bluuebunny/crossref_metadata_2025 huggingface dataset:
Dual-Band, Dual-Output Power Amplifier Using Simplified Three-Port, Frequency-Dividing Matching Network
Authors: Chen Xiaopan , Wu Yongle , Wang Weimin
Published: January 2022

This study presents a dual-band power amplifier (PA) with two output ports using a simplified three-port, frequency-dividing matching network. The dual-band, dual-output PA could amplify a dual-band signal with one transistor, and the diplexer-like output matching network (OMN) divided the two bands into different output ports. A structure consisting of a λ/4 open stub and a λ/4 transmission line was applied to restrain undesired signals, which made each branch equivalent to an open circuit at another frequency. A three-stub design reduced the complexity of the OMN. Second-order harmonic impedances were tuned for better efficiency. The PA was designed with a 10-W gallium nitride high electron mobility transistor (GaN HEMT). It achieved a drain efficiency (DE) of 55.84% and 53.77%, with the corresponding output power of 40.22 and 40.77 dBm at 3.5 and 5.0 GHz, respectively. The 40%-DE bandwidths were over 200 MHz in the two bands.
A New Memristive Neuron Map Model and Its Network’s Dynamics under Electrochemical Coupling
Authors: Ramakrishnan Balamurali , Mehrabbeik Mahtab , Parastesh Fatemeh , Rajagopal Karthikeyan , Jafari Sajad
Published: January 2022

A memristor is a vital circuit element that can mimic biological synapses. This paper proposes the memristive version of a recently proposed map neuron model based on the phase space. The dynamic of the memristive map model is investigated by using bifurcation and Lyapunov exponents’ diagrams. The results prove that the memristive map can present different behaviors such as spiking, periodic bursting, and chaotic bursting. Then, a ring network is constructed by hybrid electrical and chemical synapses, and the memristive neuron models are used to describe the nodes. The collective behavior of the network is studied. It is observed that chemical coupling plays a crucial role in synchronization. Different kinds of synchronization, such as imperfect synchronization, complete synchronization, solitary state, two-cluster synchronization, chimera, and nonstationary chimera, are identified by varying the coupling strengths.
Towards Human Stress and Activity Recognition: A Review and a First Approach Based on Low-Cost Wearables
Authors: Castro-García Juan Antonio , Molina-Cantero Alberto Jesús , Gómez-González Isabel María , Lafuente-Arroyo Sergio , Merino-Monge Manuel
Published: January 2022

Detecting stress when performing physical activities is an interesting field that has received relatively little research interest to date. In this paper, we took a first step towards redressing this, through a comprehensive review and the design of a low-cost body area network (BAN) made of a set of wearables that allow physiological signals and human movements to be captured simultaneously. We used four different wearables: OpenBCI and three other open-hardware custom-made designs that communicate via bluetooth low energy (BLE) to an external computer—following the edge-computingconcept—hosting applications for data synchronization and storage. We obtained a large number of physiological signals (electroencephalography (EEG), electrocardiography (ECG), breathing rate (BR), electrodermal activity (EDA), and skin temperature (ST)) with which we analyzed internal states in general, but with a focus on stress. The findings show the reliability and feasibility of the proposed body area network (BAN) according to battery lifetime (greater than 15 h), packet loss rate (0% for our custom-made designs), and signal quality (signal-noise ratio (SNR) of 9.8 dB for the ECG circuit, and 61.6 dB for the EDA). Moreover, we conducted a preliminary experiment to gauge the main ECG features for stress detection during rest.
POSIT vs. Floating Point in Implementing IIR Notch Filter by Enhancing Radix-4 Modified Booth Multiplier
Authors: Esmaeel Anwar A. , Abed Sa’ed , Mohd Bassam J. , Fairouz Abbas A.
Published: January 2022

The increased demand for better accuracy and precision and wider data size has strained current the floating point system and motivated the development of the POSIT system. The POSIT system supports flexible formats and tapered precision and provides equivalent accuracy with fewer bits. This paper examines the POSIT and floating point systems, comparing the performance of 32-bit POSIT and 32-bit floating point systems using IIR notch filter implementation. Given that the bulk of the calculations in the filter are multiplication operations, an Enhanced Radix-4 Modified Booth Multiplier (ERMBM) is implemented to increase the calculation speed and efficiency. ERMBM enhances area, speed, power, and energy compared to the POSIT regular multiplier by 26.80%, 51.97%, 0.54%, and 52.22%, respectively, without affecting the accuracy. Moreover, the Taylor series technique is adopted to implement the division operation along with cosine arithmetic unit for POSIT numbers. After comparing POSIT with floating point, the accuracy of POSIT is 92.31%, which is better than floating point’s accuracy of 23.08%. Moreover, POSIT reduces area by 21.77% while increasing the delay. However, when the ERMBM is utilized instead of the POSIT regular multiplier in implementing the filter, POSIT outperforms floating point in all the performance metrics including area, speed, power, and energy by 35.68%, 20.66%, 31.49%, and 45.64%, respectively.
An Efficient Adaptive and Steep-Convergent Sidelobes Simultaneous Reduction Algorithm for Massive Linear Arrays
Authors: Albagory Yasser , Alraddady Fahad
Published: January 2022

