In this paper, an analysis of noise and vibration of a synchronous reluctance machine for EV applications is performed. The analyzed machine was designed for electric vehicle application. The noise and vibration of a synchronous reluctance machine were first estimated during simulations; next, the obtained results were validated during laboratory tests. The analyzed model of the machine was simplified and included only stator core as it was assumed to be the main source of the machine vibration and generated noise. To simulate the noise and vibration of the machine, multiphysics modeling of the machine was performed. Laboratory tests proved the correctness of performed simulations. The obtained results allowed us to investigate the influence of the machine’s operating point on the generated noise and vibration. The frequency of the magnetic radial forces were proven to be the dominant factor in noise generation. The influence of the load and current angle on the machine’s noise and vib... [more]

Spectral selective absorption film (SSAF), a solar control film, has a special energy-saving mechanism. In the previous studies of SSAF coated glazing systems, thermal parameters (global thermal transmittance (U) and solar heat gain coefficient (SHGC)) calculated by traditional algorithms were not verified. In order to evaluate the energy-saving effect of SSAF coated glazing systems accurately, U and the SHGC were calibrated and then used for energy consumption simulation. Firstly, the simulation models of the heat transfer process of SSAF coated glazing systems were established by COMSOL Multiphysics, considering simplified linear attenuation of radiative transfer. After being validated, the simulation models were used for the calibration of U and SHGC by the Multiple Linear Regression (MLR) model. As a result, the calibration coefficients of U and SHGC are 1.126 and 1.689, respectively. Secondly, the thermal parameters of SSAF coated glazing systems calibrated by the calibration coef... [more]

Electricity theft is one of the challenging problems in smart grids. The power utilities around the globe face huge economic loss due to ET. The traditional electricity theft detection (ETD) models confront several challenges, such as highly imbalance distribution of electricity consumption data, curse of dimensionality and inevitable effects of non-malicious factors. To cope with the aforementioned concerns, this paper presents a novel ETD strategy for smart grids based on theft attacks, long short-term memory (LSTM) and gated recurrent unit (GRU) called TLGRU. It includes three subunits: (1) synthetic theft attacks based data balancing, (2) LSTM based feature extraction, and (3) GRU based theft classification. GRU is used for drift identification. It stores and extracts the long-term dependency in the power consumption data. It is beneficial for drift identification. In this way, a minimum false positive rate (FPR) is obtained. Moreover, dropout regularization and Adam optimizer are... [more]

Ultra-high-frequency (UHF) partial discharge (PD) monitoring is gaining popularity because of its advantages over electrical methods for onsite/online applications. One such advantage is the possibility of three-dimensional PD source localization. However, it is necessary to understand the signal propagation and attenuation characteristics in transformers to improve localization. Since transformers are available in a wide range of ratings and geometric sizes, it is necessary to ascertain the similarities and differences in UHF signal characteristics across the different designs. Therefore, in this contribution, the signal attenuation and propagation characteristics of two 300 MVA transformers are analyzed and compared based on experiments. The two transformers have the same rating but different internal structures. It should be noted that the oil is drained out of the transformers for these tests. Additionally, a simulation model of one of the transformers is built and validated based... [more]

High-temperature fuel cells are a promising technology due to their high energy efficiency and low environmental impacts compared to conventional engines. Nevertheless, they have a limited lifetime which reduces the use to a few application fields. Among them, Solid Oxide Fuel Cells (SOFCs) have had a recent development at the industrial level in two possible configurations: anode- and electrolyte-supported design. Considering the impossibility to experimentally distinguish the effects of every degradation mechanism on global cell performance, each layer should be tested singularly through ex situ tests and then assembled into a virgin cell to evaluate its role on the whole system by in situ tests. However, this procedure results as quite complex, and some further microstructural changes could occur during cell sintering. In order to overcome these constraints, the proposed approach paired ex situ experimental observations on a single element with modelling results on global SOFC. As a... [more]

