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The complexity of the formation mechanism of ventilated cavities makes it difficult to be explored experimentally. In this study, the formation mechanism of cavity regimes around a gas jet cavitator were first numerically predicted using the partially averaged Navier–Stokes (PANS) and homogeneous free surface models. The numerical framework was validated by comparing the numerical predictions with available experimental data. The numerical results showed that the cavity evolves across four different regimes with increasing ventilation rate, that is, bubbly flow, stable cavity, unstable cavity, and jet cavity. Moreover, the gas jet length in the front of the nozzle continues to increase, and the vortex structure in the cavity transitions from a streamwise vortex to a vortex filament. Furthermore, the correlation between the adverse pressure gradients and the characteristics of the cavity was analyzed, and the results demonstrated that the adverse pressure gradient leads to stagnation of the gas jet and cavity closure.

Turbulence modeling plays a crucial role in simulating unsteady characteristics of cavitation flows. Owing to the different theoretical backgrounds of partially averaged Navier–Stokes (PANS) and filter-based models (FBMs), the differences in their unsteady cavitation flow predictions are worth comparing. In this study, PANS and FBM were used to predict the cloud cavitation regime around a three-dimensional (3D) Clark-Y hydrofoil. Next, the effect of these two models on the cloud cavitation shedding process, shedding frequencies, lift coefficient, and velocity gradient distribution on the foil surface was investigated in detail. The results show that the FBM works only in regions far away from the hydrofoil and hence, yields poor predictions in the near-wall region of the hydrofoil. On the other hand, the PANS formulation does not suffer from the above shortcoming; it could yield reasonable predictions of the unsteady characteristics of cloud cavitation, which were in good agreement with the experimental results reported in the literature.

The objective of this brief is to propose a hot-swappable grid-connected multilevel converter (HGM-converter) for the battery energy storage system (BESS). The proposed HGM-converter is composed of series-connected bi-directional H-bridge sub-converters and a LCL filter. Advantages of the proposed HGM-converter include: hot-swappable capability, single-stage power conversion, low dc-bus voltage, and individual power control for each battery module. Therefore, the equalization, lifetime extension, and capacity flexibility of the BESS can be achieved. Based on the equivalent model, the power flow of the battery module can be estimated without the need of input current sensor. Also, with the interleaved operation between the sub-converters, the current ripple of the output inductor can be reduced too. The computer simulations and hardware experimental results are shown to verify the performance of the proposed HGM-converter.

The recent rate of the expansion of graphene nanomaterials requires appropriate toxicological assessment for biomedical usage. The toxicity of graphene and its composites is a major hurdle. Here, we report the effects of reduced graphene oxide nanocomposites on mouse fibroblast (NCTC-929) cells with the aim for futuristic biomedical applications of our synthesized material such as wearable device. The rGO was prepared by modified Hummer’s method and conjugated in comparison with carbon nanotubes (CNT), silver nanoparticles, zinc oxide particles and polyurethane to form nanocomposites. The as-prepared nanocomposites were characterized using X-ray diffraction, Raman spectroscopy, transmission electron microscope, field emission scanning electron microscopy and EDX analysis. As expected, most of our purified nanocomposites did not show any cytotoxicity on NCTC-929 cells when cultured with different doses of the samples. The nanomaterials were biocompatible and the cells displayed a viability of 80% and more. However, the nanocomposites that were autoclaved prior to testing were toxic. The materials with ZnO conjugation showed a dose dependent toxicity. The composites that had CNTs conjugated with rGO (rGO3C) were toxic than compared to the rGO-CNT conjugated with silver nanoparticles (rGO6CAgNP and rGO3CAgNP). When these nanomaterials are explored for several other applications in vivo, their biocompatibility is a major factor to be considered.

The objective of this paper is to propose a seamless grid-connected inverter (SGI) for microgrid applications. The proposed SGI is able to operate in the grid-connected mode or the standalone mode. In order to smooth the transfer transition from the grid-connected mode to the standalone mode and to isolate the microgrid from the grid fault immediately via the static switch, three seamless transfer strategies are developed: 1) predetermined sinusoidal waveform detection (PSWD); 2) fast commutation current compensation (FCCC); and 3) predictive transfer voltage control (PTVC). The PSWD strategy is proposed to predict the normal voltage of utility grid for detecting the utility fault in few voltage samples. The proposed FCCC strategy is able to provide the required commutation current for the silicon controlled rectifier (SCR), so the turn-off time of the static switch could be minimized. The PTVC strategy is proposed to prevent the voltage drop or spike as well as to quickly reach the steady-state in the standalone mode. The computer simulations and hardware experimental results from a prototype system are presented to verify the performance of the proposed SGI.

A seven-step total synthesis of α-cyclopiazonic acid is reported from a commercially available 4-bromoindole. Salient feature of the work is the rapid formation of tetracyclic skeleton via a bioinspired [3 + 2] annulation to form the C/D rings.

Synthesis of nanostructures for industrial usage is a challenge issue since most of the scale up production is not economically suitable. Here we have described two efficient synthesis approaches for copper (II) oxide nanostructures. And, we have compared the methods with current published procedures in terms of time and its impact to the environments. Our simple and environmentally friendly synthesis procedures can produce various Cu (II) oxide nanostructures. We have successfully synthesis Cu (OH)2, CuO nanowire and CuO nanoparticles. And, they were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction spectroscopy (XRD), Field emission scanning electron microscopy (FESEM), We have also explored the potential of these nanostructure for future development on biomedical applications.

