bluuebunny/crossref_metadata_2025 huggingface dataset:
UAV4PE: An Open-Source Framework to Plan UAV Autonomous Missions for Planetary Exploration
Authors: Galvez-Serna Julian , Vanegas Fernando , Brar Shahzad , Sandino Juan , Flannery David , Gonzalez Felipe
Published: December 2022

Autonomous Unmanned Aerial Vehicles (UAV) for planetary exploration missions require increased onboard mission-planning and decision-making capabilities to access full operational potential in remote environments (e.g., Antarctica, Mars or Titan). However, the uncertainty introduced by the environment and the limitation of available sensors has presented challenges for planning such missions. Partially Observable Markov Decision Processes (POMDPs) are commonly used to enable decision-making and mission-planning processes that account for environmental, perceptional (extrinsic) and actuation (intrinsics) uncertainty. Here, we propose the UAV4PE framework, a testing framework for autonomous UAV missions using POMDP formulations. This framework integrates modular components for simulation, emulation, UAV guidance, navigation and mission planning. State-of-the-art tools such as python, C++, ROS, PX4 and JuliaPOMDP are employed by the framework, and we used python data-science libraries for the analysis of the experimental results. The source code and the experiment data are included in the UAV4PE framework. The POMDP formulation proposed here was able to plan and command a UAV-based planetary exploration mission in simulation, emulation and real-world experiments. The experiments evaluated key indicators such as the mission success rate, the surface area explored and the number of commands (actions) executed. We also discuss future work aimed at improving the UAV4PE framework, and the autonomous UAV mission planning formulation for planetary exploration.
Near-Ground Delivery Drones Path Planning Design Based on BOA-TSAR Algorithm
Authors: Luo Yuan , Lu Jiakai , Zhang Yi , Zheng Kai , Qin Qiong , He Lin , Liu Yanyu
Published: December 2022

With the advancement of technology and the rise of the unmanned aerial vehicle industry, the use of drones has grown tremendously. For drones performing near-ground delivery missions, the problem of 3D space-based path planning is particularly important in the autonomous navigation of drones in complex spaces. Therefore, an improved butterfly optimization (BOA-TSAR) algorithm is proposed in this paper to achieve the autonomous pathfinding of drones in 3D space. First, this paper improves the randomness strategy of the initial population generation in the butterfly optimization algorithm (BOA) via the Tent chaotic mapping method, by means of the removal of the short-period property, which balances the equilibrium of the initial solutions generated by the BOA algorithm in the solution space. Secondly, this paper improves the shortcomings of the BOA algorithm in terms of slower convergence, lower accuracy, and the existence of local optimal stagnation when dealing with high-dimensional complex functions via adaptive nonlinear inertia weights, a simulated annealing strategy, and stochasticity mutation with global adaptive features. Finally, this paper proposes an initial population generation strategy, based on the 3D line of sight (LOS) detection method, to further reduce the generation of path interruption points while ensuring the diversity of feasible solutions generated by the BOA algorithm for paths. In this paper, we verify the superior performance of BOA-TSAR by means of simulation experiments. The simulation results show that BOA-TSAR is very competitive among swarm intelligence (SI) algorithms of the same type. At the same time, the BOA-TSAR algorithm achieves the optimal path length measure and smoothness measure in the path-planning experiment.
A Case Study of Vignetting Nonuniformity in UAV-Based Uncooled Thermal Cameras
Authors: Yuan Wenan , Hua Weiyun
Published: December 2022

Uncooled thermal cameras have been employed as common UAV payloads for aerial temperature surveillance in recent years. Due to the lack of internal cooling systems, such cameras often suffer from thermal-drift-induced nonuniformity or vignetting despite having built-in mechanisms to minimize the noise. The current study examined a UAV-based uncooled thermal camera vignetting regarding camera warmup time, ambient temperature, and wind speed and direction, and proposed a simple calibration-based vignetting migration method. The experiments suggested that the camera needed to undergo a warmup period to achieve stabilized performance. The required warmup duration ranged from 20 to 40 min depending on ambient temperature. Camera vignetting severity increased with camera warmup time, decreasing ambient temperature, and wind presence, while wind speed and direction did not make a difference to camera vignetting during the experiments. Utilizing a single image of a customized calibration target, we were able to mitigate vignetting of outdoor images captured in a 30 min duration by approximately 70% to 80% in terms of the intra-image pixel standard deviation (IISD) and 75% in terms of the pixel-wise mean (PWMN) range. The results indicated that outdoor environmental conditions such as air temperature and wind speed during short UAV flights might only minimally influence the thermal camera vignetting severity and pattern. Nonetheless, frequent external shutter-based corrections and considering the camera nonlinear temperature response in future studies have the potential to further improve vignetting correction efficacy for large scene temperature ranges.
The Use of Drones to Determine Rodent Location and Damage in Agricultural Crops
Authors: Keshet Dor , Brook Anna , Malkinson Dan , Izhaki Ido , Charter Motti
Published: December 2022

