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There is a growing demand for renewable and sustainable energy conversion and storage devices with the exhaustion of fossil fuels and increasing environmental contamination. In this paper, nickel diselenide (NiSe2) structures wrapped with various rGO (4%, 8%, 16%, and 32%) weight ratios were fabricated using a simple hydrothermal method and their structural, morphological, and electrochemical characteristics were studied systematically. The electrochemical properties of NiSe2/rGO with varying rGO concentrations were studied, and their supercapacitive performance was evaluated. NiSe2-16% rGO electrode outperformed NiSe2-32% rGO, NiSe2-8% rGO, and NiSe2-4% rGO due to its interconnected network topology and decreased effect of volume expansions. Moreover, during electrochemical activities, the optimum NiSe2-16% rGO electrode exhibited a high specific capacitance (1845.5 F g−1 at 1.5 A g−1), excellent cycling stability (99.4% over 5000 cycles), and rapid ion/electron transit. An asymmetric supercapacitor with NiSe2-16% rGO as anode and activated carbon as cathode exhibited a high energy density of 12.66 Wh kg−1 at 3999.84 W kg−1 and 99% retention of capacitance after 8000 repeated cycles. Our results have successfully demonstrated that the fabricated asymmetric supercapacitor has potential applications in the energy storage field.

A novel eutectoid structure, WxC-embedded WS2 nanosheets hybrids composite, was developed by hydrothermal reaction followed by a carbonization process. The fabricated WS2–WxC hybrid nanosheets electrode was used for lithium-ion batteries as an anode material, and demonstrated the specific capacity of 272 mA h·g−1 at 0.01 A g−1 with enhanced rate competence and cycling behavior when compared with individual WS2 and W2C electrode. While the large interlayer spacing in WS2 facilitates rapid Li+ transport, the extremely high electronic conductivity of WxC provides a highly conductive electron transfer pathway, which facilitates fast and reversible (de)lithiation reactions during charging and discharging. Further, these outcomes point the way for developing future eutectoid hybrid systems for advanced energy-storage applications.

Adverse atmospheric conditions and health hazards originated due to the discharge of particulate matter (PM), hydrocarbons (HC), nitrogen oxides (NOx) and carbon monoxide (CO) are the fundamental challenges to the researchers working on diesel engine. The solution is to develop cleaner technologies to abate emissions from diesel engine exhaust. In this paper, a novel hybrid emission control unit composed of counter flow heat exchanger (HE), oil bath cleaning unit (OBCU) and exhaust gas recirculation (EGR), the combination abbreviated as HE-OBCU-EGR unit, was designed, fabricated and implemented on the exhaust manifold of Massey Ferguson (MF-260) tractor engine to reduce the regulated gaseous emissions. An experimental study was conducted to investigate the effects of HE-OBCU-EGR unit on the emissions of a four-stroke, three cylinder diesel engine equipped with an eddy-current dynamometer. The tests were conducted on engine speed of 1400 to 2000 rpm with an interval of 100 rpm at full load. The AVL DiTEST and AVL smoke meter were used to analyze the emissions including soot concentration (SC), pollution level (PL), filter smoke number (FSN), HC, NOx and CO. The results obtained with HE-OBCU-EGR unit revealed 44.9%, 29.2%, 26.3%, 42.9% and 24.8% reduction in SC, PL, FSN, HC and NOx emissions, whereas CO emissions were increased by 14.3% due to limited supply of oxygen from EGR. Results revealed that HE-OBCU-EGR unit may help to minimize the emissions of HC, SC, PL, FSN and NOx but is not suitable to control CO emissions. To minimize the emissions of CO, this technology can be superposed with turbocharger or supercharger to enhance the availability of O2 in the combustion chamber.

We explored the doping effect of Ge4+ on the Li4Ti5-xGexO12 (x = 0.0 and 0.05) anode material by looking at its electrochemical performance in both Li- and Na-ion batteries. Combined analysis using Rietveld refinement of high-resolution powder diffraction (HRPD) and transmission electron microscopy (TEM) unambiguously identified homogeneous Ge doping into the 16c octahedral Ti site of the Li4Ti5O12 (LTO) cubic spinel structure. This Ge doping leads to a much-reduced particle size, slightly expanded lattice and increased electrical conductivity due to the increased Ti3+ to Ti4+ ratio, these results were verified by HRPD, scanning electron microscopy (SEM), 4-point probe and x-ray photoelectron spectroscopy (XPS) analysis. The Li4Ti4.95Ge0.05O12 (Ge0.05-LTO) electrode shows much-improved capacity, high-rate capability and excellent cycling stability in a Li-half cell compared with an un-doped LTO electrode. This performance improvement is due to the reduced Li+ diffusion path and faster Li+ insertion/extraction kinetics that originate from Ge doping. In addition to these results, when tested as an anode for SIBs, the Ge0.05-LTO electrode exhibits enhanced capacity and cycling stability compared to un-doped LTO electrode, demonstrating its bi-functional, advantageous features in both LIB and SIB systems.

