The arrangement of obstacles can significantly impact the deflagration behavior of combustible gases. In the actual pipeline accident site, liquefied petroleum gas (LPG) and other gases often show non-uniform distribution after leakage owing to diffusion and gravity, and the deflagration mechanism is also more complex. In this paper, based on the non-uniform distribution of combustible gases, the flame behavior and overpressure characteristics of LPG−air combustible gas deflagration are carried out by a combination of experiments and numerical simulations with obstacles arranged in increasing and decreasing blockage height. The results show that in the increasing blockage height arrangement, the flame forms a “straw hat” cavity, finally forming an elliptical region. In the decreasing blockage height arrangement, the flame appears as a “ribbon-shaped” narrow, blank area, which gradually becomes longer with time. By observing the overpressure and the structure of flame propagation in the... [more]

This proposal evaluates the energy potential of agricultural residues of Zea mays from an indigenous community in Mexico. The study consists of four stages: (a) evaluation of residue production in all community farming areas (b) morphological and physicochemical characterization, using scanning electron microscopy (SEM), as well as infrared spectroscopy (FTIR) and Raman (c) the proximal and functional evaluation of the residues, through fiber analysis, determination of fixed carbon, humidity, estimation of calorific value, ash microanalysis and elemental analysis, and (d) evaluation of energy potential and multicriteria analysis. The results show that Z. mays residues have initial moisture values of less than 10%, ash content below 20%, fixed carbon around 14% and a calorific value of 17.6 MJ/kg associated with polymeric compounds and carbohydrates, as well as a percentage of extractable compounds of the order of 40%. The production of these residues on the 249 hectares (ha) of cultiva... [more]

Better understanding of how internal short circuit causes thermal runaway will benefit the engineering for safer lithium-ion batteries. In this study, three-dimensional (3D) numerical simulations of a 20Ah lithium battery under internal shorting condition are performed. The effects of internal short circuit area, resistance, penetration depth, convective heat transfer coefficient and internal short circuit position, on the thermal runaway are investigated with the simulations in this work. This study demonstrates that the average cell temperature is only weakly affected by the internal short circuit area, penetration depth, and position. On the other hand, the internal short circuit resistance and the convective heat transfer coefficient have large impacts on the thermal runaway propagation in the lithium-ion battery. A high convective heat transfer coefficient can effectively suppress the thermal runaway propagation. However, such a high convective heat transfer coefficient is hard to... [more]

The article is devoted to the problem of proton-exchange membrane fuel cells (PEMFCs) integration into power supply systems. A hybrid energy complex (HEC) based on PEMFCs and lithium iron phosphate batteries can be used as a reliable energy source. It is necessary to properly determine the PEMFC characteristics in order to develop a PEMFC-based HEC prototype and its control algorithms. This paper presents a 1 kW PEMFC’s test results in steady and dynamic modes. The dependences of the average hydrogen consumption per 1 min, the volume of hydrogen for the generation of 1 kWh, the PEMFC efficiency on the load current were obtained and an analysis of these dependences for steady operation modes was performed. A range of load changes beyond which the efficiency of the PEMFC significantly decreased and it was recommended to switch to the joint operation of the PEMFCs and batteries (or only batteries) was established. Diagrams of the PEMFC output voltage during the dynamic changes in loads ar... [more]

Injectability of the polymer solution is a very important factor that determines the effectiveness of polymer flooding for enhanced oil recovery. Here, the medium and low permeability oil reservoir was taken as a research object, and effects of relative molecular weight, concentration and core permeability on the flow and injection performance of a partially hydrolyzed polyacrylamide (HPAM) solution with and without anionic-nonionic surfactant (ANS) were studied by indoor outcrop core physical model experiments. It was found that the influence of HPAM concentration on the flow performance was related to the core permeability. When the core permeability was lower than 59 mD, the resistance factor and residual resistance factor of HPAM increased with increasing the concentration. High molecular weight and low core permeability were not conducive to the injectability of HPAM solutions. The addition of ANS was beneficial in enhancing the injectability of HPAM solution by reducing the criti... [more]

