej
Published: April 2022

The aim of this paper is to present the results of the Weather Research and Forecasting (WRF) model of solar radiation for moderate climatic zones. This analysis covered the area of northeastern Germany. Due to very unfavorable solar energy conditions in this region for at least 1/3 of the year, we decided to select the dates with the most representative conditions: passing warm fronts, cold fronts, and occluded fronts (two cases each). As the reference, two cloudless conditions during high-pressure situations were chosen. Two different shortwave radiation schemes—Rapid Radiative Transfer Model for general circulation model (RRTMG) and Dudhia—were tested. The obtained results were compared with in situ data measured at Deutscher Wetterdienst (DWD) stations and then with European Medium-Range Weather Forecast reanalysis (ERA5) data. The results showed that for high-pressure situations, the mean correlations with measured data were above 90%. The Dudhia scheme, in addition to the expected good results for the high-pressure situation, showed better results than RRTMG for the warm and cold fronts as well. The forecast using the RRTMG scheme gave the best results for the occluded front, which were also better than those of the ERA5 model.
A Flexible-Reliable Operation Model of Storage and Distributed Generation in a Biogas Power Plant
Authors: Lautert Renata Rodrigues , Brignol Wagner da Silva , Canha Luciane Neves , Adeyanju Olatunji Matthew , Garcia Vinícius Jacques
Published: April 2022

This paper presents a novel methodology for planning and operating biogas energy systems based on the transactive energy concept to determine multilevel operating regimes for distributed generation. The developed model is used to manage the production, storage, and dispatch of biogas energy systems to meet the load demands of the biogas producer and support the operation of the distribution network operator. An Integer Linear Programming (ILP) is fitted to optimize the biogas production of the biogas producer, including the operation of the biogas storage systems and their interaction with the network operator. The model’s objective is to maximize benefits for the participating agents in a transactive energy context. The model’s effectiveness is validated using seven case studies involving biogas systems having different operating ranges and modes to achieve enhanced flexibility and reliability for the system operation with a large proportion of intermittent energy resources. The simulation results showed that the approach could effectively manage the operation of biogas systems and their interaction with the network operator. The developed model is suitable for systems fostering net metering charging and real-time pricing.
Impact of Gas Saturation and Gas Column Height at the Base of the Gas Hydrate Stability Zone on Fracturing and Seepage at Vestnesa Ridge, West-Svalbard Margin
Authors: Ramachandran Hariharan , Plaza-Faverola Andreia , Daigle Hugh
Published: April 2022

The Vestnesa Ridge, located off the west Svalbard margin, is a >60 km long ridge consisting of fine-grained sediments that host a deep-marine gas hydrate and associated seepage system. Geological and geophysical observations indicate the predominance of vertical fluid expulsion through fractures with pockmarks expressed on the seafloor along the entire ridge. However, despite the apparent evidence for an extended free gas zone (FGZ) below the base of the gas hydrate stability zone (BGHSZ), present-day seafloor seepage has been confirmed only on the eastern half of the sedimentary ridge. In this study, we combine the relationships between aqueous phase pressure, capillary pressure, sediment clay fraction, porosity, and total stress to simulate how much gas is required to open preexisting fractures from the BGHSZ towards the seafloor. Data from four specific sites with different lithology and pressure regime along the ridge are used to constrain the simulations. Results demonstrate that fracturing is favored from the FGZ (with gas saturations < 0.1 and gas column heights < 15 m) towards the seafloor. Neglecting the capillary pressure overpredicts the size of the gas column by up to 10 times, leading to erroneous maximum gas vent volume predictions and associated ocean biosphere consequences. Further parametric analyses indicate that variations in the regional stress regime have the potential to modify the fracture criterion, thus driving the differences in venting across the ridge. Our results are in line with independent geophysical observations and petroleum system modeling in the study area, adding confidence to the proposed approach and highlighting the importance of the capillary pressure influence on gas pressure.
Studying the Bond Performance of Full-Grouting Rock Bolts Based on the Variable Controlling Method
Authors: Chen Jianhang , Ding Ziwei , Wu Saisai , Zhang Junwen
Published: April 2022

