bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of Gaussian Radial Basis Functions for Fast Spatial Imaging of Ground Penetration Radar Data Obtained on an Irregular Grid
Authors: Jasek Krzysztof , Pasternak Mateusz , Miluski Witold , Bugaj Jarosław , Grabka Michał
Published: November 2021

Spatial imaging of ground penetrating radar (GPR) measurement data is a difficult computational problem that is time consuming and requires substantial memory resources. The complexity of the problem increases when the measurements are performed on an irregular grid. Such grid irregularities are typical for handheld or flying GPR systems. In this paper, a fast and efficient method of GPR data imaging based on radial basis functions is described. A compactly supported modified Gaussian radial basis function (RBF) and a hierarchical approximation method were used for computation. The approximation was performed in multiple layers with decreasing approximation radius, where in successive layers, increasingly finer details of the imaging were exposed. The proposed method provides high flexibility and accuracy of approximation with a computational cost of N·log (N) for model building and N·M for function evaluation, where N is the number of measurement points and M is the number of approximation centres. The method also allows for the control smoothing of measurement noise. The computation of one high-quality imaging using 5000 measurement points utilises about 5 s on an Intel Core i5-7200U CPU 2.5 GHz, 8 GB RAM computer. Such short time enables real-time image processing during field measurements.
Thermodynamic Insight in Design of Methanation Reactor with Water Removal Considering Nexus between CO2 Conversion and Irreversibilities
Authors: Hashemi Sayed Ebrahim , Lien Kristian M. , Hillestad Magne , Schnell Sondre K. , Austbø Bjørn
Published: November 2021

The inevitable nexus between energy use and CO2 emission necessitates the development of sustainable energy systems. The conversion of CO2 to CH4 using green H2 in power-to-gas applications in such energy systems has attracted much interest. In this context, the present study provides a thermodynamic insight into the effect of water removal on CO2 conversion and irreversibility within a CO2 methanation reactor. A fixed-bed reactor with one intermediate water removal point, representing two reactors in series, was modeled by a one-dimensional pseudo-homogeneous model. Pure CO2 or a mixture of CO2 and methane, representing a typical biogas mixture, were used as feed. For short reactors, both the maximum conversion and the largest irreversibilities were observed when the water removal point was located in the middle of the reactor. However, as the length of the reactor increased, the water removal point with the highest conversion was shifted towards the end of the reactor, accompanied by a smaller thermodynamic penalty. The largest irreversibilities in long reactors were obtained when water removal took place closer to the inlet of the reactor. The study discusses the potential benefit of partial water removal and reactant feeding for energy-efficient reactor design.
Experimental Investigation of the Heat Transfer Characteristics and Operation Limits of a Fork-Type Heat Pipe for Passive Cooling of a Spent Fuel Pool
Authors: Lim Changhwan , Choi Jonghwi , Kim Hyungdae
Published: November 2021

A fork-type heat pipe (FHP) is a passive heat-transport and air-cooling device used to remove the decay heat of spent nuclear fuels stored in a liquid pool during a station blackout. FHPs have a unique geometrical design to resolve the significant mismatch between the convective heat transfer coefficients of the evaporator and condenser parts. The evaporator at the bottom is a single heat-exchanger tube, whereas the condenser at the top consists of multiple finned tubes to maximize the heat transfer area. In this study, the heat transfer characteristics and operating limits of an FHP device were investigated experimentally. A laboratory-scale model of an FHP was manufactured, and a series of tests were conducted while the temperature was varied to simulate a spent fuel pool. As an index of the average heat transfer performance, the loop conductance was computed from the measurement data. The results show that the loop conductance of the FHP increased with the heat transfer rate but deteriorated significantly at the operating limit. The maximum attainable heat transfer rate of the unit FHP model was accurately predicted by the existing correlations of the counter-current flow limit for a single-rod-type heat pipe. In addition, the instant heat transfer behaviors of the FHP model under different temperature conditions were examined to interpret the measured loop conductance variation and operating limit.
Social and Economic Value in Emerging Decentralized Energy Business Models: A Critical Review
Authors: Adams Sophie , Brown Donal , Cárdenas Álvarez Juan Pablo , Chitchyan Ruzanna , Fell Michael J. , Hahnel Ulf J. J. , Hojckova Kristina , Johnson Charlotte , Klein Lurian , Montakhabi Mehdi , Say Kelvin , Singh Abhigyan , Watson Nicole
Published: November 2021

