The operation of a water supply system (WSS) is inextricably linked with the possibility of different types of failure. It is very common for these failures to be random in nature. The results of reliability studies carried out in many water supply systems revealed, for example, the possibility of incidental water pollution, power supply issues, failure in machinery, damage to water plants, or natural disasters. As a result of the WSS failure, we deal with a state of threat to safety (TSS) or a state of loss of safety (LSS). Using Markov processes, we developed a failure model of the WSS to determine the possibility that the system may find itself in different states of safety. As a result, a mathematical model using Markov processes has been proposed for each of these distinct states of safety (complete safety state—CSS; threat to safety state—TSS; and loss of safety state—LSS). The proposed approach in the water supply system will limit emergency states by optimizing working and repa... [more]

The present study utilized response surface methodology (RSM) and Bayesian neural network (BNN) to predict the characteristics of a diesel engine powered by a blend of biodiesel and diesel fuel. The biodiesel was produced from waste cooking oil using a biocatalyst synthesized from vegetable waste through the wet impregnation technique. A multilevel central composite design was utilized to predict engine characteristics, including brake thermal efficiency (BTE), nitric oxide (NO), unburned hydrocarbons (UBHC), smoke emissions, heat release rate (HRR), and cylinder peak pressure (CGPP). BNN and the logistic−sigmoid activation function were used to train the experimental data in the artificial neural network (ANN) model, and the errors and correlations of the predicted models were calculated. The study revealed that the biocatalyst was capable of producing a maximum yield of 93% at 55 °C under specific reaction conditions, namely a reaction time of 120 min, a stirrer speed of 900 rpm, a c... [more]

In the present work, direct numerical simulation is employed to investigate the unsteady flow characteristics and energy performance of low-pressure turbines (LPT) by considering the blades aeroelastic vibrations and inflow wakes. The effects of inflow disturbance (0 < φ < 0.91) and reduced blade vibration (0 < f < 250 Hz) on the turbulent flow behavior of LPTs are investigated for the first time. The transient governing equations on the vibrating blades are modelled by the high-order spectral/hp element method. The results revealed that by increasing the inflow disturbances, the separated bubbles tend to shrink, which has a noticeable influence on the pressure in the downstream region. The maximum wake loss value is reduced by 16.4% by increasing the φ from 0.31 to 0.91. The flow separation is majorly affected by inflow wakes and blade vibrations. The results revealed that the maximum pressure coefficient in the separated flow region of the vibrating blade has been increas... [more]

The article discusses the new technique for fracture closure pressure detection using continuous wavelet transform (CWT). The study focuses on calibrating the CWT technique and comparing it with different techniques for closure detection. According to the article, traditional methods for identifying the closure of hydraulic fracturing operations are based on assumptions that can conflict with one another, resulting in greatly varying approximations of closure pressure and duration. To address this issue, the article employs a set of diagnostic fracture injection tests that utilize the Step-Rate Injection Method for Fracture In-Situ Properties tool (SIMFIP). By directly observing wellbore deformation, the SIMFIP tool determines the minimum principal stress, while strain gauges monitor the opening and closing of fractures during multiple tests. The publicly accessible data are used to evaluate the accuracy of the new closure detection technique using CWT. The findings indicate that the C... [more]

The large-scale integration of photovoltaic (PV) power can bring a greatly negative influence on the grid-connected system’s voltage stability. To study the static voltage stability (SVS) of PV grid-connected systems, the traditional SVS index, L-index, was re-examined. It was firstly derived and proved that the PV active output Ppv is proportional to the voltage phase angle of the PV station’s POI (Point of Interconnection), based on a simplified two-node system integrated with a PV station operating in PV (active power—voltage) mode or PQ (active power—reactive power) mode with unit power factor. Then a novel voltage stability sensitivity index LPAS-index was proposed that takes the derivative of the L-index with respect to the POI’s voltage phase angle, so as to reflect the influence degree of Ppv on the SVS of each load node. A SVS zoning analysis method for the PV grid-connected system was designed according to the classification results of load nodes based on the proposed LPAS-in... [more]