Since the Paris Agreement in 2016, the goals of limiting climate change and moving toward climate resilience stand. With a share of about 80% of global CO2 emissions, the energy sector is an essential driver for these goals. A shift to low-carbon energy production and a decentralized system for more efficient energy transmission distribution is necessary. In this paper, we present our work on Modelling of Power Exchanges, Algorithms for Local Energy Market (LEM), Competitiveness of Combined Heat and Power Plant (CHP) and Energy Feedback Devices. The study was conducted considering technical, economic, social and regulatory framework. For easy integration into energy simulations or a district energy management system (DEMS), a model for power exchanges was created that allows flexible input or deterministic price patterns. The algorithm handles the clearing of an LEM by a district aggregator using limit orders with the goal of increasing the share of locally consumed electricity using e... [more]

With the continuous penetration and development of renewable energy power generation, distributed grids and microgrids are becoming increasingly important in power systems. In the distribution networks and microgrids, the grid impedance is comparatively large and cannot be ignored. Usually, the parallel compensation is used to improve the grid quality. In these three-phase four-wire power systems, analyzing the impedance characteristics of the grid-connected inverter is vital to carry out the small-signal stability analysis. Thus, it is vital to consider the influence of the zero-sequence component in addition to the positive-sequence component and the negative-sequence component when it comes to analyzing system stability. In this paper, the impedances of three-phase four-wire split capacitor inverter and three-phase four-leg inverter are established. Based on the achieved impedance, the similarities and differences between the impedances of three-phase four-wire split capacitor inver... [more]

The partial transmit sequence (PTS) technique is a fairly suitable scheme to mitigate the high peak-to-average power ratio (PAPR) problem inherent in 5G multicarrier systems, especially considering a high-order QAM modulation design. However, the high computational complexity level and the speed of the convergence for optimizing the phases of the transmitting signal restrict this technique in practical applications. In this paper, a low-complexity frequency-domain-evaluated PTS (F-PTS) based on a spacing multiobjective (SMO) processing algorithm is proposed to reduce the PAPR values. The PAPR performance are accurately predicted in terms of modifying relative dispersion in the frequency domain. As a result, the complexity of searching the optimal phase factors and IFFT computing is simplified. Moreover, a frequency-domain- and time-domain-evaluating PTS (FTD-PTS) is employed to search the optimal solution with a reasonable complexity. Simulation results verify that the operation rate o... [more]

Evaporative cooling is a promising concept to improve proton exchange membrane fuel cells. While the particular concept based on gas diffusion layers (GDLs) modified with hydrophilic lines (HPILs) has recently been demonstrated, there is a lack in the understanding of the mass and heat transport processes. We have developed a 3-D, non-isothermal, macro-homogeneous numerical model focusing on one interface between a HPIL and an anode gas flow channel (AGFC). In the base case model, water evaporates within a thin film adjacent to the interfaces of the HPIL with the AGFC and with the hydrophobic anode GDL. The largest part of the generated water vapor leaves the cell via the AGFC. The transport to the cathode side is shown to be partly limited by the ab-/desorption into/from the membrane. The cooling due to the latent heat has a strong effect on the local evaporation rate. An increase of the mass transfer coefficient for evaporation leads to a transport limited regime inside the MEA while... [more]

Targeting ultimate fidelity reactor physics calculations the Dynamic Monte Carlo (DMC) method simulates reactor transients without resorting to static or quasistatic approximations. Due to the capability to harness the computing power of Graphics Processing Units, the GUARDYAN (GpU Assisted Reactor DYnamic ANalysis) code has been recently upscaled to perform pin-by-pin simulations of power plant scale systems as demonstrated in this paper. A recent rod drop experiment at a VVER-440/213 (vodo-vodyanoi enyergeticheskiy reaktor) type power plant at Paks NPP, Hungary, was considered and signals of ex-core detectors placed at three different positions were simulated successfully by GUARDYAN taking realistic fuel loading, including burn-up data into account. Results were also compared to the time-dependent Paks NPP in-house nodal diffusion code VERETINA (VERONA: VVER Online Analysis and RETINA: Reactor Thermo-hydraulics Interactive). Analysis is given of the temporal and spatial variance dis... [more]

