bluuebunny/crossref_metadata_2025 huggingface dataset:
Photoautotrophic Euendoliths and Their Complex Ecological Effects in Marine Bioengineered Ecosystems
Authors: Dievart Alexia M. , McQuaid Christopher D. , Zardi Gerardo I. , Nicastro Katy R. , Froneman Pierre W.
Published: September 2022

Photoautotrophic euendolithic microorganisms are ubiquitous where there are calcium carbonate substrates to bore into and sufficient light to sustain photosynthesis. The most diverse and abundant modern euendolithic communities can be found in the marine environment. Euendoliths, as microorganisms infesting inanimate substrates, were first thought to be ecologically irrelevant. Over the past three decades, numerous studies have subsequently shown that euendoliths can colonize living marine calcifying organisms, such as coral skeletons and bivalve shells, causing both sub-lethal and lethal damage. Moreover, under suitable environmental conditions, their presence can have surprising benefits for the host. Thus, infestation by photoautotrophic euendoliths has significant consequences for calcifying organisms that are of particular importance in the case of ecosystems underpinned by calcifying ecosystem engineers. In this review, we address the nature and diversity of marine euendoliths, as revealed recently through genetic techniques, their bioerosive mechanisms, how environmental conditions influence their incidence in marine ecosystems and their potential as bioindicators, how they affect live calcifiers, and the potential future of euendolithic infestation in the context of global climate change and ocean acidification.
Are Source Code Metrics “Good Enough” in Predicting Security Vulnerabilities?
Authors: Ganesh Sundarakrishnan , Palma Francis , Olsson Tobias
Published: September 2022

Modern systems produce and handle a large volume of sensitive enterprise data. Therefore, security vulnerabilities in the software systems must be identified and resolved early to prevent security breaches and failures. Predicting security vulnerabilities is an alternative to identifying them as developers write code. In this study, we studied the ability of several machine learning algorithms to predict security vulnerabilities. We created two datasets containing security vulnerability information from two open-source systems: (1) Apache Tomcat (versions 4.x and five 2.5.x minor versions). We also computed source code metrics for these versions of both systems. We examined four classifiers, including Naive Bayes, Decision Tree, XGBoost Classifier, and Logistic Regression, to show their ability to predict security vulnerabilities. Moreover, an ensemble learner was introduced using a stacking classifier to see whether the prediction performance could be improved. We performed cross-version and cross-project predictions to assess the effectiveness of the best-performing model. Our results showed that the XGBoost classifier performed best compared to other learners, i.e., with an average accuracy of 97% in both datasets. The stacking classifier performed with an average accuracy of 92% in Struts and 71% in Tomcat. Our best-performing model—XGBoost—could predict with an average accuracy of 87% in Tomcat and 99% in Struts in a cross-version setup.
Towards the Mechatronic Development of a New Upper-Limb Exoskeleton (SAMA)
Authors: Abdelbar M. , Mohamed I. , Abdellatif A. , Hegaze Moutaz M.
Published: September 2022

Modern neuromuscular rehabilitation engineering and assistive technology research have been constantly developing in the last 20 years. The upper body exoskeleton is an example of an assistive rehabilitation device. However, in order to solve its technological problems, interdisciplinary research is still necessary. This paper presents a new three-degrees of freedom (DOF) active upper-body exoskeleton for medical rehabilitation named “SAMA”. Its mechanical structure is inspired by the geometry and biomechanics of the human body, particularly the ranges of motion (ROM) and the needed torque. The SAMA exoskeleton was manufactured and assembled into an ergonomic custom-made wheelchair in a sitting posture in order to provide portability and subject comfort during experimental testing and rehabilitation exercises. Dynamic modeling using MATLAB–Simulink was used for calculating the inverse kinematics, dynamic analysis, trajectory generation and implementation of proportional–integral–derivative (PID) computed torque control (PID-CTC). A new framework has been developed for rapid prototyping (the dynamic modeling, control, and experimentation of SAMA) based on the integration between MATLAB–Simulink and the Robot Operating System (ROS) environment. This framework allows the robust position and torque control of the exoskeleton and real-time monitoring of SAMA and its subject. Two joints of the developed exoskeleton were successfully tested experimentally for the desired arm trajectory. The angular position and torque controller responses were recorded and the exoskeleton joints showed a maximum delay of 200° and a maximum steady state error of 0.25°. These successful results encourage further development and testing for different subjects and more control strategies.
A Case Series of Gastric Metastatic Growths
Authors: Gandhi Mustafa , Chela Harleen Kaur , Ertugrul Hamza , Al Juboori Alhareth , Gangu Karthik , Rao Deepthi , Daglilar Ebubekir
Published: September 2022

