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Efficient solution strategies for wave propagation problems with complex geometries are essential in many engineering fields. Immersed boundary methods simplify mesh generation by embedding the domain of interest into an extended domain that is easy to mesh, introducing the challenge of dealing with cells that intersect the domain boundary. We consider the finite cell method that extends the weak form from the physical into the extended domain, multiplied by a small value, to stabilize badly cut cells. Combined with explicit time integration methods, the presence of finite cells with very little support in the physical domain results in tiny critical time step sizes. While the finite cell stabilization limits how small the critical time step size can become, this limit is still restrictive for many applications. Explicit transient analyses commonly use the spectral element method due to its natural way of obtaining diagonal mass matrices through nodal lumping. The resulting method is very efficient since nodal lumping renders the solution of the equation systems trivial while not reducing the accuracy or the critical time step size. The combination of the spectral element and finite cell methods is called the spectral cell method. Unfortunately, a direct application of nodal lumping in the spectral cell method is impossible due to the special quadrature necessary to treat the discontinuous integrand inside the cut cells. The existing approaches to lump the mass matrices of cut cells significantly reduce the accuracy of the approximation. We analyze an implicit-explicit (IMEX) time integration method to exploit the advantages of the nodal lumping scheme for uncut cells on one side and the unconditional stability of implicit time integration schemes for cut cells on the other. In this hybrid, immersed Newmark IMEX approach, we use explicit second-order central differences to integrate the uncut degrees of freedom that lead to a diagonal block in the mass matrix and an implicit trapezoidal Newmark method to integrate the remaining degrees of freedom (those supported by at least one cut cell). The immersed Newmark IMEX approach preserves the high-order convergence rates and the geometric flexibility of the finite cell method while retaining the efficiency of the nodal lumping scheme for uncut cells without compromising the critical time step size. We analyze a simple system of spring-coupled masses to highlight some of the essential characteristics of Newmark IMEX time integration. We then solve the scalar wave equation with immersed boundaries on two- and three-dimensional examples with significant geometric complexity to show that our approach is more efficient than state-of-the-art time integration schemes when comparing accuracy and runtime. While we focus on the finite and spectral cell methods, we expect other immersed methods to benefit equally from Newmark IMEX time integration. [ABSTRACT FROM AUTHOR]

The transient Stokes magnetohydrodynamic (Stokes MHD) equations are thoroughly investigated in this paper using the variational subgrid multiscale stabilized finite element approach. In order to get the optimal order of convergence, appropriate stabilization parameter expressions have been derived using Fourier analysis. The theoretical convergence analysis of the subgrid algebraic stabilized numerical scheme is also presented in this study. The numerical studies on multiply-driven cavity flow establish the credibility of the variational algebraic subgrid multiscale stabilized finite element approach. Further, the theoretically determined convergence rate is numerically validated. For different Hartmann, Reynolds, and magnetic force inclination angle values, the flow fields are traced. [ABSTRACT FROM AUTHOR]

• A numerical approach for obtaining gas-liquid flow parameters utilizing one-dimensional two-fluid model was proposed. • The two-fluid model was discretized by implicit FEM techniques utilizing the proposed algorithm in this paper. • Four cases utilizing different meshes were utilized to illustrate the gas puffing effect on the momentum exchange process. • The transient numerical trends indicate that the gas puffing manifests in two physical forms between different flow regions. The accumulation of liquid condensate in the wet gas pipelines gives negative effects on the piping efficiency and flow managements. Accurate prediction of the condensate behavior is of crucial importance in the pipeline engineering. In this study, the one-dimensional two-fluid model with the stratified modeling in its source term is used to describe the gas-liquid kinetic motion along the pipe and the flow fields obtained from the newly proposed numerical approach are utilized to analyze the flow characteristics. Firstly, four cases with varying inlet liquid fractions, outlet pressures, and different meshes are utilized to investigate the gas-liquid steady-state variations along the pipe. The numerical results indicate that the outlet pressure influences the working pressure of the inlet gas-liquid, subsequently altering the equilibrium state and momentum exchange direction near the inlet, resulting in different condensate distributions in the pipeline. In the transient analysis with initial empty pipe, the inlet gas-liquid mainly impacts the pressure wave propagations in pressure spread stage, the gas kinetic motion in gas filling stage and the motion of the dividing interface between different regions in liquid filling stage, which is validated by the proposed numerical approach through comparison with the simulation tool OLGA designed by Schlumberger. Furthermore, when the liquid condensates appear in the initial state, the transition zones have two physical forms between different flow regions, which include the sudden dividing interface due to the high liquid amount carried by the inlet gas and the transition region resulted from the liquid accumulations. [ABSTRACT FROM AUTHOR]

Vortex breakdown occurs in highly swirling flows in various engineering applications, such as hydraulic turbines working in either high-load or part-load conditions, leading to pressure pulsations and performance degradation. In the present study, the formation of a helical vortex breakdown having rotational and plunging components (axial oscillation) in a straight diffuser is investigated with transient simulation from its columnar state to a helical vortex breakdown state. It is similar to the helical precessing vortex rope occurring in hydraulic turbines operating at part-load condition. In addition, considering vortex breakdown as a global instability, a linear global stability analysis of the time-averaged turbulent flow field is conducted for different flow states. The main objective is to understand the role of plunging mode in vortex rope formation in straight draft tubes and identify its differences with the one observed in hydraulic turbines with elbow draft tubes operating at part-load condition. Results showed that in contrast to the elbow draft tubes where the plunging mode appears earlier than the rotating mode, the transient simulation showed that the plunging mode appears after several vortex rope rotations in the straight draft tube. This is confirmed by the stability analysis showing that the flow is unstable to the asymmetrical disturbances with a frequency close to the rotating frequency not the plunging ones. Finally, the stability analysis showed a higher critical flow rate than the one obtained from the contour of local swirl number and time history of pressure and velocity. [ABSTRACT FROM AUTHOR]

• Propose a transient mathematic model to predict the temperature of rotary compressors during startup process. • Discuss the instantaneous heat transfer law of the compression unit of the rotary compressor. • Put forward methods to improve the efficiency of compressor. The transient temperature distribution and heat transfer characteristics of the rotary compressor are crucial to its reliability and efficiency of the compressor. In this paper, a transient mathematical model on predicting the temperature in the compressor during startup is proposed. Control volumes are divided including the fluid and solid domains. The convective heat transfer coefficient of each surface is discussed. A coupled solution method and its Fortran calculation program are developed. This mathematical model is experimentally validated by comparing the measured and calculated temperatures of the compressor. The results shows that calculated temperatures are consistent with the measured results during the startup process. The maximum error of the steady-state temperature is within 2 °C. The refrigerant in the compression unit mainly absorbs heat from the refrigerant in the lower chamber. Measures should be taken to reduce the heating of the upper bearing surface by the refrigerant in the lower chamber to improve the volume and indicated efficiencies. [ABSTRACT FROM AUTHOR]

A closed-loop integrated model including micro-vibration disturbance, dynamic characteristics of satellite, optical system of star sensor and attitude control algorithm is established. The control torque error caused by additional disturbance torque and the star sensor imaging error caused by structural resonance is fully integrated analyzed, which are firstly presented into the attitude control system (ACS). Steady-state and transient response analyses are completed to evaluate the impact of such two errors on performances of (ACS). Steady-state response results show that the effect of control torque error appears in lower frequency band with a peak of 6.784E-8″ at 53 Hz, while influence of star sensor imaging error on attitude determination mainly concentrates in high frequency band with maximum response of 0.4101″ at 315 Hz. Transient response results show that the two errors will not significantly affect control indicators such as rise time, overshoot and peak time. The results indicate that the influence of star sensor imaging error is non-negligible for satellite ACS which required milli-arc-second attitude control accuracy. According to the analytical results, traditional analysis only on payload optical axis cannot reveal the whole impact of micro vibration on LOS error, the two errors of micro-vibration introduced to ACS in this work must be considered for the development of spacecraft with 0.1″ pointing accuracy. • A closed-loop integrated model and attitude control algorithm is established. • ACS offset caused by control torque error and star sensor imaging error induced by micro vibration are presented. • The two errors significantly affect control indicators under steady-state response condition. • Control torque error appears in lower frequency band with small magnitude. • Star sensor imaging error mainly concentrates in high frequency band with considerable magnitude. [ABSTRACT FROM AUTHOR]

