bluuebunny/crossref_metadata_2025 huggingface dataset:
UBUMonitor: An Open-Source Desktop Application for Visual E-Learning Analysis with Moodle
Authors: Marticorena-Sánchez Raúl , López-Nozal Carlos , Ji Yi Peng , Pardo-Aguilar Carlos , Arnaiz-González Álvar
Published: March 2022

An inherent requirement of teaching using online learning platforms is that the teacher must analyze student activity and performance in relation to course learning objectives. Therefore, all e-learning environments implement a module to collect such information. Nevertheless, these raw data must be processed to perform e-learning analysis and to help teachers arrive at relevant decisions for the teaching process. In this paper, UBUMonitor is presented, an open-source desktop application that downloads Moodle (Modular Object-Oriented Dynamic Learning Environment) platform data, so that student activity and performance can be monitored. The application organizes and summarizes these data in various customizable charts for visual analysis. The general features and uses of UBUMonitor are described, as are some approaches to e-teaching improvements, through real case studies. These include the analysis of accesses per e-learning object, statistical analysis of grading e-activities, detection of e-learning object configuration errors, checking of teacher activity, and comparisons between online and blended learning profiles. As an open-source application, UBUMonitor was institutionally adopted as an official tool and validated with several groups of teachers at the Teacher Training Institute of the University of Burgos.
Strategies for Applications of Oxide-Based Thin Film Transistors
Authors: Zhang Lirong , Yu Huaming , Xiao Wenping , Liu Chun , Chen Junrong , Guo Manlan , Gao Huayu , Liu Baiquan , Wu Weijing
Published: March 2022

Due to the untiring efforts of scientists and researchers on oxide semiconductor materials, processes, and devices, the applications for oxide-based thin film transistors (TFTs) have been researched and promoted on a large scale. With the advantages of relatively high carrier mobility, low off-current, good process compatibility, optical transparency, low cost, and especially flexibility, oxide-based TFTs have already been adapted for not only displays (e.g., liquid crystal display (LCD), organic light emitting diode (OLED), micro-light-emitting diode (Micro-LED), virtual reality/augmented reality (VR/AR) and electronic paper displays (EPD)) but also large-area electronics, analog circuits, and digital circuits. Furthermore, as the requirement of TFT technology increases, low temperature poly-silicon and oxide (LTPO) TFTs, which combine p-type LTPS and n-type oxide TFT on the same substrate, have drawn further interest for realizing the hybrid complementary metal oxide semiconductor (CMOS) circuit. This invited review provides the current progress on applications of oxide-based TFTs. Typical device configurations of TFTs are first described. Then, the strategies to apply oxide-based TFTs for improving the display quality with different compensation technologies and obtaining higher performance integrated circuits are highlighted. Finally, an outlook for the future development of oxide-based TFTs is given.
Integration of Low-Cost Digital Tools for Preservation of a Sustainable Agriculture System
Authors: Serrano-Trujillo Alejandra , Esqueda-Elizondo José Jaime , Jiménez-Beristáin Laura
Published: March 2022

This work presents an electronic sensing approach composed of a pair of Physical–Chemical and Imaging modules to preserve an aquaponic system. These modules offer constant measurements of the physical–chemical characteristics within the fish tank and the grow bed, and an indication of the health of the growing plants through image processing techniques. This proposal is implemented in a low-cost computer, receiving measurements from five sensors, including a camera, and processing the signals using open-source libraries and software. Periodic measurements of the temperature, water level, light, and pH within the system are collected and shared to a cloud platform that allows their display in a dashboard, accessible through a web page. The health of the vegetables growing in the system is estimated by analyzing visible and infrared spectra, applying feature extraction, and computing vegetation indices. This work provides a low-cost solution for preserving sustainable urban farming systems, suitable for new farming communities.
Data Protection and Cybersecurity Certification Activities and Schemes in the Energy Sector
Authors: Nwankwo Iheanyi , Stauch Marc , Radoglou-Grammatikis Panagiotis , Sarigiannidis Panagiotis , Lazaridis George , Drosou Anastasios , Tzovaras Dimitrios
Published: March 2022

Cybersecurity concerns have been at the forefront of regulatory reform in the European Union (EU) recently. One of the outcomes of these reforms is the introduction of certification schemes for information and communication technology (ICT) products, services and processes, as well as for data processing operations concerning personal data. These schemes aim to provide an avenue for consumers to assess the compliance posture of organisations concerning the privacy and security of ICT products, services and processes. They also present manufacturers, providers and data controllers with the opportunity to demonstrate compliance with regulatory requirements through a verifiable third-party assessment. As these certification schemes are being developed, various sectors, including the electrical power and energy sector, will need to access the impact on their operations and plan towards successful implementation. Relying on a doctrinal method, this paper identifies relevant EU legal instruments on data protection and cybersecurity certification and their interpretation in order to examine their potential impact when applying certification schemes within the Electrical Power and Energy System (EPES) domain. The result suggests that the EPES domain employs different technologies and services from diverse areas, which can result in the application of several certification schemes within its environment, including horizontal, technological and sector-specific schemes. This has the potential for creating a complex constellation of implementation models and would require careful design to avoid proliferation and disincentivising of stakeholders.
Region Resolution Learning and Region Segmentation Learning with Overall and Body Part Perception for Pedestrian Detection
Authors: Zhang Yu , Wang Hui , Liu Yizhuo , Lu Mao
Published: March 2022