Gastric cancer is one of the gastrointestinal malignancies that can be quite devastating with high morbidity and mortality. Unfortunately, it is a malignancy that is encountered all across the world and is often brought into suspicion based on symptoms of the patient. The presentation differs based on the symptomatology and can be quite variable in each and every case. Malignant lesions in the stomach discovered endoscopically can represent as primary gastric growths or can be secondary as a consequence of metastatic spread from a distant primary site. It is important to recognize the different patterns of presentation of metastatic disease and to be aware of the primary tumor sites. The treatment and ultimately the prognosis changes drastically when dealing with a metastatic disease as opposed to a primary localized source with limited spread. The aim of our study is to present a mini series of cases that manifest as metastatic gastric growths. Their clinical, endoscopic and histological appearance is depicted to provide an understanding of each case. The primary sites of origin for our patients were the lungs, skin, lymphoid tissue and kidneys. Their overall clinical course is presented including the approach to the management in each case as well as their outcomes.
A Necessary and Sufficient Condition in the Model of Kondepudi and Nelson for the Breaking of Chiral Symmetry
Authors: Colwell Jason Andrew
Published: September 2022

The setting is a system containing achiral reactants which form a chiral compound. In 1983, Kondepudi and Nelson proposed a model for the breaking of chiral symmetry. The present article reduces the conditions for bifurcation to a single condition which is shown to be both necessary and sufficient. A number of other papers on this topic also propose models for the breaking of chiral symmetry. These are shown to be essentially special cases of the model of Kondepudi and Nelson, with the same necessary and sufficient condition. The central question of this line of research is: in a racemic mixture of a chiral compound, could an excess of one enantiomer over the other develop on its own? Our answer is yes, if and only if a certain simple condition is satisfied. This answer should prove useful in further research, both theoretical and experimental, into the origin of life.
A Quantum Chemical Investigation into the Molecular Mechanism of the Atmospheric Reactions of Chemi-Ions with Nitrogen and Nitrogen Oxides
Authors: Sulay Rehin , Krishnan Anandhu , Muralikrishna Balasubramoniam , Devadas Sudheesh , Rajalakshmi Chandralekha , Mathew Jintumol , Thomas Vibin Ipe
Published: September 2022

Nitrogen oxides and chemi-ions are atmospheric pollutants with considerable aeronomic interest. These toxicants can react with each other, producing various ionic species and highly reactive by-products that play a crucial role in aerosol clustering and mediate several important atmospheric reactions. Understanding the chemical reactivity of these pollutants can provide essential information for controlling their excess emission into the atmosphere. Computational modeling and electronic structure studies help in predicting the structure, reactivity, and thermodynamics of transient atmospheric chemical species and can guide experimental research by providing vital mechanistic insights and data. In the present study, a computational investigation into the mechanisms of the binary associative reactions between negative ions: O2− and O3− with NO, NO2, and N2 was conducted using the Coupled-Cluster Singles and Doubles (CCSD) theory. Five model reactions between N2/NOx with On− (n = 2, 3) were considered in this work. Our calculations revealed that reactions (2) and (5) are two sequential processes involving intermediates, and all others occur in a concerted manner by direct transitions from the reactants to the products, with no isolable intermediates proceeding via single non-planar transition states. Our study revealed that the higher activation barrier required for the formation of NO3− (2) as compared to NO2− (1) could be the reason for the excess formation of NO2− ions over NO3− ions in the atmosphere. Further, all the investigated reactions except (5) are found to be feasible at room temperature. The energy required to break N-N bonds in the N2 molecule justifies the high barrier for (5). The results obtained from the study are in close agreement with the available experimental data. Moreover, the data from the study can be utilized for the evaluation of experiments and model predictions pertaining to NOx oxidation and molecular modeling of the gas-phase chemistry of pollutants/nucleation precursors formed in the Earth’s atmosphere and aircraft engines.
Quantum Collision Models: A Beginner Guide
Authors: Cusumano Stefano
Published: September 2022

In recent years, quantum collision models, sometimes dubbed repeated interaction models, have gained much attention due to their simplicity and their capacity to convey ideas without resorting to technical complications typical of many approaches and techniques used in the field of open quantum systems. In this tutorial, we show how to use these models, highlighting their strengths and some technical subtleties often overlooked in the literature. We do this by deriving the Markovian master equation and comparing the standard collisional derivation with the standard microscopic one. We then use the collision model to derive the master equation of a two-level system interacting with either a bosonic or fermionic bath to give the reader a flavour of the real use of the model.
Robust AOA-Based Target Localization for Uniformly Distributed Noise via ℓp-ℓ1 Optimization
Authors: Chen Yanping , Wang Chunmei , Yan Qingli
Published: September 2022

This paper addresses the problem of robust angle of arrival (AOA) target localization in the presence of uniformly distributed noise which is modeled as the mixture of Laplacian distribution and uniform distribution. Motivated by the distribution of noise, we develop a localization model by using the ℓp-norm with 0≤p<2 as the measurement error and the ℓ1-norm as the regularization term. Then, an estimator for introducing the proximal operator into the framework of the alternating direction method of multipliers (POADMM) is derived to solve the convex optimization problem when 1≤p<2. However, when 0≤p<1, the corresponding optimization problem is nonconvex and nonsmoothed. To derive a convergent method for this nonconvex and nonsmooth target localization problem, we propose a smoothed POADMM estimator (SPOADMM) by introducing the smoothing strategy into the optimization model. Eventually, the proposed algorithms are compared with some state-of-the-art robust algorithms via numerical simulations, and their effectiveness in uniformly distributed noise is discussed from the perspective of root-mean-squared error (RMSE). The experimental results verify that the proposed method has more robustness against outliers and is less sensitive to the selected parameters, especially the variance of the measurement noise.
Elastic Entropic Forces in Polymer Deformation
Authors: Kartsovnik Vladimir I. , Volchenkov Dimitri
Published: September 2022