Rodent pests cause extensive damage to agricultural crops worldwide. Farmers’ ability to monitor rodent activity and damage within crops is limited due to their inability to simultaneously survey vast agricultural areas for rodent activity, the inability to enter certain fields, and the difficulty of monitoring rodent numbers, as well as using traps due to trap shyness and high labor costs. Drones can potentially be used to monitor rodent numbers and damage because they can cover large areas quickly without damaging crops and carry sensors that provide high-resolution imagery. Here, we investigated whether rodent activity (Levant voles Microtus guentheri and house mice Mus musculus) is related to vegetation health and biomass in Alfalfa (Medicago sativa) fields. We used a drone to photograph one hundred and twenty 10 × 10 m plots in nine fields and calculate the plots’ normalized difference vegetation index (NDVI) and biomass. On each plot, we also trapped rodents, counted rodent burrows, and evaluated the harvested dry crop yield. The number of burrows was positively related to the number of Levant voles trapped (F1,110 = 12.08, p < 0.01) and negatively related to the number of house mice trapped (F1,110 = 5.23, p < 0.05). Biomass extracted from drone images was positively related to the yield harvested by hand (F1,83 = 3.81, p < 0.05). Farmers, therefore, can use burrow counting in place of trapping Levant voles, and biomass estimates from drones can be used in place of manual yield calculations. NDVI (F1,95 = 73.14, p < 0.001) and biomass (F1,95 = 79.58, p < 0.001) were negatively related to the number of Levant voles trapped, and the number of burrows were not related to the number of house mice trapped. We demonstrate that drones can be used to assist farmers in determining the Levant vole presence and damage within crop fields to control rodents using precision agriculture methods, such as adding rodenticides in specific areas, thus increasing efficiency and decreasing the amount of pesticides used.
Path Planning Research of a UAV Base Station Searching for Disaster Victims’ Location Information Based on Deep Reinforcement Learning
Authors: Zhao Jinduo , Gan Zhigao , Liang Jiakai , Wang Chao , Yue Keqiang , Li Wenjun , Li Yilin , Li Ruixue
Published: December 2022

Aiming at the path planning problem of unmanned aerial vehicle (UAV) base stations when performing search tasks, this paper proposes a Double DQN-state splitting Q network (DDQN-SSQN) algorithm that combines state splitting and optimal state to complete the optimal path planning of UAV based on the Deep Reinforcement Learning DDQN algorithm. The method stores multidimensional state information in categories and uses targeted training to obtain optimal path information. The method also references the received signal strength indicator (RSSI) to influence the reward received by the agent, and in this way reduces the decision difficulty of the UAV. In order to simulate the scenarios of UAVs in real work, this paper uses the Open AI Gym simulation platform to construct a mission system model. The simulation results show that the proposed scheme can plan the optimal path faster than other traditional algorithmic schemes and has a greater advantage in the stability and convergence speed of the algorithm.
Evaluating the Structural Robustness of Large-Scale Emerging Industry with Blurring Boundaries
Authors: Li Yang , Li Huajiao , Guo Sui , Liu Yanxin
Published: December 2022

The present large-scale emerging industry evolves into a form of an open system with blurring boundaries. However, when complex structures with numerous nodes and connections encounter an open system with blurring boundaries, it becomes much more challenging to effectively depict the structure of an emerging industry, which is the precondition for robustness evaluation. Therefore, this study proposes a novel framework based on a data-driven percolation process and complex network theory to depict the network skeleton and thus evaluate the structural robustness of large-scale emerging industries. The empirical data we used are actual firm-level transaction data in the Chinese new energy vehicle industry in 2019, 2020, and 2021. We applied our method to explore the transformation of structural robustness in the Chinese new energy vehicle industry in pre-COVID (2019), under-COVID (2020), and post-COVID (2021) eras. We unveil that the Chinese new energy vehicle industry became more robust against random attacks in the post-COVID era than in pre-COVID.
Speed of Evolution and Correlations in Multi-Mode Bosonic Systems
Authors: Kiselev Alexei D. , Ranim Ali , Rybin Andrei V.
Published: December 2022

We employ an exact solution of the thermal bath Lindblad master equation with the Liouvillian superoperator that takes into account both dynamic and environment-induced intermode couplings to study the speed of evolution and quantum speed limit (QSL) times of a open multi-mode bosonic system. The time-dependent QSL times are defined from quantum speed limits, giving upper bounds on the rate of change of two different measures of distinguishability: the fidelity of evolution and the Hilbert–Schmidt distance. For Gaussian states, we derive explicit expressions for the evolution speed and the QSL times. General analytical results are applied to the special case of a two-mode system where the intermode couplings can be characterized by two intermode coupling vectors: the frequency vector and the relaxation rate vector. For the system initially prepared in a two-mode squeezed state, dynamical regimes are generally determined by the intermode coupling vectors, the squeezing parameter and temperature. When the vectors are parallel, different regimes may be associated with the disentanglement time, which is found to be an increasing (a decreasing) function of the length of the relaxation vector when the squeezing parameter is below (above) its temperature-dependent critical value. Alternatively, we study dynamical regimes related to the long-time asymptotic behavior of the QSL times, which is characterized by linear time dependence with the proportionality coefficients defined as the long-time asymptotic ratios. These coefficients are evaluated as a function of the squeezing parameter at varying temperatures and relaxation vector lengths. We also discuss how the magnitude and orientation of the intermode coupling vectors influence the maximum speed of evolution and dynamics of the entropy and the mutual information.
Efficient System for Delimitation of Benign and Malignant Breast Masses
Authors: Mújica-Vargas Dante , Matuz-Cruz Manuel , García-Aquino Christian , Ramos-Palencia Celia
Published: December 2022