Pedestrian detection is a great challenge, especially in complex and diverse occlusion environments. When a pedestrian is in an occlusion situation, the pedestrian visible part becomes incomplete, and the body bounding box contains part of the pedestrian, other objects and backgrounds. Based on this, we attempt different methods to help the detector learn more features of the pedestrian under different occlusion situations. First, we propose region resolution learning, which learns the pedestrian regions on the input image. Second, we propose fine-grained segmentation learning to learn the outline and shape of different parts of pedestrians. We propose an anchor-free approach that combines a pedestrian detector CSP, region Resolution learning and Segmentation learning (CSPRS). We help the detector to learn extra features. CSPRS provides another way to perceive pixels, outline and shapes in pedestrian areas. This detector includes region resolution learning, and segmentation learning helps the detector to locate pedestrians. By simply adding the region resolution learning branch and segmentation branch, CSPRS achieves good results. The experimental results show that both methods of learning pedestrian features improve performance. We evaluate our proposed detector CSPRS on the CityPersons benchmark, and the experiments show that CSPRS achieved 42.53% on the heavy subset on the CityPersons dataset.
Less Is More: Robust and Novel Features for Malicious Domain Detection
Authors: Hajaj Chen , Hason Nitay , Dvir Amit
Published: March 2022

Malicious domains are increasingly common and pose a severe cybersecurity threat. Specifically, many types of current cyber attacks use URLs for attack communications (e.g., C&C, phishing, and spear-phishing). Despite the continuous progress in detecting cyber attacks, there are still critical weak spots in the structure of defense mechanisms. Since machine learning has become one of the most prominent malware detection methods, a robust feature selection mechanism is proposed that results in malicious domain detection models that are resistant to evasion attacks. This mechanism exhibits a high performance based on empirical data. This paper makes two main contributions: First, it provides an analysis of robust feature selection based on widely used features in the literature. Note that even though the feature set dimensional space is cut by half, the performance of the classifier is still improved (an increase in the model’s F1-score from 92.92% to 95.81%). Second, it introduces novel features that are robust with regard to the adversary’s manipulation. Based on an extensive evaluation of the different feature sets and commonly used classification models, this paper shows that models based on robust features are resistant to malicious perturbations and concurrently are helpful in classifying non-manipulated data.
Influence of the Port Height to Stroke Ratio on the Performance of an OP2S Engine Fueled with Methanol/Diesel
Authors: Yang Wei , Li Feng , Ma Fukang , Xu Dan , Xu Junfeng , Wang Fang
Published: March 2022

Zero carbon emission is a mainstream trend in the development of internal combustion engines (ICEs) in the future. ICEs need to constantly surpass the existing working mechanism, especially in order to explore the possibility of new combustion methods. Dual-fuel combustion is a good way to reduce carbon emissions and achieve clean combustion. However, the traditional internal combustion engine is limited by its own structure, restricting its performance improvement. The opposed-piston, two-stroke (OP2S) diesel engine is a potential power system with a high degree of structural adjustability. Therefore, this work attempted to apply methanol/diesel dual-fuel to OP2S engines in order to explore efficient and clean combustion modes in the future. In this work, a one-dimensional simulation model of an OP2S diesel engine was established and verified. The effect of the port height to stroke ratio on the performance of the OP2S diesel engine was mainly studied for different methanol blending ratios. The results show that the methanol blending ratio does not affect the port height to stroke ratio where the optimal values of the MIP and scavenging efficiency appear. The optimal methanol blending ratio for the power performance of OP2S diesel engines is 5~15%. There is a trade-off relationship between the MIP/scavenging efficiency and trapping efficiency. For the optimization of an OP2S methanol–diesel engine, priority should be given to ensuring an optimal MIP and scavenging efficiency, and then to the appropriate consideration of the trapping efficiency.
Experimental and Numerical Investigation of a Surface Sliding Discharge in a Supersonic Flow with an Oblique Shock Wave
Authors: Mursenkova Irina , Ivanov Igor , Liao Yugan , Kryukov Igor
Published: March 2022