In recent years, numerous studies have explored the opportunities and challenges for emerging decentralized energy systems and business models. However, few studies have focussed specifically on the economic and social value associated with three emerging models: peer-to-peer energy trading (P2P), community self-consumption (CSC) and transactive energy (TE). This article presents the findings of a systematic literature review to address this gap. The paper makes two main contributions to the literature. Firstly, it offers a synthesis of research on the social and economic value of P2P, CSC and TE systems, concluding that there is evidence for a variety of sources of social value (including energy independence, local benefits, social relationships, environmental responsibility and participation and purpose) and economic value (including via self-consumption of renewable electricity, reduced electricity import costs, and improved electricity export prices). Secondly, it identifies factors and conditions necessary for the success of these models, which include willingness to participate, participant engagement with technology, and project engagement of households and communities, among other factors. Finally, it discusses conflicts and trade-offs in the value propositions of the models, how the three models differ from one another in terms of the value they aim to deliver and some of the open challenges that require further attention by researchers and practitioners.
Modeling the TetraSpar Floating Offshore Wind Turbine Foundation as a Flexible Structure in OrcaFlex and OpenFAST
Authors: Thomsen Jonas Bjerg , Bergua Roger , Jonkman Jason , Robertson Amy , Mendoza Nicole , Brown Cameron , Galinos Christos , Stiesdal Henrik
Published: November 2021

Floating offshore wind turbine technology has seen an increasing and continuous development in recent years. When designing the floating platforms, both experimental and numerical tools are applied, with the latter often using time-domain solvers based on hydro-load estimation from a Morison approach or a boundary element method. Commercial software packages such as OrcaFlex, or open-source software such as OpenFAST, are often used where the floater is modeled as a rigid six degree-of-freedom body with loads applied at the center of gravity. However, for final structural design, it is necessary to have information on the distribution of loads over the entire body and to know local internal loads in each component. This paper uses the TetraSpar floating offshore wind turbine design as a case study to examine new modeling approaches in OrcaFlex and OpenFAST that provide this information. The study proves the possibility of applying the approach and the extraction of internal loads, while also presenting an initial code-to-code verification between OrcaFlex and OpenFAST. As can be expected, comparing the flexible model to a rigid-body model proves how motion and loads are affected by the flexibility of the structure. OrcaFlex and OpenFAST generally agree, but there are some differences in results due to different modeling approaches. Since no experimental data are available in the study, this paper only forms a baseline for future studies but still proves and describes the possibilities of the approach and codes.
A Rapid Method for Low Temperature Microencapsulation of Phase Change Materials (PCMs) Using a Coiled Tube Ultraviolet Reactor
Authors: Ansari Jawaad A. , Al-Shannaq Refat , Kurdi Jamal , Al-Muhtaseb Shaheen A. , Ikutegbe Charles A. , Farid Mohammed M.
Published: November 2021

Microencapsulation of phase change materials (PCMs) remain a suitable option within building materials, as they contribute to the thermal mass and provide an energy buffer, an added benefit. This paper presents a novel method for the rapid fabrication of microencapsulated phase change materials (PCMs) at ambient conditions in a perfluoroalkoxy (PFA) coiled tube ultraviolet (UV) reactor. The objective of this study was to optimize key parameters such as the product yield and quality of the as-prepared microcapsules. Rubitherm® RT-21™ PCM was microencapsulated within shells of poly-methyl-methacrylate (PMMA) through a suspension emulsion polymerization approach, where the crosslinking of polymers was driven by UV radiations with an appropriate photoinitiator. The characteristics of the resulting PCM microcapsules were found to be affected by the volumetric flow rate of the emulsion inside the coiled tube reactor. Higher volumetric flow rates led to higher PCM contents and higher microencapsulation efficiency, resulting in an average particle size of 6.5 µm. Furthermore, the effect of curing time on the PCM microcapsule properties was investigated. The optimum encapsulation yield, conversion, efficiency and PCM content were observed after 10 min of polymerization time. The thermal analysis indicated that the developed process had an efficiency of 85.8%, and the capsules were characterized with excellent thermal properties. Compared to the conventional thermal microencapsulation processes, the use of a coiled tube UV reactor with an appropriate photoinitiator enables the encapsulation of heat-sensitive PCMs at ambient conditions, and reduces the microencapsulation time dramatically. As a result, this novel microencapsulation approach can lead to a wider scope of PCM encapsulation and enable rapid, continuous and potentially large-scale industrial production of PCM microcapsules with low energy consumption.
Competency Gaps of Employees in the Construction Sector in Terms of the Requirements of a Low-Carbon Economy. Polish and Czech Case
Authors: Howaniec Honorata , Wróblewski Łukasz Krzysztof , Štverková Hana
Published: November 2021

