Transient Analysis Research Articles

Frequency control enhancement for hybrid microgrid using multi-terminal multi-function inverter

Renewable energy sources (RESs) are considered a crucial energy transformation to reduce carbon emissions, so more RESs are being integrated into contemporary power systems. Power electronic converters are extensively utilized to connect power grids with renewable generators to manage the fluctuations and unpredictability of these renewable energy sources. This paper introduces a multi-terminal multi-function inverter (MT-MF) designed for a battery energy storage system (BESS) to maintain the frequency stability of a hybrid microgrid (MG). The MG comprises a photovoltaic generation system, a diesel generator, BESS, and two loads: one constant load and the other variable, fed through a medium-voltage radial feeding system. An introduced approach involves utilizing a model predictive control controlled virtual synchronous generator (MPC-VSG) for BESS. This method offers inertia support during transient states and improves the dynamic characteristics of system frequency. In addition, it enables the connection of multiple batteries, provides individualized control for each, and supports the injection of reactive power into the MG. The required power from the BESS is shared between the two batteries using the low pass filter technique. The simulation outcomes affirm the proposed control strategy’s effectiveness and underscore the MT-MF inverter approach’s potential in integrating extensive RESs. This paper also explores how the proposed technique outperforms other methods in improving frequency stability.

Obtaining high-entropy alloy coating by laser remelting of metal powder composition: mathematical modelling of the transient thermal state

Obtaining high-entropy alloy coating by laser remelting of metal powder composition: mathematical modelling of the transient thermal state

Direct observation of photoinduced sequential spin transition in a halogen-bonded hybrid system by complementary ultrafast optical and electron probes

A detailed understanding of the ultrafast dynamics of halogen-bonded materials is desired for designing supramolecular materials and tuning various electronic properties by external stimuli. Here, a prototypical halogen-bonded multifunctional material containing spin crossover (SCO) cations and paramagnetic radical anions is studied as a model system of photo-switchable SCO hybrid systems using ultrafast electron diffraction and two complementary optical spectroscopic techniques. Our results reveal a sequential dynamics from SCO to radical dimer softening, uncovering a key transient intermediate state. In combination with quantum chemistry calculations, we demonstrate the presence of halogen bonds in the low- and high-temperature phases and propose their role during the photoinduced sequential dynamics, underscoring the significance of exploring ultrafast dynamics. Our research highlights the promising utility of halogen bonds in finely tuning functional properties across diverse photoactive multifunctional materials.

XIST dampens X chromosome activity in a SPEN-dependent manner during early human development.

XIST (X-inactive specific transcript) long noncoding RNA (lncRNA) is responsible for X chromosome inactivation (XCI) in placental mammals, yet it accumulates on both X chromosomes in human female preimplantation embryos without triggering X chromosome silencing. The XACT (X-active coating transcript) lncRNA coaccumulates with XIST on active X chromosomes and may antagonize XIST function. Here, we used human embryonic stem cells in a naive state of pluripotency to assess the function of XIST and XACT in shaping the X chromosome chromatin and transcriptional landscapes during preimplantation development. We show that XIST triggers the deposition of polycomb-mediated repressive histone modifications and dampens the transcription of most X-linked genes in a SPEN-dependent manner, while XACT deficiency does not significantly affect XIST activity or X-linked gene expression. Our study demonstrates that XIST is functional before XCI, confirms the existence of a transient process of X chromosome dosage compensation and reveals that XCI and dampening rely on the same set of factors.

Power Components Mean Values Determination Using New Ip-Iq Method for Transients

This paper deals with the quasi-instantaneous determination (in a single-step response time) of apparent, active, and reactive (i.e., blind and distortion) power mean values including the total power factor, total harmonic distortion, and phase shift of fundamentals of a power electronic and electrical system (PEES) using the ip-iq method, which is the main contribution of the paper. The power components’ mean values are investigated during the transient and steady states. The power components’ mean values can be determined directly from phase current and voltage quantities, using an integral calculus over one period within the next calculation step and using moving average and moving rms techniques (or digital filtering). Consequently, the power factor can be evaluated with known values of a phase shift of fundamentals (using a Fourier analysis). The results of this study show how a distortion power component during transients is generated even under a harmonic supply and linear resistive–inductive load. The paper contains a theoretical base, modeling, and simulation for the three and single phases of the transients in power electronic systems. The worked-out results can be used to determine and size any PES. The presented approach brings a detailed time waveform verified by simulations in Matlab/Simulink 2022a and the Real-time HW Simulator Plecs RT Box 1.