This study presents an experimental and numerical investigation on a surface sliding discharge in a supersonic airflow in the presence of an oblique shock wave. In experiments, flow Mach numbers were 1.20–1.68 in the shock tube combined with the discharge chamber. A single high-voltage 25 kV pulse sustains the plasma; the discharge current has a duration of ~500 ns. A surface sliding discharge is developed as a localized channel in a zone of interaction of an oblique shock wave with a boundary layer on the upper wall of the discharge chamber. The discharge channel acts as a linear source of heat and is at the origin of the induced shock wave. The flow field in the discharge chamber is spatio-temporally surveyed using high-speed shadowgraphy imaging with a frequency of up to 525,000 frames per second. The experiments show that the perturbed flow restored the initial structure after more than 100 μs. Numerical simulation with local energy input into the supersonic flow in a flat channel is carried out on the base of unsteady two-dimensional Navier–Stokes equations. It is determined that the dynamics of an induced shock wave are dependent on the energy input regime and on the flow parameters. The thermal energy release in the discharge channel of 0.22–0.29 J was estimated from a comparison of experimental data and numerical simulations.
Hydroponic Green Roof Systems as an Alternative to Traditional Pond and Green Roofs: A Literature Review
Authors: Rapisarda Renata , Nocera Francesco , Costanzo Vincenzo , Sciuto Gaetano , Caponetto Rosa
Published: March 2022

Among the several methods investigated over the past few years for the thermal mitigation of buildings in urban areas, green roof systems seem to be one of the most suitable solutions for several reasons, and researchers encourage the further study and implementation of these roofing techniques because of the potential benefits that they offer. So far, intensive, extensive and semi-intensive green roofs are considered to be a better option in terms of both energy efficiency and green area increase. However, there are some aspects that cause green roofs not to be suitable to every application, preventing their use from spreading, such as high maintenance and costs required by these sophisticated systems. Few studies aimed at overcoming the limits of green roofs have hinted at the possibility of implementing hydroponic cultures in green roof systems. This soil-less technology might overcome some issues, such as identifying the suitable substrate to support the growth of the vegetation. This paper aims to provide a systematic review of hydroponic green roof systems (HGRS), based on the rigorous analysis of the evidence gathered from the thorough evaluation of the available literature on the subject, in order to assess their potential use as an alternative to traditional green roofs. The review was carried out by analyzing studies that have assessed the performance of hydroponic green roofs as well as those of comparable systems, such as pond roofs and green roofs. The results of these studies show that HGRS provide similar performances to the above-mentioned systems in terms of the passive conditioning effect, lowering the cooling/heating load of buildings, with slight changes depending on the climatic conditions. However, they offer other significant properties such as higher efficiency in water runoff management, alongside others discussed in this paper, while also requiring minor maintenance. Significant results have been provided; however, gaps in the knowledge have also emerged, and further studies need to be conducted to provide exhaustive information.
Laminar Burning Speed of Aviation Kerosene at Low Pressures
Authors: Liu Jian , Zhang Dingrui , Hou Lingyun , Yang Jinhu , Xu Gang
Published: March 2022

Aero-engine combustors may experience extreme low pressures in the case of an in-flight shutdown, which makes the study of aviation kerosene flame propagation characteristics at low pressures important. The present work examined flame propagation during the combustion of aviation kerosene over the pressure range from 25 to 100 kPa using a constant-volume bomb apparatus. The laminar burning speeds at different initial pressures, temperatures and equivalence ratios were measured and compared. In addition, numerical simulations were used to examine the reaction sensitivity of the laminar burning speed at low pressure. In trials at the lean flammability limit, the data indicated that it was more difficult to ignite the fuel under a lower pressure condition of 25 kPa and a lower temperature condition of 420 K. The experimental results of laminar burning speed were fitted to an equation providing the laminar burning speeds expected at different pressures (25–100 kPa), temperatures (400–480 K) and equivalence ratios (0.8–1.5). The temperature index (α=1.76) and pressure index (β=−0.15) of the fitting equation were obtained. Both hydrodynamic and diffusional thermal flame instabilities were found to be suppressed at low pressures. The negative effects of two specific reactions on laminar burning speed were greatly reduced at these same low pressures of 25 kPa.
Heat Transfer Characteristics of Fractionalized Hydromagnetic Fluid with Chemical Reaction in Permeable Media
Authors: Souayeh Basma , Ali Abro Kashif , Alnaim Nisrin , Al Nuwairan Muneerah , Hdhiri Najib , Yasin Essam
Published: March 2022

This manuscript optimizes the conjugate heat transfer and thermal-stress analysis for hydromagnetic Brinkman fluid with chemical reaction in permeable media. The governing equations of non-Newtonian Brinkman fluid have been traced out and then fractional derivative approach, namely, Caputo–Fabrizio, is invoked, subject to the exponential boundary conditions. The Fourier Sine and Laplace transforms are applied on governing partial differential equations for generating the analytical results of temperature, concentration and velocity. A comparative study of velocity field is investigated for the sake of long memory and hereditary properties. The analytical investigation of temperature, concentration and velocity field have strong effects on chemical reaction. The graphical depiction of vibrant characteristics of hydromagnetic Brinkman fluid with chemical reaction in permeable media is exhibited for disclosing the sensitivities of different embedded rheological parameters of fluid flow. The results suggested that temperature distribution for smaller and larger Prandtl number has disclosed quick and thicker heat diffusivity.
Energy Demand Analysis and Powertrain Design of a High-Speed Delivery Robot Using Synthetic Driving Cycles
Authors: Vepsäläinen Jari
Published: March 2022

