Reliability analysis of corroded pipelines is critical to the integrity and safe working of pipeline infrastructure. Aiming at less probability information is obtained for corrosion pipeline engineering, and the mechanical properties of pipeline with corrosion defects deteriorate caused by the accumulative effect of corrosion growth. Based on the quasi-static analysis method and non-probability theory, this paper presents a reliability model for assessing corroded pipelines with corrosion growth. In fact, reliability analysis of corroded pipelines needs to consider the interaction of multiple uncertainty variables. By introducing interaction theory, a mathematical model of corrosion defects considering the interaction of variables is put forward. Moreover, this paper develops a non-probabilistic time-varying reliability method for pipeline systems with multiple defects. Thus, several numerical examples are investigated to discuss the effectiveness of the proposed methodology. The resul... [more]

Scientific and reasonable battery thermal management systems contribute to improve the performance of a power battery, prolong its life of service, and improve its safety. Based on TAFEL-LAE895 type 100Ah ternary lithium ion power battery, this paper is conducted on charging and discharging experiments at different rates to study the rise of temperature and the uniformity of the battery. Paraffin can be used to reduce the surface temperature of the battery, while expanded graphite (EG) is added to improve the thermal conductivity and viscosity of the composite phase change material (CPCM), and to reduce the fluidity after melting. With the increase of graphite content, the heat storage capacity of phase change material (PCM) decreases, which affects the thermal management effect directly. Therefore, this paper combines heat pipe and semiconductor refrigeration technology to transform heat from the inner CPCM to the thermoelectric cooling sheet for heat dissipation. The results show tha... [more]

Nickel-rich cathode material, NCA (85:14:1), is successfully synthesized using two different, simple and economical batch methods, i.e., hydroxide co-precipitation (NCA-CP) and the hydroxides solid state reaction method (NCA-SS), followed by heat treatments. Based on the FTIR spectra, all precursor samples exhibit two functional groups of hydroxide and carbonate. The XRD patterns of NCA-CP and NCA-SS show a hexagonal layered structure (space group: R_3m), with no impurities detected. Based on the SEM images, the micro-sized particles exhibit a sphere-like shape with aggregates. The electrochemical performances of the samples were tested in a 18650-type full-cell battery using artificial graphite as the counter anode at the voltage range of 2.7−4.25 V. All samples have similar characteristics and electrochemical performances that are comparable to the commercial NCA battery, despite going through different synthesis routes. In conclusion, the overall results are considered good and have... [more]

Calcium chloride brine-based drill-in fluid is commonly used within the reservoir section, as it is specially formulated to maximize drilling experience, and to protect the reservoir from being damaged. Monitoring the drilling fluid rheology including plastic viscosity, P V , apparent viscosity, A V , yield point, Y p , flow behavior index, n , and flow consistency index, k , has great importance in evaluating hole cleaning and optimizing drilling hydraulics. Therefore, it is very crucial for the mud rheology to be checked periodically during drilling, in order to control its persistent change. Such properties are often measured in the field twice a day, and in practice, this takes a long time (2−3 h for taking measurements and cleaning the instruments). However, mud weight, M W , and Marsh funnel viscosity, M F , are periodically measured every 15−20 min. The objective of this study is to develop new models using artificial neu... [more]

The thermodynamic characterisation of magnetocaloric materials is an essential task when evaluating the performance of a cooling process based on the magnetocaloric effect and its application in a magnetic refrigeration cycle. Several methods for the characterisation of magnetocaloric materials and their thermodynamic properties are available in the literature. These can be generally divided into theoretical and experimental methods. The experimental methods can be further divided into direct and indirect methods. In this paper, a new procedure based on an artificial neural network to predict the thermodynamic properties of magnetocaloric materials is reported. The results show that the procedure provides highly accurate predictions of both the isothermal entropy and the adiabatic temperature change for two different groups of magnetocaloric materials that were used to validate the procedure. In comparison with the commonly used techniques, such as the mean field theory or the interpol... [more]

As a major supplement to conventional fossil fuels, unconventional oil and gas resources have received significant attention across the globe. However, significant challenges need to be overcome in order to economically develop these resources, and new technologies based on a fundamental understanding of flow and transport processes in unconventional reservoirs are the key. This special issue collects a series of recent studies focused on the application of novel technologies and theories in unconventional reservoirs, covering the fields of petrophysical characterization, hydraulic fracturing, fluid transport physics, enhanced oil recovery, and geothermal energy.