Antenna arrays have become an essential part of most wireless communications systems. In this paper, the unwanted sidelobes in the symmetric linear array power pattern are reduced efficiently by utilizing a faster simultaneous sidelobes processing algorithm, which generates nulling sub-beams that are adapted to control and maintain steep convergence toward lower sidelobe levels. The proposed algorithm is performed using adaptive damping and heuristic factors which result in learning curve perturbations during the first few loops of the reduction process and is followed by a very steep convergence profile towards deep sidelobe levels. The numerical results show that, using the proposed adaptive sidelobes simultaneous reduction algorithm, a maximum sidelobe level of −50 dB can be achieved after only 10 iteration loops (especially for very large antenna arrays formed by 256 elements, wherein the processing time is reduced to approximately 25% of that required by the conventional fixed damping factor case). On the other hand, the generated array weights can be applied to practical linear antenna arrays under mutual coupling effects, which have shown very similar results to the radiation pattern of the isotropic antenna elements with very deep sidelobe levels and the same beamwidth.
A Comparative Analysis of Peak Load Shaving Strategies for Isolated Microgrid Using Actual Data
Authors: Rana Md Masud , Rahman Akhlaqur , Uddin Moslem , Sarkar Md Rasel , Shezan Sk. A. , Ishraque Md. Fatin , Rafin S M Sajjad Hossain , Atef Mohamed
Published: January 2022

Peak load reduction is one of the most essential obligations and cost-effective tasks for electrical energy consumers. An isolated microgrid (IMG) system is an independent limited capacity power system where the peak shaving application can perform a vital role in the economic operation. This paper presents a comparative analysis of a categorical variable decision tree algorithm (CVDTA) with the most common peak shaving technique, namely, the general capacity addition technique, to evaluate the peak shaving performance for an IMG system. The CVDTA algorithm deals with the hybrid photovoltaic (PV)—battery energy storage system (BESS) to provide the peak shaving service where the capacity addition technique uses a peaking generator to minimize the peak demand. An actual IMG system model is developed in MATLAB/Simulink software to analyze the peak shaving performance. The model consists of four major components such as, PV, BESS, variable load, and gas turbine generator (GTG) dispatch models for the proposed algorithm, where the BESS and PV models are not applicable for the capacity addition technique. Actual variable load data and PV generation data are considered to conduct the simulation case studies which are collected from a real IMG system. The simulation result exhibits the effectiveness of the CVDTA algorithm which can minimize the peak demand better than the capacity addition technique. By ensuring the peak shaving operation and handling the economic generation dispatch, the CVDTA algorithm can ensure more energy savings, fewer system losses, less operation and maintenance (O&M) cost, etc., where the general capacity addition technique is limited.
Selected Parameters of Oat Straw as an Alternative Energy Raw Material
Authors: Proszak-Miąsik Danuta , Jarecki Wacław , Nowak Krzysztof
Published: January 2022

Straw is treated as agricultural waste, and it is available in almost every region of Poland. A total of 30 million tons of straw is produced per year, of which there is a surplus of approximately 13.5 million tons of undeveloped straw. For energy purposes, straw from cereals or rapeseed is most often used. When analyzing scientific publications, it was noticed that, in Poland, large amounts of oat straw are produced, and there is no alternative use for it. Hence, we conducted research to determine the energy value of oat straw. Raw material was obtained from an individual farm from 2018 to 2020. Selected energy parameters for straw burned alone (100%) or co-fired with coal were analyzed in the following weight proportions: 70/30, 80/20, and 90/10 coal/oat straw. It was shown that changing weather conditions, in particular years, had a modifying effect on some of the energy parameters of straw. The calorific value of straw was lower than that of coal, but its impact on environmental pollution turned out to be significantly lower. The difference in combustion heat between coal and straw was 11.74 MJ·kg−1. Investigations into pollutant concentrations were performed for cubes of compressed straw and hard coal. Mixtures of these fuels were not studied in this part of the work. The combustion of straw resulted in a reduction of harmful NO, NOX, and SO2 pollutants and an increase in CO compared to coal combustion. As for hydrogen content—it was the highest in carbon and the lowest in straw. In the case of analytical moisture, an inverse relationship was observed. In the case of both coal and straw, the ash content varied throughout the years of research. As the boiler power increased from 5 to 25 kW, the consumption of burned raw material increased significantly. The results indicate that the surplus of oat straw can be rationally used to obtain thermal energy, including co-combustion with coal. This will allow one to avoid burning straw in the fields, which causes great harm to the natural environment.
The Impact of Renewable Energy Sources on the Economic Growth of Poland and Sweden Considering COVID-19 Times
Authors: Ślusarczyk Bogusław , Żegleń Patrycja , Kluczek Aldona , Nizioł Anna , Górka Małgorzata
Published: January 2022