Environmental policy obliges modern society to transition to a low-carbon economy. After entering to life, the Paris Agreement obligated the signatories to prepare the first nationally determined contributions (NDCs). The NDCs aim first to reduce greenhouse gas emission targets under the UNFCCC and they apply equally to both developed and developing countries. Countries voluntarily indicate what actions will be taken to achieve the declared goals. The construction sector is an industry that is under scrutiny due to its negative impact on the environment, but it also has the potential to reduce it. Activities that can reduce greenhouse gas emissions can be carried out at various levels in the construction industry. One of them is the appropriate preparation of the staff, including equipping them with the so-called green skills. This research aimed to determine the competency gaps of people employed in the construction industry, including competencies in the field of low-emission economy. For the purposes of the study, a questionnaire survey was carried out in Poland and the Czech Republic and based on the results obtained the appropriate competencies were determined that should be possessed by people employed in the construction sector, including competencies related to a low-emission economy. Competency profiles for people employed in the construction sector were built and competency gaps of these people were determined. In both countries, no competencies have been identified in any of checked areas that meet or exceed the requirements of managers according to specific competency profiles.
Tin Oxide Modified Titanium Dioxide as Electron Transport Layer in Formamidinium-Rich Perovskite Solar Cells
Authors: Koech Richard K. , Ichwani Reisya , Oyewole Deborah , Kigozi Moses , Amune Daniel , Sanni Dahiru M. , Adeniji Sharafadeen , Oyewole Kehinde , Bello Abdulhakeem , Ntsoenzok Esidor , Soboyejo Wole
Published: November 2021

The design of electron transport layers (ETLs) with good optoelectronic properties is one of the keys to the improvement of the power conversion efficiencies (PCEs) and stability of perovskite solar cells (PSCs). Titanium dioxide (TiO2), one of the most widely used ETL in PSCs, is characterized by low electrical conductivity that increases the series resistance of PSCs, thus limiting their PCEs. In this work, we incorporated tin oxide (SnO2) into titanium dioxide (TiO2) and studied the evolution of its microstructural and optoelectronic properties with SnO2 loading. The thin films were then integrated as ETLs in a regular planar Formamidinium (FA)-rich mixed lead halide PSCs so as to assess the overall effect of SnO2 incorporation on their charge transport and Photovoltaic (PV) characteristics. Analysis of the fabricated PSCs devices revealed that the best performing devices; based on the ETL modified with 0.2 proportion of SnO2; had an average PCE of 17.35 ± 1.39%, which was about 7.16% higher than those with pristine TiO2 as ETL. The improvement in the PCE of the PSC devices with 0.2 SnO2 content in the ETL was attributed to the improved electron extraction and transport ability as revealed by the Time Resolved Photoluminescence (TRPL) and Electrochemical Impedance Spectroscopy (EIS) studies.
A Fast and Accurate Wind Speed and Direction Nowcasting Model for Renewable Energy Management Systems
Authors: Al-Zadjali Saira , Al Maashri Ahmed , Al-Hinai Amer , Al Abri Rashid , Gajare Swaroop , Al Yahyai Sultan , Bakhtvar Mostafa
Published: November 2021

To plan operations and avoid any grid disturbances, power utilities require accurate power generation estimates for renewable generation. The generation estimates for wind power stations require an accurate prediction of wind speed and direction. This paper proposes a new prediction model for nowcasting the wind speed and direction, which can be used to predict the output of a wind power plant. The proposed model uses perturbed observations to train the ensemble networks. The trained model is then used to predict the wind speed and direction. The paper performs a comparative assessment of three artificial neural network models. It also studies the performance of introducing perturbed observations to the model using six different interpolation techniques. For each technique, the computational efficiency is measured and assessed. Furthermore, the paper presents an exhaustive investigation of the performance of neural network types and several techniques in training, data splitting, and interpolation. To check the efficacy of the proposed model, the power output from a real wind farm is predicted and compared with the actual recorded measurements. The results of the comprehensive analysis show that the proposed model outperforms contending models in terms of accuracy and execution time. Therefore, this model can be used by operators to reliably generate a dispatch plan.
Optimal Control of Plug-In Electric Vehicles Charging for Composition of Frequency Regulation Services
Authors: Germanà Roberto , Liberati Francesco , De Santis Emanuele , Giuseppi Alessandro , Delli Priscoli Francesco , Di Giorgio Alessandro
Published: November 2021

This paper presents a novel control system for the participation of plug-in electric vehicles (PEVs) in the provisioning of ancillary services for frequency regulation, in a way that is transparent to the driver and harmonized with the smart charging service requirements. Given a power-frequency droop curve, which specifies how the set of PEVs collectively participate to the provisioning of the frequency regulation service (we call this curve a “global” droop curve), we propose an algorithm to compute “local” droop curves (one for each PEV), which are optimized according to the current status of the PEV and the current progress of the smart recharging session. Once aggregated, the local droop curves match the global one (so that the PEVs contribute as expected to the provisioning of the ancillary service). One innovative aspect of the proposed algorithm is that it is specifically designed to be interoperable with the algorithms that control the PEV recharging process; hence, it is transparent to the PEV drivers. Simulation results are presented to validate the proposed solution.
A Market-Driven Management Model for Renewable-Powered Undergrid Mini-Grids
Authors: González Grandón Tatiana , de Cuadra García Fernando , Pérez-Arriaga Ignacio
Published: November 2021