Hydrogen (H2) energy is an ideal non-polluting renewable energy and can achieve long-term energy storage, which can effectively regulate the intermittence and seasonal fluctuation of solar energy. Solid oxide fuel cells (SOFC) can generate electricity from H2 with only outputs of water, waste heat, and almost no pollution. To solve the power generation instability and discontinuity of solar photovoltaic (PV) systems, a hybrid PV-SOFC power generation system has become one feasible solution. The “digital twin”, which integrates physical systems and information technology, offers a new view to deal with the current problems encountered during smart energy development. In particular, an accurate and reliable system model is the basis for achieving this vision. As core components, the reliable modelling of the PV cells and fuel cells (FCs) is crucial to the whole hybrid PV-SOFC power generation system’s optimal and reliable operation, which is based on the reliable identification of unknow... [more]

Modern power engineering is struggling with various problems that have not been observed before or have occurred very rarely. The main cause of these problems results from the increasing number of connected distributed electricity sources, mainly renewable energy sources (RESs). Therefore, energy generation is becoming more and more diverse, both in terms of technology and location. Grids that have so far worked as receiving networks change their original function and become generation networks. The directions of power flow have changed. In the case of distribution networks, this is manifested by power flows towards transformer stations and further to the network with a higher voltage level. As a result of a large number of RESs, their total share in the total generation increases. This has a significant impact on various aspects of the operation of the power system. Voltage profiles, branch loads, power flows and directions of power flows between areas change. As a result of the rando... [more]

The frequency diversion in hybrid power systems is a major challenge due to the unpredictable power generation of renewable energies. An automatic generation controller (AGC) system is utilised in a hybrid power system to correct the frequency when the power generation of renewable energies and consumers’ load demand are changing rapidly. While a neural network (NN) model based on a back-propagation (BP) training algorithm is commonly used to design AGCs, it requires a complicated training methodology and a longer processing time. In this paper, a bacterial foraging algorithm (BF) was employed to enhance the learning of the NN model for AGCs based on adequately identifying the initial weights of the model. Hence, the training error of the NN model was addressed quickly when it was compared with the traditional NN model, resulting in an accurate signal prediction. To assess the proposed AGC, a power system with a photovoltaic (PV) generation test model was designed using MATLAB/Simulink... [more]

The results of selected volatile organic compounds (benzene, n-hexane, isopropanol, and formic acid) catalytic oxidation are presented on Fe2O3 cenospheres in the fluidised bed reactor. The core−shell Fe2O3-cenosphere catalyst was developed by applying an Fe layer on cenospheres by FB-MO-CVD (fluidised bed, metal−organic chemical vapor deposition) and following Fe layer oxidation. The efficiency of the decomposition of VOCs was tested in the range of 200 to 500 °C, using the method based on infrared spectroscopy (FTIR). The research was focused especially on the analysis of incomplete combustion products, such as CO and oxygen compounds. During the oxidation of isopropanol and n-hexane, in addition to carbon monoxide, species such as acetone, formaldehyde, and acetaldehyde were also detected. The oxidation of formic acid proceeded with only a slight emission of carbon monoxide, unexpectedly the oxidation of benzene proceeded in a similar way, and no other products of the incomplete oxi... [more]

This work presents a new trapezoidal-rule-based variation of the perturb and observe algorithm to track the point with maximum power for a wind energy conversion system. The algorithm works in three steps. In the first step, the trapezoidal-rule-based division of the power curve into trapezoids of equal width is carried out. In the second step, areas of the adjacent trapezoids are compared to identify the trapezoid with the largest area. In the third step, the conventional perturb and observe algorithm is employed in the trapezoid having the largest area to capture the point of maximum power. The algorithm is simulated in MATLAB/SIMULINK to check the efficacy in capturing the maximum power. The simulation results suggest that the proposed method performs well under fluctuating wind conditions with improved yielded power. An effort to achieve simplicity for implementation and effectively track the maximum power point is made and presented.

