bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimization of Multi-Track Laser-Cladding Process of Titanium Alloy Based on RSM and NSGA-II Algorithm
Authors: Shu Linsen , Li Jiahao , Wu Han , Heng Zhao
Published: September 2022

Titanium alloy is an important material in the 21st century and its consumption in the aerospace and energy fields is increasing. In the production and repair of titanium alloy, the problem of energy saving and consumption reduction is becoming increasingly important. Laser-cladding technology with optimized parameters can bring great economic benefit. In order to obtain the best process parameters of laser-cladding TC4 alloy powder, a method of laser-cladding parameters’ optimization based on the RSM and NSGA-II Algorithm is proposed. The BBD (Box–Behnken Design) experiment scheme was designed by the response surface method. A surrogate model between input variables (laser power, scanning speed, and powder-feeding speed) and response values (macroscopic quality, microhardness, and average friction coefficient) was established. The second generation non-dominant sorting genetic algorithm (NSGA-II) was used to optimize the process parameters and the optimization results were verified by experiments. The results show that the optimum parameters are a laser power of 2600 W, scanning speed of 19.1 mm/s, and powder-feeding rate of 12.2 g/min. The samples prepared with the best process parameters show mainly abrasive wear, accompanied by a small amount of adhesive wear. Its wear depth is 7.71 μm and the average friction coefficient is 0.293. After cladding, the macroscopic quality of the cladding layer is increased by 5.8%, the microhardness is increased by 10.1%, and the average friction coefficient is reduced by 27.6%.
Thermal Analysis of Mullite Coated Piston Used in a Diesel Engine
Authors: Shu Zihao , Deng Jun , Qian Zuoqin , Fei Chunguang , Zhu Siwei , Du Yuxuan , Zhou Kai
Published: September 2022

Due to special working conditions, diesel engines often need to run stably for a long time at high power operating conditions. As the core of diesel engine moving parts, the piston needs to be exposed to high temperature for a long time. Based on the problem of excessive piston temperature at the maximum power point of a certain type of diesel engine, this paper discussed the protective effect of using different thicknesses of Mullite thermal barrier coating on the top surface of the piston, by using the method of hardness plug temperature measurement and three-dimensional simulation. When the thickness of the ceramic coating was increased from 0.2 to 0.7 mm, the maximum temperature of the piston seat decreased from 358.6 to 338.9 °C. This showed that the use of Mullite thermal barrier coating could reduce the working temperature of the aluminum alloy piston at the maximum load operating point, and greatly improve the reliability of engine components.
Assessing the Predatory Effects of Invasive Brown Trout on Native Rio Grande Sucker and Rio Grande Chub in Mountain Streams of New Mexico, USA
Authors: Ivie Jansen , George Owen , Collins Scott F.
Published: September 2022

Invasive predators pose a critical threat to native taxa. Body size plays an important role in mediating the interactions of predator and prey. For piscivorous fishes, increased predator body size can be accompanied by the selection of increasingly larger prey or may reflect a mix of small and large prey. Knowledge of such interactions helps determine how predation affects population vital rates. Here, we assessed the predatory effects of invasive Brown Trout (Salmo trutta) on populations of native Rio Grande Sucker (Catostomus plebeius) and Rio Grande Chub (Gila pandora) in streams of the Jemez River watershed (New Mexico, USA). Trout diets were sampled every two weeks during the 2020 growing season. Predator and prey body lengths were measured to examine relationships to better understand patterns of piscivory and quantify the threat Brown Trout pose to populations of Rio Grande Chub and Rio Grande Sucker. Across all streams and sampling dates, 7% of Brown Trout diets contained fish. Predator–prey length relationships reflected a ‘wedge’ pattern, indicating that Brown Trout consumed an increasing range of prey body sizes as they grew larger. Rio Grande Sucker and Rio Grande Chub comprised 46% of consumed fishes. The findings demonstrated that Rio Grande Sucker and Rio Grande Chub experience constant predation over the growing season by Brown Trout. Moreover, our study provides evidence that these invasive predators pose a threat to the viability of Rio Grande Chub and Rio Grande Sucker populations. Conservation efforts to protect these chub and sucker populations must account for and directly address predation by invasive Brown Trout.
The Impact of Exercise on Cardiotoxicity in Pediatric and Adolescent Cancer Survivors: A Scoping Review
Authors: Kendall Stephanie J. , Langley Jodi E. , Aghdam Mohsen , Crooks Bruce N. , Giacomantonio Nicholas , Heinze-Milne Stefan , Johnston Will J. , Keats Melanie R. , Mulvagh Sharon L. , Grandy Scott A.
Published: September 2022