In this study, the simple sonochemical synthesis of functionalized carbon black (f-CB) anchored with tungsten carbide (WC) is used to prepare a novel electrocatalyst for the electrochemical detection of furazolidone (FU) by modifying screen-printed carbon electrodes (SPCE). X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy were utilized to investigate the crystal structure, surface morphology and elemental composition of the hybrid composite. The results confirmed the successful formation of uniformly distributed flake-like WC on the surface of f-CB. Due to its peculiar and outstanding morphological structure, an f-CB/WC/SPCE electrode has an enriched electroactive surface area of 0.4105 cm2. The electrocatalytic efficiency of furazolidone was studied using cyclic voltammetry and amperometric techniques. The f-CB/WC composite displayed an outstanding synergic effect in detecting the ultra-level presence of FU, with a limit of detection of around 0.6 nM and an ultra-dynamic range of 0.001–1150 μM, which outshone other reported FU sensors. Therefore, it is evident that the preparation method can be successfully applied to bovine albumin serum and pharmaceutical tablets with acceptable recovery.

Development of green technique for the fabrication of noble metal nanoparticles is of great importance in order to avoid the usage of toxic chemicals. In this strategy, gold nanoparticles (AuNPs) are synthesized at room temperature by using Camellia japonica leaf extract under room temperature. The successful formation of AuNPs was confirmed by various spectroscopic techniques including UV, FTIR, XRD and SEM studies. The resulting antimicrobial activity of the synthesized AuNPs stabilized in C. japonica is tested against seven different microbial strains such as Bacillus subtilis, Staphylococcus aureus, Streptococcus faecalis, Klebsiella pneumoniae, Pseudomonas aeruginosa, Escherichia coli and Candida albicans. The present study opens a new window for future synthesis of AuNPs via green technique. Keywords: Camellia japonica, Gold nanoparticles, Antimicrobial activity, Green synthesis

A compact and high-efficiency power converter is the main business of today’s power industry for server power applications. To achieve high efficiency with a low-output ripple, an interleaved phase-shift full-bridge (PSFB) converter is designed, built, and tested for server power applications in this study. In this paper, dynamic dead time control is proposed to reduce the switching loss in the light load condition. The proposed technique reduces the turn-off switching loss and allows a wide range of zero-voltage switching. Moreover, the current ripple of the output inductor can be reduced with the interleaved operation. To verify the theoretical analysis, the proposed PSFB converter is simulated, and a 3 kW prototype is constructed. The experimental results confirm that the conversion efficiency is as high as 97.2% at the rated power of 3 kW and 92.95% at the light load of 300 W. The experimental transient waveforms demonstrated that the voltage spike or drop is less than 2 V in the fast-fluctuating load conditions from 0% load to 60% load and 40% load to 100% load.

In this paper, a short-term wind speed prediction model, called CEEMDAN-SE-Improved PIO-GRNN, is proposed to optimize the accuracy of the short-term wind speed forecast. This model is established on account of the optimized General Regression Neural Network (GRNN) method optimized by three algorithms, which are Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (CEEMDAN), Sample Entropy (SE), and Pigeon Inspired Optimization (PIO), separately. Firstly, decomposing the original wind speed sequences into several subsequences with different complexity by CEEMDAN. Then, the complexity of each subsequence is judged by SE and the similar subsequences are combined into a new sequence to reduce the scale of calculation. Afterwards, the GRNN model optimized by improved PIO is used to predict each new sequence. Finally, the predicted results are superposed as the eventual predicted value. Implementing the prediction for the wind speed data of a wind field in north China within 30 days by applying the different prediction models, namely, GRNN, CEEMDAN-GRNN, Improved PIO-GRNN, and CEEMDAN-SE-Improved PIO-GRNN which are proposed in this paper. Comparing the prediction curves of different models with the fitting curve of the actual wind speed shows that the optimal fitting effect and minimum error value are included in CEEMDAN-SE-Improved PIO-GRNN model. Specifically, the values of mean squared error (MSE), mean absolute error (MAE) and weighted mean absolute percentage error (WMAPE) separately decrease by 0.6222, 0.3334, and 8.5766%, which compare with the single prediction model GRNN. Meanwhile, diebold-mariano (DM) test shows that the prediction ability of the two models is significantly different. The above statements indicate the proposed model does great advance in the precision of short-term wind speed prediction.

Different from the design of conventional permanent magnet (PM) motors, high-speed motors are primarily limited by rotor unbalanced radial forces, rotor power losses, and rotor mechanical strength. This paper aimed to propose a suitable PM motor with consideration of these design issues. First, the rotor radial force is minimized based on the selection of stator tooth numbers and windings. By designing a stator with even slots, the rotor radial force can be canceled, leading to better rotor strength at high speed. Second, rotor power losses proportional to rotor frequency are increased as motor speed increases. A two-dimensional sensitivity analysis is used to improve these losses. In addition, the rotor sleeve loss can be minimized to less than 8.3% of the total losses using slotless windings. Third, the trapezoidal drive can cause more than a 33% magnet loss due to additional armature flux harmonics. This drive reflected loss is also mitigated with slotless windings. In this paper, six PM motors with different tooth numbers, stator cores, and winding layouts are compared. All the design methods are verified based on nonlinear finite element analysis (FEA).

The effect of annealing temperature variance on magnesium ferrites (MgFe2O4) later anchored on reduced graphene oxide (rGO) forming hybrid nanocomposite is demonstrated and its electrochemical performance investigated by using a screen-printed carbon paste electrode (SPCE) for detection of the environmental hazardous phenolic compound 4-cyanophenol (4-CY). The MgFe2O4 (MFO–600 °C) displayed an enhanced charge transfer ratio with high conductivity and electrocatalytic activity. To confirm the structural and morphological parameters of the rGO-MFO-2 hybrid micro/nanocomposite, X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron microscopy (XPS), and field-emission electron microscopy (FE-EM) with EDX mapping have been utilized. The rGO/MFO-2/SPCE electrode displayed high catalytic performance in detecting 4-CY with good sensitivity of 6.836 μA μM−1 cm−2 in a working range 0.001 to 700 μM with a limit of detection of 0.0012 μM by using differential pulse voltammetry (DPV). This is achieved for the active interaction between rGO and MFO-2 active surface site areas resulting in good electrochemical activity and high electron transfer rate. Moreover, 4-CY detection has been performed in the presence of various interferents and through real-time analysis in samples like tap water, industrial river water, and fish which resulted in admirable recovery. Graphical abstract