To effectively improve the dust reduction rate of fine dust and prevent the occurrence of secondary dust, surfactant-charged water mist dust reduction technology is proposed. First, the water mist induction-charged atomization mechanism was perfected by an induction-charged spray experiment and the optimal atomization-charged voltage was determined to be 10 kV. Second, by surface tension and spray experiments on AEO-9-charged solutions, the lower the surface tension and viscosity of the solution, the better the atomization effect; the best atomization solution was 10 kV and 0.02% AEO-9. Finally, according to an electrostatic adsorption experiment, it was identified that there was an electrostatic interaction between coal dust and charged droplets. The contact angle experiment showed that the contact angle of the AEO-9 droplets decreased by 68.44% compared with water after 3 s of contact with coal dust. The wetting effect of bituminous coal was significantly improved by adding AEO-9 to... [more]

This paper proposes a cooperative (Cx) coil design for the series-series-series (S-S-S)-compensated wireless power transfer (WPT) system to improve the horizontal misalignment tolerance and the system efficiency. The Cx coil is formed by four series-connected rectangular coils and integrated into the transmitter (Tx) coil to provide a coupling variation opposite to that of the Tx coil, obtaining the constant equivalent mutual inductance (MI). The design overcomes the problem that the decoupling-designed intermediate coil does not participate in system energy delivery under the well-aligned condition. A misalignment tolerant design with the zero-phase-angle (ZPA) input and load-independent constant current (CC) output conditions is presented based on the Delta-Wye network transform and linear regression. A comparison between the proposed design and a two-coil system using a similar amount of copper, i.e., the Tx coil plus the Cx coil, is made. Finally, a 218.08 W/85.85 kHz scaled-down p... [more]

Standard medium-voltage converters are operated at low switching frequencies using bulky passive components. One concept to change this involves the quasi-two-level operation (Q2O) of multilevel converters that use fast-switching semiconductors to minimize the need for passive components. The flying capacitor converter (FCC) uses SiC semiconductors and operates with Q2O to minimize passive components. In this paper, two different quasi-two-level algorithms are analyzed. A medium-voltage prototype was built and low-voltage and medium-voltage measurements were used to validate the concept. A particular focus is on the overvoltage, the dv/dt behavior of the converter, as well as the dynamic behavior.

This study aims to present the processes and mechanisms of creating smart city ecosystems by examining the complex strategic choices and interactions among stakeholders operating at different levels of governance and engagement. Based on the literature review and in-depth analyses of a case study (Lublin, Eastern Poland), we demonstrate that the implementation of tailored strategic thinking using adaptation to global trends, exploitation of development potentials and niches, and stakeholders’ involvement allows for coordination and mobilization of development processes leading to the creation of effective smart city ecosystems. In line with the defined smart city challenges, with the application of a three-stage research program, we create an implementable Smart City Ecosystem Model (SCEM). The contributions of the study are as follows: (1) it provides new insights into smart governance, leadership in creating a sustainable and human smart city; (2) it analyzes strategic choices in the... [more]

Predicting the spatial distribution of braided fluvial facies reservoirs is of paramount significance for oil and gas exploration and development. Given that seismic materials enjoy an advantage in dense spatial sampling, many methods have been proposed to predict the reservoir distribution based on different seismic attributes. Nevertheless, different seismic attributes have different sensitivities to the reservoirs, and informational redundancy between them makes it difficult to combine them effectively. Regarding reservoir modeling, multi-point geostatistics represents the distribution characteristics of the braided fluvial facies reservoirs effectively. Despite this, it is very difficult to build high-quality training images. Hence, this paper proposes a three-step method of predicting braided fluvial facies reservoirs based on probability fusion and multi-point geostatistics. Firstly, similar statistical data of modern sedimentation and field paleo-outcrops were processed under th... [more]