Thermal transient testing is widely used for LED characterization, derivation of compact models, and calibration of 3D finite element models. The traditional analysis of transient thermal measurements yields a thermal model for a single heat source. However, it appears that secondary heat sources are typically present in LED packages and significantly limit the model’s precision. In this paper, we reveal inaccuracies of thermal transient measurements interpretation associated with the secondary heat sources related to the light trapped in an optical encapsulant and phosphor light conversion losses. We show that both have a significant impact on the transient response for mid-power LED packages. We present a novel methodology of a derivation and calibration of thermal models for LEDs with multiple heat sources. It can be applied not only to monochromatic LEDs but particularly also to LEDs with phosphor light conversion. The methodology enables a separate characterization of the primary... [more]

This paper describes experimental research on a floating moored Oscillating Water Column (OWC)-type Wave-Energy Converter (WEC) carried out in the wave flume of the Coastal Engineering Research Group of Ghent University. This research has been introduced to cover the existing data scarcity and knowledge gaps regarding response of moored floating OWC WECs. The obtained data will be available in the future for the validation of nonlinear numerical models. The experiment focuses on the assessment of the nonlinear motion and mooring-line response of a 1:25 floating moored OWC WEC model to regular waves. The OWC WEC model motion has 6 degrees of freedom and is limited by a symmetrical 4-point mooring system. The model is composed of a chamber with an orifice on top of it to simulate the power-take-off (PTO) system and the associated damping of the motion of the OWC WEC model. In the first place, the motion response in waves of the moored floating OWC WEC model is investigated and the water... [more]

The aim of this study is to characterise the changes in mechanical properties and to provide a comprehensive micro-structural analysis of Harcourt granite over different pre-heating temperatures under two cooling treatments (1) rapid and (2) slow cooling. A series of uniaxial compression tests was conducted to evaluate the mechanical properties of granite specimens subjected to pre-heating to temperatures ranging from 25⁻1000 °C under both cooling conditions. An acoustic emission (AE) system was incorporated to identify the fracture propagation stress thresholds. Furthermore, the effect of loading and unloading behaviour on the elastic properties of Harcourt granite was evaluated at two locations prior to failure: (1) crack initiation and (2) crack damage. Scanning electron microscopy (SEM) analyses were conducted on heat-treated thin rock slices to observe the crack/fracture patterns and to quantify the extent of micro-cracking during intense heating followed by cooling. The results r... [more]

In the last few years, a large number of smart meters have been deployed in buildings to continuously monitor fine-grained energy consumption. Meteorological data deeply impact energy consumption, and an in-depth analysis of collected and correlated data can uncover interesting and actionable insights to improve the overall energy balance of our communities and to enhance people’s awareness of energy wasting. To effectively extract meaningful and interpretable insights from large collections of energy measurements and multi-dimensional meteorological data, innovative data science methodologies should be devised. Research frontiers are addressing self-learning approaches, which allow non-experts to exploit machine learning techniques more easily, and algorithmic transparency of models, hence providing actionable, explicit, declarative knowledge representation. This paper presents METeorological Data Analysis for Thermal Energy CHaracterization (METATECH), a data mining engine based on b... [more]

Thermodynamic and heat transfer properties of the 2LiBH₄-MgH₂ composite (Li-RHC) system are experimentally determined and studied as a basis for the design and development of hydrogen storage tanks. Besides the determination and discussion of the properties, different measurement methods are applied and compared to each other. Regarding thermodynamics, reaction enthalpy and entropy are determined by pressure-concentration-isotherms and coupled manometric-calorimetric measurements. For thermal diffusivity calculation, the specific heat capacity is measured by high-pressure differential scanning calorimetry and the effective thermal conductivity is determined by the transient plane source technique and in situ thermocell. Based on the results obtained from the thermodynamics and the assessment of the heat transfer properties, the reaction mechanism of the Li-RHC and the issues related to the scale-up for larger hydrogen storage systems are discussed in detail.