Water flow cooling is a cost-effective and environmentally friendly way to enhance the performance of a photovoltaic (PV) system. However, most of the studies have investigated a PV unit with water flow cooling in the steady-state condition. Therefore, as the novelty, this study aims at modeling and investigation of the system performance in the transient condition. For a 50W polycrystalline PV module, the annual experimental data is utilized to find its transient response to water flow cooling, which covers temperature and power improvement (ΔT and ΔP). An artificial neural network (ANN) is developed using the experimental data for prediction of ΔT and ΔP. ANN is validated and then, utilized to provide a comprehensive discussion about the impact of effective parameters on the system response. According to the results, for all the investigated cases, there is a threshold value for water flow rate. For instance, when wind velocity and ambient temperature are 1 ms−1 and 25 °C, the threshold values for the solar radiation values of 800, 1000, and 1200 Wm-2 are 0.009, 0.013, and 0.015 kgs−1, respectively. Moreover, irradiance and ambient temperature have great impacts on dimensionless ΔT and ΔP, while wind velocity is the least effective one. [ABSTRACT FROM AUTHOR]

Obtaining rock samples by drilling is an important method of asteroid detection. Due to the strict restrictions on the weight, volume, and weight on bit, conventional drilling devices are difficult to meet the requirements of drilling on an asteroid that has a weak gravitational field. This article proposed a rotary-percussive ultrasonic drill using a bonded-type piezoelectric actuator that can output harmonic vibration and elliptical trajectories simultaneously. The configuration and operation principle of the RPUD is presented and analyzed. Mode shape of the actuator and motions of the driving tips are verified by modal analysis and transient analysis, separately. Ultimately, a prototype of the RPUD is fabricated and experimentally investigated for its output characteristic and drilling performance. The test results indicate that the developed actuator can achieve the maximum no-load rotary speed of 119.2 r/min when the excitation frequency is 17.79 kHz. Furthermore, the maximum torque is 35 mNm, and the corresponding driving speed is about 20 r/min. The maximum drilling rate of the prototype to the sandstone is 7 mm per minute under a weight on bit of 5 N. The experimental results confirm that the proposed RPUD is feasible to drill rocks under a low weight on bit, which has the potential to obtain rock samples on an asteroid. [ABSTRACT FROM AUTHOR]

Recompression Brayton cycles using supercritical CO 2 as the working fluid appear as a prominent alternative for thermo-solar power applications. Also, solar energy's natural variability and intermittence make it difficult for solar plants to operate consistently and predictably. Thus, two of the most explored mitigating alternatives are thermal energy storage and auxiliary heating systems. Hence, this paper used actual meteorological data and transient numerical simulations to investigate the power output dynamics of a 10 MW plant. The modeling of an active control system of the working fluid mass inventory allowed the plant to operate in a stable manner while accounting for the significant variations in the fluid's thermophysical properties. Also, the study investigated the effect of the sizes of the thermal energy storage system and solar collectors field on the dynamics of the system. Finally, statistical analyses with actual meteorological data from Florianopolis/Brazil for nine days between 2017 and 2018 supported determining the optimal thermal energy storage system size. Hence, depending on the daily conditions, the results showed the operating settings that minimize the use of auxiliary heating with reductions of fuel consumption larger than 10%. [ABSTRACT FROM AUTHOR]

• Pipe viscoelasticity is incorporated in a fluid transient analysis via an internal variable constitutive theory. • The model unconditionally satisfies the second law of thermodynamics. • Model predictions agree well with experimental data. • Computation of energy dissipation in the fluid and pipe unveils the energy transfer mechanism between them in transient events. • The two-way interaction between the fluid and pipe is analyzed and explored. This work presents a fluid transient model capable of handling the viscoelastic behavior of the pipe. A previously developed quasi-2D flow model is employed as a base, and the viscoelastic behavior of the pipe is incorporated by considering constitutive equations formulated in a thermodynamically consistent framework of an internal variable theory. Such an approach straightforwardly provides expressions for computing the rates of energy dissipation in the fluid and pipe accurately and separately. This novel feature discerns the local and overall impacts of the energy dissipation on the pressure oscillations caused by each medium. The governing equations of the model form a hyperbolic system of partial differential equations whose approximated solutions are obtained by the method of characteristics. Taking as reference pressure signals obtained by a classic reservoir-pipe-valve experiment found in the literature, it is shown that the model predictions are fully consistent. A comparison between the pressure responses of viscoelastic and elastic pipes reveals that in addition to delaying the pressure oscillations, the viscoelastic behavior causes a faster attenuation of them. The rates of energy dissipation in the viscoelastic pipe attain significant magnitudes during the first moments of the fluid transient and alters the hydrodynamical behavior of the flow. Such interference is exposed by comparing the responses of the same experimental setup when two different viscoelastic pipe materials are considered. It is also shown that the knowledge of the parcels of energy dissipated in the fluid and pipe individually can improve the comprehension of the phenomenon and be utilized for theoretical and applied research in the field. [ABSTRACT FROM AUTHOR]

Taraxacum kok-saghyz Rodin (Tk) is a promising alternative rubber-producing grass. However, low biomass and rubber-producing capability limit its commercial application. As a carbon source transporter in plants, sugar will eventually be exported transporters (SWEETs) have been reported to play pivotal roles in diverse physiological events in the context of carbon assimilate transport and utilization. Theoretically, SWEETs would participate in Tk growth, development and response to environmental cues with relation to the accumulation of rubber and biomass, both of which rely on the input of carbon assimilates. Here, we identified 22 TkSWEET s through homology searching of the Tk genomes and bioinformatics analyses. RNA-seq and qRT-PCR analysis revealed these TkSWEETs to have overlapping yet distinct tissue expression patterns. Two TkSWEET isofroms, TkSWEET1 and TkSWEET12 expressed substantially in the latex, the cytoplasm of rubber-producing laticifers as well as the rubber source. As revealed by the transient expression analysis using Tk mesophyll protoplasts, both TkSWEET1 and TkSWEET12 were located in the plasma membrane. Heterologous expressions of the two TkSWEETs in a yeast mutant revealed that only TkSWEET1 exhibited apparent sugar transport activities, with a preference for monosaccharides. Interestingly, TkSWEET12 , the latex-predominant TkSWEET isoform, seemed to have evolved from a tandem duplication event that results in a cluster of six TkSWEET genes with the TkSWEET12 therein, suggesting its specialized roles in the laticifers. • This study is the first comprehensive analysis of SWEET s in Taraxacum kok-saghyz (Tk). • Of the two latex-abundant isoforms, TkSWEET1 and TkSWEET12 , only TkSWEET1 exhibited sugar transport capability. • Several pieces of evidence point to a special role of TkSWEET12 in the rubber-producing laticifers. [ABSTRACT FROM AUTHOR]