Childhood and adolescent cancer survivors are disproportionately more likely to develop cardiovascular diseases from the late effects of cardiotoxic therapies (e.g., anthracycline-based chemotherapy and chest-directed radiotherapy). Currently, dexrazoxane is the only approved drug for preventing cancer treatment-related cardiac damage. While animal models highlight the beneficial effects of exercise cancer treatment-related cardiac dysfunction, few clinical studies have been conducted. Thus, the objective of this scoping review was to explore the designs and impact of exercise-based interventions for managing cancer treatment-related cardiac dysfunction in childhood and adolescent cancer survivors. Reviewers used Joanna Briggs Institute’s methodology to identify relevant literature. Then, 4616 studies were screened, and three reviewers extracted relevant data from six reports. Reviewers found that exercise interventions to prevent cancer treatment-related cardiac dysfunction in childhood and adolescent cancer survivors vary regarding frequency, intensity, time, and type of exercise intervention. Further, the review suggests that exercise promotes positive effects on managing cancer treatment-related cardiac dysfunction across numerous indices of heart health. However, the few clinical studies employing exercise interventions for childhood and adolescent cancer survivors highlight the necessity for more research in this area.
Detection and Monitoring of Riverine Dragonfly of Community Interest (Insecta: Odonata): Proposal for a Standardised Protocol Based on Exuviae Collection
Authors: Arguel Loan , Denis Alice S. , Danflous Samuel , Gouix Nicolas , Santoul Frédéric , Buisson Laëtitia , Pelozuelo Laurent
Published: September 2022

Collecting quantitative data on insect species occurrence and abundance is a major concern to document population trends. This is especially the case to assess the conservation status of species listed in the European Habitats Directive and to assess the efficiency of mitigation measures with a view to achieve the “no net loss of biodiversity” goal for protected species. However, at present, populations of riverine dragonflies listed in the Habitats Directive and protected under French national law are poorly quantified and monitored. Exuviae collection could be used for such monitoring but a standardised protocol is lacking. We here proposed and tested such a protocol to monitor riverine dragonfly populations through exhaustive exuviae collection along river bank transects. To define the optimal transect size and number of visits, ninety-eight 100 m-long transects divided into 10 m-long plots were monitored on three rivers in southern France. Each transect was visited three times over the emergence period. In the course of each visit, all the exuviae along transects were collected and identified. From our results, we recommend collecting exuviae along 100 m of river bank in the course of two visits in order to both maximise the species detection and minimise the monitoring cost.
New Perspectives on the Importance of Cell-Free DNA Biology
Authors: Bronkhorst Abel J. , Ungerer Vida , Oberhofer Angela , Gabriel Sophie , Polatoglou Eleni , Randeu Hannah , Uhlig Carsten , Pfister Heiko , Mayer Zsuzsanna , Holdenrieder Stefan
Published: September 2022

Body fluids are constantly replenished with a population of genetically diverse cell-free DNA (cfDNA) fragments, representing a vast reservoir of information reflecting real-time changes in the host and metagenome. As many body fluids can be collected non-invasively in a one-off and serial fashion, this reservoir can be tapped to develop assays for the diagnosis, prognosis, and monitoring of wide-ranging pathologies, such as solid tumors, fetal genetic abnormalities, rejected organ transplants, infections, and potentially many others. The translation of cfDNA research into useful clinical tests is gaining momentum, with recent progress being driven by rapidly evolving preanalytical and analytical procedures, integrated bioinformatics, and machine learning algorithms. Yet, despite these spectacular advances, cfDNA remains a very challenging analyte due to its immense heterogeneity and fluctuation in vivo. It is increasingly recognized that high-fidelity reconstruction of the information stored in cfDNA, and in turn the development of tests that are fit for clinical roll-out, requires a much deeper understanding of both the physico-chemical features of cfDNA and the biological, physiological, lifestyle, and environmental factors that modulate it. This is a daunting task, but with significant upsides. In this review we showed how expanded knowledge on cfDNA biology and faithful reverse-engineering of cfDNA samples promises to (i) augment the sensitivity and specificity of existing cfDNA assays; (ii) expand the repertoire of disease-specific cfDNA markers, thereby leading to the development of increasingly powerful assays; (iii) reshape personal molecular medicine; and (iv) have an unprecedented impact on genetics research.
Detecting a Photon-Number Splitting Attack in Decoy-State Measurement-Device-Independent Quantum Key Distribution via Statistical Hypothesis Testing
Authors: Chen Xiaoming , Chen Lei , Yan Yalong
Published: September 2022

Measurement-device-independent quantum key distribution (MDI-QKD) is innately immune to all detection-side attacks. Due to the limitations of technology, most MDI-QKD protocols use weak coherent photon sources (WCPs), which may suffer from a photon-number splitting (PNS) attack from eavesdroppers. Therefore, the existing MDI-QKD protocols also need the decoy-state method, which can resist PNS attacks very well. However, the existing decoy-state methods do not attend to the existence of PNS attacks, and the secure keys are only generated by single-photon components. In fact, multiphoton pulses can also form secure keys if we can confirm that there is no PNS attack. For simplicity, we only analyze the weaker version of a PNS attack in which a legitimate user’s pulse count rate changes significantly after the attack. In this paper, under the null hypothesis of no PNS attack, we first determine whether there is an attack or not by retrieving the missing information of the existing decoy-state MDI-QKD protocols via statistical hypothesis testing, extract a normal distribution statistic, and provide a detection method and the corresponding Type I error probability. If the result is judged to be an attack, we use the existing decoy-state method to estimate the secure key rate. Otherwise, all pulses with the same basis leading to successful Bell state measurement (BSM) events including both single-photon pulses and multiphoton pulses can be used to generate secure keys, and we give the formula of the secure key rate in this case. Finally, based on actual experimental data from other literature, the associated experimental results (e.g., the significance level is 5%) show the correctness of our method.
An Open Digital Platform to Support Interdisciplinary Energy Research and Practice—Conceptualization
Authors: Ferenz Stephan , Ofenloch Annika , Penaherrera Vaca Fernando , Wagner Henrik , Werth Oliver , Breitner Michael H. , Engel Bernd , Lehnhoff Sebastian , Nieße Astrid
Published: September 2022