Despite the huge current challenges in sewage sludge treatment and disposal in China, anaerobic sludge stabilisation (AnSS) is still not a state-of-the-art process in WWTP in the country. However, the potential benefits of anaerobic sludge stabilisation may outweigh the drawbacks. One of these drawbacks is the backload from the sludge liquor that increases the nutrient load in the biological treatment stage. This work shows via computer modelling that not only can the sludge production and disposal costs be significantly reduced, but also that, with sensible automation and operational strategies (e.g., bypass of primary clarifiers, use of a centrate dosing strategy, incorporation of ammonium nitrogen sensors, etc.), the effects of the backload can be counteracted for nitrogen removal, even considering that wastewater in China often has an unfavourable C/N ratio for nitrogen removal. The tested strategies would even improve the overall plant performance in terms of norm compliance, slud... [more]

Usually, data-driven methods require many samples and need to train a specific model for each substation instance. As different substation instances have similar fault features, the number of samples required for model training can be significantly reduced if these features are transferred to the substation instances that lack samples. This paper proposes a fault-line selection (FLS) method based on deep transfer learning for small-current grounded systems to solve the problems of unstable training and low FLS accuracy of data-driven methods in small-sample cases. For this purpose, fine-turning and historical averaging techniques are proposed for use in transfer learning to extract similar fault features from other substation instances and transfer these features to target substation instances that lack samples to improve the accuracy and stability of the model. The results show that the proposed method obtains a much higher FLS accuracy than other methods in small-sample cases; it has... [more]

To improve the thermal comfort in the hall of the Angelo Hospital (Venezia) an analysis was developed by using Computation Fluid Dynamics and considering some configurations for the air-conditioning system and for the solar shading devices. The reference configuration consists of the installation of four fan coils in the area coupled with a 3 m high metal casing used for solar shading. Then, three other solutions are proposed: by increasing the number of fan coils and changing their position, by adding some radiant panels arranged on the walls, and by inserting a physical confinement as a lateral confinement. The study consists of three sections. Firstly, a section in which the study area is modelled through a strong simplification that allows to represent only a slice of the domain but to immediately evaluate the role of the casing. A second section in which the area is completely modelled, and a third section in which a comfort evaluation is carried out. The analysis shows that the m... [more]

External gear pumps are among the most popular fluid power positive displacement pumps; however, they often suffer from excessive flow pulsation transmitted to the downstream circuit. To meet the increasing demand of quiet operation for modern fluid power systems, it is necessary to give a physically sound method of analyzing the operation of a volumetric pump. The analysis of the basic approach used by the majority of researchers for calculating the flow rate of a gear pump by E.M. Yudin is presented. The article presents a new method for analyzing the operation of volumetric pumps. The method is suitable for the pumps whose dynamic characteristics should be considered according to the model of an equivalent source of flow fluctuations by V.P. Shorin. The method is based on wave theory, the method of hydrodynamic analogies and the impedance method, where the pump is considered according to the model in lumped parameters. The method consists in determining the pressure pulsations at th... [more]

Coal is one of the important energy sources for industry. When it is mined, it will cause the destruction of bedrock and surface. However, it is more severe in mining shallow-buried multi coal seams (SBMCS). To better reveal the characteristics of the bedrock and surface damage, we have carried out a theoretical analysis, as well as used numerical simulations and field monitoring methods to study the surface and bedrock damage caused by the mining of SBMCS. The characteristics of bedrock and surface failure structure, settlement, and stress distribution were studied and analyzed. The findings show that the collapsed block, formed by the rupture of the overlying stratum, interacts with the surrounding rock to form large cavities and gaps, and the stress concentration occurs between them. The maximum downward vertical concentration stress is about 9.79 MPa. The mining of the lower coal seam can lead to repeated failure of the upper bedrock and goaf. The settlement of bedrock presents gra... [more]