Saliency-based position sensorless drive with the pulse width modulation (PWM) switching frequency injection can achieve the high position estimation bandwidth. However, in order to obtain the rotor position, multiple currents should be sampled every PWM cycle to calculate the saliency reflected current difference. Considering the low-cost inverter using shunt resistors for phase current sensing, it is not possible to obtain this saliency current difference because machine current can only be measured once the low-side switch is ON. To implement the PWM injection sensorless drive on shunt-based sensing inverters, this paper proposes two modified PWM voltage controls for the measurement of saliency reflected current difference. The first modified PWM is based on the asymmetric PWM for both the field-oriented control (FOC) and position estimation. This proposed PWM requires only a single interrupt service routine (ISR); however, the current total harmonic distortion (THD) is higher. By contrast, the second modified PWM consists of both discontinuous PWM (DPWM) for FOC and asymmetric PWM for the position estimation. Although two ISR’s are required for this proposed PWM pattern, the current THD is reduced through the separated PWM control. All the proposed PWM patterns are experimentally verified on an interior PM machine where the inverter with shunt resistors is used for current sensing.

Copper vanadate nanoparticles (Cu2V2O7) are synthesized by using a simple hydrothermal method and later anchored with sulfur-doped reduced graphene oxide (S-rGO) by using ultrasonication to form a hybrid nanocomposite. The synthesized composite underwent characterizations like X-ray diffraction analysis (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR), Dynamic ray scattering-Ultra violet–visible spectroscopy (DRS-UV–visible) and X-ray photoelectron spectroscopically revealed the triclinic pattern of the P 1 space group of α-Cu2V2O7 and the reduced oxygen deficiency state of metal centers (Cu+ or V4+) resulting with oxides of mixed-valence oxidative states and forming of Cu-O bond. Morphological analysis was carried out by using transmission electron microscopy (TEM) and Field emission scanning electron microscopy (FE-SEM) with elemental mapping and EDX analysis. Furthermore, a novel electrochemical sensor is prepared by using the hybrid sCu2V2O7/S-rGO nanocomposite on to a disposable screen-printed carbon paste electrode (SPCE) for electrochemical sensing of antiandrogen drug nilutamide (NLT). This report reveals excellent activity in determining NLT with a low detection limit of 0.00459 nM for the linear range of 0.001–15 μM with high sensitivity of 26.2605 µA µM−1 cm−2. Further, electrode performance showed appreciable performance in real-time monitoring of biological samples like human blood serum, urine samples.

Hybrid surgery (HS) allows surgeons to tailor fusion and arthroplasty in the treatment of multiple-level cervical disc degeneration. However, the decision making of selecting either ACDF or ADR for each level in three-level HS remains controversial and has not been fully investigated. This study was aimed to optimize three-level cervical hybrid constructs by systematically investigating their biomechanical properties and their effect on adjacent levels. A finite element model of cervical spine (C2-C7) was developed, and eight C3-C6 surgical models including six HS were constructed. The range of motion (ROM) in flexion, extension, lateral bending, and axial rotation under 2.0 Nm moments with 30 N follower load were simulated. The von Mises stress, strain energy at the adjacent intervertebral disc (IVD) and force at the adjacent facet were calculated. The ROM of the hybrid constructs and adjacent levels was close to that of the intact spine. HS with arthroplasty performed at C5-6 had better performance in terms of ROM reduction at the inferior adjacent level (C6-7). Moreover, C-D-D and 3ADR had best performance in reducing the von Mises stress and strain energy at C6-7. All HS reduced the facet burden at both C2-3 and C6-7 levels. However, the major drawback of HS revealed here is that the effect of C6-7 protection is at the cost of increased C2-3 IVD burden. In conclusion, we recommend C-D-D and 3ADR for patient with C3-C6 disc degeneration without predisposing C2-3 condition. C-C-D could be a good alternative with a lower medical cost. This analysis guides the decision making in three-level cervical HS before future cadaver studies or human clinical trials.

In this work, we synthesized a series of microcrystalline MnxN100−x-MOF-74 (N = Fe, Co and Ni) materials by a one-pot reaction. Powder X-ray diffraction (PXRD) patterns of MnxN100−x-MOF-74 matched well with those of single-metal MOF-74, and the scanning electron microscopy (SEM) images exhibited homogeneous nanocrystallites aggregated together. The amounts and dispersion of metals were analyzed by using inductively coupled plasma (ICP) and energy-dispersive X-ray spectroscopy (EDS), separately. MnxN100−x-MOF-74 could remain crystalline and efficiently catalyze the epoxidation of alkenes in DMF with NaHCO3 and 30% H2O2. In particular, Mn29.39Fe70.61-MOF-74 can achieve almost 100% conversion for styrene with 95.0% selectivity towards styrene oxide and be reused at least five times without loss of activity.

Electrochemically reduced graphene oxide wrapped copper nanoparticles (ERGO/Cu NPs) composite were successfully synthesized through cyclic voltammetry. Highly stable, enhanced electroactive CuNPs growth was optimized by using different electrolyte solutions for deposition such as aqueous 0.1 M H3BO3 (I), 0.1 M H2SO4 (II) and 0.1 M Na2SO4 (III) containing 0.05 M CuSO4. Furtherly, electrocatalytic activity of the as prepared electrodes (I, II, III) were studied by non-enzymatic glucose oxidation. Obviously, lower over potential of glucose oxidation was noticed at ERGO/Cu NPs (I) modified electrode with amplified anodic current response compared than that of other electrodes (II, III). Then, ERGO/CuNPs (I) composite was characterized by SEM, FESEM, EDAX, XRD, Raman spectroscopy and cyclic voltammetry. In addition, ERGO/Cu NPs (I) modified electrode possess excellent electrocatalytic performance towards glucose in terms of wide linear range from 0.14 μM to 5091 mM and lower limit of detection (LOD) 49 nM. Moreover, the fabricated sensor exhibits appreciable reproducibility, good stability and excellent selectivity. Furthermore, obtained real sample recovery results declare that the architecture sensor matrix could be a suitable platform for detection of glucose in human samples.