Energy research itself is changing due to digitalization and the trend to open science. While this change enables new research, it also increases the amount of, and need for, available data and models. Therefore, a platform for open digital energy research and development is required to support researchers and practitioners with their new needs and to enable FAIR (findable, accessible, interoperable and reusable) research data management in energy research. We present a functional and technological concept for such a platform based on six elements: Competence to enable researchers and practitioners to find suitable partners for their projects, Methods to give an overview on the diverse possible research methods within energy research, Repository to support finding data and models for simulation of energy systems, Simulation to couple these models and data to create user-defined simulation scenarios, Transparency to publish results and other content relevant for the different stakeholder in energy research, and Core to interconnect all elements and to offer a unified entry point. We discuss the envisioned use of the outlined platform with use cases addressing three relevant stakeholder groups.
Perceived Barriers to Nearly Zero-Energy Housing: Empirical Evidence from Kilkenny, Ireland
Authors: Souaid Cynthia , van der Heijden Harry , Elsinga Marja
Published: September 2022

In 2010, the Energy Performance of Buildings Directive announced that all new buildings are to be nearly zero-energy as of January 2021. Having reached year 2022, it can be said that the transition has proven to be slower than anticipated. Transition research has long acknowledged the potential impact of the human factor in the process of change. While there is a relative wealth of literature on end-users and their perceptions as recipients of change within the demand end of the market, research on professionals and their perceptions as actors in the process of change is limited. Thus, this study looks at the human factor in the supply end of the market by bringing professionals’ perceptions to the forefront in its investigation of barriers to the implementation and uptake of nearly zero-energy housing in practice. As part of the project entitled Housing 4.0 Energy: Affordable and Sustainable Housing through Digitization, data were collected through a focus group and semi-structured interviews with housing professionals in Kilkenny, Ireland. Descriptive coding, inferential coding, and fact tracing revealed several identified barriers to be perceptions and not actual barriers to nearly zero-energy housing. Additionally, information dissemination and assimilation between policy and industry was identified as an overarching barrier. Therefore, the paper ends with recommendations to reduce delay factors at the supply end of the market, thus contributing to closing the gap between the development of policies and their implementation.
Synthesis of Biodiesel from Ricinus communis L. Seed Oil, a Promising Non-Edible Feedstock Using Calcium Oxide Nanoparticles as a Catalyst
Authors: Ahmad Jan Hammad , Šurina Igor , Zaman Akhtar , Al-Fatesh Ahmed S. , Rahim Fazli , Al-Otaibi Raja L.
Published: September 2022

This work aimed to synthesize biodiesel from Ricinus communis L., using calcium oxide (CaO) nanoparticles as a catalyst. The CaO nanoparticles were examined by scanning electron microscopy (SEM) and X-Ray Diffraction (XRD). The physico-chemical properties of biodiesel were studied through H and C-NMR, GC-MS, FT-IR, and fuel properties were studied according to ASTM and EN standard methods. The oil content of the feedstock was 53.7% with a free fatty acid (FFA) content of 0.89 mg KOH/g. The suitable condition for the optimum yield (89%) of biodiesel was 1:15 of oil to methanol using 20 mg of catalyst at a temperature of 60 °C for 80 to 100 min of reaction time. The H and C-NMR confirm the biodiesel synthesis by showing important peaks at 3.661, 2.015–2.788, 24.83–34.16 and 174.26 and 130.15 ppm. Similarly, GC-MS spectroscopy confirmed 18 different types of fatty acid methyl esters (FAME) in the biodiesel sample. FT-IR spectroscopy confirmed the synthesis of biodiesel by showing characteristic peaks of biodiesel formation in the range of 1725–1750 cm−1 and 1000–1300 cm−1. The fuel properties were compared with the international ASTM and EN standards. The physico-chemical properties confirm that RCB is both an engine and environmentally friendly fuel.
Machine Learning Methods to Forecast the Concentration of PM10 in Lublin, Poland
Authors: Kujawska Justyna , Kulisz Monika , Oleszczuk Piotr , Cel Wojciech
Published: September 2022