A demonstration of the relationship between the share of renewables in gross marginal energy and selected countries’ economic growth is the basis of this research. The paper seeks to investigate mutual correlations between renewable energy sources and economic growth for two EU economies and how it influences their fluctuations (increase and decrease). The comparative analysis of results was carried out for less-income Polish and high-income Swedish economies. This research used a regression model to answer the research questions examining the presence of correlations between renewable energy sources in gross marginal energy consumption and economic growth. This study analyzes data starting from 1991 to 2022. The results indicated a positive correlation (statistical significance) between Gross Domestic Product and Gross National Income variables for Sweden (84.6% and 83.7%, respectively) and Poland (79.9% and 79.2%, respectively), which influence the use of renewable energy sources. The findings also reveal that the higher economic growth caused by the use of renewables is observed for the leading countries but at the same time the risk of a greater recession is much more likely than in other countries. These findings would help government officials and policymakers to better understand the role of renewable energy in the economic growth of these countries. This study has contributed to the literature on renewable energy sources and statistical reports under the EU energy sector framework.
Scale Effect on Producing Gaseous and Liquid Chemical Fuels via CO2 Reduction
Authors: Liu Ya , Lei Dan , Guo Xiaoqi , Ma Tengfei , Wang Feng , Chen Yubin
Published: January 2022

Producing chemical fuels from sunlight is a sustainable way to utilize solar energy and reduce carbon emissions. Within the current photovoltaic-electrolysis or photoelectrochemical-based solar fuel generation system, electrochemical CO2 reduction is the key step. Although there has been important progress in developing new materials and devices, scaling up electrochemical CO2 reduction is essential to promote the industrial application of this technology. In this work, we use Ag and In as the representative electrocatalyst for producing gas and liquid products in both small and big electrochemical cells. We find that gas production is blocked more easily than liquid products when scaling up the electrochemical cell. Simulation results show that the generated gas product, CO, forms bubbles on the surface of the electrocatalyst, thus blocking the transport of CO2, while there is no such trouble for producing the liquid product such as formate. This work provides methods for studying the mass transfer of CO, and it is also an important reference for scaling up solar fuel generation devices that are constructed based on electrochemical CO2 reduction.
A Hydrofracturing-Triggered Earthquake Occurred Three Years after the Stimulation
Authors: Lasocki Stanisław , Rudziński Łukasz , Tokarski Antek K. , Orlecka-Sikora Beata
Published: January 2022

Hydrofracturing, used for shale gas exploitation, may induce felt, even damaging earthquakes. On 15 June 2019, an Mw2.8 earthquake occurred, spatially correlated with the location of earlier exploratory hydrofracturing operations for shale gas in Wysin in Poland. However, this earthquake was atypical. Hydrofracturing-triggered seismicity mainly occurs during stimulation; occasionally, it continues a few months after completion of the stimulation. In Wysin, there were only two weaker events during two-month hydrofracturing and then 35 months of seismic silence until the mentioned earthquake occurred. The Wysin site is in Gdańsk Pomerania broader region, located on the very weakly seismically active Precambrian Platform. The historical documents, covering 1000 years, report no natural earthquakes in Gdańsk Pomerania. We conclude, therefore, that despite the never observed before that long lag time after stimulation, the Mw2.8 earthquake was triggered by hydrofracturing. It is possible that its unusually late occurrence in relation to the time of its triggering technological activity was caused by changes in stresses due to time-dependent deformation of reservoir shales. The Wysin earthquake determines a new time horizon for the effect of HF on the stress state, which can lead to triggering earthquakes. Time-dependent deformation and its induced stress changes should be considered in shall gas reservoir exploitation plans.
Do COVID-19 Lock-Downs Affect Business Cycle? Analysis Using Energy Consumption Cycle Clock for Selected European Countries
Authors: Kufel Tadeusz , Kufel Paweł , Błażejowski Marcin
Published: January 2022

On 11 March 2020, the WHO declared the COVID-19 epidemic to be a global pandemic. This was a consequence of the rapid increase in the number of people with positive test results, the increase in deaths due to COVID-19, and the lack of pharmaceutical drugs. Governments introduced national lockdowns, which have impacted both energy consumption and economies. The purpose of this paper is to answer the following question: do COVID-19 lockdowns affect the business cycle? We used the cycle clock approach to assess the magnitude of decrease in electricity consumption in the three waves of the epidemic, namely, April 2020, November 2021, and April 2021. Additionally, we checked the relation between energy consumption and GDP by means of spectral analysis. Results for selected 28 European countries confirm an impact of the introduced non-pharmaceutical interventions on both energy consumption and business cycle. The reduction of restrictions in subsequent pandemic waves increased electricity consumption, which suggests movement out of the economic recession.
Study on the Influential Factors of CO2 Storage in Low Permeability Reservoir
Authors: Yue Ping , Zhang Rujie , Sheng James J. , Yu Gaoming , Liu Feng
Published: January 2022