In this study, a high-performing scheme is introduced to delimit benign and malignant masses in breast ultrasound images. The proposal is built upon by the Nonlocal Means filter for image quality improvement, an Intuitionistic Fuzzy C-Means local clustering algorithm for superpixel generation with high adherence to the edges, and the DBSCAN algorithm for the global clustering of those superpixels in order to delimit masses’ regions. The empirical study was performed using two datasets, both with benign and malignant breast tumors. The quantitative results with respect to the BUSI dataset were JSC≥0.907, DM≥0.913, HD≥7.025, and MCR≤6.431 for benign masses and JSC≥0.897, DM≥0.900, HD≥8.666, and MCR≤8.016 for malignant ones, while the MID dataset resulted in JSC≥0.890, DM≥0.905, HD≥8.370, and MCR≤7.241 along with JSC≥0.881, DM≥0.898, HD≥8.865, and MCR≤7.808 for benign and malignant masses, respectively. These numerical results revealed that our proposal outperformed all the evaluated comparative state-of-the-art methods in mass delimitation. This is confirmed by the visual results since the segmented regions had a better edge delimitation.
How Students’ Inspirations and Aspirations Impact Motivation and Engagement in the First Year of Study
Authors: Lacey Melissa M. , Shaw Hollie , Abbott Nikki , Dalton Caroline J. , Smith David P.
Published: December 2022

Within this study, we aim to better understand the inspirations and aspirations of first year Biosciences and Chemistry undergraduates, how these change over the first year of study and their impact on motivation and engagement. Participants were asked to write a short reflective piece at the start of Welcome Week in their first year of undergraduate study. Thematic analysis identified four themes surrounding inspirations and aspirations. The most common theme was students naming a specific career as their aspiration (58%), followed by being inspired by work experience, aspiring to undertake further study and finally personal experience of a specific illness. Our findings showed that students’ career aspirations differed depending on ethnicity, with ambitions for medicine and laboratory work showing a marked increase in some ethnically marginalised groups. Focus groups undertaken at the end of the first year of study highlight increased motivation and engagement when students feel their course content aligns with their career aims. Conversely, students are disengaged by course material they feel is irrelevant to their chosen career. Here, we will discuss the impact of these findings on creating an inclusive curriculum and the career readiness of the student body. Conclusions apply to career development modules and how the applied nature of a course can lead to engagement and higher motivation for students as well as curriculum design.
Virtual Reality in Space Technology Education
Authors: Atta Ghada , Abdelsattar Amal , Elfiky Dalia , Zahran Mohamed , Farag Mohamed , Slim Salwa O.
Published: December 2022

The simplification of space science and technology for students K–12 is a challenging task for educators. Virtual reality and augmented reality are educational techniques that introduce the concept of educational games. Moreover, those techniques have a stunning effect on students. This work presents the utilization of virtual reality models to teach students about the satellite types, satellite subsystems, the satellite assembly and integration process, watching the rocket launch carrying the satellite and observing the satellite in its orbit in virtual space laboratories. A 10-min mission in virtual laboratories will effectively improve the learning outcomes. In addition to the VR feature, a set of activities and short movies are considered to be beneficial for use by students to enrich the teaching results. Finally, the VR model results confirmed that the students’ knowledge about the space technology cycle is boosted.
Multitask Learning Based Intra-Mode Decision Framework for Versatile Video Coding
Authors: Zouidi Naima , Kessentini Amina , Hamidouche Wassim , Masmoudi Nouri , Menard Daniel
Published: December 2022

In mid-2020, the new international video coding standard, namely versatile video coding (VVC), was officially released by the Joint Video Expert Team (JVET). As its name indicates, the VVC enables a higher level of versatility with better compression performance compared to its predecessor, high-efficiency video coding (HEVC). VVC introduces several new coding tools like multiple reference lines (MRL) and matrix-weighted intra-prediction (MIP), along with several improvements on the block-based hybrid video coding scheme such as quatree with nested multi-type tree (QTMT) and finer-granularity intra-prediction modes (IPMs). Because finding the best encoding decisions is usually preceded by optimizing the rate distortion (RD) cost, introducing new coding tools or enhancing existing ones requires additional computations. In fact, the VVC is 31 times more complex than the HEVC. Therefore, this paper aims to reduce the computational complexity of the VVC. It establishes a large database for intra-prediction and proposes a multitask learning (MTL)-based intra-mode decision framework. Experimental results show that our proposal enables up to 30% of complexity reduction while slightly increasing the Bjontegaard bit rate (BD-BR).
Self-Decoupled MIMO Antenna Realized by Adjusting the Feeding Positions
Authors: He Yangyang , Cheng Yi-Feng , Luo Jiang
Published: December 2022