Air pollution has a major impact on human health, especially in cities, and elevated concentrations of PMx are responsible for a large number of premature deaths each year. Therefore, the amount of PM10 in the air is monitored and forecasts are made to predict the air quality. In Poland, mainly deterministic models are used to predict air pollution. Accordingly, research efforts are being made to develop other models to forecast the ambient PM10 levels. The aim of the study was to compare the machine learning models for predicting PM10 levels in the air in the city of Lublin. The following machine learning models were used: Linear regression (LR), K-Nearest Neighbors Regression (KNNR), Support Vector Machine (SVM), Regression Trees (RT), Gaussian Process Regression Models (GPR), Artificial Neural Network (ANN) and Long Short-Term Memory network (LSTM). The collected data for three consecutive years (January 2017 to December 2019) were used to develop the models. In total, 19 parameters, covering meteorological variables and concentrations of several chemical species, were explored as potential predictors of PM10. The data used to build the models did not take into account the seasons. The algorithms achieved the following R2 values: 0.8 for LR, 0.79 for KNNR, 0.82 for SVM, 0.77 for RT, 0.89, 0.90 for ANN and 0.81 for LSTM. Research has shown that the selection of a machine learning model has a large impact on the quality of the results. In this research, the ANN model performed slightly better than other models. Then, an ANN was used to train a network with five output neurons to predict the approximate level of PM10 at different time points (PM level at a given time, after 1 h, after 6 h, after 12 h and after 24 h). The results showed that the developed and tuned ANN model is appropriate (R = 0.89). The model created in this way can be used to determine the risk of exceeding the PM10 alert level and to inform about the air quality in the region.
Simulation and Study of DC Corona Discharge Characteristics of Bar-Plate Gap
Authors: Feng Na , Ma Tiehua , Chen Changxin , Yao Boren , Gao Weitao
Published: September 2022

In this paper, the corona discharge process of the bar-plate gap at −1 kV DC voltage is simulated using a two-dimensional axisymmetric plasma module. We analyze the variation of air negative corona discharge current, and the distribution morphology of microparticles in different discharge stages in detail. The significance of plasma chemical reactions at some typical time and the distribution characteristics of heavy particles are investigated according to reaction rates. Results show that, in the current rising stage, the collision ionization reactions (e.g., R1 and R2) and electron adsorption reaction (e.g., R3) play a major role, which lead to the increase in charged particles and the formation of an electron avalanche. In the current drop stage, all reaction rates decreased, except for collision ionization and electron attachment, partial charge transfer reactions (e.g., R8, R10, R11, and R14), and composite reactions (e.g., R16, R17, and R18), which come into play and gradually reduce the number of charged ions in the gap. In the current stabilizing stage, the main chemical reactions are composite reactions (e.g., R16 and R17), then the corona discharge ends. For the heavy particle distribution, O2+ and O4+ are the main positive ions, O2− is the most abundant negative ions, and the neutral particles are mainly O.
Hybrid MLI Topology Using Open-End Windings for Active Power Filter Applications
Authors: Noman Abdullah M. , Alkuhayli Abdulaziz , Al-Shamma’a Abdullrahman A. , Addoweesh Khaled E.
Published: September 2022

Different multilevel converter topologies have been presented for achieving more output voltage steps, hence improving system performance and lowering costs. In this paper, a hybrid multilevel inverter (MLI) topology is proposed for active-power-filter applications. The proposed MLI is a combination of two standard topologies: the cascaded H-bridge and the three-phase cascaded voltage source inverter. This configuration enhances the voltage levels of the proposed MLI while using fewer switches than typical MLI topologies. The proposed MLI was developed in the MATLAB/Simulink environment, and a closed-loop control technique was used to achieve a unity power factor connection of the PV modules to the grid, as well as to compensate for harmonics caused by nonlinear loads. To demonstrate that the configuration was working correctly and that the control was precise, the proposed MLI was constructed in a laboratory. A MicroLabBox real-time controller handled data acquisition and switch gating. The proposed topology was experimentally connected to the grid and the MLI was experimentally used as an active power filter to compensate for the harmonics generated due to nonlinear loads. This control technique was able to generating a sinusoidal grid current that was in phase with the grid voltage, and the grid current’s total harmonic distortion was within acceptable limits. To validate the practicability of the proposed MLI, both simulation and experimental results are presented.
An Offline and Online Approach to the OLTC Condition Monitoring: A Review
Authors: Ismail Firas B. , Mazwan Maisarah , Al-Faiz Hussein , Marsadek Marayati , Hasini Hasril , Al-Bazi Ammar , Yang Ghazali Young Zaidey
Published: September 2022

Transformer failures have a significant cost impact on the operation of an electrical network. In many utilities, transformers have been operating for many years past their expected usable life. As power demand has surged, transformers in some areas are being loaded beyond their rated capacity to meet the demand. One of the vital components in a transformer is the on-load tap changer (OLTC), which regulates the voltage in the distribution network. This study aims to review several condition-monitoring techniques (online and offline) that can monitor the health of the OLTC and assure the safety of the transformer’s OLTC from irreparable damage by detecting the defect at an earlier stage, which is preceded by the specification of typical faults. This paper also discussed the common faults of the OLTC and the root causes of these faults. The OLTC is prone to mechanical faults due to its frequently changing mechanism in the tap operation. The OLTC are also prone to oil as well as thermal faults. As a result, it is critical to monitor OLTC conditions while they are in use. Proper management of condition monitoring (CM) for the OLTC is useful and necessary to increase availability and achieve optimised operating. Condition monitoring (CM) and diagnostics methods (DM) have been developing since the 1950s. CM and DM have been implemented to diagnose and detect an incipient fault, especially for the OLTC. Many techniques, online and offline, are being used to monitor the condition of the OLTC to prevent failure and minimize outages. These DM and CM will prolong the operational cycle and avoid a major disaster for the OLTC, which is an unfavorable scenario.
Dynamic Electric Simulation Model of a Proton Exchange Membrane Electrolyzer System for Hydrogen Production
Authors: De Lorenzo Giuseppe , Agostino Raffaele Giuseppe , Fragiacomo Petronilla
Published: September 2022