Transition metal chalcogenides (TMCs) have great potential in diverse electrochemical technologies owing to their unique characteristics. In the present work, we portray the design and synthesis of Vanadium selenide (V2Se9)/reduced graphene oxide (rGO) forming a two-dimensional (2D) hybrid nanocomposite via a simple hydrothermal method. The successfully synthesized nanocomposite underwent in-depth surface and morphological characterizations by XRD, Raman spectroscopy, XPS, TEM, STEM and its potential as an electro catalyst was investigated by using glassy carbon electrode (GCE) for the detection of 2,4,6-trichlorophenol (TCP). The structural features favored a high charge transfer ratio, high surface area as well as excellent conductivity and catalytic activity. The V2Se9/rGO/GCE modified electrode showed a low charge transfer resistance (Rct) of 54.057 Ω cm2, a decent detection limit (LOD) of 35.07 nM and a very high sensitivity of 22 μA μM−1 cm−2 in a working range of 0.001 μM–1150 μM. This is due to the active proton interaction, surface enhancement, and positive synergistic effect between rGO and V2Se9. The proposed sensor has good detection potential in agricultural soil, river water, fish, and beverage samples like wine and apple juice. The obtained results from our investigation would elucidate the application of the catalyst in electrochemical sensors.

A series of novel azobenzene-based dyes were designed and synthesized using azobenzene as the π-spacer unit to connect diarylamino and cyanoacetic acids for construction of the D–π–A conformation. The introduction of a thienyl into the anchor group (A) could lead to a red-shift in the absorption spectra and λonset of the dyes. When the diaryamino substituent was changed from methyl to methoxyl, a slight negative shift in the first oxidation peak could be observed. The spin density distribution of the cation radicals of the four dyes was also investigated. The qualitative order of the stability of these four cation radicals was found to be TA4 > TA3 > TA2 > TA1 in air. They were then employed as the sensitizer in organic dye-sensitized solar cells to achieve the highest power conversion efficiency (PCE) of 4.78% under AM 1.5 conditions. By systematically changing the donor and acceptor unit of these dyes, the new record on PCE with using azobenzene as the π-spacer unit was achieved.

This paper develops a digital measurement and control technology of grey predictor-based inverse hyperbolic sliding function for solar PV inverters. The advantage of inverse hyperbolic sliding function (IHSF) is very low sensitivity to system uncertainties. However, when a large parameter variation or a sudden external load interference is applied, the steady-state errors still occur in the IHSF controlled solar PV inverter and incur high total harmonic distortion (THD), even deteriorate control accuracy. To eliminate steady-state errors, a grey predictor is used for the prediction of voltage THD. Once a high voltage THD of the solar PV inverter output is detected and then measured by grey predictor, the tracking error of the IHSF controlled system will gradually decrease to zero, thus achieving zero steady-state errors. With the proposed measurement and control technology, a digital closed-loop solar PV inverter system will yield high-quality AC output voltage with low THD and fast dynamic response even under highly nonlinear loading. Experimental results for the solar PV inverter are performed in support of the proposed technology.

The objective of this paper is to propose a bidirectional single-stage grid-connected inverter (BSG-inverter) for the battery energy storage system. The proposed BSG-inverter is composed of multiple bidirectional buck–boost type dc–dc converters (BBCs) and a dc–ac unfolder. Advantages of the proposed BSG-inverter include: single-stage power conversion, low battery and dc-bus voltages, pulsating charging/discharging currents, and individual power control for each battery module. Therefore, the equalization, lifetime extension, and capacity flexibility of the battery energy storage system can be achieved. Based on the developed equations, the power flow of the battery system can be controlled without the need of input current sensor. Also, with the interleaved operation between BBCs, the current ripple of the output inductor can be reduced too. The computer simulations and hardware experimental results are shown to verify the performance of the proposed BSG-inverter.

A series of alcohols (methanol, ethanol and isopropyl alcohol) were added to poly(3,4-ethylenedioxythiophene): (polystyrene sulfonate) (PEDOT: PSS) aqueous solutions in order to manipulate the molecular structure of the PEDOT chains in PEDOT: PSS hole transporting materials (HTMs) and thus to improve the power conversion efficiency of CH3NH3PbI3 based solar cells. The structural and electronic characteristics of the resultant PEDOT: PSS HTMs were analyzed using atomic-force microscopy, contact angle measurement, Raman scattering spectrometry and photoelectron spectrometry. The properties of the PEDOT: PSS thin films could be controlled by tuning the viscosity of the PEDOT: PSS solutions. High viscosity PEDOT: PSS solutions resulted in linear structured PEDOT chains, which increased the work function of the PEDOT: PSS HTMs thereby improving the open-circuit voltage of the CH3NH3PbI3 solar cells. The surface roughness and surface free energy of the PEDOT: PSS HTMs influence the structural properties of CH3NH3PbI3 thin films, which determines the exciton dissociation at the CH3NH3PbI3/PEDOT: PSS interface (short-circuit current density) and the carrier recombination at the CH3NH3PbI3/[6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) interface (fill factor). In addition, it is predicted that the power conversion efficiency can be further improved by increasing the crystallinity of the CH3NH3PbI3 thin film.