Last mile is known as the last leg of the delivery process, which is the most expensive and time-consuming part per kilometer. The most common last mile deliveries are postal packages, groceries and take away meals. Recently, there has been a growing interest and implementation of sidewalk autonomous delivery robots. These robots travel roughly at the speed of pedestrians (6 km/h). A high-speed (15 km/h) delivery robot design is proposed for reducing the time, energy and carbon footprint of deliveries. The preliminary design of the delivery robot powertrain is based on worst-case scenario analysis and Monte Carlo simulations with synthetic driving cycles. Synthetic driving cycles were used because there are no open data available of delivery robots. Thus, the procedure presented in this paper is a general approach for cases where there is no precedent application and/or no data are available. The synthetic driving cycles are based on start and end location of food-delivery services in Helsinki, Finland. Based on the simulations, the crucial factors contributing to energy demand and its variation were analyzed. Carbon footprint of the delivered package over distance of the design is compared to existing wheeled delivery robots and quadrupeds. The motivation of the work is that showcasing the energy savings of higher speed aids government officials in their decision-making regarding delivery robot regulations. As a result of the simulations, higher operation speed lowered the energy consumption by over 40%.
Fuzzy Logic-Based Load Frequency Control in an Island Hybrid Power System Model Using Artificial Bee Colony Optimization
Authors: Kumar Neelamsetti Kirn , Gopi Rahul Sanmugam , Kuppusamy Ramya , Nikolovski Srete , Teekaraman Yuvaraja , Vairavasundaram Indragandhi , Venkateswarulu Siripireddy
Published: March 2022

This study presents the implementation of Artificial Bee Colony (ABC) optimization in an island hybrid power system model using fuzzy logic-based load frequency control. The Island Hybrid Power System considered in this study consisted of various generation units and an energy storage system. The optimized control parameters of PID using ABC were used in an intelligent fuzzy logic controller. The profiles (power & Frequency) of isolated hybrid power system were improved using a Super Conducting Magnetic Energy Storage (SMES) System. Individual controllers were used for wind turbine and diesel generators to control the power output for balancing the demand (frequency change control). Comparative analysis of power and frequency with the help of various classical and intelligent control configurations is presented. The outcome of the study shows that a minimum deviation in frequency and power is obtained through the proposed Intelligent Fuzzy Control approach for the considered isolated power system model.
Low-Frequency Non-Intrusive Load Monitoring of Electric Vehicles in Houses with Solar Generation: Generalisability and Transferability
Authors: Vavouris Apostolos , Garside Benjamin , Stankovic Lina , Stankovic Vladimir
Published: March 2022

Electrification of transportation is gaining traction as a viable alternative to vehicles that use fossil-fuelled internal combustion engines, which are responsible for a major part of carbon dioxide emissions. This global turn towards electrification of transportation is leading to an exponential energy and power demand, especially during late-afternoon and early-evening hours, that can lead to great challenges that electricity grids need to face. Therefore, accurate estimation of Electric Vehicle (EV) charging loads and time of use is of utmost importance for different participants in the electricity markets. In this paper, a scalable methodology for detecting, from smart meter data, household EV charging events and their load consumption with robust evaluation, is proposed. This is achieved via a classifier based on Random Decision Forests (RF) with load reconstruction via novel post-processing and a regression approach based on sequence-to-subsequence Deep Neural Network (DNN) with conditional Generative Adversarial Network (GAN). Emphasis is placed on the generalisability of the approaches over similar houses and cross-domain transferability to different geographical regions and different EV charging profiles, as this is a requirement of any real-case scenario. Lastly, the effectiveness of different performance and generalisation loss metrics is discussed. Both the RF classifier with load reconstruction and the DNN, based on the sequence-to-subsequence model, can accurately estimate the energy consumption of EV charging events in unseen houses at scale solely from household aggregate smart meter measurements at 1–15 min resolutions.
Flashover Voltage of Epoxy FRP Insulators with Different Surface Roughness and Groove under Nanosecond Pulses in SF6
Authors: Chen Zhiqiang , Wang Chengcheng , Jia Wei , Cheng Le , Guo Fan , Xie Linshen , Wu Wei , Chen Wei
Published: March 2022