To date, the world has accumulated a large amount of long-lived radioactive materials that need to be disposed of or reprocessed. Such materials include nuclear legacy objects containing 226Ra, which is an important material for obtaining a wide range of isotopes for nuclear medicine via irradiation in reactors, cyclotrons, and electron accelerators. For the selective recovery of 226Ra from waste materials, crown-ether (CE) 18-crown-6 (18C6) or its derivatives can be used, which, however, have not been widely studied for these purposes. In our work, the key property of 18C6 and its derivatives, the phase distribution, was studied using tritium labeling. The possibility of introducing a tritium label into CEs molecules using thermal activation of tritium has been demonstrated; a high specific activity of the obtained compounds was achieved (from 18 to 108 TBq/mol). Methods for chromatographic purification of the studied CEs were developed. The distribution of 18C6 and its derivatives be... [more]

Experimental and computer investigations were conducted into long-duration impulse current distribution in the lightning protection system, supplying network, and electrical installation of a test house that was equipped with household appliances. Long-duration impulse currents simulating lightning continuing currents were injected from the unique current generator into the test object. The current distributions in the elements of the test object were measured using current shunts, coaxial cables, and digital oscilloscopes, then they were modeled using the ATP-EMTP software package. The obtained results show a quite good agreement between the measured and computed current waveforms. The relationships between the values of currents at different points of the conductive installation are similar, as reported in previous studies on the fast-changing lightning return stroke component distribution, although the efficiency of the lightning protection system (LPS) is a few percent better for t... [more]

Liquid fuel nuclear reactors offer innovative possibilities in terms of nuclear reactor designs and passive safety systems. Molten Salts Reactors (MSRs) with a fast spectrum are a particular type of these reactors using liquid fuel. MSFRs often involve large open cavities in their core in which the liquid fuel circulates at a high speed to transport the heat generated by the nuclear reactions into the heat exchangers. This high-speed flow yields a turbulent field with large Reynolds numbers in the reactor core. Since the nuclear power, the neutron precursor’s transport and the thermal exchanges are strongly coupled in the MSFR’s core cavity, having accurate turbulent models for the liquid fuel flow is necessary to avoid introducing significant errors in the numerical simulations of these reactors. Nonetheless, high-accuracy simulations of the turbulent flow field in the reactor cavity of these reactors are usually prohibitively expensive in terms of computational resources, especially... [more]

Non-Intrusive Load Monitoring (NILM) is an effective energy consumption analysis technology, which just requires voltage and current signals on the user bus. This non-invasive monitoring approach can clarify the working state of multiple loads in the building with fewer sensing devices, thus reducing the cost of energy consumption monitoring. In this paper, an NILM method combining adaptive Recurrence Plot (RP) feature extraction and deep-learning-based image recognition is proposed. Firstly, the time-series signal of current is transformed into a threshold-free RP in phase space to obtain the image features. The Euclidean norm in threshold-free RP is scaled exponentially according to the voltage and current correlation to reflect the working characteristics of different loads adaptively. Afterwards, the obtained adaptive RP features can be mapped into images using the corresponding pixel value. In the load identification stage, an advanced computer vision deep network, Hierarchical Vi... [more]

Flexible DC distribution networks have a strong capacity for new energy consumption and have received extensive attention from scholars in recent years, but fault location for DC distribution lines is a difficult task. To solve this problem, we propose using a comprehensive grey correlation degree analysis to analyze the similarity of aerial mode traveling differential current waveforms at the first and last ends of a DC line, thus achieving fault location by obtaining the optimal time shift. Additionally, we built a six-terminal flexible DC distribution network model in Matlab/Simulink for simulation and validation, showing that the method can complete the rapid and accurate location of all types of faults on a DC line, and that it possesses an anti-transition resistance capability, making it suitable and highly reliable for cases of low sampling frequency.