This paper studied the bond performance of full-grouting rock bolts with a theoretical analysis. The variable controlling method was used to study the effect of parameters on the load-carrying force of bars. The results showed that when the bar diameter grew from 15 mm to 25 mm, the maximum force of the bars rose from 194 kN to 349 kN, growing by 80%. As for the stiffness, it grew by 108%. Moreover, when the elastic modulus grew from 50 GPa to 200 GPa, the maximum force rose from 229 kN to 269 kN, only growing by 17%. As for the stiffness, it grew by 100%. When the grouting length increased from 2 m to 3 m, the maximum force rose from 269 kN to 364 kN, growing by 35%. However, the grouting length had almost no effect on the stiffness. Lastly, for the bond slip when the bond strength was reached, when it grew from 1 mm to 3 mm, the maximum force dropped from 281 kN to 258 kN, dropping by 8%. As for the stiffness, it dropped by 44%. This paper is conducive to enriching the base of knowledge.
Synthesis of Heat-Integrated Water Networks Using a Modified Heat Exchanger Network Superstructure
Authors: Ibrić Nidret , Ahmetović Elvis , Nemet Andreja , Kravanja Zdravko , Grossmann Ignacio E.
Published: April 2022

This work presents the synthesis of heat-integrated water networks (HIWNs) by using mathematical programming. A new superstructure is synthesised by combining a water network and a modified heat exchanger network. Based on the proposed superstructure, a mixed-integer nonlinear programming (MINLP) model is developed. The model is solved by using a one-step solution strategy enabling different initialisations and the generation of multiple solutions, from which the best one is chosen. The results show that the proposed model can be effectively used for solving HIWN problems of different complexities, including large-scale problems.
Analyzing Wind Energy Potential Using Efficient Global Optimization: A Case Study for the City Gdańsk in Poland
Authors: Aydin Olgun , Igliński Bartłomiej , Krukowski Krzysztof , Siemiński Marek
Published: April 2022

Wind energy (WE), which is one of the renewable energy (RE) sources for generating electricity, has been making a significant contribution to obtaining clean and green energy in recent years. Fitting an appropriate statistical distribution to the wind speed (WS) data is crucial in analyzing and estimating WE potential. Once the best suitable statistical distribution for WS data is determined, WE potential and potential yield could be estimated with high accuracy. The main objective of this paper is to propose a novel approach for calculating wind energy potential. For this purpose, the Efficient Global Optimization (EGO) technique was proposed for fitting a statistical distribution to WS data and the performance of the technique was compared with genetic algorithm (GA), simulated annealing (SA), and differential evolution (DE). Performance metrics showed that EGO is providing better estimations compared with GA, SA, and DE. Based on Weibull parameters obtained by using EGO, potential WE and potential annual revenue were estimated for Gdańsk, which is the capital of Pomerania Voivodeship in Poland, in the case of having city-type wind turbines in the city center. Estimations for Gdańsk showed that city-type wind turbines might be helpful for producing electricity from WE in the city without being limited by constraints such as having a long distance between wind turbines and buildings. If such wind turbines were erected on the roofs of residential buildings, malls, or office buildings, there is a possibility that part of the electric energy needed for such buildings could be generated using WE. However, this topic should be further investigated from technical and financial perspectives.
Design Optimization of a Direct-Drive Electrically Excited Synchronous Generator for Tidal Wave Energy
Authors: Ousmane Samb Serigne , Bernard Nicolas , Fouad Benkhoris Mohamed , Kien Bui Huu
Published: April 2022