As the demands of tight-oil Enhanced Oil Recovery (EOR) and the controlling of anthropogenic carbon emission have become global challenges, Carbon Capture Utilization and Sequestration (CCUS) has been recognized as an effective solution to resolve both needs. However, the influential factors of carbon dioxide (CO2) geological storage in low permeability reservoirs have not been fully studied. Based on core samples from the Huang-3 area of the Ordos Basin, the feasibility and influential factors of geological CO2 sequestration in the Huang-3 area are analyzed through caprock breakthrough tests and a CO2 storage factor experiment. The results indicate that capillary trapping is the key mechanism of the sealing effect by the caprock. With the increase of caprock permeability, the breakthrough pressure and pressure difference decreased rapidly. A good exponential relationship between caprock breakthrough pressure and permeability can be summarized. The minimum breakthrough pressure of CO2 in the caprock of the Huang-3 area is 22 MPa, and the breakthrough pressure gradient is greater than 100 MPa/m. Huang-3 area is suitable for the geological sequestration of CO2, and the risk of CO2 breakthrough in the caprock is small. At the same storage percentage, the recovery factor of crude oil in larger permeability core is higher, and the storage percentage decreases with the increase of recovery factor. It turned out that a low permeability reservoir is easier to store CO2, and the storage percentage of carbon dioxide in the miscible phase is greater than that in the immiscible phase. This study can provide empirical reference for caprock selection and safety evaluation of CO2 geological storage in low permeability reservoirs within Ordos Basin.
Modelling of Luminous Flux Directed to the Upper Hemisphere from Electrical Substation before and after the Refurbishment of Lighting Systems
Authors: Novak Tomas , Becak Petr , Dubnicka Roman , Raditschova Jana , Gasparovsky Dionyz , Valicek Pavel , Ullman Jiri
Published: January 2022

This article deals with options for how to express the luminous flux from outdoor electrical substations of the electric transmission system. Processing of the models of light emissions before and after refurbishment of lighting systems was motivated by setting out rules for the design and erection of refurbished lighting systems in outdoor electrical substations, which are most commonly built in inhabited rural areas with low luminance of the background. The proposed model and calculations are based on requirements of international standards and recommendations for lighting of outdoor workplaces as well as on internal regulations of the ČEPS (Czech Transmission System Operator). These requirements are implemented in real electrical substations and lighting models that are extended by the calculation space of the software goniophotometer. The software goniophotometer was used to evaluate light distribution characteristics of entire electric stations in various situations. This article assesses the impact of different lighting systems installed at electrical substations from the perspective of both direct and total luminous flux directed to the upper hemisphere. It takes into account three outdoor electrical substations (420 kV) of a transmission network and their lighting systems before and after refurbishment. The aim of this article is to determine to what extent the electrical substations contribute to emissions of luminous flux to the upper hemisphere. Results from calculations on models show reduced radiation to the upper hemisphere up to 52.3% after refurbishment of obsolete lighting systems, although total installed flux actually increased due to a change in the ratio of direct and reflected luminous flux after refurbishment of lighting systems.
Flushing of Soils Highly Contaminated with Cd Using Various Washing Agents Derived from Sewage Sludge
Authors: Klik Barbara K. , Kulikowska Dorota , Gusiatin Zygmunt M.
Published: January 2022

The suitability of sewage-sludge derived washing agents (SS_WAs) (dissolved organic matter DOM; humic-like substances HLS; soluble humic substances SHS), was assessed for removing Cd from highly contaminated (300 mg/kg) sandy clay loam and clay. The soils were remediated via column flushing at two flow rates, 0.5 and 1.0 mL/min. The stability of the flow velocity (FV) depended on the type of SS_WA and decreased in the following order: DOM > HLS > SHS. Cd was most effectively removed during the first hours of flushing, and the process proceeded with a first-order kinetics. The overall process efficiency was higher at flow rate of 1.0 mL/min than at 0.5 mL/min and ranged from 65.7 (SHS) to 75.5% (DOM) for the sandy clay loam and from 64.7% (SHS) to 67.8% (DOM) for the clay. However, all SS_WAs at both flow rates removed the most mobile Cd fraction (F1) with an efficiency above 90%. Flushing improved soil characteristics in terms of the content of organic matter, humic substances and nutrients. Among all SS_WAs, DOM was the most suitable for remediation of highly Cd-contaminated soils due to high efficiency of Cd removal, the high stability of its FV during flushing and the simple manner of DOM recovery from sewage sludge.
On the Impact of Climate Change on Building Energy Consumptions: A Meta-Analysis
Authors: Campagna Ludovica Maria , Fiorito Francesco
Published: January 2022

The body of literature on climate change impacts on building energy consumption is rising, driven by the urgency to implement adaptation measures. Nevertheless, the multitude of prediction methodologies, future scenarios, as well as climate zones investigated, results in a wide range of expected changes. For these reasons, the present review aims to map climate change impacts on building energy consumption from a quantitative perspective and to identify potential relationships between energy variation and a series of variables that could affect them, including heating and cooling degree-days (HDDs and CDDs), reference period, future time slices and IPCC emission scenarios, by means of statistical techniques. In addition, an overview of the main characteristics of the studies related to locations investigated, building types and methodological approaches are given. To sum up, global warming leads to: (i) decrease in heating consumptions; (ii) increase in cooling consumption; (iii) growth in total consumptions, with notable differences between climate zones. No strong correlation between the parameters was found, although a moderate linear correlation was identified between heating variation and HDDs, and total variation and HDDs. The great variability of the collected data demonstrates the importance of increasing specific impact studies, required to identify appropriate adaptation strategies.
The Impact of Climate Change on Primary Air Treatment Processes and Energy Demand in Air Conditioning Systems—A Case Study from Warsaw, Poland
Authors: Kostka Maria , Zając Agnieszka
Published: January 2022