Screening and functional verification of drought resistance-related genes in castor bean seeds

Drought is one of the natural stresses that greatly impact plants. Castor bean (Ricinus communis L.) is an oil crop with high economic value. Drought is one of the factors limiting castor bean growth. The drought resistance mechanisms of castor bean have become a research focus. In this study, we used castor germinating embryos as experimental materials, and screened genes related to drought resistance through physiological measurements, proteomics and metabolomics joint analysis; castor drought-related genes were subjected to transient silencing expression analysis in castor leaves to validate their drought-resistant functions, and heterologous overexpression and backward complementary expression in Arabidopsis thaliana, and analysed the mechanism of the genes' response to the participation of Arabidopsis thaliana in drought-resistance.Three drought tolerance-related genes, RcECP 63, RcDDX 31 and RcA/HD1, were obtained by screening and analysis, and transient silencing of expression in castor leaves further verified that these three genes corresponded to drought stress, and heterologous overexpression and back-complementary expression of the three genes in Arabidopsis thaliana revealed that the function of these three genes in drought stress response.In this study, three drought tolerance related genes, RcECP 63, RcDDX 31 and RcA/HD1, were screened and analysed for gene function, which were found to be responsive to drought stress and to function in drought stress, laying the foundation for the study of drought tolerance mechanism in castor bean.

The new layout and regulation of the “pulsating” power conversion system of EU DEMO WCLL for an effective and safe control of pulse-dwell transition and increase of plant efficiency

Abstract EUROFUSION DEMO is a Fusion Power Plant concept under assessment, based on Tokamak technology. Regarding Balance of Plant (BoP) definition, particular effort have been posed to the design of the Power Conversion System (PCS), thermally coupled to the Primary Heat Transport System (PHTS). Several architectures of the PCS have been assessed, present work is focused on the PCS -based on the Rankine Cycle technology- equipped with a Small Energy Storage System (ESS) operated with Molten Salt. A new Energy Map has been released in 2021, revealed uncertainties on the thermal power deposited on the different in-Vacuum Vessel components (i.e., Breading Blanket, Divertor, Limiters and Vacuum Vessel) and rejected to the coolant of related cooling circuits. This fact leads to several (twelve) possible operating scenarios. In the following treatment will be analyzed the 2022 PCS Small ESS concept design review, performed by the Industry with the main aim to align the new layout with the updated Thermal inputs and its comparison with the preliminary design developed in 2018. Design novelties will be highlighted, especially those dealt improving the cycle control, robustness, safety of the operation and efficiency. The outcomes of the transient analysis will be shown and compared, to verify the mechanical and thermal stress during the DEMO period (pulse/dwell). Finally, a performance and efficiency analysis of the 2022 PCS layout will be also presented and compared to 2018 configuration.

Transient Analysis on the Crosswind Effect to the Aerodynamics of High-speed Train Travelled on the Bridge Between Two Tunnels at Jakarta -Bandung Track

The rapid evolution of global transportation technology is exemplified by Indonesia's innovative high-speed train initiative, linking Jakarta and Bandung in an impressive 45 minutes. Operating at 350 km/h, the HST CR400AF underscores the importance of aerodynamics in high-speed rail systems. This study delves into the significant impact of crosswind on key aerodynamic factors (drag, lift, rolling moment) within the tunnel-bridge-tunnel configuration. Leveraging Computational Fluid Dynamics (CFD) through ANSYS FLUENT, the analysis explores crosswind variations at 0 m/s, 10 m/s, and 25 m/s. Results reveal a proportional increase in aerodynamic load with higher crosswind intensities: 1.67 times for drag, 58.8 times for lift, and 29.8 times for rolling moment. Notable observations include pronounced aerodynamic load fluctuations during the "OUT" process, with the head section bearing the greatest load, followed by the tail and middle sections. These findings contribute valuable insights to the global discourse on enhancing safety and efficiency in high-speed rail systems