An energy storage system based on a Proton Exchange Membrane (PEM) electrolyzer system, which could be managed by a nanoGrid for Home Applications (nGfHA), is able to convert the surplus of electric energy produced by renewable sources into hydrogen, which can be stored in pressurized tanks. The PEM electrolyzer system must be able to operate at variable feeding power for converting all the surplus of renewable electric energy into hydrogen in reasonable time. In this article, the dynamic electric simulation model of a PEM electrolyzer system with its pressurized hydrogen tanks is developed in a proper calculation environment. Through the calculation code, the stack voltage and current peaks to a supply power variation from the minimum value (about 56 W) to the maximum value (about 440 W) are controlled and zeroed to preserve the stack, the best range of the operating stack current is evaluated, and hydrogen production is monitored.
Profitability and Revenue Uncertainty of Wind Farms in Western Europe in Present and Future Climate
Authors: Alonzo Bastien , Concettini Silvia , Creti Anna , Drobinski Philippe , Tankov Peter
Published: September 2022

Investments into wind power generation may be hampered by the uncertainty of future revenues caused by the natural variability of the wind resource, the impact of climate change on wind potential and future electricity prices, and the regulatory risks. We quantify the uncertainty of the economic value of wind farms in France, Germany, and Denmark, and evaluate the cost of support mechanisms needed to ensure the profitability of wind farms under present and future climates. To this end, we built a localised model for wind power output and a country-level model for electricity demand and prices. Our study reveals that support mechanisms are needed for current market conditions and the current climate, as well as under future climate conditions according to several scenarios for climate change and energy transition. The cost of support mechanisms during a 15-year period is evaluated to EUR 3.8 to EUR 11.5 billion per year in France, from EUR 15.5 to EUR 26.5 billion per year in Germany, and from EUR 1.2 to EUR 3.3 billion per year in Denmark, depending on the scenario considered and the level of penetration of wind energy.
Load Management and Optimal Sizing of Special-Purpose Microgrids Using Two Stage PSO-Fuzzy Based Hybrid Approach
Authors: Azeem Fawad , Ahmad Ashfaq , Gondal Taimoor Muzaffar , Arshad Jehangir , Rehman Ateeq Ur , Eldin Elsayed M. Tag , Shafiq Muhammad , Hamam Habib
Published: September 2022

The sizing of microgrids depends on the type of load and its operational hours. The significance of understanding the load operational characteristics in special purpose islanded microgrids is much needed for economic system sizing. The load operation of special-purpose microgrids often consumes high power for a short duration and remains idle most of the time, thus reducing the load factor. The inclusion of such loads in microgrid sizing causes huge capital costs making islanded microgrids an unfeasible solution. The islanded microgrid under study is an agricultural microgrid in a village having a small Crab Processing Plant (CPP) and a Domestic Sector (DS). The CPP constitutes the major power consumption. The community has a unique load consumption trend that is dependent on the highly uncertain parameter of availability of the crabs. Interestingly, crab availability is an independent parameter and cannot be accurately scheduled. The existing system sizing of the microgrid is performed based on the conventional methods that consider the CPP for full-day operation. However, the microgrid sources, especially the storage system may be reflected as oversized if the crab processing plants do not operate for several days due to the uncertain behavior of CPP causing enormous power wastage. In this paper, an integrated fixed and operational mode strategy for uncertain heavy loads is formulated. The proposed algorithm is based on the optimal sizing methodology aided by the load scheduling control strategy. The Particle Swarm Optimization technique is used for the optimal sizing integrated with the fuzzy logic controller to manage the available load. The membership functions are available excess power and the state of the charge of storage that defines the operational conditions for CPP. Based on input membership functions, the fuzzy controller decides on power dispatch in DS or CPP, keeping considerable SoC available for night hours. The simulation result shows that the time-dependent fuzzy controller approach manages to provide power to both sectors under optimal sizing while reducing the overall cost by 24% less than the existing microgrid.
Wind Turbine Gust Load Alleviation with Active Flow Control
Authors: Liu Chang , Gupta Abhineet , Rotea Mario A.
Published: September 2022