This article presents the impact of climate change on air treatment processes and energy demand in a selected air-conditioning system. The analysis was performed for a system supplying rooms with pre-treated primary air. Further treatment occurred directly in the rooms with individual devices such as fan coils or chilled beams. The analysis of the second stage of air treatment was not part of this study. The calculations were made for the city of Warsaw, where, according to the climate analysis for the period 1961–2020, an increase in outside temperature by 0.4 °C per decade and an increase in air humidity by 0.2 g/kg per decade were observed. The system analysis was divided into two stages. The first, including calculations made for monthly average climate data for the entire period of 1961–2020, shows changes in the energy demand of the system, resulting from progressive climate change. This analysis confirmed the general tendency of increasing demand for cooling energy and decreasing demand for heating energy, which is also observed in many other regions of the world. The second stage, based on calculations for hourly climate data in selected years, is an analysis of the operation of all elements of the system equipment. Research has identified areas that will have an increasing impact on the energy efficiency of the whole air condition system during further climate change.
Control Analysis with Modified LQR Method of Anti-Tank Missile with Vectorization of the Rocket Engine Thrust
Authors: Nocoń Łukasz , Grzyb Marta , Szmidt Piotr , Koruba Zbigniew , Nowakowski Łukasz
Published: January 2022

This article approaches the issue of the optimal control of a hypothetical anti-tank guided missile (ATGM) with an innovative rocket engine thrust vectorization system. This is a highly non-linear dynamic system; therefore, the linearization of such a mathematical model requires numerous simplifications. For this reason, the application of a classic linear-quadratic regulator (LQR) for controlling such a flying object introduces significant errors, and such a model would diverge significantly from the actual object. This research paper proposes a modified linear-quadratic regulator, which analyzes state and control matrices in flight. The state matrix is replaced by a Jacobian determinant. The ATGM autopilot, through the LQR method, determines the signals that control the control surface deflection angles and the thrust vector via calculated Jacobians. This article supplements and develops the topics addressed in the authors’ previous work. Its added value includes the introduction of control in the flight direction channel and the decimation of the integration step, aimed at speeding up the computational processes of the second control loop, which is the LQR based on a linearized model.
Method to Predict the Non-Uniform Potential Distribution in Random Electrical Machine Windings under Pulse Voltage Stress
Authors: Hoffmann Alexander , Ponick Bernd
Published: January 2022

This article describes a practical method for predicting the distribution of electric potential inside an electrical machine’s winding based on design data. It broadens the understanding of winding impedance in terms of inter-winding behavior and allows to properly design an electrical machine’s insulation system during the development phase. The predictions are made based on an frequency-dependent equivalent circuit of the electrical machine which is validated by measurements in the time domain and the frequency domain. Element parameters for the equivalent circuit are derived from two-dimensional field simulations. The results demonstrate a non-uniform potential distribution and demonstrate that the potential difference between individual turns and between turns and the stator core exceeds the expected values. The findings also show a link between winding impedance and potential oscillations inside the winding. Additionally, the article provides an overview of the chronological progression of turn-based models and shows how asynchronous multiprocessing is used to accelerate the solution process of the equivalent circuit.
New Ways for the Advanced Quality Control of Liquefied Natural Gas
Authors: Ferreiro Borja , Andrade Jose , Paz-Quintáns Carlota , López-Mahía Purificación , Muniategui-Lorenzo Soledad
Published: January 2022

Currently, gas chromatography is the most common analytical technique for natural gas (NG) analysis as it offers very precise results, with very low limits of detection and quantification. However, it has several drawbacks, such as low turnaround times and high cost per analysis, as well as difficulties for on-line implementation. With NG applications rising, mostly thanks to its reduced gaseous emissions in comparison with other fossil fuels, the necessity for more versatile, fast, and economic analytical methods has augmented. This work summarizes the latest advances to determine the composition and physico-chemical properties of regasified liquid natural gas, focusing on infrared spectroscopy-based techniques, as well as on data processing (chemometric techniques), necessary to obtain adequate predictions of NG properties.
Application of a Thermal Performance-Based Model to Prediction Energy Consumption for Heating of Single-Family Residential Buildings
Authors: Szul Tomasz
Published: January 2022