This paper presents a simple realization of the meminductor emulator using two operational transconductance amplifiers (OTAs) and two capacitors. To obtain different configurations of meminductor in the proposed design, one of the OTA has been replaced by a multi-output transconductance amplifier (MO-OTA). MO-OTA is a slightly modified version of conventional OTA that has multiple outputs. The design flexibilities offered by MO-OTA helped in achieving decremental as well as incremental configurations for both grounded and floating meminductor emulators. The proposed meminductor emulator realizations are very simple because these emulators do not employ an analog multiplier, resistor, or memristor. The pinched hysteresis curves have been acquired for the frequency range of 600 kHz–900 kHz for different values of capacitors. The proposed meminductor emulators have been designed and simulated with the help of the LTspice tool using TSMC 180 nm CMOS technology parameters. The pinched hysteresis loops, transient analysis, and non-volatility tests of the proposed meminductor emulators confirm their satisfactory behavior as meminductor. The functioning of proposed meminductor emulator circuits has also been tested by demonstrating their use in chaotic oscillators. • A very simple circuitry for grounded and floating meminductor emulators requiring only two OTAs and two capacitors. • Flexibility of switching between incremental and decremental meminductor emulators for both grounded and floating types. • Avoids the requirement of memristor, multiplier, and resistor in the realization. • Significant range of operating frequency. • Demonstration of chaotic responses obtained by Chua's oscillator using proposed meminductor emulator. [ABSTRACT FROM AUTHOR]

An enriched finite element approach with appropriate enrichment function is proposed for the transient analyses of wave propagations in nonhomogeneous media. In present method, the traditional linear nodal interpolation functions for low order finite elements are enriched by the augmented enrichment function. For the purpose of improving the computation accuracy and reducing the numerical dispersion error, the polynomial bases and the trigonometric functions are utilized to form the enrichment functions. In addition, a simple and direct approach is introduced with the aim to tackle the possible linear dependence of the system equations. The numerical results show that the accuracy of the obtained numerical results can be markedly improved by the proposed method in comparison with the standard finite elements. What's more, it can be found that the calculated solutions from the proposed method with the appropriate temporal discretization scheme are able to monotonically converge to the exact solution in transient wave analysis. In consequence, it is possible to consistently increase the solution accuracy by directly decreasing temporal discretization step size. This valuable and important property enable the present approach to be particularly suitable to tackle the wave propagations in nonhomogeneous media. [ABSTRACT FROM AUTHOR]

• A three-zone extraction system in solar ponds for desalination is proposed. • Temperature drop across exchanger surfaces is considered. • Simplified model is validated with theoretical results of literature. • Possible extraction mechanisms are compared quantitatively and qualitatively. • Influence of user defined parameters on distillate output is investigated. A solar pond from which thermal energy is extracted from its non-convective zone (NCZ), lower convective zone (LCZ) and the ground below is modelled in transient state. The novelty of the study lies in the fact that heat extraction in each of the three zones is considered to be realistic, taking into account temperature drop across the exchanger surfaces. The pertinent weather parameters are described by curve fitting as series of sinusoidal time functions. Using these expressions, implicit finite difference method is used to solve the five coupled partial differential equations involved in the analysis, and the scaled down model is validated with simpler models available in the literature. To quantify the practical utility of pond, the final outgoing water stream heated from the pond is fed to a large scale solar still to assess the usefulness in a desalination application. Annual distillate production of the still coupled to such a pond is calculated and its variation with various manually adjustable parameters is studied. A total of 9 such parameters have been investigated. It is observed that there are five pond parameters related to pond's operation that possess optimum values that maximize annual distillate production. These are: NCZ and LCZ thicknesses, NCZ and LCZ exchanger pipes' radii, and ground extraction mass flow rate. An increase in any of the remaining parameters: upper convective zone (UCZ) thickness, ground exchanger pipes' radius and NCZ , LCZ extraction mass flow rates generate a decrease in distillate produced. It is also revealed that extraction should be carried from how many zones depends on the application coupled to the pond, and in this case, where the application is a solar still, LCZ with ground extraction turns out to be the best choice. Further, the assumption of ideal NCZ and ground extraction used in the literature is seen to overestimate system output by nearly 46%. Therefore, this model is a generalized one and various other single or dual zone extraction models available so far become subsets of it. This generalized model presented here can serve to design such a triple zone extraction based solar pond system in a realistic and practical manner and help evaluate suitable values of user-controlled variables that yield maximum output of the application to which the pond supplies energy. [ABSTRACT FROM AUTHOR]

Cerebellar mutism syndrome is a debilitating postoperative neurological complication following posterior fossa surgery in children. It is characterized by a significant lack or loss of speech. Injury to the dentato-thalamo-cortical pathway is thought to be the main anatomical substrate of cerebellar mutism syndrome; however, few studies have investigated the physiological changes using computed electroencephalogram. Herein, we report a case of a nine-year-old girl who developed cerebellar mutism syndrome after excision of an ependymoma of the fourth ventricle and was followed up with evaluation of aphasia, gross motor function, and scalp electroencephalograms. Her language, dysmetria and gait ataxia gradually improved until day 605 after onset. Computed electroencephalogram analyses were performed for the relative power spectrum and connectivity at each frequency band. On the three electroencephalograms at days 109, 299, and 605 after onset, the relative power spectrum at the delta band transiently decreased and then increased, and the relative power spectrums at theta, beta, and gamma bands transiently increased and then decreased. Only the relative power spectrum in the alpha band continuously increased in the occipital area. Additionally, brain connectivity in the delta, beta, and gamma bands increased continuously. We report a case of cerebellar mutism syndrome with recovery of language, dysmetria and gait ataxia in 20 months. Electroencephalogram analyses indicated transient changes in the powers of brain activity and continuous improvements in connectivity during the long follow-up, reflecting the plasticity and remodeling of brain function after cerebellar mutism syndrome. Power and connectivity analyses for EEG might be a tool to investigate underlying pathophysiology of cerebellar mutism syndrome. [ABSTRACT FROM AUTHOR]

It is important to ensure the transient safety and stability of Hydropower generating system (HGS) both in the design and operation stages. Many uncertainties in the Hydropower Generating Units (HGUs) have a strong effect on the transient characteristics. In this study, a transient analysis framework under parameter uncertainty is proposed, which includes: integrating modeling, uncertain transient analysis, and transient calibration. First, not only a physical HGS including a comprehensive model of hydro-turbine but also Polynomial-Chaos-Kriging data-driven models are established for transient considering uncertain HGU parameters. Secondly, based on the evaluation system, the contributions of uncertain HGU parameters on the transient characteristics are quantified objectively. The results show that: (1) in evaluation systems, 6 HGU parameters play a key effect on transient characteristics, and the uncertain properties of 6 indicators can reach moderate variabilities; (2) the effect of HGU uncertainty can be reduced by optimizing the control strategies. Finally, uncertain HGU parameters are calibrated considering 3 measured transient processes. Compared with the conventional HGU model, the max relative absolute error of the volute pressure, the HGU speed, and the servomotor stroke are reduced by 2.14%, 2.70%, and 37.81%. This framework provides new insight into the effect of the uncertain HGU model on transient characteristics, which could be beneficial for the safe and stable operation of HGSs. • Propose a transient analysis framework for parameter uncertainty analysis and transient calibration. • Quantify and rank the contribution of the major influencing HGU parameters to transient characteristics. • The max error in P v , n t, and Y s are reduced by 2.14%, 2.70%, and 37.81% using the calibrated model. • Guide uncertain transient analysis of hydropower generating systems in both the design and operation stages. [ABSTRACT FROM AUTHOR]

• A novel PINN-based method for transient analysis in pipe networks. • An elastic water column model is employed to simplify the network modelling. • Hydraulic transient physics is integrated with measured data. • Pressure heads at unmonitored locations in a network can be estimated. Reconstructing transient states presents significant challenges, particularly within complex pipe networks. These challenges arise due to nonlinear behaviours, inherent uncertainties in the system, and limitations in data availability. This work proposed a novel approach employing Physics-Informed Neural Networks (PINN) to reconstruct transient states in pipe networks, even with limited sensor data. To integrate the complex topology of pipe network systems into neural networks, the method integrates the PINN framework with an efficient elastic water column (EWC) model which can be simply formulated across diverse pipe network configurations. The results showed the proposed PINN method can accurately reconstruct the pressure and flow variation at unmonitored locations, even provided with noisy data at a limited number of locations. One of its advantages lies in its ability to effectively capture extreme values that hold potential significance for pipe infrastructure, providing a promising avenue for pipe failure analysis and enhanced safety management. Laboratory experiments have also been conducted to validate the efficacy and reliability of this method, thus further underlining its potential for real-world applications. [Display omitted] [ABSTRACT FROM AUTHOR]