Renewable-powered “undergrid mini-grids” (UMGs) are instrumental for electrification in developing countries. An UMG can be installed under a—possibly unreliable— main grid to improve the local reliability or the main grid may “arrive” and connect to a previously isolated mini-grid. Minimising costs is key to reducing risks associated with UMG development. This article presents a novel market-logic strategy for the optimal operation of UMGs that can incorporate multiple types of controllable loads, customer smart curtailment based on reliability requirements, storage management, and exports to and imports from a main grid, which is subject to failure. The formulation results in a mixed-integer linear programming model (MILP) and assumes accurate predictions of the following uncertain parameters: grid spot prices, outages of the main grid, solar availability and demand profiles. An AC hybrid solar-battery-diesel UMG configuration from Nigeria is used as a case example, and numerical simulations are presented. The load-following (LF) and cycle-charging (CC) strategies are compared with our predictive strategy and HOMER Pro’s Predictive dispatch. Results prove the generality and adequacy of the market-logic dispatch model and help assess the relevance of outages of the main grid and of spot prices above the other uncertain input factors. Comparison results show that the proposed market-logic operation approach performs better in terms of cost minimisation, higher renewable fraction and lower diesel use with respect to the conventional LF and CC operating strategies.
Dynamics of Electromechanical Systems Containing Long Elastic Couplings and Safety of Their Operation
Authors: Popenda Andrzej , Szafraniec Andrzej , Chaban Andriy
Published: November 2021

The electromechanical systems under analysis include electric drives, working machines that perform specific tasks in the technological process, and working mechanisms that transmit mechanical power between the electric drive and the working machine. The vast majority of electric motors included in drive systems require rotational speed control. This task is most often performed with the use of closed-loop control structures based on speed controllers. A step or overly rapid change in the speed reference causes a temporary lock of the speed controller due to the applied limitations at its output. Particularly, unfavorable effects of such a lock can be observed in drive systems in which there is a long elastic coupling (transmission shaft) between the electric motor and the working machine. As a consequence, shaft torsion and accompanying twisting moments of considerable amplitudes appear. This article proposes an uncomplicated active torque limiter structure, which enables the uninterrupted operation of the speed controller thanks to the automatic adaptation of the rate of the speed reference change to any moment of inertia of the rotor and attached rotating masses. The results of the investigations confirm the effectiveness of the proposed structure.
Optimal Control of a Doubly Fed Induction Generator of a Wind Turbine in Island Grid Operation
Authors: Gołębiowski Lesław , Gołębiowski Marek , Kwiatkowski Bogdan
Published: November 2021

Great significance is given to the use of energy from renewable sources, especially in industrial and municipal applications. The present article is devoted to the optimal control of a DFIG generator with the help of a rotor-side converter (RSC). Its aim is to ensure the delivery of the voltage of a three-phase network with appropriate parameters while operating in an islanded grid. Such a grid is usually characterized by an uneven loading of each phase. Additionally, the load of these phases changes randomly in time. In order to ensure the assumed parameters of line voltages, the optimal control is applied with a square cost function. This ensures the shape of voltage that is in accordance with the referential voltage. Moreover, higher harmonics with a given number are detected and reduced. The simulations that were executed confirm compliance with the conditions of the parameters of the output voltage in the islanded grid. Attention was paid to oscillations in the power flowing through the rotor-side converter (RSC). The methods to accelerate the suppression of these oscillations are presented.
Temperature and Electric Field Distribution Characteristics of a DC-GIL Basin-Type Spacer with 3D Modelling and Simulation
Authors: Li Xiaolong , Wan Mingde , Yan Shouyi , Lin Xin
Published: November 2021

The temperature properties of real-type direct-current gas-insulated transmission lines (DC-GIL) with a basin-type spacer were investigated by the finite element method in this paper. A horizontally installed model was established and the temperature distribution was obtained with a 3D model. The specific heat capacity and thermal conductivity of the spacer were measured and applied in the simulation. The results show that the temperature of the convex surface was slightly higher than that of the concave surface. With an increase in the SF6 pressure, the temperature of the spacer decreased, which can be attributed to the improvement of convection due to increases in the heat capacity per unit volume. With an increase in the ambient temperature, the temperature of the spacer increased linearly. The temperature difference between the inner and outer parts of the spacer increased with increases in the load current. Besides, an obvious increase in the surface electric field strength appeared under the influence of the thermal gradient compared to the results without the thermal gradient. Thus, special attention should be paid to the insulation properties of the spacer considering the influence of temperature distribution. This study evaluates both the thermal and insulation characteristics of the GIL along with the spacer under various conditions.
Real-Time Monitoring of the Vacuum Degree Based on the Partial Discharge and an Insulation Supplement Design for a Distribution Class Vacuum Interrupter
Authors: Bang Seungmin , Lee Hyun-Woo , Lee Bang-Wook
Published: November 2021