In the field of marine renewable energies, the extraction of marine currents by the use of tidal current turbines has led to many studies. In contrast to offshore wind turbines, the mass minimization is not necessarily the most important criterion. In that case, Direct-Drive Electrically Excited Synchronous Generators (EESG) can be an interesting solution in a context where the permanent magnet market is more and more stressed. In the particular case of a tidal turbine, the electric generator operates at variable torque and speed all the time. Its sizing must therefore take into account the control strategy and check that all the constraints are respected during the working cycle, particularly the thermal one because its permanent regime is never reached. There is no solution today that can completely solve such a sizing problem. The paper presents a specific solution. In particular, we will see that the method presented allows an avoidance of an oversizing of the generator compared to conventional methods while finding the optimal control strategy. Thus, the design optimization of an EESG is conducted considering the variable torque and speed profiles related to marine currents. The analytical model used in the paper is presented at first. In a second step, the innovative and original method that allows solving at the same time the design optimization and the control strategy (dq stator currents and rotor current) are presented. It shows how it is possible to minimize both the lost energy during the working cycle and the mass while fulfilling all the constraints (especially the thermal constraint with its transient temperature response) and keeping a reduced computation time. The case of a 2 MW tidal wave turbine is chosen to illustrate this study. Finally, the optimal design selected is validated by a 2D magnetic Finite Element Analysis (FEA).
To Boost or Not to Boost: Acceptability of a COVID-19 Booster Dose among Osteopathic Medical Students: A Cross-Sectional Study from a Medical School in New York
Authors: Al Janabi Taysir , Pino Maria
Published: April 2022

The COVID-19 pandemic continues to evolve, with new variants emerging and vaccine-induced immunity waning. Protecting and retaining the healthcare force remains crucial in fighting this pandemic, as healthcare workers (HCWs) are a critical driver in increasing vaccine uptake among the public. This study explored the uptake of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) booster shots among medical students at the New York Institute of Technology College of Osteopathic Medicine (NYITCOM). Predictors for actual booster uptake were also examined. An electronic survey was distributed to Osteopathic Medical Students (OMS I-IV) in January 2022. The survey was distributed to 1762 students total, with 319 responses received (18%). Of those who responded, 70.2% (224/319) reported that they had already received a booster, while 29.5% (94/319) reported they had not yet received it. We identified that pharmaceutical mistrust, building long-lasting immunity via vaccines, and vaccines’ adverse effects were the most significant predictors for how willing participants were to accept a booster dose. Vaccine hesitancy around the COVID-19 booster was prevalent during the surge of the highly transmissible variant Omicron. This finding necessitates some evidence-based approaches to enhance booster uptake among a population subgroup whose impact is critical.
Experimental Study of the Source of CO Anomalies in Mines Based on Microscopic Changes
Authors: Zhang Jiuling , Ruan Gaoyang , Chen Jianguang
Published: April 2022

The phenomenon of abnormal CO emergence occurred in a working face of Tangshan mine, and the CO source was analyzed from the two perspectives of CO detection method optimization and microstructure changes in the low-temperature environment of the coal body. Then, the critical index system was optimized. The CO identification tube test results and gas chromatograph test results are combined to derive a fitting formula, and the CO identification tube test results are used as the independent variable to obtain the gas chromatograph test results, which can effectively eliminate the error of small CO identification tube test results. The analysis of raw coal and coal samples heated by water bath at 30 °C, 40 °C, and 50 °C was carried out using low temperature liquid nitrogen adsorption and thermogravimetric and infrared spectroscopy experiments. It was found that the pore structure of the coal body developed as the temperature increased; the oxidation reaction occurred in the low-temperature state when heat was absorbed to produce CO. The thermal decomposition of carbonyl group was found to be the main source of CO. Finally, the index of spontaneous combustion of coal is optimized according to the temperature, and the index systems represented by O2/(CO2+CO), CH4 and CO2/CO were determined from 30~80 °C, 90~180 °C and 18~240 °C, respectively.
A Numerical Study on Distant Tsunami Propagation Considering the Strong Nonlinearity and Strong Dispersion of Waves, or the Plate Elasticity and Mantle Fluidity of Earth
Authors: Kakinuma Taro
Published: April 2022