The presented study describes proprietary calculation methods that simulate the process of storing nitrogen dioxide elevation in a catalytic LNT reactor. The first section’s points of reference are the achievements of the article’s authors and the possibility of modeling NO2 adsorption processes in LNT reactors. The rest of the article presents model calculations (proposed by the authors) of the course of the NO2 storage process in LNT reactors. It considers one in its transition period, affecting the improvement and duration of the adsorption process. The conclusion presents selected results of simulation calculations obtained with the help of the equations’ authors and an evaluation of the results. A review of theoretical considerations is consistent with the experimental data, suggesting that the proposed computational solution may be used in future analytical validity assessments of LNT reactor tools under operating conditions.

The paper deals with a simplified approach to evaluate the frequency of damage of low voltage apparatus powered by a in housing HV/LV transformer against overvoltages due to nearby lightning flashes (source of damage S4 according to IEC 62,305 standard). The approach is based on computer simulations with validated models according to the current state of the art. The paper evaluates: the overvoltages stressing the HV/LV transformer due to lightning-induced over-voltages on the supplying HV overhead line; the voltage transferred to low voltage circuit through the power transformer and the influence of the transformer characteristics and of the LV circuits feeding the apparatus; the influence of the characteristics and the number of LV circuits on the frequency of damage of the apparatus. The different contributions to the voltage at the apparatus terminals, namely, the voltage transferred by the HV/LV transformer and the voltage induced by lightning current in the circuit downstream the... [more]

Biodiesel is considered valuable to reduce dependency on petrofuels. This work aimed to synthesize biodiesel from Silybum marianum using synthesized ZnO nanoparticles as a catalyst. The synthesized ZnO nanoparticles were examined by scanning electron microscopy and X-ray diffraction for confirmation. The synthesized biodiesel was confirmed by ASTM D-6751, H and C-NMR, GC-MS, and FT-IR spectroscopy. The optimum biodiesel yield of 91% was obtained with an oil-to-methanol ratio of 1:24, 15 mg of catalyst concentration, 60 °C temperature, and 45 min of reaction time. Fuel properties were determined according to the ASTM-defined methods and found within the defined limits of ASTM D-6751. and showed characteristic peaks at 3.667 ppm, 2.000−2.060 ppm, 0.858−0.918 ppm, 5.288−5.407 ppm, 24.93−34.22 ppm, 172.71, 173.12, 130.16 ppm, and 128.14 ppm, respectively, which confirm biodiesel synthesis. The FAMEs composition of biodiesel was determined by GC-MS, which recognized 19 peaks for different t... [more]

With the proliferation of e-commerce, the field of last-mile logistics has grown increasingly, highlighting the need to manage the environmental consequences of this phenomenon, especially to achieve decarbonization targets for cities and to improve citizens’ quality of life. Within this framework, the authors carried out a last-mile logistics life cycle assessment, to analyse and compare different logistics vehicle options performing the same service in an urban context: an electric four-wheel cargo bike, an electric van, a plug-in hybrid van, and a diesel van. The assessment shows that the e-cargo bike performs better for all the impact categories considered. The second-best option is the e-van, while the diesel van shows the worst environmental results. Focusing on decarbonization, the replacement of a diesel van with an electric one or with an e-cargo bike allows a reduction of 173 g CO2 eq/km and 250 g CO2 eq/km, respectively. Similar results are obtained for Photochemical Ozone F... [more]