The internal pressure of a vacuum interrupter (VI) is increased by arc heat, ceramic cracking, gas leakage, and manufacturing defects. Accordingly, the dielectric strength of VI rapidly decreases. To improve the reliability of power transmission, efficient maintenance through the real-time monitoring of the vacuum degree is essential. However, real-time monitoring of the vacuum degree is difficult, and related research is scarce. Additionally, due to the insulation problems of this technology, there are few commercially available products. Therefore, this paper proposes a method for real-time monitoring of the vacuum degree and an insulation supplement design for a distribution class VI. First, dielectric experiments were conducted to identify the section in which the dielectric strength of the VI rapidly decreased according to the vacuum degree. Second, for real-time monitoring of the VI, several factors were proposed through the partial discharge in the VI, while the capacitance characteristics of the VI were calculated to improve the signal of the internal partial discharge. Finally, to supplement the dielectric problems of the solid insulation high voltage apparatus that occur when real-time monitoring technology is applied, the insulation supplement design was performed through the finite element method (FEM).
Operational Analysis of Fire Alarm Systems with a Focused, Dispersed and Mixed Structure in Critical Infrastructure Buildings
Authors: Jakubowski Krzysztof , Paś Jacek , Duer Stanisław , Bugaj Jarosław
Published: November 2021

The article presents issues regarding the impact of operating conditions on the functional reliability of representative fire alarm systems (FASs) in selected critical infrastructure buildings (CIB). FAS should operate correctly under variable environmental conditions. FASs ensure the safety of people and CIB. Operational measurements for 10 representative systems were conducted in order to determine the impact of environmental conditions on FAS reliability. Selected operational indices were also determined. The next stage involved developing two models of representative FASs and the availability, pre-ageing time and operating process security indices. Determining operational indices is a rational selection of FAS technical and organizational solutions that enables the reliability level to be increased. Identifying the course of the FAS operating process security hazard changes in individual system lines, particularly at the initial operation stage, enables people that supervise the operation to affect operating parameters on an ongoing basis. The article is structured in the following order: issue analysis, FAS power supply in CIB, operational test results, selected FAS operating process models, determination of operational and security indices, and conclusions.
Testing of Software for the Planning of a Linear Object GNSS Measurement Campaign under Simulated Conditions
Authors: Figiel Sławomir , Specht Cezary , Moszyński Marek , Stateczny Andrzej , Specht Mariusz
Published: November 2021

The precision of a linear object measurement using satellite techniques is determined by the number and the relative position of the visible satellites by the receiver. The status of the visible constellation is described by the Dilution Of Precision (DOP). The obtained geometric coefficient values are dependent on many variables. When determining these values, field obstacles at the receiver location and satellite positions changing with time must be taken into account. Carrying out a series of surveys as part of a linear object Global Navigation Satellite System (GNSS) measurement campaign requires the optimisation problem to be solved. The manner of the inspection vehicle’s movement should be determined in such a way that the surveys are taken only within the pre-defined time frames and that the geometric coefficient values obtained at subsequent points of the route are as low as possible. The purpose of this article is to develop a software for the planning of a linear object GNSS measurement campaign to implemented in motion and taking into account the terrain model and its coverage. Additionally, it was determined how much the developed program improves DOP values on the planned route under simulated conditions. This software has no equivalent elsewhere in the world, as the current solutions for the planning of a GNSS measurement campaign, e.g., Trimble GNSS Planning, GNSS Mission Planning, or GPS Navigation Toolbox, allow the satellite constellation geometry to be analysed exclusively for specific coordinates and at a specific time. Analysis of the obtained simulation test results indicates that the campaign implementation in accordance with the pre-determined schedule significantly improves the quality of the recorded GNSS data. This is particularly noticeable when determining the position using the Global Positioning System (GPS) and GLObal NAvigation Satellite System (GLONASS) satellite constellations at the same time. During the tests conducted on the road along a three-kilometre-long route (tram loop) in Gdańsk Brzeźno, the average value of the obtained Position Dilution Of Precision (PDOP) decreased by 22.17% thanks to using the software to plan a linear object GNSS measurement campaign. The largest drop in the geometric coefficient values was noted for an area characterised by a very large number of field obstacles (trees with crowns and high buildings). Under these conditions, the PDOP value decreased by approx. 25%. In areas characterised by a small number of field obstacles (single trees in the vicinity of the track, clusters of trees and buildings located along the track), the changes in the PDOP were slightly smaller and amounted to several percent.
A Step-by-Step Design for Low-Pass Input Filter of the Single-Stage Converter
Authors: He Qingqing , Liu Lei , Qiu Mingyang , Luo Quanming
Published: November 2021

