Variation Of Cell Parameters Research Articles

Dynamic model and robust control for the PEM fuel cell systems

In response to the escalating challenges posed by climate change, the global energy sector has witnessed a paradigm shift towards sustainable alternatives. The promising fuel cell technology known as the proton exchange membrane fuel cell (PEMFC) has found widespread use in a variety of mobile and stationary applications. This paper presents a super-twisting sliding mode (STSM) control for maximum power point tracking (MPPT) on the proton exchange membrane fuel cell (PEMFC) system incorporated floating interleaved boost converter (FIBC). This work aims to extract the maximum power from the PEMFC by means of robust control in conjunction with FIBC to improve current ripple. The proposed controller is designed for the PEMFC system by combining the STSM and MPPT methods. The designed MPPT control tracks down the maximum power point of the system, and the corresponding current values act as the reference values for the STSM controller. The results show that incorporating the PEMFC with the FIBC can result in current ripple reduction when compared with a traditional interleaved boost converter (IBC). The obtained results demonstrate the capability of the PEMFC closed-loop control system to maintain the system's robustness under fuel cell parameter variations.

Deriving representative load profiles for battery simulation: The use case of system imbalances induced by cell-to-cell variations

Intrinsic battery cell parameter variations and their impact on the overall system behavior is topic of many experimental and simulative research papers. Usually, studies use short operational profiles to measure the extent of behavior inhomogeneities. However, load profile choices highly influence the extent of differences between each cell’s behavior. Simultaneously, actual vehicle usage history is high-dimensional. Until now, studies lack the framework to derive representative load profiles to reduce complexity for simulations measuring cell-to-cell variation effects. We propose the usage of micro-trip representations to synthesize suitable load profiles. By augmenting State-of-the-Art methods with a battery-specific autoregressive generation algorithm, we can compress high-dimensional vehicle history information into significantly shorter load profiles. During synthetization of trip sequences, signal consistency and representativeness are ensured. The obtained framework enables realistic battery design choices.

Clinical Application of Reticulocyte Maturity Indices in Early Diagnosis of Iron Deficiency Anemia in the First Trimester of Pregnancy

Background: Iron deficiency anemia (IDA) is a prevalent global health issue, particularly affecting pregnant females due to increased iron demands during pregnancy. In Pakistan, IDA remains a significant concern, posing challenges to maternal and child health. Early detection and management of iron deficiency are crucial for improving pregnancy outcomes.
 Objective: This study aims to investigate the iron status and associated hematological parameters among pregnant females during the first trimester in Islamabad, Pakistan.
 Methodology : This cross-sectional study, conducted in collaboration with the Pakistan Atomic Energy Commission (PAEC) and the Pakistan Institute of Medical Sciences (PIMS), aimed to investigate the iron status among first-trimester pregnant females in Islamabad, Pakistan.Laboratory investigations encompassed hemoglobin and serum ferritin assays, reticulocyte counts, and other red blood cell parameters. Participants were categorized into distinct iron status groups based on these evaluations. Utilizing SPSS version 25, statistical analysis followed ethical protocols, striving to uncover discrepancies in hematological parameters across the various iron status groups.
 Results : Among 340 first-trimester pregnant women, three iron status groups were identified. Group 1 (n = 102) had low ferritin despite normal Hb, with elevated immature reticulocytes. Group 2 (n = 150) showed normal iron parameters, while Group 3 (n = 88) had high reticulocyte counts. Group 2 exhibited superior erythrocyte indices and higher ferritin levels than Groups 1 and 3. Group 3 displayed the poorest indices and elevated immature reticulocytes. These findings highlight variations in iron status and reticulocyte maturation among pregnant women.
 Conclusion: This study underscores the high prevalence of iron deficiency anemia among first-trimester pregnant females in Islamabad, Pakistan. Variations in red blood cell parameters and serum ferritin levels highlight the importance of early iron status assessment for optimizing maternal and foetal health outcomes.