The entropic nature of elasticity of long molecular chains and reticulated materials is discussed concerning the analysis of flows of polymer melts and elastomer deformation in the framework of Frenkel–Eyring molecular kinetic theory. Deformation curves are calculated in line with the simple viscoelasticity models where the activation energy of viscous flow depends on the magnitude of elastic entropic forces of the stretched macromolecules. The interconnections between deformation processes and the structure of elastomer networks, as well as their mutual influence on each other, are considered.
Practical Considerations for the Application of Nonlinear Indices Characterizing the Atrial Substrate in Atrial Fibrillation
Authors: Finotti Emanuela , Quesada Aurelio , Ciaccio Edward J. , Garan Hasan , Hornero Fernando , Alcaraz Raúl , Rieta José J.
Published: September 2022

Atrial fibrillation (AF) is the most common cardiac arrhythmia, and in response to increasing clinical demand, a variety of signals and indices have been utilized for its analysis, which include complex fractionated atrial electrograms (CFAEs). New methodologies have been developed to characterize the atrial substrate, along with straightforward classification models to discriminate between paroxysmal and persistent AF (ParAF vs. PerAF). Yet, most previous works have missed the mark for the assessment of CFAE signal quality, as well as for studying their stability over time and between different recording locations. As a consequence, an atrial substrate assessment may be unreliable or inaccurate. The objectives of this work are, on the one hand, to make use of a reduced set of nonlinear indices that have been applied to CFAEs recorded from ParAF and PerAF patients to assess intra-recording and intra-patient stability and, on the other hand, to generate a simple classification model to discriminate between them. The dominant frequency (DF), AF cycle length, sample entropy (SE), and determinism (DET) of the Recurrence Quantification Analysis are the analyzed indices, along with the coefficient of variation (CV) which is utilized to indicate the corresponding alterations. The analysis of the intra-recording stability revealed that discarding noisy or artifacted CFAE segments provoked a significant variation in the CV(%) in any segment length for the DET and SE, with deeper decreases for longer segments. The intra-patient stability provided large variations in the CV(%) for the DET and even larger for the SE at any segment length. To discern ParAF versus PerAF, correlation matrix filters and Random Forests were employed, respectively, to remove redundant information and to rank the variables by relevance, while coarse tree models were built, optimally combining high-ranked indices, and tested with leave-one-out cross-validation. The best classification performance combined the SE and DF, with an accuracy (Acc) of 88.3%, to discriminate ParAF versus PerAF, while the highest single Acc was provided by the DET, reaching 82.2%. This work has demonstrated that due to the high variability of CFAEs data averaging from one recording place or among different recording places, as is traditionally made, it may lead to an unfair oversimplification of the CFAE-based atrial substrate characterization. Furthermore, a careful selection of reduced sets of features input to simple classification models is helpful to accurately discern the CFAEs of ParAF versus PerAF.
Statistical Mechanics of Political Polarization
Authors: Kaufman Miron , Kaufman Sanda , Diep Hung T.
Published: September 2022

Rapidly increasing political polarization threatens democracies around the world. Scholars from several disciplines are assessing and modeling polarization antecedents, processes, and consequences. Social systems are complex and networked. Their constant shifting hinders attempts to trace causes of observed trends, predict their consequences, or mitigate them. We propose an equivalent-neighbor model of polarization dynamics. Using statistical physics techniques, we generate anticipatory scenarios and examine whether leadership and/or external events alleviate or exacerbate polarization. We consider three highly polarized USA groups: Democrats, Republicans, and Independents. We assume that in each group, each individual has a political stance s ranging between left and right. We quantify the noise in this system as a “social temperature” T. Using energy E, we describe individuals’ interactions in time within their own group and with individuals of the other groups. It depends on the stance s as well as on three intra-group and six inter-group coupling parameters. We compute the probability distributions of stances at any time using the Boltzmann probability weight exp(−E/T). We generate average group-stance scenarios in time and explore whether concerted interventions or unexpected shocks can alter them. The results inform on the perils of continuing the current polarization trends, as well as on possibilities of changing course.
A Growing Light in the Lagging Region in Indonesia: The Impact of Village Fund on Rural Economic Growth
Authors: Hartojo Nurlatifah , Ikhsan Mohamad , Dartanto Teguh , Sumarto Sudarno
Published: September 2022