Numerical Analysis of Transient Convective Heat Transfer in a Dental Implant

Hot substance consumption can have adverse effects on the neighbouring bone tissue in proximity to a dental implant. Elevated temperatures at the interface between the bone and implant could potentially disrupt the local cellular processes crucial for osteointegration. The primary goal of this study was to analyse the temperature and heat flux distributions within the implant body, surrounding bone, and bone-implant interface when the implant system subjected to a thermal load of transient nature. Transient thermal finite element analysis was utilised to analyse a three-dimensional model of dental implant with three different lengths – 6, 10, and 13 mm – placed in a mandible section. In order to obtain realistic results, thermal load was applied through convection on the outer surface of the prosthesis, simulating exposure to a hot liquid with the temperature and convection heat transfer coefficient of 67°C and 0.005 W/mm2°C, respectively. The temperature of the other components in the model was maintained at a constant 37°C. The results showed that increasing the implant length generally led to lower temperature and heat flux levels in the implant body, bone, and bone-implant interface. The highest temperature and heat flux values were concentrated in the superior region, gradually decreasing toward the inferior region. Importantly, all maximum temperature values remained below the limits associated with cellular bone necrosis and remodelling, thereby reducing the risk of osteoporosis. It is noteworthy that, when considering transient thermal load, shorter implants pose a significantly higher risk of implant failure compared to longer ones.

Ultrasensitive detection of trace Hg(Ⅱ) in acidic conditions using DMABR loaded on sepiolite: Function, application and mechanism studies

Fast and real-time detection of trace Hg(Ⅱ) by fluorescent probes under acidic conditions is urgently required due to the high toxicity and accessibility to creatures and human being. However, fluorescent probes for Hg(Ⅱ) detection in environmental samples are rarely reported due to the protonation potential of acidic mercury sources. In this study, the SD probe was developed by 5-(p-dimethylaminobenzylidene) rhodanine (DMABR) loaded on sepiolite by hydrothermal treatment, and showed excellent Hg(Ⅱ) detection performances for mercury sources at pH 4–10 due to buffering ability of the hyperconjugated lactam rings. Sepiolite functioned as the support skeleton to decrease intermolecular transition, and thus increased the sensitivity. At pH 4, the SD probe showed high selectivity and sensitivity for Hg(Ⅱ) among various species, with low LOD and binding constant of 4.78 × 10−9 M and 1.34 × 106 M−1, respectively. Through DFT calculations, MAS 1H NMR and 2D-COS analysis, the detection mechanism was demonstrated as SN1 substitution of the spontaneous leaving H on amino groups in the transient state during tautomeric equilibrium, rather than the expected high-affinity sulphydryl. Additionally, the SD probe exhibited promising potential in quantifying water-soluble and bioavailable Hg(Ⅱ) in acidic polluted soil and water samples. Moreover, real-time detection was realized by paper-based strips.

The transcriptional regulation of a putative hemicellulose gene, PtrPARVUS2 in poplar

The plant cell wall serves as a critical interface between the plant and its environment, offering protection against various stresses and contributing to biomass production. Hemicellulose is one of the major components of the cell wall, and understanding the transcriptional regulation of its production is essential to fully understanding cell wall formation. This study explores the regulatory mechanisms underlying one of the genes involved in hemicellulose biosynthesis, PtrPARVUS2. Six transcription factors (TFs) were identified from a xylem-biased library to negatively regulate PtrPARVUS2 expression. These TFs, belonging to diverse TF families, were confirmed to bind to specific cis-elements in the PtrPARVUS2 promoter region, as validated by Yeast One-Hybrid (Y1H) assays, transient expression analysis, and Chromatin Immunoprecipitation sequencing (ChIP-seq) assays. Furthermore, motif analysis identified putative cis-regulatory elements bound by these TFs, shedding light on the transcriptional regulation of SCW biosynthesis genes. Notably, several TFs targeted genes encoding uridine diphosphate glycosyltransferases (UGTs), crucial enzymes involved in hemicellulose glycosylation. Phylogenetic analysis of UGTs regulated by these TFs highlighted their diverse roles in modulating hemicellulose synthesis. Overall, this study identifies a set of TFs that regulate PARVUS2 in poplar, providing insights into the intricate coordination of TFs and PtrPARVUS2 in SCW formation. Understanding these regulatory mechanisms enhances our ability to engineer plant biomass for tailored applications, including biofuel production and bioproduct development.