This paper proposes a novel decoupling technique achieved by adjusting the position of feeding probes of antennas. Two inherent radiation modes (patch mode and monopole mode), with different patterns and polarizations, are simultaneously excited by the same feeding probe. High isolation is realized based on manipulating the relationship of two-mode couplings by moving the feeding positions. Since the two radiation modes are generated by the same antenna element, the proposed MIMO antenna features a simple structure and compact size. For verification, a two-element array with center-to-center spacing of 0.404 λ0 (λ0 is the wavelength in the air) is prototyped and characterized. Simulation and experimental results show that the proposed novel technique can offer higher port isolation (>18.1 dB), increased efficiency (>70%), and a lower envelope correlation coefficient (ECC < 0.1) in the operating frequency band (11.61–12.49 GHz).
An Ontology-Based Approach for Knowledge Acquisition: An Example of Sustainable Supplier Selection Domain Corpus
Authors: Konys Agnieszka
Published: December 2022

Selecting the right supplier is a critical decision in sustainable supply chain management. Sustainable supplier selection plays an important role in achieving a balance between the three pillars of a sustainable supply chain: economic, environmental, and social. One of the most crucial aspects of running a business in this regard is sustainable supplier selection, and, to this end, an accurate and reliable approach is required. Therefore, the main contribution of this paper is to propose and implement an ontology-based approach for knowledge acquisition from the text for a sustainable supplier selection domain. This approach is dedicated to acquiring complex relationships from texts and coding these in the form of rules. The expected outcome is to enrich the existing domain ontology by these rules to obtain higher relational expressiveness, make reasoning, and produce new knowledge.
A Compact Model for Single-Event Transient in Fully Depleted Silicon on Insulator MOSFET Considering the Back-Gate Voltage Based on Time-Domain Components
Authors: Wang Kewei , Zhang Xinyi , Li Bo , Li Duoli , Zhao Fazhan , Bu Jianhui , Han Zhengsheng
Published: December 2022

FDSOI (Fully Depleted Silicon On Insulator) devices have a good performance in anti-single-event circuits. However, the bipolar amplification effect becomes a severe problem due to the buried oxide. The previous models for Single Event Transient (SET) of FDSOI did not fully consider the current of all components. Most importantly, they did not take the influence of the back-gate voltage into account. Thus, this paper presents a modeling method for the SET current in FDSOI MOSFET where all three components are modeled individually. The prompt current and diffusion current are modeled with a current source respectively. The Berkeley Short-channel IGFET Model for Silicon-on-Insulator (BSIMSOI) model is integrated into this model to calculate the bipolar amplification current. Compared to using the bipolar transistor model, this method avoids additional current input from the base electrode. It is more consistent with the mechanism of bipolar amplification effect for FDSOI devices without body contact. Instantaneously, an improved model is proposed that considers the influence of the back-gate voltage on the SET of the FDSOI devices. All models are validated through Technology Computer Aided Design (TCAD)simulation results.
Development and Testing of Performance Scale Application as an Effective Electronic Tool to Enhance Students’ Academic Achievements
Authors: Ozdamli Fezile , Ababneh Mustafa , Karagozlu Damla , Aljarrah Aayat
Published: December 2022

Performance scale application (PSA) usage in the classroom is underutilized, despite the rapid progress of mobile phone and e-learning technology. Lack of self-learning, evaluation, satisfaction, and inability to choose appropriate specialties influence students’ academic achievement in secondary school. The objective of this study is to investigate the development and testing of PSA on students’ learning achievement in secondary school. The PSA was developed on the Android mobile operating system using the extra trees regression algorithm to predict student achievement in secondary school. Students in the 11th grade basic specialty were considered. Three specialties were used, namely scientific, literary, and industry. The variables examined include improving evaluation (IME), improving communication (IMC), improving scientific (IMSC), and satisfaction of learning (SOL). The findings demonstrated that the PSA accurately predicted the students’ choice of specialty, IMC, IMSC, SOL, personalized learning (L), distance L, mobile L, self L, and specialty L. The findings also indicated a positive and significant effect of the PSA on students’ learning achievement. This validates that the extra trees regression is an effective tool for the development of PSA. In conclusion, the PSA has efficiently predicted the choice of specialties and academic achievements of students in secondary schools.
Deep Learning Techniques for Pattern Recognition in EEG Audio Signal-Processing-Based Eye-Closed and Eye-Open Cases
Authors: Husham Almukhtar Firas , Abbas Ajwad Asmaa , Kamil Amna Shibib , Jaleel Refed Adnan , Adil Kamil Raya , Jalal Mosa Sarah
Published: December 2022