Narrowing the development gap has long been and continues to be a key element of government aspiration worldwide. Since 2015, the Government of Indonesia has implemented the village fund (VF) transfer to enhance its rural economy, especially in remote areas. The impact of the VF on village development may vary greatly depending on the village’s location. This study examines the causal effects of VF transfer on the rural economic growth of underdeveloped villages in Indonesia. Using a nighttime light dataset at the village level as a proxy for rural economic growth and a regression discontinuity design in time, we found a significant improvement in rural economic growth in underdeveloped villages after the implementation of VF transfer. Our study confirms that the underdeveloped villages in East Indonesia are growing faster than those in West and Central Indonesia. The average growth of nightlight after the implementation of VF is approximately 156% in East Indonesia, 141% in Central Indonesia, and 98% in West Indonesia compared to the growth of pre-VF. Therefore, there is a strong argument to review the current formula of the VF to narrow the rural development gap in Indonesia.
A Miniaturized Triple-Band Antenna Based on Square Split Ring for IoT Applications
Authors: Abdulzahra Duaa H. , Alnahwi Falih , Abdullah Abdulkareem S. , Al-Yasir Yasir I. A. , Abd-Alhameed Raed A.
Published: September 2022

This article presents a miniaturized triple-band antenna for Internet of Things (IoT) applications. The miniaturization is achieved by using a split square ring resonator and half ring resonator. The antenna is fabricated on an FR4 substrate with dimensions of (33 × 22 × 1.6) mm3. The proposed antenna resonates at the frequencies 2.4 GHz, 3.7 GHz, and 5.8 GHz for WLAN and WiMax applications. The obtained −10 dB bandwidth for the three bands of the proposed antenna are 300 MHz, 360 MHz, and 900 MHz, respectively. The measured reflection coefficient values of the proposed antenna corresponding to each resonant frequency are equal to −14.772 dB, −20.971 dB, and −28.1755 dB, respectively. The measured gain values are 1.43 dBi, 0.89 dBi, and 1 dBi, respectively, at each resonant frequency. There is a good agreement between the measured and simulated results, and both show an omnidirectional radiation pattern at each of the antenna resonant frequencies that is suitable for IoT portable devices.
Disorder Effects in One-Dimensionally Periodic Extraordinary Transmission Structures
Authors: Camacho Miguel , Fernández-Prieto Armando , Boix Rafael R. , Medina Francisco
Published: September 2022

Extraordinary transmission structures show promising capabilities for highly selective filters in both frequency and angle of incidence. However, their realistic response once manufacturing limitations are taken into account remains unexplored. In this manuscript, we explore a novel degree of freedom: disorder. We expand on previously developed highly efficient method of moment (MoM) implementations to study the effects on the transmission properties of large but finite chains of slots due to different families of disorder: lateral and vertical displacements as well as scatterer manipulation (modifying sizes and rotation angles), showing their effects on the transmission spectrum.
Forces and Stresses in the Windings of a Superconducting Fault Current Limiter
Authors: Kozak Janusz
Published: September 2022

This paper presents the design of a Superconducting Fault Current Limiter (SFCL) and calculation results of forces and stresses in the windings of a resistive fault current limiter. The design of the fault current limiter consists of two parallelly connected and magnetically coupled windings, cooled by a single stage cryocooler. Magnetically compensated windings made of HTS tape give a very low voltage on the limiter at a nominal current. Limitation of the short-circuit time and the value of the maximum initial fault current reduces the thermal and dynamic effects of the passage of a fault current. Using devices which limit the value of a fault current can lower the level of required short-circuit capacity of the elements in a system. However, selected means of fault currents limitation must maintain the power quality standards. A perfect fault current limiter is required to have substantial impedance in fault conditions and zero impedance at work currents. Such requirements are met by a SFCL. An increase of current caused by the occurrence of a fault current results in the transition of the superconducting material from the superconducting state into the resistive state. This increases the impedance of short-circuit loop, allowing the fault current value to decrease. During a short-circuit, the forces generated from the short-circuit current also act on the limiter windings. Short-circuit current causes stresses in the superconducting tape. Exceeding the permissible stress value results in an irreversible reduction in the critical current of the superconducting tape. Calculations of the forces and stresses in the HTS tape for the maximum value of the short-circuit current were carried out using the finite element method. The constructed limiter was tested and the winding design ensures that the tape stresses are at a safe level even for short-circuit currents.
Integration of Renewable Energy Sources into Low-Temperature District Heating Systems: A Review
Authors: Sarbu Ioan , Mirza Matei , Muntean Daniel
Published: September 2022