Large wind turbine rotors are becoming more common in utility-scale wind power, especially for offshore wind plants. However, the trend toward large rotors can be limited by their ability to manage dynamic and extreme loads. To provide a safety margin for the rotor design and avoid catastrophic events such as tower strikes, extreme loads need to be controlled. The objective of this study is to develop and evaluate a feedback control system to alleviate extreme loads and reduce blade deflections under gust events using active flow control devices. We also propose a modification in the turbine controller to achieve further reduction in extreme loads. The extreme load reductions are evaluated under gust wind conditions with direction changes according to the IEC standard. The effects of the gust alleviation controller on turbine performance and fatigue loads are investigated as well. With the deployment of the gust alleviation controller and modified turbine baseline controller, the extreme loads and deflections reduce by up to 23%. The energy captured by the turbine is not affected by the proposed gust alleviation controller. The fatigue loads of various wind turbine components are either reduced or remain unchanged.
Why LNG Can Be a First Step in East Asia’s Energy Transition to a Low Carbon Economy: Evaluation of Challenges Using Game Theory
Authors: Mozakka Masih , Salimi Mohsen , Hosseinpour Morteza , N. Borhani Tohid
Published: September 2022

As countries scramble for cleaner energy production and to meet carbon reduction targets, natural gas seems to become an increasingly attractive option with liquified natural gas (LNG) as a popular transportation choice. In this paper, we first conduct a literature review and discuss the various factors affecting the global natural gas market, its recent history, current state, and future. Then we look at the possibility of East Asia becoming an alternative market to Europe for Russian LNG. We also bring in the US both as a political force that employs economic sanctions and as a potential LNG supplier. As a case study, we define a 3-player game between Russia, The United States, and Japan which results in relative market stability. In the case of sanctions against Russia, we conclude that it will lose its foothold in the Japanese market in the long term. Finally, we discuss the potential of LNG trading as the first step for East Asia’s energy transition to a low-carbon economy.
Behavior of Glass-like and Mineral-like Phosphate Compounds with an Immobilized Chloride Mixture in Hydrogen Peroxide Solutions
Authors: Frolova Anna V. , Kulikova Svetlana A. , Belova Kseniya Y. , Danilov Sergey S. , Vinokurov Sergey E.
Published: September 2022

A new type of high-level waste (HLW) is generated during pyrochemical reprocessing of mixed nitride spent uranium–plutonium nuclear fuel. Such waste is a spent electrolyte, which is a mixture of chloride salts containing approximately 25.7 wt.% LiCl + 31.6 wt.% KCl + 4.1 wt.% CsCl + 5.1 wt.% BaCl2 + 3.8 wt.% SrCl2 + 29.7 wt.% LaCl3, and its immobilization in reliable matrices is an actual radiochemical problem. The structure and hydrolytic stability of sodium aluminoironphosphate (NAFP) glass and a low-temperature mineral-like magnesium potassium phosphate (MPP) matrix, which are promising for spent electrolyte immobilization in the presence of hydrogen peroxide solutions simulating natural water radiolysis products, were studied in this work. The structure of the samples was studied using the SEM-EDS method. It was shown that the initial samples of NAFP glass after leaching in hydrogen peroxide solutions are prone to precipitation of crystalline phases on the surface, which are mainly represented by a mixture of sodium–iron–aluminum pyrophosphates. It was established that the leaching rate of structure-forming components of NAFP and MPP matrices generally increase, but remain at a low level, meeting modern requirements for HLW immobilization. This confirms the effectiveness of the studied matrices for the industrial use of the spent electrolyte.
Residential Refrigeration MEPS in Colombia: A Review and a Comparative Analysis
Authors: Ramírez Sánchez Andrés Felipe , Solís-Chaves Juan Sebastián , Rodríguez-Muñoz Andrea del Pilar , Arias Barragán Luis Alejandro , Serna-Pérez Diana Ximena , Prías Caicedo Omar Fredy
Published: September 2022

This paper addresses the energy efficiency issue in household appliances, which has led to the establishment of policies at a global level in favor of setting minimum energy performance standards (MEPS), which guarantee end users are able to select more efficient equipment. The countries of the United States, Brazil, Mexico, Chile, and the Community of the European Union were taken as references to review their policies and implementation strategies, in order to be compared with the Colombian panorama (at the market, technical and political levels). This allows the establishment of common aspects and differences related to the determination of energy consumption, adjusted volume, and formalization of efficiency ranges, and in the specific case of domestic refrigeration. Managing to distinguish the most relevant aspects for the successful adoption of these policies in Colombia. It is evident that the implementation of these guidelines has a positive impact on the market of the countries and communities of reference. Similarly, the MEPS are shown as a mechanism to regulate energy consumption in the residential sector.
Design of Energy-Saving Duct for JBC to Reduce Ship Resistance by CFD Method
Authors: Wu Ping-Chen , Chang Chin-Wei , Huang Yu-Chi
Published: September 2022