Recently, pattern recognition in audio signal processing using electroencephalography (EEG) has attracted significant attention. Changes in eye cases (open or closed) are reflected in distinct patterns in EEG data, gathered across a range of cases and actions. Therefore, the accuracy of extracting other information from these signals depends significantly on the prediction of the eye case during the acquisition of EEG signals. In this paper, we use deep learning vector quantization (DLVQ), and feedforward artificial neural network (F-FANN) techniques to recognize the case of the eye. The DLVQ is superior to traditional VQ in classification issues due to its ability to learn a code-constrained codebook. On initialization by the k-means VQ approach, the DLVQ shows very promising performance when tested on an EEG-audio information retrieval task, while F-FANN classifies EEG-audio signals of eye state as open or closed. The DLVQ model achieves higher classification accuracy, higher F score, precision, and recall, as well as superior classification abilities as compared to the F-FANN.
PDDQN-HHVBF Routing Protocol Based on Empirical Priority DDQN to Improve HHVBF
Authors: Chen Yan , Bai Jie , Li Yun
Published: December 2022

Reinforcement learning (RL) has been successfully applied to underwater routing protocols due to its powerful ability of distributed decision making. However, the traditional RL has slow convergence speed and low learning efficiency in underwater. Meanwhile, too many studies focus on using RL to find low hop paths rather than short distance paths in underwater routing, while the long distance of ocean communication is the significant reason for the packets collision and energy loss in underwater. Based on the above problems, this paper proposes the PDDQN-HHVBF (Empirical Priority DDQN to Improve Hop-by-Hop Vector-Based Forwarding) protocol for M-UWSNs (Mobile source node Underwater Wireless Sensor Networks), in which AUV (Autonomous Underwater Vehicle) is used as source node to collect data and transmit data hop-by-hop to Sink node through underwater nodes. The proposed protocol is adopt to find the optimal relay nodes in pipeline referred HHVBF protocol by requesting the max Q value according to three states of the residual energy of nodes, the number of candidate relay nodes and the geographical location information of all candidate relay nodes in time. This because PDDQN-HHVBF avoids the strong correlation between data samples, and its playback samples will not be too concentrated or lead to over fitting. It can converge rapidly in underwater environment. In addition, the requesting Q value mechanism related to the geographical location information can find the optimal relay node with short distance propagation in large-scale networks, which will reduce the number of packets collision, and then saving energy and improving network lifetime. In addtion, the in-time requesting for Q value can cope with the nodes drift affected by ocean current movement. In addition, the Q value related to the residual energy of nodes and the number of candidate relay nodes will effectively load balancing nodes, prolong network lifetime and avoid routing holes. Finally, the “Store-Carry-Forward” mechanism proposed for AUV, this mechanism store and carry packets when facing routing holes until find the optimal relay node for forwarding, which will improve PDR and save energy of AUV significantly. The simulation results show that, the proposed PDDQN-HHVBF protocol converges about 30% faster than DQELR. Although its delay is higher than DQELR and ROEVA for requesting Q value. It outperforms VBF, HHVBF, DQELR, and ROEVA in terms of energy efficency, PDR, and lifetime, which are analyzed by varying speed of nodes from 0 m/s to 3 m/s with 1000 nodes and varying number of nodes from 500 to 3000 with speed in 1 m/s.
Experimental Rock Characterisation of Upper Pannonian Sandstones from Szentes Geothermal Field, Hungary
Authors: Koroncz Péter , Vizhányó Zsanett , Farkas Márton Pál , Kuncz Máté , Ács Péter , Kocsis Gábor , Mucsi Péter , Fedorné Szász Anita , Fedor Ferenc , Kovács János
Published: December 2022

The Upper Pannonian (UP) sandstone formation has been utilised for thermal water production in Hungary for several decades. Although sustainable utilisation requires the reinjection of cooled geothermal brine into the host rock, only a fraction of the used water is reinjected in the country. UP sandstone formation is reported to exhibit low injectivity, making reinjection challenging, and its petrophysical properties are poorly known, which increases uncertainty in designing operational parameters. The goal of the study is to provide experimental data and to gain a better understanding of formation characteristics that control injectivity and productivity issues in Upper Pannonian sandstone layers. Petrographical characterisation and petrophysical laboratory experiments are conducted on cores retrieved from two wells drilled in the framework of an R&D project at the depth of between 1750 m and 2000 m. The experiments, such as grain density, porosity, permeability, and ultrasonic velocity, as well as thin section, grain size distribution, XRD, and SEM analyses, are used to determine Petrophysical Rock Types (PRT) that share distinct hydraulic (flow zone indicator, FZI) and petrophysical characteristics. These are used to identify well intervals with lower potential for injectivity issues. The results imply that fines migration due to formation erosion is one of the key processes that must be better understood and controlled in order to mitigate injectivity issues at the study area. Future investigation should include numerical and experimental characterisation of formation damage, including water–rock interaction tests, critical flow velocity measurements, and fines migration analysis under reservoir conditions.
Flow around an Oscillating Cylinder at Low Reynolds Number with Forced Convection: Effect of Corner Radius and Reynolds Number
Authors: Sarout Yuvraj , Islam Md. , Fatt Yap , Janajreh Isam
Published: December 2022