In order to further improve the insulation performance of fiber reinforce plastic (FRP) materials used in electromagnetic pulse (EMP) simulators, the flashover characteristics of FRP materials with different surface roughness and groove, i.e., those who are easily achieved and have a prominent effect, are investigated in 0.1 MPa SF6 under nanosecond pulse voltage with a rise time of 20–30 ns. The experimental results show that surfaces with different roughness have no significant influence on the flashover voltages of the FRP insulators, and both the convex grooves made of FRP and the convex grooves with nylon rings inlaid to form projections can improve the surface flashover voltage of epoxy FRP insulators under nanosecond pulse, in which the effect of the former surface is more obvious. For the insulators with convex grooves made of FRP, it is found that the root of the FRP protrusions breaks down after a number of shots with the occurrence of carbonization channels and spots, which is nonexistent for the nylon projections. Combined with the test results of surface characteristics, the surface roughness and the secondary electron emission yield (SEEY) are not key factors of flashover characteristics in SF6 under nanosecond pulse, arguably due to the fact that the energy needed for an incident electron to ionize an SF6 molecule is lower than that to excite two secondary electrons. Hence, the flashover performance cannot be improved by adjusting the surface roughness, and the flashover channel is principally governed by the macroscopic distribution of electrical field which can be changed by the convex groove. Breakdown phenomena of FRP protrusions indicate that the bulk insulation performance of resin FRP is weaker compared to pure resin because of its composite structure, as well as the impurities and voids introduced in the manufacturing process. The results are instructive for the design of FRP insulation structures in the compact EMP simulator.
Economic Aspects for Recycling of Used Lithium-Ion Batteries from Electric Vehicles
Authors: Lima Maria Cecília Costa , Pontes Luana Pereira , Vasconcelos Andrea Sarmento Maia , de Araujo Silva Junior Washington , Wu Kunlin
Published: March 2022

Worldwide, there has been an exponential growth in the production and application of lithium-ion batteries (LIBs), driven by the energy transition and the electric vehicle market. The scarcity of raw materials and the circular economy strategy of LIBs encourage the need to reuse components, recycle, and give second life to used batteries. However, one of the obstacles is the insufficient volume of LIBs for recycling, which prevents the economic viability of this industrial process. Thus, this article mainly focuses on the economic aspects of the recycling of LIBs, presenting and analyzing: (i) the advantages and disadvantages of recycling and (ii) a survey of factors that influence the cost and economic feasibility of disposing of batteries. The importance of regulations, the market, and business models regarding the recycling of LIBs in a few countries are also discussed. Finally, a business model is created for recycling LIBs in Brazil. The main factors that influence the economic feasibility of this process are indicated, such as government incentives through regulation, exemption from fees and taxes, and the adequacy of battery technology. Encouraging recycling through tax exemptions or reductions can make the process more economically viable, in addition to contributing to the circular economy. Another essential factor to be considered is the creation of joint ventures, which can facilitate the entire chain of the circular economy, including logistics, transport, and disposal of batteries.
Fast Experimental Magnetic Model Identification for Synchronous Reluctance Motor Drives
Authors: Varvolik Vasyl , Wang Shuo , Prystupa Dmytro , Buticchi Giampaolo , Peresada Sergei , Galea Michael , Bozhko Serhiy
Published: March 2022

The accurate magnetic model is mandatory for high-performance control of high anisotropy synchronous machines. This paper presents a time-efficient and accurate magnetic model identification based on triangle current injection while the machine under the test is driven at a constant speed by a prime mover. The current injection pattern allows scanning the whole range of current, reducing the identification time compared to the standard constant-speed method (CSM) with the same level of accuracy. The ohmic voltage drop and inverter nonlinearities are compensated by using the average voltage of motor and generator modes. The synchronous reluctance machine is used as a case study for validation through the comparison between the experimental results obtained by the proposed method and the CSM against finite element simulation. Moreover, the temperature variation of the machine winding is measured showing no considerable changes during the identification test.
Improvement of PMSM Sensorless Control Based on Synergetic and Sliding Mode Controllers Using a Reinforcement Learning Deep Deterministic Policy Gradient Agent
Authors: Nicola Marcel , Nicola Claudiu-Ionel , Selișteanu Dan
Published: March 2022

The field-oriented control (FOC) strategy of a permanent magnet synchronous motor (PMSM) in a simplified form is based on PI-type controllers. In addition to their low complexity (an advantage for real-time implementation), these controllers also provide limited performance due to the nonlinear character of the description equations of the PMSM model under the usual conditions of a relatively wide variation in the load torque and the high dynamics of the PMSM speed reference. Moreover, a number of significant improvements in the performance of PMSM control systems, also based on the FOC control strategy, are obtained if the controller of the speed control loop uses sliding mode control (SMC), and if the controllers for the inner control loops of id and iq currents are of the synergetic type. Furthermore, using such a control structure, very good performance of the PMSM control system is also obtained under conditions of parametric uncertainties and significant variations in the combined rotor-load moment of inertia and the load resistance. To improve the performance of the PMSM control system without using controllers having a more complicated mathematical description, the advantages provided by reinforcement learning (RL) for process control can also be used. This technique does not require the exact knowledge of the mathematical model of the controlled system or the type of uncertainties. The improvement in the performance of the PMSM control system based on the FOC-type strategy, both when using simple PI-type controllers or in the case of complex SMC or synergetic-type controllers, is achieved using the RL based on the Deep Deterministic Policy Gradient (DDPG). This improvement is obtained by using the correction signals provided by a trained reinforcement learning agent, which is added to the control signals ud, uq, and iqref. A speed observer is also implemented for estimating the PMSM rotor speed. The PMSM control structures are presented using the FOC-type strategy, both in the case of simple PI-type controllers and complex SMC or synergetic-type controllers, and numerical simulations performed in the MATLAB/Simulink environment show the improvements in the performance of the PMSM control system, even under conditions of parametric uncertainties, by using the RL-DDPG.
Particle Swarm Optimization in Residential Demand-Side Management: A Review on Scheduling and Control Algorithms for Demand Response Provision
Authors: Menos-Aikateriniadis Christoforos , Lamprinos Ilias , Georgilakis Pavlos S.
Published: March 2022