Improving the protection system in the distribution networks integrated with photovoltaic cells by changing the ratio of X/R

Due to the increased demand for electrical energy, many countries were prompted nowadays to search for new sources. One important source is the photovoltaic energy. However, despite the great benefits of this source, some defects where observed when linking to distribution networks (negative impact on the protection system). Hence, an approach of improving the protection system in distribution networks integrated with photovoltaic cells is presented in this paper. The protection system improvement is proposed by changing the impedance to resistance ratio (X/R) values of the networks cables, which leads to increasing the overcurrent relays' response speed when a fault occurs. A comparative analysis with different cable reactance values was conducted. The electrical transient analyzer program (ETAP) software was used to investigate and validate the effects on the relay’s response times. Amriya Fallujah power station, located in Iraq, was investigated as a case study. Simulation results show that it is possible to increase the response speed of the overcurrent relay by reducing X/R of the network cables. For more validation, the distance relay was used to compare the best improvement results of changing the X/R ratio with the results of changing the type of relay, which also shows the strength of the proposed method.

Raised Ge-Source with n+ pocket and recessed drain line TFET: A proposal for biosensing applications

In this paper, we present a novel raised Ge-source with an n+ pocket and recessed drain line Tunnel Field-Effect Transistor (TFET). It offers enhanced performance for potential biosensing applications. The proposed device comprises a Ge source with a low bandgap, an n+ pocket, and a larger tunneling area. This results in improved performance characteristics: an ON current of 54.27 μA/μm, an ON-current to OFF-current ratio of 1.5 × 1012, and an average subthreshold swing of 21.3 mV/dec. The recessed drain design eliminates ambipolarity, further enhancing performance. The study thoroughly investigates biosensing capabilities, including DC and transient analyses, evaluating charged and neutral biomolecules (uricase, biotin, 3-aminopropyltriethoxysilane, DNA, keratin, and gelatin). The proposed biosensor, with a higher drain current sensitivity of 1.2 × 109 for gelatin (k = 12) and 3.05 × 108 for keratin (k = 8), outperforms existing approaches, making our proposed biosensor a compelling choice for future low-power biomedical applications.

The chemo-mechanics of initiation of crack advance in Niobium Tungsten Oxide single crystals due to delithiation

Niobium tungsten oxide (NWO) micron-sized single crystals show promise as the active particles in the anodes of lithium ion batteries due to their fast charge/discharge and high storage capabilities. Within the “block” phases such as Nb16W5O55, Nb14W3O44 and the HNb2O5 polymorph, Li ion diffusion occurs in a unidirectional manner along a single axis of the crystal and lithiation/delithiation results in significant length changes in this direction. A chemo-mechanics analysis is developed for delithiation of an NWO “block” phase single crystal that contains a pre-existing flaw in the form of a through-thickness edge crack. Galvanostatic delithiation occurs by the flux of Li ions through the free ends of the crystal and also through the faces of the crack, with concomitant shrinkage of the surface layer over a depth equal to that of the crack. The induced tensile stress in the surface layer can be of sufficient magnitude to advance the crack in the NWO crystal, consistent with recent experimental observations for Nb14W3O44. A 2D full-field finite element version of the chemo-mechanics model is used to explore the sensitivity of cracking to crack length, delithiation rate of the anode, diffusivity of Li ions within the NWO single crystal storage particle and to the kinetics of Li ion transfer across the particle surface-electrolyte interface. Additionally, a simplified, lumped parameter model is developed by assuming that the Li ion occupancy is spatially uniform in a surface layer that extends to a depth of the pre-existing crack, and has a spatially uniform but different value than that of the underlying core of the particle. This simplified model can be expressed as a set of first order differential equations in time and gives the main features of delithiation and the associated transient stress state in the single crystal. Both the full model and the lumped parameter version predict that crack advance from a pre-existing defect is triggered by a high delithiation rate, consistent with the experimental literature.