Scanning Precession Electron Tomography (SPET) for Structural Analysis of Thin Films along Their Thickness

Accurate structure analysis of epitaxial perovskite thin films is a fundamental step towards the ability to tune their physical properties as desired. Precession-assisted electron diffraction tomography (PEDT) has proven to be an effective technique for performing ab initio structure solutions and refinements for this class of materials. As the film thickness or the region of interest (ROI) decrease in size, the capacity to collect PEDT data with smaller electron beams is a key parameter and ROI tracking becomes a major issue. To circumvent this problem, we considered here an alternative approach to acquiring data by combining PEDT with a scan over an area, extracting the intensities collected at different positions and using them to perform accurate structure refinements. As a proof of concept, a Scanning Precession Electron Tomography (SPET) experiment is performed on a 35 nm thick perovskite PrVO3(PVO) film deposited on a SrTiO3 (STO) substrate. This way, it was possible to detect small changes in the PVO structure along the film thickness, from the variation in unit cell parameters to atomic positions. We believe that SPET has the potential to become the standard procedure for the accurate structure analysis of ROIs as small as 10 nm.

Biomimetic ion substituted and Co-substituted hydroxyapatite nanoparticle synthesis using Serratia Marcescens

Biomimicry is becoming deep-rooted as part of bioceramics owing to its numerous functional advantages. Naturally occurring hydroxyapatite (HA) apart from primary nano structures are also characterised by various ionic substitutions. The ease of accommodating such key elements into the HA lattice is known to enhance bone healing properties of bioceramics. In this work, hydroxyapatite synthesized via biomimetic approach was substituted with individual as well as multiple cations for potential applications in bone repair. Ion substitutions of Sr, Mg and Zn was carried out on HA for the first time by using Serratia grown in a defined biomineralization medium. The individual ions of varying concentration substituted in Serratia HA (SHA) (Sr SHA, Mg SHA and Zn SHA) were analysed for crystallinity, functional groups, morphology and crystal size. All three showed decreased crystallinity, phase purity, large agglomerated aggregates and needle-shaped morphologies. Fourier transform infrared spectroscopy (FTIR) spectra indicated increased carbonate content of 5.8% resembling that of natural bone. Additionally, the reduced O–H intensities clearly portrayed disruption of HA lattice and subsequent ion-substitution. The novelty of this study lies primarily in investigating the co-substitution of a combination of 1% Sr, Zn and Mg in SHA and establishing the associated change in bone parameters. Scanning electron microscope (SEM) and transmission electron microscope (TEM) images clearly illustrated uniform nano-sized agglomerates of average dimensions of 20–50 nm length and 8–15 nm width for Sr SHA; 10–40 nm length and 8–10 nm width for both Zn SHA and Mg SHA and 40–70 nm length and 4–10 nm width in the case of 1% Sr, Zn, Mg SHA. In both individual as well as co-substitutions, significant peak shifts were not observed possibly due to the lower concentrations. However, cell volumes increased in both cases due to presence of Sr2+ validating its dominant integration into the SHA lattice. Rich trace ion deposition was presented by energy dispersive X-ray spectroscopy (EDS) and quantified using inductively coupled plasma optical emission spectrometer (ICP-OES). In vitro cytotoxicity studies in three cell lines viz. NIH/3T3 fibroblast cells, MG-63 osteosarcoma cells and RAW 264.7 macrophages showed more than 90% cell viability proving the biocompatible nature of 1% Sr, Zn and Mg in SHA. Microbial biomineralization by Serratia produced nanocrystals of HA that mimicked “bone-like apatite” as evidenced by pure phase, carbonated groups, reduced crystallinity, nano agglomerates, variations in cell parameters, rich ion deposition and non-toxic nature. Therefore ion-substituted and co-substituted biomineralized nano SHA appears to be a suitable candidate for applications in biomedicine addressing bone injuries and aiding regeneration as a result of its characteristics close to that of the human bone.