Three N,N′ -diaryl-4-amino-azobenzene derivatives containing donor (D) and acceptor (A) moieties have been synthesized for light harvesting. Their optical and electronic characteristics have been analyzed to determine the optical band gap between highest occupied molecular orbital (HOMO) and lowest occupied molecular orbital (LUMO). The electrochemical properties and electrochemical redox potential of the triarylamines exhibited linear relationship with respect to the Hammett equation. The stability of the oxidation products and spectral changes with different applied potentials were monitored with UV–vis spectroelectrochemical investigations and DFT calculations. A solution-processed organic photovoltaic cell employing N,N′ -ditolyl-4-aminoazobenzene (DTAA) mixed with PC 60 BM produced a power conversion efficiency (PCE) of 0.28% under 1 sun illumination.

A series of nonpolar antisolvents (chlorobenzene, bromobenzene, iodobenzene and toluene) were used to assist in the formation of smooth and crystalline CH3NH3PbI3 thin films by a one-step spin-coating method. The structural, optical and excitonic characteristics of the resultant CH3NH3PI3 thin films were analyzed using an atomic-force microscope, X-ray diffractometer, absorbance spectrum, photoluminescence (PL) spectrum, time-resolved PL and temperature-dependent PL. The properties of the CH3NH3PbI3 thin films are dependent on the relative polarity and boiling point of the nonpolar antisolvents used in the washing treatment process. The interplay between nucleation (relative polarity) and crystal growth (boiling point) during the formation of CH3NH3PbI3 thin films influences the short-circuit current density (JSC) and power conversion efficiency (PCE) of the corresponding solar cells. The experimental results demonstrate that iodobenzene can be substituted for toluene as a more efficient antisolvent in the washing treatment process during the fabrication of CH3NH3PbI3 thin films. In addition, it is predicted that the JSC and PCE can be further improved by increasing the crystallinity of the CH3NH3PbI3 thin film.

This paper analyzes the saliency-based position estimation for the permanent magnet (PM) machine with non-sinusoidal inductance. Considering the saliency-based sensorless drive relying on the spatial information of machine inductance, an ideally sinusoidal inductance is assumed to estimate the rotor position. However in actual PM machines, non-sinusoidal inductances are typically resultant due to the stator slotting effect, rotor topology, and most importantly, the saturation caused by magnet flux and coil flux. In this paper, a systematic analysis of saliency-based position estimation errors caused by the non-sinusoidal inductance is proposed. It is shown that the saturation decreases d-q self-inductances while increases d-q mutual-inductances. In addition, secondary inductance harmonics increase as saturation increases. The saliency-based drive ultimately fails because of considerable position errors. This paper clearly defines the feasible drive operating area for highly saturated PM machines. An optimal current control strategy is developed to maintain the drive stability for full load operation. Finite element analysis (FEA) is used to simulate the inductance saturation at various load conditions. A 5kW interior PM (IPM) machine with highly non-sinusoidal inductance is analyzed.

In this paper, a step-up battery charger for the stand-alone wind power system is proposed. In general, maximum power point tracking (MPPT) is investigated to harvest the maximum wind energy. However, most of standalone type wind turbine systems adopt batteries and it is hard to apply a MPPT strategy on a battery-charging type wind turbine system. The proposed power converter can harvest the maximum power from the wind turbine while generating pulsating current for the battery bank. Based on the circuit analysis, the maximum power point tracking function is realized by the circuit parameter design of the power converter and the characteristics of wind turbine. Also, with the interleaved operation between the step-up power converters, the current ripple of the input can be reduced. Advantages of the proposed converter include: maximum power tracking, control circuit simplicity, low voltage stress, no current sensor, and high reliability. Hardware experimental results from a 100 W prototype circuit are presented to verify the performance of the proposed power converter.

This paper proposes a modified sinusoidal pulsewidth modulation (SPWM)control single-phase inverters for the tidal current generation system. In general, a two-stage configuration is used to convert the generating AC power from the tidal current generator to DC power by a rectifier and transfer the DC power into AC power by an inverter to provide a stable voltage source. It is noticed that a small size capacitor of the rectifier is possible and the discontinuous current can be improved. However, a small size capacitor implies the higher voltage ripple and results in a lots of low-order voltage harmonics of the inverter with traditional SPWM control. Therefore, a modified modulation control strategy is developed in this paper. The proposed inverter has lower total harmonic distortion (THD)of the output voltage with high input voltage ripple. The low-order harmonics of output voltage can be reduced effectively and the THD is less than 2.5% in the experiments.

Here, we developed a novel organic semiconductor of 2,7-di(anthracen-2-yl)naphthalene (2,7-DAN), which not only exhibits outstanding hole-transport with a mobility of 3.3 cm2 V-1 s-1 but also shows a high photoresponsivity of 8000 A W-1 with detectivity as high as 1.2 × 1014 Jones. Most importantly, optical memory transistors (OMTs) based on it display an excellent memory effect due to the inhomogeneity (nanosprouts) of the 2,7-DAN film only, different from traditional strategies towards memory devices like the application of a floating gate layer, an electret layer or a photochromic molecule. The findings distinctly make 2,7-DAN an excellent candidate for high performance nonvolatile OMTs with a simpler structure.

In the present work, multiple applications of natural clay loaded Samarium molybdate for photodegradation, sensing and antibacterial activity were analyzed. The clay-based materials have attracted great attention as they show good application prospects for environmental remediation. We developed natural clay loaded Sm2MoO6 (CSm2MoO6) nanocomposite, hydrothermally and characterized by XRD, SEM, HR-TEM, FT-IR and optical studies. XRD pattern of CSm2MoO6 exhibits peaks at 19.60, 27.80, 35.60 and 62.40 corresponding to clay and Sm2MoO6 peaks clearly indicates the formation of natural clay conjugated with Sm2MoO6. SEM image of the natural clay doped CSm2MoO6 nanoparticle shows a homogeneous distribution of spherical Sm2MoO6on nanoflakes of clay material. HR-TEM images reveal that the average particle size is 50 nm. Loading of natural clay material increased the visible absorption of Sm2MoO6 by reducing the band gap from 3.82 to 2.39 eV. Decomposition of 20 ppm of Metronidazole (MNZ) was 95% with 60 mg of CSm2MoO6 in 100 min of visible light illumination. Hydroxyl radicals played the main role for photodegradation of MNZ. Electrochemical analysis revealed that the oxidation peak current of 4-aminophenol has increased with a high potential at pH 6.0 and CSm2MoO6/SPCE electrode has an advantage of low detection limit of 0.005 μ M and a long linear range of 2949.72 μ M with a sensitivity of 5.29301 μ M. The synthesized nanocomposite has a significant bactericidal activity against Bacillus subtilis, Staphylococcus aureus, Proteus mirabilis, Bacteroides fragilis, E. coli and Candida albicans. These results make this green catalyst potential for multiple applications.