• Transient CO oxidation titrates binuclear Cu2+ structures in Cu-CHA catalysts. • Extrapolation of short CO oxidation tests suggests ZCu2+(OH)- as precursors. • An extended CO exposure test proves complete ZCu2+(OH)- conversion. • All NH 3 -solvated ZCu2+(OH)- cations are converted to binuclear Cu2+ complexes. • The CO oxidation methodology is validated over a monolith catalyst. The nuclearity of Cu2+ species active in the low-temperature Reduction Half Cycle (RHC) of NOx Selective Catalytic Reduction with NH 3 over Cu-CHA catalysts is controversial. In the past, transient CO to CO 2 oxidation protocols have been used to titrate binuclear Cu2+ species, and identified NH 3 -solvated ZCu2+(OH)- ions as their precursors. However, the prior results relied on asymptotic extrapolation due to the very slow CO oxidation kinetics. We herein present the results from a prolonged (24 h) CO titration experiment under dry conditions over an industrial Cu-SSZ-13 catalyst: the results demonstrate the conversion of all ZCu2+(OH)- ions to binuclear Cu2+ complexes and agree well with the extrapolation of a shorter (90 min) experiment, based on the assumption of the CO oxidation rate being second order in ZCu2+(OH)-. These outcomes confirm the adequacy of short CO oxidation tests to titrate ZCu2+(OH)- ions and support a Cu2+ pair mediated RHC pathway. [ABSTRACT FROM AUTHOR]

• A new analytically modified EDFM (AEDFM) is developed to analyze the pressure transient behaviors of fluid flow using structured Cartesian grids. • The skin factor in the Well Index only accounts for the additional pressure drop within the hydraulic fracture, which can lead to substantial errors. AEDFM can effectively address this limitation. • The results show that AEDFM can accurately capture pressure transient behaviors of fluid flow around fractures. Even more significant is that AEDFM, with fewer grids, can significantly reduce computational costs. In the past few decades, multi-stage hydraulic fracturing has emerged as a crucial technology for the commercial development of unconventional oil and gas (UOG) resources. It is crucial to accurately and efficiently characterize transient fluid flow near fractures, which is a critical concern for many researchers. Discrete fracture models (DFMs) are primarily used to analyze the pressure transient behaviors of fluid flow in naturally fractured porous media. DFMs can accurately capture transient fluid flow near fractures, but they require a substantial number of grids to ensure computational accuracy, leading to higher computational costs. On the other hand, standard embedded discrete fracture models (EDFMs) based on pseudo-steady-state assumptions are computationally efficient, but they struggle to model the early transient fluid flow near fractures accurately. To address this limitation, we propose a new analytically modified EDFM (AEDFM) with structured Cartesian grids for analyzing the pressure transient behaviors of fluid flow in naturally fractured porous media. The transmissibility between the matrix and fractures is adjusted by multiplying it with a transient factor. In addition, we have validated the accuracy and efficiency of our proposed model through comparisons with results from analytical models and a standard well-testing software package. The results demonstrate the significance of our proposed model in accurately capturing transient fluid flow around fractures and reducing computational costs. In this work, we analyze the pressure transient behaviors of fluid flow using various parameter values and further evaluate the significance of the proposed modifications. The results indicate that AEDFM can effectively match the early nonlinear pressure drop near fractures compared to the standard EDFM. This work presents a powerful tool for the fast and accurate analysis of pressure transient behaviors of fluid flow in naturally fractured porous media. [ABSTRACT FROM AUTHOR]

• A novel multi-scale domain overlapping method is applied to the transient analysis of Xi'an pulsed reactor. • When the maximum time step of involved codes RELAP5 and CTF is 0.1 s, the stability and efficiency are the best. • The results of coupling calculation are closer to the experimental data than the standalone system code. • The trend of global parameters and detailed distribution of local are obtained by coupling calculation. Multi-scale thermal–hydraulic coupled calculation is widely applied in the design and safety analysis of reactor. It can provide the thermal–hydraulic results with high-fidelity and high-resolution. According to natural circulation flow requirement of Xi'an pulsed reactor (XAPR), which is a pool-type reactor with natural circulation, a novel multi-scale coupling method of domain overlapping for XAPR is proposed. The system code RELAP5 and subchannel code CTF are coupled. The explicit coupling strategy is applied to the pulsed operation transient condition of XAPR. The results show that the transient coupling strategy is effective, and the results of coupled calculation are closer to the experimental data than those of standalone system code. Meanwhile, the coupled calculation has advantages in obtaining local detailed thermal–hydraulic characteristics. Furthermore, the method is applied to the research of station blackout (SBO) accident of XAPR, and sensitivity analysis of the coupling time-step is carried out. The results indicate that the stability and efficiency are best when the maximum time-step is set as 0.1 s. Meanwhile, in the transient analysis of accident, the multi-scale coupled calculation could provide high-fidelity, high-precision and high-resolution thermal–hydraulic results, which proves the validity and advantage of coupled calculation. [ABSTRACT FROM AUTHOR]

The adoption of Distributed Generation (DG) technology has seen a substantial level of advancement in recent years. This has created potential protection issues in microgrids during faults and islanding. This paper proposes a fault and islanding detection method using wavelet packet transform (WPT) and Ensemble. A new index called Normalized RMS Node power index (NRNPI) is defined based on WPT to differentiate between transient behavior during faults and islanding, and the ensemble acts as a classifier. The ability of the method in detecting islanding and both grounded and non-grounded faults is demonstrated through simulations of a test system in Matlab Simulink. Real time simulation of the proposed method is done in OPAL-RT using UDP-IP communication protocol. The proposed method as an islanding detection technique gives an accuracy of 100% and 99.32 % as a fault detection technique under the test conditions. Results of both simulations and Hardware in Loop (HIL) implementation is promising. The proposed method has the potential of extending the idea for other transient analysis in the microgrid. • Method capable of detecting islanding and faults in AC microgrid. • Wavelet packet transform used for feature extraction from measured signals. • Ensemble machine learning technique is used for classification of faults and island. • Applicable for microgrids with single distributed generator. • Fast and accurate islanding and fault detection method. [ABSTRACT FROM AUTHOR]

[Display omitted] • Iron oxide nanofluids were synthesized by microemulsion and analyzed with a Michelson interferometer. • A double stage Fast Fourier Transform analysis explored the dynamic properties of the nanofluid. • The linear effects of sedimentation of nanoparticles had a greater impact on the optical properties. • The nonlinear interactions between nanoparticles had more influence on the electrical conductivity. Iron oxide nanoparticles (IONPs) exhibit low toxicity and high chemical stability, attractive for developing of nanofluids (NFs) for advanced medical applications. This research focuses on the study of the optical, mechanical, and electrical dynamics of iron oxide–ethanol NFs. A novel sensitive methodology for analyzing the influence of nanoparticles (NPs) over the optical and electrical processes exhibited by IONFs is reported. The IONPs were synthesized by a microemulsion route and were characterized by transmission electron microscopy, scanning electron microscopy, and X-ray diffraction. The NPs exhibit a mean diameter of 30 nm and they were identified as Fe 2 O 3. UV–Vis spectroscopy allows us determining the volume fraction of the fluid as a function of time. The assistance of a Michelson interferometer integrated with an image processing methodology was employed to explore the dynamics of the nanostructures. The percentage of NPs involved in linear and nonlinear dynamic fluid processes was estimated by taking a double-stage (spatial and frequency domains) Fast Fourier Transform in the interferometric pattern. A DC voltage source was used to study the electrical conductivity of the NF as it was being sedimented. The opto-mechatronic parameters were correlated, considering the volume fraction as the main variable to determine the optical and electrical characteristics. For the Fe 2 O 3 NF, it is identified that the linear effects of sedimentation present a stronger impact on the optical properties, while the nonlinear interactions have more influence on the electrical conductivity. The main findings of this research have potential applications in rheological instrumentation to analyze complex effects using transient opto-mechatronic components. [ABSTRACT FROM AUTHOR]