Multi-skin ventilated facades with integrated building elements that respond to climatic conditions (mechanized openings and automatic shading with intelligent control) present the potential of improving overall annual energy savings by adapting the thermal properties of buildings. This paper presents a literature review on multi-skin adaptive ventilated facades. Additionally, this article presents a literature review on building envelopes that contain inner-air layers. The operation modes of the air layer used in building enclosure structures are classified and summarized and the thermal performance and benefits of climate-adaptive facades are discussed and reviewed. The existing operation modes of the air layer used in building envelopes are summarized, outlined and roughly classified into the following types: the enclosed type, the naturally ventilated type and the mechanically ventilated type. One of the sustainable development trends is the investigation and application of energy-... [more]

The work aimed to solve the problem of determining, validating, and transferring model parameters of flooding using chemical enhanced oil recovery (EOR) from a core experiment to a full-scale hydrodynamic model. For this purpose, a digital hydrodynamic model describing the process of oil displacement by the surfactant and polymer solution on the core is created and the digital model is matched to achieve convergence with the historical data. This approach allows the uncertainties associated with the limited number of experiments to be removed to fully describe the parameters of the chemical surfactant polymer flooding model and form a database that could subsequently be replicated at various field sites, having the composition of reservoir fluids and distribution of rock composition in the core material as the basis. Besides, the digital model allows for verification of physical and chemical properties of surfactants and polymers, values of the adsorption of chemical agents on rocks, a... [more]

The presence of Poland in the European Union obliges the domestic economy and the professional energy sector to improve the condition of the natural environment by reducing the emissions of harmful substances into the environment. One of the substances that have a negative impact on the environment is nitrogen oxides. The results of numerical calculations of flue gas denitrification using the SNCR method in an OP 650 boiler are presented in the paper. The method of verifying the combustion of the numerical model, in terms of measurement and calculations with a zero-dimensional model, is presented. Then, the results of numerical tests of flue gas denitrification using the SNCR method with the use of urea solution injection in a specific temperature window for various nozzle positions are presented. In this paper, three variants of the reagent’s injection into the furnace chamber were carried out, depending on the height of the position of the nozzle. It is shown in this paper that thank... [more]

In this work, performance analysis and comparison of three photovoltaic technologies are carried out in the Louisiana climate. During the calendar year of 2018, the University of Louisiana at Lafayette constructed and commissioned a 1.1 MW solar photovoltaic power plant for researching solar power in southern Louisiana and for partial energy demand of the university. It was one of the largest solar photovoltaic power plants in Louisiana when constructed and receives an annual solar insolation of 4.88 kWh/m2/d at latitude minus five degrees (25°) tilt. The solar power plant has a total of 4142 modules and incorporates three module technologies. Preliminary performance data from the system level are presented. The evaluation of different technologies is based on final yield, performance ratio, and capacity factor for one year from September 2019 to August 2020. An economic analysis is carried out using levelized cost of energy for the three photovoltaic (PV) technologies. Finally, the re... [more]

Gallium nitride high-electron-mobility transistor (GaN HEMT) is a key enabling technology for obtaining high-efficient and compact power electronic systems. At the design stage of a power converter, the proper modelling of the GaN HEMT is essential to benefit from their good features and to account for the limits of the current technology. Circuit models of power MOSFETs have been deeply investigated by academia and industry for a long time. These models are able to emulate the datasheet information, and they are usually provided by device manufacturers as netlists that can be simulated in any kind of SPICE-like software. This paper firstly highlights the similarities and differences between MOSFETs and GaN HEMTs at the datasheet level. According to this analysis, the features of MOSFET circuit models that can be adopted for GaN HEMT modelling are discussed. This task has been accomplished by overviewing the literature on MOSFETs circuit models as well as analysing manufacturers netlis... [more]