Owing to the constantly rising energy demand, Internal Combustion Engine (ICE)-equipped vehicles are being replaced by Electric Vehicles (EVs). The other advantage of using EVs is that the batteries can be utilised as an energy storage device to increase the penetration of renewable energy sources. Integrating EVs with the grid is one of the recent advancements in EVs using Vehicle-to-Grid (V2G) technology. A bidirectional technique enables power transfer between the grid and the EV batteries. Moreover, the Bidirectional Wireless Power Transfer (BWPT) method can support consumers in automating the power transfer process without human intervention. However, an effective BWPT requires a proper vehicle and grid coordination with reasonable control and compensation networks. Various compensation techniques have been proposed in the literature, both on the transmitter and receiver sides. Selecting suitable compensation techniques is a critical task affecting the various design parameters. I... [more]

The Chang 7 member of the Upper Triassic Yanchang Formation in the Ordos Basin is considered to hold the main source rocks for conventional and unconventional oil and gas. The lamination or lithology alteration in vertical and lateral directions, even over a short distance, is a common feature in lacustrine source rocks. The differences in the geochemical characteristics of black shales, dark mudstones and interbedded sandstones have been scarcely reported, and their influences on the petroleum generation potential and shale oil potential are not clear. To this end, 22 core samples were collected from the Lower and Middle Chang 7 (C7-3 and C7-2) members of the Triassic from well CYX in the Qingcheng area. By conducting a series of geochemical analyses including TOC, Rock-Eval pyrolysis yields, bitumen extraction and quantification, and the separation and quantification of saturates, aromatics, resins and asphaltenes, along with biomarker analyses, several results were found. Firstly, t... [more]

The influence of electromagnetic induction coil launcher (EICL) system parameters on the launch performance was analyzed, and a method for measuring the launch performance of an EICL system with a muzzle velocity and energy conversion efficiency was proposed. The EICL system mainly includes a pulse power supply and launcher. The parameters of the pulse power supply mainly include the discharge voltage and the capacitance value of the capacitor bank. The structural parameters of the launcher mainly include the bore size of the launcher, the air gap length between the armature and the drive coil, the length and width of the drive coil, and the trigger position of the armature. Change in single or multiple parameters in the launch system will influence the launch performance. The influence of single or multiple parameters on the launch performance was summarized, and the physical law as analyzed. The influence law of the EICL system parameters on the launch performance was obtained, which... [more]

The Rapid reduction of energy resources and the escalated effects of global warming have created a strong motivation to find some new techniques in the field of paving construction. Adopting new technologies, such as warm-mix asphalt (WMA) or the recycling process of asphalt can be very helpful for the economy and have a significant impact on the environmental footprint. Thus, this research aimed to study the mechanical and durable characteristics of modified WMA mixtures using (1.0%, 1.5%, and 2.0%) Sasobit REDUX®, (0.3%, 0.4%, and 0.5%) Aspha-Min®, and (0.07%, 0.1%, and 0.125) ZycoTherm® additives corresponding to three percentages of reclaimed asphalt pavement (RAP) (20%, 40%, and 60%). Three mixing temperatures have been conducted in this study to generate WMA mixtures at (135 °C, 125 °C, and 115 °C) corresponding to three compacting temperatures (125 °C, 115 °C, and 105 °C). The mechanical properties of the developed WMA mixtures have been evaluated using the Superpave volumetric... [more]

The demand for energy is increasing at an abrupt pace, which has highly strained the power system, especially with high share of power generation from renewable energy sources (RES). This increasing strain needs to be effectively managed for a continuous and smooth operation of the power system network. Generation and demand exhibit a strong correlation that directly creates an impact on the power system frequency. Fluctuations and disruptions in load frequency can manifest themselves as over-voltages and physical damages in the power grid and, in the worst case, can lead to blackouts. Thus, this paper proposed an effective solution to mitigate the load frequency problem(s), which is initiated by the changing load demand under high penetration of RES. This paper presented an improved cascaded structure, the proportional integral with a fractional operator coupled with proportional derivative PI−FOP+PD. The proposed FOP+PD modifies the (1+PD) controller by introducing fractional propert... [more]