Simulation and experimental study on rope driven artificial hand and driven motor.

Prosthetic hands have the potential to replace human hands. Using prosthetic hands can help patients with hand loss to complete the necessary daily living actions. This paper studies the design of a bionic, compact, low-cost, and lightweight 3D printing humanoid hand. The five fingers are underactuated, with a total of 9 degrees of freedom. In the design of an underactuated hand, it is a basic element composed of an actuator, spring, rope, and guide system. A single actuator is providing power for five fingers. And the dynamic simulation is carried out to calculate the motion trajectory effect. In this paper, the driving structure of the ultrasonic motor was designed, and the structural size of the ultrasonic motor vibrator was determined by modal and transient simulation analysis, which replace the traditional brake, realize the lightweight design of prosthetic hand, improve the motion accuracy and optimize the driving performance of prosthetic hand. By replacing traditional actuators with new types of actuators, lightweight design of prosthetic hands can be achieved, improving motion accuracy and optimizing the driving performance of prosthetic hands.

Impact of bariatric surgery on carotid intima-media thickness and arterial stiffness in metabolically healthy obesity: a prospective study.

Cardiovascular disease is one of the leading causes of mortality in patients with obesity. Metabolically healthy obesity (MHO), in which people do not have metabolic disorders, is a transient state of obesity. However, over the long term, a proportion of individuals with MHO develop metabolic syndrome (MetS). We aimed to investigate the effect of substantial weight loss following bariatric surgery in MHO on carotid intima-media thickness (CIMT) and pulse-wave velocity (PWV), which are independent predictors of subclinical atherosclerosis. This prospective study included 38 patients (34 women, four men) undergoing bariatric surgery who had severe obesity but without comorbidities (hypertension, diabetes, and hyperlipidemia), and 28 control individuals who were matched for age and sex. CIMT and PWV of the left common carotid artery were measured. At 12-month follow-up after bariatric surgery, measurements were repeated in the 38 patients with obesity. Mean baseline body mass index (BMI) in the MHO group was 40.55 ± 3.59kg/m2, which decreased by 33.1% after bariatric surgery. Compared with controls, CIMT and PWV were increased in MHO (543.53 ± 55.29 vs. 407.82 ± 53.09μm, 6.70 ± 1.22 vs. 5.45 ± 0.74m/s, respectively; all P < 0.001). At 12 months post-bariatric surgery, CIMT in MHO was lower than baseline (466.79 ± 53.74 vs. 543.53 ± 55.29μm, P = 0.009), but PWV was not significantly different from baseline (6.27 ± 0.86 vs. 6.70 ± 1.22m/s, P = 0.132). Multivariate regression showed that BMI was an independent predictor of CIMT (β = 0.531, P < 0.001). Carotid artery structure and function were impaired in MHO, and improved carotid artery structure was associated with weight loss in MHO after bariatric surgery.

Synergizing theory and experiment: Enhancing solar distillation performance with external reflector in a passive 4-stage model

Passive multi-stage solar distillers are pivotal in sustainable water purification, effectively utilizing solar energy. This study addresses the underexplored impact of reflective characteristics by integrating an aluminum reflector with radiation-trapping properties into a passive 4-stage solar distiller leveraging both experimental and theoretical methodologies. The influence of reflector height and angle on solar input, water production rate, and the Gain Output Ratio (GOR) was examined. Findings revealed a water production rate of 5.98 kg∙m−2hr−1and a GOR enhancement to 156 % at an optimal reflector setup of 40 mm height and 120° angle. Theoretical analysis assessed heat distribution and thermal efficiency across various air gaps and solar radiation levels. Evaporation emerged as the dominant heat mechanism, achieving 91 % thermal efficiency in the first stage with a 6.5 mm air gap and 1.50 kW∙m−2 of reflected solar radiation. Conversely, a 16 mm gap significantly lowered efficiency to 72 % in the last stage due to increased lateral heat loss. Transient analysis of the newly defined dissipation percent showed that narrower air gaps boosted heat retention in the distiller for evaporation and greater heat dissipation through the last stage, optimizing heat recycling for thermal applications. Increasing the solar input leads to sustained dissipation capacity.