Reduced Order Model of Common Battery Pack Architectures for Assessment of Cell Parameter Variation Propagation

Reduced Order Model of Common Battery Pack Architectures for Assessment of Cell Parameter Variation Propagation

Correlation of structure and dielectric response in Ce-doped double perovskite cobaltite

Double perovskite Bi2Ca2-xCexCoO6; x = 0.00, 0.05, 0.10 and 0.15 (BCCCO) is synthesized by co-precipitation route. X-ray diffraction (XRD) confirms the monoclinic single-phase crystal structure with negligible variation in unit cell parameters, indicating that the Cerium (Ce) has been successfully incorporated. With Ce doping, the average crystallite size of Bi2Ca2CoO6 (BCCO) nanoparticles decreases. Scherrer's formula was used to determine the crystallite sizes (33–37 nm) of BCCO nanoparticles. Jonscher's power law is used to investigate the conduction mechanism of all the prepared specimens. The power-law specifies the correlated barrier hopping for BCCCO x = 0.00 and 0.05, short polaron tunneling for x = 0.10, while BCCCO x = 0.15 follows overlapping large polaron tunneling. The dielectric permittivity has been calculated with a frequency range of 20 Hz - 3 MHz, and the Ce doped samples show a high value of dielectric permittivity εr = 1.79 × 105 at 500 °C. The influence of crystallite size on the dielectric permittivity of BCCCO was examined in this work. The relaxation time and spreading factor of all samples are investigated using Non-linear Debye's function. All these features are studied as a function of frequency at temperatures ranging from 100 to 500 °C. Here, the DC electrical conductivity of BCCCO is investigated by the four-probe method at 50–400 °C. In Ce-doped specimen the lowest value of thermal conductivity (k = 0.797 W/m-K at 120 °C) has been observed.

Study of The Electrical, Optical and Morphological Properties in Submicron and Microstructured ZnO Thin Films Obtained by Spin Coating and Chemical Bath Deposition

In the present work the synthesis of ZnO semiconductor thin films was performed successively using spin coating and chemical bath deposition techniques. The deposition was made by varying the concentration of zinc acetate and hexamethylenetetramine (HMTA: ZnAc) in the precursor solution. This process led to two preferred growth directions (002) and (101), both with very similar texture coefficients, too; a noticeable change in morphology of structured surface, variation in unit cell parameters and crystalline grain size. All the films turned out homogeneously submicro and microstructured and with a wurtzite-type hexagonal crystalline structure. Using pre-loaded Mathematica 11.3 software functions and an algorithm developed in it, the micrographies were analyzed to calculate the percentage of substrate-covered area which was always greater than 80%. Likewise, it also found that resistivity decreases at a higher percentage of covered area and that the variation in the shape of the photo luminescent emission spectrum can be considered as a qualitative indication of the concentration of charge carriers.

Towards lead-free all-inorganic perovskite solar cell with theoretical efficiency approaching 23%

ABSTRACT Single junction solar cells with organic-inorganic perovskites have achieved efficiency > 25%, yet they suffer from long-term durability and toxicity. Additionally, all the best-performing perovskite light harvesters contain lead, hindering their real-time application. Herein, we report preliminary studies with the SCPAS-1D software package on three different perovskite light harvesters, namely FAPbI3, FASnI3, and CsSnI3, considering an approach towards stable and environmentally benign perovskite light harvesters. Additionally, to extract the best performance, each perovskite light harvester is analysed with four electron transport layers, namely TiO2, SnO2, BaSnO3, and La doped BaSnO3. The physical parameters such as thickness, doping, and defect density are optimised for the subsequent films to deliver high performance. Further, the operating temperature-dependent variation in power conversion efficiency and other solar cell parameters are also analysed. In an attempt to replace the high-cost gold counter electrode, a comparative study on the performance of other possible counter electrodes is also comprehensively detailed.