The rapid adoption of the smart grid’s nascent load-management capabilities, such as demand-side management and smart home systems, and the emergence of new classes of controllable high-wattage loads, such as energy storage systems and electric vehicles, magnify the smart grid’s exposure to load-altering cyberattacks. These attacks aim at disrupting power grid services by staging a synchronized activation/deactivation of numerous customers’ high-wattage appliances. A proper defense plan is needed to respond to such attacks and maintain the stability of the grid, and would include prevention, detection, mitigation, incident response, and/or recovery strategies. In this paper, we propose a solution to detect load-altering cyberattacks using a time-delay neural network that monitors the grid’s load profile. As a case study, we consider a cyberattack scenario against demand-side management programs that control the loads of residential electrical water heaters in order to perform peak shav... [more]

The hybrid indirect evaporative cooling-mechanical vapor compression (IEC-MVC) process is deemed a promising cooling system for hot and humid areas. It possesses the merits of high energy efficiency and strong capability of temperature and humidity control. Herein, we provide an overview of the state-of-the-art investigations over different aspects of the hybrid IEC-MVC process. Firstly, we evaluate the potential of IEC as a pre-cooler and heat-recovery device. Then, we compare the energy efficiency of IEC-MVC with standalone MVC and summarize its long-term energy-saving potential under specific weather conditions. Subsequently, we discuss the economic viability and water consumption of the hybrid process. These studies form a solid foundation for the future installation of the IEC-MVC system.

Decreasing the negative impact of buildings on the environment is a major challenge [...]

In the present paper, a current sensorless (CSL) method for buck-boost converter control is proposed for maximum power point tracking (MPPT) photovoltaic applications. The proposed control scheme uses the mathematical model of the buck-boost converter to derive a predefined objective function for the MPPT control. The proposed scheme does not require any current sensor and relies only on the input voltage signal, which decreases the implementation cost. The proposed method is successfully implemented using a Matlab/Simulink/Stateflow environment, and its effectiveness is compared over the perturb and observe (P&O) method. An experimental rig, that includes a buck-boost converter, a PV simulator, and a resistive load, is used for the experimental validation. A rapid Arduino prototyping platform is used for the digital implementation, where the SAM3X8E microcontroller of the Arduino DUE board, which integrates an ARM Cortex-M3 MCU, is used as a target hardware for the proposed model-base... [more]

Fuel spray characteristics influence combustion, which in turn has a direct impact on engine performance and emissions. Recently, there has been an increasing interest in novel castor oil biodiesel. However, few investigations have been performed that combine both numerical and experimental biodiesel spray analyses. Hence, in this paper, we aim to explore the spray behavior of castor and jatropha biodiesel by employing numerical and experimental methods under non-evaporating, varying injection, and ambient conditions. The experimental study was carried out in a control volume vessel (CVV) at high injection and ambient pressures. The fuel atomization was modelled in ANSYS Fluent using a Lagrangian/Eulerian multiphase formulation. The results revealed that the Kelvin−Helmholtz and Rayleigh−Taylor (KHRT) model coupled with the Taylor Analogy Breakup (TAB) model provide a better estimation of the penetration length (PL) and spray cone angle (SCA) compared to the KH and TAB models. On avera... [more]

To reduce the impact of volatility on photovoltaic (PV) power generation forecasting and achieve improved forecasting accuracy, this article provides an in-depth analysis of the characteristics of PV power outputs under typical weather conditions. The trend of PV power generation and the similarity between simultaneous outputs are found, and a hybrid prediction model based on feature matching, singular spectrum analysis (SSA) and a long short-term memory (LSTM) network is proposed. In this paper, correlation analysis is used to verify the trend of PV power generation; the similarity between forecasting days and historical meteorological data is calculated through grey relation analysis; and similar generated PV power levels are searched for phase feature matching. The input time series is decomposed by singular spectrum analysis; the trend component, oscillation component and noise component are extracted; and principal component analysis and reconstruction are carried out on each comp... [more]