Thermomagnetic Transient Analysis of an Infinitely Long Transverse Isotropic Annular Cylinder Using the MGT Fractional Heat Conduction Model with a Non-Singular Kernel

Thermomagnetic Transient Analysis of an Infinitely Long Transverse Isotropic Annular Cylinder Using the MGT Fractional Heat Conduction Model with a Non-Singular Kernel

Quasi-"In-Situ" Analysis of the Reactive Liquid-Solid Interface during Magnesium Corrosion using Cryo-Atom Probe Tomography.

The early stages of corrosion occurring at liquid-solid interfaces controls the evolution of the material's degradation process, yet due to their transient state, their analysis remains a formidable challenge. Here we perform corrosion tests on a MgCa alloy, a candidate material for biodegradable implants using pure water as a model system. The corrosion reaction was suspended by plunge freezing into liquid nitrogen. We studied the evolution of the early-stage corrosion process on the nanoscale by correlating cryo-atom probe tomography with transmission-electron microscopy and spectroscopy. We observed the outward growth of Mg hydroxide and the inward growth of an intermediate corrosion layer consisting of hydroxides of different compositions, mostly monohydroxide Mg(OH) instead of the expected MgO layer. In addition, Ca partitions to these newly formed hydroxides and oxides. Density-functional theory calculations suggest a domain of stability for this previously experimental unreported Mg(OH) phase. These new approach and findings advance the understanding of the early stages of magnesium corrosion, and in general reactions and processes at liquid-solid interfaces, which can further facilitate the development of corrosion-resistant materials or better control of the biodegradation rate of future implants. This article is protected by copyright. All rights reserved.

Design and analysis of mode-matched decoupled mass MEMS gyroscope with improved thermal stability

This paper presents an efficient design approach for microelectromechanical systems (MEMS) gyroscope considering the design constraint of MEMSCAP’s Silicon-on-Insulator Multi-User MEMS Processes (SOIMUMPs). A design for a decoupled mass MEMS resonant gyroscope with tuning electrodes is presented to minimize cross-axis coupling and optimize the gyroscope’s performance. The device features a size of 1.8 ×2.772 mm2 . A decoupled mass MEMS gyroscope has been designed using a novel mechanical beam configuration that optimizes the structural design to reduce unwanted interactions between drive and sense axes motions. Mode order has been achieved by obtaining the first two modes as drive and sense modes at 9946.3 Hz and 10 202.7 Hz, respectively. Parallel plate electrostatic tuning electrodes have been added to adjust and match the drive and sense modes at the resonant frequencies of 9946 Hz. This mode matching is crucial for optimizing gyroscope performance, accuracy, and sensitivity. The effects of temperature variation on the performance of the designed decoupled mass MEMS gyroscope have been investigated, particularly in terms of its mode-matched operation achieved using tuning electrodes. Finite element method (FEM) simulations were conducted, demonstrating that thermal stability was achieved, and mode-matched operation was maintained within the temperature range of −40 °C to 80 °C. The gyroscope exhibits enhanced performance compared to existing MEMS gyroscopes under mode-matched conditions, featuring a lower temperature coefficient of frequency (TCF) at 0.0415 Hz °C−1 in the drive mode and 0.0165 Hz °C−1 in the sense mode. FEM analysis for the fabrication process tolerances has been done, where MEMS gyroscope’s resonant frequencies, output capacitance, output displacement, and sense mode quality factor have shown negligible changes to fabrication process tolerances. Transient analysis was conducted using CoventorWare MEMS+ 3D schematic, which was integrated with MATLAB Simulink to measure the MEMS gyroscope’s output response, which corresponded with the varying input angular velocity signal.