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In recent years, the penetration of renewable power generations into the electrical grid has substantially increased. Continuous deployment of power electronic-based distributed generations and the reduction of traditional synchronous machines with their essential dynamics in modern power networks are very critical in this change. The use of power electronic inverters leads to the dissociation of sources and loads and lowering the power system inertia. Under power imbalance, this drop causes an elevated rate of change in frequency and frequency divergences, which has a notable impact on the system’s frequency stability. As a result, enhanced control techniques for grid-tied electronic converters are required to secure the power system’s stability and support. The virtual-synchronous generator (VSG) control is used to mimic the dynamics of a rotating synchronous generator and improve the power system’s stability. In this article, the problems of such low-inertia power systems, as well as the VSG technologies, are explored. This research also looks at different control orders and strategies for virtual-synchronous generators (VSG). In addition, the utilization of energy storage and critical matters in VSG and further research recommendations are explained.

This is a second part of iron oxide nanoparticles synthesis by co-precipitation method with various PH values. This study includes stabilizing iron oxide nanoparticles with dextran of molecular weight 10000 Da by aqueous route, then study its characteristics with AFM, FTIR and VSM also using the stabilized material as a contrast agent in T1-weighted image then compare the contrast enhancement with gadolinium based commercially available contrast agent (Magnevist TM ). Ph values were (7,11,14), all samples were injected to mice bodies then imaged with MRI best result of T1 contrast enhancement was obtained from sample with Ph 14 compared with gadolinium-based T1 contrast agent with no toxic effects.

The paper presents an applied study on the optimization of the production process within a company in the leather industry organized in the Lohn system. The research aims to identify the main losses in the technological flow, with a focus on the leather cutting operation, considered the main source of non-conformities, additional times and high operational costs. The methodology used includes process analysis through Value Stream Mapping (VSM), equipment performance evaluation through the OEE indicator, cause-effect analysis for the prioritization of critical factors. The results highlight a reduced utilization of production capacity, high waiting and transfer times, as well as an overall equipment efficiency of 75%, below the level considered optimal in the industry. The proposed solution, the implementation of an automated cutting machine, led to a reduction in total production time by 27.7%, an increase in OEE to over 85%, and a uniform production flow. The study confirms the efficiency of applying Lean Manufacturing principles in an industrial environment specific to Lohn production and highlights the significant impact of automation on operational performance.

In the paper, the method of the production process improvement with the use of lean production tools has been presented. The Value Stream Mapping (VSM) for the cardboard packaging production process has been presented. On the basis of the current state map (CSM), areas for improvement have been designated – 5 organizational changes of the process were marked out. To minimize the three basic losses excessive storage, unnecessary movement and delays, the changes were introduced in the method of inter-operative transport, supervision of the storage condition (input and output of the process), control at the processing operation and the use of a production loop. As a result of the changes, it is possible to shorten the process time, shorten the total time of operations adding value and reduce the number of non-compliant products.

CoO/Co3O4 nanoparticles (NPs) were synthesized by using a fresh egg white-assisted combustion method which acts as a new approach for green synthesis of this composite. This method was carried out by the direct heat of cobalt precursor with egg white at low temperature for very short period. In fact, this route is a novel, cheap and appropriate technique yielding nanoparticle-based materials. CoO/Co3O4 nanoparticles were characterized by examining the structure and identifying the elements and determining the morphology via XRD, FTIR, SEM, EDS and TEM techniques. The sample magnetic observations were measured through the use of a vibrating sample magnetometer (VSM). The results of XRD, EDS, SEM and TEM confirmed the positive synthesis of the cubic CoO/Co3O4 NPs with sponge crystals which proceed. For the as synthesized composite, 57.75 m2/g, 0.0148 cc/g and 10.31 nm were identified to be the SBET, Vp and ȓ, respectively. The cobalt oxide particles in their nature were polycrystalline, and the crystallite sizes varied from 10 to 20 nm. The magnetic measurement showed that the prepared nanocomposite displays room temperature ferromagnetism with an optimum value, 3.45 emu/g, of saturation magnetization.

The Integral Ergonomic-Value Stream Mapping (Ergo-VSM) methodology is introduced in this study, which is tailored for the metal-mechanic sector and aims to assess the operational and ergonomic conditions of production processes. The methodology is designed to identify ergonomic risks and propose an improvement plan to increase productivity by integrating ergonomic measurement instruments aligned with official standards and lean manufacturing tools such as VSM and Kaizen. The study, which was conducted in a metal-mechanical MSME (micro, small and medium enterprises), resulted in an 11.8% overall improvement in psychosocial risk factors, a 4.4% increase in productivity with a 1.96-h reduction in cycle time, and a 20% decrease in reported quality rejections. Notably, the study shows that the Integral Ergo-VSM can be implemented in a variety of organizational contexts, ensuring adaptability without jeopardizing the methodology’s core objectives.