To study the safety characteristics of an ultra-small (5.2 MWt) lithium-cooled space reactor power system (ULCR) under postulated accidents, a transient analysis code for the ultra-small space reactor coupled with a closed Brayton cycle dynamic conversion and heat pipe radiator was established. A preliminary analysis of four typical postulated accidents occurring at 100 percent power in-orbit operation of the ULCR system was conducted to define postulated problem areas and establish safety requirements. The postulated accidents mainly include (1) reactivity insertions, (2) coolant partial flow loss, (3) turbomachinery failure, and (4) radiator partial failure. The results showed that: a) since the ULCR system was designed to operate at high-temperature conditions (coolant temperature greater than 1500 K), the safety margin of the ULCR system was small. Emergency shutdown control or reduced power operation action should be taken proactively to ensure ULCR's safety in different accidents. b) When the control rod was misoperated and large reactivity was inserted, the maximum temperature of the lithium coolant was very close to the saturation temperature (the difference was 24 K), and the system was operated at extremely high temperatures (the average temperature of the core coolant was 1750 K); c) In coolant flow loss accident, when the coolant flow of the system dropped below 40% of the rated mass flow, the lithium coolant boiling would occur in the primary loop system, and the emergency shutdown control action was required to ensure the safety of the system. [ABSTRACT FROM AUTHOR]

This paper focuses on the nonlinear behaviors of offset-halves journal bearings (OHJBs), particularly under dynamic loading and journal misalignment. A new tribo-dynamic model is given to perform transient thermoelastohydrodynamic analysis in the crucial yet understudied domain of this novel structure. Bearing characteristics are compared among bi-directional misalignment, single-direction misalignment as well as alignment. The results demonstrate that the influence of bi-directional misalignment exerts dominance. Moreover, the evolution mechanisms of bi-directional misalignment and step loading on the time-varying stiffness and damping are evaluated. In addition, parametric analyses are done to emphasize key factors in the bearing design, including the horizontal offset and radial clearance, for better transient lubrication performance. This study enriches the structural optimum for dynamically loaded journal bearings. [Display omitted] [ABSTRACT FROM AUTHOR]

The journal-thrust coupled bearing (abbreviated as JTC bearing) works at the end of the crankshaft in diesel engine, with the function of carrying radial load and prevent axial movement of the crankshaft. The journal part and the thrust part of this special bearing both form the oil film lubrication when subjected to the time-varying loads in axial and radial directions during the working condition. In this work, the JTC bearing in marine diesel engines was analyzed using a transient thermal elastohydrodynamic (TEHD) lubrication model. The thermal and pressure (thermal-pressure) coupled effects were taken into consideration based on the flow, pressure, and thermal continuity conditions between the journal and thrust parts. Moreover, the transient time-varying load was considered in the lubrication analysis to explore the coupled effect under the actual operating conditions. A test rig was built to validate the established transient TEHD lubrication model for the JTC bearing. The thermal-pressure coupled effect between the journal and thrust parts was found to significantly affect the transient lubrication behaviors of the JTC bearing, which cannot be ignored. Also, different boundary conditions were investigated for the influence of the coupled effect on transient lubrication characteristics, including axial clearances, radial clearances, waveforms of radial load, incline angles and inlet oil temperatures. This work could theoretically support the lubrication design of the JTC bearings used in the diesel engine crankshafts. [ABSTRACT FROM AUTHOR]

The supercritical carbon dioxide (sCO 2) heat removal system, which is based on multiple closed Brayton cycles with sCO 2 as the working fluid, is an innovative, self-propelling and modular heat removal system for existing and future nuclear power plants. Previous studies analysed its design, layout, control and operation. In addition, this study considers different sudden failures during the accident progress, e.g. failure of single sCO 2 cycles, control systems and valves. These abnormal conditions were investigated with the thermal-hydraulic system code ATHLET for a generic Konvoi pressurized water reactor. In most cases, the failure of a single sCO 2 cycle can be compensated. On the one hand, failure of the fans of the gas cooler leads to a pressure increase which may be mitigated by an inventory control system or cycle shutdown. On the other hand, unintended fan speed-up can cause compressor surge without adequate countermeasures. Furthermore, the system can operate under the cyclic blow-off from the steam generator safety valves when the relief valves are not available. Finally, the unintended closure of the valve which controls the steam flow through the compact heat exchanger triggers a fast cycle shutdown but a subsequent restart might be possible. • Transient simulation of a supercritical carbon dioxide heat removal system. • Successful operation in interaction with a pressurized water reactor. • Analysis of different sudden failures, e.g. of single cycles, control systems and valves. • Some failures are mitigated by the applied robust design of the heat removal system. • For other failures, fast interventions or further design or control improvements are proposed. [ABSTRACT FROM AUTHOR]

• The mechanism of negative bias instability in commercial silicon carbide Metal-Oxide-Semiconductor Field-Effect Transistors has been explained through the analysis of transient gate currents. • Experimental results demonstrate that near-interface traps with energy levels aligned to the valence band trap holes from the valence band by tunneling. • The transients in the gate current correspond to the trapping of holes by the near-interface traps. • The study demonstrates the impact of the aluminum implantation process on the p-type region, highlighting its role in hole trapping. This article explains the mechanisms of negative bias instability in commercial n-channel SiC metal–oxide semiconductor field-effect transistors (MOSFETs) by analysis of transient gate currents. The current–voltage measurements were performed at different temperatures along with capacitance–voltage measurements to characterise hole trapping and de-trapping in planar SiC MOSFETs. The experimental results reveal that near-interface traps (NITs) with energy levels aligned to the valence band trap holes from the valence band by tunneling, which is different from published results about NITs with energy levels aligned to the energy gap. The impact of the aluminium implantation process of the p-type region on hole trapping is also demonstrated. The presented analysis also reveals that the hole trapping by NITs is limited to the p-type region, indicating that the aluminium implantation process is responsible for the detected NITs. [ABSTRACT FROM AUTHOR]

Several innovations have been devised to design a system with lower capital cost and passive safety features in NuScale SMR. The system incorporates primary natural circulation and helically-coiled steam generators, leading to unique dynamical and stability aspects. A mathematical model is developed for both the primary and secondary sides of the reactor, consisting of 56 coupled ordinary differential equations (ODEs). A computer code, named DYSN (DYnamics Simulator for NuScale), is also created to simulate transients in the primary and secondary sides of the NuScale reactor. The DYSN code model comprised a system of equations for the core, steam generator, pressurizer, hot leg riser, and downcomer based on their governing equations. The analysis of the code results for the steady-state condition indicates that the values calculated by DYSN are in good agreement with the reactor's design data. To evaluate the capability of the code for predicting reactor dynamics, three different transient scenarios, including ramp change in core reactivity, secondary system feedwater mass flow rate, as well as feedwater temperature variations, are considered. The reactor's response to each scenario is computed using DYSN and then compared with the results calculated by the RELAP5 reactor model. Both models demonstrate a consistent trend of variation for the scenarios. The computational cost of DYSN for the same scenario is significantly lower than that of RELAP5, making it suitable for assessing system response and designing controllers. Additionally, this code can interface with controller and deep learning modules of Python, for future studies. • A mathematical model is developed for the calculation of the NuScale-SMR response to various transients. • A computer code, named DYSN, is developed based on the plant mathematical model and Python programming. • The model response is evaluated in several scenarios, and the results are compared with the RELAP5 model of the NuScale. • The DYSN code computes the performance of the helically-coiled steam generator and the natural circulation primary loop. • The DYSN code execution time is, on average, 132 times faster than the RELAP5 model for the analyzed transient scenarios. [ABSTRACT FROM AUTHOR]