This paper presents a fast fault detection scheme based on mathematical morphology (MM), which is a nonlinear signal transformation tool in a time-domain, in order to avoid the damage on diodes of power electronic devices in low voltage DC (LVDC) distribution networks. The MM is utilized to extract abnormal features from fault currents when short circuit faults with capacitive discharging characteristic or high impedance faults (HIFs) with arcing phenomenon occur in the network. The presented scheme utilizes a dilation erosion difference filter (DEDF) and closing opening difference filter (CODF) for detecting capacitive discharging current from the AC/DC converter and arc current with repetitive extinction and re-ignition, respectively. The two filters work in a coordinated way to meet the critical fault detection time (CFDT) for preventing damages on diodes in the AC/DC converter and avoid unfavorable tripping by applying different length of structuring element (SE). The framework for using the proposed scheme including a guideline for selecting the SE for each filter is also presented to make the best use of the proposed scheme. The presented scheme is implemented using the electromagnetic transients program (EMTP) and computer simulations are conducted on a test last mile radial LVDC distribution network.

Carbon quantum dots derived from the chemical oxidation of D-(+)-glucose have been efficiently synthesized in good yield using a simple and economically viable approach. Carbon quantum dots possess a quasi-spherical structure with facile storage and transport channels for lithium and sodium-ions. When applied as an anode for the lithium-ion battery, the as-prepared quantum dots demonstrate a superior and stable cycling performance after 500 cycles (864.9 mAh g−1 at 0.5 C) with capacity retention of 91.6%, and a good rate performance (340.2 mAh g−1 at 20 C). As a sodium-ion battery anode, the quantum dots present a specific capacity of 323.9 mAh g−1 at 0.5 C and capacity retention of 72.4% after 500 charge/discharge cycles, indicating an excellent cycling stability. A relatively moderate rate performance of 123.6 mAh g−1 is achieved at the 20 C rate. This study demonstrates the use of individual quantum dots as a potential electrode material for lithium-ion, and sodium-ion battery applications, and it will definitely result in the fabrication of new composite materials in the energy-storage field. The extreme downsizing to the quantum regime has led to the achievement of utmost properties that have been prescribed to the quantum effects, efficient ion diffusion, and the charge transfer.

The concept of microgrids has been proposed as an economical, reliable, and efficient way to integrate a large number of distributed energy resources (DERs) into distribution networks. To ensure the safe operation of a microgrid fast and accurate fault detection and location are crucial. This paper proposes fault detection and location in a microgrid using mathematical morphology (MM) and recursive least-square (RLS) methods. The proposed method first applies dilation and erosion median filter (DEMF) on a current signal to detect and classify the faults in microgrids. Then, the RLS method estimates the fault location using a differential equation derived from an equivalent model of the microgrid. The performance of the proposed method is evaluated on a medium voltage microgrid test system through simulations using MATLAB/SIMULINK. The simulation results depict that the proposed method provides faster fault detection and accurate fault location.

Nanostructured sodium metal orthosilicates hold a lot of promise as next-generation cathodes but their practical application is hindered by the complex crystal structure and electrochemical behaviour. Herein, cubic polymorphs of Na2FeSiO4 with F-43 m symmetry decorated on carbon nanotubes have been synthesised successfully using a novel two-step process. The composite material with 0.08 wt% of carbon nanotubes demonstrate a capacity corresponding to a 1.25 sodium-ion exchange process resulting in 172.9 mAh g−1 at 0.1C cycled in the voltage range between 1.5 and 4.5 V. This work also highlights the mechanism of insertion/extraction process using complementary techniques of X-ray photoelectron spectroscopy, and X-ray diffraction revealing the involvement of Fe 3 d band and conversion of Fe+2 to Fe+3 during first sodium-ion extraction while second sodium-ion extraction is possible due to further oxidation of Fe+3. The discharge capacity is remarkable even at the high current rate of 20C, where we obtained the final capacity of 109.3 mAh g−1. The excellent electrochemical performance reported here is due to the high structural stability of Na2FeSiO4 composed of rigid corner-sharing tetrahedra, improved electronic conductivity by carbon nanotubes, reduced particle size, increased defect structure, high sodium-ion diffusion coefficient and the decreased charge transfer resistances.