This numerical study investigated the flow-induced vibration (FIV) on non-heated and heated cylinders with different normalized corner radii (r*) at different Reynolds numbers (Re). Four different values of r* were considered (i.e., 0 (square cylinder), 0.5, 0.75, and 1.0 (circular cylinder)) at three different Re: 100, 150, and 200 within the laminar regime. The cylinder constrained in the axial direction and oscillated transversally was considered for a fixed nondimensional cylinder mass (m*)  of 10 and a reduced velocity (Ur) of 4.92. The effect of r* and Re could be seen in the vibration modes of cylinders. The two-dimensional incompressible Navier–Stokes and energy equations were solved together with Newton’s Second Law governing the motion of the cylinder with the help of a computational solver. Four different modes were observed in this study: Mode-I characterized by exceptionally low amplitude; Mode-II characterized by fluctuating amplitude known as hysteresis (beating); Mode-III characterized by high amplitude due to synchronization or lock-in; and Mode-IV characterized by the monotonic oscillation of fixed amplitude. For r* = 1, synchronization phenomenon/lock-in was observed. For the heated cylinder cases, due to the change in the normalized corner radius, a notable change in nondimensional vibrational amplitude A/D and the average Nusselt number Nuavg was seen. It was observed that A/D was higher when lock-in occurred (at Re = 100 and r* = 1), leading to a rise in Nuavg by 47.9% compared to Re = 100 and r* = 0. Due to the change in r*, a shifting phenomenon was observed at Re = 150, r* = 0.75 and Re = 200, r* = 1. A major change in Nuavg was observed from the circular cylinder to square cylinder at different Re. The beating phenomenon was observed at Re = 100 for r* = 0.75, which was similar to that occurring at Re = 150 and r* = 0.5, and those at Re = 200 and r* = 0. Heat transfer and wake structure parameters were found to be dependent on r* and Re.
Small-Scale Hybrid and Polygeneration Renewable Energy Systems: Energy Generation and Storage Technologies, Applications, and Analysis Methodology
Authors: Homa Maksymilian , Pałac Anna , Żołądek Maciej , Figaj Rafał
Published: December 2022

The energy sector is nowadays facing new challenges, mainly in the form of a massive shifting towards renewable energy sources as an alternative to fossil fuels and a diffusion of the distributed generation paradigm, which involves the application of small-scale energy generation systems. In this scenario, systems adopting one or more renewable energy sources and capable of producing several forms of energy along with some useful substances, such as fresh water and hydrogen, are a particularly interesting solution. A hybrid polygeneration system based on renewable energy sources can overcome operation problems regarding energy systems where only one energy source is used (solar, wind, biomass) and allows one to use an all-in-one integrated systems in order to match the different loads of a utility. From the point of view of scientific literature, medium- and large-scale systems are the most investigated; nevertheless, more and more attention has also started to be given to small-scale layouts and applications. The growing diffusion of distributed generation applications along with the interest in multipurpose energy systems based on renewables and capable of matching different energy demands create the necessity of developing an overview on the topic of small-scale hybrid and polygeneration systems. Therefore, this paper provides a comprehensive review of the technology, operation, performance, and economical aspects of hybrid and polygeneration renewable energy systems in small-scale applications. In particular, the review presents the technologies used for energy generation from renewables and the ones that may be adopted for energy storage. A significant focus is also given to the adoption of renewable energy sources in hybrid and polygeneration systems, designs/modeling approaches and tools, and main methodologies of assessment. The review shows that investigations on the proposed topic have significant potential for expansion from the point of view of system configuration, hybridization, and applications.
Experimental Study of Pulsating Heat Pipes Filled with Nanofluids under the Irradiation of Solar Simulator
Authors: Liu Shubo , Yang Yi , Ma Kuiyuan , Jin Haichuan , Jin Xin
Published: December 2022

Developing renewable energy technologies, especially solar technology, is of vital importance to cope with increasing energy consumption. The existing solar thermal systems have the disadvantages of capturing solar energy inefficiently and needing additional pumping power to circulate the working fluid. A concept of a direct absorption pump-free solar thermal system that combines the advantages of nanoparticles and pulsating heat pipes (PHP) is proposed in this work. The effects of a variety of parameters including nanoparticle types, nanoparticle concentration, and nanofluid filling rate on the performance of PHP were studied. It was found that PHP has the best filling rate (80–90%) making the best heat transfer performance and minimizing the thermal resistance. The concentration of nanoparticles affects the input power of the pulsating heat pipe and thus the operation of the PHP. The nanofluid with relatively low concentration cannot absorb enough solar energy to drive the PHP to operate normally. Experimental research shows that the new solar thermal system can absorb solar energy efficiently and transfer the heat into the targeted area spontaneously, which may be an approach for future solar thermal utilization.
Design of Adaptive Fuzzy Sliding-Mode Control for High-Performance Islanded Inverter in Micro-Grid
Authors: Yang Yan , Wang Yeqin , Zhang Weixing , Li Zhenghao , Liang Rui
Published: December 2022