Rare-earth metal vanadate has gained much interest in recent years due to its excellent catalytic properties and chemical stability in electrochemical sensors. In this study, we have explored the electrochemical activity of graphitic-carbon nitride (g-C3N4) and hierarchical 3D cerium vanadate (CeVO4) by using screen printed carbon paste electrode (SPCE) for detection of mesalazine (MEZ). Successfully, g-C3N4 and CeVO4 were synthesized by using a simple hydrothermal process, and then to form a nanocomposite ultrasonication procedure is approached. To confirm the structural and morphological parameters X-ray diffraction (XRD), X-ray photoelectron spectroscopy, Field-emission scanning electron microscopy (FE-SEM), Transmission electron microscopy (TEM) is being utilized. The g-C3N4/CeVO4/SPCE modified electrode has exhibited superior electrocatalytic performance in detecting MEZ with lower Rct value and with the high active surface area when compared with other electrodes. The prepared sensor has shown good sensitivity 18.92 μA μM−1 cm−2 and with a huge working range of 0.002−380 μM, with a promising trace-level limit of detection of about 0.00547 μM by using differential pulse voltammetry (DPV). Henceforth, g-C3N4/CeVO4/SPCE was carried out to subject real-time application in detecting MEZ in various biological, river water, and pharmaceutical samples which resulted in excellent recovery stating the chosen sensor is applicable in real-time analysis.

Prostate cancer is one of the major causes of death around the globe leading to cancer deaths in the US standing at a second position. Flutamide is one of the important drugs which is utilized in clinical diagnosis. Even though over usage and improper discharge leads to very serious harm to both living and environmental bodies. In this aspect developing a sensor for ultra-trace level detection of flutamide is very much indeed with selectivity, stability, and reproducibility. Herein, we report a facile synthesis of hexagonal Sn doped zinc oxide (Sn-ZnO) anchored on reduced graphene oxide (rGO) hybrid nanocomposite in discriminating reduction of flutamide. As per prepared Sn-ZnO/rGO nanocomposite has exhibited good catalytic performance when compared to bare and other modified electrodes. Resulting in inactive sites, large surface areas, synergic effects, and crystalline growths. Noticeable merits include the wide linear range of 0.01 to 170 µM and Limit of detection (LOD) of 7.3 nM with an excellent sensitivity of 14.10 µA µM−1 cm−2 and satisfying stability. The modified electrode was successfully applied as a real-time analysis in both biological and water bodies with promising recoveries.

The aim of the present research is to determine the optimal process of WC-10Co and WC(90 wt%)-Co(10-X wt%)-Cr3C2(X wt%)-cemented alloys, especially as related to their microstructural, magnetic and mechanical properties. In this work, different temperatures (1280 °C, 1320 °C, 1360 °C and 1400 °C) are explored in order to investigate the optimal parameters of the WC-10Co alloys. The influence on the WC-Co-cemented alloys of adding Cr3C2 powder is also evaluated. The experimental results show the optimal sintering temperature of the WC-10Co-cemented alloys as 1360 °C, with the WC-9.25Co-0.75Cr3C2-cemented alloys possessing the smallest grain size (480 nm) and a relatively higher hardness (93.23 HRA) after 1360 °C sintering for 1 h. It is also shown that the increase in the Cr3C2 content into the cemented alloys is effective in refining the WC grains and obtaining higher coercive force values.

Metallic composite materials are mainly manufactured by powder metallurgy (PM) or casting, with reinforced ceramic particulates dispersed in a metal matrix. The current study presents an investigation with respect to simultaneously gas-atomized spherical Ti/TiC composite powders. Various analytical methods are used to characterize the gas-atomized Ti/TiC composite powders, including XRD, laser particle size analysis, flow rate tests, apparent density and tap density tests, SEM, and alike. The spherical Ti/TiC composite powders will be further laser sintered at the next stage to utilize mechanical properties testing.

Two diketopyrrolopyrrole (DPP) containing D–π–A organic dyes, named as TEDBn and TEDTh were prepared. Their optical, electrochemical and photophysical properties were investigated and their application in dye-sensitized solar cells (DSCs) was demonstrated. The broaden absorption and low-energy λ max of DPP containing dyes were contributed from DPP bridge and EDOT π-conjugated moiety. Compared to TEDTh, TEDBn has smaller absorption coefficient and higher optical bandgap. Nevertheless the power conversion efficiency (PCE) of TEDBn based DSC is 7.2% which is larger than that of TEDTh based DSC and 90% of N719 based cell. The higher PCE of TEDBn based device originates from both higher open-circuit voltage (V OC ) and short-circuit current (J SC ). Femtosecond time-resolved photoluminescence data show that the electron injection at TEDBn/TiO 2 is more efficient than that at TEDTh/TiO 2 interface, resulting in higher J SC (and IPCE) of TEDBn based DSC. Density function theory (DFT) calculations revealed that TEDBn is a linear structure which leads to higher dye loading on TiO 2 than TEDTh which featured a bend conformation, better TiO 2 surface coverage, resulting in larger V OC . Therefore, the overall efficiency of the cell sensitized by TEDBn is better than that the devices based on TEDTh.