This article presents a complex and exhaustive review of the integration of renewable energy sources (RES) (specifically solar, geothermal, and hydraulic energies and heat pumps (HPs)) and the improvement of water pumping in district heating systems (DHSs) focused on low-temperature systems, to increase energy efficiency and environmental protection. For this aim, the main components of a DHS and the primary RES with applications in DHSs were described briefly. Finally, several case studies regarding the DHS in Timisoara, Romania, were analysed. Thus, by integrating water source HP (WSHP) systems in cooperation with solar thermal and photovoltaic (PV) collectors and reducing the supply temperature from 110 °C to 30 °C in DHS, which supplies the water radiators to consumers in a district of this city in a 58/40 °C regime of temperatures and produces domestic hot water (DHW) required by consumers at 52 °C, a thermal energy saving of 75%, a reduction in heat losses on the transmission network of 90% and a diminution of CO2 emissions of 77% were obtained. Installed PV panels generate 1160 MWh/year of electricity that is utilised to balance the electricity consumption of HP systems. Additionally, mounting pumps as turbines (PATs) for the recovery of excess hydraulic energy in the entire heating network resulted in electricity production of 378 MW, and the variable frequency drive’s (VFD) method for speed control for a heating station pump resulted in roughly 38% more energy savings than the throttle control valve technique.
Systematic Design of Energy-Saving Action Plans for Taiwan Campus by Considering Economic Benefits and Actual Demands
Authors: Wai Rong-Jong
Published: September 2022

In response to the future net zero emissions plan in Taiwan, the campus shoulders the university’s social responsibility and educational significance. Recently, energy conservation and carbon reduction have become common goals for every campus. However, there is a common problem to be addressed in terms of how to take into account the economic benefits and the continuous improvement strategy regarding actual demands. In this study, a systematic design of energy-saving action plans for a Taiwan campus by considering economic benefits and actual demands is demonstrated. By taking National Taiwan University of Science and Technology in Taiwan as an example, eight energy-saving action plans during the period from 2016 to 2020 are introduced, and the effectiveness of these topologies is verified by real implementations. Action plans contain the installation of a smart energy management system, elevator power recovery devices, circulating fans, and lighting delay switches; the replacement of old air-conditioners, fluorescent lamps, and high-sodium streetlights; and load consolidation and low-efficiency transformers replacement. Upon evaluation, the estimated electricity savings can achieve up to 16% of annual electricity consumption, and the payback period is about 5.22 years. Upon application, the actual power saving amounts to about 3,076,260 kWh for approximately 15.5% of the power consumption of Taiwan Tech in 2020.
Mapping of Alternative Oilseeds from the Brazilian Caatinga and Assessment of Catalytic Pathways toward Biofuels Production
Authors: Aquino Aline Scaramuzza , Silva Milena Fernandes da , Almeida Thiago Silva de , Bilheri Filipe Neimaier , Converti Attilio , Melo James Correia de
Published: September 2022

Biofuels are increasingly important renewable resources in the world’s energy matrix that have challenged the scientific community as well as small and large farmers to develop alternatives to fossil fuels in order to achieve the aims of energy transition. In particular, Brazil’s proven competitiveness in agribusiness together with its rich biodiversity put the country in a key position in the biofuels market. The semiarid Caatinga of northeastern Brazil, an exclusive biome rich in many oilseed species suitable for potential energy purposes, is of particular interest in this field. Nowadays, soybeans are the main feedstock used for the production of biodiesel, but, due to the increasing demand for biofuels, the search for alternative sources of oil from tropical flora with high productivity is crucial. Under this premise, this systematic review focuses on mapping Caatinga’s vegetable oil crops that could be used as alternative raw materials for biofuels’ production in Brazil, in addition to traditional soybeans and sugarcane. To gain more detailed insight into these matrices, their main properties, including oil content, fatty acid profile and physicochemical properties, are discussed. Moreover, an overview is provided of processes to synthesize different types of biofuels, particularly biodiesel and aviation biokerosene, including the routes employing homogeneous, enzymatic and mainly heterogeneous catalysts. Finally, future prospects and challenges for renewable biofuels and the Caatinga biome are addressed.
Study on the Coal Pillar Weakening Technology in Close Distance Multi-Coal Seam Goaf
Authors: Zhang Jie , Zhuo Qingsong , Yang Sen , Yang Tao , Wang Bin , Bai Wenyong , Wu Jianjun , Xie Shaoliang
Published: September 2022

The pressure relief of coal pillars in close-distance multi-coal seam goaf is a complex engineering problem with the characteristics of “dynamic mine pressure”. Hence, this paper studies such problems. First, the influence factors of the coal pillar in the goaf on the mine pressure of the mining face of the lower coal seam under this condition were theoretically analyzed, and it was concluded that vertical stress is the most important element, followed by horizontal stress. Next, a physical similarity simulation experiment was designed to study the stress distribution law of the coal pillar floor in the goaf before and after pressure release and the damage depth. Finally, a technology and monitoring method for coal pillar blasting pressure alleviation in goaf were introduced and implemented in engineering practice. After the pressure is alleviated, the surrounding rock stress of the lower coal seam mining face is redistributed, and the vertical stress is decreased by 20%. The adjacent rock’s deformation is improved. This technology’s cost and safety advantages are extraordinary and helpful for mining coal seams over close distances.
Model Based Optimal Control of the Photosynthetic Growth of Microalgae in a Batch Photobioreactor
Authors: Ifrim George Adrian , Titica Mariana , Horincar Georgiana , Antache Alina , Baicu Laurențiu , Barbu Marian , Guzmán José Luis
Published: September 2022