The concept of microgrids has been introduced to facilitate the integration of the distributed energy resources (DERs) into distribution networks in a more economical, reliable and environment-friendly manner. One of the critical challenges associated with microgrids is devising an appropriate protection strategy. This is because the fault current level continuously varies owing to the existence of DERs and to the fact that the microgrid can operate in grid-tied and islanded modes. This paper proposes a new protection strategy for microgrids using an interval type-2 fuzzy logic system. The proposed strategy considers various uncertainties associated with faults and employs two different fuzzy systems to detect, classify, and locate the faults in microgrids. The phase angle between superimposed modal voltage and modal current is used as an input to the fuzzy system designed to identify the fault direction. The significant feature of the proposed strategy is that it can protect the microgrid after a single-phase tripping event. To validate the effectiveness of the proposed strategy, we have performed extensive simulations using MATLAB/SIMULINK. The simulation results show that the proposed strategy can detect, classify, and isolate various faults in the microgrid. Moreover, the strategy also provides backup protection in case of failure of the primary protection.

To overcome crosstalk effects in operational transfer path analysis (OTPA) for effective identification and evaluation of vibration transfer path contributions based on measured response signals, a customized scheme of crosstalk cancellation for OTPA is proposed in this paper, which flexibly adopts different crosstalk cancellation methods for different path stages, and quantitatively evaluates transfer path contributions with high accuracy and efficiency. Firstly, the fundamental theories of OTPA and two crosstalk cancellation methods, prior transmissibility function-based method and independent component analysis (ICA) based method, are introduced. Secondly, an OTPA model is constructed for the test bed with shell structures, and the effects of airborne path contributions on OTPA is also analysed. Thirdly, the proposed customized scheme is applied to the two-stage transfer path of the test bed, and the vibration path contributions are comprehensively evaluated and analysed. Generally, this study proposes a flexible crosstalk cancellation scheme of OTPA for complex mechanical systems, which can provide reliable evidences for vibration and noise reduction and control.

With the growing integration of distributed generation, distribution networks have evolved toward the concept of microgrids. Microgrids can be operated in either the grid-connected mode to achieve peak shaving and power loss reduction or the islanded mode to increase the reliability and continuity of supply. These two modes of operation cause a challenge in microgrid protection, because the magnitude of fault current decreases significantly during the transition of a microgrid from the grid-connected mode to the islanded mode. This paper proposes a protection scheme for the microgrid based on superimposed reactive energy. The proposed scheme uses the Hilbert transform to calculate the superimposed reactive energy (SRE). The sequence components of superimposed current are adopted to detect fault incidents in the microgrid. The faulty phase and section are recognised by using the directional characteristics of SRE along with a threshold value. Moreover, a relay structure, which enables the proposed protection scheme, is designed. The significant feature of the proposed protection scheme is that it has the ability to protect the looped and radial microgrids against solid and high-impedance faults. To verify the efficacy of the proposed approach, extensive simulations have been carried out using the MATLAB/SIMULINK software package. The results show that the proposed scheme successfully identifies and isolates various types of fault in a microgrid and performs well with different fault resistances and fault locations.

In recent years, the emergence of antibiotic resistant bacteria has compelled the scientific community to develop new class of antibiotics with improved efficiency. In this work, we synthesized cryptomelane type FexMn1-xO2 (for x = 0.00, 0.04, 0.08, 0.12) nanowires and performed an in-vitro study of the antibacterial activity against multidrug resistant (MDR) S. aureus (G-positive) and Extensively Drug-Resistant (XDR) S. Typhi (G-negative) strains. The samples were successfully prepared by using a simple hydrothermal method and their structural, morphological, optical and thermal properties were investigated by a range of comprehensive analytical tools. The variation of Fe concentration in the host lattice significantly influenced the physicochemical properties of the cryptomelane. The antimicrobial screenings indicated that increasing the fraction of Fe from x = 0.00 to 0.12 also increases the inhibitory zones. A maximum inhibitory zone of 25 mm for S. Typhi and 23 mm for S. aureus was observed. The antibacterial results, evaluated through the agar well-diffusion method, suggested that cryptomelane FexMn1-xO2 nanowires are remarkably efficient against both types of resistant bacterial strains and could be used for food preservation and biomedical applications.

Methane enrichment in anaerobic digestion (AD) is definitely required to enhance the calorific value of biogas to ensure its application as an off-grid energy source. Electromethanation in bioelectrochemical systems (BESs) integrated with the AD process is a promising technology because of its efficient conversion of CO2 to methane at the biocathode using microbes as catalysts. An additional advantage of this system is CO2 fixation, which is important in view of the increasing global-warming threat. BES performance is highly reliant on different operating and physical parameters, among which poor cathode materials and reactor design often limit the performance. The cathode serves as an electron reservoir for microorganisms to reduce CO2 to methane. Reactor design governs internal resistance, mass transport of reactants and products, and boundary-layer oxygen diffusion in the system, which determine the rate of ion flux and overall system performance. Detailed critical commentary on recent developments in cathode materials and their role in the bioconversion of methane and adopted efficient BES–AD designs is given in this paper. The current costs of catalysts and base-electrode materials for scaling up BES-AD have been also comprehensively discussed. Studies have suggested that an efficient cathode should possess biocompatibility, hydrophilicity, positive surface charge, and an extensive surface area. Graphitic-carbon materials, especially those with three-dimensional structure, have been demonstrated to be superior cathodes than metal electrodes. The modification of carbon-based electrodes with efficient catalysts could further enhance performance in methane production suggesting the beneficial action of catalyst on the microbes–electrode interaction and extracellular electron transfer. Further detailed investigations will help the development of cutting-edge catalysts and configurations for scale-up BES–AD systems.