Active power factor correction converters are often introduced as the front stage of power electronic equipment to improve the power factor and eliminate higher harmonics. A Boost or Buck-Boost converter operating in discontinuous current mode is always adopted to achieve high power factor correction. In addition, the input current contains a large amount of higher harmonics, and a low-pass input filter is commonly adopted to filter it out. In this paper, a single-stage high-frequency AC/AC converter is taken as an example to demonstrate the design method of a passive low-pass filter. Firstly, the input side of the grid needs to meet the power factor and harmonic requirements. The preset parameters are set to a range to characterize the performance of the LC filter. The quantitative design method of input filter is proposed and summarized. Moreover, the sensitivity of the filter parameters is analyzed, providing a direction in practical applications. Preset parameters are all proved to conform to the preset range through PSIM simulation. Finally, a 130-W prototype is established to verify the correction of proposed design method. The power factor is around 0.935 and harmonic content in the input current is about 26.4%. All requirements can be satisfied.
Investments in Renewable Energy Sources in the Concepts of Local Spatial Policy: The Case of Poland
Authors: Blaszke Małgorzata , Nowak Maciej , Śleszyński Przemysław , Mickiewicz Bartosz
Published: November 2021

The paper aims to determine the role and formula of investments in renewable energy sources in Poland’s concepts of local spatial policies. It analyses 12,777 planning documents of local spatial policy (these are resolutions adopted by municipalities—in Poland there are two types of these instruments: studies of spatial development conditions and directions and local spatial development plans) in Poland enacted in 2005–2020. On this basis, local concepts were classified and related to the geographical and functional characteristics of municipalities. Poland is an interesting case study in this respect, providing a good reference point for broader international considerations. It was found that only 58.4% of Polish municipalities include renewable energy sources in their spatial policy concept. These are definitely more often urbanised municipalities. The degree of approach to renewable energy sources is also determined by the location of the municipality in the given province. The authors diagnose serious weaknesses in the Polish spatial planning system, consisting in the lack of skilful implementation of renewable energy sources into it. This is one of the reasons for the weaker development of renewable energy sources in the country. The authors consider as an innovative element of the research the analysis of the content of all spatial policy instruments in a given country, from the perspective of renewable energy sources, including proposing a way to verify these instruments.
Experimental Investigation on the Performance and Emission Characteristics of a Compression Ignition Engine Using Waste-Based Tire Pyrolysis Fuel and Diesel Fuel Blends
Authors: Kondor István Péter , Zöldy Máté , Mihály Dénes
Published: November 2021

Due to the world’s growing population, the size of areas intended for food production in many countries of the world can only be achieved through severe environmental damage and deforestation, which has many other detrimental consequences in addition to accelerating global warming. By replacing the bio-content of fuels with other alternative fuels, land that is used for energy crops can also be used to grow food, thus mitigating the damaging effects of deforestation. Waste-based tire pyrolysis oil (TPO) can be a promising solution to replace the bio-proportion of diesel fuel. Since it is made from waste tires, it is also an optimal solution for recycling waste. This research shows the effect of different low-volume-percent tire pyrolyzed oil blended with diesel on the performance, fuel consumption, and emissions on a Mitsubishi S4S-DT industrial diesel engine. Four different premixed ratios of TPO were investigated (2.5%, 5%, 7.5% and 10%) as well as pyrolysis oil and 100% diesel oil; however, the following studies will only include the data from the pure diesel and the 10% TPO measurements. The experimental investigations were in an AVL electric dynamometer, the soot measurements were in an AVL (Anstalt für Verbrennungskraftmaschinen List) Micro soot sensor (MSS), and the emission measurements were in a AVL Furier-transform infrared spectroscopy (FTIR) taken. The scope of research was to investigate the effect of low volume percentage TPO on performance and emissions on a light-duty diesel engine.
Numerical Investigation of Transient Flow Characteristics in a Centrifugal Compressor Stage with Variable Inlet Guide Vanes at Low Mass Flow Rates
Authors: Li Shuai , Liu Yan , Omidi Mohammad , Zhang Chuang , Li Hongkun
Published: November 2021

This study numerically investigates the beneficial effects of positive pre-swirl on the aerodynamic performance and internal flow field in a centrifugal compressor stage with variable inlet guide vanes (VIGVs) at low mass flow rates. Four positions of VIGV are considered, including 0°, 30°, 45°, and 60° angle. The latter three positions of VIGV induce positive pre-swirl. Numerical results show that as positive pre-swirl increases, the aerodynamic performance curve of the stage moves in the low mass flow rate direction. In the three cases of positive pre-swirl, there was an improvement of approximately 9.95% of stall/surge margin greater than in conditions with no pre-swirl. The regulation of IGV can effectively improve the unstable flow of the compressor stage at low mass flow rates. A low frequency that has a great influence on the internal flow of the compressor stage is found, and the unstable flow caused by low frequency is analyzed by the combination of streamline distribution, spectrum analysis, vector, entropy increase, and modal decomposition method. Meanwhile, the modal decomposition method and flow field reconstruction techniques are used to investigate the coherent flow structures caused by low frequency under different guide vane openings.
Estimation of Stress-Strength Reliability for Multicomponent System with Rayleigh Data
Authors: Wang Liang , Lin Huizhong , Ahmadi Kambiz , Lio Yuhlong
Published: November 2021