Numerical simulations were generated to investigate the propagation processes of distant tsunamis, using a set of wave equations based on the variational principle considering both the strong nonlinearity and strong dispersion of waves. First, we proposed estimate formulae for the time variations of the tsunami height and wavelength of the first distant tsunami, by assuming that the initial tsunami profile was a long crest in a uniform bathymetry. Second, we considered the plate elasticity and upper-mantle fluidity of Earth, to examine their effects on the distant tsunami propagation. When the plate and upper mantle meet certain conditions with both a large depth and moderately large density of the upper mantle, the internal-mode tsunamis with a significant tsunami height propagated slower than the tsunamis in the corresponding one-layer problems, leading to the delay of the arrival time observed in distant tsunamis from that evaluated by the one-layer calculation.
Numerical Simulation of High-Density Ratio Bubble Motion with interIsoFoam
Authors: Siriano Simone , Balcázar Néstor , Tassone Alessandro , Rigola Joaquim , Caruso Gianfranco
Published: April 2022

The breeding blanket is one of the fundamental components of a nuclear fusion reactor and is responsible for the fuel production, generating tritium through neutronic capture reaction between lithium and neutrons. Lithium is a liquid PbLi alloy and the helium formed as reaction by-product can coalesce into bubbles, generating a two-phase mixture with a high-density ratio (ηρ∼O5). These bubbles can accumulate and stagnate within the blanket channels with potentially harmful consequences. In this work, the interIsoFoam solver of OpenFOAM v2012 is used to simulate bubble motion for a two-phase mixture representative of the He-PbLi system to test its potential for future developments in the field of fusion. In a first phase, several traditional benchmarks were carried out, both 2D and 3D, and considering the two variants of the VOF method implemented in the solver, isoAdvector and plicRDF. Subsequently, He bubbles of different diameters rising in liquid PbLi (ηρ=1.2×105) were analysed to investigate different regimes. For a Eötvös number (Eo) greater than 10, it was possible to recreate the axisymmetric, skirted, oscillatory regimes and the peripheral and central breakup regimes. For Eo < 10, non-physical deformations of the interface are observed, probably generated by spurious velocities that have a greater impact on the solution for very small bubbles and rising velocities.
RANS Modelling of a NACA4412 Wake Using Wind Tunnel Measurements
Authors: Tabatabaei Narges , Hajipour Majid , Mallor Fermin , Örlü Ramis , Vinuesa Ricardo , Schlatter Philipp
Published: April 2022

Wake analysis plays a significant role in wind-farm planning through the evaluation of losses and energy yield. Wind-tunnel tests for wake studies have high costs and are time-consuming. Therefore, computational fluid dynamics (CFD) emerges as an efficient alternative. An especially attractive approach is based on the solution of the Reynolds-averaged Navier–Stokes (RANS) equations with two-equation turbulence closure models. The validity of this approach and its inherent limitations, however, remain to be fully understood. To this end, detailed wind-tunnel experiments in the wake of a NACA4412 wing section profile are compared with CFD results. Two- and three-dimensional RANS simulations are carried out for a range of angles of attack up to stall conditions at a chord- and inflow-based Reynolds number of Rec=4×105. Here, we aim to investigate the wake characteristics and self-similar behaviour, both from the experimental and numerical perspectives. The measurements are carried out by means of hot-wire anemometry capturing the wake pattern in several planes. The sensitivity of the CFD model to different configurations of the setup and the considerations required for reliable simulation are discussed. The agreement between CFD, experiments, and the literature is fairly good in many aspects, including the self-similar behaviour and wake parameters, as well as the flow field. Comparison of experiments with URANS/RANS data indicates that the latter is an adequate methodology to characterize wings and their wakes once the CFD setup is designed appropriately and the limitations due to discretization and turbulence modelling are considered.