Comparison of surface effects in bare and titanium oxide coated CoFe2O4 nanoparticles has been done with the help of magnetic measurements. The average crystallite size was 31 for bare CoFe2O4 nanoparticles. For titanium oxide coated nanoparticles, the CoFe2O4 and titanium oxide phases have crystallite size of 46 and 38 nm, respectively. TEM images confirmed the coating behavior of titanium oxide on CoFe2O4 nanoparticles. Both kinds of nanoparticles were in magnetically blocked state at room temperature as evident by ZFC/FC measurements. The effective anisotropy constant was calculated from simulated ZFC curve and found higher for bare CoFe2O4 nanoparticles due to large surface spin disorder and strong interparticle interactions. In modified Bloch's law fit for Ms vs. T data, the higher value of Bloch's constant for titanium oxide coated CoFe2O4 nanoparticles demonstrates the weak exchange coupling constant J. The Kneller's law fit for Hc vs. T data showed a lower value of constant α for titanium oxide coated CoFe2O4 nanoparticles which is due to the reduced surface magnetic and weak interparticle interactions. In summary, crystalline titanium oxide coating on CoFe2O4 nanoparticles showed reduction in surface spin disorder and weaken interparticle interactions.

The contradictory relationship between the damping capacity and specific strength remains a challenge for developing metallic damping materials with high strength and stability for energy-absorbing and energy-saving applications. Porous TiNi shape memory alloy composite (SMAC) seems to be a valid strategy to solve this problem. The deformation and damping behaviors of porous SMAC (composed on a particle-like brittle Ti2Ni embedded in ductile TiNi shape memory alloy matrices) were studied and precisely determined using dynamic mechanical analyzer (DMA) and compressive testing in this study. The porous B2–TiNi and Ti2Ni composites exhibit a three-stage deformation character while only one-yielding phenomenon in the compressive stress-strain curves, which is ascribed to the synergistic effect of pore together with the interaction of TiNi and Ti2Ni phases which is different from dense SMAC. This is because porous SMAC with 37% porosity demonstrates exceptional damping property of at least 0.025 at relatively low strain amplitude in −100 to 200 °C temperature range, which resulted from modulus mismatch and the massive interfaces between pore/matrix and TiNi/Ti2Ni. Moreover, the high 113 MPa∙cm3/g compressive specific strength and 27% fracture strain in RT to 130 °C temperature range further dominate on dense SMAC.

Pretreatment of pre-blended palm and rubber seed oil (50:50) was studied. A parametric study to determine the effect of alcohol-to-oil ratio, catalyst loading and reaction temperature on free fatty acid (FFA) content was also conducted. Interestingly, the FFA percentage of pre-blended feedstock has been reduced significantly from 20% to below 2%. The optimum value for the reduction of FFA was found to be 1.5 wt. % catalyst, alcohol-to- oil ratio 6:1, 62 °C reaction temperature at constant stirring speed (400 rpm) and reaction time 1.5 hours. NaOH/bentonite was also investigated and characterized as a solid heterogeneous catalyst for transesterification. The characterization was conducted by FTIR and XRD analysis. The catalyst showed good results by producing 92 wt% fatty acid methyl esters at reaction temperature of 62 °C and reaction time of 3 hours.

The high penetration of renewable energy resources, along with their inherently intermittent nature, makes unintentional islanding a critical issue in distributed generation systems. This study proposes an islanding detection scheme for integrated microgrids by using variational mode decomposition-based mode singular entropy (VMDMSE). The proposed scheme retrieves a three-phase voltage signal at the targeted distribution energy resource (DER), and employs variational mode decomposition (VMD) to obtain the principal modes. First, singular value decomposition (SVD) generates the characteristic singular matrix. Then, the probability array associated with the singular values is calculated. Finally, the mode singular entropy (MSE) is computed and utilized as an islanding detection index. The proposed scheme is evaluated through several simulations in various islanded and normal operating conditions. Moreover, cases involve varying power mismatches, and the quality factor are simulated on a widely used UL-1741 standard test system in MATLAB/SIMULINK environment. The obtained results confirm that the proposed scheme is capable of detecting islanding operation within half a cycle, even for a zero mismatch power between load and generation in the islanded region.