Power distribution networks at the distribution level are becoming more complex in their behavior and more heavily stressed due to the growth of decentralized energy sources. Demand response (DR) programs can increase the level of flexibility on the demand side by discriminating the consumption patterns of end-users from their typical profiles in response to market signals. The exploitation of artificial intelligence (AI) methods in demand response applications has attracted increasing interest in recent years. Particle swarm optimization (PSO) is a computational intelligence (CI) method that belongs to the field of AI and is widely used for resource scheduling, mainly due to its relatively low complexity and computational requirements and its ability to identify near-optimal solutions in a reasonable timeframe. The aim of this work is to evaluate different PSO methods in the scheduling and control of different residential energy resources, such as smart appliances, electric vehicles (EVs), heating/cooling devices, and energy storage. This review contributes to a more holistic understanding of residential demand-side management when considering various methods, models, and applications. This work also aims to identify future research areas and possible solutions so that PSO can be widely deployed for scheduling and control of distributed energy resources in real-life DR applications.
Improving the Thermal Performance of Indirect Evaporative Cooling by Using a Wet Fabric Device on a Concrete Roof in Hot and Humid Climates
Authors: Esparza-López Carlos J. , Pozo Carlos Escobar-del , Al-Obaidi Karam M. , González-Trevizo Marcos Eduardo
Published: March 2022

This study investigated an indirect evaporative cooling system (IECS) to control latent heat loss on roof ponds by increasing the evaporation rates on wet fabric membranes. The cooling potential of the proposed system was experimentally tested in a real environment and it was compared against a roof pond and a floating fiber (gunny bags) to provide an efficient model for buildings in hot and humid climates. Dry bulb temperatures (DBT) are presented for four experimental models. Solar irradiance, ambient and indoor dry bulb temperatures, and relative humidity (RH) were measured for seven days in each of the following climate conditions: hot sub-humid (mean DBT 27.3 °C and mean RH 72%), hot humid (mean DBT 27.1 °C and mean RH 81%), and warm sub-humid (mean DBT 25.2 °C and mean RH 68%). There were no significant variations in thermal performance between the examined devices under hot humid conditions; however, the wet fabric device had superior thermal performance under sub-humid conditions when compared to the other IECSs. In the three climatic scenarios where the proposed system was tested, the wet fabric managed to reduce the indoor air temperature by 6.6 °C, 5.3 °C, and 5.1 °C, respectively, as compared to the outdoor air temperatures.
Water Distribution in the Ultra-Deep Shale of the Wufeng–Longmaxi Formations from the Sichuan Basin
Authors: Gao Ping , Xiao Xianming , Hu Dongfeng , Liu Ruobing , Cai Yidong , Yuan Tao , Meng Guangming
Published: March 2022

Recently, deep and ultra-deep shales (depth >3500 m) of the Lower Paleozoic Wufeng–Longmaxi formations (WF–LMX) have become attractive targets for shale gas exploration and development in China, and their gas contents may be influenced by the occurrence of water to some extent. However, the water content and its distribution in the different nanopores of the deep and ultra-deep shales have rarely been reported. In this study, a suite of the WF–LMX ultra-deep shale samples (5910–5965 m depth) from the Well PS1 was collected for water content measurements, and low-pressure CO2 and N2 adsorption experiments of both as-received and experimentally dried shale samples were carried out to investigate the distribution of water in the different nanopores. Since the studied ultra-deep shales are characterized by higher thermal maturity (equivalent vitrinite reflectance (EqVRo) > 2.5 %) and ultra-low water saturation, the pore water is generally dominated by irreducible water. The content of irreducible water of the studied shales varies from 1.57 to 13.66 mg/g, averaging 6.74 mg/g. Irreducible water may mainly occur in the clay-hosted pores, while it could also be hosted in parts of organic pores of organic-rich shales. Irreducible water is primarily distributed in non-micropores rather than in micropores of the studied shales, which mainly occurs in micopores with a diameter of 0.4–0.6 nm and mesopores with a diameter of 2–10 nm. Very low contents of irreducible water could reduce the specific surface area and volume of non-micropores of the shales to some extent, but the effect of irreducible water on the specific surface area of non-micropores was more significant than the volume of non-micropores, especially for organic-rich shale samples. The ultra-deep shale gas may be predominately composed of free gas, so low contents of irreducible water may play a limited role in its total gas contents. Overall, our findings can be helpful for a better understanding of water distribution in the highly-matured shales, and provide a scientific basis for ultra-deep shale gas exploration.
Effects of Multi-Stage Split Injection on Efficiency and Emissions of Light-Duty Diesel Engine
Authors: Kang Seungwoo , Lee Sanguk , Bae Choongsik
Published: March 2022