The present work is to modify the stern duct of Japan bulk carrier (JBC) to reduce the ship total resistance for Froude number 0.142. The research method is to use the CFD (computational fluid dynamics) tool OpenFOAM to predict the total resistance and viscous flow field around the ship hull considering the free surface. First, the V&V (verification and validation) analysis was conducted to ensure our CFD method is reliable, and to estimate its error and uncertainty range for the original JBC with and without the original stern duct. Second, the angle of attack (AoA) of the foil section of the stern duct was adjusted, thus forming a series of different ducts axisymmetric along the propeller shaft axis. The CFD simulations were performed for each duct appended behind the ship hull. By comparing the total resistance with and without the duct, the ship hull resistance reduction effect caused by the duct would be obtained. Finally, the duct with 7° AoA achieved the best resistance reduction of 2.49%. The original duct (with 20° AoA) could only provide a 0.6~0.7% reduction. The nominal wake was also analyzed with the ducts, in order to understand the detailed flow phenomena which had an essential influence on propeller inflow.
Inventory Routing for Ammonia Supply in German Ports
Authors: Prause Felix , Prause Gunnar , Philipp Robert
Published: September 2022

Following the International Maritime Organization (IMO), in order to safeguard the realization of the Paris Agreement on climate protection, greenhouse gas (GHG) emissions have to be reduced by 50% by the year 2050. This objective shall be reached by decarbonization of maritime traffic, which is why ship operators currently increasingly search for alternative fuels. Moreover, since the start of the Ukrainian war in February 2022, this issue of alternative fuels has gained central importance in political agendas. A promising candidate for clean shipping that meets the IMO goals is ammonia since it is a carbon-free fuel. Ammonia (NH3) shows good advantages in handling and storage, and it ensures long sea voyages without any significant loss in cargo space for a reasonable price. Hence, ammonia has the potential to improve the environmental footprint of global shipping enormously. Induced by the introduction of stricter regulations in the so-called emission control areas (ECAs) in Northern Europe in 2015 as well as the renewed global sulfur cap, which entered into force in 2020, ship operators had to decide between different compliance methods, among which the most popular solutions are related to the use of expensive low-sulfur fuel oils, newbuilds and retrofits for the usage of liquefied natural gas (LNG) or the installation of scrubber technology. A change to ammonia as a marine alternative fuel represents an additional novel future option, but the successful implementation depends on the availability of NH3 in the ports, i.e., on the installation of the maritime NH3 infrastructure. Currently, the single German NH3 terminal with maritime access is located in Brunsbüttel, the western entrance to Kiel Canal. The distribution of NH3 from the existing NH3 hub to other German ports can be analyzed by the mathematical model of an inventory routing problem (IRP) that is usually solved by combinatorial optimization methods. This paper investigates the interrelated research questions, how the distribution of marine NH3 fuel can be modeled as an IRP, which distribution mode is the most economic one for the German ports and which modal mix for the NH3 supply leads to the greenest distribution. The results of this paper are empirically validated by data that were collected in several EU projects on sustainable supply chain management and green logistics. The paper includes a special section that is dedicated to the discussion of the economic turbulences related to the Ukrainian war together with their implications on maritime shipping.
Detailed Analysis of PAH Formation, Toxicity and Regulated Pollutants in a Diesel Engine Running on Diesel Blends with n-Propanol, n-Butanol and n-Pentanol
Authors: Yilmaz Nadir , Vigil Francisco M. , Atmanli Alpaslan , Donaldson Burl
Published: September 2022

There are a number of emissions produced by internal combustion engines that are regulated to limit atmospheric pollution. However, it is equally important for both environmental and human health to also monitor and control polycyclic aromatic hydrocarbons (PAHs). Using high-carbon alcohols with straight-chain structures, such as n-propanol (Pro), n-butanol (Bu) and n-pentanol (Pen), together with diesel fuel (D), can be a way to reduce these harmful pollutants. In this study, nine different test fuels were created by mixing each higher alcohol with diesel fuel at 5%, 20% and 30% mixing ratios. In order to compare the effects of these test fuels on regulated pollutants and PAH compounds, fuel blends were evaluated in a diesel engine at partial loads and at a constant speed. Regulated emissions were measured using a standard 5-gas analyzer, and PAHs were detected and quantified using rigorous analytical chemistry methods, such as gas chromatography–mass spectrometry (GC–MS). While higher carbon monoxide (CO) and hydrocarbon (HC) pollutants were emitted by the binary blends due to their high oxygen content and latent heat of evaporation (LHE), a decrease in nitrogen oxides (NOx) emissions between 4.98% and 20.08% was observed depending on the alcohol concentration. With the exception of the 20% n-pentanol mixture, PAH concentrations in the exhaust gas were significantly reduced in other binary blends. The 35% n-butanol mixture stood out in reducing total PAHs by 80.98%. In toxicity reduction, the 20% n-propanol mixture was the most effective with a decrease of 91.23% in toxicity. Overall, higher alcohols have been shown to be effective additives not only in reducing overall PAH emissions and toxicity, but also in reducing high-ring and heavier PAHs, which are more carcinogenic and cause a greater risk to engine lifedue to wet stacking under cold starting or low-load conditions.
Alternative Simplified Analytical Models for the Electric Field, in Shoreline Pond Electrode Preliminary Design, in the Case of HVDC Transmission Systems
Authors: Tsekouras George J. , Kontargyri Vassiliki T. , Prousalidis John M. , Kanellos Fotios D. , Tsirekis Constantinos D. , Leontaritis Konstantinos , Alexandris John C. , Deligianni Panagiota M. , Kontaxis Panagiotis A. , Moronis Antonios X.
Published: September 2022