Inference is investigated for a multicomponent stress-strength reliability (MSR) under Type-II censoring when the latent failure times follow two-parameter Rayleigh distribution. With a context that the lifetimes of the strength and stress variables have common location parameters, maximum likelihood estimator of MSR along with the existence and uniqueness is established. The associated approximate confidence interval is provided via the asymptotic distribution theory and delta method. Meanwhile, alternative generalized pivotal quantities-based point and confidence interval estimators are also constructed for MSR. More generally, when the lifetimes of strength and stress variables follow Rayleigh distributions with unequal location parameters, likelihood and generalized pivotal-based estimators are provided for MSR as well. In addition, to compare the equivalence of different strength and stress parameters, a likelihood ratio test is provided. Finally, simulation studies and a real data example are presented for illustration.
Spread Analysis of the Sustainability-Linked Bonds Tied to an Issuer’s Greenhouse Gases Emissions Reduction Target
Authors: Liberadzki Marcin , Jaworski Piotr , Liberadzki Kamil
Published: November 2021

Sustainability-Linked Bonds (SLBs) are a new type of general corporate purpose bond in which payments are tied to an issuer’s sustainability key performance indicators (KPIs) with respect to the environmental, social, and governance (ESG) criteria. The structure is complementary to green bonds. The Tesco SLBs are linked to the firm’s ability to cut its greenhouse gas emissions by 60%. The priority is to reduce its reliance on nonrenewable grid electricity, which contributed 65% of Tesco’s global carbon emissions footprint. Tesco accounts for 1% of electricity demand in the UK. Failure to meet the goals will result in a coupon step-up by 25 basis points on the last three coupons. The aim of our study is to investigate the presence of, how we call it ‘ESG spread’, marked by negative yield difference between SLB and regular bonds. It is something similar to ‘greenium’, that is, a premium paid by bondholders for green bonds when compared to nongreen bonds. We compare the bid and ask yields of SLBs with the interpolated yields, calculated for the yields of Tesco and Carrefour notes. Then, we look into the SLB yields in coupon step-up scenario to answer the question if the issuer’s failure to keep up with KPIs results in changing of ESG spread from negative to positive.
Real-Time Approximate Equivalent Consumption Minimization Strategy Based on the Single-Shaft Parallel Hybrid Powertrain
Authors: Qiang Penghui , Wu Peng , Pan Tao , Zang Huaiquan
Published: November 2021

Real-time energy management strategy (EMS) plays an important role in reducing fuel consumption and maintaining power for the hybrid electric vehicle. However, real-time optimization control is difficult to implement due to the computational load in an instantaneous moment. In this paper, an Approximate equivalent consumption minimization strategy (Approximate-ECMS) is presented for real-time optimization control based on single-shaft parallel hybrid powertrain. The quadratic fitting of the engine fuel consumption rate and the single-axle structure characteristics of the vehicle make the fitness function transformed into a cubic function based on ECMS for solving. The candidate solutions are thus obtained to distribute torque and the optimal distribution is got from the candidate solutions. The results show that the equivalent fuel consumption of Approximate-ECMS was 7.135 L/km by 17.55% improvement compared with Rule-ECMS in the New European Driving Cycle (NEDC). To compensate for the effect of the equivalence factor on fuel consumption, a hybrid dynamic particle swarm optimization-genetic algorithm (DPSO-GA) is used for the optimization of the equivalence factor by 9.9% improvement. The major contribution lies in that the Approximate-ECMS can reduce the computational load for real-time control and prove its effectiveness by comparing different strategies.
LPWAN Networks for Energy Meters Reading and Monitoring Power Supply Network in Intelligent Buildings
Authors: Nowak Mariusz , Derbis Piotr , Kurowski Krzysztof , Różycki Rafał , Waligóra Grzegorz
Published: November 2021

In this paper the idea of functioning of Building Management Systems and Object Management Systems in intelligent buildings is presented. New functionalities of intelligent buildings resulting from the introduction of microgeneration are described. Low-Power Wide-Area Networks (LPWAN) are characterized and compared. The selected Long-Range (LoRaWAN) technology is tested for its use for communication with energy meters and monitoring the power supply network in intelligent buildings. In the paper a new system for reading and monitoring the network is proposed, consisting of hardware, communication, and application layers. A key element of the system is a specially developed converter, which has been designed and tested in a real urban environment. Using our solution in practice could allow to change the architecture of a measurement data acquisition system to much more flexible and efficient.
Research on a Bi-Level Collaborative Optimization Method for Planning and Operation of Multi-Energy Complementary Systems
Authors: Liu Changrong , Wang Hanqing , Liu Zhiqiang , Wang Zhiyong , Yang Sheng
Published: November 2021