The construction sector generates large amounts of heterogeneous and dynamic data characterized by their fragmentation throughout the life cycle of a project. Immediate and accurate access to that data is fundamental to the management, decision-making and analysis by construction owners, supervisors, managers, and technicians involved in the different phases of the project life cycle. However, since construction project data are diverse, dispersed, uncorrelated, and difficult to visualize, a reliable basis for decision-making can rarely be established by the management team. Aiming to bridge this gap, a methodology for data management during building construction by means of Data with BIM and Business Intelligence (BI) analysis tools was developed in this study. This methodology works by extracting data from 3D parametric model and integrating it with a BI tool, through which data are visualized and interrelated with the same database, the BIM model. To demonstrate the applicability of... [more]

Background. Laws that enable a circular economy (CE) are being enacted globally, but reliable standardized and digitized CE data about products is scarce, and many CE platforms have differing exclusive formats. In response to these challenges, the Ministry of The Economy of Luxembourg launched the Circularity Dataset Standardization Initiative to develop a globalized open-source industry standard to allow the exchange of standardized data throughout the supply cycle, based on these objectives: (a) Provide basic product circularity data about products. (b) Improve circularity data sharing efficiency. (c) Encourage improved product circularity performance. A policy objective was to have the International Organization for Standardization (ISO) voted to create a working group. Methods. A state-of-play analysis was performed concurrently with consultations with industry, auditors, data experts, and data aggregation platforms. Results. Problem statements were generated. Based on those, a sol... [more]

Electrical insulation is an integral part of power components. The aging of electrical insulation is an undeniable fact that limits the operational lifetime of power components. Apart from regular aging, abnormal stresses and the development of defects are real threats because of their contribution in accelerating the aging rate and thereby leading to a premature failure of the power components. Over the decades, various studies have been carried out to understand the aging behavior of electrical insulation mainly considering electrical and thermal stresses. Similarly, a number of mathematical (aging) models have been developed based on the theoretical and experimental investigations and evidences. However, a dependable formulation of the models that can provide more practical estimation of the insulation degradation profile has not been achieved yet. This paper presents a comprehensive review of the aging models considering single and multistress conditions. Further, the paper discuss... [more]

Solar energy is prevalent in many applications, therefore, the reliability of solar energy systems has become an important topic for research communities and industry. High reliability and fault-tolerant capability are particularly vital for the solar energy systems that are mission-critical and/or inaccessible to affordable maintenance. In order to enhance the reliability of a grid-tied PV system, a fault-tolerant Photovoltaic (PV) inverter, termed Integrated Fault-Tolerant PV Inverter (IFTPVI), is proposed in this paper. The IFTPVI is based on the Highly Efficient and Reliable Inverter Concept (HERIC) and H5 inverters that are both popular and commercialized transformerless inverters in grid-tied PV applications. The IFTPVI can tolerate both open-circuit (OC) and short-circuit (SC) faults while maintaining the same voltage and current levels. The system description, reliability analysis, simulation in Matlab/Simulink 2018, and experimental results are provided to verify the feasibili... [more]

A 3D stationary CFD study was conducted in our previous work, resulting in a novel reactor design methodology oriented to upgrading biogas through CO2 methanation. To enhance our design methodology incorporating relevant power to gas operational conditions, a novel transient 3D CFD modelling methodology is employed to simulate the effect of relevant dynamic disruptions on the behaviour of a tubular fixed bed reactor for biogas upgrading. Unlike 1D/2D models, this contribution implements a full 3D shell cooled methanation reactor considering real-world operational conditions. The reactor’s behaviour was analysed considering the hot-spot temperature and the outlet CH4 mole fraction as the main performance parameters. The reactor start-up and shutdown times were estimated at 330 s and 130 s, respectively. As expected, inlet feed and temperature disruptions prompted “wrong-way” behaviours. A 30 s H2 feed interruption gave rise to a transient low-temperature hot spot, which dissipated after... [more]