Energy consumption for heating of single-family residential buildings is a basic item in energy balance and significantly affects their operating costs. Accuracy of heat consumption assessment in existing buildings to a large extent determines the decision on taking actions aimed at heat consumption rationalization, both at the level of a single building and at regional or national level. In the case of energy calculations for the existing buildings, a problem often arises in the form of lack of complete architectural and construction documentation of the analyzed objects. Therefore, there is a need to search for methods that will be suitable for rapid energy analysis in existing buildings. These methods should give satisfactory results in predicting energy consumption when there is limited access to data characterizing the building. Therefore, the aim of this study was to check the usefulness of a model based on thermal characteristics for estimating energy consumption for heating in single-family residential buildings. The research was conducted on a group of 84 buildings, for which the energy characteristics were determined based on the actual energy consumption. In addition, information was collected on variables describing these buildings in terms of construction technology and building geometry, from which the following were extracted for further calculations: cubic capacity, heated area, and year of construction. This made it possible to build a prediction model, which enables the application of a fast, relatively simple procedure of estimating the final energy demand index for heating buildings. The resulting calculations were compared with actual values (calculated from energy bills) and then evaluated according to the standards for evaluating model quality proposed by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE). In this way, it was possible to determine whether, in the absence of building documents, the indicative method gives good results when estimating the energy demand for heating single-family residential buildings.
Design and Structural Simulations of a Custom Li-Po Accumulator for Low Range, Lightweight, Single-Seater, Open Cockpit, and Open-Wheeled Racecar
Authors: Khedkar Nitin , Bhatt Akul , Kapadia Dhruval , Chavan Shantanu , Agarwal Yash , Abouel Nasr Emad , Davim João Paulo , Salunkhe Sachin
Published: January 2022

Electric, hybrid, and fuel cell vehicles are the future of the automobile industry, and power source design is one of the most crucial steps in designing these vehicles. This paper aims to design and structurally simulate a custom accumulator—which powers an electric vehicle, for a lightweight, single-seater formula-style racecar. The work is dependent on the model-based design and CAD model approach. Mathematical modeling on SCILAB is used to model equations to get the characteristics of the accumulator, such as the energy, capacity, current, voltage, state of charge, and discharge rates. The output of this model gives the configuration of the battery pack as several cells in series and parallel to adequately power the tractive system. An accumulator container is designed to safeguard the cells from external impacts and vibrational loads, which otherwise can lead to safety hazards. Following this, the Finite Element Analysis (FEA) performed on the accumulator resulted in maximum peak deformation of 0.56 mm, ensuring the safety check against various external loads. Further, the finer stability of the battery pack was virtually validated after performing the vibrational analysis, resulting in a deformation of 3.5493 mm at a 1760.8 Hz frequency.
Mixed H2/H∞ Optimal Voltage Control Design for Smart Transformer Low-Voltage Inverter
Authors: Hu Wei , Shen Yu , Yang Zhichun , Min Huaidong
Published: January 2022

The smart transformer has been widely applied for the integration of renewables and loads. For the smart transformer application, the voltage control of low-voltage inverter is important for feeding the load. In this paper, a multi-objective optimization control design approach which comprehensively considers all aspects of indexes, such as linear quadratic (LQ) index, H∞ norm, and closed-loop poles placement, is proposed based on the linear matrix inequality (LMI) solution. The proposed approach is able to alleviate the weight of the designer from the tedious design process of the multiple resonant controllers and the selection of the weighting matrix for the LQ control. Besides that, some excellent performances such as fast recovering time, low total harmonic distortion (THD) and high robustness are achieved by the proposed approach. The THD are 0.5% and 1.7% for linear and non-linear loads, respectively. The voltage drop for linear load step is reduced to 10 V. The proposed approach is applied to a 5 kVA three-phase inverter to yield an optimal control law. Results from the simulation and experiment presented herein will illustrate and validate the proposed approach.
Possibility of Advanced Modified-Silica-Based Porous Materials Utilisation in Water Adsorption Processes—A Comparative Study
Authors: Sztekler Karol , Mlonka-Mędrala Agata , Khdary Nezar H. , Kalawa Wojciech , Nowak Wojciech , Mika Łukasz
Published: January 2022

Due to a high risk of power outages, a heat-driven adsorption chillers are gaining the attention. To increase the efficiency of the chiller, new adsorbents must be produced and examined. In this study, four newly developed silica–based porous materials were tested and compared with silica gel, an adsorber commonly paired with water. Extended sorption tests using mercury intrusion porosimetry, gas adsorption, and dynamic vapor sorption were performed. The morphology of the samples was determined using a scanning electron microscope. The thermal properties were defined using simultaneous thermal analysis and a laser flash method. Metal organic silica (MOS) nanocomposites analysed in this study had thermal properties similar to those of commonly used silica gel. MOS samples have a thermal diffusivity coefficient in the range of 0.17–0.25 mm2/s, whereas silica gel of about 0.2 mm2/s. The highest water adsorption capacity was measured for AFSMo-Cu and equal to 33–35%. For narrow porous silica gel mass uptake was equal about 25%. In the case of water adsorption, it was observed that the pore size of the sorbent is essential, and adsorbents with pore sizes higher than 5 nm, are most recommended in working pairs with water.
A Smart Energy Recovery System to Avoid Preheating in Gas Grid Pressure Reduction Stations
Authors: Danieli Piero , Masi Massimo , Lazzaretto Andrea , Carraro Gianluca , Volpato Gabriele
Published: January 2022