Structural, vibrational and luminescence properties of solid solution based on the (1-x/2) Ce2(WO4)3 + (x/2) Sm2(WO4)3 system

A series of 14 polycrystalline cerium samarium tungstates belonging to the system [(1-x/2).Ce2(WO4)3 + x/2 Sm2(WO4)3] was synthesized by a coprecipitation method followed by thermal treatment at 1000 °C. The polycrystalline samples were characterized by X-ray diffraction, scanning electron microscopy and Raman spectroscopy. Their crystal structure was subjected to Rietveld refinement calculations and quasi-linear variation of cell parameters was observed, suggesting the formation of a solid solution Ce(2-x)Smx(WO4)3 (0 ≤ x ≤ 2). Raman spectroscopy was used to confirm the formation of the disordered solid solution. The analyses of Bragg peak and Raman emission profiles allowed evidencing the formation of structural defects. Scanning electron microscopy images show relatively well crystallized grains. Photoluminescence experiments were performed under polychromatic X-ray excitation delivered by copper source. The characteristic luminescence of Ce3+ cations was not observed whatever the composition x. The resulting emissions were ascribed to Sm3+ cations associated with additional emission from structural defects. Chromaticity diagrams show that color coordinates vary with Sm composition and structural defects in the orange-red range.

Modulation of ionic arrangement in polar magnet by chemical pressure

The similarity of local structure-connection pattern and volumetrically compressive strain between host and guest phases can be used to stabilize heteroid metastable matter and tune the local structure and properties. Here a series of metastable ABO3 (A = Mn; B = Mn0.5Mo0.5, Mn1/3Ta2/3, and Mn0.5Ta0.5) were trapped in LiTaO3 to form solid-solutions, where the difference of solid solubility limit reveals the barrier of size effect on chemical pressure. All samples show antiferromagnetic characters, in which the (LiTaO3)1-x-[Mn(Mn0.5Mo0.5)O3]x series exhibit more complex magnetic and dielectric behaviors with the increasing of metastable guest phase, stemming from the complex interactive mechanism between Mn2+ and Mo6+. The cell parameter variation of (LiTaO3)1-z-[Mn(Mn0.5Ta0.5)O3]z shows a more regularly changing tendency, on account of the smallest size barrier. These findings show that chemical pressure can effectively stimulate the physical pressure to intercept and modulate a metastable phase at atomic-scale by compressibility effect between like structures at ambient pressure.

Optimized CH3NH3PbI3-XClX based perovskite solar cell with theoretical efficiency exceeding 30%

Organic-inorganic perovskite light absorbers have shown tremendous progress over the last decade. Single junction solar cells with perovskite light absorbers have achieved power conversion efficiencies exceeding 25%. Further optimization of the subsequent thin-films in the perovskite solar cells is essential to attain higher power conversion efficiencies reaching the Shockley-Queisser limit. Herein, we report the preliminary studies on how the subsequent thin-films thickness and properties can be tuned to achieve efficiencies exceeding 30%. We used SCAPS-1D software to optimize the thickness, donor, defect, and acceptor densities of each thin film of the perovskite solar cells. The thickness and defect densities of the CH3NH3PbI3-XClX light absorber had the highest control over power conversion efficiencies. The thickness and acceptor densities of the hole transporting films had the slightest control over power conversion efficiencies. We have also studied the operating temperature-dependent variation in power conversion efficiency and other solar cell parameters. In an attempt to replace the high-cost gold counter electrode, we compared the variation of power conversion efficiency with other possible counter electrodes. Overall, the current approach of utilizing SCAPS-1D software to optimize high-efficiency perovskite solar cells theoretically can be extended to other solar cells and optoelectronic devices.

Temperature Dependence of Spin-Phonon Coupling in [VO(acac)2]: A Computational and Spectroscopic Study.

Molecular electronic spins are good candidates as qubits since they are characterized by a large tunability of their electronic and magnetic properties through a rational chemical design. Coordination compounds of light transition metals are promising systems for spin-based quantum information technologies, thanks to their long spin coherence times up to room temperature. Our work aims at presenting an in-depth study on how the spin–phonon coupling in vanadyl-acetylacetonate, [VO(acac)2], can change as a function of temperature using terahertz time-domain spectroscopy and density functional theory (DFT) calculations. Powder THz spectra were recorded between 10 and 300 K. The temperature dependence of vibrational frequencies was then accounted for in the periodic DFT calculations using unit-cell parameters measured at two different temperatures and the optimized ones, as usually reported in the literature. In this way, it was possible to calculate the observed THz anharmonic frequency shift with high accuracy. The overall differences in the spin–phonon coupling magnitudes as a function of temperature were also highlighted showing that the computed trends have to be ascribed to the anisotropic variation of cell parameters.