Several series of six-cell photovoltaic test-modules—intact and with deliberately generated failures (micro-cracks, cell cracks, glass breakage and connection defects)—were artificially and naturally aged. They were exposed to various stress conditions (temperature, humidity and irradiation) in different climate chambers in order to identify (i) the stress-induced effects; (ii) the potential propagation of the failures and (iii) their influence on the performance. For comparison, one set of test-modules was also aged in an outdoor test site. All photovoltaic (PV) modules were thoroughly electrically characterized by electroluminescence and performance measurements before and after the accelerated ageing and the outdoor test. In addition, the formation of fluorescence effects in the encapsulation of the test modules in the course of the accelerated ageing tests was followed over time using UV-fluorescence imaging measurements. It was found that the performance of PV test modules with me... [more]

Hydrogen storage in the solid state represents one of the most attractive and challenging ways to supply hydrogen to a proton exchange membrane (PEM) fuel cell. Although in the last 15 years a large variety of material systems have been identified as possible candidates for storing hydrogen, further efforts have to be made in the development of systems which meet the strict targets of the Fuel Cells and Hydrogen Joint Undertaking (FCH JU) and U.S. Department of Energy (DOE). Recent projections indicate that a system possessing: (i) an ideal enthalpy in the range of 20⁻50 kJ/mol H₂, to use the heat produced by PEM fuel cell for providing the energy necessary for desorption; (ii) a gravimetric hydrogen density of 5 wt. % H₂ and (iii) fast sorption kinetics below 110 °C is strongly recommended. Among the known hydrogen storage materials, amide and imide-based mixtures represent the most promising class of compounds for on-board applications; however, some barriers still have to be overcom... [more]

In this communication we present a detailed study of Nafion™ composite membranes containing different amounts of nanosized sulfated titania particles, synthesized through an optimized one-step synthesis procedure. Functional membrane properties, such as ionic exchange capacity and water uptake (WU) ability will be described and discussed, together with thermal analysis, atomic force microscopy and Raman spectroscopy data. Also electrochemical properties such as proton conductivity and performances in hydrogen fuel cells will be presented. It has been demonstrated that a critical concentration of filler particles can boost the fuel cell performance at low humidification, exhibiting a significant improvement of the maximum power and current density delivered under 30% low-relative humidity (RH) and 70 °C with respect to bare Nafion™-based systems.

Lignin is Nature’s major source of aromatic chemistry and is by many seen as the green entry-point alternative to the fossil-based chemical industry. Due to its chemically recalcitrant structure, the utilization of lignin is challenging, wherein enzymes might be the key to overcome this challenge. Here, we focus on the characterization of dye-decolorizing peroxidases from Streptomyces coelicolor A3(2) (ScDyPs) in the context of enzymatic modification of organosolv lignins from aspen and Miscanthus × giganteus. In this study, we show that the ScDyPB can remodel organosolv lignins from grassy biomass, leading to higher molecular weight species, while ScDyPAs can deconstruct hardwood lignin, leading to an overall reduction in its molecular weight. Additionally, we show that ScDyPB is effective in polymerizing low-molecular-weight phenolics, leading to their removal from the solution.