In Greece, a new bi-polar high voltage direct current (HVDC) transmission system with a ground return was designed with nominal characteristics of ±500 kV, 1 GW, between Attica in the continental country and the island of Crete, which is an autonomous power system based on thermal diesel units. The interconnection line has a total length of about 380 km. The undersea section is 330 km long. In this paper, the use of the Aegean Sea as an active part of the ground return, based on shoreline pond electrodes, was proposed to avoid EUR 200 Μ of expenses. According to the general guidelines for HVDC electrode design by the International Council on Large Electric Systems (CIGRE) working group B4.61/2017, the electric field and ground potential rise of shoreline electrodes should be studied to analyze safety, electrical interference and corrosion impacts related to the operation of the electrodes. Two kinds of studies are available; one is a simplified approach based on a spherical/pointed electrode centered at the edge of the seashore and seabed, assuming it to be sloping to the horizontal, and the other is a detailed simulated model using a suitable electric field software package. The first approach usually gives more unfavorable results than the second one, especially in the near electric field, while it can not take into account obstacles, i.e., dams, near to electrode position. The second approach demands a detailed description of the wider installation area, which cannot be available during the preliminary study, significant computational time and considerable financial resources for the purchase of a reliable specialized software package. In this research, a two-step modification of the CIGRE simplified model was proposed. The first modification deals with the obstacles in the near electric field, and the second modification deals with the use of a linear current source (instead of a point one), which can give more accurate results. Additionally, the electric field for complex electrode formation is calculated by applying the superposition method, which can be easily achieved using a common software package, i.e., MATLAB. The proposed simplified approaches were applied on shoreline pond electrode locations for the Attica–Crete HVDC interconnection line (between Stachtoroi island in Attica and Korakia beach in Crete), allowing the preliminary study to be conducted swiftly, giving satisfactory results about electric field gradient, ground potential rise and resistance to remote earth of electrodes stations for the near and far electric field.
Changes in Gross Primary Production in Response to Afforestation in the Hilly Loess Plateau of Northern Shaanxi, China
Authors: Li Wangjun , Chen Dechao
Published: September 2022

As a large-scale afforestation initiative, the Grain for Green (GFG) program was implemented for more than decade in the hilly Loess Plateau of Northern Shaanxi starting in 1999 and inevitably affected plant biomass production. This study evaluated the trend and magnitude of gross primary production (GPP) changes with VPM in the study area over 2000–2012 and quantitatively identified GFG’s contribution. The results indicate that the regional mean GPP was 529.6 to 854.7 g C m−2 yr−1, which significantly increased by 1.63% per year during the period. At the pixel level, 80% of the pixels presented an increasing trend in annual GPP, and in nearly half of the region, the increasing trend was statistically significant. Spatial analyses showed that the GPP increased more significantly in the gully areas of the middle north area, while no evident change trend was observed in the southern forestland areas. Statistical data from relevant yearbooks and interpreted data from high-resolution images show that the GFG program promoted vegetation restoration. Taking the increased area of forestland to indicate the achievements of GFG, we estimated, using regression analyses, that the afforestation contributed 40%–60% to the increased GPP in the region during 2000–2012. Overall, the ecosystem had a positive response to the Grain for Green (GFG) program in Northern Shaanxi.
Structure Degradation Induced by Wetting and Drying Cycles for the Hilly Granitic Soils in Collapsing Gully Erosion Areas
Authors: Xia Jinwen , Zhang Lichao , Ge Pelin , Lu Xianghui , Wei Yujie , Cai Chongfa , Wang Jie
Published: September 2022

The hydrological and mechanical properties of granitic residual soils can be significantly altered by periodical wetting and drying (W-D) cycles. The soil structure degradation induced by W-D cycles can lead to soil mass failure and collapsing gully erosion in granitic hilly slopes in south China. However, limited attempts have been made at a comprehensive investigation of the effects of W-D cycles on the structure degradation of granitic residual soils, especially at the pedon scale. The purpose of this paper is to investigate the structural degradation of granite soils induced by W-D cycles and explore its potential influence on the development of collapsing gully erosion. The granitic soil properties, including hydraulic properties, shear strength, and disintegration characteristics, were performed after W-D cycles. The results indicated that the W-D cycles altered the soil pore structure, leading to variations in soil hydraulic properties. Specifically, with increasing alternate W-D cycles, the initial saturated water content and residual water content decreased, while the saturated hydraulic conductivity increased. Meanwhile, increasing W-D cycles contributed significantly to variations in cohesion and internal friction strength by decreasing the shear strength variables, especially the soil cohesion strength. Correspondingly, soil disintegration was increased during W-D cycles. Furthermore, most degradation of soil structure was recorded within the first two cycles of W-D. The obtained results indicate that the W-D cycles weaken soil structure, increase rainwater infiltration, decrease soil shear strength and disintegration resistance, and accelerate soil erosion. A vicious cycle of granitic slope failure induced by W-D cycles is eventually formed. This study provides useful information about the mechanism of soil mass failure and collapsing gully erosion in granitic hilly slopes.