The efficiency of light-duty diesel engines should be improved for further emissions regulation. Multi-stage split injection with five injection events was investigated for improvement in efficiency at low-load conditions. The injection timing and quantity were adjusted to achieve a smooth in-cylinder pressure rise and continuous heat release. The multi-stage split injection was compared to injection strategies involving two-pilot and single-main injections. A 0.5 L single-cylinder diesel engine experiment was conducted under low-load conditions. Two multi-stage split injection processes with different combustion phases were developed. The multi-stage split injections yielded a smooth in-cylinder pressure trace and a lower peak heat release rate than the two-pilot injection process. The combustion duration was shorter for multi-stage split injection with an advanced combustion phase, and the fuel consumption was reduced by 1.78% with lower heat transfer, exhaust heat, and combustion loss. The multi-stage split injection flame penetration was shorter than the two-pilot injections. The shorter flame penetration and lower tip velocity reduced the heat transfer to the combustion chamber. The PM emissions were also reduced by 30% under the same NOx emissions, because increased PM oxidation and divided fuel injection prevented flame diffusion and improved air utilization.
An Analytical Algorithm for Extracting Model Parameters in a Lumped-Parameter Equivalent Circuit of Solar Cells
Authors: Ma Yunhan , Liu Jingxian , Huang Junkai , Deng Wanling
Published: March 2022

An analytical algorithm is proposed to extract model parameters in a single-diode lumped-parameter equivalent circuit of solar cells. In the calculation process, six relevant factors in the datasheet are necessary to establish a set of transcendental equations. This set of equations is analyzed and solved to acquire accurate values for the model parameters, by retaining equation items with important physical significance. Furthermore, based on simulations and reconstruction experiments, verifications show the accuracy and universality of the algorithm. Therefore, the proposed algorithm can be regarded as a valid solution for estimating the model parameters of a single-diode lumped-parameter circuit of solar cells.
Guest Editorial: Special Issue on Designs and Algorithms of Localization in Vehicular Networks
Authors: Lee Sangwoo , Kim Sunwoo
Published: March 2022

We have been witnessing a paradigm shift in road transport systems over the last few years with the advent of autonomous vehicles and emerging road applications for road safety and traffic efficiency [...]
Analysis of Control-System Strategy and Design of a Small Modular Reactor with Different Working Fluids for Electricity and Hydrogen Production as Part of a Decentralised Mini Grid
Authors: Gad-Briggs Arnold , Osigwe Emmanuel , Jafari Soheil , Nikolaidis Theoklis
Published: March 2022

Hydrogen is increasingly being viewed as a significant fuel for future industrial processes as it offers pathways to zero emission. The UK sees hydrogen as one of a handful of low-carbon solutions for transition to net zero. Currently, most hydrogen production is from steam reforming of natural gas or coal gasification, both of which involve the release of carbon dioxide. Hydrogen production from mini decentralised grids via a thermochemical process, coupled with electricity production, could offer favourable economics for small modular reactors (SMRs), whereby demand or grid management as a solution would include redirecting the power for hydrogen production when electricity demand is low. It also offers a clean-energy alternative to the aforementioned means. SMRs could offer favourable economics due to their flexible power system as part of the dual-output function. This study objective is to investigate the critical performance parameters associated with the nuclear power plant (NPP), the cycle working fluids, and control-system design for switching between electricity and hydrogen demand to support delivery as part of a mini grid system for a reactor power delivering up to approximately 600 MWth power. The novelty of the work is in the holistic parametric analysis undertaken using a novel in-house tool, which analyses the NPP using different working fluids, with a control function bolt-on at the offtake for hydrogen production. The results indicate that the flow conditions at the offtake can be maintained. The choice of working fluids affects the pressure component. However, the recuperator and heat-exchanger effectiveness are considered as efficiency-limiting factors for hydrogen production and electricity generation. As such, the benefit of high-technology heat exchangers cannot be underestimated. This is also true when deciding on the thermochemical process to bolt onto the plant. The temperature of the gas at the end of the pipeline should also be considered to ensure that the minimum temperature-requirement status for hydrogen production is met.
Integrated Volt/Var Control Method for Voltage Regulation and Voltage Unbalance Reduction in Active Distribution Networks
Authors: Afandi Izzah , Agalgaonkar Ashish P. , Perera Sarath
Published: March 2022