A thorough study of the literature suggests that greater attention has to be paid to power line noise measurements, characterization, and modeling. Several studies show that significant differences do exist, and the findings are somewhat conflicting. This may be attributed to the diverse environment under investigation, which includes volatile noise sources, differences in electrical grid structure from country to country, topology, and unknown power cable characteristics. An in-depth analysis of the approaches for measuring, characterizing, and modeling noise, as well as the descriptions of relevant components, and the environment needed to carry out the measurements, is presented. This review serves as a roadmap for academics and engineers in the deployment of power line communication systems.

Sluggish oxygen reduction reaction (ORR) of electrodes is one of the main challenges in fuel cell systems. This study explored the kinetics of the ORR reaction mechanism, which enables us to understand clearly the electrochemical activity of the electrode. In this research, electrocatalysts were synthesized from platinum (Pt) catalyst with multi-walled carbon nanotubes (MWCNTs) coated by three polymers (polybenzimidazole (PBI), sulfonated tetrafluoroethylene (Nafion), and polytetrafluoroethylene (PTFE)) as the supporting materials by the polyol method while hexachloroplatinic acid (H2PtCl6) was used as a catalyst precursor. The oxygen reduction current of the synthesized electrocatalysts increased that endorsed by linear sweep voltammetry (LSV) curves while increasing the rotation rates of the disk electrode. Additionally, MWCNT-PBI-Pt was attributed to the maximum oxygen reduction current densities at −1.45 mA/cm2 while the minimum oxygen reduction current densities of MWCNT-Pt were o... [more]

The stable bearing capacity of roadside backfill body (RBB) is the key to control the surrounding rock deformation of gob-side entry retaining (GER) in deep mining. In this paper, slump and uniaxial compressive strength tests were conducted to study the changes of the slump and RBB mechanical properties of RBB fresh mixture under the influence of different percentages of fly ash (FA), river sand, and amounts of steel fiber (SF) admixture. The results show that (1) the slump first increases and then decreases with the increase of the FA proportion, while 20% of FA proportion is the critical point. In addition, SF has little influence on slump. However, when the proportion of FA is 60% and the content of SF is 0.4%, the slump reaches the minimum value of 130 mm. (2) The peak strength and residual strength increase with the increase of the FA proportion, and the strength gain starts to decrease when the FA proportion exceeds 40%. Moreover, SF only has a small effect on the peak strength w... [more]

Nanoencapsulated phase change materials (NePCMs) are promising thermal energy storage (TES) and heat transfer materials that show great potential in battery thermal management systems (BTMSs). In this work, nanocapsules with a paraffin core and silica shell were prepared using an optimized sol-gel method. The samples were characterized by different methods regarding chemical composition, thermal properties, etc. Then, the nanocapsules were used as the coolant by mixing with insulation oil in the immersion cooling of a simulative battery. The sample doped with Ag on the shell with a core-to-shell ratio of 1:1 showed the best performance. Compared to the sample without doping material, the thermal conductivity increased by 49%, while the supercooling degree was reduced by 35.6%. The average temperature of the simulative battery cooled by nanocapsule slurries decreased by up to 3.95 °C compared to the test performed with pure insulation oil as the coolant. These novel nanocapsules show gr... [more]

To investigate the influence of joints on the stability of underground opening, uniaxial compression tests and FE analyses based on a microplane damage model for rocks has been conducted for rock-like models with a circular hole and a set of non-persistent joints. It was found that the peak strength and Young’s modulus decrease with the increase in joint continuity factor k, and variation of them with joint inclination angle β are W or V-shaped curves with the minima and maxima at β = 30° and 90°, respectively. The failure modes of the specimens and the collapse modes of the hole can be related to crack coalescence between the hole and the joints or matrix. Numerical simulation can reproduce the main features of macroscopic mechanical behavior and explain the anisotropic damage mechanism. The strong interaction between the hole and the nearest joint was revealed. During the elastic stage, stress concentration around the hole will be altered by the presence of the joints, and the effect... [more]