Natural circulating steam generators are extensively applied in pressurized water reactor units, where the water level control is a tough challenge. During transients, the water level may change drastically, and its reverse dynamic characteristics may even cause safety concerns. This article studies the dynamic effects of several crucial impact factors on the level, including their gains, time constants, and coupling relationships. Considering the impact and the inter connections of these factors, a dynamic distributed parameter mechanism model for real-time water level estimation is constructed. It consists of three sub-models: the close-loop control system model, the mass and heat transfer model, and the momentum transfer model. Solving these models, one may yield the flow rates of the inputs and outputs of the downcomer channel. Then, the level is determined employing the dynamic conservation for the feedwater chamber. Pseudo-online simulation studies are carried out with the measurements from an operating 1000 MW unit during the full load rejection test. • Impact factors affecting the steam generator water level are studied quantitively. • A dynamic distributed parameter model of steam generator water level is established. • The proposed model is validated using measured data during load rejection transients. • Comparison suggests the accuracy of water level simulation with a mean error of 0.13%. • The model is suitable for online application since each-step simulation takes only 7 ms. [ABSTRACT FROM AUTHOR]

This paper describes a novel methodology for the analysis of transient nuclear criticality in layered aqueous-emulsion-organic plutonium nitrate systems. The presented methodology includes point neutron kinetics equations coupled with phenomenological one-dimensional nuclear thermal hydraulics models, which describe the variation in mass, power, reactivity, temperature and voidage within the system. Equations to describe the mean neutron generation time and changes in reactivity due to changes in the system's temperature and void fraction are formulated from fits of the results predicted by the criticality transient multiphysics model. Using these developed models, the nuclear criticality incident that occurred at the Windscale Works in 1970 is analysed and presented. In this criticality transient, two immiscible fissile liquids (an aqueous solution and an organic solvent) were disturbed such that an emulsion layer formed between them, inducing a transient nuclear criticality excursion and yielding around 1 0 15 fissions. It was determined that parameters such as emulsion globule size and vessel outlet pipe radius had negligible impact on the total fission yield of the corresponding transient when compared to variations in organic solvent volume and emulsion band thickness. Several possible configurations were identified which could result in a transient similar to that of the Windscale Works in 1970. Notably, a system containing 39.75 L of organic solvent which underwent a transient with the formation of an emulsion band that was a maximum of 5.4 cm thick and 54% aqueous solution by volume yielded 9 × 1 0 14 fissions, and thus is expected to closely resemble the 1970 Windscale nuclear criticality incident. However, the uncertainties associated with the original transient and the system parameters (e.g. thermophysical properties of the three layers) are such that the configuration is likely to vary from these exact quantities. • Models to simulate transient nuclear criticality in layered liquids are developed. • Material properties of plutonium nitrate phases are determined. • Kinetics and reactivity feedback data are determined. • The nuclear criticality incident at the Windscale Works in 1970 is investigated. • Transient variations, e.g. in power and thermal hydraulics, are investigated. [ABSTRACT FROM AUTHOR]

• The magnitude of current and electromagnetic force was calculated through simulation analysis combined with theoretical formulas. • The target plate structure was calculated through finite element analysis under the influence of eddy currents and halo current electromagnetic forces. • Transient dynamic analysis was conducted using modal superposition method. • Based on the safety performance evaluation criterion 3Sm for internal components of fusion devices, the safety performance assessment of the structure was conducted. China Fusion Engineering Test Reactor (CFETR) is a fully superconducting tokamak device independently designed and developed by China. The divertor of CFETR is one of the core components, which will withstand huge and complex electromagnetic loads. Electromagnetic loads are often of large magnitude and short duration, which will cause impact damage to internal components.During the plasma disruption event, the plasma current drops rapidly in milliseconds, which creates large eddy currents on the divertor, and eddy current will generate electromagnetic force and torque under the action of toroidal and poloidal magnetic field, which will cause the divertor to be pulled, compressed or twisted; during the plasma vertical displacement event, halo current is generated on the plasma surface, then a large electromagnetic force will be generated on the divertor under the action of the toroidal and the poloidal magnetic field.In this paper, the electromagnetic analysis under the action of halo current and eddy current is carried out for the hypervapotron structure, and transient dynamic analysis of the real stress state during the electromagnetic load impact process is simulated.Strength analysis based on the results of transient analysis shows that the structure has a high reliability. The work in this paper is based on the evaluation of reliability of the hypervapotron structure under the maximum electromagnetic load. [ABSTRACT FROM AUTHOR]

One of the crucial steps in the European Roadmap to the realisation of fusion energy is the design and construction of the Demo-orientated NEutron Source (DONES) facility. DONES is a fusion-like neutron source, based on the International Fusion Materials Irradiation Facility (IFMIF) concept, aimed at qualifying and testing the materials to be used in fusion reactors. The Target System (TSY) is a crucial system as it is the component where the interactions between deuterons and a liquid lithium target, flowing on a solid surface (i.e. the Back Plate), take place to produce neutrons for irradiating the testing materials. In this regard, an investigation campaign has been performed to evaluate the thermo-mechanical behaviour of the DONES TSY under selected steady state and transient loading conditions, in light of the most recent design updates (new bellows and connection systems). The first part of the assessment concerned the analysis of the TSY under the normal operation steady state loading scenario. A detailed 3D FEM model has been set up, considering the newest updates of the TSY geometry and of the operational parameters, and a thermo-mechanical analysis has been launched. Results have been mainly checked in terms of TSY global deformation, focusing on the Back Plate and on the connecting bellows displacements, in order to exclude overlapping with the High Flux Test Module and misalignments with the beam footprint. Afterwards, since the lithium inlet temperature has been increased from 250 °C to 300 °C, a transient thermo-mechanical analysis of the TSY under the start-up loading conditions has been performed to check if it is able to withstand the hotter lithium flow according to the RCC-MRx criteria. Therefore, the reference pre-heating strategy has been adopted, assessing the thermal and mechanical behaviour of the TSY, focusing on the Back Plate. The obtained results are presented and critically discussed, suggesting important recommendations for the follow-up of the design. [ABSTRACT FROM AUTHOR]

• Zeolite Molecular Sieve bed adopted for tritiated water removal from helium primary coolant. • Analysis of the integral process involved in the regeneration of ZMS bed and in the recovery of tritiated water. • A dynamic model developed in MATLAB simulates the adsorption/desorption phases of the ZMS bed. • A RELAP5/MOD3.3 model developed for the transient analysis of the regeneration loop. • The proposed procedure ensure a continuous operation of the Coolant Purification System and a regeneration efficiency of the ZMS bed of 74.4 %. Zeolite Molecular Sieves (ZMSs) are commonly adopted in tritium handling facilities for impurity removal from gaseous streams, particularly for tritiated water trapping. Several activities have been conducted to characterize the adsorption and desorption behaviour of the sieving materials. Instead, less attention has been put on the analysis of the integral process comprising the adsorption of the tritiated humidity, the regeneration of the molecular sieve and the recovery of the desorbed water. Focusing on the application for the EU-DEMO helium Coolant Purification System (CPS), this work presents a process simulator relying on a MATLAB dynamic model of the ZMS bed and on a RELAP5/MOD3.3 model for the regeneration loop. The dynamic model can simulate both the adsorption and regeneration modes of the ZMS by providing the temperature and the adsorbate concentration profile along the column, while the thermal-hydraulic model is used to assess the conditions of the regeneration loop. By coupling the outcomes of the two models it is possible to establish the effective regeneration efficiency of the process and the amount of the tritiated water recovered. For the case of helium CPS, the analysis demonstrates the feasibility of the proposed operative scheme and the capabilities of the regeneration procedure to ensure a 74.4 % regeneration efficiency of the ZMS bed. [ABSTRACT FROM AUTHOR]