The present paper investigates the optimal control of the photosynthetic growth process in an artificial light photobioreactor operated in batch mode, the objective being to find an optimal incident light intensity for which the consumption of light energy, for any amount of newly formed biomass, is minimal. By using a simple and reliable model for the photosynthetic growth of microalgae of microalgae, predictions can be made on the quantity of produced biomass and on the amount of light consumed, whose ratio gives the biomass yield on light energy. This variable is unimodal on the allowed range of incident light intensities and has been used as objective function. An improved objective function is proposed by using the specific growth rate and a weighing factor that allows obtaining the desired amount of biomass while the light energy consumption is optimal. A closed-loop control structure has been designed based on the developed optimization algorithm. The optimal controller has been validated in simulation, comparing different lengths of the optimization horizon and the sampling period. It was found that a bigger sampling period, for the cases where there is no online information on the biomass concentration, does not significantly affect the productivity. The optimization algorithm can be used either online or offline, being useful for various experimental setups.
Design of a More Efficient Rotating-EM Energy Floor with Lead-Screw and Clutch Mechanism
Authors: Jintanawan Thitima , Phanomchoeng Gridsada , Suwankawin Surapong , Thamwiphat Weeraphat , Khunkiat Varinthorn , Watanasiri Wasu
Published: September 2022

There is an interest in harvesting energy from people’s footsteps in crowded areas to power smart electronic devices with low consumption. The average power consumption of these devices is approximately 10 μW. The energy from our footsteps is green and free, because walking is a routine activity in everyday life. The energy floor is one of the most efficient pieces of equipment in vibration-based energy harvesting. The paper aims to improve the previous design of the energy floor—called Genpath—which uses a rotational electromagnetic (EM) technique to generate electricity from human footsteps. The design consists of two main parts of (1) the EM generator, including the lead-screw mechanism for translation-to-rotation conversion, and (2) the Power Management and Storage (PMS) circuit. The improvement was focused on the part of the EM generator. A thorough investigation of the design components reveals that the EM generator shaft in the previous Genpath design cannot continuously rotate when the floor-tile reaches the bottom end, resulting in no energy gain. Therefore, a one-way clutch is implemented to the system to disengage the generator shaft from the lead-screw motion when the floor-tile reaches the allowable displacement. During the disengagement, the EM generator shaft still proceeds with a free rotation and could generate more power. In our analysis, the dynamic model of the electro-mechanical systems with the one-way clutch was successfully developed and used to predict the energy performances of the VEH floors and fine-tune the design parameters. The analytical result is shown that the spring stiffness mainly affects the force transmitted to the EM generator, and then the induced voltage and power of the generator, thus, the value of the stiffness is one of the critical design parameters to optimize. Finally, the new prototype consisting of 12-V-DC generator, mechanisms of lead-screw and clutch, as well as coil springs with the optimal stiffness of 1700 N/m was built and tested. The average energy produced by the new prototype is 3637 mJ (or average power of 3219 mW), per footstep which is 2935 mJ greater than that of the previous design. Moreover, to raise the social awareness about energy usage, the sets of Genpath have been used to organize an exhibition, “Genpath Empower our Journey”. The people who stroll forward on the paths can realize how much energy they gain from their footsteps.
Upgrading Conventional Power System for Accommodating Electric Vehicle through Demand Side Management and V2G Concepts
Authors: Alotaibi Majed A. , Eltamaly Ali M.
Published: September 2022

The continually increasing fossil fuel prices, the dwindling of these fuels, and the bad environmental effects which mainly contribute to global warming phenomena are the main motives to replace conventional transportation means to electric. Charging electric vehicles (EVs) from renewable energy systems (RES) substantially avoids the side effects of using fossil fuels. The higher the increase in the number of EVs the greater the challenge to the reliability of the conventional power system. Increasing charging connections for EVs to the power system may cause serious problems to the power system, such as voltage fluctuations, contingencies in transmission lines, and loss increases. This paper introduces a novel strategy to not only replace the drawbacks of the EV charging stations on the power system’s stability and reliability, but also to enhance the power system’s performance. This improvement can be achieved using a smart demand side management (DSM) strategy and vehicle to grid (V2G) concepts. The use of DSM increases the correlation between the loads and the available generation from the RES. Besides this, the use of DSM, and the use of V2G concepts, also helps in adding a backup for the power system by consuming surplus power during the high generation period and supplying stored energy to the power system during shortage in generation. The IEEE 30 bus system was used as an example of an existing power system where each load busbar was connected to a smart EV charging station (SEVCS). The performance of the system with and without the novel DSM and V2G concepts was compared to validate the superiority of the concepts in improving the performance of the power system. The use of modified particle swarm optimization in optimal sizing and optimal load flow reduced the cost of energy and the losses of the power system. The use of the smart DSM and V2G concepts substantially improved the voltage profile, the transmission line losses, the fuel cost of conventional power systems, and the stability of the power system.
Conceptualization and Mapping of Predictors of Technological Entrepreneurship Growth in a Changing Economic Environment (COVID-19) from the Polish Energy Sector
Authors: Czemiel-Grzybowska Wioletta
Published: September 2022