Magnetic transitions with magnetocaloric effects near room temperature related to structural transitions in Y0.9Pr0.1Fe2D3.5 deuteride

The structural and magnetic properties of Y0.9Pr0.1Fe2D3.5 deuteride have been investigated by synchrotron and neutron diffraction, magnetic measurements, and differential scanning calorimetry. Deuterium insertion induces a 23.5% cell volume increase and a lowering of crystal symmetry compared to the cubic C15 Y0.9Pr0.1Fe2 parent compound (Fd-3m SG). The deuteride is monoclinic (P21/c SG) below 330 K and undergoes a first-order transition between 330 and 350 K toward a pseudo-cubic structure (R-3 m SG) with TO–D = 342(2) K. In both structures, the D atoms are located in 96% R2Fe2 and 4% RFe3 tetrahedral interstitial sites (R = Y0.9Pr0.1). The compound is ferromagnetic, accompanied by a magnetostrictive effect below TC = 274 K. The analysis of the critical exponents indicates a second-order type transition with a deviation from the isotropic 3D Heisenberg model toward the 3D XY model. This implies an easy plane of magnetization in agreement with cell parameter variation showing planar magnetic orientation. A weak magnetic peak is even observed at the order–disorder transition with a maximum at 343 K. Magnetic entropy variations are characteristic of direct and inverse magnetocaloric effects at TC and TO–D, respectively.

Evaluation of Cell Parameter Variation on Energy Absorption Characteristic of Thermoplastic Honeycomb Sandwich Structure

Evaluation of Cell Parameter Variation on Energy Absorption Characteristic of Thermoplastic Honeycomb Sandwich Structure

Ceramic pigments from CoxNi3-xP2O8 (0 ≤ x ≤ 3) solid solutions

CoxNi3-xP2O8 (0 ≤ x ≤ 3) solid solutions were synthesized via the chemical co-precipitation method. Variation of unit cell parameters and interatomic distances indicated that these solid solutions with the Ni3P2O8 structure are stable between 800 and 1200 °C in compositions with 0 ≤ x ≤ 1.5 and between 800 and 1000 °C when (0 ≤ x ≤ 3). When (2.5 ≤ x ≤ 3.0), the solid solutions lead to the Co3P2O8 structure, being stable between 800 and 1000 °C.The yellow colour of the Ni3P2O8 compound changes to pink or red when Co(II) ions are incorporated in the structure as Ni3P2O8 solid solutions are formed. Bands corresponding to second and third electronic transitions of the Co(II) ions in octahedral coordination appear in the 450–600 nm in the UV-V spectra, and they are responsible of the observed changes in the colour. Absorbance in the visible spectra was also obtained from enamelled samples but a new band at 650 nm with considerable absorbance when x > 1.0 increased the blue amount, and colour of the enamelled samples was yellowish brown, brown, green and blue.

Solidification microstructures of multielement carbides in the high entropy Zr-Nb-Hf-Ta-Cx system produced by arc melting

Multielement, high entropy carbides are a new class of refractory materials typically manufactured by solid-state synthesis. Although high entropy alloys are usually produced by solidification of a melt, the solidification of high entropy carbides has not been investigated to date. Herein, we report the first arc melting study of the solidification microstructures of the Zr-Nb-Hf-Ta-Cx system. The results highlight the presence of elemental segregation in interdendritic regions whose composition depends on the carbon load (i.e., the composition of the primary solidification phase changes with the amount of carbon in the melt). Duplex microstructures containing two distinct multielement carbides, possessing hardness as high as 30 GPa, are obtained. Interestingly, under certain conditions, there is a perfect “crystallographic continuity” (no grain boundaries and cell parameter variations) between the two phases, though their composition differs. Arc melting produces new and exotic microstructures not observed in materials processed in the solid state.