The emergence of distributed generation such as solar systems has introduced new challenges in distribution networks that are becoming more apparent with increasing penetration levels. The time mismatch between peak load and peak generation can make voltage levels in distribution networks swing towards extreme limits during a day. Distribution network service providers are struggling to cater for new distributed generation installations while ensuring that the quality of steady state supply voltage meets stipulated requirements. The segregation between medium and low voltage networks in control strategies may result in unnecessary or worse, opposing control actions leading to voltage issues and control on one side of the distribution network influencing the other. By developing an efficient volt/var control method, the steady state voltage level and voltage unbalance in a comprehensive distribution network can be controlled simultaneously. This paper analyses voltage issues and volt/var control in medium and low voltage networks as a whole, unabridged problem. This paper proposes a pragmatic and effective volt/var control method that addresses voltage regulation and voltage unbalance simultaneously using existing infrastructure. The proposed control method is implemented on three types of representative Australian distribution networks and results obtained demonstrate that the proposed volt/var control can simultaneously manage voltage level and voltage unbalance whilst reducing the number of tap change operations and maximizing solar penetration.
A Simplified Modeling Approach of Floating Offshore Wind Turbines for Dynamic Simulations
Authors: López-Queija Javier , Robles Eider , Llorente Jose Ignacio , Touzon Imanol , López-Mendia Joseba
Published: March 2022

Currently, floating offshore wind is experiencing rapid development towards a commercial scale. However, the research to design new control strategies requires numerical models of low computational cost accounting for the most relevant dynamics. In this paper, a reduced linear time-domain model is presented and validated. The model represents the main floating offshore wind turbine dynamics with four planar degrees of freedom: surge, heave, pitch, first tower fore-aft deflection, and rotor speed to account for rotor dynamics. The model relies on multibody and modal theories to develop the equation of motion. Aerodynamic loads are calculated using the wind turbine power performance curves obtained in a preprocessing step. Hydrodynamic loads are precomputed using a panel code solver and the mooring forces are obtained using a look-up table for different system displacements. Without any adjustment, the model accurately predicts the system motions for coupled stochastic wind–wave conditions when it is compared against OpenFAST, with errors below 10% for all the considered load cases. The largest errors occur due to the transient effects during the simulation runtime. The model aims to be used in the early design stages as a dynamic simulation tool in time and frequency domains to validate preliminary designs. Moreover, it could also be used as a control design model due to its simplicity and low modeling order.
Thermoelectric Performance Evaluation and Optimization in a Concentric Annular Thermoelectric Generator under Different Cooling Methods
Authors: Yang Wenlong , Zhu Wenchao , Yang Yang , Huang Liang , Shi Ying , Xie Changjun
Published: March 2022

To ensure effective heat recovery of thermoelectric generators, a cooling system is necessary to maintain the working temperature difference of the thermoelectric couples, which decreases continuously due to thermal diffusion. In order to evaluate and improve the thermoelectric performance of a concentric annular thermoelectric generator under various cooling methods, a comprehensive numerical model of the thermo-fluid-electric multi-physics field for an annular thermoelectric generator with a concentric annular heat exchanger was developed using the finite-element method. The effects of four cooling methods and different exhaust parameters on the thermoelectric performance were investigated. The results show that, in comparison to the cocurrent cooling pattern, the countercurrent cooling pattern effectively reduces temperature distribution non-uniformity and hence increases the maximum output power; however, it requires more thermoelectric semiconductor materials. Furthermore, when using the cocurrent air-cooling method, high exhaust temperatures may result in lower output power; high exhaust mass flow rates result in high exhaust resistance and reduce system net power. The maximum net power output Pnet = 432.42 W was obtained using the countercurrent water-cooling, corresponding to an optimal thermoelectric semiconductor volume of 9.06 × 10−4 m3; when compared to cocurrent water-cooling, the maximum net power increased by 8.9%, but the optimal thermoelectric semiconductor volume increased by 21.4%.
A Versatile Model for Estimating the Fuel Consumption of a Wide Range of Transport Modes
Authors: Khan Ankur Atiquzzaman , Kraus Stefan , Grube Thomas , Castro Rui , Stolten Detlef
Published: March 2022

The importance of a flexible and comprehensive vehicle fuel consumption model cannot be understated for understanding the implications of the modal changes currently occurring in the transportation sector. In this study, a model is developed to determine the tank-to-wheel energy demand for passenger and freight transportation within Germany for different modes of transport. These modes include light-duty vehicles (LDVs), heavy-duty vehicles (HDVs), airplanes, trains, ships, and unmanned aviation. The model further estimates future development through 2050. Utilizing standard driving cycles, backward-looking longitudinal vehicle models are employed to determine the energy demand for all on-road vehicle modes. For non-road vehicle modes, energy demand from the literature is drawn upon to develop the model. It is found that various vehicle parameters exert different effects on vehicle energy demand, depending on the driving scenario. Public transportation offers the most energy-efficient means of travel in the forms of battery electric buses (33.9 MJ/100 pkm), battery electric coaches (21.3 MJ/100 pkm), fuel cell electric coaches (32.9 MJ/100 pkm), trams (43.3 MJ/100 pkm), and long-distance electric trains (31.8 MJ/100 pkm). International shipping (9.9 MJ/100 tkm) is the most energy-efficient means of freight transport. The electrification of drivetrains and the implementation of regenerative braking show large potential for fuel consumption reduction, especially in urban areas. Occupancy and loading rates for vehicles play a critical role in determining the energy demand per passenger-kilometer for passenger modes, and tonne-kilometer for freight modes.