This study seeks to address the issue of the development factors influencing technological entrepreneurship capabilities of enterprises during the COVID-19 epidemic crisis. This research is particularly relevant in light of the leading role given to innovation and science-oriented technology companies in the economic and epidemiological crisis. This study aims to analyze the impact of the changing environment on the predictors of technological entrepreneurship, assess their impact by the management practice and establish a causal relationship between the used variables. The paper draws on foreign literature review, covering fundamental theoretical fields in international management literature, to develop an integrated research framework. Based on a differentiated approach, the collaborative framework emphasizes a range of network processes and attributes, their interactions and moderating managerial relationships related to their impact on companies’ technological entrepreneurship capabilities and their contribution to business outcomes. The study was conducted by means of four-wave research. The factors of models included in the correlation analysis are management functions and demand for new technology. Results show that there is a weak positive relationship between management functions and manager’s technological preferences. These findings show that during COVID-19, firms changed their management practices using digitalization to respond to the pandemic. Additionally, it shows that managers moved towards employing new technologies as a strategic response to the crisis. The results showed a mutual, two-way relationship between the demand for new technology and managers from the planning area, high level scientifically and managers with managerial functions, a quick diffusion of technological innovations and managers with the motivating function, a short lifecycle of products and processes and managers from the short lifecycle of products and processes. Taking into consideration that technology entrepreneurship and innovation are facets of the innovative entrepreneur sector, the need for a holistic approach is needed to support their development during the international economic crisis. The next practical implication derived from the crisis may hinder the ability of entrepreneurs to discover new opportunities for technology development. Moreover, an epidemic shock such as COVID-19 may have an impact on technology entrepreneurial opportunities. This article presents a new look at the theory of management by using the implementation role of predictors of the growth of technological entrepreneurship during the epidemic crisis. In addition, the article obviously contributes to the technology entrepreneurship literature by providing an empirical study that advances a new perspective on the process of developing new technologies in the period of crisis.
Design and Optimization on the Degree of Hybridization of Underground Hybrid Electric Trackless Rubber-Tyred Vehicle
Authors: Yuan Xiaoming , Lu Yao , Bao Jiusheng , Han Peixin , Yin Yan , Wang Xu
Published: September 2022

The explosion-proof diesel engine trackless rubber-tyred vehicle (TRTV) has the disadvantages of high fuel consumption and serious exhaust emissions, while the problems of insufficient power and short endurance limit the development of the explosion-proof battery trackless rubber-tyred vehicle. Hybrid technology can effectively reduce fuel consumption and emissions on the basis of ensuring sufficient power. Exploring the application of hybrid electric trackless rubber-tyred vehicle (HETRTV) has practical significance for coal mine auxiliary transportation. The degree of hybridization (DOH) will directly affect the performance and cost of TRTV, which needs to be focused in the development process. The effects of DOH on dynamic performance, fuel economy, emission performance, and cost were studied based on a simulation by ADVISOR, and the results were verified and analyzed by experiment. Compared with the flameproof diesel engine trackless vehicles, HETRTV with the optimal DOH exhausts has far less gas emissions. The engine fuel consumption and the equivalent fuel consumption of the vehicle are reduced by 33.9% and 12.5%, respectively. The results showed that in spite of a small increase in cost, the HETRTV with the optimal DOH can not only meet the driving requirements of underground working conditions but also greatly improve fuel economy and emission performance.
State-of-the-Art Using Bibliometric Analysis of Wind-Speed and -Power Forecasting Methods Applied in Power Systems
Authors: Lagos Ana , Caicedo Joaquín E. , Coria Gustavo , Quete Andrés Romero , Martínez Maximiliano , Suvire Gastón , Riquelme Jesús
Published: September 2022

The integration of wind energy into power systems has intensified as a result of the urgency for global energy transition. This requires more accurate forecasting techniques that can capture the variability of the wind resource to achieve better operative performance of power systems. This paper presents an exhaustive review of the state-of-the-art of wind-speed and -power forecasting models for wind turbines located in different segments of power systems, i.e., in large wind farms, distributed generation, microgrids, and micro-wind turbines installed in residences and buildings. This review covers forecasting models based on statistical and physical, artificial intelligence, and hybrid methods, with deterministic or probabilistic approaches. The literature review is carried out through a bibliometric analysis using VOSviewer and Pajek software. A discussion of the results is carried out, taking as the main approach the forecast time horizon of the models to identify their applications. The trends indicate a predominance of hybrid forecast models for the analysis of power systems, especially for those with high penetration of wind power. Finally, it is determined that most of the papers analyzed belong to the very short-term horizon, which indicates that the interest of researchers is in this time horizon.
Solar–Wind System for the Remote Objects of Railway Transport Infrastructure
Authors: Shavolkin Olexandr , Gerlici Juraj , Shvedchykova Iryna , Kravchenko Kateryna
Published: September 2022