Preheating is often required to prevent hydrate formation during the pressure reduction process in a natural gas distribution network’s pressure reduction station. This paper examines an energy recovery method to avoid the cost and energy consumption of this preheating. The primary aim is to assess the techno-economic feasibility of an energy recovery system based on the Ranque–Hilsch vortex tube coupled to a heat exchanger for large-scale application to the gas grid. To this end, a techno-economic model of the entire energy recovery system was included in an optimisation procedure. The resulting design minimises the payback period (PP) when the system is applied to the pressure reduction stations belonging to a particular gas grid. The pressure reduction stations always operate at an outlet pressure above atmospheric pressure. However, available performance models for the Ranque–Hilsch vortex tube do not permit prediction at backpressure operation. Therefore, a novel empirical model of the device is proposed, and a cost function derived from several manufacturer quotations is introduced for the first time, to evaluate the price of the Ranque–Hilsch vortex tubes. Finally, a nearly complete set of pressure reduction stations belonging to the Italian natural gas grid was chosen as a case study using actual operating parameters collected by each station’s grid manager. The results indicate that the environmental temperature strongly affects the technical and economic feasibility of the proposed energy recovery system. In general, pressure reduction stations operating at an ambient temperature above 0 °C are economically desirable candidates. In addition, the higher the energy recovery system convenience, the higher the flow rate and pressure drop managed by the station. In the Italian case study, 95% of preheating costs could be eliminated with a PP of fewer than 20 years. A 40% preheating cost saving is still possible if the maximum PP is limited to 10 years, and a small but non-negligible 3% of preheating costs could be eliminated with a PP of fewer than 4.5 years.
Multi-Agent Real-Time Advanced Metering Infrastructure Based on Fog Computing
Authors: Popović Ivan , Rakić Aleksandar , Petruševski Ivan D.
Published: January 2022

This effort to make the power grid more intelligent is tightly coupled with the deployment of advanced metering infrastructure (AMI) as an integral part of the future vision of smart grid. The goal of AMI is to provide necessary information for the consumers and utilities to accurately monitor and manage energy consumption and pricing in real time. Immediate benefits are enhanced transparency and efficiency of energy usage and the improvement of customer services. Although the road map toward successful AMI deployment is clearly defined, many challenges and issues are to be solved regarding the design of AMI. In this paper, a multi-agent AMI based on the fog-computing approach is presented. Architecture follows structural decomposition of AMI functionalities encapsulated in a form of local and area-specific service components that reside at the different tiers of hierarchically organized AMI deployment. Fog computing concepts provide the framework to effectively solve the problems of creating refined and scalable solutions capable of meeting the requirements of the AMI as a part of future smart grid. On the other hand, agent-based design enables concurrent execution of AMI operations across the distributed system architecture, in the same time improving performance of its execution and preserving the scalability of the AMI solution. The real-time performance of the proposed AMI solution, related to the periodic and on-demand acquisition of metering data from the connected electricity meters, was successfully verified during one year of pilot project operation. The detailed analysis of the performance of AMI operation regarding data collection, communication and data availability across the deployed pilot AMI, covering several transformer station areas with diverse grid topologies, is also presented.
Extending DC Bus Utilization for Induction Motors with Stator Flux Oriented Direct Torque Control
Authors: Esparza Sola Tomas , Chiu Huang-Jen , Liu Yu-Chen , Rahman Arief Noor
Published: January 2022

This paper presents a method to extend the DC bus utilization on an induction motor (IM) by using a combination of Space-Vector Modulated Direct Torque Control (DTC–SVM) and conventional DTC. The scheme proposed in this paper exploits the advantages of both control methods. During the linear region, it allows for a low torque ripple and low current harmonic distortion (THD). During the overmodulation region, it allows for the fastest torque response up to the six-step operation region. In both regions, there is complete independence of the motor parameters. The paper describes a way to provide a smooth transition between the two control schemes. Non-linearities affect the stator flux angle estimation, which leads to the inability to decouple torque and flux. To overcome this problem, a novel PI-based control scheme as well as a simplification on the decoupling terms’ calculation are proposed. Simulation and experimental results are presented to verify the feasibility of the proposed method.
Methods of Thermal Treatment of Radioactive Waste
Authors: Fuks Leon , Herdzik-Koniecko Irena , Kiegiel Katarzyna , Miskiewicz Agnieszka , Zakrzewska-Koltuniewicz Grazyna
Published: January 2022

Throughout the world, and especially in the European Union, numerous technologies for the thermal treatment of radioactive waste are available or being developed. These technologies can be applied to a large range of different radioactive waste streams, including non-standard types of waste that present specific waste management challenges. Thermal treatment can result in a significant reduction in volume and hazard, which are beneficial for safe storage and disposal. Thermal treatment also removes organic material that can form complexing agents and increase the mobility of radionuclides in the landfill. In the paper, basic thermal techniques are presented, and some examples of the installations are shown. Common knowledge of these methods may result in an increased public acceptance of nuclear energy in a country just introducing it, as Poland is.
Simulation and Flow Analysis of the Hole Diaphragm Labyrinth Seal at Several Whirl Frequencies
Authors: Zhang Xiang , Jiao Yinghou , Qu Xiuquan , Huo Guanghe , Zhao Zhiqian
Published: January 2022