This study looks at the short- and long-term effects of fossil fuels, renewable energy, and nuclear energy on CO2 emissions in the South Asian Association for Regional Cooperation (SAARC) countries from 1982 to 2021. We assess the impacts of SAARC’s current and anticipated use of nuclear, fossil, and alternative energies by testing the environmental Kuznets curve (EKC) hypothesis. The study applied the second-generation unit root test, cointegration test, and the newly introduced AMG technique to handle the presence of cross-sectional dependence. The results indicate that EKC does not hold in SAARC, and a U-shaped quadratic link exists between GDP and environmental pollution. The findings also reveal that the environmental pollution in the SAARC is caused by fossil fuel, whereas using renewable (REN) and nuclear energy can cut long-term pollution. While renewable energy is critical to minimizing environmental deterioration in SAARC, empirical findings also show that more than rising na... [more]

Thermal design and the choice of turbulence models are crucial for motors. In this project, the geometrical model of the vertical shielding induction motor for a small nuclear main pump was established by SolidWorks software and the finite volume method was adopted to investigate the temperature of the motor, especially the temperatures of bearings lubricated water. To make the numerical simulation of flow and heat transfer in the rotating clearance of the shielding induction motor more accurate, the effects of four types of different two equation turbulence models on the temperature field of the shielding induction motor were studied. The results showed that different choices of turbulence models had little effect on the temperature of the winding insulation but influenced the temperature of the lower guide bearing lubricating water and the secondary cooling water outlet. The SST k-ω model showed the lowest relative error result of the temperature of the winding insulation and the bea... [more]

In this paper, the results of numerical investigations on heat transfer in a multi-vane expander (MVE) are reported. MVEs are very interesting for various technological applications because of their advantages (such as, for example, low gas flow capacity and a low expansion ratio). According to a literature study, the heat exchange mechanisms occurring in these machines have not yet undergone in-depth analysis. As a result, there have been very few experimental or modeling results connected to these unquestionably significant processes from both a scientific and practical perspective. Despite the fact that several analytical models have been developed for these phenomena, there is no numerical model dedicated to an MVE. This model was developed by the authors and presented in this paper together with modeling results. Numerical simulations were executed in the ANSYS CFX and focused on defining the expander heat transfer coefficients under various flow circumstances. The results showed... [more]

This paper investigates the economic consequences of a haulage company replacing its line-haul diesel trucks with battery-electric ones. It also examines how large truck batteries should be, whether the haulage companies should use public fast chargers to complement their own, and whether public fast chargers have the potential to be profitable. The potential extra cost of losing payload capacity is estimated and there is an investigation of whether a charge-point operator should meet the peak demand for charging. The case under analysis is designed to represent a typical line-haul service between terminals in a major logistics system, with the finding that, in this case, a transition to battery-electric trucks seems cost effective for the company. Moreover, it is advisable for the company to use public fast chargers and these will likely become profitable given that the utilisation factor of the investigated public fast chargers may realistically exceed 20%.

Electrification is considered an optimal long-term solution for the decarbonization of the transport sector. However, in the medium period, propulsion systems will continue to dominate urban mobility, thus requiring the shift from fossil fuels toward low carbon fuels. In this regard, the request from the EU to achieve carbon neutrality by 2050 is encouraging the use of innovative fuels and powertrains. Alcohols such as ethanol and methanol are particularly suitable for spark ignition engines. This paper investigates the effect of ethanol/methanol blends on the performance and emissions of a turbocharged direct injection spark ignition engine running on the worldwide harmonized light vehicles test cycle. Three blends were considered, consisting of 10% v/v ethanol (E10), 25% v/v ethanol (E25) and 5% v/v ethanol with 15% v/v methanol (E5M15). Gaseous and particle emissions were measured at the exhaust. The main novelty of the study regards the investigation of the behavior of alcohol blen... [more]