Multi-energy complementary systems (MCSs) are complex multilevel systems. In the process of system planning, many aspects—such as power planning, investment cost, and environmental impact—should be considered. However, different decision makers tend to have different levels of control objectives, and the multilevel problems of the system need to be solved effectively with comprehensive judgment. Therefore, based on the terminal MCS energy structure model, the optimization method of MCS planning and operation coordination, considering the influence of planning and operation in the system’s life cycle, is studied in this paper. Consequently, the research on the collaborative optimization strategy of MCS construction and operation was carried out based on the bi-level multi-objective optimization theory in this paper. Considering the mutual restraint and correlation between system construction and operation in practical engineering, a bi-level optimization model for collaborative optimization of MCS construction and operation was constructed. To solve the model effectively, the existing non-dominated sorting genetic algorithm III (NSGA-III) was improved by the authors on the basis of previous research, which could enhance the global search ability and convergence speed of the algorithm. To effectively improve and strengthen the reliability of energy supply, and increase the comprehensive energy utilization of the system, the effects of carbon transaction cost and renewable energy penetration were considered in the optimization process. Based on an engineering example, the bi-level model was solved and analyzed. It should be noted that the optimization results of the model were verified to be applicable and effective by comparison with the single-level multi-objective programming optimization. The findings of this paper could provide theoretical reference and practical guidance for the planning and operation of MCSs, making them significant for social application.
Power Bus Management Techniques for Space Missions in Low Earth Orbit
Authors: Schirone Luigi , Ferrara Matteo , Granello Pierpaolo , Paris Claudio , Pellitteri Filippo
Published: November 2021

In space vehicles, the typical configurations for the Solar Array Power Regulators in charge of managing power transfer from the solar array to the power bus are quite different from the corresponding devices in use for terrestrial applications. A thorough analysis is reported for the most popular approaches, namely Sequential Switching Shunt Regulation and parallel-input Pulse Width Modulated converters with Maximum Power Point Tracking. Their performance is compared with reference to a typical mission in low Earth orbit, highlighting the respective strengths and weaknesses. A novel solar array managing technique, the Sequential Maximum Power Tracking, is also introduced in the trade-off and was demonstrated able to boost energy harvesting, especially in the presence of mismatching in the solar array. It also can achieve top levels of reliability using a rather simple control hardware. Its operation was verified both by a Matlab–Simulink model and by an experimental breadboard.
Sustainable Mobility and the Smart City: A Vision of the City of the Future: The Case Study of Cracow (Poland)
Authors: Bielińska-Dusza Edyta , Hamerska Monika , Żak Agnieszka
Published: November 2021

The vision of the smart city is inextricably linked with the concepts of intelligent transport, sustainable mobility and managerial decision making. Cities of the future not only entail the use of new technology, but also increasingly the interpenetration of technological and social aspects, with the simultaneous involvement of urban space users in the creation of such technologies. This provides an opportunity to introduce desired changes and create a more balanced space with a higher quality of life and improved energy efficiency. The article discusses the concepts of sustainable development and sustainable mobility with a particular emphasis on issues related to the smart city. The authors reviewed the various smart city solutions that have been implemented in the field of urban transport in Cracow, whose authorities have taken steps over the last few years to make the city smarter and more modern. The aim of the research was to assess the contribution made by smart city solutions to improving the attractiveness and reliability of public transport in Poland’s second-largest city. The undoubted added value of this analysis is the application of the Structural Equation Modeling (SEM) method to evaluate the implemented solutions. It should be pointed out that such an analysis constitutes a new approach in this area. Until now, these models have been used to assess consumer behavior. The results showed that some of the implemented intelligent solutions increase the attractiveness of public transport in Cracow, but this does not square with users’ assessment of reliability. According to users, ecological solutions have no impact on the attractiveness of public transport. Nor do conveniences such as bus lanes, giving priority to public transport vehicles at intersections, and adjusting traffic light regulation to traffic volume, have a positive impact on perceptions of public transport as a reliable means of getting around the city. The results may be of particular importance for the city’s authorities and other stakeholders engaged in strategic activities and the building of a city of the future.
Macroeconomic Factors Influencing Public Policy Strategies for Blue and Green Hydrogen
Authors: Fazioli Roberto , Pantaleone Francesca
Published: November 2021

The aim of this paper is to analyze the factors affecting hydrogen and Carbon Capture and Storage Technologies (“CCS”) policies, taking into consideration Fossil Fuel Consumption, Oil Reserves, the Debt/GDP Ratio, the Trilemma Index and other variables with respect to OECD countries. STATA 17 was used for the analysis. The results confirm the hypothesis that countries with high fossil fuel consumption and oil reserves are investing in blue hydrogen and CCS towards a “zero-carbon-emission” perspective. Moreover, countries with a good Debt/GDP ratio act most favorably to green policies by raising their Public Debt, because Foreign Direct Investments are negatively correlated with those kinds of policies. Future research should exploit Green Finance policy decision criteria on green and blue hydrogen.