In order to improve the accuracy of wind power prediction and ensure the effective utilization of wind energy, a short-term wind power prediction model based on variational mode decomposition (VMD) and an extreme learning machine (ELM) optimized by an improved grey wolf optimization (GWO) algorithm is proposed. The original wind power sequence is decomposed into series of modal components with different center frequencies by the VMD method and some new sequences are obtained by phase space reconstruction (PSR). Then, the ELM model is established for different new time series, and the improved GWO algorithm is used to optimize its parameters. Finally, the output results are weighted and merged as the final predicted value of wind power. The root-mean-square error (RMSE), mean absolute error (MAE), and mean absolute percentage error (MAPE) of the proposed VMD-improved GWO-ELM prediction model in the paper are 5.9113%, 4.6219%, and 13.01% respectively, which are better than these of ELM, back propagation (BP), and the improved GWO-ELM model. The simulation results show that the proposed model has higher prediction accuracy than other models in short-term wind power prediction.

On account of unique characteristics, the integration of metal-organic frameworks as active materials in electronic devices attracts more and more attention. The film thickness, uniformity, area, and roughness are all fatal factors limiting the development of electrical and optoelectronic applications. However, research focused on ultrathin free-standing films is in its infancy. Herein, a new method, vapor-induced method, is designed to construct centimeter-sized Ni3 (HITP)2 films with well-controlled thickness (7, 40, and 92 nm) and conductivity (0.85, 2.23, and 22.83 S m-1 ). Further, traditional transfer methods are tactfully applied to metal-organic graphene analogue (MOGA) films. In order to maintain the integrity of films, substrates are raised up from bottom of water to hold up films. The stripping method greatly improves the surface roughness Rq (root mean square roughness) without loss of conductivity and endows the film with excellent elasticity and flexibility. After 1000 buckling cycles, the conductance shows no obvious decrease. Therefore, the work may open up a new avenue for flexible electronic and magnetic devices based on MOGA.

A graded fullerene derivative thin film was used as a dual-functional electron transport layer (ETL) in CH3NH3PbI3 (MAPbI3) solar cells, to improve the fill factor (FF) and device stability. The graded ETL was made by mixing phenyl-C61-butyric acid methyl ester (PCBM) molecules and C60-diphenylmethanofullerene-oligoether (C60-DPM-OE) molecules using the spin-coating method. The formation of the graded ETLs can be due to the phase separation between hydrophobic PCBM and hydrophilic C60-DPM-OE, which was confirmed by XPS depth-profile analysis and an electron energy-loss spectroscope. Comprehensive studies were carried out to explore the characteristics of the graded ETLs in MAPbI3 solar cells, including the surface properties, electronic energy levels, molecular packing properties and energy transfer dynamics. The elimination of the s-shape in the current density–voltage curves results in an increase in the FF, which originates from the smooth contact between the C60-DPM-OE and hydrophilic MAPbI3 and the formation of the more ordered ETL. There was an improvement in device stability mainly due to the decrease in the photothermal induced morphology change of the graded ETLs fabricated from two fullerene derivatives with distinct hydrophilicity. Consequently, such a graded ETL provides dual-functional capabilities for the realization of stable high-performance MAPbI3 solar cells.

As for heterogeneous catalysis, the activity and selectivity are two key factors for evaluating catalysts. Metal-organic frameworks (MOFs) as selectivity regulators for catalytic reaction have attracted much attention, especially MOFs and metal nanoparticles (NPs) shelled structures, e.g., MOFs@NPs@MOFs. Nevertheless, the hydrophilic MOFs shell is challenging to gather hydrophobic reactants. Here, we innovate a new and viable approach to solve this problem. By employing conjugated micro- and mesoporous polymers with iron(Ⅲ) porphyrin (FeP-CMPs) as the new shell, MIL-101@Pt@FeP-CMP was fabricated firstly, which not only is hydrophobic and porous to enrich reactants, but also possesses iron sites to activate C=O bond and thereby regulate the selectivity for cinnamyl alcohol in hydrogenation of cinnamaldehyde. Interestingly, MIL-101(Cr)@Pt@FeP-CMPsponge can reach ultrahigh turnover frequency (TOF) as high as 1516.1 h-1 with 97.3 % selectivity towards cinnamyl alcohol and 97.6 % conversion. The results open up a new avenue for decorating and protecting MOFs and will play an important role in both academia and industry.

Traditional drug delivery systems, using invasive, transdermal, and oral routes, are limited by various factors, such as the digestive system environment, skin protection, and sensory nerve stimulation. To improve the drug delivery system, we fabricated a polysaccharide-based, dissolvable microneedle-based array, which combines the advantages of both invasive and transdermal delivery systems, and promises to be an innovative solution for minimally invasive drug delivery. In this study, we designed a reusable aluminum mold that greatly improved the efficiency and convenience of microneedle fabrication. Physical characterization of the polysaccharides, individual or mixed at different ratios, was performed to identify a suitable molecule to fabricate the dissolvable microneedle. We used a vacuum deposition-based micro-molding method at low temperature to fabricate the model. Using a series of checkpoints from material into product, a systematic feedback mechanism was built into the "all-in-one" fabrication step, which helped to improve production yields. The physical properties of the fabricated microneedle were assessed. The cytotoxicity analysis and animal testing of the microneedle demonstrated the safety and compatibility of the microneedle, and the successful penetration and effective release of a model protein.

The objective of this paper is to propose a reactive power control strategy of the grid-connected inverter for microgrid application. The proposed strategy can actively participate to regulate the voltage, realize the islanding detection, reduce the power quality impact of islanding detection and simplify the controller design. When the distributed energy resource (DR) of the microgrid system generates power to the grid, it may cause the voltage of the point of common couple (PCC) rising. The proposed strategy is to use the grid-connected inverter with the reactive current control to regulate the PCC voltage. Meanwhile, the reactive current disturbance is used to detect the variable frequency in islanding condition. Also, the experimental results are shown to confirm the validity of the design concept of the proposed strategy.