• The open loop dynamic response characteristics of a novel compact megawatt nuclear power system with a heat pipe reactor coupled supercritical CO 2 Brayton cycle is been done. • The self-developed transient analysis code for heat pipe reactors (TAPIRS) and that for S-CO 2 Brayton cycles (SCTRAN/CO 2) are coupled. • Two different modes, "load-following" and "reactor-following", are studied and the advantages and disadvantages of the two different modes are analyzed. • Sensitivity analysis of different control setpoints are have been done, and the relationship between the loop flowrate, turbine inlet temperature and core power is discussed. A novel compact megawatt nuclear power system with a heat pipe reactor coupled supercritical CO 2 Brayton cycle has been proposed. To investigate its transient operational characteristics, this paper conducts open-loop dynamic response analyses and designs control systems for it under the load-following mode and the reactor-following mode. Subsequently, transient operational characteristics analysis of the system under different operating conditions is conducted. The results indicate that under load-following conditions, the rotation speed is highly sensitive to disturbances. The system can achieve a load variation of 0–100 % at a rate of 6 %FP/min, while at higher rates, there may be a decrease in speed due to exceeding the regulating range of the bypass valve. It can also accommodate continuous stepped load variations and operate at any desired load level. Under load rejection conditions, the system experiences significant fluctuations, but it can still maintain a new steady state and keep parameters within a safe range. In reactor-following mode, the system can achieve rapid power changes. [ABSTRACT FROM AUTHOR]

During the load rejection condition of the pump-turbines, the S -shaped characteristic would lead to intense pressure pulsations, thus threatening the safe operation of the pumped storage plants (PSPs). Extracting water harmer pressure (WHP) and pulsating pressure (PP) from the measured pressure signals is of great engineering significance. As a result, this study proposes a novel multi-step extraction framework for the WHP. First, a theoretical method for extracting WHP is developed by analyzing the transient properties of the pressure pulsations. Subsequently, a denoising strategy combining improved variational mode decomposition (IVMD) and multi-level wavelet denoising (MWD) is presented to reduce noise interference. The proposed IVMD is used to reduce wideband noise, and the MWD method is developed to reduce narrow-band noise within the IVMD decompositions. Finally, the proposed method's effectiveness is verified using spiral case inlet and draft tube inlet pressure signals acquired from a prototype pump-turbine of 375 MW. The results show that the proposed denoising method can effectively reduce noise interference and accurately extract WHP. This study provides an innovative and theoretically-based method for extracting WHP and PP, which has important engineering significance for the safe operation of PSPs. • The measured pressure pulsations of PSP load rejection are analyzed and processed. • A novel and theoretically-based method is presented for extracting WHP. • A pressure pulsations denoising method based on the IVMD and MWD is designed. • The effectiveness of the proposed method is verified using two application cases. [ABSTRACT FROM AUTHOR]

In this article, a dopingless TFET with dual-drain and reversed T-shaped channel (DLVIT-TFET) is investigated to offer improvement in ON-state current (I On) along with the reduction in OFF-state leakage current (I Off) and in ambipolarity. The investigated device has a dual channel region which helps in improving the on-state parameters like I On and subthreshold swing (SS) due to the extended tunneling area. The inverted T-shaped channel minimizes the charge carriers to tunnel during the off-state, thereby reducing the magnitude of I Off. The results obtained from 2D TCAD simulation show that the investigated device provides ∼1 order of improvement in I On and ∼3 orders of improvement in I Off. Furthermore, DLVIT-TFET offers an ∼3 orders of improvement in ambipolar current (I Amb) due to a reduction in peak electric field at channel-drain interface caused by splitting of drain potential at ambipolar state. Moreover, various analog/RF parameters such as transconductance (g m), gate parasitic capacitance (C gd , and C gs), cut-off frequency (f Tmax), gain-bandwidth product (GBP), transconductance-frequency product (TFP) and transit time (τ) are found to be improved in DLVIT-TFET compared to the conventional DL-TFET. In addition, the transient analysis of DLVIT-TFET based inverter is analyzed, which shows improvement in the parameters like propagation delay and voltage swing. Finally, reliability of the investigated device is discussed by considering the effect of interface trap charges (ITCs) and variation in ambient temperature and it is observed that DLVIT-TFET is more immune to such defects and environmental factors than the conventional one. [ABSTRACT FROM AUTHOR]

The inclusion of automation mechanisms in the intricate design of power management units (PMUs) is long pursued in industry. This paper addresses a mixed-signal design flow whose purpose is to automatically produce, from the system-level to the ready-for-tape-out layout, complex PMUs when given a set of specifications. Particularly, in that flow, at the IP level, the proper analysis of the design tradeoffs is tedious and impractical, as a large amount of conflicting performance figures obtained from transient analysis for typical and multiple process/temperature corners, must be considered simultaneously. Therefore, it is common for the design cycle of a single integrated charge pump required in a state-of-the-art PMU to surpass a full month, depending on the intended technology, devices' types and operation voltages. Additionally, by the end of this process, circuit designers often end up with a limited vision of the attainable performances. However, due to the recent improvements in computational power of modern workstations, optimization-based techniques with expensive evaluation mechanisms are now perceived as a potential solution to pursue optimal sizing and layout. Therefore, an academic electronic design automation tool is adapted and applied to explore the performance boundaries of a charge pump in a 180-nm technology node and determine the optimal tradeoffs between performance and the, severely constrained, layout area. In the last step, a worst-case corner optimization on a 45- and 99- dimensional design and performance spaces, respectively, derived from 9 time-consuming transient analysis of each candidate solution, produced 35 design solutions that provide a thorough analysis between worst-case efficiency, voltage drop, and rise and fall times, impossible to perform in the manual design. The obtained insights on the design space were used to speed-up the process of devising a solution for tape-out. [ABSTRACT FROM AUTHOR]

The WHO considers schistosomiasis, which is controlled by the mass administration of the drug praziquantel (PZQ), to be a neglected tropical disease. Despite its clinical use for over four decades, PZQ remains the only choice of chemotherapy against this disease. Regarding the previous studies that demonstrated that PZQ activates the transient receptor potential (TRP) channel in Schistosoma mansoni (Sm.TRPM PZQ), the expression profile of the ortholog of this channel gene (Smp_246790.5) in S. japonicum (EWB00_008853) (Sj.TRPM PZQ) was analyzed. The relative expression of this gene in various stages of the parasite lifecycle was analyzed by quantitative real-time reverse transcription-PCR (qRT-PCR), and the expression of Sj.TRPM PZQ was observed by immunohistochemical staining using anti-serum against the recombinant Sj.TRPM PZQ protein. qRT-PCR revealed the significantly lower mRNA expression in the snail stage in comparison to other stages (p < 0.01). The relative quantity of the Sj.TRPM PZQ expression for paired females, unpaired males, and eggs was 60%, 56%, and 68%, respectively, in comparison to paired males that showed the highest expression (p < 0.05). Interestingly, immunostaining demonstrated that Sj.TRPM PZQ is expressed in the parenchyma which contains muscle cells, neuronal cells and tegument cells in adult worms. This may support the two major effects of PZQ—worm paralysis and tegument disruption—induced by channel activation. Moreover, the channel was expressed in both the eggshell and the miracidia inside, but could not be observed in sporocyst. These results suggest that the expression of Sj.TRPM PQZ corresponds to the known sensitivity of S. japonicum to PZQ. [Display omitted] • EWB00_008853 (Sj.TRPM PZQ) of S. japonicum was obtained as orthologous gene of S. mansoni (Sm.TRPM PZQ). • The expression profile of EWB00_008853 do not contradict the sensitivity of S. japonicum to PZQ. • Sj.TRPM PZQ is expressed in the parenchyma in adult worms but not in the tegument layer. [ABSTRACT FROM AUTHOR]