Clean methanol can play an important role in achieving net zero emission targets by decarbonizing the energy and chemical sectors. Conventionally, methanol is produced by using fossil fuel as raw material, which releases a significant amount of greenhouse gases (GHGs) into the environment. Clean methanol, which is produced by hydrogen (H2) from renewable sources (green H2) and captured carbon dioxide (CO2), is totally free from the influence of fossil fuel. Due to its vast applications, clean methanol has potential to substitute for fossil fuels while preventing further GHGs emissions. This review addresses the feasibility of producing clean methanol from renewable resources, i.e., green H2 and captured CO2. Availability of these raw materials is the main factor involved in establishing the circular economy of methanol, therefore, their potential sources and the possible pathways to access these sources are also summarized. Renewable energy sources such as solar, wind and biomass shoul... [more]

Electric arcing is an unavoidable consequence of the current collection process by sliding contact in railways and metros, and in general in many electrified transportation systems (ETSs). The most relevant consequences in an electrical perspective are: the occurrence of transients triggering resonant behaviour and transient responses, reduction of the energy efficiency of the system, conducted and radiated disturbance, in particular for the new radio systems widely employed for signalling and communication. The involved parameters are many (type of materials, current intensity, DC and AC supply, relative speed, temperature), as well as the studied characteristics (arc instability and lifetime, dynamic behaviour, electrical system response, radiation efficiency and coupling to external radio systems). This work reports the state of the art in arc modelling, arcing experimental characterisation, interaction with the supply system, radiated emissions and disturbance to radio systems, pro... [more]

In this work, the synthesis of nickel particles encapsulated in a few-layer graphene shell was carried out using the method of electric arc discharge in the liquid phase, in various media: deionized water, alcohol, and toluene. Nickel and graphite were used as electrodes. The study was carried out to analyze how various liquids, acting as a cooling medium and a source of carbon, affect the formation of a protective shell around metal particles. Raman studies, analysis of X-ray diffraction data, and scanning electron microscopy confirmed the formation of spherical encapsulated nickel particles in all types of liquid media. It was found out that the use of toluene as a cooling medium increased the number of particles with a graphite shell and allowed obtaining micro- and nanoparticles covered with monolayer graphene. The absence of oxygen in the composition of toluene, in contrast with alcohol and especially water, prevents the oxidation of nickel particles during the synthesis. This fac... [more]

A novel route was invented for utilizing thermal energy (at an elevated temperature of 110 ± 2 °C) to synthesize and crosslink gels from resorcinol and formaldehyde without using catalysts or buffers. The outcome gels are identified by various techniques such as Fourier transform infrared, Raman spectroscopy, thermal gravimetric analysis, X-ray diffraction, nano-scanning electron microscopy, energy-dispersive X-ray spectroscopy and surface area and porosity analyses. Resorcinol−formaldehyde gels prepared by this approach are also carbonized and activated to study their subsequent activated carbons. The gels and their corresponding activated carbons expose hierarchical pore structures with micro-, meso- and macroporous features. The average pore sizes of gels and activated carbons ranged from 3.5 to 62.9 nm and from 0.9 to 2.0 nm, respectively. The total surface areas of gels and activated carbons ranged from 0.01 to 176.15 and from 160.93 to 511.46 m2/g, respectively. Moreover, the tot... [more]

Polypropylene undergoes permanent alterations during the processing and manufacture of cables due to shear effects, which in turn affect all of its qualities. There are currently few research papers on the modulation of material structure and many performance parameters by the shear stress field. In this study, we examined the impact of various shear levels on the structural, mechanical, and electrical properties of polypropylene, as well as their relationships. The results indicated that shear strength decreased the material’s viscosity and oxidation resistance. As shear duration increased, crystallinity began to diminish. In the meantime, the crystallinity improved as the shear temperature rose. The thermal elongations of the sheared samples were all about 5%. Short-term shearing boosted the material’s toughness, but as the degree of shear continued to increase, the material’s toughness and rigidity steadily decreased. The storage modulus of the material decreased with increasing she... [more]