The article deals with adding the power of a local object to a solar–wind system when consuming electricity from the grid within the power limit. The parameter’s calculation technique for the different values of degree of power increase was considered. The load schedule, the electricity consumption, use of installed power, boundary conditions of generation, and ensuring energy balance were taken into account. Furthermore, data from the renewable source’s generation archive for the location of the object were used. The control of the power consumed by the object was carried out on the taken values of added and total load power with binding to photovoltaic generation. The added power reference on some time intervals was carried out according to the actual renewable generation power value. This increases the degree of use of the battery capacity and energy from renewable sources. The reference of the added power with the state of battery charge formation was carried out according to the forecast. One cycle of deep battery discharge at the evening peak was used to extend the battery life. For the accepted conditions with the average monthly values of renewable energy sources generation with an increase in power by 1.6 times, there was a decrease in electricity consumption by 1.57–4 times.
The Potential of Ukrainian Agriculture’s Biomass to Generate Renewable Energy in the Context of Climate and Political Challenges—The Case of the Kyiv Region
Authors: Wąs Adam , Sulewski Piotr , Gerasymchuk Nataliia , Stepasyuk Ludmila , Krupin Vitaliy , Titenko Zoia , Pogodzińska Kinga
Published: September 2022

Increasing the share of renewable energy in the final energy consumption is a way to ensure independence from external supplies of fossil fuels, which is a fundamental political and economic challenge for many countries nowadays. One such country is Ukraine, which depended on Russian gas supplies and energy (electricity) from nuclear power plants. Russian gas is not delivered anymore to Ukraine, and Russians have recently taken over some of the nuclear power plants. The changes in the political situation force Ukraine to search for alternative energy sources. In countries with high agricultural production potential, one of the basic options seems to be popularization of modern methods of obtaining energy from biomass (bioenergy), which so far has played a minor role in the country’s energy mix (less than 2% in the case of Ukraine). The analysis carried out on the case of the Kyiv Region indicates that the annual economic potential of biomass in the region is equivalent to 1743 thousand toe (tonnes of oil), and its use allows them to save about 43% of fossil fuel annually.
Safe and Effective Smart Urban Transportation—Energy Flow in Electric (EV) and Hybrid Electric Vehicles (HEV)
Authors: Karoń Grzegorz
Published: September 2022

Electric vehicles (EVs) and hybrid electric vehicles (HEVs) are the most appropriate alternatives for conventional vehicles (internal combustion engine (ICE)-based) for smart urban transport—as an element of sustainable modes of transportation [...]
Mine Intelligent Receiver: MIMO-OFDM Intelligent Receiver for Mine Information Recovery
Authors: Wang Anyi , Feng Zhiyuan , Li Xuhong , Pan Yong
Published: September 2022

With the advancement of an intellectual and numerical society, the coal mining industry has also begun to change to intelligence. As an important aspect of intelligent coal mine construction, coal mine communication has put forward more stringent standards for communication quality. For the complex communication environment in mines, the transmission of communication signals is always damaged by various noises and interferences, resulting in serious distortion of the communication signals received at the receiving end. Therefore, the use of traditional receivers for information recovery has the problem of high bit error rate (BER), which cannot meet the standard of intelligent coal mine construction. Based on this, the aim of this research is to combine convolutional neural networks (CNN) and multi-input multi-output orthogonal frequency division multiplexing (MIMO-OFDM) communication systems to design an intelligent receiver model for complex mine communication systems. At the receiver side, CNNs are used to take the place of all the information processing processes. First, features are extracted from the received IQ signal by the convolutional neural network, and then the original information bit is recovered using a multi-label classifier to finally realize end-to-end information restoration. The experimental results show that the intelligent receiver model designed in this research has more accurate information recovery capability in the complex mine channel environment compared with the traditional receiver. In addition, they also verify that the intelligent receiver can still recover information effectively when the traditional receiver cannot recover information properly in the case of partial loss of received data.
Characterizing the Microscopic Anisotropic Permeabilities of Tight Oil Reservoirs Impacted by Heterogeneous Minerals
Authors: Wang Ziqiang , Ge Hongkui , Wei Yun , Wang Yi , Jia Kerui , Xu Ning , Zhang Yuankai , Du Shuheng
Published: September 2022

This study aimed to reveal the anisotropic permeabilities of tight oil reservoirs impacted by heterogeneous minerals. SEM imaging, image processing, fractal calculation, microscopic reservoir modeling, and visual flow simulation were carried out to investigate the above problems. Results show that the variation coefficient of two-dimensional permeability for the studied tight reservoir samples ranges from 0.09 to 0.95, with an average value of 0.68. The penetration coefficient ranges from 1.16 to 2.64, with an average value of 2.13. The ratio of maximum to minimum permeability is between 1.25 and 7.67, with an average value of 5.62. The fluid flow in tight reservoirs has significant anisotropy comprising dominant flow through conductive channels. Flow in tight oil reservoirs tends to involve minor hydraulic fracturing with no proppant.