This manuscript presents the fuel performance analysis results of the General Atomics Fast Modular Reactor (FMR) based on an axi-symmetric (2D-RZ) geometry. Three fuel performance model sets that fit the FMR fuel specifications best, i.e., a BISON baseline model set, a BISON diffusion enhancement model set, and a BISON-FASTGRASS model set, were identified and evaluated against a series of relevant experimental cases featuring high burnup and low irradiation temperature conditions. The three BISON-based model sets were then utilized to conduct a comprehensive fuel performance analysis of the FMR fuel under normal operation including the shutdown/restarting periods for refueling. The evaluation of the fuel performance parameters, represented by temperature, internal pressure, stress, and strain, shows that the FMR fuel maintains its thermal and mechanical integrity during normal operation. Technology gaps and limitations are also discussed to guide future efforts for extending the performance analysis to transient scenarios as well as improving the fuel performance evaluation through experiments. [ABSTRACT FROM AUTHOR]

In general, electric ovens represent a low-efficiency class among home appliances, contributing to overall environmental changes in buildings and apartments. To improve their low efficiency, which is typically between 10% to 12%, industries are increasingly focused on developing effective technologies. One suitable strategy is to design and control the oven's center temperature, as specified by the EN 60350-1 European standard, which regulates the energy efficiency index (EEI) test. The present simulation study explains the transient thermo-fluid behavior of a domestic electric oven subjected to free convection, i.e., static mode. For this purpose, appropriate dynamic models are employed, intended for design and control. A lumped-parameter based methodology is considered to develop a low-order dynamic model, resulting in reduced computational cost and run time. A finite level of discretization is introduced into the model, enabling the capture of limited insights, such as temperature, heat flux, mass flow rate, pressure drop, etc., particularly at the cavity center, internal and external cavity wall surfaces, and at suction and exit openings. The electric oven is mainly divided into four sub-systems: door, cavity, ventilation, and cabinet. Each sub-system has a suitable level of discretization signifying a lumped mass parameter to reproduce the transient behavior within the electric oven. Heaters are considered as individual lumped masses and are integrated within the cavity sub-system. The above sub-systems employ both the first principle equations and correlations based on experimental data, giving a low-order grey-box identity to the system. In addition to conduction and convection, a non-linear form of radiation is considered to increase model accuracy. The developed model is further calibrated with available physical data. Once calibrated, the model is then compared with the remaining physical data produced at different heat loads to understand the accuracy in terms of transient temperature prediction at various temperature set points. • Developed a design and control model for empty cavity transient test. • Lumped parameter approach is implemented ensuring model accuracy and agility. • Model were calibrated and validated with experimental data. • All the non-linear terms were incorporated improving fidelity of model. [ABSTRACT FROM AUTHOR]

• This study considers both conduction and convection heat transfer by introducing a uniformly thick top wall. • The thermal stratification between the top and bottom walls generates thermal convection. • This study indicates a 46.91 % rise in entropy generation for Re ranging from 500 to 1000. • A decrement of 88.31 % is observed in exergy generation with the greatest amplitude in the case of the lowest heat transfer. The main focus of this article is on analyzing the entropy generation characteristics of an air-filled hexagonal thermo-fluid system with an adiabatic clockwise rotating dynamic modulator through second law analysis. This modulator rotation creates striations that affect natural convection. This convection is generated by the thermal stratification between the top and bottom walls. To fully analyze the system, the study considers both conduction and convection heat transfer by introducing a uniformly thick top wall. Overall, the study looks at the behavior of a conjugate thermo-fluid system. The system is solved numerically using non-dimensional Navier Stokes equations as a moving mesh problem by the Arbitrary Lagrangian Euler finite element method. The parameters whose effects have been conceptualized here are 102 ≤ Re ≤ 103, 104 ≤ Ra ≤ 107, and 103 ≤ Bi ≤ 104. Air is chosen to be the working fluid with P r of 0.71. Effects of these parameters are visualized by spatially averaged total entropy generation, spatially averaged total exergy generation, spatially averaged Bejan's number, and fast Fourier transform analysis. The present study indicates a 46.91 % rise in entropy generation for R e ranging from 500 to 1000. Moreover, for the same case, a decrement of 88.31 % is observed in exergy generation with the greatest amplitude in the case of the lowest heat transfer. This phenomenon is further supported by the amplitude of the fundamental frequency, where the thermodynamic configuration with the lowest heat transfer has the highest peak. As far as the authors are aware, no previous research has been conducted to analyze the entropy generation characteristics of a hexagonal conjugate transient system that involves a dynamic modulator stirring the flow. Therefore, this study represents a novel contribution to the existing literature on the subject. Present study focused on only a single type of blade irrespective of its aerodynamic design, size, or thickness. Moreover, the blade is also considered to be a rigid body that is not affected by the hoop stress generated from its own rotation. [ABSTRACT FROM AUTHOR]

The supercritical CO 2 Brayton cycle has promising prospects for application in hypersonic vehicles owing to its performance and compactness. However, the extreme thermal environment in aircrafts and limited cold sources make the transient characteristics of the Brayton cycle unclear. In this study, dynamic models of supercritical CO 2 Brayton cycle were established. The heat exchanger model was based on the supercritical moving boundary method proposed in our previous work and the finite volume method, whereas the modeling of the turbomachinery was based on the performance map approach. Proportional-integral-derivative (PID) controller modules were introduced to enable closed-loop control of various parameters to meet different working conditions. The transient characteristics of the heat exchanger and Brayton cycle model were validated using literature data. Dynamic models for both simple and recuperated layouts were developed to study the transient behavior in aerospace scenarios with sudden thermal load increases, cold-source limitations, and combined disturbances. Under the given conditions, results indicate that both sudden increases in thermal load and cold-source limitations cause a decrease in the thermodynamic performance, with a reduction in thermal efficiency of 0.7 and 2.2%, respectively. When these conditions were combined, the performance further deteriorated, with the thermal efficiency decreasing from 14.4 to 9.5%. This condition can result in compressor over speeding and failure of the PID controller. The simulation results for the two layouts show that the recuperated layout has a 34.8% higher power output at the cost of increasing the total weight by 29.7%. The dynamic models proposed in this study provide valuable insights into the behavior of Brayton cycle systems in hypersonic vehicles, aiding system design, evaluation, and control strategy development. • Transient characteristics of the supercritical CO 2 Brayton cycle need clarification. • Dynamic models used to study transient behavior in SCO 2 -CBC in aerospace scenarios. • Thermal load increases, cold-source limits, and combined disturbances considered. • Recuperated and simple layouts have contrasting advantages of cycle performance. • Valuable insights for improving the design of CBCs for hypersonic vehicles obtained. [ABSTRACT FROM AUTHOR]

• The axisymmetric and in-plane transient dynamic responses of poroelastic media are investigated. • The extended precise integration method and the integral transform theorem are applied to obtain the solution. • Various suddenly applied load forms in different coordinates are involved in the transient analysis. • Effect of transversely isotropic parameters on the dynamic behavior is discussed. Based on the integral transform theorem and the extended precise integration method (EPIM), this paper investigates the axisymmetric and in-plane transient dynamic responses of multilayered transversely isotropic (TI) poroelastic media. First, the governing equations are transformed into ordinary differential equations by virtue of the integral transform technique. It can be found that the transformed equations of the axisymmetric problem are similar to those of the in-plane problem. Then, we introduce the boundary conditions and apply the EPIM to obtain the transient dynamic solution in the transformed domain. The actual solution is further gotten by the numerical transform inversion. Various suddenly applied load forms are considered in this work, including concentrated point loads, line loads, uniform strip loads and circular loads. Several numerical examples are provided to verify the proposed theory and to investigate the differences of the transient problems in cylindrical coordinates and Cartesian coordinates. The influences of transverse isotropy and load forms on transient behaviors are also analyzed. [ABSTRACT FROM AUTHOR]