The seal is designed to reduce leakage and improve the efficiency of gas turbine machines, and is an important technology that needs to be studied in gas turbine design. A series of seals were proposed to try to achieve this goal. However, due to the complex fluid dynamic performance of the seal-rotor system, the seal structure can obtain both the best leakage performance and best rotordynamic performance. This paper presents a detailed flow analysis of the hole diaphragm labyrinth seal (HDLS) at several whirl frequencies and several rotation speeds. The pressure drop, velocity, turbulence kinetic energy and leakage performance of the HDLS were discussed by simulations. An interesting exponential–type relationship between rotation speeds and leakage flow at different whirl frequencies was observed by curve fitting technology. A reverse flow rate was proposed to describe such an unusual phenomenon. Such a relationship can be used to further establish the leakage model of the HDLS and other similar seals.
Numerical Simulation of Operating Parameters of the Ground Source Heat Pump
Authors: Bartyzel Filip , Wegiel Tomasz , Kozień-Woźniak Magdalena , Czamara Marek
Published: January 2022

Due to the growing demand for new ecological, low-emission heat sources, there is a need to develop new tools for simulating the operating parameters and costs of the implemented solutions. The article analyses the existing solutions for the simulation of heat pump operation parameters, describes the requirements for a modern building—nZEB and proposes a simulation tool based on thermodynamic parameters of the refrigerant. The script allows for deriving simple linear equations that can be used for the overall simulation of a system in which the heat pump is a key part and the efficiency of the entire system depends on its performance. The developed numerical script allows for reproducing the Linde refrigeration cycle and the parameters of its characteristic points. To calibrate the simulation, historical data obtained from the SOPSAR system were used. These data were pre-cleaned (peaks and other obvious measurement errors were removed). The obtained numerical model in combination with ground and air temperatures, anticipated hot water consumption and energy losses of the building can be used to simulate the annual performance and energy consumption of the heat pump. The obtained linear models have an RSMD error of 8% compared to historical data from SOPSAR system for all sets of simulated temperatures.
Bio-Based Waste’ Substrates for Degraded Soil Improvement—Advantages and Challenges in European Context
Authors: Kacprzak Malgorzata , Kupich Iwona , Jasinska Anna , Fijalkowski Krzysztof
Published: January 2022

The area of degraded sites in the world is constantly expanding and has been a serious environmental problem for years. Such terrains are not only polluted, but also due to erosion, devoid of plant cover and organic matter. The degradation trends can be reversed by supporting remediation/reclamation processes. One of the possibilities is the introduction of biodegradable waste/biowaste substrates into the soil. The additives can be the waste itself or preformed substrates, such composts, mineral-organic fertilizers or biochar. In EU countries average value of compost used for land restoration and landfill cover was equal 4.9%. The transformation of waste in valuable products require the fulfillment of a number of conditions (waste quality, process conditions, law, local circumstances). Application on degraded land surface bio-based waste substrates has several advantages: increase soil organic matter (SOM) and nutrient content, biodiversity and activity of microbial soil communities and change of several others physical and chemical factors including degradation/immobilization of contaminants. The additives improve the water ratio and availability to plants and restore aboveground ecosystem. Due to organic additives degraded terrains are able to sequestrate carbon and climate mitigate. However, we identified some challenges. The application of waste to soil must comply with the legal requirements and meet the end of use criteria. Moreover, shorter or long-term use of bio-waste based substrate lead to even greater soil chemical or microbial contamination. Among pollutants, “emerging contaminants” appear more frequently, such microplastics, nanoparticles or active compounds of pharmaceuticals. That is why a holistic approach is necessary for use the bio-waste based substrate for rehabilitation of soil degraded ecosystems.
First-Principles Study of Amorphous Al2O3 ALD Coating in Li-S Battery Electrode Design
Authors: Klorman Jake A. , Guo Qing , Lau Kah Chun
Published: January 2022

The Li-S battery is exceptionally appealing as an alternative candidate beyond Li-ion battery technology due to its promising high specific energy capacity. However, several obstacles (e.g., polysulfides’ dissolution, shuttle effect, high volume expansion of cathode, etc.) remain and thus hinder the commercialization of the Li-S battery. To overcome these challenges, a fundamental study based on atomistic simulation could be very useful. In this work, a comprehensive investigation of the adsorption of electrolyte (solvent and salt) molecules, lithium sulfide, and polysulfide (Li2Sx with 2 ≤x≤ 8) molecules on the amorphous Al2O3 atomic layer deposition (ALD) surface was performed using first-principles density functional theory (DFT) calculations. The DFT results indicate that the amorphous Al2O3 ALD surface is selective in chemical adsorption towards lithium sulfide and polysulfide molecules compared to electrolytes. Based on this work, it suggests that the Al2O3 ALD is a promising coating material for Li-S battery electrodes to mitigate the shuttling problem of soluble polysulfides.