Incorporating photovoltaic (PV) inverters in power distribution systems via static synchronous compensators (PV-STATCOM) during the nighttime has lately been described as a solution to improve network performance. Hunter prey optimization (HPO) is introduced in this study for efficient PV-STATCOM device allocation in distribution systems. HPO generates numerous scenarios for how animals could act when hunting, some of which have been expanded into stochastic optimization. The PV-STATCOM device allocation issue in distribution networks is structured to simultaneously minimize the electrical energy losses and improve the voltage profile while accounting for variable 24 h loadings. The impacts of varying the number of installed PV-STATCOM devices are investigated in distribution systems. It is tested on two IEEE 33-node and 69-node distribution networks. The effectiveness of the proposed HPO is demonstrated in comparison to the differential evolution (DE) algorithm, particle swarm optimiz... [more]

In this article, we seek to present the synthesis of the global ethanol market in the United States (US) and Brazil by using caloric equivalence to empirically characterize the elasticity of supply and demand. We also seek to evaluate the relationship between world ethanol production and prices of agricultural commodities (wheat, rice, corn, soybeans and sugar) from 1981 to 2016 using climate-induced yield shocks as instrumental variables. The main results for the world market indicate that the production and demand for ethanol respond elastically to changes in commodity prices. The world ethanol production has no significant relationship with food prices. However, evaluation of the ethanol market and its interaction with the agricultural commodities market confirms the hypothesis that Brazilian ethanol is weakly related to the price of food.

The advent of distributed renewable energy sources (DRESs) has led to the progressive transformation of traditional distribution networks to active components of the power system. This transformation, however, may jeopardize the reliable grid operation due to the advent of new technical problems, such as network overloading, over-/under-voltage events, abnormal frequency deviation and dynamic instability. In this challenging scenery, the installation of a modern measuring infrastructure has created new sources of data and information that facilitate the provision of ancillary services (ASs) via measurement-based analysis. The ACTIVATE (ancillary services in active distribution networks based on monitoring and control techniques) project aims to design innovative AS solutions for power system operators. These solutions aim to tackle the technical issues emerged by the ever-increasing DRES penetration and their volatile nature. In this context, in ACTIVATE, a holistic system is proposed... [more]

overcharging can occur due to capacity and internal resistance variations among cells or battery management system failure that both accelerate battery degradation, which is more likely at low temperatures because of the large polarization effect. This study experimentally investigated the battery degradation characteristics during charging of LiFePO4 (LFP)/Graphite batteries at voltages of 3.65−4.8 V and Li(Ni0.5Co0.2Mn0.3)O2 (NCM)/Graphite batteries at 4.2−4.8 V at −10 °C with currents of 0.2−1 C. The results showed that the LFP cell capacities decreased linearly with an increasing number of cycles, while the NCM cell capacities faded in three trends with an increasing number of cycles under different conditions with linear fading, accelerated fading, and decelerated fading. The incremental capacity curves and differential voltage curves showed that the LFP cell degradation was mainly caused by the loss of lithium inventory (LLI), with some effect from the loss of active material (LA... [more]

To further the development of low-enriched uranium fuels, precedence has been placed on delivering the same amount of power while lowering the fuel temperature and radial temperature gradient. To address this, modeling efforts have resulted in a novel design featuring conductive fins of varying thermal conductivities and geometries inserted into the fuel matrix. These conductive inserts were not allowed to exceed 6% of the original fuel volume. This constraint was imposed due to other designs displacing 10% of fuel volume. A parametric study was performed that consisted of 2.56 million BISON simulations involving varying fin characteristics (i.e., fin thermal conductivity, number, and geometry) to determine the optimal geometric configuration for a desired amount of fuel volume displaced. The results from this study show that the thickness and length of each fin affect the fuel temperature and temperature gradient more than varying the number and thermal conductivity of the fins. The p... [more]