In this paper, an adaptive fuzzy sliding-mode control (AFSMC) system is investigated for an islanded inverter to achieve a high-performance power supply. A sliding mode control (SMC) law is designed initially to obtain both the voltage tracking error and the current tracking error of the inverter involved, to realize both the output-voltage regulation and the current protection with global stability. Moreover, to deal with uncertainties in the practical inverter system without the chattering phenomenon, an adaptive fuzzy system embedded with a self-adjustive translation width is developed to replace the switch term of the SMC. In addition, the adaptation laws, derived from the Lyapunov stability theorem, adjust the AFSMC parameters online to guarantee optimal and robust performance. Furthermore, the superior control performance of the proposed AFSMC is verified by a numerical simulation in MATLAB, producing experimental results on the prototype in comparison with the conventional SMC.
A Generalized Switched-Capacitor Multilevel Inverter Topology with Voltage Boosting Ability and Reduced Inrush Current
Authors: Anand Vishal , Singh Varsha , Sathik M. Jagabar , Almakhles Dhafer
Published: December 2022

This article presents a novel quadruple boost inverter (QBI) with an integrated boost stage that comprises an inductor, a capacitor, a switch, and an input source. The inductor on the input side limits the inrush current and also the capacitor charging current ripples. The QBI topology comprises a dc source, an input inductor, nine switches, three diodes, and capacitors. This produces a nine-level waveform, which reduces the need for additional filters such as inductors and capacitors. The proposed QBI is elementary, compact, and needs fewer components than existing nine levels inverter. Compared to the typical triangular carrier-based sinusoidal pulse width modulation, the newly developed parabolic level-shifted carrier has a much greater RMS value. Another advantage of the proposed topology is extension for generating higher voltage levels without increment in the blocking voltage across the switches. This makes the topology ideal for medium voltage high power applications. The output voltage has been determined in terms of selection, sizing, and expression. The proposed QBI is compared to existing similar nine-level inverters in order to assess its efficacy. The experiment is performed on a laboratory prototype to state the practical feasibility of QBI topology for the inductive load, variation in input, load, and modulation index.
A Modified Calculation Method for a Centered Water Nozzle Steam–Water Injector
Authors: Ke Hanbing , Xiao Qi , Long Chengyi , Liu Jialun , Shi Leitai , Tang Linghong
Published: December 2022

A centered water nozzle steam–water injector is driven by cold water to pump steam at a low pressure and to produce a high outlet water pressure. It can be used as a safety pump in a light water reactor to inject cooling water into the reactor core with no power supply in case of an accident. In this study, a modified calculation method for a centered water nozzle steam–water injector is proposed and verified by experimental data in the literature. The calculation method consists of a water nozzle model, a steam nozzle model, a mixing section model, and a shock wave model. Comparisons between the calculated results and the experimental results under different inlet steam pressures, inlet water pressures, and back pressures are conducted, and the calculated results show good agreement with the experimental results. The calculated results with different back pressures show that no shock wave occurs in the mixing section when the back pressure is small, but with the back pressure increasing, the pressure undergoes a dramatic increase in the throat tube, and the shock wave position moves towards the inlet of the mixing section. Due to the complexity of shock wave characteristics, it is necessary to conduct a more in-depth study of shock wave characteristics in the mixing section to determine more detailed boundary conditions for shock wave generation.
Production, Activation and CO2 Uptake Capacity of a Carbonaceous Microporous Material from Palm Oil Residues
Authors: Moliner Cristina , Focacci Simona , Antonucci Beatrice , Moreno Aldo , Biti Simba , Hamzah Fazlena , Martinez-Felipe Alfonso , Arato Elisabetta , Fernández Martín Claudia
Published: December 2022

While Malaysia produces about half of the world’s palm oil and is the largest producer and exporter worldwide, oil palm industries generate large amounts of lignocellulosic biomass waste as a sub-product with no economic market value other than feedstock for energy valorisation. With the aim to increase the sustainability of the sector, in this work we prepare new materials for CO2 capture from palm oil residues (empty fruit bunches and kernels). The biochar is obtained through the carbonisation of the residues and is physically and chemically activated to produce porous materials. The resulting microporous samples have similar properties to other commercial activated carbons, with BET surfaces in the 320–880 m2/g range and pore volumes of 0.1–0.3 cm3·g−1. The CO2 uptake at room temperature for physically activated biochar (AC) was 2.4–3.6 mmolCO2/gAC, whereas the average CO2 uptake for chemically activated biochar was 3.36–3.80 mmolCO2/gAC. The amount of CO2 adsorbed decreased at the highest temperature, as expected due to the exothermic nature of adsorption. These findings confirm the high potential of palm oil tree residues as sustainable materials for CO2 capture.
Numerical Simulation Study on Temporary Well Shut-In Methods in the Development of Shale Oil Reservoirs
Authors: Zhang Qitao , Liu Wenchao , Wei Jiaxin , Taleghani Arash Dahi , Sun Hai , Wang Daobing
Published: December 2022