Phase equilibria and oxygen content of intermediate phases in the Sm2O3–SrO–Fe2O3 system

Six types of oxide phases are formed in the Sm2O3–SrO–Fe2O3 system at 1100 °C in air: perovskite type Sr1-хSmхFeO3-δ (0.05 ≤ х ≤ 0.50 with the cubic structure, S.G. Pm-3m and 0.85 ≤ x ≤ 1.0 with the orthorhombic structure, S.G. Pbnm), and Ruddlesden-Popper series corresponding to n = 1,2,3, i.e. Sr2-ySmyFeO4-δ, Sr3-uSmuFe2O7-δ (0 ≤ u ≤ 0.3; u = 1.80) and Sr4-rSmrFe3O10-δ. The structural parameters of single-phase samples, refined by the Rietveld method, allowed to reveal the variation of unit cell parameters with composition. A subsolidus isothermal isobaric phase diagram (1100 °C, Po2 = 0.21 atm) for the ½Sm2O3–SrO–½Fe2O3 system has been constructed. The compositional triangle was divided into 24 phase fields. The values of oxygen content and mean oxidation state of iron in all single phases were determined by iodometric titration. The changes in oxygen content with temperature in Sr2.7Sm0.3Fe2O7-δ, Sr1.2Sm0.8FeO4-δ, and Sr3.1Sm0.9Fe3O10-δ were studied by TGA within the range of 25−1100 °C in air. They show that the maximum oxidation state of Fe ions in RP oxides at room temperature increases with n, reaching 3.52 for the Sr3.1Sm0.9Fe3O10-δn = 3 member.

Anomalous stepped-hysteresis and T-induced unit-cell-volume reduction in carbon nanotubes continuously filled with faceted Fe3C nanowires

Ferromagnetically-filled carbon nanotubes have been recently considered important candidates for application into data recording quantum disk devices. Achievement of high filling rates of the ferromagnetic materials is particularly desirable for applications. Here we report the novel observation of carbon nanotubes continuously filled along the capillary with unusual μm-long faceted Fe3C nanowires. Anomalous magnetic features possibly due to strain effects of the crystal facets are reported. Magnetization measurements revealed unusual stepped magnetic hysteresis-loops at 300 K and at 2 K together with an anomalous decrease in the coercivity at low temperature. The observed unusual shape of the hysteresis is ascribed to the existence of an antiferromagnetic transition within or at the boundary of the ferromagnetic facets. The collapse in the coercivity value as the temperature decreases and the characteristic width-enhancement of the hysteresis with the field increasing appear to indicate the existence of layered antiferromagnetic phases, possibly in the strain-rich regions of the nanowire facets. Zero field cooled (ZFC) and field cooled (FC) magnetic curves evidenced presence of magnetic irreversibilities, an indicator of a possible spin-glass-like behavior induced by competing antiferromagnetic and ferromagnetic interactions. Characterization performed with low temperature XRD measurements, further revealed a slight variation in the average Fe3C unit cell parameters, suggesting the absence of additional unit-cell volume induced ferromagnetic transitions at low temperature.

Growth and characterization of lithium chloride doped KDP crystals: a DFT and experimental approach

The potassium dihydrogen phosphate (KDP) is a popular nonlinear optical material. Optically good quality LiCl doped KDP crystals have been grown by slow solvent evaporation method at room temperature. The structural study of grown crystals reveled single phasic nature of grown crystals with slight variation in unit cell parameters. I had done the Rietveld refinement to study the influence of dopant in the structure of KDP. The linear optical properties of grown crystals such as optical transparency energy band gap, reflectance, extinction coefficient, refractive index, etc. were studies using the UV-Visible spectroscopy. The Kurtz and Perry powder NLO technique was employed to study the nonlinear optical improvement in KDP crystal due to doping. The AC electrical study of grown crystals was done using the complex impedance spectroscopy. The theoretical study of grown crystals has been done using the Generalized Gradient Approximation pseudopotential method. The results are discussed here.