Nanoparticles of Co 0.5 Cd 0.5 Fe 2 O 4 have been fabricated using a typical sol–gel combustion technique. X-ray diffraction (XRD), field emotion-scanning electron microscopy (FE-SEM), energy dispersive spectroscopy, Raman spectroscopy and vibrating sample magnetometer measurements were used to study the structure, morphology and magnetic characteristics of ferrite nanoparticles at varied calcination temperatures. The electrical characteristics of the structure are calculated from the first principles using the GGA approach in density functional theory. The X-ray analysis of calcined samples revealed the formation of the spinel fcc crystalline phase was unaffected by the increment in calcination temperature. Due to the presence of cubic cadmium oxide (CdO), several low-diffraction peaks with the symbol * are present. As calcination temperature rises, the average crystal size increases from 20.34 to 21.94 nm. The FE-SEM images indicated a porosity structure and agglomerations caused by the interaction of uniform magnetic nanoparticles. The compositional analysis of the Co 0.5 Cd 0.5 Fe 2 O 4 sample reveals the existence of desired constituents and the elimination of all undesirable precursors. Raman spectroscopy proved spinel ferrite nanoparticles include tetrahedral (A) sites and octahedral (B) sites. The magnetic hysteresis curves demonstrate the ferromagnetic nature, and it was observed that calcination temperatures significantly impacted the magnetic characteristics. As calcination temperature increased, saturation and remanence magnetization decreased, and inter-sub-lattice (A–B) super-exchange interactions were slightly more pronounced in smaller particles than in larger ones. Coercivity increases as calcination temperature rises. This can be attributed to the increase in particle size within the singular domain region. In addition, theoretical results (band structures) indicate that cobalt-cadmium ferrite possesses half-metallic properties.

Wet-chemical co-precipitation was used to create Co 0.5 Mg x Cu 0.5−x Fe 2 O 4 nano-ferrites (x = 0.0, 0.2, 0.3, and 0.4). XRD, FT-IR, HRTEM, and EDX analyses were used to confirm each sample’s single-phase spinel cubic crystal structure. The crystallite size was calculated from the XRD data and determined to be between (11.1570 and 16.1457 nm), with a lattice constant between (8.359 to 8.387Å). The two absorption bands found in the FTIR data were utilized to show metal cation and oxygen bond stretching at tetrahedral and octahedral positions, as well as to calculate the elastic moduli. The elemental composition and structural behavior of every sample were examined using FE-SEM and EDS. The magnetic parameters were also estimated based on the VSM data, the contribution of magnetic anisotropy (K), and the magnetic interaction by Neel’s and Y-K-type magnetism modify as the Mg 2+ ion substitution increases, thus we must consider how this variation in cation distribution affects all of these factors. As per the ferromagnet theory, ions originating from the magnetic tetrahedral A and octahedral B sites engage in super-exchange interactions with one another. Anti-ferromagnetic alignment occurs as a result (M B -M A ). Magnetization occurs as a result.

Pure nickel ferrite nanoparticles (NiFe 2 O 4 NPs) were prepared by the solvothermal method. Different concentrations of NiFe 2 O 4 were added to PVDF/PEO blend to prepare the PVDF/PEO-NiFe 2 O 4 nanocomposite films. The films were characterized using different techniques in detail. Pure NiFe 2 O 4 NPs images have a semispherical shape and roundness of the edges, with average particle size ~ 4.3–8.8 nm, and polycrystalline structure. Pure NiFe 2 O 4 NPs show that micrometrical agglomeration suggests the presence of pore-free crystallites on the surface. The spectroscopic techniques such as XRD, FTIR, and UV–visible have confirmed the interaction between PVDF/PEO and NiFe 2 O 4 NPs. Still, the nanocomposites exhibit a smooth surface with typical spherulitic clusters revealing the semi-crystalline structure of the PVDF/PEO-NiFe 2 O 4 nanocomposites. The values of ε ′ and ε ″ were increased as an increase of NiFe 2 O 4 due to the high value of dielectric permittivity of NiFe 2 O 4 . The appearance of semi-circles in the plot of M ″ with Log confirms the single phase of the samples. The dielectric measurements show that M ′ is inversely proportional to ε ′. At higher temperatures, M ′ levels off at frequencies higher than those at lower temperatures because the relaxation processes were spread over a range of frequencies. The values of saturation magnetization of PVDF/PEO-NiFe 2 O 4 films were linearly increased as an increase of NiFe 2 O 4 indicates improvement in the magnetic vector arrangement. Due to the enhancement of the magnetic properties, they can further exploit the films for magnetic applications.

Herein, we report the synthesis of nanoparticles and doping of Cu-doped Co–Zn ferrites using the auto-combustion sol–gel synthesis technique. X-ray diffraction studies confirmed the single-phase structure of the samples with space group Fd3m and crystallite size in the range of 20.57–32.69 nm. Transmission electron microscopy micrographs and selected area electron diffraction patterns confirmed the polycrystalline nature of the ferrite nanoparticles. Energy-dispersive X-ray spectroscopy revealed the elemental composition in the absence of any impurity phases. Fourier-transform infrared studies showed the presence of two prominent peaks at approximately 420 cm−1 and 580 cm−1, showing metal–oxygen stretching and the formation of ferrite composite. X-ray photoelectron spectroscopy was employed to determine the oxidation states of Fe, Co, Zn, and Cu and O vacancies based on which cationic distributions at tetrahedral and octahedral sites are proposed. Dielectric spectroscopy showed that the samples exhibit Maxwell–Wagner interfacial polarization, which decreases as the frequency of the applied field increases. The dielectric loss of the samples was less than 1, confirming that the samples can be used for the fabrication of multilayer inductor chips. The ac conductivity of the samples increased with increasing doping and with frequency, and this has been explained by the hopping model. The hysteresis loops revealed that coercivity decreases slightly with doping, while the highest saturation magnetization of 55.61 emu/g was obtained when x = 0.1. The magnetic anisotropic constant was found to be less than 0.5, which suggests that the samples exhibit uniaxial anisotropy rather than cubic anisotropy. The squareness ratio indicates that the samples are useful in high-frequency applications.