Field tests indicate that temporary well shut-ins may enhance oil recovery from a shale reservoir; however, there is currently no systematic research to specifically guide such detailed operations in the field, especially for the design of the shut-in scheme and multiple rounds of shut-ins. In this study, the applicability of well shut-in operations for shale oil reservoirs is studied, and a numerical model is built using the finite element method. In order to simulate the production in a shale oil reservoir, two separate modules (i.e., Darcy’s law and phase transport) were two-way coupled together. The established model was validated by comparing its results with the analytical Buckley–Leverett equation. In this paper, the geological background and parameters of a shale oil reservoir in Chang-7 Member (Chenghao, China) were used for the analyses. The simulation results show that temporary well shut-in during production can significantly affect well performance. Implementing well shut-in could decrease the initial oil rate while decreasing the oil decline rate, which is conducive to long-term production. After continuous production for 1000 days, the oil rate with 120 days shut-in was 9.85% larger than the case with no shut-in. Besides, an optimal shut-in time has been identified as 60 days under our modeling conditions. In addition, the potential of several rounds of well shut-in operations was also tested in this study; it is recommended that one or two rounds of shut-ins be performed during development. When two rounds of shut-ins are implemented, it is recommended that the second round shut-in be performed after 300 days of production. In summary, this study reveals the feasibility of temporary well shut-in operations in the development of a shale oil reservoir and provides quantitative guidance to optimize these development scenarios.
The Boundary of Porter Hypothesis: The Energy and Economic Impact of China’s Carbon Neutrality Target in 2060
Authors: Huang Shenhai , Du Chao , Jin Xian , Zhang Daini , Wen Shiyan , Wang Yu’an , Cheng Zhenyu , Jia Zhijie
Published: December 2022

The process of carbon neutrality does have economic costs; however, few studies have measured the cost and the economic neutral opportunities. This paper uses a dynamic computable general equilibrium (CGE) model to simulate China’s carbon neutrality path from 2020 to 2060 and analyzes its economic impact. This paper innovatively adjusts the CGE modeling technology and simulates the boundary of the Porter hypothesis on the premise of economic neutrality. The results show that the carbon neutrality target may reduce the annual GDP growth rate by about 0.8% in 2020–2060. To make the carbon pricing method under the carbon neutrality framework meet the strong version of the Porter hypothesis (or economic neutrality), China must increase its annual total factor productivity by 0.56–0.57% in 2020–2060; this is hard to achieve. In addition, the study finds that China’s 2030 carbon target has little impact on the economy, but the achievement of the 2060 carbon neutrality target will have a significant effect. Therefore, the paper believes that the key to carbon neutrality lies in the coexistence of technological innovation and carbon pricing to ensure that we can cope with global warming with the lowest cost and resistance.
A Two-Tier Superstructure Model for Optimization of Microalgae-Based Biorefinery
Authors: Gu Siwen , Wang Jiaan , Zhuang Yu
Published: December 2022

Microalgae have attracted great research interest as a feedstock for producing a wide range of end-products. However, recent studies show that the tight processing integration technology for microalgae-based biorefinery makes production less economical and even has a negative impact on sustainability. In this study, a new two-tier superstructure optimization design methodology is proposed to locate the optimal processing pathway. This model is developed based on the decomposition strategy and the relationship-based investigation, coupling an outer-tier structure with an inner-tier structure, wherein the outlet flows of the middle stages is relaxed and then an appropriate level of redundancy for designing the processing is provided. Two scenarios are developed to compare the most promising biorefinery configurations under two different design option favors. By solving the mixed integer nonlinear programming model with the objective functions of maximizing the yield of the desired products and maximizing the gross operating margin, the optimization results obtained show the ability of this framework to provide the promising configurations and cost-effectiveness of microalgae-based biorefinery. Compared with Scenario 1, the optimized solutions in Scenario 2 feature a gross operating margin increase up to 27.09% and an increase in product yield up to 25.00%. The proposed method improves the original huge computing scale and ensures economics without simplifying the processing pathways.
Passive Solar Systems for the Promotion of Thermal Comfort in African Countries: A Review
Authors: Santos Michael M. , Ferreira Ana Vaz , Lanzinha João C. G.
Published: December 2022

Globally, the residential sector consumes a significant amount of energy. Therefore, bioclimatic architectural systems which consider passive solutions should be studied, analyzed, and implemented to reduce energy consumption. This review aims to promote thermal comfort in African countries by using passive solar systems. It begins with the keyword thermal comfort and then reviews articles published over the last ten years that consider bioclimatic architecture and construction strategies in Africa, the main trends in scientific research in this field, and the possibilities for each climate zone in achieving the highest degree of climate comfort. Following an extensive review, certain bioclimatic architectural strategies adopted in specific countries can be applied in countries with similar climates and this can contribute to significant energy savings through effective functional solar and ventilation design strategies. Several countries have been identified as having the most significant publications on thermal regulations in buildings, and the associated regulations and projects are discussed. Several studies have also examined static and adaptive models of thermal comfort.