Hydroquinone (HQ), a phenolic compound is expansively used in many industrial applications and due to the utilization of HQ, water pollution tragedies frequently found by the improper handling and accidental outflows. When HQ is adsorbed directly through the skin that create toxic effects to human by affecting kidney, liver, lungs, and urinary tract and hence, a highly selective and sensitive technique is required for its quantification. Herein, we have developed the ultrasonic synthesis of copper oxide nanoflakes (CuO-NFs) using ultrasonic bath (20 kHz, 100 W) and successfully employed for the sensitive detection of the environmental hazardous pollutant HQ. The formed CuO-NFs were confirmed by X-ray diffraction, field emission scanning electron microscopy (FE-SEM), FT-IR spectroscopy and UV–visible spectroscopy and fabricated with the screen-printed carbon electrode (SPCE). The SEM images exhibited the uniform CuO-NFs with an average width of 85 nm. The linker-free CuO-NFs fabricated electrode showed the appropriate wide range of concentrations from 0.1 to 1400 µM and the limit of detection was found to be 10.4 nM towards HQ. The fabricated sensor having long term stability and sensitivity was successfully applied for the environmental and commercial real sample analysis and exhibited good recovery percentage, implying that the SPCE/CuO-NFs is an economically viable and benign robust scaffold for the determination of HQ.

Here, the synthesis of a wafer-scale ultrathin 2D imine polymer (2DP) film with controllable thickness from simple benzene-1,3,5-tricarbaldehyde (BTA) and p-phenylenediamine (PDA) building blocks is reported using a Schiff base polycondensation reaction at the air-water interface. The synthesized freestanding 2DP films are porous, insulating, and more importantly, covalently linked, which is ideally suited for nonvolatile memristors that use a conductive filament mechanism. These devices exhibit excellent switching performance with high reliability and reproducibility, with on/off ratios in the range of 102 to 105 depending on the thickness of the film. In addition, the endurance and data retention capability of 2DP-based nonvolatile resistive memristors are up to 200 cycles and 8 × 104 s under constant voltage stress at 0.1 V. The intrinsic flexibility of the covalent organic polymer enables the fabrication of a flexible memory device on a polyimide film, which exhibits as reliable memory performance as that on the rigid substrate. Moreover, the 2DP-based memory device shows outstanding thermal stability and organic solvent resistance, which are desirable properties for applications in wearable devices.

The objective of this paper is to propose a cascaded multi-level inverter for battery energy storage systems. This paper proposes the implementation of the multi-level inverter system having five H-bridge structure inverter modules connected in series with distinct linked batteries. Based on the developed controller, the proposed inverter system can uninterruptedly operate to overcome the disadvantage of power downtime while one of the battery modules is under fault condition or maintenance. By taking advantage of the hot swappable capability, not only the flexibility and fault tolerance of the proposed system can be improved, but the capacity expansion is possible for the battery energy storage systems in microgrids. The control strategy is implemented on a 32-bit floating point TMS320F28335 DSP and tested in standalone mode and grid-connected mode. Finally, the simulations and hardware experimental results from the prototype system are presented to verify the validity of the proposed inverter.

Differences in cultural and the convenience of obtaining information expose a significant difference in the effectiveness of learning between Indigenous and non-Indigenous students. Indigenous students frequently misunderstand the content and examples provided by the teachers, and cultural constraint is an important factor in learning. This study created a new learning system with information technology for Indigenous students. We established and integrated indigenous culture into a cloud-based Indigenous elementary school e-learning system. Students can read e- books online and study new vocabularies with teachers' explanations. Moreover, students can engage in exercises after completing very segment of a whole lesson. After finishing the course, students take an examination for evaluating the learning effects. All examples used in the e-books match the students' culture and lifestyle and can facilitate their understanding of the contents. We administered the test teaching course at 4 aboriginal elementary schools and found that the average score has improved significantly(p

Owing to the limited availability of natural sources, the widespread demand of the flavouring, perfume and pharmaceutical industries for unsaturated alcohols is met by producing them from α,β-unsaturated aldehydes, through the selective hydrogenation of the carbon-oxygen group (in preference to the carbon-carbon group). However, developing effective catalysts for this transformation is challenging, because hydrogenation of the carbon-carbon group is thermodynamically favoured. This difficulty is particularly relevant for one major category of heterogeneous catalyst: metal nanoparticles supported on metal oxides. These systems are generally incapable of significantly enhancing the selectivity towards thermodynamically unfavoured reactions, because only the edges of nanoparticles that are in direct contact with the metal-oxide support possess selective catalytic properties; most of the exposed nanoparticle surfaces do not. This has inspired the use of metal-organic frameworks (MOFs) to encapsulate metal nanoparticles within their layers or inside their channels, to influence the activity of the entire nanoparticle surface while maintaining efficient reactant and product transport owing to the porous nature of the material. Here we show that MOFs can also serve as effective selectivity regulators for the hydrogenation of α,β-unsaturated aldehydes. Sandwiching platinum nanoparticles between an inner core and an outer shell composed of an MOF with metal nodes of Fe

In this experiment, we use carbon black as counter electrodes to replace the conventional platinum electrodes in dye sensitized solar cell (DSSC). The electrical properties and device efficiency with carbon black counter electrodes with various concentrations, and under the annealing temperature from 100 to 500 °C are discussed. After the proper annealing process, the conductivity and redoxing ability of the carbon black is improved, resulted in the enhancement of the electrical characteristics, especially fill factor, of the device. The highest device efficiency was 7.28% with the J SC of 14.70 mA/cm2, V OC of 0.75 V, and fill factor of 0.67 under 1-sun AM 1.5G solar illumination.